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Öğe Abrasive wear model for Al2O3 particle reinforced MMCs using Genetic Expression Programming(2010) Kök, Metin; Kanca, ErdoganIn this investigation, a new model was developed to predict the wear rate of Al2O3 particle-reinforced aluminum alloy composites by Genetic Expression Programming (GEP). The training and testing data sets were obtained from the well established abrasive wear test results. The volume fraction of particle, particle size of reinforcement, abrasive grain size and sliding distance were used as independent input variables, while wear rate (WR) as dependent output variable. Different models for wear rate were predicted on the basis of training data set using genetic programming and accuracy of the best model was proved with testing data set. The two-body abrasive wear tests of the specimens was performed using a pin-on-disc abrasion test apparatus where the sample slid against different SiC abrasives under the loads of 2N at the room conditions. The test results showed that GEP model has produced correlation coefficient (R) values about 0.988 for the training data and 0.987 for the test data. The predicted wear rate results were compared with experimental results and found to be in good agreement with the experimentally observed ones. Copyright © 2010 Tech Science Press.Öğe Characteristics and high temperature wear behavior of chrome vanadium carbide composite coatings produced by thermo-reactive diffusion(Elsevier Science Sa, 2020) Gunen, Ali; Kalkandelen, Muge; Gok, Mustafa Sabri; Kanca, Erdogan; Kurt, Bulent; Karakas, Mustafa Serdar; Karahan, Ismail HakkiIn this study, Cr-V-C composite carbide layers were grown on the surface of a GGG-80 ductile iron using thermoreactive diffusion (TRD). The TRD process was carried out at temperatures of 900, 1000, and 1100 degrees C for 1 h using nano-sized Fe-V and Fe-Cr powders. The coatings were characterized by X-ray diffractometry (XRD), 2D profilometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), microhardness measurements, nanoindentation, and wear tests. The wear tests were performed on untreated and coated samples using a ball-on-disc type wear tester under 10 N load at four different temperatures (25 degrees C, 250 degrees C, 500 degrees C and 750 degrees C) against a 6-mm WC ball. Metallographic investigations revealed that the graphite nodules near the surface were dissolved as a result of the TRD process. Depending on the TRD process temperature, a coating with a thickness of 12-36 mu m, hardness of 24.14-31.38 GPa, and elastic modulus of 198-233 GPa was obtained. An increase in process temperature increased the thickness, hardness, and elastic modulus of the obtained Cr-V-C layers, which resulted in low friction coefficient values and decreased wear rates. Although all coated samples showed improved wear resistance in all wear test conditions, the wear rates were significantly increased at 750 degrees C due to flaking.Öğe Characterization of electrodeposited Ni-Cr/hBN composite coatings(Elsevier Science Sa, 2020) Demir, Mehmet; Kanca, Erdogan; Karahan, Ismail HakkiIn 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. (c) 2020 Elsevier B.V. All rights reserved.Öğe A Comparative Study on the Effects of Different Thermochemical Coating Techniques on Corrosion Resistance of STKM-13A Steel(Springer, 2018) Gunen, Ali; Kanca, Yusuf; Karahan, Ismail Hakki; Karakas, Mustafa Serdar; Gok, Mustafa Sabri; Kanca, Erdogan; Curuk, AhmetThe corrosion resistances of three different thermochemical coatings (grown using titanizing, boriding, and borotitanizing treatments) applied to STKM-13A steel surfaces were investigated. The coatings were characterized using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, 2D profilometry, and microhardness experiments. The corrosion tests were conducted using both electrochemical and static immersion methods, in 3.5 pct NaCl and 40 pct HF acid solutions, respectively. The corrosion resistance of STKM-13A steel was enhanced after the coating process. The specimens were exposed to more corrosion in the HF solution than in the NaCl solution. The best corrosion resistance was obtained in the borotitanized and borided specimens immersed in the NaCl and HF solutions, respectively. The borided STKM-13A steel sample showed even less cumulative weight loss than Inconel 625 in the static immersion HF acid solution test. This suggests potential use of the borided STKM-13A steel in the uranium production units of nuclear power plants as an alternative to more costly alternatives such as Monel, Inconel, and Hastelloy. (C) The Minerals, Metals & Materials Society and ASM International 2018Öğe The effect of process conditions in heat-assisted boronizing treatment on the tensile and bending strength characteristics of the AISI-304 austenitic stainless steel(Maik Nauka/Interperiodica/Springer, 2015) Gunen, Ali; Kurt, Bulent; Somunkiran, Ilyas; Kanca, Erdogan; Orhan, NuriIn this study, AISI 304 austenitic stainless steel surface was boronized with nanoboron and ekabor-III powders at 950 and 1000A degrees C for 2 and 4 hours period by solid-state box boronizing method. Then, behaviors of the boronized specimen in the microstructure, three-point bending, and tensile strength characteristics were investigated. As a result of the boriding process, the boride layer thickness in the range of 23-67 A mu m and microhardness value in the range of 1020-2200 HV have been obtained according to the increase in processing time and temperature and to the particle size of the boron source (0, 1). The coating layer on boronized specimens did not exhibit any sign of reaction caused by the tensile strength applied until the yield point was in both tests. Although the particle size of the boron agents was more effective on the boronized specimen's bending and tensile strength behaviors, it was observed that processing temperature and its duration are effective as well.Öğe Effect of saccharin addition on formation, wear and corrosion resistance of electrodeposited Ni-Cr coatings(Sciendo, 2023) Demir, Mehmet; Kanca, Erdogan; Karahan, Ismail HakkiNumerous factors play a pivotal role in shaping the mechanical and corrosion resistance properties of electrodeposited Ni-Cr alloy coatings. This study delves into the deposition of Ni-Cr alloy coatings on AISI 1040 steel, examining the influence of saccharin additives within the electrodeposition bath. Specifically, the concentration of saccharin within the solution was varied over a range of 0 to 2 g/l. Following the electrodeposition process, a comprehensive array of characterization techniques was employed, encompassing 2D surface roughness analysis, scanning electron microscopy, X-ray diffraction, nanoindentation, energy-dispersive X-ray spectroscopy and assessments of wear and corrosion performance. The characterization results of this article reveal a compelling difference between saccharin-free Ni-Cr coatings and their saccharin-modified counterparts. Notably, microcracks, a common occurrence in saccharin-free coatings, were suppressed in the saccharin-modified Ni-Cr coatings. Additionally, the latter exhibited a smoother and more uniform surface texture. A crucial observation was that the introduction of saccharin into the bath was directly associated with an increased incorporation of chromium within the coatings, resulting in higher nanohardness values. Furthermore, the residual stress within the coatings shifted from tensile to compression as saccharin concentrations increased. Concurrently, surface roughness and wear rates exhibited a consistent downward trend with increasing saccharin concentrations in the solution. The most significant findings were seen in the domain of corrosion resistance. Saccharin-modified Ni-Cr coatings outperformed the bare steel substrate and saccharin-free Ni-Cr coatings. Intriguingly, the enhancement of corrosion resistance was not linearly proportional to saccharin concentration; the optimal corrosion resistance was achieved at a concentration of 1 g/l.Öğe Effect of thermal degradation on the properties and wear behavior of Cr-V-C composite coatings grown on ductile iron(Elsevier Science Sa, 2021) Gunen, Ali; Kanca, Erdogan; Karakas, Mustafa Serdar; Gok, Mustafa Sabri; Kalkandelen, Muge; Kurt, Bulent; Cetin, MelikThe thermal fatigue behavior of chromium vanadium carbide (Cr - V - C) coatings and the wear of the coatings after thermal fatigue cycling was studied. The Cr - V - C coatings were grown on the surface of a ductile iron using thermo-reactive diffusion (TRD) and subjected to thermal fatigue in the temperature range of 25 to 750 degrees C for up to 500 cycles. Characterizations were made using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, microhardness measurements and wear tests. The Cr - V - C coated samples displayed superior thermal fatigue and wear resistance compared to the untreated ductile iron, mainly due to the dissolution of graphite nodules in the vicinity of the surface during TRD. The dissolution of graphite reduced the possibility of failure initiating from graphite nodules and graphite-matrix interfaces. Increasing the number of cycles resulted in increased flaking and decreased wear resistance in both the Cr - V - C coatings as well as the untreated ductile iron. Although much of the Cr V C coating was lost (due to flaking) after thermal cycling, the absence of graphite near the surface still provided improved resistance to wear in the TRD-treated samples. The results of this study indicate that TRD coatings hold great promise for use in the industrial applications.Öğe The investigation of corrosion behavior of borided AISI 304 austenitic stainless steel with nanoboron powder(Maik Nauka/Interperiodica/Springer, 2014) Gunen, Ali; Kurt, Bulent; Orhan, Nuri; Kanca, ErdoganIn this study, corrosion behavior and mechanical properties of AISI 304 austenitic stainless steel, which was borided with Nanoboron powder, was investigated. The commercially available steel was subjected to a boriding treatment with a size of 10-50 nm Nanoboron powders, at the temperatures of 1223 K to 1273 K with boriding durations of 2 to 4 h. Microstructure characterization of the steel was carried out with optical microscopy, scanning electron microscopy, microhardness and X-ray diffraction analyses. Corrosion tests were made by static immersion into a 10% H2SO4 acid solution and weight loss calculations as well as salt spray tests were carried out in accord with the ASTM B-117 standard. Boriding thermal treatment, increased the corrosion resistance of the steel against the acid solution, up to about 4.3 times while in the salt spray tests, weight loss corrosion resistance increased up to tier 2. However, anti-corrosion resistance decreased by 40%, its untreated value.Öğe Phase evolution in Fe Mn Si shape memory alloys due to forging speed(2013) Eskil, Murat; Kanca, ErdoganThe objective of this investigation is to compare the crystallographic characteristics of two different compositions of Fe-Mn-Si alloys forged with the newly designed and constructed High Energy Rate Forming (HERF) hammer with conventional hydraulic and mechanical presses. The degree of martensite formation may depend on metal forming conditions. For both of the alloys, one of the specimens was investigated in as «prepared form», the other specimen was investigated after air cooling with homogenization treatment and three specimens were deformed in different velocities after homogenization treatments. The changes which occurred in the transformation parameters of two FeMnSi alloys with different compositions due to the effects of thermal and mechanical procedures have been studied by using X-ray diffraction. In the alloy specimens cooled to different conditions from the high-temperature ? phase region, ??? and ?????? martensitic transformations were observed. The lattice parameters (LP) of fcc ? and hcp ? structures were determined, and changes in forging speed on the LPs were found. © 2013 World Scientific Publishing Company.Öğe Prediction of surface roughness in abrasive waterjet machining of particle reinforced MMCs using genetic expression programming(Springer London Ltd, 2011) Kok, Metin; Kanca, Erdogan; Eyercioglu, OmerMachining of particle-reinforced metal matrix composites has been considerably difficult due to the extremely abrasive nature of the reinforcements that causes rapid tool wear and high machining cost. Abrasive water jet (AWJ) machining has proven to be a viable technique to machine such materials compared to conventional machining processes. The present study is focused on the surface roughness of AWJ cut surfaces and genetic expression programming (GEP) was proposed to predict surface roughness in AWJ machining of 7075 Al alloy composites reinforced with Al2O3 particles. In the development predictive models, characteristics of materials such as size and weight fraction of reinforcement particles, and depth of cut were considered as model variables. The training and testing data sets were obtained from the well-established machining test results. The weight fraction of particle, size of particle, and depth of cut were used as independent input variables, while arithmetic mean of surface roughness, maximum roughness of profile height, and mean spacing of profile irregularity as dependent output variables. Different models for the output variables were predicted on the basis of training data set using GEP and accuracy of the best model was proved with testing data set. The test results showed that output variables increased with increasing input variables. The predicted results were compared with experimental results and found to be in good agreement with the experimentally observed ones.Öğe Properties and Corrosion Behavior of Chromium and Vanadium Carbide Composite Coatings Produced on Ductile Cast Iron by Thermoreactive Diffusion Technique(Asme, 2020) Gunen, Ali; Kalkandelen, Muge; Karahan, Ismail Hakki; Kurt, Bulent; Kanca, Erdogan; Gok, Mustafa Sabri; Karakas, Mustafa SerdarDuctile 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 degrees 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 the nodular graphite in the surface was dissolved at the TRD process temperatures and that a coating of 12-36 mu m thickness and 2461-3200 HV0.05 hardness was obtained. The corrosion resistance of the composite coating was up to 10, 33.5, and 75 times higher than the uncoated GGG-80 in NaCl, H2SO4, and HNO3, respectively. The improvement in corrosion resistance was a direct result of the formation of complex carbides and the elimination of graphite nodules in the surface of the alloy.
