Titanium nitride concentration and coordination effect with hexagonal boron nitride enhancing the reciprocating wear behavior of AZ91D alloy-based composites

Abstract

The influence of TiN hard ceramic concentration and coordination effect of hBN solid lubricant particulates on reciprocating wear and friction behavior of AZ91D alloy-based magnesium matrix composites is investigated in this work. A unique stir-ultrasonication-squeeze casting procedure was employed to fabricate the composites. The fine dispersion of reinforcing particulates in matrix was examined using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). The X Ray Diffraction (XRD) analysis confirmed the existence of reinforcements in composites and formation of intermetallic phases demonstrating the thermal stability of matrix reinforcement materials. The hardness of fabricated AZ91D/5 wt.% TiN (AT), AZ91D/5 wt.% hBN (AH), AZ91D/5 wt.% TiN/5 wt.% hBN (ATH), and AZ91D/10 wt.% TiN/5 wt.% hBN (ATTH) composites were increased by 18.37%, 8.14%, 11.68%, and 25.2% in comparison with as-cast alloy “A”. The tribo-properties of single and dual ceramic particles reinforced materials were investigated using a linear reciprocating tribometer at an unchanged sliding distance of 200 mm and stroke length of 10 mm under varied loads (7.5, 15, 22.5, and 30 N), reciprocating frequencies (2, 4, 6, and 8 Hz), and temperature conditions (50°C, 100°C, 150°C, and 200°C). Compared to material “A,”“ATTH” composite performs well in terms of wear behavior, with performance increasing by 42.63% and 54.33% respectively, under ambient and enhanced conditions. At low load, increased frequency accelerates material removal from the plate’s surface due to direct abrasion and plowing action caused by rough asperities on the counterface. The increase in applied load under high-frequency settings increases the pin’s contact pressure with the sample surface, which raises the temperature and causes the shallow grooves to severe delamination. At increased temperatures, the wear characteristics of intense oxidation, plastic deformation, and significant delamination were discovered on manufactured materials.