Development history of friction materials

Friction materials can be roughly divided into the following stages:

(1) Before 1930, asbestos long fibers were mainly added with other thread weaving impregnation methods.

(2) In 1930, a flexible resin adhesive was developed, which has good thermal stability, making it possible to mix more fillers in the dry process, and developed drum brake pads. In the following 30 years, asbestos raw materials still dominate.

(3) In 1950, the American SKELLMAN Company took the lead in developing friction materials with iron powder, graphite and other fillers and resins as adhesives for hot pressing, that is, semi-metallic friction materials. In 1970, semi-metallic friction materials were used in disc brakes and are still widely used today.

(4) Since 1960, due to the continuous improvement of automobile technology, the requirements for brake friction performance are getting higher and higher. Asbestos friction materials can no longer meet the development requirements of automobiles, especially the environmental pollution and human health problems caused by asbestos. Many developed country automobile companies have begun to study and seek substitutes for asbestos materials, such as composite fiber friction materials. These new friction materials have good friction and wear properties and meet the needs of the development of the times. Since 1980, disc brakes and new friction brake linings have been rapidly developed and applied to automobile braking systems on a large scale. People pay more attention to the comfort, environmental protection, safety, and lightweight of automobiles. The friction material industry has to speed up The development of new materials improves the braking performance of brake materials. In addition, researchers in the mid-1970s proposed that non-asbestos materials have some shortcomings. For example, the steel fibers of semi-metallic friction materials are easy to rust and cause certain damage to the brake disc; friction heat causes the brake sealing ring to soften and brake fluid "Air resistance phenomenon". Fiber-reinforced friction materials and composite fiber friction materials also have a series of problems, such as poor glass fiber wettability and complex manufacturing processes. The cost of composite fiber friction materials is high, and the preparation process should be improved to solve this problem. The subsequent second and third generation semi-metallic friction materials have the advantages of low thermal conductivity and low noise.