Investigation On Corrosion Of Aluminum Alloy And Copper By Using Difference Viewer Imaging Technique

A novel technique for in situ corrosion research called Difference Viewer Imaging Technique (DVIT) was used to investigate the localized corrosion of aluminum alloys and copper for the first time in this thesis. It is an in situ, non-invasive technique displaying only the changes of morphology and color and their locations on materials surface in various environments, which is beyond the capability of the nowaday common in-situ imaging techniques. DVIT is a powerful technique for dynamic corrosion imaging, by continuously recording sequential, in situ optical images of the materials surface, and showing the differences between images through digital subtraction and multiplying the differences.AA7075 aluminum alloy has been applied in numerous fields such as aircrafts, automobiles and architectures because of its high strength and good electronic properties. However, in many environments it is susceptible to localized corrosion such as pitting and intergranular attack. The surface layer behavior of AA7075 aluminum alloy in chloride solutions is of great interest. But it is difficult to directly observe the morphology and color changes taking place on surface during open circuit immersion in chloride solutions. In this work, we observed one special kind of localized corrosion on abraded AA7075-T6 aluminum alloy surface in chloride solutions, and we named it as"Streaking Corrosion"for the first time. The corrosion behaviors of streaking corrosion and its elimination methods were systemically investigated. Here is the summary of this work:...