12/6/07

1/3/08

Next generation carbon fibre composites

Patrik Fernberg

The Swerea group 2010

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Swerea IVF

Industrial product manufacturing, textile, polymers,

ceramics

Swerea KIMAB

Material use, material and process development, corrosion

Swerea MEFOS Metallurgy, metal heating

Swerea SICOMP Composite material, process and product development

Swerea SWECASTCast metals – product, material and process development

MD: Tomas ThorvaldssonOwner: Industry 53 %, RISE 47 %Turn over: 550 MSEKNo of employees: 450Company representation: 600 companies in different trade associations

Factfile - Swerea

Swerea SICOMP

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MD: Hans HanssonOwner: Swerea (100%)Turn over: 29 MSEKNo of employees: 31

Factfile - Swerea SICOMP

Piteå

Mölndal

Carbon fibre composites in primary load carrying structures

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Potentials for composites in aero engine application

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Composites can be used outside this line

Guide vanes

Fan case

Fan blades T < 120°C

Image presented by courtesy of Volvo Aero

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Desired composite characteristics

Damage tolerant composite material– material that can withstand high load (mechanical, thermal etc)

without defects or damage being created– material in which small defects do not easily grow to larger

critical defects• No manufacturing induced defects

• Good adhesion between fibre and polymer matrix

• Tough polymer matrix

Maintain load carrying capacity at high temperatures• polymer matrix resin with high glass transition temperature, Tg

Development of resins for CFRP

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Source: Smith PA In: Comprehensive Composite Materials, Kelly (Ed), Zweben (Ed)Images by courtesy of Per Hallander, Saab

Epoxy base

hardener hardenerEpoxy base

toughener

hardenerEpoxy base

toughener

Thermoplastic particles

hardenerEpoxy base

(Toughener)

(Thermoplastic particles)

Nanoparticles provides

enhanced or new properties

1st generation 2nd generation 3rd generation next generation !?

Potentials with nanocomposite resins

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Toughness enhancement Electrical conductivity Thermal conductivity

+ other functional properties (magnetic, barrier, shrinkage etc)

Source: Thostenson & Chou, Carbon (2006) Source: Thostenson & Chou, Carbon (2006)

Main obstacles – processing related

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Dispersion Viscosity increase Filtering (distribution)

Two epoxy-CNT nanocomposites (0.1% CNT)

Cross-section showing partially clogged flow channel between bundles

Increase by up to 3 orders of magnitude for CNF-suspensions

Source: Xu In: Processing and properties of nanocomposites, Advani (Ed)

Filtering of carbon nanotubes during resin transfer moulding

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Filtration No visual filtration

Vf ~ 58% Vf ~ 42%

More CNT filtering – influence of fibre architecture

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No MWCNTVf ~ 42 %

0.5% MWCNTVf ~ 42 %

0.5% MWCNTVf ~ 50 % Source: Nordlund, Fernberg, Lundström,

Composites Part A

Possible composite manufacturing solutions for nanocomposites

Technologies under investigation: Manufacturing with nanomodified prepreg tapes Position nanoparticles on fibre reinforcement Commingle nanocomposite and reinforcing fibres Coarse reinforcing structure to minimize flow resistance and

filtering

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Conceptual route: Tailor composite manufacturing for minimal flow length of nanodoped phase !!!

Manufacturing with nanomodified prepreg tapes

Some commercial systems becoming available Our current work is devoted to study processability issues and

consequences of low flow and air/gas permeability in doped prepreg Concept currently evaluated in FP7-project, Laysa, Interreg-project

Nakomate and to be further studied in NFFP5-project Multimap.

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CNT-doped epoxy film

clay-doped epoxy film

Nanoparticles on fibre reinforcement

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Carbon fiber after EPD treatment

CNT grown on to carbon fibresSource: Qian, Bismarck, Greenhalgh, Kalinka & Shaffer, Chem Mater, 2008

1. Grow particles on to fibres Particles integrated (covalent bonds) with fibres Tendency to strongly reduce fibre strength

2. Deposit or place particles on to fibres Electrophoretic deposition (EPD) Manual impregnation No covalent bonds between particles and fibres Concepts currently evaluated in FP7-project, Laysa and

NFFP5-project Kanon

Commingled fibres

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Types of yarns– Thermoplastic matrix fibres– Thermoset matrix fibres

Potential advantages– Particulate distribution– Short flow path (reduces problems

with high viscosity)

Concept to be evaluated/developed in FP7-project, FireResist. Starts 2010

Coarse reinforcing structure to minimize flow resistance and filtering

• Coarse reinforcement structure made from e.g. towpreg (preimpregnated fiber tow)

• Casting or resin transfer moulding of resin with high particle loadings

• Possible to reduce thermal expension of casting epoxies in high precision articles with moderate load carrying requirement

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Carbon fibre preform Preform impregnated with epoxy containing 50% (by volume) silica-particles (5 – 100 m]

Results from ongoing work Manufacturing concept:

Position nanoparticles on fibre reinforcement

Cross-ply laminates, [0/903]s

Tenax-E HTS 5631 Carbon fibre– Sigmatex UD-weave

– Surface weight 262 g/m2

HexFlow® RTM6 (Hexcel)– Monocomponent epoxy resin formulation

– Certified for use in aeronautic industry

– Tg 160 – 200°C (DMA)

MWCNT– Graphistrength CL1-020 by ARKEMA

– Provided as pre-dispersed aqueous dispersion

– (2g CNT / 100ml H20).

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Carbon fibre layup

0° 0°90°

Graphistrength CL 1-020

RTM-manufacturing of laminates

23-04-21 6th International ECNP Conference, Madrid 18

RTM-tool Laminate after demouldingImpregnation with H2O–based CNT dispersion

Preform preparation Composite manufacturing

Mechanical characterisation Apparent Interlaminar Shear Strength (ILSS)

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hw

PR4

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Standard EN2563

r – radius of support (3 mm);

h – thickness of the specimen (2 mm);

L – length of the specimen (20 mm);

lv – support span length (10 mm);

w – width of the specimen (10 mm)

Loading rate 1 mm/min

L

lv

h

r

The apparent shear stress at which failure occurs is given by:

PR is maximum force at failure

Results ILSS

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Laminate Average ILSS [MPa] Standard deviation [MPa] No of samples

Ref 73.6 7.7 7

Doped 83.2 2.4 8

13 % improvement with CNT-doping

Stiffness reduction due to crackingresults from tensile loading-unloading experiments

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!!! Strain at onset of transverse cracking decrease with CNT-doping !!!Potential explanations:• CNT-agglomerates acts as stress concentrations• too high CNT-content creates poorly impregnated interphase around fibres and poor adhesionPotential solution:• more “gentle” and precise deposition technique (electrophoretic deposition), ongoing work!!

SUMMARY

Integration of nanocomposites and nanotechnology in next generation fibre composites will provide improved or new features to the materials and components

A major technical obstacle is to adapt composite manufacturing technologies for particle (nano- and microsized) material systems

The route to overcome obstacle is to tailor composite manufacturing for minimal flow length of particle doped phase

Four different manufacturing concepts with such potential were proposed Encouraging results from work on RTM-manufacturing with CNT-doped

reinforcement were presented:

– Interlaminar shear strength improvements was confirmed

– lower resistance against transverse cracking Current work includes similar manufacturing and evaluation of laminates

with fabrics treated by electrophoretic deposition (KANON)

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Some sponsors

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NFFP5

KANON

Kolnanorörförstärkta kolfiberkompositer

Multifunctional Layers for Safer Aircraft Composite

Structures

Aerospace Nanotube Hybrid Composite Structures with

Sensing and Actuating Capabilities

COMETA

Advanced Polymeric COmpounds and METAL

Matrix Composites for Excellent Performances

in Machine Tools applications

RISE - Research Institutes of Sweden