Development of dual-fiber-reinforced glass-matrix composites for structural space-based applications. Final report, 14 March 1988-14 March 1990

The goal of the program was to create high specific stiffness, zero thermal composites for structural applications in space by using dual fiber reinforcement approach. This approach consisted of adding large-diameter monofilaments as a secondary reinforcement to a pitch-based carbon fiber reinforces glass matrix composite. It was demonstrated that composite thermal expansion could be increased into the near-zero domain over the temperature range of interest (-100 C to +70 C) using a wide variety of monofilaments with and without fiber coatings. The use of uncoated boron monofilaments resulted in rather poor tensile performance and brittle fracture behavior due to degradation of the boron monofilaments during composite processing. The use of coated monofilaments resulted in a marked improvement in tensile strength and fracture behavior.