Evaluation of Au-Based Active Brazing Filler Metals to Joint Alumina

Gold-based active brazing filler metals were developed and tested on 97.6% Alumina. Five Au-based alloy systems were selected for the present study. They are pure Au, AuNi (82%Au and 18%Ni), AuCuNi (35%Au, 62%Cu, and 3%Ni), AuPdNi (50%Au, 25%Pd and 25%Ni), and AuPd (92%Au and 8%Pd). It was discovered that titanium and/or vanadium are effective active elements depending on the alloy system. It was also discovered that there is an optimum brazing temperature for achieving complete wetting.  When brazed at higher than the optimum temperature, certain brazing filler metals showed dewetting phenomena.  With the alloys that shown good wettability behavior further studies were conducted to determinate their ability to attain hermetic ceramic-to-ceramic and ceramic-to-metal brazed joints.