Carbon Ceramic rotors are widely known to be the brake rotors of choice for the street-fairing super-car and hyper-car. It’s fairly easy to see why considering the rotors have significantly lower weight than traditional iron rotors (up to 70%) and virtually no brake fade.
The history of carbon ceramic rotors begins in aerospace. Carbon-Carbon composites (or carbon-fibre reinforced carbon matrix composites) were initially developed to be used as heat shields on spacecraft. The technology was later adapted to other applications because of its success.
Engineers saw the benefits of lightweight, high-friction, high-performance Carbon-Carbon composites in brake applications and therefore adapted the material for that purpose. It was used on the Concord in the 1970s and from there the technology was later adapted for automotive racing in Formula 1. By 1979, the race team Brabham F1 had successfully adapted the technology to Formula 1 racing and thereby ushered in a new form of high-powered braking.
However, there was a drawback to Carbon-Carbon rotor systems when being considered for street use. Apart from being incredibly expensive, carbon-carbon brakes don’t work when cold or wet and therefore cannot be used on the road safely. The carbon matrix also oxidizes at high temperatures which essentially means that the lifetime you can expect from these brakes are relatively short. This isn’t an issue for Formula 1 races since teams would typically run through a few rotors in a season. However, it does become an issue with street cars since no one would like to switch rotors every season!
Due to the technology’s high-costs and short lifetimes, it was rather inconvenient for commercialization. Over the span of a few decades, extensive research was conducted to figure out ways of extending the lifetime of carbon-reinforced rotors and making the technology more affordable.
The solution was to replace the carbon-matrix with a non-oxidizing ceramic while using carbon fibre for structural integrity. This is where Silicon-Carbide (the ‘ceramic’) comes into play. Engineers were able to increase the oxidization resistance and the thermal shock resistance of the final product by using Silicon Carbide as the matrix material. The rotors now had a longer lifetime, withstood a larger temperature range, and handled more drastic temperature changes. This made carbon ceramic brake rotors useful, and economically feasible, for automotive and rail applications.
Initial Carbon-Ceramic rotors (carbon-fibre reinforced silicon-carbide matrix) in automotive applications were constructed in one of two ways. The first method was to use ceramic material with chopped carbon fibre and an additional ceramic layer on the friction surface. The second was to use ceramic material with chopped carbon fibre and no outer friction layer
In 2001, the chopped fibre technology was used in the first commercialized Carbon Ceramic disc brake system made available to the public on the Porsche GT2. This system was a big leap in commercial braking technology for the automotive sector and ushered in a new era of the ‘super-brake’.
With the advances in vehicle power and chassis technology, even these brakes were being put to the test and consistently purchasing a new set of carbon-ceramic brake rotors (chopped fibre) made the rotors unreasonable for extended race usage.
Enter Surface Transforms and their patented continuous fibre, high conductivity, ceramic technology. Established in 1992, Surface Transforms began developing an automotive carbon ceramic brake in 2004 utilizing continuous carbon fibre instead of chopped carbon fibre. This means that the reinforcing carbon fibres in the ceramic matrix were now much longer than chopped fibre rotors and offer many benefits over chopped-fibre carbon ceramic rotors.
The continuous fibre construction offers:
- Refurbishing capabilities thanks to the homogenous (uniform) material structure. This allows the rotor to be refurbished (resurfaced) up to three times, significantly extending its lifetime.
- Higher thermal conductivity (heat transfer) which leads to lower operating temperatures and improved fade resistance.
- Higher strength (mechanical) contributes to longer lifetime and increased durability.
- Reduced cost of ownership through refurbishment and increased lifetime. With the ability to refurbish the product and with the product’s inherent longevity, costs of ownership are significantly reduced.
Continuous fibre carbon ceramic can easily be considered the future of advanced braking technology for the high-powered car and the technology of choice for the hyper-car.