Effect of tribo-oxide layers on wear properties and coefficient of friction of TC4 alloy in fretting

Abstract:

The gross slip regimes of TC4 alloy against with various counterface materials and temperatures at critical experimental conditions were selected to study the effect of formation of tribo-oxide layers on wear properties and coefficient of friction of TC4 alloy in fretting wear. Results show that irrespective of tribo-pairs, the coefficient of friction of TC4 alloy had undergone periodic evolutions at room temperature, no tribo-oxide layers had been produced on wearing sufaces and the wear rates were higher. When the samples were heated to 260℃, the COF of TC4/GCr15 tribo-pair appeared the earliest transition from a ‘concave-convex’ dynamic to an approximately ‘straight-line’ stable state, the earliest severe-mild wear transition occurred and tribo-oxide layer had generated resulted in the wear rate reduced signigicantly, however, TC4/Si₃N₄ and TC4/Al₂O₃ tribo-pairs had no abviously tribo-oxide layers formed, and the wear rate climbed sharply to the maximum value. Severe-mild wear transitions of TC4 alloy against with various counterface materials had occurred while the samples were heated to 450℃, the tribo-oxide layers differed from the matrix were formed on worn surface and the wear rates were lower reaching a minimum value. The excellent of wear properties of TC4 alloy in fretting at elevated temperature is attributed to the generation of a tribo-oxide layers with uniform distribution, continuous compressed and good adhesion. The wear mechanisms of TC4 alloy was dominated by adhesive and abrasive wear before the severe-mild transition, while controlled by oxidative with slightly abrasive wear after the transition beginning.