Growth of CNT on Carbon Fibre

reinforcement

Presented By :

Charu Lakshmi T.R

Sem:4 roll No:4

Materials Science Department

Outline

Introduction:Wood to Metal to carbon composite

About the title !!

what’s the need ??

Growth of CNT on carbon fibre

About the MethodProcedure

Benefits

Results & discussion

conclusion

Reference

Wood To Metal to carbon fibre composite

Carbon as

fibres??

CNT’s??

Composite??

Carbon Fiber : a material consisting

of thin, strong crystalline

filaments of carbon, and is used

as a strengthening material.

Carbon Nanotubes : a tube-shaped

material, made of carbon, having

a diameter measuring on the

nanometer scale

About the title !!

This photo shows the size of a carbon fiber

next to a human hair - the carbon fiber is the

smaller one. The small diameter of the fibers

combined with the number of fibers helps give

it the extra strength and keep it flexible.

A single walled CNT

growing CNT on carbon fibre and using it as a reinforcement in the composite is the aim of the research paper

What’s the need??

• In aerospace industry, metals are still being incorporated into structuresto impart electrical conductivity to avoid charge build up gained through air friction and lightening strikes.• Charge accumulation can lead to discharge sparks or material failure.• The addition of metals adds to the weight ,cost, leads to corrosion issues and has proven troublesome to consolidate with carbon fibre composite

• CNTs are either grown or attached to carbon fibre to form a fuzzy fibre which can be used as a reinforcement.• Initially, Dispersion of CNTs was done on polymer matrix with covalent and non covalent modifications ; surfactant addition ; by mechanical processing etc.• Problems with CNTs alignment, orientation, graphitization and agglomeration; Lack of morphology control and poor matrix infusion; were faced.• In this paper, Carbon fibre is taken as substrate and they are bothered with modification of reinforcement and not the matrix.• Dispersion related problems like agglomeration is solved; so a well dispersed,high density of less defective CNTs is obtained on the fibres.• These CNTs bridge adjacent fibres, creating electrical and thermal percolation pathways thereby increasing electrical properties.

So, Growth of CNTs on Carbon Fibres

• AS growing CNTs was advantageous over attaching it, in termsof the quantity, length, orientation, controllability of size of CNTs; it was followed.

• When growth temperatures is over 700°C and reactive atmosphere is present in CVD chamber, significant degradation of fibre occurs, ruining the mechanical properties.

• So they carried the growth of CNTs on the fibre substrate by maintaining it at low temperatures; without compromising on quality, yield or production time of CNTs.

• They used Surrey Nanosystems 1000n photo-thermal chemical vapour deposition(PTCVD) growth system, featuring a water cooled substrate table (5°C) and optical radiation for thermal heating.

• This arrangement enables part of carbon fibres to remain at low temperature whilst the catalyst on the carbon fibre(that is exposed to optical radiation) is allowed to reach high temperature necessary for growth of CNTs of high crystalline quality.

Method Followed !!

Procedure

• Iron was deposited on both side of the carbon fibre surface using magnetron sputtering(JLS MPS500 DC sputtering).

• Sample was loaded into the PTCVD apparatus.

• After reducing pressure to about 2 torr , hydrogen gas(100sccm) was introduced into the chamber, and optical heating(4kw) was employed to reduce the iron oxide.

• After annealing for 5 min , acetylene(20sccm) was injected into the chamber and the growth process was performed for 10 min on each side of the carbon fibre.• The temperature was recorded by a thermocouple, which was in contact with the sample holder, which is exposed to the sametreatment as the carbon fibre substrate.

Benefits of the method

• After CNT growth , the thermal radiation( sourced by an array of halogen lamps) can be turned of quickly enabling the system to cool down in short time i.e. 5 min, which greatly improves the sample throughput yield( 8 times the throughput of conventional CVD systems).

• Better electrical properties obtained to minimum degradation of fibres.

• As it employs optical heating instead of resistive heating , where there is not much higher thermal resistance between it and catalyst sites, the system reduces amount of energy required for growth and reduces amount of gas used for cooling.

• This method is large area compatible and directly transferable to industrial manufacturing companies.

• Nanotubes can be hundred times stronger than steel, but only one-sixth the weight, making such composites attractive for use in airplanes, cars, trains, spacecraft and satellites.

BEAUTY with Classic duty

SEM images of (a) a bundle of carbon fibres following CNT growth (low magnification), (b) a single carbon fibre following CNT growth (high

magnification)

Results & discussion

• Characterization of carbon fibre were carried out using thermal analysis before growing CNT on them.• To improve the handling and processability of commercial fibres, it is usually coated with a size based on low Tg epoxy oligomer.

•But it inhibits CNT nucleation in CVD process, so fibres were examined for polymer sizing. The presence of epoxy resin(DGEBA) as sizing agent was found.• TGA was used to determine the weight% of the resin.•The PTCVD system was used to verify the effect of sizing on CNT growth and the quality, quantity of CNT growth was determined using SEM.•The growth parameters were adjusted to obtain long, well dispersed CNTs over the entire surface of carbon fibres.•It was observed that the presence of the epoxy sizing on carbon fibre does not hinder the growth of CNTs.

• This result is in contrast to other work in the literature, where the sizing needed to be removed for successful CNT growth.• The ability to grow CNTs without needing to remove the sizing reinforces the applicability of our growth processes and compatibilitywith current manufacturing methods as it avoids the deleterious effectsof using polymer solvents on the carbon fibre or needlessly subjecting the carbon fibre to high temperatures just to remove the sizing.

• The temperature of the substrate during the growth of CNTs were recorded by athermocouple, and it was at temp of 620-650°C. The growth temperature was about 750°Cin other studies which resulted in substantial degradation of fibre, compromising the mechanical properties.•The growth rate is about 6-20 times greater than that of studies carried out usingtradition thermal CVD systems.•The CNTs display no alignment , they are observed to bridge gaps between the carbon fibres improving electrical conductivity.

• Raman analysis was carried out on both the carbon fibre and the fuzzy fibre to confirm the presence of CNTs and analyze the quality and it reveals the quality of graphitization.• TGA was carried out on the fuzzy fibre sample. It was observed that the fuzzy fibre displays superior thermal stability(0-600°) before the complete decomposition of the sample, which is indicative of more graphitic(less defective) CNTs in this study.• Due to the presence of CNTs, the material as made a shift from being anisotropic to isotropic , allowing for a more efficient dispersal of electrons.

• Once infused into a composite, the enhancements in the adhesion between the fuzzy fibre and the epoxy resin is expected to offset the degradation to the carbon fibres(if any) resulting in a net improvement in the mechanicalproperties of the composites.

Conclusion

• The growth of CNTs on carbon fibres using a low temperature photo thermal chemical vapour deposition technique has successfully yielded fuzzy fibres.

• The growth is the least harmful to the mechanical properties of the carbon fibre than other studies & will improve the prospect of employing fuzzy fibres in industry.

• By :-T.R.Pozegic

I.Hammerton

S.R.P.Silva

W.Tang et al.

• Taken From :-CARBON 2014

• Special credits :-

Calvin & Hobbes

Research paper

So, thank you & enjoy !!