Tribological properties of B4C reinforced aluminum composite coating produced by TIG re-melting of flame sprayed Al-Mg-B4C powder

Producing a high-performance surface composite layer under severe tribological conditions such as wear was main purpose of this investigation. In this regard, B4C submicron-sized particles were chosen as reinforcement to increase tribological properties of Al-Mg alloy. A surface layer with a mixture of Al and B4C powders (5 wt%B4C) was made using thermal spray process on the substrate and then melted using gas tungsten arc welding (GTAW) technique to produce composite coating. Microstructure, formed phases and reinforcement particles in the composite layer were examined, as well. Wear behavior of samples against steel disc with hardness of 62 HRC was evaluated by a pin-on-disk setup of experiment at ambient temperature. The results illustrated significant reduction in the friction coefficient and weight loss; around 35 and 60% in comparison with uncoated substrate, respectively and showed a decline in wear rate up to 48%. Moreover, a substantial increase, up to 4 times, in the hardness of Al/5 wt%B4C composite coating was observed compared to the original substrate.