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

The paper analyzes the distribution of doping elements and their influence on the phase composition, structure, and tribological properties of a new self-lubricating copper-based antifriction composite doped with nickel, titanium, aluminum, and silicon, with additions of the CaF₂ solid lubricant. The composite is intended 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 that they were uniformly distributed over the composite and there were no segregation phenomena. The homogeneous distribution of doping elements throughout the volume promoted strengthening phases that were uniformly distributed in the composite. These phases, together with the CaF₂ solid lubricant distributed uniformly, increased the tribological properties in severe friction conditions. The composite’s high tribological properties were due to a uniform antiseize film that developed on the contact surfaces in operation, preventing the adhesion of surfaces and providing constant self-lubrication. The experimental results indicated that the new composite, 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 greater antifriction characteristics than the well-known BrOTsS6-6-3 cast bronze used in the same operating conditions. In operation of the cast bronze, high rotation speeds lead to the ejection of the liquid lubricant by centrifugal forces from the contact area. The contact surfaces thus remain unprotected, which increases the friction coefficient and wear rate and leads to seizure of the contact surfaces. Homogeneous antiseize friction films make the new composite effective in operation without liquid lubrication at high rotation speeds and elevated loads. Such films act as a third, lubricating component in the friction unit along with the composite and the counterface. The antifriction copper-based composite can be recommended for friction units of high-speed web offset printing machines.