The general powder metallurgy friction materials are composed of metal matrix, friction components and lubrication components. The main role of metal matrix is to keep ceramic components and lubricants in it by mechanical bonding, forming a whole with certain strength. The matrix is metallic. Its structure, physical and chemical properties largely determine the friction and wear properties, thermal stability, mechanical properties and thermal conductivity of powder metallurgy parts.
The matrix composition of powder metallurgy materials generally adds a certain amount of alloy elements Cu, W, Ni, P, Cr, Mo and Si to the iron matrix to improve the performance of the matrix. The alloy elements added together with Fe in the matrix form alloy pearlite, and form carbide phase or intermetallic compound phase, thus improving the high-temperature strength and oxidation resistance of the matrix, and greatly reducing the wear amount of materials.
Alloy elements such as Zn, Ni, Al, Ti, Mo and Sn are added to the matrix of copper based powder metallurgy brake materials. Friction components The friction components commonly used in friction materials are SiO2, Al2O3, SiC, B4C, etc. The main purpose of adding friction components is to improve the friction coefficient of the matrix material and enhance the strength of the matrix.
It is generally considered that it is appropriate to add SiO2 as friction agent in Cu based friction materials. SiO2 has a certain effect on improving the friction coefficient and reducing wear, but some studies have also shown that SiO2 reduces the content of iron carbide due to its reduction and dissolution in iron, thus reducing the friction properties.
Lubricating component In order to improve the scratch resistance and wear resistance of powder metallurgy materials, it is necessary to add lubricating component into the material composition. Graphite is one of the main components in powder metallurgy materials that plays a role in solid lubrication, and plays an important role in the wear resistance and brake stability of materials.