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Challenges in fabricating large-area metallic materials for energy economyPaul H. Steenphs7@cornell.eduNSF CMMI Workshop 2011Atlanta, GA

Chemical & Biomolecular EngineeringCornell University

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energy economy enters in a) the fabrication process and by the end-application energy-saving benefits. In this talk, be energy economy, we mean the energy economy provided by the end-product although the energy consumed in fabrication is important (as is life-cycle issues) E.g. for an Oerlikon Solar PV module, energy pay-back time is down to 1 year -- this for an end-product that will operate for 25-30 years. For Metglas, Amorphous Metal Distribution transformers operate even longer.

What do me mean by large-area? OS produces 2300 m^2/day of PV modules (more than half a foot-ball field per day). Metglas fabricates ribbon per day.1

energy economy solar energy at earths surface =1 10,000 X energy consumption of all humanity

11.9 Quad energy (electrical) consumed USA (2002) 26.3 Quad energy losses (2002)

1 Quad = 278,000 GW-h = 278 TW-h

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energy economy grid losses1 Quad = 278 TW-h

Hours in year: 24x365 = 8,760 h1.6 GW power plant x 1 year = 1.6 x 8,760 GW-h = 14,016 GW-h = 0.05 Quad3

energy economy grid losses

distributed

electricity31.2distribution(steel transformer)electrical

energy100heat68.8

1 Quad = 278 TW-h

Hours in year: 24x365 = 8,760 h1.6 GW power plant x 1 year = 1.6 x 8,760 GW-h = 14,016 GW-h = 0.05 Quad4

Source: Metglas sales literaturemetallic glass transformer cores

infrared images of transformerscrystalline core

amorphous metal coremicro-structure

33.8 TW-h energy (electrical) DT losses USA (2004) 27.0 TW-h potential savings by Amorphous Metal DT

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Source: PowerSource Summer 2007Metglas Conway, SC

EAS

amorphous core

power- distribution transformer (DT)

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Metglas fabrication

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Metglas challenge cast new ultra-efficient nano-crystalline alloys deeper understanding of fundamentals: high-speed contacting, solidification, transport

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example: fundamentals & product quality

Cornell: planar-flow spin-castingsurface tensionContact Zone9

high-speed contacting texture

Cast direction5 cm Wheel side Air side

C.J. Byrne et al., Capillary puddle vibrations linked to casting-defect formation in planar-flow melt spinning, Met. & Mat. Trans. B, 36B, pp. 445-456, 2006 10

origin of texture surface tension vs inertia

natural frequency: plucked liquid sphere (Rayleigh oscillation)

surface tensionC.J. Byrne et al., Capillary puddle vibrations linked to casting-defect formation in planar-flow melt spinning, Met. & Mat. Trans. B, 36B, pp. 445-456, 2006 11

BL Cox, in preparationexample: controlling texture

10 cm5 cm0.12 cm0.012 cm

Rounded Edge

Sharp Edge

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example: manipulating textureUS Patent 7,306,025 2007, Methods for continuous casting of a molten material US Patent 7,082,986 2006, PH Steen A system . . . for continuous casting . . .

5 cmBN Patterned Ribbon

Write-headErase-headRibbonContact zoneOverhead Pressure

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example: manipulating texture

LaserLensPrismByrne, CJ, et al., In-situ manipulation of cooling rates during planar-flow melt spinning processing, Mat. Sci. & Eng. A. 459, 172-181, 2007.14

photo-voltaic (PV) cell the sandwich

Source: Surek (2005)learning curve grid-parity goal

Source: RGS presentation

fabrication path

Source: OS Media Conference EU PVSEC 2010 Valencia, Spain 9/7/2010

Oerlikon Solar architecture thin-film bi-junctionMedia ConferenceEU PVSEC 2010Valencia, Spain9/7/2010 OS18

Source: http://www.oerlikon.com/solar/Oerlikon Solar (OS) batch fabricationMicromorph +TCO + front

plasma-enhancedchemical vapor deposition (PECVD)TCO +front glassStep 1Step 2back contact + Mm + TCO + front

laser processing (LSS laser)Micromorph + TCO +front glassStep 3

TCO +front glass

front glasslow-pressurechemical vapor deposition (LPCVD)

OS ThinFab manufacturing

Source: http://www.oerlikon.com/solar/thinfab/ 9/2010Source1: OS ThinFab FactSheetSource2: OS Media Conference EU PVSEC 2010 Valencia, Spain 9/7/2010

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OS challenges market ThinFab, increase efficiency & innovate

fend-off competing technological alternatives

deeper understanding of fundamentals: high-speed deposition, laser surface-processing

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RGS: alternative fabrication strategy

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RGS continuous-casting of Si wafer

RGS: area rate = 1,350 m^2/day. 23

RGS challenges achieve quality while maintaining productivity deeper understanding of fundamentals: high-speed contacting, polycrystalline seeding and solidification

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Ack: NSF CMMI 07278613; Metglas; RGS; Alcoasummary: fabrication science our challenge! deeper understanding needed of fundamentals of high-speed contacting lubrication laser-processing solidification transport metrology

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gassolid 1liquidinterfacesInterfaces: liquid/solid; gas/liquid/solid; gas/liquid/solid I/solid II; acknowledgements25