Microstructure and Properties of SiC Ceramic Joint Actively Brazed with SiC_p Reinforced Composite Brazing Alloy Tape

SiC_p reinforced Ag-Cu-Ti (SiC_p/Ag-Cu-Ti) composite brazing alloy tapes with 10vol%-40vol% SiC_p were fabricated by tape casting technique, and then the SiC ceramics were brazed with the sandwich structure of Ag-Cu-Ti alloy foil/(SiC_p/Ag-Cu-Ti composite brazing alloy tape)/Ag-Cu-Ti alloy foil. The microstructure and micro area composition of the brazed joint were studied, and the flexural strength at room temperature and elevated temperature were measured. The results show that the SiC_p, which was coated by a layer of reaction product with thicknesses of 0.6-0.8 μm, distributed uniformly in the braze metal. The SiC ceramics were tightly bonded to the braze metal. An interface reaction layer composed of TiC and Ti₅Si₃ with thicknesses of 0.75-0.90 μm was formed between the SiC ceramics and the braze metal. With the increase of SiC_p content in the composite brazing alloy tape, the flexural strength at room temperature of the joint decreased slightly and then increased, and reached the maximum value of 301 MPa when the SiC_p content was 40vol%. In addition, the high-temperature flexural strength at 600℃ reached 193 MPa, which was obviously higher than that of ordinary brazed joints without SiC_p reinforcement.