INFLUENCE OF VARIATIONS OF THE STEEL SUBSTRATE-CR3SI(CR)/MOS2-X FILM SYSTEM ON WEAR PROPERTIES

The film systems Cr3Si/MoS1.85 and Cr/MoS1.85 as low-friction composites on steel substrates were deposited by planar high frequency magnetron sputtering. The deposition conditions such as the sputtering parameters, operating gas pressure, target-substrate distance and substrate temperature were kept constant. The film thickness of the intermediate layers Cr3Si, Cr and MoS1.85 was varied. Tribological investigations by scratch testing and pin-on-disc testing led to an optimum result for 100 nm Cr3Si and 500-1000 nm MoS1.85. For the system Cr/MoS1.85 the optimum result was obtained for about 400 nm Cr, and about double the value of MoS1.85. The friction coefficients mu in air measured by scratch testing lie between 0.03 and 0.07 and the critical loads L(c) reached values up to 25 N. In the pin-on-disc tests pins of hard metal, Al2O3 and 100Cr6 were used as counterpart. For the hard metal pairs numbers of revolution up to 60 000 and 40 000 were measured for Cr3Si/MoS1.85 and Cr/Mo-1.85 respectively. The chemical composition of the layers was determined by ESMA and the in-depth homogeneity by Auger electron spectroscopy. X-ray measurements show very broad maxima, while transmission electron microscopy reveals crystallite sizes ranging from 2 to 6 nm.