Friction Mechanism Features of the Nickel-Based Composite Antifriction Materials at High Temperatures

Adam Kurzawa,Miroslaw Bocian,Tetiana Roik,Iuliia Vitsiuk,Pawel Zajac,Oleg Gavrysh,Krzysztof Jamroziak,Dariusz Pyka

doi:10.3390/coatings10050454

Adam Kurzawa, Miroslaw Bocian + Show 6 more

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https://doi.org/10.3390/coatings10050454

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Abstract

The friction behavior of the formed antifriction films and their effect on the functional properties of the composite based on the powder nickel alloy EI929 with solid lubricant CaF2 at high temperatures was investigated. An antifriction film was formed on the contact surfaces during the friction process. Such a film was the result of the interaction of the contact surfaces with atmospheric oxygen at high temperatures. It contains oxides of alloying elements from materials of the frictional contact and solid lubricant calcium fluoride. The quantitative ratio of formed oxides depends on the temperature operating conditions of material. The data of thermodynamic simulation of the high-temperature interaction of the composite with oxygen coincide with the experimental data obtained by studying the fine structure of surface antifriction films. Antifriction films consist of oxide phases in combination with solid CaF2 lubricant. Anti-friction films provide high wear resistance of the self-lubricating composite in the range of temperatures 1073–1173 K due to the balance between the rate of their formation and wear. When the temperature exceeds 1200 K, the film loses its lubricating properties and acts as an abrasive substance due to the intense oxidation. Abrasive surfaces of materials were subjected also to microscopic examination, in which the mechanically mixed layer (MML) was described. The study of the friction surface roughness parameters confirmed the presence of the formed friction self-lubricating film and allowed to determine its parameters. The friction mechanism was the formation of an oxide layer combined with a solid lubricant, which provides high antifriction properties in the range of 1073–1273 K.

Highlights

The high temperatures exceeding 800 K are inherent in the operation of gas turbine equipment, where many units operate under the influence of high temperatures, and increased pressures in the oxidizing environment
The analysis showed an increase in the number of oxide phases formed on the friction surface
The material science approach was used to describe the structural features of the friction films formation, their composition, the distribution of chemical elements inside them, and their influence on the functional properties of high-temperature nickel composites

Summary

Introduction

The high temperatures exceeding 800 K are inherent in the operation of gas turbine equipment, where many units operate under the influence of high temperatures, and increased pressures in the oxidizing environment (atmospheric air). This fully applies to friction units operating in such conditions. The use of cast nickel alloys as antifriction materials is ineffective due to their low wear resistance, and liquid lubricants cannot be used due to high operating temperatures. The properties of the base material and additives effect on the composition of the secondary structures formed during friction process This is especially important when the material operates at high temperatures exceeding 800 K

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