Yazar "Ozturk, M. K." seçeneğine göre listele

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    Synthesis and Characterization of Boron Doped Alumina Stabilized Zirconia Fibers
    (KOREAN FIBER SOC, 2011) Uslu, I.; Tunc, T.; Keskin, S.; Ozturk, M. K.
    Boron doped PVA/Zr-Al acetate nanofibers were prepared by electrospinning using PVA as a precursor. The effect of calcination temperature on morphology and crystal structure was investigated at 250, 500, and 800 degrees C. The study also establishes the effect of boron doping on the morphology of PVA/Zr-Al acetate nanofibers at various calcination temperatures. The measurements showed that the conductivity, pH, viscosity and the surface tension of the hybrid polymer solutions have increased with boron doping. In addition, the fibers were characterized by FTIR, DSC, XPS, XRD and SEM techniques. The addition of boron did not only increase the thermal stability of the fibers, hut also increased the average fiber diameters, which gave stronger fibers. The DSC results indicated that the melting temperature (Tm) of the fibers was increased from 256 to 270 degrees C with the addition of boron. XRD peak patterns showed that after further heat treatment at 800 degrees C, zirconia exists in two phases of tetragonal and monoclinic modifications. Moreover, alumina does not transform into the gamma-Al2O3 and theta-Al2O3 phase at 800 degrees C. The SEM appearance of the fibers showed that the addition of boron resulted in the formation of crosslinked bright surfaced fibers.
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    Synthesis and characterization of erbia and ceria doped calcia stabilized nanocrystalline zirconia based ceramics
    (SPRINGER, 2013) Uslu, I.; Aytimur, A.; Kocyigit, S.; Ozcan, F.; Ozturk, M. K.; Colak, U.
    Er2O3 doped calcia stabilized zirconia based inert matrix fuel containing CeO2 as a surrogate for PuO2 was fabricated for a wide range of concentration using the polymer-to-ceramic conversion technique via metal acetate preceramic hybrid polymer solutions. Samples were characterized by XRD, SEM and AFM techniques. Nanocrystallite size variation in the samples was evaluated using peak broadening values by means of the Scherrer formula. The smallest lattice constant was obtained for the sample containing Zr/Ca/Ce/Er atomic weight ratio of 74/11/10/5. The average grain diameters varied between 64 nm and 129 nm. SEM results show that, the smallest grain size was obtained for the sample containing Zr/Ce/Er atomic weight ratio of 22/2/1. Moreover, surface roughness characteristics of the samples were evaluated by different definitions using intermittent contact mode AFM.