High-performance flash joining of MgAl2O4 transparent ceramics

The MgAl2O4 transparent ceramic was firstly flash joined in 3 min at 1500 degrees C by applying direct current (DC) electric field. Three-point flexural strength of the joints reached approximately 256.0 MPa, which was even 114.7% of that of the parent material. Compared with parent transparent ceramics, transmittance loss of the MgAl2O4/MgAl2O4 joints in band of visual light and mid-infrared was only 1.5% and 4.5%, respectively. A possible mechanism of flash joining was proposed. The applied DC electric field induces numerous charged defects in the sample and superplastic deformation of the ceramic. The defects generated at the pores of the joining interface migrate directionally under the action of the DC electric field, which accelerates the diffusion rate of substances and enables the samples to be quickly jointed at a lower temperature.