부산대학교 도서관

Results of work directed to production of B spheres are reported. The stockpile boron supplied by LRL was processed through the Institute's plasma spheroidizer in suitable particle-size fractions. Physical properties were altered in all sizes, although complete spheroidization of individual particles appeared only at 200 mesh (74 $mu$) and below. The products from the spheroidizer were characterized with respect to their particle size, sphere content, packing density, and surface area. An average sphere content of 50 to 60 percent (particle-count technique) was obtained for size fractions below 200 mesh. By mixing portions of the various particle-size products from initial tests to represent the composition of the bulk sample, packing densities as high as 1.54 g/cm$sup 3$ were achieved, but in the practical processing of the bulk sample, a final mixture with a packing density of 1.37 g/cm$sup 3$ was obtained. This was a 26.9 percent increase over the as-received material which had a density of 1.08 g/cm$sup 3$. This final mixture (400 g) was submitted to LRL. Surface area for the bulk material was reduced from 8.55 to 3.14 m$sup 2$/g. The flowability of the stockpile material was greatly improved, and with the parameters developed under the present program, a 30 percent increase in deposition efficiency can be expected in plasma-sprayed boron coatings as compared with the values obtained in the initial portion of this program. (auth)