High precision composite pipes for SOLAR-B optical structures

The authors have been developing new high thermal conductivity and low mois ture absorption composite pipes for high precision space optics application s on the Japanese Institute of Space and Astronautical Science (ISAS) SOLAR -B satellite. Pitch based K13C (Mitsubishi Chemical) high modulus and high conductivity g raphite fiber, and EX1515 (Bryte Technology) low moisture absorption cyanat e resin, were applied to the pipes. Thermal expansion of the composite pipes was designed to be zero and more u niform in the longitudinal direction in order to obtain long term dimension al stability in the space environment. Model pipes whose length was 500 mm were fabricated and evaluated for therm al and hygroscopic deformation in a new testing apparatus. Equivalent coeff icient of thermal expansion of the model pipes was essentially zero (less t han 0.1 ppm/degreesC) and standard deviation of these coefficients was 0.05 ppm/degreesC. Hygroscopic deformation of the model pipes was under represe ntative conditions 7 ppm over 3 month. The excellent thermal and hygroscopi c stability were verified. In addition, thermal conductivity of the model p ipes was more than 200 Wi(m(.)K). (C) 2001 Published by Elsevier Science Lt d.