| Among the phosphate pigments, zinc phosphate found the widest application in paints, since it provides excellent corrosion resistance and is non-toxic. The two methods of preparation of zinc phosphate with the average crystallite size of 30-40 nm have been developed. Nanocrystalline zinc phosphate tetrahydrate was formed in the three-stage process: the synthesis of Zn3(PO4)2 · 4H2O from diammonium phosphate and zinc nitrate, low-temperature calcination of precipitated phosphate, and the hydration of the intermediate. Whereas the anhydrous zinc phosphate was obtained in the two-stage process of calcination (initially at low temperature, subsequently at higher temperature) of the gel formed as a result of treatment of aqueous solution containing Zn(NO3)2, (NH4)2HPO4, and citric acid. |
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