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Advanced Friction-Wear Behavior of Organic Brake Pads Using a Newly Developed System
(Taylor & Francis Inc, 2019) Öktem, Hasan; Uygur, İlyas
The objective of this study was to investigate the influence of an advanced performance system on the tribological behavior of brake pad material using a specially designed brake pad tester system following standard SAE J-661. The tribological behavior and friction and wear characteristics of the organic brake pad samples were evaluated. During braking tests, the samples, in contact with a cast iron disk, were studied at different disc speeds, temperatures, and braking cycles under a constant pressure. In order to understand the friction and wear behavior, the unworn surfaces, worn surfaces, and wear debris were characterized by means of scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). Furthermore, the surface characteristics and differences in the wear modes of the brake pad samples were examined. Wear debris was permitted to deform the brake pad surfaces, leading to friction layers and enabling the estimation of the friction behavior of the brake pads. The results showed that the best friction-wear behavior was obtained with lower braking cycles at low speeds and temperature. Thus, the newly developed brake pad tester system proved very effective in evaluating the performance of the brake pad samples. [GRAPHICS] .
Alternatif katkı maddesi olarak kullanılan bor oksitin fren balatasının sürtünme davranışına etkisinin incelenmesi
(2019) Akıncıoğlu, Gülşah; Akıncıoğlu, Sıtkı; Uygur, İlyas; Öktem, Hasan
Otomobillerin frenleme sistemlerinin en önemli parçalarından olan fren balatalarınıniçeriğinde onlarca farklı malzeme bulunmaktadır. Kompozit bir malzeme olan frenbalatasından, iyi bir frenleme performansı, kararlı bir sürtünme katsayısı, yüksekaşınma direnci ve çevre dostu olması beklenmektedir. Özellikle son yıllarda, çevreyezararsız, doğal fren balata malzemesi arayışları hız kazanmıştır. Bu çalışmadadünya rezervlerinin büyük çoğunluğu ülkemizde bulunan bor oksit kullanılarak, frenbalatası numunesi üretilmiştir. Alternatif toz ile üretilen fren balatasının performanstestleri yapılmıştır. Bor oksit katkılı numuneden elde edilen performans test sonuçlarıborun fren balatalarında alternatif toz olarak kullanılabileceğini göstermiştir.
Biyodizel-Dizel Yakıt Karışımlarının Motor Titreşimine Olan Etkisinin İncelenmesi
(2016) Sarıdemir, Suat; Alçelik, Necdet; Uygur, İlyas
Alternatif yenilenebilir yakıtlardan biri olan biyodizel günümüzde popüler hale gelmiştir. Titreşim dizel motorların önemli karakteristiklerinden biridir. Bu çalışmanın amacı biyodizel ve standart dizel yakıt karışımlarının tek silindirli direk enjeksiyonlu bir motorun titreşimine olan etkilerini incelemektir. Deney motoru için minimum titreşim oluşturan yakıt tipi yakıt karışımları içerisinden belirlenmiştir. Tüm yakıt karışımları için en büyük titreşim değeri eksenel yönde, en küçük titreşim değeri ise yanal eksende elde edilmiştir. Motor titreşim değeri, tüm yakıtlar için motor devrine bağlı olarak artış göstermiştir. En büyük toplam titreşim değeri Ab15 yakıt karışımı ile elde edilmiştir. En küçük toplam titreşim değeri ise Ab50 yakıt karışımı ile elde edilmiştir. Tüm yakıt karışımları için eksenel (y) yönde Ch2 kanalından elde edilen titreşim değerlerinin zaman bölgesi olarak en büyük olduğu, yanal (x) eksende Ch1 kanalından elde edilen titreşim değerlerinin ise en küçük olduğu görülmüştür.
Bor oksit tozunun fren balatalarının tribolojik özelliklerine etkisi
(2018) Akıncıoğlu, Gülşah; Akıncıoğlu, Sıtkı; Uygur, İlyas; Öktem, Hasan
Bu çalışmada, Renault Clio otomobilin fren balatası, bor oksit tozu katkısı ile sıcak presleme yöntemiyleüretilerek, bor oksit tozunun balatanın tribolojik özellikleri üzerine etkisi deneysel olarak araştırılmıştır.Son yıllarda çevre dostu malzemelerin kullanılmasının önem kazanmasından dolayı fren balatasınıniçeriğinde bor oksit kullanılmıştır. Ayrıca bu malzemenin seçilmesinde ülke ekonomisine fayda sağlamaktaamaçlanmıştır. Karşılaştırma yapmak için ticari Clio balatası kullanılmıştır. Balata numunelerinin aşınmasürtünme deneyleri Chase tipi cihazda yapılmıştır. Bor oksit katkısının fren balatasının aşınma sürtünmeperformansına etkisi ticari fren balatasının sonuçlarıyla kıyaslanarak incelenmiştir. Sonuçta bor oksitkatkısının sürtünme katsayısına olumlu etki yaptığı gözlenmiştir.
Brake Pad Performance Characteristic Assessment Methods
(2021) Akıncıoğlu, Gülşah; Akıncıoğlu, Sıtkı; Öktem, Hasan; Uygur, İlyas
Along with the developing technology, expectations for improved automobile brake pads are also rising. Research on higher performance brake pads is contin-uing at a rapid pace. It is also recognized that in this field, widespread efforts are being made towards the production of brake pads which are economical, envi-ronmentally friendly and do not pose risks to human health. In recent years, non-industrial waste products have also been used as additives in brake pads, thus contributing to local economy. Performance tests have to be carried out so that the brake pads produced with the new compositions can be used. For this reason, the performance tests of the brake pads are important. This study brings a new overview via an investigation of the methods applied in determining their per-formance characteristics.
Corrosion response of ultra-high strength steels used for automotive applications
(Iop Publishing Ltd, 2019) Gerengi, Hüsnü; Şen, Nuri; Uygur, İlyas; Solomon, Moses M.
The corrosion resistance properties of two ultra-high strength steels, Docol 1200 and 1400 were studied in 3.5 wt% NaCl solution using chemical and electrochemical techniques supported by surface characterization techniques namely scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), atomic force microscope (AFM), and optical profilometer. The mechanical properties of both Docol 1200 and Docol 1400 uncorroded and corroded were determined by tensile test. Results obtained reveal that the two alloys exhibit similar mechanical properties. Corrosion has effect on the mechanical properties of the alloys. Corrosion studies reveal that both Docol 1200 and 1400 are prone to corrosion in NaCl environment. A corrosion rate of 30.6 mpy and 49.6 mpy was recorded for a Docol 1200 at 25 degrees C and 60 degrees C, respectively. For Docol 1400, the corrosion rate obtained at 25 degrees C and 60 degrees C was 32.7 mpy and 52.4 mpy, respectively. Docol 1200 is adjudged to exhibit superior corrosion resistance property than Docol 1400. The optical profilometric results disclose that Docol 1200 and Docol 1400 suffered pitting corrosion in NaCl solution. Pitting corrosion was more severe with Docol 1400 than 1200.
Design, construction and performance of a novel brake pad friction tester
(Elsevier Sci Ltd, 2018) Öktem, Hasan; Uygur, İlyas; Çevik, Murat
Determination of the tribological behavior of brake pads under real environmental conditions is an important and critical task which can significantly impact the automotive industry. Most studies simulate or measure the variants by indirect methods and accept them as true results. The new computer-controlled, interactive brake pad friction tester presented in this study was developed for this purpose. The major components of the machine, which are operated simultaneously, include: a proportional pressure-controlled hydraulics power pack, a mechanical transmission system with electromagnetic clutch, and a brake and automation control with SCADA computer analysis interface. Compared to other friction testing machines, a very important innovation of the newly developed friction tester allows for the testing of the brake pad samples and measuring of the noise level both to be performed with high precision under real conditions. Moreover, this friction tester is capable of determining the friction coefficients; wear behavior, temperature, and life intervals of brake pad samples. This novel brake pad system is relatively cheaper and measures effective friction coefficients more accurately. The uncertainty in measurements for friction coefficient and wear rate was approximately calculated as +/- 0.0135 and +/- 0.170 in all of experiments, respectively. In this study, the machine performance was carried out to evaluate the friction behavior of non-asbestos brake pad samples reinforced with hazelnut shell powder according to the standard brake lining quality control testing procedure (SAE J661).
Determination of Friction-Wear Performance and Properties of Eco-Friendly Brake Pads Reinforced with Hazelnut Shell and Boron Dusts
(Springer Heidelberg, 2018) Akıncıoğlu, Gülşah; Öktem, Hasan; Uygur, İlyas; Akıncıoğlu, Sıtkı
Brake pads are the most important component of an automobile braking system. In recent studies, brake pads have been produced by varying the constituents of existing compositions and by making new formulations with other friction materials. This study evaluated two sets of asbestos-free automotive brake pads produced from boron oxide (6%) and hazelnut shell (7%) dusts and seventeen other components. All ingredients were mixed and pressed to manufacture the sample eco-friendly brake pads in the same shape as commercial Clio pads. Hardness, porosity, compressibility, shear and wear tests were carried out on the samples, and the test results were compared with those of the commercial pad.
Diffusion bonding of iron and bronze by mirowave sintering
(European Powder Metallurgy Association (EPMA), 2007) Kurt, Adem; Ateş, Hakan; Uygur, İlyas; Gürhan, A.H.
In this study, diffusion bonding of Fe and Bronze (90%Cu+10% Sn) powders used as bearing materials has been investigated by microwave sintering. For this purpose Fe and Bronze powders were compacted at 250, 350 and 500 MPa and sintered via microwave energy and conventional sintering process. Green and sintered densities were measured. Fe- Bronze interfaces and porosity changes were investigated after microwave and conventional sintering.
The Effect of Cryogenic Treatment on Microstructure and Mechanical Response of AISI D3 Tool Steel Punches
(Asme, 2015) Arslan, Yusuf; Uygur, İlyas; Jazdzewska, Agata
Recently, deep cryogenic treatment is performed to improve the mechanical responses (wear, hardness, fatigue, and thermal conductivity) of various steel components. Researchers have tried to evaluate the eco-friendly and nontoxic process to optimize the parameters. Cold-shearing punches used to manufacture various holes that undergo severe impact loading and wear in the metal forming process. This study concerns the effect of soaking time (24 hr, 36 hr) at liquid nitrogen temperature (-145 degrees C) during the deep cryogenic treatment on the microstructural changes which are carbide distribution and retained austenite percentage of AISI D3 tool steel punches. It was shown that the deep cryogenic treatment reduces retained austenite and enhanced uniform distribution of carbide particles. It is concluded that for significantly improved punch life and performance, it is an advisable application of 36 hr deep cryogenic treatment.
The Effect of Cryogenic Treatment on Some Chemical, Physical, and Mechanical Properties of Thermowood (R) Oriental Spruce
(North Carolina State Univ Dept Wood & Paper Sci, 2022) Aytin, Ayhan; Uygur, İlyas; Demirci, Tuna; Akgül, İrfan
Effects of cryogenic treatment on the chemical, physical, and mechanical properties of oriental spruce wood, which was heat-treated with the Thermowood (R) method, were investigated in this work. Cryogenic treatment, which is a secondary process applied to industrially heat-treated ferrous and non-ferrous metallic materials, was applied to Thermowood (R) Oriental spruce wood. For this purpose, Oriental spruce wood was first heat-treated at two different temperatures (190 and 212 degrees C), and then both Thermowood (R) and control samples were cryogenically treated at -80 degrees C. The effects on shrinkage and swelling pressure resistance parallel to fibers, and the elemental structure were examined. The findings revealed that the improvement in shrinkage and swelling continued with heat treatment, and there was an average increase of 18 and 14.5%, respectively, in the compressive strength parallel to fibers compared with control and heat-treated samples. The FT-IR analysis showed that the wood compound structure was mostly cellulosic. The difference between the carbon-oxygen ratio in the cryogenically-treated wood decreased compared to the percentage change in the three basic elements, and the amount of hydrogen increased proportionally.
Effect of cryogenic treatment on wear behavior of Sleipner cold work tool steel
(Elsevier Ltd, 2023) Kara, Fuat; Küçük, Yılmaz; Özbek, Onur; Özbek, Nursel Altan; Gök, Mustafa Sabri; Altaş, Emre; Uygur, İlyas
Cryogenic treatment, also known as subzero heat treatment, is a cooling process that complements conventional heat treatment to improve the properties of metals. Unlike coatings, it is a one-time, inexpensive, permanent operation that affects the entire part. This method is mainly applied to tool steels used in mold making. In this study, the changes caused by the effects of shallow and deep cryogenic treatment on Sleipner cold work tool steel were investigated in terms of microhardness, microstructure, coefficient of friction (COF), and wear rate (WR). For this purpose, the test specimens were subjected to the cryogenic treatments performed at two different temperatures (?80 ºC for the shallow cryogenic treatment (SCT) and ? 180 ºC for the deep cryogenic treatment (DCT)) and various retention times (12 h, 24 h for SCT and 12 h, 24 h, 36 h for DCT). Dry sliding wear tests were carried out under different loads (10 N and 20 N) and varying test durations (60, 120, and 240 min) at a constant sliding speed of 0.075 m/s. According to the microhardness results, it was determined that the cryogenic treatment increased the hardness by 6.53 %. According to the microstructure investigations, a more homogeneous structure was observed with the cryogenic treatment, and secondary carbide precipitations were detected. It was observed that the conventional heat-treated (CHT) sample gave the highest COF value with an average coefficient of friction of 0.63. The lowest COF value of 0.58 was observed in the DCT-12 sample. After the wear tests, the lowest wear rate value for both load values was obtained from the DCT-36 specimen. © 2023 Elsevier Ltd
Effect of deep sub-zero treatment on mechanical properties of AA5XXX aluminum plates adjoined by MIG welding technique
(Elsevier Science Bv, 2017) Ateş, Hakan; Özdemir, A. Tamer; Uzun, Mahmut Esat; Uygur, İlyas
In this study, mechanical and microstructural characteristics of AA5XXX aluminum plates connected by MIG welding were investigated. Thus, after several preliminary experiments done to ensure quality requirements of the parameters, specimens in the form of long aluminum plates were welded, and then some of them were spared for the subsequent sub-zero treatment at about 146 degrees C for 12 and 24 h, respectively. To investigate the effect of this super cooling on the welded parts, several tensile, bending, and hardness tests in conjunction with micro-structure examinations were carried out and results were discussed in detail. It was concluded that during sub-zero treatment, microstructure gets finer and stabilized, positively affecting the overall strength of the material. There is no significant difference in the overall strength of the material right after the subzero treatment and that of the specimens rested for one year at room temperature after cryogenics treatments. (C) 2017 Sharif University of Technology. All rights reserved.
Effect of Friction Welding Parameter on Mechanical and Microstructural Properties of Dissimilar AISI 1010-ASTM B22 Joints
(Amer Welding Soc, 2011) Kurt, Adem; Uygur, İlyas; Paylaşan, U.
Rotary friction welding is one of the most economical and efficient production methods for joining similar and dissimilar materials. It is widely used with metals and thermoplastics in a wide variety of aviation, transport, and aerospace industrial component designs. Individually, mild steel to mild steel and copper to copper are normally easy to weld by fusion welding methods, but the joint of mild steel to copper can be extremely difficult due to the differences in the two materials' melting temperature, density, strength, and thermal conductivity. Thus, these kinds of problems can be eliminated by a solid-state friction welding technique. Hence, the current study attempts to understand the friction welding characteristics of mild steel-bronze dissimilar parts. This study looks into the influence of process parameters, which includes friction pressure, upsetting pressure, and upset time on the axial shortening, hardness, microstructure, and tensile properties of the welds. The optimum parameters for upset time, upset pressure, and friction pressure necessary for welding were obtained. Finally, the obtained mechanical properties results were commented on the light of optical microscopy.
Effect of friction welding parameters on mechanical and microstructural properties of dissimilar AISI 1010-ASTM B22 joints
(2011) Kurt, Adem; Uygur, İlyas; Paylaşan, U.
Rotary friction welding is one of the most economical and efficient production methods for joining similar and dissimilar materials. It is widely used with metals and thermoplastics in a wide variety of aviation, transport, and aerospace industrial component designs. Individually, mild steel to mild steel and copper to copper are normally easy to weld by fusion welding methods, but the joint of mild steel to copper can be extremely difficult due to the differences in the two materials' melting temperature, density, strength, and thermal conductivity. Thus, these kinds of problems can be eliminated by a solid-state friction welding technique. Hence, the current study attempts to understand the friction welding characteristics of mild steel-bronze dissimilar parts. This study looks into the influence of process parameters, which includes friction pressure, upsetting pressure, and upset time on the axial shortening, hardness, microstructure, and tensile properties of the welds. The optimum parameters for upset time, upset pressure, and friction pressure necessary for welding were obtained. Finally, the obtained mechanical properties results were commented on the light of optical microscopy.
The effect of overlapping on the primary stability of osteochondral grafts in mosaicplasty
(Springer, 2008) Haklar, Uğur; Tüzüner, Tolga; Uygur, İlyas; Kocaoğlu, Barış; Güven, Osman
Our goal was to determine the primary stability of overlapping osteochondral grafts used in mosaicplasty by studying the effect of overlapping in an ex vivo model. Osteochondral grafts, 10 mm in diameter, were transplanted from the trochlea of cow femurs to the weight-bearing area of the lateral femoral condyle with 0, 15, or 30% overlap. The grafts were pushed in with a probe at a rate of 2 mm/min, and load (N)-displacement (mm) curves were recorded. In Group I (control, 0% overlap), insertion 1 and 2 mm below the cartilage level could be reached at 572.3 +/- 273.6 and 999.3 +/- 427.6 N, respectively. In Group II (15% overlap), insertion 1 and 2 mm below the cartilage level could be reached at 263.6 +/- 91.7 and 746.6 +/- 88.0 N, respectively. In Group III (30% overlap), insertion 1 and 2 mm below the cartilage level could be reached at 179.4 +/- 31.2 and 657.0 +/- 106.5 N, respectively. The loads that were necessary to produce a 1-mm dent in the grafts were significantly different between Groups I and II and Groups I and III (p < 0.05). These results suggest that stability may be reduced by graft overlapping in mosaicplasty surgery. The results of this ex vivo animal study contribute to a more complete understanding of the primary stability of osteochondral grafts in an overlapping position as well as postoperative protocols.
Effect of wet Hydrogen Sulfide on Carbon Steels Degradation in Refinery Based on Case Study
(Springer Heidelberg, 2022) Orlikowski, Juliusz; Jazdzewska, Agata; Uygur, İlyas; Gospos, Radoslaw; Olczak, Tomasz; Darowicki, Kazimierz
Material degradation caused by wet hydrogen sulfide (Wet H2S) is one of the major issues in refineries. Carbon steel is the main construction material used in refineries and is subjected not only to thickness loss but the hydrogen is the major concern. H2S leads to high atomic hydrogen penetration in steel which causes degradation in the form of blistering and/or cracking (HIC/SOHIC) and stress cracking in the area of welds and heat affected zones. Mechanism is unusually dangerous due to high difficulty of threat assessment, which is mostly based on ultrasonic measurements or calculations based on the API standards. This research is based on evaluation of the real threat of wet H2S degradation based on examination of construction materials after 41 years of exploitation in refinery. The comparison of the theoretical calculation based on API standards and experience of the degradation of the real objects was characterized. Laboratory measurements include mechanical tests involving the elongation in the function of tensile stress and deformation, with analysis of material hardness and gas chromatography analysis. The results are complemented by studies of the chemical composition of the streams and analytical studies of the hydrogen content in the material obtained by the gas chromatography method. The tests showed compliance of the standard analysis of the corrosion risk with the laboratory tests performed on the real samples. Research leads to indication of the destructive methods which can be used on the materials obtained during scheduled material replacements or installation modernizations.
The Effects of Cryogenic Treatment on the Corrosion of AISI D3 Steel
(Univ Fed Sao Carlos, Dept Engenharia Materials, 2015) Uygur, İlyas; Gerengi, Hüsnü; Arslan, Yusuf; Kurtay, Mine
It is well known that cryogenic treatment is used to improve the mechanical properties of a material. Consequently, the use of cryogenic treatment has grown beyond its successful application on tool steels. In this research, the effects of cryogenic treatment on the corrosion of AISI D3 steel in 3.5% NaCl solution were examined by electrochemical impedance spectroscopy (EIS). The surface structure of the AISI D3 steel was examined by scanning electron microscopy (SEM) after the EIS investigations. Results clearly indicated that the pre-treatment of the steel was responsible for a significant effect on corrosion. The heat treatment process prior to the cryogenic treatment and the tempering process after were shown to decrease corrosion resistance.
The effects of cryogenic-treated carbide tools on tool wear and surface roughness of turning of Hastelloy C22 based on Taguchi method
(Springer London Ltd, 2016) Akıncıoğlu, Sıtkı; Gökkaya, Hasan; Uygur, İlyas
In this study, Taguchi method has been applied to evaluate the effect of cryogenically treated tools in turning of Hastelloy C22 super alloy on surface roughness. The optimum parameters (cryogenic treatment, cutting speed, and feed rate) of turning were determined by using the Taguchi experimental design method. In Taguchi method, L9 orthogonal array has been used to determine the signal noise (S/N) ratio. Analysis of ANOVA was carried out to identify the significant factors affecting surface roughness. The statistical analysis indicated that feed rate, with a contribution percentage as high as 87.64 %, had the most dominant effect on machining performance, followed by the cryo-treated tools treatment and cutting speed, respectively. The confirmation tests indicated that it is possible to improve surface roughness significantly by using the Taguchi method. Surface roughness was improved by 28.3 and 72.3 % by shallow (CT1) cryogenic treatment and deep cryogenic treatment (CT2) applied on cementite carbide tools (UT). It found that wear resistance of tungsten carbide insert was increased by shallow and deep cryogenic treatments.
Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel
(Springer, 2015) Çiçek, Adem; Kara, Fuat; Kıvak, Turgay; Ekici, Ergün; Uygur, İlyas
In this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 degrees C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.

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