Studies on High Temperature Wear and Friction Behaviour of AA6061/B₄C/hBN Hybrid Composites

This present work deals with the use of hexagonal boron nitride (h-BN) as a solid lubricant for AA6061/B₄C composite due to its special features of self-lubricating property, thermal and chemical stability. The wear behaviour of composites at elevated temperature test, varied from 27 to 300 °C, was performed for AA6061 alloy with boron carbide (B₄C) 5–15 wt% and h-BN 5–15 wt% reinforced hybrid composites under a load of 10 and 45 N at constant sliding velocity and sliding distance of 2.2 m/s and 2500 m. The prepared composites were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis. The mechanical properties of hybrid composites were evaluated using tensile testing and hardness. The microstructural results revealed a homogenous distribution of reinforcement particles and grain refinement in the composites up to 10 wt% of h-BN. The tensile test results showed a significant improvement in the tensile strength up to 82% attained for the 15% B₄C and 5% h-BN hybrid composite compared to AA6061 matrix alloy. The wear behaviour and different wear mechanisms under various testing conditions were explored. The mild-severe wear transition is noticed with increasing load and temperature for AA6061. The wear properties of a hybrid composite of C₁₀N₁₀ exhibited superior wear resistance due to the complete lubrication effect on the entire worn surface. The predominant wear of abrasive and adhesion occurred at room and elevated temperatures and low load conditions. Oxidative wear, plastic deformation, and delamination wear were operating with an increase in load and temperature.