| Nano-composite electroplating is a new and upcoming composite surface technology, by adding nano partials into electrolyte or plate fluid, while causing the partials to deposit onto the metallic surface bounded to cathode, creating a better performing plate surface. This technique is slowly becoming the focus in the plating research field. The research discusses the difference in nano-plating using direct circuit and pulse, taking into account of the plate density and strength. The best result can be obtained by electroplating the Copper(Ⅱ) Sulphate Pentahydrate at concentration of 200g/L, Sulphuric Acid 78g/L, anion-surfactant 0.8g/L, nano Aluminum trifluoride 25g/L, mixing at 240rpm, electrolyte temperature at 24℃, electric density at 4.58A/dm2 work ratio 0.3, frequency at 300Hz. The plated structure were analysed using multiple technique, like electron microscope (SEM), X-ray diffract (XRD), corrosion weight loss, anodic polarization curve and high temperature oxidization reaction, analytical results where compared and discussed in the thesis.By studying the results of plating Cu-nanoAlO3 using acidic Copper sulphate as solvent, with 3 typical surfactants:cationic Hexadecyl trimethyl ammonium Bromide; Cetrimonium Bromide (CTAB), anionic Linear alkylbenzenesulfonate (LAS) and non ionic Polyethylene glycol, avg mol wt 6000 (PEG 6000). It can be concluded that plating with CTAB increases the suspension of the plated subject and enhance the binding of the Cu-nanoAl2O3 on to the subject; while LAS improved the condition of the plated surface, however it does not have any effect on the molecular level binding of the Cu-nanoAl2O3 molecules.The Cu-nanoAl2O3 nano-composite coatings were prepared by direct and pulse electrodeposition (named DC and PC) respectively. The results from scanning electron microscope (SEM) indicate that compared with DC, the morphology of PC illustrates the following features. The surface texture is more fine, and the crystallline granules on sueface are more uniform, and dense. Additionally, the orientation of the granules is enhanceed. The results from X-ray diffract ion indicate that the preferential orientation and granules size of the composite coating strongly depends on the preparation method. Both lattice constant and distortion of PC were increased, which agree with the results from SEM mentioned above. Using continuous direct circuit plating, cation contin uously deposit onto the plate surface; single pulse plating utilise the break in the electric pulse to re-dissolve the unwanted larger granules of deposits thereby creating a more even plate surface. Results show that using pulse plating yields finer plate crystals and increase the rate of plate crystal seed formation.Under common conditions and reaction parameters, single pulse electro plating yields more corrosion resistant plate surface. High temperature oxidization reaction shows that, single pulse electro plating yields a better plate result; resulting in higher average hardness than normal copper plated surfaces and direct current plated nano plating.Based on the DC diffusion model, we build a duplex diffusion layer model which is composed of inner pulse diffusion layer and outer stable diffusion layer. In inner pulse diffusion layer, the concentration of ions fluctuates with frequency of pulse current. For PC, the pulse diffusion layer only depends on the diffusion coefficient of cations and the pulse length, is not related to the current density and the concentration of the mass. In outer stable diffusion layer, the transport speed of ions is almost stabled all the time, the main purpose is to transport the ions from the mass to the pulse diffusion layer. |
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