Sliding wear results for RF sputtered MoS2 coatings

Flat washer specimens of various RF sputtered MoS2 coatings were subjected to sliding loads on a standard thrust washer tester to determine the relationship between coating parameters and wear life. Argon pressure, target-to-substrate distance, RF wattage to target, and duration of sputter etch cleaning, in addition to coating thickness, were the parameters varied. All testing was performed in a nitrogen atmosphere. The RF sputtered coatings were applied using a 25.4 cm diameter planar target in the RF diode mode without substrate biasing. Testing was conducted in two phases. The first phase was a single variable test; the second was a factorial design. The results of the Phase One testing indicate that wear life increases as the target-to-substrate distance is decreased and as chamber pressure is increased; that wear life decreases as the RF wattage to the target is increased; that the duration of sputter etch cleaning has little or no effect on wear life; and that wear life is strongly dependent, as expected, on coating thickness, the thicker films providing longer life. Phase Two testing indicated that the distance-pressure interaction is the most significant factor affecting wear life. Chamber pressure was found to be the only single variable having significant effect. (author)