Reactive air wetting and brazing of Al2O3 ceramics using Ag–Nb2O5 filler: Performance and interfacial behavior

We firstly performed the reactive air wetting and brazing of Al2O3 ceramics using Ag–(0.5‒12)Nb2O5 fillers, where Nb2O5 can react with liquid Ag and O2 from air to generate AgNbO3. The contact angle of the Ag–Nb2O5/Al2O3 system almost linearly decreases from ~71.6° to 32.5° with the Nb2O5 content increasing, and the joint shear strength reaches the maximum of ~65.1 MPa while employing the Ag–4Nb2O5 filler, which are mainly related to the formation and distribution of the AgNbO3 phase at the interface. Moreover, the interfacial bonding and electronic properties of related interfaces were investigated by first-principles calculations. The calculated works of adhesion (Wa) of Ag(111)/Ag–O–AgNbO3(001) and AgNbO3(001)/Al2O3(100) interfaces are higher than that of the Ag(111)/Al2O3(110) interface, indicating good reliability of the Ag/AgNbO3/Al2O3 structure. The relatively large interfacial charge transfer indicates the formation of Ag–Ag, Al–O, and Ag–O bonds in the Ag/AgNbO3/Al2O3 structure, which can contribute to the interfacial bonding.