Steam-induced changes in surface characteristics and corrosion resistance of spark-anodized titanium

• Main Authors: Chen, Zhaoxiang, Zhou, Kun, Li, Zhong
• Other Authors: School of Materials Science & Engineering
• Format: Article
• Language: English
• Published: 2015
• Online Access: https://hdl.handle.net/10356/80891; http://hdl.handle.net/10220/38540
• Institution: Nanyang Technological University

Titanium was spark-anodized in 1 M phosphoric acid solution. Surface characteristics and corrosion resistance of spark-anodized titanium were investigated before and after the steam exposure at 180 °C. It was found that spark-anodizing of titanium produced a layer of poorly crystallized TiO2 film with the incorporation of phosphate anions. The oxide film exhibited a porous microstructure with many craters and micro-projections on the surface. After the steam exposure for 48 h, the crystallinity of anodic TiO2 increased greatly. The original dense and smooth micro-projection surface became very loose and rough, and fine Ti(OH)PO4 crystals formed and congregated there. A phase transition mechanism has been proposed based on the experimental observations. The corrosion behavior investigation has shown that the steam exposure could reduce the corrosion resistance of spark-anodized titanium greatly.