Low Temperature Fabrication fo High Quality Powders by Ultra - fine Grinding under Electrical Discharge

复合粒子是创造各种新型材料的关键材料。本研究旨在开发一种新的粉末加工技术，利用放电辅助下的超细磨削机制，在低温下快速制备出高质量的复合颗粒。讨论了这些粉末的形成机理。实验从粒子处理装置的研制开始。然后，在没有任何热辅助的情况下直接合成了复合氧化物纳米粒子，并在NH3/N2气体条件下进行了二氧化钛纳米粒子的表面改性。前一种实验选择工业用的La和Mn粉末，用高机械能装置对两种粉末进行加工。因此，LaMnO_3纳米颗粒的合成只需要机械能输入，而不需要任何热辅助。在大气中水的辅助下，通过机械化学反应讨论了反应路线。后一种实验是在机械处理下，在氨氮混合气体中发光放电，将氮掺杂到氧化钛纳米颗粒表面。结果表明，氮掺杂成功地实现了纳米颗粒的生长。在可见光下，该表面改性还获得了光催化活性。利用等离子体气氛下氮与二氧化钛的反应模型探讨了掺杂机理。这些结果表明，本研究开发的加工技术有望用于制造各种高功能粉末。

Composite particles are just key materials which create various kinds of new materials. This study aimed at developing novel powder processing technique to fabricate high quality composite particles rapidly under low temperature processing by making use of ultra-fine grinding mechanism assisted by electrical discharge. The formation mechanism of these powders was also discussed. The experiments started from the development of particle processing apparatus. Then, direct synthesis of composite oxide nanoparticles were conducted without any heat assistance, and the surface modifications of titanium dioxide nanoparticles were also conducted in NH3/N2 gas conditions with glow discharge. For the former experiment, La and Mn powders used in industries were selected, and both powders were processed by the apparatus with high mechanical energy. Consequently, nanosized particles of LaMnO_3 were synthesized only by mechanical energy input without any heat assistance. The reaction route was discussed by a mechanochemical reaction with the assistance of water in the atmosphere. For the latter experiment, nitrogen doping onto the surface of titanium oxide nanoparticles was conducted in the mixed gas of ammonium and nitrogen with glow discharge under mechanical processing. As a result, the nitrogen doping was successfully achieved without any grain growth of nanoparticles. The photocatalytic activity was also obtained by such surface modification under visible light. The doping mechanism was also discussed by a reaction model of nitrogen and titanium dioxides under plasma atmosphere. These results suggest that the processing technique developed by this study is promising for creating various kinds of high functional powders.