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91.
Gaurang Pant Prakaipetch Punchaipetch M. J. Kim Robert M. Wallace Bruce E. Gnade 《Thin solid films》2004,460(1-2):242-246
Physical and electrical properties of hafnium silicon oxynitride (HfSixOyNz) dielectric films prepared by UV ozone oxidation of hafnium silicon nitride (HfSiN) followed by annealing to 450 °C are reported. Interfacial layer growth was minimized through room temperature deposition and subsequent ultraviolet/ozone oxidation. The capacitance–voltage (C–V) and current–voltage (I–V) characteristics of the as-deposited and annealed HfSixOyNz are presented. These 4 nm thick films have a dielectric constant of 8–9 with 12 at.% Hf composition, with a leakage current density of 3×10−5 A/cm2 at Vfb+1 V. The films have a breakdown field strength >10 MV/cm. 相似文献
92.
Engineering Aspects of the Integration of Chemical and Biological Oxidation: Simple Mechanistic Models for the Oxidation Treatment 总被引:1,自引:0,他引:1
Santiago Esplugas Sandra Contreras David F. Ollis 《Canadian Metallurgical Quarterly》2004,130(9):967-974
Oxidation processes can oxidize biorecalcitrant compounds into biodegradable intermediates, which in turn can be treated less expensively by a subsequent biological process. To design such a two-step (chemical+biological) process to treat poorly characterized wastewaters, it is useful to model the time evolution of characteristic global variables, chemical oxygen demand (COD) and biochemical oxygen demand (BOD), in order to develop a useful treatment strategy based upon these classical variables. We consider two simple model reaction networks, requiring three- and five-rate constants, respectively. The first model, proposed recently, involves conversion of a nonbiodegradable species, C, into a single biodegradable intermediate S. Here, biodegradable compounds are immediate kinetic products of oxidation. In general, it is not probable that a single recalcitrant compound undergoes a single-step reaction to CO2. However, when working with complex undefined wastewaters streams, single-step reactions may be used to simplify. The second new model corresponds to a lag time in BOD formation due to the necessity of multiple partial oxidations to reach a first biodegradable intermediate. The second network includes two intermediates, I and S, which are, respectively, nonbiodegradable and biodegradable. We then compare model behavior with an unfortunately sparse literature on BOD and COD values versus time in chemical reactors, and demonstrate the convenience of the first model, and the occasional necessity of the second, which reflects the presence of early intermediates which are nonbiodegradable. 相似文献
93.
Molecular basis of lubrication 总被引:8,自引:0,他引:8
The advent of micro-electromechanical devices (MEMs), sensors, actuators, microsystems, and nanotechnology have called to attention the effect of friction on moving parts in nano/micro devices. To take full advantage of the opportunity to sense, compute, and actuate in real time, fast-moving parts are often necessary or desirable. As the scales of the components shrink, adhesion, stiction, friction, and wear become a significant technological barrier for the successful deployment of durable devices. Most current devices in production avoid such contacts.The nature of the surface contacts, as component scale moves from macro to micro to nano, is dominated by surface forces that normally are dwarfed by mechanical loading. Therefore nanolubrication needs to take into account different factors than conventional lubrication concepts. This paper compares traditional lubrication concepts and those necessary for nanolubrication and proposes various nanometer scale thick lubricating film designs as a means to control the surface properties of surfaces at nano/micro scales.Many of the concepts derive their origin from studies and observations from the magnetic hard disk technology where a “monolayer” of lubricant protects the system and has proven to be robust and safe. Examples from magnetic hard disks will be used to illustrate some of the concepts. 相似文献
94.
Leopoldo M. Nieto Gassan Hodaifa Salvador R. Vives José A. G. Casares 《Canadian Metallurgical Quarterly》2010,136(11):1309-1313
Olive-oil production generates high and variable amounts of wastewaters from the olives and olive-oil washing (OMW), resulting to great environmental impact. These waters are normally stored in large holding ponds for evaporation during the summer. The present study examines the chemical-oxidation process using ferric chloride catalyst for the activation of H2O2 (Fenton reaction). Tests have been made on an industrial scale. The final average value of chemical oxygen demand (COD) was close to 371?mg?O2?L?1 (%CODremoval = 86%, CODinitial = 2684?mg?O2?L?1), and the water produced can be used for irrigation or can be discharged directly into the municipal wastewater system for tertiary treatment. 相似文献
95.
JIN Huiming FELIX Adriana 《机械工程学报(英文版)》2008,21(3):16-19
The isothermal oxidizing kinetics of Co-40Cr alloy and its yttrium ion-implanted samples are studied at 1 000 ℃ in air by thermal-gravity analysis (TGA). Scanning electronic microscopy (SEM) is used to examine the Cr2O3 oxide film's morphology after oxidation. Acoustic emission (AE) method is used in situ for monitoring the cracking and spalling of oxide films formed on both samples during oxidizing and subsequent air-cooling stages. Theoretical model is proposed relating to the film fracture process and is used for analyzing the acoustic emission spectrum both on time domain and on AE-event number domain. It is found that yttrium implantation remarkably reduces the isothermal oxidizing rate of Co-40Cr and improves the anti-cracking and anti-spalling properties of Cr2O3 oxide film. The reasons for the improvement are mainly that the implanted yttrium reduced the grain size of Cr2O3 oxide, increased the high temperature plasticity of oxide film, and remarkably reduced the number and size of Cr2O3/Co-40Cr inteffacial defects. 相似文献
96.
高炉煤粉喷枪破损机理分析 总被引:1,自引:1,他引:0
高炉喷煤是现代高炉冶炼的一项重大技术革命,煤粉喷枪寿命直接影响喷煤操作与高炉正常生产,因此探索喷枪破损机理、研制长寿命喷枪成为高炉喷煤技术的重要课题。作者对某高炉实用喷枪进行跟踪监测,在正常工况下,材质为1Cr18Ni9Ti的喷煤枪平均寿命为32天。失效原因为表面氧化和煤粉流冲蚀磨损所致。本文从反应热力学分析了喷枪外表面氧化损坏机理,并由微切削理论解释了喷枪内壁出现沟状磨损痕迹及气固两相流动导致喷枪下半部分先磨损破口的原因。 相似文献
97.
氧化亚铁硫杆菌的筛选及其特性研究 总被引:4,自引:0,他引:4
从广东云浮一硫铁矿的酸性废水中分离出一株氧化亚铁硫杆菌,对其菌落形态和细胞形态进行了初步的探讨,研究了温度、初始pH、Fe2+初始浓度、接种量对细菌氧化Fe2+的影响。试验结果表明,该菌在pH=2 0、温度30~35℃活性最强,同时加大接种量也可以缩短细菌的迟缓期,培养基中过高的Fe2+浓度对该菌生长起抑制作用。 相似文献
98.
铜矿石中硫酸铜的自然变化规律 总被引:3,自引:1,他引:2
铜矿石从坑下采出后,硫酸铜仍继续不断生成,其生成量与矿石自然堆放时间及黄铁矿含量成正比关系,矿石粒度愈细硫酸铜的生成速度愈快,矿石中硫酸铜生成速度最快的时间是矿石采出后的头五天,硫酸铜主要由次主硫化铜氧化而成。 相似文献
99.
100.