Research On Synthesis And Corrosion Property Of Ni-Cr-Mo-Cu Alloy

The composition and the range of APF factor of Ni-Cr-Mo-Cu alloys designed by APF factor were determined by Tammann Theory. Alloy with the APF factor of 1.5, 2.875, 3.3, 3.8, and 4.3 were selected as research sample respectively. And in order to research the corrosion property in gas, four kinds of alloys with different Cu content were prepared respectively. They were shown as:1) The oxygenation and high temperature examination of alloys with different Cu content and APF=2.875 were performed, and universal resistance of corrosion of these alloys were analyzed accordingly.2) The linear potential scanning of cathodic process for corrosion reaction in HCl solution were performed for five kinds of Ni-Cr-Mo-Cu alloys from the solution concentration range of 0.002mol/cm³ to 0.012 mol/cm³ at 20℃. According to these polarization curves, the exchange current density, corrosion potential, the number of exchange electron, reaction order, and the rate constant of five kinds of alloys at different HCl solution were determined. The experiment relationships of these kinetic parameters with HCl solution concentration and APF factor were constructed. From which, the corrosion resistance character of alloys in HCl solution was identified, and the relationships of corrosion resistance of alloys with HCl solution concentration and APF factor were concluded.3) The linear potential scanning of cathodic process for corrosion reaction in H₂SO₄ solution were performed for five kinds of Ni-Cr-Mo-Cu alloys from the solution concentration range of 0.002 mol/cm³ to 0.012 mol/cm³ at 20℃. Regard to two kinds of mechanisms of cathodic reaction: H⁺ reduced at low H₂SO₄ concentration and water molecular at high concentration, the kinetics of cathodic process was analyzed. According to the cathodic polarization curves, the solution concentration of mechanism shift and the kinetic parameters corresponding to different reaction mechanism were determined, and the relationship of kinetic parameters with H₂SO₄ solution concentration and APF factor were constructed. From which, the corrosion resistance character of alloys in H₂SO₄ solution was identified, and the relationships of corrosion resistance of alloys with H₂SO₄ solution concentration and APF factor were concluded.4) The linear potential scanning of cathodic process for corrosion reaction in NaOH solution were performed for five kinds of Ni-Cr-Mo-Cu alloys from the solution concentration range of 0.0025mol/cm³ to 0.0150 mol/cm³ at 20℃. Kinetic parameters, such as the tuning current, tuning constant, passive potential and passive film thickness, were determined from above polarization curves, and the relationship of kinetic parameters with NaOH solution concentration and APF factor were constructed. According to this, the corrosion resistance character of alloys in NaOH solution was identified, and the relationships of corrosion resistance of alloys with NaOH solution concentration and APF factor were concluded.5) Finally, the current of the procession of electrochemical corrosion was analyzed quantitatively by the calculation of quantum theory and Computer-analysis and Modeling. Crystal structure of five kinds of Ni-Cr-Mo-Cu alloys were obtained by the D8-ADVANCE diffract meter. Structure was refined by Rietveld method, and high-accuracy crystal structure was obtained. Fermi energy and the densities of electron in alloys were calculated by means of the Materials Studio 4.0. The current of the reaction of electrochemical corrosion was analyzed quantitatively by the math model of calculating current in the electrochemical reaction, and the structure reason of the corrosion resistance of alloys changing with the change of APF factor was explained.