The effect of thin coating on the formation of the oxide-scale layer on FeCrAl metal fibers at elevated temperature

This study investigates the development and impact of thin coatings on the formation of a protective oxide-scale layer on FeCrAl metal fibers. The objective is to examine the effects of applying a thin coating layer using nano-oxide colloidal solutions on the oxidation rate and surface microstructure of 40 μm FeCrAl metal fibers. Two nano-oxide particles dispersed in water-based solutions were considered: (1) Aluminum hydroxide oxide (AlOOH) with nanoparticle sizes ranging from 10 to 45 nm, and (2) Zirconium oxide (ZrO₂) with nanoparticle sizes smaller than 100 nm. The samples' weight gain and oxidation rate were measured using Thermo-Gravimetric Analysis (TGA) during a 4-h isothermal heating process at 800 °C. Additionally, a Scanning Electron Microscope (SEM) was used to analyze the surface and cross-sectional micromorphology, while X-ray diffraction (XRD) was employed to examine the crystalline structure on the surface of the FeCrAl fiber. TGA results indicated that the thin-coated metal fibers effectively reduced the oxidation rate compared to the uncoated baseline fibers. Specifically, the thin-coated samples with AlOOH and ZrO₂ showed a 21 % and 42 % reduction in weight change after five isothermal heat treatment cycles, respectively, compared to the baseline metal fibers.