A Study On Impact Of Ferrophosphorus And Silane On The Anti-corrosive Capacity Of Epoxy Zinc-rich Coating

Zinc-rich primers have become the main matching primer species of the fields of heavy-duty coatings,such as the ships,bridges,offshore drilling platforms,terminals,pipelines,storage tanks and so on.Epoxy zinc-rich primer is the most variety of applications of organic zinc-rich primer.Ferrophosphorus has good conductivity,ferrophosphorus can be added into Epoxy zinc-rich primer to improve the utilization of zinc powder.Silane can be added into Epoxy zinc-rich primer to prolong the term of cathodic protection.This paper mainly studys the impact of ferrophosphorous and silane on the anti-corrosive capacity of Epoxy zinc-rich coating.Corrosion potential-time,EIS,XRD and SEM were used to assess impact of ferrophosphorus and silane on the corrosion prevention performance of the ZRP coatings.The main work and achievement obtained in this paper are shown as follows:(1)Two kinds of experimental device for testing EIS of organic coatings were compared.The EIS(electrochemical impedance spectroscopy)measurements on the coating/metal samples were made by using a three-electrode cell in which the sample was placed horizontally.A Perspex tube was fixed on the sample and filled with Electrolyte.A Auxiliary electrode and a reference electrode completed the arrangement.The organic glass tube can be fixed in two ways.The organic glass tube was fixed by binder on the coating/metal sample in the A device.In the B device,the organic glass pipe was fixed by screw between two pieces of organic glass plates.The EIS of epoxy coatings and epoxy zinc-rich coatings was studied by the two kinds of experimental devices.The results showed that the B device may be beneficial to improve experimental accuracy.(2)The impact of ferrophosphorous on the anti-corrosive capacity of Epoxy zinc-rich coating was studied.The results showed that coatings prepared by different levels of ferrophosphorous haven't significant difference.In the Epoxy zinc-rich coating,ferrophosphorous can instead of a part of zinc powder,but the impact of levels of ferrophosphorous on the anti-corrosive capacity of Epoxy zinc-rich coating need further research.(3)Corrosion potential of Epoxy zinc-rich coating adding ferrophosphorous and silane is the lowest.Its coating capacitance and corrosion reaction capacitance of zinc powder is lower,its coating resistance and corrosion reaction resistance of zinc powder is bigger.It has good cathodic protection at the same time,through bonding of silane and corrosion products of zinc powder filling the role to obtain better coating compactness.In the coating of adding ferrophosphorous and silane at the same time,Conductivity of ferrophosphorus improves the utilization of zinc powder,silane impels coating densification,thus decrease erosion rate of corrosion medium.The results of XRD and SEM showed that corrosion product are mainly Zn5(OH)8Cl2 and little Zn4C03(OH)6.