Effect of ZnO on the interfacial bonding between Na 2O–B 2O 3–SiO 2 vitrified bond and diamond

Abstract

Diamond composites were prepared by sintering diamond grains with low melting Na 2O–B 2O 3–SiO 2 vitrified bonds in air. The influence of ZnO on the wettability and flowing ability of Na 2O–B 2O 3–SiO 2 vitrified bonds was characterized by wetting angle, the interfacial bonding states between diamond grains and the vitrified bonds were observed by scanning electron microscope (SEM), and the micro-scale bonding mechanism in the interfaces was investigated by means of energy-dispersive spectrometer (EDS), Fourier transform infrared (FTIR) spectrometer and X-ray photoelectron spectroscopy (XPS). The experimental results showed that ZnO facilitated the dissociation of boron/silicon–oxygen polyhedra and the formation of larger amount of non-bridging oxygen in the glass network, which resulted in the increase of the vitrified bonds' wettability and the formation of –C O, –O–H and –C–H bonds on the surface of diamond grains. B and Si diffused from the vitrified bonds to the interface, and C–C, C–O, C O and C–B bond formed on the surface of sintered diamond grains during sintering process, by which the interfacial bonding between diamond grains and the vitrified bonds was strengthened.