Deposition Rate and Electrochemical Corrosion Behavior of Nickel-Based Composite Coatings

Abstract

Metal corrosion control is technically, economically, environmentally and aesthetically important. The best option is to use coatings to protect metals and alloys from corrosion. Nickel plating is one of the most widely used methods for protecting less noble metal surfaces since the turn of the century. The need for improved coatings with better wear and corrosion resistance has led to the development and use of composite electrostatic deposits. In this paper, Ni-P-TiO2 composite coatings were fabricated by direct current electrodeposition on copper substrates. X-ray diffraction (XRD) analysis and energy dispersive spectroscopy (EDS) were employed to determine the average particle size of coatings elemental chemical composition. The electrochemical corrosion behavior of Ni-P-TiO2 composite coatings in 3.5 wt. % NaCl was characterized using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). The results indicate that TiO2 nanoparticles are included in the coatings. The deposition rate increased with increasing current density; the microhardness of the coatings noticeably increased with current density. Corrosion tests have shown that 3 A.dm -2 is the optimal value of the applied current density in terms of the lowest value Ecorr  -504 mV and the best charge transfer resistance Rp  114.7 Ω.cm 2 .