Influence of variations of the steel substrate-Cr3Si(Cr)/MoS2−x film system on wear properties

Abstract The film systems Cr 3 Si/MoS 1.85 and Cr/MoS 1.85 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 Cr 3 Si, Cr and MoS 1.85 was varied. Tribological investigations by scratch testing and pin-on-disc testing led to an optimum result for 100 nm Cr 3 Si and 500–1000 nm MoS 1.85 . For the system Cr/MoS 1.85 the optimum result was obtained for about 400 nm Cr, and about double the value of MoS 1.85 . The friction coefficients μ 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, Al 2 O 3 and 100Cr6 were used as counterpart. For the hard metal pairs numbers of revolution up to 60 000 and 40 000 were measured for Cr 3 Si/MoS 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.