An Advanced Aluminum-Tin-Silicon Engine Bearing Alloy and its Performance Characteristics

A new engine bearing alloy, Al Sn8 Si2.5 Pb2 Cu0.8 Cr0.2, has been developed. Extensive experimentation has led to this composition, which shows excellent performance characteristics, particularly seizure resistance and wear resistance. Seizure resistance of the alloy, generally thought to be directly related to soft phase content, compares favorably to that of two different versions of SAE 788, alloys that contain approximately 12% tin.

Fatigue resistance of the alloy is very good, due in part to the lower soft phase content and the absence of a pure aluminum interlayer between the lining and steel. Wear resistance is excellent due to careful attention to the size and distribution of hard phase particles in the microstructure.

The manufacturing process for the alloy includes a rapid solidification casting operation and carefully controlled thermal treatments to produce the desired microstructure with consistency.