Carbon fibre

The specialised use of the material in the world of competition, as well as the advance of the technology has resulted in carbon fire being more common in the automotive field.

Until a few years ago, this synthetic material was exclusively used in aeronautics and the world of top competition. Now, we can find this material anyway from supercars to everyday objects such as bicycles, watches, etc.

First, we must remember that carbon fibre is a synthetic fibre made up of filaments which measure from 5 to 10 µm in diameter. Each one of these is the union of thousands of carbon fibres manufactured from polyacrylonitrile.

The properties of carbon fibre are: 

·                     High mechanical strength (3 times greater than that of steel) with a high modulus of elasticity. 

·                     Low density in comparison with other materials: The density of carbon fibre is 1750 kg/m³, while that of steel is 7850 kg/m³.

·                     Resistance to external agents (corrosion, oxidation, etc.).

·                     High thermal insulation capacity.

·                     Resistance to temperature variations, it maintains its shape only if a thermostable matrix is used.

·                     It is a semiconductor.

·                     High price in comparison with other materials. Currently, a kg of carbon fibre is around €100, while the price per kg of steel is 2 to 5 € approximately.

·                     The main application is the manufacturer of composite materials with thermostable polymers such as epoxy resin, although it can be associated with others such as polyester or vinyl ester.

Carbon fibre in the automotive industry

The first time that carbon fibre was used in the automotive world was in 1980, when John Barnard, the McLaren Formula One designer, developed the use of carbon fibre (specifically CFRP: a carbon fibre reinforced polymer) for the McLaren MP4/1 monocoque, replacing the aluminium normally used at that time.

 In spite of a certain scepticism of the other teams at first, it did not take long to see the improvements that carbon fibre brought with respect to the other materials. This started the evolution of this material until today, Formula 1 vehicles are now made of 90% carbon fibre.

The improvements that result from the use of carbon fibre are essentially due to the lightness of this material. In the world of competition this lightness means a better CV/kg ratio, while this same lightness for commercial vehicle manufacturers means a reduction in consumption and lower CO2 emissions without having to invest in costly solutions for the engine.

Due to this and the reduction in its price over recent years, all car manufacturers are investing in carbon fibre with the aim of reducing its cost by 70% so it can replace aluminium and steel components.

Although the supercar makes such as Ferrari, McLaren, etc., have been using this material for some years, the first company to use carbon fibre reinforced polymer on a small car was BMW with the electric i3.

BMW uses a very strong carbon fibre body on an aluminium frame for the i3. This provides a weight reduction of up to 30% with the same strength as steel, the resulting mass of the vehicle is 1200 kg. If we compare this with a vehicle of similar characteristics, for example, the Renault Zoe, manufactured in traditional materials (its weight is 1430 kg), the BMW i3 is 200 kg lighter.

Other makes such as Ford plan to reduce the weight of their fleet by 340 kg on average, with the use of CFRP on some body components of their vehicles such as the bonnet, wings, boot lid. etc. 

In summary, all the makes are seeking a significant reduction in weight for the next generations of their vehicles, which will help meet the noxious gas emission limits with reduced consumption and for this, carbon fibre will be used.