| In order to prepare nickel-based nanocrystalline coatings with good hydrogen evolution catalytic performance and corrosion resistance,pulsed electrodeposition technology was used to prepare different crystals under different process conditions?plating solution pH,current density,duty cycle and plating solution temperature?.Grain size Ni-Co-W alloy coating.Scanning electron microscopy?SEM?and its accompanying energy dispersive spectrometer?EDS?,X-ray diffractometer,cathodic polarization curves,electrochemical impedance spectroscopy and tafel curveswere used to analyze the microstructure,element composition,grain size,the phase structure,hydrogen evolution performanceits and corrosion resistance.The results show that nanocrystalline Ni-Co-W coatings with different grain sizes can be prepared by adjusting the process parameters.When the current density is 2.5 A /dm2,the duty ratio is 20 %,the bath temperature is 30 ?,the plating time is 30 minutes,and the bath p H is equal to 4,the average grain size of the Ni-Co-W alloy coating is the smallest.59 nm.At this time,the coating has good hydrogen evolution catalytic performance and corrosion resistance.Its stable hydrogen evolution overpotential in 1mol/L NaOH solution is 1.072 V,and the self-corrosion potential(Ecorro)and selfcorrosion current(Jcorro)in 3.5 wt% NaCl are-0.29 V and 4.768E-7 A / cm2.The cyclic voltammetry curve,electrochemical impedance spectroscopy,and timing current curve were used to analyze the electrodeposition mechanism of Ni-Co-W alloy.The results show that electrodeposition of Ni-Co-W alloy is an irreversible process with nucleation behavior.The nucleation mechanism of Ni-Co-W alloy is instantaneous nucleation.The electrodeposition of the alloy is controlled by a mixture of kinetic and diffusion processes,which are mainly controlled by kinetics.Figure 50;Table 19;Reference 68... |
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