THE INFLUENCE OF PHOSPHATE ADDITIVES ON THE MICROPITTING OF GEARS

抄録

Micropitting, one form of fatigue damage, can lead to serious breakage if it progresses. In this study, I examined lubricants with different types of phosphate additives and considered their influence by analyzing the surfaces of gear teeth.
The test results showed that while lubricants with a high acid number (AN) of phosphate additive easily expand micropitting areas, but they could protect the depth of the damage. The lubricants with lesser amounts of AN phosphate additive prevented expansion of the micropitting areas, yet easily caused large pits.
It is consider that low acid number phosphate additives have few hydroxyl groups. Therefore they could cause only physical adsorption. Thus, the amount of additive on the tooth surface will be insufficient, the adsorbing power of the additive is weak and causes deep damage.