Heat resisting property of Al coated steel sheet by sputtering

Al coated steel sheets are being used for heat resisting application such as muffler for automobile, fuel tank, microwave oven, and combustion chamber parts. These are commercially produced by hot-dip galvanizing process and their heat resisting properties are depending on their processes. In this study, Al coated steel sheets are fabricated by sputtering process in order to compare their properties with the ones of galvanizing.Hot-dip Al coated steel sheet (HACSS) showed a typical solidified structure of Al–Si alloy; primary Al dendrite and Al–Si eutectic structure. Intermetallic compounds were found between the coating layer and the steel substrate. On the other hand, sputtered Al coated steel sheet (SACSS) represented a well-mixed structure of Al–Si. No intermetallics were observed. Heat resistance tests were carried out at 450 °C and 500 °C. HACSS was discolored at 450 °C, but SACSS at 500 °C. In this study, heat resistance experimental results are analyzed and discussed based on their microstructures of non-ferrous/ferrous metal hybrid system.

► We produced sputtered Al coated steel sheets (SACSS).
► SACSS are compared with hot-dip Al coated steel sheets (HACSS).
► Intermetallic compound is formed in HACSS, but not in SACSS when these are fabricated.
► SACSS has better heat resistance than HACSS due to the intermetallic compound.
► Decrease of Si in SACSS with Al–Si coating layer suppresses the diffusion of Fe.