Konys, J.

English

KITopen

KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz AssociationINSTITUTE FOR  APPLIED  MATERIALS   – MATERIAL  PROCESS  TECHNOLOGY   |   CORROSION  DEPARTEMENTwww.kit.eduDevelopment of Electrochemical Processes for Aluminum-based Coatings for Fusion ApplicationsJuergen Konys2 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysIntroduction - Location of KIT, Germany3 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysAdvanced processes for tritium permeation andcorrosion barriersOutlineApplications for Nuclear Fusion T-permeation and/or anti-corrosion barriers for liquid breeder blanketconcepts in ITER and future Fusion Power Reactors► Why Al-based barriers?Overview of previous coating activities  Hot-dip-aluminization processNew electrochemical Al coating processesAl deposition from organic aprotic electrolytes (ECA)Al deposition from ionic liquids + metal salt (ECX)Conclusions4 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysNuclear Fusion as an long-term Option for theWorldwide Energy Demand from South Korea's National Fusion Research InstituteDevelopment of a new primary energy source on the basis of a magnetically confined fusion plasma Favorable environmental and safety properties Unit size 2 – 5 GWth / 1 – 2 GWe Size of present base load power plants Potential fusion applications Base load for large cities Energy intensive industries High temperature process heat in a renewable economyWorldwide energy demand is rising continuously5 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysThe He-PbLi blanket concept for ITER: Application of T-permeation and/or anti-corrosionbarriersOUTINPb-15.7Li  Barriersare required!Corrosion of cooling and stiffening plates by PbLi and permeation of tritium from PbLi into He gasDeuterium (D) is highly available, e.g. in sea waterTritium (T) is naturally “not really“ available, butproduced in CANDU reactors by (n, ) reaction on deuteriumand bred by nuclear reactions from Lithium6Li (8%)  +  n   T  +  He  +  4.8 MeV  enrichment is needed7Li (92%)  +  n   T  +  He   - 2.87 MeVWorldwide, many fusion reactor concepts are designed to uselithium in different chemical formas solid breeder (ceramic), e.g. Li4SiO4, Li2Oas liquid metal, e.g. pure Li or Pb-15.7Li (Tm = 235°C) EUROFER(wt.-%)8.82Cr0.47Mn0.20V1.09W0.13Ta--Mo0.11C0.02Ni6 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysWhy do we need Tritium Permeation Barriers for “(European) Liquid Breeder Concepts”? Safety and cost: Its to reduce the tritium release from the PbLi (where its formed) into the coolant significantly (water for WCLL and helium for HCLL blanket concept)  limit for ITER 1gT/aInvestigated barrier systems Type of coatings Thickness Agency / Country Year reportedFeAl+Al2O3ECA, ECX150-180 m20-70 µmKIT, (HDA) & CEA, (CVD)KIT, China, etc.Feb-Sep ’04> 2009FeAl+Al2O3 100 m JRC, Ispra, Italy (VPS) 1998Er2O3, Al2O3,W+Al2O31 m1 + 0.5 µmIPP, Germany (PVD) Aug 2007(Cr2O3+SiO2)+CrPO480-200 m JAERI, Japan (CDC) Nov 2007W 10-120 µm KIT, Germany (EC) &CRPP, Switzerland (EC, PVD, PS)June 20077 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysRequirements for a tritium permeation barrierReduction of T-permeation by a factor of <100 in Pb-15.7Li (1000 in gas phase)Self-healing of (mechanically) damaged layer must be thermodynamically possible in      Pb-15.7Li (re-oxidizing)Long-term corrosion resistant in Pb-15.7Li up to ca. 550°CHigh content of low activation elementsNo negative influence on mechanical properties of the steel due to the coating processThe coating process must be of industrial relevanceStructure and technical requirements for an Al-based T-permeation and/or corrosion barrierAl2O3 (ca. 0.5 - 2 µm)Fe(Cr, Al)-phase (10 – 100 µm)FM-steele. g. EUROFER (9% Cr)Schematic structure8 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysPermeation data of different barriers on FM-steel P (molm-1 s-1 Pa-1/2 )Taken from:9 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysPermeation data of Al-coated FM-steels in H2PRF  2000PRF  200uncoated disk and tubecoated disk and tube 500°C  250°C10 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysRequirements for a tritium permeation barrierReduction of T-permeation by a factor of <100 in Pb-15.7Li (1000 in gas phase)Self-healing of (mechanically) damaged layer must be thermodynamically possible in      Pb-15.7Li (re-oxidizing)Long-term corrosion resistant in Pb-15.7Li up to ca. 550°CHigh content of low activation elementsNo negative influence on mechanical properties of the steel due to the coating processThe coating process must be of industrial relevanceStructure and technical requirements for an Al-based T-permeation and/or corrosion barrierAl2O3 (ca. 0.5 - 2 µm)Fe(Cr, Al)-phase (10 – 100 µm)FM-steele. g. EUROFER (9% Cr)Schematic structure11 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysThermodynamics of Al/Al2O3-based T-permeation barriersStability of oxides12 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysCorrosion attack of bare EUROFER steel in        Pb-15.7Li at 550°C as a function of flow velocity400 µm/year220 µm/yearCorrosion barriersare required!13 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysRequirements for a tritium permeation barrierReduction of T-permeation by a factor of <100 in Pb-15.7Li (1000 in gas phase)Self-healing of (mechanically) damaged layer must be thermodynamically possible in      Pb-15.7Li (re-oxidizing)Long-term corrosion resistant in Pb-15.7Li up to ca. 550°CHigh content of low activation elementsNo negative influence on mechanical properties of the steel due to the coating processThe coating process must be of industrial relevanceStructure and technical requirements for an Al-based T-permeation and/or corrosion barrierAl2O3 (ca. 0.5 - 2 µm)Fe(Cr, Al)-phase (10 – 100 µm)FM-steele. g. EUROFER (9% Cr)Schematic structure14 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysActivation of Al for Al-based barriers in a “fusion irradiation environment”Aluminium irradiation for 2 years15 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysAl-based coatings: The Fe-Al phase diagram tounderstand the complexity of intermetallics1: Fe3Al2: FeAl3: FeAl24: Fe2Al5Diffusion couple: Fe‐AlBrittle phases16 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysHot-Dip aluminizing processparameters for hot dipping are: Tdip = 700°C, dipping time of 30 s in Ar-5%H2 atmosphere9% Cr steelFe2Al5AlHV 1000230Microstructure of hot dipped surface Microstructure after heat treatmentThe alloyed surface layer consists of brittle Fe2Al5, covered by solidified AlFeAl-Fe(Al)9% Cr steelHV 320270240Heat treatment at 980°C / 0.5 h + 760°C / 1.5 h and an applied pressure of >250 bar (HIPing) reduces porosity and transforms the brittle Fe2Al5-phase into the more ductile phases FeAl and α-Fe(Al)17 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysElectrochemistry for coating applicationEC measurements of protic and aprotic metal deposition systems18 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysElectrochemical deposition for barriers/coatings- advantages of galvanic coatings -By anodic dissolution, metal removaltakes place without any mechanical stresses and at “low” temperaturesNo gradients ∆T, ∆p(and resulting forces) betweenelectrolyte medium and metal surfacemetal surface and metal bulk►no local heating as in EDM working►no mechanical load (no residual stresses)Metal substrateMen+e-Men+Men+Men+Men+Men+Men+ConductivitygradientElectrolytee-e-e-Metal substratee-Me0 Me0 Me0Men+Men+Men+Men+Men+ConductivitygradientElectrolyte19 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysSolvens Toluol, XylolDiisopropyletherQuarternay Amin saltse. g. Ethylmidazolium chlorideIonic solubility of solvens No YesAl-carrier system KF2Al(R)3 R = CnH2n+1 mit n= 2-6AlCl3Temperature 100°C RT … 200°CReactivityWater extremly high modestAir extremly high lowTemperature modest Stable up to 300°CToxicology | biodegrability Aromates: ++/--- Amines: -/+Max. conductivity [mS/cm] 19,5 22,0ECA ECXAl-Alkyl-Acryl-Complexin Toluolresp. AlkyletherAl3+ + 3 Cl-→  EMIM-AlCl4AlAlKKF+N NRX-+Electrochemical aluminium deposition- properties of organic aprotic electrolyte systems -20 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen Konysca. 20 µmca. 5 µmEurofer + Al galv.Reduced Al thickness  +Rough surface from turningca. 50 µmEurofer + 20 µm Al galv. Heat treatment :960°C 0.5h; 760°C 1.5hAl-enriched zoneProcess specificsOrganic electrolyte, Al-alkyle, under cover gasDeposition temperature ca. 100°C, rate ≈ 12 µ/hMore complex geometries can be coated; even inside tubesResult of ECA developmentElectrochemical coating applicable to functional scales in TBM’sBarrier function tested in corrosion, successfullySalt-based processes have to be developed for higher compositional flexibilityReason: Electro-negativity of refractory metals and unique behaviorDevelopment of electrochemical Al coating process, toluol-based (ECA)EUROFER(wt.-%)8.82Cr0.47Mn0.20V1.09W0.13Ta--Mo0.11C0.02NiScrews with nuts21 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen Konyst = 0.5 ht = 1 hDevelopment of coatings as corrosion T-permeation barriers (ECX)Development of electrochemical aluminum coating process based on ionic liquids (ECX)t = 2 hAdvantages of ECX process based on ionic liquids: Improved flexibility compared to ECAImproved security (inflammable, not volatile) compared to ECA Deposition parameters are customizable to produce coatings with specific properties (thickness, deposition rate, morphology) Controllable layer thickness (compared to HDA)DCP1P2Control of morphologyControl of layer thicknessDeposition ParametersParameter DC P1 P2jm 20 mA/cm2 20 mA/cm2 20 mA/cm2jp - 80 mA/cm2 25 mA/cm2t 30 min 30 min 30 minf - 1 s-1 1 s-1 100 % 25 % 80 %22 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysElectrochemistry of aluminum in ionic liquidsCyclic voltammetrySystem Pt/EMIM-Cl+AlCl3/Ptv = 100 mV/si = f(T)anodic reactionscathodic reactions23 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen Konysca. 5 µmca. 50 µmAl‐enriched zoneHeat treatment of Al layers for corrosion and T-permeation barriers (pure Al is not stable in PbLi)Treatment of Al coatings produced by ECXHT SchemeAfter depositionHomogeneous conversion of Al coatings and formation of desired Fe-Al phases on 1.2210 steelNo delamination visibleHeat treatment necessary to convert Al coatings to desired protective Fe-Al scales for corrosion protection and T-permeationtube furnace usedfor HTAfter HT24 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysHeat treatment of Al layers for corrosion and T-permeation barriersTreatment of Al coatings produced by EDX process (Lewis acidic IL)before heat treatment: approx. 8µm AlEuroferα‐Feafter heat treatment: 4h 640°C,0.5 h 980°C, 1.5h 760°C-Fe (0-12 at.% Al)Eurofer (9% Cr) Heat treatment under Ar atmosphere (preventing of strong surface oxidation) + additional annealing step at 640°C (4h)Relatively smooth surface after heat treatment Layer thickness after heat treatment: approx. 50µm (center)Actual work:Ongoing examination of deposition parameters:Adhesion to the substrate, reproducibility, influence on coating propertiesInfluence of sample geometryOptimization of heat treatment parameters (depending on parameters during ECX process)25 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen Konysca. 5 µmca. 50 µmAl‐enriched zoneDevelopment of electrochemical aluminum coating processes (corrosion tests in Pb-15.7Li for ECX process)Barriers produced by ECX process:Corrosion protection of Eurofer in flowing Pb-Li is shown for “short-term“ exposure times up to 4.000hRemaining protective scale thickness after 4000 h: >50 µmRadial mass loss:  ca. 10 µm  corrosion rate ca. 20 µm/yearHomogeneous corrosion attack of the scale itself  No formation of   plateaus (!) visible as in the case scales produced by ECA process  after 4000 hPb‐15.7LiFe‐AlEuroferafter 2000 hEuroferFe‐AlPb‐15.7Li26 19th International Corrosion Congress  |  November 2-6, 2014  |  Jeju Island, Korea                                                                                                  Jürgen KonysConclusionsBarriers, based on Fe-Al/Al2O3, are appropriate to fulfill the requirements for     T-permeation reduction and corrosion protection in liquid PbLi.Hot-dip aluminizing is an excellent tool to investigate the formation of aluminidelayers on FM-steels (interdiffusion). But HDA coatings have drawbacks because of the high Al content in the surface ► high activation under neutron irradiation: 26Aland the low flexibility for coating of complex-shaped parts.Electrochemical deposition processes like ECX have shown their applicability for manufacturing of thin Al coatings with high reproducibility, even for complex geometries.The development of appropriate heat treatments has to be further optimized, followed by new permeation tests in H-, D- and finally T- environments.The new electrochemical Al-based coatings have also a high potential in other energy applications at elevated temperatures and aggressive environments. 

Development of electrochemical processes for aluminum-based coatings for fusion applications

https://publikationen.bibliothek.kit.edu/230097965/3816687

Development of electrochemical processes for aluminum-based coatings for fusion applications

Abstract

Similar works

Full text

Available Versions

KITopen