Influence of Double-Pulse Electrodeposition Parameters on the Performance of Nickel/Nanodiamond Composite Coatings

In this study, using 45# carbon steel as the substrate, a first experimental analysis was carried out on the polarisation behaviour of different component wattage plating solutions in order to determine the reasonable content of nanodiamond particles in a nickel/nanodiamond composite plating solution. Secondly, the effect of double-pulse forward and reverse duty cycle and reverse working time on the performance of nickel/nanodiamond composite plating was then investigated by testing the thickness, hardness and surface roughness of the composite plating and observing the surface micromorphology. The experimental results show that, when the content of nanodiamond particles in the plating solution is 5 g/L, the anti-pulse working time, forward and reverse pulse duty cycle of the double-pulse plating parameters are 20, 0.3 and 0.2 ms, respectively, and the composite plating layer prepared by double pulse has good comprehensive performance. This research work provides technical support for the optimisation of process parameters for the preparation of nickel/nanodiamond composite coatings by double-pulse electrodeposition.

Aperture Ratio Improvement by Optimizing the Voltage Slope and Reverse Pulse in the Driving Waveform for Electrowetting Displays

Electrowetting display (EWD) performance is severely affected by ink distribution and charge trapping in pixel cells. Therefore, a multi structural driving waveform is proposed for improving the aperture ratio of EWDs. In this paper, the hysteresis characteristic (capacitance–voltage, C-V) curve of the EWD pixel is tested and analyzed for obtaining the driving voltage value at the inflection point of the driving waveform. In the composition of driving waveform, a voltage slope is designed for preventing ink dispersion and a reverse pulse is designed for releasing the trapped charge which is caused by hysteresis characteristic. Finally, the frequency and the duty cycle of the driving waveform are optimized for the max aperture ratio by a series of testing. The experimental results show that the proposed driving waveform can improve the ink dispersion behavior, and the aperture ratio of the EWD is about 8% higher than the conventional driving waveform. At the same time, the response speed of the driving waveform can satisfy the dynamic display in EWDs, which provides a new idea for the design of the EWD driving scheme.

Numerical study of the effects of cartridge shape on the reverse pulsed flow cleaning of pleated cartridge filters

Patchy cleaning is one of the principal factors resulting in the reduction of the efficiency and quality of reverse pulse-jet cleaning as well as the service lifetime of filtration units. To resolve the above issues, a new pleated cartridge shape was introduced in this study to improve the cleaning efficiency and quality of pleated filter cartridges. To calculate the transient flow and pressure fields for a simple filtration system with one filter cartridge in the reverse pulse-jet cleaning process, an unsteady computational fluid dynamics model was developed via the commercial computational fluid dynamics software of ANSYS CFX. The transient static pressure fields for filter cartridges under four different pleated cartridge shapes were studied. The conventional cylindrical cartridge was selected as the base-model of filter cartridge and contrasted with other three cartridge shapes. It was found that the convergent–divergent cartridge was able to effectively improve the cleaning performance without the increase of tank pressure. Different pleated cartridge shapes are expected to be able to redistribute the pressure drop across the porous media along the filter height and to improve the flow behavior after pulsing gas releasing from the nozzle. For convergent–divergent cartridge shape, the peak pressure on the inner surface of porous media has an obvious increase and the peak pressure arriving time is earlier than other cases. It shows that the reverse flow has much more competence to remove the dust powder or cake from the porous media. At the same time, the area-averaged pressure drop at the bottom section of the filter has an increase of 50% under the cartridge with a convergent–divergent shape compared to that with a cylindrical shape. It is considered to enhance the cleaning mechanical stress at the bottom section of the filter cartridge. The better cleaning performance was observed in the medium, with 150% increase compared to that with a cylindrical shape. Furthermore, the cleaning performance gets improved because the value enhances on the top section. The redistribution of pressure drop observed is mainly because the special geometric construction of pleated cartridges compresses the flow on the medium and produce higher pressure drop there. Further studies indicate that the improved cleaning performance was observable under the consideration of the tank pressure reduction and variation of media permeability during each cleaning phase, and the change of pleated cartridge shapes can also improve the cleaning performance when combined with other improvement methods.

Capacitive performance of vertically aligned reduced titania nanotubes coated with Mn2O3 by reverse pulse electrodeposition

Mn2O3 was coated onto reduced titania nanotubes by reverse pulse electrodeposition, showing smooth and homogenous deposits without covering the opening of the nanotubes.