Friction and wear of self-lubricating TiN-MoS₂ coatings produced by chemical vapor deposition

The purpose of the work reported here was to develop special chemical vapor deposition (CVD) methods to produce self-lubricating ceramic coatings in which the lubricating and structural phases were co-deposited on Ti-6A1-4V alloy substrates. These novel composite coatings are based on a system containing titanium nitride and molybdenum disulfide. The method for producing these coatings and their sliding behavior against silicon nitride counterfaces, in the temperature range of 20 to 700°C in air, are described. The initial sliding friction coefficients for the composite coatings at room temperature were 0.07 to 0.30, but longer-term transitions to higher friction occurred, and specimen-to-specimen test variations suggested that further developments of the deposition process are required to assure repeatable friction and wear results. Friction and wear tests at 300 and 700°C produced encouraging results, but tests run at an intermediate temperature of 400°C exhibited friction coefficients of 1.0 or more. Oxidation and a change in the nature of the debris layers formed during sliding are believed to be responsible for this behavior.