Dependence of Inhibition Effects of Oxalate, Tungstate, Molybdate and Phosphate on Purity of Zinc Metal

Abstract

The inhibition effects of oxalate, tungstate, molybdate and phosphate on corrosion of 99.99 %, 99.999 % zinc and 99.95 % molybdenum metals were investigated in NaCl solutions by potential-time, AC-impedance spectra and current-potential curves. The corrosion rates of metals are highly dependent on the purity of its. The inhibition effect of these anions on 99.999 % purity zinc is less than the effect on 99.99 % purity zinc. This implies that alloying elements are effective on inhibiting efficiencies of these anions. Inhibition effect of these anions decreases also with increasing NaCl concentration. None of the studied anions behaved as inhibitors on 99.999 % purity zinc in 1 M NaCl solution. The corrosion mechanism on the zinc metals is charge-transfer, but reaction on the molybdenium is diffusion controlled in the studied solutions.

Keywords: Zinc, corrosion, oxalate, tungstate, molybdate, phosphate

DOI: 10.7176/JSTR/5-4-12