Friction films analysis and tribological properties of composite antifriction self-lubricating material based on nickel alloy

This article analyzes the composition and distribution of chemical elements in friction films and their effect on the tribological properties of the self-lubricating, high-temperature antifriction composite based on EP975 powder nickel alloy with CaF₂ solid lubricant. Analysis of the chemical elements by energy-dispersive spectroscopy (EDS) showed their uniform distribution, on both the composite’s surface and the counterface’s surface. The alloying elements’ uniform distribution leads to a uniform distribution of the corresponding phases and structural elements in the antifriction film. This ensures high tribological properties at high temperatures. Analysis of the material’s tribological properties, by means of metallographic and micro-X-ray research confirmed the correctness of the technology for producing the composite. Solid lubricant CaF₂, alloying elements, and their corresponding phases form the continuous antiscoring film. The film influences the antifriction properties formation during the friction process and provides a self-lubricating mode under the action of high temperature and oxygen. Antiscoring, self-lubricating CaF₂ films minimize wear of the friction pairs and defend the contact surfaces against intensive wear. The dense antifriction films have smooth microtopography, which stabilizes the high-temperature friction unit operation. Thus, the self-lubrication mode is realized for a long exploitation time. Tribological properties analysis allowed us to determine the ranges of rational exploitation modes for the material being studied: a load up to 5.0 MPa, a slide speed from 0.3 to 1.0 m/s, a temperature up to 800°C, in the air. The results obtained opened the opportunity to control the antifriction film formation and the composite’s tribological properties by the choice of the initial ingredients while taking into account the operating conditions.