Influence of process parameters on joint properties of MgAl2O4 transparent ceramics using flash joining

Flash joining has been proven to a high-performance joining technology for MgAl2O4 transparent ceramics. To reveal the functions and effecting mechanism of electric field in the flash joining, the effects of E-field intensity, temperature, current density and joining time on the joints were systematically studied. The E-field intensity and temperature above a certain threshold were the preconditions for flash joining, while the current density and joining time had great influence on the joint performance. Combined with the finite element analysis (FEA) under thermal-electric field, the possible mechanism of flash joint formation was proposed. The contact impedance causes Joule-heat to accumulate near the joining interface, increasing the diffusion coefficient, and promoting the formation of Schottky defects. Under the action of direct current E-field, the defects migrate rapidly along the direction of E-field and promote the healing of the welding seam.