Investigation of adhesion and diffusion activity of Cu – Mn – Ni brazing filler metal with WC – 8Co cemented carbide

Abstract

In this work, the interaction between Cu – Mn – Ni brazing filler metal (BFM) melt and WC – 8Co cemented carbide is studied. In particular, the diffusion interaction in a binary system (BFM-cemented carbide substrate) and a ternary system (steel-BFM-cemented carbide substrate) is considered. An attempt has been made to control the interaction process by applying thin metal coatings (Ti, Cr, Al, Ni, Cu) by the magnetron sputtering method. For the CuMn24Ni9 filler metal temperature dependences of contact angles on cemented carbide are obtained. Their dependences on the coating material and the depth of interaction between BFM melt and cemented carbide substrate is also estimated. It was found that the thickness of the diffusion layer of brazing filler metal into the cemented carbide depends on the temperature and does not depend on the coating material and the amount of liquid interacting with the substrate. The depth of copper diffusion into the cemented carbide is 100 ± 5 μm for a heating temperature 1120 oC and 50 ± 8 μm for a temperature 960 oC. Without coating, the contact angle is 15. The minimum contact angle obtained on the Ni coating is 6. For Al, Cr and Ti coatings, to obtain a contact angle of less than 10, high temperatures are required, over 1200 oC. The evaluation of the failure mechanism of brazed samples with preliminary deposited metal coatings during shear testing has been carried out. Fracture of all brazed samples took place on the cemented carbide, except for those coated with Ti. Cracks in all samples originated in the region above the fillet, and then penetrated deep into the material. The reported study was funded by RFBR according to the research project № 20-32-90011.