Protection of type-304 stainless steel against to corrosion by conducting polymer coatings

Nowadays, many traditional methods have been used to prevent of corrosion. Especially in recent years, corrosion protection studies by using conducting polymers become important because of the properties that adapt to most of the widely used industrial metal, can be easily synthesis as chemical or electrochemical, properties can be changed easily and environmentally safe. One of the conductive polymer which is used for this purpose, polyaniline (PANI), is one of the most preferred conductive polymer due to high protection yield, easy synthesis and have a different oxidation states unlike other conductive polymers. In this study, corrosion behavior of Type-304 stainless steel coated PANI and its derivatives of poly N-ethylaniline (PNEA) and poly N-methylaniline (PNMA), were investigated in acidic medium. In this study, cyclic voltammetry (CV) technique was used to synthesize conducting polymers onto the steel surface. PANI coatings on the electrode surfaces that prepared by using different techniques; effect of scan rate and number of coating on the corrosion behavior of metal were investigated in 1 M HCl. For the coatings formed at constant scan rate and number of different coatings, PANI, poly N-ethylaniline (PNEA) and poly N-methylaniline were used. Corrosion rate of conducting polymer coated Type-304 stainless steel were determined in 1 M HCl and 1 M H2SO4. Corrosion rates were calculated by the method of extrapolation of cathodic polarization curve to the corrosion potential. Experimental results were used in the study of experimental design in order to examine the effects of scan rate, cycle number and polymer type on the corrosion protection efficiency. Conductive polymer coatings were characterized by infrared (IR) spectroscopy and surface morphology were examined by using scanning electron microscopy (SEM). The results were expressed in the model equations and these equations showed that PANI, PNEA and PNMA coatings substantially prevent the corrosion of steel in acidic medium. Preparation technique of electrode surface, has been significantly increases the efficiency of protection. In general, the highest yield of protection in 1 M HCl and 1 M H2SO4 was obtained 96,2 % ( 20 mV/s scan rate, 15 cycle) and %98,1 (20 mV/s scan rate, 5 cycle), respectively.