Study On The Properties And Curing Kinetics Of Corrosion Coatings Of CO 2 + / S ^{2 -} Corrosion Coatings

Recently, for one thing, in the wake of our increasing demand for oil and gas resources, the exploitation of harsh natural conditions oil and gas fields (especially acidic oil and gas fields) begin to develop. For another thing, there are more research about alone CO2or S2-anti-corrosion coatings, however our acidic oil and gas fields frequently are CO2and S2-coexistence system. Therefore it has important practical significance to study a kind of organic coating to prevent the N80steel corrosion by CO2and S2-.With orthogonal and single factor experiment by coating the main physical and electrochemical properties of test, the optimum coating formulations of polyaniline, zinc and epoxy were determined. The results show that, when the mass ratio of the component A are epoxy resin36.90%, polyaniline0.37%,3.69%zinc,29.52%polyamide, other fillers (including titanium dioxide, silicon dioxide and talc)33.21%, B component n-butanol and n-methylpyrrolidone each50vol.%, the prepared coating was with adhesion of layer reaching level1, hardness of5H and the impact resistance of40cm.The corrosive resistance of the coating had been studied by electrochemical workstation, IR, TG, SEM and XRD. The results show that, there is no peeling, wrinkling, blistering and rusting, only colors on the surface of the coating becoming darker after it had been soaked in the5wt%NaCl,10wt%HCl and20wt%NaOH for30days. Coating’s mainly organics epoxy resin, polyamide650and polyaniline IR absorption peaks characteristic functional groups did not change, initial weight loss temperature reduced from315.2℃to293.3℃but the half-life greatly increased, after soaking in7MPa CO2and lg/L Na2S solution at120℃for72day. In the saturated CO2and Na2S solution, with immersion time and Na2S content increasing, the corrosion rate of coating first increased and then decreased. With soaking temperature rising from35℃to80℃, the corrosion resistance of coating increased first, then decreased, which was because the rising temperature not only increased the conductivity of polyaniline but also maked it translate from oxidation state to the intrinsic state. With the increase of CO2partial pressure from3Mpa to7MPa, the corrosion rate of coating increased. In the corrosion condition of1g/L Na2S solution and CO2with7MPa, the sulfide corrosion samples occur mainly on the coatings and the corrosion products were FeS and ZnS. The mechanism of coating for anti-corrosion is shielding effect and cathodic protection.With the analysis of DSC, the curing process of the polyaniline, zinc and epoxy coating were researched through chemical reaction kinetics. The kinetic three-factor was solved by phenomenological n-level model fitting. Experimental results show that, system reaction order is0.939, the average pre-exponential factor is89.028×106s-1, Kissinger method to calculate the apparent activation energy of numerical approach is49.856kJ/mol, n-level model can accurately reflect the coating curing behavior. Curing reaction rate equation for the composite coatings of reaction curing degree is:do/dα/dt=89.028×106e(-49855.672/RT)(1-α)0-939.