Abstract
We newly developed the prototype calcium complex grease (Cx-S) which delivered a better temperature performance than traditional calcium complex greases and could keep its structure even over 200°C. This was achieved by combining the common calcium complex thickener technology with a new concept. In this report, the bearing life of several grease types was evaluated by ASTM D 1741. It was demonstrated that the bearing life of Cx-S wasn’t as long as urea grease, although it had excellent anti-oxidation performance. Additionally, leakage rate was calculated by the amounts of leaked grease from bearings during the test. Therefore, it was suggested that a physical factor such as shear stability of the grease is likely to cause shorter bearing life. Then, by using behenic acid instead of stearic acid - to improve shear stability of Cx-S - it was found that behenic type calcium complex grease (Cx-B) forms much thicker and stronger fiber micelles than stearic type (Cx-S). As a result, the shear stability of Cx-B was strongly improved and bearing life was extended by 50% compared to Cx-S.
