MCBÜ Açıkerişim Sistemi :: Browsing by Author "Durmus, H"

Browsing by Author "Durmus, H"

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Al/Zn/Al2O3 and Zn/Al2O3 Coatings by Cold Spray Coating Method of WE43 Magnesium Alloy and Investigation of Its Wear Behaviors
Gül, C; Albayrak, S; Çömez, N; Durmus, H
Mg alloys are preferred in automotive, aircraft, aerospace and communication industries due to their low specific gravity and high strength. WE series is a series of Mg alloys containing Mg, Y, Nd, rare earth elements, and although the creep strength is good for this alloy series, the wear resistance is open to improvement. The aim of this study is to develop coatings that can increase the wear resistance of WE43 Mg alloys, which have a high potential for use due to their specific gravity, by using a method that can be easily applied in the industry. For this purpose, using the cold spray coating method, magnesium alloys, whose surfaces are highly active, are provided to be coated without oxidation and wear resistance is improved. In the study carried out, WE43 Mg alloys, which roughen the surfaces by fine sandblasting process, were used with cold spray method, using powders containing Al/Zn/Al2O3 and Zn/Al2O3 and trade names DYMET K-20-11 and DYMET K-00-11, respectively, using N2 shielding gas at 500 degrees C. 6 g/min for powders delivered to supersonic speeds under the atmosphere. The powder was sprayed onto the substrates using the feed rate. Morphological analysis of the coated and uncoated samples with different contents were examined by SEM, XRD methods, the coating thicknesses were measured with SEM images taken from the section, and the percentages of the elements were determined by EDS analysis. In addition, ball-on disc wear tests were performed to examine the wear performance and volume losses were evaluated. As a result, the wear loss of WE43 alloys was reduced by approximately 40% compared to the uncoated condition, thanks to the cold spray coatings.
A STUDY OF WEAR OF AGED ALUMINUM ALLOYS 2XXX AND 6XXX WITHIN THE MANOVA STATISTICAL ANALYSIS
Meyveci, A; Karacan, I; Firat, EH; Çaligülü, U; Durmus, H
Statistically processed data on the microstructure and wear of aged aluminum alloys AA2024 and AA6063 are presented. Results of wear tests are analyzed using multidimensional analysis of variance (MANOVA) with 95% confidence interval for statistically significant deviations. It is shown that the temperature and the duration of the aging are statistically significant factors affecting wear of aluminum alloys 2XXX and 6XXX.
Improving the wear resistance of the magnesium alloy WE43 by cold sprayed Ni-Al2O3 and Ni-Zn-Al2O3 coatings
Gül, S; Durmus, H; Gül, C; Çömez, N
Lightweight magnesium (Mg) alloys are employed in a wide range of applications due to their high specific strengths. Nevertheless, some applications require improvement of the wear resistance of Mg alloys. The purpose of this study was to investigate the effect of the initial surface conditions, cold spray temperature, and coating material on the wear resistance of the cold sprayed coatings on WE43 Mg substrate. Blasted and sandpapered surfaces were coated with commercial powders of K-32 (Ni and Al2O3) and K-714 (Zn, Ni, and Al2O3). The coating materials were cold sprayed on blasted and sandpapered WE43 Mg surfaces at 500 ?and 600 ?. Surface roughness, thickness and wear resistance of the coatings were examined. Deposition efficiency was improved by raising the N-2 gas temperature. The samples with the greatest wear resistance were those that were coated with Zn, Ni, and Al2O3 powder mixture on sandpapered surfaces at temperatures of 600 ?, where deposition efficiency is maximum. Cold spray coatings enhanced the wear resistance of the WE43 Mg substrate.
Determination of the effect of plasma spray parameters on in-situ reaction intensity by experimental method and by means of artificial neural networks techniques
Durmus, H; Tekmen, C; Tsunekawa, Y
In the present work, mechanically alloyed Al-12Si and SiO2 powder was deposited onto an aluminium substrate by atmospheric plasma spraying (APS) to obtain a composite coating consisting of in-situ formed alumina reinforced hypereutectic Al-18Si matrix alloy. The effects of spray parameters and in-flight particle characteristics on reaction intensity between selective powders were investigated. Obtained results are tested by artificial neural network (ANN) techniques. An ANN model is built, trained and tested. Multilayer perception model has been constructed with back propagation algorithm using the input parameters of arc current, spray distance, in-flight particle velocity and temperature. The ANN model was found able to predict the coating hardness, substrate temperature, alumina intensity and silicon intensity in the range of input parameters considered. This study demonstrates that ANN is very efficient for predicting output parameters of experimental studies.
Determination of tribological properties at CuSn10 alloy journal bearings by experimental and means of artificial neural networks method
Ünlü, BS; Durmus, H; Meriç, C
Purpose - It is important to know the friction coefficient and wear loss for determination of tribological conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. The purpose of this paper is to determine friction coefficient and wear loss at CuSn10 alloy radial bearings by a new approach. In experiments, effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities. Design/methodology/approach - In this study, friction coefficient and wear losses of journal and bearing have been determined by a new approach with a radial journal bearing test rig and artificial neural networks (ANNs) method. The ANN typifies a learning technique that enables the hidden input-output relationship to be mapped accurately. Bronze-based materials have been used as bearing material. Effects of friction coefficient and wear losses have been examined at same load and velocity and at dry and lubricated conditions. Findings - The results obtained in ANN application are close to friction test results for dry and lubricated conditions. Therefore, by using trained ANN values, the intermediate results that were not obtained in the tests can be calculated. Experimental studies will be increased and research with ANN will be continued. Originality/value - By using trained ANN values, the intermediate results that were not obtained in the tests can be calculated. The training finished on 30 min whereas experimental study had continued day after day.
Effect of sandblasting and aging on structural and mechanical properties of Inconel 625 coated steels for marine applications
Durmus, H; Çömez, N; Gül, C
In present study, the Inconel 625 alloy was coated using TIG welding method, and the coating was subjected to sandblasting and artificial aging. The coating samples were examined by wear and corrosion tests to evaluate their performance in marine applications. The study characterized different sample groups for the purposes of coating steel samples, coating surfaces by deformation, applying aging processes, and observing the combined effects of aging and deformation. Wet-sliding wear and corrosion tests were conducted in 3.5 wt.% NaCl solution. The presence of compressive stresses resulting from sandblasting and aging led to microstructural changes, while formation of delta, gamma ', gamma '' phases and complex carbides contributed to increased wear and corrosion resistance. Deformation supported the precipitation of gamma ', gamma '' phases and carbides. Aging increased the hardness by 30 %, whereas the sandblasting process doubled up the hardness of as-deposited coating. Maximum corrosion resistance was obtained in the aged sample without applying sandblasting.
Effects on Mechanical and Physical Properties of Ta Element Addition to Ti-6Al-7Nb Alloy
Caligulu, U; Durmus, H; Kejanli, H; Keskinkilic, AR; Balci, E
Ti and its alloys play a leading role in biomedical applications within the field of materials science. In this study, different amounts of Ta were added to the TiAlNb alloy. Various analyses were carried out to determine the physical and chemical properties of the produced samples. DSC (differential scanning calorimetry), and XRD (X-ray diffraction) analyses were conducted to determine the phase transformations and crystal structure of the alloys, respectively. SEM-EDX (scanning electron microscopy) and OM (optical microscopy) images were taken to analyze the chemical structure of the samples and to examine their microstructures in more detail. Microhardness and wear resistance tests were performed to determine some mechanical properties of the produced samples. It was observed that increasing the tantalum content increased both hardness and wear resistance. These findings suggest that the addition of tantalum to the Ti-6Al-7Nb alloy could be an effective strategy to improve biomaterial performance.
Wear and corrosion resistance of zinc-oxide and zirconium-oxide coated WE43 magnesium alloy
Gül, C; Durmus, H; Albayrak, S; Çömez, N
Magnesium alloy, which draws attention with its lightness and high specific strength, is frequently preferred due to its advantages. However, it is necessary to improve the wear and corrosion properties in order to develop the areas of use in the automotive, aircraft, and space industries. For this purpose, after the surface preparation of the main material WE43 Mg alloy, ZnO and ZrO2 coatings were made and characterized in this study. The surface morphology and structural and chemical properties of the samples were investigated using profilometry, contact angle tests, scanning electron microscopy, and x-ray diffraction. Corrosion tests have been carried out. In order to determine the wear performance of the samples, the wear-related volume losses were measured and the friction coefficients were compared. Layers with 2-6 mu m coating thickness were obtained homogeneously on the polished and sandblasted sample surfaces. It was determined that the coating layers grew in the form of columns and did not contain capillary cracks. As a result of the study, it was observed that the ZnO-coated samples had the highest wear and corrosion resistance, and the wear and corrosion resistance of the coatings and magnesium alloy substrates improved.
Fe-Cr-C-V hardfacing coatings with molybdenum addition: Wear, corrosion, and cavitation performances
Çömez, N; Yurddaskal, M; Gül, C; Durmus, H; Albayrak, S
The purpose of this study was to determine how molybdenum content affected the hardfacing coatings made of Fe-Cr-C-V that resist wear, corrosion, and cavitation. The hardfacing process was applied on the S235JR steel by the metal arc welding method. Apart from the chromium-rich M23C6 and M7C3 (M: Cr, Fe) carbides, the presence of molybdenum led to the development of M2C (M: Mo, Fe, Cr) carbides. As molybdenum and carbon concentration decreased, the size and volume fraction of M23C6 and M7C3 carbides tended to reduce. While molybdenum did not significantly alter hardness or wear resistance, it was found to be advantageous in terms of cavitation and corrosion. The coating, including 3 wt% FeMo, demonstrated a 20-fold increase in cavitation resistance compared to the coating devoid of molybdenum. The hardfacing coatings' resistance to corrosion was increased by up to 4.5 times with the addition of molybdenum.
Wear performance of Fe-Cr-C-B hardfacing coatings: Dry sand/rubber wheel test and ball-on-disc test
Durmus, H; Çömez, N; Gül, C; Yurddaskal, M; Yurddaskal, M
Minimizing wear would ensure reduced loss of material, labor and time for numerous branches of industry. Hardfacing coating method is a promising application to overcome this loss. The purpose of the the hardfacing application is to support, repair or improve the surface that is susceptible to abrasion by forming hard phases. The present study was aimed to investigate the wear resistance of iron-based hardfacing coatings which were produced with Fe-Cr-C-B and Fe-Cr-C based filler wires, according to ball-on-disc and dry sand rubber wheel wear tests. During the open arc welding process powder compositions of 100% FeB and 40% FeB + 60% FeCr were transferred to the weld pool, in order to enrich the coating with boron and chromium. Increased FeB content ensured the formation of boride phases such as Fe2B, CrB2, B6Fe23, Cr5B3. Minimum wear loss was obtained in a sample which was coated with Fe-Cr-C-B based filler wire reinforced with 40% FeB + 60% FeCr powder. Formation of massive carbide/boride phases and a tough matrix protected by the high amount of secondary carbides increased the wear resistance. The outcomes showed that the wear resistance is not only correlated with hardness but also affected by the morphology of microstructural constituents.
Artificial Neural Network (ANN) Approach to Hardness Prediction of Aged Aluminium 2024 and 6063 Alloys
Meyveci, A; Karacan, I; Durmus, H; Caligülü, U
In this study, the effect of aging heat treatment on the hardness of AA 2024 and AA 6063 aluminum alloys was investigated by experimental and an Artificial Neural Network (ANN). AA 2024 and AA 6063 aluminum alloys were solution treated at two different temperatures of 490 degrees C and 520 degrees C. Then both samples were cooled to room temperature. After this process, the samples were aged at three different temperatures (140 degrees C, 180 degrees C, 220 degrees C) for ten different periods of time (2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 h.). The experimental results were trained in an ANNs program, and the results were compared with experimental values. It is observed that the experimental results coincided with the ANNs results.
Microstructure and Mechanical Properties of Ni Matrix B4C Reinforced Functionally Graded Composites
Caligulu, U; Durmus, H; Akkas, M; Sahin, B
In this study, microstructure and mechanical properties of nickel matrix B4C reinforced functionally graded composites produced by powder metallurgy method were investigated. Samples with Ni+5% B4C, Ni +10% B4C, Ni+ 15% B4C and Ni+ 20% B4C compositions were sintered at 900 and 1050 degrees C for 60 minutes. Microhardness and wear tests along with optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD) analyses were carried out to determine the mechanical properties, microstructure and phase composition of the samples. The results indicated that hardness and wear resistance increased with increases of B4C amount in nickel matrix.
Effect of solutionizing and quenching treatment on Ti6Al4V alloy: a study on wear, cavitation erosion and corrosion resistance
Çömez, N; Yurddaskal, M; Durmus, H
Titanium alloys are preferred in many engineering applications due to their high specific strength and superior corrosion resistance. However, its abrasion resistance is not very high and it limits the use of titanium alloys. The aim of this study is to examine the effect of solutionizing temperature on microstructure, hardness, wear, cavitation resistance and corrosion behavior of the Ti6Al4V alloy. For this purpose, quenching in water (WQ) was carried out by solutionizing the Ti6Al4V alloy at the temperatures 1050 and 960 degrees C containing the beta-transus and beta + alpha regions, respectively. The hardness of Ti6Al4V alloy increased with increasing heat treatment (HT) temperature. Depending on the increased hardness value, the highest wear resistance was observed in the specimen, which was heat treated at 1050 degrees C for 1 h and quenched. However, maximum cavitation resistance was observed in the specimen, which was heat treated at 960 degrees C for 1 h and quenched. The non-heat treated specimen exhibited the minimum cavitation resistance. Corrosion rate values were determined as 1.85, 0.66 and 0.46 9 10(-3) mm/year for non-heat treated, 960 and 1050 degrees C heat treated + quenched specimens, respectively. It has been determined that heat treatment reduces the corrosion rate 3-4 times.
Al/Zn/Al2O3 and Zn/Al2O3 Coatings by Cold Spray Coating Method of WE43 Magnesium Alloy and Investigation of Its Wear Behaviors
Gül, C; Albayrak, S; Çömez, N; Durmus, H
Mg alloys are preferred in automotive, aircraft, aerospace and communication industries due to their low specific gravity and high strength. WE series is a series of Mg alloys containing Mg, Y, Nd, rare earth elements, and although the creep strength is good for this alloy series, the wear resistance is open to improvement. The aim of this study is to develop coatings that can increase the wear resistance of WE43 Mg alloys, which have a high potential for use due to their specific gravity, by using a method that can be easily applied in the industry. For this purpose, using the cold spray coating method, magnesium alloys, whose surfaces are highly active, are provided to be coated without oxidation and wear resistance is improved. In the study carried out, WE43 Mg alloys, which roughen the surfaces by fine sandblasting process, were used with cold spray method, using powders containing Al/Zn/Al2O3 and Zn/Al2O3 and trade names DYMET K-20-11 and DYMET K-00-11, respectively, using N2 shielding gas at 500 degrees C. 6 g/min for powders delivered to supersonic speeds under the atmosphere. The powder was sprayed onto the substrates using the feed rate. Morphological analysis of the coated and uncoated samples with different contents were examined by SEM, XRD methods, the coating thicknesses were measured with SEM images taken from the section, and the percentages of the elements were determined by EDS analysis. In addition, ball-on disc wear tests were performed to examine the wear performance and volume losses were evaluated. As a result, the wear loss of WE43 alloys was reduced by approximately 40% compared to the uncoated condition, thanks to the cold spray coatings.
Characterization of SiO2 Sol-Gel Coated Ti6Al4V Alloy Obtained by using TEOS and GPTMS
Gul, C; Albayrak, S; Durmus, H; Cömez, N
Synthesis of silicon oxide (SiO2) via the sol-gel method and SiO2 coating ability on to Ti6Al4V alloy were investigated, in the novel study. Ti6Al4V alloy is the most used alloy in biomedical applications due to its many advantages. However, it has a minor disadvantage like releasing ions into the human body. In this study, the substrate material Ti6Al4V alloy samples were coated using the sol-gel method with alkoxysilane solutions (tetraethyl orthosilicate, TEOS; Si(OC2H5)(4) and glycidoxypropyltrimethoxysilane, GPTMS; C9H20O5Si) containing the unit of prepared Si(OR)(n) after the surface preparations were made. The prepared solutions were examined using thermal analysis methods and the process temperatures to be applied to the coatings were determined according to the results of the analysis. Coated samples were subjected to aging, drying, and sintering processes at specified temperatures. The morphologies and structures of the samples were investigated by using a scanning electron microscope with energy-dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). The sol-gel coating ability of the silicon oxide on the surface of the Ti6Al4V alloys has been discussed. The results demonstrate that cracks were observed in coating produced by TEOS precursor whereas the coatings used GPTMS precursor exhibited crack-free surface independently of dipping number. The crack formation tended to reduce with increasing dipping number of coatings produced by TEOS precursor. Distances between coating islets gradually became smaller as the number of dippings increased, and the continuity of the coatings increased. It has been observed that SiO2 coating layers produced with GPTMS are obtained in a more continuous and crack-free form than the layers produced with TEOS.
Cold metal transfer welding of AA1050 aluminum thin sheets
Irizalp, AO; Durmus, H; Yüksel, N; Türkmen, I
This study was aimed to investigate the welding parameters on mechanical behavior of 2 mm thick AA1050 sheet materials joined by cold metal transfer (CMT) method. Macro structural examination showed that decreasing heat input decreased the pore size in the weld metal. Tensile test was applied and failure occurred in heat affected zone of aluminum sheet metal. Maximum tensile strength was found in the sample with minimum heat input. Heat affected zone was observed explicitly in the sample produced with the maximum heat input. Decreasing joint gap affected the bending strength positively. Bending strength was found superior with maximum bonding line length.
Effect of Mill Type on Morphology of AA6013 Aluminium Powder
Uzun, RO; Durmus, H
In conventional recycling method, metal chips are cast after pressing and melting in electric arc furnace. Material loss occurs during the recycling from liquid metal due to the several reasons. Direct recycling method which produces the aluminium powder from aluminium chips using mechanical mill can be an alternative to conventional recycling method. Thus material and energy losses, and labour cost will be reduced by direct recycling method without melting. In this study, the particle morphology of powder direct recycled from AA6013 aluminium alloy chips with cryogenic, disc and ball type grinders is investigated. Mechanical milling resulted flaky and irregular shaped AA6013 particles. It was ascertained that the chips did not break sufficiently in despite of the long duration milling mechanisms by ball mill. Cryogenic mill provides the energy required for milling mechanisms to act. Disc mill has the highest impact energy was determined. Consequently, efficiency of ball mill is lower than the efficiency of cryogenic and disc type mills. Shape factors of powders produced with ball and cryogenic mills were found greater than that of the powder produced by disc mill. Disc mill has the most efficient and effective impact energy which produces the smaller particles per minute, was determined.
Weldability of AL99-SiC Composites by CO2 Laser Welding
Durmus, H; Meriç, C
In this study, Al99-SiC composites were produced using PM method. In the composites produced, the reinforcement rates of SiC were 0, 5, 10, and 20 (%wt). The matrix Al 99 powders were mechanically mixed with SiC particulates. These powders were compacted at room temperature at 500 MPa for 5 x 10 x 60 mm specimens and followed by sintering at 600 and 620 degrees C for 1 h. Composite specimens were joined by CO2 laser welding method. Rofin-Sinar SM2000 machine was used for the welding process. The microstructure of melted region was investigated by optical, scanning, and X-ray microchemical analysis techniques. The hardness test, tensile test, and three-point bend test results were presented. The effect to CO2 laser welding method at different reinforcement rates and different sintering temperatures in Al 99 powder was investigated. Because of the lower thermal conductivity of Al99-SiC composites, melting zone is wide. It was observed that 0.5 m/min laser welding velocity was suitable for composites with low SiC rate (0% and 5% SiC), and with increasing SiC (10 and 20%), laser welding velocity of 0.3 m/min was suitable.
Tribological and mechanical properties of Al alloyed bearings
Ünlü, BS; Durmus, H; Akgün, S
Aluminum based alloys are widely used as journal bearing materials in tribological applications. Duralumines, AlMgSi are widely used as journal bearing materials for aluminum based alloys. These alloys provide properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured from aluminum alloys were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for the total of 150 min by using radial journal bearing wear test rig. Wear resistance of AI alloyed bearings increased about 2-3 times and journal wear resistance increased about 2-8 times. The highest bearing wear rate occurred in pure AI bearings while the lowest bearing wear rate occurred in AlMgsi bearing. (C) 2009 Elsevier B.V. All rights reserved.
Effects of Al2O3 Particles on Corrosion Behavior and Microstructure of Al-Al2O3 Composites and Texture of Aluminum Matrix
Dehrib, S; Zazi, N; Durmus, H
In this paper, we studied the influence of alumina particles addition, 5, 10, and 15 wt %, on the microstructure after elaboration of Al-Al2O3 MMC composite, morphology and kinetic of corrosion, hardness, texture evolution of aluminum matrix. The results show distribution of alumina particles in shape of petal-like phase in some zones , in form of flack in another region for sample with 5% addition alumina, and in mixture between truncated petal-like phase and flake form particles for the sample with 10% addition of alumina, of flake in zone 1 one and a mixture of petal-like phase and flake in zone 2 for the sample with 15% addition of Al2O3, the samples with 5 and 10% Al2O3 were undergo generalized corrosion almost in the all surfaces, but for the sample with 15% addition of was undergo the corrosion which don't tends to generalized corrosion. The corrosion resistance increase when the Al2O3 addition increases. The texture of aluminum changes slightly when the alumina powders are added to aluminum. The hardness change when alumina powders are added to aluminum.

Browsing by Author "Durmus, H"

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