Thermal cycling behavior of alumina-graphite brazed joints in electron tube applications
(1. Central Glass & Ceramic Research Institute, Council of Scientific and Industrial Research, Kolkata 700032, India;
2. Department of Physics, Bengal Engineering & Science University, Howrah 711103, India;
3. Institute for Plasma Research, Gandhinagar 302428, India)
2. Department of Physics, Bengal Engineering & Science University, Howrah 711103, India;
3. Institute for Plasma Research, Gandhinagar 302428, India)
Abstract: Alumina was joined with graphite by active metal brazing technique at 895, 900, 905, and 910 °C for 10 min in vacuum of 0.67 mPa using Ti-Cu-Ag (68.8Ag-26.7Cu-4.5Ti; mass fraction, %) as filler material. The brazed samples were thermal cycled between 30 and 600 °C and characterized. X-ray diffraction results show strong reaction between titanium and carbon as well as titanium and alumina. Scanning electron microscopy and helium leak tests show that the initial and thermal cycled brazed samples are devoid of cracks or any other defects and hermeticity in nature. Brazing strength of the joints is found to be satisfactory.
Key words: brazed joints; thermal cycling; brazing strength; hermeticity