Polymer derived PyC interphase coating for C/SiBOC composites

Polymer derived Pyrocarbon (PyC) interphase coating with varying thickness were deposited onto the surface of carbon fiber reinforcement by dip coating technique. The graphitic layered structure of PyC interphase was characterized by X-ray diffraction analysis (XRD) and Raman spectroscopy. Two-dimensional carbon fiber reinforced SiBOC matrix (2D C/PyC/SiBOC) composites were fabricated by Polymer Infiltration and Pyrolysis (PIP) process. Influence of the interphase thickness on the flexural strength of C/SiBOC composites was investigated using three-point bending test. The Extended Pressure Scanning Electron microscope (EPSEM) was used to evaluate the PyC coating thickness. The results indicated that the flexural strength of composites initially increased with increasing PyC coating thickness and reached a peak value of 163 ± 2 MPa at a coating thickness of 0.5 μm. Further increase in the coating thickness led to decrease in the flexural strength of the composite. Oxidative stability of C/PyC/SiBOC composites were investigated and the oxidation rates were compared with that of C/C and C/SiBOC. The results indicated that PyC interphase can improve the oxidation resistance of C/SiBOC composites.