FABRICATION OF THIN-WALLED SEAMLESS TUBES FROM GRAPHITE/MAGNESIUM PRECURSOR TAPES

THIN-WALLED TUBULAR STRUCTURES ARE EXTREMELY USEFUL FOR STRUTS AND JOINTS IN LIGHTWEIGHT TRUSSES FOR SPACE PLATFORMS, FOR ANTENNA SUPPORT SYSTEMS, AND, PERHAPS, EVEN FOR WAVEGUIDES. ON THE BASIS OF MASS-SPECIFIC PROPERTIES, GRAPHITE-FIBER-REINFORCED MAGNESIUM (GR/MG) COMPOSITES HAVE THE GREATEST POTENTIAL TO SATISFY AEROSPACE STRUCTURAL REQUIREMENTS FOR STRENGTH AND DIMENSIONAL STABILITY (STIFFNESS AND THERMAL EXPANSION). NEWLY DEVELOPED MANUFACTURING PROCESSES WILL BE USED TO PRODUCE GR/MG COMPOSITE PRECURSOR TAPES BY VAPOR DEPOSITION TECHNIQUES. THE FIBERS WILL BE PITCH-BASED CARBON AT A VOLUMEN FRACTION OF 0.5 AND CONFIGURED AS AN 8000-END TAPE. OUR PROCESS OFFERS ULTRA-THIN PLIES (0.0003 TO 0.0004 INCH) WITH EXCELLENT CONTROL OF FIBER VOLUME FRACTION, THEREBY, AFFORDING THE MATERIALS DESIGNER UNPRECEDENTED FLEXIBILITY IN SPECIFYING DIMENSIONAL STABILITY, MODULUS, OR STRENGTH IN LAMINAE AND FINAL PROPERTIES IN THE LAMINATED COMPOSITE STRUCTURE. THESE TAPES WILL BE FABRICATED INTO UNIDIRECTIONALLY REINFORCED DEMONSTRATION TUBES APPROXIMATELY 12 INCHES IN LENGTH, ONE INCH IN DIAMETER, AND APPROXIMATELY 0.020 INCH IN WALL THICKNESS. PRELIMINARY CHARACTERIZATION OF THESE TUBES WILL ESTABLISH DESIGN GUIDELINES FOR A PHASE II OPTIMIZATION AND SCALE-UP OF THE PROCESS.