韋文誠臺灣大學:材料科學與工程學系暨研究所駱嬿雯Yen-Wen, LoLoYen-Wen2010-07-142018-06-282010-07-142018-06-282008U0001-2207200811565800http://ntur.lib.ntu.edu.tw//handle/246246/189009摘要 本研究主要採用膠粒分散及打泡法，將氣泡均勻分散在陶瓷漿料中，經適當的微波乾燥及燒結步驟，製備出孔隙率在85 %以上的多孔陶瓷，並使用不同材料種類、觀察微結構，了解這些因素對於熱傳導之影響。實驗中，分別以SDS和valeric acid當作起泡劑，利用直接泡沫法(Direct Foaming Method, DFM)做出孔隙率高達85 % ~ 95%的多孔氧化鋁，氧化鋯及雲母。經由掃描式電子顯微鏡(SEM-EDX)分析，發現製出的多孔陶瓷氣胞平均尺寸在17 um到80 um之間，且包含緻密與不緻密的兩種氣胞壁。利用熱機械性質分析(TMA)觀察不同孔隙率的多孔陶瓷對燒結溫度的影響。光學部份，經由快速傅立葉轉換紅外線光譜儀(FTIR)分析多孔陶瓷在1000 cm-1到4000 cm-1被散射的情況，及比較孔隙率、晶粒與氣胞壁對衰減係數之影響。在熱傳導分析部份，以熱線法(hot-wire method)自行組裝熱傳分析儀器，利用標準樣品做校正後，量測分析比較多孔陶瓷的孔隙率、晶粒大小、氣胞壁緻密度、以及固溶物與氧空缺對熱傳導係數的影響。本研究製備95 %孔隙率的氧化鋁有最佳隔熱性，其在室溫的熱傳係數為0.05 W/m*oC，在800oC為0.17 W/m*oC。This study used colloidal dispersion and direct foaming method to distributed bubbles uniformly in ceramic slurry. After microwave drying and appropriate sintering, the porous ceramics with porosity 85 ~ 95 % were made. The effects of material and porous structure on thermal conductivity are investigated in this study. Porous Al2O3, ZrO2 and mica with porosity higher than 85 % are foamed by the direct foaming method with SDS and valeric acid as surfactants. The gas cells of porous ceramics in an average bubble size with the range of 17 um to 80 um were characterized by scanning electron microscope equipped with energy dispersive spectroscopy (SEM-EDX). Two different cell walls with dense and non-dense profiles exist in the porous samples. Thermal mechanical analysis (TMA) was used to analyze the sintering behaviors of porous ceramics with different porosities. Light scattering between 1000 cm-1 and 4000 cm-1 were investigated by Fourier Transform Infrared Spectroscopy (FTIR). The instrumental set-up for measuring thermal conductivity by a hot-wire method was calibrated by the standard sample. The thermal conductivities of porous ceramics with different porosity, grain size, cell walls, and defects are observed and compared to each other. Consequently, small k value of 0.05 W/m*oC at room temperature and 0.17 W/m*oC at 800oC of one Al2O3 foam with the porosity of 95 % can be reached in this study.Contenthapter 1. Introduction 1hapter 2 Literature Review 3-1 Fundamentals of Processing of Porous Green Ceramics 3-1-2 Hydration Reaction 3-1-2 Surface Phenomena 5a) Surface Tension and Surface Energy 5b) Surface Curvature and Pressure 6-1-3 Bubble Stability 6a) Stability of Bubbles 6b) Foam Destabilization 7-2 Processing Methods of Porous Ceramics 10-2-1 Replica Method 10-2-2 Sacrificial Template Method 11-2-3 Direct Foaming Method 12-3 Thermal Conductivity by Phonon and Photon Conduction 16-3-1 Phonon Conduction 16a) Physical Definition and Theory of Phonons 17b) Influence Factors of Phonon Conductivity 19-3-2 Photon Conduction 21a) Physical Definition and Property of Photons 21b) Influence Factors of Photon Conductivity 22-3-3 Measurements of Thermal Conductivity 34a) Axial Flow Method 34b) Guarded Hot Plate Method 35c) Hot-Wire Method 36hapter 3 Experimental 43-1 Materials 43-2 Fabrication of Porous Ceramics 43-2-1 Foam Preparation 43-2-2 Drying and Sintering of Ceramic Foams 44-3 Characterization 45-3-1 Kinetic Analysis of Hydration 45-3-2 Microstructure Analysis 47-3-3 Porosity Measurement 47-3-4 Thermal Conductivity Measurement 48a) Instrument Set-up. 48b) Calibration. 48-3-5 FTIR Analysis 49a) Sample Preparation.. 49b) Sample Preparation for Porous Ceramics 50c) Calculation of Extinction Coefficient:. 50-3-6 TMA 51hapter 4 Results and Discussion 69-1 Hydration Reaction 69-2 Microstructure and Sintering Behavior 78-2-1 Microstructural Analysis of Porous Ceramics 78a) Al2O3 Foams 78b) ZrO2 Foams 80c) Mica Foams 80-2-3 Sintering Behavior 81-3 FTIR Analysis 102-3-1 Photon Transport 102a) Effect of Porous Ceramics 102b) Effect of Grain Size 103c) Effect of Gas-Cell Size 104d) Effect of Cell Walls of Triple Junctions 104-3-2 Extinction Coefficient 106a) Effects of Materials and Porosity 107b) Effect of Grain Size 108c) Effect of Gas-Cell Dense 108-4 Thermal Conductivity Analysis 119-4-1 Grain Size Effect 119-4-2 Porosity Effect 120-4-3 Effect of Atomic Defects 122-4-4 Effect of Dense Cell Wall on Thermal Conductivity 123-4-5 Effect of Photon Scattering 124. Conclusion 139錄一 多孔黏土陶瓷製作與分析 142-1 研究目的 142-2 結果與討論 142a) 黏土之TEM 分析 142b) 黏土之熱分析 143c) 多孔黏土之配方與SEM觀察 143d) 黏土熱傳導分析 143efrtrnce 1518675432 bytesapplication/pdfen-US氧化鋁氧化鋯孔隙率熱傳導光譜分析水合Al2O3ZrO2porositythermal conductivityFTIRhydrationthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/189009/1/ntu-97-R95527039-1.pdf