Friction and wear behavior of Al–CNT composites

Aluminum (Al)–carbon nanotube (CNT) composites are promising candidates for friction and wear applications. The wear behavior of Al–CNT composites, with up to 5 wt% homogeneously dispersed CNTs, is investigated in the present study and compared to that of pure aluminum processed using the same technique of cold compaction and hot extrusion. The effects of CNT content, sliding speed and applied load, on the wear behavior of the composites were studied. The morphologies of the wear surfaces were investigated using scanning electron microscopy (SEM). Hardness and wear resistance were found to increase significantly with CNT content. The wear rate of the 5 wt% CNT composite decreased by 78.8% compared to pure aluminum. This was accompanied by a decrease in the coefficient of friction. For samples with 5 wt% CNT, the wear rate and coefficient of friction were found to decrease with increasing sliding speed. The SEM investigation of the worn surfaces confirmed the dominant role played by the CNTs in enhancing the wear characteristics. CNTs were observed to be either partially or fully crushed forming a carbon film that covered the surface and acted as a solid lubricant enhancing the wear behavior significantly.