Wear-resisting oxide films for 900 degrees C

A study was conducted to develop low-friction,wear-resistant surfaces on high temperature alloys for the temperature range from 26 degrees C to 900 degrees C. The approach investigated consists of modifying the naturally occurring oxide film in order to improve its tribological properties. improvement is needed at low temperatures where the oxide film, previously formed at high temperature, spalls due to stresses induced by sliding. Experiments with Ti, W and Ta additions show a beneficial effect when added to Ni and Ni-base alloys. Low friction can be maintained down to 100 degrees C from 900 degrees C. For unalloyed Ni friction and surface damage increases at 400 degrees C to 500 degrees C. Two new alloys were perpared based on the beneficial results of binary alloys and ZrO2 diffusion in Ni. Low friction at temperature above 500 degrees C and reasonable values (0.32 similar to 0.42) at low temperature are obtained.