High temperature oxidation of low carbon steel with and without an Al coating in an atmosphere containing burning ethanol

High temperature oxidation of low carbon steel (SAPH440) with and without a hot-dip Al coating in an atmosphere containing burning ethanol, water vapor, and air were studied by isothermal oxidation at 600 °C, 650 °C, 700 °C, and 750 °C over 49 h. The experimental results show that the water vapor and hydrogen produced by ethanol burning in the atmosphere promotes an increase in weight gain and metal loss in the bare steel. The growth of the iron oxide layer is attributed to large amounts of hydrogen dissolved in the iron oxide layer leading to fast oxidation kinetics. The protective Al₂O₃ layer formed on the surface of aluminide steel can serve as a barrier to hydrogen penetration in the aluminide layer; thus, the oxidation rate of bare steel was significantly slower in the atmosphere containing both water vapor and hydrogen.