1. Teckn weledge
An R&D Initiative
An insight on carbon fibre based materials
Carbon Fibres
in composites
A potential material for high
temperature applications!

2. 02 An R &D Initiative
The reduction in the specific unit consumption of refractories for a unit production of steel is traversing the path
of improvement in area of quality of refractories and moving towards more use of monolithic materials to
enhancerefractorylife.
As a result the manufacturers and researchers have laid a prominent focus in using carbon containing materials
in refractories. These materials have a valuable set of properties conducive to refractory operations which
include high temperature resistance, corrosion resistance to the melts produced during steelmaking and high
mechanical strength. These carbon-containing refractories are comprised of binders, oxides, graphite and
oxidation inhibitors in the form of metallic or metal-carbides powder. In the current refractory matrix carbon
exists in the form of fine and reactive pyrolytic carbon which comes from binders such as pitch or resin and as
graphiteflakes.
Carbon Fibres and steel industry :
However, since last few decades the scientists are on a quest
to explore new possibilities of increasing the thermo-
mechanical properties of ceramics including increase in
flexural strength so that they can withhold the stresses
developed when in use at high temperatures. One such step
in this direction is the production of composites by
reinforcement with carbon fibres in them. Carbon fibres are
few micron thick, light weight and very strong material with
an inherent characteristic of maintaining their structure and
thermo-mechanical properties under extreme conditions of
temperature and pressure. Interest in carbon fibres as
reinforcement materials for composites started with use in
structural applications, but in this article an insight would be
laid on using them for potential high temperature
applicationsinasteelindustry.
The Idea :
Whenthespace–vehiclesentertheearth’satmosphere,they
come under the influence of aerodynamic heating generated
on the surface of vehicle due to combination of compression
and surface friction of atmospheric gas. As a result, they have
a stringent requirement of using Thermal Protection Systems
(TPS).
The Thermal Protection Systems (TPS) comprises of various
materials suitable for application on the outer structural skin
ofthespacecrafttokeeptheexternalpanelwithinacceptable
temperatures upto 2000⁰C, mainly during the entry phase of
the mission. In addition, they can be repeatedly used for 100
missionswithslightrepairandrefurbishmentwork.
ThisThermalProtectionSystems(TPS)areafamilyofceramic
materials with extremely high melting temperatures and
good oxidation resistance required during re-entry
operations of a spacecraft, and possess good thermal shock
resistance.ThematerialscomprisingofTPSincludes:
1. Reinforced carbon-carbon which is used on the leading
edges of wings , nose cap and protects those areas
wheretemperaturesexceed1300⁰Cduringentry.
2. Black High-temperature Reusable Surface Insulation
(HRSI) tiles are used on the entire underside of the
vehicle where reinforced carbon-carbon is not used.
These insulation tiles protect areas where
temperatures are below 1300⁰C. The tiles have a black
surface coating required for entry emittance created
whileenteringtheearth’satmosphere.
Techscan - Carbon fibres in composites

3. Techscan - Carbon fibres in composites
03An R &D Initiative
Carbon-Carbon composites:
Carbon fibre reinforced carbon matrix composites, also
known as carbon–carbon (C/C) composites have densities in
the range 1.6 – 2.0 gm/cm3, which is much lower than those
of metals and ceramics used for widespread applications and
hence used for making components with lower weight, an
important parameter for aero-vehicles . Among many
important and useful properties of carbon–carbon
composites few prominent among them include their light
weight, high strength at temperatures around 3000⁰C in non-
oxidising atmospheres, low coefficient of thermal expansion,
high thermal conductivity (higher than that of copper and
silver), high thermal shock resistance and low degradation in
highpressureablationenvironments.
Carbon/carbon composites, developed about three decades
agoforthenovelneedsofa spaceprogramme,arenowadays
finding their use in high performance engineering materials
with potential employment in high temperature industries.In
area of extensive consumption, the main application of
carbon/carbon composites is in high performance braking
systems. New innovations in this field are indebted to
requirements from space industries but in general
engineering sectors, they are being used in engine
components, as refractory materials, as hot-pressed dies and
heating elements along with high temperature protection
Fig.1 Ceramiccompositesindifferentareasofaspaceshuttle
tubes. As the technology becomes more economically
viable, more and more application areas will get evolve.
Figure 2 shows the manufacturing process of carbon-carbon
composites.
Many companies around the globe are laying extensive
attention toward utilising the above mentioned properties
of carbon fibres in developing the C-C composite materials
on industrial scale suitable for high temperature
applications. Chevron Industries group’s Bluesteel and
3. Black tiles also called Fibrous Refractory Composite
Insulation(FRCI)weredevelopedtoreplacesomeofthe
HRSI tiles in selected areas of the spacecraft. The typical
TPSisshowninfigure1.
This Thermal Protection system(TPS) used in spacecraft
vehicles with varied materials under its umbrella compelled
to explore the possibilities of using carbon fibre based
products viable for iron and steel making operations. As a
result a detailed study is carried out on different carbon fibre
based products which are commercially available in the
currentmarket

4. Techscan - Carbon fibres in composites
04 An R &D Initiative
Fig. 3 Some of the flame resistant and heat blocking
material(Pyron)developbyZoltek
Fig. 4 Phenomenon behind good heat insulation by
materialdevelopedbyZoltek
The major drawback of using carbon-carbon composites in
high temperature applications is the degradation of
attractive thermo-mechanical properties at elevated
temperatures. Their potential applications in many
structural applications is restricted by inherent reactivity of
carbontowardsoxygenbeyond450⁰C.
ZoltekofTorayGrouparefewamongthem
Carbon - carbon
composites being lightweight
structures have zero thermal
expansion unlike ceramics
Carbon-fibre based
composites are brittle
with low impact
resistance

5. Techscan - Carbon fibres in composites
05An R &D Initiative
Ceramic Matrix Composites:
The Ceramic matrix composites (CMC) comprises of a fiber-
reinforced material - a silicon oxycarbide or silicon carbide
matrix. The bulk and surface properties are tuned through
fillers and fiber surface treatments to tailoring the
manufacturedengineeredmaterialtospecificapplications.
There are many organizations who have realised the
potential of CMCs and have setup big research centres to
venture into this more effectively. One among them is Lancer
systems. The picture shown in figure 5 will summarise the
manufacturing process of CMCs as adopted by Lancer
systems
Fig.5 ManufacturingprocessofCeramicMatrixComposites
Currently, many viable CMCs products based on carbon are
availableinthemarket.Theycanbesubdividedintotwotypes
basedonPolymertoCeramictechnologyas:
These types of products are manufactured by polymeric
route, producing stoichiometric silicon carbides and
1. SiliconCarbide–Polycarbosilanebased–
hence delivering the benefits of silicon carbide ceramic
compositeswithoutthesinteringandmachining
challenges.Themainhighlightsofsuchproductsare:
The precursor materials possess very high green
strength with curing temperatures as low as 200⁰C and
thus forming SiCs with nanoscale grain sizes. Complex
and near net shaped ceramic composite components
can be moulded from them. As the grains have nano
scale size these SiC ceramic matrix composites yield
tough parts which are lightweight, corrosion resistant
andtemperatureresistant.
Siliconoxycarbideresinsareusedasprecursormaterials
for these ceramic matrix matrix composites which are
designedtoofferatough,durableceramicformoderate
service temperatures. The ratio of Si-O-C can be
customised and thus giving a way for one of the most
cost effective ceramic formers in the market with
serviceupto1400⁰C.
Someofthehighlightsofthesetypeofproductsare:
They can be moulded to complex and near net shaped
ceramic matrix composites. The green curing of the
prepared products can be done in conventional presses
and moulds. As these products have configurable Si-O-C
in ceramic, they are lightweight, corrosion resistant and
hightemperatureresistant.
There are many other solutions which are available in
the field of ceramic matrix composites based on carbon.
Fewprominentamongthemare:
2. SiliconOxycarbide(SiOC)–Polysiloxanebased–

6. Techscan - Carbon fibres in composites
06 An R &D Initiative
Prospective applications in steel industry
By using the above mentioned products and combining their
properties, these products can find certain prospective
applicationsinasteelindustryasmentionedbelow:
• an insulating material for blast furnace tuyere by
replacingcopper.
• insulating refractory for burner zone applications in
indurationfurnacesandmills.
• inheatexchangesandplasmafusiondevices.
These Bulk Moulding compounds consist of fibre, carbon
resins and refractory materials. Some of the features of
thesecompoundsare:
They are easily mouldable through compression mould
tooling. They are medium modulus carbon fibre
reinforced products possessing high temperature
stability. These products are strong, ultra-light weight
systems with excellent performance in high temperature
applications and suitable for highly corrosive/high wear
environments.
Thermosetting polymers are a new family of
polysiloxanes called polyaramic resins and are inherently
flame resistant. The products can be either applied as a
coating or given a shape of composites with high
modulusandexcellentthermalshockresistance.
BulkMatrixCompounds-
ThermosettingPolymers–
One of the major advantage of this class is that they
have high temperature oxidation resistance and can
be used as inherent flame retardants in high
temperaturecompositesandflameresistantcoating.
Fig. 6 Flame resistant thermal barrier polymer

7. Techscan - Carbon fibres in composites
07An R &D Initiative
Challenges and hurdles
Several sources indicate that there are many barriers to the
use of carbon fibre based products in key application areas
whichinvolvehightemperatureenvironments.
Theprominentoneamongthemisthematerialcostofcarbon
fibre and high-rate composites manufacturing which hinders
the market growth for high volume applications. Current,
carbon fiber composites cost around 1.5 – 5.0 times steel’s
cost inhibiting high fiber-production for large volume
deployment; thus, there is a need to reduce precursor and
processing costs. Apart from these manufacturing
challenges, one of the main hurdle which is needed to be
overcome in case of carbon fibres based composite is their
application for high temperature applications involving
oxidative atmosphere instead of reducing atmosphere, as
carbon is prone to reaction with oxygen at temperature of
450⁰Candabove.
Looking ahead
The carbon-fibre based products have found widespread use
in non-oxidising environments with service temperatures
upto 3000⁰C, but their low oxidation resistance limits their
usage as an universal insulating material. As a result a focus
should be laid upon innovating novel oxidation protection
mechanisms so that they can serve all the desired purposes.
In addition the above mentioned bulk matrix compounds
can be used in composites to create a combination having
high temperature resistance properties at extreme
atmospheres.

8. Techscan - Carbon fibres in composites
References
1. E. Fitzer, Composites for high temperatures, Pure &
Appl.Chem.,60(1988),287-302.
2. A. Rodriguez, C. Snapp, Thermal Protection Systems,
EngineeringInnovations,182-199.
3. Advanced Composites Materials and their
Manufacture Technology Assessment, Composite
MaterialsandManufacture,2015.
4. Starfire Systems, Lancer systems, Zoltek and
Bluesteel.
5. I. D. Kashcheev, K. G. Zemlyanoi, S. A. Podkopaev, E.
V. Korsukov, L. A. Karpets, and I. V. Kormina, Use of
carbon fibres in refractory materials, Refractories
andindustrialceramics,50(2009),335-339.
6. G. R. Devi, K. R. Rao, Carbon-carbon composites –
an overview, Defence science journal, 43(1993),
369-383.
7. L.M. Manocha , S. Manocha, K.B. Patel, P. Glogar,
Oxidation behaviour of carbon/carbon composites
impregnated with silica and silicon oxycarbide,
Carbon,38(2000),1481-1491.
8. T. Gumula, A.Rudawski, J. Michalowski, S.
Blazewicz, Fatigue behaviour and oxidation
resistance of carbon/ceramic composites
reinforced with continuous carbon fibres, Ceramics
International,41(2015),7381-7386.
Research and Development
R & D, Tata Steel, Jamshedpur - 831007, India
Rel +91 657 6648911 Mobile +91 7033094770
email : ashish.chaudhary@tatasteel.com http://www.tatasteel.com
The author
Mr.AshishChaudhary
Mr. Ashish Chaudhary has completed his B.Tech in Ceramic Engineering from Indian Institute of
Technology (Banaras Hindu University), Varanasi in 2014. He joined Tata Steel in 2014 as
ManagementTrainee(Technical),SteelOperations.HeiscurrentlyworkingasManager,Refractories
Technology Group. His areas of interest are refractories for iron and steel making and working on
cuttingedgetechnologiesforhightemperatureapplications.