Application of pyrolytic chromium-carbide coatings in friction units of machines

Abstract

Tribological aspects of the research on promising pyrolytic chromium-carbide coatings to improve the wear resistance of surfaces of heavy loaded units of transportation vehicles are presented in this article. The values of the friction coefficients of standard metal ceramic frictional MK-5 materials such as steel 65G and steel 40X with chromium-carbide coatings are obtained in the speed range from 2 to 6 m/s. Study is carried out in oil medium, which is used in the hydraulic transmissions of tractors. The results of measurement of the friction and wear of steel disks with and without coatings are compared, showing the advantages of the chromium-carbide coatings: the coated 40X steel with a surface roughness of R_a ~ 1.8–2.0 μm has a reduced wear by up to two orders of magnitude in comparison with a disk of steel 65G without coating. Testing of fullsize disks in a hydromechanical transmission in the real modes of slipping has shown that the application of disks with pyrolytic chromium-carbide coatings can increase the service life at least twofold.