Abstract
Thermal spray coatings of austenitic materials are mainly used under corrosive conditions. The relatively poor wear resistance strongly limits their use. A selective enrichment of the surface layer region with carbon by means of thermochemical heat treatment improves the residual stresses and increases the wear resistance. The interstitial deposition of carbon causes strong compressive residual stresses and a high surface hardness. The low process temperature of the thermochemical heat treatment avoids the precipitation of chromium carbide, whereas the corrosion resistance is not affected. Increases in the service life of existing applications or new material combinations with face-centred cubic friction partners are possible. In the absence of dimensional change, uniform as well as partial carbon enrichment of the thermal spray coating is possible. In comparative studies between carburized and untreated thermal spray coatings, the influence of the carbon enrichment on the coating properties and the microstructure was investigated. Carburized coatings demonstrate a significant improvement in adhesive wear resistance and an extremely high surface hardness. The cross section micrograph of the carburized coating shows the S-phase formation in the surface layer region. The depth profile of the carbon concentration was determined by GDOS analysis.
