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1、A member of NSG Group,2,Application of Inorganic Chemistry in Industry,Flat Glass and Coatings On GlassDr Troy ManningAdvanced Technologist,On-line CoatingsPilkington European Technical CentreHall LaneLathomUKtroy.manningpilkington,3,Outline,Overview of Flat Glass industry and NSG/PilkingtonFlat Gla
2、ss manufactureFloat Glass ProcessCoating technology within the glass industryChemical Vapour DepositionExamples of on line coating applicationsLow Emissivity/Solar ControlSelf CleaningSummarySuggested Reading,4,Global Flat Glass Market,Global Market 37 million tonnes(4.4 billion sq.m)Building Produc
3、ts 33 m tonnes-Automotive 4m tonnesOf which24 million=high quality float glass3 million=sheet2 million=rolled8 million=lower quality float(mostly China)Global Value At primary manufacture level 15 billionAt processed level 50 billion,5,NSG and Pilkington combined,A global glass leader the pure play
4、in Flat GlassCombined annual sales c.4 billionEqual to Asahi Glass in scale,most profitable in Flat GlassOwnership/interests in 46 float lines6.4 million tonnes annual outputWidened Automotive customer base36,000 employees worldwideManufacturing operations in 26 countriesSales in 130+countries,6,Man
5、ufacture of Flat Glass,Four main methodsPlate Glass(1688)molten glass poured on to a flat bed,spread,cooled and polishedSheet Glass(1905)continuous sheet of glass drawn from tank of molten glassRolled Glass(1920)molten glass poured onto to two rollers to achieve an even thickness,making polishing ea
6、sier.Used to make patterned and wired glass.Float Glass(1959)molten glass poured onto bed of molten tin and drawn off in continuous ribbon.Gives high quality flat glass with even thickness and fire polish finish.320 float-glass lines worldwide,7,Melting furnace,Float bath,Cooling lehr,Continuos ribb
7、on of glass,Cross cutters,Large plate lift-off devices,Small plate lift-off devices,Raw material feed,The Float-Glass Process,Operates non-stop for 10-15 years6000 km/year0.4 mm-25 mm thick,up to 3 m wide,8,The Float Glass Process,9,Raw materials,10,Melting Furnace,11,Float Bath,12,Float Glass Plant
8、,13,The Float-Glass Process,Fine-grained ingredients,closely controlled for quality,are mixed to make batch,which flows as a blanket on to molten glass at 1500 C in the melter.The furnace contains 2000 tonnes of molten glass.,After about 50 hours,glass from the melter flows gently over a refractory
9、spout on to the mirror-like surface of molten tin,starting at 1100C and leaving the float bath as a solid ribbon at 600C.,Despite the tranquillity with which float glass is formed,considerable stresses are developed in the ribbon as it cools.,14,Raw Materials,Oxide%in glass Raw material sourceSiO272
10、.2SandNa2O13.4Soda Ash(Na2CO3)CaO8.4Limestone(CaCO3)MgO4.0Dolomite(MgCO3.CaCO3)Al2O31.0Impurity in sand,Feldspar or CalumiteFe2O30.11Impurity in sand or Rouge(Fe2O3)SO30.20Sodium sulphateC0.00Anthracite,15,Raw materials,SiO2Very durable,BUT high melting point(1700C)!+Na2OMelts at a lower temperature
11、,BUT dissolves in water!+CaOMore durable,BUT will not form in bath without crystallisation+MgOGlass stays as a super-cooled liquid in bath,no crystallisation+Al2O3Adds durability+Fe2O3Adds required level of green colour for customer,16,Chemistry of Glass,Important glassmaking chemistry:basic reactio
12、nsNa2CO3+SiO2 1500C Na2SiO3+CO2Na2SiO3+x SiO2 Na2SO4(Na2O)(SiO2)(x+1),Digestion,17,Composition of Glass,18,Structure of Glass,Random network of SiO4-tetrahedral units.Na-O enter Si-O network according to valency Network FormersCa and Mg Network Modifiers make structure more complex to prevent crysta
13、llisation,19,Body-tinted Glass,20,CIE L a*b*colour space,21,CIE L a*b*colour space,22,Functions of a Window,Light in homes,officesLight out shops,museum displaysHeat in heating dominated climatesHeat out cooling dominated climatesCan change properties of glass by applying coatings to the surface,23,
14、Making a window functional-coatings,A wide variety of coating technologies are utilised by the glass industrySpray PyrolysisPowder SprayChemical Vapour DepositionSputter CoatingThermal Evaporation CoatingsSol Gel CoatingsThese are appliedOn Line i.e.as the glass is produced on the float lineOff Line
15、 i.e.coating not necessarily produced at the same location,24,Variations of CVD,Atmospheric Pressure APCVDLow Pressure-LPCVDAerosol Assisted-AACVD Metalorganic MOCVDCombustion/Flame CCVDHot Wire/Filament HWCVD/HFCVDPlasma Enhanced-PECVDLaser Assisted LACVDMicrowave Assisted MWCVDAtomic Layer Deposit
16、ion ALD,25,Chemical Vapour Deposition,26,Chemical Vapour Deposition,Main gas flow region,Gas Phase Reactions,Surface Diffusion,Desorption of Film Precursor,By Products,Diffusion to surface,27,Chemical Vapour Deposition,Animation kindly supplied by Dr.Warren Cross,University of Nottingham,28,CVD proc
17、esses and parameters,29,CVD Precursor Properties,Volatile gas,liquid,low melting point solid,sublimable solidPureStable under transportReact/Decompose cleanly to give desired coating minimise contaminantsCan be single source or dual/multi-source,30,CVD Precursors,Single Source pyrolysis(thermal deco
18、mposition)e.g Ti(OC2H5)4 TiO2+4C2H4+2H2O(400 C)Oxidation e.g SiH4(g)+O2(g)SiO2(s)+2H2(g)Reduction e.g.WF6(g)+3H2(g)W(s)+6HF(g)Dual source e.g.TiCl4(g)+4EtOH(g)TiO2(s)+4HCl(g)+2EtOEt(g),31,Dual Source and Single Source Precursors,32,Transport of Precursors,Bubbler for liquids and low melting solids,D
19、irect Liquid Injection syringe and syringe driver for liquids and solutions Sublimation for solids hot gas passed over heated precursorAerosol of precursor solutions,33,Effect of Temperature on Growth Rate,Independent of temperature,34,Flow conditions,Laminar Flow regime,Turbulent Flow Regime,35,Rey
20、nolds Number,Dimensionless number describing flow conditions,r=Mass density related to concn and partial pressureu=average velocity=viscosityL=relevant length,related to reactor dimensions,If Re 1000 fully turbulent flowReality is between the two extremes,36,Dimensionless Numbers,Reduces the number
21、of parameters that describe a systemMakes it easier to determine relationships experimentallyFor example:Drag Force on a SphereVariables:Force=f(velocity,diameter,viscosity,density)Can be reduced to 2“dimensionless groups”:Drag coefficient(CD)and Reynolds number(Re),37,Dimensionless Numbers,Laminar
22、flow regime,Turbulent flow regime,Experimental values of CD for spheres in fluid flows at various Re,38,Boundary Layer gas velocity,Frictional forces against reactor walls decrease gas velocity,The boundary layer thickness can be estimated from:,39,Boundary Layer-temperature,Contact with hot surface
23、s increases temperature,40,Boundary Layer precursor concentration,Depletion of precursor decreases gas phase concentration,41,Nucleation and Growth,Van der Waals type adsorption of precursor to substrate,Precursors then diffuse across surface,Precursors diffuse across boundary layer to surface,And c
24、an be desorbed back into main gas flow,Or can find low energy binding sites to coalesce into film,Main Gas Flow,42,Nucleation and Growth,43,Growth Mechanisms,(b)Frank-van der Merwe,Layer growth,(c)Stranski-Kastanov,Mixed layered and island,growth,(a)Volmer-Weber,Island growth,44,Thin Film Analysis,M
25、any techniques are used to characterise thin filmsExamples includeXRD crystallinity,phaseXRR layer thickness,layer roughnessSEM/EDX/WDX morphology,thickness,compositionRaman phase,bondingFTIR phase,bondingXPS composition,depth profiling,dopingSIMS composition,depth profiling,dopingAFM roughness,surf
26、ace morphologyTEM crystalline structure,crystal defectsAnalysis of functional properties,45,CVD on Glass,For on-line coating of glass we require:High growth rates required thickness in 2 sStable chemistry uniform coatings for continuous operation for many daysGood adhesion to glassHigh efficiency re
27、duce costs,46,APCVD Strengths and Weaknesses,47,On-Line Coating Positions,Load raw materials,48,Laminar Flow CVD Coater,49,APCVD Applications on Glass,Coating technology allows us to add functionality to glassCoating technology is today used for a variety of productsLow Emissivity coatings to reduce
28、 heating billsSolar Control coatings to reduce solar heat gainTechnical products e.g.TCOs for LCD displays,solar cellsAnti-Reflective ProductsHydrophobic CoatingsSelf Cleaning CoatingsSmart Coatings e.g.electrochromics,thermochromics,photochromics,50,Low-Emissivity Coatings,Designed to reduce heatin
29、g bills,In a double glazed unit,a low-emissivity coating on the inner pane blocks radiative heat trying to escape into the cavity,51,Emissivity,Emissivity is the ratio of radiation emitted by a blackbody or a surface to the theoretical radiation predicted by Plancks law.Surface emissivity is general
30、ly measured indirectly by assuming that e=1-reflectivity,usually at a specified wavelength,52,Solar Spectrum,We have to distinguish between:what comes from the outside to the inside solar spectrumwhat goes from the inside to the outside-heat,Visible light,Infra-Red,UV,53,Outside to Inside,Optimal cu
31、rve for solar control-no UV-all visible light pass-no IR,Optimal curve for low-e-no UV-all visible light pass-all IR pass,54,Inside to Outside No Glazing,55,Inside to Outside Low-e Coated Glass,Low emissivity coated products limit the black body radiation i.e.the energy losses through the window:K-G
32、lass e=0.15,56,Transparent Conducting Oxides,Doped metal oxides displaying n-type conductivityF-substitutes for O2-in the SnO2 lattice releasing an electron into the conduction band i.e.Sn4+O2-2-xF-xe-xClose to metallic conductivity(15 W/)can be achieved but with high optical transmittance(band gap
33、4 eV),C.G.Granqvist,Adv.Mater.,2019,15,1789-1803,57,CVD of SnO2:F,SnCl4+H2O+HF SnO2:F+HCl(1.5 at%F)Much gas phase reactionGases introduced separately in turbulent flow regimeVery high growth rates 100 nm/s possibleLow precursor efficiency 10%,SiCxOy(70 nm),SnO2:F(350 nm),Glass,SiH4+C2H4+CO2 SiCxOy+H
34、2O+other by-productsUsed as colour suppression and barrier layer,58,Low Emissivity Coating,Generally based on SnO2:F(Transparent Conductive Oxide)SiCO under layer used as colour suppressant,59,Low-E and Solar Control Coatings,60,Self-Cleaning Glass,Two mechanisms:Super hydrophilicityPhotocatalytic d
35、egradation of organic matter.TiO2 coating,61,Superhydrophilicity,Oxygen vacancies,O,H,O,O,O,O,H,H,H,2,O,(,O,H,-,H,+,),Water droplets,Uniform water film,UV illumination time,Contact angle,o,o,o,o,o,o,o,dark,UV,62,Photocatalytic Activity,Ultra band gap irradiation of TiO2 Generation of electron hole i
36、n valence bandHole migrates to the surface and results in oxidation of organic material,63,Semi-conductor Photocatalysis,A.Mills,S Le Hunte,J.Photochem.Photobiol A,2019,108,1-35.,64,CVD of ActivTM,SiO2(30 nm),TiO2(17 nm),Glass,SiH4+O2+C2H4 SiO2+by-productsUsed as barrier layer to prevent diffusion o
37、f Na ions into TiO2 layer,TiCl4+EtOAc TiO2+HCl+organic by-products,Laminar Flow regimeReasonable growth rates and precursor efficiency,65,ActivTM,66,ActivTM,67,ActivTM,68,Superhydrophilicity,15 mins UV Exposure,30 mins UV Exposure,45 mins UV Exposure,Before UV Exposure,69,Photocatalytic Effect,UV-Ab
38、sorptionO2-OH*,Organic Soil,H2O+CO2,Glass,Barrier Layer,TiO2-Layer,70,Photocatalytic Effect,The photoactivity of the coating can be measured by monitoring the decomposition of a standard contaminant A thin film of stearic acid(n-octadecanoic acid,200)is applied from a methanol solution onto the coat
39、ingStearic acid used as a typical organic contaminantFTIR(Fourier transform infra-red spectroscopy)used to detect C-H stretch of stearic acidC-H absorption intensity measured after varying UV exposure,71,Stearic Acid Decomposition,C-H Absorption Zero UV exposure,C-H Absorption 60 mins UV exposure,UV
40、 0.77W/m2 340nm,72,Pilkington ActivTM,73,Summary,Scale of the Global Flat Glass IndustryManufacturing Flat Glass Float Glass ProcessCoating Glass Chemical Vapour DepositionExamples of commercial glazing coatings prepared by CVD,74,Recommended Reading,D.W.Sheel and M.E.Pemble Atmospheric Pressure CVD Coatings on Glass,ICCG4 2019 cvdtechnologies.co.uk/CVD%20on%20Glass.pdfM.L.Hitchman,K.F.Jensen Chemical Vapor Deposition Academic Press,1993W.S.Rees,CVD of Non-metals,VCH,Weinheim,2019 M.Ohring The Materials Science of Thin Films,Academic Press,2019pilkington,First in Glass,谢谢你的阅读,知识就是财富丰富你的人生,
