UNILAG JOURNAL OF MEDICINE, SCIENCE AND TECHNOLOGY

Abstract

Nickel-based superalloys are heat-resistant metallic materials used in aero- and land-based gas turbine engines hot sections. At high temperatures above 1000 °C, oxidation behaviour of gas turbine superalloy materials is characterized by the oxidation reaction rates and formation of stable and adherent oxide films on the materials’ surfaces. However, superalloy materials display varying oxidation behaviours due to compositional differences and environmental conditions. In this present investigation, the high temperature oxidation behaviour of Haynes 282 and Inconel 718 nickel-based superalloys were examined through experimental studyat both 1050 °C and 1100 °Ctest temperatures for maximum exposure periods of 10 hours (36000seconds). The morphological, microscopic,and elemental compositions of the formed-surface oxides were assessed usingOptical Light Microscopy, Scanning Electron Microscopy (SEM) and X-ray Energy Dispersive Spectroscopy (EDS). The parabolic oxidation rate constant, kp was calculated from the slope of the best-fit straight lines for the plots of bothsuperalloysexperimental weight gain data at both test temperatures. Asobservedkp = 3.9 x 10^-2(mg/cm².s) and 4.6 x 10^-2 (mg/cm². h) for Haynes 282; and kp = 1.4 x 10^-2 (mg/cm².s) and 4.4 (mg/cm².s) for Inconel 718 at 1050 and 1100 °C test temperatures respectively. Haynes 282 had an overall higher weight gain andkp than Inconel 718 under the same test conditions at both test temperatures as observed from the oxidation experiments.EDS results showedelemental presence of chromium and titaniumoxides for Haynes 282; and predominantly elemental presence of chromium oxide for Inconel 718