The primary purpose of this work is to develop and demonstrate technologies to manufacture ultra-low-cost precision optical systems for very large x-ray, UV/optical, or infrared telescopes.
Starfire® RD-730 is a polycarbosilane precursor material that can be converted to a thermally stable silicon carbide by direct pyrolysis. RD-730 is a melt-processable polymer, meaning that it is a solid at room temperature, but can be melted to produce a viscous liquid polymer that can be flowed at temperatures to 100 °C. Using melt processing, T-300 cloth fabrics can be infiltrated with RD-730, which then solidifies and becomes a hard, machinable thermoplastic. T-300 cloth layups with RD-730 in the thermoplastic form will be the new prepreg material. The prepreg in block form can be machined to near-net shape, put in a mold, and re-flowed (re-melted). The molded parts can then be cured (curable above 150 °C) to render a thermoset, which is machinable. The cured polymer matrix composite can then be fired to form a high-temperature, oxidation-resistant, amorphous silicon carbide material.
A 12 × 12 × 0.5 in. (≈30 × 30 × 1.3 cm) vented, lightweight, H-SiC panel was developed that had a density relative to bulk silicon carbide of 11% (89% lightweighting). The H-SiC panel and facesheet stock material were fabricated into ASTM standard coupons and tested at SoRI to obtain basic materials properties data. The materials properties data showed a near-zero coefficient of thermal expansion [CTE, from –320 to +75 °F (≈ –196 to 24 °C) is –0.22 ppm/°C] ceramic matrix composite (CMC) C/SiC material with good strength.