Techincal Note 9.0
Carbon Ceramic Brakes (CCB's) - Are They Worth The Price?
Figure 1: Development of carbon-based disc for automotive use:
Using carbon and ceramics in braking systems offers significant advantages over their iron counterparts, particularly with their light weight, superior heat resistance and longevity. However, the processes involved in their manufacture are considerably lengthy and much more expensive – why are they so expensive and is it worth the cost?
History
Carbon-based friction-resistant surfaces have been around for over 40 years – first seen in the heat-resistant carbon/ceramic-based materials for the undersides of NASA’s space shuttles, which were covered in silica ceramic tiles designed to resist the massive frictional heat generated when re-entering the atmosphere – and where the temperatures were at their highest; the use of Reinforced Carbon-Carbon (RCC) was used on the nose cone and leading wing edges.
The Concorde plane was the first instance of a braking application utilizing Carbon-Carbon (graphite reinforced carbon fibre) components in 1976, before F1 cars picked up on the technology and implemented their own systems by the end of that decade.
Besides being outrageously expensive ($CDN60,000 per pair), the original RCC’s performed poorly when wet, cold, were extremely brittle and degraded quickly (oxidized) under high temperature – making them unsuitable for general road use.
Figure 2: SiC Coating (Gen3):
This led to the development of more modern Carbon-Ceramic Brakes (CCB’s) in 2001, combining most of the benefits of RCC’s with the added durability provided by ceramics. The more recent introduction of silicon carbide (SiC) into the CCB matrix, as well as an additional SiC top-coating, increased the oxidisation and thermal shock resistance, making the brake discs last longer and better handle a wider range of temperatures and road conditions.
Figure 3: Carbon-Carbon "Heat Discs" on Airbus A340
Today, modern CCB’s are widely utilized in braking systems for commercial and military aircraft and locomotives – stopping vehicles weighing in the hundreds of tonnes in several seconds, time and time again.
MODERN CCB MANUFACTURING
While a traditional iron rotor takes about 30 minutes to manufacturer, a CCB disc (plus hat) takes over a month. The process involves a multi-step process where a carbon fibre and silicon resin mix are put into moulds and placed under 20,000kgs of pressure at 200C before being cooled, creating a plastic-like disc. This plastic-like disc is then refined (milled, drilled, sanded) and is then heated again over several days at 1,000C, before more silicon
powder is added and heated a third time to 2,000C for another 24 hours – this time under ultra-high vacuum to impregnate the silicon (now in a vapour state) throughout the carbon disc.
This process transforms the raw ingredients into the silicon-carbide ceramic disc that imputes durability and longevity.
FIGURE 4: CCB CASTING MOLD
The combination of these materials offers an extensive list of advantages over iron discs;
- Significant weight saving (70% less vs iron).
- Mass reduction typically 80-100lbs.
- This “unsprung” reduction has a dynamic affect equivalent to 320-400lbs.
- Much longer wear life (30x longer vs iron = life of the vehicle).
- Higher temperature tolerance (>1,000C vs 500C for iron).
- Increased stopping power (virtually no fade).
- No brake dust (98% of dust comes from iron wear).
Performance Brake Systems recommends three educational videos which explains the manufacturing process, as well as a comparison of Iron discs, CCB disc and Porsche’s new PSCB (Porsche Surface Coated (iron) Brakes):
What is Gen1 vs Gen2 vs Gen3 CCB discs?
The first generation of CCB’s (Gen1) where made exactly as described above, however the carbon fibres used in the manufacturing were made of short-stranded carbon fibres, about ~5mm in length. The resultant disc was susceptible to chipping or shattering, even with a small knock against a hard object – very common during the rotor installation process, as well as if the wheel hits a curb or a pot-hole. The Gen1 disc has the following appearance:
The second generation (Gen2) utilized long-stranded carbon fibres and additionally woven together, creating a much stronger matrix after processing. These long fibres and the weaving process adds additional equipment costs and significantly longer processing time. It should be noted that the general appearance of the Gen1 and Gen2 disc are similar, but on close examination, the woven fibres appear longer.
The third generation (Gen3) involves applying a pure Silicon Carbide (SiC) coating onto the wear surface (where pad meets disc) of the CCB disc. This is an additional manufacturing step requiring a high-temperature, vacuum deposition spray process, creating an 800um diamond-like SiC coating. This creates an incredibly hard, additional wear resistant coating on the CCB disc. The spider-like web cracking on the surface is normal and is indicative of a Gen3 disc. Below is the image of a Performance Brake Systems CCB.
IMPORTANT NOTE:
Performance Brake Systems CCB discs are Gen3. Our Hats are military-spec 7075-T6 aluminum and additionally FORGED to add maximum strength and lighter weight.
BEWARE of no-name, on-line brands in the range of $CDN5,000 – $CDN7,000 per pair, as these CCB’s are typically Gen1, with Hats made of CAST spec 6061-T6 aluminum Hats.
Do I need special pads and special calipers for CCB’s?
YES for pads, NO for calipers.
Gen1 CCB’s got a bad name early-on, as there were no special ceramic pads for CCB’s yet developed. The copper and/or steel fibres in the standard ceramic composite pads caused premature wear on the CCB surface. Consumers whom paid for a rotor that should last 10-years minimum (non-tracked) where showing significant wear after 2-years of normal use.
This is still an issue today, as many users are unaware that special pad materials are REQUIRED to use with CCB’s.
Performance Brake Systems (PBS) can recommend two (2) manufactures of specially formulated CCB pads: PAGID RSC Pads at $CDN1,400/pair and our own PBS brand at $CDN650/pair. The PBS pad is most equivalent to the PAGID RSC-1 formulation.
Below is a CCB Pad. Note the beige colour indicative of the ceramic CCB pad material:
Through innovation, expertise, and dedication to customer satisfaction, PBS is revolutionizing the high-performance braking industry, one rotor at a time.
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For more information or to find the right 2-piece floating iron rotors for your vehicle, contact our team of experts. We’re here to help you make the best choice for your braking needs.