Films of carbide-derived carbon (CDC) were produced on surfaces of binderless tungsten carbide substrates by reacting the carbide phase with chlorine or chlorine-hydrogen mixtures at temperatures ranging from 800°C to 1000°C in a sealed tube furnace. Temperatures of 950°C and higher are required to achieve full conversion of the surfaces of tungsten carbide surfaces and to obtain films with tribological properties of interest for various applications. The typical friction coefficients of CDC films grown on tungsten carbide at 1000°C, when tested in air, are similar to the reported values for CDC films grown on silicon carbide, and are in the range of 0.18-0.25. Some of the treated samples were then subjected to a high-temperature hydrogenation treatment (at 800°C) in an effort to achieve an even lower friction on CDC films. Friction coefficients for hydrogen post-treated films were measured to be as low as 0.11 when tested in air. Additionally, friction coefficient testing was done in dry nitrogen, and CDC films exhibited friction coefficient values as low as 0.03. Detailed mechanical and structural characterizations of the CDC films and sliding contact surfaces were done using a series of analytical techniques and these results were correlated with the friction and wear behavior of the CDC films.
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