定氧定碳和定氧定铝的热力学原理

文章根据炼钢过程中碳氧反应热力学和铝脱氧反应热力学,给出热力学平衡条件下碳氧关系和氧铝关系。结合具体的炼钢工艺控制,解读如何通过炼钢过程中的氧测定(传感器测氧)来达到测定钢液中碳含量和酸溶铝值的目的,即定氧定碳和定氧定铝。     

50Mn钢酸溶铝量与晶粒度关系的研究和应用

论述了酸溶铝对５０Ｍｎ钢本质晶粒度的影响，通过试验找出５０Ｍｎ钢最佳酸溶铝范围，并用于指导生产。     

酸溶铝含量对车轮性能的影响

拟在车轮钢冶炼中采用降低钢中加铝量的工艺以杜绝因大尺寸Al2O3夹杂导致的车轮次表面疲劳破损，但减少钢中加铝量会导致钢中酸溶铝含量的降低，是否会影响成品车轮性能值得关注。为此，进行了实物车轮奥氏体晶粒度对比试验分析及成品车轮性能的统计分析。分析结果表明，将车轮钢中酸溶铝含量降低至0．010％以下，在现热处理工艺下，车轮奥氏体晶粒度和性能未发生明显变化，降低钢中加铝量这一工艺值得推广。     

低温酸浸高铁铝土矿中铁和铝的溶出规律研究

采用低温酸浸法对广西高铁铝土矿中的铝和铁的溶出规律进行了研究,考察了硫酸浓度、浸出温度、浸出时间及液固比因素对铝土矿中铝和铁溶出率的影响.结果表明,最优浸出条件为浸出时间60min,浸出温度100℃,液固比5∶1,硫酸浓度20％.此条件下铁的浸出率为98.68％,铝的浸出率为3.02％,溶出比为32.68,可实现高铁铝土矿中铁和铝的分步溶出.对该浸出过程进行动力学分析研究表明,此条件下浸出过程属化学反应控制,其控制动力学方程为:lgk=3-1.83×10-31/T反应活化能Ea=35.11kJ/mol.     

粉煤灰盐酸法提铝后残渣的综合利用研究

神华集团自主研发的粉煤灰盐酸法协同提取技术,将粉煤灰中铝及有价元素镓、锂、钪等协同提取,最终将酸浸液中的有用成分全部回收利用。酸浸后剩余的固体残渣主要由非晶态的二氧化硅和氧化铝组成,活性较高,可以作为硅基产品原料来制备分子筛、保温板、瓷质砖、橡塑填料、白炭黑等。酸溶渣综合利用研究技术不仅解决了酸溶渣堆存带来的环境问题,而且又可获得较高利润,是循环经济产业链上重要的组成部分。     

SCR催化剂中钒钨钛含量的测定

试验首先采用6种不同酸配比的酸溶法和2种碱熔法对SCR催化剂进行前处理,采用电感耦合等离子体质谱法测定样品中钒、钨、钛含量。实验发现:需添加氢氟酸,否则钨、钛溶出率极低,钨在高温下易挥发,采用碱熔法溶出率低。试验通过对酸添加量,微波消解温度和消解时间的考察,进一步优化酸溶法,并以电感耦合等离子体质谱法测定样品中钒、钨、钛含量。结果显示:采用8 m L盐酸,2 m L硝酸和1 m L氢氟酸,在180℃下微波消解30 min,为SCR最佳前处理方案,钒钨钛的回收率分别为101.0%,100.7%,101.7%,相对标准偏差分别为1.0%,2.2%,0.3%,结果满意。     

酸溶法柔性光纤传像束的玻璃组成及性能

酸溶法柔性光纤传像束的单丝由芯料、皮料和酸溶玻璃构成。本文首先分别探讨了皮料玻璃的组成、化学稳定性和折射率以及酸溶玻璃的组成、酸溶特性和析晶性能。然后重点分析了芯料、皮料和酸溶玻璃的性能和工作参数的匹配问题。研究结果表明:皮料玻璃的混合碱效应不仅可以提高玻璃的化学稳定性,而且有利于提高光纤的机械强度。同时,控制酸溶玻璃中B2O3/SiO2比例可以较好地兼顾玻璃的酸溶特性和抗析晶性能。此外,酸溶法单丝作业芯、皮、酸溶玻璃工艺参数的匹配,不仅要求缩小它们在成纤温度范围内的粘度差异,而且应尽可能保持稳定的粘度比值。CDG2皮料玻璃、ASG2酸溶玻璃以及商用芯料玻璃的物理化学性质以及工作参数的匹配性可以满足柔性光纤传像束的要求。     

硅铝比对La负载粉煤灰基多孔陶瓷滤料的影响

以工业废弃物粉煤灰为主要原料,通过改变配料中的硅铝比来制备不同硅铝比的粉煤灰基多孔陶瓷基体.在基体表面负载稀土La,制得La负载粉煤灰基多孔陶瓷.研究了不同硅铝比对多孔陶瓷的物相、形貌、气孔率、酸溶率、体积密度、碎裂应力和La负载的影响.结果表明:钠钙斜长石含量越高,稀土La负载量越高;当硅铝比为1.55时,多孔陶瓷中钠钙斜长石含量为82％,负载La后Cr(Ⅵ)吸附量为0.7845 mg/g.     

碱熔法检测铁矿中全铁含量

铁矿石中全铁含量的测定通常采用常规的重铬酸钾容量法,主要为酸溶法和碱熔法.本文主要采取碱熔的试样处理方法,探讨其对全铁含量测定结果的影响.     

油页岩制油残渣制备氧化铝及其铝浸出率的研究

以抚顺东露天油页岩制油残渣为原料,用酸提法制备氧化铝,采用单因素考察法确定了抚顺东露天油页岩残渣提取氧化铝的酸溶反应最佳工艺条件为:煅烧温度850℃,煅烧时间1h,所需原料粒度0.074mm,盐酸浓度为12%,液固比为5∶1,酸溶反应温度100℃,反应时间1.5h,各项工艺指标在最佳工艺条件下,Al2O3浸出率为81.75%;采用均相化学沉淀法由酸溶反应得到的氯化铝滤液制备氧化铝的最佳工艺条件为:反应温度55℃,偏铝酸钠浓度0.4mol/L,乙酸乙酯与铝离子物质的量之比为1.7∶1,反应时间1.5h,表面活性剂的用量为总体系质量的0.3%。采用激光粒度分布仪、X射线衍射仪、X射线荧光光谱仪对所制得的产物氧化铝进行了表征和分析研究。     

Microemulsion extraction separation and determination of aluminium species by spectrofluorimetry

A simple and sensitive microemulsion extraction separation method was developed for the speciation of aluminium in tea samples by spectrofluorimetry. With 8-hydroxyquinoline (8-HQ) as the chelating agent and Triton X-100 Winsor II microemulsion as the extractant, separation of aluminium species in different pH solutions was achieved by microemulsion extraction. The formation of microemulsion, the conditions of extraction and determination of aluminium species were studied. The results showed that, the contents of aluminium species in tea leaves and infusions samples, such as total aluminium, total soluble aluminium, total granular aluminium, inorganic aluminium except Al-F, and (Al-F+Al-org), were obtained successfully under the optimal conditions. The limit of detection was 0.23 μg L(-1) in pH 9.5 solution, and 0.59 μg L(-1) in pH 6.0 solution respectively; the precision (RSD) for 11 replicate measurements of 10 μg L(-1) aluminium was 2.1% in pH 9.5 solution, and 2.8% in pH 6.0 solution respectively; the recoveries for the spiked samples were 96.8-103.5%. The proposed method is simple and efficient, which has been applied to the speciation of aluminium in tea samples with satisfactory results.     

锻造铝合金中相的形态分群识别

铝合金经压力加工后，其合金元素和杂质元素所形成的相被破碎而均呈细碎的颗粒并相互混杂在一起，造成识别上的困难。根据这些相形态方面存在的差别，提出形态分群识别法。即按相的形态特征，分为固态可溶于基体相和不溶于基体相两个组群，然后分别处理。使难度高又繁琐的相识别工作，变为准确可靠的简而易行。     

Analysis of hardenability effect of boron

Abstract

The effect of boron on the hardenability of steels depends on the contents of such elements as aluminium, titanium, nitrogen, and boron and on the austenitising temperature. An attempt has been made to calculate the solubility of boron in the presence of aluminium, titanium, and nitrogen in steels. Three systems, Ti–B–Al–N, Ti–B–N, and B–N, were derived according to the thermodynamic state of each steel and the soluble boron contents were calculated. It was found that the maximum boron factor was achieved at 0·0004–0·0005% soluble boron. The fact that aluminium content in the range 0·018–0·050 wt-% investigated in this study has little effect on the boron hardenability factor can be explained from the results of the thermodynamic calculation.

MST/1025     

Preparation of transparent,electrically conducting ZnO film from zinc acetate and alkoxide

Very uniform and transparent zinc oxide thin films doped with aluminium and indium were fabricated by the dip-coating technique using solutions prepared by the ethanolamine method. As starting materials, zinc acetate and zinc n-propoxide were used. Zinc acetate and propoxide are soluble in PrⁱOH in the presence of diethanolamine, although they are hardly soluble without the amine. The prepared solutions were very stable and suitable for dip-coating. Zinc oxide was crystallized by heating above 500 °C, and doping of aluminium and indium retarded the crystallization. The electrical resistivity of the film was decreased by doping with aluminium and indium. The lowest resistivity of 2 × 10^–2 cm was obtained by post-coating treatment in a nitrogen atmosphere.     

缓蚀型添加剂对阳极氧化后铝合金耐蚀性的影响

选择海洋用铝合金进行阳极氧化处理,运用电化学极化及交流阻抗技术,结合微观分析,比较阳极氧化后铝合金的耐蚀性。结果表明,所研究的铝合金中主要存在Al-Cu-Mn-Fe-Si-Cr和Al-Mg-Si第二相,Al-Cu-Mn-Fe-Si-Cr相不溶解,在氧化膜中呈突起状态;而Al-Mg-Si相溶解形成孔洞,易受到侵蚀,成为腐蚀源。对于特定的铝合金,阳极氧化电解液中添加Na2MoO4缓蚀剂后,MoO4^2-进入阳极氧化膜,抑制侵蚀性离子的有害作用,提高了铝合金的耐蚀性。     

The role of aluminium and silicon in the setting chemistry of glass ionomer cements

A model of the setting chemistry of glass-ionomer cements (GICs) is proposed based on ²⁷Al and ²⁹Si solid state nuclear magnetic resonance spectroscopy data on three GICs. All the precursor glasses are found to contain three aluminium species viz.: four, five and six-coordinate aluminium environments as well as four-bridging silicate tetrahedra. Upon cement formation, Al³⁺ ions in the glass are leached out from the surface layer of the glass. On entering the cement matrix, these ions adopt six-coordination and crosslink the polymer chains as part of the setting reaction. The remaining four-coordinate aluminium is distributed between two species: one in the inert core of the glass particles; and a second, less concentrated, in the surface layer of the glass particles, modified by the curing reactions. There is some evidence for residual five and six coordinate aluminium species in the final cement in some of the systems. In the case of the silicate tetrahedra, the curing reactions result in a decrease in the number of aluminium atoms in the second coordination sphere, with a subsequent recondensation of silicate network of the glass.     

An experimental study of hydrogen solubility in liquid aluminium

Hydrogen solubility in molten aluminium at different temperatures from 973–1123 K, has been measured using Sieverts' method. Inert gas (helium or argon) was used as a reference gas to calibrate the measurement system of the Sieverts' apparatus. The measured hydrogen solubility was found to vary with the reference gases. Helium was detected to be soluble in liquid aluminium. When helium is used as the reference gas, its solubility resulted in lower measured hydrogen solubility than that when argon was used to calibrate the measurement system of the apparatus. Argon gas was therefore considered as an appropriate reference gas when Sieverts' method is used to measure the hydrogen solubility in liquid aluminium. The hydrogen solubility, S, in liquid aluminium as a function of melt temperature, T, determined in the present investigation is expressed as log S = (−2980/T) + 3.07.     

On the growth sequence of highly ordered nanoporous anodic aluminium oxide

Anodic aluminium oxide films were fabricated by well known two-step anodizing process in oxalic acid electrolyte. The ordering characteristics (ordered pore domains, average pore diameter size and through-pore arrangement) of anodic aluminium oxide films, obtained in different growth sequences, were identified by microscopic analysis such as ex situ contact-mode atomic force microcopy and scanning electron microscopy. Flattened areas in which some pits are seen mostly cover the electropolished surface of aluminium. Single anodizing of aluminium produces a broad distribution of nanopore size, whereas induces a highly ordered hemispherical pattern, which plays the ordered nucleation sites for the second anodizing step. Moreover, a quasi-linear growth behavior exists for the ordered domain growth versus the duration of first step anodizing. The through-pore arrangement of ideally grown membranes is not influenced by increasing the duration of second step anodizing.     

Modelling of dealumination of aluminium silicate molecular sieves

Abstract

A simplified treatment of the dealumination of aluminium silicate (zeolite like) molecular sieves has been developed that considers both the diffusion of aluminium atoms and the formation and migration of vacancy sites. The instantaneous concentration of aluminium atoms as a function of time and location has been derived according to Fick's second law. Critical parameters affecting the dealumination process are discussed. The calculated results agree with the ratios of silicon to aluminium reported in the literature from infrared and ²⁷Al NMR spectroscopy studies on the commercial aluminium silicate molecular sieves materials Mordenite and ZSM-5, following exposure to air and water vapour.     

A comparison of two Nextel 440 Fibre reinforced aluminium composites using acoustic emission

The acoustic emission (AE) response and mechanical behaviour of two Nextel 440 fibre reinforced aluminium composites were compared. The total cumulative AE events were found to occur in two regions. The first region occurred at smaller strains and had a large exponential rise in events for the reinforced 6061 composite and few events for the high purity aluminium matrix composite. The difference was attributed to the alloy constituents of the 6061 aluminium matrix. The events were attributed to a dislocation release mechanism that occurred prior to yielding of the matrix. In the second region of events in the reinforced 6061 composite the event rate was constant and continued to failure. The second region of events in the high purity aluminium (HPAL) composite had a steady increase in the event rate until a constant rate was reached prior to failure. The events in the reinforced HPAL composite were attributed to the fracturing of fibres and the associated plastic deformation of the matrix that accompanies fibre failure. Thus failure in the materials occurs due to the propagation of fracturing fibres. The propagation was rapid in the reinforced 6061 aluminium composite. The reinforced HPAL composite had a slower propagation due to the high ductility of the HPAL.