Friction studies of various materials in liquid nitrogen

D. W. Wisander, W. F. Hady, R. L. Johnson
naca-tn-4211
Feb 1958


Friction, wear, and surface-failure properties of various materials were determined in liquid nitrogen. Data were obtained at a sliding velocity of 2300 feet per minute and a load of 1000 grams with a hemisphere (3/16-in. radius) sliding on the flat surface of a rotating disk. Various metals and nonmetals including carbon, phenolic laminates, and filled Teflon were run against metals. Filled Teflon gave lower friction coefficients (0.15) and wear than any of the other materials studied, and should be useful as a seal and bearing material in some cryogenic applications. A carbon seal material with a phenolic impregnant wore rapidly. A metal-haloid impregnant gave the best wear properties to molded carbon. Phenolic laminates formed thin smear films on mating metal surfaces and gave relatively high friction coefficients (>0.5). A cermet that has been used successfully as a high-temperature seal ring failed because of subsurface brittle fracture during sliding. Decreasing the load to 800 grams reduced the tendency toward brittle fracture.

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