Microstructural evolution and mechanical properties of C/SiOC composites prepared by PIP process

Abstract

Carbon fiber reinforced silicone resin derived SiOC ceramic (C/SiOC) composite is a high-temperature structural material with good application prospect due to its performance/cost ratio. In order to further reduce the cost, carbon fiber needled felt with low price was selected as the reinforcement, and C/SiOC composites were prepared by precursor impregnation pyrolysis (PIP) process. The hot molding process was introduced in the first cycle of PIP route. By optimizing the concentration of precursor solution, molding temperature and pressure, the fiber volume fraction and matrix content in the first cycle were effectively improved without damaging the structure of needled felt. Accordingly, the bending strength at room temperature and fracture toughness of C/SiOC composites were increased to 331 MPa and 16.0 MPa·m1/2, respectively. Then the microstructure evolution during the fabrication of C/SiOC composites was evaluated. The results show that SiOC matrix grows in the carbon fiber bundle firstly, then grows from inside to outside of carbon fiber bundle during fabrication. The pores are distributed around Z direction fibers. Porosity of the composites is decreased gradually and pores of the composites transformed from connected ones into isolated ones as the fabrication cycles is increased. When the fabrication cycles reach 8, the porosity of the composites is unchanged basically. At the same time, the densification of composites is completed.

Keywords

• c/sioc composites
• three-dimensional needle-punched carbon fiber
• hot molding process
• mechanical property
• precursor infiltration pyrolysis