Interfacial Microstructure and Properties of In-situ TiB Reinforced ZrB2-SiC Joints

Abstract:

The ZrB2-SiC ceramics were joined to themselves using Ag-Cu eutectic/Ti lamination as interlayer. The SEM and EDS analyses demonstrate that ZrB2 could react with Ti in brazing alloy to form an in situ TiB whisker array with preferred orientation. The typical microstructure of the joint is ZS/TiB(Ag(s,s))/TiCu(AgCu4Zr)/Ag(s,s)/TiCu(AgCu4Zr)/TiB(Ag(s,s))/ZS. The microstructural evolution at various brazing temperatures was investigated. It is revealed that the ZrB2 decomposing temperature is 860 oC and TiB formation temperature is 880 oC. The maximum shear strength of 134 MPa is obtained when joining at 900 oC for 10 min. The high strength mainly benefits from stress accommodation by TiB and gradient transition from the ceramic to the seam center.