Lubrication of Bearing Steels with Electroplated Gold under Heavy Loads

Abstract

The lubricating action of electroplated gold on 52100 steel and 440 C stainless steel in sliding under 68-kg load was examined with a tester consisting of a single rub block loaded against a rotating disk. The advantage obtained with gold plating was that of low wear while the coefficient of sliding friction remained high. The wear life of thick films was much longer; one 20 μ film had a wear life of 150,000 revolutions, while 1 μ films had wear lives of about 3000 revolutions. Silver, copper, and two gold alloys plated to the appropriate thickness were able to extend the wear life to several thousand revolutions while nickel was not effective at all. The failure of the plated films was usually marked by a rapid increase in wear rate. With thick gold alloy films, wear debris in the form of flakes were obtained in addition to irregular shaped particles. The appearance of the wear track indicated that the gold film underwent considerable plastic deformation.