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Öğe A comparison of genetic programming and neural networks; new formulations for electrical resistivity of Zn-Fe alloys(Springer Heidelberg, 2013) Karahan, Ismail Hakki; Ozdemir, Rasim; Erkayman, BurakIt is difficult to automatically solve a problem in a systematic method without using computers. In this study, a comparison between Neural Network (NN) and genetic programming (GEP) soft computing techniques as alternative tools for the formulation of electrical resistivity of zinc-iron (Zn-Fe) alloys for various compositions is proposed. Different formulations are supplied to control the verity and robustness of NN and GEP for the formulation to design composition and electrolyte conditions in certain ranges. The input parameters of the NN and GEP models are weight percentages of zinc and iron in the film and in the electrolyte, measurement temperature, and corrosion voltage of the films. The NN- and GEP-based formulation results are compared with experimental results and found to be quite reliable with a very high correlation (R (2)=0.998 for GEP and 0.999 for NN).Öğe Effect of Citrate-Based Bath pH on Properties of Electrodeposited Cu-Zn Coating on an Aluminum Substrate(Springer, 2024) Ozdemir, Rasim; Unal, Ersin; Karahan, IsmaIl HakkiIn this study, Cu-Zn alloys were deposited in citrate-based electrolytes on aluminum substrate by electrodeposition method. The effect of bath pH variation on the properties of the obtained Cu-Zn alloy coatings was investigated. The electrochemical behavior of the citrate-based baths and the crystalline structure, surface morphology and elemental content, electrical resistivity and thermal behavior of the alloy coatings were analyzed. According to the results of cyclic voltammetry (CV) analysis, increasing bath pH caused a negative shift in the cathodic deposition potential. In addition, the anodic dissolution peaks first shifted to the positive side with increasing pH and then shifted back to the negative direction. According to the results of XRD analysis, the phase structure of Cu-Zn alloys generally consists of alpha and beta ' phases, but according to differential scanning calorimeter (DSC) analysis, it is possible that there is a gamma phase in the structure in addition to these phases. In addition, pH increase (4.5 to 6.5) caused a relative increase in crystal grain size (similar to 14 to similar to 25 nm). The Zn content of Cu-Zn coatings first increased (similar to pct 15 to similar to pct 55) with pH increase, then followed a horizontal trend (similar to pct 55 to similar to pct 59) with further pH increase and then exhibited a slight decreasing trend (similar to pct 59 to similar to pct 52). The pH increase significantly affected the surface morphology of the coatings and denser coatings were obtained with increasing pH. While the electrical resistivity of Cu-Zn coatings first increased (0.0408 to 0.0696 mu Omega cm for 297 K) with increasing pH, it tended to decrease (0.0696 to 0.0479 mu Omega cm for 297 K) again at higher pH values. In addition, the electrical resistivity of the coatings increased with increasing measurement temperature. According to DSC analysis of the coatings, endothermic peaks were obtained, possibly representing the transformation from gamma to beta ' phase. [GRAPHICS] . (c) The Author(s) 2024Öğe Effect of Cu concentration on the formation of Cu1-x Znx shape memory alloy thin films(Elsevier Science Bv, 2014) Karahan, Ismail Hakki; Ozdemir, RasimThe CuxZn1-x (x = 0.06, 0.08, 0.1) deposits were fabricated by a electrodeposition method. The structural and electrical properties of the films were investigated by cyclic voltammetry (CV), X-ray diffraction (XRD), Scanning electron micrograph (SEM), and DC resistivity measurements. Phase identification of the samples was studied by the XRD patterns. XRD patterns shows the characteristics XRD peaks corresponding to the, beta, and gamma phases. The grain sizes of the samples were decreased whereas microstrain increased with the increase in Cu2+ substitution. The SEM study reveals the fine particle nature of the samples with increasing Cu content. DC resistivity indicates the metallic nature of the prepared samples. It has been found that the Cu ions have a critical influence on the resultant structure and resistivity properties of the Cu-Zn samples. (C) 2014 Elsevier B.V. All rights reserved.Öğe Effect of Sodium Citrate as Complexing Agent on the Electrodeposited CuZn Alloys: Electrochemical, Morphology, Structure, and Electrical Resistivity Studies(Maik Nauka/Interperiodica/Springer, 2023) Ozdemir, Rasim; Karahan, Ismail HakkiIn this study, sodium citrate (SC) ions were applied as a complexing agent in the co-deposition of CuZn alloy thin film coatings from nontoxic sulphate electrolyte at room temperature. This study examined the effects of SC ion concentrations on morphology, electrical resistivity, and structure of the deposited thin films. Using the cyclic voltammetry method, electrochemical analyzes were performed. It was seen in the results of XRD analyzes that merely & alpha; and/or & beta; phases were formed in the CuZn thin-film coatings. Average grain sizes, estimated by Scherrer's formula, were decreased 63% via the addition of SC to the bath. Electrical resistivity properties of electrodeposited CuZn alloys were realized at a wide range temperature between 100 to 405 K. It is seen that when the amount of SC in the electrolyte increases, it decreases the amount of copper in the film, increases the amount of zinc, and increases the electrical resistance of the film.Öğe Electrodeposition and properties of Zn, Cu, and Cu1-x Znx thin films(Elsevier Science Bv, 2014) Ozdemir, Rasim; Karahan, Ismail HakkiThe electrodeposition of Cu, Zn and Cu-Zn deposits from the non-cyanide Zn sulphate and Cu sulphate reduced by citrate at constant stirring speed has been investigated. The composition of the Cu-Zn bath was shown to influence the morphology, electrical resistivity, phase composition, and Cu and Zn content of the Cu-Zn deposits. Their structural and electrical properties have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDAX), cyclic voltammeter (CV) and current-voltage measurements against the temperature for electrical resistivity, respectively. XRD shows that Cu-Zn samples are polycrystalline phase. Resistivity results show that the copper film exhibits bigger residual resistivity than both the zinc and the Cu-Zn alloy. Theoretical calculations of the XRD peaks demonstrate that the average crystallite size of the Cu-Zn alloy decreased and microstrain increased when the Cu alloyed with zinc. (C) 2014 Elsevier B.V. All rights reserved.Öğe Electronic structure study of the bimetallic Cu1-xZnx alloy thin films(Taylor & Francis Ltd, 2018) Ozkendir, O. Murat; Cengiz, Erhan; Mirzaei, Mahmoud; Karahan, I. Hakki; Ozdemir, Rasim; Klysubun, WantanaA 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.Öğe Genetic programming modelling for the electrical resistivity of Cu-Zn thin films(Indian Acad Sciences, 2018) Karahan, Ismail Hakki; Ozdemir, RasimElectrical resistivity measurement is an exact way to find defects in metals and alloys. Defects contribute to the residual resistivity, and determining their number is very important. Defining the inner electrical structure of an alloy is difficult, and especially it is unpredictable in alloys. This article offers a genetic programming formulation to learn how deposition conditions and alloy constituents affect the electrical resistivity of Cu-Zn alloy. Input parameters selected were: measurement temperature (K), Cu and Zn% content in the deposition bath and thin films, bath temperature, deposition potential, and the grain size of the samples. Electrical resistivity values were the output parameters. A total of 130 training and testing sets were selected. The comparative results prove the superior performance in predicting electrical resistivity of the films. The produced model proposes a close relationship for all the input parameters with the electrical resistivity property.Öğe A Study on the Electrodeposited Cu-Zn Alloy Thin Films(Springer, 2016) Ozdemir, Rasim; Karahan, Ismail Hakki; Karabulut, OrhanIn this article, electrochemical deposition of the nanocrystalline Cu1-x Zn (x) alloys on to aluminum substrates from a non-cyanide citrate electrolyte at 52.5, 105, 157.5, and 210 A m(-2) current densities were described. The bath solution of the Cu1-x Zn (x) alloys consisted of 0.08 mol L-1 CuSO4 center dot 5H(2)O, 0.2 mol L-1 ZnSO4 center dot 7H(2)O, and 0.5 mol L-1 Na3C6H5O7. The effect of the current density on the microstrain, grainsize, phase structure, and DC electrical resistivity behavior was investigated. The electrolyte was investigated electrochemically by cyclic voltammetry (CV) studies. A scanning electron microscope (SEM) was used to study the morphologies of the deposits. Deposited alloys were investigated by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and four-point probe electrical resistivity techniques. With an increase in applied current density values from 52.5 to 210 A m(-2), the amount of deposited copper in the alloy was decreased significantly from 65.5 to 16.6 pct and zinc increased from 34.4 to 83.4 pct. An increase in the current density was accompanied by an increase in grain size values from 65 to 95 nm. SEM observations indicated that the morphology of the film surface was modified to bigger grained nanostructures by increasing the current density. The XRD analysis showed alloys have a body-centered cubic (bcc) crystal structure with preferential planes of (110) and (211). Furthermore, four-point measurements of the films revealed that the resistivity of the deposited films was tailored by varying current densities in the electrolyte.
