Enhancement of corrosion resistance in carbon steels using nickel-phosphorous/titanium dioxide nanocomposite coatings under high-temperature flowing water

To mitigate the corrosion of carbon steels in high-temperature flowing water, we deposited Ni-P/TiO2 nanocomposite coatings, composed of a Ni-P alloy matrix with dispersed TiO2 nanoparticles. Their morphology, early-stage open-circuit voltage, weight loss, and microstructure evolution after the tests, performed in a temperature range of 125 degrees C-175 degrees C with 5 m/s flow, were investigated. The incorporation of TiO2 nanoparticles in electroless Ni-P matrix was found to change the microstructure and improve the corrosion resistance especially at 150 degrees C. At 150 degrees C, the Ni-P alloy undergoes severe corrosion with the detachment of NiO while the Ni-P/TiO2 nanocomposite coatings remain passive by the galvanic coupling of the Ni-P matrix and the nanoparticles. Based on this study, TiO2 nanoparticles are found to enhance the passivation of the Ni-P alloy and, consequently, improve corrosion resistance in high-temperature flowing water. (C) 2016 Elsevier B.V. All rights reserved.