液硅渗透法制备Ti_3SiC_2改性C/C-SiC复合材料

Fabrication of Ti_3SiC_2 modified C/C-SiC composites by liquid silicon infiltration

采用浆料浸渗结合液硅渗透法原位生成高韧性Ti3SiC2基体,制备Ti3SiC2改性C/C-SiC复合材料。研究了TiC颗粒的引入对熔融Si浸渗效果的影响,分析了Ti3SiC2改性C/C-SiC复合材料的微结构和力学性能。实验结果表明:TiC与熔融Si反应生成Ti3SiC2是可行的,而且C的存在更有利于生成Ti3SiC2;在含TiC颗粒的C/C预制体孔隙(平均孔径22.3μm)内,熔融Si的渗透深度1min内可达10.8cm;Ti3SiC2取代残余Si后提高了C/C-SiC复合材料的力学性能,C/C-SiC-Ti3SiC2复合材料的弯曲强度达203MPa,断裂韧性达到8.8MPa.m1/2;对于厚度为20mm的试样,不同渗透深度处材料均具有相近的相成分、密度和力学性能,无明显微结构梯度存在,表明所采用的浆料浸渗结合液硅渗透工艺适用于制备厚壁Ti3SiC2改性C/C-SiC复合材料构件。

In the paper, the high toughness matrix Ti3SiC2 was in-situ formed by the joint process of slurry infiltration and liquid silicon infiltration, and Ti3 SiC2 modified C/C-SiC composites were obtained. The effect of introduction of TiC particle on the infiltration of molten silicon were studied, and the microstructure and mechanical properties of C/C-SiC-Ti3 SiC2 composites were analysed. The results show Ti3 SiC2 can be formed by the reaction of TiC with liquid silicon during liquid silicon infiltration, and the existence of carbon is beneficial to the formation of TigSiC2. The infiltration depth of molten silicon in the micropore （mean size 22.3μm） can reach to 10.8 cm in one minute. The in- situ formed Ti3SiC2 replaces the residue silicon and improves both the flexural strength and the fracture toughness of C/C-SiC-Ti3SiC2 composites, which reach to 203 MPa and 8.8 MPaμm1/2 , respectively. For C/C-SiC-Ti3SiC2 composites with the depth of 20 mm, the materials with different infiltration depths displays similar phase composition, density and mechanical properties, and no obvious microstructure gradient exist, which indicate the joint process of slurry infiltration and liquid silicon infiltration can be used to fabricate the thick- wall components.