A new type of flaking failure in bearings for electrical instruments of automotive engines

摘要

The higher transission efficiency of engine accessory drive belts has resulted in a new type of bearing damage, called "brittle flaking". The type of grease used in the bearing was found to have a significant effect on the occurrence of brittle flaking. Thus, brittle flaking can be avoided by using specific greases. The amount of hydrogen measured in the inner rings, outer rings and balls of bearings run under acceelration-deceleration tests, was highest in the stationary ring, where brittle flaking was likely to occur. Brittle flaking was reproduced in rolling contact fatigue tests when the test specimens were charged with a sufficient amount of hydrogen prior to testign. The test results concluded that brittle flaking is caused by the diffusion of hydrogen into the steel due to the decomposition of the grease by a tribochemical reaction.