摩擦氧化层对TC4合金磨损行为和摩擦系数的影响

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

摘要:

选取TC4合金与三种摩擦副微动磨损的完全滑移区,研究摩擦氧化层的形成对TC4合金微动磨损行为和摩擦系数的影响。结果表明：室温下摩擦系数曲线经历阶段性变化,合金表面未形成摩擦氧化层,磨损率均较高。下试样加热至260℃时,TC4/GCr15微动摩擦系数曲线最早出现由动态稳定向直线稳定的过渡,最早发生轻微磨损转变和摩擦氧化层的形成,磨损率明显减小,TC4/Si₃N₄和TC4/Al₂O₃配合下未形成摩擦氧化层,磨损率急剧攀升至最大值。下试样加热至450℃时,TC4合金与三种摩擦副微动磨损均出现轻微磨损转变,合金表面均形成不同于基体的摩擦氧化层,磨损率低于室温且达到最小值。TC4合金良好的高温微动磨损性能归因于分布均匀、连续致密、粘结良好的摩擦氧化层的形成。TC4合金轻微磨损转变前微动损伤由粘着和磨粒磨损控制,轻微磨损转变后由氧化磨损伴随轻微磨粒磨损控制。

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.