Development of Novel Surface Development of Novel Surface Protection Strategies for Copper Protection Strategies for Copper

CorrosionCorrosion

5th INTERNATIONAL CONFERENCE FOR YOUNG CHEMISTS 2015, UNIVERSITY SAINS MALAYSIA, PENANG, AUGUST 05-07, 2015

Need for Surface ProtectionNeed for Surface Protection Surfaces of all materials are corrosion-prone due Surfaces of all materials are corrosion-prone due

to Climatic conditions & Chemical factorsto Climatic conditions & Chemical factors Destruction of materials leads to economy lossesDestruction of materials leads to economy losses Direct & Indirect losses due to corrosion amounts Direct & Indirect losses due to corrosion amounts

to $13 billions per yearto $13 billions per year

Need for Surface ProtectionNeed for Surface Protection……

Prime concern is Conservation of MaterialsPrime concern is Conservation of Materials World’s supply of materials is limited &World’s supply of materials is limited &

wastage / loss of materials leads to loss of wastage / loss of materials leads to loss of energy, cost escalation etc.,energy, cost escalation etc., Surface coating is an important strategy to Surface coating is an important strategy to

protect materials which are prone to decayprotect materials which are prone to decay

Copper – An Engineering MaterialCopper – An Engineering Material Copper has been commonly used in a wide range

of applications in heat conductors, heat exchangers because of its excellent thermal conductivity and mechanical workability.

Copper generally shows resistant against atmospheric corrosion and other forms of corrosion.

However, copper becomes very susceptible to corrosion in a significant rate in media that contain chloride ions.

Corrosion Protection MethodsCorrosion Protection Methods Prevention of corrosion in copper has attracted

many Researchers and many strategies have been developed to protect copper.

Among the available methods, electropolymerization techniques have become prominent nowadays due to its simplicity and wide range of applications.

Protection through ElectropolymerizationElectropolymerization- polymerization of an organic compounds (usually the heterocyclic compounds) under the influence of current.Electrodeposition of polymeric films at the surface of an electrode has opened up a new field at the convergence between two rich domains: electrochemistry of modified electrode and conjugated systems.

Simple process

It is enough to impose a sufficiently positive potential (Epolym) or to cycle

with a sufficiently high anodic limit (generally, it should exceed Epolym by

100–200 mV) on a metallic electrode.

By passing of an anodic current through the solution of monomer, film of

the corresponding polymer progressively grows at the electrode surface.

General Aspects of Electropolymerization

Solvent Electrolyte Bath composition and temperature pH Monomer concentration Hydrodynamic conditions (e.g., stirring or its

absence) Electrode surface area Pretreatment of its surface Shape of the working electrode Current density

Factors Affecting Electropolymerization

Electrodeposition can be done by any of the following methods

Cyclic VoltammetryCyclic Voltammetry

ChronoamperometryChronoamperometry

ChronopotentiometryChronopotentiometry

Work done in our lab...Electrosynthesis of poly-3-amino-1,2,4-triazole/TiO2 (3-ATA/TiO2) on copper

Electropolymerization Electropolymerization of ATAof ATA

Electropolymerization of ATA done using 0.2 M Electropolymerization of ATA done using 0.2 M

ATA with 0.1M ethanol/NaOH by CV-by scanning ATA with 0.1M ethanol/NaOH by CV-by scanning

the potential between -0.2 to 1.6 V vs SCE at a scan the potential between -0.2 to 1.6 V vs SCE at a scan

rate of 30 mV/s.rate of 30 mV/s.

CV of 3-ATA on Cu in MeOH-NaOH CV of monomer –free Cu in MeOH-NaOH

CV of 3-ATA with various concentrations of TiO2

Addition of TiO2 increases the peak current values suggesting the increase of rate of polymerization

Schematic representation of electropolymerization of 3-ATA

FT-IR Studies XRD pattern of (a) p-3-ATA (b) p-3-ATA/TiO2

For bare TiO2, the strong absorption at 686 cm-1 could be obtained due to Ti-O stretching . This band is weak in p-ATa+TiO2 composites due to the interaction of polymer with TiO2

XRD pattern of p-ATa showed a peak at 25o. This could be due to the polymer.

The 2Ө values at 37o, 47o and 55o showed the presence of Ti in the polymeric matrix and these values proved that the crystalline behavior of TiO2 particles was not affected during electropolymerization.

SEM image of p-3-ATA/TiO2

EDAX spectra of p-3-ATA/TiO2

Ti

SEM Suggests the incorporation of TiO2 particles in the polymeric matrix.

The average particle size of TiO2 is 0.67 µm.

The incorporation of TiO2 particles into the polymeric matrix was also confirmed by EDX analysis.

The intense peak at 0.40 and 4.5 KeV confirms the presence of Ti.

Nyquist plots Polarization plots

Materials Rct

(Ω cm-2 )

IE (%) icorr IE (%)

Bare 1043 --- 97.94 -0.1 M ATA 5051 95.3 18.4 81.20.1 M ATA + 10-3 M TiO2

11549 98.8 0.982 98.9

Thus, the study revealed that the incorporation of TiO2 at lower concentration decreases the porosity of the polymer and significantly increases the inhibition efficiency

Work done in our lab...

Electropolymerization of Electropolymerization of MMTAMMTA

Electropolymerization of MMTA done using 0.1 Electropolymerization of MMTA done using 0.1

M MMTA with 0.5M methanol/NaOH by CV-by M MMTA with 0.5M methanol/NaOH by CV-by

scanning the potential between 0 to 1.7 V vs SCE at a scanning the potential between 0 to 1.7 V vs SCE at a

scan rate of 10 mV/s.scan rate of 10 mV/s.N

N

N

SH

CH3

slow

NN

N

S

CH3

e

NN

N

S

CH3

NN

N

S

CH3

nH

fast ne

H

NN

N

S

CH3

NN

N

S

CH3n

(peak A)

(peak B)

FT-IR spectrum of (a) TiO2, (b) p-MMTA and (c) p-MMTA/TiO2

CV of p-MMTA over copper surface

As the number of cycles were increased, the anodic current values decreased. This suggested the formation of insulating polymeric films.

The strong absorption at 694 cm-1 is due to Ti–O stretching. This band appeared weak in the IR spectrum of the composite. This result strongly suggested the interaction of TiO2 with polymer.

CV of poly-MMTA on Cu FT-IR spectrum

The 2θ values at 35, 55, 60, 63 and 70 indicated the presence of TiO2 in the polymeric matrix. It also confirmed the crystalline nature of the incorporated TiO2.

XRD pattern of poly-MMTA/TiO2

Corrosion Inhibition Studies of poly-MMTA/TiO2

Materials Rct(Ω

cm-2 )

IE (%) icorr(µA cm-2)

IE (%)

Bare/Cu 1081 --- 70.12 ---p-MMTA/Cu 2450 55.4 33.12 52.7p- MMTA/TiO2/Cu 5201 79.1 15.62 77.7

Nyquist plots Polarization plots

The increase in Rct values and decrease in icorr values suggested the higher IE of p-MMTA/TiO2 composite on copper

M. G. Sethuraman et al. DOI: 10.1007/s11164-014-1876-2

Electrochemical synthesis of poly-3-amino-5-mercapto-1,2,4-triazole (AMTA) on copper and its protective effect in 3.5% NaCl medium (Res. Chem. Intermed.)

Electropolymerization Electropolymerization of AMTAof AMTA

Electropolymerization of AMTA done using 0.1 Electropolymerization of AMTA done using 0.1

M AMTA with 0.5M methanol/NaOH by CV-by M AMTA with 0.5M methanol/NaOH by CV-by

scanning the potential between -0.7 to 1.2 V vs SCE scanning the potential between -0.7 to 1.2 V vs SCE

at a scan rate of 10 mV/s.at a scan rate of 10 mV/s.

CV of AMTA

Schematic representation of electropolymerization of

AMTA on Cu

As the cycle increases, anodic peak current decreases, suggesting the formation of polymer film at the electrode surface

FT-IR spectra of (a) AMTA and (b) p-AMTA film

AMTA

Effect of scan rate on electropolymerization of AMTA

Materials IE (%)

Bare Cu --

p-AMTA/Cu 81

Corrosion Inhibition Studies of p-AMTA on Cu

Electrodes – Ecorr icorr βa βc IE

(mV/SCE) (µAcm−2) (mVdec−1) (mVdec−1) (%)

A 194.4 39.87 91 206 -- B 163.3 13.63 122 179 65.8 C 302.9 11.73 110 222 70.5 D 307.9 7.02 102 131 82.3 E 99.9 4.97 138 173 87.5 F 200.6 3.14 126 151 92.1

A – Bare Cu; B – poly-AMTA-Cu; C – poly-AMTA-La2O3-Cu; D – poly- AMTA-CeO2-Cu; E – poly-AMTA-TiO2-Cu; F – poly-AMTA-nano TiO2-Cu

Polarization Studies of p-AMTA and its composites

Protection through Superhydrophobic coatings

Self- Cleaning Mechanism (a) Normal Smooth Surface, (b) Superhydrophobic Surface

3131

Cont……Neinhuis, C.; Barthlott W. Ann. Bot. 1997, 79, 667–677

Superhydrophobic coatings fabrication can be done by any of the following

methods

Electroless depositionElectroless deposition

Immersion techniqueImmersion technique

Work done in our lab

Electroless DepositionDepending on its position in the electrochemical series, a metal higher in the series may be covered (plated) with the metal lower down in the series.

A well known example is the coverage of iron on copper in an acidified copper sulphate solution.

Two reactions, one anodic and the other cathodic, take place simultaneously at the surface. 3434

Cont……

Fabrication of ultra-water-repellent copper surface

3535

Experimental Copper electrodes

Immersed in 0.01 M AgNO3 for 60 s

Ag/Cu

Immersed in 0.1 M CA-SA for 6, 12 and

24 h

SA-CA/Cu

SA-CA/Ag/Cu

1st Route 2nd Route

Immersed in 0.1 M CA-SA for 6, 12 and 24 h

Seth

uram

an e

t al

., Su

rf.

Inte

rfac

e A

nal.

2015

, 47,

423

.

H3CCOOH

8

H2N SH60 o CEthanol

H3C8

O

HNSH

H2O

Stearic acid Cysteamine SA-CA organic molecular hybrid

C18 H36 O2 C2 H7 S N

3636

Results and Discussion

4000 3500 3000 2500 2000 1500Wavenumber (cm-1)

C-H (2922) anti-symmetric methylene

C-H (2847) symmetric methylene

S-H (2363) stretching

N-H (1591) bending

C=O(1637) stretching

C=O (1700) stretching

d-SA-CA/Ag/Cu

c-SA-CA/Cu

b-Pure CA

Tran

smitt

ance

(%)

a-Pure SA

FT-IR spectra of (a) pure SA, (b) pure CA,

(c) SA-CA/Cu and (d) SA-CA/Ag/Cu

EDX spectra of (a) SA-CA/Cu and (b) SA-CA/Ag/Cu

Spectral and Elemental Analyses

C, N, O, S and Cu

Ag, C, N, O, S and Cu

5 µm5 µm5 µm

5 µm 5 µm5 µm

5 µm

Surface Analyses

SEM and WCA images of (a) Ag/Cu ,SA-CA/Ag/Cu and SA/CA-Cu surfaces at

different immersion times: (b,e) 6 h, (c,f) 12 h and (d,g) 24 h (insert- a

photograph of sisal flower)

AFM images of (a) SA-CA /Cu

and (b) SA-CA/Ag/Cu surfaces

Specimen Immersion time (h)

Water contact angle (0)

Sliding angle (0)

SA-CA/Cu 6 150±2 7±112 154±1 6±224 169±2 3±1

SA-CA/Ag/Cu 6 168±2 3±112 176±1 1±224 178±1 1±2

Wettability of the as-prepared SA-CA/Cu and SA-CA/Ag/Cu surfaces at different immersion times

3939

-8 -7 -6 -5 -4 -3 -2 -1 0-0.4

-0.2

0.0

0.2

0.4

3

2 1

c

b

a

E (m

V)

log i (µ A cm-2)

a-Bare copperb-SA-CA/Cuc-SA-CA/Ag/Cu

-7 -6 -5 -4 -3 -2 -1 0-0.4

-0.2

0.0

0.2

0.4

c ba

a-Bare copperb-SA-CA/Cuc-SA-CA/Ag/Cu

E (m

V)log i (µ A cm-2)

Potentiodynamic polarization studies

Potentiodynamic polarization curves of (a) bare copper,

(b) SA-CA/Cu and (c) SA-CA/Ag/Cu surfaces after 1 h of immersion in 3.5 % NaCl

solution

Potentiodynamic polarization curves of (a) bare copper,

(b) SA-CA/Cu and (c) SA-CA/Ag/Cu surfaces after 168 h of immersion in 3.5 %

NaCl solution

(1) e Cu Cu -

(2) CuCl Cl Cu -

(3) CuCl Cl CuCl --2

Apparent Tafel

Transpassive region

Limiting region

Time (h) Specimen Ecorr (V) icorr (µA cm-2)1 Bare copper -219.93 5.185

SA-CA/Cu -120.61 2.586

SA-CA/Ag/Cu -56.10 1.258

168 Bare copper -216.23 6.824

SA-CA/Cu -169.30 3.021

SA-CA/Ag/Cu -118.58 1.847

Relevant electrochemical parameters of potentiodynamic polarization curves of bare

copper, SA-CA/Cu and SA-CA/Ag/Cu electrodes in 3.5 % NaCl

0 30 60 90 120 150 180165

170

175

180

185

Stat

ic c

onta

ct a

ngle

(o )

Time (days)

SA-CA/Ag/Cu

Variation in the static water contact angles of the as-prepared SA-CA/Ag/Cu surface as a function of

exposure time

Durability of the as-prepared SA-CA/Ag/Cu surface

4242

Work carryout in our lab

4343

Mussel-Glue threads like superhydrophobic coatings fabricated on aluminium surface

Kart

hik,

N.;

Seth

uram

an, M

. G. N

ew J

Chem

. 39

(201

5) 3

337

EXPERIMENTAL

2 Al + 3 Cu2+ 2 Al3+ + 3 Cu (1)

2 Al + 6 H+ 2 Al3+ + 3 H2 (3)

Cu2+ + 2 CH3 (CH2)11 NH2 [CH3 (CH2) 11 N]2 Cu + 2H+ (2)

4545

Results and DiscussionSpectral and Elemental Analyses

4000 3600 3200 2800 2400 2000 1600 1200 800 400

C-H (900) out-of-plane deformation

N-H (900-700) wag

C-N (1105-1035) stretching

N-H (1643) bend

scissoring

C-H (2874) symmetric methylene

C-H (2929) anti-symmetric

methylene

N-H (3500-3400) stretching

b

a

Tran

smitt

ance

(%)

Wavenumber (cm-1)

a-Pure LAb-LA/Cu/Al

FT-IR spectra of (a) pure LA and (b) LA/Cu/Al

EDX spectra of (a) Cu/Al and (b) LA/Cu/Al surfaces (assembled for 3 h)

O, Cu and Al

C, N, O, Cu and Al

4646

20 µm

50 µm50 µm

Surface Analyses

SEM and WCA of (a) Cu/Al, (b) LA/Cu/Al (assembled for 1 h) and (c) LA/Cu/Al (assembled for 3 h) surfaces. Arrow marks indicated the

formation of Mussel glue threads and circles indicated the presence of copper dendrites. Inset: a photograph of Mussel glue threads

Sethuraman et al. Journal of Taiwan Institute for Engineers (Under Review)

78°

135° 154°

4747

0 2 4 6 8 10 12 14135

140

145

150

155

160

165

170

175a

Stat

ic c

onta

ct a

ngle

(deg

ree)

pH

LA/Cu/Al

0 15 30 45

120

130

140

150

160

170

180b

Stat

ic c

onta

ct a

ngle

(deg

ree)

Time (d)

LA/Cu/Al

Durability and pH test of the as-prepared LA/Cu/Al surface

(a) Effect of pH and (b) exposure in air on the superhydrophicity of LA/Cu/Al surfaces

Applications

Self-cleaning cloths, glasses, board etc.

Anticorrosion coatings

Energy storage ( batteries and supercapacitors)

Semiconductors

Oil/water separation

Anti-fouling