| abstract |
The chromium-free treating composition for forming a chemical conversion coating on a surface of a magnesium and magnesium alloy material comprises 2 to 10% by weight of a phosphate compound, 0.5 to 3% by weight of a manganese ion compound, 0.1 to 1% by weight of a zirconium compound, By weight to 4% by weight, a vanadium compound in an amount of 0.05 to 1% by weight, and an extra water-soluble solvent. The above-described composition forms a uniform and dense chemical conversion coating film on the surface of magnesium or magnesium alloy material, and imparts corrosion resistance, top adhesion and water resistance to water, and does not cause surface defects in top coating. |