Preparation method for low-oxygen spherical aluminum nitride powder

Abstract

The invention provides a preparation method for low-oxygen spherical aluminum nitride powder and pertains to the field of non-oxide ceramic powder material preparation technology. The low-oxygen spherical aluminum nitride powder can be obtained through the following steps: ball-grinding, evenly mixing and then drying aluminum nitride powder and appropriate amount of spherical auxiliary materials for deoxidation; placing the mixture in a graphite crucible with certain loading density, heating to 1,550 to 1,900 DEG C in N2 or Ar and preserving for 0 to 20 hours, and then cooling with the crucible; mechanically crashing the product and heating to 600 DEG C in a muffle furnace for carbon emission, then washing in a hydrochloric acid solution with 5 to 20 mass percent concentration and fully washing the product after acid cleaning in de-ionized water for 2 to 10 times; after drying, obtaining the aluminum nitride powder with 3 to 15mum median particle diameter, more than 90 percent sphericity and less than 1wt percent oxygen content. The preparation method provided by the invention can achieve spherical particle morphology and granulation at the same time required by the high thermal-conductivity aluminum nitride filling.

Description

technical field [0001] The invention discloses a method for preparing spherical aluminum nitride powder with low oxygen content, and relates to a method for assisting in trimming the morphology of aluminum nitride powder in a high-temperature liquid phase. The invention belongs to the technical field of preparation of non-oxide ceramic powder materials. Background technique [0002] Aluminum nitride is an important inorganic non-metallic ceramic material. It has high theoretical thermal conductivity, high insulation, high mechanical strength, and also has excellent anti-oxidation and thermal shock properties. Therefore, AlN is considered as a promising ceramic material. The most important application of aluminum nitride ceramic materials is concentrated in the field of high thermal conductivity electronic packaging materials, including high thermal conductivity aluminum nitride ceramic substrates and adding high thermal conductivity inorganic fillers to polymer matrix comp...

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Problems solved by technology

However, the target use of aluminum nitride obtained by these methods is to prepare aluminum nitride ceramic blocks or substrates by sintering as raw materials, so the particle size of the obtained aluminum nitride powder is ultrafine, generally around 1 μm, and the The particle size of the product reaches 0.5 μm, which will increase the contact area of ​​inorganic / organic materials when used as a thermally conductive filler in organic-inorganic composite materials, increase a large amount of contact thermal resistance, and make it difficult to form an efficient fast channel during heat transfer (thermal conduction chain), and it is difficult to achieve the desired high performance. Therefore, in organic / inorganic high thermal conductivity composite materials, it is desirable that the particle size of the thermally conductive filler be as large as possible to reduce the interface and thereby reduce the resulting thermal resistance.

At the same time, the aluminum nitride powder obtained by these synthesis methods has a relatively uniform appearance except for the relatively uniform appearance obtained by the gas phase method. Triangular, equiaxed, and even slightly sintered hard agglomerated particles with complex shapes and internal pores. These particles with complex shapes have a large internal friction during the process of compounding with organic matter, so that the composite material does not reach the desired level. When the required volume filling rate is reached, it has reached a high viscosity and is not suitable for process operation

Under the appropriate viscosity, the amount of its addition is insufficient to make the heat conduction chain density in the composite material insufficient, which affects the heat transfer efficiency, and the existence of pores also increases the thermal resistance of the composite material and reduces the performance of the material.

Especially for the relatively low-cost self-propagating high-temperature synthesis method, the obtained aluminum nitride powder has a serious positional sintering situation, and the morphology of the product is also very complicated, which seriously affects the application value of the high thermal conductivity inorganic filler in composite materials.

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