Aluminum nitride powder and preparation method thereof

Abstract

The invention relates to aluminum nitride powder and a preparation method thereof.The method comprises the steps that in the oxygen-isolated environment, anhydrous aluminum chloride is subjected to multiple times of first purification, and aluminum chloride with the set purity is obtained; the aluminum chloride with the set purity, a complexing agent and a solvent are subjected to a complexation reaction, so that the aluminum chloride with the set purity is subjected to second purification, and a first mixed solution is obtained; filtering the first mixed solution, and then drying a filter cake material obtained by filtering; and in an oxygen-isolated environment, carrying out heat treatment on the dried filter cake material to obtain the aluminum nitride powder. The aluminum nitride powder prepared by the invention meets the following indexes: the oxygen content is less than 0.8%, the particle size is 0.9-1.4 mu m, and the specific area is greater than 2.0 m < 2 > / g.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum nitride powder, and in particular to an aluminum nitride powder and a preparation method thereof. Background Art

[0002] AlN (aluminum nitride) is a III-V semiconductor compound. The crystal is a covalent bond compound with [AlN4] tetrahedron as the structural unit, belonging to the hexagonal system. Compared with traditional ceramic materials, AlN materials have many more excellent properties, such as high thermal conductivity (about 10 times that of Al2O3 materials), good electrical insulation, small thermal expansion coefficient, similar to single crystal silicon, high mechanical strength, good thermal stability, non-toxicity, etc., so it has good application prospects in many fields such as electronics, electricity, information, transportation, aerospace, and military industry. It can replace highly toxic beryllium oxide as substrate and packaging material in high-power integrated circuits and semiconductor module circuits; it can be used as heat sink packaging and additive materials in power module circuits, silicon-controlled rectifiers, and high-voltage power insulators; it can be used as additives in high-temperature crucibles, heat-resistant coatings, and advanced refractory materials, etc. As a new type of ceramic material, aluminum nitride has the characteristics of high thermal conductivity and high insulation. It is currently mainly used in high-power module substrates in the electronics industry. Aluminum nitride has the advantages of high thermal conductivity, high resistivity, and high dielectric constant, making it a key material for the new generation of electronic substrates.

[0003] However, the current preparation process of aluminum nitride powder is long, and impurities are inevitably introduced during the synthesis, making it difficult to obtain high-purity aluminum nitride powder. Summary of the invention

[0004] The present application provides an aluminum nitride powder and a preparation method thereof to solve the following technical problem: how to improve the purity of aluminum nitride powder.

[0005] In a first aspect, the present application provides a method for preparing aluminum nitride powder, the method comprising:

[0006] In an environment isolated from oxygen, the anhydrous aluminum chloride is subjected to a first purification multiple times to obtain aluminum chloride powder with a set purity;

[0007] The aluminum chloride with a set purity, a complexing agent and a solvent are subjected to a complexing reaction, so that the aluminum chloride with a set purity is subjected to a second purification to obtain a first mixed solution;

[0008] Filtering the first mixed solution, and then drying the filter cake material obtained by filtration;

[0009] In an environment isolated from oxygen, the dried filter cake material is heat treated to obtain aluminum nitride powder.

[0010] Optionally, the first purification includes heating and cooling; wherein the heating temperature is 178°C to 200°C, and the cooling temperature is 129°C to 159°C.

[0011] Optionally, the set purity is ≥99.991%.

[0012] Optionally, the complexing agent includes at least one of the following: diethylenetriamine pentacarboxylate, ethylenediaminetetraacetic acid, o-phenanthroline, monoethanolamine, triethanolamine, dimercaptopropanol, and thiourea.

[0013] Optionally, the solvent includes a first solvent and a second solvent; wherein the first solvent includes water;

[0014] The second solvent includes at least one of the following: methanol, ethanol, isopropanol, ethyl ether, ethylene oxide, ethylene glycol monomethyl ether, chlorobenzene, acetone, and toluene.

[0015] Optionally, in terms of weight fraction, the weight of the aluminum chloride with a set purity is 39% to 61%, the weight of the complexing agent is 8% to 15%, the weight of the first solvent is 24% to 36%, and the weight of the second solvent is 7% to 10%.

[0016] Optionally, the dried filter cake material is heat treated to obtain aluminum nitride powder, comprising:

[0017] The dried filter cake material is subjected to a first heat treatment to obtain ammonia gas and aluminum salt;

[0018] The ammonia gas and the aluminum salt are subjected to a second heat treatment so that the aluminum salt is sublimated into a gas to react with the ammonia gas to obtain aluminum nitride powder.

[0019] Optionally, the temperature of the first heat treatment is 650°C to 850°C; and / or the temperature of the second heat treatment is 950°C to 1200°C.

[0020] In a second aspect, the present application provides an aluminum nitride powder prepared by the method described in any embodiment of the first aspect.

[0021] Optionally, the aluminum nitride powder meets the following indicators: oxygen content <0.8%, particle size of 0.9 μm to 1.4 μm, specific area greater than 2.0 m 2 / g.

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The preparation method of the aluminum nitride powder provided in the embodiment of the present application comprises: in an environment isolated from oxygen, anhydrous aluminum chloride is subjected to multiple first purifications to obtain aluminum chloride with a set purity; the aluminum chloride with a set purity, a complexing agent and a solvent are subjected to a complexing reaction to enable the aluminum chloride with a set purity to be second purified to obtain a first mixed solution; the first mixed solution is filtered, and then the filter cake material obtained by filtration is dried; in an environment isolated from oxygen, the dried filter cake material is subjected to heat treatment to obtain aluminum nitride powder. In an environment isolated from oxygen, anhydrous aluminum chloride is subjected to multiple first purifications to obtain a high-purity aluminum chloride powder raw material with a set purity; the complexing agent can form a stable complex with the impurity ions in the aluminum chloride with a set purity and does not react significantly with the aluminum chloride, and reduces the influence of pigment impurities, further improving the purity of the aluminum chloride powder raw material; the dried filter cake material obtained after the mixed solution is treated is subjected to heat treatment in an environment isolated from oxygen to prepare aluminum nitride powder, and no impurities are introduced in the preparation process, thereby obtaining high-purity aluminum nitride powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 A schematic diagram of a process for preparing aluminum nitride powder provided in an embodiment of the present application;

[0027] Figure 2 A scanning electron microscope (SEM) image of an aluminum nitride powder provided in Example 3 of the present application;

[0028] Figure 3 An X-ray diffractometer (XRD) of aluminum nitride powder provided in Example 3 of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0030] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0031] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0033] In a first aspect, the present application provides a method for preparing aluminum nitride powder. Figure 1 A schematic diagram of a method for preparing aluminum nitride powder provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0034] S1. In an environment isolated from oxygen, the anhydrous aluminum chloride is subjected to a first purification multiple times to obtain aluminum chloride with a set purity;

[0035] In some embodiments, the first purification includes heating and cooling; wherein the heating temperature is 178°C to 200°C, and the cooling temperature is 129°C to 159°C.

[0036] In some embodiments, the set purity is ≥ 99.991%.

[0037] In the embodiments of the present application, anhydrous aluminum chloride is an important inorganic salt of aluminum, which is usually prepared by chemical processing of bauxite or chlorination of metallic aluminum. Industrial products are often light yellow, gray or orange-yellow because they contain free chlorine, iron, trace amounts of other metal ions, organic matter, etc. The sublimation point of anhydrous aluminum chloride is relatively low, only 177.8°C at normal pressure, while the boiling points of chloride salts formed by other major metal impurities are: SiCl4: 57.6°C; FeCl3: 315°C; NaCl: 1413°C; KCl: 1500°C, which are far from the sublimation point of anhydrous aluminum chloride, and the sublimation-desublimation method can be used to purify anhydrous aluminum chloride.

[0038] After heating, anhydrous aluminum chloride can be sublimated into aluminum chloride gas; aluminum chloride gas is cooled, so that aluminum chloride gas is condensed into solid for collection, and anhydrous aluminum chloride is heated and cooled to achieve the purification effect of aluminum chloride. The sublimation point of anhydrous aluminum chloride under normal pressure is 177.8℃, and the heating temperature can be 178℃~200℃, which can make anhydrous aluminum chloride sublime; if the heating temperature is higher than 200℃, the impurity FeCl3 in anhydrous aluminum chloride may sublime, thereby introducing Fe impurities and increasing energy consumption. The cooling temperature can be 129℃~159℃, so that aluminum chloride gas is condensed and easy to collect, reducing pollution. The heating and cooling can be carried out in different zones, namely the discharge zone (heating) and the collection zone (cooling). When the aluminum chloride is cooled and collected after sublimation, the aluminum chloride that is being sublimated and cooled and the aluminum chloride that is not sublimated will not be mixed together, which has a purification effect. Exemplarily, the heating temperature may be 178°C, 180°C, 182°C, 184°C, 186°C, 188°C, 190°C, 192°C, 194°C, 196°C, 198°C, 200°C, etc., and the cooling temperature may be 129°C, 130°C, 132°C, 134°C, 136°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C, 150°C, 152°C, 154°C, 156°C, 159°C, etc. Aluminum chloride having a set purity may be obtained by subjecting anhydrous aluminum chloride to multiple first purifications, and the set purity may be 99.991%, 99.993%, 99.992%, 99.994%, etc. The first purification can be repeated three to four times; in an environment isolated from oxygen, that is, under the protection of a nitrogen atmosphere, the nitrogen flow rate is 1.0L / min to 3.0L / min. Furthermore, the sublimation and desublimation purification of anhydrous aluminum chloride is carried out more than three times in a dual-temperature structure device; the sublimation and purification device has two temperature zones: a discharge zone and a collection zone, which are heated by two independently controlled heaters respectively. The lower part of the device is the discharge zone, and the top is the collection zone. Heaters with precise temperature control are installed outside the two zones. The inner tank of the device is a cylindrical structure with sealed upper and lower ends. The material is inert glass or quartz. The top is separated and can be disassembled.

[0039] Step S1 comprises: placing anhydrous aluminum chloride in a heating zone (discharging zone), the top of which is a cooling zone (collecting zone), and a heater with precise temperature control is installed outside each of the two zones. The temperature of the heater in the discharging zone is 178°C to 200°C, and the temperature of the heater in the collecting zone is 129°C to 159°C. After all the aluminum chloride in the discharging zone is sublimated, the heater is turned off, and the anhydrous aluminum chloride is taken out from the collecting zone. The whole process is carried out under a nitrogen protective atmosphere; the discharging zone is cleaned with deionized water, and the anhydrous aluminum chloride obtained by sublimation and purification in the previous step is re-placed into the discharging zone, and the previous step is repeated. This step can be repeated three to four times.

[0040] S2, carrying out a complex reaction on the aluminum chloride with a set purity, a complexing agent and a solvent, so that the aluminum chloride with a set purity is subjected to a second purification to obtain a first mixed solution;

[0041] In some embodiments, the complexing agent includes at least one of the following: diethylenetriamine pentacarboxylate, ethylenediaminetetraacetic acid, o-phenanthroline, monoethanolamine, triethanolamine, dimercaptopropanol, and thiourea.

[0042] In the embodiment of the present application, the complexing agent can form a stable complex with the impurity ions in the aluminum chloride with a set purity and does not react significantly with the aluminum chloride, and reduces the influence of pigment impurities to achieve the second purification of the aluminum chloride with a set purity. The complexing agent can be a combination of one or more of diethylenetriamine pentacarboxylate (DTPA), ethylenediaminetetraacetic acid, o-phenanthroline, monoethanolamine, triethanolamine, dimercaptopropanol, and thiourea.

[0043] In some embodiments, the solvent comprises a first solvent and a second solvent; wherein the first solvent comprises water;

[0044] The second solvent includes at least one of the following: methanol, ethanol, isopropanol, ethyl ether, ethylene oxide, ethylene glycol monomethyl ether, chlorobenzene, acetone, and toluene.

[0045] In the embodiment of the present application, the first solvent cooperates with the second solvent to dissolve aluminum chloride with a set purity. The first solvent can be water, and the second solvent can be a combination of one or more of methanol, ethanol, isopropanol, ether, ethylene oxide, ethylene glycol monomethyl ether, chlorobenzene, acetone, and toluene.

[0046] In some embodiments, in terms of weight fraction, the weight of the aluminum chloride with a set purity is 39% to 61%, the weight of the complexing agent is 8% to 15%, the weight of the first solvent is 24% to 36%, and the weight of the second solvent is 7% to 10%.

[0047] In the embodiment of the present application, the weight of aluminum chloride with a set purity can be 39% to 61%, the weight of the complexing agent can be 8% to 15%, the weight of the first solvent can be 24% to 36%, and the weight of the second solvent can be 7% to 10%, so that the solvent can fully dissolve and disperse the aluminum chloride with a set purity, and the complexing agent can fully react with the impurity ions in the aluminum chloride with a set purity to form a stable complex, further purifying the aluminum chloride with a set purity. Therefore, the aluminum chloride powder, the complexing agent and the solvent can play their respective roles, use the coupling effect and the synergistic effect, and form a good first mixed solution system. Exemplarily, the weight of aluminum chloride with a set purity can be 39%, 43%, 45%, 48%, 50%, 53%, 55%, 58%, 61%, etc.; the weight of the complexing agent can be 8%, 10%, 12%, 14%, 15%, etc.; the weight of the first solvent can be 24%, 26%, 28%, 30%, 32%, 34%, 36%, etc.; the weight of the second solvent can be 7%, 8%, 9%, 10%, etc. Step S2 specifically includes: mixing aluminum chloride with a set purity and a solvent, dispersing and dissolving them by magnetic stirring, the magnetic stirring speed is not less than 500r / min, and the stirring time is 30min~60min; then adding the complexing agent to the mixed solution of aluminum chloride with a set purity and the solvent, and stirring under the action of magnetic stirring to carry out a complexing reaction, the stirring speed is not less than 350r / min, and the stirring time is 150min~240min.

[0048] S3, filtering the first mixed solution, and then drying the filter cake material obtained by filtration; the drying temperature can be 110° C. to 150° C., and the drying time can be 2 h to 3 h.

[0049] S4. In an environment isolated from oxygen, heat-treating the dried filter cake material to obtain aluminum nitride powder.

[0050] In some embodiments, the drying of the filter cake material is heat treated to obtain aluminum nitride powder, comprising:

[0051] The dried filter cake material is subjected to a first heat treatment to obtain ammonia gas and aluminum salt;

[0052] The ammonia gas and the aluminum salt are subjected to a second heat treatment so that the aluminum salt is sublimated into a gas to react with the ammonia gas to obtain aluminum nitride powder.

[0053] In some embodiments, the temperature of the first heat treatment is 650°C to 850°C; and / or the temperature of the second heat treatment is 950°C to 1200°C.

[0054] In the embodiment of the present application, the dried filter cake material is subjected to a first heat treatment, and the temperature of the first heat treatment can be 650°C to 850°C, so that the dried filter cake material is thermally decomposed, and the thermal decomposition generates a mixture of carbon-containing compounds and aluminum salts (low melting point), and the carbon-containing compounds are decomposed to form ammonia under the condition of the temperature of the first heat treatment, thereby obtaining ammonia and aluminum salts. If the temperature of the first heat treatment is higher than 850°C, the structure of the carbon-containing compounds and aluminum salts produced by the pyrolysis may be destroyed, and it is difficult to obtain aluminum nitride powder; if the temperature of the first heat treatment is lower than 650°C, it may be difficult to completely thermally decompose the dried filter cake material. Exemplarily, the temperature of the first heat treatment can be 650°C, 680°C, 700°C, 730°C, 750°C, 780°C, 800°C, 830°C, 850°C, etc. In addition, the time of the first heat treatment can be 1.5h to 3h. Ammonia and aluminum salt are subjected to a second heat treatment so that the aluminum salt sublimates into gas and reacts with ammonia. The temperature of the second heat treatment can be 950°C to 1200°C, which can make the nitridation reaction of ammonia and aluminum salt complete and generate high-purity fine-grained aluminum nitride powder. Exemplarily, the temperature of the second heat treatment can be 950°C, 980°C, 1000°C, 1030°C, 1050°C, 1080°C, 1100°C, 1130°C, 1150°C, 1180°C, 1200°C, etc. In addition, the time of the second heat treatment can be 1h to 2.5h. The heat treatment is carried out in an environment isolated from oxygen, that is, in a protective atmosphere. The protective atmosphere can be nitrogen or argon, and the protective gas flow rate can be 1.2L / min to 5.0L / min.

[0055] In a second aspect, the present application provides an aluminum nitride powder prepared by the method described in any embodiment of the first aspect.

[0056] In some embodiments, the aluminum nitride powder meets the following indicators: oxygen content <0.8%, particle size of 0.9 μm to 1.4 μm, specific area greater than 2.0 m 2 / g.

[0057] In the embodiment of the present application, the aluminum nitride powder can meet the following indicators: oxygen content <0.8%, particle size of 0.9 μm to 1.4 μm, specific area greater than 2.0 m 2 / g. The aluminum nitride powder prepared by the above method has high purity, low oxygen content, high quality, small particle size and large ratio (greater than 2.0m 2 / g), which can be used as raw materials for high-quality ceramic substrates, electronic packaging materials, and thermal conductivity of fine devices. Compared with existing aluminum nitride products, it fills the high-end application field and application range. No impurities are introduced during its preparation process, and there is no need for carbon thermal reduction reaction and subsequent decarburization, which shortens the preparation process and reduces the preparation cost.

[0058] The aluminum nitride powder is realized based on the preparation method of the aluminum nitride powder mentioned above. The specific steps of the preparation method of the aluminum nitride powder can refer to the above embodiment. Since the aluminum nitride powder adopts part or all of the technical solutions of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be repeated here one by one.

[0059] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0060] Example 1

[0061] A method for preparing aluminum nitride powder, comprising:

[0062] S11. In an environment isolated from oxygen, the anhydrous aluminum chloride is subjected to a first purification multiple times to obtain aluminum chloride with a set purity; wherein the first purification includes heating and cooling, the heating temperature is 180° C., the cooling temperature is 135° C., the first purification is repeated three times, and the purity is set to 99.993%;

[0063] Step S1 specifically includes: taking 200g of anhydrous aluminum chloride, placing it in the discharge area, setting the temperature of the heater in the discharge area to 180°C, and the temperature of the heater in the collection area to 135°C, and taking out the collection area after 2 hours to obtain 190g of anhydrous aluminum chloride that has been sublimated and purified once, and the purification is carried out under the protection of a nitrogen atmosphere, with a nitrogen flow rate of 1.2L / min. Repeat the sublimation purification process three times to obtain 171g of pure aluminum chloride powder.

[0064] S21, performing a complex reaction on aluminum chloride with a set purity, a complexing agent, and a solvent, so that the aluminum chloride with the set purity is second purified to obtain a first mixed solution;

[0065] Step S2 specifically includes: preparing a mixed solution, in which, by weight, the weight of aluminum chloride with a set purity is 45%, the weight of ethanol is 10%, and the weight of deionized water is 34%, and dispersing and dissolving by magnetic stirring at a stirring speed of 550 r / min for 30 min to obtain a mixed slurry; adding 11% by weight of diethylenetriamine pentacarboxylate (DTPA) to the mixed slurry, and using magnetic stirring at a stirring speed of 450 r / min for 180 min to carry out a complex reaction to obtain a first mixed solution.

[0066] S31, filtering the first mixed solution, and then drying the filter cake material obtained by filtration; wherein the drying temperature is 115° C. and the drying time is 3 hours;

[0067] S41. In an environment isolated from oxygen, the dried filter cake material is heat-treated to obtain aluminum nitride powder; wherein, the dried filter cake material is subjected to a first heat treatment to obtain ammonia and aluminum salt; the ammonia and aluminum salt are subjected to a second heat treatment to allow the aluminum salt to sublime into a gas to react with ammonia to obtain aluminum nitride powder; the heat treatment is carried out in a nitrogen protective gas flow rate of 1.5 L / min, the temperature of the first heat treatment is 650°C, and the time of the first heat treatment is 2 hours; the temperature of the second heat treatment is 950°C, and the time of the second heat treatment is 1 hour.

[0068] Example 2

[0069] A method for preparing aluminum nitride powder, comprising:

[0070] S12. In an environment isolated from oxygen, the anhydrous aluminum chloride is subjected to a first purification multiple times to obtain aluminum chloride with a set purity; wherein the first purification includes heating and cooling, the heating temperature is 186° C., the cooling temperature is 140° C., the first purification is repeated three times, and the purity is set to 99.995%;

[0071] Step S1 specifically includes: taking 200g of anhydrous aluminum chloride, placing it in the discharge area, setting the temperature of the heater in the discharge area to 186°C, and the temperature of the heater in the collection area to 140°C, and taking out the collection area after 2 hours to obtain 186g of anhydrous aluminum chloride that has been sublimated and purified once, and the purification is carried out under the protection of a nitrogen atmosphere, with a nitrogen flow rate of 1.7L / min. Repeat the sublimation purification process three times to obtain 167g of pure aluminum chloride powder.

[0072] S22, performing a complex reaction on aluminum chloride with a set purity, a complexing agent, and a solvent, so that the aluminum chloride with the set purity is second purified to obtain a first mixed solution;

[0073] Step S2 specifically includes: preparing a mixed solution, in which, by weight, the weight of aluminum chloride with a set purity is 50%, the weight of ethanol is 7%, and the weight of deionized water is 33%, and dispersing and dissolving by magnetic stirring at a stirring speed of 550 r / min for 30 min to obtain a mixed slurry; adding 10% by weight of diethylenetriamine pentacarboxylate (DTPA) to the mixed slurry, and using magnetic stirring at a stirring speed of 450 r / min for 180 min to carry out a complex reaction to obtain a first mixed solution.

[0074] S32, filtering the first mixed solution, and then drying the filter cake material obtained by filtration; wherein the drying temperature is 120° C. and the drying time is 3 hours;

[0075] S42. In an environment isolated from oxygen, the dried filter cake material is heat-treated to obtain aluminum nitride powder; wherein, the dried filter cake material is subjected to a first heat treatment to obtain ammonia and aluminum salt; the ammonia and aluminum salt are subjected to a second heat treatment to allow the aluminum salt to sublime into a gas and react with ammonia to obtain aluminum nitride powder; the heat treatment is carried out in a nitrogen protective gas flow rate of 2 L / min, the temperature of the first heat treatment is 700°C, and the time of the first heat treatment is 2 hours; the temperature of the second heat treatment is 980°C, and the time of the second heat treatment is 1.5 hours.

[0076] Example 3

[0077] A method for preparing aluminum nitride powder, comprising:

[0078] S13, in an environment isolated from oxygen, subjecting anhydrous aluminum chloride to a first purification for multiple times to obtain aluminum chloride with a set purity; wherein the first purification includes heating and cooling, the heating temperature is 190° C., the cooling temperature is 145° C., the first purification is repeated three times, and the purity is set to .99.996%;

[0079] Step S1 specifically includes: taking 200g of anhydrous aluminum chloride, placing it in the discharge area, setting the temperature of the heater in the discharge area to 190°C, and the temperature of the heater in the collection area to 145°C, and taking out the collection area after 2 hours to obtain 192g of anhydrous aluminum chloride that has been sublimated and purified once, and the purification is carried out under the protection of a nitrogen atmosphere with a nitrogen flow rate of 2.0L / min. Repeat the sublimation purification process three times to obtain 175g of pure aluminum chloride powder.

[0080] S23, performing a complex reaction on aluminum chloride with a set purity, a complexing agent, and a solvent, so that the aluminum chloride with the set purity is second purified to obtain a first mixed solution;

[0081] Step S2 specifically includes: preparing a mixed solution, in which, by weight, the weight of aluminum chloride with a set purity is 53%, the weight of ethanol is 9%, and the weight of deionized water is 30%, and the mixed solution is dispersed and dissolved by magnetic stirring at a stirring speed of 550 r / min and a stirring time of 30 min to obtain a mixed slurry; adding 8% by weight of diethylenetriamine pentacarboxylate (DTPA) to the mixed slurry, and using magnetic stirring at a stirring speed of 450 r / min and a stirring time of 180 min to carry out a complex reaction to obtain a first mixed solution.

[0082] S33, filtering the first mixed solution, and then drying the filter cake material obtained by filtration; wherein the drying temperature is 125° C., and the drying time is 2 h;

[0083] S43. In an environment isolated from oxygen, the dried filter cake material is heat-treated to obtain aluminum nitride powder; wherein, the dried filter cake material is subjected to a first heat treatment to obtain ammonia and aluminum salt; the ammonia and aluminum salt are subjected to a second heat treatment to allow the aluminum salt to sublime into a gas to react with ammonia to obtain aluminum nitride powder; the heat treatment is carried out in a nitrogen protective gas flow rate of 3L / min, the temperature of the first heat treatment is 850°C, and the time of the first heat treatment is 2h; the temperature of the second heat treatment is 1150°C, and the time of the second heat treatment is 2h.

[0084] Example 4

[0085] A method for preparing aluminum nitride powder, comprising:

[0086] S14. In an environment isolated from oxygen, the anhydrous aluminum chloride is subjected to a first purification multiple times to obtain aluminum chloride with a set purity; wherein the first purification includes heating and cooling, the heating temperature is 196° C., the cooling temperature is 155° C., the first purification is repeated three times, and the purity is set to 99.991%;

[0087] Step S1 specifically includes: taking 200g of anhydrous aluminum chloride, placing it in the discharge area, setting the temperature of the discharge area heater to 196°C, and the temperature of the collection area heater to 155°C, and taking out the collection area after 2 hours to obtain 191g of anhydrous aluminum chloride that has been sublimated and purified once, and the purification is carried out under the protection of nitrogen atmosphere, with a nitrogen flow rate of 2.8L / min. Repeat the sublimation purification process three times to obtain 173g of pure aluminum chloride powder.

[0088] S24, performing a complex reaction on aluminum chloride with a set purity, a complexing agent, and a solvent, so that the aluminum chloride with the set purity is subjected to a second purification to obtain a first mixed solution;

[0089] Step S2 specifically includes: preparing a mixed solution, in which, by weight, the weight of aluminum chloride with a set purity is 51%, the weight of ethanol is 7%, and the weight of deionized water is 32%, and dispersed and dissolved by magnetic stirring at a stirring speed of 550 r / min for 30 min to obtain a mixed slurry; adding 10% by weight of diethylenetriamine pentacarboxylate (DTPA) to the mixed slurry, and using magnetic stirring at a stirring speed of 450 r / min for 180 min to carry out a complex reaction to obtain a first mixed solution.

[0090] S34, filtering the first mixed solution, and then drying the filter cake material obtained by filtration; wherein the drying temperature is 130° C. and the drying time is 2 h;

[0091] S44. In an environment isolated from oxygen, the dried filter cake material is heat-treated to obtain aluminum nitride powder; wherein, the dried filter cake material is subjected to a first heat treatment to obtain ammonia and aluminum salt; the ammonia and aluminum salt are subjected to a second heat treatment to allow the aluminum salt to sublime into a gas to react with ammonia to obtain aluminum nitride powder; the heat treatment is carried out in a nitrogen protective gas flow rate of 2.5 L / min, the temperature of the first heat treatment is 750°C, and the time of the first heat treatment is 2 hours; the temperature of the second heat treatment is 1050°C, and the time of the second heat treatment is 2.5 hours.

[0092] Example 5

[0093] A method for preparing aluminum nitride powder, comprising:

[0094] S15. In an environment isolated from oxygen, the anhydrous aluminum chloride is subjected to a first purification multiple times to obtain aluminum chloride with a set purity; wherein the first purification includes heating and cooling, the heating temperature is 200° C., the cooling temperature is 159° C., the first purification is repeated three times, and the purity is set to 99.994%;

[0095] Step S1 specifically includes: taking 200g of anhydrous aluminum chloride, placing it in the discharge area, setting the temperature of the discharge area heater to 200°C, and the temperature of the collection area heater to 160°C, and taking out the collection area after 2 hours to obtain 190g of anhydrous aluminum chloride that has been sublimated and purified once, and the purification is carried out under the protection of nitrogen atmosphere, with a nitrogen flow rate of 3.0L / min. Repeat the sublimation purification process three times to obtain 171g of pure aluminum chloride powder.

[0096] S25, performing a complex reaction on aluminum chloride with a set purity, a complexing agent, and a solvent, so that the aluminum chloride with the set purity is subjected to a second purification to obtain a first mixed solution;

[0097] Step S2 specifically includes: preparing a mixed solution, in which, by weight, the weight of aluminum chloride with a set purity is 45%, the weight of ethanol is 10%, and the weight of deionized water is 34%, and dispersing and dissolving by magnetic stirring at a stirring speed of 550 r / min for 30 min to obtain a mixed slurry; adding 11% by weight of diethylenetriamine pentacarboxylate (DTPA) to the mixed slurry, and using magnetic stirring at a stirring speed of 450 r / min for 180 min to carry out a complex reaction to obtain a first mixed solution.

[0098] S35, filtering the first mixed solution, and then drying the filter cake material obtained by filtration; wherein the drying temperature is 115° C. and the drying time is 3 hours;

[0099] S45. In an environment isolated from oxygen, the dried filter cake material is heat-treated to obtain aluminum nitride powder; wherein, the dried filter cake material is subjected to a first heat treatment to obtain ammonia and aluminum salt; the ammonia and aluminum salt are subjected to a second heat treatment to allow the aluminum salt to sublime into a gas and react with ammonia to obtain aluminum nitride powder; the heat treatment is carried out in a nitrogen protective gas flow rate of 4 L / min, the temperature of the first heat treatment is 750°C, and the time of the first heat treatment is 2 hours; the temperature of the second heat treatment is 1100°C, and the time of the second heat treatment is 2 hours.

[0100] Comparative Example 1

[0101] Based on the disclosure of Example 3, the difference between Comparative Example 1 and Example 3 is that the first purification is performed once, and the purity is set to 97.365%.

[0102] Comparative Example 2

[0103] Based on the disclosure of Example 3, the difference between Comparative Example 1 and Example 3 is that the components of the first mixed solution include: 59% by weight of aluminum chloride with a set purity; 3.5% by weight of ethanol; and 35.5% by weight of deionized water. No complexation reaction is performed.

[0104] Comparative Example 3

[0105] Based on the disclosure of Example 3, the difference between Comparative Example 1 and Example 3 is that the second heat treatment temperature is 940°C.

[0106] The aluminum nitride powders prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were tested for various indicators. Please see Table 1 for the test results.

[0107] Table 1 Various indicators of aluminum nitride powder

[0108]

[0109]

[0110] As shown in Table 1, the high-purity fine-grained aluminum nitride powder obtained by the preparation method of aluminum nitride powder provided in the embodiment of the present application has a specific surface area of ​​≥2.6 m 2 / g, oxygen content <0.8%, Ca content <300ppm, Fe content <40ppm. For example, Figure 2 This is a scanning electron microscope (SEM) image of an aluminum nitride powder provided in Example 3 of the present application; see Figure 2, indicating that the aluminum nitride powder is well developed, the crystals are well crystallized, the powder edges are rounded, the dispersion between particles is good, and there is less adhesion. Figure 3 An X-ray diffractometer (XRD) of an aluminum nitride powder provided in Example 3 of the present application; see Figure 3 , indicating that the aluminum nitride powder has high chemical purity, high degree of crystal phase transition, perfect crystallization, and is an aluminum nitride phase. However, the purification times of anhydrous aluminum chloride in Comparative Example 1 are not enough, and the set purity requirement cannot be met; in Comparative Example 2, no complexing agent is used to carry out complexing reaction on aluminum chloride with set purity; and the second heat treatment temperature in Comparative Example 3 is low, so to a certain extent, some indicators in Comparative Examples 1 to 3 in Table 1 are worse than those in Examples 1 to 5.

[0111] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:

[0112] (1) Anhydrous aluminum chloride has low cost and competitive advantage. Industrial anhydrous aluminum chloride is purified by sublimation three to four times to achieve the purpose of purifying raw materials. The complexing agent and aluminum chloride raw materials are then complexed and purified to further improve the purity;

[0113] (2) The first heat treatment in the heat treatment generates a mixture of carbon-containing compounds and aluminum salts (low melting point). The carbon-containing compounds decompose under heating conditions to form ammonia, which is raised to a second heat treatment temperature of above 950°C, so that the ammonia and the aluminum salt sublimated into gas react to prepare high-purity fine-grained aluminum nitride powder. Compared with the current carbon thermal reduction method for preparing aluminum nitride, there is no need to go through the carbon thermal reduction stage (the carbon thermal reduction stage requires heating at a temperature above 1700°C, the insulation time is ≥4 hours, and it consumes power) and subsequent decarburization. Impurities are not introduced during the preparation process, which shortens the preparation process. The shortened process reduces the preparation cost and meets the national green and low-carbon requirements;

[0114] (3) The aluminum nitride powder provided in the embodiment of the present application has high purity, low oxygen content, high quality, small particle size and large specific surface area (greater than 2.0 m 2 / g), which can be used as raw materials for high-quality ceramic substrates, electronic packaging materials, thermal conductivity of fine devices, etc. Compared with existing aluminum nitride products, it fills the high-end application field and application scope.

[0115] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing aluminum nitride powder, characterized in that: The method comprises: In an environment isolated from oxygen, the anhydrous aluminum chloride is subjected to a first purification multiple times to obtain aluminum chloride with a set purity; The aluminum chloride with a set purity, a complexing agent and a solvent are subjected to a complexing reaction, so that the aluminum chloride with a set purity is subjected to a second purification to obtain a first mixed solution; Filtering the first mixed solution, and then drying the filter cake material obtained by filtration; In an environment isolated from oxygen, the dried filter cake material is heat treated to obtain aluminum nitride powder.

2. The method according to claim 1, characterized in that: The first purification includes heating and cooling; wherein the heating temperature is 178°C to 200°C, and the cooling temperature is 129°C to 159°C.

3. The method according to claim 1 or 2, characterized in that: The set purity is ≥99.991%.

4. The method according to claim 1, characterized in that: The complexing agent includes at least one of the following: diethylenetriamine pentacarboxylate, ethylenediaminetetraacetic acid, o-phenanthroline, monoethanolamine, triethanolamine, dimercaptopropanol, and thiourea.

5. The method according to claim 1, characterized in that: The solvent includes a first solvent and a second solvent; wherein the first solvent includes water; The second solvent includes at least one of the following: methanol, ethanol, isopropanol, ethyl ether, ethylene oxide, ethylene glycol monomethyl ether, chlorobenzene, acetone, and toluene.

6. The method according to claim 5, characterized in that In terms of weight fraction, the weight of the aluminum chloride with a set purity is 39% to 61%, the weight of the complexing agent is 8% to 15%, the weight of the first solvent is 24% to 36%, and the weight of the second solvent is 7% to 10%.

7. The method according to claim 1, characterized in that The method of heat treating the dried filter cake material to obtain aluminum nitride powder comprises: The dried filter cake material is subjected to a first heat treatment to obtain ammonia gas and aluminum salt; The ammonia gas and the aluminum salt are subjected to a second heat treatment so that the aluminum salt is sublimated into a gas to react with the ammonia gas to obtain aluminum nitride powder.

8. The method according to claim 7, characterized in that The temperature of the first heat treatment is 650°C to 850°C; and / or the temperature of the second heat treatment is 950°C to 1200°C.

9. Aluminum nitride powder prepared by the method according to any one of claims 1 to 8.

10. The aluminum nitride powder according to claim 9, characterized in that: The aluminum nitride powder meets the following indicators: oxygen content <0.8%, particle size of 0.9 μm to 1.4 μm, specific area greater than 2.0 m 2 / g.

Images