Effect of sliding speed and sliding distance on wear behavior of AZ31-B4C composite

Abstract

Emphasis of current research is to investigate the dry sliding behavior of AZ31 magnesium alloy and AZ31–1.5B4C magnesium metal matrix composites (MMCs) at varying sliding speeds and sliding distances. Magnesium alloy and composite are fabricated through ultrasonic assisted stir casting method. Optical microscope (OM), scanning electron microscopy (SEM), and energy dispersive x-ray analysis (EDAX) are used to characterize developed materials. Microhardness of all materials is measured using a Vickers microhardness tester. Wear-friction behavior is investigated in dry sliding mode using pin-on-disc tribometer at room temperature. Magnesium alloy and composite are tested over a range of sliding speeds (0.25–1.25 m s−1) and distances at a moderate normal load (20N). Wear morphology is finally investigated for composites and alloy under SEM and EDAX. SEM micrographs of as-cast AZ31-1.5B4C composite reveals uniform distribution of B4C particles with noticeable refinement in grain structure. EDAX spectra of AZ31-1.5B4C composite depict the presence of boron and carbon along with existing elements of AZ31 alloy. Microhardness has enhanced around 30% for Mg-MMC by incorporating 1.5 wt% B4C in AZ31 alloy. Furthermore, the use of B4C as reinforcement increases the density of the composite. Wear rate is reduced by around 20% and COF is reduced by around 25% for AZ31-1.5B4C composite compared to AZ31 alloy for all experimental conditions. Abrasion, oxidation, adhesion and delamination wear mechanisms are observed as dominant mechanism for varying sliding speeds and distances.