Wear behaviour of zinc-based alloys as influenced by alloy composition, nature of the slurry and traversal distance

Abstract

In this study, the influence of microstructural alterations brought about by adding silicon on the slurry wear behaviour of a zinc-based alloy has been investigated. Wear tests were conducted using sample rotation method at a speed of 4.71 m/s over a range of traversal distance and sand concentration in the test environment. The electrolyte (i.e. liquid part of the slurry) contained chloride and sulphate ions which are essential constituents of mine water. The study suggests maximum wear loss and rate of the samples in the liquid-only medium. The presence of suspended sand particles in the liquid led to substantially decrease the wear rate/loss. A comparison of the wear response of the samples in the liquid plus sand environments showed that intermediate concentration, i.e. 40%, of the suspended sand particles in the test environment caused maximum wear rate/loss. However, this was substantially less than the liquid-only medium. The wear loss increased with traversal distance. The slope of the wear loss versus traversal distance plots was high initially followed by a reduced slope at longer traversal distances. This trend was very clearly visible in the liquid-only environment. Increasing traversal distance initially led to higher wear rate. This was followed by the attainment of a wear rate peak, a reduction in wear rate and finally a steady state wear rate at longer traversal distances. The average (cumulative) wear rate versus average (cumulative) wear loss plots showed acceleration, steady state and deceleration zones depending on the test conditions. Silicon particles, generated as a result of silicon addition in the alloy system, led to improved wear behaviour. Observed wear characteristics of the samples have been explained on the basis of operating wear mechanisms such as corrosion, erosion and abrasion. Predominance of one mechanism of material removal over the other(s) and the nature of various reaction products formed on the affected surfaces were thought to be responsible for specific wear behaviour of the samples under a given set of conditions. Examination of affected surfaces and subsurface regions further supported the wear characteristics of the specimens.