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

Abstract

The application discloses a high-toughness high-thermal-conductivity aluminum nitride ceramic and a production process, and relates to the related field of aluminum nitride ceramics.The application introduces hexagonal boron nitride and Ti3SiC2 composite particles coated with titanium nitride on the surface into the aluminum nitride ceramic, and is supplemented with cerium oxide sintering aids and a reasonable organic additive system, so that the thermal conductivity and toughness are simultaneously improved, the interface stability and oxidation resistance of Ti3SiC2 are enhanced after TiN nano-coating, the combination of Ti3SiC2 and the matrix is improved, and the fracture toughness and mechanical strength of the ceramic are significantly improved; meanwhile, the aluminum nitride and the hexagonal boron nitride construct an efficient thermal conduction network, so that the material maintains excellent thermal conduction performance, the overall scheme structure design is reasonable, component matching is scientific, and the obtained ceramic has the advantages of high compactness, high thermal conductivity, excellent mechanical properties and strong thermal shock resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aluminum nitride ceramics, and particularly relates to a high-toughness high-thermal-conductivity aluminum nitride ceramic and a production process. BACKGROUND

[0002] Aluminum nitride ceramic is a high-performance ceramic material prepared by high-temperature sintering with aluminum nitride (AlN) as the main crystal phase, which has the characteristics of high thermal conductivity, high electrical insulation, low dielectric constant and low thermal expansion coefficient, and its internal structure is a covalent bond hexagonal system, which can maintain chemical stability under high temperature conditions, and has good heat dissipation performance and similar thermal expansion matching with silicon chips, and is widely used in power electronic packaging substrates, heat sinks, microwave devices and high-reliability electronic structural parts and other fields.

[0003] A nickel-doped enhanced aluminum nitride ceramic and a preparation method thereof disclosed in Chinese Patent Publication No. CN116589293B relate to the field of ceramic additive manufacturing technology. The preparation method of the nickel-doped enhanced aluminum nitride ceramic provided by the present application first demagnetizes the nickel powder at high temperature before doping nickel, avoiding the influence of the ferromagnetic property of nickel metal on the performance of the ceramic substrate; further introducing an oxide type sintering aid can reduce the sintering temperature of the nickel-doped aluminum nitride, avoiding the high temperature required during sintering from causing certain hidden dangers to equipment and workers, and helping to prepare aluminum nitride ceramic with high density, fine grains and uniform microstructure. The bending strength of the aluminum nitride ceramic after sintering can be further improved through the post-processing of hot isostatic pressing, so as to obtain the nickel-doped enhanced aluminum nitride ceramic.

[0004] While obtaining high thermal conductivity, aluminum nitride ceramic often has the problems of high brittleness and low fracture toughness, and is prone to cracking under thermal shock or mechanical load, which is difficult to meet the requirements of high-reliability working environment. In order to improve the mechanical properties of aluminum nitride ceramic, the method of adding second-phase particles or fiber reinforcement is usually adopted, but the conventional oxide, carbide and other reinforcing phases are easy to react with the matrix during high-temperature sintering, resulting in poor interface bonding or blocked thermal conduction path, so it is difficult to balance high toughness and high thermal conductivity. SUMMARY

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

[0006] In order to achieve the above object, the present application adopts the following technical scheme: a high-toughness high-thermal-conductivity aluminum nitride ceramic comprises the following components in mass fraction: aluminum nitride powder: 80-95 parts, hexagonal boron nitride powder: 1-5 parts, Ti3SiC2 particles coated with a 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, polyvinyl alcohol as a binder: 0.1-2 parts, dispersant PEI: 0.1-1 part, and deionized water: 30-60 parts.

[0007] Preferably, the Ti3SiC2 particles coated with a titanium nitride coating are coated with tetrabutyl titanate as a precursor 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 600-2000.

[0009] Preferably, the high-toughness high-thermal-conductivity aluminum nitride ceramic comprises the following components in mass fraction: aluminum nitride powder: 88 parts, hexagonal boron nitride powder: 2 parts, Ti3SiC2 particles coated with a titanium nitride coating: 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 part, dispersant PEI: 0.3 part, and deionized water: 45 parts.

[0010] A production process of a high-toughness high-thermal-conductivity aluminum nitride ceramic comprises the following specific steps:

[0011] S1, Ti3SiC2 surface TiN coating modification: take Ti3SiC2 powder, add anhydrous ethanol for ultrasonic dispersion, add tetrabutyl titanate to react with ammonia water, control pH 8-10, form a TiO2 precursor coating layer, dry, and then heat-treat at 700-900°C for 2 hours in an ammonia gas atmosphere to generate a dense TiN coating layer, thereby obtaining Ti3SiC2 particles coated with a titanium nitride coating;

[0012] S2, main material and auxiliary component pretreatment: mix the raw materials according to the following mass fraction, including aluminum nitride powder: 80-95 parts, hexagonal boron nitride powder: 1-5 parts, Ti3SiC2 particles coated with a 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, add deionized water: 30-60 parts as a ball milling medium to the mixed powder, and add dispersant PEI: 0.1-1 part and polyvinyl alcohol as a binder: 0.1-2 parts;

[0013] S3, ball milling mixing and dry granulation: using zirconia balls as medium in a ball mill tank for 12-24 hours at a rotation speed of 200-300 rpm, and after ball milling, the slurry is treated by vacuum drying to obtain uniform premixed powder, which is then treated by an auxiliary pretreatment device and sieved for standby use;

[0014] S4, forming and pre-sintering treatment: the dried powder is cold-pressed to form a green body, which is optionally pre-burned at 800°C to remove organic matter and residual binder;

[0015] S5, sintering densification: the green body is placed in a graphite mold and heated to 1800-1900°C in a nitrogen atmosphere while applying a pressure of 30-50 MPa for 2 hours to complete sintering;

[0016] S6, post-treatment and performance test: after natural cooling, the sintered body is taken out, machined, and the sample is tested for thermal conductivity, fracture toughness, density, and microstructure.

[0017] Advantages of the present application:

[0018] The present application introduces hexagonal boron nitride and Ti3SiC2 composite particles coated with titanium nitride into aluminum nitride ceramics, and adds cerium oxide sintering aid and a reasonable organic additive system, which realizes the synergistic improvement of thermal conductivity and toughness, enhances the interface stability and oxidation resistance of Ti3SiC2 after TiN nano-coating, improves the combination 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 conduction network, so that the material maintains excellent thermal conductivity, the overall scheme structure design is reasonable, the component matching is scientific, and the obtained ceramic has high density, high thermal conductivity, excellent mechanical properties and strong thermal shock resistance. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structure schematic diagram of the auxiliary pretreatment device of the present application;

[0020] Figure 2 is a structure schematic diagram of the swing mechanism of the present application;

[0021] Figure 3 is a structure schematic diagram of the processing bin of the present application;

[0022] Figure 4 is a structure schematic diagram of the processing bin of the present application.

[0023] The swing mechanism-1, the processing bin-2, the fixed frame-3, the lower guide rail-4, the upper guide rail-5, the base-11, the driving motor-12, the support arm-13, the swing arm-14, the linkage block-15, the sliding piece-16, the moving piece-17, the swing block-18, the guide strip-19, the support-110, the guide piece-111, the sliding block-112, the upper supporting piece-21, the shielding cover-22, the fixed cover-23, the flexible sleeve-24, the lower supporting piece-25, the leading-out cylinder-26, the upper screen-27, and the lower screen-28. DETAILED DESCRIPTION

[0024] In order to further explain the technical scheme of the present application, the following specific embodiments are described in detail.

[0025] The present application provides a high-toughness 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: 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 part, deionized water: 30-60 parts, the Ti3SiC2 particles coated with a titanium nitride coating are coated with tetrabutyl titanate as a precursor by a sol-gel method, and then heat-treated at 700-900°C to form the titanium nitride coating, the dispersant is PEI, and the molecular weight is 600-2000.

[0026] A preparation method of high-toughness high-thermal-conductivity aluminum nitride ceramic, steps as follows: S1, Ti3SiC2 surface TiN coating modification: take Ti3SiC2 powder, add anhydrous ethanol for ultrasonic dispersion, add tetrabutyl titanate and ammonia water reaction, control pH 9, form TiO2 precursor coating layer, dry in ammonia atmosphere at 800 DEG C for 2 hours, generate dense TiN coating layer, get Ti3SiC2 particles coated with titanium nitride coating on the surface; S2, main material and auxiliary component pretreatment: take the raw material according to the following mass fraction, including aluminum nitride 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, add deionized water: 30-60 parts as ball milling medium to the mixed powder, add dispersant PEI: 0.1-1 part and polyvinyl alcohol as binder: 0.1-2 parts; S3, ball milling and drying granulation: using zirconia ball as medium in the ball milling tank for 18 hours, the speed is 250 rpm, after ball milling, the slurry is treated by vacuum drying, get uniform premixed powder, then pass through auxiliary pretreatment device for screening and standby; S4, forming and pre-sintering treatment: dry powder is cold pressed to form green body, which can be pre-burned at 800 DEG C to remove organic matter and residual binder; S5, sintering densification: the green body is put into graphite mold, heated to 1850 DEG C in nitrogen atmosphere, and pressure of 40 MPa is applied, and the sintering is completed after 2 hours of heat preservation; S6, post-treatment and performance test: the sintered body is taken out after natural cooling, and the thermal conductivity, fracture toughness, density and microstructure of the sample are tested and analyzed.

[0027] Please refer to Figure 1 The auxiliary pretreatment device comprises a swing mechanism 1 for swinging, the swing mechanism 1 is connected with a treatment bin 2 at the right side, a fixing frame 3 is arranged at the right side of the treatment bin 2, a lower guide rail 4 is welded at the lower end of the inner side of the fixing frame 3, and an upper guide rail 5 is welded at the upper end, the lower guide rail 4 and the upper guide rail 5 are movably embedded into a connecting block at the middle part, the connecting block is connected with the right side of the treatment bin 2 respectively, and the upper guide rail 5 is in arc shape.

[0028] Please refer to Figure 2, swing mechanism 1 includes a base 11 for supporting, the top left end of the base 11 is convex, the convex position top is equipped with a drive motor 12, the right side output shaft of the drive motor 12 penetrates through the fixed arm 13 on the top of the base 11, the right side output shaft of the drive motor 12 is connected with the swing arm 14, the upper end of the swing arm 14 is connected with the linkage block 15, the outer side of the linkage block 15 is movably embedded into the inside of the sliding piece 16, the outer side of the upper end of the sliding piece 16 is movably sleeved with the right side upper end of the moving piece 17 which is convex, the convex position is hinged with the swing block 18, the swing block 18 is penetrated by the arc-shaped guide strip 19, the front and rear ends of the guide strip 19 are connected with the bracket 110, the inner side of the lower end of the bracket 110 is welded with the guide piece 111, the middle part of the guide piece 111 is movably embedded with the sliding block 112, the left side of the sliding block 112 is fixed with the sliding piece 16, the right side of the sliding block 112 and the right side of the swing block 18 are connected with the processing bin 2, and the processing bin 2 swings with the two components.

[0029] Please refer to Figure 3 and Figure 4 , the processing bin 2 includes an arc-shaped upper supporting piece 21, the left side of the upper supporting piece 21 is connected with the swing block 18, the right side is connected with the connecting block in the upper guide rail 5, the top of the upper supporting piece 21 is embedded with a detachable shielding cover 22, the top end of the shielding cover 22 is provided with a movable opening fixed cover 23, the bottom of the upper supporting piece 21 is connected with the lower supporting piece 25 through the flexible sleeve 24, the flexible sleeve 24 has elasticity and the inner wall is smooth, the left side of the lower supporting piece 25 is connected with the sliding block 112, and the right side is connected with the connecting block in the lower guide rail 4, the bottom of the lower supporting piece 25 is communicated with the discharging cylinder 26, the middle parts of the upper supporting piece 21 and the lower supporting piece 25 are hollow, the inner middle part of the upper supporting piece 21 is fixed with the upper screen 27, the middle part of the lower supporting piece 25 is fixed with the lower screen 28, and the lower screen 28 is correspondingly below the discharging cylinder 26.

[0030] The specific implementation of the auxiliary pretreatment device is as follows:

[0031] When the uniform premixed powder needs to be sieved, first, the shielding cover 22 is opened, then the powder is poured onto the upper supporting piece 21, and then the shielding cover 22 is covered, and the collection device is used to collect below the discharging 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, and the swing block 18 can swing on the guide strip 19, and the lower sliding block 112 slides in the guide piece 111, so that the upper supporting piece 21 reciprocatingly swings, the lower supporting piece 25 reciprocatingly moves in the front and rear positions, and the screen in the supporting piece can quickly and efficiently sieve the powder in sections.

[0033] Example one

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

[0035] Example two

[0036] A high-toughness high-thermal-conductivity aluminum nitride ceramic includes the following components by mass fraction: 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, deionized water: 45 parts, the components are prepared with the preparation method of the above high-toughness high-thermal-conductivity aluminum nitride ceramic.

[0037] Example three

[0038] A high-toughness high-thermal-conductivity aluminum nitride ceramic includes the following components by mass fraction: 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, deionized water: 50 parts, the components are prepared with the preparation method of the above high-toughness high-thermal-conductivity aluminum nitride ceramic.

[0039] Comparison of key performance test data of three groups of sintered bodies, hot-pressed sintering, 1850°C, 30 MPa, 2 hours, as shown in the following table:

[0040] Performance index Example 1 Example 2 Example 3 Thermal conductivity (W / m-K) 176 168 158 FRACTURE TOUGHNESS (MPa-m 1 / 2 )]> 4.8 5.9 6.8 Bending strength (MPa) 350 380 370 Relative density (%) 97.2 98.4 97.8 Electrical insulation (Ω-cm) >10 14 ]] >10 14 ]] >10 14 ]]

[0041] Example one, the aluminum nitride content in the formula is the highest, the addition amount of Ti3SiC2 particles coated with a titanium nitride coating on the surface and hexagonal boron nitride powder is relatively low, which effectively maintains the integrity of the continuous thermal conduction path in the ceramic matrix, so that the thermal conductivity of the sintered body reaches 176 W / m·K, which is the highest among the three groups, although the fracture toughness and bending strength are slightly lower, respectively 4.8 MPa·m 1 / 2 and 350 MPa, but still meets the engineering application requirements, suitable for electronic packaging field with extremely high thermal conductivity requirements;

[0042] Example two, the formula is balanced among aluminum nitride powder, Ti3SiC2 particles coated with titanium nitride coating and hexagonal boron nitride powder, the content of Ti3SiC2 is moderate, combined with CeO2 sintering aid, high density (98.4%) and excellent comprehensive performance are realized, the thermal conductivity of the sintered body reaches 168 W / m·K, while the fracture toughness is as high as 5.9 MPa·m 1 / 2 , the bending strength is also 380 MPa, with strength, toughness and thermal conductivity, suitable for use as a high-load heat dissipation substrate or structural-functional ceramic piece;

[0043] Example three, the content of Ti3SiC2 particles coated with titanium nitride coating in the formula reaches 10 parts, and h-BN is also increased to 4 parts, significantly improving the fracture toughness of the material (6.8 MPa·m 1 / 2 ), which is the highest in the three groups, this enhancement effect mainly comes from the bridging crack and energy dissipation mechanism of Ti3SiC2 particles coated with titanium nitride coating, at the same time, the lamellar structure of hexagonal boron nitride powder plays a role in crack deflection and induced cracking, although the thermal conductivity decreases slightly to 158 W / m·K, but it has obvious advantages in ceramic structural parts that require thermal shock resistance and crack propagation resistance.

[0044] The above only describes the preferred examples of the present application and is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high-toughness, high-thermal-conductivity aluminum nitride ceramic, characterized by: The following components are included by mass parts: aluminum nitride powder 80-95 parts, hexagonal boron nitride powder 1-5 parts, Ti3SiC2 particles coated with a titanium nitride coating layer 3-15 parts, wherein the thickness of the titanium nitride coating layer 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 part, and deionized water 30-60 parts.

2. The high-toughness, high-thermal-conductivity aluminum nitride ceramic of claim 1, wherein: The Ti3SiC2 particles coated with a titanium nitride coating layer are coated with tetrabutyl titanate as a precursor by a sol-gel method, and then heat-treated at 700-900°C in an ammonia atmosphere to form a titanium nitride coating layer.

3. The high-toughness, high-thermal-conductivity aluminum nitride ceramic of claim 2, wherein: The dispersant is PEI with a molecular weight of 600-2000.

4. The high toughness, high thermal conductivity aluminum nitride ceramic of claim 2, wherein: The following components are included by mass parts: aluminum nitride powder 80-95 parts, hexagonal boron nitride powder 1-5 parts, Ti3SiC2 particles coated with a titanium nitride coating layer 3-15 parts, wherein the thickness of the titanium nitride coating layer 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 part, and deionized water 30-60 parts.

5. A production process of high-toughness high-thermal-conductivity aluminum nitride ceramics, characterized by: The specific steps are as follows: S1, Ti3SiC2 surface TiN coating modification: take Ti3SiC2 powder, add anhydrous ethanol and ultrasonic dispersion, add tetrabutyl titanate and react with ammonia water, control pH 8-10, form TiO2 precursor coating layer, dry and heat treat at 700-900°C in ammonia atmosphere for 2 hours to generate dense TiN coating layer, obtain Ti3SiC2 particles coated with a titanium nitride coating layer; S2, main material and auxiliary component pretreatment: mix the raw materials according to the following mass parts, including aluminum nitride powder 80-95 parts, hexagonal boron nitride powder 1-5 parts, Ti3SiC2 particles coated with a titanium nitride coating layer 3-15 parts, wherein the thickness of the titanium nitride coating layer is 5-20 nanometers, cerium oxide sintering aid 0.5-3 parts, add deionized water 30-60 parts as a ball milling medium to the mixed powder, add dispersant PEI 0.1-1 part and polyvinyl alcohol as a binder 0.1-2 parts; S3, ball milling mixing and drying granulation: use zirconia balls as a medium to wet ball mill in a ball mill jar for 12-24 hours at a speed of 200-300 rpm, the slurry is vacuum dried after ball milling to obtain uniform premixed powder, then the powder is treated by an auxiliary pretreatment device and sieved for standby use; S4, forming and pre-sintering treatment: the dried powder is cold pressed to form a green body, and pre-sintering treatment is performed at 800°C; S5, sintering densification: the green body is placed in a graphite mold, heated to 1800-1900°C in a nitrogen atmosphere, and a pressure of 30-50 MPa is applied, and the sintering is completed after 2 hours of holding; S6, post-treatment and performance testing: the sintered body is taken out after natural cooling, and mechanical processing is performed, and the sample is tested for thermal conductivity, fracture toughness, density, and microstructure.

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