Effect of Ti Content on Microstructure and Mechanical Properties of Si3N4/Si3N4 Joints Brazed with Ag-Cu-Ti plus Mo Composite Filler

Mo particles have been introduced into Ag-Cu-Ti brazing alloy for the joining of Si(3)N(4) ceramic. Effects of Ti content on microstructure and mechanical properties of the joints were investigated. The results present that a compact reaction layer which is composed of TiN and Ti(5)Si(3) was formed at the Si(3)N(4)/solder interface. The central part of the joint was composed of Ag based solid solution, Cu based solid solution, Mo particles and Cu-Ti intermetallics. By increasing Ti content in the composite filler, both the thickness of reaction layer and the amount of Cu-Ti intermetallics in the joint increased, which is beneficial for the joint strength. However, the reaction between Ti and Si(3)N(4) proceeded more excessively. Simultaneously, more Cu-Ti intermetallics were precipitated while elevating Ti content to 6wt.%, leading to deterioration of the bonding strength. The maximum bending strength (429.4MPa) was obtained when Ti content is 4wt.% in the composite filler.