Characteristics of Al2O3/diamond/c-BN/SiC grain steel brazing joints using Cu–Sn–Ti active filler powder alloys

• A diamond/CBN/Al2O3/SiC brazed tool was proposed.
• The grains were brazed onto steel substrate using Cu–Sn–Ti alloys.
• Interface bonding of grains/steel was due to the new formed Ti-based compounds.
• Interface of steel/alloy exists as a cross-diffusion of iron and titanium.

Diamond, c-BN, Al2O3 and SiC abrasive crystals were brazed onto 0.45%C steel matrix using Cu–Sn–Ti active powder filler alloys in vacuum to develop a new superhard abrasive wheel. The brazing process was carried out in vacuum at the temperatures of 890 °C, 925 °C, and 960 °C for dwell durations from 10 to 30 min, respectively. The interface characteristics of the brazed joints between the abrasive grains and the filler alloys were investigated using optical microscope, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The results by microanalyses show that the element of Ti from the active powder filler was diffused preferentially to the surface of the grains, resulting in a Ti-rich reaction layer in the brazed joints. The microstructure phases of TiC, TiN, TiB, TiB2, TiO and TiSi2 in the grains/active filler interface and Cu–Ti in the active filler/steel interface were confirmed by XRD analysis. The joining of the grains to the 0.45%C steel was realized by the reaction products of Ti-based on the interface. The adhesive strength experiment of the joint interfaces was performed; the results suggest that the grains were not dislodged from the bond interface.