Protection Of Cooling Water System In Motors Cars From corrosion using Sodium Nitrite and Sodium hexametaphosphate


Abstract This research is included the investigation of electrochemical behaviour of Carbon-Steel in natural aerated solution of cooling system for motor cars and performance of sodium nitrite (SN) and sodium hexametaphosphate (SHMP) inhibitors blend for inhibiting of such corrosion process under controlled conditions of mass transfer . To achieved such control , under turbulent flow a rotating cylinder electrode ( R.C.E. ) system was designed to provide quantified hydrodynamics . Potentiostatic polarization measurements under isothermal conditions were carried out at ( 313 , 323 , 333 , 343 , 353 , 363 and 373 ) K by using uninhibited solution and flow rates of ( 100 , 200 , 300 and 400 ) r.p.m. at each temperature . Corresponding experiments for inhibited solution under the same conditions . The results show that the limiting current density is increased with increasing the temperature range and flow rate in uninhibited and inhibited solution . Also , the corrosion potentials are generally shifted to the more positive direction with increasing temperature and flow rate , whereas such potentials are shifted in less positive direction by using mixture from inhibitors . Increasing in limiting current density (iL) with rate the rotation is obey Levich equation . The interpretation that it is introduced in this study about the corrosion potential in uninhibited solution are independence on the theory of mixed potential . The mechanism of inhibition by using these inhibitors have been shown and discussed .