Low-temperature pressure-less joining of SiCf/SiC via NITE sintering: Mechanical performance and steam oxidation resistance

Developing a pressure-less joining process operable at tolerable temperatures is crucial for practical engineering deployment of SiC f /SiC thin-walled cladding tubes. Hereby, we invented a low-temperature pressure-less Nano-Infiltration and Transient Eutectic (NITE) joining method for SiC f /SiC composites using Al 2 O 3 and Y 2 O 3 sintering additives, achieving successful bonding at 1600 ℃ for 2.5 h without interfacial debonding. The joint microstructure consisted of SiC with finely distributed Y 3 Al 5 O 12 intergranular phase, exhibiting excellent integrity and mechanical performance (shear strength of 46.7 ± 2.7 MPa). After 8 h steam oxidation at 1200 ℃, joints retained 77.9 % strength (36.4 ± 6.8 MPa) through protective SiO 2 /AlOOH layers and Y-silicate transformations. Successful SiC f /SiC cladding tube encapsulation demonstrated technical feasibility, with XCT revealing robust bonding despite minor inner-wall densification issues. This work establishes NITE as a viable solution for nuclear applications, combining favorable processing conditions with superior joint performance.