Browsing by Author "Yetim, T."

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Corrosion Behavior of 316L Stainless Steel in Treated and Untreated Artificial Effluent Solutions (AESS)
(Bulgarian Acad Science, 2016) Yetim, T.
Some organic compounds in wastewaters not only pollute the environment but also cause corrosion to the wastewater transportation systems. In this study the corrosion behavior of treated textile wastewater was investigated by using AISI 316L stainless steel. Treatment was done by sonochemical (US), photochemical (UV) and sonophotochemical (US+UV) processing. These processes were used to degrade the dyestuffs which cause the pollution of textile wastewater. Artificial effluent solutions were prepared for use in the treatment processes. The concentrations of the solutions decreased with time for three treatment processes. The most reduced concentration was obtained after sonophotocatalytic treatment and the least was for sonochemical treatment. The OCP curves were found to move away from the noble direction for all the tested samples. The reduction tendency of the potential values for all samples was observed close to each other. The most active OCP values were for US+UV. In polarization results, the US sample showed a lower corrosion potential and higher corrosion current density. The corrosion results of samples tested in treated solutions were better than in untreated solutions. For the sonophotochemical process, stainless steel showed a better corrosion resistance than the others.
The Effect of Calcination Temperatures on Structural and Electrochemical Properties of TiO2 Film Deposited on Commercial Pure Titanium
(Elsevier Science SA, 2016) Comakli, O.; Yazici, M.; Yetim, T.; Yetim, A. F.; Celik, A.
TiO2 films were deposited on commercial pure titanium (CP-Ti) by sol-gel process, dip coating technique. Coated samples were calcined at various temperatures. The effects of calcination temperature on the structural and electrochemical properties of coated films were investigated. The results showed that the anatase peaks were obtained from the samples calcinated at 500 degrees C. When the calcination temperatures increased from 500 degrees C to 700 degrees C, the intensities of the anatase peaks were increased. As the calcination temperature was 900 degrees C, the anatase phase nearly transformed to the rutile phase. Also, thickness of TiO2 films increased with the increasing calcination temperature. Electrochemical behavior of uncoated and coated samples was mainly investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF) solution. According to test results, corrosion resistance values of TiO2 film coated samples were higher than the uncoated CP-Ti values. Furthermore, corrosion resistance increased with increasing calcination temperature and the best result was observed from the sample calcinated at 900 degrees C. (C) 2015 Elsevier B.V. All rights reserved.
The Effect of Calcination Temperatures on Wear Properties of TiO2 Coated CP-Ti
(Elsevier Science Sa, 2014) Comakli, O.; Yetim, T.; Celik, A.
Commercially pure titanium (CP-Ti) is commonly used as an implant material especially for orthopedic and dental treatments in biomedical applications. This material shows insufficient tribological properties. Some surface treatments were applied on surface CP-Ti in order to improve tribological properties of the CP-Ti. Among these techniques, sol-gel coating process was used for this purpose. In this study, CP-Ti was coated by TiO2 film with sal-gel dip coating process. Coated samples were calcined at the various temperatures. The effects of calcination temperature on the wear performance of the coated films were observed. It was observed that the hardness, elastic modulus, surface roughness, friction coefficient and wear resistance values of coated samples were higher than the uncoated CP-Ti values. Also, these properties of coated samples increased with increasing of calcination temperature. The intensity of the rutile-TiO2 phase increased with the calcination temperatures. It was determined that rutile-TiO2 structure showed self-lubrication like behavior. The best tribological properties were obtained from the sample calcinated at 900 degrees C. (C) 2014 Elsevier B.V. All rights reserved.
The Effect of Plasma Nitriding Temperature on the Electrochemical and Semiconducting Properties of Thin Passive Films Formed on 316 L Stainless Steel Implant Material in SBF Solution
(Elsevier Science Sa, 2015) Yazici, M.; Comakli, O.; Yetim, T.; Yetim, A. F.; Celik, A.
In this study, 316 L stainless steel samples were nitrided plasma at temperatures of 350, 400 and 450 degrees C for 2 h under a gas mixture of 50% N-2-50% H-2. The effect of plasma nitriding temperature on the corrosion performance and semiconductor properties of the passive film on the 316 L stainless steel was evaluated in simulated body fluid (SBF) using electrochemical test and Mott-Schottky analysis. In literature study, the effect of plasma nitriding temperature on corrosion behavior of 316 L stainless steel was evaluated in solutions of NaCl, H2SO4 and acidic for biomedical applications. However, corrosion studies are more suitable to test in simulated body solution. Also, there are no enough studies on the effects of plasma nitriding temperature on semiconductor properties of the passive film obtained on film 316 L stainless steels in SBF solution. So, in this study the effects of plasma nitriding temperature on the electrochemical and semiconducting properties of thin passive films formed on 316 L stainless steel implant material in SBF solution at 37 degrees C were investigated. The effects of microstructure and phase structure on corrosion properties of samples were determined. The results showed that the phase composition and microstructure of the treated samples were affected from the nitriding temperatures. It was obtained that s-phase formed at the lower temperature than 400 degrees C. According to electrochemical test results, the plasma nitriding process at 350 degrees C was the most suitable process condition for improving the corrosion resistance in SBF. All oxide films showed p-type (acceptor) semiconductor behavior at low potentials and n-type (donor) behavior at high potentials. (C) 2014 Published by Elsevier B.V.
Effect of Sol Aging Time on the Wear Properties of TiO2-SiO2 Composite Films Prepared by a Sol-Gel Method
(Elsevier Sci Ltd, 2016) Yazici, M.; Comakli, O.; Yetim, T.; Yetim, A. F.; Celik, A.
TiO2-SiO2 composite films were deposited on commercially pure titanium (Cp-Ti) substrate with composite sols of different aging times (unaged, 1, 3,10 weeks) by a sol gel method. The effects of aging time on the structural, mechanical and wear properties of composite coatings were investigated using pin-on-disk tribotester. The structure of composite coatings was analyzed with XRD and SEM. The wear volume of TiO2-SiO2 composite films were investigated with 3D profilometer. Tribological properties of the composite films were significantly influenced by aging time. Composite coatings prepared from unaged sol showed the best wear resistance. This may be attributed to their high surface hardness, low surface roughness and self-lubricant phase structure. It was observed that increasing aging time led to increase the grain size. It was obtained that the wear volume values increased with increasing aging time. (C) 2016 Elsevier Ltd. All rights reserved.
Effect of Ti Amount on Wear and Corrosion Properties of Ti-Doped Al2O3 Nanocomposite Ceramic Coated Cp Titanium Implant Material
(Elsevier Sci Ltd, 2018) Comakli, O.; Yanici, M.; Yetim, T.; Yetim, A. F.; Celik, A.
Al2O3 and Ti-doped Al2O3 nanocomposite ceramic coatings were prepared by using a sol-gel dip-coating process. Corrosion and wear resistance of Al2O3 ceramic coatings in relation to Ti amount were carried out using pin-on disk tribotester, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Surface characterizations before and after the corrosion and wear tests were investigated by the scanning electron microscope (SEM) and X-ray diffraction (XRD) and hardness analysis. The results of corrosion and wear tests exhibited that the corrosion and wear resistance of nanocomposite ceramic coatings became better than un-coated samples. Also, corrosion and wear resistance of nanocomposite ceramic coatings improved with Ti doping content increased.
The Effect of Wettability on Corrosion Resistance of Oxide Films Produced by Silar Method on Magnesium, Aluminum and Copper Substrates
(Elsevier Science Sa, 2016) Akaltun, Y.; Aslan, M.; Yetim, T.; Cayir, T.; Celik, A.
The CuO, MgO and Al2O3 films were deposited on Cu, Mg and Al substrates by the Successive Ionic Layer Adsorption and Reaction (SITAR) method. While the MgO thin film showed hydrophilic behavior with contact angle of 75, the Al2O3 film was hydrophobic with the contact angle of 117 degrees. The best enhancement in terms of the wetting behavior was obtained from the copper oxide films. For these films, maximum static water contact angle was 164 degrees. Results showed super-hydrophobic property and unique shape of form. Moreover, the superhydrophobic surface of CuO film exhibited higher corrosion resistance than MgO and Al2O3 films. (C) 2016 Elsevier B.V. All rights reserved.
Improving Structural, Tribological and Electrochemical Properties of Ti6al4v Alloy with B-Doped TiO2 Thin Films
(Elsevier Sci Ltd, 2020) Celik, A.; Acar, M. T.; Yetim, T.; Kovaci, H.; Yetim, A. F.
B-doped TiO2 coatings with different B:Ti molar ratios were produced on Ti6Al4V alloy by a sol-gel dip-coating in order to improve tribological and electrochemical properties of Ti6Al4V. The properties of films were evaluated by XRD, XPS, SEM, surface tension-meter, tribotester and EIS. The highest roughness and hardness were obtained from B:Ti molar ratio of 2:1 TiO2 thin-film. TiO2 and B-doped TiO2 improved the wear resistance. While the mean CoF of Ti6Al4V was 0.39, TiO2 films reduced CoF significantly. B-doped TiO2 showed higher wear resistance than substrate and TiO2 film. Corrosion resistance was enhanced by TiO2 and the increasing B molar ratio provided improvement. The surface state changed after coatings. While TiO2 film showed hydrophobic behavior, B-doped all films exhibited hydrophilic characteristics.
An Investigation of the Corrosion Properties of Ag-Doped TiO2-Coated Commercially Pure Titanium in Different Biological Environments
(Elsevier Science Sa, 2017) Yetim, T.
Ag-doped TiO2 films were coated via the sol-gel method on commercially pure titanium (CP-Ti), and their corrosion properties in simulated body fluid, artificial saliva and Ringer's solution were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Both un-doped and Ag-doped TiO(2-)coated samples exhibited higher corrosion resistances than uncoated samples. It was determined that Ag-doping improved the corrosion resistance compared with untreated and un-doped TiO2 film-coated samples in the three electrolytes. It was also observed that the Ag-doped TiO2 coating had the highest corrosion resistance in saliva. The use of the Ag-doped TiO2 coating in a saliva medium is more suitable for real medical applications. Additionally, Ag-doped TiO2-coated implants can be used in dental applications. (C) 2016 Elsevier B.V. All rights reserved.
Sonolytic, Photocatalytic and Sonophotocatalytic Disinfection of Vibrio Cholerae
(Parlar Scientific Publications, 2020) Gormez, A.; Yetim, T.; Gurkok, S.
In this study, bacterial disinfection was investigated by using the sonolysis, photocatalysis and sonophotocatalysis processes. For this purpose, Vibrio cholerae Inaba NCTC 3661 strain was used throughout the study. Compared to sonolysis and photocatalysis, sonophotocatalysis was found to be the most effective on disinfection. In addition, different wavelengths (254 nm and 365 nm) of ultraviolet lamps (UV) were evaluated on disinfection. The wavelength of 254 nm was more effective than 365 nm on the disinfection. Moreover, the shortest disinfection time was measured as 8 minutes in sonophotocatalytic process at 254 nm wavelength. © 2020 Parlar Scientific Publications. All rights reserved.
Synergistic Effect of Sonolysis and Photocatalysis in the Degradation Kinetics of Effluent Solution
(Pleiades Publishing Inc, 2016) Yetim, T.; Tekin, T.
In this study, degradation of the effluent solution using sonolysis, sonocatalysis, photocatalysis and sonophotocatalysis was investigated. For this purpose, an artificial effluent solution (AES) containing Acid Black 1 and Acid Blue 62 dyestuffs was prepared. The initial AES concentration, catalyst amount, light intensity and the power of ultrasound energy were chosen as the reaction parameters.The degradation rate of AES followed the pseudo-first order kinetics inconcentration of artificial effluent solution. The results showed that the sonophotocatalysis (US + UV + TiO2) was more effective in the degradation than sonolysis (US), sonocatalysis (US + TiO2) and photocatalysis (UV + TiO2) performed individually. The highest and lowest degradation rates were obtained in sonophotocatalytic process and sonolytic process (US), respectively. It was found also that the synergistic effect between sonolysis and photocatalysis processes is the main reason why the maximum degradation is achievable in the sonophotocatalytic process.
Synthesis and Characterisation of Single and Duplex ZnO/TiO2 Ceramic Films on Additively Manufactured Bimetallic Material of 316L Stainless Steel and Ti6Al4V
(IOP Publishing Ltd, 2023) Yetim, T.; Tekdir, H.; Taftali, M.; Turalioglu, K.; Yetim, A. F.
Selective laser melting (SLM), one of the Laser Powder Bed Fusion (LPBF) additive manufacturing methods, has enabled the layered production of Ti6Al4V/316L layered samples, thanks to the layer-by-layer construction. Although 316L and Ti6Al4V are used in many engineering applications, their wear performance is limited. This study aims to improve the tribological and electrochemical properties of Ti6Al4V/316L layered samples. Thus, ZnO, TiO2 monolayer, composite, and ZnO/TiO2, TiO2/ZnO multilayer ceramic films on Ti6Al4V/316L layered surface sample, were coated via the sol-gel dip-coating process. The structural, morphological, and tribological properties of ZnO-TiO2 ceramic films were analyzed via x-ray diffractometer, Scanning Electron Microscopy (SEM), and 3D profilometer. The tribological properties of these coatings were examined using a reciprocating tribo-tester, and the electrochemical properties of samples were evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Structural and mechanical results indicated that ZnO and TiO2 films (monolayer, composite, and multilayer-coated) have higher surface roughness and hardness values than additively manufactured Ti6Al4V/316L layered models. Both single and multilayer ZnO and TiO2 ceramic-coated films improved the wear resistance of the Ti6Al4V/316L substrate. Also, The best tribological and corrosion resistance was acquired for the multilayer film (ZnO/TiO2) among all the coated models.
The Tribological and Corrosion Properties of Anodized Ti6Al4V/316L Bimetallic Structures Manufactured by Additive Manufacturing
(Elsevier Science Sa, 2021) Turalioglu, K.; Taftali, M.; Tekdir, H.; Comakli, O.; Yazici, M.; Yetim, T.; Yetim, A. F.
In this study, layered Ti6Al4V/316L substrates were formed by Laser Powder Bed Fusion. TiO2 ceramic layers were produced on the Ti6Al4V/316L structures by an anodic oxidation method at different coating times (15, 30, and 60 min) to advance the wear features of layered Ti6Al4V/316L structure. The surface characterizations, wear and electrochemical behaviors of all specimens were examined via scanning electron microscopy, X-ray diffraction, a microhardness device, a reciprocating tribo-tester, and electrochemical corrosion experiments. According to the outcomes, the wear and corrosion resistance of the anodic oxidized specimens were higher compared to untreated 316L and layered Ti6Al4V/316L substrates, and the best results were obtained from the anodized specimen treated for 60 min.
Tribological and Electrochemical Properties of TiO2 Films Produced on Cp-Ti by Sol-Gel and Silar in Bio-Simulated Environment
(Elsevier Science Sa, 2018) Comakli, O.; Yazici, M.; Kovaci, H.; Yetim, T.; Yetim, A. F.; Celik, A.
Commercially pure titanium (Cp-Ti) is commonly used in different applications due to its good structural properties but its low mechanical and tribological properties restrict its usage areas. Therefore, different surface modifications based on TiO2 formation on material surfaces are applied to enhance surface features of materials. In this study, TiO2 films were produced on Cp-Ti by sol-gel and successive ionic layer adsorption and reaction (SILAR) methods to compare the effectiveness of these methods. The structural, morphological and mechanical features of TiO2 films were investigated by XRD, SEM and nano-indentation tester. The tribological features of coatings were characterized by using a pin-on-disk tribotester. The electrochemical behavior of TiO2 coatings was determined by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analyses. The structural and mechanical analyses showed that sol-gel method caused the formation of more stable and hard film structures with good adhesion in comparison to SILAR method. For that reason, TiO2 films produced by sol-gel process exhibited better wear and corrosion resistance than the films produced by SILAR.
Tribological Behavior of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings on 316l Stainless Steel Under High-Temperature Conditions
(Elsevier, 2023) Yetim, A. F.; Tekdir, H.; Turalioglu, K.; Taftali, M.; Yetim, T.
Yttria Stabilized Zirconia (YSZ) coatings by plasma spray coating were performed to investigate the behavior of 316L Stainless Steel (SS) under high temperatures. The structural and mechanical properties of YSZ films were examined by successful scanning electron microscopy and Vickers microhardness. A tribotester determined the friction and wear properties at 500 and 1000 degrees C temperature conditions. The results showed that the surface hardness values of the YSZ-coated samples were significantly improved due to obtained ceramic layer compared with untreated 316L samples. Although the abrasive wear mechanism was observed in both the coated and uncoated samples, it was observed that higher temperatures produced smoother wear tracks. Also, increased wear test temperatures resulted in micro cracks and structural degradations on the surface of untreated stainless steel samples.
Tribological Properties of TiO2/SiO2 Double Layer Coatings Deposited on Cp-Ti
(World Scientific Publ Co Pte Ltd, 2017) Comakli, O.; Yazici, M.; Yetim, T.; Yetim, A. F.; Celik, A.
In the present paper, the influences of different double layer on wear and scratch performances of commercially pure Titanium (CP-Ti) were investigated. TiO2/SiO2 and SiO2/TiO2 double layer coatings were deposited on CP-Ti by sol-gel dip coating process and calcined at 750 degrees C. The phase structure, cross-sectional morphology, composition, wear track morphologies, adhesion properties, hardness and roughness of uncoated and coated samples were characterized with X-ray diffraction, scanning electron microscopy (SEM), nano-indentation technique, scratch tester and 3D profilometer. Also, the tribological performances of all samples were investigated by a pin-on-disc tribotester against Al2O3 ball. Results showed that hardness, elastic modulus and adhesion resistance of double layer coated samples were higher than untreated CP-Ti. It was found that these properties of TiO2/SiO2 double layer coatings have higher than SiO2/TiO2 double layer coating. Additionally, the lowest friction coefficient and wear rates were obtained from TiO2/SiO2 double layer coatings. Therefore, it was seen that phase structure, hardness and film adhesion are important factors on the tribological properties of double layer coatings.
Wear and Tribocorrosion Behavior of UV Curable Coated CP-Ti
(Elsevier, 2023) Cakir, M. Aslan; Yetim, T.; Bozkurt, Y. B.; Kovaci, H.; Celik, A.
In this study, commercial titanium (Cp-Ti) was coated with a UV-curable film to improve the wearing and tri-bocorrosion performance of Cp-Ti. Wear tests were carried out under dry and simulated body fluid (SBF) test environments, and tribocorrosion tests were also performed in SBF. In tribocorrosion tests, a reciprocating test device coupled with open circuit potential and potentiodynamic polarization test monitoring system was used. SEM investigations showed that a polymeric film with a layer thickness of about 3-4 mu m was deposited on Cp-Ti. It was also found that the Si element in the film considerably increased the hardness and improved the wear performance. According to tribocorrosion test results, the corrosion mechanism has significantly increased the wear rates. The wear resistance of the Cp-Ti surface was markedly enhanced by UV-curable treatment.