Effect of SiC addition and running-in-wear on the sliding wear behaviour of Al-Zn-Mg aluminium alloy

Sliding wear behaviour of Al-Zn-Mg alloy and Al-Zn-Mg-SiC particle composite was studied under varying applied load. Effects of running-in-wear on sliding wear characteristics of the alloy and composite was studied giving emphasis on the parameters such as coefficient of friction, rise in temperature, wear rate and seizure pressure. The seizure pressure of composite was noted to be significantly higher than that of the alloy and is increased further due to running-in-wear prior to the test. The running-in-wear also improved the wear resistance and seizure pressure of the alloy, whereas both the coefficient of friction and temperature rise are reduced due to running-in-wear. However, the level of improvement in seizure pressure due to running-in-wear is relatively less in composite (22%) as compared to that in alloy (40%). These facts have been discussed on the basis of nature of worn surface produced after running-in-wear. The worn surface was studied in detailed through scanning electron microscopy, EDX analysis and X-ray diffraction measurement. Transfer of counter surface material, the formation and stability of mechanically mixed layer (MML) in the investigated materials were assessed indirectly through these analyses. The MML is noted to be more stable in running-in-wear samples as compared to the fresh samples both in alloy and composites.