Recovery of High-Temperature Creep-Resistant Substructure in Rutile

Recovery of creep-resistant substructure in rutile was studied at 1000°, 1020°, and 1040°C. Specimens were crept under a stress of 10,000 psi to a strain early in the secondary stage of creep and then allowed to recover for varying periods under a residual stress of 400 psi. Recovery was detected by the increased creep strain which occurred when the 10,000 psi stress was reapplied. An apparent activation energy of 135,000 cal/mol was obtained for the recovery process. Experimental evidence suggests that the primary recovery mechanism involves the sweeping out of dislocation barriers within the material by the migration of dislocation walls or subgrain boundaries.     

真空挤压成型机真空度降低的原因及其改进

本介绍了真空挤压成型机的工作原理及造成真空度降低的原因，并详细论述了提高真空挤压成型机真空度应采取的措施。     

减压膜蒸馏热量回收过程研究

减压膜蒸馏作为一种新型的脱盐技术在海水淡化和高盐废水处理等方面具有广泛的应用价值。针对解决减压膜蒸馏过程中热量消耗大的问题展开了探索性研究,研制出了1套三级热量回收式减压膜蒸馏组件, 考察了不同操作条件对热量回收利用率的影响。研究结果表明,所设计的热量回收式组件能够有效回收利用减压膜蒸馏过程中的蒸汽潜热,而进料液温度、进料液流速和蒸汽透过侧真空度等操作条件都对其热量回收利用率具有一定程度的影响。为进一步提升减压膜蒸馏热量回收效率的研究和降低运行成本工艺技术的开发奠定了基础。     

空气管道出口处的负压问题

空气管道出口处负压现象的发现,打破了传统的空气管道终端压力分布理论,改变了人们长期形成的风机出口管道终端不会出现负压的观念.在阐明风机全压基本概念及其用途的基础上,着重从条件和原因方面,分析管道出口处出现负压的机理,并得出几点重要的结论.     

X-ray Absorption Near-Edge Structure of Grain-Boundary-Segregated Y and Zr in Creep-Resistant Alumina

X-ray absorption near-edge structure (XANES) depends on stereochemical features of coordination polyhedra around probe atoms. K -edge XANES of Y and Zr segregated in alumina grain boundaries has been obtained and analyzed using metallic Y and Zr, Y₂O₃, YAG, and monoclinic ZrO₂ as standards. Grain-boundary-segregated Y and Zr show a positive chemical shift, and the magnitude of the shift, as compared with that of Y₂O₃ and ZrO₂, respectively, is different for Y and Zr, indicating that, relative to Y₂O₃ and ZrO₂, charge transfers for the grain-boundary-segregated Y and Zr are different. This result is also supported by the strength of the threshold resonance. A pre-edge shoulder is seen in K -edge XANES for grain-boundary-segregated Y and Zr but not for Y₂O₃ and ZrO₂. This shoulder is attributed to the 1 s → 4 d transition, which is normally forbidden, but can occur because of d – p mixing, which is favored by a tetrahedral coordination configuration. These results suggest that some of the grain-boundary-segregated Y and Zr have coordination configurations with a well-defined tetrahedral symmetry. The XANES results are compared with those obtained from EXAFS. Implications of these results for understanding of the enhanced creep resistance in alumina are also discussed.     

Air Flow and Compression Work in Vacuum Dewatering of Paper

Dewatering on the paper machine takes place by gravity, suction, pressing, and evaporation. Optimizing the operation of the vacuum system is important, since the electricity consumption of the vacuum pumps might be one-fifth of the total electricity consumption of the paper machine. Vacuum dewatering involves large volumes of air penetrating the web. The present study presents four sets of measured air flow rates useful for designing industrial equipment. The mass flux of air increases with increasing applied vacuum and decreases with increasing basis weight. Paper technological parameters, such as fiber size and fiber flexibility, also influence the mass flux.     

真空玻璃的应力分析及强度设计

基于真空玻璃的典型结构特征,分析了大气压差、温差及风载荷作用下真空玻璃的应力分布特征,给出了最大弯曲拉应力定量计算公式。基于结构抗力设计方法,分析了长期和短期应力协同作用下真空玻璃的承载性能设计。结果表明,在给定基片厚度情况下,随着支撑物间距的增大,真空玻璃最大弯曲拉应力呈近似线性增长,在支撑物间距不变情况下,真空玻璃最大弯曲拉应力随基片厚度增大呈指数式下降趋势。温差引起的最大弯曲拉应力与玻璃基片厚度及长宽尺寸无关,但与膨胀系数有关,温差值与其引发的真空玻璃最大弯曲拉应力呈线性关系。相同条件下,真空玻璃抗风压性能弱于与其等厚度的单片玻璃。在长期和短期应力协同作用下,宜分别计算不同应力作用时间下真空玻璃的效应设计值进行校核。     

Growth of Ag and Au Nanoparticles on Reduced and Oxidized Rutile TiO2(110) Surfaces

The nucleation and growth of Au and Ag nanoparticles on rutile TiO₂(110)–(1 × 1) surfaces in different oxidation states is studied by means of photoelectron spectroscopy (PES) and scanning tunneling microscopy (STM). Au and Ag nanoparticles were found to bind much more strongly to oxidized TiO₂(110) model supports than to reduced TiO₂(110) surfaces, as directly revealed by STM. Detailed PES studies addressing small Au and Ag particles complete this picture and show that the PES core level spectra acquired on Au/TiO₂(110) and Ag/TiO₂(110) can be best described by fitting with two binding energy (BE) components. Particularly for coverages in the sub-monolayer regime and for depositions at low temperatures (100 K) the PES core level spectra must be fitted with at least two BE components. The higher BE component is attributed to atoms at the interface between the metal clusters and the TiO₂(110) support. For Au/TiO₂(110), the two BE components were evident in the core level spectra for higher coverage than for Ag/TiO₂(110), consistent with different growth modes for Au (initially 2D) and Ag (3D) on TiO₂(110). Finally, strong evidence for charge transfer from Ag nanoparticles to the TiO₂(110) support is presented, whereas the charge transfer between Au nanoparticles and the TiO₂(110) support is very small.     

减压法合成醇醚和酚醚羧酸盐

醇醚和酚醚羧酸盐是一种性能温和、无毒、生物降解性表面活性剂。报道了以醇醚 (酚醚 )、一氯乙酸和氢氧化钠为原料通过减压除水法合成醇醚 (酚醚 )羧酸盐的方法和限制一氯乙酸钠的情况下合成反应的最佳条件。     

Kinetics of Carbothermal Reduction of Quartz Under Vacuum

The kinetics of reduction of 0.2 mol of –70?mesh quartz particles by 0.2 mol of graphite were determined in a batch reactor between 0.25 and 10⁻⁰ torr. The effects of temperature, CO partial pressure, SiO₂ phase transformation, and alkali and alkaline-earth oxide additives on the rate of reaction were studied. Increasing CO overpressure retarded carbothermal reduction. At 1400−C, addition of 5 wt% alkali oxide inhibited the reaction, whereas the same amount of alkaline-earth oxide decreased the induction time; CaO was the best promoter. The initial reaction rate obeyed the cubic power law of nucleation growth at weight losses <15%, with an apparent activation energy of 77 kcal/mol. At higher weight losses, the Austin-Rickett equation with an exponent near 2 was more applicable. The results are consistent with a model based on a transitory phase intermediate.     

回收塔空冷器风机改造

进入夏季后,回收塔空冷器换热效果明显变差,造成生产负荷下降20%,分析原因进行技改,技改后达到良好的效果。     

造气吹风气回收技术的成功使用

总结造气吹风的设计和操作要点,该技术的使用,取得了节能降耗等综合效益。     

非均匀地应力下套管应力的敏感性分析

套损是影响地下储气库井筒完整性的关键问题,制约着储气库长期的安全生产。为此,基于弹性力学理论,运用有限元分析方法,建立了理想固井状态下的套管-水泥环-地层组合分析模型,对受非均匀地应力时组合体各层Mises应力的分布规律进行了研究,讨论了套管应力对水泥环与地层的弹性参数变化的敏感程度。结果表明：套管内壁的应力明显高于水泥环和地层内壁的应力且沿井周呈非均匀分布;地层弹性模量对套管内壁应力的影响最为显著,套管应力随地层弹性模量的增加急剧减小;其次为水泥石弹性模量,当其与地层弹性模量相同时,套管应力达到最大。该研究成果可为优化套管完井设计和预防套管损坏提供理论参考。     

Recovery of Water from Atmospheric Air in Arid Climates

Abstract

The possibility of using hydrated salts supported on carrier beds for extracting water from cool night air and solar energy for recovering the moisture for use as drinking water is dealt with. Equipment for obtaining sorption data in the laboratory is described. The rate of water adsorption by salts from air is a linear function of relative humidity, the amount adsorbed depending on the partial pressure of water exerted by the hydrated salt or by the aqueous salt that results on exposure to the moist air. To assure maximum adsorption it is important to select salts whose saturated aqueous solution exhibits minimal aqueous tension. Hydrated salts supported on carriers, composed of as widely different materials as porous glass, sand, and fibrous board, all release water equally well on heating, despite their large differences in physical makeup.     

循环冷却水回水的废热利用

根据化纤厂全新风工艺空调系统每年冬季需大量蒸汽对新风进行加热,而工艺用循环冷却水却需通过冷却塔降温处理大量废热的现状,通过调查研究和理论校核计算,由初步试验到全面推广,将循环水回水引入空调预热新风,从而降低了大量蒸汽消耗。     

Studies on Hot Air and Microwave Vacuum Drying of Wild Cabbage

Abstract

Wild cabbage was dehydrated by a combination of hot-air drying and microwave vacuum drying. It showed that the total drying time was reduced by about half while the retention values of the nutrient components and chlorophyll were improved significantly. Microwave/vacuum-dried products had a more porous texture. Finally, microwave drying showed effective bactericidal action in the product with acceptable quality of dried product.     

Electric Strength of Polymers Under Vacuum at Cryogenic Temperatures

Abstract

The electric strength of solid polymers under high vacuum is investigated at a temperature ranging from 293°K down to that of liquid helium (5°K) under power frequency alternating- and direct-voltages. The electric strength of polymers was found to be very dependent on the pre-breakdown partial discharges when measured in cryogenic medium whether gas or liquid. When helium was used as coolant, discharges may extend very far from the electrodes and thus exerted high electric stresses on large areas of the sample under test. These discharges may produce flash-over and serious troubles. It may also lead to localised breakdown of polymers which may give apparent reduction in dielectric strength.

A large increase in the electric strength of polymers was observed when used at cryogenic temperatures under vacuum; the increase was very significant for polyethylene and polyimide specially under direct voltages.

The results showed promising properties and it is concluded that the high vacuum will offer the solution to many insulation problems at liquid helium temperatures in cryogenic and superconducting equipment.     

Studies on Hot Air and Microwave Vacuum Drying of Wild Cabbage

Wild cabbage was dehydrated by a combination of hot-air drying and microwave vacuum drying. It showed that the total drying time was reduced by about half while the retention values of the nutrient components and chlorophyll were improved significantly. Microwave/vacuum-dried products had a more porous texture. Finally, microwave drying showed effective bactericidal action in the product with acceptable quality of dried product.