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71.
At high temperatures in clean oxidizing environments, SiC forms a very protective SiO2 film, but, in environments containing low levels of gaseous alkali salt contaminants or where condensed salts may deposit on the surface, the resistance of the film is significantly reduced. Oxidation kinetics of SiC were measured by continuous thermogravimetric analysis in a controlled environment containing CO2 , H2 O, and O2 plus low levels of potassium-containing salts. Potassium was found to be incorporated into the SiO2 scale and to significantly change its transport properties and its morphology. The rate of scale formation was found to increase directly in proportion to K in the scale. A change in mechanism was observed when water vapor was added to the reacting gas stream. 相似文献
72.
中国油田堵水技术综述 总被引:17,自引:0,他引:17
本文论述了我国油田堵水技术的发展及其在油田开发中的作用,总结和阐述了油井化学堵水技术和注水井吸水剖面调整技术的原理和效益,指明了实践证实的有成效的工艺方法和堵水技术发展方向。 相似文献
73.
M.A.R. Alves 《Microelectronics Journal》2005,36(1):51-54
We developed a process to obtain sharper silicon tips by employing anisotropic etching in a KOH solution followed by SF6 plasma etch. The tips were further sharpened using the established thermal oxidation technique to decrease the cone angle and, therefore, obtain smaller curvature radii. We have analyzed the impact of such changes in geometry on a figure of merit associated with the field emission characteristics. An increase in the figure of merit by a factor of three was found in relation to the tips before sharpening. 相似文献
74.
D. P. Dreoni D. Pinelli F. Trifirò Z. Tvaruzkova H. Habersberger P. Jiru 《Catalysis Letters》1991,11(3-6):285-294
The catalyst behaviour of titanium silicalite, which was found the most active and selective catalyst for liquid-phase ammoximation of cyclohexanone to the corresponding oxime with hydrogen peroxide, was investigated in the gas-phase ammoximation with molecular oxygen in and compared with those of pure silicalite and samples of vanadium and chromium silicalites. The results showed that Ti-silicalite is a selective catalyst not only in the reaction with hydrogen peroxide but also in the reaction with molecular oxygen. However, a big limitation was found in the poor activity of the silicalites which do not allow to reach high oxime yields. 相似文献
75.
No authorship indicated 《Canadian Metallurgical Quarterly》2004,59(8):728
Provides the biography of Dante Cicchetti and announces that he has received the APA Award for Distinguished Senior Career Contributions to Psychology in the Public Interest (2004) for his seminal role in bridging theory, research, and practice by fostering the emergence and coalescence of the field of developmental psychopathology. A selected bibliography is also provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
No authorship indicated 《Canadian Metallurgical Quarterly》2006,61(8):811
Presents the citation for Anthony D. Wagner, who received the Award for Distinguished Scientific Early Career Contributions to Psychology (cognition and human learning) "for outstanding and innovative research on the neural basis of memory and executive control." A brief profile and a selected bibliography accompany the citation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
Low carbon steel was oxidized over the temperature range 1000‐1250°C in O2‐CO2‐H2O‐N2, O2‐H2O‐N2, and O2‐CO2‐N2 gas mixtures. Oxidation times were 12‐120 min. and the scales were 50‐2000 μm thick. The variations of these parameters were chosen to elucidate the phase composition of oxide scales under conditions similar to those of reheating furnaces in hot strip mills, using either thin slab casting or conventional casting and rolling technology. Two types of scales have been observed which are influenced by the furnace atmosphere, oxidation time, and temperature. The first type is a crystalline scale with an irregular outer surface, composed mostly of wustite (FeO), and a negligible amount of magnetite (Fe3O4). The second type is the classical three‐layer scale, composed of wustite (FeO), magnetite (Fe3O4), and hematite (Fe2O3). In general, the experiments showed that an increase in oxidation time decreased the percentage of wustite while the percentages of magnetite and hematite increased. A rise in oxygen concentration in the gas mixture increased the percentages of magnetite and hematite, confirming earlier experimental findings. In water vapour‐free atmospheres O2‐CO2‐N2, the oxide scales had a low percentage of wustite, and high percentage of magnetite and hematite. Carbon dioxide showed a small influence at 1100°C, and a negligible one at 1250°C. 相似文献
78.
介绍了太钢板坯连铸水处理系统的工艺流程,分析了连铸浊环水水质存在的问题。通过对冷却塔部分、铁皮坑、水泵调速等改造,以及选用新的水质稳定剂,使水质明显好转。 相似文献
79.
The role of gas phase CH3 radicals in the oxidative coupling of CH4 over 1 wt% Sr/La2O3 is supported by the observations that (i) this is a very effective catalyst for the generation of CH3 · radicals and (ii) the concentration of CH3 · radicals increases with temperature over the range of 450 °C–800 °C. 相似文献
80.
La-OMS-2催化剂催化甲苯氧化制苯甲醛 总被引:1,自引:0,他引:1
合成了氧化锰八面体(OMS-2)分子筛,采用离子交换法和浸渍法制备了稀土金属La改性的OMS-2分子筛(La-OMS-2)催化剂,并用于甲苯液相选择性氧化制苯甲醛,考察了催化剂用量、反应温度、反应时间、氧气流量及溶剂种类对甲苯转化率和苯甲醛选择性的影响,对La-OMS-2催化剂进行了X射线衍射表征和BET比表面积测定。实验结果表明,离子交换法制备的La-OMS-2-A催化剂的活性高于浸渍法制备的La-OMS-2-B催化剂,在甲苯0.1mol、溶剂冰乙酸10mL、氧气流量60mL/min、La-OMS-2-A催化剂用量0.10g、反应温度353K、反应时间1.0h的条件下,甲苯转化率达61%,苯甲醛收率为56%。加入La对OMS-2分子筛中的MnO晶格结构产生了影响,提高了苯甲醛的收率。 相似文献