Braking Every Day? Have You Ever Experienced the Power of Ceramic Brake Pads?
Brake materials have evolved through several stages: from asbestos materials, semi-metallic materials, powder metallurgy materials, to carbon/carbon composites and carbon-ceramic composites. Powder metallurgy brake materials have drawbacks such as a tendency to bond at high temperatures, susceptibility to friction performance degradation, a significant decline in high-temperature strength, poor thermal shock resistance, and short service life. On the other hand, C/C brake materials face issues like low static and wet friction coefficients (with wet friction coefficient dropping by about 50% compared to dry conditions), large thermal mass, poor oxidation resistance, long production cycles, and high production costs, all of which limit their further development and application.
Carbon-ceramic brake materials emerged in the 1990s as a multiphase composite braking material. They use high-strength carbon fibers as reinforcement and materials like pyrolytic carbon and silicon carbide (SiC) as the matrix. Essentially built upon C/C composite brake materials, they incorporate hard SiC ceramic materials—known for their excellent oxidation resistance—into the matrix. Hence, they are also referred to as ceramic brake pads. These materials retain the advantages of C/C composites (low density, high-temperature resistance) while overcoming their shortcomings (low static friction coefficient, significant wet friction decay, insufficient friction lifespan, and poor environmental adaptability), establishing them as a new generation of brake material.
The Origin of Carbon-Ceramic Brake Pads
Carbon-ceramic braking technology originally came from the aviation industry. In 1969, the Concorde supersonic airliner, jointly developed by Aérospatiale (France) and the British Aircraft Corporation, made its maiden flight. This aircraft was exceptionally fast, completing the journey from London to New York in under three hours and setting records for the fastest commercial flight. Such performance required powerful acceleration, with an average takeoff speed of 400 km/h and a similar approach speed. To stop a 185-ton airliner traveling at these immense speeds, a robust, high-temperature-resistant braking system was essential. Dunlop was tasked with developing the world's first aviation carbon-ceramic braking system for the Concorde, capable of bringing it to a halt from 305 km/h within 1600 meters.
While carbon-ceramic technology proved successful in aviation, disc brake systems for cars were just beginning to gain popularity in passenger vehicles at the time, making the expensive carbon-ceramic option impractical. Fast forward to 1976, automotive design legend Gordon Murray was struggling to reduce the weight of the Brabham Formula 1 team's cars. He experimented with using carbon-ceramic material for brake calipers, as carbon-ceramic discs weighed roughly half as much as their steel counterparts. Successfully adapting them for F1 could significantly enhance vehicle performance.
After some effort, he contacted Hitco, a materials company. They managed to produce one-piece carbon-ceramic brake discs, mounted to the wheels using aluminum bells. This led to the first-ever carbon-ceramic braking system for cars being fitted to the Brabham team's new F1 car, the BT45, for that season. Although the car's overall results weren't stellar, it didn't stop carbon-ceramic brakes from gradually being adopted by other teams, eventually becoming the standard material throughout F1. For a long time afterwards, carbon-ceramic brakes remained primarily in the realm of race cars. Their absence from production vehicles was not only due to the exorbitant cost but also perhaps because the extreme performance they offered wasn't deemed necessary for road cars. This changed in 1997 when two component manufacturers began researching carbon-ceramic technology for civilian use: SGL, a world-leading carbon products manufacturer, and the well-known Brembo.
The year after the project started, in 1999, SGL and Porsche unveiled the world's first production-ready carbon-ceramic brake disc at the Frankfurt Motor Show. By 2000, it was fitted to Porsche's latest high-performance model, the 996 Turbo. In 2002, Brembo had a mass-producible product ready. They partnered with Ferrari, equipping their first carbon-ceramic brakes onto the Ferrari Enzo. Considering the Enzo was a hypercar named after the company's founder, its adoption of Brembo's new product was a strong testament to the braking system's performance capabilities. Even after over two decades of use in production vehicles, the cost of carbon-ceramic brakes remains high due to their complex manufacturing process. Consequently, they are primarily found on a limited number of high-performance cars today. However, with the rise of electric vehicles and continuous advancements in carbon-ceramic technology and cost control, these brake pads are beginning to make their mark in the EV segment. In 2022, Tesla began offering a new carbon-ceramic brake system for its Model S Plaid. This system includes components like carbon-ceramic brake discs, calipers, brake pads, aluminum (or alloy steel) bells, and fastening bolts, with a complete set for all four wheels. Tesla's pioneering move to commercially adopt carbon-ceramic brakes has led some to believe it will spearhead an upgrade in braking technology for electric vehicles.
Advantages and Disadvantages of Putting Carbon-Ceramic on Vehicles
Some describe carbon-ceramic brake pads as a new braking material "propelled" by electric vehicles—not in the sense of being "hyped up," but rather riding the wave of EV popularity.
If we were still in the era of traditional fuel-powered cars, even after another 10 or 20 years, carbon-ceramic pads might still be considered "luxury items." However, the electric vehicle age presents two key advantages that seem to smooth the path for ceramic brake pads adoption.
First is the lightweighting advantage. In the gasoline vehicle era, studies by the European Automobile Manufacturers' Association indicated that for every 100 kg reduction in vehicle mass, fuel consumption per 100 km could drop by about 0.4 L, and CO2 emissions could decrease by roughly 1 kg. Thus, lightweighting effectively reduces carbon footprint. Compared to fuel vehicles, electric vehicles lack an engine and transmission but gain a heavy battery pack, making them heavier overall. Therefore, lightweighting is even more critical for the development of energy-efficient and electric vehicles.
Carbon-ceramic brakes significantly reduce the weight of unsprung components, making them a better fit for electric vehicles and helping alleviate range anxiety. A traditional cast iron disc might weigh over 10 kg, whereas a carbon-ceramic disc weighs only about 6 kg. This represents roughly a 50% weight reduction, meaning four brake discs can save around 20 kg. The effect of reducing unsprung mass is roughly five times greater than reducing sprung mass. It's like the difference between carrying a weight on your back versus strapping it to your feet while walking—the feeling of burden is entirely different. Therefore, the 20 kg reduction from carbon-ceramic discs can have an effect comparable to reducing the vehicle's body weight by 100 kg, potentially increasing the driving range by tens of kilometers.
Furthermore, a major advantage—and key selling point—of electric vehicles compared to fuel vehicles is their significantly enhanced acceleration. Nowadays, many electric vehicles can easily achieve 0-100 km/h times in the 4-second range, approaching supercar territory. But the ability to go fast must be matched by the ability to stop effectively, so electric vehicles have increasingly high demands on braking performance. Ceramic brake pads meet these demands more effectively. In practical use, braking is the process where friction converts kinetic energy into heat energy. If the brake system's heat cannot be dissipated quickly enough, braking effectiveness suffers. When bringing a vehicle weighing over a ton to a complete stop from speeds exceeding 100 km/h, the braking system must convert immense kinetic energy into heat.
Under such conditions, ordinary brake discs are prone to overheating and thermal fade during hard braking, significantly reducing braking performance. Ceramic brake discs, however, exhibit excellent resistance to thermal fade, with heat resistance many times greater than that of standard discs. Moreover, ceramic discs generate maximum braking force right from the initial application, resulting in faster overall braking and shorter stopping distances compared to traditional systems.
Of course, the disadvantages of ceramic brake pads are also quite clear, primarily their high cost. This stems from factors like complex manufacturing processes, production difficulty, and long cycle times. Leading overseas manufacturers of carbon-ceramic brake discs primarily supply high-end sports car producers, and their product prices are very high. For example, Brembo, a major player, sells individual carbon-ceramic discs for over €15,000. Therefore, the exorbitant price remains the main reason ceramic brake pads haven't become commonplace in ordinary vehicles.
Huge Market Potential and Significant Opportunities for New Market Entrants
Initially, barriers such as complex processes, production difficulty, and long cycle times kept the cost of carbon-ceramic brake pads high. Before Tesla's commercial application, these systems were mainly used in aerospace and high-speed rail, with their presence in the automotive sector limited to race cars and high-end models like Porsches, Bentleys, Bugattis, and Lamborghinis. With the rapid growth of the global electric vehicle industry, along with economies of scale, technological upgrades, improved automation, and lower carbon fiber prices, costs are expected to drop significantly in the coming years, potentially boosting the penetration rate of carbon-ceramic discs. According to forecasts by relevant institutions, the global market size could reach into the billions by 2030. This could represent a brand-new market; once breakthroughs are made, safety could become a key selling point, potentially accelerating development faster than anticipated.
Furthermore, this industry represents a developing market with substantial room for new competitors. Due to the aforementioned barriers, relatively few companies globally can mass-produce carbon-ceramic discs. Major suppliers of carbon-ceramic composite brake discs include Italy's Brembo, UK's Surface Transforms Plc, and US-based companies like Fusion Brakes. There are relatively few enterprises worldwide mastering the preparation technology for high-performance carbon/ceramic composite brake discs, leaving significant space for new alternatives. As technology in this field continues to advance globally, and with the ongoing trend towards "enhanced features, high-end configurations, and intelligent systems" in electric vehicles, the adoption rate of carbon-ceramic discs in the global EV market is expected to rise steadily.