Surface Fatigue Initiated by Fatty Acids

The performance of fatty acids under inerted atmospheres is found to depend upon base stock. The presence of aromatics in the base oil causes severe failure of the test specimens even under conditions of light load. The severity increases with increasing acid chain length in the series C4 to C18. The results are rationalized by suggesting a surface fatigue mechanism. The generation of a carboxylate anion is assumed to cause crack growth and the cyclic stressing of the moving member which occurs during the sliding process is assumed to cause rapid crack propagation. Presented as on American Society of Lubrication Engineers paper at the ASME/ASLE International Lubrication Conference held in New York City, October 9–12, 1972