A study of sliding wear behaviors of Al-7075 alloy and Al-7075 hybrid composite by response surface methodology analysis

摘要

In this paper, an attempt has been made to investigate the specific wear rate of the unreinforced Al 7075 and hybrid aluminum metal matrix composite reinforced with the hard ceramic (7 wt.% of SiC) and soft solid lubricant (3 wt.% of graphite) fabricated by using stir casting method. The unlubricated pin-on-disc wear tests were conducted to examine the wear behavior of the aluminum alloy and its composites. The sliding wear tests were carried out at various loads (20-60 N), speeds (2-6 m/s), and sliding distances (2000-4000 m). It is inferred that specific wear rate of the hybrid composite is lower than that of the unreinforced Al 7075 in all combination of loads, sliding speeds, and sliding distances. The specific wear rate exhibited increasing trend with change of load. However, it is apparent from the result that specific wear rate decreases up to the speed of 4 m/s and then starts increasing. To recognize the mixing of reinforcement, worn surfaces and wear debris tested samples were examined using scanning electron microscope (SEM and EDX) and X-ray diffraction (XRD). Response Surface Methodology (RSM), which is a statistic method has been used to find out the most significant factor, which influence the specific wear rate. Consequently, it is concluded that load is most significant factor which leaves an effect on specific wear rate. Sliding speed and sliding distance provide the secondary contribution to the performance indicator.