Influence of ZrB <sub>2</sub> /hBN particles on the wear behaviour of AA7075 composites fabricated through stir followed by squeeze cast technique
P. Loganathan, A. Gnanavelbabu, K. Rajkumar
Abstract
This paper reports on the effect of ZrB 2 and hBN solid lubricant particles on the dry sliding wear behaviour of the AA7075 composite, fabricated by stir-squeeze cast technique. ZrB 2 and hBN at levels of 5 wt% were chosen as reinforcements for the study. The optical microscope images revealed uniform distribution of particles and a low order of porosity in microstructure, possibly due to the squeeze pressure. The ZrB 2 particles reinforced composite (AZ) showed an improvement in hardness compared to as-cast (A0) and hBN containing composite (AH). A minor reduction in the hardness of ZrB 2 –hBN hybrid composite (AZH) was observed. This is attributed to changes in the hardness induced by the individual ZrB 2 and hBN particles. The hybrid composite (AZH) exhibits a superior wear resistance, possibly due to the formation of good quality B 2 O 3 and H 3 BO 3 self-lubricating film.