Abstract

Amorphous silicon-containing diamond like-carbon (Si-DLC) coatings were formed by thermal evaporation of a tetraphenyl-tetramethyl-trisiloxane ((C₆H₅)₄(CH₃)₄Si₃O₂) diffusion pump oil (Dow Corning 704) onto silicon and steel substrates with simultaneous bombardment of the growing film with 40 keV Ar⁺ ions to decompose the (C₆H₅)4(CH₃)4Si₃O₂ molecules. Both the current density of the ion beam and the oil arrival rate were varied to produce hard, adhesive films on room temperature substrates, with densities ranging from 1.4 to 2.3 g/cm³ and Knoop microhardness values (at 15 g load) from 1000 to 2100 MPa. Unlubricated friction coefficients against an AISI 52100 alloy high chromium steel ball with a 100 g load ranged from 0.03 to 0.40, depending on deposition conditions. All films were more wear-resistant than the substrate materials. The properties of the coatings deposited on AISI alloy 4130, 17-7 PH, 440-C and 4340 (bare and Ti/Cr nitride precoated) steel substrates were extensively studied. Measured microhardness values (about 2,040 MPa) were substantially higher for the coatings on the nitride precoated 4340 steel due to precoating effects. The film cohesion and adhesion failure loads for these coatings increased with increasing hardness of the underlying (nitride) layer.

© 1995 Optical Society of America