N80 Steel Surface Coating Preparation And Corrosion Behavior Of Simulated Oil Field Environment

Corrosion of tubing pipeline has become a severe problem to restrict development of petroleum industrial, hence many mechanicals at home and abroad have focused on it to prosecute widely protection technique research. To attain adaptive corrosion resistance coating and protection technology for tubing pipeline steel, Ni-P electroless plating coating, Zn-Ni alloy electroplating coating, Al-Zn-Si alloy hot dip coating and Ni-Cr-Fe-Ta-Mo-Ti alloy HVOF spray coating were prepared individually on the N80 steel which is popular to apply to tubing and were evaluated corrosion resistance property characteristic using simulation oil filed corrosion environment experiments, such as CO2 High temperature high pressure corrosion, neutral salt spray test ,Potentiodynamic polarization technique ,AC impedance spectroscopy, etc in this paper. In addition, component, the morphology, microstructure, bonding state both coating and substrate of the coatings were analyzed and studied by using scanning electron microscopy, X-ray diffractometer, glow-discharge photo-electron spectroscopy and so on respectively.The results show: (1) By orthogonal table, the new process conditions and solutions of Zn-Ni alloy electroplating coating and Zn-Ni alloy electroplating coating with good appearance and high corrosion resistance has been obtained. (2) The results of polarization curves show that according to N80 steel, Ni-P electroless plating coating and Ni-Cr-Fe-Ta-Mo-Ti alloy HVOF(high velocity oxy-fuel spraying) spray coating are cathode coatings contrast to substrate , while Zn-Ni alloy electroplating coating and Al-Zn-Si alloy hot dip coating are anode coatings. (3) The results of CO2 high temperature high pressure corrosion experiment under the simulation oil field condition shows that the Corrosion Capacity of the four coatings decrease sequentially in order of Ni-P deposition coating, Ni-Cr-Fe-Ta-Mo-Ti hot spray coating, Zn-Ni plating deposition coating, Al-Zn-Si hot-dipping coating.(4) Neutral salt spray test for evaluating Coatings corrosion property under Cl- condition shows that the Corrosion Capacity of the four coatings decrease sequentially in order of Ni-Cr-Fe-Ta-Mo-Ti hot spray coating, Ni-P deposition coating, Zn-Ni plating deposition coating, Al-Zn-Si hot-dipping coating. (5) AC impedance spectroscopy test which can indicate coatings corrosion mechanism under CO2 and Cl- condition and evaluate coating corrosion relative rate indicates that Ni-P electroless plating coating is the best corrosion resistance coating in cathode coatings ,while Al-Zn-Si hot-dipping coating is the best corrosion resistance coating in anode coatings.In summary, under the simulation oil field condition , Ni-P electroless plating coating is the most appropriate coating for tubing steel protection in the four investigated coatings, and has good prospect for application.