Study on the influence of surface nickel plating on the microstructure and mechanical properties of WC-8Co/Inconel 718 brazed joints

The drilling and sampling technique is the preferred method for lunar soil sample collection. In response to the poor wettability of the AgCuNiMn brazing alloy that is utilized for the lunar soil drilling tools on the surface of Inconel 718 superalloy, a nickel plating process was adopted for surface modification of the superalloys. Under the conditions of 890 °C and 10 min, the influence of nickel plating and different plating thicknesses on the wettability and gap-filling capability of the brazing alloy, as well as the microstructure and mechanical characteristics of the joints, were investigated. An analysis was done on the brazed joints’ microstructural development process and strengthening mechanism. The findings show that nickel plating on the superalloys’ surfaces considerably increases the brazing alloy’s wettability to the substrate and its gap-filling capacity. The gaps between the base materials are closed, and the contact angle between the brazing alloy and the superalloy surface is decreased from 20 to 4°. With an increase in plating thickness, the joint’s shear strength initially rises and subsequently falls. When the plating thickness is 28 μm, the shear strength is increased by 43.5% (from 168 to 241 MPa) compared to the unplated brazed joint.