On Improved Bonding of Tic-Coated CBN Grits in Nickel-Based Matrix

Summary The present work has shown that galvanically bonded CBN abrasive tools, particularly those with monocrystalline CBN particles having relatively smooth surface may suffer from large grit pull out during grinding. This investigation has further revealed that strong and durable Ni-Cr alloys, which are known to braze uncoated diamond grits very effectively, providing superior bond than galvanic one, however, failed to wet uncoated CRN crystals during brazing. Thus, in order to activate Ni-Cr alloys, surface modification of CBN grits was found to be essential. To achieve this, a new process has been developed, wherein the CBN particles were coated with a strongly adherent film of TIC by conventional CVD. Such surface modification significantly improved retention of CBN grits in NI-based matrix.