Adhesion

E. BarthelSeptember 2008

Recent review

Adhesive Elastic Contact – JKR and more, E. Barthel, J. Phys. D: Appl. Phys. 41 (2008) 163001

Cleaning windows…

Paris, Quai d’Orsay, August 23, 2008

Self cleaning

TiO2

Water

5 µm

Optical functionalisation

AgZnO

ZnO50 nm

Verre

22Damage morphology

damage morphology

Windshield – laminated glass

Laminated glass – impact testing

Standard test EN 356 :ball 4 kg / 8 m / 2 times

Glass strengthening

Brittleness isfascinating

Afasia 1Arcangelo SassolinoParis, Palais de Tokyo, August 2008

Lengthscales issue

Outline

Surfaces and interactions – adhesionMechanics at the local scale – crack tip

stressesMechanics at the macroscopic scale – remote

loading

Part I

Part I – Interaction stresses

1 Measuring the interactionsa) Surface forcesb) Derjaguin approximationc) Derjaguin approximation – Adhesion

2 Interactions and critical stressa) various interactionsb) critical (rupture) stress

I.1.a) Surface forces measurement

AFM – contact force modeLiquid medium

d[nm]

Classical force curve

40

30

20

10

0

-10

-20

-30

Def

lect

ion

Sign

al [n

m]

12080400Seperation [nm]

approach retract

Before irradiation

Jump to contact

Separation [nm]

Interaction potential – Interaction stresses

z z

(z) (z)

I.1.b) Derjaguin Approximation

δ

I.1.c) Derjaguin Approximation –Adhesion

Pull out force

1932 Bradley1932

d1

d2

with silica spheres

sous vide…préhistorique

Scaling issues – small is… sticky

macroscopic forcesgravity but alsoinertiaaerodynamics

surface forces

The cut-off distance is about 1 mm !…equal to a capillary length

…strange

I.2.a) Example: van der Waals forces

TiO2 Anatase – UV irradiation

-30

-20

-10

0

10

F/2π

R

[10

-5 J

.m-2

]

200150100500

Irradiation time [mn]

12

10

8

6

4

2

0F/

2πR

[1

0-5 J

.m-2

]250200150100500

Sample-tip separation [nm]

Irradiation time

Before UV 5 mn UV 15 mn UV 30 mn UV

Ramzi Jribi, PhD thesis

Very short range surface forces measurements

Lantz, Science,291(2001) 2580

I.2.b) Rupture stress

Interaction potential

Rupture

OrowanKohn Sham 1974

orders of magnitude – adhesion energies and critical (rupture) stresses

Part II

Irwin ERR Intro

J. Appl. Mech.1957

Part II – remote loading

Crack propagation – Energy release rate1) Linear system

a) Peel test and asymmetric vs symmetric peelb) DCB measurement for thin filmsc) crack deflection

2) Non linear systema) hertzian contactb) adhesion and elastic deformation: Derjaguin 1934 II

Crack propagation – Energy release rate

Energy release rate

Equilibrium

II.1.a) 90° Peel test

II.1.a’) (A)symmetric peel test – Elastic stripethylene propylene rubber / PMMA + thin EPR film10 cm wide / 12 mN / applied 60 mna: no propagation / b: crack speed 2 µm/s

K. Kendall, J Adhes Sci Technol 8 (1994) 1271

II.1.b) The Double Cantilever Beam (DCB)

L

δ

Epoxy gluebond layer

OpticalmultilayerSubstrate

Backing

A1

II.1.b) The Double Cantilever Beam (DCB)

Linear system

Energy release rate

or

Impacts the stability

with

DCB adhesion energy measurement

Side view

Top view

Actuator Blade holder Sample Sampleholder

Blade Sample

Ruler

experimental set-up

DCB – results

6x104

5

4

3

2

1

0

δ2 (µm

2 )

8x1066420(L+0.64h)4 (mm4)

w = 2.4 J/m2

w = 0.8 J/m2

Obreimov, Kanninen

Barthel et al. Thin Solid Films, 2005

Indentification of the interfaces - XPS5x10

4

4

3

2

1

0

Cou

nts

600 500 400 300 200Binding Energy (eV)

Ag

3d

Ag

3pZn

AugerO

1s

backingside

substrateside

Ag

ZnO

ZnO

// is the locus of failure

1 Glass / Si3N4 // Ag / ZnO 0,7 J/m2 ± 0,2 (2 s.)

2 Glass / ZnO // Ag / ZnO 1,5 J/m2 ± 0,2 (2 s.)

3 Glass / TiO2 / Ag // ZnO 2,1 J/m2 ± 0,7 (3 s.)

4 Glass / SnO2 / Ag // ZnO 2,4 J/m2 ± 0,1 (3 s.)

underlayer

Deposition is not at equilibriumSilver on oxide:

Ambiant Temperature

High

Temperature

History matters:

Ag does not wet ZnO; ZnO wets Ag

cf also Lin and Bristowe PRB 2007

Adhesion – crack propagation in structured interfaces

Sample A : Single Scratch Sample B : Multi scratch

10005000x (pix)

1400

1200

1000

800

600

400

200

0

h(x)

(pix

)

Front n° :01020304050607080910111213141516171819

10005000x (pix)

1400

1200

1000

800

600

400

200

0

h(x)

(pix

)

Front n° :01020304050607080910111213141516171819

12008004000x (pix)

1200

1000

800

600

400

200

0

h(x)

(pix

)

Front n° :050607080910111213141516171819202122232425

12008004000x (pix)

1200

1000

800

600

400

200

0

h(x)

(pix

)

Front n° :050607080910111213141516171819202122232425

Dalmas et al. 2009

II.1.c) A more complex examplecrack deflection (kink)

Cook-Gordon 1964, Kendall 2004

Thin film – instability under sliding contact

X. Geng, PhD

II.2) Adhesive contact

II.2.a) Hertz contact

II.2.b) Derjaguin 1934 Part II

Energy

Penetration and forceDerjaguin,Kolloid Z., 69, 155 (1934)

Derjaguin 1934 Part II

Pull out force

Part III