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131.
The preparation of pure Y3Al5O12 (YAG) and 50 vol% Al2O3–YAG
composite powders by a wet chemical route is presented. The role of the synthesis
temperature during reverse-strike precipitation has been investigated, showing
its relevant effect on the purity and homogeneity of YAG powder.
The
composite material was prepared by comparing two different synthesis routes.
A composite powder was synthesized via reverse-strike temperature-controlled
co-precipitation. In the latter case, a pure-alumina precursor was firstly
reverse-strike precipitated and then doped with an yttrium salt solution.
For both syntheses, the role of thermal and mechanical pre-treatments on the
phase development was demonstrated. 相似文献
132.
H. Kienitz 《Angewandte Chemie (International ed. in English)》1969,8(10):733-750
The important advances being made in modern analytical methods are indicative of the fundamental changes that are occuring in the theory and practice of “analytical chemistry”. “Information optimization” demands a new approach in teaching and research, and calls for the intergration of chemistry with other scientific and technical disciplines. 相似文献
133.
Elisângela Corradini Luís C. de Morais Nicole R. Demarquette José A. M. Agnelli Luiz H. C. Mattoso 《先进技术聚合物》2007,18(10):861-867
This work involved a study of the effect of processing variables (temperature, water content, rotor speed, and time) on the mechanical properties of starch:gluten:glycerol mixtures in the weight ratio of 40:40:20. The properties of the materials were affected by the processing variables. The torque decreased with water content, indicating that water facilitates the plasticization of mixtures, whereas the increase in temperature accelerated the evaporation of water, thus increasing the torque. Ultimate tensile strength was achieved at the lowest temperature (110°C) and the highest water content (20%), whereas maximum elongation was achieved for the material processed at the highest temperature, 150°C, and the fastest rotor speed, 70 rpm. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
134.
一种基于二进小波变换的自适应滤波方法 总被引:3,自引:0,他引:3
根据信号和噪声经小波变换后在不同尺度上有不同的特征,将相邻尺度二进小波变换值的相关量进行归一化处理并与小波变换值比较来判断信号与噪声,以噪声在各尺度的方差作为终止迭代的标准,提出了一种基于二进小波变换小波域选择噪声的自适应滤波方法。研究了模拟信号的去噪过程、半峰宽和信噪比对去噪结果的影响,并对模拟含噪信号和含噪毛细管电泳信号去噪前后的结果进行了比较。实验结果表明:由于该方法具有良好的自适应性和显著的滤波效果,必将得到广泛的应用。 相似文献
135.
R.?Mitchell C.?M.?CarrEmail author M.?Parfitt J.?C.?Vickerman C.?Jones 《Cellulose (London, England)》2005,12(6):629-639
The surface chemical composition of raw unscoured cotton was successfully investigated by the surface analytical techniques
X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The presence of non-cellulosic
material at the fibre surface was established and determined to be a complex mixture of fatty acids, alcohols, alkanes, esters
and glycerides. The effect of scouring and bleaching was to reduce the surface concentration of these materials but even after
aqueous processing some non-cellulosic material residue was still detected at the fibre surface. 相似文献
136.
A.?H.?Naik N.?V.?Thakkar S.?R.?DharwadkarEmail author K.?D.?Singh Mudher V.?Venugopal 《Journal of Thermal Analysis and Calorimetry》2004,78(3):707-713
Sodium zirconium phosphate [NaZr2P3O12], a potential ceramic matrix for fixation of high level nuclear waste, was synthesized by heating the mixture of sodium carbonate [Na2CO3], zirconyl nitrate hydrate [ZrO(NO3)2·5H2O] and ammonium dihydrogen phosphate [NH4H2PO4] in air, in a resistance heated furnace and a microwave heating system respectively in the temperature range 450 to 650°C. The mixture heated for 1 h in a resistance furnace at 450°C yielded a poorly crystalline NaZr2P3O12 [NZP]. Increasing the temperature to 650°C produced a highly crystalline product. The same mixture heated in a microwave oven at 450°C for 1 h however, yielded the most crystalline NZP.In an alternate method, the mixture of sodium dihydrogen phosphate (NaH2PO4), zirconium dioxide (ZrO2) and diammonium hydrogen phosphate [(NH4)2HPO4] heated in resistance furnace at 650°C for the same period did not react in air. It also did not yield the pure product at 450°C when heated in microwave assembly for 1 h.The authors thank the Board of Research in Nuclear Sciences (BRNS) of the Department of Atomic Energy (DAE) for the financial support for this work under the project No. 2000/37/19/BRNS/1959 dtd09-02-02. 相似文献
137.
138.
Differential scanning calorimetry and the advanced solidification processing of metals and alloys 总被引:2,自引:0,他引:2
B. Cantor 《Journal of Thermal Analysis and Calorimetry》1994,42(4):647-665
This paper describes some examples of the use of differential scanning calorimetry (DSC) in providing information for advanced solidification processing of metals and alloys. Spray forming, squeeze casting, grain refinement and crystallization of amorphous alloys are all discussed. DSC measurements are shown to be valuable for testing kinetic theories of nucleation and growth, and validating solidification process models. 相似文献
139.
Interchange reactions involving esters were used in reactive processing with a view to obtaining polymer blends with stabilized morphology. Dibutyltinoxide (DBTO) appeared to be an excellent catalyst for these reactions. In fact, it was shown that the true catalytic entity is a dimeric alkoxy, acyloxy distannoxane entity formed in situ, during processing, by the reaction of the DBTO with the polymer ester groups. This compound was first obtained with model esters and characterized by multinuclear NMR analysis (1H, 13C, 119Sn). The catalytic efficiency of the in situ polymeric distannoxane was compared with other added parent distannoxanes. Later on – still with model compounds – ligand exchanges at the tin sites were investigated and it was shown that these exchanges are not essential to the catalyst activity, but when they take place it increases the catalytic efficiency. Then, this type of catalysis was successfully used for interchange reactions in reactive extrusion of different polymer blends, some applications are briefly presented. To cite this article: M.-F. Llauro and A. Michel, C. R. Chimie 9 (2006). 相似文献
140.
《Surface and interface analysis : SIA》2003,35(3):282-286
We have developed a high‐speed image processing CCD video camera for real‐time energy‐loss imaging using a conventional electron microscope with an energy‐loss imaging facility. As an initial demonstration of real‐time lock‐in energy‐loss imaging, a background‐subtracted energy‐loss image was observed by attaching the high‐speed image processing CCD video camera to an analytical electron microscope equipped with a floating‐type energy‐loss imaging analyser. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献