Homogenous seamless joint of SiC ceramics driven by mechanically constrained expansion-induced stress (MCES)

In this work, the internal stress induced by the self-thermal expansion of the ceramic matrix was utilized, instead of external pressure, to drive the densification of the ceramic joint. The theoretical results indicate that a large axial compressive stress (on the GPa order) is generated at the joint interface under constrained expansion. The microstructure and joining performance of the homogeneous interlayer under constrained expansion-induced stress were investigated via experiments, and the joining mechanism driven by this stress was explored. Under constrained conditions, the induced compressive stress facilitates the diffusion of Si-C and mass transfer processes, which results in the formation of a fully dense interlayer. The joining process comprises two stages: internal stress-driven interlayer densification and epitaxial grain growth at the joining interface. The joint strength reaches 359 ± 39 MPa, with a Weibull modulus of 10.9. The proposed technique was successfully adopted for joining Al 2 O 3 ceramics, indicating its broad applicability.