Development of Surface Treatment Method for Ultra-Fine Powder Particles for Elastic Emission Machining (EEM)

为了适应各种材料的弹性发射加工，有必要制造出具有足够表面特性的粉末。并对粒径恒定的小粉末颗粒进行了涂覆。具体而言，我们采用等离子体化学气相沉积，该工艺可以在低温下进行，从而避免粉末颗粒的粘聚。得到如下结果：(1) 1989年，建立了用于粉末表面改善的等离子体CVD装置。我们确认了所要求的性能已经建立。在此基础上，研制了粉剂进料仪，使进料效率大大提高。(2)对等离子体气相沉积腔内粉末颗粒的气流运动进行了分析，实现了粉末颗粒直径的分类。在构造的仪器中，可对粒径在0.03微米和1微米之间的颗粒进行分级。(3)我们通常使用SiO_2颗粒，但从分散性的角度考虑，我们决定使用Latex（聚苯乙烯粉末）。由于乳胶的熔点低于SiO_2，因此不能在等离子体中进行涂层处理。然后我们改进了表面处理装置，使其能够从等离子体中取出。然后，在乳胶颗粒上涂覆Al_2O_3，并对其进行EEM实验。然后我们发现加工速度与纯Al_2O_3颗粒具有相同的趋势。

To adapt EEM (Elastic Emission Machining) for various materials, it is necessary to make powder with adequate surface character. And coating any materials on small powder particles which sizes are constant was carried out. Concretely, we use Plasma Chemical Vapor Deposition which process can be done under low temperature so that cohesion of powder particles can be avoided.The following results are obtained.(1) In 1989, Plasma CVD apparatus for powder surface improvement was constructed. And we confirmed that required performance had been established. After that, we made the powder feed instrument and feed efficiency was improved sharply.(2) The powder particles movement by gas flow in the Plasma CVD chamber was analyzed and it was realized that classification of the diameters of powder particles can be done. In the constructed instrument, classification of particle which size is within 0.03 mum and 1 mum can be held.(3) We usually used SiO_2 particle, but from the view point of dispersibility we decided to use Latex (polystyrene powder). The melting point of Latex is lower than SiO_2, so we cannot take coating process in plasma. Then we improved the surface processing apparatus to be able to take out of plasma. After that, we coated Al_2O_3 on Latex particle and EEM experiment with those Latex was carried out. Then we realized that machining velocity has the same tendency with pure Al_2O_3 particle.