1996 Volume 14 Issue 3 Pages 563-569
Synthetic ruby has been brazed to molybdenum rod using Ag-Cu eutectic filler including active metal of 1-8 mass%Ti, in order to investigate on the relation between the brazing condition and the bonding strength.
The strength of the joint was evaluated by tensile test and the brazing interface was examined by SEM and EPMA.
According to the tensile test, bonding strength of the joint brazed with 1 mass%Ti-Ag.Cu was less than 20 MPa independent on bonding temperature. Anotherside, bonding strength of the joint brazed at 1123 K-1173 K using 2-8 mass% Ti-Ag.Cu, was more than 100 MPa, and above 1223 K, it was reducing with raising of brazing temperature. Especialy the bonding strength of joint brazed at 1223 K using 8 mass%Ti-Ag.Cu showed remarkable reduction.
The examination of brazing interface by SEM and EPMA showed that ruby was corroded by brazing filler and reaction layer composed by Ti, Cu, Al and 0 was formed at bonding interface. According to the corrosion test, raising the brazing temperature and increasing the Ti content in the brazing filler hasten the corrosion of ruby.
Wiht advancing of ruby corrosin, Al and O made from corroded ruby diffused into the reaction layer and the content of these elements increased in this area. These experimental results showed that bonding strength of joint was reducing with advancing of ruby corrosion at brazing interface.
This suggests that advancing of ruby corrosion at bonding interface brings the brittleness of reaction layer and the bonding strength is reducing.
Anotherside, the preferential movement of Ti to bonding interface was hasten with advancing of ruby corrosion and it was assumed that the movement of Ti to bonding interface was concern to ruby corrosion.