Development of Corrosion andHydrogen Permeation Resistant
Nanostructured Composites
Branko N. PopovBranko N. PopovCenter for Electrochemical EngineeringCenter for Electrochemical EngineeringDepartment of Chemical EngineeringDepartment of Chemical Engineering
University of South Carolina, Columbia SC 29208University of South Carolina, Columbia SC 29208
ØDevelopment of novelprocesses and treatmentsfor synthesis ofnanostructured materials.ØDevelopment of
mathematical models whichhelp to engineer andoptimize the materialssurface and bulk properties.ØDevelopment of novel
hybrid nanostructuredmaterials with superiorcorrosion properties.
Presentation Outline
Hydrogen Induced Cracking
Hydrogen is produced duringØCorrosionØElectroplatingØCharging secondary batteriesØCathodic protectionHydrogen in alloy can cause catastrophic failures via:ØHydrogen embrittlementØBlisteringØHydrogen induced cracking
Mitigation of Hydrogen Permeation
Current methods for decreasing hydrogen permeationlike temperature treatments and laser modification donot decrease the hydrogen penetration rate to the safelevel
Our approachØInhibit the hydrogen discharge reaction rate
ØIncrease the recombination reaction rate
ØInhibit hydrogen absorption into the metal
ØForm a physical barrier to hydrogen diffusion
Development of Novel Treatments for Synthesis ofNanostructured Materials with Superior Corrosion Properties
Superior corrosionproperties
Synthesis of Nanostructured Materials byElectrochemical Processes
UnderpotentialDeposition (UPD)of monolayers ofZn, Ni, Bi onto
hard alloys
Novel autocatalyticreduction process for
deposition ofamorphous Zn-Ni-P
alloys
DC and Galvanostatic pulsetreatments for deposition of
ternary and quarternarycomposites based on Zn, Ni,
P and SiO2
Superior corrosion and hydrogenpermeation inhibition properties
Superior mechanical properties(low rates of hydrogen
permeation and corrosion)
DC and Pulse Deposition of NanostructuredMultilayers
ØThe particle nucleation rate andthe grain size is controlled by thepeak cathodic potential, the pulseperiod and the relaxation periodand the duty cycle.ØThin films and nanostructured
deposits have been deposited byoptimizing the duty cycle and theconcentration of leveling agents.ØThe film grain size is
proportional to the crystal growthrate and inversely proportional tothe nucleation rate.ØPulse deposition increases the
nucleation rate, decreases thecrystal growth rate.
Multiple Layers of Zn-Ni
Nanostructured Zn-Ni-P
1 µm
1 µm
Underpotential Deposition of Zn
Underpotential Deposition of NanostructuredMonatomic Layers of Zn, Pb and Bi
Ø UPD occurs with a formation of monatomic layers atpotentials more noble than the reversible Nernstpotential
Ø UPD has been optimized for Zn, Pb and Bi by using thework functions of these metals and the work function ofthe substrate
Ø The Underpotential shift (E) when the monatomiclayers are formed is determined by the difference inwork functions in electron volts of both metals
Ø UPD formed monatomic layers pf Pb, Bi and Zn onsteel surface inhibit corrosion due to lowering of thebinding energy of the hydrogen adatoms on Zn,Pb andBi adsorbates.
Experimental
Ø HY-130 Steel (0.4 cm2) was used as the substrate
Ø Devanathan-Stachurski permeation technique wasused to study hydrogen inhibition
Ø Cathodic solution during permeation was 1M Na2SO4
+ 0.4 M NaCl + 1M H3BO3
Ø For underpotential deposition of Zinc, 2X10-3 M Zn2+
ions were added to the catholyte
Ø Anodic solution during permeation was 0.2M NaOH
Ø Anodic side of the membrane was coated with 0.15-0.2 µm thin layer of Pd
Devanathan-Stachurski Technique
ØThe hydrogen permeation current wasmeasured continuously as a function of time.ØThe permeation current was measured by
setting the potential on the anodic side of themembrane at -0.3 V vs. Hg/HgO.ØCathodic side of the membrane was polarized
potentiostatically creating conditions forUnderpotential deposition of Zn or Pb.ØZero concentration of absorbed hydrogen on
the anodic side of the membrane wasmaintained by instantaneous oxidation ofdiffusing H.
Hydrogen Permeation Cell
CVs obtained on HY 130 with electrolytecontaining different Zn concentrations
Hydrogen permeation curves through aHY 130 steel
Hydrogen permeation curves through a HY130 steel in presence of zinc ions
Dependence of hydrogen entry efficiency as afunction of applied cathodic overpotential
Conclusions
Ø Underpotential deposition of Zinc inhibits the discharge ofhydrogen on HY-130 steel.
Ø In the presence of a monolayer coverage of Zn, hydrogenevolution currents were reduced by 58%.
Ø Hydrogen atom direct entry mechanism has been usedalong with a mass transfer correction term to interpret thepermeation data.
Ø In the presence of Zn, hydrogen entry efficiency in thealloy and hydrogen entry rate constant were reduced by afactor of three and by 74% respectively.
G. Zheng, B. N. Popov, and R. E. White, "Use of Underpotential Deposition of Zinc to MitigateHydrogen Absorption into Monel-K500," J. Electrochem. Soc., 141, 1220-1224 (1994).
Summary of Experimental Results
Alloy Additive Decreasingof ic
Decreasingof j∞
Relation between j∞
and ic
Model
Zn2+ 46% 51% - -Pb2+ 44% 71% j∞ α ri
Conventional ModelAISI - 4340
Bi3+ 85% 65% - -Zn2+ 58% 90% j∞ α ic Direct EntryHY-130Tl1+ 83% Increasing
74%j∞ α ri and j∞ α ir conventional
model
Zn2+ 68% 40% - -Inconel-718Pb2+ 67% 70% - -Bi3+ 60% 76% - -
Monel-K500 Zn2+ 60% 60% - -Pd - - - j∞ α ic Direct Entry
Deposition of Multiple NanostructuredZn Layers
Objectives
ØTo investigate the effect of bulk deposition ofzinc layer on hydrogen permeation through aniron membraneØTo study the effect of thickness of the Zn-layers
on hydrogen permeation through themembrane.ØTo estimate the parameters governing the
hydrogen permeation through the ironmembrane using a conventional permeationmodel.
Experimental
Ø The zinc layers are deposited using a solutionconsisting of 1.0 M H3BO3 + 1M Na2SO4+ Zn SO4
Ø Nanostructured Zn layers were depositedgalvanostatically at 0.8 mA for 2-5, 10, 20 or 40 s.
Ø Assuming 100% current efficiency this wouldcorrespond to a Zn layer of 100nm thickness for each40 s of plating.
Ø Measurements of the cathodic current and permeationcurrent at different applied cathodic potentials, Ec weremade of the bare iron substrate and subsequently aftereach layer was plated.
Multiple Electroplated Zinc Layers forHydrogen Permeation Inhibition
0 50 100 150 200
Plating time (s)
10
20
30
40
50
60
70
j ∞ (µ
A/c
m2 )
i c (µA
/cm
2)
0
800
1600
2400
3200
4000
Multiple Electroplated Nanostructured ZincLayers for Hydrogen Permeation Inhibition
8.346.251.01160
6.206.991.021208.048.701.04100
4.629.831.24804.6911.41.2570
4.9414.71.28605.0320.61.4750
5.2228.21.55407.5641.71.7830
9.9762.01.992010.872.16.2510
69.880.6139Bare Iron (s)k3(109mol/cm2s)k”(106mol/cm3)io=io
’(1010A/cm2)Layer
Decrease of ic and j∝ with NanostructuredZn layers on Carbon Steel
20 s 40 s 60 s 80 s 100 s 120 s 160 s
ic 86 90 92 93 92 93 93
j∞ 61 82 91 93 95 96 96
Ø Hydrogen evolution and Permeationdecreased with each successivenanostructured zinc layers to 93% and 96%respectively as compared with bare iron
Ø Decrease in the permeation rate of hydrogenthrough the iron membrane was due tov Decrease of hydrogen discharge ratev Suppression of hydrogen absorption and
adsorption on deposited zinc layers
Conclusions
Deposition of Ternary Zn-Ni-X (X= P,SiO2,) Alloys
NanostructuredZn-Ni multilayers
Nanostructured Zn-Ni-Cd
1 µm1 µm
Synthesis of Nanostructured Layers of Zn-Ni-Cd
ØDeveloped a newelectrodeposition technique thatcan control the Zn-Ni ratio andthereby the barrier properties ofthe nano deposits.ØThe ability to control the Zn-Ni ratio helps in engineeringcoatings that are galvanicallycompatible with the substratesØ Zn-Ni-Cd coatings can beregarded as replacements forcadmium plating.
0.0 0.5 1.0 1.5 2.0 2.5 3.0Time (hour)
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
Pote
ntia
l (V
vs.
SCE
)
Zn-Ni-Cd(3 g/l CdSO 4)
Zn-Ni
Zn
Nickel
Cadmium
Steel
Nanostructured AlkalineZn-Ni-Cd (47/28/25%)
Objective
ØTo develop Zn-Ni-X ternary alloy coatingsØTo study the corrosion and hydrogen
permeation behavior of the developed coatingsusing electrochemical techniquesØCompare the results to that of cadmium
Our Approach
ØControl Zn-Ni ratio; increase Ni contentvincreases barrier properties
ØDecrease the Corrosion potentialvreduces the dissolution rate
ØModify hydrogen evolution, recombinationand absorption kineticsvinhibits hydrogen permeation
Objectives for Zn-Ni-X (X=P, SiO2) Composites
ØTo electrodeposit a Zn-Ni-X alloy thatvProvides Sacrificial Protection to ironvHas low dissolution rate in corrosive media
Ø To study the hydrogen permeation inhibitioncharacteristics of the new Zn-Ni-X alloy byvDetermining various kinetic properties
characterizing hydrogen permeation inhibitionunder corroding conditionsvComparing the hydrogen permeation inhibition
characteristics with Zn-Ni
A. Krishniyer, M. Ramasubramanian, B. N. Popov and R. E. White, “Electrodeposition &Characterization of a Corrosion Resistant Zinc-Nickel-Phosphorous Alloy,” Journal of the AmericanElectroplaters and Surface Finishing Society, January (1999) 99-103.
ExperimentalØ Zn-Ni alloy deposited galvanostatically fromv0.5M NiSO4 + 0.2M ZnSO4 + 0.5M Na2SO4; pH=3.0
Ø Zn-Ni-P alloy deposited galvanostatically fromvAbove Solution + 100 gpl NaH2PO2; pH=3.0
Ø SiO2 was deposited on top of Zn-Ni alloy by usingtechnology developed at USC for Elisha technologies
Ø Fe foil, 99.5% pure, 0.1 mm thick, 4 cm2 area was used assubstrate
Ø Composition analysis was done using EDAXØ Linear polarization technique was used to find RP
Ø Devanathan-Stachurski permeation technique was usedto study hydrogen inhibition
Ø Cathodic solution during permeation was 1M Na2SO4 +1M H3BO3 ; at various pH values
Ø Anodic solution during permeation was 0.2 M NaOH
Surface Morphologies of Zn-Ni and Zn-Ni-X alloyelectrodeposited galvanostatically at 5 mA/cm2
Zn-Ni-PZn-Ni Zn-Ni-SiO2
Ni- 9.5%Zn-90.5%
Ni- 4.27%Zn- 67.03%SiO2-28.70%
Ni- 9.0%Zn-90.0%P - 1.0%
Linear polarization studies on different deposits
-50 -30 -10 10 30 50
Current (µA/cm2)
-5
-3
-1
1
3
5
η (m
V v
s. S
CE
)
Zn-Ni-SiO2
Rp = 32000 Ω
Zn-Ni
Rp = 300 Ω
Zn-Ni-P
Rp = 600 Ω
Zinc
Rp = 167 Ω
Corrosion rates for different nanosize coatings
0
5
10
15
20
25
30
35
40
45
50
Corrosionrate inmpy
Zn-48.92
Cd-21.31Zn-Ni-22.12
Zn-Ni-P-10.7 Zn-Ni-
SiO2-0.3
Current WorkElectroless Deposition of Zn-Ni-P
Electroless Ni-P Electroless Zn-Ni-P
SEM Analysis of Electroless Zn-Ni-P
Ni- 97.9%P - 2.1%
Ni- 71.3%Zn-13.8%P -14.9%
Linear polarization studies on different deposits
-30 -20 -10 0 10 20 30
Current (µA/cm2)
-10
-5
0
5
10O
verp
oten
tial η
( mV
vs
SCE
)
Electroless Zn-Ni-P
Rp=1663 Ω,
OCV=-0.641 V
Electrodeposited Zn-Ni ,
Rp=167 Ω, OCV=-1.083 V
Electroless Ni-P
Rp=3592 Ω,
OCV=-0.399 V
Zn, Rp=300 Ω,
OCV=-1.120 V
Ø Deposit nanostructured Zn-Ni-Cd, Zn-Ni-P, Cd on AerMet 100samples
Ø Three different depositthickness of 2, 4, and 6 µm with%yield strengths of 50 and 75.
Ø Stress Corrosion Evaluation ofCoated and Bare AerMet 100specimens
Ø Polarization studies to comparethe corrosion rates of each of thecoatings with that of bareAerMet 100 alloy.
Current work for NASA
Development of Corrosion model
Hydrogen Permeation Model underCorroding Conditions
Ø Hydrogen evolution is the onlycathodic reaction
Ø Hydrogen permeation occursonly by diffusion of absorbedhydrogen
Ø The membrane is homogenouswith no hydrogen trappingsites
Ø The process is steady state
M. Ramasubramanian, B. N. Popov and R. E. White, "Characterization of Hydrogen Permeationthrough Zinc-Nickel Alloys under Corroding Conditions," J. Electrochem. Soc., 145, 1907 (1998).
Relationship between ln(iRelationship between ln(irr0.50.5/ j/ j∞∞) and j) and j
0.3 0.5 0.7 0.9 1.1
Jα, mA/cm2
3.0
3.5
4.0
4.5
ln((
I r)0.
5/J
α)
3 g/l CdSO4
1 g/l CdSO4
Corrosion Model
Nads
Nabs
NH
Ndes
Ndsb
CathodicSurface
x=0
AnodicSurface
x=L
NPerm(iCorr)
(irec)
(j∞)(j∞)
Discharge
Recombination
Absorption
adsk MHeHM →++ −+ 1
abs
k
kads MHMH3
4
⇔
MH e H MH 2k-
ads2 +→++ +
Development of Corrosion Model
)fexp()C-(1k zFi
N pH1
cads ηα−θ== +
)exp(qHC2k ηαθ fzF
ridesN −+==
NH = Nads - Ndes
NH = Nabs - Nrab
LC
D- N absH =
Parameter Estimation from Model
q
HaC
kk
j)fexp(i 2r
+=ηα
∞
pH1c CzFk )fexp(i +=ηα
∞−
+ =ηα jkk - zFk C)fexp(i
a
11
1pHc
NH = Nabs - Nrab absCkk 43 −= θ
azFkj∞=?
DL
k
kka
4
3
1+=
ic = ir + j∝MHads=MHabs;
Nabs = k3θNrab = k4(1-θ)Cabs
LC
D- N absH =
Plot of the Recombination function against theHydrogen ion concentration for Fe and Zn-Ni Alloy
-10 -9 -8 -7 -6 -5
log (CH+) (mol/cm 3)
-5
-4
-3
-2
-1
-0
1
log
(1/j ∞
i re(α
fη) ) Fe
Zn-Ni
Experimentally Determined Parameters for HydrogenPermeation Through Zn-Ni Nanolayers
Fe Zn-Ni
k1(mol/cm2s)
k2 (mol/cm2s)
ka (mol/cm2s)
p
q
1.0 × 10-12 1.5 × 10-12
1.8 × 10-13 3.9 × 10-12
2.85 × 10-9 9.09 × 10-11
-0.196 0.286
-0.476 0.227
θ 0.0125 0.075
Comparison of cathodic and permeation currentdensities for Zn-Ni-Cd, Zn-Ni and Steel
100 101 102 103 104
Ic and Jα (µA/cm2)
-0.8
-0.6
-0.4
-0.2
η (V
vs.
SC
E)
Jα, 3 g/l CdSO4
Jα, Zn-Ni
Ic, Steel
Jα, Steel
Ic, 3 g/l CdSO4
Ic, Zn-Ni
Experimentally Determined Parameters for HydrogenPermeation Through Nanostructured Layers of Zn-Ni-Cd
2.54x 10-10
1.78x 10-10
1.58x 10-15
k2, mol/cm2s
59.243.90.285ka mol/cm3
x10-8
0.212.616.98io, A/cm2
x10-4
Zn-Ni-Cd (5:2:3)Zn-Ni-Cd(16:3:1)Steel
Percentage Decrease in Permeation Current*of Different Nanostructure Coatings
* At over potential of 300 mV.
10.88
1.27
0.50
0.30
Coating Permeation current,µA/cm2 % Decrease
Steel
Zn-Ni
Zn-Ni-P
Zn-Ni –SiO2
-
88
95
97
Conclusions
Ø Developed a new electrodeposition technique that cancontrol the Zn-Ni ratio and thereby the barrierproperties of the nano deposits
Ø The ability to control the Zn-Ni ratio helps inengineering coatings that are galvanically compatiblewith the substrates
Ø Developed a mathematical model to evaluate thepermeation characteristics under corroding conditions
Ø Zn-Ni-SiO2 and Zn-Ni-P coatings have been developedthat are environmentally benign and can be regardedas replacements to Cd plating.
• Process optimization studies will be carried by scalingup the process.• Bench scale depositions• Require larger electrolytic cells
• Optimization of the novel Zn-Ni electroless depositionprocess to obtain corrosion and hydrogen permeationresistant deposits
• Development of Electroless Plating Techniques forobtaining Zn-Ni-P and Zn-Ni-SiO2 alloys.
• Hydrogen permeation characterization studies forelectroless plated alloys
Future Work