偏压对活性屏离子渗氮工艺的影响

Influence of Bias Voltage on Active Screen Plasma Nitriding Technology

通过对40C钢进行活性屏离子渗氮处理,研究了在活性屏离子渗氮工艺过程中工件所加的偏压对渗氮层的影响。试验结果表明,在不加偏压或偏压较低的情况下,对距离活性屏较近的工件,其表面有一定厚度的渗氮层形成,硬度提高;而距离活性屏较远的工件,其表面几乎没有渗氮层的形成,但当增大偏压至400~450 V时,工件表面产生弱的辉光放电,距离活性屏较远的工件表面也有渗氮层形成。通过控制偏压值,可以使工件表面形成厚度均匀的渗氮层,提高工件硬度;同时也可以避免直流离子渗氮过程中产生的打弧、边缘效应等问题。

A novel technique was developed to improve the surface modification of 40Cr steel by active screen plasma nitriding technology.The original work involves the application of the bias voltage.The impacts the bias voltage on the growth of the nitride layers,improvement of its surface mechanical properties were evaluated.The results show that the bias significantly affects growth and properties of the nitride layers.For instance,at zero or a low bias,non-uniform nitride layer forms in the areas close to the active screen,with its thickness decreasing with an increase of the distance;at 400～500 V,the nitride layers covered all the surfaces of the substrate,where weak glow discharge was observed.We suggest that the compact,uniform nitride layers may be grown,and the glow discharge and edge effect of the direct current screen nitriding,be eliminated by optimizing the bias voltage.