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Sodium Silicate and Phosphate as
Corrosion Inhibitors for Mild Steel in
Simulated Cooling Water System |
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Two inorganic inhibitors were used to
protect mild steel in cooling water system (single and binary
sodium silicate and phosphate). Four different concentrations of
silicate and phosphate ions were used
(1×10−3, 5×10−3, 1×10−2 and 0.2M) and (1 × 10−3, 5 × 10−3, 1 ×
10−2 and 0.1 M), respectively, in addition to two mixtures of
SiO2−3 and PO3−4. Corrosion parameters were measured by
electrochemical method using potentiostat such as
corrosion potentials, corrosion current densities and Tafel
slopes to calculate polarization
resistance. Protection efficiencies P% were calculated to
know the best concentration of inhibitors; these results
indicate that the best concentration of SiO2−3 and PO3−4 is
1×10−2M that gave P%74.088 and 95.494, respectively,while PO3−4
gave better protection than SiO2−3 and
its mixtures. The adsorption of SiO2−3 and PO3−4 on the steel
surface in simulated cooling water obeys the Langmuir adsorption
isotherm model. |
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