LOW FRICTION COATINGS OF DIAMOND-LIKE CARBON WITH SILICON PREPARED BY PLASMA-ASSISTED CHEMICAL VAPOR-DEPOSITION

Amorphous carbon-silicon (a-C-Si) coatings with smooth surface and adhesion to steel substrate were deposited at 550 °C by a dc glow discharge method from reactant gases of CH4, SiC l4, H2, and Ar at a deposition rate of 1–3 μm h_1. Diamond-like carbon was detected by laser Raman spectroscopy in the coatings with high hardness of Hv 2000 and more than 70 at.% carbon. Ball-on-disk type and Ohgoshi-type apparatuses were used to measure the tribological properties. Ball-on-disk tests revealed that the a-C-Si coatings showed a friction coefficient as low as 0.04 against steel with no lubricant in an ambient atmosphere of 70% relative humidity, which was one-third that of an i-C coating. The wear rate of the steel ball against the coated disk was an order and three orders of magnitude smaller than that against i-C coated and uncoated disks, respectively. Both types of tests showed that the wear rate of the a-C-Si coating itself was also very small. © 1990, Materials Research Society. All rights reserved.