O’zbekistоn respublikasi оliy va o’rta maxsus ta`lim vazirligi

fatigue wear. In the process of repeated frictional deformation, fatigue of the material occurs in the surface layers, fatigue microcracks are formed in them, the development of which leads to microchipping. material. The processes of frictional-contact fatigue develop in a zone commensurate with the zone of mutual introduction of microroughnesses of the interacting surfaces. When rolling with slippage (operating conditions of rollers, rollers, teeth of chain sprockets and gears, etc.), fatigue microwear can be accompanied by "pitting" - fatigue macro-chipping of individual sections of the surface of materials based on polymers.
According to the molecular-mechanical theory of friction of solids, the minimum fatigue wear is realized with the elastic nature of the contact; the intensity of fatigue wear during plastic deformation of microroughnesses is several orders of magnitude higher. This ratio is also preserved for materials based on polymers.
abrasive wear. Under a certain combination of friction loading conditions and the geometry of the mating surfaces, the stress-strain state reaches limit values that exceed the strength characteristics at the corresponding local points of the interacting materials. Frictional destruction of materials occurs due to single impacts of the indenter. The most characteristic manifestation of abrasive wear is microcutting.
Abrasive wear of polymers is accompanied by tribochemical processes initiated mainly by destruction.
Erosive wear. This type of surface destruction of materials occurs in the process of high-speed flow around the product of a liquid and gas, including high-temperature, medium (ablation phenomenon), usually containing abrasive particles in the form of sand, combustion products, etc.
Erosion wear is observed during the operation of water pumps, underwater parts of ships, smoke exhauster blades, etc.
In general, the nature and intensity of wear of materials based on polymers are determined by the following main factors:

1. 
   The nature of the materials;
   
2. 
   Surface and bulk mechanical, physical and chemical properties of friction-interacting bodies;
   
3. 
   Loading parameters (value and law of load change, movement speed, presence of vibrations);
   
4. 
   Macro- and microgeometry (shape, waviness and roughness) of contacting surfaces;
   
5. 
   Friction temperature and environmental parameters (temperature, atmospheric effect, the presence of lubricants and chemically active reagents, irradiation, vacuum, etc.).
   

Much experience has been accumulated in the field of friction and wear of polymer-based materials. But, unfortunately, we have to state once again that the lack of unified methods makes it difficult to compare and generalize the results of scientific work and engineering evaluations of materials, which leads to large losses of time and money.
Due to the specifics of the structure, polymeric materials exhibit characteristic features in the process of frictional interaction, which must be taken into account in the methods and designs of tribometers, when choosing the main factors and assigning research modes, as well as when creating a unified international tribometric system.