Impact of Small Steel Spheres on the Surfaces of "Normal" and "Anomalous" Glasses

High-speed photography (framing rate of 10⁶ s^-1) has been used to follow the formation and growth of damage in a number of oxide glasses when impacted with 1-mm-diameter steel balls at velocities of 150 m· s^-1 or higher. Silicate, germanate, and borate glasses were studied in order to clarify the importance of "anomalous" vs "normal" elastic characteristics on their impact behavior. As expected it was found that glasses in these systems which are "anomalous" showed impact behavior which had earlier been seen in silica and borosilicate glass, whiie those glasses which are "normal" showed behavior similar to that shown by soda-lime silica glass. On the other hand, although B₂O₃ has been characterized as "normal," its impact, as well as its quasi-static behavior, appears to put it in a class by itself. In this case, no cracking is observed during loading up to 150 m·s^-1, while radial and lateral cracking are seen during unloading.     

"温州打火机"和"广东瓷砖"反倾销案的比较与启示

我国加入WTO后,对外贸易飞速发展,但随之而来的国外反倾销案例也逐渐增多。本文以温州打火机遭遇欧盟反倾销和广东瓷砖遭遇印度反倾销为例进行对比,分析他们遭遇国外反倾销的原因以及两种截然不同的结果,从中归纳出一些经验和教训,为今后企业应对国外反倾销提供有益借鉴。     

"枷锁"自非无情物

以写旧诗为例,说明“枷锁”：道是无情却有情。“枷锁”,形成某种局限,会给人们以不便和繁难,但这并不可怕可憎。如果我们不把它看作桎梏,而是当成对自己的严格要求,在苛刻的规范之中激发自己的聪明才智和创造能力,从而跨进新的“自由王国”,常会取得超乎寻常的成就。     

由解决方案所想到的

从几则案例分析解决方案的特点、构成及背后所蕴含的竞争理念.建议供应商更新理念,制定长期发展战略,加大投入,开发拥有自主知识产权的专有技术,深化企业改革,注重协同发展,提高企业的竞争力,推动我国硫酸工业健康稳定地发展.     

Properties of Multilayered Interphases in SiC/SiC Chemical-Vapor-Infiltrated Composites with "Weak" and "Strong" Interfaces

The interfacial properties of SiC/SiC composites with interphases that consist of (C-SiC) sequences deposited on the fibers have been determined by single-fiber push-out tests. The matrix has been reinforced with either as-received or treated Nicalon fibers. The measured interfacial properties are correlated with the fiber-coatingbond strength and the number of interlayers. For the composites reinforced with as-received (weakly bonded) fibers, interfacial characteristics are extracted from the nonlinear portion of the stress-displacement curve by fitting Hsueh's push-out model. The interfacial characteristics are controlled by the carbon layer adjacent to the fiber. The resistance to interface crack growth and fiber sliding increases as the number of (C-SiC) sequences increases. For the composites reinforced with treated (strongly bonded) fibers, the push-out curves exhibit an uncommon upward curvature, which reflects different modes of interphase cracking and a contribution of fiber roughness.     

模糊控制在工业过程控制中的应用

本文对模糊控制的产生、发展及现状作了介绍,提出了模糊控制能解决的四项有重大经济和社会效益的课题。     

新品种丰花玫瑰与紫枝玫瑰出油率及成分的探讨

玫瑰是一种香原料植物,其鲜花提取的精油应用于高档化妆品及日用品的凋香。丰花玫瑰和紫枝玫瑰是经过有性杂交培育出的新品种。在一年中均能多次开花,但集中开花期只有两次,以后便是零星开花。经过两年的鲜花出油率提取实验发现,不仅两个品种的鲜花出油率不同,即使同一品种,不同花期的鲜花出油率亦不同,而且差别还很大。经山东检测中心测试分析,丰花玫瑰和紫枝玫瑰的鲜花提取的精油的化学成分及其含量也存有差别。     

"Classical" Superplasticity of SiAlON Ceramics

"Classical" superplasticity of SiAlON ceramics with the nominal composition (Y _x Li _y )_{0.6/(3 x + y )}Si_8.9Al_3.1O_2.5N_13.5 is reported in this study. During deformation, these materials exhibit little microstructural evolution, with negligible growth of elongated β'-phase grains and minimal texture formation. Excellent formabilities are obtained in the temperature range of 1500°-1600°C in compression, where a strain rate of 10⁻² s⁻¹ has been achieved, and in punch stretching, where a strain rate of 1.2 × 10⁻³ s⁻¹ has been used successfully. Flow stresses are found to be dramatically affected by the viscosity of the grain-boundary phase and decrease as the amount of lithium addition increases. Fracture stress also is compositionally dependent and decreases as the lithium content increases. As the overall formability is determined by the competition between fracture and deformation, maximum formability coincides with a maximum ratio of fracture stress to forming stress at an intermediate lithium composition. Finally, all materials exhibit higher room-temperature bend strength after postforming annealing. Thus, transient superplastic deformation does not impair the ultimate mechanical properties of the materials.     

“双碳”目标下膜技术发展的思考

实现碳达峰和碳中和,本质在于使经济社会发展彻底摆脱对含碳矿产资源的依赖,其关键在科技创新。作为一种高效节能的共性分离技术,膜技术在这个过程中可以发挥怎样的作用？本文从零碳能源重构、低碳流程再造、非二气体减排及负碳体系构建四个方面详细阐述了膜技术在实现“双碳”目标的关键技术途径中所发挥的重要作用,主要包括零碳电力存储、绿氢制备及利用、工业流程优化及节能降耗、CO₂及非二气体捕集、CO₂转化再利用等。文中分析了相关领域膜技术的发展现状,并对“双碳”目标下我国未来膜技术的研究方向和发展目标进行了展望,指出通过一系列颠覆性膜技术的大规模应用,可助力实现可再生能源成本全球最低、低碳流程再造代价最小两大战略目标,为我国实现碳中和提供坚实的技术支撑。     

Tensile Creep of Alumina-Silicon Carbide "Nanocomposites"

The tensile creep behavior of an (Al₂O₃-SiC) nanocomposite that contains 5 vol% of 0.15 μm SiC particles is examined in air under constant-load conditions. For a stress level of 100 MPa and in the temperature range of 1200°–1300°C, the SiC reduces the creep rate of Al2O3 by 2–3 orders of magnitude. In contrast to Al₂O₃, the nanocomposite exhibits no primary or secondary stages, with only tertiary creep being observed. Microstructural examination reveals extensive cavitation that is associated with SiC particles that are located at the Al₂O₃ grain boundaries. Failure of the nanocomposite occurs via growth of subcritical cracks that are nucleated preferentially at the gauge corners. A modified test procedure enables creep lifetimes to be estimated and compared with creep rupture data. Several possible roles of the SiC particles are considered, including (i) chemical alteration of the Al₂O₃ grain boundaries, (ii) retarded diffusion along the Al₂O₃-SiC interface, and (iii) inhibition of the accommodation process (either grain-boundary sliding or grain-boundary migration).     

对“恒沸精馏”的质疑

本文通过对“共沸”与“恒沸”概念的分析和由来的追踪,指出了目前化工原理教学中“恒沸精馏”的称谓造成了概念混乱的缺陷和弊端,提出了将有共沸物生成的精馏过程一律称为“共沸精馏”的建议。     

中低低变换工艺的应用

介绍无饱和热水塔中低低变换工艺的技术改造情况 ,给出了工艺流程和主要设备 ,阐述了催化剂的升温还原过程和生产运行及存在的问题     

“AA”饲料添加剂的制备

本文介绍了对氨苯基胂酸饲料添加剂的制备及应用效果,其毒性及残留测定结果均符合规定。     

内,外环半包覆氟塑料“O”形圈的研制

主要介绍内、外环半包覆四氟膜“O”形圈的研制，该技术已用于无油润滑密封和液压、气动往复密封。可降低摩擦系数，提高密封的可靠性和使用寿命。     

“激光测窑”方法的改进

本文介绍了用激光测量回转窑筒体中心线（通常称为“激光测窑”）方法的改进，改进后的方法在测量和计算等方面有了较大改进，减少了测量误差     

Jonker "Pecir" Analysis of Oxide Superconductors

Data for the normal state of the superconducting oxide systems YBa₂Cu₃O_6+y, and the nonsuperconducting system La₃Ba₃Cu₆O_12.5+y, when plotted as thermoelectric coefficient versus logarithm of conductivity, exhibit Jonker "pear" behavior, confirming the semiconducting character of these materials. The symmetry of the plots indicates similar conduction parameters (density-of-states (DOS), transport constants, and mobilities) for p - and n -type mechanisms. Band gaps on the order of 0.5 eV are obtained. DOS—mobility products for the above-mentioned systems and La_2-xBa_xCuO₄ and Bi₂Sr₂CaCu₂O₈ scale roughly according to the density of copper ions in these materials and fall in the range 10²⁰ to 10²¹ (cm·V·s)⁻¹. Assuming DOS equal to copper content results in mobilities on the order of 0.15 cm²·V⁻¹· s⁻¹. These results are discussed in terms of possible semiconduction mechanisms.     

传递课程教学刍议

本文介绍了传递教学中把握课程的抽象特征、数学特征和方法论特征的一些体会,以及对传质教学内容改革方面的分析与尝试。强化对课程特征的认识,可以使学生理解课程内容的实用性,掌握化工过程建模的思路。     

"绿色"清洗之路

石油高价位以及飓风Katrina将对未来一年全球表面活性剂工业产生深远的影响。介绍了全球表面活性剂工业的现状，具体分析了供应链、原油和主原料等因素对表面活性剂产业链的影响。指出了表面活性剂工业的发展趋势。     

Toward quantitatively fluorescent carbon-based "quantum" dots

Carbon-based "quantum" dots (or "carbon dots") are generally defined as surface-passivated small carbon nanoparticles that are brightly fluorescent. Apparently, the carbon particle surface passivation in carbon dots is critical to their fluorescence performance. An effective way to improve the surface passivation is to dope the surface of the precursor carbon nanoparticles with an inorganic salt, followed by the typical functionalization with organic molecules. In this work we passivated small carbon nanoparticles by a combination of the surface-doping with nanoscale semiconductors and the organic functionalization, coupled with gel column fractionation to harvest the most fluorescent carbon dots, which exhibited fluorescence emission quantum yields of up to 78%. Experimental and mechanistic issues relevant to potentially further improve the performance of carbon dots toward their being quantitatively fluorescent are discussed.     

炉管“红管”的原因分析和处理对策

介绍了合成氨装置一段炉炉管出现的"红管"超温现象,对炉管超温的原因进行阐述,并提出了处理对策。