Improving wear performance of Mg-4Zn alloy using Si3N4 nanoparticle reinforcements: Mass loss analysis

Si3N4 ceramic possesses superior wear properties and high-temperature properties. This research hypothesizes that very small quantities (0.23, 0.45, and 0.67 wt.%) of the biocompatible, bio-ceramic, Si3N4 nanoparticles (of 15-30 nanometre average particle size) added as reinforcements to the lightweight, biofriendly Mg-4Zn alloy matrix would improve the wear properties of the Mg-4Zn alloy. Hypothesis verification was done using design of experiments (DoE)-based dry sliding wear studies. Mg-4Zn alloy and Mg-4Zn/xSi3N4 (x=0.23, 0.45, and 0.67 wt.% nano-Si3N4) nanocomposites were the pin materials, and SS316Ti was used as the disc (counterface) material. Load and sliding speed were also varied. A regression model for predicting the mass loss was obtained using Design-Expert software. Worn surface analysis revealed that abrasion was the dominating mechanism of wear in all tested conditions. Adhesion wear was also observed at mild levels. The addition of 0.23, 0.45, and 0.67 wt.% nano-Si3N4 to Mg-4Zn alloy refined the grain size by 10.58, 34.32, and 63.94 %, respectively, thereby improving the microhardness by 8.11, 19.54, and 38.67 %, respectively, and reducing the mass loss up to 8.3%. The microstructural studies indicated α-Mg grains surrounded by Mg-Zn intermetallic at the grain boundaries.