Comparative study of microstructure, mechanical, and wear behavior on Cu/hBN composites sintered through microwave and muffle furnace

Abstract

In this work, copper reinforced with different weight percentage of hexagonal boron nitride particles (0, 1.5, 3, and 4.5 wt.% designated as C0, C1, C2, and C3, respectively) were fabricated through powder compaction technique followed by a sintering process. Sintered process was carried out in two different furnaces, microwave and muffle. Initially, the alloy particles were mechanically blended, and then, the processed materials were compacted in ambient condition and sintered at 800 °C for 60 min in both furnaces. Microstructure behavior was analyzed through optical microscope and scanning electron microscope. Physical, mechanical, and wear behavior of the sintered composites were studied as per the American Society for Testing and Materials (ASTM) standards. Microstructural study revealed that the microwave sintered composites had better particle dispersion than muffle sintered composites due to rapid heat increasing. The hardness and compression strength of sintered composites decreased as the wt.% of hexagonal boron nitride increased. Due to the weak interfacial bonding between matrix and reinforcement, microwave and muffle sintered C3 composites have 45% and 60% lower hardness values and 66% and 96% lower compression strength than base alloy, respectively. The wear behavior of sintered composites were evaluated by the pin-on-disc setup at ambient and elevated temperatures (200–500 °C), with the varying loads (10–40 N). As the wt.% of solid lubricant increased, the sample's wear resistance improved. At 10 N, microwave and muffle sintered C3 composites have a wear rate of 86% and 80% lower than sintered alloy. Especially, microwave sintered C3 composites had 83% better wear resistance than muffle sintered C3 composite. In elevated conditions, microwave sintered C3 composites had 7% greater wear resistance than muffle sintered C3 composites at 200 °C, owing to the formation of the hexagonal boron nitride tribolayer. The scanning electron microscope images of the worn-out surfaces and wear debris of the sintered composites exposed that the wear mechanisms conquered grooves, delamination, oxide debris, and spalling.