Composite material and its manufacturing method

Abstract

This composite material and its manufacturing method fall within the technical field of composite materials. The composite material includes a core and a shell covering the core. The core material has a thermal conductivity of 20 W / m·k or greater, and the shell material contains a first metal salt. The composite material satisfies the following conditions: the composite material's D501 is A, and its mass is M. The composite material is placed in a container equipped with a stirrer, stirred at 500 r / min for 10 minutes with a loading coefficient of 0.4, and then passed through a (0.1-0.3)×A sieve, with the remaining material remaining at 0.05×M or less. This compensates for defects in the core material, providing excellent aging resistance and thermal conductivity.

Description

[Technical Field]

[0001] This application relates to the technical field of composite materials, and more particularly to composite materials and methods for their manufacture.

[0002] Cross-reference to related applications This application claims priority from a Chinese application bearing application number 202310007419.9 and entitled "Composite material and manufacturing method thereof," filed with the China Patent Office on January 4, 2023, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Thermally conductive fillers are added to substrates (such as various thermally conductive adhesive substrates) to increase the thermal conductivity of the material. Typical thermally conductive fillers include aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon carbide, etc. Thermally conductive fillers are usually in powder form, and the thermal conductivity of the material can be increased by adding one type of powder or two or more types of powder to the substrate.

[0004] However, using a single material powder as a thermally conductive filler usually has drawbacks. For example, silicon carbide is a semiconductor material and has poor insulating properties. When a thermally conductive composite material formed by adding silicon carbide as a thermally conductive filler to a substrate is used in an electrical appliance, the operation of the electrical appliance may be adversely affected. Furthermore, for example, aluminum nitride has poor hydrolytic stability. When a thermally conductive composite material formed by adding aluminum nitride as a thermally conductive filler to a substrate is used in a high-humidity environment, its performance may be adversely affected. Furthermore, for example, silicon nitride has very high hardness. When a thermally conductive composite material formed by adding silicon nitride as a thermally conductive filler to a substrate is used, the silicon nitride may cause wear on other devices that come into contact with it, shortening the service life of the device.

[0005] The Chinese patent application CN105419301A relates to a composite thermally conductive filler and its manufacturing method. One type of highly thermally conductive powder serves as the shell of a composite powder, while another type of powder serves as the core. The two are physically integrated to produce a composite powder, which then forms a thermally conductive filler. Shell materials include ceramic materials such as nitrides, borides, oxides, silicides, carbides, and composite oxides (water and metal silicates). These materials have excellent thermal conductivity and dielectric properties. Core materials include inorganic materials such as graphite, oxides, and glass. These materials must be thermally conductive but not necessarily insulating. The selection of different shell and core materials aims to achieve at least one of the following objectives: (1) The outer layer has high thermal conductivity and insulating properties, while the core has high thermal conductivity and electrical conductivity. The insulating properties of the shell block the electrical conductivity of the core in the resulting composite powder. When this material is added to a substrate as a filler, thermal conduction paths are formed between the particles, while the dielectric properties of the shell block the conductive paths of the core. As a result, the composite filler has only thermal conductivity and no electrical conductivity. A typical example is a structure in which graphite is coated with HBN. (2) The shell material has high thermal conductivity and insulating properties, while the core material has insulating properties but not high thermal conductivity. This structure is inexpensive. In the formed composite powder, the core increases the volume. Therefore, for the same volumetric filling rate, the amount of shell material used can be reduced, achieving high thermal conductivity at low cost. A typical example is a coating of Al2O3 and glass with HBN. (3) It improves the physical properties of thermally conductive materials, reducing viscosity and hardness. This contributes to the use of thermally conductive materials, increasing the filling rate, and improving thermal conductivity. A typical example is a coating of graphite with HBN. (4) Composite fillers can achieve desired effects in color, thermal expansion coefficient, wettability, corrosion resistance, etc. by combining the shell and core.

[0006] For example, the physical integration process for composite materials (those in which graphite is coated with HBN) typically involves mixing a core of graphite, a shell of HBN, and a consolidating agent (e.g., a binder), adhering the shell of HBN to the surface of the core of the graphite using the consolidating agent, and forming a structure in which the surface of the core of the graphite is coated with the shell of HBN. However, through research by the inventors, we have found that a material obtained by mixing the core-shell structure formed by such a physical integration process with a substrate still has relatively strong electrical conductivity, which adversely affects thermal conductivity, and does not eliminate the deficiencies in the electrical conductivity of the core of the graphite. Summary of the Invention

[0007] The present embodiment has been made in consideration of the deficiencies of the conventional technology, and provides a composite material and a manufacturing method thereof that can overcome the deficiencies of a single thermally conductive filler and has excellent aging resistance.

[0008] In a first aspect, an embodiment of the present application provides a composite material. The composite material includes a core and a shell coating the outside of the core, wherein the core material has a thermal conductivity of 20 W / m·k or more, and the shell material includes a first metal salt. The composite material satisfies the following conditions: where A is the D501 of the composite material, a mass of M of the composite material is placed in a container equipped with a stirrer and stirred for 10 minutes under conditions of a loading coefficient of 0.4 and 500 r / min, and then passed through a (0.1 to 0.3)×A sieve, with the amount of material remaining under the sieve being 0.05×M or less.

[0009] In the above technology, the core material has a thermal conductivity of 20 W / m·k or higher. The high thermal conductivity of the composite obtained by combining the core and shell contributes to its use as a thermally conductive filler. Furthermore, the metal salt shell can compensate for some of the defects of the individual core material. Because the composite is processed under stirring conditions with very little residue, the shell and core materials are tightly bonded together, making them less likely to separate. This results in a low viscosity thermally conductive composite, which effectively compensates for defects in the core material and has good aging resistance.

[0010] In a second aspect, the present invention provides a composite material comprising a core and a shell covering the outside of the core, wherein the core material has a thermal conductivity of 20 W / m·k or more, and the shell material comprises a first metal salt obtained by sintering.

[0011] In the above technical form, the core material has a thermal conductivity of 20 W / m·k or more, and the composite material obtained by combining the core and shell has a high thermal conductivity, making it suitable for use as a thermally conductive filler. Furthermore, the metal salt shell is obtained by sintering, and during the sintering process, at least a portion of the shell material mass-transfers to the core surface, resulting in a shell material with excellent coating effect. The thermally conductive mixed material formed by adding this composite material as a filler to a substrate can compensate for defects in the core material and has good aging resistance. Furthermore, the low viscosity of the thermally conductive mixed material allows it to be uniformly dispersed in the thermally conductive mixed material, providing an excellent effect of compensating for defects in the core material.

[0012] In a third aspect, the present invention provides a composite material comprising a core and a shell coating the outside of the core, the shell material comprising a first metal salt, the core material having a thermal conductivity of 20 W / m·k or more, at least one element in the core material being the same as at least one element in the shell material, and a transition layer between the core and the shell, in which the content of the at least one element in the transition layer gradually decreases and the content of the at least one element in the transition layer gradually increases from the outside to the inside.

[0013] In the above technical form, the core material has a thermal conductivity of 20 W / m·k or more, and the composite obtained by combining the core and shell has a high thermal conductivity, making it suitable for use as a thermally conductive filler. Furthermore, the metal salt shell is obtained by sintering, during which some of the core material reacts with the shell raw material to form the shell material. This results in at least one element in the core material becoming identical to at least one element in the shell material, creating a transition layer between the core and shell. As the core material and shell raw material react during the sintering process, one element gradually increases and the other element gradually decreases in the transition layer. The thermally conductive composite formed by adding this composite material as a filler to a substrate can compensate for defects in the core material and has good aging resistance. Furthermore, the low viscosity of the thermally conductive composite allows it to be uniformly dispersed in the thermally conductive composite, thereby effectively compensating for defects in the core material.

[0014] In one possible embodiment, the composite material satisfies the following conditions: D501 of the composite material is A, and the composite material having a mass M is placed in a container equipped with a stirrer, stirred for 10 minutes under conditions of a loading coefficient of 0.4 and 500 r / min, and then passed through a sieve of (0.1 to 0.3) × A, with the amount of material remaining under the sieve being 0.02 × M or less.

[0015] In the above technical form, the bonding effect between the two is further improved, and the resulting composite material is added to the substrate as a thermally conductive filler to form a thermally conductive mixed material, which has a lower viscosity and is more effective in compensating for defects in the core.

[0016] In one possible embodiment, there is no gap between the core and the shell, which makes it difficult for the core to separate from the shell during the process of adding this to the substrate to form a thermally conductive composite, and reduces the viscosity of the thermally conductive composite.

[0017] In one possible embodiment, the shell is a complete shell, which uniformly covers the core surface and does not detach even when subjected to an external force.

[0018] In one possible embodiment, the shell is a continuous coating layer. Because the shell uniformly covers the core surface, the shell does not come off even when subjected to an external force.

[0019] In one possible embodiment, the composite material does not contain a binder, which avoids the influence of the binder on the performance of the composite material and provides better bonding performance between the shell and the core.

[0020] In one possible embodiment, the shell is not formed by an agglomeration of multiple particles adhered to the surface of the core. If the shell is formed by an agglomeration of multiple particles adhered to the surface of the core, some of the shell particles will easily detach from the core. Adding such a material to the base material will likely result in two independent types of thermally conductive powder being added to the base material, resulting in a deterioration in the performance of the thermally conductive composite material. In contrast, in the present application, the shell is less likely to detach from the core, resulting in better performance of the thermally conductive composite material.

[0021] In one possible embodiment, the crystal grains of the core are directly connected to the crystal grains of the shell. The metal salt shell is obtained by sintering, during which the core material reacts with the shell material to form the shell material. This directly connects the microscopic crystal grains between the shell and the core, and the shell is tightly connected to the outside of the core. Therefore, the inorganic composite filler has excellent performance, and adding such a filler to the base material improves the performance of the thermally conductive composite material.

[0022] In one possible embodiment, the shell covers at least 85% of the surface of the core. Since most of the surface of the core is covered with the shell material, the presence of the shell can compensate for defects in the core material.

[0023] In one possible embodiment, the shell completely covers the core: since the entire surface of the core is covered with the shell material, the shell can better compensate for the defects of the core material.

[0024] In one possible embodiment, the mass ratio of the core is 95% or less, and at least 5% of the shell is located on the surface of the core, which can compensate for some defects in the core material.

[0025] In one possible embodiment, the mass ratio of the core is 30% to 95%. The core increases the thermal conductivity of the composite material, and the shell can compensate for defects in the core material.

[0026] In one possible embodiment, the mass ratio of the core is 55% to 80%. The composite material combines the performance of the core and the shell, and has excellent overall performance.

[0027] In one possible embodiment, the mass ratio of the core is 60% to 75%.

[0028] In one possible embodiment, the thermal conductivity of the core material is between 20 W / m·k and 500 W / m·k. If a material with a high thermal conductivity is used as the core, the thermal conductivity of the final composite material will also be high.

[0029] In one possible embodiment, the thermal conductivity of the core material is between 50 W / m·k and 250 W / m·k.

[0030] In one possible embodiment, at least one element of the core material is the same as at least one element of the first metal salt. During the process of forming the shell by sintering, the surface layer of the core reacts to form the shell metal salt, so that at least one element of the core becomes the same as at least one element of the first metal salt. This strengthens the bond between the core material and the shell material, and also improves the adaptability of the material and the effect of compensating for defects in the core material.

[0031] In one possible embodiment, the core is a semiconducting material and the shell is an insulating material. A thermally conductive composite formed by adding a semiconducting thermally conductive filler to a substrate has poor insulating properties in the resulting heat dissipation layer, which can have adverse effects when applied to electrical products. By tightly covering the outside of the core with an insulating shell, the insulating material can compensate for the electrical performance deficiencies of the semiconducting material in the core, thereby increasing the thermal conductivity and breakdown voltage of the composite.

[0032] In one possible embodiment, the core material is silicon carbide, and the first metal salt is metal silicate.The metal silicate tightly coats the surface of silicon carbide.Metal silicate has certain thermal conductivity and high insulating properties, so the thermal conductivity and breakdown voltage of the composite material are both high, and the insulating properties are also excellent.In addition, since both the shell and the core contain silicon, the consistency of the composite material is better, and the effects of thermal conductivity and insulating properties are both good.

[0033] In one possible embodiment, silicon carbide is the primary particle, and the primary particle has fewer boundaries, which results in a higher heat conduction efficiency and a better thermal conductivity of the composite material.

[0034] In one possible embodiment, the core material has a Mohs hardness of 7 to 10. When a thermally conductive mixed material is formed by adding a material with high hardness to a substrate, the resulting heat dissipation layer comes into contact with a device and is prone to abrasion of the device. By tightly coating the outside of the hard core with a metal salt material, the hardness of the material can be reduced, and abrasion of the thermally conductive filler to the device can be prevented to some extent.

[0035] In one possible embodiment, the core material is silicon nitride, and the first metal salt is a metal silicate. Because silicon nitride has high hardness and high thermal conductivity, the outer surface of the silicon nitride is tightly coated with a metal silicate, thereby reducing the hardness of the composite material and ensuring thermal conductivity. In addition, because both the shell and the core contain silicon, the composite material has better conformity, excellent thermal conductivity, and low hardness.

[0036] In one possible embodiment, the metal silicate includes at least one of magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium silicate zirconate, aluminum silicate zirconate, and zinc silicate zirconate. The metal silicate is formed by chemically reacting the shell material on the core surface with the core (silicon nitride or silicon carbide) through sintering. This allows the formation of a composite material with better overall performance, and when added to a substrate, it combines low viscosity, high thermal conductivity, low hardness, and insulation properties.

[0037] In one possible embodiment, the core material is silicon carbide, the shell material further comprises a second metal salt containing at least two metal elements and no silicon, and the mass ratio of the metal silicate in the shell material is 10% or more. Because the second metal salt is an insulating material with better thermal conductivity, the metal silicate shell completely covers the core, and the composite material has high thermal conductivity and insulating properties.

[0038] In one possible embodiment, the mass proportion of the metal silicate in the shell material is 20% to 90%.

[0039] In one possible embodiment, the second metal salt is an aluminate and / or zirconate, which provides good thermal conductivity and high electrical insulation.

[0040] In one possible embodiment, the second metal salt comprises at least one of zinc aluminate, magnesium aluminate, calcium aluminate, potassium aluminate, zinc zirconate, magnesium zirconate, calcium aluminate, and potassium aluminate. A shell material containing two of the above metal salts can be formed by sintering, and when combined with the above metal silicate, the composite material has better performance.

[0041] In one possible embodiment, the mass proportion of metal silicate in the shell material is 100%.

[0042] In one possible embodiment, the composite material has a D501 of 100 μm to 150 μm, the core material is silicon carbide, and the shell material is magnesium silicate. The composite material satisfies the following conditions: 4.8 parts by weight of vinyl silicone oil with a viscosity of 100 mpa.s, 20 parts by weight of the composite material, 21 parts by weight of spherical alumina NSM-1S, 30 parts by weight of spherical alumina BAK-10, and 25 parts by weight of spherical alumina BAK-120 are mixed, and the mixture is first treated under conditions of a rotation speed of 1100 r / min and a vacuum degree of 1000 Pa for 1 minute, and then treated under conditions of a rotation speed of 1500 r / min and a vacuum degree of 40 Pa for 1 minute. The mixture is then sintered at 25°C for 0.1 to 100 s using an Anton Paar rheometer. -1 Under the condition of 1s -1 When the viscosity is measured, it is 1×10 6 mpa·s~1.6×10 6 Obtain viscosity in mpa·s.

[0043] In the above technical form, the composite material in which the core is silicon carbide and the shell is magnesium silicate has a viscosity within the above range, and has high thermal conductivity and breakdown voltage, resulting in excellent overall performance.

[0044] In one possible embodiment, the core material is silicon carbide and the shell material is metal silicate. The composite material satisfies the following conditions: EDS measurement is performed on the composite material, and an EDS line scan is performed from the shell to the core. The obtained EDS curves of silicon, oxygen, and metal elements are all continuous lines, and the silicon content increases sharply in the middle of the curve, the oxygen content decreases sharply in the middle of the curve, and the metal element content decreases sharply in the middle of the curve.

[0045] In the above technical form, the EDS curve of the silicon between the core and the shell is continuous, which means that there is essentially no gap between the core and the shell, and the silicon content increases sharply in the middle of the curve, which means that the core material is different from the shell material, and the composite material that meets the above conditions has high thermal conductivity and breakdown voltage. That is, the silicon content of the core component is higher than that of the shell, and the metal element and oxygen content of the shell component is higher than that of the core. The content characteristics of these elements are highly consistent with the core and shell reactive raw materials and manufacturing process.

[0046] In one possible embodiment, the core material is silicon carbide, the shell material is magnesium silicate, and the composite material satisfies the following conditions: XPS measurement is performed on the composite material, and peak fitting is performed to find that the composite material contains Si-C bonds with bond energies of 100 eV to 101 eV and O-Si-O bonds with bond energies of 105 eV to 106 eV in a spectroscopic diagram based on Si2p, and Mg-O-Si bonds with bond energies of 1305 eV to 1307 eV in a spectroscopic diagram based on Mg1s.

[0047] In one possible embodiment, the core material is silicon carbide, the shell material is zinc silicate, and the composite material satisfies the following conditions: XPS measurement is performed on the composite material, and peak fitting is performed to find that the composite material contains Si-C bonds with bond energies of 100 eV to 101 eV and O-Si-O bonds with bond energies of 105 eV to 106 eV in a spectroscopic diagram based on Si2p, and Zn-O-Si bonds with bond energies of 1022 eV to 1045 eV in a spectroscopic diagram based on Zn1s.

[0048] In one possible embodiment, the core material is aluminum nitride and the shell material includes an aluminate. When aluminum nitride is added as a thermally conductive filler to a substrate to form a thermally conductive composite, the resulting heat dissipation layer is prone to hydrolysis of the thermally conductive filler, resulting in poor thermal conductivity when used in a high-humidity environment. Coating the outside of the core with an aluminate can somewhat prevent the hydrolysis of aluminum nitride, improving the thermal conductivity of the composite and improving its hydrolytic stability. Furthermore, both the shell and core contain aluminum. During sintering, some of the aluminum nitride reacts to form aluminate, improving both the thermal conductivity and hydrolytic stability of the composite.

[0049] In one possible embodiment, the aluminate includes at least one of magnesium aluminate, zinc aluminate, calcium aluminate, potassium aluminate, and aluminum silicate. This aluminate can be formed by chemically reacting the shell material on the core surface with the core (aluminum nitride) through sintering. This results in a composite material with better overall performance, and the thermally conductive mixed material formed by adding such a material to the substrate has low viscosity, high thermal conductivity, and excellent hydrolytic stability.

[0050] In one possible embodiment, the D501 of the composite material is 0.5 μm or more, which can contribute to the formation of a core-shell structure.

[0051] In one possible embodiment, the D501 of the composite material is 0.5 μm to 1000 μm, which, when added to a substrate as a thermally conductive filler, results in a product with higher thermal conductivity.

[0052] In one possible embodiment, the composite material has a D501 of 0.5 μm to 500 μm, which allows it to be applied to almost any substrate.

[0053] In one possible embodiment, the composite material has a D501 of 0.5 μm to 150 μm, and satisfies 0.5≦(D901−D101) / D501≦1.5. The particle size of such a composite material is appropriate and has good uniformity. Therefore, when added to a substrate as a thermally conductive filler, the thermally conductive filler is less likely to aggregate, resulting in more uniform dispersion.

[0054] In one possible embodiment, the composite material has a D501 of 20 μm to 150 μm and satisfies 0.6≦(D901−D101) / D501≦1.5, which allows it to be used as a coarse powder for a thermally conductive filler.

[0055] In one possible embodiment, the composite material has a D501 of 40 μm to 150 μm, and satisfies 0.6≦(D901−D101) / D501≦1.

[0056] In one possible embodiment, the composite material has a D501 of 0.5 μm to 20 μm and satisfies 0.5≦(D901−D101) / D501≦1, which allows it to be used as a fine powder for a thermally conductive filler.

[0057] In one possible embodiment, the ratio of the shell thickness to the particle size of the composite material is 0.02 to 0.1, and this relative thickness of the shell is appropriate, which allows the composite material to have high thermal conductivity and to compensate to some extent for the defects of the core material.

[0058] In one possible embodiment, the ratio of the shell thickness to the particle size of the composite material is 0.04 to 0.07, which further improves the overall performance of the composite material.

[0059] In one possible embodiment, the composite has a tap density of 1.85 g / m 3 That's all. The high tap density of the composite material increases its thermal conductivity, and it has an excellent effect of compensating for defects in the core material.

[0060] In one possible embodiment, the composite has a tap density of 1.85 g / m 3 ~2.30g / m 3 is.

[0061] In one possible embodiment, the composite has a tap density of 1.90 g / m 3 ~2.30g / m 3 If the tap density of the composite material is kept within this range, its thermal conductivity will be higher and the effect of compensating for the defects of the core material will be better.

[0062] In one possible embodiment, the specific surface area of ​​the composite material is 4 m 2 / g or less. The low specific surface area of ​​the composite material increases its thermal conductivity and is effective in compensating for defects in the core material.

[0063] In one possible embodiment, the specific surface area of ​​the composite material is 0.04 m 2 / g~4m 2 / g.

[0064] In one possible embodiment, the D501 of the composite material is 40 μm to 150 μm, and the specific surface area of ​​the composite material is 0.04 m 2 / g~0.06m 2 / g. Because the specific surface area of ​​the coarse powder is low, the composite effect between the core and shell is better, and the shell material is more uniform. When the shell is complete, the thermal conductivity of the composite material is higher and the effect of filling the defects of the core material is also better.

[0065] In a fourth aspect, the present invention provides a method for producing a composite material, the method including: forming a precursor by coating a surface of a core with a shell material; and sintering the precursor to allow at least a portion of the shell material to mass transfer to the surface of the core to form a shell containing a first metal salt, thereby obtaining a composite material, wherein the core material has a thermal conductivity of 20 W / m·k or more.

[0066] In the above technical form, during the sintering process of the precursor, the shell material undergoes mass transfer to the core surface, resulting in a shell containing metal salts that uniformly covers the core surface, with essentially no gaps between the shell and core. This results in superior performance of the composite material obtained after sintering, compensates for some defects in the core material, and improves aging resistance. Furthermore, the core material has a thermal conductivity of 20 W / m·k or higher. The high thermal conductivity of the composite material obtained after sintering to form the shell contributes to its application as a thermally conductive filler.

[0067] In one possible embodiment, the tap density of the core is 1.90 g / m 3 That's all. Because the tap density of the core is high, the composite effect of the core and the shell is better, the thermal conductivity is higher, and a composite material with a better effect of compensating for the defects of the core is obtained.

[0068] In one possible embodiment, the tap density of the core is 1.90 g / m 3 ~2.4g / m 3 This results in a composite material with higher thermal conductivity and better ability to compensate for core defects.

[0069] In one possible embodiment, the thermal conductivity of the core material is between 20 W / m·k and 500 W / m·k. Using a material with a higher thermal conductivity as the core will result in a higher thermal conductivity of the final composite material.

[0070] In one possible embodiment, the thermal conductivity of the core material is between 50 W / m·k and 250 W / m·k.

[0071] In one possible embodiment, the D502 of the shell raw material is 0.05 μm to 10 μm, and the D503 of the core material is 0.5 μm to 1000 μm, and the relationship 0.00001≦D502 / D503≦0.1 is satisfied. The shell raw material with a small particle size can easily coat the surface of the core material, which contributes to the formation of a core-shell structure with a uniform coating by subsequent sintering.

[0072] In one possible embodiment, the D503 of the core material is 0.5 μm to 500 μm, and satisfies 0.0001≦D502 / D503≦0.1. The combination of core and shell materials that satisfies this condition provides a better coating effect on the precursor, which contributes to the subsequent formation of a more uniform shell, improving the overall performance of the composite material.

[0073] In one possible embodiment, the D503 of the core material is 0.5 μm to 140 μm, and satisfies 0.0003≦D502 / D503≦0.1. By combining the core material and the shell material that satisfy this condition, the resulting composite material can be easily added to a substrate as a thermally conductive filler, contributing to applications in the field of thermal conductivity.

[0074] In one possible embodiment, the mass ratio of the shell raw material in the precursor is 1% to 30%, which allows a better shell to be formed by sintering and to some extent prevents the impact on thermal conductivity caused by an excessively thick shell.

[0075] In one possible embodiment, the mass ratio of the shell material in the precursor is 5% to 20%, which allows the shell to completely cover the core, avoiding an excessively thick shell, improving the thermal conductivity of the composite material, and better compensating for defects in the core material.

[0076] In one possible embodiment, the core material is silicon nitride or silicon carbide, and the shell raw material comprises at least one of magnesium, magnesium oxide, magnesium hydroxide, organomagnesium, zinc, zinc oxide, zinc hydroxide, organozinc, zirconium, zirconium oxide, zirconium hydroxide, and organozirconium, and upon sintering, at least a portion of the shell raw material reacts and mass transfers with the core to form a shell containing the first metal salt.

[0077] In the above technical form, the core material chemically reacts with the shell raw material, and SiO produced in the core migrates to the outer layer and reacts with the shell raw material to form silicates. This results in magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium silicate zirconate, aluminum silicate zirconate, zinc silicate, etc. This results in the formation of a metal silicate shell on the surface of the core, i.e., in situ, which improves the thermal conductivity of the composite material, as well as its excellent electrical insulation (composite material with a silicon carbide core) and low hardness (composite material with a silicon nitride core).

[0078] In one possible embodiment, the shell raw material includes at least one of magnesium, magnesium oxide, magnesium hydroxide, aluminum, aluminum oxide, aluminum hydroxide, zinc, zinc oxide, zinc hydroxide, zirconium, zirconium oxide, and zirconium hydroxide. The above shell raw materials are easily available and can easily react with silicon nitride or silicon carbide under sintering conditions to obtain a shell material.

[0079] In one possible embodiment, the shell raw material is at least one of magnesium oxide, aluminum oxide, zinc oxide, and zirconium oxide. When a metal oxide is used as the shell raw material, it can easily react with silicon nitride or silicon carbide to form a metal silicate. When two or more metal oxides are used as the shell raw material, a shell material containing a second metal salt in addition to the metal silicate can be formed, resulting in a shell containing multiple materials and improving the performance of the composite material.

[0080] In one possible embodiment, sintering is carried out at a temperature of 1000° C. to 1400° C. for 3 to 8 hours.

[0081] In one possible embodiment, sintering is carried out at a temperature of 1300° C. to 1400° C. for 3 to 8 hours.

[0082] In one possible embodiment, the core material is silicon carbide, and the silicon carbide is the primary particle. The primary particle has fewer boundaries, which results in higher heat conduction efficiency and better thermal conductivity of the composite material.

[0083] In one possible embodiment, the core material is aluminum nitride and the shell raw materials include at least one of zinc oxide, magnesium oxide, calcium oxide, potassium oxide, and silicon oxide. Upon sintering, at least a portion of the shell raw materials react and mass transfer with the core to form a shell containing the first metal salt.

[0084] In the above technical form, the surface of the core and the shell raw material are chemically reacted by sintering, and AlO produced from the core moves to the outer layer and reacts with the shell raw material to form aluminates. The shell material includes at least one of magnesium aluminate, zinc aluminate, calcium aluminate, potassium aluminate, and aluminum silicate.

[0085] In one possible embodiment, sintering is carried out at a temperature of 1400° C. to 1800° C. for 3 to 8 hours.

[0086] In one possible embodiment, the shell raw material comprises a hydrous silicate. Upon sintering, at least a portion of the hydrous silicate melts and mass transfers to the surface of the core, forming a silicate-containing shell.

[0087] In the above-mentioned technical form, during the sintering process, the shell material melts and becomes fluid, and the molten shell material mass-transfers to the core surface, converting the hydrous silicate into silicate, thereby obtaining a composite material with good coating effect, which can well compensate for the defects of the core material and has better overall performance.

[0088] In one possible embodiment, the hydrous silicate is one or more of hydrous magnesium silicate, hydrous sodium silicate, hydrous sodium aluminosilicate, and hydrous calcium aluminosilicate.

[0089] In one possible embodiment, sintering is carried out at a temperature higher than the melting point of at least a portion of the hydrous silicate for 3 to 8 hours.

[0090] In one possible embodiment, the method for forming the precursor includes mixing a core, a shell material, and a coating aid, and then coating the mixture. By using the coating aid to coat, the shell material is uniformly adhered to the surface of the core, and during the sintering process, the shell material undergoes mass transfer, and finally, a relatively complete coating shell is formed, and the shell coats the surface of the core more uniformly.

[0091] In one possible embodiment, the core material is silicon nitride or silicon carbide, and the coating agent is a silicon-containing coating agent, which allows the shell raw material to react with the core material and the coating agent at the same time, resulting in a more uniform coating, a better coating effect, a product that is less likely to agglomerate, and better thermal conductivity of the composite material.

[0092] In one possible embodiment, the coating aid comprises tetraethyl orthosilicate, which can be used as a coating aid while also providing silicon, so that the shell raw material reacts with the core material and the tetraethyl orthosilicate at the same time, ultimately obtaining the shell material.

[0093] In one possible embodiment, the mass ratio of the coating aid in the precursor is 1% to 15%, which improves the coating effect and prevents the performance of the composite material from being affected by excessive use of the coating aid.

[0094] In one possible embodiment, the mass ratio of the coating aid in the precursor is 3% to 10%.

[0095] In one possible embodiment, the coating is performed using a wet ball mill, with the rotation speed of the wet ball mill being 200 r / min to 600 r / min, and the wet ball milling time being 1 hour or more. By using a wet ball mill for coating, the shell raw material can work together with the coating aid to more uniformly coat the core surface, and core agglomeration that occurs during the raw material coating process can be avoided.

[0096] In one possible embodiment, the rotation speed of the wet ball mill is 300 r / min to 500 r / min, and the wet ball milling time is 1 hour to 6 hours.

[0097] In order to more clearly explain the technology of the embodiments in the present application, the drawings necessary for the description of the embodiments will be briefly described below. The drawings described only show some embodiments of the present application and do not limit the scope. Those skilled in the art can obtain other related drawings based on these drawings without using inventive ability. [Brief explanation of the drawings]

[0098] [Figure 1] FIG. 1 is a schematic diagram showing the structure of a composite material according to an embodiment of the present invention. [Figure 2]FIG. 2 is a flow chart of a process for manufacturing a composite material according to an embodiment of the present invention. [Figure 3] FIG. 3 is an SEM image (magnified 200 times) of the precursor of Example R1 of the present application. [Figure 4] FIG. 4 is an SEM image (magnified 200 times) of the composite material of Example R1 of the present application. [Figure 5] FIG. 5 is an SEM image (magnified 500 times) of the precursor of Example R21 of the present application. [Figure 6] FIG. 6 is an SEM image (magnified 500 times) of the composite material of Example R21 of the present application. [Figure 7] FIG. 7 is an SEM image (magnified 2000 times) of the composite material of Example R28 of the present application. [Figure 8] FIG. 8 is an SEM image (magnified 2000 times) of the composite material of Example R33 of the present application. [Figure 9] FIG. 9 is an XRD diagram of the precursor of Example R1 of the present application. [Figure 10] FIG. 10 is an XRD diagram of the composite material of Example R1 of the present application. [Figure 11] FIG. 11 is an XRD diagram of the precursor of Example R21 of the present application. [Figure 12] FIG. 12 is an XRD diagram of the composite material of Example R21 of the present application. [Figure 13] FIG. 13 is an XPS Si2p spectroscopic analysis diagram of the precursor of Example R1 of the present application. [Figure 14] FIG. 14 is an XPS Si2p spectroscopic analysis diagram of the composite material of Example R1 of the present application. [Figure 15] FIG. 15 is an XPS Mg1s spectroscopic analysis diagram of the precursor of Example R1 of the present application. [Figure 16] FIG. 16 is an XPS Mg1s spectroscopic analysis diagram of the composite material of Example R1 of the present invention. [Figure 17] FIG. 17 is an XPS Si2p spectroscopic analysis diagram of the precursor of Example R21 of the present application. [Figure 18] FIG. 18 shows the XPS Si2p spectroscopic analysis of the composite material of Example R21 of the present invention. [Figure 19]FIG. 19 is an XPS Mg1s spectroscopic analysis diagram of the precursor of Example R21 of the present invention. [Figure 20] FIG. 20 is an XPS Mg1s spectroscopic analysis diagram of the composite material of Example R21 of the present application. [Figure 21] FIG. 21 shows the EDS line scan direction of the precursor of Example R21 of the present invention. [Figure 22] FIG. 22 is an EDS line scan of the precursor of Example R21 of the present invention. [Figure 23] FIG. 23 is an EDS line scan of the precursor carbon of Example R21 of the present application. [Figure 24] FIG. 24 is an EDS line scan of the silicon precursor of Example R21 of the present application. [Figure 25] FIG. 25 is a diagram showing the EDS line scan direction of the composite material of Example R21 of the present application. [Figure 26] FIG. 26 is an EDS line scan image of the composite material of Example R21 of the present application. [Figure 27] FIG. 27 is a carbon EDS line scan diagram of the composite material of Example R21 of the present application. [Figure 28] FIG. 28 is a silicon EDS line scan image of the composite material of Example R21 of the present application. [Figure 29] FIG. 29 is an oxygen EDS line scan image of the composite material of Example R21 of the present application. [Figure 30] FIG. 30 is a zinc EDS line scan image of the composite material of Example R21 of the present application. [Figure 31] FIG. 31 is an SEM image (magnified 6400 times) of the composite material of Example R1 of the present invention after cutting. [Figure 32] FIG. 32 is an SEM image (magnified 6400 times) of the composite material of Example R21 of the present invention after cutting. [Figure 33] FIG. 33 is an SEM image (magnified 60,000 times) of the composite material of Example R1 of the present invention after cutting. DETAILED DESCRIPTION OF THE INVENTION

[0099] Through research by the inventors, it was discovered that when a thermally conductive filler formed by physical integration, for example a core-shell structure in which the core is silicon carbide and the shell is magnesium silicate, is added to vinyl silicone oil to form a silica gel mixture, and the silica gel mixture is then solidified to form a layered structure, the thermal conductivity is significantly reduced and the breakdown voltage is not substantially increased (compared to the layered structure after solidification of a silica gel mixture formed by adding silicon carbide alone to vinyl silicone oil).

[0100] Through research by the inventors, it was discovered that the reason for this is that when a thermally conductive filler with a core-shell structure (silicon carbide as the core and magnesium silicate as the shell) formed by physical integration is added to vinyl silicone oil, both the thermal conductivity and insulating properties of the silica gel layer after the silica gel mixture has solidified are poor.

[0101] Therefore, the inventors investigated the use of in situ reactions to form a shell to enhance the thermal conductivity and insulating properties of the silica gel layer after solidification of a silica gel mixture formed by adding a composite material to silica gel. The inventors sintered silicon carbide in an air atmosphere at 1300°C for two hours, reacting the surface layer of the silicon carbide shell with oxygen gas to obtain silicon dioxide, resulting in a composite thermally conductive filler in which the silicon carbide is coated with silicon dioxide. The inventors also added the resulting composite thermally conductive filler to vinyl silicone oil, uniformly mixed it with the vinyl silicone oil to form a silica gel mixture, and solidified the silica gel mixture to form a silica gel layer. The thermal conductivity and breakdown voltage of the formed silica gel layer were measured, and it was found that the thermal conductivity was significantly reduced and the breakdown voltage was not significantly increased (compared to the layered structure after solidification of a silica gel mixture formed by adding silicon carbide alone to vinyl silicone oil).

[0102] Through further research, the inventors discovered that when silicon carbide is sintered in a high-temperature oxygen atmosphere, the surfaces of the silicon carbide particles are oxidized and corroded, destroying the particle structure. The reason for this is as follows: Silicon carbide particles are obtained by pulverization, resulting in an uneven surface. When exposed to air, the reaction speed between oxygen gas and the protruding portions of the surface is faster than the reaction speed between oxygen gas and the recessed portions of the surface. This prevents the formation of a shell that adequately covers the silicon carbide surface, and instead results in the formation of silicon dioxide particles on the protruding surfaces of the silicon carbide. This reduces the properties of the composite thermally conductive filler.

[0103] In view of the above problems, the inventors have developed a new composite material with a core-shell structure in which the shell can compensate for defects in the core to some extent. This composite material is added to a substrate as a thermally conductive filler to form a thermally conductive mixed material. After solidification, the layered structure has high thermal conductivity, compensates for defects in the core, and has good aging resistance.

[0104] composite material FIG. 1 is a schematic diagram of a composite material 100 according to an embodiment of the present invention. As shown in FIG. 1, the composite material 100 has a core 110 and a shell 120 that covers the outside of the core 110. The thermal conductivity of the core material is 20 W / m·k or more, and the shell material contains a first metal salt. The composite material 100 satisfies the following conditions: D501 is A, and the composite material 100 has a mass M. The composite material 100 is placed in a container equipped with a stirrer, stirred for 10 minutes under conditions of a loading coefficient of 0.4 and 500 r / min, and passed through a sieve of (0.1 to 0.3) × A, with the amount of material that falls under the sieve being 0.05 × M or less.

[0105] The composite material 100 has a particle structure. The shape of the composite material 100 may be a highly spherical particle as shown in FIG. 1, a non-spherical particle, or an irregular particle, but is not limited thereto in the present application. The core 110 of the composite material 100 refers to the core 110 of the particle, and the shell 120 of the composite material 100 refers to the shell 120 of the particle. As can be seen from FIG. 1, there is no obvious gap between the core 110 and the shell 120. Furthermore, the material of the core 110 (single material or composite material) is different from the material of the shell 120 (single material or composite material).

[0106] The principle of measuring the thermal properties of core materials using the transient plane heat source method is based on the transient temperature response generated by a stepped heated disk heat source in an infinite medium. A planar probe made of a thermally resistive material serves as both the heat source and the temperature sensor. Nickel's thermal resistance coefficient, i.e., the relationship between temperature and resistance, exhibits a linear change. This means that heat loss can be determined based on the change in resistance, which reflects the thermal conductivity of the sample. The hot disk probe is a continuous double-helix sheet formed by etching nickel, a conductive metal. The outer layer is a two-layer protective layer made of polyimide (Kapton) with a thickness of 0.025 mm, which provides the probe with a certain mechanical strength and electrical insulation from the sample. The probe is placed in the center of the sample during measurement. When a current passes through the nickel, a certain temperature rise occurs, and the generated heat simultaneously diffuses to the sample on both sides of the probe. The rate of heat diffusion depends on the thermal conductivity properties of the material. By recording the temperature and the response time of the probe, the thermal conductivity and thermal diffusivity can be directly obtained from a mathematical model, and the volumetric specific heat can be calculated from the ratio of the two. During the initial test, a small temperature drop occurs in the Kapton coating, and after a while, the temperature drop becomes constant as the output becomes constant. The change in resistance of the probe can be expressed as follows:

[0107] Formula (1) R(t)=Ro[1+α△Ti+α△T(τ)] Where Ro: Resistance of probe before instantaneous recording α: Temperature coefficient of resistance (TCR) △Ti: Temperature difference of the film protective layer (because the protective layer is very thin, △Ti can be considered a constant within a short period of time) △T(τ): Average temperature rise of the probe when it is in ideal and complete contact with the sample △T(τ) is expressed as follows:

[0108] Formula (2) △T(τ)=QD(τ) / (λroπ 3 / 2 ) where Q is a constant output power ro: Probe radius λ, the thermal conductivity of the sample being measured, i.e., the value to be determined D(τ): Dimensionless time function R*=Ro(1+α△Ti), K=αRoQ / (λroπ 3 / 2 ), and by substituting equation (2) into equation (1), we obtain the following equation.

[0109] formula 3 R(t)=R*+KD(τ) Based on the measured resistance R(t) versus D(τ), a straight line graph with an intercept C is plotted. The characteristic time θ is repeatedly varied and fitted to maximize the linear correlation of R(t) versus D(τ). The thermal conductivity in this case can be calculated from the slope K of the line.

[0110] A loading coefficient of 0.4 means that the volume of the container is V mL, the volume of the composite material 100 is V mL, and V / V = 0.4. For example, if the volume of the container is 500 mL and the volume of the composite material 100 is 200 mL, the loading coefficient of the container is 0.4. However, the volume of the composite material 100 refers to the volume of the composite material 100 deposited.

[0111] After being stirred, the composite material 100 is passed through a sieve of (0.1 to 0.3) x A. The mesh size of the sieve is selected as follows: First, the range (0.1 x A to 0.3 x A) is obtained from the A value of the composite material 100 (the value of D501) x (0.1 to 0.3), and a sieve standard is selected from this range to perform sieving. After that, the content of the material that falls under the sieve is measured.

[0112] For example, when D501 of the composite material 100 is A and the composite material 100 has a mass M, the composite material 100 is placed in a container equipped with a stirrer, stirred for 10 minutes under conditions of a loading coefficient of 0.4 and 500 r / min, and passed through a sieve of (0.1 to 0.3) × A. The amount of material that falls under the sieve is 0.05 × M, 0.04 × M, 0.03 × M, 0.02 × M, 0.01 × M, or 0.

[0113] In the composite material 100 of the present application, the thermal conductivity of the core material is 20 W / m·k or more, and the composite material 100 obtained by combining the core 110 and shell 120 has high thermal conductivity. This allows the composite material 100 to be used as a thermally conductive filler. Furthermore, the metal salt shell can compensate for defects of a single core material to some extent. The composite material 100 is processed under stirring conditions, and the amount of undersize is very small, proving that the shell material and core material in the composite material 100 are tightly bonded, preventing the core 110 and shell 120 from separating. This proves that the thermally conductive composite has low viscosity, is effective in compensating for defects in the core material, and has good aging resistance.

[0114] The present embodiment further provides a composite material 100 having a core 110 and a shell 120 covering the outside of the core 110, wherein the core material has a thermal conductivity of 20 W / m·k or more, and the shell material contains a first metal salt obtained by sintering.

[0115] During sintering, the shell raw materials react to produce a first metal salt. Because the first metal salt is used as at least a part of the shell material, it is possible to eliminate gaps between the shell 120 and the core 110. Furthermore, during sintering, the shell raw materials undergo mass transfer, allowing the formed shell 120 to more uniformly cover the surface of the core 110.

[0116] In the composite material 100 of the present application, the thermal conductivity of the core material is 20 W / m·k or more, and the composite material 100 obtained by combining the core 110 and shell 120 has high thermal conductivity. This allows the composite material 100 to be used as a thermally conductive filler. The metal salt shell is obtained by sintering. During sintering, at least a portion of the shell material undergoes mass transfer to the surface of the core 110, resulting in a shell material with superior coating effect. When the composite material 100 is added as a filler to a substrate to form a thermally conductive mixed material, it compensates for defects in the core material and provides excellent aging resistance. Furthermore, the composite material can be uniformly dispersed in the thermally conductive mixed material due to its low viscosity.

[0117] An embodiment of the present application further provides a composite material 100 having a core 110 and a shell 120 coating the outside of the core 110, wherein the shell material contains a first metal salt, the core material has a thermal conductivity of 20 W / m·k or more, at least one element in the core material is the same as at least one element in the shell material, and a transition layer (a microscopic structure, not shown) is further present between the core 110 and the shell 120, and the content of the at least one element in the transition layer gradually decreases and the content of the at least one element gradually increases from the outside to the inside.

[0118] The transition layer is a layered structure in which the elements of the material change gradually, for example, the core material is a material with a relatively uniform element content (which may be a single material or a composite material), and the shell material is also a material with a relatively uniform element content (which may be a single material or a composite material), whereas the material in the transition layer is not made of a single material but is made of a material with a gradually changing element content.

[0119] In the above technical form, the thermal conductivity of the core material is 20 W / m·k or more, and the composite material 100 obtained by combining the core 110 and the shell 120 has high thermal conductivity. Therefore, this composite material 100 can be used as a thermally conductive filler. The metal salt shell is obtained by sintering. During sintering, a portion of the core 110 reacts with the shell raw material to form the shell material. As a result, at least one element in the core material becomes the same as at least one element in the shell material, resulting in the formation of a transition layer between the core 110 and the shell 120. As the core material and the shell raw material react during sintering, the content of one element in the transition layer gradually increases and the content of another element gradually decreases. When this composite material 100 is added to a substrate as a filler to form a thermally conductive composite, it compensates for defects in the core material and has good aging resistance. Furthermore, the composite material has low viscosity in the thermally conductive composite, allowing it to be uniformly dispersed in the thermally conductive composite, thereby more effectively compensating for defects in the core material.

[0120] In the present application, the composite material can be used as a thermally conductive filler, a ceramic material, other materials that require insulation, a filler for available materials, etc., but is not limited to these.

[0121] In one embodiment, the mass ratio of the core 110 is 95% or less. The mass ratio of the core 110 is determined by XRD measurement followed by analysis based on the RIR method. The basic principle is that the RIR value is the ratio of the integrated intensities of the strongest diffraction peaks of the shell material and the core material. Therefore, the integrated intensity of the core material can be calculated from the integrated intensity / RIR value of the shell material. In the case of a mixture, all components of the substance can be calculated in this way, and the content of each specific component can be finally obtained by normalization.

[0122] The thermal conductivity of the core material is typically higher than that of the shell material. In the composite material 100, at least 5% of the shell 120 is located on the surface of the core 110 to compensate for some defects in the core material.

[0123] For example, the mass ratio of the core 110 is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. Optionally, the mass ratio of the core 110 is 30% to 95%. Therefore, the core 110 provides the composite material 100 with high thermal conductivity, and the shell 120 compensates for the defects of the core material.

[0124] In one embodiment, the mass ratio of the core 110 is 55% to 80%. This increases the thermal conductivity of the composite material 100, and the shell material at this content covers a wider area of ​​the core 110 surface, essentially covering the entire surface of the core 110. This compensates for the defects of the core material, and the composite material 100 combines the performance of the core 110 and the performance of the shell 120, resulting in excellent overall performance. Optionally, the mass ratio of the core 110 is 60% to 75%. This further improves the overall performance of the composite material 100.

[0125] In one embodiment, the thermal conductivity of the core material is between 20 W / m·k and 500 W / m·k. The thermal conductivity of the core material is an inherent property of the material, and using a material with a high thermal conductivity for the core 110 can further increase the thermal conductivity of the final composite material 100.

[0126] Illustratively, the thermal conductivity of the core material is 20 W / m·k, 50 W / m·k, 100 W / m·k, 150 W / m·k, 200 W / m·k, 250 W / m·k, 300 W / m·k, 350 W / m·k, 400 W / m·k, 450 W / m·k, or 500 W / m·k. Optionally, the thermal conductivity of the core material is between 50 W / m·k and 250 W / m·k.

[0127] In one embodiment, at least one element of the core material is the same as at least one element of the first metal salt. If the amount of undersize after the composite material is stirred is small or if one element of the first metal salt after sintering is the same as one element of the core material, the bond between the core material and the shell material will be stronger, the adaptability of the materials will be better, and the effect of compensating for defects in the core material will be better.

[0128] The first type of composite material In the present application, the core 110 may be various inorganic thermally conductive fillers. In one embodiment, the core 110 is a semiconductor material. When a semiconductor material is used as a thermally conductive filler in an electrical product, the semiconducting properties of the thermally conductive filler may adversely affect the performance of the electrical product (for example, the composite material 100 may be used as a thermally conductive filler in a thermal pad or thermally conductive gel, and may be applied in fields such as 5G, the electronics industry, and new energy). For this reason, semiconducting thermally conductive fillers have the drawback of poor insulation.

[0129] In contrast, in the present application, the surface of the semiconductor core is coated with an insulating shell made of an insulating material containing a first metal salt, so the insulating metal salt shell can compensate to some extent for the defects of the semiconductor core material. The composite material is processed under stirring conditions, and the amount of undersize is very small, which proves that the shell material and the core material in this composite material are tightly bonded, making it difficult for the core and shell to separate. This results in a low viscosity thermally conductive composite material, excellent thermal conductivity and insulating properties, and good aging resistance.

[0130] Alternatively, the core material may be silicon carbide or aluminum oxide. When the core material is silicon carbide, the first metal salt in the shell material is a metal silicate, and when the core material is aluminum oxide, the first metal salt in the shell material is an aluminate.

[0131] The following describes an example in which the core material is silicon carbide and the shell material contains a metal silicate. Silicon carbide has a thermal conductivity of 80 W / m·k to 490 W / m·k. In one embodiment, there is no gap between the core 110 and the shell 120, i.e., there is no gap between the silicon carbide core and the shell 120 containing the metal silicate, and the metal silicate coats the silicon carbide surface without any gaps. This results in high thermal conductivity and breakdown voltage of the composite material 100, and excellent insulation properties.

[0132] In one embodiment, the shell 120 is a complete shell, i.e., a shell 120 containing a metal silicate coated silicon carbide core is a complete shell. The terms complete shell and complete coating have different meanings. A complete shell refers to an integral structure with connections between the shells 120. This integral structure coats the surface of the core 110, i.e., the shell 120 coats the surface of the core 110 relatively uniformly, making it difficult for the shell 120 to detach even when the composite material 100 is subjected to external force. In addition, the composite material 100 has high thermal conductivity and excellent electrical insulation properties.

[0133] In one embodiment, the shell 120 is a continuous coating layer, i.e., the shell 120 containing the metal silicate coated silicon carbide core is a continuous coating layer. A continuous coating layer and a complete coating have different meanings. A continuous coating layer refers to a coating layer in which the connections are integrally connected and do not include intermittent or split-layered regions. In this case, the shell 120 is less likely to detach even when the composite material 100 is subjected to external force, and the composite material 100 has higher thermal conductivity and better insulation properties. A complete coating refers to a coating in which the entire surface of the silicon carbide is coated with a metal silicate shell, leaving no exposed silicon carbide surface.

[0134] In one embodiment, the composite material 100 does not contain a binder. The composite material 100 of the present application is sintered to obtain a shell 120 containing a metal silicate that coats a silicon carbide core. The sintering is performed at high temperatures, and the composite material 100 obtained by the sintering reaction does not contain a binder (binders are typically organic substances that cannot withstand high temperatures and react and disappear at high temperatures). This strengthens the bond between the silicon carbide and the metal silicate in the composite material 100, thereby avoiding, to some extent, the impact of the binder on the performance of the composite material 100.

[0135] In one embodiment, the shell 120 is not an agglomerate of multiple metal silicate particles adhered to the surface of the core 110. In conventional physical coatings (where a binder is added to allow the shell 120 to coat the surface of the core 110), the shell 120 is an agglomerate of multiple particles adhered to the surface of the core 110, and some particles of the shell 120 are easily detached from the core 110. Adding such a material to the base material results in the addition of independent silicon nitride powder and metal silicate powder to the base material, which can degrade the performance of the thermally conductive composite material. In contrast, in the present application, at least a portion of the shell material is obtained by chemical reaction through sintering, and is not an agglomerate of multiple particles physically adhered to the surface of the core 110. This makes it less likely for the shell 120 to detach from the core 110, resulting in better performance of the thermally conductive composite material.

[0136] In one embodiment, the crystal grains of the core 110 are directly connected to the crystal grains of the shell 120. The metal silicate shell is obtained by sintering, during which the silicon carbide in the surface layer reacts with the shell material to form the metal silicate. This directly connects the microscopic crystal grains between the shell 120 and the core 110, tightly connecting the shell 120 to the outside of the silicon carbide core, and improving the performance of the inorganic composite filler. Adding such a material to the base material improves the performance of the thermally conductive composite material.

[0137] In one embodiment, the composite material 100 satisfies the following conditions: the composite material 100 has a mass M and a D501 of A, is placed in a container equipped with a stirrer, and is stirred for 10 minutes at a loading coefficient of 0.4 and 500 r / min. Thereafter, the composite material 100 is passed through a sieve of (0.1-0.3) x A, and the amount of material remaining under the sieve is 0.02 x M or less. This allows the silicon carbide core to be tightly connected to the shell 120 containing the metal silicate, resulting in a high thermal conductivity and high breakdown voltage of the resulting composite filler.

[0138] In one embodiment, the silicon carbide core is a primary particle. Primary particles are not composed of agglomerated silicon carbide particles, but rather are silicon carbide particles obtained by crushing a large silicon carbide block or directly formed silicon carbide particles, and these silicon carbide particles have essentially no gaps within them. Because the silicon carbide core 110, which is a primary particle, has high thermal conductivity, when it is combined with the shell 120, the resulting composite material 100 also has high thermal conductivity. Therefore, it can be added to a substrate as a thermally conductive filler. Furthermore, when the silicon carbide core is a primary particle, the number of interfaces is reduced, resulting in high thermal conductivity, and thus superior thermal conductivity of the composite material 100.

[0139] In one embodiment, the metal silicate-containing shell 120 covers at least 85% of the surface of the silicon carbide core. Because most of the surface of the silicon carbide core is covered with the metal silicate-containing shell material, the presence of the shell 120 enhances the insulating properties of the composite material 100. This can improve the performance of electrical appliances when the composite material 100 is applied to such appliances.

[0140] In one embodiment, the shell 120 completely coats the core 110. The surface of the silicon carbide core is completely coated with the shell 120 (metal silicate-containing shell 120), i.e., the entire surface of the core 110 is coated with the complete shell, or the entire surface of the core 110 is coated with a continuous coating layer (shell 120). When this composite material 100 is added as a thermally conductive filler to a substrate to form a thermally conductive composite, the resulting layered structure has a higher breakdown voltage and better insulating properties without adversely affecting thermal conductivity.

[0141] In this application, the core material of the composite material 100 is silicon carbide, and the metal salt of the shell material includes a metal silicate, which includes at least one of magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium silicate zirconate, aluminum silicate zirconate, and zinc silicate zirconate. The metal silicate is formed by chemically reacting the shell material on the surface of the silicon carbide with the silicon carbide through sintering, resulting in a material with excellent electrical insulation and thermal conductivity. Adding such a material as a thermally conductive filler to the substrate has the advantages of lowering viscosity, increasing thermal conductivity, and increasing breakdown voltage.

[0142] In one embodiment, the metal salt of the shell material includes a metal silicate (first metal salt) and a second metal salt containing at least two metal elements but no silicon, where the mass ratio of the metal silicate in the shell material is 10% or more. When the second metal salt contains two metal elements, it has higher thermal conductivity (compared to the metal silicate), and the metal silicate allows the shell 120 to completely cover the core 110 and improves the thermal conductivity of the composite material 100. In addition, the second metal salt also has a certain insulating property, which improves the insulating property of the composite material 100.

[0143] Illustratively, for composite material 100 in which core 110 is silicon carbide, the weight percentage of the metal silicate in the shell material is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%. Optionally, the weight percentage of the metal silicate in the shell material is between 20% and 90%.

[0144] Furthermore, the mass ratio of the metal silicate in the shell material is 40% to 80%, and the higher the content of the metal silicate, the stronger the bond between the core 110 and the shell 120. This also improves the performance of the shell material, and the bonding performance of the two materials in the shell 120 is also good, so the overall performance of the composite material 100 is better.

[0145] In the present application, in the composite material 100 in which the core 110 is silicon carbide, the first metal salt of the shell material is a metal silicate, and the second metal salt is an aluminate and / or zirconate. Its thermal conductivity and electrical insulation properties are also high. Optionally, the second metal salt includes at least one of zinc aluminate, magnesium aluminate, calcium aluminate, potassium aluminate, zinc zirconate, magnesium zirconate, calcium aluminate, and potassium aluminate. The second metal salt can bond well with the first metal salt, and the thermal conductivity and electrical insulation properties of aluminates and / or zirconates are superior to those of metal silicates, resulting in high thermal conductivity and electrical insulation properties of the composite material 100.

[0146] In another embodiment, all of the metal salts in the shell material are metal silicates, and the mass fraction of the shell material is 100% metal silicates. In a composite material 100 having a silicon carbide core 110, when all of the shell material is metal silicates, the purity of the shell material is high, which is conducive to manufacturing.

[0147] In another embodiment, the shell material may contain a portion of metal oxide (shell material that has not reacted with the core material), but this is not a limitation of the present application, as long as a portion of the shell material reacts with the core material to form a metal silicate.

[0148] In some embodiments, the composite material has a D501 of 100 μm to 150 μm, the core material is silicon carbide, and the shell material is magnesium silicate. The composite material 100 satisfies the following conditions: 4.8 parts by weight of vinyl silicone oil having a viscosity of 100 mpa.s, 20 parts by weight of the composite material 100, 21 parts by weight of spherical alumina NSM-1S, 30 parts by weight of spherical alumina BAK-10, and 25 parts by weight of spherical alumina BAK-120 are mixed, and the mixture is first treated at a rotation speed of 1100 r / min under a vacuum of 1000 Pa for 1 minute, and then at a rotation speed of 1500 r / min under a vacuum of 40 Pa for 1 minute. The mixture is then measured at 25°C for 0.1 to 100 s using an Anton Paar rheometer. -1 Under the condition of 1s -1 When the viscosity is measured, it is 1×10 6 mpa·s~1.6×10 6 mpa·s.

[0149] When the viscosity of the composite material 100 is within the above range, the thermal conductivity and breakdown voltage of the composite material 100 are high, and the overall performance is excellent. 6 mpa·s, 1.1×10 6 mPa·s, 1.2×10 6 mpa·s, 1.3×10 6 mPa·s, 1.4×10 6 mpa·s, 1.5×10 6mPa·s or 1.6×10 6 mpa·s.

[0150] In some embodiments, the composite material 100 in which the core 110 is silicon carbide has a ratio of the thickness of the shell 120 to the particle size of the composite material 100 (thickness of the shell 120:particle size of the composite material 100) of 0.02 to 0.1. The appropriate relative thickness of the shell 120 containing such a metal silicate provides the composite material 100 with high thermal conductivity and also improves the insulating properties of the composite material 100. In the present application, the thickness of different portions of the shell 120 may be different, as long as the ratio of the thickness of a portion of the shell 120 to the particle size of the composite material 100 is within the range of 0.02 to 0.1.

[0151] For example, the ratio of the thickness of the shell 120 containing the metal silicate to the particle size of the composite material 100 is 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. Optionally, the ratio of the thickness of the shell 120 containing the metal silicate to the particle size of the composite material 100 is 0.04 to 0.07. This can further improve the thermal conductivity and electrical insulation of the composite material 100.

[0152] Second type of composite material In the present application, the core 110 can be made of various high-hardness materials. In one embodiment, the core material has a Mohs hardness of 7 to 10. When a high-hardness core material is added as a thermally conductive filler to a substrate to form a thermally conductive composite. If the thermally conductive composite is solidified and the resulting thermally conductive layer is placed between other devices, the high-hardness thermally conductive filler in the thermally conductive layer may cause wear on the device and affect its service life over long-term use. Therefore, in the present application, the surface of the core 110, which has a Mohs hardness of 7 to 10, is tightly coated with a metal salt-containing shell material. The metal salt shell has a Mohs hardness of less than 7, thereby increasing the thermal conductivity of the composite 100 while maintaining a relatively low hardness. Furthermore, the composite is processed under stirring conditions, resulting in a very low amount of undersize material, which demonstrates that the shell and core materials are tightly bonded to each other in the composite, preventing the core and shell from separating. When such a thermally conductive filler is added to a substrate to form a thermally conductive composite, the viscosity of the thermally conductive composite is reduced, and the thermally conductive layer formed using this material has high thermal conductivity and low hardness, resulting in excellent wear resistance and aging resistance of the device.

[0153] Alternatively, the core material may be silicon carbide (Mohs hardness 9.5), silicon nitride (Mohs hardness 9 to 9.5), or aluminum oxide (Mohs hardness 9). When the core material is silicon nitride, the first metal salt in the shell material is a metal silicate, and when the core material is aluminum oxide, the first metal salt in the shell material is an aluminate.

[0154] The following describes an example in which the core material is silicon nitride and the shell material contains metal silicate. Silicon nitride has a thermal conductivity of 40 W / m·k to 320 W / m·k. In one embodiment, there are no gaps between the core 110 and the shell 120, i.e., there are no gaps between the silicon nitride core and the shell 120 containing metal silicate, and the metal silicate completely coats the silicon nitride surface. This increases the thermal conductivity of the composite material 100 and reduces its hardness, thereby preventing wear on the device when used as a thermally conductive filler.

[0155] In one embodiment, the shell 120 is a complete shell, i.e., a shell 120 containing a metal silicate coated silicon nitride core is a complete shell. The terms complete shell and complete coating have different meanings. A complete shell refers to an integral structure with connections between the shells 120. This integral structure coats the surface of the core 110, i.e., the shell 120 coats the surface of the core 110 relatively uniformly, making the shell 120 less likely to detach even when the composite material 100 is subjected to external forces. Furthermore, the composite material 100 has increased thermal conductivity and reduced surface hardness, further improving the wear resistance of the device. Complete coating refers to the metal silicate shell coating the entire silicon nitride surface, leaving no exposed silicon nitride surface.

[0156] In one embodiment, the shell 120 is a continuous coating layer, i.e., the shell 120, which contains a silicon nitride core coated with metal silicate, is a continuous coating layer. A continuous coating layer and a complete coating have different meanings. A continuous coating layer refers to a coating layer in which the connections are integrally connected and do not include intermittent or split-layered areas. In this case, the shell 120 is less likely to detach even when the composite material 100 is subjected to external force, and the thermal conductivity of the composite material 100 is increased. This can, to some extent, prevent wear on the device caused by the thermally conductive layer formed as a thermally conductive filler.

[0157] In one embodiment, the composite material 100 does not contain a binder. The composite material 100 of the present application is sintered to obtain a shell 120 containing a metal silicate coating a silicon nitride core. The sintering is performed at high temperatures, and the composite material 100 obtained by the sintering reaction does not contain a binder (binders are typically organic substances that cannot withstand high temperatures and react and disappear at high temperatures). This strengthens the bond between the silicon nitride and the metal silicate in the composite material 100, thereby avoiding, to some extent, the impact of the binder on the performance of the composite material 100.

[0158] In one embodiment, the shell 120 is not an agglomerate of multiple metal silicate particles adhered to the surface of the core 110. In conventional physical coatings (where a binder is added to coat the surface of the core 110 with the shell 120), the shell 120 is an agglomerate of multiple metal silicate particles adhered to the surface of the silicon nitride core, and some particles of the shell 120 are easily detached from the core 110. Adding such a material to the base material results in the addition of independent silicon carbide powder and metal silicate powder to the base material, which can degrade the performance of the thermally conductive composite material. In contrast, in the present application, at least a portion of the shell 120 is obtained by chemical reaction through sintering, and is not an agglomerate of multiple particles physically adhered to the surface of the core 110. This makes the shell 120 less likely to detach from the core 110, resulting in better performance of the thermally conductive composite material.

[0159] In one embodiment, the crystal grains of the core 110 are directly connected to the crystal grains of the shell 120. The metal silicate is obtained by sintering, during which the silicon nitride on the surface reacts with the shell material to form the metal silicate. This directly connects the microscopic crystal grains between the shell 120 and the core 110, tightly connecting the shell 120 to the outside of the silicon nitride core, and improving the performance of the inorganic composite filler. Adding such a material to the base material improves the performance of the thermally conductive composite material.

[0160] In one embodiment, the composite material 100 satisfies the following conditions: the composite material 100 has a mass M and a D501 of A, is placed in a container equipped with a stirrer, and is stirred for 10 minutes at a loading coefficient of 0.4 and 500 r / min. Thereafter, the composite material 100 is passed through a sieve of (0.1 to 0.3) x A, with the amount of material remaining under the sieve being 0.02 x M or less. This allows the silicon nitride core to be tightly connected to the shell 120 containing the metal silicate, and the resulting composite filler has high thermal conductivity and low strength, making it less likely to cause wear to the device.

[0161] In one embodiment, the metal silicate-containing shell 120 covers at least 85% of the surface of the silicon nitride core. Because a majority of the surface of the silicon nitride core is covered by the metal silicate-containing shell material, the presence of the shell 120 can reduce the hardness of the composite material 100. This can reduce or eliminate wear on the device of a thermally conductive layer including the composite material 100, and also improve the thermal conductivity of the thermally conductive layer.

[0162] In one embodiment, the shell 120 completely covers the core 110. The surface of the silicon nitride core is completely covered with the shell 120 (metal silicate-containing shell 120), i.e., the entire surface of the core 110 is completely covered with the shell, or the entire surface of the core 110 is covered with a continuous covering layer (shell 120). When this composite material 100 is added as a thermally conductive filler to a substrate to form a thermally conductive composite, the resulting layered structure is less hard and less abrasive to the device, without adversely affecting thermal conductivity.

[0163] In this application, the core material is silicon nitride, and the shell material is a metal silicate, which includes at least one of magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium silicate zirconate, aluminum silicate zirconate, and zinc silicate zirconate. The metal silicate is formed by chemically reacting the shell material on the silicon nitride surface with the silicon nitride through sintering, resulting in a material with low hardness and excellent thermal conductivity. Adding such a material as a thermally conductive filler to the substrate can reduce viscosity, increase thermal conductivity, and reduce wear on the device.

[0164] Illustratively, for a composite material 100 in which the core 110 is silicon nitride, the weight percentage of the metal silicate in the shell material is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%. Optionally, the weight percentage of the metal silicate in the shell material is between 20% and 90%.

[0165] Furthermore, the mass ratio of the metal silicate in the shell material is 40% to 80%, and other components in the shell material may include metal oxides. The higher the content of the metal silicate, the stronger the bond between the core 110 and the shell 120. This also improves the performance of the shell material and the bonding performance of the two types of materials in the shell 120, resulting in better overall performance of the composite material 100.

[0166] In another embodiment, all of the metal salts in the shell material are metal silicates, and the mass fraction of the shell material is 100% metal silicates. In a composite material 100 having a silicon carbide core 110, when all of the shell material is metal silicates, the purity of the shell material is high, which is conducive to manufacturing.

[0167] In another embodiment, the shell material may contain a portion of metal oxide (shell material that has not reacted with the core material), but this is not a limitation of the present application, as long as a portion of the shell material reacts with the core material to form a metal silicate.

[0168] In some embodiments, the composite material 100, in which the core 110 is silicon nitride, has a ratio of the thickness of the shell 120 to the grain size of the composite material 100 (thickness of the shell 120:grain size of the composite material 100) of 0.02 to 0.1. The relative thickness of the shell 120 containing such a metal silicate is appropriate, so that the composite material 100 has high thermal conductivity and can avoid wear on the device. In this application, the thickness of different parts of the shell 120 may be different, as long as the ratio of the thickness of some areas to the grain size of the composite material 100 is within the range of 0.02 to 0.1.

[0169] Illustratively, the ratio of the thickness of the metal silicate-containing shell 120 to the particle size of the composite material 100 is 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. Optionally, the ratio of the thickness of the metal silicate-containing shell 120 to the particle size of the composite material 100 is 0.04 to 0.07. This can further improve the thermal conductivity of the composite material 100 and prevent wear on the device.

[0170] The third type of composite material In the present application, the core 110 can be a thermally conductive filler having various hydrolytic properties. In one embodiment, the core 110 is a material that is easily hydrolyzable. If such a thermally conductive filler is used to form a thermally conductive layer, the thermally conductive filler in the thermally conductive layer will hydrolyze if the thermally conductive layer is used for a long period of time in a high-humidity environment, resulting in a decrease in the thermal conductivity of the thermally conductive layer. In contrast, in the present application, the surface of the easily hydrolyzable core 110 is tightly coated with a water-insoluble shell 120, and the water-insoluble shell material contains a first metal salt. The high hydrolytic stability of the metal salt shell also contributes to the high hydrolytic stability of the composite material. Furthermore, the composite material is processed under stirring conditions, and the very low amount of undersize material proves that the shell material and core material are tightly bonded in this composite material, making it difficult for the core and shell to separate. This results in a low viscosity of the thermally conductive composite material, as well as high thermal conductivity and hydrolytic stability, and good aging resistance, allowing the high thermal conductivity to be maintained for a long period of time.

[0171] Alternatively, the core material is aluminum nitride and the shell material contains aluminate. Aluminum nitride has a thermal conductivity of 80 W / m·k to 320 W / m·k. In one embodiment, there is no gap between the core 110 and the shell 120, i.e., there is no gap between the aluminum nitride core and the aluminate-containing shell 120, and the aluminate coats the aluminum nitride surface without any gaps. This results in high thermal conductivity and high hydrolytic stability of the composite material 100.

[0172] In one embodiment, the shell 120 is a complete shell, i.e., a shell 120 containing an aluminate coated aluminum nitride core is a complete shell. The terms complete shell and complete coating have different meanings. A complete shell refers to an integral structure with connections between the shells 120. This integral structure coats the surface of the core 110, i.e., the shell 120 coats the surface of the core 110 relatively uniformly, making it difficult for the shell 120 to detach even when the composite material 100 is subjected to external forces. This increases the thermal conductivity and hydrolytic stability of the composite material 100. A complete coating refers to the entire surface of the aluminum nitride being coated with an aluminate shell, with no exposed aluminum nitride surface.

[0173] In one embodiment, the shell 120 is a continuous coating layer, i.e., the shell 120 includes an aluminum nitride core coated with aluminate. A continuous coating layer and a complete coating are different terms. A continuous coating layer refers to a coating layer in which the connections are integrally connected and do not include intermittent or split-layered regions. In this case, the shell 120 is less likely to detach when the composite material 100 is subjected to external forces, and the composite material 100 has high thermal conductivity and high hydrolytic stability.

[0174] In one embodiment, the composite material 100 does not contain a binder. The composite material 100 of the present application is sintered to obtain a shell 120 containing an aluminate coating on an aluminum nitride core. The sintering is performed at high temperatures, and the composite material 100 obtained by the sintering reaction does not contain a binder (binders are typically organic substances that cannot withstand high temperatures and react and disappear at high temperatures). This strengthens the bond between the aluminum nitride and the aluminate in the composite material 100, thereby avoiding, to some extent, the impact of the binder on the performance of the composite material 100.

[0175] In one embodiment, the shell 120 is not an agglomerate of aluminate particles adhered to the surface of the core 110. In conventional physical coatings (where a binder is added to coat the surface of the core 110 with the shell 120), the shell 120 is an agglomerate of aluminate particles adhered to the surface of the aluminum nitride core, and some particles of the shell 120 are easily detached from the core 110. Adding such a material to the base material results in separate aluminum nitride powder and aluminate powder being added to the base material, which can degrade the performance of the thermally conductive composite material. In contrast, in the present application, at least a portion of the shell 120 is obtained by chemical reaction through sintering, and is not an agglomerate of a plurality of particles physically adhered to the surface of the core 110. This makes the shell 120 less likely to detach from the core 110, resulting in better performance of the thermally conductive composite material.

[0176] In one embodiment, the crystal grains of the core 110 are directly connected to the crystal grains of the shell 120. The aluminate is obtained by sintering, during which the aluminum nitride in the surface layer reacts with the shell material to form aluminate. This directly connects the microscopic crystal grains between the shell 120 and the core 110, tightly connecting the shell 120 to the outside of the aluminum nitride core, and improving the performance of the inorganic composite filler. Adding such a material to the base material improves the performance of the thermally conductive composite material.

[0177] In one embodiment, the composite material 100 satisfies the following conditions: the composite material 100 has a mass M and a D501 of A, is placed in a container equipped with a stirrer, and is stirred for 10 minutes at a loading coefficient of 0.4 and 500 r / min. Thereafter, the composite material 100 is passed through a sieve of (0.1-0.3) x A, with the amount of material remaining under the sieve being 0.02 x M or less. This allows the aluminum nitride core to be tightly connected to the aluminate-containing shell 120, resulting in a composite filler with high thermal conductivity and improved hydrolytic stability.

[0178] In one embodiment, the aluminate-containing shell 120 covers at least 85% of the surface of the aluminum nitride core. Because a majority of the surface of the aluminum nitride core is covered by the aluminate-containing shell material, the presence of the shell 120 further improves the hydrolytic stability of the composite 100, thereby extending the useful life of the composite 100 in high humidity environments.

[0179] In one embodiment, the shell 120 completely covers the core 110. The surface of the aluminum nitride core is completely covered with the shell material (the aluminate-containing shell 120). When this composite material 100 is added as a thermally conductive filler to a substrate to form a thermally conductive composite, the resulting layered structure has higher hydrolytic stability without adversely affecting thermal conductivity.

[0180] In this application, the core material is aluminum nitride, and the shell material includes an aluminate, which includes at least one of magnesium aluminate, zinc aluminate, calcium aluminate, potassium aluminate, and aluminum silicate. The aluminate is formed by chemically reacting the shell material with aluminum nitride on the surface of the aluminum nitride through sintering, resulting in a material with high hydrolytic stability and thermal conductivity. Adding such a material as a thermally conductive filler to the substrate can reduce viscosity, increase thermal conductivity, and extend service life in high-humidity environments.

[0181] In another embodiment, the shell material includes an aluminate and a shell raw material (e.g., at least one of magnesium oxide, zinc oxide, calcium oxide, potassium oxide, and silicon oxide), provided that some of the shell raw material reacts with the core material to form an aluminate, and this is not a limitation of the present application.

[0182] In some embodiments, the composite material 100, in which the core 110 is aluminum nitride, has a ratio of the thickness of the shell 120 to the particle size of the composite material 100 (thickness of the shell 120:particle size of the composite material 100) of 0.02 to 0.1. The appropriate relative thickness of the aluminate-containing shell 120 allows the composite material 100 to have high thermal conductivity and high hydrolytic stability. In the present application, the thickness of different portions of the shell 120 may vary, as long as the ratio of the thickness of some regions to the particle size of the composite material 100 is within the range of 0.02 to 0.1.

[0183] For example, the ratio of the thickness of the aluminate-containing shell 120 to the particle size of the composite material 100 is 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. Optionally, the ratio of the thickness of the aluminate-containing shell 120 to the particle size of the composite material 100 is 0.04 to 0.07. This can further improve the thermal conductivity of the composite material 100 and increase its hydrolytic stability.

[0184] In some embodiments, the composite has a tap density of 1.85 g / m 3 That's it. The relatively high tap density of this composite material 100 results in high thermal conductivity and a more regular morphology of the material.

[0185] Illustratively, the tap density of the composite material 100 is 1.85 g / m 3 , 1.90g / m 3 , 1.95g / m 3 , 2.00g / m 3 , 2.05g / m 3 , 2.10 g / m 3 , 2.15g / m 3 , 2.20 g / m 3 , 2.25g / m 3 , 2.30 g / m 3 or 2.35 g / m 3 Optionally, the tap density of the composite material 100 is 1.85 g / m 3 ~2.30g / m 3 Furthermore, the tap density of the composite material 100 is 1.90 g / m3 ~2.30g / m 3 By controlling the tap density of the composite material 100 within the above range, the thermal conductivity is further increased and the overall performance is also improved.

[0186] In some embodiments, the specific surface area of ​​the composite material 100 is greater than 4 m 2 / g or less. The relatively low specific surface area of ​​the composite material 100 results in high thermal conductivity and a good composite effect between the shell material and the surface of the core.

[0187] Illustratively, the specific surface area of ​​the composite material 100 is 0.01 m 2 / g, 0.1m 2 / g, 0.2m 2 / g, 0.4m 2 / g, 0.6m 2 / g, 1m 2 / g, 2m 2 / g, 3m 2 / g or 4m 2 Optionally, the specific surface area of ​​the composite material 100 is 0.04 m 2 / g~4m 2 / g.

[0188] In some embodiments, the composite material 100 has a D501 of 0.5 μm or greater, which can contribute to the formation of a core-shell structure. Exemplarily, the composite material 100 has a D501 of 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 400 μm, 800 μm, or 1200 μm. Alternatively, the composite material 100 has a D501 of 0.5 μm to 1000 μm. Adding a composite material 100 satisfying this particle size range as a thermally conductive filler to a substrate can produce a product with higher thermal conductivity.

[0189] Furthermore, the D501 of the composite material 100 is 0.5 μm to 500 μm. This allows it to be applied to almost all base materials. The D501 of the composite material 100 is 0.5 μm to 150 μm, and also satisfies 0.5≦(D901−D101) / D501≦1.5. Because the particle size of this composite material 100 is appropriate and highly uniform, when it is added to a base material as a thermally conductive filler, the thermally conductive filler is less likely to agglomerate and is more uniformly dispersed.

[0190] In some embodiments, the composite material 100 has a D501 of 20 μm to 150 μm and satisfies 0.6≦(D901−D101) / D501≦1.5. This allows it to be used as a coarse powder for a thermally conductive filler. Optionally, the composite material 100 has a D501 of 40 μm to 150 μm and satisfies 0.6≦(D901−D101) / D501≦1. The composite material 100 has a specific surface area of ​​0.04 m 2 / g~0.06m 2 / g.

[0191] In some other embodiments, D501 of the composite material 100 is 0.5 μm to 20 μm and satisfies 0.5≦(D901−D101) / D501≦1, which allows it to be used as a fine powder for a thermally conductive filler.

[0192] Composite material manufacturing method The composite material 100 has been described above, and a method for manufacturing the composite material 100 will now be described. FIG. 2 is a flow chart of a manufacturing process for a composite material according to an embodiment of the present invention. As shown in FIG. 2, the manufacturing method includes step S110 of coating the surface of core 110 with a shell raw material to form a precursor, and step S120 of sintering the precursor to mass transfer at least a portion of the shell raw material to the surface of core 110 to form shell 120 containing a first metal salt, thereby obtaining composite material 100, wherein the core material has a thermal conductivity of 20 W / m·k or more.

[0193] If the core 110 is sintered directly in an oxygen atmosphere without coating, a coating structure having the shell 120 and the core 110 cannot be formed, and multiple protruding oxide particles form on the surface of the core 110. In contrast, in the present application, a precursor is first formed by coating the core 110 with a shell material. During the sintering process, the shell material mass-transfers to the surface of the core 110, forming a metal salt-containing shell 120 that coats the surface of the core 110 relatively uniformly. There are essentially no gaps between the shell 120 and the core 110. This results in a composite material 100 with superior performance, which can compensate for some defects in the core material and improves aging resistance. Furthermore, since the core material has a thermal conductivity of 20 W / m·k or higher, forming the shell 120 by sintering increases the thermal conductivity of the resulting composite material 100, making it suitable for use as a thermally conductive filler.

[0194] Furthermore, mass transfer refers to the fact that the shell raw material coats the surface of the core 110, and during the sintering process, the shell raw material or the reacted material slightly migrates to the surface of the core 110. This allows the resulting shell 120 to be more uniformly coated.

[0195] In one embodiment, the thermal conductivity of the core material is 20 W / m·k to 500 W / m·k. The thermal conductivity of the core material is an inherent property of the material, and using a material with high thermal conductivity for the core 110 can further increase the thermal conductivity of the final composite material 100. This can contribute to the application of the thermally conductive filler.

[0196] Illustratively, the thermal conductivity of the core material is 20 W / m·k, 50 W / m·k, 100 W / m·k, 150 W / m·k, 200 W / m·k, 250 W / m·k, 300 W / m·k, 350 W / m·k, 400 W / m·k, 450 W / m·k, or 500 W / m·k. Optionally, the thermal conductivity of the core material is between 50 W / m·k and 250 W / m·k.

[0197] In some embodiments, sintering is performed at a temperature of 900° C. to 1800° C. for 1 hour to 10 hours. Sintering under these conditions allows the core material and the shell raw materials to react with each other, resulting in a core-shell composite material 100 having a metal salt shell.

[0198] In some embodiments, the sintering atmosphere may be an air atmosphere, a nitrogen gas atmosphere, an inert gas atmosphere, or the like, and is not limited to this application.

[0199] Method for manufacturing first-class composite material This manufacturing method includes the steps of forming a precursor that coats the surface of a semiconductor core with a shell material, and sintering the precursor to mass transfer at least a portion of the shell material to the surface of core 110 to form shell 120 containing a first metal salt, thereby obtaining composite material 100, wherein the core material has a thermal conductivity of 20 W / m·k or more. The following description will be given taking as an example a case where core 110 is made of silicon carbide.

[0200] A method for producing composite material 100 in which A 110 is silicon carbide includes forming a precursor that coats the surface of a silicon carbide core with a shell material, and sintering the precursor to mass transfer at least a portion of the shell material to the surface of the silicon carbide core to form shell 120 containing a first metal silicate, thereby obtaining composite material 100.

[0201] In this manufacturing method, the shell material is first coated, and then during the sintering process, the shell material is mass-transferred to the surface layer of the silicon carbide, forming a relatively uniform and complete shell 120 on the surface of the silicon carbide core. This not only satisfies the thermal conductivity requirements of the composite material 100, but also improves the breakdown voltage of the composite material 100 and enhances its insulating properties, making it suitable for use in the field of electrical products.

[0202] In some embodiments, the silicon carbide core is a primary particle, which provides better thermal conductivity to the composite material 100 due to fewer boundaries and more efficient heat transfer.

[0203] In some embodiments, the silicon carbide core has a tap density of 1.90 g / m 3 The tap density of the core 110 is high, so that the composite effect of the core 110 and the shell 120 is excellent, and as a result, the composite material 100 has high thermal conductivity and excellent insulating properties.

[0204] Illustratively, the tap density of a silicon carbide core is 1.90 g / m 3 , 1.95g / m 3 , 2.00g / m 3 , 2.05g / m 3 , 2.10 g / m 3 , 2.15g / m 3 , 2.20 g / m 3 , 2.25g / m 3 , 2.30 g / m 3 , 2.35g / m 3 , 2.40g / m 3 or 2.45 g / m 3 Optionally, the tap density of the silicon carbide core is 1.90 g / m 3 ~2.4g / m 3 This makes it possible to obtain a composite material 100 with high thermal conductivity and excellent insulating properties.

[0205] In some embodiments, the core material is silicon carbide, and the shell raw material includes at least one of magnesium, magnesium oxide, magnesium hydroxide, organic magnesium, zinc, zinc oxide, zinc hydroxide, organic zinc, zirconium, zirconium oxide, zirconium hydroxide, and organic zirconium. During sintering, at least a portion of the shell raw material reacts with and mass transfers with the core 110, thereby forming a shell 120 containing the first metal salt. During sintering, the shell raw material reacts with the surface layer of the silicon carbide and mass transfers to the surface of the silicon carbide, thereby forming magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium zirconate silicate, aluminum zirconate silicate, zinc zirconate silicate, or the like. Thus, a shell containing the metal silicate is formed on the surface of the core 110, i.e., in situ, resulting in high thermal conductivity and excellent electrical insulation of the composite material 100.

[0206] Optionally, the shell raw material is at least one of magnesium, magnesium oxide, magnesium hydroxide, aluminum, aluminum oxide, aluminum hydroxide, zinc, zinc oxide, zinc hydroxide, zirconium, zirconium oxide, and zirconium hydroxide. The above shell raw materials are easily available and can easily react with silicon carbide to obtain a shell material under sintering conditions.

[0207] Furthermore, the shell raw material is at least one of magnesium oxide, aluminum oxide, zinc oxide, and zirconium oxide. When a metal oxide is used as the shell raw material, it can easily react with silicon carbide to form a metal silicate. When two types of metal oxides are used as the shell raw material, a shell material containing a second metal salt in addition to the metal silicate can be formed, resulting in a shell 120 containing multiple materials, thereby improving the performance of the composite material 100.

[0208] In some embodiments, the core material is silicon carbide, and sintering is performed for 3 to 8 hours at a temperature of 1000° C. to 1400° C. Under these conditions, silicon carbide chemically reacts with magnesium, magnesium oxide, magnesium hydroxide, organic magnesium, zinc, zinc oxide, zinc hydroxide, organic zinc, zirconium, zirconium oxide, zirconium hydroxide, organic zirconium, etc. to form magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium zirconate silicate, aluminum zirconate silicate, zinc zirconate silicate, etc.

[0209] Exemplary sintering temperatures are 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C, or 1400°C. Sintering times are 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours. Optionally, when the core material is silicon carbide, sintering is performed at a temperature of 1300°C to 1400°C for 3 hours to 8 hours.

[0210] In another embodiment, the core material is silicon carbide and the shell raw material is a hydrous silicate. During sintering, at least a portion of the hydrous silicate melts and mass transfers to the surface of the core 110, forming a silicate-containing shell 120. During sintering, the shell raw material melts and mass transfers to the surface of the silicon carbide core, separating water, resulting in a silicate-containing shell 120. This provides the composite material 100 with high thermal conductivity and excellent electrical insulation.

[0211] Optionally, the hydrous silicate comprises one or more of hydrous magnesium silicate, hydrous sodium silicate, hydrous sodium aluminosilicate, and hydrous calcium aluminosilicate. The shell material obtained by sintering comprises magnesium silicate, sodium silicate, sodium aluminosilicate, calcium aluminosilicate, etc.

[0212] Alternatively, sintering may be performed for 3 to 8 hours at a temperature higher than the melting point of at least a portion of the hydrous silicate. For example, when the shell raw material is hydrous magnesium silicate (talc), sintering may be performed for 3 to 8 hours at 850°C to 1000°C.

[0213] In some embodiments, the D502 of the shell raw material is 0.05 μm to 10 μm, and the D503 of the silicon carbide core is 0.5 μm to 1000 μm, and the D502 / D503 satisfies 0.00001≦D502 / D503≦0.1. The shell raw material has a small particle size, which makes it easy to coat the surface of the silicon carbide core, and this contributes to the formation of a core-shell structure with a uniform coating after sintering.

[0214] Illustratively, the D502 of the shell material is 0.05 μm, 0.1 μm, 0.15 μm, 0.3 μm, 0.5 μm, 0.7 μm, 0.9 μm, 1.1 μm, 1.3 μm, 1.5 μm, 1.7 μm, 1.9 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. The D503 of the silicon carbide core is 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 400 μm, 800 μm, or 1000 μm. Furthermore, the value of D502 / D503 is 0.00001, 0.00005, 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.05 or 0.1.

[0215] In this application, D503 of the silicon carbide core is 0.5 μm to 1000 μm, and D501 of the composite material 100 is 0.5 μm to 1000 μm. This does not mean that the grain size of the composite material 100 obtained after coating and sintering the core 110 is the same as the grain size of the core 110. Usually, the grain size of the composite material 100 obtained by coating and sintering is slightly larger than the grain size of the core 110. This will not be explained here.

[0216] Optionally, the silicon carbide core has a D503 of 0.5 μm to 500 μm, and satisfies 0.0001≦D502 / D503≦0.1. The combination of core and shell materials that satisfies this condition provides a better precursor coating effect and a more uniform shell 120, thereby improving the thermal conductivity and electrical insulation of the composite material 100.

[0217] Furthermore, the silicon carbide core has a D503 of 0.5 μm to 140 μm, and satisfies 0.0003≦D502 / D503≦0.1. By combining silicon carbide core and shell materials that satisfy this condition, the resulting composite material 100 can be easily added to a substrate as a thermally conductive filler, contributing to applications in the field of thermal conduction.

[0218] In some embodiments, the mass ratio of the shell material in the precursor is 1% to 30%, which allows a good shell 120 to be formed by sintering and also prevents the shell 120 from being too thick, which can affect thermal conductivity to some extent.

[0219] For example, the mass ratio of the shell raw material in the precursor is 1%, 3%, 5%, 8%, 10%, 15%, 20%, 25%, or 30%. Optionally, the mass ratio of the shell raw material in the precursor is 5% to 20%. This allows the shell 120 to completely cover the core 110, preventing the shell 120 from becoming too thick. This increases the thermal conductivity of the composite material 100, further improving the insulating properties of the composite material 100.

[0220] In some embodiments, the method for forming the precursor includes mixing and coating a silicon carbide core, a shell material, and a coating aid. By using the coating aid to coat, the shell material is uniformly adhered to the surface of the silicon carbide core, and during the sintering process, the shell material undergoes mass transfer, ultimately forming a complete coated shell 120. This allows the shell 120 to coat the surface of the silicon carbide core more uniformly.

[0221] Optionally, the coating aid may include a silicon-containing coating aid, which allows the shell raw material to react with the silicon carbide and the coating aid at the same time, resulting in a more uniform coating, a better coating effect, and a less agglomerated product. The composite material has a high dielectric constant and a higher thermal conductivity.

[0222] Optionally, the coating aid includes tetraethyl orthosilicate. Tetraethyl orthosilicate can be used as a coating aid while also providing silicon, allowing the shell raw material to react with the silicon carbide core and tetraethyl orthosilicate at the same time. This results in a more uniform coating, a better coating effect, a product that is less likely to agglomerate, and a higher thermal conductivity for the composite material 100. Furthermore, the coating aid is tetraethyl orthosilicate.

[0223] In other embodiments, the coating aid may be polyvinyl butyral resin, acrylic resin, etc., but is not limited to this application. Any coating aid that can effectively adhere the shell raw material to the surface of the silicon carbide core is within the scope of protection of this application.

[0224] In some embodiments, the mass ratio of the coating aid in the precursor is 1% to 15%, which improves the coating effect and prevents the performance of the composite material 100 from being affected by excessive use of the coating aid.

[0225] For example, the mass ratio of the coating additive in the precursor is 1%, 2%, 4%, 6%, 9%, 12%, or 15%. Optionally, the mass ratio of the coating additive in the precursor is 3% to 10%, which improves the coating effect, avoids excessive use of the coating additive, and allows more shell raw material to react with the silicon carbide core.

[0226] In some embodiments, the coating is performed using a wet ball mill, with the rotation speed of the wet ball mill being 200 r / min to 600 r / min, and the wet ball milling time being 1 hour or more. By performing the coating using a wet ball mill, the coating aid can be utilized, the shell raw material can more uniformly coat the surface of the core 110, and agglomeration of the core 110 that occurs during the coating process of the raw material can be avoided.

[0227] Exemplarily, the rotation speed of the wet ball mill is 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, or 600 r / min, and the wet ball milling time is 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours. Optionally, the rotation speed of the wet ball mill is 300 r / min to 500 r / min, and the wet ball milling time is 1 hour to 6 hours.

[0228] Manufacturing method for the second type of composite material This manufacturing method includes the steps of forming a precursor that coats the surface of core 110 (having a Mohs hardness of 7 to 10) with a shell raw material, and sintering the precursor to mass transfer at least a portion of the shell raw material to the surface of core 110 to form shell 120 containing a first metal salt, thereby obtaining composite material 100, wherein the core material has a thermal conductivity of 20 W / m·k or more. The following description will be given taking as an example a case where core 110 is made of silicon nitride.

[0229] A method for producing a composite material 100 in which the core 110 is silicon nitride includes forming a precursor that coats the surface of the silicon nitride core with a shell raw material, and sintering the precursor to mass transfer at least a portion of the shell raw material to the surface of the silicon nitride core to form a shell 120 containing a first metal silicate, thereby obtaining the composite material 100.

[0230] In this manufacturing method, the shell material is first coated, and then during the sintering process, the shell material is mass-transferred to the surface layer of the silicon nitride, forming a relatively uniform and complete shell 120 on the surface of the silicon nitride core. This not only satisfies the thermal conductivity requirements of the composite material 100, but also reduces the hardness, thereby reducing the abrasion resistance of the device when it is subsequently used as a thermally conductive filler.

[0231] In some embodiments, the silicon nitride core has a tap density of 1.90 g / m 3 The high tap density of the core 110 provides an excellent combined effect between the core 110 and the shell 120, resulting in a composite material 100 with high thermal conductivity and low hardness.

[0232] Illustratively, the tap density of a silicon nitride core is 1.90 g / m 3 , 1.95g / m 3 , 2.00g / m 3 , 2.05g / m 3 , 2.10 g / m 3 , 2.15g / m 3 , 2.20 g / m 3 , 2.25g / m 3 , 2.30 g / m 3 , 2.35g / m 3 , 2.40g / m 3 or 2.45 g / m 3 Optionally, the tap density of the silicon nitride core is 1.90 g / m 3 ~2.4g / m 3 This results in a composite material 100 with high thermal conductivity and low hardness.

[0233] In some embodiments, the core material is silicon nitride, and the shell raw material comprises at least one of magnesium, magnesium oxide, magnesium hydroxide, organomagnesium, zinc, zinc oxide, zinc hydroxide, organozinc, zirconium, zirconium oxide, zirconium hydroxide, and organozirconium. During sintering, at least a portion of the shell raw material reacts with and mass transfers with the core 110, thereby forming a shell 120 containing the first metal salt. During sintering, the shell raw material reacts with the surface layer of the silicon nitride and mass transfers to the surface of the silicon nitride, thereby forming magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium zirconate silicate, aluminum zirconate silicate, zinc zirconate silicate, or the like. Thus, a shell containing the metal silicate is formed on the surface of the silicon nitride core, i.e., in situ, improving the thermal conductivity and reducing the hardness of the composite material 100.

[0234] Optionally, the shell raw material is at least one of magnesium, magnesium oxide, magnesium hydroxide, aluminum, aluminum oxide, aluminum hydroxide, zinc, zinc oxide, zinc hydroxide, zirconium, zirconium oxide, and zirconium hydroxide. The above shell raw materials are easily available and can easily react with silicon nitride to obtain a shell material under sintering conditions.

[0235] Furthermore, the shell raw material is at least one of magnesium oxide, aluminum oxide, zinc oxide, and zirconium oxide. When a metal oxide is used as the shell raw material, it can easily react with silicon nitride to form a metal silicate. When two types of metal oxides are used as the shell raw material, a shell material containing a second metal salt in addition to the metal silicate can be formed, resulting in a shell 120 containing multiple materials, thereby improving the performance of the composite material 100.

[0236] In some embodiments, the core material is silicon nitride, and sintering is performed for 3 to 8 hours at a temperature of 1000° C. to 1400° C. Under these conditions, silicon nitride chemically reacts with magnesium, magnesium oxide, magnesium hydroxide, organic magnesium, zinc, zinc oxide, zinc hydroxide, organic zinc, zirconium, zirconium oxide, zirconium hydroxide, organic zirconium, etc. to form magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium zirconate silicate, aluminum zirconate silicate, zinc zirconate silicate, etc.

[0237] Exemplary sintering temperatures are 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C, or 1400°C. Sintering times are 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours. Optionally, when the core material is silicon nitride, sintering is performed at a temperature of 1300°C to 1400°C for 3 hours to 8 hours.

[0238] In another embodiment, the core material is silicon nitride and the shell raw material is a hydrous silicate. During sintering, at least a portion of the hydrous silicate melts and mass transfers to the surface of the core 110, forming a silicate-containing shell 120. During sintering, the shell raw material melts and mass transfers to the surface of the silicon nitride core, and water separates, resulting in a silicate-containing shell 120. This increases the thermal conductivity of the composite material 100, which, when used as a thermally conductive filler, reduces abrasion to devices upon contact with the device.

[0239] Optionally, the hydrous silicate comprises one or more of hydrous magnesium silicate, hydrous sodium silicate, hydrous sodium aluminosilicate, and hydrous calcium aluminosilicate. The shell material obtained by sintering comprises magnesium silicate, sodium silicate, sodium aluminosilicate, calcium aluminosilicate, etc.

[0240] Alternatively, sintering may be performed for 3 to 8 hours at a temperature higher than the melting point of at least a portion of the hydrous silicate. For example, when the shell raw material is hydrous magnesium silicate (talc), sintering may be performed for 3 to 8 hours at 850°C to 1000°C.

[0241] In some embodiments, the D502 of the shell raw material is 0.05 μm to 10 μm, and the D503 of the silicon nitride core is 0.5 μm to 1000 μm, and the D502 / D503 satisfies 0.00001≦D502 / D503≦0.1. The small particle size of the shell raw material makes it easy to coat the surface of the silicon nitride core, which contributes to the formation of a core-shell structure with a uniform coating after sintering.

[0242] Illustratively, the D502 of the shell material is 0.05 μm, 0.1 μm, 0.15 μm, 0.3 μm, 0.5 μm, 0.7 μm, 0.9 μm, 1.1 μm, 1.3 μm, 1.5 μm, 1.7 μm, 1.9 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. The D503 of the silicon nitride core is 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 400 μm, 800 μm, or 1000 μm. Furthermore, the value of D502 / D503 is 0.00001, 0.00005, 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.05 or 0.1.

[0243] In this application, D503 of the silicon nitride core is 0.5 μm to 1000 μm, and D501 of the composite material 100 is 0.5 μm to 1000 μm. This does not mean that the particle size of the composite material 100 obtained after coating and sintering the core 110 is the same as the particle size of the core 110. Usually, the particle size of the composite material 100 obtained by coating and sintering is slightly larger than the particle size of the core 110. This will not be explained here.

[0244] Optionally, the D503 of the silicon nitride core is 0.5 μm to 500 μm, and satisfies 0.0001≦D502 / D503≦0.1. The combination of core material and shell material that satisfies this condition provides a better precursor coating effect and a more uniform shell 120, thereby improving the thermal conductivity of the composite material 100 and reducing its hardness.

[0245] Furthermore, the silicon nitride core has a D503 of 0.5 μm to 140 μm, and satisfies 0.0003≦D502 / D503≦0.1. By combining silicon nitride core and shell materials that satisfy this condition, the resulting composite material 100 can be easily added to a substrate as a thermally conductive filler, contributing to applications in the field of thermal conduction.

[0246] In some embodiments, the mass ratio of the shell material in the precursor is 1% to 30%, which allows a good shell 120 to be formed by sintering and also prevents the shell 120 from being too thick, which can affect thermal conductivity to some extent.

[0247] For example, the mass ratio of the shell raw material in the precursor is 1%, 3%, 5%, 8%, 10%, 15%, 20%, 25%, or 30%. Optionally, the mass ratio of the shell raw material in the precursor is 5% to 20%. This allows the shell 120 to completely cover the core 110, preventing the shell 120 from being too thick. This increases the thermal conductivity of the composite material 100 and reduces the hardness of the composite material 100.

[0248] In some embodiments, the method for forming the precursor includes mixing and coating a silicon nitride core, a shell material, and a coating aid. By using the coating aid to coat, the shell material is uniformly adhered to the surface of the silicon nitride core, and during the sintering process, the shell material undergoes mass transfer, ultimately forming a complete coated shell 120. This allows the shell 120 to coat the surface of the silicon nitride core more uniformly.

[0249] Optionally, the coating aid may include a silicon-containing coating aid, which allows the shell raw material to react with the silicon nitride and the coating aid at the same time, resulting in a more uniform coating, a better coating effect, and a less agglomerated product. The composite material has low hardness and higher thermal conductivity.

[0250] Optionally, the coating aid includes tetraethyl orthosilicate. Tetraethyl orthosilicate can be used as a coating aid while also providing silicon, allowing the shell raw material to react with the tetraethyl orthosilicate while also reacting with the silicon nitride core. This results in a more uniform coating, a better coating effect, a product that is less likely to agglomerate, and a higher thermal conductivity for the composite material 100. Furthermore, the coating aid is tetraethyl orthosilicate.

[0251] In other embodiments, the coating aid may be polyvinyl butyral resin, acrylic resin, etc., but is not limited to this application. Any coating aid that can effectively adhere the shell material to the surface of the silicon nitride core is within the scope of protection of this application.

[0252] In some embodiments, the mass ratio of the coating aid in the precursor is 1% to 15%, which improves the coating effect and prevents the performance of the composite material 100 from being affected by excessive use of the coating aid.

[0253] For example, the mass ratio of the coating additive in the precursor is 1%, 2%, 4%, 6%, 9%, 12%, or 15%. Optionally, the mass ratio of the coating additive in the precursor is 3% to 10%, which improves the coating effect, avoids excessive use of the coating additive, and allows more shell raw material to react with the silicon nitride core.

[0254] In some embodiments, the coating is performed using a wet ball mill, with the rotation speed of the wet ball mill being 200 r / min to 600 r / min, and the wet ball milling time being 1 hour or more. By performing the coating using a wet ball mill, the coating aid can be utilized, the shell raw material can more uniformly coat the surface of the silicon nitride core, and agglomeration of the core 110 that occurs during the coating process of the raw material can be avoided.

[0255] Exemplarily, the rotation speed of the wet ball mill is 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, or 600 r / min, and the wet ball milling time is 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours. Optionally, the rotation speed of the wet ball mill is 300 r / min to 500 r / min, and the wet ball milling time is 1 hour to 6 hours.

[0256] Manufacturing method for the third type of composite material This manufacturing method includes the steps of forming a precursor that coats the surface of core 110 (easily hydrolyzable core) with a shell raw material, and sintering the precursor to cause at least a portion of the shell raw material to react with core 110 and undergo mass transfer to form shell 120 containing a metal salt, thereby obtaining composite material 100, wherein the core material has a thermal conductivity of 20 W / m·k or more. The following description will be given taking the case where core 110 is aluminum nitride as an example.

[0257] A method for producing a composite material 100 having an aluminum nitride core 110 includes forming a precursor that coats the surface of the aluminum nitride core with a shell material, and sintering the precursor to react at least a portion of the shell material with the aluminum nitride core to form an aluminate-containing shell 120, thereby obtaining the composite material 100.

[0258] In this manufacturing method, the aluminum nitride core is first coated with a shell material, and then, during the sintering process, the shell material reacts with the surface layer of the aluminum nitride core and undergoes mass transfer, forming a relatively uniform and complete shell 120 on the surface of the aluminum nitride core. This not only satisfies the thermal conductivity requirements of the composite material 100, but also improves the hydrolysis stability of the composite material 100, making it suitable for use in high-humidity environments.

[0259] In some embodiments, the tap density of the aluminum nitride core 110 is 2.0 g / m 3 The high tap density of the core 110 provides an excellent combined effect between the core 110 and the shell 120, resulting in a composite material 100 with high thermal conductivity and good hydrolytic stability.

[0260] Illustratively, the tap density of an aluminum nitride core is 2.0 g / m 3 , 2.05g / m 3 , 2.10 g / m 3 , 2.15g / m 3 , 2.20 g / m 3 , 2.25g / m 3 , 2.30 g / m 3 , 2.35g / m 3 , 2.40g / m 3 or 2.45 g / m 3 Optionally, the tap density of the aluminum nitride core is 2.1 g / m 3 ~2.4g / m 3 This results in a composite material 100 with higher thermal conductivity and better hydrolytic stability.

[0261] In some embodiments, the core material is aluminum nitride and the shell material comprises at least one of zinc oxide, magnesium oxide, calcium oxide, potassium oxide, and silicon oxide. When aluminum nitride reacts with the shell material, magnesium aluminate, zinc aluminate, calcium aluminate, potassium aluminate, aluminum silicate, etc. is obtained. This results in the formation of an in-situ aluminate-containing shell 120 on the surface of the core 110, which provides the composite material 100 with high thermal conductivity and good hydrolytic stability.

[0262] In some embodiments, D502 of the shell raw material is 0.05 μm to 10 μm, and D503 of the aluminum nitride core is 0.5 μm to 1000 μm, and the relationship 0.00001≦D502 / D503≦0.1 is satisfied. The shell raw material has a small particle size, which makes it easy to coat the surface of the aluminum nitride core, and this contributes to the formation of a core-shell structure with a uniform coating after sintering.

[0263] Illustratively, the D502 of the shell material is 0.05 μm, 0.1 μm, 0.15 μm, 0.3 μm, 0.5 μm, 0.7 μm, 0.9 μm, 1.1 μm, 1.3 μm, 1.5 μm, 1.7 μm, 1.9 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, and the D503 of the aluminum nitride core is 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 400 μm, 800 μm, or 1000 μm. Furthermore, the value of D502 / D503 is 0.00001, 0.00005, 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.05 or 0.1.

[0264] In this application, D503 of the aluminum nitride core is 0.5 μm to 1000 μm, and D501 of the composite material 100 is 0.5 μm to 1000 μm. This does not mean that the grain size of the composite material 100 obtained after coating and sintering the core 110 is the same as the grain size of the core 110. Usually, the grain size of the composite material 100 obtained by coating and sintering is slightly larger than the grain size of the core 110. This will not be explained here.

[0265] Optionally, the aluminum nitride core has a D503 of 0.5 μm to 500 μm, and satisfies 0.0001≦D502 / D503≦0.1. The combination of core and shell materials that satisfies this condition provides a better precursor coating effect and a more uniform shell 120, thereby improving the thermal conductivity and hydrolytic stability of the composite material 100.

[0266] Furthermore, the D503 of the aluminum nitride core is 0.5 μm to 140 μm, and satisfies 0.0003≦D502 / D503≦0.1. By combining silicon carbide core and shell materials that satisfy this condition, the resulting composite material 100 can be easily added to a substrate as a thermally conductive filler, contributing to applications in the field of thermal conduction.

[0267] In some embodiments, the mass ratio of the shell material in the precursor is 1% to 30%, which allows a good shell 120 to be formed by sintering and also prevents the shell 120 from being too thick, which can affect thermal conductivity to some extent.

[0268] For example, the mass ratio of the shell raw material in the precursor is 1%, 3%, 5%, 8%, 10%, 15%, 20%, 25%, or 30%. Optionally, the mass ratio of the shell raw material in the precursor is 5% to 20%. This allows the shell 120 to completely cover the core 110, preventing the shell 120 from becoming too thick. This increases the thermal conductivity of the composite material 100 and improves its hydrolytic stability.

[0269] In some embodiments, the method for forming the precursor includes mixing and coating an aluminum nitride core, a shell material, and a coating aid. By using the coating aid to coat, the shell material is uniformly adhered to the surface of the aluminum nitride core, and during the sintering process, the shell material undergoes mass transfer, ultimately forming a complete coated shell 120. This allows the shell 120 to more uniformly coat the surface of the aluminum nitride core.

[0270] Optionally, the coating aid may be at least one of tetraethyl orthosilicate, polyvinyl butyral resin, and acrylic resin, but is not limited thereto. Any coating aid that can effectively adhere the shell material to the surface of the silicon carbide core is within the scope of protection of the present application.

[0271] In some embodiments, the mass ratio of the coating aid in the precursor is 1% to 15%, which improves the coating effect and prevents the performance of the composite material 100 from being affected by excessive use of the coating aid.

[0272] For example, the mass ratio of the coating aid in the precursor is 1%, 2%, 4%, 6%, 9%, 12%, or 15%. Optionally, the mass ratio of the coating aid in the precursor is 3% to 10%, which improves the coating effect and avoids excessive use of the coating aid, allowing more shell raw material to react with the aluminum nitride core.

[0273] In some embodiments, the coating is performed using a wet ball mill, with the rotation speed of the wet ball mill being 200 r / min to 600 r / min, and the wet ball milling time being 1 hour or more. By performing the coating using a wet ball mill, the coating aid can be utilized, the shell raw material can more uniformly coat the surface of the core 110, and agglomeration of the core 110 that occurs during the coating process of the raw material can be avoided.

[0274] Exemplarily, the rotation speed of the wet ball mill is 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, or 600 r / min, and the wet ball milling time is 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours. Optionally, the rotation speed of the wet ball mill is 300 r / min to 500 r / min, and the wet ball milling time is 1 hour to 6 hours.

[0275] In other embodiments, the coating device may be a planetary ball mill, a ball mill, a sand mill, a stirring device, or the like.

[0276] In some embodiments, the core material is aluminum nitride, and sintering is performed at a temperature of 1400°C to 1800°C for 3 to 8 hours, under which aluminum nitride reacts with substances such as zinc oxide, magnesium oxide, calcium oxide, potassium oxide, and silicon oxide to produce magnesium aluminate, zinc aluminate, calcium aluminate, potassium aluminate, and aluminum silicate.

[0277] Exemplary sintering temperatures are 1400°C, 1450°C, 1500°C, 1550°C, 1600°C, 1650°C, 1700°C, 1750°C, or 1800°C. Sintering times are 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours. Optionally, the core material is aluminum nitride, and sintering is performed at a temperature of 1500°C to 1700°C for 3 hours to 8 hours.

[0278] In order to clarify the purpose, technical features and advantages of the examples of the present application, the technical features in the examples of the present application will be explained clearly and completely below. In the examples, specific conditions are not specified, but the experiments can be carried out under conventional conditions or under conditions recommended by the manufacturer. For reagents or equipment used without specifying the manufacturer, conventional products available on the market can be used. Example This example provides a method for manufacturing a composite material, which includes the following steps:

[0279] (1) The core, coating aid, and shell raw materials are mixed with pure water, placed in a planetary ball mill, and ball milled and mixed for 6 hours at 500 r / min. The slurry is then filtered, and the powder is dried in an oven at 90°C for 12 hours and passed through a 60-mesh sieve to obtain a precursor.

[0280] (2) The precursor is placed in an alumina sagger, sintered, and then naturally cooled to room temperature to obtain a composite material.

[0281] The manufacturing conditions of the composite material are shown in Tables 1 to 5 below. In Table 1, the core is a silicon carbide material (thermal conductivity is 90 W / m·k), and the particle size distribution is D10 88 μm, D50 124 μm, D90 186 μm, and the tap density is 1.94 g / cm 3 In Table 2, the shell raw material is magnesium oxide, with a particle size D50 of 1.9 μm and a mass ratio of 10% magnesium oxide in the precursor. In Table 3, the coating aid is tetraethyl orthosilicate. In Table 5, the thermal conductivity of silicon nitride is 60 W / m·k and that of aluminum nitride is 100 W / m·k.

[0282] [Table 1]

[0283] [Table 2]

[0284] [Table 3]

[0285] [Table 4]

[0286] [Table 5] The composite material was passed through a 25 μm sieve to remove the shell material that did not cover the core surface, and the parameters and performance of the sieved composite materials of the Examples and Comparative Examples were measured, and the results are shown in Tables 6 to 10. The measurement methods are as follows.

[0287] (1) Tap density (unit: g / cm 3 The method for measuring the density of powder or particles is as follows: Using a tap density meter, a measuring cylinder containing powder or particles is fixed to a mechanical vibrator, and a vibration motor is used to vibrate the mechanical vibrator up and down in the vertical direction, causing the measuring cylinder containing the powder or particles to vibrate rhythmically in accordance with the vibration of the mechanical vibrator. As the number of vibrations increases, the powder or particles in the measuring cylinder are tapped, and after the number of vibrations reaches a predetermined number, the vibration of the mechanical vibrator is stopped and the volume of the measuring cylinder is read. The tap density of the tapped powder or particles is calculated based on the definition of density as mass / volume.

[0288] (2) Specific surface area (unit: m 2 / g) is measured based on GB / T19587-2004 "Measurement of the specific surface area of ​​solid materials by the gas adsorption BET method."

[0289] (3) The ratio of shell thickness to particle size is calculated based on (D50 particle size of composite material - D50 particle size of core) / D50 particle size of composite material.

[0290] (4) The core-to-shell mass ratio (unit: %) is measured by analyzing using the RIR method after XRD measurement. The principle is that the ratio of the integrated intensities of the strongest diffraction peaks of the shell material and the core material is the RIR value, and the integrated intensity of the core material can be calculated from the integrated intensity of the shell material / RIR value. In the case of a mixture, all components of the substance can be calculated in this way, and the content of a certain component can be finally obtained by normalization.

[0291] (5) Particle size distribution of the composite material (unit: μm), measured using a BT particle size analyzer and GBT 19077-2016 particle size distribution laser diffraction method.

[0292] (6) The mass ratio (%) of the under-sieve material is calculated as follows: M kg of composite material with a bulk volume of 200 ml is weighed out and placed in a container (volume 500 ml) equipped with a stirrer, and after stirring at 500 r / min for 10 minutes, the material is passed through a sieve (the R34 sieve has an opening of 18 μm, and the other sieves have an opening of 25 μm), and the mass of the under-sieve material is measured and designated as M kg. The mass ratio of the under-sieve material is calculated from M / M × 100%.

[0293] (7) The viscosity (unit: mPa.s) of the silica gel mixture is measured as follows. For a D50 of 80 μm to 150 μm, 4.8 parts by weight of vinyl silicone oil with a viscosity of 100 mPa.s, 20 parts by weight of the composite material, 21 parts by weight of spherical alumina NSM-1S, 30 parts by weight of spherical alumina BAK-10, and 25 parts by weight of spherical alumina BAK-120 are mixed, and the mixture is first treated at a rotation speed of 1100 r / min under a vacuum of 1000 Pa for 1 minute, and then at a rotation speed of 1500 r / min under a vacuum of 40 Pa for 1 minute to obtain a silica gel mixture. The mixture is measured using an Anton Paar rheometer at 25°C for 0.1 to 100 s. -1 Under the condition of 1s -1 The viscosity at this point is measured to obtain the viscosity value of the silica gel mixture.

[0294] The measurement method for D50 between 60 μm and 80 μm is as follows: 5.2 parts by weight of vinyl silicone oil with a viscosity of 100 mPa.s, 52 parts by weight of the composite material, 15 parts by weight of spherical alumina NSM-1S, and 33 parts by weight of spherical alumina BAK-5 are mixed, and the mixture is first treated at a rotation speed of 1100 r / min under a vacuum of 1000 Pa for 1 minute, and then at a rotation speed of 1500 r / min under a vacuum of 40 Pa for 1 minute to obtain a silica gel mixture. The measurement is performed using an Anton Paar rheometer at 25°C for 0.1 to 100 s. -1 Under the condition of 1s -1 The viscosity is measured at this point to obtain the viscosity value of the silica gel mixture.

[0295] The measurement method for D50 between 30 μm and 50 μm is as follows: 5.6 parts by weight of vinyl silicone oil with a viscosity of 100 mPa.s, 60 parts by weight of the composite material, and 40 parts by weight of spherical alumina BAK-5 are mixed, and the mixture is first treated at a rotation speed of 1100 r / min under a vacuum of 1000 Pa for 1 minute, and then at a rotation speed of 1500 r / min under a vacuum of 40 Pa for 1 minute to obtain a silica gel mixture. The mixture is measured using an Anton Paar rheometer at 25°C for 0.1 to 100 s. -1 Under the condition of 1s -1 The viscosity is measured at this point to obtain the viscosity value of the silica gel mixture.

[0296] (8) The thermal conductivity (unit: W / m·k) of the pad is measured as follows: The silica gel mixture from measurement (7) is solidified at 120°C for 30 minutes to form a silicone pad, and then the thermal conductivity of the pad is measured using the HotDisk method.

[0297] (9) The method for measuring the dielectric breakdown voltage (unit: KV / mm) of the pad is as follows: For the silicone pad in measurement (8), measurements are performed based on ASTM D149, the test method for dielectric breakdown voltage and dielectric strength at industrial power frequencies for solid electrical insulating materials, to obtain the dielectric breakdown voltage of the pad.

[0298] (10) The method for measuring the aging resistance of the pad (unit: KV / mm) is as follows: The silicone pad of measurement (8) is left under conditions of 85% humidity and 85°C for 1000 hours, and its breakdown voltage (unit: KV / mm) is measured based on the method of measurement (9) to obtain the aging resistance of the composite material.

[0299] (11) The method for measuring the hardness of the pad is as follows: For the silicone pad of measurement (8), the Shore hardness is measured based on the standard test method for rubber properties of ASTM D2240.

[0300] (12) The hydrolytic stability of the pad is measured as follows: The composite material and pure water are mixed at a mass ratio of 1:10, and the pH value of the mixture is measured. The temperature of the solution is then raised to 90°C, and the mixture is left for 100 hours, and the pH value of the mixture is then measured. The aluminum nitride and pure water are mixed at a mass ratio of 1:10, and the pH value of the mixture is measured. The temperature of the solution is then raised to 90°C, and the mixture is left for 3 hours, and the pH value of the mixture is then measured.

[0301] [Table 6] As can be seen from Tables 1 and 6, the composite materials of Examples R1 to R9 have a low amount of undersize, indicating that the shell and core in these composite materials are strongly bonded and that the materials do not essentially break or peel under stirring conditions. The silica gel mixture obtained by adding these composite materials to vinyl silicone oil as a thermally conductive filler has an appropriate viscosity, high thermal conductivity, and a high breakdown voltage. Furthermore, after aging tests, the breakdown voltage remained essentially unchanged, indicating good aging resistance.

[0302] In D1 and D2, the coated shell raw material was not sintered, and after the resulting composite material was stirred, a large amount of undersize material remained. The viscosity of the silica gel mixture formed from this composite material was high, indicating that the dielectric breakdown voltage of the pad was very low. Based on the inventors' investigations, the following is speculated to be the cause: During the stirring and mixing process of the composite raw material and vinyl silicone oil, the shell raw material detached from the core, and a large amount of the shell raw material was mixed alone into the silica gel mixture, increasing the viscosity of the silica gel mixture. Furthermore, the shell powder detached from the core, exposing the core, resulting in a lower dielectric breakdown voltage of the pad. Furthermore, after conducting an aging test, the dielectric breakdown voltage further decreased, indicating poor aging resistance.

[0303] In D3, silicon carbide was directly sintered under an oxygen atmosphere. Silicon dioxide was formed on the surface of silicon carbide, and the viscosity of the silica gel mixture formed by the composite material was low, which increased the breakdown voltage of the pad (compared to pure silicon carbide). However, the increase in the breakdown voltage of the pad was not significant, indicating that the thermal conductivity of the pad was low.

[0304] In D4, it is shown that the breakdown voltage of the pads formed by adding pure silicon carbide as a thermally conductive filler to the silica gel mixture is low.

[0305] Comparing R2, R3, and R4, it can be seen that when the shell materials are essentially the same (R2 and R3), the longer the sintering time (R3), the better the performance of the resulting composite material. When sintering for 5 hours at a sintering temperature of 1300°C (R3 and R4), the composite with a 30% magnesium oxide shell material exhibits better performance. This shows that when the sintering temperature is low and the sintering time is short, the higher the amount of shell material added, the more sufficient the reaction between the shell material and the core, resulting in better composite performance.

[0306] In contrast to R8 and R9, R1 has a silicon carbide core and tetraethyl orthosilicate as the coating additive. The composite material obtained from this material was added to vinyl silicone oil as a thermally conductive filler, and the resulting silica gel mixture was solidified to form a silicone pad. It was found that this silicone pad exhibited higher thermal conductivity and breakdown voltage. R8 and R9 have a higher core ratio. The inventors speculate that when the coating additive is polyvinyl butyral resin or acrylic resin, many of the raw materials remain unreacted, resulting in insufficient reaction of the core material and a lower breakdown voltage for the final composite.

[0307] [Table 7] As can be seen from Tables 2 and 7, the silica gel mixtures obtained by adding the composite materials of Examples R11 to R13 to vinyl silicone oil as thermally conductive fillers have low viscosity, high thermal conductivity, and high breakdown voltage (compared to R10 and R14). Furthermore, after aging tests, the breakdown voltage remained essentially unchanged, indicating good aging resistance. As can be seen from the above, the tap density of the silicon carbide core was 1.90 g / cm. 3 ~2.1g / cm 3 If so, the performance of the composite material is better.

[0308] [Table 8] As can be seen from Tables 3 and 8, in the present invention, the shell material in R15 is talc. After sintering, magnesium silicate is melted and water is decomposed to obtain a composite material with a magnesium silicate shell. The pad formed by solidifying the silica gel mixture made from this composite material has high thermal conductivity and breakdown voltage. The inventors speculate that the talc undergoes mass transfer to the surface of the silicon carbide shell during the melting process at high temperatures, resulting in a composite material with excellent coating properties.

[0309] In contrast to R16, composite materials were produced in R17 to R19, where the D503 of the core silicon carbide was approximately 125 μm and the D502 of the shell raw material was approximately 2 μm. Pads formed by solidifying the silica gel mixture formed from this composite material had both high thermal conductivity and high breakdown voltage. The inventors speculate that the performance of the composite material obtained will be better if the D503 of the core material is 100 μm to 140 μm and the D502 of the shell raw material is 1.5 μm to 2 μm.

[0310] [Table 9] As can be seen from Tables 4 and 9, in addition to composites with a silicon carbide core and a magnesium silicate shell, there are also composites with a silicon carbide core and a mixture of magnesium silicate and magnesium aluminate (R20), or a zinc silicate shell (R21-R23, R26-R28), or a mixture of zinc silicate and zinc aluminate (R24 and R25), or an aluminum silicate shell (R29), or a zirconium silicate shell (R30), or a yttrium silicate shell (R31), or a cerium silicate shell (R32). The inventors speculate that any substance capable of chemically reacting with the silicon carbide core under sintering conditions can be used as the shell raw material, resulting in composites with shells composed of various components. Comparing R24 and R26, the composite material obtained with the shell material containing both zinc silicate and zinc aluminate (R24) performs better than the composite material with a zinc silicate shell (R26). The pads formed by solidifying the silica gel mixture formed from this composite have both high thermal conductivity and breakdown voltage. The inventors speculate that the addition of zinc aluminate increases the thermal conductivity of the composite, resulting in a higher breakdown voltage.

[0311] As can be seen from the comparison between R24 and R25, adding more zinc silicate (R25) adversely affects the breakdown voltage of the composite. The inventors speculate that the composite will perform better if the shell material is zinc aluminate and magnesium silicate and the magnesium silicate content is 20% to 50%.

[0312] As can be seen from Tables 6 to 9, the performance of the composite material obtained when the core is silicon carbide and the shell is magnesium silicate is better. In the composite material, when the core is silicon carbide, the core proportion is 60% to 75%, and the shell is magnesium silicate, the performance of the composite material obtained is better.

[0313] As can be seen from Tables 6 to 9, the core is silicon carbide, the shell is magnesium silicate, the core ratio is 60% to 75%, and the viscosity of the thermally conductive mixed material is 1×10 6 mpa·s~1.6×10 6 When the viscosity is higher than 1000kJ / s, the composite material has better performance.

[0314] [Table 10] As can be seen from Tables 5 and 10, the hardness of the composite material is low in R36, and when this is used as a thermally conductive filler, it can reduce the wear of the composite material on the device and has excellent thermal conductivity.

[0315] In R37, the composite material has high hydrolysis stability, and when used as a thermally conductive filler, it can be used for long periods of time under high temperature and humidity conditions without affecting thermal conductivity.

[0316] Test Example Figure 3 is an SEM image (magnified 200x) of the precursor of Example R1 of the present application. Figure 4 is an SEM image (magnified 200x) of the composite material of Example R1 of the present application. Figure 5 is an SEM image (magnified 500x) of the precursor of Example R21 of the present application. Figure 6 is an SEM image (magnified 500x) of the composite material of Example R21 of the present application. As can be seen from Figures 3 to 6, when the shell raw material before sintering covers the surface of the core, the uniformity is poor, making it difficult to achieve complete coverage. Many particulate matter aggregates on the surface and adheres to the core surface. After sintering, the shell uniformly covers the surface of the core, making it easy to achieve complete coverage. It also forms a continuous coating layer, forming a complete shell, and the particulate matter does not aggregate and adhere to the core surface. The inventors speculate that during the sintering process, the shell raw material, magnesium oxide or zinc oxide, reacts with the core silicon carbide and undergoes mass transfer to the surface of the core, forming a coating layer of magnesium silicate or zinc silicate, which results in a more uniform coating layer, a better coating effect, easier complete coating, and better overall performance of the composite material.

[0317] Figure 7 is an SEM image (magnified 2000 times) of the composite material of Example R28 of the present application. Figure 8 is an SEM image (magnified 2000 times) of the composite material of Example R31 of the present application. As can be seen from Figures 7 and 8, the core in region A is exposed and not completely coated with shell B. This is because the content of the shell raw material is low and the content of the coating aid is high, making it difficult for the shell material produced by the reaction to coat the entire surface of the core material.

[0318] The composite material was analyzed by XRD. The measurement conditions were a copper target, a tube voltage of 20 kV to 60 kV, a tube current of 20 mA to 60 mA, a goniometer radius of 185 mm, and a high-speed array detector. Figure 9 shows the XRD pattern of the precursor of Example R1. Figure 10 shows the XRD pattern of the composite material of Example R1. Figure 11 shows the XRD pattern of the precursor of Example R21. Figure 12 shows the XRD pattern of the composite material of Example R21. As can be seen from Figures 9 and 10, the surface of the silicon carbide was coated with magnesium oxide before sintering, and magnesium silicate was formed after sintering, indicating that the magnesium oxide reacted to form magnesium silicate. Furthermore, the silicon carbide content in the precursor was 86%, and the silicon carbide content in the sintered composite was 71%, indicating that the silicon carbide content decreased after the reaction. As can be seen from this, silicon carbide reacts during the sintering process and participates in the synthesis of magnesium silicate. Figures 11 and 12 show that zinc oxide coats the surface of silicon carbide before sintering, and zinc silicate coats the surface of silicon carbide after sintering, indicating that zinc oxide reacted to form zinc silicate. Furthermore, the precursor contains 65% silicon carbide, and the sintered composite contains 77% silicon carbide. When zinc oxide, the shell material, accounts for 30% of the precursor, much of the shell material did not coat the core surface and was unreacted. The unreacted shell material was removed by sieving before measuring the composite's performance.

[0319] The composite material was measured by XPS. The measurement conditions were a collection time of 2 minutes 30.4 seconds, 10 scans, Al-Kα, a spot size of 500 μm, CAE pass energy of 30.0 eV, photoelectron kinetic energy of 0.050 eV, and bond energy of 301. Peak fitting was performed on the XPS pattern of the composite material. Figure 13 shows the XPS Si2p spectroscopy of the precursor of Example R1. Figure 14 shows the XPS Si2p spectroscopy of the composite material of Example R1. Figure 15 shows the XPS Mg1s spectroscopy of the precursor of Example R1. Figure 16 shows the XPS Mg1s spectroscopy of the composite material of Example R1. 13 to 16, the precursor before sintering contains Si-C chemical bonds with bond energies of 100 eV to 101 eV and Mg-O chemical bonds with bond energies of 1303.9 eV to 1305 eV. The composite material after sintering contains Si-C chemical bonds with bond energies of 100 eV to 101 eV, O-Si-O chemical bonds with bond energies of 105 eV to 106 eV, and Mg-O-Si chemical bonds with bond energies of 1305.3 eV to 1306.7 eV. This indicates that magnesium oxide was converted to magnesium silicate after sintering.

[0320] FIG. 17 is an XPS Si2p spectroscopy analysis diagram of the precursor of Example R21 of the present application. FIG. 18 is an XPS Si2p spectroscopy analysis diagram of the composite material of Example R21 of the present application. FIG. 19 is an XPS Mg1s spectroscopy analysis diagram of the precursor of Example R21 of the present application. FIG. 20 is an XPS Mg1s spectroscopy analysis diagram of the composite material of Example R21 of the present application. As can be seen from FIGS. 17 to 20, the precursor before sintering contains Si-C chemical bonds with bond energies of 100 eV to 101 eV and Zn-O chemical bonds with bond energies of 1022 eV to 1044 eV. The sintered composite material contains Si-C chemical bonds with bond energies of 100 eV to 101 eV and Zn-O-Si chemical bonds with bond energies of 1022.6 eV to 1044.8 eV. This indicates that magnesium oxide was converted to zinc silicate after sintering.

[0321] EDS measurements were performed under the following conditions: FOV: 13.4 μm, Mode: 15 kV-Image, Detector: BSD Full. FIG. 21 shows the EDS line scan direction (direction indicated by the arrow) of the precursor of Example R21 of the present application. FIG. 22 shows the EDS line scan direction (direction indicated by the arrow) of the precursor of Example R21 of the present application. FIG. 23 shows the EDS line scan direction (direction indicated by the arrow) of the precursor of Example R21 of the present application. FIG. 24 shows the EDS line scan direction (direction indicated by the arrow) of the composite material of Example R21 of the present application. FIG. 26 shows the EDS line scan direction (direction indicated by the arrow) of the composite material of Example R21 of the present application. FIG. 27 shows the EDS line scan direction (direction indicated by the arrow) of the composite material of Example R21 of the present application. FIG. 28 shows the EDS line scan direction (direction indicated by the arrow) of the composite material of Example R21 of the present application. FIG. 29 shows the EDS line scan direction (direction indicated by the arrow) of the composite material of Example R21 of the present application. Figure 30 shows an EDS line scan of zinc from the composite material of Example R21 of the present application. As can be seen from Figures 21 to 24, before EDS measurement, the precursor was cut. During cutting, powder fell off the precursor, and the coating material detached from the core. The resulting carbon and silicon EDS line scans were essentially horizontal, indicating that the silicon content remained essentially unchanged. This indicates poor bonding between the coating material and the core in the precursor. As can be seen from Figures 25 to 30, the precursor was cut before EDS measurement. After cutting, the shell and core were clearly formed. The shell and core were in close contact with each other without any gaps, and their crystal grains were directly connected, demonstrating good bonding between them. Furthermore, the EDS line scans of carbon and silicon obtained show a sudden rise in the middle of the curve (within the black frame), while the EDS line scans of oxygen and zinc show a sudden drop in the middle of the curve (within the black frame), indicating that the elemental changes are continuous and uninterrupted, with no gap between the shell and core.

[0322] Figure 31 is an SEM image (magnified 6400 times) of the composite material of Example R1 after cutting. Figure 32 is an SEM image (magnified 6400 times) of the composite material of Example R21 after cutting. Figure 33 is an SEM image (magnified 60,000 times) of the composite material of Example R1 after cutting. As can be seen from Figures 31 and 32, the shell and core of the composite material of the present invention are tightly connected with no gaps, and the crystal grains of the shell and the crystal grains of the core are connected, resulting in superior performance of the resulting composite material. As can be seen from Figure 33, when this composite material is magnified 60,000 times, there is no gap between the core A and the shell B, and a constant transition layer C exists. This indicates that there are no gaps between the core and shell of the composite material of the present invention, the coating effect is good, and the performance of the resulting composite material is excellent.

[0323] As can be seen from Figures 3, 4, 9-10, 13-16, 31, and 33, when producing a composite material in which magnesium silicate coats silicon carbide, silicon carbide reacts with magnesium oxide to form magnesium silicate, eliminating any gaps between the silicon carbide and magnesium silicate. Furthermore, magnesium silicate is obtained through a chemical reaction, and the magnesium silicate coating layer obtained through the chemical reaction is a continuous coating layer. Furthermore, because a chemical reaction occurs during sintering, the shell material does not contain a binder. Furthermore, the magnesium silicate obtained after sintering is not an agglomerate of multiple particles adhered to the surface of the silicon carbide, but rather a complete shell, with the silicon carbide and magnesium silicate crystal grains directly connected.

[0324] As can be seen from Figures 5, 6, 11, 12, 17-30, and 32, when producing a composite material in which zinc silicate coats silicon carbide, the silicon carbide reacts with zinc oxide to form zinc silicate, eliminating any gaps between the silicon carbide and zinc silicate. Furthermore, the zinc silicate is obtained by a chemical reaction, and the zinc silicate coating layer obtained by the chemical reaction is a continuous coating layer. Furthermore, because a chemical reaction occurs during sintering, the shell material does not contain a binder. Furthermore, the zinc silicate obtained after sintering is not an agglomerate of multiple particles adhered to the surface of the silicon carbide, but rather a complete shell, with the silicon carbide and zinc silicate crystal grains directly connected.

[0325] The above-described embodiments are only some of the embodiments of the present application, and not all of the embodiments. The detailed description of the embodiments of the present application merely illustrates selected embodiments of the present application and does not limit the scope of the present application to be protected. All other embodiments that a person skilled in the art can obtain based on the embodiments of the present application without using his or her inventive ability fall within the scope of protection of the present application. [Explanation of symbols]

[0326] 100, composite materials 110, Core 120, Shell

Claims

1. A composite material comprising: a core and a shell covering the outside of the core, the core material having a thermal conductivity of 20 W / m·k or more, and the shell material containing a first metal salt; The composite material satisfies the following conditions: D50 of the composite material １ The composite material having a mass of M and a mass of A is placed in a container equipped with a stirrer, and stirred for 10 minutes under the conditions of a loading coefficient of 0.4 and 500 r / min, and passed through a sieve of (0.1 to 0.3) x A, with the amount of under-sieve matter being 0.05 x M or less. A composite material characterized by:

2. A composite material comprising a core and a shell covering the outside of the core, wherein the core material has a thermal conductivity of 20 W / m·k or more, and the shell material contains a first metal salt obtained by sintering.

3. The core includes a core and a shell covering the outside of the core. the shell material contains a first metal salt, and the core material has a thermal conductivity of 20 W / m·k or more; at least one element of the core material is the same as at least one element of the shell material; A transition layer is provided between the core and the shell, and the transition layer has a gradually decreasing content of at least one element and a gradually increasing content of at least one element from the outside to the inside. A composite material characterized by:

4. The composite material satisfies one or more of the following conditions: (1) D50 of the composite material １ The composite material having a mass of M and a mass of A is placed in a container equipped with a stirrer, and stirred under the conditions of a loading coefficient of 0.4 and 500 r / min, and then passed through a sieve of (0.1 to 0.3) x A, and the amount of material that falls under the sieve is 0.02 x M or less; (2) There is no gap between the core and the shell, (3) the shell is a complete shell; (4) The shell is a continuous coating layer, (5) The composite material does not contain a binder; (6) The shell is not formed by an aggregation of a plurality of particles adhered to the surface of the core, (7) The grains of the core are directly connected to the grains of the shell; (8) The shell covers at least 85% of the surface of the core; (9) The mass ratio of the core is 95% or less, (10) The thermal conductivity of the core material is 20 W / m·k to 500 W / m·k; (11) D50 of the composite material １ is 0.5 μm or more, (12) D50 of the composite material １ is 0.5 μm to 150 μm, and 0.5≦(D90 １ -D10 １ ) / D50 １ ≦1.5 is satisfied, (13) The ratio of the thickness of the shell to the particle size of the composite material is 0.02 to 0.1; (14) The tap density of the composite material is 1.85 g / m ３ That's all, (15) The specific surface area of ​​the composite material is 4 m ２ / g or less The composite material according to any one of claims 1 to 3.

5. The composite material satisfies one or more of the following conditions: (16) The shell completely covers the core, (17) The mass ratio of the core is 60% to 75%; (18) The thermal conductivity of the core material is 50 W / m·k to 250 W / m·k; (19) D50 of the composite material １ is 0.5 μm to 500 μm, (20) D50 of the composite material １ is 0.5 μm to 20 μm, and 0.5≦(D90 １ -D10 １ ) / D50 １ ≦1 is satisfied, (21) The ratio of the thickness of the shell to the particle size of the composite material is 0.04 to 0.07; (22) The tap density of the composite material is 1.90 g / m ３ ~2.30g / m ３ and (23) The specific surface area of ​​the composite material is 0.04 m ２ / g~4m ２ / g, (24) D50 of the composite material １ is 40 μm to 150 μm, and the specific surface area of ​​the composite material is 0.04 m ２ / g~0.06m ２ / g 5. The composite material according to claim 4.

6. At least one element of the core material is the same as at least one element of the first metal salt.

3. The composite material according to claim 1 or 2.

7. The composite material satisfies one or more of the following conditions: (25) The core material is a semiconductor material, and the shell material is an insulating material; (26) The core material is silicon carbide, and the first metal salt is a metal silicate; (27) The core material is silicon carbide, and the silicon carbide is a primary particle. The composite material according to any one of claims 1 to 3.

8. The composite material satisfies one or more of the following conditions: (28) The core material has a Mohs hardness of 7 to 10; (29) The core material is silicon nitride, and the first metal salt is a metal silicate; (30) The core material is silicon nitride, the first metal salt is a metal silicate, and the metal silicate comprises at least one of magnesium silicate, aluminum silicate, zinc silicate, zirconium silicate, magnesium silicate zirconate, aluminum silicate zirconate, and zinc silicate; (31) The core material is aluminum nitride and the shell material comprises an aluminate; (32) The core material is aluminum nitride, and the shell material comprises an aluminate, the aluminate comprising at least one of magnesium aluminate, zinc aluminate, calcium aluminate, potassium aluminate, and aluminum silicate. The composite material according to any one of claims 1 to 3.

9. the core material is silicon carbide; the shell material further comprises a second metal salt comprising at least two metal elements and not comprising silicon; The mass ratio of the metal silicate in the shell material is 10% or more. The composite material according to any one of claims 1 to 3.

10. The composite material satisfies one or more of the following conditions: (33) The mass ratio of the metal silicate in the shell material is 20% to 90%; (34) The second metal salt is an aluminate or / and zirconate, (35) The second metal salt comprises at least one of zinc aluminate, magnesium aluminate, calcium aluminate, potassium aluminate, zinc zirconate, magnesium zirconate, calcium aluminate, and potassium aluminate.

10. The composite material of claim 9.

11. The mass ratio of the metal silicate in the shell material is 100%.

10. The composite material of claim 9.

12. The composite material satisfies one or more of the following conditions: (36) D50 of the composite material １ The composite material satisfies the following conditions: 4.8 parts by weight of vinyl silicone oil having a viscosity of 100 mPa.s, 20 parts by weight of the composite material, 21 parts by weight of spherical alumina NSM-1S, 30 parts by weight of spherical alumina BAK-10, and 25 parts by weight of spherical alumina BAK-120 are mixed, and the mixture is first treated at a rotation speed of 1100 r / min under a vacuum of 1000 Pa for 1 minute, and then at a rotation speed of 1500 r / min under a vacuum of 40 Pa for 1 minute. The mixture is then sintered at 25°C under conditions of 0.1 to 100 s-1 using an Anton Paar rheometer. -１ The viscosity was measured at 1 × 10 ６ mpa·s~1.6×10 ６ Obtain a viscosity of mPa·s, (37) The core material is silicon carbide, the shell material is metal silicate, and the composite material satisfies the following conditions: EDS measurement is performed on the composite material, and an EDS line scan is performed from the shell to the core. The obtained EDS curves of silicon, oxygen, and metal elements are all continuous lines, and the silicon content increases sharply in the middle of the curve, the oxygen content decreases sharply in the middle of the curve, and the metal element content decreases sharply in the middle of the curve; (38) The core material is silicon carbide, the shell material is magnesium silicate, and the composite material satisfies the following conditions: XPS measurement is performed on the composite material, and peak fitting is performed. The spectroscopic diagram based on Si2p contains Si-C bonds with bond energies of 100 eV to 101 eV and O-Si-O bonds with bond energies of 105 eV to 106 eV; and the spectroscopic diagram based on Mg1s contains Mg-O-Si bonds with bond energies of 1305 eV to 1307 eV; (39) The core material is silicon carbide, the shell material is zinc silicate, and the composite material satisfies the following conditions: XPS measurement is performed on the composite material, and peak fitting is performed. The spectroscopic diagram based on Si2p contains Si-C bonds with bond energies of 100 eV to 101 eV and O-Si-O bonds with bond energies of 105 eV to 106 eV, and the spectroscopic diagram based on Zn1s contains Zn-O-Si bonds with bond energies of 1022 eV to 1045 eV. The composite material according to any one of claims 1 to 3.

13. 1. A method for producing a composite material, comprising: the surface of the core is coated with the shell material to form a precursor; sintering the precursor to allow at least a portion of the shell material to mass transfer to the core surface and form a shell containing a first metal salt, thereby obtaining the composite material; The thermal conductivity of the core material is 20 W / m·k or more. A method for producing a composite material, comprising:

14. The manufacturing method satisfies one or more of the following conditions: (40) The tap density of the core is 1.90 g / m ３ That's all, (41) The thermal conductivity of the core material is 0 W / m·k to 500 W / m·k; (42) D50 of the shell raw material ２ is 0.05 μm to 10 μm, and the D50 of the core material is ３ is 0.5 μm to 1000 μm, and 0.00001≦D50 ２ / D50 ３ ≦0.1, (43) The mass ratio of the shell raw material in the precursor is 1% to 30%; (44) The core material is silicon nitride or silicon carbide, and the shell raw material includes at least one of magnesium, magnesium oxide, magnesium hydroxide, organic magnesium, aluminum, aluminum oxide, aluminum hydroxide, organic aluminum, zinc, zinc oxide, zinc hydroxide, organic zinc, zirconium, zirconium oxide, zirconium hydroxide, and organic zirconium, and during the sintering, at least a portion of the shell raw material reacts with the core and undergoes mass transfer to form a shell containing the first metal salt; (45) The core material is silicon carbide, and the silicon carbide is a primary particle; (46) The core material is aluminum nitride, and the shell raw material includes at least one of zinc oxide, magnesium oxide, calcium oxide, potassium oxide, and silicon oxide, and during the sintering, at least a portion of the shell raw material reacts with the core and undergoes mass transfer to form a shell containing the first metal salt; (47) The core material is silicon nitride or silicon carbide, the shell raw material contains a hydrous silicate, and during the sintering, at least a part of the hydrous silicate melts and mass transfers to the surface of the core to form a shell containing the silicate; (48) The method for forming the precursor includes mixing the core, the shell raw material, and a coating aid and then coating. The method of claim 13 .

15. The manufacturing method satisfies one or more of the following conditions: (49) The tap density of the core is 1.90 g / m ３ ~2.4g / m ３ and (50) The thermal conductivity of the core material is 50 W / m·k to 250 W / m·k; (51) D50 of the core material ３ is 0.5 μm to 140 μm, and 0.0003≦D50 ２ / D50 ３ ≦0.1, (52) The mass ratio of the shell raw material in the precursor is 5% to 20%; (53) The core material is silicon nitride or silicon carbide, and the shell raw material contains at least one of magnesium, magnesium oxide, magnesium hydroxide, aluminum, aluminum oxide, aluminum hydroxide, zinc, zinc oxide, zinc hydroxide, zirconium, zirconium oxide, and zirconium hydroxide, and during the sintering, at least a portion of the hydrous silicate melts and mass transfers to the surface of the core to form a shell containing silicate; (54) The core material is silicon nitride or silicon carbide, the shell material is at least one of magnesium oxide, aluminum oxide, zinc oxide, and zirconium oxide, and the sintering is carried out under a temperature condition of 1000°C to 1400°C for 3 to 8 hours; (55) The core material is aluminum nitride, the shell raw material includes at least one of zinc oxide, magnesium oxide, calcium oxide, potassium oxide, and silicon oxide, and the sintering is performed under a condition of a temperature of 1400°C to 1800°C for 3 hours to 8 hours; (56) The core material is silicon nitride or silicon carbide, and the shell raw material comprises a hydrous silicate, the hydrous silicate comprising one or more of hydrous magnesium silicate, hydrous sodium silicate, hydrous sodium aluminosilicate, and hydrous calcium aluminosilicate; (57) The core material is silicon nitride or silicon carbide, the shell raw material contains a hydrous silicate, and the sintering is carried out for 3 to 8 hours under a temperature condition higher than the melting point of at least a part of the hydrous silicate; (58) The core material is silicon nitride or silicon carbide, and the coating aid includes a coating aid containing silicon. The method of claim 14 .

16. The manufacturing method satisfies one or more of the following conditions: (59) The coating aid comprises tetraethyl orthosilicate; (60) The mass ratio of the coating aid in the precursor is 1% to 15%; (61) The coating is performed using a wet ball mill, the rotation speed of the wet ball mill is 200 r / min to 600 r / min, and the time of the wet ball mill is 1 hour or more. The method of claim 15.

17. The manufacturing method satisfies one or more of the following conditions: (62) The mass ratio of the coating aid in the precursor is 3% to 10%; (63) The rotation speed of the wet ball mill is 300 r / min to 500 r / min, and the wet ball milling time is 1 hour to 6 hours. The method of claim 16 .

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