High-thermal-conductivity high-mechanical-property multilayer composite structure ceramic and preparation method thereof

Abstract

A kind of high thermal conductivity high mechanical property multilayer composite structure ceramic and its preparation method, the composite structure ceramic is prepared by the composite structure of Al2O3 single layer ceramic blank and AlN single layer ceramic blank upper and lower in turn, and Y2O3 single layer ceramic blank is arranged between adjacent Al2O3 single layer ceramic blank and AlN single layer ceramic blank.The preparation method is:Al2O3, Y2O3 and AlN single layer ceramic blank are prepared by tape casting respectively;The three kinds of ceramic blanks are sequentially stacked according to the order of Al2O3 / Y2O3 / AlN / Y2O3 to form a composite structure casting sheet, and then isostatic pressing is carried out to obtain a composite structure ceramic blank;Finally, glue is removed, high temperature sintering and double side polishing are carried out in sequence to obtain a composite structure ceramic.The multilayer composite structure ceramic obtained by the method can reduce the generation of AlON, and has the characteristics of high thermal conductivity and high mechanical property.

Description

Technical Field

[0001] This invention relates to the field of advanced ceramic materials technology, specifically to a multilayer composite ceramic with high thermal conductivity and high mechanical properties and its preparation method. Background Technology

[0002] Alumina (Al₂O₃) ceramics are widely used as substrates and encapsulation materials for various applications due to their excellent electrical and mechanical properties and acceptable cost. However, their low thermal conductivity (less than 30 W / m²) makes them less suitable for use as substrates and encapsulation materials. -1 K -1 Due to its incompatibility with silicon's coefficient of thermal expansion, the widespread applicability of Al₂O₃ in advanced VLSI and high-power LEDs is greatly limited. Compared to Al₂O₃, aluminum nitride (AlN) not only has a higher thermal conductivity (intrinsic thermal conductivity ≈ 319 W / m²), but also... -1 K -1 Furthermore, AlN has a higher coefficient of thermal expansion than silicon. However, its low oxidation resistance, low mechanical strength, high sintering temperature, and high production cost limit its widespread application. Therefore, Al2O3 / AlN composite ceramics, as a novel system, offer Al2O3's high-temperature oxidation resistance and mechanical strength, while the addition of AlN helps improve the overall thermal conductivity and reduce the coefficient of thermal expansion. The combination of Al2O3 and AlN allows for the complementary advantages of both materials, expanding their application range.

[0003] Furthermore, studies have shown that AlN reacts with Al₂O₃ at high temperatures (>1500℃) to form aluminum oxynitride (AlON), leading to a deterioration in the thermal and mechanical properties of the composite ceramic. This is because AlON has a very low thermal conductivity (≈10 W / m²). -1 K -1 AlON formation can significantly reduce the thermal conductivity of sintered Al2O3 / AlN composite ceramics. Simultaneously, AlON has a larger specific volume than the initial Al2O3 / AlN mixture, causing the Al2O3 / AlN composite ceramic to expand and form large pores, thus leading to a decrease in its relative density and mechanical strength. These results indicate that minimizing AlON plays a crucial role in improving the fracture strength and thermal conductivity of Al2O3 / AlN composite ceramics.

[0004] CN112279628A discloses an alumina composite ceramic, its preparation method, and its application. The alumina composite ceramic is composed of composite microparticles and AlN microparticles. The first composite microparticle is obtained by spray granulation, and then mixed with AlN microparticles by dry ball milling to obtain the second composite microparticle. The process required to obtain the alumina composite ceramic in this scheme is very demanding, requires high precision, and is costly, making it unsuitable for large-scale production. The literature (Effect of AlN content on the properties and microstructure of pressureless-sintered Al2O3-AlN composites, J.Ceram.Process.Res.19(3)(2018)224-230) reports that the flexural strength of Al2O3 / AlN ceramics decreases sharply when the AlN content exceeds 15wt%, due to the formation of AlON in the composite system. Therefore, in order to improve the mechanical and thermal properties of Al2O3 / AlN composite ceramics, there is an urgent need for simple and low-cost techniques to reduce the formation of AlON. Summary of the Invention

[0005] The purpose of this invention is to provide a multilayer composite ceramic with high thermal conductivity and high mechanical properties and its preparation method. The method is simple, and the multilayer composite ceramic prepared can effectively reduce the generation of AlON, realize the complementary advantages of Al2O3 and AlN, and has the characteristics of high thermal conductivity and high mechanical properties.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a multilayer composite ceramic with high thermal conductivity and high mechanical properties. The multilayer composite ceramic is a composite structure prepared by sequentially stacking Al2O3 single-layer ceramic blanks and AlN single-layer ceramic blanks, and Y2O3 single-layer ceramic blanks are provided between adjacent Al2O3 single-layer ceramic blanks and AlN single-layer ceramic blanks.

[0007] This invention also provides a method for preparing the above-mentioned high thermal conductivity and high mechanical properties multilayer composite ceramic, the specific steps of which are as follows:

[0008] (1) Preparation of Al2O3 monolayer ceramic green body, Y2O3 monolayer ceramic green body and AlN monolayer ceramic green body:

[0009] (1-1) Weigh out raw material powders Al2O3 powder, Y2O3 powder and AlN powder respectively. Mix Al2O3 powder and Y2O3 powder with sintering aid A to obtain Al2O3 mixed powder and Y2O3 mixed powder respectively. Mix AlN powder with sintering aid B to obtain AlN mixed powder.

[0010] (1-2) Using anhydrous ethanol as the ball milling medium, the Al2O3 mixed powder, Y2O3 mixed powder and AlN mixed powder obtained in step (1-1) are ball-milled and mixed with dispersant, and then binder and plasticizer are added respectively, and ball milling is continued to obtain Al2O3 slurry, Y2O3 slurry and AlN slurry;

[0011] (1-3) Defoaming is performed on Al2O3 slurry, Y2O3 slurry and AlN slurry respectively. After defoaming, they are poured into the material tank of the casting machine for casting. After drying and molding, Al2O3 single-layer ceramic blank, Y2O3 single-layer ceramic blank and AlN single-layer ceramic blank are obtained.

[0012] (2) The Al2O3 monolayer ceramic blank, Y2O3 monolayer ceramic blank and AlN monolayer ceramic blank prepared in step (1) are stacked in sequence in the order of Al2O3 / Y2O3 / AlN / Y2O3 to form a composite structure tape. The composite structure tape is then formed by isostatic pressing to obtain a composite structure ceramic blank.

[0013] (3) The composite structure ceramic blank is placed in a muffle furnace for debinding treatment, and then the debinding treatment of the composite structure ceramic blank is sintered at high temperature. Finally, double-sided polishing is performed to obtain multi-layer composite structure ceramic.

[0014] Preferably, in step (1-1), the sintering aid A is MgO and TEOS, and the amount added is 0.2-0.7 wt.% and 0.4-0.6 wt.% of the raw material powder, respectively; the sintering aid B is any one or more of Y2O3, CaF2, Nb2O5, and ZrO2, and the amount of the sintering aid added is 3-8% of the raw material powder.

[0015] Preferably, in steps (1-2), the dispersant is any one or more of herring oil, oleic acid, sodium citrate, polyacrylic acid, and NP-10, and the amount of the dispersant added is 3 to 10% of the mass of the raw material powder.

[0016] Preferably, in steps (1-2), the binder is polyvinyl butyral, and the amount of binder added is 2-8% of the mass of the raw material powder.

[0017] Preferably, in (1-2), the plasticizer is any one or more of benzyl phthalate, polyvinyl alcohol, tert-butyl peroxypentanoate, and glycerin, and the amount of plasticizer added is 2-7% of the mass of the raw material powder.

[0018] Preferably, in steps (1-3), the thickness of the Al2O3 monolayer ceramic blank, the Y2O3 monolayer ceramic blank, and the AlN monolayer ceramic blank is 0.05-1 mm.

[0019] Preferably, in step (2), the total number of layers is 20 to 40, and the thickness of the composite structure casting sheet after stacking is 1 to 20 mm.

[0020] Preferably, in step (3), the adhesive removal process is as follows: in a flowing nitrogen atmosphere, the temperature is increased to 500°C at 0.2-5°C / min, then increased to 900°C at 5-10°C / min, and kept at 900°C for 5-8 hours.

[0021] Preferably, in step (3), the sintering temperature is 1700-1800℃, the sintering time is 5-12h, the sintering atmosphere is a mixture of hydrogen and nitrogen, and the volume ratio of hydrogen to nitrogen is 1:(1-2).

[0022] Compared with existing technical solutions, the present invention has the following advantages:

[0023] (1) This invention introduces a Y2O3 ceramic discontinuity between Al2O3 ceramic and AlN ceramic, which can effectively reduce the formation of AlON, achieve the complementary advantages of Al2O3 and AlN materials, and expand their application range. The resulting multilayer composite ceramic has a thermal conductivity, flexural strength and fracture resistance of 40 W / m. -1 K -1 700MPa and 15MPa·m -0.5 ;

[0024] (2) The present invention uses a powder forming process that combines tape casting and isostatic pressing to increase the density of the tape casting green body of composite structure ceramics, thereby further reducing the shrinkage of the green body during sintering, which helps to obtain multilayer composite structure ceramics with high thermal conductivity and high mechanical properties. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the multilayer composite ceramic sample prepared according to an embodiment of the present invention;

[0026] In the attached diagram: 1. Al2O3 ceramic layer, 2. Y2O3 ceramic layer, 3. AlN ceramic layer. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] A multilayer composite ceramic with high thermal conductivity and high mechanical properties, the structure of which is as follows: Figure 1As shown, the multilayer composite ceramic structure is a composite structure prepared by stacking Al2O3 single-layer ceramic blanks and AlN single-layer ceramic blanks one on top of the other, and Y2O3 single-layer ceramic blanks are provided between adjacent Al2O3 single-layer ceramic blanks and AlN single-layer ceramic blanks.

[0030] A method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties, the specific steps of which are as follows:

[0031] (1) Preparation of Al2O3 monolayer ceramic green body, Y2O3 monolayer ceramic green body and AlN monolayer ceramic green body:

[0032] (1-1) Weigh out 60g of raw material powders Al2O3, Y2O3 and AlN respectively. Mix Al2O3 powder and Y2O3 powder with sintering aid A (0.125g MgO and 0.25g TEOS) to obtain Al2O3 mixed powder and Y2O3 mixed powder respectively. Mix AlN powder with sintering aid B (1.8g Y2O3) to obtain AlN mixed powder.

[0033] (1-2) Using anhydrous ethanol as the ball milling medium, the Al2O3 mixed powder, Y2O3 mixed powder, and AlN mixed powder obtained in step (1-1) were ball-milled with dispersant (0.6g herring oil and 1.4g NP-10) for 6h. Then, binder (1.8g polyvinyl butyral) and plasticizer (1.2g benzyl butyl phthalate) were added respectively, and ball milling was continued at 180r / min for 6h to obtain Al2O3 slurry, Y2O3 slurry, and AlN slurry.

[0034] (1-3) Place Al2O3 slurry, Y2O3 slurry and AlN slurry in a vacuum degassing machine with a vacuum pressure of 1 Torr for 10 min to degas them. After degassing, pour them into the material tank of the casting machine for casting. After drying and forming, Al2O3 single-layer ceramic blank, Y2O3 single-layer ceramic blank and AlN single-layer ceramic blank with a thickness of 0.05 mm are obtained.

[0035] (2) The Al2O3 single-layer ceramic blank, Y2O3 single-layer ceramic blank and AlN single-layer ceramic blank prepared in step (1) are stacked in sequence in the order of Al2O3 / Y2O3 / AlN / Y2O3 for 20 layers to form a composite structure casting sheet. The composite structure casting sheet is then formed by isostatic pressing to obtain a composite structure ceramic blank with a thickness of 1 mm.

[0036] (3) The composite structure ceramic blank is placed in a muffle furnace for debinding treatment, and then the debinding composite structure ceramic blank is sintered at high temperature. Finally, double-sided polishing is performed to obtain multi-layer composite structure ceramic. The debinding mechanism is as follows: in a flowing nitrogen atmosphere, the temperature is increased to 500℃ at room temperature at 0.2℃ / min, and then increased to 900℃ at 5℃ / min, and held at 900℃ for 5h. The sintering mechanism is as follows: the sintering temperature is 1700℃, the sintering time is 5h, and the sintering atmosphere is a mixed atmosphere of hydrogen and nitrogen, wherein the volume ratio between hydrogen and nitrogen is 1:2.

[0037] The multilayer composite ceramic prepared in this embodiment has a thermal conductivity, flexural strength, and fracture toughness of 35.3 W / m. -1 K -1 653.5 MPa and 14.6 MPa·m -0.5 .

[0038] Example 2

[0039] A multilayer composite ceramic with high thermal conductivity and high mechanical properties, the structure of which is as follows: Figure 1 As shown, the multilayer composite ceramic structure is a composite structure prepared by stacking Al2O3 single-layer ceramic blanks and AlN single-layer ceramic blanks one on top of the other, and Y2O3 single-layer ceramic blanks are provided between adjacent Al2O3 single-layer ceramic blanks and AlN single-layer ceramic blanks.

[0040] A method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties, the specific steps of which are as follows:

[0041] (1) Preparation of Al2O3 monolayer ceramic green body, Y2O3 monolayer ceramic green body and AlN monolayer ceramic green body:

[0042] (1-1) Weigh out 60g of raw material powders Al2O3, Y2O3 and AlN respectively. Mix Al2O3 powder and Y2O3 powder with sintering aid A (0.325g MgO and 0.325g TEOS) to obtain Al2O3 mixed powder and Y2O3 mixed powder respectively. Mix AlN powder with sintering aid B (1.4g CaF2 and 1.6g Nb2O5) to obtain AlN mixed powder.

[0043] (1-2) Using anhydrous ethanol as the ball milling medium, the Al2O3 mixed powder, Y2O3 mixed powder, and AlN mixed powder obtained in step (1-1) were ball-milled with dispersant (2g sodium citrate and 1.5g NP-10) for 6h. Then, binder (3g polyvinyl butyral) and plasticizer (1.4g polyvinyl alcohol and 1.6g glycerol) were added respectively, and the mixture was ball-milled at 180r / min for 6h to obtain Al2O3 slurry, Y2O3 slurry, and AlN slurry.

[0044] (1-3) Place Al2O3 slurry, Y2O3 slurry and AlN slurry in a vacuum degassing machine with a vacuum pressure of 1 Torr for 10 min to degas them. After degassing, pour them into the material tank of the casting machine for casting. After drying and forming, Al2O3 single-layer ceramic blank, Y2O3 single-layer ceramic blank and AlN single-layer ceramic blank with a thickness of 0.4 mm are obtained.

[0045] (2) The Al2O3 single-layer ceramic blank, Y2O3 single-layer ceramic blank and AlN single-layer ceramic blank prepared in step (1) are stacked in sequence in the order of Al2O3 / Y2O3 / AlN / Y2O3 to form a composite structure casting sheet. The composite structure casting sheet is then formed by isostatic pressing to obtain a composite structure ceramic blank with a thickness of 10mm.

[0046] (3) The composite structure ceramic blank is placed in a muffle furnace for debinding treatment, and then the debinded composite structure ceramic blank is sintered at high temperature. Finally, double-sided polishing is performed to obtain multi-layer composite structure ceramic. The debinding mechanism is as follows: in a flowing nitrogen atmosphere, the temperature is raised to 500℃ at room temperature at 2℃ / min, and then raised to 900℃ at 8℃ / min, and held at 900℃ for 6h. The sintering mechanism is as follows: the sintering temperature is 1760℃, the sintering time is 8h, and the sintering atmosphere is a mixed atmosphere of hydrogen and nitrogen, wherein the volume ratio between hydrogen and nitrogen is 1:1.5.

[0047] The multilayer composite ceramic prepared in this embodiment has a thermal conductivity, flexural strength, and fracture toughness of 38.1 W / m². -1 K -1 687.6 MPa and 14.8 MPa·m -0.5 .

[0048] Example 3

[0049] A multilayer composite ceramic with high thermal conductivity and high mechanical properties, the structure of which is as follows: Figure 1 As shown, the multilayer composite ceramic structure is a composite structure prepared by stacking Al2O3 single-layer ceramic blanks and AlN single-layer ceramic blanks one on top of the other, and Y2O3 single-layer ceramic blanks are provided between adjacent Al2O3 single-layer ceramic blanks and AlN single-layer ceramic blanks.

[0050] A method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties, the specific steps of which are as follows:

[0051] (1) Preparation of Al2O3 monolayer ceramic green body, Y2O3 monolayer ceramic green body and AlN monolayer ceramic green body:

[0052] (1-1) Weigh out 60g of raw material powders Al2O3, Y2O3 and AlN respectively. Mix Al2O3 powder and Y2O3 powder with sintering aid A (0.4g MgO and 0.35g TEOS) to obtain Al2O3 mixed powder and Y2O3 mixed powder respectively. Mix AlN powder with sintering aid B (4.8g ZrO2) to obtain AlN mixed powder.

[0053] (1-2) Using anhydrous ethanol as the ball milling medium, the Al2O3 mixed powder, Y2O3 mixed powder, and AlN mixed powder obtained in step (1-1) were ball milled with dispersant (4g polyacrylic acid and 2g oleic acid) for 6h. Then, binder (4.8g polyvinyl butyral) and plasticizer (2.4g tert-butyl peroxyvalerate) were added respectively, and ball milling was continued at 180r / min for 6h to obtain Al2O3 slurry, Y2O3 slurry, and AlN slurry.

[0054] (1-3) Place Al2O3 slurry, Y2O3 slurry and AlN slurry in a vacuum degassing machine with a vacuum pressure of 1 Torr for 10 min to degas them. After degassing, pour them into the material tank of the casting machine for casting. After drying and forming, Al2O3 single-layer ceramic blank, Y2O3 single-layer ceramic blank and AlN single-layer ceramic blank with a thickness of 0.6 mm are obtained.

[0055] (2) The Al2O3 single-layer ceramic blank, Y2O3 single-layer ceramic blank and AlN single-layer ceramic blank prepared in step (1) are stacked in sequence in the order of Al2O3 / Y2O3 / AlN / Y2O3 to form a composite structure casting sheet. The composite structure casting sheet is then formed by isostatic pressing to obtain a composite structure ceramic blank with a thickness of 18mm.

[0056] (3) The composite structure ceramic blank is placed in a muffle furnace for debinding treatment, and then the debinding composite structure ceramic blank is sintered at high temperature. Finally, double-sided polishing is performed to obtain multi-layer composite structure ceramic. The debinding mechanism is as follows: in a flowing nitrogen atmosphere, the temperature is raised to 500℃ at room temperature at 5℃ / min, and then raised to 900℃ at 10℃ / min, and held at 900℃ for 8h. The sintering mechanism is as follows: the sintering temperature is 1800℃, the sintering time is 12h, and the sintering atmosphere is a mixed atmosphere of hydrogen and nitrogen, wherein the volume ratio between hydrogen and nitrogen is 1:1.

[0057] The multilayer composite ceramic prepared in this embodiment has a thermal conductivity, flexural strength, and fracture toughness of 40 W / m². -1 K -1 700MPa and 15MPa·m -0.5 .

Claims

1. A multilayer composite ceramic with high thermal conductivity and high mechanical properties, characterized in that, The multilayer composite ceramic structure is prepared by periodically stacking Al2O3 monolayer ceramic blanks and AlN monolayer ceramic blanks with Al2O3 / Y2O3 / AlN / Y2O3 as a basic unit, wherein the Y2O3 layer serves as an intermediate isolation layer.

2. A method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties as described in claim 1, characterized in that, The specific steps are as follows: (1) Preparation of Al2O3 monolayer ceramic green body, Y2O3 monolayer ceramic green body and AlN monolayer ceramic green body: (1-1) Weigh out raw material powders Al2O3 powder, Y2O3 powder and AlN powder respectively. Mix Al2O3 powder and Y2O3 powder with sintering aid A to obtain Al2O3 mixed powder and Y2O3 mixed powder respectively. Mix AlN powder with sintering aid B to obtain AlN mixed powder. (1-2) Using anhydrous ethanol as the ball milling medium, the Al2O3 mixed powder, Y2O3 mixed powder and AlN mixed powder obtained in step (1-1) are ball-milled and mixed with dispersant, respectively. Then, binder and plasticizer are added respectively, and ball milling is continued to obtain Al2O3 slurry, Y2O3 slurry and AlN slurry. (1-3) Defoaming is performed on Al2O3 slurry, Y2O3 slurry and AlN slurry respectively. After defoaming, they are poured into the material tank of the casting machine for casting. After drying and forming, Al2O3 single-layer ceramic blank, Y2O3 single-layer ceramic blank and AlN single-layer ceramic blank are obtained. (2) The Al2O3 monolayer ceramic blank, Y2O3 monolayer ceramic blank and AlN monolayer ceramic blank prepared in step (1) are stacked in sequence in the order of Al2O3 / Y2O3 / AlN / Y2O3 to form a composite structure tape. The composite structure tape is then formed by isostatic pressing to obtain a composite structure ceramic blank. (3) The composite structure ceramic blank is placed in a muffle furnace for debinding treatment, and then the debinding treatment composite structure ceramic blank is sintered at high temperature. Finally, double-sided polishing is performed to obtain multi-layer composite structure ceramic. The sintering temperature is 1700~1800℃, the sintering time is 5~12h, and the sintering atmosphere is a mixed atmosphere of hydrogen and nitrogen. The volume ratio between hydrogen and nitrogen is 1:(1~2).

3. The method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties according to claim 2, characterized in that, In step (1-1), the sintering aid A is MgO and TEOS, and the amount added is 0.2~0.7wt.% and 0.4~0.6wt.% of the raw material powder, respectively; the sintering aid B is any one or more of Y2O3, CaF2, Nb2O5, and ZrO2, and the amount of the sintering aid added is 3~8% of the raw material powder.

4. The method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties according to claim 2 or 3, characterized in that, In steps (1-2), the dispersant is any one or more of herring oil, oleic acid, sodium citrate, polyacrylic acid, and NP-10, and the amount of dispersant added is 3 to 10% of the mass of the raw material powder.

5. The method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties according to claim 2 or 3, characterized in that, In steps (1-2), the binder is polyvinyl butyral, and the amount of binder added is 2-8% of the mass of the raw material powder.

6. The method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties according to claim 2 or 3, characterized in that, In steps (1-2), the plasticizer is any one or more of benzyl butyl phthalate, polyvinyl alcohol, tert-butyl peroxypentanoate, and glycerin, and the amount of plasticizer added is 2-7% of the mass of the raw material powder.

7. The method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties according to claim 2 or 3, characterized in that, In steps (1-3), the thickness of Al2O3 monolayer ceramic green body, Y2O3 monolayer ceramic green body and AlN monolayer ceramic green body are all 0.05~1mm.

8. A method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties according to claim 2 or 3, characterized in that, In step (2), the total number of layers is 20 to 40, and the thickness of the composite structure cast film after stacking is 1 to 20 mm.

9. A method for preparing a multilayer composite ceramic with high thermal conductivity and high mechanical properties according to claim 2 or 3, characterized in that, In step (3), the adhesive removal process is as follows: in a flowing nitrogen atmosphere, the temperature is increased to 500°C at 0.2-5°C / min, then increased to 900°C at 5-10°C / min, and kept at 900°C for 5-8 hours.

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