| Organic anticorrosive coating is an important means of metal corrosionprotection, as people’s requirement of corrosion protection increases, however,anticorrosive coatings are designed to have a long life of anticorrosion performance invarious complex environment, so coatings must have a variety of excellentcomprehensive performance to meet the requirements.In this paper, with the aid ofscanning electron microscope (SEM) and electrochemical impedance spectroscopytest (EIS), and other research methods,we comparatively studied the epoxy micaceousiron oxide corrosion protection coatings, polyurethane anticorrosion coating andpolyurea coatings three kind of anticorrosive coating,when immersing them in5%salt water, hot and humid environment, dry-wet circulation and uv accelerated agingand function under the condition of wet and dry cycles, its gloss and adhesionperformance of change rule, we analyzed their anticorrosion performance. Throughthe study we have got the following conclusions:1.The conventional performance results of polyurea coating, polyurethanecoating, epoxy micaceous iron oxide coating show that the tensile strength ofpolyurea coatings is26.65MPa,which is6.9times of that of the epoxy micaceous ironoxide and2times of the polyurethane;their Elongation at break is498.33%,11times of epoxy micaceous iron oxide coating and47times of the polyurethanecoatings; The Three kinds of paint dry time was47s、1.5h、2.5h, The gel time was10s,4h,7h;The respective solid content of the above coatings is97.8%,89.2%and67.8%,they are all high solid content polyurea coatings with zero VOC; These threekinds of coatings’ bibulous rate is2.16%,4.21%and1.17%respectively; Constanttemperature humidity adhesion are all greater than3.0MPa, and they still keep asufficient wet adhesion under a certain temperature range.2.The5%brine immersion corrosion study showed that when polyurea coatings,polyurethane coatings, epoxy micaceous iron oxide coatings are immersed in5%saltwater for90d, the light loss rate was4%,16%,16%respectively; The adhesion ofpolyurea coatings and epoxy micaceous iron oxide coatings is2.42MPa and1.15 MPa respectively; Polyurethane coatings bubblinged when it was76d; The analysisof SEM to coating/metal interface hints that polyurethane coating metal has severecorrosion, epoxy micaceous iron oxide coating metal shows signs of corrosion,while polyurea coating/metal interface in good condition, its antiseptic performancesgood; EIS experiments show that the polyurethane coating has failure in21d,polyurea coatings and epoxy micaceous iron oxide coating are in the intermediatesoaking stage.The phenomenon,combined with the coating phase Angle at105Hz andchanges with time, informs us that the porosity in above5%brine corrosionresearch results demonstrate that the anti-corrosion ability of polyurea coating isbetter than the other two kinds of coating.3.The damp and hot corrosion experiment study shows that after90days’ wetand heat aging, polyurea coatings and other two slightly lost their light; After dampheat aging,polyurea coating still keeps the adhesion of2.63Mpa in90d, whilepolyurethane coating and epoxy micaceous iron oxide coating lost adhesionrespectively in65d and82d; The SEM analysis of interface shows that polyurethaneand epoxy micaceous iron oxide coating metal appeared different degree of corrosion,polyurea coating protection is good. EIS experimental results shows that in28dpolyurethane coating resistance is less than106Ω. cm2, indicating the failure of thecoating, the other two coatings are effective. The phenomenon,combined with105Hzphase Angle and the coating porosity change over time,informs us that the epoxymicaceous iron oxide coating anticorrosion performance is the best. EIS experimentsresults and the macro to micro experiments of polyurea coating anticorrosiveperformance of the optimal result, it may be related to the thickness of the coatingexperiment.4.The dry-wet circulation corrosion experiment research shows that after90ddry-wet circulation corrosion polyurea coating, polyurethane coating and epoxymicaceous iron oxide coating have different levels of light, three kinds of coatingadhesion are greater than2.00MPa. Adhesion results are in agreement with the SEManalysis results, the coating and metal adhesive is good, the metal corrosion didn’thappen. EIS experiments results show that the dry-wet circulation corrosion after35, three kinds of coating resistance were1.60x106Ω. cm2,1.38x106Ω. cm2,5.52x105Ω. cm2. we can know that the polyurea coating in wet environment anticorrosionperformance is optimal, polyurethane, epoxy micaceous iron oxide is the worst.5.The uv accelerated aging and the dry-wet cycles corrosion test research showsthat after90d corrosion, polyurea coating, polyurethane coating and epoxy micaceousiron oxide coating are all seriously loss of light.During the experiment, the adhesionof polyurea coating is always higher than that of the rest of the two kinds of coating,when its90d coating adhesion were2.92MPa,1.83MPa and1.61MPa respectively.The SEM analysis showed that interface, under three kinds of coating metal are nocorrosion. EIS experiments indicates that the failure time of three kinds of coating are35d,28d and21d respectively.we know that the polyurea coatings in the uvaccelerated aging and the dry-wet cycles under the action of anti-corrosionperformance is the best, polyurethane coating anticorrosion performance times, epoxymicaceous iron oxide coating is the worst.The experimental study shows that polyurea anti-corrosive coating anticorrosionperformances in four kinds of environment better than that of polyurethane and epoxymicaceous iron oxide anticorrosive coating.The experimental research provides basicdata and theoretical support for the application of polyurea anti-corrosive coating. |
PDF Full Text Request