Scanning Electron Microscope Studies of Copper-Lead Bearing Corrosion

Scanning Electron Microscopy is a highly effective tool for characterizing the types of corrosion experienced by the surface of copper-lead connecting rod bearings from the CLR engine L-38 Test. Results indicate that the initial corrosive attack on these surfaces is preferentially upon lead; subsequent attack is upon lead and/or copper. Although ethylene dibromide and ethylene dichloride fuel scavengers contribute to corrosion, the presence of halogen on after-test bearing surfaces is not necessarily associated with high bearing weight loss. The effect of ashless dispersants, alkaline detergents and zinc dithiophosphates on bearing corrosion was also investigated. No relationship was found between additive performance and the generation of additive-derived films on bearing surfaces.