Motorlu Araçlar ve Ulaştırma Teknolojileri Bölümü, Makale Koleksiyonu

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https://hdl.handle.net/11492/3480

Listeleniyor 1 - 20 / 24

Experimentally detected aerodynamic drag coefficient of the agricultural tractor form considering effects of windshield angle and hood front shape
(Elsevier Ltd., 2024) Küçüksarıyıldız, Hanifi; Canlı, Eyüb; Carman, Kazim
Agricultural tractors are improving their capacity, speed, and performance. However, the characteristic form of the agricultural tractors is not known in terms of aerodynamics. This is required in modeling transportational duties and their impacts on energy and environment, especially considering tractor-trailer couples. In this work, this characteristic form solely investigated apart from the couple to base a foundation. The geometry was adapted from a commercial model. The model was simplified greatly to isolate numerous parameters yielding a generic shape. Only geometrical features as parameters were selected as the nose shape as the leading surface and the windshield angle. Scaled models were tested in a wind tunnel. Drag coefficients independent from Reynolds number, drag forces, pressure distributions on the symmetry planes and pressure coefficients were obtained. An extrapolation was made in order to predict drag force related fuel consumption and CO2 emission for a full-scale tractor on-road transportation scenario based on experimentally obtained drag coefficient. It is understood that changes in tractor front surface topology and wind shield angle can lead to drag changes up to 3%. A 0.72 value of drag coefficient may be assumed for the generic agricultural tractor form. Based on this value, an on-road agricultural tractor cruising with 70 km h−1 is predicted to have a drag sourced fuel consumption of 3.9 kg h−1 and CO2 emission of 10.19 kg h−1. Tractor trailer couples and their platoons are of interest in terms of research and computational simulations that may utilize present results as validator.
Effect of diesel injection pressure for enhancing combustion and reducing mechanical vibration and noise emissions in a non-road diesel engine
(2023) Gülcan, Halil Erdi; Gültekin, Nurullah; Ciniviz, Murat
In this study, the combustion, performance, emissions, noise, and vibration characteristics of a single-cylinder, four-stroke, air-cooled diesel engine used for non-road purposes were investigated by controlling different injection pressures with a common rail fuel injection system. The aim of this study is to enhance the combustion performance and improve the existing noise and vibration levels of this commonly used non-road diesel engine in fields such as agriculture, wetlands, and the construction sector by optimizing the injection pressure. The experiments were conducted under low and medium load conditions and at a constant engine speed. The single-cylinder, non-road engine's fuel injection system was controlled using a common rail fuel delivery system, and four different diesel injection pressures (250, 300, 350, and 400 bar) were utilized. The experimental results have shown that the combustion performance, emissions, noise, and vibration values of the non-road diesel engine improved with an increase in diesel injection pressure (DIP). Increasing DIP led to higher maximum combustion pressures and resulted in reductions of HC, CO, and smoke emissions by up to 25%, 48%, and 59%, respectively. Vibration values also decreased by up to 25%.
Experimental investigation of the effect of hydrogen ratio on engine performance and emissions in a compression ignition single cylinder engine with electronically controlled hydrogen-diesel dual fuel system
(Elsevier Ltd, 2023) Gültekin, Nurullah; Ciniviz, Murat
In recent years, there has been a rapid transition from internal combustion engines to hybrid and electric vehicles. It is an inevitable fact that the dominance of internal combustion engines in the market will continue for many years due to the charging and battery problems in these vehicles. Therefore, it is an important issue to improve the performance and emissions of internal combustion engines by making them work with alternative energy sources. In this study, hydrogen-diesel dual fuel mode was used in a dual-fuel compression ignition single cylinder engine with common rail fuel injection system and electronically controlled gas fuel system. The study was carried out at constant speed (1850 rpm), different load (3-4.5-6-7.5-9 Nm) and different hydrogen injector opening amounts (1.6-1.8-2.0 ms). The effects of hydrogen energy ratios obtained with different hydrogen injector opening amount on engine performance and emissions were examined. According to the results, it was determined that the in-cylinder pressure values increased at medium and high loads, and the specific energy consumption decreased. When the emission values were examined, it was determined that there was an increase in NO emissions and a significant decrease in other emissions. However, increasing the hydrogen energy ratio above 14% adversely affected engine performance and emissions.
Examination of the effect of combustion chamber geometry and mixing ratio on engine performance and emissions in a hydrogen-diesel dual-fuel compression-ignition engine
(Elsevier Ltd, 2022) Gültekin, Nurullah; Ciniviz, Murat
The fact that fossil fuels, which supply a large amount of the energy need, are limited in the world and can be only found in certain regions, have led humankind to seek alternatives. In addition, the use of fossil fuels generates wastes detrimental to humans and nature, which has led this search to alternative, clean and renewable energy sources. The use of hydrogen, which is a clean energy source, in internal combustion engines is very important in terms of reducing emission values as well as providing an alternative to petroleum-derived fuels. This study presents a literature review on the effect of the hydrogen ratio and combustion chamber geometry on the engine performance and emissions in a compression-ignition engine operating in the hydrogen diesel bi-fuel mode. As a result of the study, it was concluded that the hydrogen energy ratio should be between 5 and 20% and the combustion chamber should be designed by considering the combustion characteristics. The main purpose of the study is to highlight the functionality of the use of hydrogen in dual fuel mode in compression ignition engines and to be a resource for researchers who will work on this subject.
Prediction of specific fuel consumption of 60 HP 2WD tractor using artificial neural networks
(2021) Küçüksarıyıldız, Hanifi; Çarman, Kazım; Sabancı, Kadir
In this study, specific fuel consumption was determined at different axle load, tirepressure and drawbar force for a 60 HP tractor. In addition, the results were also estimated with the help of Artificial Neural Networks (ANN), which is one of the machine learning methods. The testings were carried out on the Tractor Draft Test Track. In the study; three different drive tire inner pressures (P) (160 kPa, 120 kPa and 80 kPa), four differentdynamic axle loads (W) (1796 daN, 2076 daN, 2276 daN, 2476 daN) and four different traction forces (500 daN,1000 daN, 1500 daN, 2000 daN) were tested. Specific fuelconsump-tion values varied between 290.7-542.1 g/kWh depending on the draft force in the testings Despite the 38% increase in the axle load, a 3.5% decrease occurred in the specific fuel consumption values. Specific fuel consumption values in-creased whenincreased tire inner pressure. Specific fuel consumption in-creased by 1.03% when a 100% increase in tire pressure. In ANN, the most suc-cessful model was determined by trying different training algorithms, transfer functions and the number of neurons in the hidden layer. In the most successful network model, MAE, RMSE values for the prediction of specific fuel consump-tion were found to be 0.005331, 0.007551 respectively.
Impact assessment of new generation high-speed agricultural tractor aerodynamics on transportation fuel consumption and related phenomena
(Springer Heidelberg, 2022) Canlı, Eyüp; Küçüksarıyıldız, Hanifi; Carman, Kazım
New generation agricultural tractors contribute to transportation by increased travel speeds. There is not any available aerodynamic data on the authentic agricultural tractor form. On-road transportation by tractors is between 8 and 30% of their operational time. In this work, two agricultural tractors are modelled via computational fluid dynamics for nine different speeds to determine aerodynamic resistances. Constant speed travel scenarios are analyzed. Corresponding speeds are 5 and 10 to 80 km/h with 10 km/h increments. Reynolds number changes between 1.6 x 10(5) and 2.98 x 10(6). The characteristic lengths are taken as the square root of the streamwise projected area of the tractor geometries. Aerodynamic forces exerted on the tractors change between 3 and 746 N. The calculated drag coefficients are found as independent from Reynolds number and are 0.6 and 0.78 for the two different types of driver compartments. The approximated aerodynamic related fuel consumptions for 1-h changes between 0.002 and 8.28 lt/s which correspond to 0.001 to 5.76 kg/s carbon emission. A potential improvement in decreasing aerodynamic resistance about 20% is discussed by spatial data. Since the conducted work is being regarded as the first instance in the literature, it is estimated that several consecutive reports will be triggered.
Determination of abrasion resistance of Fe28Cr5C1Mn coating applied to 30MnB5 boron alloy cultivator blades via electric arc spray
(SAGE Publications Ltd., 2022) Güney, Bekir; Dilay, Yusuf
The poor abrasive wear behavior of agricultural machinery affects the farmers all over the world, rendering their activities more inefficient and negatively affecting their productivity. Therefore, innovation in the manufacture of soil cultivation machinery and the selection of wear-resistant materials has been of great importance. Recently, boron alloys, in particular, have been used in the manufacture of machinery parts that work the soil. The aim of this was to investigate the behavior of the blades of the machines widely used in soil cultivation in agricultural production following a surface treatment technique. For this purpose, the blades made of 30MnB5, a material widely used in the production of cultivator blades, were used as substrate samples in the trials as well as blades of the same substrate coated with Fe28Cr5C1Mn alloy wire via the electric arc spray technique. The morphologies and structures of the uncoated and coated samples were comprehensively analyzed by light microscopy, scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. In addition, their microhardness, porosity, and surface roughness properties were assessed separately before and after plowing. These prepared blades were tested under in the same conditions by plowing the same field at two different soil moisture. Although the weight loss was measured as 9.4 g and 5.4 g in the uncoated and in the coated sample at 9% moisture level, respectively, the weight losses were at 14% humidity level were 10.6 g and 5.9 g in the uncoated and coated samples, respectively. Although the amount of wear increased with increasing humidity levels in both groups, the mass wear loss in cultivator blades coated with Fe25Cr5C1Mn alloy wire was found to be lower in all trials. The results suggest that coating the cultivator blades using electric arc spray would increase agricultural productivity and reduce factors that cause environmental pollution.
Wear properties and microstructure of WC-10Co-4Cr powder coating applied to cultivator blades via hvof
(World Scientific, 2022) Dilay, Yusuf; Güney, Bekir; Özkan, Adem
Abrasion of cultivator equipment parts working in the soil causes serious losses if necessary precautions are not taken. The cultivator blades used to plow the soil in agricultural production wear out over time. In order to reduce this wear, the hardness and wear resistance of the material should be increased first. In this study, some of the 30MnB5 cultivator blades were heat-treated and some were coated with HVOF technique. The samples were obtained by plowing the soil at 15-cm working depth and 5.4-kmh-1 forward speed in two fields with different soil moisture contents. As a result of the experiments, abrasion losses and surface deformation of the blade material were observed and the effect of soil moisture on wear was also determined. After the treatment of 49.5daa (decare) with soil at 9% moisture content, the heat-treated 30MnB5 sample was worn 5.6 g, and the sample coated with WC-10Co-4Cr was worn 3.2g. Abrasions at 14% soil moisture were 6.3 g and 3.6g, respectively. It was observed that the coated material was less corroded than the heat-treated material. While the results obtained will contribute to the prevention of economic losses, the release of metals into the soil will also be prevented.
Corrosion characteristics of plasma spray, arc spray, high velocity oxygen fuel, and diamond jet coated 30MnB5 boron alloyed steel in 3.5 wt.% NaCl solution
(De Gruyter Open Ltd., 2021) Güney, Bekir; Dilay, Yusuf; Solomon, M. M.; Gerengi, Hüsnü; Özkan, Adem; Yıldız, Mesut
30MnB5 boron alloyed steel surface is coated using different coating techniques, namely 60(Ni-15Cr-4.4Si-3.5Fe-3.2B 0.7C)-40(WC 12Co) metallic powder plasma spray, Fe-28Cr-5C-1Mn alloy wire arc spray, WC-10Co-4Cr (thick) powder high velocity oxy-fuel (HVOF), and WC-10Co-4Cr (fine) diamond jet HVOF. The microstructure of the crude steel sample consists of ferrite and pearlite matrices and iron carbide structures. The intermediate binders are well bonded to the substrate for all coated surfaces. The arc spray coated surface shows the formation of lamellae. The cross-section of HVOF and diamond jet HVOF coated surfaces indicates the formation of WC, W2C Cr, and W parent matrix carbide structures. The corrosion characteristic of the coated steel has been investigated in 3.5 wt.% NaCl solution using electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDAX) techniques. The results reveal that the steel corroded in the medium despite the coatings. However, the extent of corrosion varies. HVOF coated sample demonstrated the highest corrosion resistance while arc spray coated sample exhibited the least. EDAX mapping reveals that the elements in the coatings corroded in the order of their standard electrode potential (SEP). Higher corrosion resistance of HVOF coated sample is linked to the low SEP of tungsten.
Microstructure and wear properties of WC-10Co-4Cr coating to cultivator blades by DJ-HVOF
(Ice Publishing, 2021) Dilay, Yusuf; Güney, Bekir; Özkan, Adem; Öz, Ali
The friction force in mechanical systems not only reduces their efficiency but also causes wear in the machine components, resulting in financial losses. As in every sector, in agricultural production, the problem of abrasion, particularly in soil tillage, is extremely important. Studies have been conducted examining the different methods for minimizing wear on tillage machinery. In this study, the cultivator blades of a boron-alloyed 30MnB5 steel substrate were coated with WC-10Co-4Cr ceramic powder by way of the Diamond Jet high-velocity oxygen-fuel (DJ-HVOF) technique. The microstructure of the sample and its wear properties under field conditions were then investigated. The microstructure, porosity, hardness, surface roughness and wear properties of the samples were revealed. The coating was observed to be well bonded, both mechanically and metallurgically, and the hardness of the coating was three times higher than that of the uncoated substrate material. In the field trials, the wear was found to be six times lower due to the hardness of the WC-10Co-4Cr coating and the hard carbide phases in its microstructure. As a result, the HVOF coating was shown to minimize wear, which is a big problem in tillage machinery. This can extend the economic life of machinery and make agricultural production more efficient.
Microstructural analysis of liquefied petroleum gas vehicle emissions, one of the anthropogenic environmental pollutants
(Springer, 2021) Güney, Bekir; Aladağ, Ali
Human health and a clean environment are undoubtedly of great importance all over the world. Currently, toxic exhaust emissions in the atmosphere are significantly increasing due to the more widespread use of motor vehicles. In this study, we aimed to characterize the microstructure and chemical properties of exhaust particles released from modified spark-ignition vehicles powered by liquefied petroleum gas fuel. For this purpose, particulate matter samples taken from vehicle exhausts in Karaman, Turkey, were analyzed via scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy and Fourier-transform infrared spectroscopy. Microscopic studies of these particles showed the particulate matter to have an ultra-thin (150-nm) nanostructure, whereas the energy-dispersive X-ray spectroscopy studies identified 18 element structures in the content, including carbon, oxygen and nitrogen. In addition, the morphology and crystallography of toxic structures such as hydrocarbons, nitrogen oxides, sulfur oxides and carbon dioxide were determined by the X-ray diffraction spectroscopy, and molecular bonds were revealed by the Fourier-transform infrared spectroscopy. Our results demonstrated that the exhaust emissions of all vehicles using petroleum-derived fuel contained harmful components at levels above those acceptable for environmental and human health. In addition, vehicles using liquefied petroleum gas as fuel produced relatively fewer harmful emissions compared to other vehicles. However, due to the low cost of liquefied petroleum gas, the more widespread use of these vehicles also significantly increases the amount of exhaust emissions, uncontrollably spreading pollutants into the atmosphere and causing environmental problems.
Corrosion and wear behaviour of HVOF spraying WC-12% Ni coating on gray cast-iron
(Natl Inst Science Communication-Niscair, 2021) Güney, Bekir
The coatings produced with high-velocity oxygen fuel spraying technology can greatly improve wear and corrosion resistance. In this study, WC-12% Ni coating was applied on the lamellar graphite cast iron substrate. Morphologies and structures of uncoated samples and sprayed coatings were analyzed with light microscopy, scanning electron microscope, energy dispersive spectrometry and X-ray diffraction. Although their micro-hardness, porosity, abrasion and corrosion properties were studied, wear experiments were performed at normal atmospheric conditions (under room temperature and 30% humidity) in the reciprocating wear testing machine. The corrosion resistance of the coatings was measured using potentio-dynamic polarization. The results revealed that the microstructure was porous, had micro-cracks, and contained some inhomogeneous structures such as carbide. Energy dispersive spectrometry analysis revealed that the presence of phases indicated the success in coating process. It was found that the WC-12% Ni coating exhibited lower potential and lower corrosion current density compared to those of the uncoated sample.
Microstructure analysis of welding fume of low and medium carbon steels
(CSIC Consejo Superior de Investigaciones Cientificas, 2021) Güney, Bekir
In this study, the sample of welding fume was obtained from low and medium carbon steels and the electrodes used in welding. The microstructures of the particles were analysed using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and fourier transform infrared spectrometer (FTIR). In the experiments; Be, O, F, Fe, Si, Cl, K, Ca, Ti, V, Cr, Mn were found to be atomically more than 1%. Based on this finding, it is revealed that the structure is composed mainly of oxides such as Fe2O3, Fe3O4, MnO2, TiO2, SiO2, Fe3Mn3O8, FeMn2O4, BeO, CrO. It was also found with XRD analysis that the elements which were found to beatomically less 1% formed oxide phases. Because oxidized structures threaten the environment and human health, it has been experimentally found that the metals and heavy metals emitted by welding fumes still keep polluting and threatening the environment. © 2021 CSIC Consejo Superior de Investigaciones Cientificas.
Dizel yakıtlı taşıtlardan salınan partikül maddelerin mikroyapı ve kimyasal karakterizasyonu
(TUBITAK, 2021) Güney, Bekir; Aladağ, Ali
Taşıt trafiğinden kaynaklanan egzoz emisyonları, taşıt kullanımı sırasında yakıtların, katkı maddelerinin yanması ve sistemindeki motor parçalarının aşınması nedeniyle havaya salınan parçacıkları ifade eder. Kirliliğin en önemli potansiyel kaynağı taşıt emisyonlarıdır. Dizel yakıtlı araçlar yaygın olarak kullanılmalarından dolayı, ulaştırma sektöründe egzoz gazı emisyonlarını arttırmaktadır. Bu emisyonlar motorlarda motor tipi, yakıt tipi ve yanma süreci gibi farklı şartlarda gaz halinden katılaşarak meydana gelmektedir. Bu motorlarda yanma sırasında yaklaşık 2000 0C sıcaklık meydana gelirken, egzoz hattında bu sıcaklık 1000 0C seviyelerine düşmektedir. Çevreye dahil olduğunda ise gerçek atmosferik sıcaklıkta seyretmektedir. Yüksek sıcaklıktan soğuyarak katılaşan partiküller oldukça farklı yapılar içermektedir. Bu çalışmanın amacı, gerçek atmosfere katılan komplex yapıların mikro yapı ve kimyasal özelliklerini ayrıntılı olarak tanımlamaktır. Çalışmada SEM, EDS, XRD ve FTIR teknikleriyle kullanılarak karakterizasyon yapılmıştır. Çalışma sonunda, dizel partikül kompozisyonunda hidrokarbon, azot oksit, karbon monoksit, organik esaslı mineral ve bileşiklerin farklı formlarda havayı kirletmeye devam ettiği tespit edilmiştir.
Microstructure and chemical analysis of vehicle brake wear particle emissions
(2020) Güney, Bekir; Öz, Ali
Vehicle emissions cause serious environmental problems, especially in industrial areas and populated areas. Although exhaust emissions are tried to be reduced by legal regulations, it is clear that non-exhaust emissions also increase significantly. Brake wear emissions are one of the most important sources of non-exhaust emissions. Brake wear particles are usually result from a cast-iron disc and a composite pad pair that is accompanied by friction. The chemical composition of these materials affects the content of the wear particles. The purpose of this study is to investigate the chemical and microstructural characterization of brake wear emission material of brake discs and pads commercially available to the market by Original Equipment Manufacturers (OEMs). Microstructure characterization of the wear particles was analyzed with field scanning electron microscopy (SEM); elemental analysis was conducted with energy dispersing spectrometer (EDS); crystal structures were analyzed with X-ray diffraction (XRD), and molecular bond structures were analyzed with the aid of fourier-transform infrared spectroscopy (FTIR). As a result of the analysis, it was found out that elements such as C, N, O, F, Si, Ca, Fe and Cu; sulfates, phosphates, oxides, and different mineral structures exist in the chemistry of wear particles. Especially, the presence of oxidized structures and heavy metals, pose a serious threat to human health and the environment. This study will provide important information for policymakers and researchers.
Microstructure and chemical analysis of NOx and particle emissions of diesel engines
(2020) Güney, Bekir; Öz, Ali
This study was carried out to investigate the micro and chemical structure of particulate matter and nitrogen oxide from motor vehicle exhaust fumes. In this context, particulate matter microstructure was determined with the help of scanning electron microscope; elements such as C, O, N, F, Na, Mg, Br, Al, Si, Hg, S, Pb, Cl, Cd, K, Ca, Ba, Ti, V, Mn, Fe, Ni, V and Zn which constitute the source of pollution were determined by energy dispersive spectrometer; nitrogen oxide compounds were determined with X-ray diffraction spectrometer; and photonic properties were determined by means of photoluminescence spectrophotometer. The data obtained in this study provide important source information to understand the effects of exhaust fume on environmental pollution.
Investigation of the effect of Cr2O3-2 % TiO2 coating on braking performance
(2020) Mutlu, İbrahim; Güney, Bekir; Erkut, İbrahim
The brake discs of the new generation vehicles operate with very high speed and tough braking conditions. Therefore, high performance in braking is essential in terms of human and vehicle safety. In vehicles, the braking performance criterion is to control the speed of the vehicle safely without causing a mechanical failure. During a braking process in a moving vehicle, an excessive abrasion occurs. The aim of this study was to investigate the performance of the brake disc coated with Cr2O3-2%TiO2 (Metco106F) composite powder by using the plasma coating method to increase the abrasion resistance of automobile brake disc. The braking test was performed according to the SAEJ2430 braking test standard. The microstructure, hardness, wear and braking performance characteristics of the coating were investigated. Our results showed that the coated disc exhibited better wear resistance than the uncoated disc under the different wear mechanisms at high temperatures. The obtained coefficient of friction revealed that the coated disc showed better braking performance.
Taşıt emisyonlarının mikroyapı analizi
(2019) Güney, Bekir; Küçüksarıyıldız, Hanifi
Dünyada kültürel etkileşim, ekonomik büyüme ve teknolojik ilerlemeler hızla gelişmektedir. Bu gelişmeler insanoğlunun refah seviyesini yükseltmekle birlikte birçok problemi de beraberinde getirmektedir. Karşılaşılan problemlerden birisi de trafikte seyreden motorlu kara taşıtlarının neden olduğu hava kirliliğidir. Bu çalışmada taşıt egzoz gazlarından kaynaklanan hava kirliliğinden ve etkilerinden, canlıları ve çevreyi korumak amacıyla SEM cihazı ile egzoz gazlarının mikro yapı analizi yapılmıştır. Egzoz gazlarındaki temel kirletici maddeler; karbon monoksit, azot oksitler, hidrokarbonlar, karbon dioksit, kükürt dioksit, kurşun ve bileşikleri, aldehitler, is ve partiküllerden meydana gelmektedir. Bu kirletici gazları oluşturan C, O, Al, Si, P, S, Cl, Ca, Ba, Cr, Fe, Zn ve Pb ana elementlerinin ağırlık oranları bulunmuştur. Ayrıca taşıt emisyonları kaynaklı metal ve ağır metallerin hala çevreyi kirletmeye ve tehdit etmeye devam ettiği deneysel olarak tespit edilmiştir.
The effect of flame spray coating on the tribological properties of brake disc
(Gazi University, 2020) Guney, Bekir; Mutlu, İbrahim; Küçüksarıyıldız, Hanifi
The movement of moving devices or machines in terms of safety perspective must be controlled. In modern vehicle applications, braking is closely related to safety. Slowing or breaking the movements of vehicles safely is the task of braking mechanisms. The most important components of these mechanisms are the disc and brake lining pairs. Brake discs are made of lamella graphite cast iron. During the braking, the kinetic energy of the vehicle is converted into the heat energy through friction. The braking elements are subject to very heavy thermo mechanical conditions under heat, speed and load. The friction and wear properties of the brake disc must be thermally more stable against the heat energy generated on it in order to maintain stability. In this study, mechanical properties of the brake discs, which the disc surface was coated with flame spraying and melting, were improved. In addition, microstructure, abrasion, hardness and surface roughness tests of the brake disc were conducted. As a result, the coated disc showed superior mechanical properties compared to the original disc
Characterization and wear behavior of TiBC coatings formed by thermoreactive diffusion technique on AISI D6 steel
(Elsevier, 2020) Kurt, Bülent; Özdoğan, Lütfullah; Güney, Bekir
A two-step Thermo reactive diffusion processes (including an initial titatinizing step followed by boronizing) is proposed in order to obtain superhard complex TiBC coating layer on AISI D6 steel. Microstructural characterization and mechanical properties of obtained TiBC layer conducted by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), optical microscopy, 2D profilometer, X-ray diffraction (XRD), micro-hardness, nano-indentation hardness and ball-on disc wear tests. Wear tests were carried out in ball on disc device by applying 30 N load and 500 m sliding distance against WC abrasive ball. Microstructural studies revealed a compact, homogenous and crack-free TiBC layer with 0.29-1.91 surface roughness (Ra), 3.65-29.5 mu m thickness and 1800-4841 HV0.05, hardness and 146-235 GPa elastic modulus. Hardness values of TiBC layers was significantly higher than those obtained by standard titanizing and boronizing due to the interspersed TiB and TiC phases within the TiBC layer. Higher hardness values are highly effective on the wear resistance and wear type. Thus, in parallel with the increase in mechanical properties, wear resistance increased in the range of 4-120 times in comparison with the untreated AISI D6 sample. Severe wear and extensive plastic deformation was observed in the untreated AISI D6, while micro-cutting, micro-cracking and pitting was dominant in samples with hardness 1800-4000 HV. When the surface hardness reached values above 4000 HV the wear mechanism further changed to microcracking and spalling.

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