چكيده به لاتين
In this study, the effective parameters on the Ni-W nanocomposite coating structure with TiC nanoparticles which was produced on low carbon steel substrate by means of pulse electroplating was investigated. Pulse electroplating was performed at 70 ° C for 1 hr at different frequency, duty cycle, TiC nanoparticles concentration in electrolyte and effect of these parameters on properties of coating was investigated. Microstructure of the coatings and dispersion of TiC nano-particles were studied by scanning electron microscopy (SEM). Crystallite size was calculated using X-ray diffraction patterns by the Scherrer equation. Finally the polarization and electrochemical impedance methods were applied to measure the corrosion resistance properties of the nanocomposite coatings in 3.5% NaCl solution. The results showed that the pulse frequency of 1000 Hz, duty cycle of 80%, average current density of 10 A/dm2, and TiC nano-particle concentration of 5 g/L were the optimum plating conditions. The amount of TiC nano-particles incorporated into the coating that were produced under the optimum plating conditions was 3.5 wt.%; also, the crystallite size of this coating was 16 nm and the micro-hardness was 947 Hv. Incorporation of TiC nanoparticles reduced crystallite size and increased microhardness of Ni-W-TiC nanocomposite coating compared to Ni-W alloy coatings. By increasing the pulse frequency and duty cycle, the corrosion resistance of Ni-W-TiC nanocomposite coating increased. Among the coatings prepared with different concentrations of TiC particles, the coating with a concentration of TiC 5 g/L particles had the highest corrosion resistance. The Ni-W-TiC nanocomposite coating produced by the pulsed current compared to Ni-W-TiC nanocomposite coatings produced by direct current and Ni-W alloy coating showed higher corrosion resistance.
Keywords: pulse electrodeposition, duty cycle, frequency, average current density, TiC nanoparticles concentration, corrosion resistance, Ni-W-TiC nanocomposite coating.
