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

Xiangping Xu,Chunzhi Xia,Jiasheng Zou,Yi Wang,Chi Liu

doi:10.3390/coatings9110703

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.

Highlights

Copper and copper alloys have high electrical and thermal conductivity, good corrosion resistance, and wear resistance, and are widely used in electric power, electrical, mechanical, and other industrial fields, such as continuous casting molds, blast furnace tuyeres, lead frames, electric vacuum devices, and power rails
With the rapid development of the manufacturing industry, higher requirements are imposed on the conditions of use of copper alloy parts, and related surface engineering techniques have emerged to achieve enhanced surface strength and maintain high electrical conductivity of the copper alloy as a whole [1,2]
The composite coating material used in the experiment consisted of WC-10Ni powder of 11 μm points 1–3 on the copper substrate, taking 4–5 on the brazing seam and taking the point 6–10 on the to 45 μm, AgCuTi solder of 30 μm to 45 μm, and a trace amount of binder

Summary

Introduction

Copper and copper alloys have high electrical and thermal conductivity, good corrosion resistance, and wear resistance, and are widely used in electric power, electrical, mechanical, and other industrial fields, such as continuous casting molds, blast furnace tuyeres, lead frames, electric vacuum devices, and power rails. The purpose is to improve the hardness and wear resistance of the surface of the part and to avoid the problems of poor bonding performance, large residual stress, and high input cost when preparing the composite coating by thermal spraying, surfacing, and laser cladding. The composite coating material used in the experiment consisted of WC-10Ni powder of 11 μm points 1–3 on the copper substrate, taking 4–5 on the brazing seam and taking the point 6–10 on the to 45 μm, AgCuTi solder of 30 μm to 45 μm, and a trace amount of binder. The bonding strength of the coating to the substrate was tested using a CMT5205 electronic universal testing machine (Zhuhai, China) and a self-designed shearing fixture, and the coating was tested five times at each temperature

Microstructure and Structure Analysis of the Coating Section

Internal

Composite Coating Cross-Section Microhardness Test

10. Under conditions brazing of 830The

Conclusions