Flash joining of conductive ceramics in a few seconds by flash spark plasma sintering

The feasibility of conductive ceramics flash joining using spark plasma sintering is demonstrated. It is shown that graphite disks can be joined in a few seconds (6 – 10 s electric discharge time) using a SiOC precursor (methyl silicone resin) as an interlayer. Differently from usual flash experiments, the process does not require any pre-heating, allowing a dramatic reduction of the processing time. XPS analysis of the joint revealed a clear evolution of the chemical environment of silicon with a progressive transition from SiOC to SiO2/SiC. Mechanical tests were performed to determine the fracture toughness (1.0 ±0.2 MPa m0.5 ) and fracture energy (40.6 ± 9.8 J/m2) of the interface. Flash joining can be applied beyond graphite joining, and opens a novel and flexible processing route for many conductive ceramics, as demonstrate by preliminary work on Kanthal® Super MoSi2 and Cf-reinforced SiC.