The Phase Composition and Structure of the Antifriction Copper-Based Composite and Their Influence on Tribological Properties 

Abstract

The article analyzes the distribution of doping elements and their influence on the phase composition, structure, and tribological properties of a new composite self-lubricating copper-based antifriction material doped with nickel, titanium, aluminum, and silicon, with the addition of CaF₂ solid lubricant for operation at elevated loads up to 2.0 MPa and high rotation speeds up to 10,000 rpm. The maps of chemical elements showed their uniform distribution in the structure of the material and did not reveal segregation phenomena. The homogeneous distribution of alloying elements throughout the volume promoted uniformly distributed strengthening phases in the material. These phases, together with the uniform distribution of the CaF₂ solid lubricant, contributed to an increase in tribological properties in severe friction conditions. High tribological properties of the material were due to the formation of a uniform antiseize film on the contact surfaces during operation, preventing the adhesion of surfaces and providing a constant self-lubrication mode. The experimental results showed that the new composite material, Cu–(4.0–6.0)% Ni–(1.0–1.5)% Ti–(7.0–10.0)% Al–(0.5–0.8)% Si–(5.0–8.0)% CaF₂, had higher antifriction characteristics than the well-known BrOTsC 6-6-3 cast bronze used in similar operating conditions. In operation of the cast bronze, high rotation speeds lead to the ejection of liquid oil by centrifugal forces from the contact area. As a result, the contact surfaces remain unprotected, which increases the friction coefficient and wear rate and leads to seizure of the working surfaces. The new material is effective in operation without oil lubrication at high rotation speeds and elevated loads through the formation of homogeneous antiseize friction films. Such films act as the lubricating, third component in the friction unit along with the composite material and the counterface. The developed antifriction copper-based composite material can be recommended for equipping friction units of high-speed web-offset roll printing machines.