Search

CuxZn1−x alloy films were electrodeposited from non-cyanide sulphate solutions. Solution zinc ion concentration was varied, while that of copper was kept constant. Cyclic voltammetry studies from solutions showed that change in zinc ion molarity causes differences in electrolyte characteristics and resulting films. Morphology, elemental composition and phase structures of electrodeposited samples were characterised using SEM, EDS and XRD, respectively. Additionally, resistivity measurements were carried out on films using the four-point probe method. Results show that change of solution zinc concentration affects morphological, elemental and structural properties of deposited films, which consequently results in different electrical resistivity behaviour. [ABSTRACT FROM AUTHOR]

The present work reports on electropolymerisation of aniline onto AISI 4140 steel substrate at room temperature in oxalic acid media by the potentiodynamic electrodeposition method. The effect of coating current density on the morphology of conductive polymer films and their corrosion behaviour has been investigated. The electrolyte solution comprised 0.1 M aniline + 0.3 M oxalic acid. The effects of deposition current density changes (0.1, 0.2, 0.3, 0.4 and 0.5 mA cm−2) on the films were investigated. The PANI film was characterised using cyclic voltammetry and optical microscopy; it was covered with a dark green-yellow homopolymer film of strongly adherent homogeneous characteristic. The corrosion behaviour of steel electrodes with and without polyaniline (PANI) film in 3.5 wt-% NaCl solution was investigated through anodic polarisation curves. The results indicated that the PANI coating obtained under 0.2 mA cm−2 was the most corrosion protective. [ABSTRACT FROM AUTHOR]

A series of Zn doped copper materials were investigated upon their crystal and electronic structure with the general formula Cu1-xZnx. CuZn alloys were produced via electrodeposition method. Galvanostatic deposition was preferred for the deposition. Crystal properties of the samples were studied via X-ray diffraction (XRD) patterns and supported by the X-ray absorption fine structure spectroscopy (XAFS) data. According to the crystal structure analysis, crystal geometries of the substituted samples were mainly determined in bcc cubic. The study has revealed that, low amount of Zn substitution (0.1M) are inactive in the molecular interplays and treated as an impurity in fcc copper environment. However, higher Zn concentrations (> 0.1 M) have built bcc structure under the influence of the highly overlapped 4p levels wavefunctions of the neighbouring Cu and Zn atoms. Thus, 0.1 M zinc substitution has been determined as a threshold of the phase transition from fcc to the bcc structure. [ABSTRACT FROM AUTHOR]

Thin film brass alloys were galvanostatically electrodeposited from non-cyanide citrate solutions. Aqueous sulphate solutions were used as deposition medium. It was aimed to understand the effect of ultrasonication of the solutions before electrodeposition process. Ultrasonication was not applied during deposition. This method was utilized to change solution characteristics, by applying high energy via cavitation mechanism, which would result in changes in resultant film properties. X-ray diffraction technique was used to investigate phase formation in samples. Moreover X-ray diffractograms were also used to calculate grain size values. Cu and Zn elements were codeposited successfully to form brass alloys. When phase formations in the samples were compared to each other, it was concluded that although there are small differences between X-ray diffractograms of samples, ultrasonic treatment before electrodeposition is not an effective way to alter phase characteristics of CuZn alloy samples, since all samples have shown similar X-ray diffraction graphs. Grain size is found to get smaller with presence of ultrasonication, extending ultrasonication time caused only small random changes in grain size. [ABSTRACT FROM AUTHOR]

Copper zinc alloys were electrodeposited in the form of thin films. Electrodeposition process was carried out in non-cyanide aqueous medium, under constant current. Effect of pre-deposition ultrasonication of solution was investigated. In other words ultrasonic treatment was applied only before the electrodeposition. Solutions were subjected to high-energy ultrasonication for increasing times. Cyclic voltammetry was used to understand changes occurring due to duration of ultrasonication. No ultrasonication was applied during deposition. Atomic composition of resultant films were revealed by MP-AES. It was found that implementation of ultrasonic treatment before electrodeposition affects CV characteristics, when compared to non-ultrasonicated solution. Atomic composition of fabricated samples were found to be close to each other, some of them showing more deviation. [ABSTRACT FROM AUTHOR]

Cobalt-Nickel alloys have been widely used for decoration, in magnetic recording devices and corrosion resistance applications, etc. In this study, the influences of cobalt amount in electrolyte on the magnetic and structural properties of the electrodeposited Co-Ni alloys were investigated. An electrolyte solution, consisting of cobalt sulfate, nickel sulfate, nickel chloride and boric acid, was used in electrodeposition. The electrochemical investigation of Co-Ni alloys was completed using cyclic voltammetry and galvanostatic studies. The morphological and structural analyses of the alloys were performed using inductively coupled plasma, scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer techniques. The effect of cobalt concentration on the magnetic properties, phase structure and grain size of the alloys was investigated. Magnetic hysteresis results indicate that the amount of the cobalt content in the electrolyte has a strong influence on the ferromagnetic behavior of fabricated alloys. Results of the study show that changing the electrodeposition parameters, such as composition of electrolyte solution, allows to fabricate alloys with different properties. [ABSTRACT FROM AUTHOR]

Background: Two unique biomarkers, soluble form of the urokinase-type plasminogen activator receptor (suPAR) and neopterin, play a crucial role in inflammatory processes. This study aimed to reveal whether it is possible to utilize these biomarkers in predicting tumor prognosis in patients with lung cancers.

Zinc-iron alloy plating (ZnFe) was successfully deposited on AISI 4140 steel applying cyclic voltammetry technique. Polyaniline (PANI) film was synthesized with cyclic voltammetry technique from 0.10 M aniline containing 0.30 M oxalic acid solution on zinc-iron plated carbon steel (AISI4140/ZnFe) electrode. ZnFe film was characterized by scanning electron microscopy and X-ray diffraction technique. The corrosion behaviour of zinc-iron deposited carbon steel electrodes with and without PANI film in 3.5% NaCl solution was investigated with polarization curves. Effect of pH and current density on the synthesis of the aniline was also examined. The results showed that PANI coating led to decrease of the permeability of metallic plating. The PANI homopolymer film provided an effective barrier property on zinc-iron coating and a remarkable anodic protection to substrate. ZnFe particles had more homogeneous, smooth prismatic structure. It is suggested that ZnFe/PANI deposits produced in the bath applying 0.1 mA/cm² current density probably offer bigger protection to the steel substrate. [ABSTRACT FROM AUTHOR]

Blanking operation is widely used to cut sheet or plates by a shearing process between punch and die. The process of shearing and the conditions of the sheared surface are influenced by the punch, the die, the speed of punching, the clearance between the punch and the die. In this study, effects of high speed blanking on surface quality and corrosion properties of mild steel St37 shear surface have been investigated. The work presented in this paper aims at evaluating the shear surface quality improvements of the St37 resulting from the use of high energy rate forging machine. The appraisal is based on criteria related to surface accuracy and corrosion resistance characterization. For this purpose, St37 mild steels were cut using three different punch speeds hydraulic presses at nearly qua-sistatic, conventional mechanical presses at low punch velocity (0.2 m/s) and high energy rate forging machine at high punch velocity (10 m/s), for different die clearances (4.5%-6% of sheet thickness). After accelerated corrosion tests, blanks were performed in conjunction with scanning electron microscopy technique to study the cutting process of the blanks at room temperature. In fact, by using high energy rate forging machine, a reduction of more than 25% of the surface roughness (Ra) was realized and better resistance to stress corrosion cracking and pitting corrosion was noticed. It was observed that the corrosion resistance of the high energy rate forging-cut specimen was better than that of the hydraulic-cut and mechanical-cut specimens. [ABSTRACT FROM AUTHOR]

In this work, the Zn–Co coatings were synthesized on AISI 4140 steel and aluminum plates by using potentiostatic electrodeposition technique in sulphate-based acidic baths with 0, 20, 40 and 60 g l-1 of borax pentahydrate, as additive. The effect of borax pentahydrate on the microstructure of the samples was observed using scanning electron microscopy and X-ray diffractometer. The deposition process was investigated by cyclic voltammetry. The effect of borax pentahydrate on the corrosion resistance of the samples was studied by potentiodynamic polarization technique. The results have demonstrated, that the addition of borax pentahydrate was in favor of the growth of grains. The morphology of pyramidal islands on the surface was changed to a more flat structure. The results have also demonstrated that the effect of borax pentahydrate was not monotonous. With increasing concentration, the corrosion potential was at minimum and the charge transfer resistance Rt was at maximum for the sample obtained from the bath with 60 g l-1 of borax pentahydate, indicating that this sample showed the best corrosion resistance. It was found that current density first decreased and than increased, due to adsorption of a complex of borax pentahydrate and/or changes in the morphology, however, the initial deposition potential was not affected. The addition of borax pentahydrate to the bath led to formation of the best Zn–Co deposits, composed of coalesced globular fine grains, smaller than ≈2 μm in diameter. In addition, all of the studied Zn–Co deposits consisted of η phases. It is suggested that Zn–Co deposits produced in the bath containing 60 g l-1 of borax pentahydrate probably offer sacrificial protection to the steel substrate. [ABSTRACT FROM AUTHOR]

Neural Networks (NN) and Genetic Programming (GP) were used as a new method for formulation of grain size of electrodeposited Cu1-xZnx alloys as a function of Zinc and Copper content both electrolyte and the alloy films produced by electrodeposition technique. To predict grain size a great number of different expression models genetic programming and neural network were conducted. Each model differs from the other with their linking function, number of genes, head size, and chromosomes. To generate databases for the new grain size formulations, testing and training sets in total of 134 samples were selected at different Zn and Cu ratios of components. 6 different input parameters were selected and the output parameter was grain size of the electrodeposited Cu-Zn alloys. The testing and training sets consisted of randomly selected 106 and 28 for the proposed models. All results in the models indicated an applicable performance for predicting grain size of the alloys and found reliable. The predicted model showed that all of the input parameters effected on the resulting grain size. The NN and GEP based formulation results are compared with experimental results and found to be quite reliable with a very high correlation (R2 = 0.995 for GEP and 0.999 for NN). [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) was successfully deposited by means of cyclic voltammetry technique from 0.10 M aniline containing 0.30 M oxalic acid and 1 g/l H3BO3 solution on AISI 4140 steel electrode. In this investigation nominate scan rates 25, 50, 75, and 100 mV/s have been examined. PANI film was characterized using optical microscope; it was covered with a dark green-yellow homopolymer film of strongly adherent homogeneous characteristic. The corrosion behaviour of the steel electrodes with and without PANI film in 3.5% NaCl solution was investigated through anodic polarization curves. The results indicated that PANI coating led to decrease of the permeability of metallic plating. The PANI homopolymer film provided an effective barrier property and a remarkable anodic protection to substrate. [ABSTRACT FROM AUTHOR]