Chemical Compatibility and High Temperature Limits for ... · 1.3 1.5 2.36 1.9 Damaged brittle layer Lithium LixMyIz ... Chemical Compatibility and High Temperature Limits for Structural

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CHEMICAL COMPATIBILITY AND HIGH-CHEMICAL COMPATIBILITY AND HIGH-TEMPERATURE LIMITS FOR STRUCTURALTEMPERATURE LIMITS FOR STRUCTURAL

MATERIALSMATERIALS

Nasr M. GhoniemNasr M. Ghoniem

Mechanical and Aerospace Engineering DepartmentMechanical and Aerospace Engineering DepartmentUniversity of California at Los Angles (UCLA)University of California at Los Angles (UCLA)

Los Angeles, CA. 90095-1597Los Angeles, CA. 90095-1597

APEX Study MeetingAPEX Study Meeting

SANDIA NATIONAL LABSSANDIA NATIONAL LABS

Albuquerque, N.M.Albuquerque, N.M.July 27-28, 1998July 27-28, 1998

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COOLANT - STRUCTURAL MATERIAL SYSTEMS

•• Liquid LithiumLiquid Lithium

•• Liquid Lithium-LeadLiquid Lithium-Lead

•• Molten Salts (Molten Salts (FLiBeFLiBe))

•• HeliumHelium

•• Vanadium AlloysVanadium Alloys

•• Silicon CarbideSilicon CarbideCompositesComposites

•• FerriticFerritic Steels Steels

•• Refractory Alloys Refractory Alloys ((TaTa, Nb, , Nb, MoMo, W), W)

COOLANTCOOLANT STRUCTURAL MATERIALSTRUCTURAL MATERIAL

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LIQUID METAL CHEMICAL COMPATIBILITY(Basic Mechanisms)

> Dissolution in Liquid MetalDissolution in Liquid Metal

( )

RT

H

bulksat

act

Cedt

dS

ccdt

dS

∆−

=

−β=

$ = mass transfer coefficient

csat = element saturation concentration in liquid metal

cbulk = actual element concentration in bulk

)Hact = activation energy for dissolution

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LIQUID METAL CHEMICAL COMPATIBILITY(Basic Mechanisms) cont.

> Exchange due to non-metallic ElementsExchange due to non-metallic Elements

For oxygen, carbon, and nitrogen, the distribution coefficientFor oxygen, carbon, and nitrogen, the distribution coefficientis:is:

[ ][ ]

( ) ( )

∆−∆

=RT

soGloG

os

os e

la

saK

aassoo are saturation activities for solid (s) and liquid (l).are saturation activities for solid (s) and liquid (l).

>> For K>1, we get pick-up. For K>1, we get pick-up.>> For K<1, we get loss. For K<1, we get loss.

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COMPATIBILITY OF VANADIUM ALLOYS WITHLIQUID LITHIUM

•• For V-3Ti-1Si and V-15Cr-5Ti at 550ºC in flowingFor V-3Ti-1Si and V-15Cr-5Ti at 550ºC in flowinglithium (lithium ( BorgstedtBorgstedt ):):

-- weight loss: 10weight loss: 10 -3-3 - 3x10 - 3x10 -3-3 g/m g/m 22hrhr

-- weight loss is strongly influenced by nitrogenweight loss is strongly influenced by nitrogencontent of the liquid metal.content of the liquid metal.

-- Reaction is parabolic with an activation energyReaction is parabolic with an activation energy

of 180kJ/of 180kJ/ mol mol ((≈≈ nitrogen diffusion energy in nitrogen diffusion energy invanadium)vanadium)

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Weight Loss for 1000 m2 at 550 oCin Flowing Lithium

Nitrogen concentration [wppm]

0 10 20 30 40 50 60 70

Cor

rosi

on R

ate

(Kg

/Yea

r)

0

20

40

60

80

100

120

140

V-3Ti-1Si

Dissolution of vanadium carbo-nitrides

Dissolution of vanadium metal



0 10 20 30 40 50 60 70

Cor

rosi

on R

ate

(Kg

/Yea

r)

0

20

40

60

80

100

120

140



CALCULATED WEIGHT LOSS IN 1000 m2 SYSTEM



0 10 20 30 40 50 60 70

Co

rro

sio

n R

ate

(Kg

/Yea

r)

0

20

40

60

80

100

120

140

V-3Ti-1Si





0 10 20 30 40 50 60 70

Co

rro

sio

n R

ate

(Kg

/Yea

r)

0

20

40

60

80

100

120

140



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MAIN CORROSION MECHANISM FORREFRACTORY METALS

Electronegativity ChartMetal Impurity Li

IV A V A VI A VII A IV B V B VI B 0.98Ti V Cr C N O

1.54 1.63 1.66 2.55 3.04 3.44Zr Nb Mo

1.33 1.6 2.16Hf Ta W Re1.3 1.5 2.36 1.9

Damaged brittle layerDamaged brittle layer

LithiumLithium

LiLixxMMyyIIzz

M = refractory metalM = refractory metal I = interstitial impurityI = interstitial impurity

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EQUALIZATION OF ELECTRONEGATIVITY

Electronegativity Electronegativity ≡≡ the relative ability to acquire a negative the relative ability to acquire a negative charge. charge.

MetalMetal ImpurityImpurity

(low in (low in electronegativityelectronegativity))

(highly electro-negative)(highly electro-negative)

MetalMetalImpurityImpurity

(gets smaller with losing(gets smaller with losingmore than 1/2 the valencemore than 1/2 the valenceelectrons)electrons)

(gets larger by acquiring(gets larger by acquiringmore than 1/2 the valencemore than 1/2 the valenceelectrons)electrons)

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CONCEPT OF ELECTRONEGATIVITY

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COMPOUND STABILITY BASED ONELECTRONEGATIVITY

Carbides Nitrides Oxides CommentsTi 1.01 1.5 1.9 oxide formers

IV A Zr 1.22 1.71 2.11 (alloyingHf 1.25 1.74 2.14 elements)V 0.92 1.41 1.81

V A Nb 0.95 1.44 1.84Ta 1.05 1.54 1.94Cr 0.89 1.38 1.78

VI A Mo 0.39 0.88 1.28 most corrosionW 0.19 0.68 1.08 resistant

VII A Re 0.65 1.14 1.54

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EXPERIMENTAL OBSERVATIONS OF LITHIUMCOMPATIBILITY WITH REFRACTORY METALS

Up to lithium velocities of 6m/s, the temperature limit forUp to lithium velocities of 6m/s, the temperature limit foracceptable corrosion for Nb alloys is ~1250acceptable corrosion for Nb alloys is ~1250ººC, while that for C, while that for TaTaalloys is ~1350alloys is ~1350 ººC.*C.*

T(ºC)

∆T(ºC)

Time(hr)

Li velocity(m/s)

corrosion rate(µm/yr)

1100 200 10,000 3-6 negligible

1200 200 1,550 3-4 negligible

1297 179 3,000 .05 7.5

1073-1143 ~10 500 48.5 120

1330 200 500 3-4 1000

Corrosion Rates for Nb-1ZrCorrosion Rates for Nb-1Zr

*References:

1. A.J. OVERMAN, et al, LCRE Non Nuclear System Test, Final Report PWAC-402, Part IV, Pratt and Whitney Aircraft, Middletown, Connecticut (October 1965).

2. L.G. HAYES, Corrosion of Niobium-1Zr Alloy by Lithium at High Velocities, JPL Technical Report 32-1233 (December 1, 1967).

3. M.S. FREED, Corrosion of Columbian Base and Other Structural Alloys in High Temperature Li, PWCA-3555 (June 30, 1961).

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EXPERIMENTAL OBSERVATIONS OF LITHIUMCOMPATIBILITY W/ REFRACTORY METALS (cont.)

Corrosion Rates of Tantalum Alloys in Flowing LithiumCorrosion Rates of Tantalum Alloys in Flowing Lithium

Alloy T(ºC)

∆T(ºC)

Time(hr)

Li velocity(m/s)

corrosion rate(µm/yr)

T-111 1370 170 3,000 6 < 1.3

T-111 1330 200 5,000 < .05 < 1.3

ASTAR-811 1360 200 5,000 < .05 < 0.3

T-111,ASTAR-811

1150 95 5,000 3 No metal loss orLi attack

T-111 1230 95 10,000 6-6 No metal loss orLi attack

*References cont.:

4. J.E. DEVAN and C.E. SESSIONS, Nucl. App. Tech 3, 102-109 (February 1967).

5. J.E. DEVAN and C.E. SESSIONS, Nucl. App. Tech 9, 250-259 (August 1967).

6. G.W. AUSTON, Lithium Corrosion Investigation of Columbiam-Zironicum Alloy System PWAC-343 (June 27, 1961).

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CALCULATED EVOLUTION OF CARBONITRIDELAYER ON VANADIUM

Thickness of brittle vanadium nitride layer

Tim e (hours)

0 2000 4000 6000 8000 10000

carb

oni

trid

e la

yer

thic

knes

s (m

icro

ns)

0

20

40

60

80

100

120

140

160

180

200

V-3T i-1S iV-15C r-5Ti

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INTERSTITIAL TRANSPORT IN REFRACTORYMETAL-LITHIUM SYSTEM

•• OxygenOxygen: Will be transported from all : Will be transported from all refractoriesrefractoriesto lithium (except for to lithium (except for yltriumyltrium, hafnium, and, hafnium, andzirconium)zirconium)

•• CarbonCarbon: All metals (except for : All metals (except for Mo Mo and W) will be aand W) will be asink for carbon.sink for carbon.

•• NitrogenNitrogen: All metals (except for : All metals (except for Mo Mo and W) willand W) willgettergetter nitrogen. nitrogen.

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COMPATIBILITY OF SiC/SiC COMPOSITES WITHCOOLANTS

Corrosion ReactionsCorrosion Reactions::

SiC(s) + OSiC(s) + O22(g) = (g) = SiOSiO(g) + CO(g): Low Po(g) + CO(g): Low Po22

SiC(s) + 3/2OSiC(s) + 3/2O22(g) = SiO(g) = SiO22(s) + CO(g): High Po(s) + CO(g): High Po22

SiC(s) + 2HSiC(s) + 2H22(g) = (g) = Si Si + CH+ CH44(g)(g)

SiC(s) + 2HSiC(s) + 2HzzO(g) = O(g) = SiOSiO(g) + CO(g) + 2H(g) + CO(g) + 2H22(g)(g)

SiOSiO22(s) + H(s) + H22(g) = (g) = SiOSiO(g) +H(g) +H22O(g)O(g)

MM22O(l) + SiOO(l) + SiO22(s) = M(s) = M22SiOSiO33(s)(s)

xSiOxSiO22(s) + Na(s) + Na22SOSO44(l) = Na(l) = Na22O O •• x(SiO x(SiO 22) (l) + SO) (l) + SO33(g)(g)

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COMPATIBILITY OF SiC/SiC COMPOSITES WITHCOOLANTS (cont.)

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•• For For αα-SiC exposed to a thin layer of -SiC exposed to a thin layer of Li Li (30-60min,(30-60min,T < 500T < 500ººC), RT fracture strength decreased fromC), RT fracture strength decreased from350MPa to 150MPa, and fracture toughness from350MPa to 150MPa, and fracture toughness from4MPa4MPa••mm1/21/2 to 2MPa to 2MPa ••mm1/21/2..

•• Intergranular Intergranular penetration and crack growth is apenetration and crack growth is aresult of reduction of the protective SiOresult of reduction of the protective SiO22 glassy glassyphase.phase.

•• Flowing Lithium will accelerate corrosion.Flowing Lithium will accelerate corrosion.•• SiC/SiC may not be compatible with lithium.SiC/SiC may not be compatible with lithium.

Experimental ObservationsExperimental Observations

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Molten Salt Effects on SiC/SiCMolten Salt Effects on SiC/SiC

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Molten Salt Effects on SiC/SiC Molten Salt Effects on SiC/SiC ((contcont.).)

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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES

1.1. Hydrogen and Nitrogen ReactionsHydrogen and Nitrogen Reactions

AA22(g) (g) ⇔⇔ 2A(in M) 2A(in M)

Equilibrium Equilibrium ⇒⇒

∆−

==RT

osG

A

p eP

aK

2

KKpp = equilibrium constant, a = activity. = equilibrium constant, a = activity.For dilute solutions For dilute solutions ⇒⇒ SievertSievert’’s s Law:Law:

∆−

∆

==RT

osH

R

osS

AApA eePPKX22

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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES (cont.)

2.2. OxygenOxygen

OO22(g) (g) →→ 2O(in M) 2O(in M) [absorption][absorption]nOnO(in M) + M(s) (in M) + M(s) →→ MOMOnn(g)(g) [[desorptiondesorption]]

( )

desabs

des

abso

nRT

Q

OonOo

QQQ

K

KK

ePKKPX

−=∆

=

==

∆−

,

1

2

1

2

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3.3. Compound FormationCompound Formation

Gas/metal: 1/2AGas/metal: 1/2A22(g) + (m/n)*M(s) (g) + (m/n)*M(s) ⇔⇔ (1/n)* (1/n)*MMmmAAnn(s)(s)Saturated solution: A(in M) + (m/n)*M(s) Saturated solution: A(in M) + (m/n)*M(s) ⇔⇔ (1/n)* (1/n)*MMmmAAnn(s)(s)

∆−

==RT

ofG

A

eX

Kmax,

1

XXA.maxA.max = maximum solid solubility = maximum solid solubility

=∆−∆=∆ of

of

of STHG Formation energyFormation energy

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HHyyddrrooggeenn NNiittrrooggeenn OOxxyyggeenn CCaarrbboonnMMeettaall ∆∆HHss

oo ∆∆HHffoo ∆∆HHss

oo ∆∆HHffoo ∆∆HHss

oo ∆∆HHffoo ∆∆HHff

oo

αα--ZZrr --5599..55 --9955..33 --336644 --661199 --554411 --118855αα--HHff --3377..66 --6655..55 --336699 --555522 --555533

VV --3322..44 --4411..55 --228822 --442222 --443322 --114477NNbb --3399..66 --117788 --227722 --338866 --441188 --115599TTaa --3366..44 --118822 --220044 --338833 --440022 --112266MMoo 5522..22 9955 --5577 --228888 --4499WW 110000..44 119955 --2277

∆∆HHssoo and and ∆∆HHss

oo Values in kJ/(gValues in kJ/(g••atom) for Solution of H, N, and O in Solidatom) for Solution of H, N, and O in SolidRefractory Metals or Formation of the Corresponding Metal-Rich CompoundsRefractory Metals or Formation of the Corresponding Metal-Rich Compoundswith H, N, O and C.*with H, N, O and C.*

*References:

7. E. Fromm and E. Gebhardt, eds., Gase und Kohlenstoff in Metallen, (Berlin, Springer, 1976)

8. H. Jehn, H. Speck, E. Fromm, W. Hehn and G. Hörz, “Gases and Carbon in Metals (Thermodynamics, Kinetics and Properties),” Physics Data, Series 5, FachinformationszentrumEnergie, Physik, Mathematik, Karlsruhe; “Pt. V, GroupIVa Metals (1), Titanium” [no.5-5 (1979), 78 pp.]; “Pt.VI, Group Iva Metals(2), Zirconium, Hafnium” [no5-6 (1979), 74pp.];“Pt. VII, Grouop Va Metals(1), Vanadium” [no.5-7 (1981), 64pp.]; “Pt. VIII, Group Va Metals(2), Niobium” [no. 5-8 (1981), 117pp.]; “Pt. IX, Group Va Metals(3), Tantalum” [no. 5-9(1981), 74pp.]; “Pt. X, Group Via Metals(1), Chromium, Tungsten” [no. 5-10(1980), 60pp.]; “Pt. XI, Group Via Metals(2) Molybdenum” [no. 5-11(1980) 51pp.]; and “Pt. XII, GroupVIIa Metals, Manganese, Technettium, Rhenium” [no. 5-12(1981), 27pp.].

9. E. Fromm and G. Hörz, “Hydrogen, Nitrogen, Oxygen, and Carbon in Metals,” Intern. Met. Rev., Nos. 5 and 6, (1980), pp.269-311.

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Rate laws and Activation Energies of Nitrogen Absorption and Rate laws and Activation Energies of Nitrogen Absorption and Desorption Desorption forforNb, Nb, TaTa, , Mo Mo and W.*and W.*

Metal Rate Law Qab

(kJ/mol)Qdes

(kJ/mol)Temperature

(oC)

Nb v=kpN2-k’cn

2 67 519 1650-2100Ta 68 562 1480-2730Mo v=k(pN2)

1/2-k’cN 189 95 1300-2400W 287 92 >1400

*References:

10. G. Hörz, “Niob,” in Ref. 7, pp.460-494.

11. G. Hörz, “Tantal,” in Ref. 7, pp. 494-520.

12. H. Jehn, “Molybdän,” in Ref. 7, pp. 534-551.

13. H. Jehn, “Wolfram,” in Ref. 7, pp. 552-563.

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Rate laws and Activation Energies of Nitrogen Absorption or Rate laws and Activation Energies of Nitrogen Absorption or DesorptionDesorption of ofOxygen.*Oxygen.*

Metal Rate Law Qab

(kJ/mol)Qdes

(kJ/mol)Temperature

(oC)

V vab= (kpO2)/(1+k’exp(Qab/RT)) 73.1 1030-1430

V vdes = k’cO 572 >1500

Nb vdes = k’cO + k"cO

2 543 >1700

Ta vdes = k’cO + k"cO

2 553 >1700Ta vab = kpO2(1-θ)2

vab = (1/(1+kcO) 2

~0 1000-1700

*References:

14. G. Hörz, “Vanadium,” in Ref. 7, pp.441-460.

15. G. Hörz, H. Kanbach, R. Klaiss and H. Vetter, “Influence of the Surface State on the Reactions of Transition Metals with Nitrogen, Oxygen and Hydrocarbons,” Proc. 7thIntern. Vac. Congress and 3rd Intern. Conf. On Solid Surf., Vienna, (1977), pp. 999-1002.

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Values of Values of ∆∆Q and Q and KKoo Determining the Steady-State Relations for the ReactionDetermining the Steady-State Relations for the ReactionSystems of Nb and Systems of Nb and Ta Ta with Owith O22 and H and H22O.*O.*

System Nb-O Nb-H2O Ta-O Ta-H2O

∆Q(kJ/mol)

502 480 560 530

Ko (at.%•Pa)

9.1x10 -10 1.5x10 -10 1.35x10 -10 6.4x10 -10

*References:

16. G. Hörz, “Kinetik und Mechanismen,” in Ref. 7, pp.1-83.

17. H. Jehn, “Vorgänge beim Glühen der Via- und Va- Metalle in Sauerstoff, Luft und Wasserdampf bei niedrigen Drücken,” Metall, 28 (1974), pp. 699-705.

18. K. Schulze and H. Jehn, “Behaviour of Niobium and Tantalum at High Temperatures in Low-Pressure Oxygen-Containing Atmospheres,” Proc. 8th Intern. Vacuum Congress,Cannes, France (1980), Vol. II, pp. 554-557.

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•• Nb and Nb and Ta Ta show high nitrogen show high nitrogen solubilities solubilities (between 0.1 and(between 0.1 and10 at %) at low pressures (1010 at %) at low pressures (10-4-4-10-10-3-3bar).bar).

•• Nitrogen solution is exothermic (concentration decreasesNitrogen solution is exothermic (concentration decreaseswith temperature) for Nb, with temperature) for Nb, TaTa, and V. It is endothermic for W, and V. It is endothermic for Wand and MoMo, with very low , with very low solubilitiessolubilities..

•• At extremely low oxygen pressures (10At extremely low oxygen pressures (10-40-40-10-10-10-10bars), thebars), thesolubility limit of (3-10 at %) is reached in solubility limit of (3-10 at %) is reached in TaTa, Nb, and V., Nb, and V.

•• General Trend General Trend ⇒⇒ Interstitial Interstitial solubilities solubilities decrease in thedecrease in theorder: IV A > V A > VI A.order: IV A > V A > VI A.

•• Because of the Because of the embrittlement embrittlement effects of the interstitialeffects of the interstitialimpurities at low concentrations (10impurities at low concentrations (10’’s s ppmppm ), severe), severerestrictions are expected for helium-cooled systems.restrictions are expected for helium-cooled systems.

Experimental Observations and ConclusionsExperimental Observations and Conclusions

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Recommended Maximum Interstitial Impurity Limits for Helium-Cooled Refractory PipingMetal Group C N O

Solubility Limit Maximum for Solubility Limit Maximum for Solubility Limit Maximum for

(Tm/2) 50 oC shift (Tm/2) 50 oC shift (Tm/2) 50 oC shiftV A V, Nb, Ta ~10,000 wppm ~10,000 wppm ~8% ~4,000 wppm 10% ~2,000wppmVI A Cr, Mo, W ~10,000 wppm ~200 wpp, 0.10% ~150 wppm 0.10% ~100wppm

⇒⇒ Note that the most stringent control has to be on oxygenNote that the most stringent control has to be on oxygenimpurities at a level of less than 100wppm.impurities at a level of less than 100wppm.

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ESTIMATED UPPER TEMPERATURE LIMITS ONTHE BASIS OF COMPATIBILITY

0200400600800

1000120014001600

V Nb Ta Mo W

He (100appm oxygen)

Li-Be-F salt

Li (dynamic)T (oC)

Tm (K) 2175 2740 3287 2890 3680

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Chemical Compatibility and High Temperature Limits for ... · 1.3 1.5 2.36 1.9 Damaged brittle layer Lithium LixMyIz ... Chemical Compatibility and High Temperature Limits for Structural