Refractory metal coating‐assisted SiC brazing: Microstructure, strength, and molten salt corrosion test

Abstract Silicon carbide (SiC) ceramics are promising for molten salt reactor (MSR) applications, but their poor machinability necessitates reliable joining technologies. This study investigates SiC joining using pure Ag filler combined with magnetron‐sputtered refractory metal coatings (W, Mo, and Ti). All joints achieved sound metallurgical bonding: Ti coating reacted completely with SiC to form TiC and Ti 5 Si 3 ; W coating partially reacted to generate W 2 C, WC, and minor W 5 Si 3 with residual W; and Mo coating reacted to form Mo 2 C and MoSi 2 with remaining Mo. Corrosion tests conducted in FLiNaK molten salt at 700°C for 100 h showed that Mo/Ag joints exhibited the best resistance with a corrosion depth of approximately 8.62 µm, followed by W/Ag joints at 56.75 µm while Ti/Ag joints suffered complete failure. The shear strengths were measured as 103.10 ± 6.86 MPa for Ti/Ag, 95.39 ± 7.48 MPa for W/Ag, and 59.17 ± 8.60 MPa for Mo/Ag brazed SiC joints. The Mo/Ag brazing system shows promise for SiC joining in MSR environments, with potential for further optimization.