SiC/C遗态陶瓷的制备工艺研究

Preparation process of SiC/C morph-genetic ceramics

以苎麻纤维为生物模板,经溶胶-凝胶浸渍工艺获得苎麻/SiO2前驱体A和苎麻/酚醛树脂/SiO2前驱体B,在真空炉中经1 500℃碳热还原反应制备得SiC/C遗态陶瓷。采用TG-DTG、XRD和SEM等技术分别对材料的热解行为、物相构成和显微结构进行分析与表征,利用阿基米德法测定试样的显气孔率。结果表明:SiC/C遗态陶瓷继承苎麻纤维的天然结构形貌,其物相中包含有β-SiC相和石墨化程度较低的C相;由苎麻/SiO2前驱体A制备的试样组织结构疏松,界面结合较差,显气孔率高,纤维形貌更为完整;由苎麻/酚醛树脂/SiO2前驱体B制备的试样组织结构致密,界面结合较好,显气孔率低。

Sol-gel processing was used to prepare ramie/SiO2 precursor A and ramie/phenolic resin/SiO2 precursor B with ramie fibers bio-template,then SiC/C morph-genetic ceramics were obtained though the carbothermal reduction of the precursor at 1 500 ℃ in vacuum.Thermo gravimetric analysis（TG-DTG）,X-ray diffraction（XRD） and scanning electron microscope（SEM） were employed to analyze and characterize the pyrolysis behavior,phase composition and microstructure of the samples.And apparent porosity was measured by Archimend′s law.The results show that SiC/C morph-genetic ceramics inherit the original natural tracheid structure of ramie fibers,and the phase compositions are crystalline β-SiC phase and C phase with a low degree of graphitization.The samples prepared from ramie/SiO2 precursor A with loose organizational structure,poor bonding interface,high porosity and more completing morphology.The samples prepared from ramie/phenolic resin/SiO2 precursor B with dense organizational structure,good bonding interface,and low porosity.