Improving the Wear Resistance of Bushings through Polymer Coatings

Abstract

The paper deals with modern designs of crankshaft bushings used in internal combustion engines. It delineates the prospects of polymer coatings to ensure additional protection of lead bronze bushings in the event of emergencies associated with a temporary loss of lubrication. For this purpose, a polymer composition of silicone polyorganosiloxane and fluoro-epoxy lacquers is proposed. Tribotechnical results are provided for polymer-coated bushings: 1) in a full-film lubrication condition, 2) in boundary conditions (with lubricant residues once the unit has been switched off) and 3) in dry conditions (with no lubrication after a long standstill). A thin-layer (3...5 μm) polymer coating based on polyorganosiloxane and fluorine can be used on the bearing surfaces of the shells of highly loaded bearings in order to increase antifriction properties, especially with limited lubrication and possible scores in a bearing.