制备多孔C_f/ZrO_2陶瓷基复合材料研究

Fabrication of Porous C_f/ZrO_2 Ceramic Matrix Composite

以带有SiC涂层(厚度～1μm)的C纤维预制体作为骨架,液相浸渍Sol-Gel法制备的高固相含量ZrO_2先驱体,溶胶-原位烧结制备多孔Cf/ZrO_2陶瓷基复合材料。ZrO_2先驱体溶胶稳定性取决于pH值和稀释NH_3·H_2O的浓度。pH=3时先驱体溶胶固相含量为50%。XRD及SEM结果表明:不同烧结温度和烧结气氛条件下,多孔Cf/ZrO_2陶瓷基复合材料的成分物相和表面形貌有明显差别。Ar气氛低温烧结可以有效防止C纤维氧化和副反应发生,断裂过程中有纤维拔出的痕迹。1100℃烧结制备Cf/ZrO_2陶瓷基复合材料力学性能最好,显气孔率为54%时弯曲强度接近13 MPa。

Zirconia based porous composite was fabricated by liquid phase dipping and in-situ sintering using the silicon carbide coated carbon fibre perform. Low viscous sol of zirconia precursor dispersed with a high concentration of solid phase was prepared by sol-gel method. The stability of zirconia precursor sol depended on the pH value and the concentration of NH3-H2O dilute, with the optimal values of 3% and 50% respectively. The component and microstructures of the Cf/ZrO2 composite changed with the sintering temperature. Oxidation of the carbon fibre and the secondary reaction were suppressed for the composite sintered at low temperature in argon. Pulling out of carbon fibres took placed, an indicator of the improved mechanical properties of the composite. The flexural strength of the composite sintered at 1100 ℃ approached to 13MPa with the porosity of 54%.