Furnace Brazing of Diamond Grinding Wheel with Ni-Cr Alloy under Vacuum Atmosphere

The brazing of a monolayer diamond grinding wheel with active filler metals can show distinct advantages over conventional electroplated diamond grinding wheel in terms of faster cutting and longer life. The present study has shown that a commercially available Ni-Cr alloy can be used as an active filler material for brazing diamond grit. Furnace brazings carried out in a current of vacuum. SEM-EDS microanalyses have shown that during brazing the chromium present in the alloy segregated preferentially to the surface of the diamond to form a chromium-rich reaction product. X-ray diffraction reveals that the wetting and bonding behaviour on diamond surface by Ni-Cr alloy melt is realized through Cr₇C₃ which is produced by interaction between Cr atoms of Ni-Cr alloy and C atoms of diamond surface at elevated temperatures. The analyses also indicate that the bond between the alloy and the steel substrate is established through a cross-difusion of iron and chromium. Finally, a grinding test shows that the wear modes of such a brazed grinding wheel are mainly grit fracture and attrition rather than grit dislodgement from the bond.