Topographic Investigation of the Wear Resistance of PTFE Seals in Sliding Contact with Ceramic Materials

This paper is concerned with the wear of PTFE seals used in connection with reciprocating ceramic-coated rods. An analysis of the relationship between the surface topography of ceramics and wear of PTFE seals was undertaken, formulating three hypotheses which have been investigated experimentally using a seal test rig and a system for three-dimensional surface roughness analysis. It was observed that no running-in of the rod surface lakes place and, consequently, the tribological situation never stabilizes. It was shown that seal wear rate is dependent on the number of asperities penetrating the lubricant film thickness, the wear rate being correlated to a functional parameter (S_{pk_0}) which was especially developed to describe the peak height above the mean plane. Furthermore, it was illustrated how the structure of ceramics allows the lubricant to flow unhindered between isolated asperities in contrast to the traditionally polished structure of steel which restricts the lubricant flow.