On the Potential of CVD Diamond Films as Mechanical Seal Face Materials

Polycrystalline diamond coatings have been deposited by microwave plasma-assisted CVD onto silicon carbide substrates. The coating conditions and the substrate properties were varied systematically using the Taguchi method and the resulting coating morphologies were determined. A second Taguchi experiment was then used to assess the tribological performance of the coatings against a range of counterface materials in a thrust washer test rig. The results of these tests are reported here, and they confirm the excellent tribological performance that can be obtained. Consideration is also given to the role of surface texture in determining seal performance. A simple mathematical model has been developed to assist in the characterization and interpretation of the tribological results produced. The surface texture of the diamond films was identified as significant to their tribo-performance. The model demonstrated how the surface texture could contribute to interface lubrication.