Effects of plasma excitation power, sample bias, and duty cycle on the structure and surface properties of amorphous carbon thin films fabricated on AIS1440 steel by plasma immersion ion implantation

Plasma immersion ion implantation is a nonline-of-sight method for fabricat ing amorphous carbon or diamond-like-carbon coatings on steels to improve t he surface properties. In this work, carbon thin films are synthesized on 9 Cr18 (AISI440) stainless bearing steel by acetylene (C2H2) plasma immersion ion implantation (Pm). The effects of the processing parameters, including rf power, sample voltage pulse duty cycle, and target bias, on the structu re and surface properties of the carbon thin films is systematically invest igated employing Raman spectroscopy, Auger electron spectroscopy, friction coefficient measurement, and wear test. The results reveal that carbon film s several hundred nanometers thick with a well-mixed interface are formed o n the 9Cr18 steel after C2H2PIII but the structure and properties of the ca rbon films vary greatly under different PIII conditions. There is an optima l process window within which the synthesized films have superior propertie s, and current densities that are too high do not yield films with the desi red performance. (C) 2000 American Vacuum Society.