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Two types of new conceptual lead free overlays are developed for automotive internal combustion(IC) engine bearings. The overlays are consisted of molybdenum disulfide(MoS2) and polyamideimide(PAI) resin for binding. One of the overlays is suitable for diesel engines with higher unit load and the other overlay is suitable for gasoline engines with higher sliding velocity. Both overlays indicate good corrosion resistance and wear resistance comparing with conventional lead base overlay. Moreover, higher fatigue resistance is obtained in combination with high performance lead free bearing alloy. These new bearings have the potential to become alternative materials to conventional copper lead bearings with lead base overlay.

In recent years, engines equipped with idle reduction system for fuel saving have been increased in Europe and Japan. Because of the start-stop frequency increase, correspondingly crankshaft and engine bearing contacts also increase. The friction between shaft and bearing is significant to reduce fuel consumption, and besides it, engine bearing wear tends to increase. Therefore, lower friction with small wear engine bearings are expected. In this paper, new developed engine bearing with solid lubricant overlay and its frictional and wear properties are reported (1). As experimental result, a bearing with MoS2 solid lubricant contained polyamide-imide resin coated overlay proved 40% less coefficient of friction, 25% less starting torque and 65% less bearing wear against conventional aluminum alloy bimetal bearing without overlay under close to the start-stop lubrication conditions by testers. Also diesel engine bench test proved less FMEP.