Activation of SiC Surfaces for Vapor Phase Lubrication by Chemical Vapor Deposition of Fe

Abstract

Vapor phase lubrication (VPL) has been proposed as a method for lubrication of high temperature engines. During VPL, lubricants such as tricresylphosphate (TCP), (CH3–C6H4O)3P=O, are delivered through the vapor phase to high temperature engine parts and react on their surfaces to deposit a thin, solid, lubricating film. Although ceramics such as SiC are desirable materials for high temperature applications, their surfaces are unreactive for the decomposition of TCP and thus not amenable to VPL. As a means of activating the SiC surface for TCP decomposition we have used chemical vapor deposition of Fe from Fe(CO)5. Modification of the SiC surface with adsorbed Fe accelerates subsequent decomposition of TCP and deposition of P and C onto the surface. In the temperature range 500–800 K, m-TCP decomposes more readily on Fe-coated SiC surfaces than on SiC surfaces. The C and P deposition rates depend on the thickness of the Fe film and are further enhanced by oxidation of the Fe. This work provides a proof-of-concept demonstration of the feasibility of using VPL for ceramics