The statistical correlation of the coefficient of friction and wear rate of PTFE composites with steel counterface roughness and hardness

The results of tribological research of selected PTFE composites sliding against steel counterfaces of different hardness and roughness under dry friction conditions are treated in this article. The roughness of steel surface is described with different parameters such as Ra, Rz, R3z, Rp, Rk, Sm, Δα, r, Δ, etc. Based on the experimental results obtained, regression functions showing the influence of the aforementioned parameters on the tribological properties of composites were found. Using test F, the evaluation of correlation of the regression function with the results of the researches was obtained. In some cases this correlation was strong and in the other, weak. A detailed analysis showed that the roughness parameters related to the shape of asperities of the profile, i.e. Sm, Δα and Rk, have the strongest influence on the coefficient of friction, while the parameters related to the height of asperities of the profile, i.e. Rp, Rpk, Δ and Ry, have the strongest influence on the wear of PTFE composites. The R3z parameter appeared to be the most universal one: it may be employed in regression functions describing both the coefficient of friction and specific linear wear rate.