Interfacial microstructure and mechanical property of brazed copper/SiO2 ceramic joint.

Vacuum brazing of copper to SiO 2 electroceramics was carried out using commercially obtained Ag-Cu-Ti filler alloy. The effects of brazing temperature and bonding time on the interfacial microstructure and mechanical properties were investigated. The microstructure observation revealed that the typical interfacial structure could be expressed as SiO 2 ceramic/Ti 5 Si 3 + Ti 4 O 7 /Ti 2 Cu + Ti 3 Cu 3 O/Ag (s,s) + Cu (s,s)/Copper. The migration of Ti in brazing seam, which promoted the reaction of Ti with the SiO 2 ceramic, was a positive factor on the interfacial microstructure and mechanical properties. With increased the brazing temperature or holding time, the thickness of Ti 5 Si 3 + Ti 4 O 7 reaction layer thickened, meanwhile, the amount of AgCu eutectic structure decreased. The shear strength firstly increased and then decreased with brazing temperature increasing or bonding time prolonging. The maximum shear strength of 22 MPa was obtained at 850 °C for 5 min. Its fracture occurred both along the ceramic substrate adjacent to the bonding interface and along the reaction layer, showing a mixture fracture mode. [ABSTRACT FROM AUTHOR]