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Öğe Hardness and wear behaviours of al matrix composites and hybrid composites reinforced with B 4 C and SiC(Springer Nature, 2019-01-15) Çelik, Yahya Hışman; Kılıçkap, ErolThe conversion into the desired shape of the metal powders using Powder Metallurgy (PM) method enables economically mass productions. This case allows producing parts with complex and high dimensional accuracy with no machining. In this study the composites and hybrid composites with Al matrix were produced using PM method with different ratios B4C and SiC. Microhardness and wear experiments of the produced composites were investigated. Wear experiments were performed at a constant speed of 0.5 m/s, application loads of 5, 10 and 15 N and sliding distances of 250, 500, and 750 m. Then, SEM images of composites and hybrid composites were captured. The increase of the reinforcement ratio in the composites contributed to the increase of the hardness. The highest hardness value was computed as 58.7 HV from 16% B4C reinforced composite. In addition, the increase in the reinforcement ratio contributed to the increase of the wear resistance. The increase in the load and sliding distance also increased the wear. The minimum weight loss was calculated as 18 mg from 5 N load, 250 m sliding distance and 16% SiC reinforced composite.Öğe Investigation of microstructure, hardness values and compressive strengths of SiC/Al composites in different reinforcing rates produced by PM method(Fırat Üniversitesi, 2017-10) Çelik, Yahya Hışman; Kılıçkap, ErolIn this study, the microstructures, hardness values and compressive strength of SiC reinforced Al metal matrix composites in different rates produced by powder metallurgy (PM) method have been examined. Al powders which has 99% purity and 1-210 µm size, and SiC powders which has 98.5% purity and 1-45 µm size were used in experiments. These powders were weighed in proportions pure Al, 4% SiC/Al, 8% SiC/Al, 12% SiC/Al, 16% SiC/Al via precision balance. A mechanical mixing device was used in order to homogeneously mix of the weighed powders. These mixtures were pressed under pressure of 475 MPa. All pressed materials were made into composite by sintering for 120 minutes at 580 ºC. Microstructures, hardness values and compressive strength of the composites were analyzed by polishing the surfaces of the composites. As a result of analysis, it was observed that the SiC reinforces were uniformly dispersed in Al matrix, the hardness values of the composite increased with increasing reinforcement rate and the compressive strength values of the composites were similar to one anotherÖğe CNC plazma ile kesmede işleme parametrelerinin kesme kalitesine etkisinin araştırılması(Fırat Üniversitesi, 2011) Çelik, Yahya Hışman; Özek, CebeliNowadays, It is important to usenew machines in manufacturing technologies.Oneof the most important of these machinesisCNC plasma cutting machines. The measuring sensitivity is not soimportantinthese machines.However,the materials workingunder high pressure and strength can be cut by means of these machines. In thisstudy,S235JR sheet materials of 4, 6 and 8mm thickness which areused inpressurized containers were cut in the CNC plasma machine atvarious speeds, amperesand arc voltages. For Cutting processeswhichwerecarried out atvarious parameters,surface roughnessesand temperature distributionsweremeasured on the samplescut.Comments on the hardness and material strength of the material exposed to the cutting process were madedepending on surface roughnessesand temperature distributions.Öğe Investigation of wear behaviours of Al matrix composites reinforced with different B4C rate produced by powder metallurgy method(Elsevier, 2017-09) Çelik, Yahya Hışman; Seçilmiş, KübraIn this study, the effects of wear behaviours of Al matrix composites reinforced with different B4C rate produced by powder metallurgy method were investigated. Al and B4C powders with purity of 99.9% and sizes of 25–44 µm were prepared as pure Al, 4% B4C/Al, 8% B4C/Al, 12% B4C/Al and 16% B4C/Al. After these prepared mixtures were pressed under 350 MPa, they were sintered for 90 min at 580 °C in atmospheric environment. Microhardness and wear tests of the produced samples were carried out. Wear experiments of these composites were performed with specially manufactured test equipment at different application loads (5 N, 10 N and 15 N), different sliding distances (250 m, 500 m, 750 m and 1000 m) and a constant speed of 0.46 m/s. In addition, optical microscope, SEM, EDS analyses were used to determine the microstructural changes in the worn and unworn surface of the manufactured composite materials. The results of experimental studies show that the increasing the B4C reinforced rate in composites with Al matrix has led to increase of the hardness and to reduce of the wear loss.Öğe Effects of natural hard shell particles on physical, chemical, mechanical and thermal properties of composites(SAGE Journals, 2021-05-31) Çelik, Yahya Hışman; Çelik, Kadir Serdar; Kılıçkap, ErolShelled herbal foods are widely consumed. The evaluation of the shells of these foods is important due to their features such as low cost, ease of recycling and environmental friendliness. In this study, hazelnut shell (HS), pistachio shell (PS), and apricot kernel shell (AKS) were brought to powder particles by grinding to dimensions of 300–425 µm. Some of the powder particles were converted into ash at 900°C. The amounts of cellulose, ash, humidity, and metal in these particles via chemical analyses were determined, while their structural properties via X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) analyses. Composite materials were produced by adding 15 wt.% to the polyester matrix material from these powder particles and ashes. Compression strength, hardness, specific weight, and thermal conductivity of these composites were analyzed. The lowest and highest humidity, ash, cellulose, hemicellulose, and lignin ratios in powders showed differences depending on the type of powders. The amount of Sn and K in the HS, PS, and AKS powders were close to each other, while the amount of Ca, Na, Mg, Fe, Mn, Cu, Zn and Si was higher in AKS powder. The reinforcement adding to the polyester increased the compression strength, hardness, specific weight and thermal conductivity properties.Öğe Investigating the effects of cutting parameters on materials cut in CNC plasma(Taylor & Francis, 2013-10-03) Çelik, Yahya HışmanComplex-profile surfaces, of which measurement precision is not important, are cut serially using CNC plasma. These materials cut using CNC plasma are assembled with different manufacturing techniques. These materials can also operate under high pressure and resistance. In this study, S235JR sheet materials (4, 6, and 8 mm thick), used in pressure vessels, were cut using the CNC plasma cutting machine at different cutting speeds, amperes, and arc voltages. Temperature distribution, thickness of heat-affected zone (HAZ), surface roughness, and hardness were measured from the material cut at these different values. Based on values obtained from measurements, the ideal cutting conditions were identified for the materials exposed to the cutting procedures.Öğe Farklı takviye oranlarındaki B4C/Al kompozitlerın sertlik ve mikroyapılarının araştırılması(International Engineering, Science & Education Group (INESEG), 2016) Çelik, Yahya Hışman; Seçilmiş, KübraToz metalürjisi ile şekillendirilen parçalar ikinci bir işleme ihtiyaç duyulmadan nihai ürün olarak üretilebilmekte ve bu malzemelere istenilen üstün mekanik özellikler kazandırılabilmektedir. Bu üstün özellikler, toz metalürjisi yöntemi ile elde edilen parçaların pek çok alanda kullanımını arttırmaktadır. Bu çalışmada, toz metalürjisi yöntemiyle üretilen farklı oranlardaki B4C takviyeli Al metal matrisli kompozitlerin sertlikleri ve mikroyapıları incelenmiştir. Saflıkları %99,9 ve boyutu 325 mesh olan Al ve B4C tozları hassas terazi yardımı ile belirlenen (saf Al, %4 B4C/Al, %8 B4C/Al, %12 B4C/Al ve %16 B4C/Al) oranlarda tartılmış ve mekanik karıştırma cihazında karıştırılmıştır. Bu karışımlar 350 MPa basınç altında preslenmiştir. Uygun sinterleme sıcaklığının belirlenebilmesi için %8 B4C takviyeli Al matrisi 560 ºC, 580 ºC ve 600 ºC‘de 90 dakika boyunca sinterlenmiştir. En yüksek sertlik ve basma mukavemetinin 580 ºC sinterleme sıcaklığından elde edildiği görülmüştür. Bu doğrultuda farklı takviye oranlarında preslenmiş tüm malzemeler 580 ºC‘ de sinterlenerek kompozit haline getirilmiştir. Yapılan deneysel çalışmalar, takviye oranının artmasının kompozitin sertlik değerinin artmasına katkı sağladığını göstermiştir. Bu durumun mikroyapıdaki takviye oranının sıklığı ve matris içerisindeki dağılımı ile ilgili olduğu gözlemlenmiştir.Öğe TM yöntemi ile üretilmiş Al matrisli kompozitlerde presleme basıncının ve B4C oranının sertlik ve aşınma davranışı üzerine etkisi(Fırat Üniversitesi, 2018-03-01) Çelik, Yahya Hışman; Kılıçkap, Erol; Yenigün, BurakToz metalürjisi (TM) yöntemi sayesinde metal tozlarının istenilen şekle çok kısa zamanda dönüştürülmesi ekonomik anlamda seri imalatı mümkün kılmaktadır. Bu durum, malzemelerde talaşlı işleme ihtiyacını ortadan kaldırarak karmaşık ve boyutsal hassasiyeti yüksek olan parçaların üretilmesine olanak sağlamaktadır. Özellikle alüminyum ve alaşımları, ticari alanlarda vazgeçilmez malzemeler olarak TM yöntemi ile üretimde yerini almıştır. Bu çalışmada, TM yöntemiyle üretilmiş B4C takviyeli Al matrisli kompozitlerin farklı presleme basıncına (400 ve 475 MPa) ve takviye oranına (takviyesiz ve ağırlıkça % 4, 8 ve 12 takviyeli) bağlı olarak mikroyapı, sertlik ve aşınma davranışları incelenmiştir. Numunelerin aşınma deneyleri özel olarak imal edilen test düzeneği ile 0,50 m/s sabit kayma hızında, farklı uygulama yüklerinde (5, 10 ve 15 N) ve farklı kayma mesafelerinde (250, 500 ve 750 m) yapılmıştır. Ayrıca üretilen kompozitlerin mikroyapısal değişimlerini belirlemek için optik mikroskop ve SEM görüntüleri incelenmiştir. Deneysel çalışmalar sonucunda, kompozit numunelerde presleme basıncının ve takviye oranının artması ile sertlik değerlerinin arttığı ve aşınma kayıplarının azaldığı tespit edilmiştir. Ayrıca kayma mesafesi ve uygulanan yükün artması ile aşınma miktarının arttığı görülmüştür
