Sodium zinc phosphate as a corrosion inhibitive pigment

摘要

A sodium zinc phosphate pigment synthesized using a co-precipitation method and characterized by X-ray diffraction was investigated for its corrosion inhibition activity in comparison with the commercial zinc phosphate using EIS in a 3.5% NaCl solution. A mild steel surface analysis after exposure to the test solutions was conducted using scanning electron microscope-energy dispersive X-ray and infrared spectroscopies. The results indicate that the corrosion inhibitive performance of the synthesized pigment is higher than that of the commercial zinc phosphate. This can be the result of the synthesized pigment's relatively high solubility, which affects the precipitation of a phosphate layer onto the mild steel surface and the modification of the crystalline structure of the corrosion products in the presence of the inhibitive pigment. The salt spray and wet pull-off tensile strength results revealed an improved corrosion protection of the coatings formulated with SZP.