Metal Matrix Composites (MMCs) are seeing increased use in tribological applications where hardness, toughness and wear resistance are required. Already such qualities have been included within composite coatings by methods such as electrochemical deposition. In this study the feasibility of including diamond as the hard phase in MMC’s using thermal spraying processes has been investigated. In this work the application specifically targeted is that of hard facing for sub sea drill bits, where the coatings experience a harsh environment of high stress abrasion, erosion and corrosion. The coatings were investigated in terms of their microstructure (light microscope, SEM), their elemental composition using EDX and XRD to identify retention of diamond and phases in the coatings, their hardness and abrasion resistance. Preliminary results show that it is possible to produce a hard facing diamond composite coating with good distribution of the diamond phase and little degradation of the diamond during the spraying and that diamond MMCs (DMMC) have potential for improving durability in drill bits. Diamond/metal powder mixture is sprayed onto the surface using an oxyacetylene torch.

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