活性屏等离子体源渗氮工艺特性及传质机制

Process Characteristics and Mass Transfer Mechanism of Active Screen Plasma Source Nitriding

为揭示活性屏等离子体源渗氮工艺特性(试样偏压电位和试样距屏高度)对AISI 316奥氏体不锈钢渗氮效果的影响规律,利用最小二乘法线性回归拟合了不同工艺条件下渗氮层厚度数据,绘制了活性屏等离子体源渗氮AISI316奥氏体不锈钢的工艺特性图,以此确定其最佳工艺参数。并通过对金属网屏上溅射颗粒的化学成分和相结构分析,探讨了活性屏等离子体源渗氮的传质机制。结果表明:渗氮层厚度随试样距屏高度增大而降低,当适当降低渗氮气压或试样施加一定负偏压时,均有助于提高渗氮层的厚度,并且证实了"溅射-再沉积"模型是活性屏等离子体源渗氮重要的传质机制。

The active screen plasma source nitriding of AISI 316 austenitic stainless steel was used to study the effect of process characteristic （namely the various samples bias and the distance between screen and sample） on the nitriding result. A process characteristics map was constructed to summarize the measured thickness of the nitrided layer and processing conditions through systematic experimentation. The mass transfer mechanism of active screen plasma source nitriding was discussed by analyzing concentration and microstructure of nano-partieles sputtered from material screen.The results show that the thickness of the nitriding layer is reduced with the increase of the distance between the screen and the samples. A greater thickness of the nitriding layer is obtained at a moderate nitriding pressure with a suitable samples bias. The sputtering and redeposition mechanism is proven to be an important mass transfer mechanism foractive screen plasma source nitriding.