Abstract
Micropitting, which is one form of fatigue damage, can lead to serious breakage if it progresses. In this study, I examined two lubricants that differ in their micropitting characteristics, and investigated the influence of the boundary lubrication film by analyzing the surface shape and the chemical forms on the tooth flank. The micropitting test was carried out using the FZG gear test machine (DIN51354). From the test results, the number of smoothed areas was greater on the tooth surface which micropitted area was smaller. And the smoothed area was softer than other area. According to XPS analysis, the main ingredient of the boundary lubrication film was iron phosphate and iron oxide. A higher ratio of iron phosphate film was found in the deeper on the softer tooth surface. Blending the lubricant with an additive agent to form a flexible iron phosphate film prevented the generation of micropitting on the tooth surface.
