RESEARCH STUDY OF DIFFUSION BONDING OF REFRACTORY MATERIALS, COLUMBIUM AND TANTALUM.
Abstract
The bonding of columbium and tantalum to themselves and to each other was observed under conditions of temperature, pressure, and presence of filler metal, wherein the controlling process is predominantly diffusion-controlled, as distinguished from pressure bonding, yield stress-controlled bonding, or creep-controlled bonding. For example, at 2000 psi and 419C.,--a pressure well below the yield point of the parent metals and a temperature below their recrystallization points--all three combinations of parent metals could produce good lap-bonds with aluminum foil in 1/2 hr. At the same condition no bonds were obtained without foil in two hours. Butt-bonded joints under the same conditions exhibited tensile strengths of 12,000 psi for columbium and 19,850 psi for tantalum, with relatively poor joint efficiency as noted after rupture by the relatively small fraction of available contact areas. Results were obtained well below the observed recrystallization temperatures (600C. for columbium, and 800C. for tantalum). Evidence of oxidation was correlated with interference with bonding efficiency. It is believed that stricter atmosphere control and surface cleanliness related thereto could improve the joint strength and bond efficiency, even without reference to optimization of other process parameters. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 10, 1967
- Accession Number
- AD0663846
Entities
People
- C. Gonzales
- P. Keusch
- S. Korman
- V. Agostino