Research On The Corrosion Behavior Of Carbon Steel With Different PSI And Chloride

The corrosion behaviors of carbon steel in Ca (HCO3) 2 solution with different PSI, the effect of chloride and the effect of HEDP and zinc salt on the corrosion behavior of C.S were studied by weight loss, polarization curves and XPS methods. The performances of scale inhibitor, like HEDP, on Ca (HCO3) 2 solution with different PSI were evaluated by static test.1. The corrosion behaviors of carbon steel in Ca (HCO3) 2 solution with different PSI(1) The corrosion behaviors of carbon steel in Ca (HCO3) 2 solution is typical activation-passivation system and the carbon steel's corrosion rate raised by PSI; (2) The out layer of protective film formed by Ca (HCO3) 2 solution on the surface of carbon steel comprised Ca (Ⅱ) ,C (Ⅳ) , O (Ⅱ) and O2－ mainly;(3) When the value of PSI of Ca (HCO3) 2 solution is lower than 6.0,it can form a film on the carbon steel surface to protect C.S.2. The effect of chloride on the corrosion behavior of carbon steel(1) The carbon steel's corrosion rates are raised by the concentration of chloride;(2) The chloride can spoil the film on the carbon steel's surface and accelerate the corrosion rate of carbon steel.3. The effect of chloride and the effect of HEDP and zinc salt on the corrosion behavior of carbon steel(1) When there is no chloride in the Ca (HCO3) 2 solution with different PSI, if added HEDP or Zn2+ in the solution only, the corrosion rate of carbon steel would decrease; when the value of PSI is 3.0 or 4.0, the ip of C.S turns to be smaller;(2) If added HEDP or Zn2+ in the Ca (HCO3) 2 solution only, the corrosion rate of carbon steel would decrease slightly;(3) If added HEDP and Zn2+ in the Ca (HCO3) 2 solution at the same time, the corrosion rate of carbon steel would decrease obviously;(4) If the concentration of chloride is too high, it could spoil the film on the carbon steel's surface;(5) The out layer of protective film formed by Ca (HCO3) 2 solution (PSI=3.0, HEDP= 5ppm) on the surface of carbon steel comprise Ca (Ⅱ) ,C (Ⅳ) and O (Ⅱ) mainly, but do not discovery element P;(6) The out layer of protective film formed by Ca (HCO3) 2 solution (PSI=3.0, Zn2+= 2ppm) on the surface of carbon steel comprise Ca (Ⅱ) ,C (Ⅳ) ,O (Ⅱ) and Zn (Ⅱ) mainly;(7) The out layer of protective film formed by Ca (HCO3) 2 solution (PSI=3.0, HEDP= 5ppm, Zn2+= 2ppm) on the surface of carbon steel comprise Ca (Ⅱ) ,C (Ⅳ) ,O (Ⅱ) ,Zn (Ⅱ) and P; but the exist situation of P is complex.4. The scale inhibition performances of HEDP on Ca (HCO3) 2 solution with different PSI(1) In the range of the value of PSI adopted in the experiments, the scale inhibition performances of HEDP are not so good;(2) The rates of scale inhibition of HEDP are raised by the concentration of chloride.