Structure and mechanical properties of tungsten-containing hydrogenated diamond like carbon coatings for space applications

Tungsten-containing diamond like carbon (W-C:H) coatings were prepared by unbalanced magnetron sputtering (UBM) using tungsten carbide targets in Ar/C2H2 atmosphere. The structure and mechanical properties of these coatings with different C2H2 flow (from 40 sccm to 140 sccm) were studied. According to the analysis of Raman spectroscopy and the measurement of hardness and Young's modulus about the coatings, it was showed that sp3/sp2 ratio in the coatings changed and the hardness and Young's modulus decreased with increase of the C2H2 flow. Besides, the adhension and friction wear properties of the coatings were evaluated using the scratch test and dry sliding tests respectively. It was found that the coatings exhibited very good adhension and the C2H2 flow (actually the hydrogen) played a very important role in the tribological behavior of the W-C:H coatings in vacuum.