| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 94 === Among several advanced energy technologies, SOFC have many advantages such as higher efficiency, low pollution, no noise, etc. In the sturcture of SOFC, ordered porous structure will enhance the transport of gas and then facilitate the electrochemical reaction. In this study, the monodisperse PMMA spheres were orderly compacted by gravitation method.The interstices between PMMA spheres were filled with NiO/YSZ precursor by impregnation method. Subsequently, NiO/YSZ with ordered and porous structure was obtained by removing the PMMA spheres followed heat treatment at 800℃.
In this study,the effect of heat-treatment temperature and the reducing atmosphere on the macroporous structure of NiO/YSZ was disccused. The result shows that the monodisperse PMMA spheres with diameters of 4.2μm, 6.4μm, and 1.2μm were prepared by dispersion polymerization method when PAA, PVP and PDMS as stabilizer were used individually. The PMMA spheres with diameter of 0.45μm were prepared by emusifier-free emulsion polymeriztion method. When using the gravitation method, PMMA spheres with diameters of 1.2μm and 0.45μm could form the 3-D ordered array. After filling PMMA spheres with diameters of 4.2μm and 6.4μm with precursor and followed by calcination at 800℃, the pore diameter of macroporous NiO/YSZ macroporous structure were estimated to be 2.4μm and 3.36μm respectively. When using the PMMA spheres with diameter of 1.2μm and 0.45μm PMMA spheres as templates, the 3-D oredred macroporous structure with diameters of 0.81μm and 0.3μm was obtained. The BET specific surface area of macroporous NiO/YSZ with pore diameter of 0.3μm was found to be 18.66m2/g.
After sintering at 1300℃ for 4h, the macroporus structure of NiO/YSZ collapsed due to the minimization of surface tension. However, the macroporous structure of NiO/YSZ remained stable at 1200℃. Due to the volume reduction accompanied the reduction of NiO into metallic Ni, the strength of macroporous Ni/YSZ is lower than its oxide counterpart. Thus, the ratio of NiO/YSZ should be less than 60% in order to obtain a desired macroporous Ni/YSZ structure using PMMA spheres as a template.
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