Mechanical properties and strengthening mechanism of SiCf/SiC mini-composites modified by SiC nanowires

The effects of the SiC nanowires (SiCNWs) and PyC interface layers on the mechanical and anti-oxidation properties of SiC fiber (SiCf)/SiC composites were investigated. To achieve this, the PyC layer was coated on the SiCf using a chemical vapour infiltration (CVI) method. Then, SiCNWs were successfully coated on the surface of SiCf/PyC using the electrophoretic deposition method. Finally, a thin PyC layer was coated on the surface of SiCf/PyC/SiCNWs. Three mini-composites, SiCf/PyC/SiC, SiCf/PyC/SiCNWs/SiC, and SiCf/PyC/SiCNWs/PyC/ SiC, were fabricated using the typical precursor infiltration and pyrolysis method. The morphologies of the samples were examined using scanning electron microscopy and energy dispersive X-ray spectrometry. Tensile and single-fibre push-out tests were carried out to investigate the mechanical performance and interfacial shear strength of the composites before and after oxidization at 1200 degrees C. The results revealed that the SiCf/PyC/ SiCNWs/SiC composites showed the best mechanical and anti-oxidation performance among all the composites investigated. The strengthening and toughening is mainly achieved by SiCNWs optimization of the interfacial bonding strength of the composite and its own nano-toughening. On the basis of the results, the effects of SiCNWs on the oxidation process and retardation mechanism of the SiCf/SiC mini-composites were investigated.

Automated summary

The addition of SiC nanowires (SiCNWs) in SiCf/PyC composites resulted in the best mechanical and anti-oxidation properties, mainly achieved through optimization of interfacial bonding strength and nano-toughening effects.