Investigation of Elongation and Its Relationship to Residual Stresses in Boron Filaments.
Abstract
Elongation in boron filament during fabrication was investigated and found to be as great as 16% under certain conditions. It was also found to obey a relatively simple empirical relationship which yielded effective activation energies. A model for the elongation was proposed, and a computer program was designed to simulate the deposition and elongation of boron on a tungsten wire substrate. Internal residual stress distribution of boron/tungsten filament were also generated by the computer program. Good agreement was found between the proposed model and experimental results. Negative elongation (contraction) of boron filament was observed during annealing and found to be dependent upon the concentration of oxygen present in the annealing atmosphere. The contraction was also found to be the result of void formation at the core-boron sheath interface. The contraction obeyed an empirical relationship, which represented an exponential decay toward equilibrium from a non-equilibrium state and an effective activation energy was determined for boron/tungsten filament. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1979
- Accession Number
- ADA074440
Entities
People
- Franklin E. Wawner Jr.
- J. W. Eason
- Robert A. Johnson
Organizations
- University of Virginia