1.steel fiber
The use of low-carbon steel and low ultrasonic cutting method adopted to produce the oil content of the steel fibers, surfactants, good, cheap, so get in the semi-metallic friction material widely used in the base. Steel fiber most notable feature is a good thermal conductivity. Steel fiber with its high thermal conductivity so that the local surface heat rapidly spread to the interior, thereby reducing the friction surface temperature to avoid high surface temperatures to prevent heat resin matrix decomposition group which led to material wear and tear, extending the life of the product. But friction material made ​​of large steel fiber quality, easy to rust. After the clutch facings made ​​of this material corrosion cause adhesions, affecting shift separation and lead to the transmission of vibration and jitter [2]. Research shows that adding a certain amount of zinc oxide and calcium can enhance the anti-rust properties of the material, but no significant effect on the friction properties; steel fibers and mineral fibers and organic fibers mixed-use can further reduce the density of the material and improve brake noise . Currently, steel fiber reinforced friction material on the application of a variety of cars carried, reflecting better.

2.glass fibers
Glass fiber as a substitute fiber reinforced research time is longer, more stable product quality, greater production, the price is relatively cheap. Glass fibers are inorganic silicate fibers, thus better thermal stability. A surface treatment process has also been extensively studied, developed a variety of coupling, the affinity with the resin is good, and therefore the application to a certain reinforcing fiber friction material. According to foreign reports, the glass fiber reinforced friction material, good friction and wear properties [3], but more sensitive to glass fiber reinforced materials of the load, sliding speed and brake temperature solid hormone response. Under heavy load atrial tachycardia and high temperature, friction coefficient changed significantly, instability [4]. Glass fiber reinforced fiber friction materials used for certain requirements. Glass fiber should be more flexible, and potassium chloride containing 15-30% of glass fiber can Mohs strength is reduced to soften the glass fibers, E-glass fibers may be used that the [1]. Although glass fiber reinforced materials can be used in friction material, but fiberglass is inadequate. ① high hardness, wear and material than asbestos reinforced; ② when the temperature exceeds 800 ℃, easy to form glass beads, and glass beads Mohs hardness higher, the material will further increase the amount of wear; friction coefficient ③ glass fiber reinforced material with temperature a larger change in the coefficient of friction is unstable.

3. the carbon fibers
Carbon fiber has a high specific strength, high specific modulus, heat resistance, wear resistance, corrosion resistance and low coefficient of thermal expansion, and many other advantages. Carbon fiber reinforced matrix (C / C) composite friction materials have been widely used in the aerospace industry. Carbon fiber reinforced matrix composite material aircraft brake light weight, thermal shock resistance, friction coefficient stability, long life and other characteristics, is a new generation of aviation brake [9,10]. Currently, most of the international military and civilian aircraft mining trunk were reinforced composite brake matrix carbon fiber deputy. But as a general civil friction material also exist following obstacles; ① carbon / carbon composite material production process very complicated costs, higher raw material prices and limited production. ② conventional carbon fibers are generally long fibers, and the friction material applied to the reinforcing fibers is generally 2-5mm short fibers. This is currently difficult to achieve. ③ Carbon fibers are particularly the surface of the high modulus graphite fibers are inert, the resin wetting, adhesion is poor, so that the skin preparation of carbon fiber reinforced composite materials and shall be of the carbon fiber surface may be treated to increase the viscosity of carbon fiber and the resin between the attached strength. After the treatment the surface area of ​​the carbon fiber is not only increased, but also to generate a reactive group (such as carbonyl, carboxyl, and hydroxyl groups, etc.) on the surface, by these groups between the carbon fibers and the resin matrix to produce a chemical bond, thereby increasing the interfacial strength.

4.organic fibers
Aramid (Kevlar), polypropylene fibers, polyethylene fibers, polyester fibers and other combustible high point, thermal decomposition temperature is not obvious, and therefore can be used as the reinforcing fibers of the friction material. Organic fibers alone as a reinforcing fiber used generally have a surface treatment, typically to a natural or synthetic organic fibers in non-electrolytic treatment bath, the fiber surface coated with a thin layer of metal [1]. After the organic fiber surface treatment, both the advantages of metal fibers, such as thermal conductivity, wear; also has non-metallic fiber characteristics, such as low density, good toughness. For example, more commonly used aramid (Kevlar-49) is characterized by good toughness, high elastic modulus, low density, the price is only about a third of the carbon fiber, its downside is that it is made from a composite material compressive strength and flexural fatigue degree is not very good grip. Research shows that organic fibers can improve the stability of the material friction properties, significantly reducing the amount of wear, reducing brake noise also plays a significant role. But organic fiber in friction materials prices still exist, surface treatment, dispersing technology and other issues, pending further study.

5.mineral fibers
Mineral fibers drawn wide range and low prices, but also gradually attracted people's attention. Asbestos fibers are inexpensive to replace mineral fibers will be an important topic of friction materials research. Mineral fibers following shortcomings: ① general co-crystallization of water, high temperature brake easy to dehydration, material properties is not stable; unstable ② quality; product quality by larger origin, affecting the production time. If you choose to yield high grade mineral fiber, can achieve better results after adjustment friction material formulations.