Corrosion Characteristics of the Sulfuric Acid Anodized Film Formed on Al6070 Alloy in Nitric Acid Vapor Environment

Abstract

The corrosion properties of anodized films on aluminium 6070 alloy in a sulfuric acid have been studied. Comparison to evaluate the anodized A6070 and pure 6070 specimen, corrosion tests in HNO 3 vapor environment of the 20 wt.% were performed up to 72 hours. Characteristics of film formation and surface morphology were examined by optical microscopy, FE-SEM, and EDS. The oxide film anodized in the sulfuric acid solution contained 5 to 10 wt.% of sulfur. In the initial stages of corrosion, anodized specimens exhibited corrosion resistance than the pure specimen. However, the corrosion conditions in 24 hours, corrosion was far more anodized specimen than pure specimen. Therefore, anodized films contained sulfur, nitric acid vapor in the environment is thought to stimulate corrosion.

Plasma Corrosion in Oxalic Acid Anodized Coatings Depending on Tartaric Acid Content

“…Sulfuric acid (H 2 SO 4 ) electrolytes are often used in industries because of their economical advantage, and many studies have reported optimal conditions using sulfuric acid anodized coatings [2][3][4][5]. However, when sulfuric acid electrolytes are used, sulfuric acid ions remain in the oxide film, creating a film with low purity that is more susceptible to corrosion [6]. For this reason, anodizing processes using organic acids have been actively researched.…”