Sulphurizing of Metal Surfaces by Electrospark-Discharge Alloying. Pt. 1: Structural–Phase State of Sulphur-Containing Coatings on Constructional Steels

The methods of surface sulphur saturation of metal surfaces to provide them with special tribotechnical properties are reviewed and analysed.The main attention is focused on technologies based on the method of electrospark alloying (ESA).As shown, the process of sulphur saturation can be realised by using a special sulphur-containing saturating technical substance (STS).The methods of forming sulphided, sulphocarburized, sulphoaluminized, Al-C-S, and sulphomolybdenum coatings on steels using STS by ESA are considered.The results of sulphur distribution in the surface layer during ESA sulphurizing with a metal electrode using STS are presented.As shown, the sulphur concentration on the surface is of about 0.53-0.60%that gradually decreases deeper into the substrate.The topography of the treated surface and its structure after sulphocarburized of steel surfaces with a graphite electrode using STS containing sulphur are investigated.As found, the coating consists of several layers: a 'soft' layer saturated with sulphur, a hardened layer saturated with carbon, and the substrate metal.C i t a t i on: