Using PyC modified 3D carbon fiber to reinforce UHTC under low temperature sintering without pressure

Abstract

To find the optimum balance between strength and toughness, as well as acquiring reliable thermal shock resistance and oxidation resistance, has always been the most concerned topic in the discussion of ultra-high temperature ceramic composites. Herein, PyC modified 3D carbon fiber is used to reinforce ultra-high temperature ceramic. The macroscopic block composite with large size is successfully fabricated through ultra-low temperature sintering at 1300°C without pressure. The prepared PyC modified 3D Cf/ZrC-SiC composites simultaneously possess excellent physical and chemical stability under the synergistic effect of PyC interface layer and ultra-low temperature sintering without pressure. The fracture toughness is increased in magnitude to 13.05 ± 1.72 MPa∙m1/2 accompanied by reliable flexural strength of 251 ± 27 MPa. After rapid thermal shock spanning from RT to 1200°C, there is no visible surface penetrating cracks, spalling or structural fragmentation. The maximum critical temperature difference reaches 875°C, which is nearly three times higher than that of traditional monolithic ceramics. The haunting puzzle of intrinsic brittleness and low damage tolerance are resolved fundamentally. Under the protection of PyC interface layer, the carbon fibers around oxide layer and matrix remain structure intact after static oxidation at 1500°C for 30 min. The oxide layer has reliable physical and chemical stability and resist the erosion from fierce oxidizing atmosphere, ensuring the excellent oxidation resistance of the composites. In a sense, the present work provides promising universality in designability and achievement of 3D carbon fiber reinforced ceramic composites.

Additive manufacturing of continuous carbon fiber–reinforced silicon carbide ceramic composites

“…The bending strength and fracture toughness of C f /SiC composites are mainly improved by the pullout, debonding, and breakage of C f to enable the material to absorb more energy. 31,38 Figure 14 shows the bending strength, porosity, and density of the green bodies with different C f contents. It is observed that the bulk density of the samples increases and then decreases with increasing C f content, and the sample C-1 shows the lowest porosity and the highest bulk density.…”