Development and Evaluation of Hydrogen Free Diamond-Like Carbon Coatings by HiPIMS
(Room Room 104-B)
29 Apr 19
5:00 PM
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5:20 PM
Tracks:
Protective, Tribological and Decorative Coatings
Tetrahedral amorphous (ta-C) diamond-like carbon (DLC) films are of strong interests to automotive industry as they provide low coefficient of friction (COF) in lubricants and excellent wear resistance. In this study, 4-5 mm thick hydrogen (H) free DLC coatings are deposited by sputtering a graphite target using deep oscillation magnetron sputtering (DOMS), one version of high power impulse magnetron sputtering (HiPIMS) technique. The development efforts are focused on obtaining super hard (>40 GPa) H-free DLC with high sp3 bonding fraction while maintaining excellent adhesion on tool steel and stainless steel for desired thicknesses. In particular, the effects of magnetic field strength on HiPIMS process and the structure and properties of H-free DLC coatings were investigated in detail. For sputtering carbon using HiPIMS, a strong magnetic field is critical to generate high peak current (power) which is crucial to achieve a high ionization of carbon species. The structure and mechanical properties of the coatings deposited at different magnetic field strengths are characterized by scanning electron microscopy (SEM), Raman spectroscopy, nanoindentation, and adhesion test. The tribological properties of the H-free DLC coatings are evaluated and compared to hydrogenated DLC and other low friction coatings in 10W-30 (standard) and 0W-30 (low viscosity) lubricants using ball-on-disk test and block-on ring test. These DOMS DLC coatings are extremely smooth and super hard (>40 GPa), and show excellent adhesion on tool steel with obtainable thickness up to several micrometers. The bench tests reveal great friction reduction effects of these H-free DLC in both standard and low viscosity lubricants.