Abstract
Machine parts made of nickel-based alloys usually work in high-temperature service environments such as aircraft turbines. The mechanical properties and antioxidant properties of materials tend to be reduced at high temperatures. Therefore, it is of great practical significance to reveal the wear mechanisms of materials at different temperatures. In the present investigation, the tribological behaviour of an Inconel 718 superalloy at different temperatures was investigated. First, the coefficient of friction curves obtained under different test conditions were analysed in detail to illustrate the dynamic change process of friction at high temperature. Next, the morphology of the wear surface, surface morphology of friction pairs and material transfer during friction were analysed via scanning electron microscopy 3D morphology and energy dispersive spectroscopy measurements to reveal the wear mechanisms of materials in a high-temperature environment. Finally, the microstructure of the cross section of the wear tracks was analysed by using optical microscopy electron back-scattered diffraction etc., to clarify the mechanisms of crack initiation and material removal. The results show that the friction properties of the Inconel 718 superalloy have differences at different test temperatures. Although increasing the test temperature does not necessarily aggravate the wear of the material, the oxidation of the wear surface during the friction process significantly increases. In addition, when the contact load increases, the thickness of the oxide layer and wear of the material simultaneously increase.
Highlights
High-temperature alloys are materials with excellent strength, creep resistance and fatigue resistance at working temperatures above 600°C (Reed, 2008)
These authors found that the tensile strength at room temperature and 650°C slowly decreased and the stress rupture life remarkably decreased with increasing thermal exposure time
In the high-temperature friction test, the coefficient of friction (COF) curve during the test was recorded in real time
Summary
High-temperature alloys are materials with excellent strength, creep resistance and fatigue resistance at working temperatures above 600°C (Reed, 2008). Many researchers have investigated the mechanical properties of nickel-based superalloys, e.g., the influence of high temperature on the microstructure of materials (Lu et al, 2013; Deng et al, 2015; An et al, 2019; Gao et al, 2019). Other researchers have studied the fatigue and mechanical properties of superalloys from the viewpoint of high-temperature creep (Lund and Nix, 1976; Yeh et al, 2011; Chen et al, 2016; Long et al, 2019). This approach can effectively reveal the wear mechanism of materials in different temperature
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