Superlow Friction Behavior of Diamond-Like Carbon Coatings: Time and Speed Effects
NAVAL RESEARCH LAB WASHINGTON DC
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The friction behavior of a diamond-like carbon coating was studied in reciprocating sliding contact at speeds from 0.01 to 5 mms, in dry nitrogen. Superlow friction coefficients of 0.003 0.008 were obtained in continuous sliding at the higher speeds 1 mms. However, friction coefficients rose to values typical of diamond-like carbon in dry and ambient air 0.01-0.1 at lower speeds 0.5 mms as well as in time-delayed, higher speed tests. The rise of the friction coefficients in both speed and time-delay tests was in good quantitative agreement with gas adsorption kinetics predicted by the Elovich equation for adsorption onto carbon. More generally, superlow friction could be sustained, suppressed, and recovered as a function of exposure time, demonstrating that duty cycle cannot be ignored when predicting performance of superlow friction coatings in devices.
- Inorganic Chemistry
- Physical Chemistry
- Coatings, Colorants and Finishes
- Numerical Mathematics