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A failure mode in engine components that undermines engine reliability is scuffing; defined as sudden catastrophic failure of sliding surfaces. Usually accompanied by a rapid rise in friction and temperature, occurrence of scuffing marks the end of the component's useful life. At Argonne National Laboratory, we recently developed low-friction amorphous carbon coatings with exceptional tribological properties. The present study evaluates the scuffing performance of three variations of the carbon coating deposited on H-13 steel surfaces and lubricated with base-stock and fully formulated synthetic Poly-alfa-olefin (PAO) lubricants. Using a ball-on-flat contact configuration in reciprocating sliding, we found that although the coatings reduced friction slightly, they increased scuffing resistance significantly when one of the sliding surfaces was coated when compared to uncoated steel-on-steel contact.

Laser glazing of steel is being investigated as a means of improving its tribological properties for railroad and other applications. The microstructure of the surface layer on 1080 steel formed by the process was characterized by optical and transmission electron microscopy (TEM) and microhardness measurements. The microhardness increases were consistent with self-quenching of the 1080 steel, followed by tempering of adjacent areas. TEM revealed a very fine (5-10 nm) grain size. Friction and wear tests were conducted on glazed and unglazed materials with a pin-on-disc test rig. Laser glazing reduced both friction and wear during dry tests. The improved friction and wear performance is attributed to the microstructural changes of the near-surface region by laser glazing.