Effect of electroless plating Ni–Cu–P layer on brazability of cemented carbide to steel

Electroless plating was applied to prepare Ni–Cu–P layer on the surface of YT15 cemented carbide. The effect of electroless plating parameters (pH values, copper sulfate concentration, and reaction temperature) on brazability of cemented carbide to steel was investigated by testing the weld shear strength between the cemented carbide and steel substrate. The surfaceʹs and interfaceʹs morphologies of the layer and the brazing seam were analyzed by scanning electron microscopy. The results show that the electroless plating Ni–Cu–P layer apparently improves the brazability of cemented carbide to steel. In addition, the electroless plating parameters significantly affect the brazability of cemented carbide to steel substrate. Under optimal conditions: the concentration of copper sulfate (CuSO4) is 1.25 g/L, pH value is 11, and plating temperature is 90 °C, the Ni–Cu–P layer is homogeneous, compact, with good metallurgical bonding between the Ni–Cu–P layer, the cemented carbide and the solder. The weld shear strength of copper brazing is up to 480 MPa, and the brazability reaches the best.