Mitsuo Niinomi1, Yukinao Suzuki2 and Yoshisada Ueda3
1Toyohashi University of Technology, Toyohashi
Commercial pure iron, S45C, Fe-Cr, Fe-Si and Fe-C alloys were dipped into molten aluminum (99.8%) mostly at 1073 K and rotated at various speeds for various times. Then the alloy layer formed on each alloy was examined and the dissolution process of these alloys was studied. The thickness of the alloy layers became thinner with increasing rotating speed. With regard to the composition of the alloy layers, Fe2Al5 occupied the major portion in the same manner as under the static condition. The shape of the alloy layers formed on commercial pure iron, Fe-Cr and Fe-Si alloys changed from tounge-like to band-like as the rotating speed increased. For Fe-C alloy, the alloy layer is band-like at every rotating speed.
The dissolution rate of each alloy layer increased as the rotating speed increased. As under the static condition, the dissolution resistance against molten aluminum is the highest in Fe-C alloy and is the lowest in Fe-Si alloy. The dissolution process of commercial pure iron, S45C, Fe-Cr and Fe-Si alloys is controlled by the diffusion of Fe in molten aluminum. Moreover, in commercial pure iron. Fe-Cr and Fe-Si alloys, the dissolution is accelerated by natural convection and flaking of the alloy layer at lower rotating speed, while accelerated by flaking of the alloy layer and mechanical errosion by molten aluminum or by turblent flow near the rugged surface of alloys at higher rotating speed. The dissolution of Fe-C alloy, however, probably be controlled by the chemical reaction or mass transfer in the alloy layer and the diffusion of Fe in molten aluminum.
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