High-toughness high-thermal-conductivity aluminum nitride ceramic and production process thereof

Abstract

The invention discloses high-toughness and high-thermal-conductivity aluminum nitride ceramic and a production process, and relates to the related field of aluminum nitride ceramic. Hexagonal boron nitride and Ti3SiC2 composite particles with the surfaces coated with titanium nitride are introduced into aluminum nitride ceramic, a cerium oxide sintering aid and a reasonable organic adding system are supplemented, synergistic improvement of thermal conductivity and toughness is achieved, Ti3SiC2 is subjected to TiN nanometer coating, interface stability and oxidation resistance are enhanced, combination of Ti3SiC2 and a matrix is improved, and the thermal conductivity and toughness of the aluminum nitride ceramic are improved. The fracture toughness and the mechanical strength of the ceramic are obviously improved; meanwhile, aluminum nitride and hexagonal boron nitride construct an efficient thermal conductivity network, so that the material keeps excellent thermal conductivity, the overall scheme is reasonable in structural design and scientific in component matching, and the obtained ceramic is high in density, high in thermal conductivity, excellent in mechanical property and high in thermal shock resistance.

Description

Technical Field

[0001] The present invention relates to the field related to aluminum nitride ceramics, and in particular to a high-toughness and high-thermal-conductivity aluminum nitride ceramic and a production process. Background Art

[0002] Aluminum nitride ceramics are a high-performance ceramic material made of aluminum nitride (AlN) as the main crystal phase and prepared by high-temperature sintering. They have the characteristics of high thermal conductivity, high electrical insulation, low dielectric constant and low thermal expansion coefficient. Its internal structure is a covalently bonded hexagonal crystal system, which can maintain chemical stability under high temperature conditions. At the same time, it has good heat dissipation performance and thermal expansion matching similar to that of silicon chips. Therefore, it is widely used in power electronic packaging substrates, heat sinks, microwave devices and high-reliability electronic structural parts.

[0003] Chinese Patent Publication No.: CN116589293B A nickel-doped enhanced aluminum nitride ceramic and its preparation method, relating to the field of ceramic additive manufacturing technology. The preparation method of the nickel-doped enhanced aluminum nitride ceramic provided by the present invention first demagnetizes the nickel powder at high temperature before nickel addition, thereby avoiding the influence of the ferromagnetism of nickel metal on the performance of the ceramic substrate; further introduction of an oxide-type sintering aid can reduce the sintering temperature of the nickel-doped aluminum nitride, thereby avoiding the high temperature required during sintering causing certain hidden dangers to equipment and workers, and helping to prepare aluminum nitride ceramics with high density, fine grains, and uniform microstructure. By post-processing the sintered aluminum nitride ceramics with hot isostatic pressing, its bending strength can be further improved, thereby producing nickel-doped enhanced aluminum nitride ceramics.

[0004] While aluminum nitride ceramics have high thermal conductivity, they often have problems such as high brittleness and low fracture toughness. They are prone to cracking when subjected to thermal shock or mechanical loads, making it difficult to meet the requirements of a high-reliability working environment. In order to improve the mechanical properties of aluminum nitride ceramics, the method of adding second-phase particles or fiber reinforcement is usually adopted. However, conventional reinforcing phases such as oxides and carbides easily react with the matrix during high-temperature sintering, resulting in poor interface bonding or blocked thermal conduction paths, making it difficult to achieve both high toughness and high thermal conductivity. Summary of the Invention

[0005] Therefore, in order to solve the above-mentioned deficiencies, the present invention provides a high-toughness and high-thermal-conductivity aluminum nitride ceramic and a production process.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a high-toughness and high-thermal conductivity aluminum nitride ceramic, comprising the following components, in parts by mass: aluminum nitride powder: 80-95 parts, hexagonal boron nitride powder: 1-5 parts, Ti3SiC2 particles coated with a titanium nitride coating on the surface: 3-15 parts, wherein the thickness of the titanium nitride coating is 5-20 nanometers, cerium oxide sintering aid: 0.5-3 parts, polyvinyl alcohol as a binder: 0.1-2 parts, dispersant PEI: 0.1-1 parts, and deionized water: 30-60 parts.

[0007] Preferably, the Ti3SiC2 particles with titanium nitride coating on the surface adopt tetrabutyl titanate as a precursor, are coated by a sol-gel method and then heat-treated at 700-900° C. to form the titanium nitride coating.

[0008] Preferably, the dispersant is PEI with a molecular weight of 600 to 2000.

[0009] Preferably, the composition includes the following components, in parts by mass: aluminum nitride powder: 88 parts, hexagonal boron nitride powder: 2 parts, Ti3SiC2 particles coated with a titanium nitride coating on the surface: 8 parts, wherein the thickness of the titanium nitride coating is 10-15 nanometers, cerium oxide sintering aid: 2 parts, polyvinyl alcohol as a binder: 0.5 parts, dispersant PEI: 0.3 parts, and deionized water: 45 parts.

[0010] A production process for high-toughness and high-thermal-conductivity aluminum nitride ceramics, the specific steps are as follows:

[0011] S1. TiN coating modification of Ti3SiC2 surface: Ti3SiC2 powder was taken and added to anhydrous ethanol for ultrasonic dispersion, and tetrabutyl titanate was added to react with ammonia water, and the pH was controlled at 8-10 to form a TiO2 precursor coating layer. After drying, the powder was heat-treated at 700-900°C in an ammonia atmosphere for 2 hours to form a dense TiN coating layer, thereby obtaining Ti3SiC2 particles coated with titanium nitride on the surface;

[0012] S2. Pretreatment of the main material and auxiliary components: weigh and mix the raw materials according to the following mass ratio, including 80-95 parts of aluminum nitride powder, 1-5 parts of hexagonal boron nitride powder, 3-15 parts of Ti3SiC2 particles coated with a titanium nitride coating, wherein the thickness of the titanium nitride coating is 5-20 nanometers, and 0.5-3 parts of cerium oxide sintering aid. Add 30-60 parts of deionized water as a ball milling medium to the mixed powder, add 0.1-1 parts of PEI as a dispersant, and 0.1-2 parts of polyvinyl alcohol as a binder;

[0013] S3, ball milling and drying granulation: Wet milling is performed in a ball mill using zirconium oxide balls for 12–24 hours at a speed of 200–300 rpm. The slurry is vacuum dried to obtain a uniform premixed powder, which is then processed through an auxiliary pretreatment device and sieved for later use.

[0014] S4, molding and pre-sintering: The dried powder is cold-pressed to form a green blank, which can be pre-sintered at 800°C to remove organic matter and residual binder;

[0015] S5. Sintering and densification: Place the green billet into a graphite mold, heat it to 1800-1900°C in a nitrogen atmosphere, apply a pressure of 30-50 MPa, and keep it at this temperature for 2 hours to complete the sintering.

[0016] S6. Post-processing and performance testing: The sintered body is taken out after natural cooling and mechanical processing is performed. The thermal conductivity, fracture toughness, density and microstructure of the sample are tested and analyzed.

[0017] Beneficial effects of the present invention:

[0018] The present invention achieves a synergistic improvement in thermal conductivity and toughness by introducing hexagonal boron nitride and Ti3SiC2 composite particles coated with titanium nitride on the surface into aluminum nitride ceramics, supplemented by cerium oxide sintering aid and a reasonable organic additive system. After TiN nano-coating, Ti3SiC2 enhances the interface stability and antioxidant ability, improves its bonding with the matrix, and significantly improves the fracture toughness and mechanical strength of the ceramic. At the same time, aluminum nitride and hexagonal boron nitride construct an efficient thermal conductivity network, so that the material maintains excellent thermal conductivity. The overall structural design of the scheme is reasonable, and the components are scientifically matched. The resulting ceramics have high density, high thermal conductivity, excellent mechanical properties, and strong thermal shock resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the auxiliary pretreatment device of the present invention;

[0020] Figure 2 It is a structural schematic diagram of the swing mechanism of the present invention;

[0021] Figure 3 This is a schematic diagram of the processing chamber structure of the present invention;

[0022] Figure 4 It is a schematic diagram of the internal structure of the processing chamber of the present invention.

[0023] Among them: swing mechanism-1, processing chamber-2, fixed frame-3, lower guide rail-4, upper guide rail-5, base-11, drive motor-12, support arm-13, swing arm-14, linkage block-15, sliding part-16, moving part-17, swing block-18, guide bar-19, bracket-110, guide part-111, slider-112, upper supporting part-21, shielding cover-22, fixed cover-23, flexible sleeve-24, lower supporting part-25, guide cylinder-26, upper screen-27, lower screen-28. DETAILED DESCRIPTION

[0024] In order to further explain the technical solution of the present invention, it is described in detail below through specific embodiments.

[0025] The present invention provides a high-toughness and high-thermal-conductivity aluminum nitride ceramic, comprising the following components, calculated in parts by mass: 80-95 parts of aluminum nitride powder, 1-5 parts of hexagonal boron nitride powder, 3-15 parts of Ti3SiC2 particles coated with a titanium nitride coating, wherein the thickness of the titanium nitride coating is 5-20 nanometers, 0.5-3 parts of a cerium oxide sintering aid, 0.1-2 parts of polyvinyl alcohol as a binder, 0.1-1 parts of a dispersant PEI, and 30-60 parts of deionized water. The Ti3SiC2 particles coated with the titanium nitride coating are prepared by using tetrabutyl titanate as a precursor, coating the Ti3SiC2 particles by a sol-gel method, and then heat-treating the Ti3SiC2 particles at 700-900°C to form the titanium nitride coating. The dispersant is PEI, and has a molecular weight of 600-2000.

[0026] A preparation method of high-toughness and high-thermal-conductivity aluminum nitride ceramics, comprising the following steps: S1, TiN coating modification of Ti3SiC2 surface: taking Ti3SiC2 powder, adding it into anhydrous ethanol for ultrasonic dispersion, adding tetrabutyl titanate and ammonia water to react, controlling the pH to 9, forming a TiO2 precursor coating layer, drying it, and heat treating it at 800°C in an ammonia atmosphere for 2 hours to form a dense TiN coating layer, thereby obtaining Ti3SiC2 particles coated with a titanium nitride coating on the surface; S2, pretreatment of main materials and auxiliary components: weighing raw materials according to the following mass ratios, including nitrogen Aluminum powder: 80-95 parts, hexagonal boron nitride powder: 1-5 parts, Ti3SiC2 particles coated with titanium nitride coating: 3-15 parts, wherein the thickness of the titanium nitride coating is 5-20 nanometers, cerium oxide sintering aid: 0.5-3 parts, deionized water: 30-60 parts are added to the mixed powder as a ball milling medium, dispersant PEI: 0.1-1 parts and polyvinyl alcohol as a binder: 0.1-2 parts; S3, ball milling mixing and dry granulation: use zirconium oxide balls as the medium in a ball mill for 18 hours, the rotation speed is 250 rpm, the slurry after ball milling is vacuum dried to obtain a uniform premixed powder, which is then processed and sieved through an auxiliary pretreatment device for use; S4, molding and pre-sintering: the dried powder is cold-pressed to form a green blank, which can be pre-sintered at 800°C to remove organic matter and residual binder; S5, sintering densification: the green blank is placed in a graphite mold, heated to 1850°C in a nitrogen atmosphere, and a pressure of 40MPa is applied at the same time, and the sintering is completed after keeping warm for 2 hours; S6, post-processing and performance testing: the sintered body is taken out after natural cooling and mechanically processed, and the thermal conductivity, fracture toughness, density and microstructure of the sample are tested and analyzed.

[0027] See also Figure 1 The auxiliary pretreatment device includes a swinging mechanism 1 for shaking. The right side of the swinging mechanism 1 is connected to the processing chamber 2. A fixing frame 3 is provided on the right side of the processing chamber 2. A lower guide rail 4 is welded to the lower end of the inner side of the fixing frame 3, and an upper guide rail 5 is welded to the upper end. The middle parts of the lower guide rail 4 and the upper guide rail 5 are movably embedded in the connecting block, which is respectively connected to the right side of the processing chamber 2, and the upper guide rail 5 is arc-shaped.

[0028] See also Figure 2The swing mechanism 1 includes a base 11 for support. The left end of the top of the base 11 is convex, and a driving motor 12 is installed on the top of the convex position. The right output shaft of the driving motor 12 passes through the support arm 13 fixed on the top of the base 11, and the right output shaft of the driving motor 12 is connected to the swing arm 14. The upper end of the swing arm 14 is connected to the linkage block 15. The outer side of the linkage block 15 is movably embedded in the interior of the sliding member 16. The upper end of the outer side of the sliding member 16 is movably sleeved with a moving member 17 on the right side, and the middle of the convex position is hinged to the swing block 18. The middle of the swing block 18 is penetrated by an arc-shaped guide bar 19. The front and rear ends of the guide bar 19 are connected to the bracket 110. A guide part 111 is welded on the lower inner end of the bracket 110, and a slider 112 is movably embedded in the middle of the guide part 111. The left side of the slider 112 is fixed to the slider 16, and the right side of the slider 112 and the right side of the swing block 18 are connected to the processing chamber 2, and the processing chamber 2 swings with the two components.

[0029] See also Figure 3 and Figure 4 The processing chamber 2 includes an arc-shaped upper support member 21, the left side of the upper support member 21 is connected to the pendulum block 18, and the right side is connected to the connecting block inside the upper guide rail 5. A detachable shielding cover 22 is embedded in the top of the upper support member 21, and a movable fixed cover 23 is provided in the middle of the top of the shielding cover 22. The bottom of the upper support member 21 is connected to the lower support member 25 through a flexible sleeve 24. The flexible sleeve 24 has elastic force and the inner wall is smooth. The left side of the lower support member 25 is connected to the slider 112, and the right side is connected to the connecting block inside the lower guide rail 4. The middle part of the bottom end of the lower support member 25 is connected to the lead-out tube 26. The middle parts of the upper support member 21 and the lower support member 25 are both hollow, and an upper screen 27 is fixed in the middle position of the upper support member 21, and a lower screen 28 is fixed in the middle of the lower support member 25. The lead-out tube 26 corresponds to the lower screen 28.

[0030] The specific implementation of the auxiliary pre-processing device is as follows:

[0031] When the uniform premixed powder needs to be sieved, the shielding cover 22 is first opened, and then the powder is poured onto the upper support 21, and then the shielding cover 22 is covered. The collecting device needs to be used to collect the powder under the outlet cylinder 26;

[0032] Then the drive motor 12 is started to work. The drive motor 12 drives the output shaft to make the swing arm 14 swing. During the swinging process, it can act on the linkage block 15, and the linkage block 15 can move the sliding member 16. The moving member 17 is subjected to force, and then the swing block 18 can swing on the guide bar 19, and the slider 112 below slides in the guide member 111, so that the upper support member 21 can swing back and forth, and the lower support member 25 can move back and forth in the front and back positions. The screen in the support member can quickly and efficiently screen the powder in sections.

[0033] Example 1

[0034] A high-toughness, high-thermal-conductivity aluminum nitride ceramic comprises the following components, measured in parts by mass: 92 parts of aluminum nitride powder, 2 parts of hexagonal boron nitride powder, 4 parts of Ti3SiC2 particles coated with a titanium nitride coating, wherein the thickness of the titanium nitride coating is 10 nanometers, 1 part of a cerium oxide sintering aid, 0.5 parts of polyvinyl alcohol as a binder, 0.3 parts of PEI dispersant, and 40 parts of deionized water. The components are prepared according to the above-mentioned preparation method of the high-toughness, high-thermal-conductivity aluminum nitride ceramic.

[0035] Example 2

[0036] A high-toughness, high-thermal-conductivity aluminum nitride ceramic includes the following components, calculated in parts by mass: aluminum nitride powder: 88 parts, hexagonal boron nitride powder: 2 parts, Ti3SiC2 particles coated with a titanium nitride coating on the surface: 8 parts, wherein the thickness of the titanium nitride coating is 10-15 nanometers, cerium oxide sintering aid: 2 parts, polyvinyl alcohol as a binder: 0.5 parts, dispersant PEI: 0.3 parts, and deionized water: 45 parts. The components are prepared according to the above-mentioned preparation method of the high-toughness, high-thermal-conductivity aluminum nitride ceramic.

[0037] Example 3

[0038] A high-toughness, high-thermal-conductivity aluminum nitride ceramic includes the following components, calculated by mass: aluminum nitride powder: 85 parts, hexagonal boron nitride powder: 4 parts, Ti3SiC2 particles coated with a titanium nitride coating on the surface: 10 parts, wherein the thickness of the titanium nitride coating is 15-20 nanometers, cerium oxide sintering aid: 2.5 parts, polyvinyl alcohol as a binder: 1 part, dispersant PEI: 0.5 parts, and deionized water: 50 parts. The components are prepared according to the above-mentioned preparation method of the high-toughness, high-thermal-conductivity aluminum nitride ceramic.

[0039] The key performance test data of the three groups of sintered bodies were compared after hot pressing at 1850°C, 30 MPa, and 2 hours, as shown in the following table:

[0040] Performance indicators Example 1 Example 2 Example 3 Thermal conductivity (W / m·K) 176 168 158 <![CDATA[Fracture toughness (MPa·m 1 / 2 ).]]> 4.8 5.9 6.8 Flexural strength (MPa) 350 380 370 Relative density (%) 97.2 98.4 97.8 Electrical insulation (Ω·cm) <![CDATA[>10 14 ]]> <![CDATA[>10 14 ]]> <![CDATA[>10 14 ]]>

[0041] In Example 1, the aluminum nitride content in this formula is the highest, and the addition amount of Ti3SiC2 particles coated with titanium nitride coating and hexagonal boron nitride powder is relatively low, which effectively maintains the integrity of the continuous thermal conductivity path in the ceramic matrix, making the thermal conductivity of the sintered body reach 176W / m·K, the highest among the three groups, although its fracture toughness and flexural strength are slightly lower, at 4.8MPa·m 1 / 2 and 350MPa, but still meet the requirements of engineering applications and are suitable for electronic packaging fields with extremely high thermal conductivity requirements;

[0042] Example 2: This formula strikes a balance between aluminum nitride powder, Ti3SiC2 particles coated with titanium nitride coating, and hexagonal boron nitride powder. The Ti3SiC2 content is moderate, and combined with CeO2 sintering aid, it achieves high density (98.4%) and excellent comprehensive performance. The thermal conductivity of the sintered body reaches 168W / m·K, while the fracture toughness is as high as 5.9MPa·m 1 / 2 , the flexural strength is also 380MPa, combining strength, toughness and thermal conductivity, making it suitable for use as a high-load heat dissipation substrate or structural-functional integrated ceramic component;

[0043] In Example 3, the content of Ti3SiC2 particles coated with titanium nitride coating in the formula reached 10 parts, and h-BN was also increased to 4 parts, which significantly improved the fracture toughness of the material (6.8MPa·m 1 / 2 ), the highest among the three groups. This enhancement effect is mainly due to the bridging crack and energy dissipation mechanism of Ti3SiC2 particles coated with titanium nitride on the surface. At the same time, the lamellar structure of hexagonal boron nitride powder plays a role in crack deflection and crack induction. Although the thermal conductivity drops slightly to 158W / m·K, it has obvious advantages in ceramic structural parts that require thermal shock resistance and crack propagation resistance.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A high-toughness, high-thermal-conductivity aluminum nitride ceramic, characterized by: The invention comprises the following components, in parts by mass: 80-95 parts of aluminum nitride powder, 1-5 parts of hexagonal boron nitride powder, 3-15 parts of Ti3SiC2 particles coated with a titanium nitride coating on the surface, wherein the thickness of the titanium nitride coating is 5-20 nanometers, 0.5-3 parts of cerium oxide sintering aid, 0.1-2 parts of polyvinyl alcohol as a binder, 0.1-1 parts of dispersant PEI, and 30-60 parts of deionized water.

2. The high-toughness, high-thermal-conductivity aluminum nitride ceramic according to claim 1, characterized in that: The Ti3SiC2 particles with titanium nitride coatings on their surfaces are prepared by using tetrabutyl titanate as a precursor, and are coated by a sol-gel method and then heat-treated at 700-900° C. to form the titanium nitride coatings.

3. The high-toughness, high-thermal-conductivity aluminum nitride ceramic according to claim 2, characterized in that: The dispersant is PEI, and the molecular weight is 600-2000.

4. The high-toughness and high-thermal-conductivity aluminum nitride ceramic according to claim 2, characterized in that: The method includes the following components, in parts by mass: 88 parts of aluminum nitride powder, 2 parts of hexagonal boron nitride powder, 8 parts of Ti3SiC2 particles coated with a titanium nitride coating, wherein the thickness of the titanium nitride coating is 10-15 nanometers, 2 parts of cerium oxide sintering aid, 0.5 parts of polyvinyl alcohol as a binder, 0.3 parts of dispersant PEI, and 45 parts of deionized water.

5. A production process for high-toughness and high-thermal-conductivity aluminum nitride ceramics, characterized by: The specific steps are as follows: S1. TiN coating modification of Ti3SiC2 surface: Ti3SiC2 powder was taken and added to anhydrous ethanol for ultrasonic dispersion, and tetrabutyl titanate was added to react with ammonia water, and the pH was controlled at 8-10 to form a TiO2 precursor coating layer. After drying, the powder was heat-treated at 700-900°C in an ammonia atmosphere for 2 hours to form a dense TiN coating layer, thereby obtaining Ti3SiC2 particles coated with titanium nitride on the surface; S2. Pretreatment of the main material and auxiliary components: weigh and mix the raw materials according to the following mass ratio, including 80-95 parts of aluminum nitride powder, 1-5 parts of hexagonal boron nitride powder, 3-15 parts of Ti3SiC2 particles coated with a titanium nitride coating, wherein the thickness of the titanium nitride coating is 5-20 nanometers, and 0.5-3 parts of cerium oxide sintering aid. Add 30-60 parts of deionized water as a ball milling medium to the mixed powder, add 0.1-1 parts of PEI as a dispersant, and 0.1-2 parts of polyvinyl alcohol as a binder; S3, ball milling and drying granulation: Wet milling is performed in a ball mill using zirconium oxide balls for 12–24 hours at a speed of 200–300 rpm. The slurry is vacuum dried to obtain a uniform premixed powder, which is then processed through an auxiliary pretreatment device and sieved for later use. S4, molding and pre-sintering: The dried powder is cold-pressed to form a green blank, which can be pre-sintered at 800°C to remove organic matter and residual binder; S5. Sintering and densification: Place the green billet into a graphite mold, heat it to 1800-1900°C in a nitrogen atmosphere, apply a pressure of 30-50 MPa, and keep it at this temperature for 2 hours to complete the sintering. S6. Post-processing and performance testing: The sintered body is taken out after natural cooling and mechanical processing is performed. The thermal conductivity, fracture toughness, density and microstructure of the sample are tested and analyzed.

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