Investigation of microstructure and mechanical property of Li-Ti ferrite/Bi2O3-B2O3-SiO2 glass/Li-Ti ferrite joints reinforced by FeBi5Ti3O15 whiskers

The Bi2O3-B2O3-SiO2 glass solder was used to join the Li-Ti ferrite. SEM micrographs of the joints showed the formation of FeBi5Ti3O15 whiskers at the interface. The formation mechanism was that the elements Fe and Ti reacted with [BiO6] units and came out as needle-like FeBi5Ti3O15 whiskers during cooling when the Ti content in the seam reached the critical concentration of crystallization. The quantity and morphology of the FeBi5Ti3O15 whiskers could be controlled by adjusting the bonding temperature and applied pressure, which could decide the Ti content in the seam. The deciduous ferrite ceramic particles were observed at the interface due to the formation of the FeBi5Ti3O15 whiskers continually consumed the elements Fe and Ti. Under the combined influence of the elements diffusion and interfacial reactions, nearly defect-free joints were obtained and a maximum in the shear strength of 92 MPa was achieved at 750 °C for 30 min under 100 Pa applied pressure.