SURFACE-TREATED ARTICLE OF MAGNESIUM OR MAGNESIUM ALLOYS, METHOD OF SURFACE PREPARATION AND METHOD OF COATING

摘要

An article of magnesium or its alloy having a surface layer containing magnesium condensed phosphate and magnesium phosphate, which can be produced by treating an article of magnesium or its alloy with a treating liquid containing 1,000 to 20,000 ppm of alkaline metal ions, 1,000 to 50,000 ppm of condensed phosphate ions, and 100 to 20,000 ppm of borate ions, and having pH of at least 8. The treated article has good corrosion resistance, and a coating can be formed on the surface of the article with good adhesion.