Corrosion resistant films were prepared on Mg–4Al–1Ca (ACa41) alloy by steam coating, spin coating, or steam coating followed by spin coating. The chemical and corrosion resistant properties of the films were characterized by using SEM, XRD, FT-IR, and electrochemical methods. XRD patterns revealed that the film prepared by steam coating was composed of crystal Mg(OH)₂ and Mg–Al layered double hydroxide (LDH). FT-IR spectra showed the presence of Si–O, C–H, Mg–O, and Al–O bonds in the film prepared by steam coating followed by spin coating, resulting in the formation of silane/Mg(OH)₂ composite film. Potentiodynamic polarization curves of the film prepared by the two steps coating showed high corrosion resistance, and the corrosion current density of the composite film decreased considerably compared to those of the bare ACa41, the film prepared by steam coating or spin coating.

When circular tubes are laterally compressed using a rigid plate, they collapse. Therefore, it is difficult to form tubes with one or more flat faces from circular tubes by lateral compression. To prevent such collapse, which is the cause of poor fitting to dies, the possibility of incremental flattening of 5052 half hard aluminum circular tubes was experimentally examined. The results indicate that no collapse was induced for circular tubes and that the forming of a flat surface on the side of circular tubes by incremental flattening is possible. Following first-path incremental flattening, the tube was rotated by 90° and second-path incremental flattening was carried out. No collapse was induced. The surface obtained after the second-path incremental flattening was also flat, indicating that partially square tubes can be formed. These findings indicate the possibility of small-lot production of various tubes shaped by multipath incremental flattening without collapse.