Thermo-Mechanical and Fracture Characterization of Uncoated, Single and Multilayer (SiN/CrN) Coating on Granite Powder Filled Metal Alloy Composites

Abstract

The purpose of this study was to investigate the thermo-mechanical and fracture behavior of uncoated and coated granite powder reinforced 1050 aluminum alloys composite for hydro-turbine blade material. Granite powder reinforced aluminum alloy was fabricated by the stir casting technique with four different weight percentages (0 wt.%, 2 wt.%, 4 wt.% and 6 wt.% granite powder). As hydro-turbine blades are exposed to water and other slurry hard materials, the proposed granite powder reinforced composites were initially coated with a single layered thermal coating i.e CrN on granite particulate filled 1050 aluminum alloy composites and then a multi-layered thermal coating i.e SiN/CrN on the same sets of alloy composites, which significantly improved the life span of the blade material simultaneously improving the properties. The hardness of the uncoated granite powder filled alloy composites increased with the increase in granite powder content from 32 HV to 61.2 HV respectively. Similarly, for both the single and multi-layered coating the hardness of the composites increases gradually with the increased in granite powder content from 87 HV to 123 HV (single layered coating) and 93 HV to 139 HV (multi-layered coating)) respectively. The impact strength of the uncoated particulate filled alloy composites increases from 41 J to 46 J (uncoated), 44 J to 53 J (single layered coating) and 45 J to 58 J (multi-layered coating) with the increased in granite powder content. The thermo-mechanical and fracture analysis were also performed and found improved in properties in the case of the multi-layered thermal coating on the granite powder filled alloy composites.