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1.
Hydrogenated amorphous carbon (a-C:H) film is deposited on CoCrMo alloy by plasma immersion ion implantation and deposition (PIII-D) at different flow ratios of acetylene to argon (C2H2/Ar). The results show that Ar fraction in the C2H2-Ar gas mixture has an important effect on the structure and the adhesion of the a-C:H films. When Ar fraction in the C2H2-Ar gas mixture is less than 50%, the fabricated a-C:H film composition transfer from graphite-like to diamond-like which contains higher sp3 binding thanks to Ar ion bombardment, and the adhesion strength decreased with the increment of Ar fraction. But when Ar fraction in the C2H2-Ar gas mixture is beyond 50%, the fabricated film contains more sp2 bonding for thermally driven and exhibits higher adhesion strength with the increment of the Ar fraction. 相似文献
2.
T. Van der Donck M. Muchlado S. Achanta J.-P. Celis 《Surface & coatings technology》2009,203(22):3472-3479
Hydrogenated amorphous carbon (a-C:H) coatings deposited onto steel substrates by plasma assisted CVD, using different precursor gases (1 < H/C ratio < 4) were tested for their tribological behaviour. The H content in these coatings ranged from 25 to 29 at.%. Fretting mode I tests were performed on different couples consisting of coated and/or uncoated first bodies. Some tests were performed after a heat treatment of the coatings. As-deposited a-C:H/corundum couples tested at 23 °C and 50% RH showed lowering of the coefficient of friction at increasing normal load. Graphitisation is taking place in sliding contacts at high normal loads. For a-C:H/corundum couples a clear minimum in the coefficient of friction was noticed at 100 °C for coatings containing 27 at.% H. The coefficient of friction recorded on such couples is high compared to the one recorded on as-deposited a-C:H/a-C:H couples. However for the a-C:H/a-C:H couple, a lowering of the coefficient of friction with increasing fretting test temperature was noticed. The decreasing coefficient of friction was accompanied by an increasing wear. Graphitisation is causing severe degradation of a-C:H coatings at high test temperatures. An energetic analysis of the wear is finally reported. It appeared that the wear volume recorded at RT on as-deposited a-C:H coatings varies linearly with the cumulative dissipated energy. The wear rate coefficient decreases with increasing H-content. A stabilization of the sp3 bonds with increasing H-content might explain this behaviour. Confirmation was found by performing high temperature fretting tests. Interesting is the finding that fretting tests at RT performed after a thermal treatment of a-C:H coatings at either 100 or 150 °C, show a friction and wear behaviour identical to the ones recorded on as-deposited coatings tested at RT. 相似文献