On the abrasive-corrosive wear of aluminium alloys

Abstract

The performance of a range of aluminium alloys in abrasive-corrosive wear conditions which simulate those encountered in mining environments has been investigated. Wear processes are identified and the influences of material properties and microstructure are examined. Cast alloys, which show poor microfracture properties as a result of coarse and brittle phases, have poor dry abrasion resistance. Heat-treatable alloys with good combinations of hardness, strength and toughness, which provide improved resistance to surface deformation and microfracture, have improved abrasion resistance. In aqueous solutions which simulate corrosive mine waters the aluminium alloys show isolated pitting attack through to severe pitting, localized attack and general corrosion depending upon the composition, size and dispersion of microconstitutents. The presence of cathodic copper-, silicon- and iron-rich regions is particularly deleterious. Under wear conditions comprising abrasive and corrosive intervals, performance is determined by both mechanical and electrochemical properties, the importance of which will be determined by their relative severities and times of exposure. A compromise of the abrasive and corrosive resistance has to be made in order to make the optimum alloy selection. For the conditions used in the laboratory test the alloys 7017, 7075, 5083 and 5251 provide the best wear resistance, although an ideal alloy has yet to be “designed”.