Chemical Compatibility and High Temperature Limits for ... · 1.3 1.5 2.36 1.9 Damaged brittle...
Transcript of Chemical Compatibility and High Temperature Limits for ... · 1.3 1.5 2.36 1.9 Damaged brittle...
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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
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
Dissolution of vanadium carbo-nitrides
Dissolution of vanadium metal
CALCULATED WEIGHT LOSS IN 1000 m2 SYSTEM
Weight Loss for 1000 m2 at 550 oCin Flowing Lithium
Nitrogen concentration [wppm]
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
Dissolution of vanadium carbo-nitrides
Dissolution of vanadium metal
Weight Loss for 1000 m2 at 550 oCin Flowing Lithium
Nitrogen concentration [wppm]
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
Dissolution of vanadium carbo-nitrides
Dissolution of vanadium metal
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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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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.)
•• 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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COMPATIBILITY OF SiC/SiC COMPOSITES WITHCOOLANTS (cont.)
Molten Salt Effects on SiC/SiCMolten Salt Effects on SiC/SiC
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COMPATIBILITY OF SiC/SiC COMPOSITES WITHCOOLANTS (cont.)
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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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES (cont.)
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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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES (cont.)
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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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES (cont.)
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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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES (cont.)
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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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES (cont.)
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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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES (cont.)
•• 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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COMPATIBILITY OF REFRACTORY METALS WITHNON-METALLIC IMPURITIES (cont.)
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.