METAL MATRIX COMPOSITES BEHAVIOR AT CRYOGENIC TEMPERATURES

*MMC ARE VIALBLE CANDIDATES FOR SATELLITE AND SPACECRAFT STRUCTURES. THEIR PROPERTIES AND BEHAVIOR AT THE LOW TEM- PERATURES EXPERIENCED IN LOW-EARTH OR GEOCENTRIC ORBITS OR FOR DEEP SPACE MISSIONS ARE INADEQUATELY KNOWN. NETCO PRO- POSES TO OBTAIN THESE DATA UTILIZING SPECIMENS OF A GR/A1 UNIDIRECTIONAL FIBER-REINFORCED COMPOSITE. PRELIMINARY NON-DESTRUCTIVE METHODS FOR CHARACTERIZING PANEL-TO-PANEL AND SPECIMEN-TO-SPECIMEN VARIABILITY WILL FIRST BE UNDERTAKEN, AND A SMALL NUMBER OF SPECIMENS WILL BE TESTED AT RT 20.0 DEG C) FOR LONGITUDINAL AND TRANSVERSE STRENGTHS, DYNAMIC AND STATIC MODULI, AND STRAINS TO FAILURE IN TENSION AND COMPRESSION. WET CHEMICAL ANALYSISWILL BE OBTAINED. HALF THE REMAINING SPECIMENS WILL BE IMMERSED ONCE OR MORE TIMES IN LN (2) AND AGED TO T6. THERE WILL BE COMPLETE CHARACTERIZATION AND HALF OF THEM WILL BE STATICALLY TESTED AT RT WITH PARTICULAR CARE BEING TAKEN TO DETERMINE THE ELASTIC LIMITS IN LONGITUDINAL TENSION AND COMPRESSION. THEREMAINING T6 SPECIMENS WILL BE TESTED FOR CTE (L) IN THE RANGE OF RT-LN(2) - RT, AND A SMALL NUMBER STATICALLY TEST- ED IN THE LN(2) TEMPERATURE (-195.8 DEG C).