Effect of Brazing Temperature on Microstructure and Properties of WC-10Ni + AgCuTi Composite Coatings

Abstract

WC-10Ni + AgCuTi composite coating with WC mass fraction of 40% was prepared on the copper surface by vacuum brazing. The brazing temperatures were 830 °C, 860 °C, 890 °C, and 920 °C. The microstructure, interface structure, and hardness of the coating section were studied. The results showed that the composite coatings obtained at different brazing temperatures were better combined. As the brazing temperature increased, the Ni transition layer wrapped around the WC gradually decreased until it disappeared. The brazing seam gradually thickened, the reaction between the coating and the substrate became more and more intense, and more and more Cu was formed on both sides of the brazing seam. Scanning analysis of the interface between the coating and the substrate showed that the elements W and Ti hardly diffused into the brazing seam and the substrate, and the elements Ag and Cu diffused into the substrate. Finally, the interface between the brazing seam and the substrate was metallurgically bonded. The Vickers hardness results and bond strength results of the composite coatings show that the mechanical properties of the coatings are best when the brazing temperature is 890 °C.