Abstract
Commercial pure iron, Fe-Cr, Fe-Si and Fe-C alloys were dipped into molten Al-Si alloy baths (JIS AC4C and ADC12) at 800°C and rotated at various speeds for varying length of time. Study of alloy layer formation and the corrosion behavior was made and the results were compared with the results obtained in the static molten Al-Si alloys, static molten pure Al and dynamic molten pure Al baths. The thickness of the alloy layers was almost constant independent of the rotating speed and the dipping time. The major portion of the alloy layer was occupied with FeAl3. The amount of Fe2Al5 was less than that in the case of the static Al-Si alloy baths. The dissolution rate of each alloy increased as the rotating speed increased. As in the static molten Al-Si alloys, as well as static and dynamic molten pure Al baths, the corrosion resistance against molten Al was highest in Fe-C alloy and lowest in Fe-Si alloy. The dissolution process of the commercial pure iron, Fe-Cr, and Fe-Si alloys appears to be controlled by the diffusion of Fe in molten Al. At high rotating speed, the dissolution appears to be further accelerated by mechanical erosion with molten Al, while at low speed, it is accelerated by natural convection. However, the dissolution of Fe-C alloy is presumably retarded by mass transfer or chemical reaction resistance in the alloy layer.
