Abrasive wear characteristics of a zinc-based alloy and zinc-alloy/SiC composite

An attempt has been made in this investigation to assess the contribution of various parameters towards governing the abrasive wear response of a zinc-based alloy under the conditions of varying applied loads and sliding distances. The factors whose contribution has been examined include deterioration in the cutting efficiency of the abrasive medium, role played by the SiC particles (dispersed in the alloy matrix) in terms of their degradation and resistance offered by them against the destructive action of the abrasive, subsurface hardening of the matrix and such other related aspects. Four types of abrasion tests were conducted on the samples to achieve the goal. The (abrasion) tests involved the use of (i) fresh as well as preworn surfaces of the samples and (ii) fresh and degraded abrasive media in four different combinations. The study suggests that the mentioned factors contribute to a varying degree towards controlling the (high-stress) abrasive wear behaviour of the specimens. However, degradation in the cutting efficiency of the abrasive medium (through capping, clogging, attrition and shelling) dominates over the influence of other parameters such as abrasion induced subsurface hardening of the matrix. Reinforcement of the SiC particles in the alloy matrix offered improved wear resistance (inverse of wear rate) under less severe conditions such as at low applied loads, wherein the dispersoid (SiC) particles could be retained by the matrix due to low cutting depths made by the abrasive particles. The dispersoid particles deteriorated the wear response of the matrix under more severe conditions of abrasion, such as at high loads, because of larger cutting depths causing fracturing and partial removal of the reinforcement (SiC) particles. The observed wear response of the samples has further been substantiated through the characteristics of wear surfaces, debris particles and abrasive medium after testing the matrix alloy and composite in a typical test condition expected to affect the abrasive medium and test specimens to the largest extent.