Study Of Modified Potassium Silicate Zinc-rich Anti-corrosion Coatings

Waterborne inorganic anti-corrosion coatings have been widely used in marineanticorrosion, architrctural anticorrosion and industrial due to their excellent corrosionresisrance, high hardness, adhesive force, solvent resistance, weather resistance. Waterborneinorganic zinc-rich coatings have outstanding abilities of float, cover, shielding andsignificantly reduce the amount of zinc pigment by using the flake zinc pigment and theseadvantages has attracted more and more attention. However, the application of the coatingwere limited by the poor mechanical properties of zinc-rich coating resulted from the directuse of the flake zinc powder, which can lead to difficultly dispersing, poor anti-settling andprone to agglomeration. So the research on overcome the settlement and poor dispersion ofthe flake zinc powder has attract more and more attention, and added additives and modifiedthe flake zinc powder are the most effective ways to improve the properties of zincdispersing and anti-settling. To solve the above problems, the author added different types ofanti-settling agents into the system, and studied on the effect of the types of anti-settlingagent on fineness, mechanical and corrosion resistance properties of coating. In addition, theauthor modified the flake zinc powder by different types of modifiers, and discussed theeffect of the types of modifiers on the dispersing of flake zinc powder and the corrosionresistance properties of the coating.In this paper, we have got a stable organic-inorganic zinc-rich coating obtained by themodified potassium silicate solution mixing flake zinc pigment with different types ofanti-settling agent. The effects of the type and amount of anti-settling agents on the paintproperties, appearance and corrosion protective performance of zinc-rich coating wereinvestigated. On this basis, the flake zinc pigment were modified by different types ofmodifiers. The effects of the modifiers on properties of dispersing and anti-settling of zincpigment were analyzed by the data of activation degree and sedimentation volume, and thebest modifier of the flake zinc pigment was selected by comprehensive performance of thecoating. The results show that the performance of organic montmorillonite with–COOH asanti-settling agent of zinc-rich anti-corrosion coating is better than the coating with organic montmorillonite with–CH3as anti settling agent and the later is superior to zinc-richanti-corrosion coatings without anti-settling agent, and the coating with MMT asanti-settling agent is the worst. The zinc-rich coating by using0.3mass%of organicmontmorillonite modified by HOOC(CH2)17NH3+as the anti-settling agent could providecompact film and excellent mechanical properties and corrosion protective performance.Using SEM and Polarization curves tests for modified zinc-rich coatings, the flake coatingsurface was crisscross superposition state, the coating layer had smoother surface.Polarization curves test results showed that the Ecorr of coating prepared by flake zincpowder modified by Gum Arabic and SDBS could be improved from-0.6V to-0.5V UsingSEM and Polarization curves tests for modified zinc-rich coatings, the flake coating surfacewas crisscross superposition state, the coating layer had smoother surface. Polarizationcurves test results showed that the coating prepared by flake zinc powder modified by GumArabic and SDBS could improve100mV Ecorr, so that the coating has stronger corrosionresistance.