How the duty cycle affects wear and corrosion: A parametric study in the Ni–B–TiN composite coatings

Abstract

TiN-reinforced Ni–B composite coatings were synthesized in the watts bath using pulse electrodeposition method at different duty cycles of 20%, 40%, 60%, and 80%. The surface morphology, phase structure, hardness, wear, and corrosion behavior of the coatings produced at different duty cycles were examined. The effect of the duty cycle on the microstructure of the composite coating was investigated using scanning electron microscopy (SEM) analysis. Depending on the duty cycle, a coating thickness of ∼69.7μm was obtained on the cathode surface. Crystallite size and lattice distortion of coatings were calculated with X-ray diffraction (XRD) data. The nano-indentation hardness results showed that the high nucleation rate at 40% duty cycle increased the coating hardness to 1170 HV. The wear test results indicated that the distribution of TiN particles in the coating content reduced the wear rate of the coating to 2.121 × 10−5mm3/Nm. Corrosion tests performed in 3.5 wt.% NaCl solutions were analyzed by Tafel curves and electrochemical impedance spectroscopy (EIS). Depending on the duty cycle/reinforcement particle distribution relationship, icorr and Ecorr values were measured as 2.27x10 −6 (A/cm 2) and -0.427 V, respectively.