Ordem dos Engenheiros, Região Sul – dia/ mês/ 2018Ordem dos Engenheiros | Região Sul | 16 de outubro de 2018

Os Novos Desafios da Engenharia

Ciclo de Conferências

Espaço, Terra e Mar

Os Materiais Auto-Reparáveis e a Sustentabilidade

Mário Ferreira

Universidade de Aveiro

16 de Outubro, 2018

“What is a scientist after all? It is a curious man

looking through a keyhole, the keyhole of nature,

trying to know what's going on.”

Jacques Cousteau (1910-1997)

Mimicking Nature...

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(E.D. Hutchins et al., PLOS One, DOI: 10.1371/journal.pone.0105004)

http://www.natgeocreative.com

Self-healing

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futureprospects.wordpress.com

-superhydrophobic effect (CA>150º)

-combination of hierarchical structures at micro

and nanoscale (roughness) and chemical

compositionF. Xia, L. Jiang, Adv. Mater. 20 (2008) 2842.

Lotus effect

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www.gettyimages.com

Smart adhesive: heriarchical structures allow

for a mechanical control of adhesion,

depending on the adequate orientation of

setae (cedras)

Autumn, K. (2006). How gecko toes stick. American Scientist

94, 124–132.

Tokay Gecko

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Result of optical phenomena such as interference,

refraction, difraction (not due to the presence of

pigments)

F. Xia, L. Jiang, Adv. Mater. 20 (2008) 2842

http://www.webexhibits.org/

Structural coloration

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livelymoo.wordpress.com

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Key factors for introduction of new technologies:

-economic needs;

-reduction in environmental pollution;

-improvement of performance: anti-corrosion, durability, etc.

New technologies

Self-healing materials

Materials that can heal defects leading to extended service life and

reducing degradation/failure of material

Autonomic – defects activate the healing mechanism

Non-autonomic – requires external stimulus for healing

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• Capsule-basedEntrapment of healing agent in discrete capsules. Upon rupture by damage, healing agent is releasedinto the region of damage (singular local healing event).

• VascularEntrapment of healing agent in a network form of capillaries, hollow channels which may beinterconnected. Upon damage, release of healing agent occurs. The network may be re-filled (multiplelocal healing events).

• IntrinsicNo healing agent. Latent self-healing functionality which is triggered by damage or external action(multiple healing events).

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Blaiszik et al., Annu Rev Mater Res 40

(2010) 179-211.

B.S.H. Cho et al., Adv. Mater. 18 (2006) 997-1000.

Encapsulated catalystpolyurethane microcapsules

(di-n-butyltin dilaurate) - yellow

Repairing agent Siloxane-based agent is not encapsulated

but phase separated – white

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Capsule-based healing

R.S. Trask, I.P. Bond, Smart Mater. Struct. 15 (2006) 704–710.

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FRPs

Vascular-based

healing

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Extrapolated Corrosion Costs: $276 billion,

3.1% of GDP

State and Local

Government, 3.0%

$8.3 Billion

Transportation and

Utilities, 34.9%

$96.2 Billion

Construction, 18.1%

$50.0 Billion

Federal Government,

7.3%

$20.1 Billion

Services, 5.2%

$14.3 Billion

Manufacturing,

31.5%

$86.8 Billion

NACE, USA

Corrosion

costs

2-4 %

PIB

Service-life conditions of cars

T: +70ºC to -50ºC

DT: 10-20ºC during day

Stone chiping

High loads of salts

High UV exposure

Physical stresses (car washing)

...

No single coating can meet all the requirements.

Multilayer coating system is necessary!

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Substrate

Surface treatmentCr(VI) free pre-treatment

Cr-loaded Primer

Top Coat

Cr(VI) Cr-free protection

Substrate

Active Pre-treatment

Cr-Free Primer

Top Coat

Past... Present...

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reduction in environmental pollution

Automotive industryPre-treatment: inorganic

phosphate conversion layer 1-2

mm (increase surface area and

corrosion protection)

Cathodic electrocoating: passive

corrosion protection (20-22 mm).

Primer surfacer: cover

uneveness, protection against

stone chipping and provide anti-

corrosion properties.

Colored topcoat: applied in two

steps without curing in between,

with a basecoat and a clearcoat.Car body: steel, galvanized steel, aluminum

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http://www.nissan-global.com/

https://secure.drivers.lexus.com/

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Self-repair coating

Minimum film thicknesses have to be used since

weight is an extremely sensitive parameter for

utilization and energy costs.

The structural components for an aircraft are

pretreated separately and in the case of

aluminum they are anodized or chromated.

The corrosion protection primer is based on an

epoxy resin which cures with amines or

isocyanates at room temperature. Chromate-

containing active pigments are still used today.

The topcoat is made with a 2-component PUR

paint and has high gloss, color fastness and

weather resistance.

Aeronautical industry

Top coat 50-200 mm

Primer 5-200 mm

Pre-treatment <60 nm

Substrates: aluminum alloys,

steel, CFRP, titanium

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Maritime industry Surface pre-treatement: sand

blasting.

Primer: anti-corrosion protection

(250-400 mm).

Tie coat: promote adhesion

between layers.

Top coat: anti-fouling coating (>

300 mm).

The overall paint scheme can be

in the mm range.

In addition to corrosion protection

ships are also cathodically

protected by active anodes or

external current (the coating has

to withstand alkaline

environment).

Substrate: steel (carbon steel)

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Courtesy of JOTUN AS

-hull surface becomes rough due to the growth of algae and

barnacles increasing the ship’s fuel consumption up to 40%;

-increases GHG emissions;

-adds strain on the structure and hinder maneuverability.

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FP7-OCEAN-2013 Proposal for a Collaborative RTD project BYEFOULING Part B

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comprising macroscopically visible algae (seaweeds) and invertebrates such as soft corals, sponges,

anemones, tunicates and hydroids (after 2 or 3 weeks of immersion), and c) “hard macrofouling”2 (e.g.

ascidians, mussels, barnacles).

It is often stated that surface colonization follows a linear ‘successional’ model3,4,5

in which bacterial biofilm

formation is followed within a week by spores of macroalgae (seaweeds), fungi and protozoa, followed in

turn, within several weeks, by larvae of invertebrates, such as barnacles. This ‘classical’ view is a

simplification as motile spores of seaweeds are capable of settling within minutes of presenting a clean

surface and larvae of some species of barnacles or bryozoans settle within a few hours of immersion2.

However this “successional model” becomes of great use when determining the action spectra for most biocide and foul-release materials, always taking into account that, while there is a relationship among

different stages, it cannot be assumed that blocking initial stages completely eliminates later ones. Therefore,

a global action against different stages is required for an antifouling material to be effective.

Figure 1-2. Diversity and size scales of a range of representative fouling organisms.2

Figure 1-3. Colonisation process of marine fouling6.

2 J. Callow, M. Callow, Trends in the development of environmentally friendly fouling-resistant marine coatings. Nat. Commun., 2011, 2, 244. 3 L. Chambers, et al., Modern approaches to marine antifouling coatings. Surf. Coat. Technol., 2006, 201, 3642–3652. 4 C. Magin, et al., Non-toxic anti-fouling strategies. Mater. Today, 2010, 13, 36–44. 5 A. Rosenhahn, et al., The role of ‘inert’ surface chemistry in marine biofouling prevention. Phys. Chem. Phys., 2010, 12, 4275–4286. 6 M. Lejars, et al., Fouling Release Coatings: A Nontoxic Alternative to Biocidal Antifouling Coatings. Chem. Rev., 2012, 112 4347–4390.

Stage 1 Biochemical

conditioning

surface

Stage 2 Bacterial colonisation

Stage 3 Diatom and

protozoan

colonisation

Stage 4 Settlement of invertebrates

larvae and algal spores

M. Lejars et al., Chem. Rev. 112 (2012) 4347–4390.

Biofouling

M.L.Zheludkevich et al., Chem. Mater. 19 (2007) 402-411.

D.G.Shchukin et al., Adv. Mater. 18 (2006) 1672–1678.

D.G. Shchukin et al., J. Phys. Chem. C 112 (2007) 958-964.

Polyelectrolyte shells: pH-dependent

permeability for controlled release of

corrosion inhibitor

LbL (Layer-by-Layer) assembly

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Functional self-healing of coatings

Controlled release of corrosion inhibitor

Coating recovers its function

after healing, within defects/flaws

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Cl-

Cl-

Cl-

M.L.Zheludkevich et al., Chem. Mater. 19 (2007) 402-411

Chitosan

Chitosan - linear polysaccharide obtained from the partial deacetylation of Chitin

Chitin - second most abundant polysaccharide after cellulose

main component of exoskeleton of crustaceans and insects

Source of images: internet

O

O

HO

NH

OH

O

O

HO NH

OH

O

O

HO

NH2

OH

O

OHO NH2

OHCH3

O

CH3

O

n

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3

4 5

6

1-DADA

Chemical structure of copolymers (chitin (DA>>1-DA) and

chitosan (1-DA>>DA)) of N-acetyl-D-glucosamine (molar

fraction=DA) and D-glucosamine units (molar fraction=1-

DA). Generally, chitin DA> 0.50 and chitosan DA<0.50

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The new A350XWB

Composites 53%

Aluminum alloys 19%

Titanium 14%

Steel 6%

Misc. 8%

http://www.a350xwb.com/advanced/fuselage/

F. Capezzuto et al., Composite Structures 92 (2010) 1913–1919

Sensing coating for detection of

mechanical impacts

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Effect of reinforcement corrosion on

structural behaviour

Cracking and spalling of cover concreteCorrosion products has a volume 2-4 times than that of steel, causing volume

expansion, developing tensile stresses, and cracking.

Catastrophic failure of structureReduce cross-section of steel.

Pitting can reduce the section at a point, no longer withstand the applied load.

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Geim and Novoselov isolated graphene in

2004 at the University of Manchester.

They won the 2010 Nobel Prize in Physics

for their work with graphene

Graphene: the new hype in corrosion?

Graphene is the world’s first 2D material

-Thin layer of pure carbon

-Tightly packed layer of carbon atoms

bonded in a hexagonal honeycomb lattice

-Layers of graphene stacked on top of

each other = graphite

https://www.extremetech.com/

http://www.graphene.manchester.ac.uk/

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Hypothesis: if graphene exhibits execellent barrier properties and is very

good electrical conductor this can be a perfect form for obtaining some sort

of noble character in active metals!

Not exactly!

ACS Nano, 7 (2013) 5763-5768

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Is this the end of line for graphene in

Corrosion Science and Engineering?

Potential properties for coating technologies

• The 2-D structure of graphene and graphene oxide may in increase barrier

effect within polymeric matrices (increase in tortuosity for diffusion of

species);

• Graphene can also be modified to be used as nanocontainer for delivery of

inhibitors.

Challenges

• Cost effectiveness compared to other potential systems (e.g. clay materials);

• Availability of material in large amounts;

• Application technologies.

• ...

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• Ordem dos Engenheiros pelo Convite para esta apresentação.

• Prof. João Tedim da Universidade de Aveiro por me ter permitido usar

nesta apresentação vários “slides” por ele preparados para a “3rd

International Summer School on Multifunctional Smart Coatings and

Surfaces”, que teve lugar de 16 a 20 de Julho de 2018 no Departamento

de Engª de Materiais e Cerâmica da Universidade de Aveiro.

Agradecimentos