High-temperature dry sliding friction and wear behavior of Ni60A coating on the 20CrNiMo alloy surface treated by laser shock peening and its bonding zone

To address the cracking issues that often occur between laser cladding coatings and substrates on brake disc surfaces, methods including microhardness testing, scanning electron microscopy (SEM), and X-ray stress testing were employed. These techniques were used to study the high-temperature dry sliding friction and wear behavior of Ni60A coating on the 20CrNiMo alloy surface treated by laser shock peening (LSP) and its bonding zone. The results indicate that LSP can significantly enhance the microhardness of the coating and bonding zone, refine the microstructure, and form residual compressive stress without generating new phases. The weight loss due to wear and the average coefficient of friction for the substrate, the cladding alloy, and the LSP-treated alloy demonstrate a trend of first decreasing and then increasing with the rise in temperature. The high-temperature friction and wear performance of the LSP-treated alloy is excellent. This is particularly true at 400 C, where its wear resistance reaches its peak. Furthermore, after strengthening by LSP, the wear mechanism of the alloy at high temperatures transitions from spalling, oxidation, and adhesive wear to primarily oxidation and abrasive wear.