Interfacial microstructure and mechanical properties of SiC joints achieved by reactive air brazing using Ag-V2O5 filler

SiC ceramics are successfully brazed via reactive air brazing using Ag-V₂O₅ fillers. The wettability of SiC ceramics by Ag-V₂O₅ fillers is investigated. Interfacial microstructure of SiC joints is analyzed by scanning electron microscopy and transmission electron microscopy with energy dispersive spectroscopy. Effect of the brazing filler composition on the microstructure and mechanical properties of SiC joints is studied in detail. The V₂O₅ from the brazing fillers is found to react intensively with SiC, and the SiO₂ reaction layer with the thickness of ?7 μm is formed on the SiC surface which ensures a good wetting of the brazing filler on SiC ceramics. The brazing seam is composed of Ag and VO₂ with small amount of remaining V₂O₅. The maximum shear strength (?58 MPa) is achieved when using the optimized brazing process (Ag-8V₂O₅, 1050 ℃/30 min, the loading pressure is ?20 kPa and the cooling rate is 2 ℃/min).