A generic model for dry sliding wear of metals at elevated temperatures

The tribological behaviour of a nickel-base alloy, Nimonic 80A, has been studied on a like-on-like pin-on-disc reciprocating wear rig at temperatures from 20 to 600 °C. A transition in wear rate from severe to mild wear is observed during the sliding which is accompanied by the development of wear-protective layers, having high electrical resistance, on the wear surfaces. Below 250 °C, the wear-protective layers consist essentially of compacted wear debris particles. At temperatures above about 250 °C, smooth 'glaze' layers develop on these compacted particulate regions and the wear rate in the mild wear regime is negligibly small. Partial pressure of oxygen in mixtures of oxygen and argon gas has significant effect on the wear rate at temperatures below 250 °C, a peak being observed in the curve of wear against partial pressure of oxygen. However, at temperatures of 400 and 600 °C, no significant effect of partial pressure of oxygen was observed. A generic mathematical model has been developed for the formation of wear-protective layers and the transitions from severe to mild wear; the model can be extended to apply in any dry sliding wear processes where the transition of wear occurs as a result of the development of compacted triboparticulate layers. The effects of ambient sliding temperature and partial pressure of oxygen on wear at elevated temperatures have been simulated by applying the proposed model. Reasonable agreement has been achieved between calculated results and the experimental observations at temperatures from 20 to 600 °C