Processing and dry sliding wear performance of spray deposited hyper-eutectic aluminum–silicon alloys

The influence of spray deposition process on the refinement of silicon phase and the tribological performance of hyper-eutectic Al–Si alloys is reported in this work. Due to the rapid solidification conditions that prevail during the spray deposition process, both primary and eutectic silicon were found to be refined resulting in equi-axed morphology of the silicon phase across the matrix. The average silicon particle size increased from 7 μm to 17 μm with increase in the silicon content of the spray deposited alloys used for the present study. Transmission electron microscopy of the spray deposited samples exhibited sub-micron sized silicon particles of both equi-axed and acicular morphology in the aluminum matrix. Pin-on-disc wear tests were performed on the spray deposited samples, by sliding samples against hardened steel counterface for about 1000 m at a speed of 0.3 m/s under varied loading conditions ranging from 0.17 MPa to 1 MPa. Scanning electron microscopy of the wear tracks and wear debris was carried out to understand the wear mechanism. The wear performance was improved with increase in the silicon content of the alloy. The wear performance of the alloys was compared with similar alloys produced through various processing routes reported in the literature. The spray deposited alloys were observed to exhibit relatively better wear performance for the range of composition and loading conditions employed.

► Spray forming of the hyper-eutectic Al–Si alloys followed by pin-on-disc wear studies. ► Refinement of silicon as a function of silicon; observation of sub-micron sized silicon particles. ► Wear rate of the alloys decrease with increase in silicon content but at a decreasing rate. ► Comparison with the alloys processed through various processing routes reported in literature. ► Wear track and debris analysis: observation of oxidative wear.