Boundary Lubrication of Ceramic Materials by Soft Metallic Coatings and Synthetic Oil
Boundary lubrication of metallic materials often relies on surface reaction-generated films. This approach is intrinsically more difficult for ceramic materials because of their relatively lower chemical reactivity. The present study investigates the viability of boundary lubrication of ceramics by the use of a thin soft metallic film as a boundary film. Lubrication of Si3N4 and ZrO2 ceramics with coatings of Ag or Au prepared by Ion-Beam-Assisted Deposition (IBAD) and a polyol ester-based synthetic oil (with proprietary additives) was investigated. Through this method, the friction coefficient during sliding contact of ceramics was reduced (as low as 0.05) to the level that is obtained in most boundary-lubricated situations. Furthermore, wear was virtually eliminated. The method was found to be effective from room temperature up to 250°C.
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