Abrasive wear of composite coatings in a saline sand slurry environment

Abstract

The ability to deposit metal matrix composite (MMC) coatings on the surface of aluminium alloys has the potential to expand the engineering applications of these materials. Composite coatings reinforced with discontinuous ceramic particles enhance the substrate's tribological properties. In applications where dry sliding or low stress abrasive wear processes predominate, these coated aluminium alloy components could provide superior wear resistance when compared to aluminium alloys. In the present work, MMC coatings were formed on AA5083 aluminium alloy using a plasma transferred arc (PTA) surfacing technique. These relatively thick coatings (3–5 mm thick) exhibit microstructural properties characteristics of a bulk composite material which are independent of the substrate properties. The excellent weldability of AA5083 alloy makes it an ideal candidate for this surface treatment. Composite coatings reinforced with discontinuous ceramic particles of Al 2O 3, SiC and TiC (70 μm) and varying volume fraction, V r (0–40%) were prepared. The aim of the present study was to investigate the performance of such composite coatings under conditions of aqueous corrosion and low stress abrassion. Initially, immersion tests were performed on the coatings using a 3.5 wt. % NaCl solution to assess the corrosion behaviour. Low stress abrasive studies were then conducted using a wet rubber wheel test rig. In these wear tests, the silica sand abrasive were suspended in a solution of 3.5 wt. % NaCl, instead of deionised water, as specified in the Standard. The influence of corrosion and low stress abrasion on these various MMC coatings is discussed in the present work.