The Low Temperature Sulpho-Molybdenumizing Technology and the Properties of Resulted Coating

The low temperature sulpho-molybdenumizing technology (LTSM) includes two basic processes,electrolytic sulphurizing and molybdenum disulphide chemical plating. In the first process, a black and porous sulphurizing layer with FeS as main substituent is formed on the surfaces of workpieces through a series of chemical reactions. In the latter, electrolytic sulphurized workpieces are soaked in ammonium molybdenate water solution containing just the right amount of additive, and MoS2 is formed by means of multistep chemical reactions. The X-ray photoelec-tronic spectrometer (XPS) results shown that the phase composition of FeS, MoSz is 61.54% and 25.70% respectively in the sulpho-molybdenumi-zing layer which has good self-lubrication property. Under dry-friction and oil drop lubrication(2drops/min,with 20* machinry oils), the friction-wear characteristics of electrolytic sulfurized case were tested as compared with sulpho-molybdenumized case. It was found that the friction reducing and adhesive wear resistance behaviours of the latter are better than that of the former, especially the tribological properties of sulpho-molybdenumized composite coating are much better.The practical properties of various high-speed steel (HSS) tool treated with sulpho-molyb-denumizing technology have been studied as compared with those of electrolytic sulfurized tools, it was found that the durability of sulpho-molybdenumized tools is obviously better than that of electrolytic sulfurized tools, and in the case of using the latter is hard to be successful (e.g.for the materials with low hardness and severe adhesion) the former also has good machineability.Therefore, the sulpho-molybdenumized coating is of broad application prospects, it can be used not only in different friction workpieces of machinery products but also in various HSS tools.