The wettability of Y_2O_3-zirconia by fillers of Ag-Cu-Ti, Cu-Ag-Ti, In-Ag-Cu-Ti, Ag-Cu-Sn(In)-Ti, Ag-Cu-Ti-Zr, Ag-Cu-Zr, Cu-Sn-Ti, Cu-Ti, Cu-Zr and Cu-Ti-Ac-V has been investigated using sessile drop tests conducted in vacuum at 700-1000 ℃. The brazing interfaces of HT28-48 to zirconia ceramics using fillers of Ag-Cu-Ti, Cu-Ag-Ti, Ag-Cu-Ti-Zr and Cu-Sn-Ti and that of HT25-47 to zirconia ceramics using fillers of In-Ag-Cu-Ti were investigated by SEM, EPMA and X-ray diffraction techniques. The flexual strengths of HT25-47 to zirconia ceramics joints were evaluated by four points test. Substantial additions of tatinium are proved to induce fillers to wet zirconia due to the formation of a titanium rich raction products at the filler/ceramic interface. And these products were formed through the initial oxidition-reduction rection between fillers and the ceramic and the substantial diffussional rections of titanium and oxygen. It was found that titanium segeregate with other elements such as copper and indium, but not silver. It is suggested that titanium act through some active units such as CuTi_2 (in Ag-Cu-Ti fillers) and In_4Ti_3 (in In-Ag-Cu-Ti fillers). And the interfaces of filler/zirconia can be divided into a titanium diffusional rection layer which was compounded with TiOX(such as Ti_2O, TiO, TI_2O_3, Ti_3O_5 and TiO_2) and an oxygen diffusional rection layer which was compounded with active unite oxides (such as Cu_2ti_4O when using Ag-Cu-Ti fillers and In_2 tiO_5 when using In-Ag-Cu-ti fillers). The present work has shown the wettability can be improved by the additions of silver, indium and small amounts of tin. Additions of small amounts of tin are very benificial, but it is harmful to wetting due to the formation of Sn-Ti intermediate phase when its concentration is high. The most suitable titanium concentration for fillers of Ag-Cu-Ti for cast iron to zirconia brazing has been known. And the flexual strength of HT25-47 to zirconia using this filler can be as high as 257MPa.
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