Flash joining of metal-ceramic multi-layered sandwich structure

The present study uses Flash joining technique to join sandwiched Titanium (Ti) metal with two pre-sintered Titanium dioxide (TiO2) pellets. This method employs Direct Current (DC) to enable rapid diffusion across stacked layers, due to Joule heating, resulting in reliable and continuous interface of the sandwich structure. Joining was found to be more uniform and continuous at lower current density, with respect to that at higher current densities. However, current direction has a detrimental effect on the anodic interface in comparison to the cathodic interface, resulting in superior mechanical properties at cathodic interface. This differential joining behaviour can be attributed to concentration of oxygen vacancies at the anodic interface. X-ray Photoelectron Spectroscopy and Raman, indicating higher concentration of oxygen vacancies at anodic interface, support this notion. The study reveals the directional effect of the current on joining ceramics to metals to attain superior structural integrity for complex multi-layered sandwich structures.