Structure and properties of new bearing composites based on steel waste for severe operating conditions of printing machines

The article presents the research results on the structure and properties of new self-lubricating bearing composites based on grinding wastes of high-alloyed steel 8X4V2MFS2 with additives of CaF2 solid lubricant. The new composites are designed to operate in friction units of printing machines at rotational speeds of 600˗800 rpm and increased loads of up to 3.0 MPa. It is shown that the application of the developed technology ensures the formation of a fine-grained heterophase structure of the new composite. The formed structure is a metal matrix base made of regenerated grinding waste from 8X4V2MFS2 steel, consisting of a high-alloy α-solid solution and solid grains of alloying elements’ carbides, as well as a uniformly distributed solid lubricant CaF2. This structure ensured the formation of the new composite’s physical, mechanical and tribological properties high level. In the process of friction, antifriction films were formed on the contact surfaces, which provided a self-lubricating mode. Comparative friction and wear tests have shown significant advantages of the new waste composite compared to cast brass L63, which is traditionally used in friction units of printing equipment. The determined level of physical, mechanical, and tribological characteristics makes it possible to recommend the studied material for use in friction units of printing equipment operating at elevated rotational speeds of 600˗800 rpm and loads up to 3.0 MPa in air. The studies have shown the prospects of using a wide range of valuable metal grinding waste in the repeated production cycle for the manufacture of high-quality composites. The reuse of such waste will make a significant contribution to the protection of the environment from pollution associated with human industrial activity and will help reduce its negative effect on the ecosystem. Keywords: grinding waste, high-alloyed steel, technology, composite bearing, microstructure, solid lubricant, properties, antifriction films, printing machines.