ZL109铝合金及其复合材料干滑动磨损表面及亚表面的观察与分析

Observations and Analysis of Worn Surface and Subsurface of ZL109 Aluminum Alloy and Its Composites in Dry Sliding Friction and Wear

摘要:

利用预制体挤压浸渗法分别制备了Al2O3或C短纤维单一增强以及两者混杂增强ZL109金属基复合材料，探讨了基体合金及其复合材料的干滑动摩擦磨损行为，并对其磨损表面及亚表面形貌进行了观察和分析。结果表明：C纤维在复合材料中起到一定的自润滑作用，Al2O3和C短纤维混杂增强复合材料的磨损率低于基体合金和单一纤维增强的复合材料。与基体相比，单一Al2O3增强复合材料从轻微磨损到急剧磨损的临界转变载荷明显提高，经C纤维混杂后，其临界载荷进一步提高。经磨损表面及亚表面的观察与分析表明：纤维增强对基体合金的磨损机制没有明显影响，在轻微磨损阶段，主要磨损机制为犁沟磨损和层离，亚表面分为3个区域：表层未脱落的剥离层、亚表面裂纹形成区以及未受影响区。发生严重磨损时，磨损机制转变为严重的粘着磨损，此时表层未脱落的剥离层遭到破坏。

Abstract:

Aluminum alloy matrix composites reinforced with single carbon or alumina and the two short fibers were fabricated by a performing squeeze-infiltrated method, respectively. The dry sliding friction and wear behavior of the aluminum alloy and its composites were investigated. The morphology of worn surface and subsurface was also observed and analyzed. The results show that carbon is of a self-lubrication in the composites in a degree. Wear rate of the hybrid composites reinforced with both alumina and carbon fibers is lower than that of unreinforced aluminum alloy, and composites reinforced with only carbon or alumina fibers. By comparison with mono-renforced aluminum alloy, the critical transition load from mild wear to severe wear of the composites reinforced with only alumina fiber is improved from the range of 147 N-196 N to 196 N-245 N. Moreover, the critical transition load of the hybrid composites reinforced with both alumina and carbon fibers is improved further to 245N-296N. The observations and analysis of worn surface and subsurface indicate that the reinforced fibers have no significant effect on wear mechanisms of aluminum alloy. The dominant mechanisms are abrasive and slight adhesion as well as delamination during mild wear stage. The subsurface consists of three regions: non-peeling delamination layer, microcracks formation and propagation zone, and unaffected zone. Whereas the dominant mechanisms are shifted to severe wear, and the non-peeling delamination layer is damaged during severe wear regime.