Magnetohydrodynamic Effects in Mixed Convection Copper-Water Nano Fluid Flow at Lower Stagnation Point on a Sliced Sphere

The study of simulation and applications of mathematics in fluid dynamics continues to grow along with the development of computer science and technology. One of them is Magnetohydrodynamics (MHD) which is closely related to its implementation in engineering and industry. And given the importance of magnetic fluid flow has attracted researchers to study and explore its benefits and uses in the industrial field, especially in convective flow and heat transfer processes. This paper therefore considers mathematical modeling on mixed convection MHD viscous fluid flow on the lower stagnation point of a magnetic sliced sphere. The study began with transforming the governing equations which are in dimensional partial differential equations to non-dimensional ordinary differential equations by using the similarity variable. The resulting similarity equations are then solved by the Keller-Box scheme. The characteristics and effects of the Prandtl number, the sliced angle, the magnetic parameter, and the mixed convection parameter are analyzed and discussed. The results depicted that the uniform magnetic field produced by Lorentz force and slicing on the sphere act as determining factors for the trend of nano fluid movement and controlling the cooling rate of the sphere surface. In addition, the viscosity depends on the copper particle volume fraction.

Surface Texturing Behavior of Nano-copper Particles under Various Copper Salts System during Copper-assisted Chemical Etching

In this work, the effects of different copper salts on the etching behavior of n-type monocrystalline silicon wafers were detailedly studied by Cu-assisted chemical etching method. Firstly, the inverted pyramid, inverted pyramid-like and oval pit texturing structures were obtained by HF/H2O2/Cu(NO3)2, HF/H2O2/CuSO4 and HF/H2O2/CuCl2 etching systems. Then, the evolution of copper particles deposition behavior was studied to reveal the influencing mechanism of different anion species, the textured wafer surfaces were characterized by scanning electron microscopy (SEM) and ultraviolet-visible (UV) spectrophotometer, the etching rate, silicon wafer thinning and the deposition amount of copper particle was systematically analyzed. We conclude that the binding force between anion and cation, the oxidation of anions and the formation of complex groups [CuCl2]− lead to great difference in the deposition behavior of copper, resulting in different etching morphology and etching rate. The moderate size copper particles deposited from HF/H2O2/Cu(NO3)2 system make that the etching process is mild and the anisotropic etching ability can fully demonstrated, and the regular inverted pyramid structures can be formed under low thinning of silicon wafers. This work will provide guidance for controllable preparation of inverted pyramid structure and future application in high efficiency solar cells.

The Network Structure Formation of Cu-CNTs Composites During Multi-Directional Forging Process and its Mechanical Properties

Cu–[Formula: see text] CNTs composites ([Formula: see text], 1, 2, 3 vol.%) were successfully prepared using a combination of pre-treatment, powder metallurgy and multi-directional forging processes, which provides a solution for the industrial manufacture of the composites with network CNTs structures. During the multi-directional forging process, the CNTs in the composites were distributed in a network under the synergy of metal flow and copper particle squeeze. Compared with other structure modes, the network CNTs can effectively carry and transfer loads resulting in the promotion of mechanical properties (such as, the tensile strength approximately 1.5 times higher than those of composites with the same volume fraction without network structure). The composite with 2 vol.% CNTs had the highest elongation in this experiment (41%), which is about 5 times higher than the composites with other CNTs distribution patterns. At a low CNTs content level (1[Formula: see text]vol.%), a complete load transfer network cannot be formed, resulting in a relatively insufficient mechanical properties of the composites. As the content level is exceeded (3vol.%), it caused significant agglomeration of the CNTs, which lead to fracture in the agglomerated CNTs and elongation degradation of the composites.

Development of LDPE Crystallinity in LDPE/Cu Composites

This chapter summarizes the study of the filler (ie copper) effect on LDPE phasic composition in LDPE/Cu composites prepared in solution. During this research work, a particular effort is focused on the use of DSC under non-standard conditions. Therewith, the presence of copper microparticles has a great effect on the network phase than on the crystalline long-range-order phase of LDPE structure. Furthermore, LDPE phasic composition in absence and presence of copper microparticles is investigated by FTIR spectroscopy followed by a spectral simulation of the band that appeared at 720 cm−1 corresponding to the CH2. Anywise, the two-phase model confirmed that no variation is observed of LDPE phase composition for all copper contents into LDPE/Cu films. However, with the three-phase model the orthorhombic phase fraction was found to be constant compared to the fraction of amorphous and that of network phase were found to increase and decrease respectively with increase in the copper particle load in the film. Overall, the thermal and structural behavior of LDPE in presence of copper particles allows this type to be used as phase change materials (PCMs) by adding a paraffin fraction in the LDPE/Cu composite. An update of the most relevant work carried out in the field of phasic characterization of polyethylene is presented in this chapter.

Copper-Polyurethane Composite Materials: Particle Size Effect on the Physical-Chemical and Antibacterial Properties

In this work, thermoplastic polyurethane (TPU) composites incorporated with 1.0 wt% Cu particles were synthesized by the melt blending method. The effect of the incorporated copper particle size on the antibacterial, thermal, rheological, and mechanical properties of TPU was investigated. The obtained results showed that (i) the addition of copper particles increased the thermal and mechanical properties because they acted as co-stabilizers of polyurethane (PU) (ii) copper nanoparticles decreased the viscosity of composite melts, and (iii) microparticles > 0.5 µm had a tendency to easily increase the maximum torque and formation of agglomerates. SEM micrographics showed that a good mixture between TPU and copper particles was obtained by the extrusion process. Additionally, copper-TPU composite materials effectively inhibited the growth of the Gram-negative Escherichia coli and the Gram-positive Staphylococcus aureus. Considering that the natural concentration of copper in the blood is in the range of 0.7–0.12 mg/L and that the total migration value of copper particles from TPU was 1000 times lower, the results suggested that TPU nanocomposites could be adequately employed for biomedical applications without a risk of contamination.

Study into the effect of sodium lignosulfonate, anionic surfactants and their mixtures on the rate of copper ion cementation by zinc

The article focuses on the effect of sodium lignosulfonate (LS), anionic surfactants (sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate (SDBS)), and their mixtures on the rate of copper cementation by zinc. The results obtained demonstrate a decrease in copper cementation rate with the increasing LS and SDBS concentrations. There was also excessive zinc consumption for copper ion cementation noted due to LS and SDBS anion adsorption on positively charged zinc cathodic areas of the cementing agent and the precipitate. This led to a decrease in the rate of copper particle nucleation, energy consumption for forming new copper nucleation centers, and conditions for hydrogen overpotential reduction. In addition, rising temperature led to a decrease in zinc consumption in the presence of LS. Surfactants under investigation may be ranked by the negative impact on copper ion cementation in an ascending order as follows: SDS < SDBS < LS. LS + SDS mixture testing showed its irregular effect on copper cementation rate at test temperatures. Experiments with LS and SDBS mixtures demonstrated a linear decrease in copper ion cementation rate with increasing SDBS concentration and simultaneously rising zinc consumption. Due to the negative impact of investigated reagents discovered, we proposed a method for removing organic impurities from solutions using multilayered aluminosilicates modified by cationic surfactants. The results obtained indicate the high effectiveness of organic impurity removal from solutions providing for a 50 % increase in cementation rate in the presence of LS + SDBS mixture together with a decrease in zinc consumption.

Hydrophilic Coating of Copper Particle Monolayer Wicks for Enhanced Passive Water Transport

Passive water transport through thin-surface wicks made of heat conducting material is important for developing thermal management devices such as heat pipes and spreaders. In this study, we demonstrated the hydrophilic coating of a Cu particle monolayer wick for enhanced water transport. We fabricated a Cu particle monolayer using Cu powder with a nominal particle diameter of 100 μm and determined the particle size distribution using scanning electron microscopy (SEM). We observed a remarkable change in the water contact angle on the application of a hydrophilic coating, which demonstrated the enhanced passive water transport. The elemental mapping of Cu, O, and Si obtained by electron probe microanalysis confirmed the deposition of the SiO2-based coating material on each Cu particle. Although the Cu particles were only partially covered by SiO2, a remarkable enhancement in wettability was achieved. Finally, we conducted a rate-of-rise experiment to quantitatively characterize the water transport performance of the coated Cu particle monolayer. Thus, we propose hydrophilic coating as a simple and effective method to enhance passive water transport through Cu particle monolayer wicks.