|
1049 |
|
Tuesday, June 19, 2007, Brüssel 5:40 PM Diffusionsschweißen, Mikro- und Nanotechnologie, Korrosion und Korrosionsschutz, Integrierte Fertigung Diffusion bonding, micro- and nanotechnologies, corrosion and corrosion protection, integration of brazing into the production process |
|
Vacuum induction brazing for heterogeneous joining of tantalum to stainless steel
|
|
Celine Cossu* / CEA. Welding Laboratory, FRANCE Gilles PARADIS / CEA. Welding Laboratory, FRANCE Philippe NAUDY/ CEA. Welding Laboratory, FRANCE |
|
Tantalum is used in chemical industry due to its refractory and corrosion resistance properties. Because of its high cost, joining tantalum to stainless steel can be useful for less solicitated parts. As fusion welding is possible only using a filler metal, solid state joining is preferable for limiting structural deterioration. Brazing is a good compromise when using a suitable filler metal regarding corrosion resistance. The eutectic alloy Au/Ni (82/18 wt%) offers in addition good wettability and mechanical property. Its melting temperature is 955 °C. This communication presents the experimental procedure and metallurgical analysis of the brazes. Induction is prefered as a localized heat source with high dynamics. Vacuum brazing is required to protect tantalum against oxidation and enables simplified surfaces preparation. The braze matrix shows a refined lamellar structure favorable in terms of mechanical properties. Rapid heating limits the extension of reacting phenomena between filler alloy and base metals. Dispersed areas of Ni8Ta compound are localized near tantalum erosion zones. An additionnal phase rich in nickel is located at grains boundaries. |