AlON powder as well as preparation method and application thereof

Abstract

The invention provides AlON powder as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, carrying out first-stage wet ball-milling treatment on AlN powder to obtain first slurry; s2, Al2O3 powder, AlON seed crystals and the first slurry are mixed and then subjected to second-stage wet ball milling treatment, and second slurry is obtained; the D50 of the AlON seed crystal is 0.5 [mu] m-1 [mu] m; s3, carrying out drying treatment on the second slurry to obtain precursor powder; the precursor powder is subjected to calcination treatment and refining treatment in sequence, and AlON powder is obtained; based on the total weight of the AlN powder, the Al2O3 powder and the AlON seed crystal being 100%, the addition amount of the AlON seed crystal is 5%-20%. According to the method, the AlON seed crystal is introduced in the raw material mixing process, and high-energy ball milling is combined, so that the reaction temperature is finally reduced, the heat preservation time is shortened, and the single-phase AlON powder with good dispersity is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ceramics, in particular to an AlON powder, a preparation method and application thereof. BACKGROUND

[0002] AlON transparent ceramics exhibit excellent optical transmittance in the near-ultraviolet to visible and near-infrared wave bands, not only have mechanical properties comparable to sapphire, but also have isotropic structure, and have broad application prospects in the fields of transparent armor, infrared windows and missile fairing. AlON can be regarded as a solid solution of Al2O3 and AlN, and the preparation process is mainly divided into "one-step method" and "two-step method": the one-step method refers to directly sintering Al2O3 and AlN mixed powder to synthesize AlON ceramic in situ; the two-step method first synthesizes AlON powder, and then sintering densification to obtain ceramic. A large number of studies have shown that the density, light transmittance and mechanical properties of the ceramic obtained by the one-step method are significantly lower than those of the two-step method, so the two-step method is usually used to prepare AlON ceramic, and the synthesis of AlON powder is the key prerequisite for preparing high-performance AlON ceramic by the two-step method.

[0003] Currently, the mainstream preparation routes of AlON ceramic powder mainly include solid phase reaction method, carbothermal reduction nitridation method and direct nitridation method. The carbothermal reduction nitridation method refers to taking Al2O3 powder and carbon powder as raw materials, generating intermediate phase AlN by carbothermal reduction under nitrogen atmosphere, and then forming AlON powder by solid phase reaction of AlN and residual Al2O3. US patent US4481300A mixes Al2O3 powder and carbon powder by ball milling, first reacts at 1550°C for 1h to generate appropriate AlN, then increases the temperature to 1750°C or 2140°C for 40min, and the generated AlON powder is ball milled for 16h and dried, and then heated to 600°C in air or oxygen for 2h to remove contaminants. Chinese patent CN103242043B takes Al2O3 powder and carbon powder as raw materials, fills humidified nitrogen into a graphite atmosphere furnace, heats to 1700-1850°C for 2h or more, cools after cooling to obtain pure phase AlON powder. Chinese patent CN103553093B takes Al2O3 powder and carbon powder as raw materials, sprays and dries to obtain a mixture, loads it into a cylindrical container with a porous air distribution plate at the bottom of the high temperature furnace, so that the mixture is stirred and mixed by nitrogen, heats to 1700-1900°C, and reacts for 3-4h to synthesize AlON powder without carbon residue. The carbothermal reduction nitridation method needs to react with nitrogen gas to generate AlN first, and then react with the remaining Al2O3 to generate AlON, which requires high atmosphere, and there is usually carbon residue in the product, which needs to be further heated to remove carbon, the process flow is complex and the efficiency is low. The direct nitridation method refers to taking aluminum powder and Al2O3 powder as raw materials, generating AlN by reacting aluminum powder with nitrogen at high temperature, and then generating AlON powder by solid phase reaction of AlN and residual Al2O3. Chinese patent CN114455952A takes aluminum powder and Al2O3 powder as raw materials, calcines at 1-3MPa nitrogen pressure, 1700-1800°C for 1-3h, cools to 900-1100°C, and then unloads and cools to obtain AlON powder. This method also needs to react with gas to generate AlN first, and then further synthesize AlON, which requires high atmosphere, and there are often problems such as insufficient reaction product.

[0004] Both of the above methods need to react with the nitrogen atmosphere, involve gas-solid reaction, are harsh on the atmosphere, and are prone to incomplete reaction, impurity residue and other problems. In comparison, the solid phase reaction method uses AlN powder and Al2O3 powder as raw materials, generates AlON powder through solid solution reaction in one step, the whole process is solid-solid reaction, the reaction is complete, the raw materials are controllable, the product purity is high, there is no impurity pollution, the process is more simple, and high-purity AlON is more easily obtained, which is suitable for industrial production. According to the analysis of AlN-Al2O3 phase diagram by H.X. Willems et al. (H.X. Willems, et al., Thermodynamics of Alon II: Phase relations, J. Eur. Ceram. Soc., 10 (1992) 339-46.), it is believed that only when the temperature is higher than 1640℃, AlON phase can be generated. Therefore, the temperature for preparing AlON powder by solid phase reaction method is usually above 1640℃. Qijianqi et al. (Study on Preparation of Alon Ceramic Powder by Solid Phase Reaction Method[J]. Rare Metal Materials and Engineering, 2007(S1):88-91) mixed Al2O3 powder with micron-sized AlN powder and nano-sized AlN powder, respectively. The results showed that AlON powder was synthesized at 1650℃, and pure phase AlON powder was obtained by mixing nano-sized Al2O3 powder and AlN powder with a molar ratio of 3:2, and heat treating at 1800℃ for 2h in a nitrogen atmosphere. Hu Weirui et al. (Preparation of High Optical Quality Aluminum Oxynitride Transparent Ceramic by Solid Phase Reaction Method and Pressureless Sintering[J]. Materials Review, 2024, 38(S2):80-83.) mixed Al2O3 powder and AlN powder according to a certain proportion, and heat treated at 1680-1800℃ for 2h. It was found that the synthesis reaction did not completely proceed at a calcination temperature of 1680℃, and single-phase AlON powder was synthesized at 1720℃ for 2h under the appropriate mixing ratio of raw material powder. There is also prior art that mixes γ-Al2O3 and AlN powder and places it in a high-temperature atmosphere reaction furnace to heat to 1700-1750℃ and heat for 100-180min, only to obtain AlON powder mainly with AlON as the main phase, and not to synthesize single-phase AlON powder. Although this method is simple in preparation process and controllable in composition, it still needs to be carried out at a high temperature of 1700℃ or above, and the heat preservation time is relatively long, generally about 2h, and the production efficiency needs to be improved.

[0005] In summary, although the solid phase reaction method has the advantages of simple process and controllable composition in preparing single-phase AlON powder, the atomic diffusion barrier needs to be overcome in the solid solution reaction of AlN and Al2O3 to generate AlON, and full diffusion in the lattice is required. The sintering condition is usually above 1700℃ for more than 2h to make the reaction fully proceed, synthesize single-phase AlON powder, high energy consumption and low efficiency, and even partial sintering, which causes grain coarsening, specific surface area reduction, and increases the difficulty of subsequent ball milling treatment. Therefore, it is crucial to reduce the sintering temperature and holding time of the solid phase reaction method for preparing AlON powder.

[0006] Therefore, how to provide a preparation method of AlON powder to prepare single-phase AlON powder at a lower sintering temperature and a shorter sintering time is one of the important technical problems to be solved in the field. SUMMARY

[0007] The main purpose of the present application is to provide an AlON powder, a preparation method and application thereof, to solve the problem that single-phase AlON powder cannot be prepared at low temperature and short time in the prior art.

[0008] To achieve the above purpose, the first aspect of the present application provides a preparation method of AlON powder, comprising: step S1, first-stage wet ball milling treatment of AlN powder to obtain first slurry; step S2, second-stage wet ball milling treatment of Al2O3 powder, AlON seed and first slurry after mixing to obtain second slurry; the D50 of the AlON seed is 0.5-1μm; step S3, drying treatment of the second slurry to obtain precursor powder; the precursor powder is subjected to calcination treatment and refinement treatment in sequence to obtain AlON powder; the addition amount of the AlON seed is 5-20% based on the total weight of the AlN powder, Al2O3 powder and AlON seed being 100%.

[0009] Further, the molar ratio of the AlN powder to the Al2O3 powder is (20-27):(73-80); preferably, the addition amount of the AlON seed is 5-10% based on the total weight of the AlN powder, Al2O3 powder and AlON seed being 100%.

[0010] Further, the D50 of the AlN powder is 3-5μm; and / or, the D50 of the Al2O3 powder is 0.5-1μm; preferably, the purity of the AlN powder is ≥99.9wt.%; and / or, the purity of the Al2O3 powder is ≥99.9wt.%.

[0011] Further, the step S1 comprises: mixing the AlN powder with a dispersant, and then performing a first-stage wet ball milling treatment at a rotating speed of 200±50 rpm for 12±2 hours to obtain a first slurry; preferably, the dispersant is selected from one or more of ethanol, isopropanol and n-butanol.

[0012] Further, in the step S2, the rotating speed of the second-stage wet ball milling treatment is 500 rpm-800 rpm; and / or, the time of the second-stage wet ball milling treatment is 4 hours-6 hours.

[0013] Further, in the step S3, the calcination temperature of the calcination treatment is 1650℃-1700℃, and the holding time is 10 minutes-40 minutes; and / or, the calcination treatment is performed in nitrogen.

[0014] Further, in the step S3, the calcination treatment comprises a temperature rising process and a holding process, and the temperature rising process comprises a first temperature rising stage and a second temperature rising stage performed in sequence; the temperature rising rate of the first temperature rising stage is 20±2℃ / min, so that the temperature reaches 1200±50℃; the temperature rising rate of the second temperature rising stage is 10±1℃ / min, so that the temperature reaches the calcination temperature; then, the holding process is performed; preferably, before the calcination treatment, the step S3 further comprises: placing a crucible containing the precursor powder into a sintering furnace, and performing a vacuumizing treatment on the sintering furnace until the air pressure in the sintering furnace is 1±0.05 Pa; then, a protective gas is introduced into the sintering furnace, and the calcination treatment is performed at 10±0.5 kPa; more preferably, the crucible is selected from a graphite crucible, a boron nitride crucible or a graphite crucible with a boron nitride coating; further preferably, the flow rate of the introduced protective gas is 0.4 L / min-1 L / min.

[0015] Further, in the step S3, the refining treatment is realized by dry ball milling, and the rotating speed of the dry ball milling is 100±20 rpm, and the time is 5±0.5 min; preferably, the grinding jar used for the dry ball milling is selected from a corundum jar, a nylon jar or an agate jar; and the grinding ball used for the dry ball milling is selected from an alumina ball, a zirconia ball or an agate ball.

[0016] The second aspect of the present application provides an AlON powder, which is prepared by the above-mentioned method for preparing an AlON powder, and the phase composition of the AlON powder is a single γ-AlON phase.

[0017] The third aspect of the present application provides an application of the above-mentioned AlON powder as a powder material in the fields of national security, optical devices and electronic devices.

[0018] The technical scheme of the present application is used to add a small amount of AlON crystal seeds as a pre-solid solution in the initial mixing stage of the AlN powder and the Al2O3 powder, so as to reduce the lattice reconfiguration energy barrier, reduce the nucleation potential barrier, and promote the generation of the AlON; meanwhile, the high-energy ball milling of the mixed powder composed of the AlN powder, the Al2O3 powder and the AlON powder can promote the uniform mixing of the raw materials, refine the powder particles, increase the particle surface contact area, introduce a large number of lattice defects into the powder to provide a channel for atomic diffusion, store defect energy and surface energy, improve the powder energy and the reaction activity, and promote the atomic diffusion. The present application finally reduces the reaction temperature, shortens the holding time, and obtains the single-phase AlON powder with good dispersity by introducing the AlON crystal seeds in the raw material mixing process and combining the high-energy ball milling. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and serve as an aid in explaining the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0020] Figure 1 The XRD test pattern of the AlON powder obtained in Example 1 of the present application;

[0021] Figure 2 The XRD test pattern of the AlON powder obtained in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0022] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0023] As described in the background, there is a problem that the single-phase AlON powder cannot be prepared at low temperature and in a short time in the prior art. In order to solve the above technical problem, the first aspect of the present application provides a preparation method of an AlON powder, which comprises the following steps: S1, performing first-stage wet ball milling treatment on AlN powder to obtain first slurry; S2, mixing Al2O3 powder, AlON crystal seeds and the first slurry, and then performing second-stage wet ball milling treatment to obtain second slurry; the D50 of the AlON crystal seeds is 0.5 μm to 1 μm; S3, performing drying treatment on the second slurry to obtain precursor powder; the precursor powder is sequentially subjected to calcination treatment and refinement treatment to obtain AlON powder; the addition amount of the AlON crystal seeds is 5% to 20% based on the total weight of the AlN powder, the Al2O3 powder and the AlON crystal seeds being 100%.

[0024] The AlON crystal seeds are added as a pre-solid solution in the initial mixing stage of the AlN powder and the Al2O3 powder, so as to reduce the lattice reconfiguration energy barrier, reduce the nucleation barrier, and promote the generation of the AlON; meanwhile, the mixed powder composed of the AlN powder, the Al2O3 powder and the AlON powder is subjected to high-energy ball milling, so as to promote the uniform mixing of the raw materials, refine the powder particles, increase the particle surface contact area, introduce a large number of lattice defects into the powder to provide channels for atomic diffusion, store defect energy and surface energy, improve the powder energy and the reaction activity, and promote the interatomic diffusion.

[0025] Specifically, in the process of preparing the AlON powder by the solid-phase reaction method, the direct reaction of the AlN and the Al2O3 needs to overcome a huge diffusion barrier, which is mainly because the mechanism of the formation of the AlON involves the reconfiguration and diffusion of the Al, O and N atoms in the original lattice, and especially at the phase interface of the AlN and the Al2O3, enough energy is needed to promote the breaking and recombination of the chemical bonds between atoms to form a new AlON structure. The traditional solid-phase reaction method is to realize the high-temperature treatment for a long time, but this not only increases the energy consumption, but also affects the microstructure of the AlON powder due to the grain growth caused by the high temperature, and reduces the mechanical properties and optical quality of the subsequent ceramic. In view of this point, the AlON crystal seeds are creatively introduced as a pre-solid solution, the D50 particle size of which is controlled within a specific range, and the addition amount of the crystal seeds is specified to be between 5% and 20%, so as to effectively reduce the nucleation barrier required for the AlN and the Al2O3 to generate the AlON, and promote the rapid generation of the AlON phase. The particle size selection and the amount control of the AlON crystal seeds are the key. The smaller D50 particle size ensures the uniform mixing of the crystal seeds and the raw material powder, maximizes the surface energy of the AlON crystal seeds, provides a rich starting point for the atomic diffusion of the AlN and the Al2O3, and greatly accelerates the growth process of the AlON phase. The amount of the crystal seeds within the reasonable range (5% to 20%) can effectively promote the generation of the AlON phase, and avoid the excessive crystal seeds from interfering with the ideal reaction environment of the AlN and the Al2O3, so as to ensure the purity of the AlON phase.

[0026] In the above preparation process, the wet ball milling treatment of the first step is specifically for the AlN powder, which can more finely control the particle size and microstructure of the AlN powder, so that the particle size distribution of the AlN powder is more uniform and the particle size is finer. This not only increases the specific surface area of the powder, but also diffuses the surface atoms of the broken particles to provide more active points for the nucleation of AlON, thereby improving the purity and reactivity of the raw materials and laying a solid foundation for the efficient generation of the AlON phase in the subsequent process. Then, the Al2O3 powder and the AlON seed are mixed with the pretreated AlN slurry. This process can maintain the pretreatment effect of the AlN powder while ensuring the more uniform distribution of the Al2O3 powder and the AlON seed, thereby promoting the dispersion of the seed in the powder and reducing the agglomeration phenomenon. This facilitates the nucleation of the AlON seed in the reaction process and promotes the uniform generation of the AlON phase.

[0027] In summary, the present application introduces AlON seeds during the mixing of raw materials and combines high-energy ball milling, which ultimately reduces the reaction temperature, shortens the holding time, and obtains single-phase AlON powder with good dispersity.

[0028] Further, since the formation of AlON essentially depends on the solid-state diffusion of Al, O and N atoms in AlN and Al2O3, the molar ratio of AlN powder to Al2O3 powder is preferably (20-27):(73-80), which facilitates the more stable generation of the AlON phase and improves the efficiency of the reaction and the phase purity of the product. In several typical embodiments, the addition amount of AlON seeds is 5%-10% based on the total weight of AlN powder, Al2O3 powder and AlON seeds. The addition amount of AlON seeds in the above optimization range can more effectively utilize the nucleation effect of the seeds and reduce the energy demand during the generation of the AlON phase. In fact, the amount of seeds is not the more the better, and too many seeds can occupy too much space and hinder the effective contact between AlN and Al2O3, which is not conducive to the uniform growth of the AlON phase. On the other hand, too little seed can not fully play its role in accelerating nucleation and reducing energy demand. The inventors have optimized the addition amount of AlON seeds as above through a large number of experiments, which not only rapidly generates the AlON phase at a lower reaction temperature, but also more effectively inhibits the abnormal growth of the crystal grains and the agglomeration phenomenon, thereby obtaining single-phase AlON powder with higher purity and better dispersity.

[0029] Further, the D50 of the AlN powder is 3-5 μm; and / or, the D50 of the Al2O3 powder is 0.5-1 μm. Preferably, the particle sizes of the two raw powders are as above, the AlN powder has a larger particle size, is less likely to hydrolyze, the Al2O3 powder has a smaller particle size, a larger specific surface area, and provides more active sites, further accelerating the nucleation and growth of the AlON phase, thus helping to promote the formation of the AlON phase at a lower sintering temperature. In order to obtain an AlON powder with higher purity, further preferably, the purity of the AlN powder is ≥99.9 wt.%; and / or, the purity of the Al2O3 powder is ≥99.9 wt.%.

[0030] In several typical embodiments, in order to further increase the specific surface area of the AlN powder, provide more active sites, and ultimately accelerate the nucleation rate and phase purity of the AlON phase, preferably, step S1 comprises: mixing the AlN powder with a dispersant, and then performing a first-stage wet ball milling treatment at a rotation speed of 200±50 rpm for 12±2 h to obtain a first slurry, the refined AlN powder has a particle size D50 of 0.5-1 μm, which is consistent with the particle size of the Al2O3 powder and the introduced AlON seed, ensures uniform reaction interface and stable composition ratio, and helps to promote the formation of single-phase AlON. In actual applications, the dispersant can be selected from one or more of ethanol, isopropanol, and n-butanol. In step S2, preferably, the rotation speed of the second-stage wet ball milling treatment is 500-800 rpm, so as to more effectively and intensively cause the mixed powder particles to collide, extrude, and shear, further refine the powder, increase the contact area between the particles, provide more reaction interfaces and energy for the formation of the AlON phase, and ultimately improve the growth rate and phase purity thereof. In order to reduce the enrichment or depletion of the AlON seed in local areas, thus promoting the more uniform generation of the AlON phase in the entire reaction system, preferably, the time of the second-stage wet ball milling treatment is 4-6 h, more preferably 4-4.5 h.

[0031] After obtaining the precursor powder, AlON crystals are formed by calcination treatment. In step S3, the calcination temperature of the calcination treatment is further preferably 1650-1700 DEG C, and the holding time is 10-40 min. In the conventional method, due to the lack of an effective nucleation promoter, the formation of the AlON phase from AlN and Al2O3 often requires high temperature of 1700 DEG C or higher for 2 hours or longer, which not only consumes a large amount of energy, but also easily causes powder agglomeration and abnormal grain growth, affecting the purity and microstructure of the AlON phase. After the introduction of the AlON seed, the nucleation barrier of the AlON phase can be significantly reduced, and even at a lower temperature, the solid solution reaction between AlN and Al2O3 can quickly occur to generate the AlON phase. The temperature range of 1650-1700 DEG C obtained by the present application not only greatly saves energy consumption, but also effectively reduces the agglomeration and grain growth caused by high temperature sintering, making the formation of the AlON phase more controllable and the product more pure. In addition, the conventional solid phase reaction often requires a long holding time to ensure sufficient reaction, but long time high temperature treatment can make the agglomeration and abnormal grain growth of the raw material powder more serious, affecting the dispersibility and microstructure of the AlON powder, and thus affecting the optical properties and mechanical strength of the subsequent AlON ceramic. The introduction of the AlON seed and the combination of high-energy ball milling make the solid solution reaction of AlN and Al2O3 quickly complete in a short time (10-40 min), without the need for long time holding, and high-purity AlON powder can be obtained. At the same time, in order to further improve the phase purity, the calcination treatment is preferably carried out in nitrogen.

[0032] In several typical embodiments, the calcination treatment in step S3 includes a heating process and a holding process, and the heating process includes a first heating stage and a second heating stage performed in sequence; the first heating stage has a heating rate of 20±2 DEG C / min to make the temperature reach 1200±50 DEG C; the second heating stage has a heating rate of 10±1 DEG C / min to make the temperature reach the calcination temperature; and then the holding process is performed. In the above preferred scheme, the first heating stage is set to make the raw material powder gradually reach 1200±50 DEG C at a lower heating rate, thereby effectively reducing the thermal stress in the powder and the powder breakage caused by too fast heating, and further providing a better basis for the uniform generation of the AlON phase. The second heating stage further slows down the heating rate, so that the raw material powder can be more uniformly heated to the required temperature before entering the solid solution reaction temperature, thereby reducing the side reactions caused by local overheating, and finally more significantly improving the phase purity of the AlON powder.

[0033] Before the calcination treatment, preferably, the step S3 further comprises: placing the crucible containing the precursor powder into a sintering furnace, and performing vacuumizing treatment on the sintering furnace until the air pressure in the sintering furnace is 1±0.05 Pa; then introducing a protective gas into the sintering furnace, and performing the calcination treatment under 10±0.5 kPa. In this preferred scheme, a near-vacuum environment is first created, so as to more effectively reduce the interference of external impurities, and to provide more favorable conditions for the accelerated nucleation of the AlON seed and the pure generation of the AlON phase. Then nitrogen is introduced and the air pressure is maintained at 10±0.5 kPa, so as to more effectively promote the generation of the AlON phase while more effectively preventing the invasion of impurity gases such as oxygen.

[0034] In actual applications, the crucible is selected from a graphite crucible, a boron nitride crucible, or a graphite crucible with a boron nitride coating; and, in order to provide a more stable reaction system, preferably, the flow rate of the introduced protective gas is 0.4 L / min to 1 L / min.

[0035] Further, in the step S3, preferably, the refinement treatment is achieved by dry ball milling, and the dry ball milling is performed at a speed of 100±20 rpm for 5±0.5 min. In this preferred process, the AlON powder can undergo more suitable collision and shearing, so as to more effectively refine the particles, increase the specific surface area, reduce the crystal damage, and improve the dispersibility.

[0036] In addition, in the dry ball milling process of the step S3, preferably, the milling tank used is selected from a corundum tank, a nylon tank, or an agate tank; and the dry milling balls are selected from alumina balls, zirconia balls, or agate balls.

[0037] The second aspect of the present application provides an AlON powder prepared by the above-mentioned method for preparing an AlON powder, and the phase composition of the AlON powder is a single γ-AlON phase. The AlON powder obtained by the above-mentioned method for preparing an AlON powder is composed of a single γ-AlON phase, without any residual secondary phase.

[0038] It should be particularly pointed out that, due to the particularity of the material field and the limitation of existing testing and characterization means, it is difficult to comprehensively quantitatively characterize the arrangement mode of each atom in the above-mentioned AlON powder obtained by the present application. However, the performance test results have shown that the phase composition of the above-mentioned AlON powder obtained by the present application is a single γ-AlON phase, and thus has excellent physicochemical properties.

[0039] The third aspect of the present application provides an application of the above-mentioned AlON powder as a powder material in the field of national security, the field of optical devices, and the field of electronic devices. Based on the advantages of high purity, excellent microstructure integrity, and controllable particle size distribution exhibited by the above-mentioned AlON powder preparation method, the obtained AlON powder can exhibit good performance in multiple fields. In the field of national security, AlON transparent ceramics become the ideal material selection for transparent armor, missile fairing, and optoelectronic windows due to their high hardness, high damage threshold, and isotropic mechanical properties. The high-purity γ-AlON phase powder prepared by the present application can further form more dense and higher transparency AlON transparent ceramics through sintering and post-processing processes, providing more efficient and safer protection and observation windows for military and national defense applications. In the field of optical devices, the wide spectral transmittance and low optical absorption characteristics of AlON transparent ceramics make them important materials for high-end optical devices such as laser elements, ultraviolet and infrared windows, etc. In the field of electronic devices, AlON ceramics are widely used in microwave windows, antenna covers, and high-frequency electronic device packaging due to their excellent dielectric properties and thermal stability. The AlON powder prepared by the present application not only has high purity, but also has good dispersibility and controllable particle size distribution, which is beneficial to the formation of AlON ceramics with uniform structure and stable performance, improving the reliability and working efficiency of electronic devices.

[0040] The present application will be further described in detail below in conjunction with specific embodiments, which should not be understood as limiting the scope of the application claimed.

[0041] Unless otherwise defined, all professional terms used herein have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present application.

[0042] Example 1

[0043] A preparation method of an AlON powder:

[0044] AlN powder with D50 of 3 μm and purity greater than 99.9 wt.% and Al2O3 powder with D50 of 0.5 μm and purity greater than 99.9 wt.% are used as raw materials, wherein 2.589 g (27 mol%) of AlN powder and 17.411 g (73 mol%) of Al2O3 powder are weighed.

[0045] (1) Put the weighed AlN powder into a corundum ball mill tank, use anhydrous ethanol as an organic solvent, and use alumina balls as grinding balls, refine at a speed of 200 rpm for 12 h to obtain a first slurry.

[0046] (2) The weighed Al2O3 powder was added to the ball mill tank to obtain a mixed slurry. Then, AlON powder with a D50 of 0.5 μm was prepared as a seed crystal, 1.053 g (5 wt.%) of the powder was weighed and added to the mixed slurry to form a new mixed slurry, and the slurry was ball milled at a speed of 800 rpm for 4 h.

[0047] (3-1) The slurry after ball milling in step (2) was dried in a forced air drying oven, dried at 70°C for 3 h to obtain a mixed powder.

[0048] (3-2) The powder obtained in step (3-1) was loaded into a graphite crucible with a boron nitride coating, and placed in a high-temperature sintering furnace. After the vacuum was stopped at 1 Pa, non-flowing high-purity nitrogen gas was introduced at a flow rate of 1 L / min to maintain the nitrogen pressure in the sintering furnace at 10 kPa. Then, the temperature was raised to 1200°C at a rate of 20 min / °C, and then to 1680°C at a rate of 10°C / min. After holding for 30 min, the furnace was cooled to room temperature to obtain a white powder.

[0049] (3-3) The white powder obtained in step (3-2) was placed in a corundum ball mill tank, and alumina balls were used as grinding balls. The powder was refined by dry ball milling at a speed of 100 rpm for 5 min to obtain an AlON powder.

[0050] The obtained AlON powder was analyzed by XRD, and it was found that the composition was a single γ-AlON phase, and the results are shown in Figure 1 .

[0051] Example 2

[0052] A method for preparing an AlON powder:

[0053] AlN powder with a D50 of 3 μm and a purity of greater than 99.9 wt.% and Al2O3 powder with a D50 of 0.5 μm and a purity of greater than 99.9 wt.% were used as raw materials, wherein 2.037 g (22 mol%) of AlN powder and 17.963 g (78 mol%) of Al2O3 powder were weighed.

[0054] (1) The weighed AlN powder was placed in a corundum ball mill tank, anhydrous ethanol was used as an organic solvent, and alumina balls were used as grinding balls. The slurry was refined by ball milling at a speed of 200 rpm for 12 h to obtain a first slurry.

[0055] (2) The weighed Al2O3 powder was added to the ball mill tank to obtain a mixed slurry. Then, AlON powder with a D50 of 0.5 μm was prepared as a seed crystal, 1.622 g (7.5 wt.%) of the powder was weighed and added to the mixed slurry to form a new mixed slurry, and the slurry was ball milled at a speed of 800 rpm for 4 h.

[0056] (3-1) The slurry after ball milling in step (2) was dried in a blast drying oven for 3 h at 70°C to obtain a mixed powder.

[0057] (3-2) The powder obtained in step (3-1) was loaded into a graphite crucible coated with boron nitride and placed in a high-temperature sintering furnace. After the vacuum was stopped at 1 Pa, non-flowing high-purity nitrogen gas was introduced at a flow rate of 1 L / min to maintain the nitrogen pressure in the sintering furnace at 10 kPa. Then, the temperature was raised to 1200°C at a rate of 20 min / °C, and then to 1680°C at a rate of 10°C / min. After holding for 20 min, the furnace was cooled to room temperature to obtain a white powder.

[0058] (3-3) The white powder obtained in step (3-2) was placed in a corundum ball mill tank, and alumina balls were used as grinding balls. The powder was refined by dry ball milling at a speed of 100 rpm for 5 min to obtain an AlON powder.

[0059] In this example, the composition of the obtained AlON powder is a single γ-AlON phase.

[0060] Example 3

[0061] A method for preparing an AlON powder:

[0062] AlN powder with a D50 of 3 μm and a purity of greater than 99.9 wt.% and Al2O3 powder with a D50 of 0.5 μm and a purity of greater than 99.9 wt.% were used as raw materials, wherein 1.826 g (20 mol%) of AlN powder and 18.174 g (80 mol%) of Al2O3 powder were weighed.

[0063] (1) The weighed AlN powder was placed in a corundum ball mill tank, anhydrous ethanol was used as an organic solvent, and alumina balls were used as grinding balls. The powder was refined by ball milling at a speed of 200 rpm for 12 h to obtain a first slurry.

[0064] (2) The weighed Al2O3 powder was added to the ball mill tank to obtain a mixed slurry. Then, AlON powder with a D50 of 0.5 μm was prepared as a seed crystal, 1.053 g (5 wt%) of the powder was added to the mixed slurry to form a new mixed slurry, and the new mixed slurry was ball milled at a speed of 500 rpm for 4 h.

[0065] (3-1) The slurry after ball milling in step (2) was dried in a blast drying oven for 3 h at 70°C to obtain a mixed powder.

[0066] (3-2) The powder obtained in step (3-1) was loaded into a graphite crucible with boron nitride coating, and was placed in a high-temperature sintering furnace. After vacuum was drawn to 1 Pa, the vacuum was stopped, and non-flowing high-purity nitrogen gas was introduced at a flow rate of 1 L / min, so that the nitrogen gas pressure in the sintering furnace was maintained at 10 kPa. Then, the temperature was raised to 1200°C at a rate of 20 min / °C, and then the temperature was raised to 1700°C at a rate of 10°C / min. After maintaining the temperature for 20 min, the furnace was cooled to room temperature, and a white powder was obtained.

[0067] (3-3) The white powder obtained in step (3-2) was placed in a corundum ball mill jar, and dry ball milling was performed for 5 min at a speed of 100 rpm using alumina balls as the grinding balls, so that the powder was refined, and an AlON powder was obtained.

[0068] In this example, the composition of the obtained AlON powder was a single γ-AlON phase.

[0069] Example 4

[0070] A method for preparing an AlON powder:

[0071] An AlN powder with a D50 of 5 μm and a purity of more than 99.9 wt.% and an Al2O3 powder with a D50 of 1 μm and a purity of more than 99.9 wt.% were used as raw materials, wherein 2.253 g (24 mol%) of the AlN powder and 17.747 g (76 mol%) of the Al2O3 powder were weighed.

[0072] (1) The weighed AlN powder was placed in a corundum ball mill jar, and dry ball milling was performed for 12 h at a speed of 200 rpm using anhydrous ethanol as the organic solvent and alumina balls as the grinding balls, so that the powder was refined, and a first slurry was obtained.

[0073] (2) The weighed Al2O3 powder was added to the ball mill jar to obtain a mixed slurry. Then, an AlON powder with a D50 of 1 μm was prepared as a seed crystal, 1.622 g (7.5 wt%) of the powder was weighed and added to the mixed slurry to form a new mixed slurry, and ball milling was performed at a speed of 500 rpm for 4 h.

[0074] (3-1) The slurry after ball milling in step (2) was dried in a forced air drying oven, and a mixed powder was obtained after drying at 70°C for 3 h.

[0075] (3-2) The powder obtained in step (3-1) was loaded into a graphite crucible with boron nitride coating, and was placed in a high-temperature sintering furnace. After vacuum was drawn to 1 Pa, the vacuum was stopped, and non-flowing high-purity nitrogen gas was introduced at a flow rate of 1 L / min, so that the nitrogen gas pressure in the sintering furnace was maintained at 10 kPa. Then, the temperature was raised to 1200°C at a rate of 20 min / °C, and then the temperature was raised to 1700°C at a rate of 10°C / min. After maintaining the temperature for 20 min, the furnace was cooled to room temperature, and a white powder was obtained.

[0076] (3-3) The white powder obtained in step (3-2) was put into a corundum ball mill tank, with alumina balls as grinding balls, and dry ball milling was carried out at a speed of 100 rpm for 5 min for powder refinement treatment, to obtain an AlON powder.

[0077] In this example, the composition of the obtained AlON powder was a single γ-AlON phase.

[0078] Example 5

[0079] A method for preparing an AlON powder comprises the following steps:

[0080] An AlN powder with a D50 of 5 μm and a purity of more than 99.9 wt.% and an Al2O3 powder with a D50 of 1 μm and a purity of more than 99.9 wt.% were used as raw materials, wherein 1.826 g (20 mol%) of the AlN powder and 18.174 g (80 mol%) of the Al2O3 powder were weighed.

[0081] (1) The weighed AlN powder was put into a corundum ball mill tank, with anhydrous ethanol as an organic solvent, and alumina balls as grinding balls, and ball milling was carried out at a speed of 200 rpm for 12 h for refinement, to obtain a first slurry.

[0082] (2) The weighed Al2O3 powder was added into the ball mill tank to obtain a mixed slurry. Then, an AlON powder with a D50 of 1 μm was prepared as a seed crystal, 1.053 g (5 wt%) of the powder was weighed and added into the mixed slurry to form a new mixed slurry, and ball milling was carried out at a speed of 600 rpm for 4 h.

[0083] (3-1) The slurry after ball milling in step (2) was dried in a blast drying oven, and mixed powder was obtained by drying at 70 °C for 3 h.

[0084] (3-2) The powder obtained in step (3-1) was loaded into a graphite crucible with a boron nitride coating, and was put into a high-temperature sintering furnace. After the vacuum was stopped at 1 Pa, non-flowing high-purity nitrogen gas was introduced at a flow rate of 1 L / min, so that the nitrogen gas pressure in the sintering furnace was maintained at 10 kPa. Then, the temperature was raised to 1200 °C at a rate of 20 min / °C, and then raised to 1680 °C at a rate of 10 °C / min, and held for 30 min, and then cooled to room temperature with the furnace, to obtain a white powder.

[0085] (3-3) The white powder obtained in step (3-2) was put into a corundum ball mill tank, with alumina balls as grinding balls, and dry ball milling was carried out at a speed of 100 rpm for 5 min for powder refinement treatment, to obtain an AlON powder.

[0086] In this example, the composition of the obtained AlON powder was a single γ-AlON phase.

[0087] Example 6

[0088] A method for preparing an AlON powder comprises the following steps:

[0089] The difference between this example and Example 1 is that in step (2), the rotation speed of wet ball milling is changed to 400 rpm.

[0090] In the obtained AlON powder, a small amount of AlN powder and Al2O3 powder remains. Because the rotation speed of ball milling is low, the effect of breaking and refining the particles of the raw material powder is reduced, which leads to a small effective contact area of the AlN powder and Al2O3 powder, low energy introduced by ball milling, low particle energy, small activity, and few lattice defects, and a slight decrease in the degree of reaction, resulting in a small amount of residual raw material impurities.

[0091] Example 7

[0092] A method for preparing an AlON powder comprises the following steps:

[0093] The difference between this example and Example 1 is that in step (2), the rotation speed of wet ball milling is changed to 1000 rpm.

[0094] In the AlON powder obtained in this example, because the rotation speed of ball milling is high, leading to high abrasion, there are a small amount of impurities from the components of the grinding ball and the ball milling tank.

[0095] Example 8

[0096] A method for preparing an AlON powder comprises the following steps:

[0097] The difference between this example and Example 1 is that in step (3-2), specifically, the powder obtained in step (3-1) is loaded into a graphite crucible with a boron nitride coating, and is placed in a high-temperature sintering furnace. After the vacuum is extracted to 1 Pa, the vacuum extraction is stopped, and non-flowing high-purity nitrogen gas is introduced at a flow rate of 5 L / min, so that the nitrogen gas pressure in the sintering furnace is maintained at 15 kPa. Then, the temperature is raised to 1200°C at a rate of 20 min / °C, and then the temperature is raised to 1680°C at a rate of 10°C / min. After 30 min of heat preservation, the furnace is cooled to room temperature, and a white powder is obtained.

[0098] In the AlON powder obtained in this example, a small amount of AlN powder remains. Because the amount of introduced nitrogen gas is large, part of the Al2O3 powder is converted into AlN powder, and the content of Al2O3 powder is reduced, and a small amount of AlN powder not involved in the solid-phase reaction remains in the product.

[0099] Example 9

[0100] A method for preparing an AlON powder comprises the following steps:

[0101] The difference between this example and Example 1 is only in step (3-2), specifically: the powder obtained in step (3-1) is loaded into a graphite crucible with a boron nitride coating, and is placed in a high-temperature sintering furnace. After the vacuum is drawn to 1 Pa, the vacuum is stopped, and non-flowing high-purity nitrogen gas is introduced at a flow rate of 0.5 L / min, so that the nitrogen gas pressure in the sintering furnace is maintained at 5 kPa. Then, the temperature is raised to 1200°C at a rate of 20 min / °C, and then the temperature is raised to 1680°C at a rate of 10°C / min. After maintaining the temperature for 30 min, the furnace is cooled to room temperature, and a white powder is obtained.

[0102] In the AlON powder obtained in this example, a small amount of Al2O3 powder remains. This is because the AlN powder is easily decomposed at high temperatures under the condition of less nitrogen gas being introduced, resulting in a decrease in the content of AlN powder, and thus a small amount of Al2O3 powder that did not participate in the solid-phase reaction remains in the product.

[0103] Example 10

[0104] A method for producing an AlON powder:

[0105] The difference between this example and Example 1 is only in step (3-2), specifically: the calcination temperature is changed to 1600°C, and the holding time is changed to 60 min.

[0106] In the product obtained in this example, a large amount of AlN powder and Al2O3 powder remains. This is because the temperature is low, and the degree of solid-phase reaction is low, so that the raw material powder remains in the product.

[0107] Example 11

[0108] A method for producing an AlON powder:

[0109] The difference between this example and Example 1 is only in step (3-2), specifically: the calcination temperature is changed to 1800°C, and the holding time is changed to 10 min.

[0110] The product obtained in this example is a white block structure, and although the phase composition is a single γ-AlON structure, the powder has agglomerated due to the high temperature, so that additional crushing treatment is required in subsequent applications. At the same time, the size of the crystal grains in the obtained powder has also grown.

[0111] Comparative Example 1

[0112] A method for producing an AlON powder:

[0113] The difference between this comparative example and Example 1 is only that AlON powder is not added as a seed crystal.

[0114] The AlON powder obtained is analyzed by XRD to find that the composition is a mixture of AlN, Al2O3 and AlON in three phases, and the results are shown in Figure 2

[0115] By comparison, it can be seen that: Figure 1 The XRD pattern results of Example 1 show that the sintered powder presents a single γ-AlON phase structure, while Figure 2 The XRD pattern results of Comparative Example 1 show that the sintered powder presents AlN, Al2O3 and AlON three phase structures. By comparing Example 1 and Comparative Example 1, under the condition that other conditions are the same, the AlON powder is doped as a crystal seed in the raw material mixing process in the present application, and combined with ball milling, the reaction is promoted, and single-phase AlON powder is successfully prepared at a lower temperature and in a shorter time.

[0116] Comparative Example 2

[0117] A preparation method of an AlON powder:

[0118] The difference between this comparative example and Example 3 is only that no AlON powder is added as a crystal seed.

[0119] The AlON powder obtained is analyzed by XRD to find that the composition is a mixture of AlN, Al2O3 and AlON in three phases.

[0120] Comparative Example 3

[0121] A preparation method of an AlON powder:

[0122] The difference between this comparative example and Example 1 is only that the weight content of the added AlON powder is changed to 1wt%.

[0123] In the AlON powder obtained in this comparative example, a large amount of unreacted AlN powder and Al2O3 powder remains. Because the content of the added AlON powder is too low, the reaction is extremely incomplete in a low temperature and short time.

[0124] Comparative Example 4

[0125] A preparation method of an AlON powder:

[0126] The difference between this comparative example and Example 1 is only that the weight content of the added AlON powder is changed to 25wt%.

[0127] In the AlON powder obtained in this comparative example, a large amount of unreacted AlN powder and Al2O3 powder remains. Because the content of the added AlON powder is too high, the AlN powder and the Al2O3 powder are hindered from contacting, resulting in incomplete reaction and a large amount of raw materials remaining.

[0128] ​Comparative Example 5

[0129] A method for preparing AlON powder:

[0130] The difference between this comparative example and Example 1 is that step (1) is not performed, and instead the AlN powder, Al2O3 powder and AlON powder are directly added to anhydrous ethanol and wet ball-milled under the conditions of step (2).

[0131] In the obtained AlON powder, a large amount of unreacted AlN powder and Al2O3 powder remains. This is because the raw materials AlN powder and Al2O3 powder and AlON powder have a large difference in particle size, and it is difficult to mix uniformly in the second wet ball-milling stage, so the reaction is not complete. At the same time, the larger particle size means that the reactivity is low, the atomic diffusion is slow, the reaction is not complete, and a large amount of raw materials remains.

[0132] From the above description, it can be seen that the AlON powder prepared by the above-described embodiments of the present application is composed of a γ-AlON phase, with no secondary phase remaining.

[0133] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those described herein.

[0134] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. 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 method of making an AlON powder, comprising: The application relates to an AlON powder preparation method. ​ S1, a first-stage wet ball milling treatment is performed on AlN powder to obtain a first slurry; S2, Al2O3 powder, AlON seeds and the first slurry are mixed and then subjected to a second-stage wet ball milling treatment to obtain a second slurry; the D50 of the AlON seeds is 0.5-1 mu m; S3, the second slurry is subjected to a drying treatment to obtain a precursor powder; the precursor powder is subjected to a calcination treatment and a refining treatment in sequence to obtain the AlON powder; The AlON seeds are added in an amount of 5-20% based on the total weight of the AlN powder, the Al2O3 powder and the AlON seeds.

2. The method of claim 1, wherein the AlON powder is prepared by the steps of: The molar ratio of the AlN powder to the Al2O3 powder is (20-27):(73-80); Preferably, the AlON seeds are added in an amount of 5-10% based on the total weight of the AlN powder, the Al2O3 powder and the AlON seeds.

3. The method of claim 1 or 2, wherein the AlON powder is prepared by the steps of: The D50 of the AlN powder is 3-5 mu m; and / or the D50 of the Al2O3 powder is 0.5-1 mu m; Preferably, the purity of the AlN powder is greater than or equal to 99.9 wt.%; and / or the purity of the Al2O3 powder is greater than or equal to 99.9 wt.%.

4. The method of producing an AlON powder according to any one of claims 1 to 3, characterized by, In the step S1, the AlN powder is mixed with a dispersant, and then subjected to the first-stage wet ball milling treatment at a rotating speed of 200+ / -50 rpm for 12+ / -2 hours to obtain the first slurry; Preferably, the dispersant is selected from one or more of ethanol, isopropanol and n-butanol.

5. The method of producing an AlON powder according to any one of claims 1 to 4, characterized by, In the step S2, the rotating speed of the second-stage wet ball milling treatment is 500-800 rpm; and / or the time of the second-stage wet ball milling treatment is 4-6 hours.

6. The method of producing an AlON powder according to any one of claims 1 to 5, characterized in that, In the step S3, The calcination temperature of the calcination treatment is 1650-1700 DEG C, and the holding time is 10-40 minutes; and / or The calcination treatment is performed in nitrogen.

7. The method of claim 6 wherein the AlON powder is prepared by the process of claim 1 and wherein the AlON powder has a particle size of less than 1 micron. In the step S3, the calcination treatment comprises a temperature rising process and a holding process, and the temperature rising process comprises a first temperature rising stage and a second temperature rising stage performed in sequence; The temperature rising rate of the first temperature rising stage is 20+ / -2 DEG C / min, so that the temperature reaches 1200+ / -50 DEG C; the temperature rising rate of the second temperature rising stage is 10+ / -1 DEG C / min, so that the temperature reaches the calcination temperature; and then the holding process is performed; Preferably, before the calcination treatment, the step S3 further comprises: placing a crucible containing the precursor powder in a sintering furnace, and performing a vacuumizing treatment on the sintering furnace until the air pressure in the sintering furnace is 1+ / -0.05 Pa; then nitrogen is introduced into the sintering furnace, and the calcination treatment is performed at 10+ / -0.5 kPa; More preferably, the crucible is selected from a graphite crucible, a boron nitride crucible or a graphite crucible with a boron nitride coating; Further preferably, the gas inlet flow rate of the protective gas is 0.4-1 L / min.

8. The method of producing an AlON powder according to any one of claims 1 to 7, characterized by, In the step S3, the refinement treatment is achieved by dry ball milling, and the rotation speed of the dry ball milling is 100±20 rpm, and the time is 5±0.5 min. Preferably, the grinding jar used in the dry ball milling is selected from a corundum jar, a nylon jar or an agate jar; and the grinding ball used in the dry ball milling is selected from an alumina ball, a zirconia ball or an agate ball.

9. An AlON powder, characterized by, The AlON powder is prepared by the method for preparing the AlON powder according to any one of claims 1 to 8, and the phase composition of the AlON powder is a single γ-AlON phase.

10. Use of the AlON powder according to claim 9 as a powder material in the field of national defense security, the field of optical devices and the field of electronic devices.

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