Ultra-High strength and toughness continuous SiCf/SiC ceramic matrix composites prepared by an additive manufacturing manipulator

Abstract

Additive manufacturing (AM) technology provides a pathway for the preparation of complex structured silicon carbide (SiC) ceramics. Due to the high brittleness of SiC materials and a high scrap rate for large and complex SiC ceramics, short-cut and continuous carbon fibers have been used to improve the toughness of AM SiC ceramics, but the reinforcement effect is limited. Here, we report a novel combination process of the continuous fiber AM, precursor infiltration pyrolysis (PIP) and liquid-phase silicon infiltration (LSI) to prepare continuous SiC fiber (SiC_f) -reinforced SiC ceramic matrix composites (CMC). Continuous SiC fibers as reinforcing phases can improve the strength and toughness of SiC ceramics. The two polycarbosilane (PCS) PIP processes form a SiC interface layer on the surface of continuous fibers to avoid fiber corrosion during the LSI process. The multiple phenolic resin infiltration and pyrolysis processes regulate the carbon density and microstructure of carbonized parts. In the LSI process, the liquid-phase silicon reacts with partially pyrolytic carbon to generate SiC. When the carbon density of the carbonized part is 0.85 g/cm³, the final part has the high flexural strength and fracture toughness of 398 MPa and 10.79 MPa·m^1/2, respectively. Through enhancing the strength and toughness of SiC ceramics, the complex SiC CMC parts prepared by the proposed combination process show great application prospects in various fields.