C/C composite brake material

The friction materials used in brakes are usually called brake materials, such as automobile brake materials, train brake materials and aviation brake materials. Brake pads have been used for more than 100 years as a key component of automotive braking systems.

The basic performance requirements of high-performance brake pad materials are: ① Appropriate friction coefficient, the friction coefficient of the brake pad must be moderate, if the friction coefficient is lower than 0.35, the safe braking distance will be exceeded or even brake failure when braking, if the friction coefficient is higher than 0.40 , The brake is easy to lock suddenly, and there will be a rollover accident; ②Reliable stability, when the car is running at high speed or emergency braking, it will generate instantaneous high temperature. Under high temperature, the friction coefficient of the brake pad will decrease, and this kind of brake pad will resist thermal recession. The quality of performance determines the safety of car braking; ③ Reasonable life, normal driving vehicle, the life of the front brake pads is 30,000km, and the life of the rear brake pads is 80,000km; ④ Satisfactory comfort, comfort is friction The direct manifestation of performance, including braking feeling, noise, dust, odor, etc., modern brake materials mainly include the following four categories: resin-based brake materials (asbestos-free brake materials, asbestos-free brake materials, paper-based brake materials), powder metallurgy brake materials , C/C composite brake materials and ceramic-based brake materials. Among them, C/C composite brake materials and ceramic-based brake materials are the focus of current research in the field of brake materials. The C/C composite brake material is a high-performance brake material obtained by repeated densification and carbonization process with carbon fiber (or carbon cloth) as the matrix. Under high temperature conditions, because of its light weight (about 1/5 of iron), high energy load, strong high temperature resistance and long service life, it was first used in aircraft brake pads. The existing problems are: ① The price of carbon fiber is relatively high , the manufacturing process is complicated, resulting in high cost; ② the friction factor changes greatly, which is easy to cause the temperature rise of adjacent components to be too high; ③ the manufacturing cycle is long, 2~3 months. The above issues need to be resolved. Generally speaking, ceramic-based brake materials mainly refer to non-metal-based ceramic brake materials. Ceramic-based brake materials combine the high temperature sintering of powder metallurgy brake materials and the low density and high temperature resistance of C/C composite brake materials. Disadvantages of high temperature oxidation of /C composite brake materials. With the help of some powder metallurgy processes, brake materials with excellent comprehensive properties such as low density, high temperature resistance, oxidation resistance, and long life are obtained. The typical C/C-SiC ceramic brake materials are gradually used in high-speed trains, heavy-duty automobile tanks, etc. Application under extreme conditions. At present, the preparation processes of C/C-SiC materials include slurry impregnation hot pressing method, chemical vapor infiltration method, polymer impregnation pyrolysis method (PIP), liquid phase silicon impregnation method (LSI) and warm pressing-in situ reaction method. Xiao Peng et al. took the lead in studying the braking test of carbon fiber reinforced C/C-SiC materials to simulate trains, and found that the material has a high friction coefficient, a dynamic friction coefficient of 0.3 to 0.39, low braking noise, no sparks, and strong oxidation and corrosion resistance.