Surface and structural properties of ultrathin diamond-like carbon coatings

摘要

Nanoscale wear resistance, friction, and electrical conduction tests using atomic force microscope (AFM) have been conducted on ultrathin diamond-like carbon (DLC) coating, including tetrahedral amorphous carbon (ta-C) deposited using polsed cathodic arc (PCA) and filtered-PCA, and hydrogenated amorphous carbon (a-C:H) deposited using electron cyclotron resonance-chemical vapor deposition (ECR-CVD). The low-resistnat layers at the deposition methods and does not show an obvious variation with the coating thickness decreasing from tens of nm to a few nm. The approx3 nm to-C coatings from PCA and filteredcoating from ECR-CVD had the extremely low load-carrying capacity and exhibited the evidence of coating delamination, which can be related to the thicker (1.5 +-0.1 nm) soft surface layers of a-C:H coating. The results from conducting-AFM measurements indicate that a-C:H coatings have H and sp~3 C enrichment surface layers while the soft surface layers of ta-C coatings have lateral force microscope. The lower friction coefficients of these thin ta-C coatings can be attributed to the existence of graphite-kike surface structure.