Pilkington浮法玻璃生产介绍

nullnullApplication of Inorganic Chemistry in IndustryApplication of Inorganic Chemistry in IndustryFlat Glass and Coatings On Glass Dr Troy Manning Advanced Technologist, On-line Coatings Pilkington European Technical Centre Hall Lane Lathom UK troy.manning@pilkington.comOutlineOutlineOverview of Flat Glass industry and NSG/Pilkington Flat Glass manufacture Float Glass Process Coating technology within the glass industry Chemical Vapour Deposition Examples of on line coating applications Low Emissivity/Solar Control Self Cleaning Summary Suggested ReadingGlobal Flat Glass MarketGlobal Flat Glass MarketGlobal Market  37 million tonnes (4.4 billion sq. m) Building Products 33 m tonnes - Automotive 4m tonnes Of which 24 million = high quality float glass 3 million = sheet 2 million = rolled 8 million = lower quality float (mostly China) Global Value At primary manufacture level  €15 billion At processed level  €50 billion NSG and Pilkington combinedNSG and Pilkington combinedA global glass leader – the pure play in Flat Glass Combined annual sales c. £4 billion Equal to Asahi Glass in scale, most profitable in Flat Glass Ownership/interests in 46 float lines 6.4 million tonnes annual output Widened Automotive customer base 36,000 employees worldwide Manufacturing operations in 26 countries Sales in 130+ countriesManufacture of Flat GlassManufacture of Flat GlassFour main methods Plate Glass (1688) – molten glass poured on to a flat bed, spread, cooled and polished Sheet Glass (1905) – continuous sheet of glass drawn from tank of molten glass Rolled Glass (1920) – molten glass poured onto to two rollers to achieve an even thickness, making polishing easier. 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 worldwideThe Float-Glass ProcessMelting furnaceFloat bathCooling lehrContinuos ribbon of glassCross cuttersLarge plate lift-off devicesSmall plate lift-off devicesRaw material feedThe Float-Glass ProcessOperates non-stop for 10-15 years 6000 km/year 0.4 mm-25 mm thick, up to 3 m wideThe Float Glass ProcessThe Float Glass ProcessRaw materialsRaw materialsMelting FurnaceMelting FurnaceFloat BathFloat BathFloat Glass PlantFloat Glass PlantThe Float-Glass ProcessThe Float-Glass ProcessFine-grained ingredients, closely controlled for quality, are mixed to make batch, which flows as a blanket on to molten glass at 1500 ºC in the melter. The furnace contains 2000 tonnes of molten glass.After about 50 hours, glass from the melter flows gently over a refractory spout on to the mirror-like surface of molten tin, starting at 1100ºC and leaving the float bath as a solid ribbon at 600ºC. Despite the tranquillity with which float glass is formed, considerable stresses are developed in the ribbon as it cools. Raw MaterialsRaw MaterialsOxide % in glass Raw material source SiO2 72.2 Sand Na2O 13.4 Soda Ash (Na2CO3) CaO 8.4 Limestone (CaCO3) MgO 4.0 Dolomite (MgCO3.CaCO3) Al2O3 1.0 Impurity in sand, Feldspar or Calumite Fe2O3 0.11 Impurity in sand or Rouge (Fe2O3) SO3 0.20 Sodium sulphate C 0.00 AnthraciteRaw materialsRaw materials SiO2 Very durable, BUT high melting point (>1700°C)! + Na2O Melts at a lower temperature, BUT dissolves in water! + CaO More durable, BUT will not form in bath without crystallisation + MgO Glass stays as a super-cooled liquid in bath, no crystallisation + Al2O3 Adds durability + Fe2O3 Adds required level of ‘green’ colour for customerChemistry of GlassChemistry of GlassImportant glassmaking chemistry: basic reactions Na2CO3 + SiO2 1500ºC Na2SiO3 + CO2 Na2SiO3 + x SiO2 Na2SO4 (Na2O)(SiO2)(x+1) DigestionComposition of GlassComposition of GlassStructure of GlassStructure of GlassRandom network of [SiO4]- tetrahedral units. Na-O enter Si-O network according to valency – Network Formers Ca and Mg – Network Modifiers – make structure more complex to prevent crystallisation Body-tinted GlassBody-tinted GlassCIE L a* b* colour spaceCIE L a* b* colour spaceCIE L a* b* colour spaceCIE L a* b* colour spaceFunctions of a WindowFunctions of a WindowLight in – homes, offices Light out – shops, museum displays Heat in – heating dominated climates Heat out – cooling dominated climates Can change properties of glass by applying coatings to the surfaceMaking a window functional - coatingsMaking a window functional - coatingsA wide variety of coating technologies are utilised by the glass industry Spray Pyrolysis Powder Spray Chemical Vapour Deposition Sputter Coating Thermal Evaporation Coatings Sol Gel Coatings These are applied On Line i.e. as the glass is produced on the float line Off Line i.e. coating not necessarily produced at the same locationVariations of CVDVariations of CVDAtmospheric Pressure – APCVD Low Pressure - LPCVD Aerosol Assisted - AACVD Metalorganic – MOCVD Combustion/Flame – CCVD Hot Wire/Filament – HWCVD/HFCVD Plasma Enhanced - PECVD Laser Assisted – LACVD Microwave Assisted – MWCVD Atomic Layer Deposition – ALD Chemical Vapour DepositionChemical Vapour DepositionChemical Vapour DepositionChemical Vapour DepositionMain gas flow regionGas Phase ReactionsSurface DiffusionDesorption of Film PrecursorBy ProductsDiffusion to surface Chemical Vapour DepositionChemical Vapour DepositionAnimation kindly supplied by Dr. Warren Cross, University of NottinghamCVD processes and parametersCVD processes and parametersCVD Precursor PropertiesCVD Precursor PropertiesVolatile – gas, liquid, low melting point solid, sublimable solid Pure Stable under transport React/Decompose cleanly to give desired coating – minimise contaminants Can be single source or dual/multi-sourceCVD PrecursorsCVD PrecursorsSingle Source – pyrolysis (thermal decomposition) e.g Ti(OC2H5)4  TiO2 + 4C2H4 + 2H2O (>400 ºC) 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)Dual Source and Single Source PrecursorsDual Source and Single Source PrecursorsTransport of PrecursorsTransport of PrecursorsBubbler for liquids and low melting solids Direct Liquid Injection – syringe and syringe driver for liquids and solutions Sublimation for solids – hot gas passed over heated precursor Aerosol of precursor solutionsEffect of Temperature on Growth RateEffect of Temperature on Growth RateIndependent of temperatureFlow conditionsFlow conditionsLaminar Flow regimeTurbulent Flow RegimeReynolds NumberReynolds NumberDimensionless number describing flow conditions r = Mass density related to concn and partial pressure u = average velocity = viscosity L = relevant length, related to reactor dimensionsIf Re < 10  Laminar flow If Re >> 1000  fully turbulent flow Reality is between the two extremesDimensionless NumbersDimensionless NumbersReduces the number of parameters that describe a system Makes it easier to determine relationships experimentally For example: Drag Force on a Sphere Variables: Force = f (velocity, diameter, viscosity, density) Can be reduced to 2 “dimensionless groups”: Drag coefficient (CD) and Reynolds number (Re)Dimensionless NumbersDimensionless NumbersLaminar flow regimeTurbulent flow regimeExperimental values of CD for spheres in fluid flows at various ReBoundary Layer – gas velocityBoundary Layer – gas velocityFrictional forces against reactor walls decrease gas velocity The boundary layer thickness can be estimated from:Boundary Layer - temperatureBoundary Layer - temperatureContact with hot surfaces increases temperatureBoundary Layer – precursor concentrationBoundary Layer – precursor concentrationDepletion of precursor decreases gas phase concentrationNucleation and GrowthNucleation and GrowthVan der Waals type adsorption of precursor to substratePrecursors then diffuse across surfacePrecursors diffuse across boundary layer to surfaceAnd can be desorbed back into main gas flowOr can find low energy binding sites to coalesce into filmMain Gas FlowNucleation and GrowthNucleation and GrowthGrowth MechanismsGrowth Mechanisms(b) Frank - van der MerweLayer growth(c) Stranski - KastanovMixed layered and island growth(a) Volmer - WeberIsland growthThin Film AnalysisThin Film AnalysisMany techniques are used to characterise thin films Examples include XRD – crystallinity, phase XRR – layer thickness, layer roughness SEM/EDX/WDX – morphology, thickness, composition Raman – phase, bonding FTIR – phase, bonding XPS – composition, depth profiling, doping SIMS – composition, depth profiling, doping AFM – roughness, surface morphology TEM – crystalline structure, crystal defects Analysis of functional propertiesCVD on GlassCVD on GlassFor on-line coating of glass we require: High growth rates – required thickness in <2 s Stable chemistry – uniform coatings for continuous operation for many days Good adhesion to glass High efficiency – reduce costs APCVD Strengths and WeaknessesAPCVD Strengths and WeaknessesOn-Line Coating PositionsOn-Line Coating PositionsLoad raw materialsLaminar Flow CVD CoaterLaminar Flow CVD CoaterAPCVD Applications on GlassAPCVD Applications on GlassCoating technology allows us to add functionality to glass Coating technology is today used for a variety of products Low Emissivity coatings to reduce heating bills Solar Control coatings to reduce solar heat gain Technical products e.g. TCO’s for LCD displays, solar cells Anti-Reflective Products Hydrophobic Coatings Self Cleaning Coatings Smart Coatings e.g. electrochromics, thermochromics, photochromicsLow-Emissivity CoatingsLow-Emissivity CoatingsDesigned to reduce heating billsIn a double glazed unit, a low-emissivity coating on the inner pane blocks radiative heat trying to escape into the cavity EmissivityEmissivityEmissivity is the ratio of radiation emitted by a blackbody or a surface to the theoretical radiation predicted by Planck’s law. Surface emissivity is generally measured indirectly by assuming that e = 1 - reflectivity, usually at a specified wavelength Solar SpectrumSolar SpectrumWe have to distinguish between : what comes from the outside to the inside – solar spectrum what goes from the inside to the outside - heatVisible lightInfra-RedUVOutside to InsideOutside to InsideOptimal curve for solar control - no UV - all visible light pass - no IROptimal curve for low-e - no UV - all visible light pass - all IR passInside to Outside – No GlazingInside to Outside – No GlazingInside to Outside – Low-e Coated GlassInside to Outside – Low-e Coated GlassLow emissivity coated products limit the black body radiation i.e. the energy losses through the window: K-Glass e=0.15Transparent Conducting OxidesTransparent Conducting OxidesDoped metal oxides displaying n-type conductivity F- substitutes for O2- in the SnO2 lattice releasing an electron into the conduction band i.e. Sn4+O2-2-xF-xe-x Close to metallic conductivity (15 W/€) can be achieved but with high optical transmittance (band gap ~4 eV)C. G. Granqvist, Adv. Mater., 2003, 15, 1789-1803CVD of SnO2:FCVD of SnO2:FSnCl4 + H2O + HF  SnO2:F + HCl (~1.5 at% F) Much gas phase reaction Gases introduced separately in turbulent flow regime Very high growth rates >100 nm/s possible Low precursor efficiency <10%SiCxOy (70 nm)SnO2:F (350 nm)GlassSiH4 + C2H4 + CO2  SiCxOy + H2O + other by-products Used as colour suppression and barrier layerLow Emissivity CoatingLow Emissivity CoatingGenerally based on SnO2:F (Transparent Conductive Oxide) SiCO under layer used as colour suppressantLow-E and Solar Control CoatingsLow-E and Solar Control CoatingsSelf-Cleaning GlassSelf-Cleaning GlassTwo mechanisms: Super hydrophilicity Photocatalytic degradation of organic matter. TiO2 coatingSuperhydrophilicitySuperhydrophilicityOxygen vacanciesOHOOOOHHH2O(OH-, H+)Water dropletsUniform water filmUV illumination timeContact angleooooooodarkUVPhotocatalytic ActivityPhotocatalytic ActivityUltra band gap irradiation of TiO2 Generation of electron hole in valence band Hole migrates to the surface and results in oxidation of organic materialSemi-conductor PhotocatalysisSemi-conductor PhotocatalysisA. Mills, S Le Hunte, J. Photochem. Photobiol A, 1997, 108, 1-35.CVD of ActivTMCVD of ActivTMSiO2 (30 nm)TiO2 (17 nm)GlassSiH4 + O2 + C2H4  SiO2 + by-products Used as barrier layer to prevent diffusion of Na ions into TiO2 layerTiCl4 + EtOAc  TiO2 + HCl + organic by-productsLaminar Flow regime Reasonable growth rates and precursor efficiencyActivTMActivTMActivTMActivTMActivTMActivTMSuperhydrophilicitySuperhydrophilicity15 mins UV Exposure30 mins UV Exposure45 mins UV ExposureBefore UV ExposurePhotocatalytic EffectPhotocatalytic Effect UV-Absorption O2 - OH* Organic SoilH2O + CO2GlassBarrier LayerTiO2 - LayerPhotocatalytic EffectPhotocatalytic EffectThe photoactivity of the coating can be measured by monitoring the decomposition of a standard contaminant A thin film of stearic acid (n-octadecanoic acid, ~200Å) is applied from a methanol solution onto the coating Stearic acid used as a typical organic contaminant FTIR (Fourier transform infra-red spectroscopy) used to detect C-H stretch of stearic acid C-H absorption intensity measured after varying UV exposureStearic Acid DecompositionStearic Acid DecompositionC-H Absorption Zero UV exposureC-H Absorption ~60 mins UV exposure UV 0.77W/m2 @340nmPilkington ActivTMPilkington ActivTMSummarySummaryScale of the Global Flat Glass Industry Manufacturing Flat Glass – Float Glass Process Coating Glass – Chemical Vapour Deposition Examples of commercial glazing coatings prepared by CVD Recommended ReadingRecommended ReadingD.W. Sheel and M.E. Pemble Atmospheric Pressure CVD Coatings on Glass, ICCG4 2002 http://www.cvdtechnologies.co.uk/CVD%20on%20Glass.pdf M.L. Hitchman, K.F. Jensen Chemical Vapor Deposition Academic Press, 1993 W.S. Rees, CVD of Non-metals, VCH, Weinheim, 1996 M. Ohring The Materials Science of Thin Films, Academic Press, 2001 www.pilkington.comnull