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，必须使粉末具有足够的表面特性。并在尺寸恒定的小粉末颗粒上进行任何材料的涂覆。具体地说，我们采用了等离子体化学气相沉积法，该方法可以在低温下进行，从而避免了粉末颗粒的粘结。(1)1989年，用于粉末表面改性的等离子体CVD设备建成。我们确认已经建立了所需的性能。在此基础上，研制出了粉末给料装置，给料效率得到了大幅度提高. (2)分析了等离子体化学气相沉积（CVD）室中粉末颗粒在气流作用下的运动规律，实现了粉末颗粒直径的分级。在所构造的仪器中，可以保持对尺寸在0.03 μ m和1 μ m之内的颗粒的分级。(3)我们通常使用SiO_2颗粒，但从可接受性的角度考虑，我们决定使用乳胶（聚苯乙烯粉末）。乳胶的熔点比SiO_2低，不能在等离子体中进行包覆。然后，我们改进了表面处理设备，使其能够去除等离子体。在此基础上，我们在乳胶粒子表面包覆了Al_2O_3，并对包覆后的乳胶粒子进行了EEM实验。通过实验发现，加工速度与纯Al_2O_3粒子的加工速度有相同的变化趋势。

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.