Aluminum nitride ceramic material and preparation method thereof

Abstract

The invention discloses an aluminum nitride ceramic material and a preparation method thereof.The preparation method comprises the steps that S100, a first doped sintering aid and a second doped sintering aid are mixed according to a preset proportion, a first mixture is obtained through wet ball milling, the first doped sintering aid comprises a first component and a second component, the first component is beryllium oxide, and the second component is aluminum oxide; the second component is selected from one of magnesium oxide and yttrium oxide, the ball milling medium is an alcohol compound, and the second doped sintering aid is used for bonding the aluminum nitride powder and the first aid; s200, drying the first mixture and separating to obtain a second mixture of which the particle size is less than or equal to 100 microns; and S300, carrying out dry pressing molding on the second mixture, and sintering in a nitrogen atmosphere to obtain the aluminum nitride ceramic material. According to the invention, different components in the auxiliary agent generate action mechanisms with different affinity to oxygen impurities, so that the high-performance aluminum nitride ceramic is obtained.

Description

Technical Field

[0001] This application relates to the field of ceramic materials technology, and in particular to an aluminum nitride ceramic material and its preparation method. Background Technology

[0002] Currently, aluminum nitride ceramic materials possess excellent thermal, electrical, and mechanical properties, as well as a coefficient of thermal expansion that matches that of silicon, making them a novel and advanced ceramic material with good overall performance. They have become key substrate materials in fields such as high-power electronic devices, high-density integrated circuit packaging, and efficient heat dissipation modules. However, with the rapid development of electronic devices towards higher power, miniaturization, and higher integration, stringent requirements are being placed on the stability and performance of aluminum nitride ceramic materials under harsh operating conditions.

[0003] To achieve densification and a dense microstructure in aluminum nitride ceramic materials, sintering aids are typically added during the preparation process to fully leverage the high thermal conductivity and other advantages of aluminum nitride ceramics. Traditional sintering aid systems primarily utilize rare earth oxides. These sintering aids react with the natural oxide layer on the surface of aluminum nitride particles (Al₂O₃) at high temperatures, forming a low-melting-point liquid phase. This liquid-phase sintering mechanism promotes mass migration and grain growth, ultimately achieving material densification.

[0004] However, existing aluminum nitride ceramic materials sintered using traditional sintering aids exhibit unstable electrical properties at high temperatures, leading to a significant decrease in volume resistivity. Therefore, there is an urgent need to develop an aluminum nitride ceramic material and its preparation method to obtain aluminum nitride ceramic materials with good performance characteristics. Summary of the Invention

[0005] One objective of this application is to provide an aluminum nitride ceramic material and its preparation method, which is beneficial to enhance the volume resistivity of the aluminum nitride ceramic material over a wide temperature range, thereby improving the service life and stability of the aluminum nitride ceramic material at high temperatures.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: a method for preparing aluminum nitride ceramic material, comprising the following steps: S100, providing aluminum nitride powder, ball milling media, a first doping sintering aid and a second doping sintering aid in a predetermined proportion, mixing them in a predetermined proportion, and obtaining a first mixture by wet ball milling, wherein the first doping sintering aid includes a first component and a second component, the first component being beryllium oxide, the second component being selected from magnesium oxide and yttrium oxide, the ball milling media being an alcohol compound, and the second doping sintering aid being used to bind the aluminum nitride powder and the first aid; S200, drying the first mixture and separating it to obtain a second mixture with a particle size ≤100μm; S300, dry pressing the second mixture and then sintering it in a nitrogen atmosphere to obtain aluminum nitride ceramic material.

[0007] In some embodiments, the mass ratio of the aluminum nitride powder to the first doped sintering aid in step S100 is 100:(0.5~8).

[0008] In some embodiments, when the second component in step S100 is yttrium oxide, the mass ratio of the aluminum nitride powder, beryllium oxide and yttrium oxide is 100:(0.3~1):(3~6).

[0009] In some embodiments, when the second component in step S100 is magnesium oxide, the mass ratio of the aluminum nitride powder, beryllium oxide and magnesium oxide is 100:(0.3~1):(0.5~1.6).

[0010] In some embodiments, the second doped sintering aid is polyvinyl butyral, the sum of the mass of the aluminum nitride powder and the first doped sintering aid is w1, the mass of the second doped sintering aid is w2, and the ratio between w1 and w2 is 100:(2~8).

[0011] In some embodiments, the particle size of the second mixture is ≤75μm.

[0012] In some embodiments, the aluminum nitride powder has a particle size range of 0.5 μm to 5 μm, the beryllium oxide has a particle size of less than 2 μm, the magnesium oxide has a particle size of less than 1 μm, and the yttrium oxide has a particle size of less than 0.5 μm.

[0013] In some embodiments, the aluminum nitride powder has a particle size range of 0.8 μm to 2 μm, the beryllium oxide has a particle size range of 0.8 μm to 1.5 μm, the magnesium oxide has a particle size range of 0.5 μm to 0.8 μm, and the yttrium oxide has a particle size range of 0.1 μm to 0.5 μm.

[0014] In some embodiments, step S300 further includes: S310, dry pressing the second mixture at a pressure of 5 MPa to 15 MPa to obtain a third mixture; S320, sintering the third mixture in a nitrogen atmosphere at a sintering temperature of 500°C to 1200°C for 50 min to 180 min to obtain a first intermediate; S330, sintering the first intermediate in a nitrogen atmosphere at a sintering temperature of 1200°C to 2000°C for 1500 min to 1700 min to obtain a second intermediate; S340, sintering the second intermediate in a nitrogen atmosphere at a sintering temperature of less than 2000°C for up to 800 min to obtain an aluminum nitride ceramic material.

[0015] To achieve the above objectives, this application also provides aluminum nitride ceramic materials prepared by the aforementioned preparation method.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: (1) By using a first doped sintering aid comprising multiple metal oxides, this application facilitates the formation of a multi-component liquid phase during the sintering process of aluminum nitride powder. Since the multi-component liquid phase typically has more suitable viscosity and wettability, it can more effectively promote material transport through the liquid phase sintering mechanism to fill pores, thereby obtaining a sintered body with good density. On the other hand, since the different components in the first doped sintering aid have different affinity mechanisms for oxygen impurities, this synergistic effect can extract oxygen atoms from the aluminum nitride lattice, thereby guiding oxygen to form a well-crystallized and structurally stable grain boundary phase, further optimizing the sintering process and controlling the final microstructure to obtain high-performance aluminum nitride ceramic materials.

[0017] (2) This application uses beryllium oxide and magnesium oxide, or beryllium oxide and yttrium oxide, as sintering aids for aluminum nitride powder. Beryllium oxide can react with Al2O3 on the surface of aluminum nitride particles to generate beryllium aluminate (such as BeAl2O4), thereby removing point defect oxygen in the crystal lattice. The purified crystal lattice can improve the thermal conductivity of aluminum nitride ceramic materials, further improving the stability and service life of aluminum nitride ceramic materials at high temperatures. At this time, the combined use of magnesium oxide or yttrium oxide can not only guide oxygen to form a well-crystallized and structurally stable grain boundary phase, but also generate a multi-component liquid phase with beryllium oxide at a lower eutectic temperature, thereby achieving good liquid phase sintering at lower temperatures and over a wider temperature range, improving density, and inhibiting excessive grain growth, resulting in aluminum nitride ceramic materials with better service stability. Detailed Implementation

[0018] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0019] As used herein, the terms “prepared from” and “comprising” are synonymous. The terms “comprising,” “including,” “having,” “containing,” or any other variation thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements and may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0020] When a quantity, concentration, or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range is disclosed as “1 to 5”, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range includes its endpoints and all integers and fractions within that range.

[0021] Approximate terms used in the specification and claims to modify quantities indicate that the invention is not limited to that specific quantity, but also includes acceptable modifications close to that quantity that do not alter the relevant essential function. Correspondingly, the use of "about," "approximately," etc., to modify a numerical value means that the invention is not limited to that precise value. In some instances, approximate terms may correspond to the precision of the instrument used to measure the value. In this application's specification and claims, scope definitions can be combined and / or interchanged, unless otherwise stated, these scopes include all subscopes contained therein.

[0022] The technical solution adopted in this application is as follows: a method for preparing aluminum nitride ceramic material, comprising the following steps: S100, providing aluminum nitride powder, ball milling media, a first doping sintering aid and a second doping sintering aid in a predetermined proportion, mixing them in a predetermined proportion, and obtaining a first mixture by wet ball milling, wherein the first doping sintering aid includes a first component and a second component, the first component is beryllium oxide, the second component is selected from magnesium oxide and yttrium oxide, the ball milling media is an alcohol compound, and the second doping sintering aid is used to bind the aluminum nitride powder and the first aid; S200, drying the first mixture and separating it to obtain a second mixture with a particle size ≤100μm; S300, dry pressing the second mixture and then sintering it in a nitrogen atmosphere to obtain aluminum nitride ceramic material.

[0023] This application utilizes a first-doped sintering aid comprising multiple metal oxides, which facilitates the formation of a multi-component liquid phase during the sintering process of aluminum nitride powder. Since the multi-component liquid phase typically possesses more suitable viscosity and wettability, it more effectively promotes mass transport through the liquid-phase sintering mechanism to fill pores, thereby producing a sintered body with good density. Furthermore, due to the different components in the first-doped sintering aid exhibiting different affinities for oxygen impurities, this synergistic effect can extract oxygen atoms from the aluminum nitride lattice, guiding oxygen to form a well-crystallized and structurally stable grain boundary phase or solid solution. This further optimizes the sintering process and regulates the final microstructure to obtain high-performance aluminum nitride ceramic materials.

[0024] Furthermore, the first component of the first doped sintering aid is beryllium oxide, and the second component is magnesium oxide or yttrium oxide. That is, the composition of the first doped sintering aid can be beryllium oxide (BeO) and magnesium oxide (MgO), or beryllium oxide and yttrium oxide (BeO). It is understood that beryllium oxide can react with Al2O3 on the surface of aluminum nitride particles to form beryllium aluminate (such as BeAl2O4), thereby removing point defect oxygen within the crystal lattice. The purified lattice can improve the thermal conductivity of the aluminum nitride ceramic material, further enhancing its stability and service life at high temperatures. Simultaneously, the combined use of yttrium oxide and beryllium oxide can achieve a synergistic effect through these two highly efficient sintering aids, which is beneficial for improving the densification effect of the aluminum nitride ceramic material and the purification effect within the crystal lattice. Y₂O₃ and BeO can synergistically react with Al₂O₃ to form a Y-Be-Al-O multi-component liquid phase. This type of multi-component liquid phase system typically exhibits a lower eutectic temperature and more suitable viscosity and wettability, enabling rapid and effective densification in aluminum nitride ceramics at relatively lower sintering temperatures and over a wider temperature range. On one hand, both Y₂O₃ and BeO are effective oxygen scavengers. Y₂O₃ reacts with Al₂O₃ on the surface of aluminum nitride powder to form a stable yttrium aluminum garnet phase, thus fixing oxygen at the grain boundaries. On the other hand, BeO's high thermal conductivity allows it to act within the crystal lattice, thereby removing point defects such as dissolved oxygen atoms while simultaneously improving the thermal conductivity of the aluminum nitride ceramic. In other words, Y₂O₃ is beneficial for removing oxygen from macroscopic grain boundaries, while BeO is beneficial for removing oxygen from microscopic crystal lattices, thus maximizing the purification of the aluminum nitride lattice and further resulting in aluminum nitride ceramic materials with good stability and service life at high temperatures. On the other hand, the combined use of Y2O3 and BeO can form a Y-Al-Be-O composite grain boundary phase, which not only obtains grain boundaries that are more stable, have higher melting points and better crystallinity than single yttrium aluminum garnet phase or beryllium aluminate, but also allows beryllium oxygen ions to enter the aluminum nitride lattice during sintering, improving the grain boundary bonding strength and reducing crack formation, which further helps to improve the stability of aluminum nitride ceramic materials at high temperatures.

[0025] It is worth mentioning that when magnesium oxide and beryllium oxide are used in combination, the Mg in magnesium oxide, which acts as a grain boundary pinning agent, is affected. 2+ Ions segregate at the grain boundaries of aluminum nitride, reducing grain boundary migration and thus inhibiting grain growth. Solid-state sintering also promotes the removal of pores, achieving a finer-grained structure. Simultaneously, beryllium oxide reacts with Al₂O₃ on the surface of the aluminum nitride powder to form a beryllium aluminate liquid phase, removing point defect oxygen from the crystal lattice. This purified lattice improves the thermal conductivity of the aluminum nitride ceramic material, further enhancing its stability and lifespan at high temperatures. Furthermore, when MgO and BeO are used in combination, MgO reacts with Al₂O₃ to form magnesium aluminum spinel or other eutectic compounds, further lowering the liquid phase formation temperature. This results in a low-melting-point, highly fluid multi-component liquid phase system, enabling rapid densification, saving energy, and inhibiting excessive grain growth in aluminum nitride, thus contributing to a longer lifespan for the aluminum nitride ceramic material. In other words, MgO can not only guide oxygen to form a crystallizable and structurally stable grain boundary phase, but also generate a multi-component liquid phase with BeO at a lower eutectic temperature. This allows for good liquid phase sintering at lower temperatures and over a wider temperature range, improving density and suppressing excessive grain growth, resulting in aluminum nitride ceramic materials with better stability.

[0026] In some embodiments, the mass ratio of aluminum nitride powder to the first doped sintering aid in step S100 is 100:(0.5~8). Specifically, the mass ratio of aluminum nitride powder to the first doped sintering aid is 100:0.5, 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, 100:5, 100:5.5, 100:6, 100:6.5, 100:7, 100:7.5, or 100:8. It is worth noting that selecting an appropriate proportion of the first doped sintering aid helps to form a suitable amount of liquid phase during sintering and finds the optimal balance between completely removing lattice oxygen and minimizing the negative impact of grain boundary phases. This promotes particle rearrangement, effectively fills the pores inside the ceramic material, reduces the number of residual pores in the sintered body, and further improves the density of the ceramic material.

[0027] In some embodiments, the second component in the first doped sintering aid in step S100 is yttrium oxide, wherein the mass ratio of aluminum nitride powder, beryllium oxide, and yttrium oxide is 100:(0.3~1):(3~6). Specifically, the mass ratio of aluminum nitride powder to beryllium oxide is 100:0.3, 100:0.4, 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, or 100:1; and the mass ratio of aluminum nitride powder to yttrium oxide is 100:3, 100:3.5, 100:4, 100:4.5, 100:5, 100:5.5, or 100:6. It is worth mentioning that by selecting an appropriate proportion of the second component in the first doping sintering aid, it is beneficial to form an appropriate amount of liquid phase during the sintering process, and to find the best balance between completely removing lattice oxygen and minimizing the negative impact of grain boundary phase, thereby promoting particle rearrangement, effectively filling the pores inside the ceramic material, reducing the number of residual pores in the sintered body, and further improving the density of the ceramic material.

[0028] In some embodiments, the second component in the first doped sintering aid in step S100 is magnesium oxide, wherein the mass ratio of aluminum nitride powder, beryllium oxide, and magnesium oxide is 100:(0.3~1):(0.5~1.6). Specifically, the mass ratio of aluminum nitride powder to beryllium oxide is 100:0.3, 100:0.4, 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, or 100:1; and the mass ratio of aluminum nitride powder to magnesium oxide is 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, 100:1.0, 100:1.2, 100:1.4, 100:1.5, or 100:1.6. It is worth mentioning that by selecting an appropriate proportion of the second component in the first doping sintering aid, it is beneficial to form an appropriate amount of liquid phase during the sintering process, and to find the best balance between completely removing lattice oxygen and minimizing the negative impact of grain boundary phase, thereby promoting particle rearrangement, effectively filling the pores inside the ceramic material, reducing the number of residual pores in the sintered body, and further improving the density of the ceramic material.

[0029] In some embodiments, the second doping sintering aid is polyvinyl butyral, the sum of the masses of aluminum nitride powder and the first doping sintering aid is w1, the mass of the second doping sintering aid is w2, and the ratio between w1 and w2 is 100:(2~8). Specifically, the ratio between w1 and w2 is 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, 100:5, 100:5.5, 100:6, 100:6.5, 100:7, 100:7.5, or 100:8. It is understood that since aluminum nitride powder itself is a loose and non-sticky substance, polyvinyl butyral (PVB) is needed as a binder to connect the powder. On the one hand, ball milling PVB together with the powder can ensure that PVB can be evenly coated on the surface of aluminum nitride and the first doped sintering aid particles through the strong mixing and shearing action of ball milling. This allows the dried and sieved aluminum nitride powder to better fill all corners of the mold under dry pressing, reducing the risk of density gradient caused by uneven powder filling, further reducing the internal stress of the green body, preventing delamination and cracking, and thus forming a green body with sufficient mechanical strength.

[0030] In some embodiments, the ball-to-material ratio in the ball milling process of step S100 is (0.8~3):1, preferably 1:1; the ball milling speed is 40Hz~60Hz, preferably 55Hz; the ball milling time is 12h~36h, preferably 24h; and the ball milling medium is ethanol. It should be understood that by selecting a suitable ball milling process, a uniformly distributed first mixture can be obtained.

[0031] In some embodiments, the particle size of the second mixture is ≤75μm. It is understood that the particle size of the second mixture can be 75μm, 70μm, 65μm, 60μm, 55μm, 50μm, 45μm, 40μm, 35μm, or 30μm. By selecting a second mixture of suitable size, it is beneficial to allow the dried and sieved aluminum nitride powder to better fill the corners of the mold under dry pressing, thereby further producing green bodies with regular shape and uniform density.

[0032] In some embodiments, step S200 further includes the step of drying the first mixture and sieving it through a 200-mesh sieve to obtain a second mixture with a particle size ≤100μm. By selecting a second mixture of suitable size, it is beneficial to make the dried and sieved aluminum nitride powder better fill the corners of the mold under dry pressing, thereby further producing a green body with a regular shape and uniform density.

[0033] In some embodiments, the particle size range of aluminum nitride powder is 0.5 μm to 5 μm, the particle size of beryllium oxide is less than 2 μm, the particle size of magnesium oxide is less than 1 μm, and the particle size of yttrium oxide is less than 0.5 μm. It can be understood that the particle size of aluminum nitride powder is 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, and 5.0 μm; the particle size of beryllium oxide is 0.5 μm, 1.0 μm, 1.5 μm, and 2.0 μm; and the particle size of yttrium oxide is 50 nm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, and 0.5 μm. Selecting powders of suitable sizes is beneficial for obtaining aluminum nitride ceramic materials with good stability and service life at high temperatures.

[0034] In some embodiments, the particle size range of aluminum nitride powder is 0.8 μm to 2 μm, the particle size range of beryllium oxide is 0.8 μm to 1.5 μm, the particle size range of magnesium oxide is 0.5 μm to 0.8 μm, and the particle size range of yttrium oxide is 0.1 μm to 0.5 μm. It should be understood that selecting powders of suitable sizes is beneficial for obtaining aluminum nitride ceramic materials with good stability and service life at high temperatures.

[0035] In some embodiments, step S300 further includes: S310, dry pressing the second mixture at a pressure of 5 MPa to 15 MPa to obtain a third mixture; S320, sintering the third mixture in a nitrogen atmosphere at a sintering temperature of 500°C to 1200°C for 50 min to 180 min to obtain a first intermediate; S330, sintering the first intermediate in a nitrogen atmosphere at a sintering temperature of 1200°C to 2000°C for 1500 min to 1700 min to obtain a second intermediate; S340, sintering the second intermediate in a nitrogen atmosphere at a sintering temperature below 2000°C for at most 800 min to obtain an aluminum nitride ceramic material. It is worth noting that selecting appropriate sintering conditions is beneficial for obtaining aluminum nitride ceramic materials with good stability and service life at high temperatures.

[0036] This application also provides aluminum nitride ceramic materials prepared by the aforementioned preparation method. By using a first doping sintering aid comprising various alkaline earth metal oxides, this application facilitates the formation of a multi-component liquid phase during the sintering process of aluminum nitride powder. Since the multi-component liquid phase typically possesses more suitable viscosity and wettability, it more effectively promotes mass transport through the liquid-phase sintering mechanism to fill pores, thereby obtaining a sintered body with good density. On the other hand, due to the combined action of the first and second components of the doping sintering aid, which exhibit different affinities for oxygen impurities, this synergistic effect can extract oxygen atoms from the aluminum nitride lattice, thereby guiding oxygen to form a well-crystallized and structurally stable grain boundary phase, further optimizing the sintering process and controlling the final microstructure to obtain high-performance aluminum nitride ceramic materials. It is worth mentioning that the aluminum nitride ceramic material prepared by the preparation method provided in this application exhibits a volume resistivity of not less than 1×10⁻⁶ at room temperature (25°C). 15 Ω·m, up to 1.0040×10 16 The volume resistivity is Ω·m, and the volume resistivity tested at 500℃ is not less than 9.5×10⁻⁶. 9 Ω·m, up to 1.1652×10 10 The value of Ω·m indicates that the prepared aluminum nitride ceramic material also exhibits high volume resistivity and good performance stability at high temperatures.

[0037] Example 1 A method for preparing aluminum nitride ceramic material, comprising the following steps: (1) Take 500g of aluminum nitride powder (particle size 1μm, purity 100%, grade E powder), 24.85g of yttrium oxide powder (particle size 300nm, purity 99.99%), 3.05g of beryllium oxide powder (particle size 1μm, purity 99.99%), and 30g of PVB (B60H). Use ethanol as the ball milling medium and perform wet ball milling for 24h. The ball milling speed is 55Hz and the ball-to-material ratio is 1:1 to obtain the first mixture.

[0038] (2) Dry the first mixture and sieve it through a 200-mesh sieve to obtain the second mixture.

[0039] (3) The second mixture is loaded into the mold and uniaxially dry-pressed under a pressure of 10 MPa, and then sintered in a pressureless sintering furnace. The sintering conditions are shown in Table 1.

[0040] Example 2 The difference between Example 2 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size of 1μm, purity of 100%, grade E powder), 4.92g of magnesium oxide powder (particle size of 600nm, purity of 99.99%), 3.05g of beryllium oxide powder (particle size of 1μm, purity of 99.99%), and 30g of PVB (B60H) were used.

[0041] Example 3 The difference between Example 3 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size of 1μm, purity of 100%, grade E powder), 24.85g of yttrium oxide powder (particle size of 300nm, purity of 99.99%), 4.8g of beryllium oxide powder (particle size of 1μm, purity of 99.99%), and 30g of PVB (B60H) were used.

[0042] Example 4 The difference between Example 4 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size 1μm, purity 100%, grade E powder), 24.85g of yttrium oxide powder (particle size 300nm, purity 99.99%), 1.8g of beryllium oxide powder (particle size 1μm, purity 99.99%), and 30g of PVB (B60H) were used.

[0043] Example 5 The difference between Example 5 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size of 1μm, purity of 100%, grade E powder), 28g of yttrium oxide powder (particle size of 600nm, purity of 99.99%), 3.05g of beryllium oxide powder (particle size of 1μm, purity of 99.99%), and 30g of PVB (B60H) were used.

[0044] Example 6 The difference between Example 6 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size of 1μm, purity of 100%, grade E powder), 20g of yttrium oxide powder (particle size of 600nm, purity of 99.99%), 3.05g of beryllium oxide powder (particle size of 1μm, purity of 99.99%), and 30g of PVB (B60H) were used.

[0045] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size of 1μm, purity of 100%, grade E powder), 4.92g of magnesium oxide powder (particle size of 600nm, purity of 99.99%), 24.85g of yttrium oxide powder (particle size of 300nm, purity of 99.99%), and 30g of PVB (B60H) were used.

[0046] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size of 1μm, purity of 100%, grade E powder), 4.92g of magnesium oxide powder (particle size of 600nm, purity of 99.99%), and 30g of PVB (B60H) were used.

[0047] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size of 1μm, purity of 100%, grade E powder), 24.85g of yttrium oxide powder (particle size of 300nm, purity of 99.99%) and 30g of PVB (B60H) were used.

[0048] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that in step (1), 500g of aluminum nitride powder (particle size of 1μm, purity of 100%, grade E powder), 3.05g of beryllium oxide powder (particle size of 1μm, purity of 99.99%), and 30g of PVB (B60H) were used.

[0049] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that only 500g of aluminum nitride powder was used in step (1).

[0050] Comparative Example 6 The difference between Comparative Example 6 and Comparative Example 5 is that both Comparative Example 5 and Comparative Example 6 were sintered in a nitrogen atmosphere, Comparative Example 5 was tested for volume resistivity in air, while Comparative Example 6 was tested for volume resistivity in nitrogen atmosphere.

[0051] Performance testing Examples 1 to 6, and Comparative Examples 1 to 6, obtained by sintering under the same sintering conditions in Table 1, were tested according to the test standard of GB / T 31838.2-2019 using the HTS1000HR high-temperature resistance testing system. The test sample size was 3 mm in diameter and 1 mm in thickness.

[0052] Table 1: Sintering Curves

[0053] Table 2: Volume resistivity performance test of aluminum nitride ceramic materials (unit: (Ω·m))

[0054] Through tests conducted under different conditions in Examples 1-6 and Comparative Examples 1-6, it was found that the aluminum nitride ceramic material provided in this application also exhibits good stability at high temperatures. Examples 1-6 show that when an excessive amount of yttrium oxide or magnesium oxide is used as the second component, an excessive amount of grain boundary second phase is easily formed, inhibiting grain growth. In other words, excessive yttrium aluminate phase is easily generated, or excessive magnesium oxide easily introduces new impurities that hinder heat transfer, resulting in a lower volume resistivity at high temperatures. When the second component uses a smaller amount of yttrium oxide or magnesium oxide, yttrium oxide is insufficient to react with the alumina on the surface of aluminum nitride powder, making it difficult to generate a yttrium aluminate liquid phase that can improve the densification of ceramic materials and reducing the removal of oxygen. Magnesium oxide, as a grain boundary pinning agent, can reduce grain boundary mobility, thereby inhibiting abnormal grain growth and promoting the formation of fine and uniform microstructures. However, when the amount added is too small, it cannot form an effective pinning effect at all grain boundaries, which is not conducive to removing point defect oxygen in the lattice and makes it difficult to obtain aluminum nitride ceramic materials with good service stability and service life at high temperatures.

[0055] As shown in Comparative Example 1, beryllium oxide can react with Al2O3 on the surface of aluminum nitride particles to form beryllium aluminate (such as BeAl2O4), thereby removing point defect oxygen in the crystal lattice. The purified crystal lattice can improve the thermal conductivity of aluminum nitride ceramic materials, further improving the stability and service life of aluminum nitride ceramic materials at high temperatures. Therefore, the aluminum nitride ceramic material in Comparative Example 1, which did not use beryllium oxide, has a lower volume resistivity at high temperatures. As shown in Comparative Examples 2 to 6, compared with ceramic materials prepared using only a single component, the ceramic materials prepared by setting an appropriate ratio of the first component (beryllium oxide) and the second component (magnesium oxide or yttrium oxide) in the first doping sintering aid not only have high volume resistivity at room temperature, but also maintain a stable high volume resistivity under test conditions of 500°C, enhancing the stability at high temperatures.

[0056] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A method of producing an aluminum nitride ceramic material, characterized by, The method comprises the steps of: S100, providing aluminum nitride powder, ball milling medium, first doped sintering aid and second doped sintering aid in a predetermined proportion, mixing them to obtain a first mixture by wet ball milling, wherein the first doped sintering aid comprises a first component and a second component, the first component is beryllium oxide, and the second component is selected from one of magnesium oxide and yttrium oxide, the ball milling medium is an alcohol compound, and the second doped sintering aid is used for bonding the aluminum nitride powder and the first aid; S200, drying the first mixture and separating to obtain a second mixture with a particle size of ≤100 μm; S300, performing dry pressing forming on the second mixture and then performing sintering treatment in a nitrogen atmosphere to obtain an aluminum nitride ceramic material.

2. The production method according to claim 1, characterized by, In the step S100, the mass ratio of the aluminum nitride powder to the first doped sintering aid is 100: (0.5-8).

3. The production method according to claim 2, characterized by, When the second component is yttrium oxide in the step S100, the mass ratio of the aluminum nitride powder, beryllium oxide and yttrium oxide is 100: (0.3-1): (3-6).

4. The production method according to claim 2, characterized by, When the second component is magnesium oxide in the step S100, the mass ratio of the aluminum nitride powder, beryllium oxide and magnesium oxide is 100: (0.3-1): (0.5-1.6).

5. The preparation method according to claim 1, characterized in that, The second doped sintering aid is polyvinyl butyral, the sum of the mass of the aluminum nitride powder and the first doped sintering aid is w1, the mass of the second doped sintering aid is w2, and the ratio between w1 and w2 is 100: (2-8).

6. The method of claim 1, wherein, The particle size of the second mixture is ≤75 μm.

7. The preparation method according to claim 1, characterized in that, The particle size of the aluminum nitride powder ranges from 0.5 μm to 5 μm, the particle size of beryllium oxide is less than 2 μm, the particle size of magnesium oxide is less than 1 μm, and the particle size of yttrium oxide is less than 0.5 μm.

8. The method of claim 7, wherein, The particle size of the aluminum nitride powder ranges from 0.8 μm to 2 μm, the particle size of beryllium oxide ranges from 0.8 μm to 1.5 μm, the particle size of magnesium oxide ranges from 0.5 μm to 0.8 μm, and the particle size of yttrium oxide ranges from 0.1 μm to 0.5 μm.

9. The method of any one of claims 1 to 8, wherein the method further comprises the step of: The step S300 further comprises: S310, performing dry pressing treatment on the second mixture, the pressure of the dry pressing treatment ranges from 5 MPa to 15 MPa to obtain a third mixture; S320, sintering the third mixture at a sintering temperature of 500-1200 °C in a nitrogen atmosphere for 50-180 min to obtain a first intermediate; S330, sintering the first intermediate at a sintering temperature of 1200-2000 °C in a nitrogen atmosphere for 1000-1700 min to obtain a second intermediate; S340, sintering the second intermediate at a sintering temperature of less than 2000 °C in a nitrogen atmosphere for at most 800 min to obtain an aluminum nitride ceramic material.

10. An aluminum nitride ceramic material, characterized by, Prepared by the preparation method in any one of claims 1-9.

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