STRONG, SMALL DIAMETER, BORON FIBERS BY LCVD

Law assisted chemical vapor deposition (LCVD), whereby the laser beam has a focal point adjusted to coincide with the tip of a growing fiber, is a new process capable of forming continuous, small diameter inorganic fibers. This paper highlights the boron process and the properties of the resulting boron fibers. They were up to 2 m long, substrate-free and X-ray amorphous, and had diameters < 25-mu-m and tensile strengths of 5.2-7.6 GPa. Their average specific strength closely approaches that of single-crystal SiC whiskers made by the discontinuous VLS process. In summary, the properties are among the highest reported thus far for any advanced inorganic fiber.