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

Abstract

Mo particles have been introduced into Ag-Cu-Ti brazing alloy for the joining of Si3N4 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 Ti5Si3 was formed at the Si3N4/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 Si3N4 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.

Production, Characterization, and Mechanical Evaluation of Dissimilar Metal/Ceramic Joints

“…Many commercially available brazing alloys meet the main mechanical requirement of metal/ceramic joints, in which the more frequently used braze includes a Cu-Zn based alloy. Addition of small quantities of Ti increases the ceramic wettability and reactivity by diffusion of Ti across the interface (Zhang & He, 2010;Zou et al, 2009 ). The Figure 8 shows a cross-section interface of diffusion bonding Si 3 N 4 /Cu/Ti combinations joined at temperature of 980°C.…”