Effects of deposition parameters on hardness and lubrication properties of thin MoS2 films

The purpose of the present study is the development of a sputtered MoS2-coating suitable for the use in humid atmospheres. Influences of the process parameters argon pressure, temperature, distance between substrate and target and bias voltage on tribological properties and hardness are presented. By means of these parameter studies, different microstructures with widely varying wear behavior were achieved. Life cycle tests show that exclusively basal oriented coatings with dense, non columnar structures show the highest durability and a hardness of about 400 HV 0.01. However, dendritic needle like structures show lower endurance and lower hardness (<100 HV 0.01). Films with a comparatively high hardness (up to 800 HV 0.01) exhibit lowest sliding distances until failure due to an appearance of spalling in the ball-on-disc tests. Those coatings also show a dense but amorphous structure and sulfur deficiencies. Consolidation during sputtering, i.e. film hardness and porosity, can be controlled by certain process parameters and is probably affected by varying amounts of internal stress.