INVESTIGATING THE EFFECT OF CHEMICAL TREATMENTS ON CORROSION BEHAVIOR OF CARBON STEEL VIA ELECTROCHEMICAL NOISE AND POLARIZATION METHODS

The effect of phosphating and phosphating with post-treatment of passivation with chrome-free solution based on zirconume on corrosion rate and resistance of carbon steel in 3.5% NaCl solution has been investigated by Electrochemical Noise Method (ENM) and Polarization tests (DC tests). The noise resistance curves illiustrate that phosphating improves the resistance of carbon steel against the corrosion and this effect enhances via post-treatment of passivation .The results of polarization tests show that LPR (Linear Polarization Resistance ) of carbon steel increases by phosphating and by applying post-treatment of passivation LPR enhances more. The results of polarization tests also illustrate that corrosion rate is reduced by phosphating and after post-treatment of passivation reduction of corrosion rate is more. Also the results of noise resistance curves is confirmed by LPR curves .