MEASUREMENT OF ANODIC OVERVOLTAGE BY A MODIFIED CURRENT INTERRUPTION METHOD IN CRYOLITE-ALUMINA MELTS

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Hard arc-sprayed coating with enhanced erosion and abrasion wear resistance

A cored wire formulation, referred to as Alpha 1800, has been developed to produce tailored arc-sprayed coatings that are tough enough to resist particle impacts at 90° and sufficiently hard to deflect eroding particles at low impact angles. One millimeter thick coatings composed of ductile and hard phases with a Knoop hardness reaching 1800 kg/mm² were easily produced by arc spraying the cored wire with air. Coatings were (1) erosion tested at 25 °C and higher temperatures at impact angles of 25 and 90° in a gasblast erosion rig, (2) slurry erosion tested at impact angles of 25 and 90°, and (3) abrasion wear tested using the ASTM G-65 test procedure. Results show that coatings produced with the new cored wire are at least 5 times more erosion resistant and 10 times more abrasion resistant than coatings produced by arc spraying commercial cored wires. The performance of the new arc-sprayed coating can be compared with that of high-energy WC-based coatings. Maintaining their erosion resistance after being exposed to temperatures up to 850 °C and possessing good oxidation resistance, arc-sprayed coatings produced with the new cored wire are attractive for applications in many industrial sectors involving high temperatures.     

熔盐电解钛精矿制备钛铁合金的脱氧历程

以攀枝花地区的钛精矿为原料通过CaCl2熔盐电解工艺直接制备FeTi合金。主要通过不同时间间断实验对电解过程进行跟踪,结果表明以钛精矿为原料电解制备FeTi合金的过程中首先得到金属铁和钙钛矿,然后是钙钛矿电解得到钛的低价氧化物,最后是钛的低价氧化物电解得到钛和形成FeTi合金,通过阴极失重实验验证了分段反应的结论。最后对钙钛矿的形成机理进行了实验研究,得到CaTiO3形成有两个途径：（1）熔盐参与反应,并且是主要成因;（2）熔盐CaCl2水解得到CaTiO3。     

纳米二氧化硅抛光液对低k材料聚酰亚胺的影响

以3英寸的P型〈111〉硅片为衬底,经过旋涂固化制备低介电常数(低k)材料聚酰亚胺。对聚酰亚胺进行化学机械抛光(CMP),考察实验前后,纳米二氧化硅抛光液对低k材料的结构和介电常数。实验中应用了2种纳米二氧化硅抛光液:一种是传统的铜抛光液;另一种为新型的阻挡层抛光液。通过扫描电镜(SEM)和介电常数测试结果显示,2种抛光液对低k材料,不论是在结构还是电特性方面的影响都不大。经铜抛光液抛光后,k值从最初的3.0变到3.08;经阻挡层抛光液抛光后,k值从最初的3.0变到3.28。实践证明,这两种纳米二氧化硅抛光液可以应用于集成电路。     

Ultra-fast boriding of nickel aluminide

In this study, we explored the possibility of ultra-fast electrochemical boriding of nickel aluminide (Ni₃Al) in a molten borax electrolyte. Electrochemical boriding was performed at 950 °C for 15 min and at current densities ranging from 0.1 to 0.5 A/cm². The boride layers formed on the test samples were 50 to 260 μm thick depending on the current density. The mechanical, structural, and chemical characterization of the boride layers was carried out using a Vickers micro-hardness test machine, optical and scanning electron microscopes, and a thin film X-ray diffractometer. The hardness of boride layer was in the range from 800 to 1200 ± 50 HV depending on the load and the region from which the hardness measurements were taken. X-ray diffraction studies confirmed that the boride layers were primarily composed of Ni₃B, Ni₄B₃ and Ni₂₀AlB₁₄ phases. Structurally, the boride layer was very homogenous and uniformly thick across the borided surface area.     

Ultrasonic determination of the particle concentration in model suspensions and ice slurry

The development of ice slurry for refrigeration systems and the enhancement of its efficiency depend on an accurate control of the ice concentration. We present here an ultrasonic method capable to measure precisely the particle concentration in ice slurry. To calibrate the ultrasonic measurement, we first determine the sound velocity and attenuation in two model suspensions (glass beads/polyethylene glycol and polyethylene beads/vaseline oil) for different particle volume fractions. The experimental results show a good agreement with the predictions of the two-component models in the long-wavelength limit. Additionally, the sound attenuation reveals a clear signature of the aggregate formation in the nearly iso-dense suspension. We next conduct the measurement of the sound velocity in the polypropylene glycol ice slurry where the ice concentration changes with temperature. The ice concentrations extracted from our sound velocity measurements are well consistent with the values determined from the binary phase diagram.     

Optimization of the cathode material for nitrate removal by a paired electrolysis process

Ni, Cu, Cu₉₀Ni₁₀ and Cu₇₀Ni₃₀ were evaluated as cathode materials for the conversion of nitrate to nitrogen by a paired electrolysis process using an undivided flow-through electrolyzer. Firstly, corrosion measurements revealed that Ni and Cu₇₀Ni₃₀ electrodes have a much better corrosion resistance than Cu and Cu₉₀Ni₁₀ in the presence of chloride, nitrate and ammonia. Secondly, nitrate electroreduction experiments showed that the cupro-nickel electrodes are the most efficient for reducing nitrate to ammonia with a selectivity of 100%. Finally, paired electrolysis experiments confirmed the efficiency of Cu₇₀Ni₃₀ and Cu₉₀Ni₁₀ cathodes for the conversion of nitrate to nitrogen. During a typical electrolysis, the concentration of nitrate varied from 620 ppm to less than 50 ppm NO₃⁻ with an N₂ selectivity of 100% and a mean energy consumption of 20 kWh/kg NO₃⁻ (compared to ∼35 and ∼220 kWh/kg NO₃⁻ with Cu and Ni cathodes, respectively).     

煤中无机矿物组分在高浓度煤浆制备过程中的作用

煤中无机矿物质是煤的重要组成部分，对高浓度煤浆制备、煤浆性质产生重要影响。近１５年来，该领域进行的大量研究具有相当的广度和深度，对高浓度煤浆的制备，改善和强化浆体流变性及稳定性等发挥了积极作用。本文综述了国内外目前该领域研究现状和取得的一些成果。     

水煤浆添加剂研究评述

水煤浆成浆怀、流变性及静动态稳定性除了与煤质本身的性质密切相关外，还与添加剂的性能有关。８０年代以来，国外在水煤浆添加剂方面做了大量的研究工作研制及筛选聘批性能优良的分散剂及稳定剂。但是，到目前添加剂的研制剂的分子结构特征与煤质及煤表面物理化学性质有着密切的相关性，深入研究这种匹配规律，并建立相应的数据库，将会发迹以往水煤浆添加剂研制中的经验性，对添加剂的研制起理论指导作用。本文国内外水煤浆添加剂     

氨内参比法测定尿素熔融液中缩二脲含量

研究了尿素熔融液中缩二脲含量测定时各种消除氨干扰的方法，确定了氨内参比法可作为消除氨干扰的最佳方法，完善了该法应用时的具体操作步骤，建立了一个适用于尿素合成各工段尿液中缩二脲含量测定的简单、快速、准确的分析方法。