Interfacial Microstructure and Formation Mechanism of Zirconia Ceramic and Nb Brazed with Ag-Cu-Ti Powder without and with Mo-Particle-Reinforced

Abstract

Zirconia (ZrO2) ceramic and Nb were brazed using Ag-Cu-Ti powder without and with Mo-particle-reinforced. The effects of the brazing temperature, holding time and Mo content of the composite filler on the interfacial microstructures and joining mechanism of ZrO2/Nb brazed joints were investigated. By increasing the brazing temperature and holding time, the thickness of Ti3Cu3O layer increased and the thickness of TiO layer decreased, while the total thickness of the reaction layers increased slightly with the sufficient interfacial reaction. Meanwhile, the blocky Ti-Cu compounds gradually accumulate and grow up in the brazing seam. The calculated Ti activity increased first and then decreased as the Mo content was increased from 5 to 40 wt%. When the Mo content was 5wt%, only single Ti3Cu3O reaction layers formed adjacent to the ceramic substrate. By increasing of Mo particles, TiO layer became thicker. When 40 wt% Mo particles were added to the composite filler, Mo particles aggregated into larger clumps damaged the shear strength of brazing joint.