Friction materials are widely used in brakes, clutches and friction transmission devices of various vehicles (such as cars, trains, airplanes, ships, etc.). ) and all kinds of machinery and equipment. In the braking device, the kinetic energy of rotation is converted into heat energy and other forms of energy by using the friction characteristics of friction materials, thus braking the transmission device.

Modern automobile friction material is a kind of composite material with friction as its main function and structural performance requirements. When working, it mainly bears the repeatedly changing mechanical stress field and thermal stress field, and the source of force and heat is the friction interface that infinitely forms a new working face. Friction materials for automobiles are mainly brake friction plates and clutch plates. They are both a safe part and a fragile part. These two products are not widely used in automobiles, but they occupy a particularly important position in automobile compartment materials, and the research and development of asbestos-free low-noise friction materials is a high-tech involving many disciplines. Before the mid-1970s; Automobile brake systems are mostly four-wheel drum type, almost all brake friction plates are asbestos-based friction materials, and only those super-heavy vehicles are gold-based friction materials. Asbestos-based friction materials are strong carcinogens due to their large thermal decay. From the mid-1970s to the mid-1980s, the structure of automobile brakes began to transition to "front disc and rear drum" and non-asbestos friction materials. Since1mid-1980s; This is the second application period of disc brakes and new asbestos-free friction materials.

Based on the increasingly high requirements of environmental protection and safety in modern society, developed countries in the world automobile industry have rapidly developed asbestos-free friction materials, and successively introduced asbestos-free semi-metal friction materials, sintered metal friction materials, alternative fiber reinforced or polymer bonded friction materials, composite fiber friction materials, ceramic fiber friction materials and so on. Their similarities are as follows:

1) has no asbestos component, but uses alternative fibers or polymers as reinforcing materials;

2) adding metal components to improve the use humidity and service life;

3) Add various additives or fillers to improve the friction smoothness and adhesion resistance, and reduce the braking noise and vibration.