Boron fiber or boron filament is an amorphous product which represents the major industrial use of elemental boron. Boron fiber manifests a combination of high strength and high elastic modulus.
A common use of boron fibers is in the construction of high tensile strength tapes. Boron fiber use results in high-strength, lightweight materials that are used chiefly for advanced aerospace structures as a component of composite materials, as well as limited production consumer and sporting goods such as golf clubs and fishing rods.[1] [2]
One of the uses of boron fiber composites was the horizontal tail surfaces of the F-14 Tomcat fighter. This was done because carbon fiber composites were not then developed to the point they could be used, as they were in many subsequent aircraft designs.[3]
In the production process, elemental boron is deposited on an even tungsten wire substrate which produces diameters of 4.0 mil (102 micron) and 5.6 mil (142 micron). It consists of a fully borided tungsten core with amorphous boron.[4] [5] [6]
Boron fibers and sub-millimeter sized crystalline boron springs are produced by laser-assisted chemical vapor deposition. Translation of the focused laser beam allows to produce even complex helical structures. Such structures show good mechanical properties (elastic modulus 450 GPa, fracture strain 3.7%, fracture stress 17 GPa) and can be applied as reinforcement of ceramics or in micromechanical systems.[7]