等离子镍铬表面合金化合金元素利用率研究

STUDY ON ABSORPTION RATIO OF ALLOY ELEMENTS IN PLASMA Ni Cr ALLOYING BY DOUBLE GLOW PLASMA PROCESS

采用双层辉光离子渗金属技术在２０ 钢上进行镍铬共渗处理，对合金元素的溅射和吸收这两个渗金属过程，从放电及溅射等理论角度并结合试验结果进行了分析讨论。结果表明，放电条件对渗层形成效率有很大影响，合金元素的利用率在不同的放电参数下会有悬殊的变化。溅射量决定于溅射电压与气压，利用率则受工件偏压、气压、极间距的共同控制。在一定的溅射量下，利用率的高低决定了渗层质量及形成效率。提高合金元素的利用率是工艺参数选择的最重要目标。

Plasma Ni Cr surface alloying was applied on mild steel by Double Glow Plasma Surface Alloying Process. The sputtering and absorption of alloy elements, two basic processes that determined the kinetics of the alloying process, were investigated on the basis of discharge and sputtering theories and the experiment results. The study indicated that the alloying process was effected remarkably by the discharge parameters. The sputtering efficiency of the sputtering target was determined by the voltage applied on it and also the discharge pressure. High voltage and low discharge pressure were favorable. The absorption ratio was irrelevant with the sputtering process, while the discharge pressure and substrate bias should be chosen moderately to obtain the highest efficiency of the alloying process, the optimums being 40Pa and 400V respectively. Besides, the distance between sputtering target and substrate also affected the absorption ratio. Reducing distance was beneficial to the absorption process especially when it was at 20mm or shorter. The close correlation between the distance and the absorption ratio might result in the non-uniformity of the alloyed layer since it was inevitable that there would be some difference in the distance in practical operations, so the selection of distance should be considered in association with the specific processing condition. With certain sputtering supply of alloy elements, the larger the ratio of the absorption, the higher the quality of the alloyed layer. The absorption ratio should be the main concern with respect to the optimization of the processing conditions.