LAUSR

In the framework of the anticorrosive pigment research without heavy metals like zinc or chromium, a new lamellar phosphate pigment, namely zirconium orthophosphate Zr(HPO4)2·H2O, was prepared by a simple precipitation route and dispersed in an organic resin coating at 5 wt.%. After characterization by electronic microscopy, X-ray diffraction and thermogravimetry, its use as a corrosion inhibitor pigment was investigated in 0.5 M NaCl corrosive media on steel and zinc. Electrochemical impedance spectroscopy measurements show that the delamination ratio of the ZrP-loaded organic coating is considerably reduced with immersion time, even though ZrP addition lowers the bulk coating resistivity. In comparison with classical aluminium triphosphate pigments, these particular high performances are related to the specific structure and physicochemical properties of ZrP materials. On the one hand, the acidity character of ZrP due to proton lability allows the control of the pH at the metal/coating interface. On the other hand, the progressive dissolution of ZrP pigments induces the formation of insoluble protective metallic phosphates and ZrO2 on zinc and steel substrates, as revealed by solution analysis (ICP-MS). Graphical abstract Graphical abstract