Corrosion Inhibitor Of Various Metals In Ethylene Glycol-Water-based Cooling Liquid

Coolant,the main function of which is to transfer the huge heat generated by engines or electronic equipments to the external environment,is an indispensable part of cooling system of engines and electronic equipments for the operation of engines and electronic equipments.The cooling system of engines and electronic equipments,which are composed of many kinds of metals,often suffers from severe corrosion under a long time operation.It is also important to study a new type coolant with a lower corrosion rate.In this paper,a coolant corrosion inhibitor system was formulated for cast aluminum,carbon steel,cast iron,brass,copper and solder.At the same time,the effect of the corrosion inhibitor system on the corrosion of many kinds of metals was studied with electrochemical polarization technology.And that the corrosion inhibition effect on six kinds of metals was verified by weight loss.Finally,the electrochemical behavior and corrosion inhibitoion mechanism of cast aluminum in this coolant were emphatically studied.Firstly,a new type of organic buffer system for a coolant with pH range from 8.5 to 9.0 was selected by hydrochloric acid consumption test.Secondly,eight kinds of compounds(organic azole compounds,organophosphates,pyrrolone compounds,thioketone compounds,borates,phosphates,organic zinc salts and cerium salts)were selected for inhibiting corrosion of cast aluminum and carbon steel by linear polarization method.On the basis of the above,the influence level of eight kinds of corrosion inhibitors on cast aluminum was studied by the L27(38)orthogonal method:phosphate>organic zinc salt>thione compound>pyrrolone compound>organophosphate>organic azole compounds>Cerium salt>borate,and that corrosion inhibitor system was formulated.The average corrosion inhibition rate of the corrosion inhibitor system on cast aluminum reached 97%.Finally,the corrosion inhibition effect on six kinds of metals was verified by parallel weight loss.It was found that the corrosion inhibition rate of this corrosion inhibitor system on the six kinds of metals was higher than 90%and the reproducibility was good.The effect mechanism of corrosion inhibitor system was studied qualitatively and quantitatively by polarization technique.The results showed that the corrosion inhibitor was a mixed type of corrosion inhibitor early and anode type corrosion inhibitor in the late,due to that the corrosion inhibitor has the same inhibitory effect on the corrosion cathodic and anodic process of cast aluminum in the coolant.The kinetics of cast aluminum in the coolant was studied by electrochemical impedance technique.It was found that the thickness of corrosion inhibition film on the surface of cast aluminum increased with immersing time,resulting in the increment of electrochemical impedanc.When cast aluminum was immersed in this coolant for 276h,the thickness of the inhibitory film increased to 1832nm and the electrochemical impedance was up to 159kΩ·cm2.The corrosion inhibition rate of cast aluminum in the coolant was up to 99.0%.Finally,the formulation of corrosion inhibition film was studied by scan electron microscopy(SEM)in conjunction with X-ray energy spectrometer.It was found that the corrosion inhibition film was composed of cerium salts and organic compounds containing N,P.