关键词: 单层砂轮, 钎焊, 金刚石, Ni-Cr合金, 冶金结合

Abstract:

The brazing of a monolayer of diamond grinding wheel with active filler metals can show distinct advantages over conventional electroplated diamond grinding wheels 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 brazing was carried out in a current of argon. 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 revealed that the wetting and bonding behaviour on diamond surface by Ni-Cr alloy melt is realized through Cr ₃C₂ and 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 revealed that the bond between the alloy and the steel substrate was established through a cross-diffusion of iron and chromium and the formation of(Fe x Cr y )C-type carbides. Finally, a grinding test showed that the wear modes of such a brazed grinding wheel were mainly grit fracture and attrition rather than grit dislodgement from the bond.

Key words: mono layer abrasive w heels, brazing, diamond, N i-Cr alloy, metallurgical bonding