| Alumina and monel superalloy was successfully joined by active metal brazing
technique using Ticusil (68.8Ag-26.7Cu-4.5Ti in wt%) filler alloy in a vacuum furnace
at 910oC for 10 min under a vacuum of 5×10–6 Torr. Phase analysis of the monel-filler
alloy and alumina-filler alloy interfaces was conducted by X-ray diffraction analysis.
Interfacial and cross-sectional microstructural investigation and determination of
elemental composition were performed by scanning electron microscopy and energy
dispersive X-ray analysis. No crack was found at the joint interfaces after thermal
cycling test for 100 cycles between 50o and 600oC. Microhardness was estimated by
Vickers hardness tester at the cross-section of the joint after thermal cycling test.
Typical brazing strength of the thermally cycled joint was above 23 MPa. Helium
leak tests indicated good hermiticity of the thermally cycled brazed joints.
[Keywords: Al2O3-monel joint, Thermal cycling test, Microstructural study,
Microhardness, Brazing strength, Helium leak test] |
