The Performance of PS400 Subjected to Sliding Contact at Temperatures from 260 to 927°C

Report No. ARL-RP-0594
Authors: Kevin C Radil; Chris DellaCorte
Date/Pages: April 2017; 14 pages
Abstract: Adequate high-temperature lubrication between loaded surfaces in sliding contact can be one of the most challenging tribological problems confronting todayâ??s engineers. In an attempt to provide a possible solution a test program was initiated to evaluate PS400, a recently patented, high-temperature solid lubricant coating. Made from nickel-molybdenum-aluminum, chrome oxide, silver, and barium fluorideâ??calcium fluoride, PS400 is a variant of the earlier coating, PS304, but is formulated for higher density, smoother surface texture, and greater dimensional stability. It was initially developed to minimize the start-stop wear in foil air bearings but is expected to perform well in other high-temperature applications where sliding friction and wear are a concern, such as variable inlet guide vanes and process control valve stems. To better define its operational capabilities, a series of tests was conducted to study the behavior of PS400 under reciprocating sliding contact at temperatures from 260 to 927 °C. The tests were performed on stationary, uncoated cobalt-based superalloy bushings loaded against reciprocating PS400-coated shaft specimens in a flat-on-cylinder configuration at Hertz contact pressures from 14.1 to 20.1 MPa. For tests conducted below 927 °C, friction coefficients ranged from 0.37 to 0.84 with wear factors on the order of 10-5 and 10-6 at the high temperatures but substantially increased at the lowest temperature. Data collected at 927 °C were limited because the coating was found to be dimensionally unstable at this temperature.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2017