Dissertation > Industrial Technology > Chemical Industry > Electrochemical industries > Electroplating industry > A single metal plating

The Corrosin Properties of Nano-scale Twin Coatings of Nickel in Solution with Cl

Author SunFeiLong
Tutor WangFuHui
School Harbin Engineering University
Course Materials Science
Keywords Nano - twinned Pulse plating Orthogonal design Phytic acid Passive film Pitting
CLC TQ153.1
Type Master's thesis
Year 2010
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Prepared by pulse plating technology (NT) coating , nano - twinned nickel , and corrosion as standard orthogonal experimental design to optimize the parameters of pulse plating . The results showed that : when a positive going pulse that the average current density of 1.5 A/dm2, and a duty cycle of 20 % , a frequency of 250 Hz , the resulting nickel plating the best corrosion resistance . Using transmission electron microscopy (TEM), scanning electron microscopy ( SEM ) , electrochemical impedance spectroscopy (EIS) to study the effects of phytic acid on coating microstructure and morphology , as well as corrosive . The results showed that : phytic acid to promote the growth of nano twinned crystal grains , changing the morphology of the surface deposition , and improves the corrosion resistance of the coating . X-ray photoelectron spectroscopy (XPS), zero the charge potential test (pzfc) technology and chronoamperometry study the chemical composition of the generated nano- twinned structure of the nickel surface passivation film , the chloride ion adsorption and passivation film into nucleation and growth mechanisms . The results show that , compared with the industrial electrolytic nickel (IE) , generated nano- twinned nickel plating , passivation film is more complete , more dense , surface adsorption of chloride ions ; nano- twinned structure does not change the shape of the passive film nuclear way, are three-dimensional nucleation , but the passive film parallel to the increase in the growth rate . By potentiodynamic polarization curves and capacitance testing techniques to study the impact of nano - twinned structure of nickel resistance to localized corrosion and passive film semiconductor performance . The results show that , compared with the industrial electrolytic nickel , nickel nano - twinned with superior pitting resistance , surface passivation film inner layer of p-type / outer layer of n-type double-layer semiconductor structure . Application Mott-Schottky (MS) relations and point defect model (PDM) vacancy density in the passive film and vacancy diffusion coefficient . The results showed that the nano - twinned structure reduces the diffusion rate of vacancies in the passivation film , to promote passivation film growth thinner and more compact . Finally , nano- twinned structure on the mechanical properties of nickel nano nano- indentation technique . The results showed that the nano- twinned structure significantly improves the hardness and elastic modulus of the nickel surface passivation film , the passivation film is not easy to rupture the formation of pitting , so more excellent pitting resistance of nano- twinned nickel plating .

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