| Brazing of ceramics and metals was widely used in aerospace,electronics industry and fuel cells.Brazing in the air,compared with brazing in the vacuum,can not only reduce the cost but also be used in large-scale work, as well as enlarge its application.Twelve kinds of compositions of the CuO-Ag alloys were investigated in this study. The microstructure,phase and microharness of brazed joint were analyzed by metallographic examination(Optical microscope, Scan Electron microscope,Energy Dispersive X-ray Detector,X-ray Diffraction,Microhardness tester).Meanwhile,the best filler metal was selected .In order to select the best technological parameter,the 34mol% CuO-content filler metals was was investigated.The result indicated that the addition of CuO substantially improves the wetting of Zirconia ceramic substrates by silver in the air.In the interface of brazing joint ,there was a black transition.The layer was considered CuO and Ag by XRD and EDS.The joint was effected by the CuO-content of filler metal.When the CuO-content of filler metal was 34mol%,the microstructures and constituents were homogenous,the distribution and the solution of elements were best,the distribution distance of Cu and Ag was 50μm and the interface zone was the best widest.The solution of zirconium to brazing seam wasn't effected by the CuO-content of filler metals.When the CuO-content of filler metal was 34 mol%,the microhardness distribution of brazing joint was gentle .When the CuO-content of filler metal is 34mol%,brazing in the air in 1100°C,holding 15 minutes,there wasn't deficiency in the brazing joint and the interfacial joining is perfect. In 1100°C,when the CuO-content of fliller metal is 34mol%,the spreadabity is best.The spreadabity of filler metals on Aluminum oxide ceramic is better than on Zirconia ceramic.
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