球形AlN粉体的可控制备及其在热界面材料中的应用研究

Spherical aluminum nitride (AlN) granules have prosperous application prospects in the field of thermal interface materials thanks to their remarkable properties, such as high thermal conductivity and favorable fluidity. However, the fabrication and application of AlN granules still face big obstacles: the difficulty of changing AlN morphology to sphericity and the reactivity of AlN powders with water. . In this project, we intend to synthesize micro-scale spherical AlN fillers by a modified carbothermal reduction-nitridation (CRN) method. On the basis of studying the effects of reaction parameters on the morphology, structure and size distribution of AlN granules, the spherical appearance and large particle size will be achieved. Additionally, the thermodynamic and kinetic laws will be studied, and the growth mechanism of spherical AlN granule will be proposed. Next, spherical AlN granules will be treated in the Al(H2PO4)3-TEOS system to obtain SiO2 coating layer. After that, spherical AlN granules can be protected from hydrolysis even at high temperature, meeting the basic requirement of thermal fillers in the thermal interface materials. The reason for the anti-hydrolytic property under high temperature will also be explained. This project will lay a foundation for fabricating new-type thermal interface materials.

球形AlN粉体具有热导率高、流动性好等优点，在热界面材料用导热填料领域具有广阔的应用前景。但AlN无熔点、高温下易分解的特性使球形AlN粉体的制备面临困难，而AlN易水解的缺点也限制了球形AlN粉体的广泛应用。. 据此，本项目拟采用改进的碳热还原法直接合成微米级的球形AlN粉体。深入研究碳热还原反应过程中关键参数与AlN形貌和粒度的对应关系，分析反应热力学和动力学规律，阐述AlN颗粒球形化和粒径长大的机制，实现球形AlN粉体在形貌和粒径分布上的可控制备。在此基础上，利用Al(H2PO4)3催化的TEOS体系进一步对球形AlN粉体进行高温抗水解处理，构建表面包覆SiO2保护层的抗水解模型，研究球形AlN高温抗水解性的影响规律，阐述高温抗水解机制，为高性能热界面材料的制备奠定基础。

球形AlN粉体具有热导率高、流动性好等优点，在热界面材料用导热填料领域具有广阔的应用前景。但AlN无熔点、高温下易分解的特性使球形AlN粉体的制备面临困难，而AlN易水解的缺点也限制了球形AlN粉体的广泛应用。. 据此，本项目采用改进的碳热还原法成功合成微米级球形AlN粉体，深入研究了碳源、添加剂、氮气压力等关键工艺参数对氮化速率和产物形貌的影响，建立碳热还原反应特征与AlN微观结构的关系，并提出了球形AlN的生长机制。研究结果表明，高氮气压力以及反应中生成的液相铝酸盐对产物粒度调控和形貌修饰起到了重要作用，AlN在生长过程中始终被液相包裹是导致颗粒球形化的关键。进一步采用无机磷酸盐对AlN进行抗水解处理，系统研究了处理关键参数对AlN高温抗水解性的影响规律，阐述了高温抗水解机制。最后，研究AlN填料基本特性对复合热导率的影响规律，建立导热填料形态、改性过程等与复合热导率对应关系，为新型热界面材料的结构设计提供理论依据和技术支撑。