Boron carbide-graphite nuclear control-rod materials containing up to 45 wt% B were prepared by hot-pressing techniques. The densities of these compacts decreased with increasing B content. Compact strengths, however, were noticeably increased with B content of 20 wt%, suggesting that the B acts as a sintering aid. Thermal stability was evaluated by annealing compacts under a variety of temperature and atmospheric conditions. The upper limit of the ioss of 13 was 5% to 10%~ in 200 hr at 2000 deg C--considerably less than would be predicted from the Langmuir evaporation equation. Diffusion of B atoms through the pores of the …
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General Atomic Div., General Dynamics Corp., San Diego, Calif.
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San Diego, California
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Boron carbide-graphite nuclear control-rod materials containing up to 45 wt% B were prepared by hot-pressing techniques. The densities of these compacts decreased with increasing B content. Compact strengths, however, were noticeably increased with B content of 20 wt%, suggesting that the B acts as a sintering aid. Thermal stability was evaluated by annealing compacts under a variety of temperature and atmospheric conditions. The upper limit of the ioss of 13 was 5% to 10%~ in 200 hr at 2000 deg C--considerably less than would be predicted from the Langmuir evaporation equation. Diffusion of B atoms through the pores of the graphite, rather than evaporation from the surface, was found to be the rate- controlling step in the loss of B. Compacts containing 20, 30, and 40 wt% B were irradiated at 350 and 700 deg C to 1.0 and 2 4 x 10/sup 21/ nvt(fast). Physical integrity of the compacts was good after irradiation. Slight increases in tensile strength were noted in several instances. (auth)
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Goeddel, W. V.; Lonsdale, H. K. & Meyer, R. A.Boron Carbide-Graphite Nuclear Control-Rod Material: Preparation, Thermal Stability, and Irradiation Evaluation,
report,
April 24, 1962;
San Diego, California.
(https://digital.library.unt.edu/ark:/67531/metadc1032907/:
accessed March 20, 2025),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.
