Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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Access Right: Open AccessSubject: search.filters.subject.Chemical vapor deposition

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  • Article
    Citation - WoS: 10
    Citation - Scopus: 12
    Transparent block copolymer thin films for protection of optical elements via chemical vapor deposition
    (Elsevier Ltd, 2018) Karabıyık, Merve; Ebil, Özgenç; Karabıyık, Merve; Ebil, Özgenç; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this study, glycidyl methacrylate and 1H, 1H, 2H, 2H-perfluorodecyl acrylate copolymer p(GMA-co-PFDA) thin-films fabricated via Initiated Chemical Vapor Deposition (iCVD) were investigated as protective coatings on optical BK7 glass substrates and commercial optical filters. Durability tests based on military standards MIL-F-48616 and MIL-C-48497A were performed to evaluate performance of coatings for the protection of surfaces of optical elements. Cross-linked p(GMA-co-PFDA) copolymer coatings successfully passed all durability tests showing excellent mechanical properties and protection against humidity, salt water, swelling in water, and resistance to organic solvents while providing excellent adhesion to substrate. iCVD process enabled fine tuning of film morphology, mechanical properties and hydrophobicity by controlling the process parameters. Fabricated films were hydrophobic and highly transparent (>98%) in the wavelength range from 300 nm to 1000 nm. Optical transmittance measurements before and after coating process proved that while providing chemical and physical protection, p(GMA-co-PFDA) copolymer thin-films do not cause any detectable change in optical performance of commercial narrow band and wide band filters.
  • Article
    Citation - WoS: 28
    Citation - Scopus: 31
    The Effects of Catalyst Pretreatment, Growth Atmosphere and Temperature on Carbon Nanotube Synthesis Using Co-mo/Mgo Catalyst
    (Elsevier Ltd., 2015) İnce Yardımcı, Atike; Yılmaz, Selahattin; Selamet, Yusuf; Yılmaz, Selahattin; 03.02. Department of Chemical Engineering; 04.05. Department of Pyhsics; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    The growth of high quality and high yield carbon nanotubes (CNTs) by catalytic chemical vapor deposition (CVD) of CH4 over Co-Mo/MgO catalyst was investigated for different growth temperatures and H2 flow rates. It was observed that CNT yield decreased with the H2 flow rate, however, quality increased with increasing H2 flow rate. CNT yield increased for the temperatures 850-950 °C but dropped significantly above 950 °C. In this study, the highest yield of 1526% was obtained at the growth temperature of 950 °C. The optimum H2 flow rate was 200 sccm; this rate gave both high graphitization and high yield of product. Various CNT growth atmospheres including Ar, H2 and the mixture of both gases were also analyzed and it was observed that the highest quality CNTs were obtained for both pretreatment and growth carried out with H2. This gave a high yield of 292%. On the other hand, CNT growth carried out under Ar atmosphere gave higher CNT yield of 368%, however, the CNTs grown with Ar were more defective and had larger diameters. Prime novelty statement We demonstrate a sorbitol added catalysis synthesis method and importance of the ideal growth conditions to improve high quality single walled carbon nanotube yield up to 1500%.