Ni包覆Al_2O_3粉体的RCVD法制备及机理研究

Preparation and mechanism of Ni nanoparticles on Al_2O_3 by rotating chemical vapor deposition

金属Ni包覆于陶瓷粉体的表面,可以促进其烧结、提高导电性或赋予新的功能性质.本文采用旋转化学气相沉积法(RCVD),利用二茂镍(NiCp_2)前驱体的热分解,借助载体氢气对反应的催化促进作用,在Al_2O_3粉体表面包覆了均匀分散的Ni纳米粒子,并研究了包覆温度和原料供应速率对反应产物物相、粒度和形貌的影响规律.研究表明,在包覆温度为450~550℃、前驱体二茂镍(NiCp_2)供给速率为(0.6~2.0)×10^(-6)kg/s条件下,通过对反应过程中镍纳米粒子的包覆温度和前驱体二茂镍(NiCp_2)供给速率调控可对镍纳米粒子的粒径大小和包覆层数进行调控.结合实验结果,分析了载体氢气对二茂镍反应的催化促进作用,阐述了旋转化学气相沉积条件下Ni纳米粒子在Al_2O_3粉体表面均匀包覆的过程与机制.通过调控包覆温度和原料供应速率,可以影响前驱体二茂镍的分解行为,从而调控镍纳米粒子在Al_2O_3粉体表面的包覆状态.

The coating of Ni on the surface of the ceramic powders can promote their densification,improve electrical conductivity or provide new functional properties.In the present study,Ni nanoparticles were coated on Al_2O_3 powders by the novel rotary chemical vapor deposition（RCVD）,with nickelocene（NiCp_2） as a precursor and H_2 as the reactive gas.The effects of precursor supply rate and the precipitation temperature on the composition and morphologies of Ni nanoparticles were investigated.The results indicate that,at a precipitation temperature range of 450 ℃ to 550 ℃,and a precursor supply rate of 0.6×10^（-6）kg/s to 2.2×10^（-6）kg/s,the grain size of Ni nanoparticles increased with increasing of temperature and supply rate,forming a single uniform coating or a multilayer coating.Based on the experimental results,the catalytic effects of hydrogen gas on the decomposition of nickelodeon（NiCp_2） and the formation of Ni nanoparticles were discussed thoroughly.In addition,the uniform coating process of Ni nanoparticles on Al_2O_3 surface by RCVD and its mechanism were also clarified.Changing the precipitation temperature and precursor supply rate can have an effect on the decomposition behavior of precursor nickelocene,and then control the surface coating state accordingly.