液态硅浸渍反应和混合酸(HNO_3+HF)刻蚀制备多孔SiC陶瓷

Preparation of Porous SiC Ceramic by Liquid Si Infiltration and Mixture Acid (HNO_3+HF) Etching

通过液态硅浸渍反应和混合酸(HNO3+HF)腐蚀制备了多孔SiC陶瓷。扫描电镜(SEM)结果显示,多孔SiC具有不规则且相互连通的孔道结构,其微观形貌特征源于滤纸和酚醛树脂制备的多孔碳。多孔SiC的气孔率可达62%,混合酸腐蚀的多孔SiC的弯曲强度和断裂韧性均小于致密SiC/Si复合体。并提出用循环氧化-腐蚀机制解释游离态Si的腐蚀过程。

Porous SiC was prepared by liquid Si infiltration and mixture acid （HNO3＋HF） etching. SEM observation reveals that the porous SiC possesses irregular, interconnected and porous morphology, which comes from the porous carbon perform derived by filter paper and phenolic resin. Open porosity of the porous SiC is up to 62%. The bending strength and the fracture toughness of the porous SiC are lower than that of SiC/Si composites. The etching mechanism of free Si can be explained by the repeated oxidation-etching process.