Increasing Bath Temperature Research Articles

Effect of temperature and pH of ammonium galvanic bath on the properties of Zn-Co alloy coatings

The results of investigations on Zn-Co coatings obtained electrochemically in acidic and neutral ammonium baths are presented. The chemical composition, morphology and surface roughness of received coatings were determined together with the current efficiency. It was found that the coatings morphology depends on the process parameters. In the case of neutral bath the increase of bath temperature resulted in decrease of cobalt contents in the coatings, whereas it was not practically observed for acidic baths. It was also observed that surface roughness of the Zn-Co coatings decreased with the increase of temperature for both types of baths. It was also found that the grain size of coatings obtained in neutral bath depends on pH of bath.

Temperature dependence of the growth of ZnO nanorod arrays by electrochemical deposition

ZnO nanorod arrays were prepared by the electrochemical deposition route on conductive Au/Si substrates. The effect of the bath temperature on the growth of the ZnO nanorod arrays was investigated. With an increase in bath temperature from 30°C to 80°C, the deposited ZnO changed from an amorphous structure to a hexagonal crystal structure. The ZnO nanorod arrays grown above 50°C were dense and vertically well-aligned. Scanning and transmission electron microscopy results showed that the diameter of the hexagon-shaped ZnO nanorod arrays ranged from 100 nm to 180 nm and the length was about 500 nm. On the basis of the characteristics of the ZnO crystal structure and the effect of the bath temperature, the growth mechanism is described.

The effect of bath temperature on the crystallite size and microstructure of Ni–CeO2 nanocomposite coating

Nickel–ceria nanocomposite coating has been synthesized by a pulse electrodeposition technique to investigate the effect of temperature on the microstructure of the composite coating. The experimental result shows that the crystallite size of Ni decreases with the increase of bath temperature up to 45°C, beyond this temperature the crystallite size of Ni again increases. A theoretical formula has been established for evaluating the effect of temperature on the grain size. It has been also found that the co-deposition of ceria in the nickel matrix and hardness value of the nickel-ceria nanocomposite coating increase up to a bath temperature of 45°C, beyond this temperature both these factors decrease.

Coherent excitation-energy transfer and quantum entanglement in a dimer

We study coherent energy transfer of a single excitation and quantum entanglement in a dimer, which consists of a donor and an acceptor modeled by two two-level systems. Between the donor and the acceptor, there exists a dipole-dipole interaction, which provides the physical mechanism for coherent energy transfer and entanglement generation. The donor and the acceptor couple to two independent heat baths with diagonal couplings that do not dissipate the energy of the noncoupling dimer. Special attention is paid to the effect on single-excitation energy transfer and entanglement generation of the energy detuning between the donor and the acceptor and the temperatures of the two heat baths. It is found that, the probability for single-excitation energy transfer largely depends on the energy detuning in the low temperature limit. Concretely, the positive and negative energy detunings can increase and decrease the probability at steady state, respectively. In the high temperature limit, however, the effect of the energy detuning on the probability is negligibly small. We also find that the probability is negligibly dependent on the bath temperature difference of the two heat baths. In addition, it is found that quantum entanglement can be generated in the process of coherent energy transfer. As the bath temperature increases, the generated steady-state entanglement decreases. For a given bath temperature, the steady-state entanglement decreases with the increase of the absolute value of the energy detuning.

Effect of Electroplating Parameters on Microstructure of Nanocrystalline Nickel Coatings

In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin addition on grain size and texture coefficient (TC= I (200) / I (111) ) of the deposits were investigated by X-ray diffraction (XRD). The results showed that in a bath containing 5 g/L saccharin, by increasing the bath temperature from 45°C to 55°C, the grain size decreased, whereas further increase of bath temperature resulted in a contrary effect. By increasing the current density from 10 to 75 mA/cm 2 , both the grain size and TC decreased, while further increase in current density had no significant effect on the grain size. At a given current density, the grain size and TC decreased rapidly by increasing the saccharin content before leveling off at 3 g/L of saccharin. Finally, based on the grain refining the optimum conditions for producing nanocrystalline nickel coating from Watts-type bath have been proposed.

Composition Dependent Magnetic Properties of Ni-Co-P Coated Carbon Nanotubes

Carbon nanotubes were coated with a layer of nickel-cobalt-phosphorus (Ni-Co-P) alloy with different compositions of Ni/Co through electroless plating. The effects of the concentration ratio of Co2+ to Ni2+, bath temperature, and pH on deposition rate are discussed. The prepared carbon nanotubes covered with Ni-Co-P were characterized and analyzed by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and a vibrating sample magnetometer. The results show that the deposition rate reached the maximum when the concentration ratio of Co2+ to Ni2+ is 1 and the pH is 9; the deposition rate increases with the increase of bath temperature. The measurements of the magnetic properties of the obtained carbon nanotubes covered with Ni-Co-P indicate that the magnetic properties greatly depend on the concentration ratio of Co2+ to Ni2+, and the magnetic saturation reaches the maximum value when the Co2+ to Ni2+ ratio is 1. In addition, there are two peaks in the coercivity curve at Co2+ to Ni2+ ratios of 1/2 and 4/1, while the two peaks in the magnetic conductivity curve are located at Co2+ to Ni2+ ratios of 1/4 and 4/1.

Effect of bath temperature on nanocrystalline Ni-polytetrafluoroethylene composite coatings prepared by brush electroplating

Brush electroplated Ni-polytetrafluoroethylene (PTFE) composite coatings with uniform distribution of PTFE particles in the nanocrystalline Ni matrix were prepared by changing the bath temperature. The effects of the bath temperature on the deposition, microstructure and tribological properties of the composite coatings were investigated. Experimental results show that the PTFE content in coatings, deposition rate and the tribological properties trend to increase with increasing bath temperature, and the composite coating prepared at the bath temperature of 40°C reaches a maximum in surface morphology. However, it is difficult to successfully prepare the composite coatings when the bath temperature is above 40°C owing to their poor adhesion to the substrate. Therefore, some measures should be taken when the composite coatings are prepared at the bath temperatures above 40°C.

Influence of processing parameters on regeneration kinetics and morphology of porous cellulose from cellulose–NaOH–water solutions

The kinetics of cellulose regeneration in acetic acid bath from cellulose–8% NaOH–water solutions and gels is studied as a function of gelation conditions, acid concentration and bath temperature. The diffusion coefficient of NaOH from cellulose solution or gel into regenerating bath was calculated. It does not depend either on gelation mode or on acid concentration. On the contrary, cellulose regeneration from non-gelled solutions is slower than from a gel. The increase in bath temperature induces diffusion coefficient increase obeying Arrhenius law. Scanning electron microscopy images of regenerated swollen-in-water freeze-dried cellulose and of the same samples dried in supercritical CO2 show highly porous morphology.

Optical and dielectric properties of junctionlike CdS nanocomposites embedded in polymer matrix

CdS nanocomposites have been grown in a polymer (polyvinyl alcohol) matrix using a simple chemical bath deposition process. Transmission electron micrographs of nanocomposites grown at different solution temperatures revealed the formation of isolated as well as junctionlike structures. X-ray and selected area electron diffraction patterns show that the nanocomposites are polycrystalline with cubic CdS phase. Optical band gaps of nanocomposite films are found to decrease (3.26–2.86eV) with the increase in bath temperature from 70to90°C. Photoluminescence spectra show strong green emission attributed to the Cd2+ or Cd+ ion-related recombination via moderately deep trap states. The nanocomposites show an enormous enhancement of dielectric constant in polyvinyl alcohol matrix over a frequency range of 40Hz–10MHz.

Low-Internal-Stress Nickel Multiwalled Carbon Nanotube Composite Electrodeposited from a Sulfamate Bath

Nickel multiwalled carbon nanotube (MWCNT) composite plating was studied using a sulfamate-based bath. The effects of additives, current density, and bath temperature on the microstructure of Ni-MWCNT composite films were examined. The content of MWCNTs and internal stress of the composite films were also investigated. The addition of both sodium saccharin dihydrate and 2-butyne-1,4-diol caused a decrease in the voids formed in the composite films. The amount of voids in the composite films increased with increasing bath temperature. A Ni-MWCNT composite film with 0.4 mass % MWCNTs, no significant voids, and low internal stress was fabricated by adjusting the bath composition and electrodeposition conditions.

Electrodeposition and characterization of CdSe semiconductor thin films

The electrodeposition of cadmium selenide alloy on glassy carbon and gold electrodes has been studied by electrochemical techniques. Potentiostatic I-t transients were recorded to obtain the nucleation mechanism, while cyclic voltammetry was used to characterize the system. Structural information on the electrodeposited layers was obtained by X-ray diffraction. The experimental results clearly show that the deposition of cadmium selenide alloy on glassy carbon and gold electrodes is a diffusion-controlled process. The nucleation is progressive, and the number of nucleation sites decreases with increasing bath temperature. The deposition of CdSe alloy results in well-defined crystals with hexagonal shape. The films were characterized by optical absorption and electrical resistivity measurements. Films showed a direct band gap of 3.56 eV.

Effects of Growth Process on Structural and Optical Properties of Chemical Bath Deposition Cadimium Sulfide Thin Films

Hexagonal CdS thin films with a strong (002) orientation were successfully prepared by chemical bath deposition (CBD) using the reaction between CdCl2 and CS(NH2)2. A commonly available CBD system was successfully modified using a wetting agent (polyglycol) without agitation. Studies were performed to determine the effects of bath temperature on the properties of the films, such as optical transmission, surface morphology and the structure property. It was found that bath temperature plays a vital role in the quality of the CdS films. The increase in bath temperature improved the surface morphology of the CdS films and also decreased the number of pinholes on the films. The optimum bath temperature was 85 °C.

Influence of electroplating conditions on magnetic properties of Fe-36wt. % Ni alloy film

A Fe-Ni soft magnetic film was prepared in sulphate solution by electroplating. The influences of the molar ratio of n [Fe 2+]/ n [Ni 2+], current density, bath temperature, pH and L-ascorbic acid concentration on magnetic properties of Fe-Ni alloy film were investigated. The results show that the saturated flux density (BS) of the film increases initially and decreases after it reaches the specific value with the increase of n [Fe 2+]/ n [Ni 2+] molar ratio, current density, bath temperature and pH. However, the relationship between L-ascorbic acid concentration and B s keeps linear. It is observed that the coercive force ( H c) is enhanced with the increase of n [Fe 2+]/ n [Ni 2+] molar ratio, current density and pH. By comparison, when the bath temperature increases, H c always decreases. With the increase of L-ascorbic acid concentration, the coercive force increases initially and then decreases.

Crystallite size dependence of band gap energy for electrodeposited ZnO grown at different temperatures

Zinc oxide thin films were grown by potentiostatic electrodeposition at different bath temperatures (62–89 °C, and −1 V vs. SCE) from a 0.1 M Zn(NO3)2 solution. X-ray diffraction (XRD) shows there is crystallite size enlargement as bath temperature increases. The band gap energy values, determined from optical reflectance spectra, are between 3.2 and 3.3 eV, decreasing when the bath temperature increases. A quantum size effect is deduced from the correlation between the band gap energy and the crystallite size.

エリソルビン酸を還元剤とする無電解金めっき

The purpose of this investigation was to study electroless Au plating from a sulfite/thiosulfate complex bath (0.015M Na3[Au(SO3)2]+0.1M Na2S2O3+0.4M Na2SO3+0.05M C6H7O6Na+0.18M KOOCCH(OH)CH(OH)COONa) using erythorbic acid as the reducing agent. Deposition rates by autocatalytic reaction and displacement reaction were increased with increasing the concentration of erythorbic acid. The deposition rate by autocatalytic reaction was increased with increasing bath temperature. The deposition rate by displacement reaction was suppressed by the addition of benzotriazole (BTA), di-sodium ethylenediaminetetraacetate (EDTA) and ethylenediamine (en). Electroless Au film which shows a good characteristics in the solder joint strength was obtained from a bath containing BTA, EDTA and en.

Liquid metal corrosion of 316L, Fe3Al, and FeCrSi in molten Zn-Al baths

Corrosion tests of 316L and two intermetallic compounds Fe3Al and FeCrSi in industrial Galvanizing (Zn-0.18Al), GALFAN (Zn-5Al), GALVALUME (Zn-55Al), and Aluminizing (Al-8Si) baths and lab-scale static baths were conducted. In on-line tests in industrial hot-dip baths, 316L steel shows better corrosion resistance than Fe3Al in Galvanizing, GALFAN, and GALVALUME baths. The corrosion resistance of 316L and Fe3Al is similar in Aluminizing bath. In static tests, FeCrSi shows the best corrosion resistance in pure Zn, Zn-55Al, and Al-8Si baths. The corrosion resistance of 316L is better than that of Fe3Al. In Zn-5Al bath, 316L shows no thickness loss after the test. For the same bath composition, the corrosion rates of the alloys in industrial baths are higher than those in static baths. Bath temperature and chemical composition play important roles in corrosion and intermetallic layer formation. Increasing bath temperature accelerates the corrosion process and changes the nature of intermetallic layers. A small amount of aluminum reduces the corrosion process by reducing the activity of Zn and forming inhibition layer. However, after aluminum content reaches the critical point, the dominant corrosion process changes from Zn-Fe reaction to Al-Fe reaction, and, consequently, the corrosion process accelerates by increasing aluminum content in the bath.

Effect Of Ethanolic Extract From <i>Elaeophorbia drupifera</i> Leaves On The Gastrointestinal Smooth Muscle Of The Rabbi

The crude extract from E. drupifera leaves was prepared using standard methods. The rabbit intestine was removed and separated into three segments (duodenum, jejunum and ileum). About 3-4cm of each segment was mounted in an organ bath containing Tyrode solution at 37 ± 1oC. The spontaneous and rhythmic contractions were recorded and the effects of the crude extract (2-g/ml) on the tissue responses were investigated. The effect of Ca2+ concentration and temperature of the bathing fluid were also studied. From the results, the extract (2-300g/ml) increased the amplitudes of contractions in a dose-dependent manner. However, regional differences occurred in the responsiveness of the tissue preparations. The ED50 values were found to be 25.12, 44.67 and 15.85 μg/ml for the duodenum, jejunum and ileum respectively. Certain conditions such as calcium availability and increase in bath temperature favoured the action of the extract on the tissue preparations. Drugs like mepyramine or methysergide failed to influence the action of the extract. However, the extract-induced contractions were prevented or blocked by noradrenaline or atropine sulphate. The contractions were however ameliorated by the addition of acetyleholine or neostigmine to the bath solution. From the results, it is likely that the extract causes increased contractions of the tissue preparation via acetylcholine-like agent, which stimulates the muscarinic cholinoceptors. Key words: E. drupifera, extract, leaves, intestinal contractions, increase, cholinergic. Nigerian Journal of Physiological Sciences Vol.19(1&2) 2004: 60-68

Kinetics of diffusion in polyacrylonitrile fiber formation

AbstractA H2O/dimethyl sulfoxide (DMSO) mixture was used as the coagulation bath of the wet‐spun process for polyacrylonitrile fibers. Diffusion behaviors of coagulate and solvent of the protofibers were studied. Diffusion coefficients of H2O and DMSO of the protofibers, prepared by acrylonitrile (AN) homopolymers, were also determined. It was found that diffusion coefficients of H2O and DMSO in the protofibers prepared by AN homopolymers, synthesized by DMSO solution polymerization, are highest compared with those of AN homopolymers synthesized by H2O/DMSO mixture suspension polymerization and aqueous suspension polymerization. With increasing polyacrylonitrile concentration in the dope, diffusion coefficients of H2O and DMSO decreased continuously. Diffusion coefficients of H2O and DMSO increased concomitantly with increasing bath temperature, but the changes of diffusion coefficient values were less prominent when the temperature increased beyond 60°C. When DMSO concentration in the coagulation bath was 55 wt %, the values of diffusion coefficients of H2O and DMSO were minimal. Diffusion coefficients increased with increasing jet stretch minus ratio. When the protofiber radius was increased, there was a corresponding increase of diffusion coefficients of H2O and DMSO. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1529–1533, 2005

Dynamics of many particles in the urn model

We study the behavior of many particles moving in the 2-urn and 3-urn systems driven by a stochastic heat bath. The velocities and the positions of the particles are calculated through noise activated 1-D Langevin function. We find the time in which the system is in equilibrium becomes longer than the time in which the system is in non-equilibrium as the bath temperature increases. The velocity distribution of the particles is always Gaussian. The effective temperature T2 characterizing non-equilibrium state obeys the power law with the restitution coefficient r.

Influence of growth process on the structural, optical and electrical properties of CBD-CdS films

The hexagonal cadmium sulphide (CdS) thin films with strong (002) orientation are successfully prepared by chemical bath deposition (CBD) technique using the reaction between CdCl 2 and CS(NH 2) 2. Especially, polyglycol is used to modify the CBD system without magnetic agitation. The influence of bath temperature on the properties of the CdS films such as optical transmission, surface morphology and the structure is researched. The results show that polyglycol can flatten the films and diminish the pinhole. X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests verify that the deposited CdS films presented a hexagonal structure and no secondary or mixed phases are found. A preferential columnar growth parallel to the substrate edge is also observed. It is found that the bath temperature plays a vital role on the quality of the CdS films. The increase of bath temperature improves the surface morphology of the CdS films and also diminishes pinholes on the films. The optimum bath temperature is 85 °C. The band gap calculated from transmission spectra is about 2.56–2.336 eV.