Corrosion under oil films, with special reference to the cause and prevention of the after-corrosion of firearms

Abstract

Chemical-etched surface texturing is of great potential for processing technologies involving solid/liquid wetting due to its simplicity, efficiency, and applicability. In this study, the wetting behaviors of 4043 aluminum alloys on different 301L stainless steels in the as-received and two chemical-etched textured states were investigated by the modified sessile drop method. The wetting process at 650–750 °C under high vacuum was dynamically captured by a digital camera. The spreading mechanism was revealed by combining the identification of precursor films and interfacial microstructures with the analysis of spreading dynamics. During the wetting process, the movement of the triple line relied mainly on the mechanism of subcutaneous infiltrate. Chemical-etched texturing achieved changes in roughness by adjusting the ratio of ridges and pits on the surface. As the etching time extended, the spreading activation energy decreased, the interfacial reactivity enhanced, and stronger capillary forces were induced by the rough surface of the substrate and IMCs, thereby leading to droplets spreading at a faster rate. The wettability was extremely improved with a maximum increase of more than 50% in spreading radius. The elucidation of the mechanism behind the effect of chemical-etched surface texturing on Al/stainless steel wetting can provide some guidance for brazing, welding, coating, and many other fields, and serve as a reference for the wetting research on other reactive systems.