Automated Sediment Erosion Testing System Using Digital Imaging

Measurement of vertical profiles of the critical shear stress, τc, and the erosion rate, E, from the same undisturbed sediment core is crucial for modeling the resuspension of fine-grained natural sediments. The automated sediment erosion testing system (ASETS) was developed to determine profiles of τc and E with centimeter spatial (vertical) resolution in an undisturbed (Shelby tube) sediment core, whose surface was eroded by steady turbulent flow through a flume. The unique feature of ASETS is that it is a real-time imaging method that accurately determines the position of the core surface during erosion for both calculating the vertical profile of E and controlling a motor-driver system that automatically pushes up the core to maintain its surface flush with the flume bottom. Undisturbed, field cores were tested over a range of flow (average bed shear stress, τb) conditions. The amount of eroded sediment from both optical backscattering measurements and the imaging method were in good agreement, which validated ASETS. Measured vertical profiles of τc and E were similar to those reported in literature. E correlated well with (τb?τc)2, which agrees with previous results in literature.     

Fabrication and Testing of Cuff Connections for GFRP Box Sections

A new type of connection between beams and columns has been designed and fabricated specifically for use with glass fiber reinforced plastic (GFRP) pultruded box members. The work is built on previous efforts in the area of GFRP connections, which demonstrated that innovative connections between box sections are superior to connections based on concepts from steel construction for connecting I-beams. The new connection element is designed as a monolithic connection for frame members and is fabricated using a vacuum assisted resin transfer molding process. Individual connection specimens have been fabricated and tested to verify their performance under cyclic static loads in a test frame designed to simulate conditions in a moment resisting frame. The connection configuration was found to fare better from the standpoint of both strength and stiffness in comparison with previous attempts at developing GFRP beam-to-column connections.     

Experimental Investigations on Slurry Erosion Behaviour of HVOF and HVOLF Sprayed Coatings on Hydraulic Turbine Steel

Slurry erosion behaviour of high velocity oxy fuel (HVOF) and high velocity oxy liquid fuel (HVOLF) sprayed coatings on hydraulic turbine material (i.e. CA6NM steel) was investigated at different levels of various parameters. The 50 % (WC–Co–Cr) and 50 % (Ni–Cr–B–Si) coating powder was deposited on CA6NM steel samples by HVOF and HVOLF thermal spraying techniques. Erosion tests were conducted on self-made erosion test rig with various factors as explained in the "experimentation" section. Coated and uncoated samples of CA6NM steel were investigated by following a design of experiments based on the L₉ Taguchi technique, which was used to obtain the data of erosion test in a controlled way. Four parameters used in L₉ experiment were velocity, impact angle, slurry concentration and average particle size. The study revealed that the velocity, impact angle and slurry concentration were most significant among various parameters, influencing the wear rate of the coatings. The average particle size did not show any significant effect on both the coatings. In comparison, coated samples showed approximately two times better results in erosion resistance than uncoated samples. Scanning electron microscopy of eroded surface showed different mechanisms of erosion on different samples under various conditions.     

Slurry Erosion Characteristics and Erosive Wear Mechanisms of Co-Based and Ni-Based Coatings Formed by Laser Surface Alloying

In the present work, an attempt has been made to study the slurry erosion properties and operating erosive wear mechanisms of Co-based Stellite 6 and Ni-based Colmonoy 88 coatings, and also to list the conditions at which maximum and minimum erosion rates occur. Laser surface alloying (LSA) has been done on 13Cr-4Ni steels with commercial Co-based Stellite 6 and Ni-based Colmonoy 88 powders. Slurry erosion tests have been conducted on LSA-modified steels for a constant slurry velocity of 12 m/s and for a fixed slurry concentration of 10 kg/m³ of irregular, sharp-edged SiO₂ particles with average sizes of 375 and 100 μm and at impingement angles of 30, 45, 60, and 90 deg. A mixed (neither ductile nor brittle) mode of erosion behavior for Stellite 6 coatings and a brittle mode of erosion behavior for Colmonoy 88 coatings were observed when these materials were impacted with particles with an average size of 375 μm, whereas only a brittle mode of erosion was observed for both Stellite 6 and Colmonoy 88 coatings when impacted with particles with an average size of 100 μm. Mainly, chip formation, chip fracture, microcutting, plowing, and crater lip and platelet formation were observed for Stellite 6 coatings and progressive fracture of carbides, carbide pullout and carbide/boride intact were observed for the case of Colmonoy 88 coatings.     

微纳米 涂层在 介质中的抗泥沙冲蚀性能研究

采用超音速火焰喷涂 (HVOF) 工艺制备了微纳米、 纳米和普通结构 WC-10Co4Cr 金属陶瓷涂层, 测量了涂层的显微硬度、 孔隙率和开裂韧性, 分析了三种 WC-10Co4Cr 涂层在 3.5wt% NaCl 溶液中的腐蚀电位和腐蚀电流密度, 研究了喷涂层在 NaCl 介质中的抗泥沙冲蚀性能, 并探讨了涂层在 NaCl 介质中的泥沙冲蚀机理。 结果表明： 微纳米 WC-10Co4Cr 涂层具有最优异的电化学性能; 相比于纳米、 微米涂层, 微纳米涂层的抗泥沙冲蚀磨损性能分别提高了 38% 和 78%。 微纳米 WC-10Co4Cr 涂层致密的组织结构、 高显微硬度 (1126HV0.3) 和高开裂韧性 (4.66MPa·m1/2) 有效减弱了泥沙冲蚀过程中的机械冲刷作用和电化学腐蚀作用。     

纳米WC增强Ni基合金喷熔层在不同介质中抗泥浆冲蚀性能研究

采用氧乙炔火焰喷熔工艺制备了Ni60CuMo和纳米WC增强Ni60CuMo两种Ni基合金喷熔层,采用XRD、SEM方法分析了喷熔层的组织结构,测量了喷熔层的硬度和电化学性能;研究了两种喷熔层在淡水和3.5wt.%NaCl介质中的抗泥浆冲蚀磨损性能。结果表明,纳米WC增强Ni60CuMo合金喷熔层的组织结构为纳米WC呈块状均匀镶嵌在γ相固溶体和Cr23C6、Cr7C3等硬质相之间,形成弥散强化,使其硬度提高了约13%;纳米WC增强的Ni基合金喷熔层在3.5wt.%NaCl介质中比Ni60CuMo喷熔层具有更低的腐蚀电位与更高的腐蚀电流密度,它在淡水和3.5wt.%NaCl介质中的抗泥浆冲蚀磨损性能分别比Ni60CuMo喷熔层提高了约53%和20%。纳米WC的加入显著提高了Ni基合金喷熔层的抗泥浆冲蚀性能,但在3.5wt.%NaCl介质中,由于WC与NiCr合金之间形成了大量微电池,加速了喷熔层的腐蚀磨损,使其抗泥浆冲蚀性能的增强效果受到削弱。     

Effect of Electromagnetic Stirring on Fabrication of Al-Si Semi-Solid Slurry by the Cup Cast Method

Rheocasting with semi-solid slurry has been widely used in industrial processes in recent years.The Cup-Cast method is one of the most effective ways to produce semi-solid slurry for rheocasting.In order to study the effect of electromagnetic stirring on the fabrication of semi-solid slurry,we have applied the Double-Axis-Electromagnetic Stirrer(DAEMS)to the Cup-Cast method.Microstructure of the slurry was observed by an optical microscope and Electron Back-Scatter Patterns(EBSP).The results indicated that the electromagnetic stirrer made it possible to accelerate the cooling rate of the melt,thus resulting in a higher quality slurry.     

新型Ag-5%C电接触材料的制备及其电弧磨损特性的研究

采用将高能球磨、还原剂液相喷雾化学包覆及粉末冶金相结合配以适量碳纳米管做为纤维增强体的工艺 ,制备出新型的Ag 5 %C(质量分数 )电接触材料。该材料具有优异的烧结致密性 ,烧结复压密度可达理论密度的 99.9%,而传统机械混粉工艺及国外发展的烧结挤压工艺同类材料仅能达到 97.0 %～ 98.4%;其硬度达到 64 5MPa ,大大超过同类触头 ;该新型材料由于C在基体中的均匀分布以及高烧结致密性 ,具有很好的导电性能 ,其电导率达到了 3 8 0m·Ω- 1 ·mm- 2 ,远超机械混粉工艺而接近烧结挤压工艺。经由ASTM触头材料试验机进行电磨损分断对比试验 ,发现与常规机械混粉同类触头相比 ,该材料同等条件下电弧磨损量小得多 ,且具有优异的电弧磨损特性 ,其电弧磨损量随分断次数呈指数小于 1的指数函数规律上升 ,即到分断后期其材料损耗量趋于稳定 ,有效抑制了触头分断电涡流磨损现象 ,这种优异的电弧磨损特性对于提高其材料耐电弧磨损性能具有重要意义。该材料有望成为一种可替代烧结挤压和机械混粉同类材料的新型Ag/C触头材料     

Leica VMHT显微硬度测试仪的调试与操作

详细地介绍了Leica VMHT显微硬度测试仪的调试步骤和方法及操作.并对怎样更好的达到实验效果进行了探讨.     

精铝槽与普铝槽焙烧启动工艺的对比分析

结合精铝槽与普铝槽的差异,对普铝槽焙烧启动工艺进行比较和分析,提出适合精铝槽焙烧启动的具体工艺。     

新式阴极结构铝电解槽技术在200kA电解系列生产实践

介绍了200 k A系列在应用新式阴极结构铝电解技术前的生产状况,同时对新式阴极结构电解槽的设计、焙烧、启动、启动后期及正常生产及取得的效果进行了介绍,实践表明,采用该技术的电解槽生产运行稳定,槽平均电压和吨铝直流电耗均大幅下降。     

Fabrication and Testing of Apparatus for Laboratory Simulation of Alaska Frozen Rock Encountered during Hydrate Gas Reservoir Coring

Gas hydrates are inclusion compounds in which gas is trapped in ice. They are widely found in nature in permafrost and deep-sea sediments and hold huge potential as a methane gas resource. As a result, a National Methane Hydrate R&D program was launched in 2000 by the United States Department of Energy. One of the projects under the program, run by the National Energy Technology Laboratory (NETL/DOE DE-FC26-01NT41331), is to drill, core, and test one gas hydrate well in the Prudhoe Bay/Kuparuk River area of northern Alaska. In this project, cores are studied to gather field data on a hydrate reservoir in permafrost regions. Tests were required to develop coring techniques and handling procedures on frozen rocks prior to actual coring in Alaska. These tests were performed at a Houston research facility where frozen rocks were prepared using an apparatus fabricated to simulate hydrate reservoir in permafrost. The permafrost formation was simulated with a water-saturated sand pack, which was frozen using liquid nitrogen. Frozen rocks of up to 3.6 m (12 ft) high and 0.254 m (10 in.) diameter were prepared with the apparatus. The setup was designed and evaluated in several stages. First, a computer model was developed to understand the rock-freezing process. Then a prototype setup was constructed to have similar radial dimensions as the full-scale apparatus, but with a smaller height. Several experiments were performed to test the prototype and the full-scale apparatus. The apparatus has been successfully employed to prepare frozen rock, thereby assisting in development of improved coring methodology for Alaskan permafrost hydrates exploration.     

一锅法合成异氰尿酸三苄基酯

对尿素为原料一锅法制备异氰尿酸三苄基酯的合成反应进行了研究．首先由尿素通过液相法合成异氰尿酸．不经分离继续与苄氯和三乙胺反应生成异氰尿酸三苄基酯．对反应条件及影响产率的各种因素进行了讨论．     

旋转焦罐的应用

随着干熄焦大型化的发展,方形焦罐的缺点日益突出,并逐渐成为淘汰设备,改用旋转焦罐。文中对方形焦罐和旋转焦罐的优缺点做了对比。旋转焦罐既提高了焦罐的容积效率,又降低了应力集中,并使料线成流线型。旋转焦罐的应用和推广将是未来的趋势。     

锑吹炼氧化锅的应用实践

通过锑氧化锅穿孔问题解决的实践摸索,找出锑氧化锅渗漏的主要原因,改变其结构,提高使用寿命。     

熔炼铅锅的改进

熔化铅的锅大多采用铸钢结构，由于铸造时，局部很可能存在缺陷，影响锅的使用寿命，于是对熔铅锅进行改进，将它改为锅炉钢板焊接结构，不仅延长了使用寿命，而且减轻了工人的劳动强度。     

Measurements of Sediment Erosion and Transport with the Adjustable Shear Stress Erosion and Transport Flume

Soil and sediments play an important role in water management and water quality. Issues such as water turbidity, associated contaminants, reservoir sedimentation, undesirable erosion and scour, and aquatic habitat are all linked to sediment properties and behaviors. In situ analysis is necessary to develop an understanding of the erosion and transport of sediments. Sandia National Laboratories has recently patented the Adjustable Shear Stress Erosion and Transport (ASSET) Flume that quantifies in situ erosion of a sediment core with depth while affording simultaneous examination of transport modes (bedload versus suspended load) of the eroded material. Core erosion rates and ratios of bedload to suspended load transport of quartz sediments were studied with the ASSET Flume. The erosion and transport of a fine-grained natural cohesive sediment were also observed. Experiments using quartz sands revealed that the ratio of suspended load to bedload sediment transport is a function of grain diameter and shear stress at the sediment surface. Data collected from the ASSET Flume were used to formulate a novel empirical relation for predicting the ratio of bedload to suspended load as a function of shear stress and grain diameter for noncohesive sediments.     

Performance and Leaching Assessment of Flowable Slurry

This project was conducted to evaluate the performance and leaching of controlled low strength materials (CLSM) incorporating fly ash and foundry sand. Two different CLSM (or flowable slurry) reference mixtures (equivalent to available production CLSM mixtures) were proportioned for unconfined compressive strength levels in the range of 0.3–0.7 MPa (50–100 psi), at 28 days, using two sources of ASTM Class F fly ash. For each reference mixture, other mixtures were proportioned using two sources of foundry sand (molten metal-casting mold sand) as a replacement for fly ash in the range of 30–85%. The ingredients of the slurry mixtures—fly ash, clean foundry sand, and used foundry sand—were tested for their physical and chemical properties and their leachate characteristics. Portland cement used as the primary binder was also tested for its properties. All CLSM mixtures made with and without foundry sand were evaluated for settlement, setting and hardening characteristics, compressive strength, permeability, and leachate characteristics. The leachate results of these CLSM-making materials were below the enforcement standards (ES) of the Wisconsin Department of Natural Resources (WDNR) ground-water quality standards (GWQS). They also met practically all the parameters of the drinking water standards. A number of CLSM mixtures incorporating fly ash and foundry sand are recommended for construction applications.     

多分层试井仪室内实验研究

为了能使多分层试井仪更好地应用于油田现场,在室内研究中,必须对仪器主要器件、部件进行性能调试.介绍几种较为重要的室内实验,如校验定值泄压阀、密封阀,测验双封隔器轴向拉拔力,模拟测试地层流体流动压力曲线.这几项实验研究为仪器在油田的实际应用提供依据,将提高多分层试片仪在应用中的可靠性和安全性.     

浆体管道输送技术及应用

介绍了长距离浆体管道水力输送技术的特点,结合白银天诚选矿公司尾矿输送实例,对浆体输送的实用性进行了评价。