ISSN   1004-0595

CN  62-1224/O4

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磨屑对TC4钛合金微动磨损行为的影响

Effect of Debris on Fretting Wear Behavior of Ti-6Al-4V Alloy

  • 摘要: 通过在微动循环一定周次后清除磨屑和制备表面织构储存磨屑,研究磨屑对TC4钛合金微动磨损行为的影响. 结果表明:与以往认识不同,清除磨屑会导致摩擦系数和系统形变量随周次的变化曲线出现突降,最大降幅分别可达63%和41%,微动循环图也相应发生改变. 循环一定周次后,磨屑的产生和排出重新达到平衡,摩擦系数与系统形变量又恢复到清除磨屑之前的水平. 当在TC4钛合金表面制备垂直于微动方向的沟槽状表面织构后,大量的磨屑被沟槽束缚在接触区域,造成接触面之间磨屑较多,进而导致摩擦系数和系统形变量比无织构时更大,最大增幅分别可达21%和47%. 收集磨屑后用扫描电子显微镜观察,发现磨屑呈松散的颗粒状,尺寸集中在0.2~1.5 μm,并且多数呈现团聚状.

     

    Abstract: By removing the debris after a certain number of fretting cycles, and preparing the surface texture to store more debris, the effect of debris on the fretting wear of Ti-6Al-4V alloy was studied. The fretting tests were conducted under different loads (from 15 N to 120 N) and different applied displacements (from 20 μm to 50 μm). It could be found that different from the usual understanding in the past, the removal of wear debris would cause a sudden drop in friction coefficient as well as the system deformation. The biggest drop reached 63% and 41% under the load of 20 N respectively. The drop of friction coefficient was caused by the reduction of the large particles of debris, while the small particles of debris still remained at the wear scar and played a role in reducing friction. The fretting loops would also change accordingly. After a certain number of cycles, the initiation and ejection of wear debris became balanced again, which led to that friction coefficient and system deformation reached the level before the debris was removed. When the groove surface textures perpendicular to the fretting direction were prepared on the surface of the Ti-6Al-4V alloy, a large amount of wear debris was trapped in the contact area by the grooves. This caused bigger friction coefficient and the system deformation. The maximum increase reached 21% and 47% under the load of 20 N respectively. After collecting the wear debris, the scanning electron microscope observation showed that the wear debris was loose granular, the size was concentrated between 0.2 μm and 1.5 μm, and most of them appeared agglomerated. The loose debris acted as a buffer between the two contact surfaces. As a result, the more debris led to the more obvious buffering effect as well as the bigger system deformation.

     

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