Abstract
Since the advent of high-strength, high modulus, low-density boron fiber, the role of fibers produced by chemical vapor deposition (CVD) in the field of high-performance composites has been well established. Although best known for its use as a reinforcement in resin-matrix composites, boron fiber has also received considerable attention in the field of metal matrix composites. Boron/aluminum was employed for tube-shaped truss members to reinforce the Space Shuttle orbiter structure, and has been investigated as a fan blade material for turbofan jet engines. There are drawbacks, however, in the use of boron in a metal matrix. The rapid reaction of boron fiber with molten aluminum and long-term degradation of the mechanical properties of diffusion-bonded boron /aluminum at temperatures greater than 480°C (900°F) preclude its use both for high-temperature applications and for potentially more economically feasible fabrication methods such as casting or low-pressure, high-temperature pressing. These drawbacks have led to the development of the silicon carbide (SiC) fiber.
