High temperature oxidation of chromium with nanometric ceria sol–gel coating

Isothermal oxidation behavior of chromium with and without nanometric sol–gel CeO₂ coating is studied at 1000 °C in air. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to examine the surface morphology and microstructure of their oxide films. It is found that ceria coating greatly improves the anti-oxidation property of chromium. Laser Raman spectrometer and X-ray diffraction spectrometer (XRD) are also used to study the stress level in oxide films formed on ceria-coated and ceria-free Cr. The difference in oxidation behavior is mainly attributed to the fact that ceria greatly reduces the growth speed and grain size of Cr₂O₃ film, and this fine grain-sized Cr₂O₃ film probably has better high temperature plasticity, i.e. oxide film can relieve parts of compressive stress by means of creeping. XRD and Raman testing results both show the stress declination due to nano-CeO₂ application, and their deviation is analyzed concerning to the rare earth effect.