PMMA转动微动摩擦学行为的研究

Study on Rotational Fretting Tribology Behavior of PMMA

在新型转动微动试验机上,进行了PMMA与GCr15钢球(40mm直径)在转动角位移幅值为0.25～2.5°和法向载荷为100N的转动微动试验。在摩擦动力学行为研究的基础上,结合磨痕的微观分析,研究了其转动微动磨损机理。结果表明:随转动角位移幅值的增加,PMMA的转动微动会依次呈现三个区域,即部分滑移区、混合区和完全滑移区;相比部分滑移区和完全滑移区,混合区的摩擦系数明显较高;部分滑移区摩擦系数保持在较低水平且损伤轻微,微动的相对运动由弹性变形协调。在混合区和滑移区PMMA的转动微动磨损机制为伴随黏性流动的颗粒剥落和磨粒磨损。研究发现在混合区和滑移区的磨斑中央产生因黏性流动造成的损伤累积所致的材料隆起。

Rotational fretting tests of polymethylmethacrylate（PMMA）flat against GCr15 steel ball（with diameter of 40mm）were performed on a new rotational fretting tester,with different angular displacement amplitudes from 0.25° to 2.5° and a normal load of 100N.Based on the study of the frictional kinetics of rotational fretting and the micro-analysis of the wear scar,the damage characteristics of PMMA were discussed in detail.The results indicated that three fretting running regimes were presented during the rotational fretting of the PMMA with the increase of the angular displacement amplitude,i.e.partial slip regime,mixed fretting regime and gross slip regime.To compare with the partial slip regime with the gross slip regimes,the friction coefficient of the mixed fretting regime was much higher.In the partial slip regime,a lower level of friction coefficient was held and slight damage was appeared,while the fretting motion was accommodated by elastic deformation.In the case of both mixed fretting and gross slip regimes,particles detached by delamination and abrasive wear accompanying with viscous flow were the main rotational fretting wear mechanisms.The research found that an upheaval was formed induced by damage accumulation of viscous flow at the center of wear scar in the mixed fretting and gross slip regimes.