New route to process uni-directional carbon fiber reinforced (SiC + ZrB2) matrix mini-composites

Unidirectional carbon fiber-reinforced (SiC + ZrB2) matrix mini-composites were prepared by soft solution route. In this process, the matrix materials were prepared using water-soluble precursors of colloidal silica, sucrose, zirconium oxychloride, and boric acid as sources of silica, carbon, zirconia, and boron oxide respectively. The room temperature mechanical properties were investigated and the fracture features of the composites were examined. Tensile strength of 269 ± 36 MPa and fracture energy of 0.38 ± 0.05 MJ/m3 for the mini-composite, carbothermally reduced at 1,600 °C were attributed to the fiber pull out. In spite of a composite failure mode, the composite carbothermally reduced at 1,700 °C exhibited lower mechanical properties. It showed that carbon fibers reacted with ZrO2 to form ZrC phase at 1,700 °C, formed chemical bonding, and led to a strong interface between fibers and matrix, which resulted in the degradation of mechanical properties of the mini-composites. The XRD and SEM investigations of the powders and the mini-composites revealed phase formation whereas cross-sectional microstructure indicated the uniform distribution of fibers within the matrix.