Carbon-fibre reinforced stone - Technocarbon
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52 JEC Composites Magazine / No38 January - February 2008 Applications Carbon-fibre reinforced stone USERS’ PLATFORM ew people know that natural stone has the same specific weight as aluminium and is as pressure stable as construction steel - stonecutters have even been known to describe stone as being relatively flexible under certain conditions. German company TechnoCarbon Technologies (Munich) has utilized the above properties to allow compressing and preloading granite with the help of carbon fibres, to produce CarbonFibreStone (CFS), a highly durable method for stabilizing natural stone. The carbon-fibre reinforcement protects the stone against breakage, thus creating new mechanical properties. Highly pressure-stable natural stone, such as granite, is combined with extremely tension-stable carbon fibre that consists of nearly 100% pure carbon. The materials can be bound with highly stable epoxy resins, for example. The carbon-fibre/stone bond is adjusted by hardening the epoxy resins with a specific preload, resulting in a composite material with a combination of completely new and formerly unknown properties. This constitutes a technologically sound way to replace (at least to some extent) metals, that are CO 2 emission intensive. Technical description To develop its CarbonFibreStone, TechnoCarbon Technologies used patented technology to encapsulate the stone with carbon fibres, opening up the possibility to combine the following material properties: - extreme pressure stability comparable to that of steel, - extreme tensile strength, - high elasticity combined with unmatched dynamic damping characteristics, - high dimensional stability, - minimal coefficient of thermal expansion (1-3), - much lower specific weight than steel or iron (three times as low), - a specific weight that, depending on the type of stone, is the same as or lower than aluminium, - unlimited availability. The new material can be used to produce construction elements and bearing structures that are lightweight, elastic but pressure-stable, torsionally stable, and vibration-damping. They are also resistant to fatigue, chemicals, and corrosion. In other words, they are in many ways superior to traditional materials like steel. Another advantage is that CFS construction elements can easily be processed and handled using conventional stone-industry methods and instruments like drilling, sawing, screwing, or gluing. TechnoCarbon Technologies is interested in working together with industrial partners and scientific institutions, and is currently identifying partners for developing the multiplicity of potential technical applications. Natural stone slabs for kitchens Another aspect of CFS technology involves coating one side of normally treated natural stone with thin films of carbon-fibre matrix in order to stabilize the stone so thoroughly that it becomes “flexible” and unbreakable. This is achieved by preloading as a function of the specific application. These sheets are more stable, yet about three times lighter than massive natural-stone coverings 3 or 4 cm thick. The carbon-fibre material stabilizes the worktop up to temperatures of 120°C and even higher, depending on the application. The coefficient of expansion of carbon fibre is negative, which keeps the stone from breaking over Fibre-reinforced natural stone has been used for a long time for kitchen worktops, elevator carpeting or elegant bathrooms. TechnoCarbon Technologies has now developed a composite made of carbon fibre and stone that can be used in many more applications. The new material gives natural stone a new relevance as an environment-friendly material. F XXXXXXXXX, CCCCCCCCCCCCCCC, TechnoCarbon Technologies Bulthaup kitchen top, 10-mm "Angola Blue" is covered with a CFS layer JCM38_Users 21/12/07 15:40 Page 4
Transcript of Carbon-fibre reinforced stone - Technocarbon
52 JEC Composites Magazine / No38 January - February 2008
Applications
Carbon-fibre reinforced stone
USERS’ PLATFORM
ew people know that natural stonehas the same specific weight asaluminium and is as pressure stable
as construction steel - stonecutters haveeven been known to describe stone asbeing relatively flexible under certainconditions. German companyTechnoCarbon Technologies (Munich) hasutilized the above properties to allowcompressing and preloading granite withthe help of carbon fibres, to produceCarbonFibreStone (CFS), a highly durablemethod for stabilizing natural stone.
The carbon-fibre reinforcement protectsthe stone against breakage, thus creatingnew mechanical properties. Highlypressure-stable natural stone, such asgranite, is combined with extremelytension-stable carbon fibre that consists ofnearly 100% pure carbon. The materialscan be bound with highly stable epoxyresins, for example. The carbon-fibre/stonebond is adjusted by hardening the epoxyresins with a specific preload, resulting ina composite material with a combinationof completely new and formerly unknownproperties. This constitutes atechnologically sound way to replace (atleast to some extent) metals, that are CO2
emission intensive.
Technical descriptionTo develop its CarbonFibreStone,TechnoCarbon Technologies used patentedtechnology to encapsulate the stone withcarbon fibres, opening up the possibility tocombine the following material properties: - extreme pressure stability comparableto that of steel,
- extreme tensile strength,- high elasticity combined with unmatcheddynamic damping characteristics,
- high dimensional stability,- minimal coefficient of thermal expansion(1-3),
- much lower specific weight than steel oriron (three times as low),
- a specific weight that, depending on thetype of stone, is the same as or lower thanaluminium,
- unlimited availability.
The new material can be used to produceconstruction elements and bearingstructures that are lightweight, elastic butpressure-stable, torsionally stable, andvibration-damping. They are also resistantto fatigue, chemicals, and corrosion. Inother words, they are in many wayssuperior to traditional materials like steel.Another advantage is that CFS constructionelements can easily be processed andhandled using conventional stone-industrymethods and instruments like drilling,sawing, screwing, or gluing.TechnoCarbon Technologies is interested inworking together with industrial partnersand scientific institutions, and is currently
identifying partners for developing themultiplicity of potential technicalapplications.
Natural stone slabs forkitchens Another aspect of CFS technologyinvolves coating one side of normallytreated natural stone with thin films ofcarbon-fibre matrix in order to stabilizethe stone so thoroughly that it becomes“flexible” and unbreakable. This isachieved by preloading as a function ofthe specific application. These sheets aremore stable, yet about three times lighterthan massive natural-stone coverings 3 or4 cm thick. The carbon-fibre materialstabilizes the worktop up to temperaturesof 120°C and even higher, depending onthe application. The coefficient ofexpansion of carbon fibre is negative,which keeps the stone from breaking over
Fibre-reinforced natural stone has been used for a long time for kitchenworktops, elevator carpeting or elegant bathrooms. TechnoCarbon Technologieshas now developed a composite made of carbon fibre and stone that can be usedin many more applications. The new material gives natural stone a newrelevance as an environment-friendly material.
F
XXXXXXXXX,
CCCCCCCCCCCCCCC,
TechnoCarbon Technologies
Bulthaup kitchen top, 10-mm "Angola Blue"is covered with a CFS layer
JCM38_Users 21/12/07 15:40 Page 4
a wide range of temperatures (-40°C to +120°C). The dilatation of the stone canalso be forced to zero if necessary.
Developing a ski with a heartof stoneSwiss company Zai AG worked withTechnoCarbonTechnologies to developthe Spada, the first ski ever made usingnatural stone. The new ski waspresented to the market at Munich’sInternational “ISPO 2007” trade fair forsports equipment and fashion. Thecomposite material used consists ofnatural granitic gneiss from the SwissAlps coated with a carbon-fibrelaminate. Bonding these two ideallycomplementary materials togethercreates new mechanical ¬andengineering properties. The projectturned into an exemplary demonstration
of the flexibility of CFS. Because the natural stone used for theSpada ski has a lower specific weightthan aluminium, and because of CFS’ssuperior vibration-damping properties,the ski has incomparable handlingproperties. This means safer carving athigher speeds, simply because "theflutter" is better absorbed than withother materials. CFS opens up a newdimension in ski design, because itworks with the other materials used tobetter distribute the absorbed vibrations.
Wide-ranging futureapplicationsBy committing to the potential of CFS,manufacturers will soon come up with newideas for applications. CFS beams couldrevolutionize architecture and bridge-building, and it could replace steel
reinforcements or, even better, reinforcedconcrete. Earthquake-resistantarchitecture or lightweight collapse-resistant hall roofs could be designedwithout having to resort to expensivevibration-compensating techniques. Evena top producer of photovoltaic equipmenthas shown interest, seeing the possibilityfor replacing aluminium and steel with amaterial that poses fewer problems.
In car bodies, the material could providesignificant weight savings combined withhigher crashworthiness. In boat-building,it could provide higher torsional stabilitywith greater resistance to breakage. Inmachine construction, where vibrationbehaviour is often hard to control, CFScomponents could offer lightweight buthighly stable and low-vibrationconstructions that are fatigue resistant.Applying CFS to wind-turbine rotorblades or airfoils is another possibility,here again due to the uniquecombination of properties such as highstrength, vibration damping and fatigueresistance with elasticity and low weight.
And finally, CFS technology meetsenvironmental requirements, which areclose to its designer’s heart. It can beused to manufacture raw materials thatcan be machined in an environment-friendly way with the possibility forrecovery, and which consume much lessenergy than the production of steel,aluminium and concrete. �
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Fig.2: The Spada stone ski, named for the Rhaeto-Romanic word for "sword"
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