Tribological properties, stoichiometry and surface roughness of Si—DLC IBAD coatings

Abstract

Hard, low-friction silicon-containing diamond-like carbon coatings (Si—DLC), were formed by Ar + ion beam assisted deposition (BAD) on 5″ diameter silicon wafers. The Si—DLC precursor, tetraphenyl-tetramethyl-trisiloxane [(C 6H 5) 4(CH 3) 4Si 3O 2] was evaporated through seven, 3 mm diameter, closely packed apertures (multi-aperture container) arranged in a hexagonal pattern to initially study deposition of larger areas. Depending on deposition conditions, the maximum Knoop microhardness and the minimum sliding friction coefficient of these coatings were 20 000 MPa and 0.04, respectively. These values are consistent with our previously reported single nozzle results [1]. The standard deviation of the Knoop microhardness varied from 14 to 30% over the area of the 0.127 m (5″) substrate which was a significant improvement over our single nozzle oil container. The friction coefficient and stoichiometry of each coating was constant voer the substrate area. The initial use of multi-apertures for coating larger area substrates resulting in the minimization of the coating tribological property, and roughness variation will be discussed.