Microstructure and performance of diamond abrasive grains brazed in mesh belt furnace with ammonia dissociating atmosphere

• New process of brazing diamond grits applied for mass production was developed.
• Joining interface of brazed diamond in mesh belt furnace was investigated.
• Good performance of brazed diamond in mesh belt furnace was obtained.

In order to achieve the mass production of the brazing diamond tools, brazing of diamond grains to the matrix using NiCr active filler alloy was investigated in the mesh belt furnace, which could realize uninterrupted brazing under ammonia dissociating atmosphere. The surface characteristics and interfacial microstructures of brazed diamond in mesh belt furnace were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The residual stress, static compressive strength and impact toughness of the brazing diamond were measured and the corresponding results were compared to the brazing diamond grains in vacuum furnace. Results demonstrated that chemical reaction occurred between the diamond and filler alloy. The compound composed of Cr3C2 and Cr7C3 was formed at diamond interface and a higher bonding strength was obtained. The residual stresses of brazing diamond in mesh belt furnace were lower than that in vacuum furnace in the case of identical protruding height. However the static compressive strength and the impact toughness were higher than that in vacuum furnace.