Differences in the Properties of Ti–C–Mo–S Antifrictional Coatings on 40Kh and 20Kh13 Steel

Abstract

The tribological and physical properties of Ti–C–Mo–S antifrictional coatings applied by a hybrid magnetron–plasma method on 40Kh and 20Kh13 steel substrates are compared. The coatings on the 40Kh and 20Kh13 steel substrates are applied in precisely the same conditions by magnetron sputtering of cathodes produced by self-propagating high temperature synthesis (SHS), with the assistance of high-density gas-discharge plasma formed by a PINK plasma source. The methods used in coating application are detailed. The coated substrates undergo frictional tests in a pin-on-disk configuration. The relative velocity of the counterbodies is 50–60 cm/s. The results show that the tribological characteristics of the coating—in particular, the wear resistance—depend significantly on the substrate. The coating life is significantly different on different substrates: specifically, the wear resistance is higher for the coating on low-carbon (about 1%) 40Kh steel than on high-chromium (about 13%) 20Kh13 steel. Optical and scanning electron microscopy of the wear tracks reveals qualitative and quantitative differences in the coating wear on 40Kh and 20Kh13 steel substrates. By means of an electronic profilometer, the coating wear in 1000 disk cycles may be assessed on the basis of the mean cross-sectional area of the wear track, which is four times greater for the 20Kh13 steel substrate. Analysis of the tribological and physical properties indicates that the difference in the properties is due primarily to the different initial chemical and phase composition and the structural differences of the substrates, which determine the properties of the alloyed surface layer and the adhesive strength of the coating to the substrate and ultimately determine the wear mechanism.