challenges for self-healing coatings on metals - sim … · challenges for self-healing coatings on...

SBO project NAPROM

Challenges for self-healing

coatings on metals

VUB – UGent – UA – Flamac

Herman Terryn

Research Group Electrochemical and Surface Engineering

Departement Materials and Chemistry

Vrije Universiteit Brussel

[email protected]

Introduction – NAPROM Multiple action corrosion protection

1. Self-healing coating

2. Encapsulated corrosion inhibitors

3. Leaching out of corrosion inhibitors

4. Defect closure by self-healing of polymer

Metal

Metal

Coating

Metal

Metal

Metal

Inhibitor expertise support at SURF

(support TU-Delft )

Self-healing polymer and supramolecular design and synthesis by PCR, UGent (F. Du Prez) and SC, UGent (R. Hoogenboom)

Coating morphology, chemical and interface analysis by SURF, VUB (H. Terryn, I. De Graeve)

Bulk and coating thermomechanical analysis by FYSC, VUB (B. Van Mele, G. Van Assche)

Electron microscopy support for coating analysis by EMAT, UA (S. Van Tendeloo, A. Abakumov)

Inhibitor mechanism by SURF, VUB

Polymer self-healing mechanism by SURF, VUB and FYSC, VUB }

Co-operative active

protection property

analysis by SURF and

FYSC

50 nm -5 µm

1 µm ?

metal

Consortium in NAPROM

Accelerated screening method for active corrosion

protection by SURF, VUB (A. Hubin) and Flamac (J. Paul)

Self-healing Coating

Polyester- urethane acrylate coating

=

“Shape Recovery” Polymer

Nano phase separated high Tg polymer (dark zones)

and polyester segments (light zones)

combining extreme toughness with the ability to

recover from mechanical damage by heating

Semi-crystalline PCL=Polycaprolactone soft phases, Tg 50-60 °C

Self-healing polymer

Fresh coating 2 scratches Healed coating

Stepwise healing Closed defect Major defect

Self-Healing - SEM

>50°C

<1min

Metal

Impedance Spectroscopy

Coating with Flexible Spacers

Virgin coating

Coating healed for the

second time

Healed coating

Coating scratched again

after healing

Scratched coating

SVET Analysis of Self-Healing

In 0,05M NaCl Before healing After healing

Metal

Spectroscopic techniques such as EDX and EELS provide elemental information, making the localization of elements available, furthering the understanding of the sample. The steel polymer interface. EELS elemental mapping reveals the location of the various components: the polymer (indicated by the carbon signal) fills up a indentation in the oxidized zinc surface.

Interface SH coating-galvanised steel

Inhibitor MERCAPTO-BENZOTHIAZOL

Encapsulation

Layered Double Hydroxides (LDH) Porous nanocapsules

10µm

SEM EDX

SEM

TEM

+MBT

40 nm

Leaching out

Surface Enhanced Raman Spectroscopy

LDH+MBT on AgProbe

SiNC+MBT on AgProbe

Blank AgProbe

H. Verbruggen,

K. Baerts

Metal

NSH-coating without inhibitors

High currents after 4 hr of immersion

In-situ SVET mapping above two micro-drill defects

NSH-coating with LDH + MBT

In-situ SVET mapping above two micro-drill defects

No corrosion detectable after 4 hr of immersion

Metal

Scale bar: 10 µm

Very Thin Shells

< 5µm

Scale bar 100 µm

Robust microcapsules

Protective

barrier

1st generation of Melamine

Formaldehyde (MF) capsules

plasticizer ~ 90% plasticizer content

MF

outer

shell

Accelerated screening of aging

phenomena of coatings (Flamac)

• Methods for determining aging properties and associated methods for

accelerated testing of aging phenomena in the field of the high throughput

development of coatings (Flamac)

• Early stage detection of coating defects

• Current status: o High-throughput accelerated ageing platform evaluated

Application of micro- and macro-

scratches Methodology developed for applying controlled

micro-scratch (cfr. ICON project SHREC WP 5)

– Micro-scratches1:

– order of magnitude:

– 10 μm wide, 5 μm deep

1Visualised with microscope of nano-indentor

Methodology to investigate the corrosion protection

given by a coating

Metals

Coating for

additional

protection

Developing new coatings:

Different formulations

Many conditions

FAST AND

RELIABLE

EVALUATION

METHOD

Corrosion rate

monitor device for

ranking

+

Impedance to

understand damage

mechanism

ZENSOR

+

ORP-EIS

ORP-EIS ZENSOR

• Corrosion ranking

• 2 electrode based device:

evaluate corrosion activity

• Possibility of in-situ

monitoring

• User friendly

• Simplified setup but

robust!

• Save time

• Trough

modelling

able to

understand

damage

mechanism

Signal:

Sum of all single

sines

Bode plot with info over noise levels

Supramolecular self-healing materials –

concept and design

Design:

Poster: A new class of supramolecular

thermoplastic elastomers for self-healing coatings

Lenny Voorhaar & Maria Mercedes Diaz

+ +

+ +

+ +

+ +

- -

- -

- -

- - mixing

Association of

charged end

blocks

Network crosslinked by

supramolecular interactions

Phase separated structure

Charged phase

high Tg

Uncharged

phase low Tg

Charged ABA-type triblock copolymers

Charged CBC-type triblock copolymers

Synthesis performed in UGent SC

+ +

+ +

+ +

+ +

- -

- -

- -

- -


thermal characterization

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

-90 -60 -30 0 30 60 90

He

at

ca

pa

cit

y /

J g

-1C

-1

T / C

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

-90 -60 -30 0 30 60 90

He

at

ca

pa

cit

y /

J g

-1C

-1

T / C

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

-90 -60 -30 0 30 60 90

He

at

ca

pa

cit

y /

J g

-1C

-1

T / C

Tg generated by the

association of

charged end blocks!

Tg 28°C


thermal characterization

The two Tg’s indicate phase separated

structure

DMA heating ramp shows the mechanical

properties of the supramolecular network.

Transitions the material undergoes are seen

by the drop in E’.

The supramolecular interactions keep the

material from flowing even at 80°C.




0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

-80 -60 -40 -20 0 20 40 60 80

He

at

ca

pa

cit

y /

J g

-1C

-1

T / C

Tg 28°C

Tg -41°C

0

30

60

90

0.1

1

10

100

1000

10000

-80 -60 -40 -20 0 20 40 60 80

los

s a

ng

le /

°

E', E

" / M

Pa

T / °C

E'

E"

Delta

Supramolecular self-healing materials -

morphology

OsO4 stains preferentially the charged

domains

The different domains can be differentiated

in the morphology of the material

The diffractogram gives evidence of

repeating structure and indicates distances d

(6-10nm)




TEM micrograph

Performed in EMAT-UA

Supramolecular self-healing materials -

morphology

max

2

qd

Repeating structure confirmed by SANS

Repeat distances d of 8-9nm are

observed.

Small Angle Neutron Scattering

(SANS)

Performed in ISIS by Dr. Rogers

0.1

1.0

10.0

0.01 0.1 1

I /

cm

-1

q / Å-1

Concept:

Rupture

Tamb

Healing

T> 2nd

Tg

↓scratch ~50μm wide Healing at 43°C

after 20min.


self-healing

Healing

T> 2nd

Tg


tuning network properties

0.1

1

10

100

1000

10000

-80 -60 -40 -20 0 20 40 60 80

E' /

MP

a

T / °C

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

-80 -60 -40 -20 0 20 40 60 80

He

at

ca

pa

cit

y /

J g

-1C

-1

T / C

• Changing the length of the end blocks allows

tuning network properties

+ +

+ +

+ +

+ +

- - - -

- - - -

0.1

1

10

100

1000

10000

-80 -60 -40 -20 0 20 40 60 80

E' /

MP

a

T / °C

0.1

1

10

100

1000

10000

-80 -60 -40 -20 0 20 40 60 80

E' /

MP

a

T / °C

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

-80 -60 -40 -20 0 20 40 60 80

He

at

ca

pa

cit

y /

J g

-1C

-1

T / C

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

-80 -60 -40 -20 0 20 40 60 80

He

at

ca

pa

cit

y /

J g

-1C

-1

T / C- - - -

- - - -

+ +

+ +

+ +

+ +

The length of the

charged blocks -> Tg

change and

mechanical properties

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