渗硫参数对氮碳共渗表面形成FeS固体润滑层的影响

Effect of Sulphurizing Parameters on the Formation of FeS Solid Lubrication Layer on Nitrocarburized Surface

采用低温离子渗硫技术在CrMoCu合金铸铁离子氮碳共渗表面制备FeS固体润滑层。通过对FeS固体润滑层表面微观形貌的观察,初步分析了渗硫条件和氮碳共渗表面对其上FeS固体润滑层形成的影响。氮碳共渗表面细小的缺陷和凹坑为硫化物提供了形核的活性中心,利于形成以FeS相为主的较厚的FeS固体润滑层。渗硫温度对氮碳共渗表面形成FeS固体润滑层影响很大,当渗硫温度(硫罐温度/工件温度)为210℃/230℃时,FeS固体润滑层中S/Fe原子摩尔百分比值趋于1;当渗硫温度(硫罐温度/工件温度)小于或大于210℃/230℃时,FeS固体润滑层中S/Fe原子摩尔百分比值远小于1或远大于1,不利于FeS固体润滑层的形成。

FeS solid lubrication layer was prepared on the ion nitrocarburized surface of CrMoCu alloy cast iron by means of low temperature ion sulphurizing. The effect of sulphurizing parameters and nitrocarburized surface on the formation of FeS solid lubrication layer was investigated through observing the surface morphology of the FeS solid lubrication layer under SEM. The results show that the mass of small imperfection and indentation on nitrocarburized surface provides plentiful nucleation active center for the sulphide formation,which is of benefit to formation of thicker FeS solid lubrication layer with the main phase of FeS. The sulphurizing temperature affects the formation of FeS solid lubrication layer on the nitrocarburized surface greatly,and the atom tool percent ratio of S to Fe is close to 1.0 when the sulphurizing tem- perature （S pot temperature/workpiece temperature） is 210 ℃/230 ℃. The atom tool percent ratio of S to Fe of the FeS solid lubrication layer is much less or more than 1.0 when the sulphurizing temperature （S pot temperature/workpiece temperature） is lower or higher than 210 ℃/230 ℃ ,which makes against the formation of FeS solid lubrication layer.