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1、Introduction to Materials,Ch.4,Glass,重庆理工大学材料科学与工程学院,材料概论,Introduction to Materials,1,2,Most time,we did not realize,Can you count how many things in this classroom that are made from glass?,3,We see,4,We did not see,5,Glass is so important to us,So,What is the glass constituted of?(玻璃的主要组份)How is t
2、he glass classified?(玻璃的分类)How is the glass work made?(玻璃的制备方法)What are the properties of glass?(玻璃的性质)What is the structure of glass?(玻璃的结构)What are the major applications of glass?(玻璃的主要用途)New types of glass and new applications?(新型玻璃和玻璃的新用途),6,Contents,The world of glassPreparation of glassStruct
3、ure and propertiesApplications of glassOptoelectronics materials(光电材料),1.掌握玻璃的主要类型2.了解玻璃的主要用途3.学习玻璃的生产工艺4.熟悉玻璃的结构和性质5.了解光电转换材料的最新进展,课程学习目的,7,Part I:The world of glass,Section 1.1:Introduction,8,Definition of glass玻璃的定义,Glass is an inorganic product of fusion which has cooled to a rigid condition wit
4、hout crystallization ASTM 1949熔体在冷却过程中粘度逐渐增大而得的不结晶的固体材料。汉语大词典,9,Features of glass玻璃的通性,Lack of the periodic(long range)order of a crystalInfinite unit cell(no repeating large scale structures)3D network lacking symmetry and periodicityISOTROPIC 各向同性:same properties in all directionsMetastability 介稳性
5、能Compared to its crystalline form无固定熔点(no fixed melting temp.)Can be either solid or liquid/viscosity(粘度)性质变化的连续性与可逆性Continuous and reversible(可逆的)changes,10,Natural glass(1),The volcanic outflow(火山喷发)of the molten magma(岩浆)get cooled and form glasses.,11,Natural glass(2),Impactites(击变岩)are natural
6、glasses formed from crystalline materials rendered amorphous by the shock of meteoric(陨石)impact.Glasses formed from impacted melts are known as tektites(玻陨石),Moldavite(绿玻陨石).,12,Major applications of industrial glass工业玻璃的主要用途,Now commonly applied for:Containers(容器)WindowsDecoration（装饰品）Lenses(镜头)Fib
7、erglass(玻璃纤维)Optical fiber(光导纤维)Road signsCompositesinfrared detector（红外探测器）,13,A brief history of glass,According to the methods of the manufacturing process:The First Period:1700 BC through 100 ADPrimitive method of making glass using molds.The Second Period:100 AD through 400-500 ADGlassblowing t
8、echnique discovered,and glass manufacture becomes a more practical process.The Third Period:400-500 AD 1200 ADMiddle Ages,characterized by Byzantine glass.The Fourth Period:1200 AD 1900 ADVenetian glass,foundation for modern glass making is set.The Fifth Period:1900 AD presentGlass objects used as e
9、veryday goods;large scale manufacturing.,14,玻璃历史的简短介绍,人类应用玻璃的历史根据生产工艺的不同可以分为以下几个阶段:公元前1700 到 公元后100年 用模子进行原始的玻璃生产 公元100年 到 400-500人类发明了吹制玻璃的工艺 400-500 到 1200 欧洲的中世纪，拜占庭玻璃占据主流地位 1200 AD 到 1900威尼斯玻璃工艺占据主导地位，现代玻璃制造工业开始成形 1900 AD 到 现在玻璃成为日用品原材料的一种，大规模工业化生产日益普遍,Romancage cup from the 4th centuryCE,15,Gre
10、at events in the history of glass,DatePlace and Activity650 BC1st Glassmaking handbook1,200 AD Venice glass威尼斯center dominates in glass production1,590Glass telescope and microscope lenses are developed in Netherlands荷兰 and used for the first time1,609Galileo Galilei uses telescope to investigate pl
11、anetary motion,16,Great events in the history of glass,1,665 Hall of mirrors in Versailles is built 凡尔赛宫（1682-1789）,Bohemian波西米亚 flashed and engraved ruby glass(19th-century),Roman glass amphoriskoi 1st2nd century AD,18,Great events in the history of glass,1875 Technical glasses are developed in Ger
12、many by Carl Zeiss at Jena,Germany becomes a major glass science and engineering center.1926Arthur Wood and David Gray of Corning Glass Works develop the“399”machine,later called the“Ribbon”machine to make light bulbs at speeds of 1000 per minute.,19,Great events in the history of glass,1932William
13、Zachariasen publishes the“Random Network Hypothesis”of glass structure and his rules of glass formation in J.Amer.Chem.Society1959 Pilkington Brothers patent the float glassprocess and introduced in England and will ultimately revolutionize flat glass manufacturing.19701st silica optical fiber produ
14、ced at Corning Glass Works using chemical vapor deposition（CVD化学气相沉积）techniques to reduce attenuation(衰减)and improve signal transmission,20,Classification of glasses according to compositions玻璃的分类:按成份分,Oxide glassesChalcogenide Glasses(硫属化物玻璃)Thioborate glasses(B2S3)(硫硼玻璃)Halide glasses(BeF2,ZnCl2 e
15、tc.)(卤化物玻璃)Heavy metal fluoride glasses(ZrF4)(重金属氟化玻璃)Oxy-halide glasses(氧卤玻璃)Oxynitride glasses(氧氮玻璃)Metallic glasses(金属玻璃)Glass-like Carbon(玻璃碳),特种玻璃是指除日用玻璃以外的、采用精制、高纯或新型原料，或采用新工艺在特殊条件下或严格控制形成过程制成的一些具有特殊功能或特殊用途的玻璃，也包括经玻璃晶化获得的微晶玻璃。（1）使玻璃具有特殊的功能；（2）将常规特性发挥至极点；（3）将上述某项特性以另一种特性置换；（4）牺牲上述某些性能而赋予某项有用的特性
16、。,21,Oxide glass,More than 90%of the glass in use is based on oxides and in particular silica.Silica and silicate glasses(硅酸盐玻璃）B2O3 and borate glasses(硼酸盐玻璃）GeO2 and germanate glasses（锗酸盐玻璃）P2O5 and phosphate glasses（磷酸盐玻璃）Complex oxide glasses,22,Common oxide glasses,Vitreous Silica-SiO2Compositio
17、n:SiO2Very expensiveUses:Low expansion chemically resistant tubingLight bulbs where UV transparency andhigh temperature limit is necessaryUltra-low loss telecommunication optical fiberLow expansion mirrors and mirror blanks,23,Common oxide glasses,Soda-Lime-Silicate Glass(钠钙玻璃)Composition:10-15 Na2O
18、+5-15 CaO+50-70 SiO2Uses:Windows,bottles,containers,fibers,mirrors,lenses,tableware,light bulbs,etc.,24,Common oxide glass,Borate silicate glass(硼硅玻璃)Composition:SiO2+B2O3+Al2O3+Na2O+K2OUses:Pyrex glass(派勒克斯耐热玻璃)Chemical laboratory equipment CookwareLightingSpecial windows.,25,Classification of glas
19、s according to applications,Plate glass Generally plate glass comes in two thicknesses,inch and 1/8 inch.Can be polished or float glass.Tempered glass(钢化玻璃)Heated on both sides and cooled rapidly with a stream of air.This causes the outside to compress rapidly and place tension on the inside of the
20、glass.Approximately four times stronger than untempered glass.Breaks in small pieces.Used for car windows,shower doors,windows in public buildings.Laminated glass(夹层玻璃)Made by placing a piece of plastic between two layers of glass.Main use is for windshields and bulletproof glass.Container glassBlow
21、n at 600 800 celsius.Contain very little ironRefractive index can vary from top to bottom of bottle.Annealing will raise the refractive index,26,Part II:Preparation of Glasses,Section 2.1:Introduction,27,Glass Manufacturing,Four Market SegmentsContainer GlassFloat(Flat Glass)Fiber GlassSpecial Glass
22、,28,Key Factors Affecting the Glass Industry,Technology Advances Manufacturing advancesNew product advancesEnvironmental Regulations NOx,SOx regulationsIndustry Restructuring Plant and Manufacturers mergersEnergy costs and availabilitySource,purity,costs,regulation etc.,29,Scheme of common glass pro
23、duction,Material proportioning,Distributing,30,Chemical Nature of Glass Forming Materials,Glasses have been made from elements,simple chemical compounds,complex organic molecules,salt mixtures and alloys.Role of oxides in glassGlass formers:B2O3,SiO2,GeO2,P2O5,Al2O3Intermediates:TiO2,ZnO,PbOGlass mo
24、difiers:Li2O,Na2O,K2O,MgO CaOThe key factor in the preparation of glasses is how fast the melt can be quenched.,31,Question,Will oxides below form glass?,65%CaO+20%Na2O+15%MgO,32,辅助原料,是使玻璃获得某些必要性质和加速熔制过程的原料，根据作用的不同，分为：澄清剂：加入玻璃配合料或玻璃熔体中，在高温下分解或气化形成气体以促进玻璃液中气泡排除的物质。助熔剂：能促使玻璃熔制过程加速的原料。着色剂：是使玻璃着色的物质。根据着
25、色剂在玻璃中呈现的状态，可分为离子着色剂，硫、硒化合物类分子着色剂和金属胶体着色剂三大类。脱色剂：是指能减弱铁及其它杂质离子或化合物对玻璃着色影响的物质。主要是消除Fe2+的着色。又分为物理脱色剂和化学脱色剂两大类。乳浊剂：是指在玻璃中的溶解度不大，随着温度下降，重新以微粒状从玻璃中析出，使玻璃产生乳浊现象的物质。氧化剂及还原剂：是在熔制玻璃时能释放出或夺取氧的物质。可以形成氧化或还原的熔制条件。,33,对混合料的质量要求,保证配合料的质量要求是加速玻璃熔制和提高玻璃质量，防止产生缺陷的基本措施，对配合料的主要要求是：构成配合料的各种原料均应有一定的粒度组成，即同一种原料应有适宜的粒度，不同原
26、料间保持一定的粒度比，以保证配合料的均匀度、熔制速度、玻璃液均匀度，提高混合质量，防止配合料的分层。配合料中应具有一定水分，使水在石英颗粒原料表面上形成水膜，5%的纯碱和芒硝溶于水膜中，有助于加速熔化。为了有利于玻璃液的澄清和均化，配合料需有一定的气体率。对钠钙硅酸盐玻璃，气体率为15%20%。必须混合均匀，以保证玻璃液的均匀性。,34,Melting of glass,The process of firing the pre-mixed admixture of raw materials and forming the homogenous glass melt.Melting of g
27、lass is a complex process involving a serial of physical and chemical changesThe result of these changes is to turn the raw materials into a complex glass meltThe melting process of glass can be divided into five stages called:formation of silicates,melting,fining,homogenization(均化)and cooling.,35,S
28、tructural approach to glass formation,Glass Formation results whenLiquids are cooled to below Tg sufficiently fast to avoid crystallizationNucleation of crystalline seeds are avoidedGrowth of Nuclei into crystallites(crystals)is avoidedLiquid is“frustrated”by internal structure that hinders both eve
29、nts,36,Forming of glass玻璃的成形与定形,玻璃的成形是指熔融的玻璃液转变为具有固定几何形状制品的过程。玻璃必须在一定的温度范围内才能成形。在成形时，玻璃液除作机械运动之外，还同周围介质进行连续热传递。由于冷却和硬化，玻璃首先由粘性液态转变为可塑态，然后再转变脆性固态。因此，玻璃的成形过程是极其复杂的多种性质不同作用的综合。其中，机械的和热的作用具有重要的意义。玻璃制品的成形过程和其它塑性材料相同，分为成形和定形两个阶段。第一阶段是赋予制品一定的几何形状，第二阶段是把制品的形状固定下来，玻璃的成形和定形是连续进行的，定形实际是成形的延续。定形所需要的时间比成形时间要长。决定
30、成形阶段的因素：流变性，即粘度表面张力弹性及其与温度的变化特征决定定形阶段的因素：热性质硬化速度,37,Major forming techniques,Blowing 吹制法Compression 压制法Drawing 拉制法Floating method 浮法 float glassRolling 压延法Casting 浇铸法,38,Forming of glass with blowing method,suspended,Parison,Finishing,mold,Compressed,air,39,Forming of glass with blowing method,40,Fo
31、rming of glass with compression method,Gob（滴料）,Parison,mold,41,Production of glass plates,Originally,glass plates made one at a time using the Pittsburgh匹兹堡process(vertically垂直地draw a continuous sheet of glass of a consistent 连续一致width from the tank).,42,Production of float glass,Originally able to
32、make only 6mm thick glass,now made as thin as 0.4mm and as thick as 25mm.There are around 260 float plants worldwide with a combined output of about 800,000 tonnes of glass a week.A float plant,which operates non-stop for between 11-15 years,makes around 6000 kilometres of glass a year.,43,The float
33、ing part,Molten glass,at approximately 1000C,is poured continuously from a furnace onto a shallow bath of molten tin.It floats on the tin,spreads out and forms a level surface.Thickness is controlled by the speed at which solidifying glass ribbon is drawn off from the bath.After annealing(controlled
34、 cooling)the glass emerges as a fire polished product with virtually parallel surfaces.,44,The tin bath,45,Forming thinner ribbons,46,Forming thicker ribbons,47,Annealing of glass,Annealing,in glassblowing and lampworking,is the process of heating,and then slowly cooling glass to relieve internal st
35、resses消除玻璃制品在成形或热加工后残留在制品内的永久应力的过程称为退火。,48,Annealing of Glass,Flat glass must be annealed to free of strain so that it can be cut straight and easily平板玻璃必须通过退火来消除应力，以利直线切割Containers and pressed ware must be free of stresses so that they dont spontaneous fail under pressure容器玻璃和受压器皿必须消除自身应力以避免在压力作用下突
36、然破坏Optical glasses must be free of stresses that change the index of refraction光纤玻璃必须消除自身应力以避免折射率的变化,Why is there stress in glass?,Temperature gradients across glass wall thickness produces different cooling rates玻璃沿厚度方向温度的梯度将会引起冷却速度的不同Different cooling rates produce different times at which the gla
37、ss undergoes the glass transition由于冷却速度的不同，不同部位发生转变的时间也不同Surfaces cool more quickly,bulk cools more slowly表面冷却更快，而内部冷却更慢,49,50,Annealing of Glass,Annealing is to heat treat glass near the softening point to relieve stressesThen to cool more slowly back through the transition region so as to not rein
38、troduce thermal stressesAnnealing takes time and temperatureThicker glass anneals more slowly,has larger stressesThinner glass anneals more quickly,has smaller stressesGlass with large thermal expansion requires more annealing,51,Preparation of special glass,Sol-gel method 溶胶凝胶法The method is based o
39、n the phase transformation of a sol(a solution containing particles in suspension)is polymerized at low temperatureto form a wet gel,which is going to be densified through a thermal annealing to give an inorganic product like a glass or a dry gel.,52,Preparation of special glass,气相法该方法是以气体作原料，或者是将固体
40、原料气化成气体，再加热发生化学反应而制备玻璃或非晶态物质的方法。该方法主要用于光纤预制棒的制造，也用于光掩模基板等的制造。,53,Structural Approach to Glass Formation,54,Structural Approach to Glass Formation,1932William Zachariasen publishes the“Random Network Hypothesis”of glass structure and his rules of glass formation in J.Amer.Chem.Society,Structural Appr
41、oach to Glass Formation,Glass Formation results whenLiquids are cooled to below TM(TL)sufficiently fast to avoid crystallizationNucleation of crystalline seeds are avoidedGrowth of Nuclei into crystallites(crystals)is avoidedLiquid is“frustrated”by internal“structure that hinders both events,55,56,K
42、inetic approach to glass formation,All liquids can be made into the glassy stateThe question is how fast must the liquid be cooled?Fast quenching,100oC/sec,implies“strong”glass forming abilitySlow cooling,1oC/min,implies“marginal”glass forming abilityThe critical cooling rate,Rc,measures how fast a
43、liquid must be cooled,57,Can liquid water be quenched into class?,58,The kinetic approach to glass formation,What is the Rc value for a particular liquid?If Rc 100oC/sec,then the liquid is a poor glass formerIf Rc is 1oC/min,then the liquid is a good glass former,59,Properties of Glass,The glass tra
44、nsitionThe glass transition is the region of temperatures where the properties of a cooled liquid continuously change from being“liquid-like”to“solid-like”Structure is continuous with the liquid stateProperties are continuous with the liquid stateYet,the Glass Transition occurs over a relatively nar
45、row range of temperatures and can be a“sharp”transition in some cases,60,The glass transition,The glass transition results from the slowing down of the internal relaxation time necessary to achieve equilibrium properties as the temperature is loweredRapidly rising viscosity and the associated viscos
46、ity relaxation time are at root of the slowing down of the liquids response to temperature changeMost liquids have a weakly temperature dependent viscosityGlass forming liquids have a strongly temperature dependent viscosity,What is the viscosity?,Elastic solids deform elastically when stressedThey
47、relax back to their original state when stress is releasedElastic modulus is the proportionality constants=EeLiquids have no restoring forceThey have no Elastic modulusIt does require force to move the liquid thoughRate of strain,Stress=viscosity strain rate,61,Area A,Force,F,Viscosity:Shear stress
48、required to produce fixed strain rate:The higher the viscosity The higher the required stress,Velocity,62,Temperature dependence of viscosity,Soda lime glass as a common exampleViscosity decreases rapidly above the annealing point,TgDecreases less rapidly at higher temperatures,63,Phase separation(分
49、相):,Nucleation(成核)and Growth Spinodal Decomposition(螺旋线分解),64,Why is phase separation so important?,Materials properties change and become non-uniformOptical properties,transparency,are dramatically degradedElectrical properties can change from insulating to conductingAppearance can change from clea
50、r and colorless to dark and absorbingProcessing can become difficult due to second high temperature liquid phase being createdGeneral overall behavior of glass changes,65,Properties of glass,Density The density of most glasses is dependent upon its thermal history and decreases with temperatureGlass
