Tribological properties of cold-sprayed 7075Al coatings reinforced with hybrid nano-TiB2/micro-SiC particles

Abstract

In this study, strategies to strengthen 7075Al matrix by blending involving nano-sized TiB2 and micro-sized SiC particles were investigated in order to prepare advanced, highly wear-resistant Al matrix composites. Cold spray (CS) technology was used to deposit a TiB2/SiC-7075Al composite coating. For comparison purposes, three additional coatings with different powder compositions were produced using the same CS processing parameters. They were pure 7075Al, TiB2/7075Al composite and SiC-7075Al composite coatings, respectively. The mechanical properties, including hardness, modulus, adhesion strength and wear resistance, were examined. The powders and their corresponding coatings, as well as the wear tracks on the coating surfaces, were observed and analyzed by optical microscopy, scanning electron microscopy and energy-dispersive spectroscopy. Results showed that the in-situ formed TiB2 particles were uniformly distributed in the 7075Al matrix, while the ex-situ deposited SiC particles were mainly distributed at inter-particle boundaries. The hybrid reinforced TiB2/SiC-7075Al composite coating exhibited the highest hardness and modulus. The tribological tests showed that both TiB2 and SiC particles greatly influenced the wear behavior of the composite coatings, with the latter having a more significant effect. Dual reinforcement with TiB2 and SiC particles enabled the TiB2/SiC-7075Al composite coating to possess the best tribological properties.