Sliding abrasion resistance assessment of metallic materials for elevated temperature mineral processing conditions

Abstract

The multiplicity of harsh environments in mining, processing and transporting ore and related waste, cause severe wear, extremely high maintenance costs and lost production. Elevated temperature processing is one of the conditions that influence the performance of possible materials of construction. This takes the forms of reduced hardness and strength, deleterious changes in the structure and properties of materials during protracted exposure and increased oxidation and corrosion. Drag chain conveying of hot solids e.g. in smelting, typically results in three-body sliding abrasion and adhesive wear of connecting pins and hole surfaces in link assemblies and of moving paddles that impel the particulates in enclosed channels. Selected materials have been assessed for this type of service under reciprocating sliding abrasion contact conditions using an adapted Cameron-Plint TE77 wear rig at 20 °C and 350 °C. These include the current carburised low alloy steel, other steels, Cr white irons and Co-based alloys in bulk, overlay and surface treated forms. Examination of wear scars, using scanning electron microscopy, identified the main wear mechanisms affecting the highly resistant powder metallurgical (PM) tool steels and HVOF coating as micro-scratching and as indentation leading to micro-fracture. Materials with lowest resistance displayed evidence of significant material removal by micro-ploughing. The formation of oxide layers on some samples during testing appeared to be beneficial.