Codeposition Behavior Research Articles

アンモニア性酒石酸塩浴からの電析Ｎｉ‐Ｍｏ合金の構造と共析挙動

The structure of Ni-Mo alloys electrodeposited from ammoniacal tartrate baths was discussed in terms of their codeposition behavior. The results obtained are as follows:(1) With increasing Mo content in the alloys, the partial current efficiency of Mo first increased and then decreased after a maximum was achieved. This showed the existence of two characteristic alloy compositions, i. e., a Mo content at a maximum partial current efficiency of Mo and one at the upper limit of Mo deposition.(2) Alloys of lower Mo content were found to consist of α-Ni solid solution by X-ray diffraction analysis and the diffraction peaks became broader with increasing Mo content.(3) From SEM observation of the surface appearance of the deposits, the most compact and smooth deposits were found in alloy which gave the maximum partial current efficiency of Mo. With a further increase in Mo content, blackish deposits were observed in the alloy.(4) TEM study also revealed that the main phase of the electrodeposited Ni-Mo alloys was α-Ni. When the Mo content exceeded the value of the maximum partial current efficiency of Mo, the X-ray diffraction patterns of the deposit showed broad and diffuse peaks similar to those from an amorphous phase. However, the alloys were found from TEM observation to consist of α-Ni crystallites smaller than 30nm in diameter and fine particles of MoO2 crystals. This finding supports the multi-step reduction mechanism based on intermediate Mo (IV) compound in the codeposition of Mo with Ni.

電解鉄製造における不純物の共析挙動

Codeposition behaviors of Cu, Cd, Pb, Sn, Ni, Co, Zn and Mo with Fe have been studied in chloride and sulfate baths. The results obtained are as follows:(1) The single deposition of Fe proceeded with significant overvoltage, the degree of which depended on the type of electrolyte and temperature.(2) The codeposition of Cu and Cd with Fe was found to be regular type, resulting in higher contents of these impurities in the deposits than in the baths.(3) The codeposition behavior of Pb from chloride bath was similar to those of Cu and Cd. However, the content of the impurities in the deposits obtained from Pb-containing sulfate bath and Sn-containing chloride and sulfate baths was lowered by the precipitation of Pb sulfate and Sn hydroxide in the baths.(4) The contents of Ni and Co in the deposits showed lower value. This indicates the anomalous codeposition of Ni and Co with Fe, i. e., the preferential deposition of Fe over the wide range of electrolysis condition.(5) In the baths containing Zn2+, the anomalous codeposition in which less noble Zn deposits preferentially occurred. In this case, the codeposition of electrochemically less noble Zn should be considered to produce high purity Fe.(6) Mo content in the deposits decreases with an increase in current density to become less than 1% at higher current densities.

Simultaneous underpotential deposition of lead and thallium on polycrystalline silver-III

Simultaneous underpotential deposition of lead and thallium from a tartrate medium on a polycrystalline silver electrode is reported. Results of cyclic voltammetric investigations of the effects of concentration and sweep rate on the codeposition behaviour are discussed. Further investigations of the codeposition behaviour through voltammetric experiments using programmed potential inputs are described and discussed in terms of formation of a two-dimensional alloy. Finally, the validity of the existing models of electrochemical phase formation has been investigated under the codeposition conditions.

Coemulsion and electrodeposition properties of mixtures of cationic epoxy resin and cationic acrylic resin containing blocked‐isocyanate groups

Abstract2‐Ethylhexanol–half‐blocked‐toluene diisocyanate (2EH‐half‐blocked TDI) was first reacted with 2‐hydroxyethyl methacrylate (HEMA) to prepare HEMA–TDI–2EH monomer containing blocked‐isocyanate groups. This monomer was reacted with butyl acrylate, styrene, and N,N‐dimethylaminoethyl methacrylate to prepare an acrylic copolymer III′ containing blocked‐isocyanate groups and tertiary amine groups. The acrylic copolymer III′ can be mixed with an epoxy–amine adduct IV′, acetic acid, and deionized (D.I.) water to from an electrodepositable coemulsion. The electrophoretic codeposition of the coemulsion and physical and chemical properties of the codeposited film were investigated. The resin composition of film deposited from coemulsion was determined by Fourier transform infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic codeposition behavior. The applicability of this two‐component coemulsion in primer–surface (pricer) electrodepositable paint was also discussed. The results indicate that the deposition yield of cationic acrylic copolymer III is greater than that of cationic epoxy resin IV, i.e., the deposition velocity of III is faster than that of IV. However, resins III and IV can be well codispersed in D.I. water to form stable coemulsion; thus, the resin composition of deposited is almost equal to the resin composition. Moreover, the throwing power of coemulsion is almost equal to that of IV emulsion but greater than that of III emulsion. The optimum resin compositions of coemulsions for obtaining better gel content of deposited films are between 0.65 and 0.8 (III/III+IV, by weight). © 1994 John Wiley & Sons, Inc.

Coemulsion and electrodeposition properties of mixtures of cationic epoxy resin and cationic acrylic resin containing butoxymethylamide groups

AbstractButyl acrylate, styrene, N,N‐dimethylaminoethylmethacrylate, and N‐(n‐butoxymethyl) acrylamide were copolymerized to prepare a cationic acrylic copolymer (I) containing butoxymethylamide groups. This copolymer can be mixed with an epoxy‐amine adduct (II), acetic acid, and deionized (D.I.) water to form a coemulsion containing two cationic resins. The electrophoretic codeposition of the coemulsion and physical and chemical properties of the deposited film were investigated. The resin composition of film deposited from coemulsion was determined by Fourier transform Infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic codeposition behavior. The applicability of this two‐component coemulsion in primer‐surfacer (pricer) electrodeposition paint was also discussed. The results indicate that at any coemulsion resin composition the resin composition of electrodeposited film is almost equal to the coemulsion resin composition. The throwing power of emulsion increases with increasing applied voltage, as expected. However, the throwing power of coemulsion is almost equal to that of the II emulsion but greater than that of the I emulsion. Furthermore, all cured films derived from mixtures of I/II show excellent adhesive strength, good hardness, and high levels of salt spray resistance. © 1993 John Wiley & Sons, Inc.

Simultaneous deposition of Pd and Ag on porous stainless steel by electroless plating

This work investigates the codeposition behavior of palladium and silver on porous stainless steel by means of electroless plating. Although palladium and silver can be deposited independently to a considerable thickness, simultaneous deposition of palladium and silver is passivated by the preferential deposition of silver in an electroless bath containing EDTA as a complexing agent. After effective activation of the substrate by Pd predeposition, Pd and Ag can be successfully codeposited. A combination of XRD and EDX analyses reveals that codeposited Pd and Ag are in separate phases and that small amounts of an amorphous palladium rich phase are also present in the deposited material. Thus a codeposition mechanism of Pd and Ag is proposed. Thermal treatment of as-deposited Pd-Ag films in H 2 atmosphere provides composite Pd-Ag alloy membranes on the porous stainless steel substrate.

Simultaneous deposition of Pd and Ag on porous stainless steel by electroless plating

This work investigates the codeposition behavior of palladium and silver on porous stainless steel by means of electroless plating. Although palladium and silver can be deposited independently to a considerable thickness, simultaneous deposition of palladium and silver is passivated by the preferential deposition of silver in an electroless bath containing EDTA as a complexing agent. After effective activation of the substrate by Pd predeposition, Pd and Ag can be successfully codeposited. A combination of XRD and EDX analyses reveals that codeposited Pd and Ag are in separate phases and that small amounts of an amorphous palladium rich phase are also present in the deposited material. Thus a codeposition mechanism of Pd and Ag is proposed. Thermal treatment of as-deposited Pd-Ag films in HZ atmosphere provides composite Pd-Ag alloy membranes on the porous stainless steel substrate.

Codeposition of α‐Alumina Particles from Acid Copper Sulfate Bath

The purpose of this work is to elucidate the factors affecting the codeposition of α‐alumina particles with copper from an acid copper sulfate bath. The effect of current density and particle concentration in the bath on the amount of codeposited α‐alumina were determined. In order to evaluate the surface‐chemical properties of the particles, the zeta‐potential of α‐alumina particles in the plating bath was determined by means of the streaming potential method. The amounts of adsorbed Cu2+ and from the plating bath were also determined. The amount of codeposited α‐alumina particles was found to be greater than those reported in literature, in spite of the negative zeta‐potential values of α‐alumina. This indicates that the electrostatic interaction between the particles and the cathode is not the essential factor of the codeposition process. It is considered that the amount of adsorbed Cu2+ on the α‐alumina particle plays an important role in the codeposition behavior.

Ｚｎ‐Ｎｉ‐ＳｉＯ２分散めっき鋼板の共析挙動

Zn-based composite plated steel sheets are expected to exhibit better corrosion resistance than zinc- or zinc-alloy-plated steel due to the existence of dispersed particles. It is of importance, therefore, to clarify the codeposition mechanism of the dispersed particles in order to control the plating structure, and thereby control the corrosion resistance. A study was conducted on the electrodeposition behavior of Zn-Ni-SiO2 composite plated steel sheets that were electroplated from an electrolyte containing Zn ion, Ni ion and SiO2 colloid. It was found that the SiO2 content of the plated layers increased rapidly with an increase in the SiO2 concentration in the bath, showing that Guglielmi's two-step codeposition mechanism did not hold in this case. The cross-sectional structure of the plating layer was studied by grow discharge spectrometry (GDS) and transmission electron spectroscopy (TEM). It was found that Zn-7.4wt%Ni-1.6vol%SiO2 composite plating had a double-layered structure: an under layer consisting mainly of Zn-Ni alloy and an outer layer of segregated SiO2 thin film. Zn-12.1wt%Ni-20.5vol%SiO2 composite plating, on the other hand, had a laminar structure, consisting of aggregated layers of SiO2 and Zn-Ni alloy, and Zn-Ni alloy layers. It was concluded that these codeposition behaviors depended on the peculiar properties of SiO2, which adsorbs Ni ions in the bath selectively, and agglomerates at the cathode.

Simultaneous Chemical Vapor Deposition of Boron Nitride and Aluminum Nitride

Two chemically different phases, hexagonal BN and AIN, were simultaneously produced by chemical vapor deposition (CVD) using an impinging jet reactor and the BCl3─AlCl3─NH3─Ar reagent system. The microstructure of the BN + AIN composite coatings was strongly dependent on temperature, pressure, and BCl3 and AlCl3 concentrations. The growth characteristics of BN and AIN in the codeposition system were similar to those expected from the single‐phase deposition processes (i.e., BN‐CVD and AIN‐CVD), except the growth of AIN whiskers was accentuated, and competition between BN and AIN deposition in the composites was suspected to be the cause of less‐crystalline deposits. In both BN + AIN‐CVD and AIN‐CVD, the growth of AIN whiskers became more apparent with increasing pressure or temperature. The codeposition behavior observed experimentally was compared with thermodynamic predictions.

金の電解析出におけるタリウム共析量に及ぼすパルス電流波形の影響

The codeposition behavior of thallium, which acts as a grain refiner in gold electrodeposition, was studied in both DC and pulsed current electrolysis. In jet plating, the maximum current density that produced shiny deposits was the same for both methods, but the codeposition behavior of thallium in gold was quite different. In DC plating, the amount of thallium codeposited in gold increased with greater current density and thallium concentration, but decreased with an increase in the concentration of conductivity salts. In pulse current plating, on the other hand, the amount of thallium codeposited was constant at about 300ppm and independent of these factors. Thus the effect of such pulsed current parameters as pulse duration and waveform were studied in relation to thallium codeposition behavior.It was found that at optimum pulsed current conditions the amount of thallium codeposited in gold was suppressed to about 80ppm. It was also found that periodically reversed current was effective in suppressing the amount codeposited to the same level.The differences in the codeposition behavior of thallium in DC and pulsed current conditions were explained satisfactorily using a diffusion layer model of gold cyanide electrolysis and the grain refining mechanism of thallium proposed by McIntyre and Peck.

Ｚｎ｀２＋´及びＮｉ｀２＋´イオンとＳｉＯ２コロイドの共析挙動

The codeposition behavior of Zn2+, Ni2+ and SiO2 was investigated by a galvanostatic method using colloidal SiO2 (20nm). The SiO2 content of the electodeposits increased with the increase of Ni2+ content in the bath, and the amount of Ni2+ adsorbed on SiO2 particles was greater than the amount of Zn2+ adsorbed on SiO2 in the bath. Ni2+ played an important role on the deposition of SiO2. The relation between the amount of SiO2 in the bath and in the electrodeposit changed in accordance with Guglielmi's theory. Adsorption of the SiO2 on the cathode seems to occur in the first stage of the Zn-Ni-SiO2 electrodeposition process. A part of the SiO2 in the electrodeposit coagulated into larger particles during electrolysis because the pH on the cathode became higher than that of the electrolyte. The surface pH on the cathode during Zn-Ni-SiO2 electrodeposition measured by micro-Sb electrode was about 5-7 at a bath pH of 2, and a current density of 10-20A/dm2. This value coincided with the pH of the coagulation of SiO2. These results indicate that the factors controlling the codeposition of SiO2, Ni2+, and Zn2+ were: 1) adsorption of Ni2+ on the SiO2 in the bath; 2) adsorption of SiO2 on the cathode according to Guglielmi's theory; and 3) coagulation of SiO2 by the increase of pH on the cathode during electrolysis.

硫酸塩浴からのＮｉ‐Ｃｄ異常型合金電着過程

The electrodeposition behavior of Ni-Cd alloys was investigated using sulfate baths. It was found that over a wide range of electrolysis conditions the codeposition behavior of Ni-Cd alloys was anomalous because the Ni content of the alloys was extremely low in comparison with the metal-percentage of Ni in the baths. The Ni content of the alloys increased with increases in the Ni concentration in the baths, current density, pH and temperature, and with a decrease in the sodium acetate concentration in the baths.The polarization curves were measured during the deposition of Ni-Cd alloy and each component metal. In the alloy plating bath, Ni deposition showed significant polarization which brought about the anomalous codeposition while Cd deposition began to occur at around the equilibrium potential of Cd. The high polarization of Ni deposition was observed even in a Ni single bath. Therefore, the anomalous codeposition appearing in the Ni-Cd system is not attributed to the interaction of both ions during their simultaneous discharge, but to the polarization peculiar to single Ni deposition from aqueous solutions.

Neurotransmitters, pathways and circuits as the neural basis of self-stimulation of the prefrontal cortex in the rat

The properties of electrodeposited Ni–Co films produced from electrolyte consisted of nickel sulfamate, cobalt sulfate and boric acid were investigated as a function of Co content in the films. The compositional analysis performed by an energy dispersive X-ray spectroscopy demonstrated that the Co content of the films increases as the cobalt sulfate concentration in the electrolyte increases. The anomalous codeposition behavior was observed for all concentrations. The crystal structure was analyzed using an X-ray diffraction technique. The face centered cubic (fcc) structure was observed in the films containing from 0 at.% Co to 58 at.% Co. For the higher atomic Co contents (64 at.% and 80 at.%), a mixed phase of dominantly fcc and hexagonal closed packed (hcp) structure was observed although the (10.0) and (10.1) hcp peaks had minor intensities in the patterns. Surface micrographs obtained from a scanning electron microscope revealed that the film surface has a rougher appearance as the Co content increases. Magnetic measurements showed that the saturation magnetization gradually increased with increasing Co content of the films. The coercivity, Hc can be controlled by the structural parameters such as average grain size and crystal structure. The results also indicated that the optimum film composition was 28–40 at.% Co since the lower Hc and higher magnetoresistance (MR) values with very smooth or slightly granular surfaces were achieved at this Co content. It is revealed that Co content has an important effect on structural, magnetic and MR properties of the Ni–Co films.

The co-deposition of copper and zinc inclusion in electrodeposition of silver from silver cyanide bath

The co-deposition behavior of a trace of copper and zinc as an impurity in cyanide baths for silver plating was studied by means of a radioactive tracer. The authors selected 64CuCN and 65Zn(CN) 2 as a labelled compound and added it to the cyanide baths for silver plating. Each amount of copper and zinc co-deposited with silver increased with increasing copper and zinc concentration in silver plating baths and temperature. It was found that the co-deposition of copper and zinc depended on cathode potentials and was not diffusion-determining. The co-deposition of copper abruptly increased in the high current density range. In the potential range Cu co-deposition is observed with Cu reversible potential through limiting current of silver deposition, and evolution of hydrogen. At low current density, Cu and Zn co-deposition are saturated at about 6400 Å thickness of electrodeposited silver and occluded in the electrodeposits is not smooth and coarse structure is observed on it.