Structural Features and Properties of Antifriction Composites Produced from R6AM5 Steel Waste for Printing Equipment Parts.

The paper examines variation in the structure and properties of an antifriction composite produced from grinding waste of the R6AM5 high-speed steel with additives of CaF2 solid lubricant depending on the quantitative composition of the main components. The composite is intended to perform in friction units of offset and press cylinders of printing machines that operate in self-lubrication conditions at high rotation speeds (up to 5,000 rpm) and increased loads (up to 5 MPa) in air. The developed production modes allowed the R6AM5 steel grinding waste composite to be appropriately structured. The composite structure is a metal matrix in which CaF2 solid lubricant particles are evenly distributed. The composite's metal matrix consists of pearlite–carbide and carbonitride phases formed in the presence of R6AM5 steel doping elements. The appropriate amount of the CaF2 solid lubricant, which contributes to reaching the maximum antifriction properties, was determined by a series of experimental mechanical and tribotechnical tests and by fractographic analysis of the materials containing from 3.0 to 10.0 wt.% CaF2. The microstructural, fractographic, mechanical, and tribotechnical tests showed that content of the CaF2 solid lubricant that ensured high mechanical properties and significantly increased the antifriction characteristics of the composites varied from 4.0 to 8.0 wt.%. Electron microscopy studies of the friction surfaces of the R6AM5 + (4.0–8.0)% CaF2 composites confirmed the formation of uniform continuous protective antifriction films that completely covered the contact pair's friction surfaces and provided self-lubrication. Field tests showed the feasibility of using antifriction bushings made of the new composites produced from R6AM5 steel grinding waste and (4.0−8.0)% CaF2 in the friction units of offset and press cylinders of roll newspaper offset printing machines. The research identified prospects for expanding studies over a wide range of valuable metal waste for the development of new effective antifriction composites with a well-grounded content of components. This would also make another important contribution to protecting the environment against contamination. [ABSTRACT FROM AUTHOR]