The Tribological Properties of Plasma Spray Coated Al₂0₃

Abstract

Cast iron is used as a sliding material for machine tools such as a lathe. To improve the tribological properties of the cast iron, we applied a plasma spray coating to the cast iron. In this study, the cast iron was coated with films of Al₂O₃ powder and a mixture of Al₂O₃ powder and Pb, Sn or Pb-Sn alloy powders. The softer metallic powders were expected to act as solid lubricans on the film surface. The frictional and were properties of the films were examined using a reciprocating tribometer. In the case of the Al₂O₃ film coating, it was found that the initial wear was influenced by surface roughness under both dry and grease-lubricated conditions; that is, the rougher the surface, the greater was the wear. For smoother specimens the wear was negligible under the grease-lubricated condition. The tribological properties in the case of the Al₂O₃ mixture film coatings were not as good as expected because the films were not strong enough.