Papers by Keyword: Pulse Electrodeposition

Abstract: Ni-P coatings were prepared on low carbon steel substrates using the pulse electrodeposition method. The influence of the pulse duty cycle on the phosphorus content and hardness of the Ni-P coatings was investigated. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were employed to examine the surface morphology and chemical composition of the Ni-P coating layers. The results showed that an increased pulse duty cycle (20% - 80%) led to a decreased phosphorus content from 17.81 wt.% to 13.71 wt.%. The microhardness values were found to have an inverse relationship with the phosphorus content. The highest hardness of 538.22 ± 12.92 HV_0.1 was obtained from the sample produced with a duty cycle of 80%, which had the lowest P content of 13.71 wt.%.

Abstract: In order to improve the wear resistance, ensure the self-lubricating property, Cu-Sn coatings were prepared on the basis of non-cyanide pyrophosphate-stannate and strengthened by combining sol-gel method and composite electroplating technology. In the paper, graphite Sol and Al₂O₃ Sol were added to the Cu-Sn electroplating solution to obtain nanoparticles enhanced Cu-Sn-graphite and Cu-Sn-graphite-Al₂O₃. The effect of graphite Sol and Al₂O₃ Sol addition on composite coatings was investigated, such as surface morphology, micro-hardness and tribological properties. The result shows that the incorporation of the graphite Sol and the Al₂O₃ Sol lead to change the structure of the composite coatings. When the additions of graphite Sol and Al₂O₃ Sol were 110mL/L and 40mL/L respectively, the graphite and Al₂O₃ particles are uniformly distributed in the Cu-Sn matrix and contribute greatly to improve the hardness and tribological properties of Cu-Sn alloy coating.

Abstract: Synthesis and immobilization of Au nanoparticles (AuNPs) was performed on transparent fluorine-doped tin oxide (FTO) substrate by pulse electrodeposition method. The method was cost effective, simple and capable of producing nanoparticles strongly attached to the substrate. Effects of several influencing factors such as duty cycle, pulse frequency, current density, solution concentration, deposition period and annealing procedure on the optical properties of AuNPs-FTO electrode were investigated. AuNPs-FTO electrodes were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and UV-Vis absorption analysis. Controllability of the plasmon absorption of the electrodeposited film by tuning of the electrodeposition conditions and thermal annealing procedure was important achievements helpful to the progress of the AuNP film applications in the tunable localized surface plasmon resonance spectroscopy (LSPR) manufacturing industry.

Abstract: Tin seleno telluride thin film was deposited by pulse electrodeposition onto fluorine doped tin oxide coated glass from aqueous solution containing Sn-EDTA, Na₂SeO₃ and TeO₂. The sample was deposited at a potential of-0.40 V vs Ag/AgCl with various duty cycle between 10% to 90% followed by annealing under nitrogen gas at 250°C for 30 minutes. The crystalline structure, morphology and photoresponse of the thin film was analyzed using X-ray diffraction (XRD), scanning electron microscopy and linear sweep photovoltammetry techniques. The XRD pattern shows polycrystalline cubic structure of SnSe_0.4Te_0.6 for film deposited at 50% duty cycle. The domain peak at 2θ=28.82^o shows a high intensity and a better photoresponse due to the small crystalline size. The tin seleno telluride thin film reflects the loose short rod type aggregates at 10%-50% duty cycle and dendritic structure was formed at deposition of 75% and above. The deposited tin seleno telluride is a p-type semicoductor and the band gap was found to be 1.60 eV with direct transition.

Abstract: The plating parameters for optimizing the wear and corrosion resistance of Ni-TiC composite coatings were selected by orthogonal test, mainly including the TiC particles concentration, current density, duty cycle, frequency and stirring rate. A three-layer BP (Back Propagation) neural network with Lavenberg-Marquardt algorithm was established by MATLAB, which was used to train the network and predicted orthogonal experimental data. In addition, the best parameters combination of the composite coating were predicted and verified by experiments. The results predicted through the proposed BP model are in good agreement with the experimental values, the relative error is small, and the maximum error is less than 3% and the coefficient of determination value is 0.9997.

Abstract: Nickel matrix and Si₃N₄ micron particles were co-deposited on the aluminum alloy by pulse electro-deposition for high temperature performance. Meanwhile, the oxidation resistance was evaluated through the high temperature oxidation test. The phase structure, micrographs and components of the composite coatings were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) together with energy dispersive spectroscopy (EDS) respectively. The results indicated that Si₃N₄ particles were uniformly distributed across the coating and there were no pores and cracks or other defects at the coating/substrate interface. Ni-Si₃N₄ composite coatings are characterized by pyramidal micro-crystallite structure. The thickness of Ni-Si₃N₄ composite coatings were up to 80 μm for 2h. The results also revealed that the Ni-Si₃N₄ composite coatings presented better oxidation resistance than the pure Ni coating and aluminum alloy at high temperature. After oxidation at 673 K for 8h, the oxidation resistance of Ni-Si₃N₄ composite coatings presented the improved oxidation resistance behavior compared to pure Ni and the aluminum alloy, respectively.

Abstract: Mo-Ni coatings were prepared on Ni alloy by pulse electrodeposition method. The effects of current density, electrodeposition temperature, frequency, duty cycle and electrodeposition time on microhardness of Mo-Ni coating were researched, respectively. Microhardness of Mo-Ni coating increases with the increase of current density, electrodeposition temperature, frequency and electro-deposition time in 17.75 A/dm² ~ 19.25 A/dm². 21 °C~ 25 °C, 1000 Hz ~ 5000 Hz and 10 min ~ 20 min, respectively. Microhardness of Mo-Ni coating decreases with the increase of electrodeposition temperature, electrodeposition time and duty cycle in 25 °C ~ 37 °C, 20 min ~ 30 min and 0.5 ~ 0.9, respectively. In the range of current density from 19.25A/dm² to 20.75 A/dm², microhardness of Mo-Ni coating is neariy constant with the increase of current density. When electrodeposition parameters: current density 19.25 A/dm², electro-deposition temperature 25 °C, frequency 5000 Hz, duty cycle 0.5 and electrodeposition time 20 min, microhardness of Mo-Ni coatin is as high as 707.9 HV.

Abstract: Pd-Ag alloy powders were prepared on the stainless steel by pulse electrodeposition. Cyclic voltammetry found the reduction potential of Pd, Ag and Pd-Ag. The composition and morphology of Pd-Ag were investigated by means of SEM, EDS.

Abstract: Nickel-cobalt alloys have broad application prospect for their excellent properties (i.e. high microhardness, strength, abrasion, corrosion resistance and magnetic properties.etc). Nickel-rich Ni-Co coatings were produced on SUS304 substrates by pulse electrodeposition from sulfamate electrolytes with different average current density, pulse frequency, duty cycle and different bath temperature. It is clearly observed that the content of cobalt in the nickel-rich deposits gradually increases from 4.29 % to 25.47 % as the Co2+/Ni2+ concentration ratio increasing from 0.022 to 0.1(the current density applied was 2 A/dm2,bath temperature 25 °C). The Co content increases from 16.98 % to 25.47 % to 30.06 % when the duty cycle ranged from 20 % to 50 % to 60 %.The Co content seems to hardly change when pulse frequency changed from 500 Hz to 1000 Hz. The cobalt content decreases as the growth of the current density. The formation of good Ni-Co deposits with high cobalt content and smooth morphologies can be obtained by reducing current density, increasing bath temperature and pulse duty cycle.

Abstract: Ni-TiN-CeO₂ nanocomposite coatings on 45 steel substrate were prepared by ultrasound-pulse electrodeposition. The effects of process parameters, such as CeO₂ and TiN nanoparticles addition, cathode current density, positive pulse duty cycle and ultrasonic power on the Ni-TiN-CeO₂ nanocomposite electrodeposition process were studied by orthogonal experiments. The nanoparticles contents in the coating were determined, and the surface morphology of the coating was analyzed. The results show that the optimized process parameters are: the CeO₂ particles addition of 40g/l, the TiN particles addition of 15g/l, cathode current density of 4A/dm², positive duty cycle of 20%, and the ultrasonic power of 180W. Under the optimum condition, the desirable Ni-TiN-CeO₂ nanocomposite coatings are prepared with higher particle content and better surface quality.