Composition of Friction Material Formulations（三）
3. Filling
The filler in the friction material component is mainly composed of friction performance regulator and compounding agent. The purpose of using fillers mainly includes the following aspects:
(1) Adjust and improve the friction performance, physical properties and mechanical strength of the product.
(2) Control the coefficient of thermal expansion, thermal conductivity, and shrinkage of the product to increase the stability of the product size.
(3) Improve the brake noise of the product.
(4) Improve the manufacturing process performance and processing performance of the product.
(5) Improve the appearance quality and density of the product.
(6) Reduce production costs.
In the formula design of friction materials, the selection of fillers must understand the performance of fillers and the role they play in various characteristics of friction materials. The correct use of fillers determines the performance of friction materials and is also very important in the manufacturing process.
According to the function of the friction performance regulator in the friction material, it can be divided into two types: "friction-increasing filler" and "friction-reducing filler". The friction material itself is a friction material, which requires a high friction coefficient in order to perform braking and transmission functions, so the friction-increasing filler is the main component of the friction performance modifier. The friction increasing effect of different fillers is different.
The Mohs hardness of the friction-increasing filler is usually 3-9. The friction-increasing effect of high hardness is obvious. Fillers with a hardness above 5.5 are hard fillers, but their dosage and particle size should be controlled. (such as alumina, zircon, etc.)
Anti-friction filler: Generally, it is a low-hardness substance, a mineral with a hardness lower than 2 on the Mohs scale. Such as: graphite, molybdenum disulfide, talcum powder, mica, etc. It can not only reduce the coefficient of friction but also reduce the wear of the mating material, thereby increasing the service life of the friction material.
Friction material is a special material that works in a hot and high-pressure environment, so it is required that the filler components used must have good heat resistance, that is, thermal stability, including thermophysical effects and thermochemical effects.
The packing density of the filler has a great influence on the performance of the friction material. The different performance requirements of the friction material also have different requirements for the packing density of the filler.
