The first materials used by humans for vehicle braking are natural materials such as wood and leather.
Due to the low speed at that time, the temperature generated by the brakes was also very low. Until 1897, the British first invented a brake drum similar to today, and developed a brake belt made of hair or cotton as the main material. Asphalt soaked. This material was used not only for the carriage at the time but also for the early motor vehicles.
Natural fibers such as cotton will become carbon at 270 ° C and lose its friction properties and strength, thus limiting the application.
In 1908, a wound asbestos friction lining was developed. Asbestos friction materials have been the main material for brake pads until the late 1960s. Roughly divided, the development of brake pad friction materials has gone through the following stages:
Before 1930, the main method was to use asbestos long fiber and other wire types (such as brass wire). The impregnating material evolved from bitumen to a mixture of oil and glue and began to replace long fibers with short fibers. In the later stage, there was a process of mixing dry hot pressing without preparation. In 1930, chemists developed a flexible resin binder with better thermal stability. This makes the dry process possible with more fillers and gradually develops the drum brakes we are familiar with today.
Asbestos has been the main raw material for the next 30 years. At the same time, the research results of the rubber industry have also promoted the improvement of the friction material process. The coating preparation is brushed with a rubber mixture glue, and then folded or stacked for hot pressing, which is still widely used today.
In 1950, SKWELLMAN of the United States first developed a friction material made of iron powder, graphite and other fillers and resin as a binder, which is called a semi-metallic friction material.
In 1970, this material was used in disc brake pads and is still widely accepted today. A large number of semi-metal brake pads still occupy markets around the world.
Since 1960, with the continuous improvement of automobile design, the requirements for brakes have become higher and higher, forcing many friction materials companies to study the relationship between friction materials and brake drums/discs, and to seek alternative materials for asbestos. After analysis, people realize that the application of asbestos is subject to many restrictions. Asbestos resources are limited, and the quality of asbestos varies greatly, especially asbestos has a greater impact on human health and the environment.
The existence of these problems has promoted the process of replacing asbestos with glass fiber, mineral fiber and metal fiber. Recently, more and more aramid fiber, potassium titanate whisker and synthetic fiber have been used.
Now the automaker's requirements for brake pads are: overcome the shortcomings of semi-metallic brake pads; reduce thermal conductivity; reduce thermal expansion; develop new materials that maintain friction characteristics over a wider temperature range; Reduce the wear of the dual; develop friction materials suitable for aluminum brake discs.
In recent years, the success of Japanese ceramic friction materials has promoted the rapid development of friction materials. Brake pads using ceramic materials have basically solved the main shortcomings such as heat conduction, thermal expansion and wound disc, and can maintain friction characteristics in a wider temperature range.
Today, more and more automakers and aftermarkets are starting to be used in large numbers, and the market share is rapidly increasing.