The development and characterization of electroless Ni-P nanocomposite coatings and investigation of their corrosion resistance

• Author / Creator

  Shuang, Shuo

• The Steam Assisted Gravity Drainage (SAGD) system is a commonly employed method to extract crude oil in Alberta. The slotted liners of the SAGD system are made of L80 carbon steel, which is prone to the corrosion attack in the corrosive serving environment containing H2S and CO2. To reduce the corrosion rate and extend the lifetime of slotted liners, an electroless deposition of nickel–phosphorous (Ni-P) coating is applied on the carbon steel. Ni-P coating has unique properties such as remarkably high hardness, wear resistance and exceptional corrosion resistance. However, there are still some intrinsic defects in the Ni-P matrix, which enables aggressive ions to reach the substrate. It should be noted that nanoparticles possess many well-known physical and chemical properties because of their quantum size effect. Therefore, developing Ni-P nanocomposite coating is an effective strategy to modify the physicochemical property of the Ni-P coating.
  The goal of this study was to develop Ni-P nanocomposite coatings by adding nanoparticles to the plating solution, thereby filling defects in the Ni-P coating with nanoparticles and improving the performance of the Ni-P coating.
  The Ni-P-WC and Ni-P-Fe3O4 coatings were prepared by electroless deposition methods, modifying the typical Ni–P coating by adding different amounts of WC and Fe3O4 nanoparticles, respectively. The morphology, structure, microhardness, and corrosion resistance of the Ni-P-WC coating, Ni-P-Fe3O4 coating, and conventional Ni-P coating were analyzed using optical stereoscopic microscopy (OSM), scanning electron microscopy (SEM), polarization curve and electrochemical impedance spectroscopy (EIS), X-ray powder diffraction (XRD) and Vickers hardness tests.
  The study showed that WC nanoparticles had an important impact on the microhardness, anti-corrosion properties and morphology of the coatings. The results of electrochemical tests in the National Association of Corrosion Engineers (NACE) standard solution containing CO2 and H2S showed that the electroless Ni-P-WC coating exhibited better anti-corrosion ability than the Ni-P coating. The superior stability of the Ni-P-WC coating was confirmed by long-term immersion tests in the simulated solution. The Ni-P-WC coating also had an increased hardness than the Ni-P coating. The coating formed in the bath containing 5 g/L WC particles showed the highest hardness value and best corrosion resistance.
  The results showed that Fe3O4 nanoparticles deposited homogeneously on the Ni-P matrix. The electroless nanocomposite coatings exhibited an amorphous structure. The results of corrosion tests in the 3.5 wt. % NaCl solution indicated that the electroless Ni-P-Fe3O4 coating proved to be much more corrosion resistant than the conventional Ni–P electroless coating. With Fe3O4 concentrations were increased from 0 g/L to 3.0 g/L in the plating solution, the corrosion resistance of Ni-P-Fe3O4 coating increased and then decreased. This increasing-and-decreasing tendency was also observed in thickness of the coating. The coating demonstrated the best corrosion resistance and maximum thickness when the concentration of Fe3O4 was 0.8 g/L in the plating solution. In immersion tests, the Ni-P-Fe3O4 coating showed better stability than the Ni-P coating. Correspondingly, the rational mechanism behind the improvement of corrosion resistance due to the addition of Fe3O4 was further discussed.

• Subjects / Keywords

  • WC nanoparticle
  • Ni-P nano-composite coating
  • Corrosion resistance
  • Fe3O4 nanoparticle

• Graduation date

  Fall 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3D795S75

• License

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