The use of term «sintered powder frictional material»

Powder frictional materials are widely used in frictional couplings and brakes of tractors, automobiles and agricultural machinery. Today various terms are applied for these materials, such as: "ceramic-metal frictional material", "powder frictional material", "sintered frictional material". The term "ceramic-metal frictional material" is the most frequently used in scientific literature. Long-term experience of development and use of frictional materials indicates that the listed terms are not exact. There is the following definition of metal ceramics. It is the artificial material having heterogeneous composition of metals and alloys with nonmetals (ceramics). In modern sintered powder frictional materials the quantity of nonmetallic components could range from 10 to 30% of volume, including graphite, oxides, nitrides, sulfides and other components. For example, the volume of the most widespread composition of MK-5 sintered powder frictional material based on copper contains 23% of graphite that does not interact with the bronze base. According to earlier formulated definition of "ceramic-metal frictional material", the graphite should be qualified as ceramics, which is absolutely incorrect. When studying a microstructure of MK-5 sintered powder frictional material based on copper, it is established that graphite is uniformly distributed across the section surface. It does not interact with the components of frictional material and has the form of isolated particles. Therefore, it is incorrect to define this material as metal ceramics. For these materials it is suggested to use the term "sintered powder frictional materials" that indicates their application and production technology.

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