A method for preparing and using an in situ transformed AlN ceramic article coated with AlN

Abstract

The application relates to a preparation method and application of an AlN ceramic product with an in-situ converted AlN coating, and relates to the fields of aluminum substrate surface treatment and metal matrix composite preparation. The application aims to solve the problems of high sintering temperature and high cost in the existing AlN ceramic substrate preparation method. The method comprises the following steps: I, pretreatment; II, preparation of an alumina porous framework; III, placing the aluminum substrate with the alumina porous framework on an atmosphere furnace with N2, heating the atmosphere furnace to a reaction temperature, and reacting N2 with the internal aluminum through the holes in the alumina porous framework to generate AlN in-situ at the reaction temperature, so as to obtain an AlN ceramic product with an in-situ converted AlN coating. The application obtains an AlN ceramic product with high thermal conductivity and high electrical insulation on the aluminum surface under the condition of low cost and low reaction temperature, and has very important significance for realizing the development of super-speed and large-chip integrated circuit packaging substrate materials in China.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aluminum substrate surface treatment and metal matrix composite preparation, and particularly relates to a preparation method and application of an AlN ceramic product with an in-situ converted AlN coating. BACKGROUND

[0002] In recent years, packaging materials and technologies have become a research hotspot in the microelectronic industry. Although Al2O3 ceramic plates are still the most widely used electronic packaging ceramic materials at present, with the rapid development of the computer industry, the integration and chip area are becoming larger and larger, the speed is increasing, and the power is increasing, and the low thermal conductivity, high dielectric constant and large mismatch of the thermal expansion coefficient with the chip have become increasingly prominent, which cannot meet the needs of future high-power electronic development. AlN ceramic plates have attracted widespread attention due to their much higher thermal conductivity than Al2O3 ceramic plates, similar thermal expansion coefficient to Si, and have been regarded as the most promising substrate material for high-density high-power electronic packaging.

[0003] At present, the preparation of AlN ceramic substrates usually requires high-temperature sintering, and the sintering temperature reaches 1800℃ or even higher, resulting in high processing cost. Direct preparation of AlN ceramic on the surface of aluminum alloy seems to be an effective way to solve the high sintering temperature. Patent CN102912286B places a preheated aluminum workpiece into a molten bath salt for nitriding, at a temperature of 580-610℃ for 1-5h; patent CN102943230B relates to a surface nitriding method for aluminum alloy, mainly including nitriding treatment after removing the surface oxide film (580-640℃, 10-50h) to obtain a nitriding layer. The above patents perform nitriding treatment on the surface of aluminum workpieces, and according to the research, so far no patent and literature has reported the direct in-situ preparation of AlN ceramic on aluminum products. Therefore, the present application innovatively proposes a method for in-situ preparation of AlN ceramic substrate on aluminum substrate, which is expected to become an ideal substrate material for ultra-high-speed and large-chip integrated circuit packaging. SUMMARY

[0004] The purpose of the present application is to solve the problem of high sintering temperature and high cost in the existing method for preparing AlN ceramic substrate, and to provide a preparation method and application of an AlN ceramic product with an in-situ converted AlN coating.

[0005] A preparation method of an AlN ceramic product with an in-situ converted AlN coating, which is completed according to the following steps:

[0006] I. Pretreatment:

[0007] Remove impurities and oil stains on the surface of the aluminum substrate to obtain a pretreated aluminum substrate;

[0008] II. Preparation of alumina porous framework:

[0009] The porous alumina layer is prepared on the surface of the pretreated aluminum substrate by using micro-arc plasma discharge oxidation technology, and the aluminum substrate with alumina porous skeleton on the surface is obtained.

[0010] III. Preparation of aluminum matrix composite material:

[0011] The aluminum substrate with alumina porous skeleton on the surface is placed in a furnace with N2 atmosphere, the furnace is heated to a reaction temperature, at the reaction temperature, N2 reacts with the internal aluminum in situ through the pores in the alumina porous skeleton to form AlN, wherein the alumina porous outer layer serves as a skeleton to support the internal aluminum substrate, and the AlN ceramic product with in-situ conversion AlN coating is obtained after heat preservation for a period of time.

[0012] Principle of the present application:

[0013] The purpose of selecting aluminum foil, aluminum wire and thin aluminum plate in the present application is to reduce the risk of deformation and collapse due to melting structure of aluminum products that are too thick during the synthesis of AlN ceramic by reacting with N2, so that it is difficult to form an AlN ceramic layer with complete structure. The purpose of using micro-arc plasma oxidation technology to prepare alumina porous skeleton on the surface of the pretreated substrate is: ① maintain high porosity (including through holes) to ensure that N2 is in full contact with the internal aluminum product during sintering, so that it can fully react to form AlN; ② obtain an alumina porous skeleton to support the aluminum product and maintain its mechanical bearing capacity during the reaction to form AlN at 700-900℃ in a furnace with N2 atmosphere, preventing it from deforming and collapsing due to high temperature melting. Finally, the aluminum product with alumina porous skeleton is heated in a furnace with N2 to prepare an AlN ceramic product with complete structure, which has high thermal conductivity and high electrical insulation performance.

[0014] Advantages of the present application:

[0015] The present application is low-cost and can obtain an AlN ceramic product with high thermal conductivity and high electrical insulation on the surface of aluminum at a lower reaction temperature, which is of great significance for the development of super-speed and large-chip integrated circuit packaging substrate materials in China. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 XRD pattern of the AlN ceramic product prepared on the surface of the aluminum foil in Example 1 of the present application;

[0017] Figure 2 SEM image of the AlN ceramic product prepared on the surface of the aluminum foil in Example 1 of the present application;

[0018] Figure 3 Structure schematic diagram of the AlN ceramic product prepared on the surface of the aluminum foil in Example 1 of the present application;

[0019] Figure 4 Macrograph of AlN ceramic product prepared on the surface of aluminum foil, aluminum wire and aluminum plate in Example 1 of the present application, respectively;

[0020] Figure 5 Electrical insulation performance graph of AlN ceramic product prepared on the surface of aluminum foil and aluminum plate in Example 1 of the present application, respectively;

[0021] Figure 6 Thermal conductivity performance graph of AlN ceramic product prepared in different embodiments of the present application. DETAILED DESCRIPTION

[0022] Embodiment 1: A method for preparing an AlN ceramic product with an in-situ converted AlN coating, which is completed according to the following steps:

[0023] I. Pretreatment:

[0024] Impurities and oil stains on the surface of the aluminum substrate are removed to obtain a pretreated aluminum substrate;

[0025] II. Preparation of alumina porous framework:

[0026] A porous alumina layer is prepared on the surface of the pretreated aluminum substrate by using micro-arc plasma discharge oxidation technology to obtain an aluminum substrate with an alumina porous framework on the surface;

[0027] III. Preparation of aluminum-based composite material:

[0028] The aluminum substrate with an alumina porous framework on the surface is placed in a gas furnace with N2, the gas furnace is heated to a reaction temperature, at the reaction temperature, N2 reacts with the internal aluminum through the pores in the alumina porous framework to generate AlN in-situ, wherein the alumina porous outer layer serves as a framework to support the internal aluminum substrate, and the temperature is maintained for a period of time to obtain an AlN ceramic product with an in-situ converted AlN coating.

[0029] Embodiment 2: The difference between this embodiment and Embodiment 1 is that the aluminum substrate in Step I is an aluminum foil, an aluminum wire or an aluminum plate. The other steps are the same as Embodiment 1.

[0030] Specific embodiment three: the difference between this embodiment and one or two of the specific embodiments is that the specific method for preparing the porous structure of the aluminum oxide layer on the surface of the pretreated aluminum substrate in step two is as follows: first, immerse the pretreated aluminum substrate into a stainless steel electrolytic tank containing electrolyte, then connect the pretreated aluminum substrate with the positive pole of the power supply, and connect the stainless steel electrolytic tank with the negative pole of the power supply, and oxidize under the conditions of electrolyte temperature 10℃-50℃, applied voltage 250V-400V, frequency 200Hz-1000Hz, and duty cycle 4%-30% for a period of time to construct the aluminum oxide porous framework with through-hole structure. The other steps are the same as those in specific embodiment one or two.

[0031] Specific embodiment four: the difference between this embodiment and one to three of the specific embodiments is that the oxidation time is 2min-10min. The other steps are the same as those in specific embodiments one to three.

[0032] Specific embodiment five: the difference between this embodiment and one to four of the specific embodiments is that the electrolyte is composed of sodium silicate, sodium phosphate, sodium hydroxide and water; the concentration of sodium silicate in the electrolyte is 1g / L-20g / L, the concentration of sodium phosphate is 1g / L-40g / L, and the concentration of sodium hydroxide is 1g / L-20g / L. The other steps are the same as those in specific embodiments one to four.

[0033] Specific embodiment six: the difference between this embodiment and one to five of the specific embodiments is that the thickness of the aluminum oxide porous framework in step two is 3μm-15μm, and the porosity is 20%-70%. The other steps are the same as those in specific embodiments one to five.

[0034] Specific embodiment seven: the difference between this embodiment and one to six of the specific embodiments is that the gas pressure of the N2 atmosphere furnace in step three is 0.1MPa, and the purity of N2 is 99.99%; the N2 atmosphere furnace in step three needs to be purged with nitrogen for 1h-2h before heating. The other steps are the same as those in specific embodiments one to six.

[0035] Specific embodiment eight: the difference between this embodiment and one to seven of the specific embodiments is that the reaction temperature in step three is 700℃-900℃. The other steps are the same as those in specific embodiments one to seven.

[0036] Specific embodiment nine: the difference between this embodiment and one to eight of the specific embodiments is that the heating rate in step three is 5℃ / min-10℃ / min; and the holding time in step three is 10min-40min. The other steps are the same as those in specific embodiments one to eight.

[0037] Embodiment 10: The embodiment is an application of the aluminum matrix composite in-situ transformed with an AlN coating in the field of high-thermal-conductivity and high-insulation electronic packaging.

[0038] The beneficial effects of the present application are verified by the following examples:

[0039] Example 1: A preparation method of an aluminum matrix composite in-situ transformed with an AlN coating, which is specifically completed by the following steps:

[0040] I. Pretreatment:

[0041] The surface of the aluminum matrix is polished by using 800#, 1000# and 1200# sandpaper in sequence, and then ultrasonic cleaning is performed for 30 min by using anhydrous ethanol and deionized water in sequence, so as to remove impurities and an oxide layer on the surface of the aluminum matrix, and obtain the pretreated aluminum matrix;

[0042] The aluminum matrix in step one is an aluminum foil, an aluminum wire or an aluminum plate;

[0043] II. Preparation of an alumina porous framework:

[0044] An alumina layer with a porous structure is prepared on the surface of the pretreated aluminum matrix by using a micro-arc plasma discharge oxidation technology, and the aluminum matrix with the alumina porous framework on the surface is obtained;

[0045] The specific method for preparing the alumina layer with the porous structure on the surface of the pretreated aluminum matrix by using the micro-arc plasma discharge oxidation technology in step two is as follows: first, the pretreated aluminum matrix is immersed into a stainless steel electrolytic cell containing an electrolyte, then the pretreated aluminum matrix is connected with the positive pole of a power supply, and the stainless steel electrolytic cell is connected with the negative pole of the power supply, and the alumina porous framework with a through-hole structure is constructed by oxidizing for 4 min under the conditions that the temperature of the electrolyte is 25℃, the pulse voltage applied to both ends of the electrolytic cell is 250V, the frequency is 400Hz, and the duty cycle is 4%.

[0046] The electrolyte is composed of sodium silicate, sodium phosphate, sodium hydroxide and water; the concentration of sodium silicate in the electrolyte is 15g / L, the concentration of sodium phosphate is 20g / L, and the concentration of sodium hydroxide is 5g / L;

[0047] The thickness of the alumina porous framework in step two is 8μm, and the porosity is 50%;

[0048] III. Preparation of an aluminum matrix composite:

[0049] The aluminum substrate with alumina porous framework on the surface is placed in an atmosphere furnace with N2, the atmosphere furnace is heated to 750℃ at a heating rate of 5℃ / min, at 750℃, N2 reacts with the internal aluminum in situ through the holes in the alumina porous framework to generate AlN, wherein the alumina porous outer layer supports the internal aluminum substrate, and the temperature is kept for 20 min, to obtain an aluminum-based composite material with an in-situ converted AlN coating (AlN ceramic product);

[0050] The gas pressure of the atmosphere furnace with N2 in step three is 0.1 MPa, and the purity of N2 is 99.99%.

[0051] The atmosphere furnace with N2 in step three needs to be passed through nitrogen for 1h before heating.

[0052] Figure 1 The XRD pattern of the AlN ceramic product prepared on the surface of the aluminum foil is analyzed, as shown in Figure 1 ;

[0053] Figure 1 The XRD pattern of the AlN ceramic product prepared on the surface of the aluminum foil in Example 1 of the present application;

[0054] Figure 1 The results show that in addition to the diffraction peaks of Al and Al2O3, there are a large number of diffraction peaks of AlN in the product, which proves that the technology can form an AlN ceramic layer on the surface of aluminum and its alloy products.

[0055] Figure 2 The SEM image of the AlN ceramic product prepared on the surface of the aluminum foil in Example 1 of the present application;

[0056] As shown in Figure 2 , the surface scanning morphology shows that the surface of the AlN ceramic product presents a ceramic structure morphology formed by the reaction of aluminum and nitrogen, which further proves that N2 can enter through the through holes in the alumina porous framework and react with the internal aluminum to form AlN, and the AlN sintered dense ceramic layer can be clearly observed, which shows that the AlN substrate can be successfully prepared at low temperature.

[0057] Figure 3 The structural schematic diagram of the AlN ceramic product prepared on the surface of the aluminum foil in Example 1 of the present application;

[0058] As shown in Figure 3 , the aluminum substrate with alumina porous framework is placed in an atmosphere furnace with N2 to prepare an AlN ceramic product, wherein the Al in the aluminum substrate flows to the alumina porous framework at high temperature and reacts with N2 to form an AlN and Al2O3 composite structure, and the aluminum substrate itself also contacts with N2 to form an AlN layer, and finally an AlN ceramic product with an AlN coating is prepared Figure 3 .

[0059] Figure 4 Macrograph of AlN ceramic product prepared on the surface of aluminum foil, aluminum wire and aluminum plate in Example 1 of the present application, respectively;

[0060] From Figure 4 It can be seen that the surface of the product presents grayish white; and the coating prepared on the aluminum substrate under the above electrolyte system by using micro-arc plasma oxidation technology presents white color, which is due to the main phase of the micro-arc plasma oxidation coating being Al2O3 phase, so that the macro-morphology further proves that the AlN ceramic product is successfully prepared on the surface of aluminum and its alloy by using the technology; at the same time, it can be obviously observed that whether the aluminum foil, aluminum wire or aluminum plate presents good structural integrity, and no structural deformation and collapse occurs, proving that the AlN ceramic product with structural integrity is prepared.

[0061] Figure 5 Electrical insulation performance diagram of AlN ceramic product prepared on the surface of aluminum foil and aluminum plate in Example 1 of the present application;

[0062] From Figure 5 It can be seen that the aluminum alloy product with AlN ceramic layer has excellent electrical insulation performance, and the voltage resistance can reach more than 1000V, and the resistance value is greater than 100MΩ.

[0063] The thermal conductivity performance diagram of the AlN ceramic product prepared in Example 1 is shown in Figure 6

[0064] The AlN ceramic product prepared in Example 1 has high thermal conductivity of ~ 190W / mK, and can be used as a high-thermal-conductivity, high-insulation and high-heat-dissipation substrate.

[0065] Example 2: A preparation method of an in-situ transformed AlN coating aluminum-based composite material, which is completed according to the following steps:

[0066] I. Pretreatment:

[0067] The surface of the aluminum substrate is polished by using 800#, 1000# and 1200# sandpaper in sequence, and then ultrasonic cleaning is performed by using anhydrous ethanol and deionized water in sequence for 30min, so as to remove impurities and oxide layers on the surface, and an aluminum substrate after pretreatment is obtained;

[0068] The aluminum substrate in step one is aluminum foil, aluminum wire or aluminum plate;

[0069] II. Preparation of alumina porous framework:

[0070] An alumina layer with a porous structure is prepared on the surface of the aluminum substrate after pretreatment by using micro-arc plasma discharge oxidation technology, and an aluminum substrate with an alumina porous framework on the surface is obtained;

[0071] ​The specific method for preparing the porous alumina layer on the surface of the pretreated aluminum substrate in step two is as follows: first, the pretreated aluminum substrate is immersed in a stainless steel electrolytic tank containing electrolyte, then the pretreated aluminum substrate is connected to the positive pole of a power supply, and the stainless steel electrolytic tank is connected to the negative pole of the power supply, and under the conditions of electrolyte temperature 35℃, pulse voltage 300V applied to both ends of the electrolytic tank, frequency 600Hz and duty cycle 6%, the aluminum substrate is oxidized for 7min to construct an alumina porous framework with through-hole structure;

[0072] The electrolyte is composed of sodium silicate, sodium phosphate, sodium hydroxide and water; the concentration of sodium silicate in the electrolyte is 20g / L, the concentration of sodium phosphate is 10g / L, and the concentration of sodium hydroxide is 4g / L;

[0073] The thickness of the alumina porous framework in step two is 11μm, and the porosity is 42%;

[0074] III. Preparation of aluminum matrix composite material:

[0075] The aluminum substrate with alumina porous framework on the surface is placed in a N2 atmosphere furnace, and the furnace is heated at a rate of 5℃ / min to 800℃, and at 800℃, N2 reacts with the internal aluminum in situ through the through-holes in the alumina porous framework to form AlN, wherein the alumina porous outer layer serves as a framework to support the internal aluminum substrate, and the temperature is kept for 15min to obtain an aluminum matrix composite material with in-situ converted AlN coating (AlN ceramic product);

[0076] The gas pressure of the N2 atmosphere furnace in step three is 0.1MPa, and the purity of N2 is 99.99%;

[0077] The N2 atmosphere furnace in step three needs to be purged with nitrogen for 1h before heating.

[0078] The electrical insulation performance of the AlN coating prepared on the surface of the aluminum foil and aluminum plate in Example 2 is shown in Table 1; wherein the surface AlN coating on the aluminum foil has an insulation resistance of 152MΩ and a breakdown voltage of more than 1300V; the surface AlN coating on the aluminum plate has an insulation resistance of 159MΩ and a breakdown voltage of more than 1371V.

[0079] The thermal conductivity performance chart of the AlN ceramic product prepared in Example 2 is shown in Figure 6

[0080] The AlN ceramic product prepared in Example 2 has high thermal conductivity of ~193W / mK and can be used as a high-thermal-conductivity, high-insulation, high-heat-dissipation substrate.

[0081] Example 3: A method for preparing an aluminum matrix composite material with in-situ converted AlN coating, which is completed according to the following steps:​

[0082] I. Pretreatment:

[0083] The surface of the aluminum substrate was polished using 800#, 1000# and 1200# sandpaper in sequence, and then ultrasonic cleaning was performed using anhydrous ethanol and deionized water for 30 min, respectively, to remove impurities and oxide layers on the surface, thereby obtaining a pretreated aluminum substrate;

[0084] The aluminum substrate in step one is an aluminum foil, an aluminum wire or an aluminum plate;

[0085] II. Preparation of an aluminum oxide porous framework:

[0086] A porous aluminum oxide layer was prepared on the surface of the pretreated aluminum substrate using a micro-arc plasma discharge oxidation technique, thereby obtaining an aluminum substrate with an aluminum oxide porous framework on the surface;

[0087] The specific method for preparing a porous aluminum oxide layer on the surface of the pretreated aluminum substrate in step two using a micro-arc plasma discharge oxidation technique is as follows: first, the pretreated aluminum substrate is immersed in a stainless steel electrolytic cell containing an electrolyte, then the pretreated aluminum substrate is connected to the positive electrode of a power supply, and the stainless steel electrolytic cell is connected to the negative electrode of the power supply, and the aluminum oxide porous framework with through-hole structure is constructed by oxidizing the pretreated aluminum substrate under the following conditions: electrolyte temperature 45℃, external pulse voltage 300V between the two ends of the electrolytic cell, frequency 300Hz and duty cycle 20%; and the oxidation time is 8min;

[0088] The electrolyte is composed of sodium silicate, sodium phosphate, sodium hydroxide and water; the concentration of sodium silicate in the electrolyte is 10g / L, the concentration of sodium phosphate is 30g / L, and the concentration of sodium hydroxide is 5g / L;

[0089] The thickness of the aluminum oxide porous framework in step two is 12μm, and the porosity is 51%;

[0090] III. Preparation of an aluminum matrix composite material:

[0091] The aluminum substrate with an aluminum oxide porous framework on the surface is placed in a N2 atmosphere furnace, and the furnace is heated to 900℃ at a heating rate of 5℃ / min. At 900℃, N2 reacts with the internal aluminum through the through-holes in the aluminum oxide porous framework to generate AlN in situ, and the outer layer of the aluminum oxide porous framework serves as a support for the internal aluminum substrate. The temperature is maintained for 30min to obtain an aluminum matrix composite material (AlN ceramic product) with an in-situ converted AlN coating;

[0092] The gas pressure of the N2 atmosphere furnace in step three is 0.1MPa, and the purity of N2 is 99.99%;

[0093] Before heating, the N2 atmosphere furnace in step three needs to be purged with nitrogen for 1h.

[0094] The electrical insulation properties of the AlN coating prepared on the surface of aluminum foil and aluminum plate in Example 3 are shown in Table 1; wherein the surface AlN coating of aluminum foil has an insulation resistance of 161 MΩ and a breakdown voltage of 1376 V or more; the surface AlN coating of aluminum plate has an insulation resistance of 178 MΩ and a breakdown voltage of 1405 V or more.

[0095] Table 1 Electrical insulation properties of Example 2 and Example 3

[0096]

[0097]

[0098] The thermal conductivity performance chart of the AlN ceramic product prepared in Example 3 is shown in Figure 6

[0099] The AlN ceramic product prepared in Example 3 has a high thermal conductivity of ~195 W / mK and can be used as a high-thermal-conductivity, high-insulation, high-heat-dissipation substrate.​

Claims

1. A method for preparing AlN ceramic products with in-situ conversion AlN coating, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preprocessing: Remove impurities and oil stains from the surface of the aluminum substrate to obtain the pretreated aluminum substrate; II. Preparation of porous alumina framework: A porous alumina layer was prepared on the surface of a pretreated aluminum substrate using micro-arc plasma discharge oxidation technology, resulting in an aluminum substrate with a porous alumina framework on the surface. The thickness of the porous alumina framework mentioned in step two is 3μm~15μm, and the porosity is 20%~70%. III. Preparation of aluminum-based composite materials: An aluminum substrate with an alumina porous skeleton is placed in a furnace with an atmosphere of N2. The furnace is heated to the reaction temperature. At the reaction temperature, N2 reacts with the internal aluminum through the pores in the alumina porous skeleton to generate AlN in situ. The alumina porous outer layer acts as a skeleton to support the internal aluminum substrate. After holding the temperature for a period of time, an AlN ceramic product with an in situ AlN coating is obtained. The reaction temperature described in step three is 700℃~900℃.

2. The method for preparing an AlN ceramic product with an in-situ conversion AlN coating according to claim 1, characterized in that... The aluminum substrate mentioned in step one is aluminum foil, aluminum wire, or aluminum plate.

3. The method for preparing an AlN ceramic product with an in-situ conversion AlN coating according to claim 1, characterized in that... The specific method for preparing a porous alumina layer on the surface of the pretreated aluminum substrate using micro-arc plasma discharge oxidation technology in step two is as follows: First, the pretreated aluminum substrate is immersed in a stainless steel electrolytic cell containing electrolyte. Then, the pretreated aluminum substrate is connected to the positive terminal of the power supply, and the stainless steel electrolytic cell is connected to the negative terminal of the power supply. Oxidation is carried out for a period of time under the conditions of electrolyte temperature of 10℃~50℃, applied voltage of 250V~400V, frequency of 200Hz~1000Hz, and duty cycle of 4%~30%, thereby constructing a porous alumina framework with through-hole structure.

4. The method for preparing an AlN ceramic product with an in-situ conversion AlN coating according to claim 3, characterized in that... The oxidation time is 2 min to 10 min.

5. The method for preparing an AlN ceramic product with an in-situ conversion AlN coating according to claim 3, characterized in that... The electrolyte is composed of sodium silicate, sodium phosphate, sodium hydroxide and water; the concentration of sodium silicate in the electrolyte is 1g / L~20g / L, the concentration of sodium phosphate is 1g / L~40g / L, and the concentration of sodium hydroxide is 1g / L~20g / L.

6. The method for preparing an AlN ceramic product with an in-situ conversion AlN coating according to claim 1, characterized in that... The gas pressure of the N2 atmosphere furnace mentioned in step three is 0.1 MPa, and the purity of N2 is 99.99%. The N2 atmosphere furnace mentioned in step three needs to be purged with nitrogen for 1 to 2 hours before heating.

7. The method for preparing an AlN ceramic product with an in-situ conversion AlN coating according to claim 1, characterized in that... The heating rate mentioned in step three is 5℃ / min to 10℃ / min; the holding time mentioned in step three is 10min to 40min.

8. The application of an AlN ceramic product with an in-situ transformed AlN coating prepared by the preparation method described in claim 1, characterized in that... An aluminum-based composite material with an in-situ conversion AlN coating is used in the field of high thermal conductivity and high insulation electronic packaging.

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