نتایج جستجو برای: کامپوزیت al2o3

تعداد نتایج: 16863  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده فنی مهندسی 1387

آلومینا علی رغم داشتن خواص مطلوبی همچون مدول الاستیسیته بالا، مقاومت به سایش قابل توجه، مقاومت به خوردگی مطلوب در محیط های شیمیائی و حفظ استحکام در دماهای بالا، به دلیل خواص مکانیکی پائین باعث گردیده است تا به ساخت نانوکامپوزیت های zta مبادرت شود. در این کامپوزیت ها توزیع ذرات نانوئی زیرکنیا در بین ذرات آلومینا باید به گونه ای باشد که ساختاری با کمترین اندازه دانه و بهترین خواص مکانیکی حاصل گرد...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه فردوسی مشهد - دانشکده مهندسی 1389

هدف از انجام این تحقیق، تولید پودر کامپوزیتی نانو ساختار wc-al2o3 به روش سنتز احتراقی و با استفاده از مواد اولیه صنعتی و ارزان قیمت و با استفاده از دستگاه مایکروویو است. در این تحقیق از پودر آمونیوم پاراتنگستات به عنوان منبع تامین اکسید تنگستن استفاده گردید. این ماده به وفور و به قیمت های بسیار کم در بازار موجود است. پس از انجام کلسیناسیون این پودر در دو دمای 300 و 450°c و بررسی نتایج حاصل از آ...

2011
E. H. Bernhardi M. Pollnau

Applying Bragg gratings in Al2O3 channel waveguides, we demonstrate distributed Bragg reflectors with Qfactors of 1.0210 6 . An integrated Al2O3:Yb 3+ waveguide laser with 67% slope efficiency and 47 mW output power is achieved with such cavities.

2012
Writam Banerjee Siddheswar Maikap Chao-Sung Lai Yi-Yan Chen Ta-Chang Tien Heng-Yuan Lee Wei-Su Chen Frederick T Chen Ming-Jer Kao Ming-Jinn Tsai Jer-Ren Yang

Improved resistive switching memory characteristics by controlling the formation polarity in an IrOx/Al2O3/IrOx-ND/Al2O3/WOx/W structure have been investigated. High density of 1 × 1013/cm2 and small size of 1.3 nm in diameter of the IrOx nano-dots (NDs) have been observed by high-resolution transmission electron microscopy. The IrOx-NDs, Al2O3, and WOx layers are confirmed by X-ray photo-elect...

2011
Dawei Liu Yanyi Liu Stephanie L. Candelaria Guozhong Cao Jun Liu Yoon-Ha Jeong

V2O5 xerogel films were fabricated by casting V2O5 sols onto fluorine-doped tin oxide glass substrates at room temperature. Five, ten and twenty atomic layers of Al2O3 were grown onto as-fabricated films respectively. The bare film and Al2O3-deposited films all exhibited hydrous V2O5 phase only. Electrochemical impedance spectroscopy study revealed increased surface charge-transfer resistance o...

2013
Kelvii Wei Guo

Investigation was to study the influence of pulse-impact on microstructure of Liquid-Phase-Pulse-Impact Diffusion Welding (LPPIDW) welded joints of aluminum matrix composite SiCp/A356, SiCp/6061Al, Al2O3p/6061Al. Results showed that under the effect of pulse-impact: 1) the interface state between reinforcement particle (SiC, Al2O3) and matrix was prominently; 2) the initial pernicious contact-s...

2016
Huanfeng Jiao Xiaoliang Zhao Chunxiao Lv Yijun Wang Dongjiang Yang Zhenhuan Li Xiangdong Yao

One-dimensional γ-Al2O3 nanofibers were modified with Nb2O5 to be used as an efficient heterogeneous catalyst to catalyze biomass into 5-hydroxymethylfurfural (5-HMF). At low Nb2O5 loading, the niobia species were well dispersed on γ-Al2O3 nanofiber through Nb-O-Al bridge bonds. The interaction between Nb2O5 precursor and γ-Al2O3 nanofiber results in the niobia species with strong Lewis acid si...

2012
A. Gharibi Kharaji A. Shariati

One of the main reactions that can be used to reduce greenhouse gases emissions is Reverse Water Gas Shift (RWGS) reaction. Through this reaction CO2 is converted to CO to produce beneficial chemicals such as methanol. In this paper Mo/Al2O3 catalyst was prepared and then promoted with Ni ions through impregnation method to produce Ni-Mo/Al2O3 catalyst. The structures of the catalysts were stud...

2014
M. J. Sayagués M. A. Avilés J. M. Córdoba F. J. Gotor

9 The synthesis of (Ti1-xZrx)B2-Al2O3, (Ti1-xHfx)B2-Al2O3 and (Zr1-xHfx)B2-Al2O3 10 (x=0, 0.5 and 1) powder nanocomposites via a mechanochemical method using TiO2, ZrO2, 11 HfO2, HBO2 and Al as the raw materials was investigated. The formation of the 12 nanocomposites proceeds via a mechanically-induced self-sustaining reaction (MSR) process 13 that involves several simultaneous reactions. The ...

2004
Bong-Kyu Chang Bruce J. Tatarchuk

Preferential oxidation (PROX) of CO is the most efficient way to remove CO from reformate streams for PEM fuel cells. Pt/Al2O3 has long been used for this purpose. Pt/Al2O3 catalysts are effective for preferential oxidation of CO only at temperatures above 150°C, and the maximum CO conversion usually takes place at around 200°C. In this study, promotion of Pt/Al2O3 with transition metals result...

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