Development of nickel coatings by TiN interlayer

Nickel coating was electrodeposited on steel substrate using Watt's bath. With an aim to improve the corrosion resistance of Ni coating, an additional TiN interlayer of approximately 300 nm thick and average grain size 22 nm was deposited on the substrate using a plasma focus device (PFD). The electrochemical behavior of single layer TiN deposited on steel substrate and Ni coatings were studied in 3.5% NaCl solution. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) combined with an energy depressive X-ray (EDX) microanalyzer were applied to characterize the coated samples. The potentiodynamic polarization tests showed lower corrosion current density and higher polarization resistance for the coatings with TiN interlayer. Similarly, Ni coatings with TiN interlayer showed about six times improved corrosion resistance in 1 M HCl as compared to the samples without TiN interlayer. Salt spray test has been used to determine the performance of coated samples in 5% vapor of NaCl.