Formation Process and Properties of Phytic Acid Conversion Coatings on Magnesium

• 作者: Jian-Rui Liu Wei-Dong Huang Yi-Na Guo
• 来源期刊: 表面工程材料与先进技术期刊(英文)
• 学科: 工学
• 关键词: MAGNESIUM CHEMICAL CONVERSION COATINGS Phytic ACID FORMATION Mechanism
• 年，卷（期）: 2011,（1）
• 页码范围: 15-21
• 页数: 7页
• 分类号: TG17

摘要

A chromium-free conversion coating treatment for magnesium by phytic acid solution was studied. The formation process of phytic acid conversion coating was studied through measuring the open circuit potential (OCP) and weight change of the pure magnesium in the different conversion treatment time. The morphologies and compositions of the coatings were determined by SEM and EDS respectively. The conversion coating has the multideck structure with netlike morphology which is similar to the chromate conversion coating, and is mainly composed of Mg, P, O and C. The contents of C and P and the size of the cracks in different layers decrease from the external layer to the inner layer. The hydroxyl groups and phosphate carboxyl groups in the coating which have the similar properties to organic paintcoat are beneficial to the combination of substrate and organic paintcoat. The formation mechanism and thickness variation of the conversion coatings are also discussed.