SE02: Improved Design and Manufacture of Polymeric...

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SE02: Improved Design and Manufacture of Polymeric Coatings Through the Provision of Dynamic Nano-indentation Measurement Methods Lead Scientist: Nigel Jennett Project Manager: Lesley Henderson Characterisation Programme (2006-2009)

Transcript of SE02: Improved Design and Manufacture of Polymeric...

Page 1: SE02: Improved Design and Manufacture of Polymeric ...resource.npl.co.uk/materials/programmes/characterisation/pw/polymers/... · Ideal for measuring elastic and plastic properties

SE02: Improved Design and Manufacture of Polymeric Coatings Through the Provision of

Dynamic Nano-indentation Measurement Methods

Lead Scientist: Nigel Jennett

Project Manager: Lesley Henderson

Characterisation Programme(2006-2009)

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Presentation outline

• Introductions to:– SE02 science team– The project motivations– Instrumented indentation

• SE02 Project outline

• Industrial involvement

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SE02 Science Team

Surfaces, Coatings and Nano-Mechanics Group- Nigel Jennett (Lead Scientist)- Miguel Monclus- John Nunn- Tony Maxwell (now in Polymers group)

Modelling / Finite Element Analysis- Louise Crocker

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Motivation

• Requirement for local polymer properties in part design:-– bearings, gears, cams, press-fit parts, composites (matrix and

interfaces)• Requirement for properties of small volumes

– e.g. mico-mouldings, packaging, coatings.• Production control and QA via sensitivity of surface to

production parameters. – Thermal history affects surface properties and can be detected

by indentation.

Nanoindentation has the resolution but polymers have time/rate dependent properties.⇒ Dynamic measurement methods are required!

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Scientific Objectives

• Validate indentatin protocols for measuring loss and storage modulus and time constants of visco-elastic materials and feed into:

• ISO standardisation (new work item)• Development of 1GPa certified reference material

• Compare methods to measure polymer properties as a function of frequency and temperature.

• Develop ultra-rapid indentation and creep-relaxation measurement methods for characterisation of visco-elastic materials.

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Traditional Hardness – a quick and easy QA tool

d

F

HV = const x F/d2

Limited by optical resolution

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Instrumented Nanoindenter Schematic

StageLOAD FRAME

Magnet

IndenterCapacitanceDisplacementGauge

Suspensionsprings

Sample

Coil

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Instrumented (Nano)indentation

0.73

loading unloading

samplesample

loading unloading

samplesample

loadingloading unloading

samplesample

loading unloading

samplesample

loading unloading

StageLOAD FRAME

Coil

Magnet

0.73

AreaForceHIT =

Cf

Frame

Compliance

SC CAE 11* ×∝

Contact

Area

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Typical material responses

Aluminium

Plasticwork

Alumina

Elasticwork

Plasticwork

Data courtesy of VAMAS TWA22

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Indentation Contact Mechanics

• Contact mechanics after Hertz and Sneddon†

– As with traditional Hardness, pile-up / sink-in is not accounted for– †See I.N.Sneddon, Int. J. Engng. Sci., 3 (1965) pp. 47-57

0.73

For near perfectly plastic materialse.g. metalsAc ≈ residual area⇒ HIT α HV

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Nano-indentation applications

Ideal for measuring elastic and plastic properties of small volumes of materials, e.g. thin films and micro/nano-structures.

• Coatings and Surface Engineering sectors / users, e.g. Electronics, optics, automotive, aerospace, biomedical, pharmaceutical sectors..

• Local/surface properties of biological or polymeric materials (very soft, low force indentations)

• Micro-mouldings, nano-composites and ultra hard coatings where indentation depths are very small.

• Nano-mechanical testing of nano-engineered structures and materials

• Designers needing input data for models

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Scanning Indentation Mechanical Microprobe SIMM: Human Tooth

125 250 375 500 625 750

-4 -2 0 2 4 6

-1.25

-2.50

-3.75

-5.00

Typical scan, 200 by 100, takes ~30 hours (20,000 indents!)Maximum load 5 N, load resolution 2 mN, depth resolution 20 nm

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Creep affects H and E

0.0 0.2 0.4 0.6 0.8 1.0 1.20

10

20

30 Loading time 92sHold period

0.1s 15s 30s 120s 215s

Load

(mN

)

Depth (µm)

[Chudoba and Richter Surf. Coat. & Tech. 148/2-3 (2001) 191-198]

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Wait until Creep rate drops (or unload quickly)

1.00 1.05 1.10 1.15

15

20

25

30Loading time 92s

Hold period 0.1s 15s 30s 120s 215sLo

ad (m

N)

Depth (µm)

Creep rateInsignificantafter 215 s(soft metal)

Diagram from: Chudoba and Richter. Surf. Coat & Tech. 148/2-3 (2001) 191-198

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Schematic Indentation cycle

0.73

Cf

Creep / Viscosity

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Polymers: Dynamic Indentation“Continuous Stiffness”

• Hardness and modulus of visco-elastic materials• Superimpose a.c. signal on d.c. force ramp• Phase shift and amplitude related to contact stiffness

-4

-3

-2

-1

0

1

2

3

4

0 10 20 30 40 50 60 70 80 90 100

Time (milli-seconds)

Forc

e ( µ

N) /

Dis

plac

emen

t (nm

)

DisplacementLoad

Phase Shift

Amplitude

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Spring and dashpot model

( )εσ EiE ′′+′=

M

( ) ( )( )ωωωδ

EE′′′

=tan

E′= Storage modulusE″= Loss modulusδ = Phase shiftTan δ = Damping coefficient-4

-3

-2

-1

0

1

2

3

4

0 10 20 30 40 50 60 70 80 90 100

Time (milli-seconds)

Forc

e ( µ

N) /

Dis

plac

emen

t (nm

)

DisplacementLoad

Phase Shift

Amplitude

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Adhesive cure control – Car Timing Belts

OC

HNBR

Glass

RFL

Interface

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 10 20 30 40 50

Position, µ

Ela

stic

Mo

du

lus,

GP

a

Glass cord

FabricGlass cord Fabric

Nanoindentation modulus measurement of Interface properties used to improve cure cycle and reduce adhesion failure.

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High-temperature Testing:0.1 mN to 20 N

MicroMaterials NanoTestHot stage – sample temp ≤500°C

Force

Heaters

Depthsensor

Mapping the hardness of tribological coatings

5.2 micron Ion-beam Assisted Deposition (IBAD) Alumina; Stephen Abela, Unversity of Malta

Harder phase to provide abrasive resistance

Softer phase to provide toughness

H(GPa)

ScanScan

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Dynamic indentation

ON

NanoTest (Micro Materials Ltd, Wrexham)

• Dynamic nanoindentation• Repetitive impacts at low force (mN)• Displacement monitored with time• Observe fracture & delamination

Test Variables

• Impact energy• Impact Frequency• Test probe geometry

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Dynamic indentation

OFF

NanoTest (Micro Materials Ltd, Wrexham)

• Dynamic nanoindentation• Repetitive impacts at low force (mN)• Displacement monitored with time• Observe fracture & delamination

Test Variables

• Impact energy• Impact Frequency• Test probe geometry

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Supplementary Data Acquisition

Supplementary DAQ System

÷2

NanoTest Control Box

Interface

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Practical Impact Parameters

ON

AcceleratingForce

Distance

Standard Set-upForce 0.1 mN to 16 mNDistance 5 µm to 20 µm(I.e. Energy 0.5 nJ to 320 nJ)

Modified Set-upIf larger solenoid usedForce >500 mN

If Capacitor plate separation adjustedDistance >1mm(I.e. Energy > 0.5mJ)

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Impact test5µm conical indenterSingle crystal aluminium

Individual data points…20k samples.s-1 (up to 500K/s possible)

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35 nJ impact energy

PolycarbonatePolypropylene

WC-Co,Ni

Elastic recovery

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Automated determination of contact points

X1V1T1

X3 X6X4V4T4

X5X2V2T2

h

v

• Initial acceleration

• Velocity In

• Initial contact

• Max penetration

• Velocity Out

• Loss of contact

• Max rebound height

• Secondary contact

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FEA of nano-impact testing(ABAQUS Explicit model) Indentation of Aluminium single crystal

Indenter given mass and initial velocity

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FEA of nano-impact testing

Indentation of different materials- aluminium, nickel and polycarbonate

0

50

100

150

200

250

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016

time

Forc

e (m

N) nickel

polycarbonate

aluminium (yield stress = 12 MPa)

Accelerating force of 10 mN over 20 microns

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FEA of nano-impact testing

Indentation of Aluminium single crystal

Force predictions depend on yield stress used

0

20

40

60

80

100

120

140

160

180

200

0 0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035 0.004 0.0045 0.005time

forc

e (m

N)

yield stress = 75 MPa

yield stress = 12 MPa

Aluminium single crystal

accelerating force of 10 mN over 20 microns

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Stage Plans

Stage 1 (1/4/06 – 31/3/07)Selection/procurement of materials

Calibration and algorithm sensitivity studies

Development of dynamic calibration method (NPL Report)

Stage 2 (1/4/07 – 31/3/08) Design and test temperature stage

Development of ultra-rapid indentation method

Frequency, sweep and chirp

High rate indentation method (scientific paper)

Stage 3 (1/4/08 – 31/3/09)Visco-elastic models

Evaluation of temperature stage

High Rate indentation method at elevated temperatures (scientific paper)

Validated protocols/Input to ISO standards

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Industrial involvement

• Materials supply– Highly reproducible “standard” polymers– Industrial components / materials

• Collaboration for characterisation comparisons– Property data from other test methods as function of

frequency and temperature• Case studies / feasibility of adoption of method

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DeliverablesProject Description

D1: Validated protocols for room temperature measurement of mechanical properties of polymer surfaces or coatings (NPL Report).

D2: Refinement of current methods into intelligent miniaturised tests (scientific paper).

D3: Mechanical properties of polymer surfaces or coatings as a function of temperature (scientific paper).

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SE02 GANNT chart