Yazar "Riman, Richard E." seçeneğine göre listele

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    Reactive hydrothermal liquid-phase densification (rHLPD) of ceramics - a study of the BaTiO3[TiO2] composite system
    (Wiley, 2016) Vakıfahmetoglu, Cekdar; Anger, Jean Francois; Atakan, Vahit; Quinn, Sean; Gupta, Surojit; Li, Qinghua; Riman, Richard E.
    A densification process called reactive hydrothermal liquid-phase densification (rHLPD), based on principles of hydrothermal reaction, infiltration, reactive crystallization, and liquid-phase sintering, is presented. rHLPD can be used to form monolithic ceramic components at low temperatures. The densification of barium titanate-titania composite monoliths was studied to demonstrate proof of concept for this densification model. Permeable, green titania (anatase) compacts were infiltrated with aqueous barium hydroxide solutions and reacted under hydrothermal conditions in the temperature range 90 degrees C-240 degrees C. The effects of reaction time and temperature on the conversion of titania (anatase) into barium titanate were studied. Utilizing a 72 h reaction at 240 degrees C between l.0 M Ba (OH)(2), an anatase (TiO2) powder compact, and a corresponding Ba/Ti ratio of 1.5, it was possible to crystallize a composite 95 wt% (88 mol%) BaTiO3 and 5 wt% (12 mol%) TiO2. The composite had a relative density of similar to 90% with a compressive strength of 172 +/- 21 MPa and a flexural strength of 49 +/- 4 MPa.
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    Solvothermal synthesis of acmite conversion coatings on steel
    (Wiley, 2013) Whalen, Terence; VanSaders, Bryan; Vakıfahmetoglu, Cekdar; Mughal, Asad; Zlotnikov, Eugene; Cho, Seung-Beom; Riman, Richard E.
    Acmite (NaFeSi2O6) films were formed on steel coupons via solvothermal reaction of silica, sodium hydroxide, and 1, 4-butanediol in an autoclave under autogenous pressure. Systematic variation in processing variables led to homogenous coatings comprised of pinacoidal acmite grains with an average grain size of similar to 33m. The coatings were produced on the steel coupons from reactant conditions of 0.635m SiO2, 2.546m NaOH, and 3.087m 1,4-butanediol for 72h at 240 degrees C.