Tribological performance of Al-12Si coatings created via Electrospark Deposition and Spark Plasma Sintering

Spark plasma sintering (SPS) and Electrospark deposition (ESD) were used as two manufacturing routes to create Al-12Si coatings with refined microstructures. The tribological performance of these coatings was tested using a linear reciprocating tribometer. The SPS and ESD coatings were compared to a conventionally as-cast ingot (AC) of Al-12Si to observe the effect of particle refinement and morphology changes. The ESD sample exhibited lower wear rates than the AC and SPS samples. During the wear process, the Al and Si phases on the surface of the AC sample were significantly refined. This refinement led to a microstructure near the surface that was similar to the sample generated by SPS, and therefore showed similar wear rates at the end of testing. Subsurface cracking, which is known to occur in the wear of powder metallurgy alloys, was observed for sample SPS. The refinement of the Al and Si phases achieved for ESD process was much greater than what resulted during the wear of the AC and SPS surfaces and as a result the ESD sample showed lower wear rates throughout the entire test.