Fabrication and microstructure analysis of continuous C fibers reinforced SiC-Cnfs hybrid composite tubes

摘要

The carbon nanofibers (Cnfs) dispersed SiC-Cnfs composite powder has been produced by spray freeze-granulation technique. SiC-based hybrid composite tubes (BN-C-f/SiC-Cnfs) were fabricated by systematically laying of boron nitride-coated continuous carbon fiber (BN-C-f) in the SiC-Cnfs composite matrix. High-density hybrid composite tubes were processed by cold isostatically pressing (CIP) of the afore-mentioned powder in a specially designed mold followed by pressureless sintering. The detailed processing techniques highlighting the criticality of each processing-step have been discussed. The implication of the processing techniques on the structure and properties of the composites were analyzed by using SEM, FTIR, and XRD, highlighting the matrix microstructure and the interfacial bonding of fiber with the matrix. In addition, the influence of newly evolved secondary-phases, Cnfs dispersion, long C(f)reinforcement on optimization of properties of the hybrid composites was discussed in detail highlighting TEM analysis. The fractographic analysis of the hybrid composite tubes was carried out to understand the influence of long fibers on the improvement of fracture toughness of the nanofibers containing hybrid composite matrix. The fracture toughness and the other mechanical properties of the base matrix were found to improve significantly due to the combined contribution of specially laid long fibers in nanofibers containing matrix.