Thermal Decomposition Kinetic and Electrochemical Properties of KZn2(PO4)(HPO4)

Abstract

Thermal decomposition kinetic reaction parameters of KZn2(PO4)(HPO4) was investigated by non-isothermal measurement used in a multivariate non-linear regression analysis. The anticorrosive performance of the phosphate extracts in different pH 3.5% NaCl was studied by polarization and open circuit potential measurements. Kinetics analysis shows that the decomposition of KZn2(PO4)(HPO4) acts as a double-step reaction of : a n order autocatalytic reaction (Cn) with n =1.0791, E1 = 365.06 kJ/ mol, A1 =8.69×1022s−1 is followed by a expended Prout-Tompkins reaction (Bna) with n=2.6548, E2 = 390.91 kJ /mol, A2 = 5.37×1024 s−1. In different pH 3.5% NaCl extracts, KZn2(PO4)(HPO4) functions as a cathodic inhibitor on steel and is even superior to other phosphates in efficiency. The inhibiting efficiency of the pigments on steel decrease in the order: KZn2(PO4)(HPO4) > aluminum zinc phosphate > zinc phosphate ≧ aluminum triphosphate