Flash brazing of SiC via electric field assistance using BNi-2: Microstructure and high-temperature properties

In this paper, the “flash brazing” of SiC is successfully achieved using BNi-2 alloy in air for seconds. The interface temperature reaches approximately 1234 °C at an ultra-fast rate via the electric field assistance. The microstructure illustrates that SiC reacted with Ni from the BNi-2 filler alloy, producing amorphous carbon and Ni₂Si. The aggregation of Cr, Fe, C, and B elements can be observed in the center of flash brazing seam. The typical microstructure of the joint is SiC/C + Ni₂Si/Cr₂₃C₆+Cr_1.65Fe_0.35B_0.96+Ni₂Si/C + Ni₂Si/SiC. To release the strength of SiC joints, the multilayer filler (BNi-2/Ni foam/BNi-2) is designed. The joint strength reaches the maximum of 62 MPa at room temperature, which is 44 % higher than that of the joint obtained using BNi-2 alloy. Additionally, the maximum strength value is 100 MPa at 800 °C. The result shows that the mechanical properties of SiC joints are improved and the joint has excellent high-temperature mechanical properties.