Effect of multilayer graphene addition on performance of brazed diamond drill bits with Ni–Cr alloy and its mechanism

Abstract

In the study, novel Ni–Cr composite alloys that feature multilayer graphene (MLG) attached relatively evenly on the surfaces of Ni–Cr alloy particles were developed and used to fabricate new brazed diamond drill bits. The microstructures of the new drill bits and brazed diamonds obtained from five diamond segments via etching were investigated. The machining performance of the drill bits was measured, and their wear forms were investigated. Microtopography of a new drill bit with a 1 wt% MLG addition was optimal. The new drill bit also exhibited the longest tool life, highest drilling efficiency, and mildest wear modes. Experiments indicated a significant decrease in corrosion pits of diamonds due to the adsorption of Ni atoms by MLG. The corrosion pits of diamonds were mainly due to Ni during brazing. Experiments also indicated a significant decrease in the formation of chromium carbide on surfaces of the diamonds due to the adsorption of Cr atoms by MLG. Excessive MLG led to a premature pull-out of diamond grits from the bonding alloy during the drilling process. The thermal damage to diamond grits during brazing was decreased by MLG.