Feasibility of ceramic joining with high energy electron beams

Joining structural ceramics is possible using high melting point metals such as Mo and Pt that are heated with a high energy electron beam, with the potential for producing joints with high temperature capability. A 10 MeV electron beam can penetrate through 1 cm of ceramic, offering the possibility of buried interface joining. Because of transient heating and the lower heat capacity of the metal relative to the ceramic, a pulsed high power beam has the potential for melting the metal without decomposing or melting the adjacent ceramic. The authors have demonstrated the feasibility of the process with a series of 10 MeV, 1 kW electron beam experiments. Shear strengths up to 28 NTa have been measured for Si3N4-Mo-Si3N4. These modest strengths are due to beam non-uniformity and the limited area of bonding. The bonding mechanism appears to be a thin silicide reaction layer. Si3N4-Si3N4 joints with no metal layer were also produced, apparently bonded an yttrium apatite grain boundary phase