Yazar "Öztürk, Tayfur" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim
    Öğe
    Amorf/nanoyapılı Mg-esaslı ince filmlerin hidrojen depolama uygulamaları için çok elementli kaynaklardan üretimi
    (Selçuk Üniversitesi Mühendislik-Mimarlık Fakültesi, 2013) Akyıldız, Hasan; Öztürk, Tayfur
    Bu çalışmada, Mg-esaslı amorf/nanoyapılı ince filmler ısıl buhar çöktürme yoluyla üretilmiştir. Tüm filmler, toz metalurjisi yöntemleri ile hazırlanmış çok elementli kaynakların buharlaştırılması ile elde edilmiştir. Hazırlanan kaynaklar Mg-Cu, Mg-Cu-Ni, Mg-Cu-Al, Mg-Cu-Al-Ni şeklindedir. Üretilen kaynakların, sinterlendikleri sıcaklıktaki denge fazlarını ve serbest halde elementleri içerdikleri görülmüştür. Buharlaştırma sonrası ise sistemdeki fazların büyük oranda zayıflaştığı/amorflaştığı, hidrürlemenin ise incelmeyi daha da fazla artırdığı tespit edilmiştir. Çalışma, önerilen yöntemin ısıl buharlaştırma ile amorf/nanoyapılı film oluşturmaya uygun olduğunu göstermekle birlikte, bu tarz filmlerde, hidrojen depolama davranışının takibinde, X-ışınları kırınımından farklı yöntemlerin kullanılması gerekliliğini ortaya koymaktadır.
  • Küçük Resim Yok
    Öğe
    Thickness effects in hydrogen sorption of Mg/Pd thin films
    (ELSEVIER SCIENCE SA, 2013) Gharavi, Ayshe G.; Akyıldız, Hasan; Öztürk, Tayfur
    Mg thin films with various thicknesses ranging from 50 to 1000 nm capped with Pd have been prepared by thermal evaporation and their hydrogen sorption properties were examined following the electrical resistance change. The study showed that the hydrogenation and dehydrogenation temperatures correlate with the film thickness, thinner films reacting with hydrogen at reduced temperatures. It is concluded that films thinner than 200 nm react fully with hydrogen, while a considerable portion of the thicker films remain unreacted. The significance of this is discussed with reference to the design of hydrogen storage systems based on thin films or nanoparticles. (C) 2013 Elsevier B.V. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Ti modified Pd-Ag membranes for hydrogen separation
    (PERGAMON-ELSEVIER SCIENCE LTD, 2015) Pişkin, Fatih; Akyıldız, Hasan; Öztürk, Tayfur
    An investigation was carried out into Pd-Ag separation membranes to check whether a reduction in their Pd content was possible through the incorporation of a third element, namely Ti. For this purpose a combinatorial thin film deposition system was developed incorporating three sputter targets arranged in triangular form. The system had a substrate in the form of a magazine, 6 inch in diameter, accommodating 21 discs arranged again in triangular form aligned with the targets underneath. With this geometry, a library of thin film membranes was obtained in a single experiment covering a wide compositional field, Pd content up to of approx. 75%. The thin film library was then screened with respect their tendency to react with hydrogen. This was accomplished by the resistivity measurements carried out on the membranes, while they are subjected to heating-cooling cycle under hydrogen, the values being compared with identical cycle carried out under argon. Since permeability is a product of hydrogen solubility and diffusivity, membranes that react with hydrogen, i.e. either forming a solid solution or a hydride, delineate compositions which are candidates for separation membranes. In the present work, this procedure was applied to a portion of Ag-Ti Pd ternary system aiming for separation membranes with f.c.c. crystal structure. Mapping based on the resistivity measurement indicated, Ag35Ti22Pd43, Ag13Ti25Pd62 and their near compositions as possible candidates for separation membranes. Copyright (c) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.