Effect of CNTs on Microstructure and Properties of Ag-Cu-Ti Filler Metal

Ag-Cu-Ti alloy can be used as active filler metal to achieve metal-ceramic bonding. Carbon nanotubes (CNTs) were selected as the additive material and Ag-26.7Cu-4.5Ti was used as the matrix material. The effect of CNTs content on the microstructure and properties of Ag-Cu-Ti filler metal was investigated. The results indicate that CNTs can reduce the wetting spreading area of filler metal on the surface of steel substrate, and increase the melting temperature by similar to 9 degrees C, and obviously increase the shear strength of brazed joint. When the content of CNTs is 0.2%, the shear strength reaches the maximum value, and the increase range is 49.3%. Moreover, SEM analysis indicates that the addition of CNTs can refine the microstructure of filler metal, but excessive CNTs would coarsen the microstructure of Ag-Cu-Ti. For the fracture morphologies of Ag-Cu-Ti-xCNTs (x=0, 0.05, 0.1, 0.2, 0.5, 1.0, wt%) brazed joints, obvious ductile fracture mode can be observed on the fracture surface of Ag-Cu-Ti-xCNTs (x=0.05, 0.1, 0.2, 0.5) brazed joints. However, the fracture mechanism of Ag-Cu-Ti and Ag-Cu-Ti-1.0CNTs brazed joints shows obvious mixed fracture mode.