ismail karahan - Academia.edu (original) (raw)

Papers by ismail karahan

Acta Physica Polonica A, Jul 1, 2016

Polyaniline (PANI) was successfully deposited by means of cyclic voltammetry technique from 0.10 ... more 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.

Acta Physica Polonica A, Jul 1, 2016

Zinc-iron alloy plating (ZnFe) was successfully deposited on AISI 4140 steel applying cyclic volt... more 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 zinciron 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/cm 2 current density probably offer bigger protection to the steel substrate.

Materials research express, Dec 5, 2019

The effect of hexadecyltrimethylammonium bromide (CTAB) concentration on the galvanostatic electr... more The effect of hexadecyltrimethylammonium bromide (CTAB) concentration on the galvanostatic electrodeposition of Ni-B matrix nano hexagonal boron nitride (hBN) reinforced composite coatings was investigated. XRD and FE-SEM analyzes were used for crystallographical and morphological investigations, respectively. Vickers indentation, nanoindentation, and nanoscratch experiments were carried out to investigate the micromechanical, nanomechanical and tribological properties, respectively. Potentiodynamic polarization and electrochemical impedance spectroscopy techniques were applied for corrosion characterization. The investigated properties have been improved with the increasing CTAB concentrations up to 900 μM. In a general manner, CTAB has a beneficial effect at lower concentrations and can be useful for metal matrix nano ceramic reinforced composite coating electrodeposition in the lower concentration range.

Acta Physica Polonica A, Sep 1, 2017

Thin film brass alloys were galvanostatically electrodeposited from non-cyanide citrate solutions... more 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.

Estimation of microhardness and crystal grain size values of electrodeposited Ni-B/TiC nanocomposite coatings by artificial neural networks (ANN) method

Journal of Alloys and Compounds

A Response Surface Study on the Grown Behavior and Some Mechanical Properties of Niobium Carbide Coatings

Surface Review and Letters

In this study, response surface methodology was used to examine the effects of temperature and ti... more In this study, response surface methodology was used to examine the effects of temperature and time on the development of niobium carbide coatings on AISI D3 steel. The effect of niobizing temperature (900–1100∘C) and period (2–6 hours) on coating thickness, hardness, fracture toughness, coefficient of friction and wear rates was investigated. ANOVA was conducted to analyze the experimental data, and it was observed that the coating thickness and microhardness increased with temperature and time. The response surfaces developed for fracture toughness, coefficient of friction and wear rates were found to exhibit a complex structure that is significantly influenced by temperature, time and their interactions. The correlation coefficients of the developed regression models range between 0.82 and 0.99. Using the empirical formulas obtained with these mathematical models, it is predicted that niobium carbide coatings can be obtained with the targeted properties more economically and prac...

Effect of trimethylamine borane (TMAB) bath concentration on electrodeposited Ni–B/TiC nanocomposite coatings

Ceramics International

Çukurova Üniversitesi Mühendislik Fakültesi Dergisi

Makine parçaları korozyon ve aşınma gibi malzeme yüzeylerinde hasara neden olan çeşitli etkilere ... more Makine parçaları korozyon ve aşınma gibi malzeme yüzeylerinde hasara neden olan çeşitli etkilere maruz kalmaktadır. Malzeme yüzeylerinin bu zararlı etkilerden korunması için çeşitli ve etkili yöntemler bulunmaktadır. Elektrokimyasal kaplama bu yöntemlerden en çok tercih edilenlerden bir tanesidir. Bu çalışmada, Ni-B alaşımı ana yapısı titanyum karbür (TiC) takviye parçacıkları ile desteklenerek, sanayide kullanımı çok tercih edilen AISI 304 kalite paslanmaz çelik üzerine elektrokimyasal depolama metodu ile kaplanmıştır. Elde edilen bu kaplamaların korozyon dayanımları elektrokimyasal empedans spektroskopisi (EES) yöntemi ile analiz edilmiştir. Mukayese yapmak amacıyla paslanmaz çelik altlığın korozyon direncinin yanı sıra, saf nikel ve Ni-B alaşım kaplamalarda üretilmiş ve korozyon direnci incelenmiştir. Elde edilen sonuçlara göre, Ni-B/TiC nanokompozit kaplamaların Nyquist eğrilerinin, paslanmaz çelik, saf nikel ve Ni-B alaşıma göre çok daha kapsayıcı ve geniş görünümlü olduğu tesp...

Investigation of the Properties of Ni–B/TiC Nanocomposite Coatings Produced at Different Particle Concentrations by Electrodeposition

Metallurgical and Materials Transactions A

Characterizations and Kinetics of Refractory Niobium Carbide Coatings on AISI D3 Steel

Journal of Materials Engineering and Performance

The effect of metal rate on the gamma shielding parameters of hydroxyapatite at medical treatment energies

Applied Radiation and Isotopes

Effect of Current Density and Trimethylamine Borane (Tmab) Bath Concentration on Electrodeposited Ni-B/Tic Nanocomposite Coatings

SSRN Electronic Journal

Characterisation, hardness and corrosion behaviour of electrodeposited ZnFe and ZnFe/BN composite coatings

Transactions of the IMF

Electrodeposition and Properties of ZnFeNi alloys

Chinese Journal of Physics, 2008

Four Zn-Fe-Ni films were electrodeposited under potentiostatic deposition conditions on aluminum ... more Four Zn-Fe-Ni films were electrodeposited under potentiostatic deposition conditions on aluminum and steel plates. Their composition, corrosion property, and structure were evaluated as a function of the FeSO4 concentration in the electrolyte. Cyclic voltammetry of the individual metals was performed in conjunction with the SEM technique to study the electroplating process of the films. The results show that Zn-Fe-Ni alloys can be produced with good adhesive and anticorrosive properties, and all films have the same crystallographic structure as zinc, but with different crystallographic orientations.

Surface and Coatings Technology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Properties and Corrosion Behavior of Chromium and Vanadium Carbide Composite Coatings Produced on Ductile Cast Iron by Thermoreactive Diffusion Technique

Journal of Engineering Materials and Technology, 2020

Ductile iron (DI) owes many of its attractive mechanical properties to the graphite nodules in it... more Ductile iron (DI) owes many of its attractive mechanical properties to the graphite nodules in its structure. However, since galvanic coupling can occur between the graphite nodules and the matrix in aggressive environments, these nodules can, at the same time, reduce its corrosion resistance. In this study, composite carbide coatings were grown on the surface of GGG-80 using the thermoreactive diffusion (TRD) process. The process was carried out at 900, 1000, and 1100 °C for 1 h using nanosized Fe-V and Fe-Cr powders. The coatings were characterized by X-ray diffractometry (XRD), two-dimensional profilometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and microhardness tests. The corrosion behavior of the coatings were evaluated in three different solutions (3.5 wt% NaCl, 5 wt% H2SO4, and 5 wt% HNO3) using electrochemical open-circuit potential (OCP) and potentiodynamic polarization measurements. Microstructures and hardness tests showed that th...

Characterization of electrodeposited Ni–Cr/hBN composite coatings

Journal of Alloys and Compounds, 2020

Abstract In this study, Ni–Cr/hBN composite coatings with different hBN content were deposited on... more Abstract In this study, Ni–Cr/hBN composite coatings with different hBN content were deposited on AISI 1040 mild carbon steel using electrodeposition. The coatings were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), cyclic voltammetry (CV), 2D surface profilometery, nano-indentation, corrosion and wear tests. While some cracks were observed in the Ni–Cr alloy coatings, more compact and crack-free surfaces were obtained in the Ni–Cr/hBN composite coatings under all deposition conditions. XRD analysis of the Ni–Cr/hBN layer revealed the presence of a predominant Ni phase with Cr, Cr2Ni3B6, (Ni2Cr23)0.16, and hBN phases in the structure. Depending on deposition parameters, the microhardness and nanohardness of the Ni–Cr and Ni–Cr/hBN coatings were found to range between 308 and 538 HV and 1,86–7,69 GPa respectively. hBN acted as a solid lubricant in the wear tests; the friction coefficient decreased and wear resistance was improved. Among the composite coatings, the corrosion resistance of the coating with 20 g/l hBN was found to be 12 and 3.3 times higher than the steel substrate and Ni–Cr alloy, respectively. The hBN additive provided better mechanical properties and corrosion resistance in the range of 5–20 g/l hBN, but after 20 g/l hBN agglomeration became a problem and impaired the mechanical properties. The highest corrosion and abrasion resistance was obtained with 20 g/l hBN.

Metallurgical and Materials Transactions A, 2016

CoCrMo biomedical alloys were coated with a hydroxyapatite layer to improve biocompatibility and ... more CoCrMo biomedical alloys were coated with a hydroxyapatite layer to improve biocompatibility and in vitro corrosion performance. A fast electrodeposition process was completed in 5 minutes for the hydroxyapatite coating. Effect of the solution temperature and applied potential on the in vitro corrosion performance of the hydroxyapatite coatings was modeled by response surface methodology (RSM) coupled with central composite design (CCD). A 5-level-2-factor experimental plan designed by CCD was used; the experimental plan contained 13 coating experiments with a temperature range from 283 K to 347 K (10 °C to 74 °C) and potential range from À1.2 to À1.9 V. Corrosion potential (E corr ) of the coatings in a simulated body fluid solution was chosen as response for the model. Predicted and experimental values fitted well with an R 2 value of 0.9481. Response surface plots of the impedance and polarization resistance (R P ) were investigated. Optimized parameters for electrodeposition of hydroxyapatite were determined by RSM as solution temperature of 305.48 K (32.33 °C) and potential of À1.55 V. Hydroxyapatite coatings fabricated at optimized parameters showed excellent crystal formation and high in vitro corrosion resistance.

Transactions of the IMF, 2014

Polyaniline (PANI) conducting polymer coatings have been obtained galvanostatically with various ... more Polyaniline (PANI) conducting polymer coatings have been obtained galvanostatically with various current densities (from 0?1 to 0?4 mA cm 22 ) and ZnNi alloy coatings have been obtained galvanostatically at 30 mA cm 22 current density. Corrosion protection performances of monolayered PANI and ZnNi alloy coatings and multi-layered ZnNi/PANI and PANI/ZnNi coatings on st-37 low carbon mild steel (MS) have been investigated by an open circuit potential method, Tafel extrapolation method and electrochemical impedance method in 3?5 wt-% NaCl solution. In addition, the surface morphology of the coatings has been characterised by using scanning electron microscopy (SEM). Synthesising PANI films between two metal layers provided better corrosion protection to the steel. MS/PANI/ZnNi layer formation exhibited the biggest corrosion protection performance among all layer formations of the films and protected MS for up to 72 h.

Electrochimica Acta, 2014

A bioactive hydroxyapatite layer deposited on the CoCrMo bio-metallic alloys by electrodeposition... more A bioactive hydroxyapatite layer deposited on the CoCrMo bio-metallic alloys by electrodeposition under different concentrations of calcium, phosphate and H 2 O 2 . Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to optimize electrolyte concentrations. RSM and CCD were used to understand the concentration effects on the in vitro corrosion performance of biomaterials. 5level-3-factor CCD was employed to evaluate effects of deposition parameters such as calcium concentration (0.016-0.184 M), phosphate concentration (0.005-0.055 M) and H 2 O 2 concentration (2.4-27.6 ml/L) on the hydroxyapatite coatings and their corrosion resistance. Data obtained from RSM were subjected to analysis of variance (ANOVA) and analysed using a second order polynomial equation. Optimum conditions for the deposition parameters of the hydroxyapatite layer coating were found to be a calcium concentration of 0.05 M, phosphate concentration of 0.04 M and H 2 O 2 concentration of 22.11 ml/ L. Maximum phase angle under the optimum conditions was determined to be 85.4 . Ringer's simulated body fluid was used for in vivo electrochemical impedance spectroscopy analyses of biomaterials.

Acta Physica Polonica A, Jul 1, 2016

Polyaniline (PANI) was successfully deposited by means of cyclic voltammetry technique from 0.10 ... more 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.

Acta Physica Polonica A, Jul 1, 2016

Zinc-iron alloy plating (ZnFe) was successfully deposited on AISI 4140 steel applying cyclic volt... more 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 zinciron 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/cm 2 current density probably offer bigger protection to the steel substrate.

Materials research express, Dec 5, 2019

The effect of hexadecyltrimethylammonium bromide (CTAB) concentration on the galvanostatic electr... more The effect of hexadecyltrimethylammonium bromide (CTAB) concentration on the galvanostatic electrodeposition of Ni-B matrix nano hexagonal boron nitride (hBN) reinforced composite coatings was investigated. XRD and FE-SEM analyzes were used for crystallographical and morphological investigations, respectively. Vickers indentation, nanoindentation, and nanoscratch experiments were carried out to investigate the micromechanical, nanomechanical and tribological properties, respectively. Potentiodynamic polarization and electrochemical impedance spectroscopy techniques were applied for corrosion characterization. The investigated properties have been improved with the increasing CTAB concentrations up to 900 μM. In a general manner, CTAB has a beneficial effect at lower concentrations and can be useful for metal matrix nano ceramic reinforced composite coating electrodeposition in the lower concentration range.

Acta Physica Polonica A, Sep 1, 2017

Thin film brass alloys were galvanostatically electrodeposited from non-cyanide citrate solutions... more 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.

Estimation of microhardness and crystal grain size values of electrodeposited Ni-B/TiC nanocomposite coatings by artificial neural networks (ANN) method

Journal of Alloys and Compounds

A Response Surface Study on the Grown Behavior and Some Mechanical Properties of Niobium Carbide Coatings

Surface Review and Letters

In this study, response surface methodology was used to examine the effects of temperature and ti... more In this study, response surface methodology was used to examine the effects of temperature and time on the development of niobium carbide coatings on AISI D3 steel. The effect of niobizing temperature (900–1100∘C) and period (2–6 hours) on coating thickness, hardness, fracture toughness, coefficient of friction and wear rates was investigated. ANOVA was conducted to analyze the experimental data, and it was observed that the coating thickness and microhardness increased with temperature and time. The response surfaces developed for fracture toughness, coefficient of friction and wear rates were found to exhibit a complex structure that is significantly influenced by temperature, time and their interactions. The correlation coefficients of the developed regression models range between 0.82 and 0.99. Using the empirical formulas obtained with these mathematical models, it is predicted that niobium carbide coatings can be obtained with the targeted properties more economically and prac...

Effect of trimethylamine borane (TMAB) bath concentration on electrodeposited Ni–B/TiC nanocomposite coatings

Ceramics International

Çukurova Üniversitesi Mühendislik Fakültesi Dergisi

Makine parçaları korozyon ve aşınma gibi malzeme yüzeylerinde hasara neden olan çeşitli etkilere ... more Makine parçaları korozyon ve aşınma gibi malzeme yüzeylerinde hasara neden olan çeşitli etkilere maruz kalmaktadır. Malzeme yüzeylerinin bu zararlı etkilerden korunması için çeşitli ve etkili yöntemler bulunmaktadır. Elektrokimyasal kaplama bu yöntemlerden en çok tercih edilenlerden bir tanesidir. Bu çalışmada, Ni-B alaşımı ana yapısı titanyum karbür (TiC) takviye parçacıkları ile desteklenerek, sanayide kullanımı çok tercih edilen AISI 304 kalite paslanmaz çelik üzerine elektrokimyasal depolama metodu ile kaplanmıştır. Elde edilen bu kaplamaların korozyon dayanımları elektrokimyasal empedans spektroskopisi (EES) yöntemi ile analiz edilmiştir. Mukayese yapmak amacıyla paslanmaz çelik altlığın korozyon direncinin yanı sıra, saf nikel ve Ni-B alaşım kaplamalarda üretilmiş ve korozyon direnci incelenmiştir. Elde edilen sonuçlara göre, Ni-B/TiC nanokompozit kaplamaların Nyquist eğrilerinin, paslanmaz çelik, saf nikel ve Ni-B alaşıma göre çok daha kapsayıcı ve geniş görünümlü olduğu tesp...

Investigation of the Properties of Ni–B/TiC Nanocomposite Coatings Produced at Different Particle Concentrations by Electrodeposition

Metallurgical and Materials Transactions A

Characterizations and Kinetics of Refractory Niobium Carbide Coatings on AISI D3 Steel

Journal of Materials Engineering and Performance

The effect of metal rate on the gamma shielding parameters of hydroxyapatite at medical treatment energies

Applied Radiation and Isotopes

Effect of Current Density and Trimethylamine Borane (Tmab) Bath Concentration on Electrodeposited Ni-B/Tic Nanocomposite Coatings

SSRN Electronic Journal

Characterisation, hardness and corrosion behaviour of electrodeposited ZnFe and ZnFe/BN composite coatings

Transactions of the IMF

Electrodeposition and Properties of ZnFeNi alloys

Chinese Journal of Physics, 2008

Four Zn-Fe-Ni films were electrodeposited under potentiostatic deposition conditions on aluminum ... more Four Zn-Fe-Ni films were electrodeposited under potentiostatic deposition conditions on aluminum and steel plates. Their composition, corrosion property, and structure were evaluated as a function of the FeSO4 concentration in the electrolyte. Cyclic voltammetry of the individual metals was performed in conjunction with the SEM technique to study the electroplating process of the films. The results show that Zn-Fe-Ni alloys can be produced with good adhesive and anticorrosive properties, and all films have the same crystallographic structure as zinc, but with different crystallographic orientations.

Surface and Coatings Technology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Properties and Corrosion Behavior of Chromium and Vanadium Carbide Composite Coatings Produced on Ductile Cast Iron by Thermoreactive Diffusion Technique

Journal of Engineering Materials and Technology, 2020

Ductile iron (DI) owes many of its attractive mechanical properties to the graphite nodules in it... more Ductile iron (DI) owes many of its attractive mechanical properties to the graphite nodules in its structure. However, since galvanic coupling can occur between the graphite nodules and the matrix in aggressive environments, these nodules can, at the same time, reduce its corrosion resistance. In this study, composite carbide coatings were grown on the surface of GGG-80 using the thermoreactive diffusion (TRD) process. The process was carried out at 900, 1000, and 1100 °C for 1 h using nanosized Fe-V and Fe-Cr powders. The coatings were characterized by X-ray diffractometry (XRD), two-dimensional profilometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and microhardness tests. The corrosion behavior of the coatings were evaluated in three different solutions (3.5 wt% NaCl, 5 wt% H2SO4, and 5 wt% HNO3) using electrochemical open-circuit potential (OCP) and potentiodynamic polarization measurements. Microstructures and hardness tests showed that th...

Characterization of electrodeposited Ni–Cr/hBN composite coatings

Journal of Alloys and Compounds, 2020

Abstract In this study, Ni–Cr/hBN composite coatings with different hBN content were deposited on... more Abstract In this study, Ni–Cr/hBN composite coatings with different hBN content were deposited on AISI 1040 mild carbon steel using electrodeposition. The coatings were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), cyclic voltammetry (CV), 2D surface profilometery, nano-indentation, corrosion and wear tests. While some cracks were observed in the Ni–Cr alloy coatings, more compact and crack-free surfaces were obtained in the Ni–Cr/hBN composite coatings under all deposition conditions. XRD analysis of the Ni–Cr/hBN layer revealed the presence of a predominant Ni phase with Cr, Cr2Ni3B6, (Ni2Cr23)0.16, and hBN phases in the structure. Depending on deposition parameters, the microhardness and nanohardness of the Ni–Cr and Ni–Cr/hBN coatings were found to range between 308 and 538 HV and 1,86–7,69 GPa respectively. hBN acted as a solid lubricant in the wear tests; the friction coefficient decreased and wear resistance was improved. Among the composite coatings, the corrosion resistance of the coating with 20 g/l hBN was found to be 12 and 3.3 times higher than the steel substrate and Ni–Cr alloy, respectively. The hBN additive provided better mechanical properties and corrosion resistance in the range of 5–20 g/l hBN, but after 20 g/l hBN agglomeration became a problem and impaired the mechanical properties. The highest corrosion and abrasion resistance was obtained with 20 g/l hBN.

Metallurgical and Materials Transactions A, 2016

CoCrMo biomedical alloys were coated with a hydroxyapatite layer to improve biocompatibility and ... more CoCrMo biomedical alloys were coated with a hydroxyapatite layer to improve biocompatibility and in vitro corrosion performance. A fast electrodeposition process was completed in 5 minutes for the hydroxyapatite coating. Effect of the solution temperature and applied potential on the in vitro corrosion performance of the hydroxyapatite coatings was modeled by response surface methodology (RSM) coupled with central composite design (CCD). A 5-level-2-factor experimental plan designed by CCD was used; the experimental plan contained 13 coating experiments with a temperature range from 283 K to 347 K (10 °C to 74 °C) and potential range from À1.2 to À1.9 V. Corrosion potential (E corr ) of the coatings in a simulated body fluid solution was chosen as response for the model. Predicted and experimental values fitted well with an R 2 value of 0.9481. Response surface plots of the impedance and polarization resistance (R P ) were investigated. Optimized parameters for electrodeposition of hydroxyapatite were determined by RSM as solution temperature of 305.48 K (32.33 °C) and potential of À1.55 V. Hydroxyapatite coatings fabricated at optimized parameters showed excellent crystal formation and high in vitro corrosion resistance.

Transactions of the IMF, 2014

Polyaniline (PANI) conducting polymer coatings have been obtained galvanostatically with various ... more Polyaniline (PANI) conducting polymer coatings have been obtained galvanostatically with various current densities (from 0?1 to 0?4 mA cm 22 ) and ZnNi alloy coatings have been obtained galvanostatically at 30 mA cm 22 current density. Corrosion protection performances of monolayered PANI and ZnNi alloy coatings and multi-layered ZnNi/PANI and PANI/ZnNi coatings on st-37 low carbon mild steel (MS) have been investigated by an open circuit potential method, Tafel extrapolation method and electrochemical impedance method in 3?5 wt-% NaCl solution. In addition, the surface morphology of the coatings has been characterised by using scanning electron microscopy (SEM). Synthesising PANI films between two metal layers provided better corrosion protection to the steel. MS/PANI/ZnNi layer formation exhibited the biggest corrosion protection performance among all layer formations of the films and protected MS for up to 72 h.

Electrochimica Acta, 2014

A bioactive hydroxyapatite layer deposited on the CoCrMo bio-metallic alloys by electrodeposition... more A bioactive hydroxyapatite layer deposited on the CoCrMo bio-metallic alloys by electrodeposition under different concentrations of calcium, phosphate and H 2 O 2 . Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to optimize electrolyte concentrations. RSM and CCD were used to understand the concentration effects on the in vitro corrosion performance of biomaterials. 5level-3-factor CCD was employed to evaluate effects of deposition parameters such as calcium concentration (0.016-0.184 M), phosphate concentration (0.005-0.055 M) and H 2 O 2 concentration (2.4-27.6 ml/L) on the hydroxyapatite coatings and their corrosion resistance. Data obtained from RSM were subjected to analysis of variance (ANOVA) and analysed using a second order polynomial equation. Optimum conditions for the deposition parameters of the hydroxyapatite layer coating were found to be a calcium concentration of 0.05 M, phosphate concentration of 0.04 M and H 2 O 2 concentration of 22.11 ml/ L. Maximum phase angle under the optimum conditions was determined to be 85.4 . Ringer's simulated body fluid was used for in vivo electrochemical impedance spectroscopy analyses of biomaterials.