Synthesis and Characterization of Diamond-Like Carbon Coatings Deposited by Plasma Source Ion Implantation and Conventional Ion Beam Assisted Deposition Processes

摘要

Diamond-like carbon coatings produced by Plasma Source Ion Implantation (PSII) and beamline Ion Beam Assisted Deposition (IBAD) were synthesized and studied. Gas pressure and electrical current were used as variables to design four independent PSII test sets. Beamline IBAD samples were produced with a pre-optimized set of parameters. Profilometry measurements showed the films to have thicknesses between 1.44 +/- .09 and 1.64 +/- .04 microns and to possess very low roughness averages, ranging from 14 +/- 3 to 28 +/- 3 nm, which correlate with substrate surface roughness. Atomic Force Microscopy revealed that diamond-like carbon crystal sizes varied significantly with chamber pressure. Crystals were generally spherical in shape suggesting that films were highly amorphous. Microhardness and nanohardness test results showed the hardest films to be greater than 3 times the hardness of untreated steel. The elastic modulus of the films, measured during the nanohardness test, was directly related to film hardness. Fretting wear and Pin-on-Disk tests were performed to quantitatively assess the ability of films to resist wear. Fretting wear tests showed a dramatic decrease in friction for diamond-like carbon films with friction levels ranging from 10% to 30% of that of untreated steel. Pin-on- Disk tests revealed a significant improvement in wear resistance prior to stylus penetration into the substrate.