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1、Chapter 3 Ceramics,陶瓷材料龙志强 18702301212,重庆理工大学材料科学与工程学院,材料概论,Introduction to Materials,2,Inorganic Non-metallic Materials,陶瓷材料的概念与分类Concept and classification陶瓷的结构 Structure of Ceramics陶瓷材料的制作工艺 Manufacture and processing technologies陶瓷材料的性能及应用Properties and applications,2.1,1 陶瓷的概念和分类 Concept and Cl
2、assifications 1.1 概念 Concept陶瓷Ceramic:烧过的粘土。是陶器(pottery)和瓷器(porcelain)的总称。定义:陶瓷指经过高温处理所合成的无 机非金属材料(Inorganic&nonmetallic materials),简称无机材料。,3.1 Introduction,What is the ceramic,The word“ceramic”can be traced back to Greek term“keramos陶器”which is related to an old Sanskrit（梵语）root meaning“to burn”.Ca
3、n be defined as inorganic compounds made by heating clay or other mineral matter to a high temperature at which they partially melt and bond together.Ceramic can be defined as inorganic,nonmetallic materials.,陶器-瓷器,比较,表面效果制作材料烧制温度敲击声音,陶瓷之别,9,Ceramics are refractory polycrystalline（多晶）compounds Highl
4、y inert(惰性);biocompatible(生物适应性的）Hard and brittle（脆性）High compressive strength（耐压强度）Generally good electric and thermal insulators(绝缘)Good aesthetic appearance美观,Usually compound 化合between metallic and nonmetallic elementsAlways composed of more than one elementBonds are partially or totally ionic,a
5、nd may have combination of ionic离子键 and covalent bonds共价键Majority多数 has ionic(in salt compounds)or metallic and nonmetallic elements(as in oxides Al2O3,MgO,SiO2),主要组分：硅酸盐化合物 在美国，陶瓷泛指硅酸盐材料，又称为传统陶瓷或普通陶瓷。包括日用陶瓷、工业用陶瓷、一般玻璃、水泥、耐火材料等。先进无机材料(advanced inorganic materials):用氧化物、氮化物、硅化物、碳化 物以至各种无机非金属化合物经过 特殊的
6、先进工艺制成的材料。,1.2 分类 Classification,12,Ceramics,traditional ceramics:derived and processed from clay or nonclay minerals including refractories（耐火材料),white wares,cement(水泥),porcelain(瓷器),and structural clay ceramics.,advanced ceramics:high purity,better mechanical,electrical,magnetic,and optical proper
7、ties,1.2.1 传统陶瓷 Traditional ceramics：,又称普通陶瓷，主要是指以天然无机物如粘土等为主要原料、经高温处理得到的制品，主要用于制造日用器皿、生活洁具等生活用具。瓷器 Porcelain;Chinaware：细密的陶瓷器皿，质硬、半透明、白色、发 声清脆以及无孔，以长石(Feldspar)、石英（Quartz）和高岭石(Kaolin)为基本原料经一次烧成。,13,14,Traditional Ceramics,15,艺术陶瓷,16,1.2.2 先进陶瓷 Advanced ceramics：,又称为精细陶瓷、新型陶瓷、高技术陶瓷、特种陶瓷等。New、technic
8、al、engineering、advanced ceramics是指以精制的高纯天然无机物或人工合成无机化合物为原料，采用精密控制的制造加工工艺烧结，得到的具有独特性能的高功能陶瓷。,21,Advanced ceramics,Advanced ceramics are developed form rather simple chemical compounds,and advances in processing which have provided greater control over their structures.Advanced ceramic:the scale of th
9、e raw materials and microstructures,including the crystal grains,crystal interface,pores and defects is at the level of microns.先进陶瓷，从原料、显微结构中所体现的晶粒、晶界、气孔、缺陷等在尺度上都是处在微米级的水平。,Classification based on applications,Advanced(New)Ceramic materials Oxides Nitrides Carbides Abrasives Rocket Engines Abrasive
10、s研磨料 Bioceramics Gas Turbiness 燃气涡轮机 Resistance Heating电阻加热 Electrical Cutting Tools Steel Additives(Steel)Cutting Tools High Temperatures Refractory Brick Substrates基板 Cutting Tools(cermets)耐火砖 For IC Chips Glass Additives coatings Armor Ceramic Matrix Composites Nuclear Fuels Reinforcing Fibers,Ad
11、vanced Ceramics,Cutting tools Zirconia toughened alumina 氧化锆增强氧化铝,24,25,红色陶瓷系列,黑色陶瓷系列,黄色陶瓷系列,密封环陶瓷系列,26,点火头系列,27,1.2.3 先进陶瓷的分类,组成 composition：氧化物 oxide、氮化物 nitride、硅化物 silicide、碳化物 carbide 性能 properties&applications：结构陶瓷 structural ceramics、功能陶瓷 functional ceramics,28,结构陶瓷:以力学、机械性能为主。Mechanic proper
12、ties功能陶瓷:利用材料的电、磁、光、声、热等性能及其耦合效应，如铁电、压电陶瓷、敏感陶瓷、快离子导体陶瓷等。主要从电性能上考虑有绝缘陶瓷、介电陶瓷、半导体陶瓷、导体陶瓷以至高临界温度的超导陶瓷。,29,1.3 陶瓷的发展,30,1.4 Applications,Thermal Barrier Coatings:热屏蔽涂层Low thermal conductivity传导性 reduces metal temperatures,31,Electronics Packaging电子封装:,Ceramics:Provide high temperature performance and th
13、ermal expansion coefficient match to SiliconHigh thermal conductivity desired,32,Ceramic Armour 装甲,33,34,Some other examples,1.4 陶瓷的发展趋向,纳米陶瓷 nano-ceramic特性：原材料粉末 raw materials powder颗粒为纳米级 nano-level grains；微观结构 microstructures,晶粒grains,晶界 interfaces，气孔 pores以及 晶体缺陷 defects 同样在纳米级 nano-level。,35,两种
14、晶型复合的复相陶瓷：同一化 学组成的物质经适当的工艺控制,得到不同晶型和不同的颗粒形貌的复相陶瓷，达到自补强的目的。有机和无机复合的复相陶瓷：介于有机与无机材料之间，不需要高温处理而获得的一种新型材料。金属陶瓷：金属与陶瓷复合的复相陶瓷。,36,3.2 Structure of Ceramics,Crystalline solids composed of metallic and nonmetallic materialsCeramics are crystal structures made of metallic ions and Inorganic materials Bonding
15、is either partially or completely ionic离子键.（还有共价键covalent bonds）Variables include The magnitude量级 of the electrical charge电荷 on the ions;The relative size of the ions离子,37,Properties of Ceramics,Corrosion resistance抗腐蚀,chemical inertness惰性,thermal shock resistance抗热震性,wear-resistance耐磨Electrical pro
16、perties:solid electrolytes in experimental batteries and fuel cells燃料电池Other uses:include automotive sensors,packaging for integrated circuits,electronic/optical devices,fiber optics,microchips,and magnetic heads,38,3.2.1 Structure of ceramics,普通陶瓷的结构 Microstructure of ordinary ceramics陶瓷是由金属（类金属）和非
17、金属元素之间形成的化合物，其中的原子（离子)主要以共价键或离子键相结合。陶瓷通常是一种多晶多相的聚集体。,39,普通陶瓷的显微结构主要由晶相、玻璃相、气相及晶界构成。,40,晶相 crystal phase,Crystal phase:the main phase in ceramic materials,and composed of some solid solutions and compoundsh化合物.Its structure and morphology形态 decide the microstructure,properties and applications of cer
18、amics.,41,Introduction,Structure of ceramics:most varies from relatively simple to highly complex.Being compounds,ceramics are made of different types of atoms of varying sizes.,42,Silicate 硅酸盐,The basic structure unit:SiO4 tetrahedron四面体.Oxygen(O)and silicon(Si)together account for about 75%of the
19、earths crust.,43,Types:1000 different silicates occur naturally,depending on the different ways the SiO4 tetrahedra can be linked.,44,Clay,Clay:a complex mixture of silicates.Silicates:are complex ionic compounds that are exceedingly numerous数目众多.Clays:have sheets of linked SiO4 tetrahedra which sli
20、de over each other,giving their minerals a characteristic soft feeling.,45,Characteristics of layered structures,Layered structure:as a lubricant润滑剂,water can penetrate,producing a material that is pliable(柔软的)and slippery.When heated:1100 oC in a kiln(窑),the water in clay is removed;the layered she
21、ets bond or lock into a rigid structure.The material with such a solid structure is called a ceramic.,46,Structures of silicates,Chain or ring structures:link by sharing the atoms in two corners of the SiO4 tetrahedrons.Layered silicates:sharing three corner atoms.Such as:talc 滑石,kaolinite 高岭石 clay,
22、mica云母.Framework框架 silicates:sharing four corner atoms.,47,Silica 二氧化硅,Pure silica:three polymorphs 晶型cristobalite 方石英tridymite 鳞石英:high temperaturequartz 石英:low temperatureIt is the basic structure for glasses and many ceramics.,48,Structures Properties,Atoms 原子are held strongly:the atoms are diffi
23、cult to move or slip in relation to each other.the ductility延展性 of ceramics is very low and they are brittle.High shear stresses Low ductility High compressive strength 抗压强度 Low tensile strength 抗张强度.,49,Bend strength:the maximum bending stress in tension of failure.Metals VS ceramics:at room temper
24、ature:they are competitive;850 oC,metals weaken while ceramics retain much of their strength.Ceramics:good heat resistance.alumina:1800 oCsilicon carbide:1700 oC,Ceramic Phase Diagrams,Microstructures:depending on the compositions,and the variables of temperature and pressure.The desired microstruct
25、ure:coming from the processing.As the composition becomes more complex,the more the number of phases present themselves.,51,phase diagram 相平衡状态图，相图,The phase diagram,equilibrium,or constitutional diagram:The map that shows the different compositions and the temperatures under equilibrium conditions.
26、（Mullite 莫来石 3Al2O3-2SiO2）,52,莫来石（或莫乃石）是一系列由铝硅酸盐组成的矿物统称，这一类矿物比较稀少。莫来石是铝硅酸盐在高温下生成的矿物，人工加热铝硅酸盐时会形成莫来石。天然的莫来石晶体为细长的针状且呈放射簇状。莫来石矿被用来生产高温耐火材料。耐火度:1800oC时仍很稳定,1810oC分解为刚玉和液相莫来石是一种优质的耐火材料，它具有膨胀均匀、热震稳定性极好、荷重软化点高、高温蠕变值小、硬度大、抗化学腐蚀性好等特点，目前主要有高纯电熔莫来石、普通电熔莫来石、全天然铝矾土精矿烧结莫来石和轻烧莫来石。适用于石油裂介炉、冶金热风炉、陶瓷辊道窑、隧道窑、电瓷抽屉窑、玻璃
27、坩埚窑及各种电炉的内衬，可直接接触火焰,53,3.2.2 Microstructures of Ceramics,Porosity and DensityMass density质量密度,which uses the mass of a material divided by its volume refers to this theoretical densityAtomic weight is a major factor in determining the density of a materialClose-packed密实的 metals are more dense than o
28、pen-structured materials.,54,Brittle Fracture of Ceramics脆性断裂,Defects缺陷 in ceramics can develop due to internal stresses(内应力)and porosityThermal stresses due to an-isotropic thermal expansion（各向异性热膨胀）tend to crack weak grain boundaries,55,96%dense alumina,56,Pores in partially sintered Alumina部分烧结氧化
29、铝中的孔隙,Green density 压坯密度is the bulk density体积密度of a compact prior to its densification密实化.In preparing particles for the production of powdered metals or ceramics,the packing of spherical shaped球形,monosized单一尺寸(0.1m)particles,even when vibrated振动 to settle the particles,does not achieve a density le
30、vel much higher than 60%.,57,Despite tapping or vibrating,these particles do not rearrange themselves completely to eliminate 除去 pores.The optimum density of spherical particles can be reached by varying the size distribution of particles to permit smaller particles(50 nm or less)to locate in the in
31、terstices(空隙)of the larger ones.,58,Ceramics are,by nature,generally porous孔隙的 materials with varying degrees of porosity.Bulk density体积密度is used in this instance to refer to a ceramics density,and it includes the materials porosity and the fact that most ceramics contain both a crystalline and a no
32、ncrystalline phase.,59,Open porosity开口孔 refers to the network of pores in a material that is open to the surface and into which a liquid such as water can penetrate渗透 if the part were submerged浸入init.Closed porosity闭口孔 refers to those pores that have become sealed within the grain structure.,60,Pore
33、s affect the strength of ceramics in two ways：First，they produce stress concentrations应力集中.Once the stress reaches a critical level,a crack will form and propagate扩展.Second，pores reduce the cross-sectional areas over which a load can be applied and,consequently,lower the stress that these materials
34、can support.,61,The amount,size,distribution分布,and the continuity 连续性 of voids空隙 in a ceramic are the principal factors that determine its propertiesIn general，porosity is detrimental 有害的 to ceramics properties.Grain boundary晶粒界线 sliding,creep rate,and chemical reactions that attack the ceramic or r
35、educe its melting point are more adverse不利的 conditions produced by impurities and porosity.,62,63,说明：a:颗粒聚集b:开口堆积体中颗 粒中心逼近c:封闭堆积体中颗 粒中心逼近,3.3 Ceramic Processing,Traditional Processingstructural clay products and the whitewares.Formation Drying Firing,成型 Forming：,将粉料直接或间接地转变成具有一定形状、体积和强度坯体，称为素坯或生坯(ro
36、ughcast)。成型的方法有很多，主要有可塑法、注浆法与压制法。,可塑成型,利用泥料的可塑性。将粉料与一定水份或塑化剂混合均匀，使之成为具有良好塑性的料团，再用手工或机械成型制成坯体。,注浆成型,即浆料成型法，是将原料配制成胶状浆料注入具有所需形状的模具中成型，又可分为注浆成型和热压注浆成型。,压制成型,将粉料填充在模型中，施加压力，制成具有一定现状和强度的坯体。分类：普通压制成型和等静压制成型。适宜于干料(含水37)或半干料(含水815)。,Drying and Firing/Sintering,Drying:decrease layer size and spacing,Schemati
37、c illustration示意图,Sintering/firing,梭式窑,The roles of clay minerals:,Hydroplasticity含水塑性:by adding water,the clays become very plastic.Dense then,producing a dense and strong ceramics during firing without complete melting so that the desired shape is maintained.,等离子放电烧结过程示意图,Advanced Ceramic Processi
38、ng,制备工艺：不再以熔炉为主要烧结工具,如真空烧结、气氛烧结、热压烧结、气压烧结等。性能：高强度、高硬度、耐腐蚀、导电、绝缘以及磁、电、光、生物相容性等。,Chemical processesSol-gel processingMelt processing Producing single-crystal materials Vapor processing Directed metal oxygen process,固相法：包括热分解法(thermal decomposition)；非晶合金退火结晶法（在玻璃转变温度下结晶）；自蔓延高温合成方法（制备金属复合材料）。液相法：包括沉淀法；水
39、解法；溶胶-凝胶法（通过水解金属醇盐或金属无机盐来合成氧化物的一种化学方法）。,气相法：包括气相合成法；气相热分解法。机械法：球磨、振动磨、高能球磨、气流粉碎。溶剂蒸发法：酒精干燥法、冷冻干燥法、热石油工作法、喷雾工作法液相法和气相法是制备超细粉的主要方法。,3.4 Properties of Ceramics,Mechanical properties Physical properties Chemical Properties Fabricability Other properties,Mechanical properties,No yield strength:ceramics d
40、o not plastically deform before reaching their tensile strength.No permanent elongation or reduction in area:ceramics cannot be plastic deformed by room temperature.,Mechanical properties,Compressive strength:excellent,better than metals,plastics,and composites.Hardness:highest in the engineering ma
41、terials.The long-term service characteristics of ceramics:Fatigue resistance and creep strength:good Tensile fatigue strength:poor.,Special Mechanical properties:Good in compressionVery high hardness and greater stiffness than other engineering materials.Weakness:brittleness,Physical properties,Comp
42、ared to metals:ceramics are lightweight,but low density may also be an indicator of too much porosity in a particular grade.As a structural material:the designer should select a ceramic with high theoretical density(99%).,The melting points of ceramics:are among the highest of all engineering materi
43、als.The thermal conductivity and electrical conductivity:cover a large spectrum.Most ceramics:electrical insulators,but some are semiconducting.Thermal expansion:lower than metals and plastics.,Chemical Properties,Resistant to chemical attack:the engineering ceramics,aluminum oxide,silicon carbide,z
44、irconia,silicon nitride,and others,are very resistant to chemical attack in a wide variety of solutes.,Fabricability,They cannot be plastically deformed to shapes at room temperatures.Ceramics cannot be melted and cast to shapes like metals,mostly because of their high melting temperatures.The machi
45、ning of ceramics is so costly that it is not an option for many machine parts.,Other properties,Wear Resistance Thermal Shock Resistance,Applications of Ceramics,Can withstand volatile and high-temperature conditions encountered in the processing of metals.The chemical,petroleum,energy conversion,gl
46、ass and other ceramic industries all rely upon refractory materials.,Uses in the Construction Industry:,Areas such as commercial buildings,residential homes,highways,bridges,and water and sewer systems.Products such as floor,wall and roofing tile,cement,brick,gypsum,sewer pipe,and glass are the buil
47、ding blocks in the world of construction.,Lighting Electrical:,Glass properties of hardness,transparency,and its ability to withstand high temperatures and hold a vacuum at the same time made the light bulb a reality.,Electrical Applications,Electrical properties of ceramics:insulating,semi-conducti
48、ng,superconducting,piezo-electric and magnetic.Products:cell phones,computers,television,other electronic products.Magnetic storage,Communication,Optical fibers:are a reliable conduit for delivering an array of interactive services,using combinations of voice,data and video.,Medical:,Bioceramic mate
49、rials:are used for repair and replacement of human hips,knees,and other body parts.Ceramic materials:can stimulate bone growth,promote tissue formation and provide protection from the immune system.,Environmental and Space Applications,To decrease pollution,capture toxic materials and encapsulate nu
50、clear waste;Catalytic converters in trucks and cars are made of cellular ceramics and help convert noxious hydrocarbons and carbon monoxide gases into harmless carbon dioxide and water.,Advanced ceramics:used in diesel and automotive engines:Its light-weight,high-temperature and wear resistant prope
