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Ceramic Materials — Structures and Properties. Ceramic Materials 陶瓷材料 Inorganic materials 無機材料 Nonmetallic materials 非金屬材料 Most ceramics are compounds.

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Presentation on theme: "Ceramic Materials — Structures and Properties. Ceramic Materials 陶瓷材料 Inorganic materials 無機材料 Nonmetallic materials 非金屬材料 Most ceramics are compounds."— Presentation transcript:

1 Ceramic Materials — Structures and Properties

2 Ceramic Materials 陶瓷材料 Inorganic materials 無機材料 Nonmetallic materials 非金屬材料 Most ceramics are compounds between metallic and nonmetallic elements Composed of at least two elements, and often more Atomic bonding in ceramics ranges from purely ionic to totally covalent

3 MaterialIonic Character CaF 2 89% MgO73% NaCl67% Al 2 O 3 63% SiO 2 51% Si 3 N 4 30% ZnS18% SiC12%

4 Electronegativity 電負度、陰電性

5 Stable and unstable cation-anion coordination configuration unstable stable Cations are ordinarily smaller than anions cation 陽離子 anion 陰離子

6 Coordination Number 配位數 Cation-Anion Radius Ration r C /r A <

7 r C /r A > 1  配位數 12

8 Crystal Structures AX Type –Rock Salt Structure 岩鹽結構 –Cesium Chloride Structure 氯化銫結構 –Zinc Blende (Sphalerite) Structure 閃鋅礦結 構 AX 2 Type –Fluorite Structure 螢石結構、氟石結構 ABX 3 Type –Perovskite Structure 鈣鈦礦結構 AB 2 X 4 Type –Spinel Structure 尖晶石結構

9 Rock Salt Structure 岩鹽結構 NaCl, MgO, MnS, LiF, FeO r Na + = nm r Cl  = nm r Na + /r Cl  = 0.564

10 Cesium Chloride Structure 氯化銫結構 CsCl r Cs + = nm r Cl  = nm r Cs + /r Cl  = 0.939

11 Zinc Blende Structure 閃鋅礦結構 ZnS, ZnTe, SiC, ZnO r Zn 2+ = nm r O 2  = nm r Zn +2 /r O 2  = 0.529

12 Fluorite Structure 螢石結構 CaF 2, ZrO 2, UO 2, PuO 2, ThO 2 r Ca 2+ = nm r F  = nm r Ca +2 /r F  = 0.8

13 Perovskite Structure 鈣鈦礦結構 BaTiO 3, SrZrO 3, SrSnO 3

14 Interstitial position 填隙位置、間隙位置 Tetrahedral position 四面體位置 Octahedral position 八面體位置 close-packed structure 最密堆積結構、緊密堆積結構

15 Crystal structure Hexagonal Close-Packed (HCP) 六方最密堆積 –ABAB... Stacking Sequence Face-Centered Cubic (FCC) 面心立方 –ABCABC... Stacking Sequence c a A sites B sites A sites

16 Determine Crystal Structures 1.Stoichiometry 化學計量 Charge Neutrality 2.Cation-anion radii ratios (coordination number) 3.Covalent character

17 Ceramic Density Computation Number of formula units/unit cell A C : atomic weight of cation A A : atomic weight of anion V C : Volume of unit cell N A : Avogadro’s number

18 Silicate Ceramics 矽酸鹽陶瓷

19 Silica 矽石、二氧化矽 Crystalline structure of Silica –Quartz 石英 –Cristobalite (Crystobalite) 白矽石、方矽石 –Tridymite 鱗石英、鱗矽石 The strong Si-O bond leads to a strong, high melting temperature (1710  C)

20 Cristobalite (Crystobalite) 白矽石、方矽石

21 Silica Glass 矽石玻璃 fused silica or vitreous silica 熔凝矽石或 玻化矽石 B 2 O 3 and GeO 2 –Network former CaO and Na 2 O –Network modifier TiO 2 and Al 2 O 3 –Intermediate Modifiers and Intermediates lowers the melting point and viscosity of a glass

22 Crystalline silicon dioxideNoncrystalline silicon dioxide

23 Silicate 矽酸鹽

24 Two-dimensional silicate sheet structure (Si 2 O 5 ) 2 

25 Layered Silicates Can change the counterions ( 相對離子 ) –this changes layer spacing –the layers also allow absorption of water Mica 雲母 KAl 3 Si 3 O 10 (OH) 2 Bentonite 膨土、火山黏土 –used to seal wells –packaged dry –swells 2-3 fold in H 2 O –pump in to seal up well so no polluted ground water seeps in to contaminate the water supply

26 Structure of kaolinite clay 高嶺黏土

27 Carbon 碳 Diamond 鑽石 –metastable state 介穩態、準穩態 Graphite 石墨 Fullerene 芙、芙樂、富勒、芙樂烯、富勒烯 C 60 –Buckminsterfullerenes 巴克明斯特芙樂烯 –Buckyball 巴克球

28 Diamond cubic crystal structure

29 Structure of Graphite

30 Structure of a C 60 Molecule

31 Structure of a Carbon Nanotube

32 Imperfections in Ceramic Imperfection 缺陷 Electroneutrality 電中性 Atomic Point Defect –Vacancy 空位 –Interstitial 填隙、間隙 Defect Structure –Frenkel defect 夫倫克耳缺陷 –Schottky defect 肖特基缺陷 Stoichiometry or Nonstoichiometry

33 Defect Structure Frenkel defect Schottky defect

34 Impurities in Ceramics Electroneutrality 電中性 Solid solution 固溶體 –substitutional type –interstitial type

35 Diffusion in Ionic Materials Diffusion in ionic materials usually occurs by a vacancy mechanism Electroneutrality 電中性

36 Ceramic Phase Diagrams MgO-Al 2 O 3

37 Brittle Fracture of Ceramics brittle fracture 脆性斷裂 plastic deformation 塑性形變 fractography 斷口形像學 crack 裂痕、裂紋、裂縫 branch or bifurcate 分叉

38 Stress-Strain Behavior Stress 應力 Strain 應變 flexural strength 抗彎強度、抗撓強度、 撓曲強度 modulus of rupture 破壞模數 fracture strength 破裂強度 bend strength 彎曲強度

39 Plastic Deformation Crystalline ceramics Noncrystalline ceramics –Viscosity 黏度、黏性


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