含碎砖再生混凝土的抗压强度研究

通过对18组再生混凝土试件的轴压试验,研究碎砖杂质对再生混凝土抗压强度性能的影响。结果显示:水灰比从0.36增大到0.53,含碎砖杂质再生混凝土的抗压强度呈逐渐下降,并且下降幅度较大;碎砖含量不超过10%时,再生混凝土强度受到的影响不大;含有碎砖块的再生混凝土7d抗压强度能够达到28d的54%~68%。     

浓缩湿法磷酸中的杂质对其流变性能的影响

浓缩湿法磷酸中存在大量的杂质离子,它们对浓缩磷酸的黏度和密度有着交互影响。通过模拟浓缩磷酸的组成,采用三因素二次回归正交设计的方法来考察Fe,Mg,Al等杂质离子对磷酸黏度的影响。结果表明:当杂质相对质量分数小于3.1%时Al对浓缩磷酸黏度影响最大,当杂质相对质量分数大于3.1%时,Mg对浓缩磷酸黏度影响最大;并得出杂质质量分数与磷酸黏度关系的数学模型,模型检验所得误差为7.37%,对实现浓缩湿法磷酸的管道输送提供一定参考价值。     

应用890铝衬套胶辊替代中铁辊的实践

通过生产实际应用 890铝衬套胶管套制胶辊轴承替代 6 82 5铁辊 ,减少了中铁辊表面粘附的杂质 ,并分析了 890铝衬套胶辊的使用优势和应注意的问题     

Purging Metal Impurities from Nuclear Fuel using Centrifuge Cascades with Additional Feed Component

Abstract

Nuclear fuel can be purged, that is metal impurities can be extracted from the uranium hexafluoride, by feeding an additional component, a kind of Freon, C₆F₁₂, which is chemically stable with respect to uranium hexafluoride, into the centrifuge purge cascade. The metal impurities are then continuously withdrawn from the purge cascade as a result of the additional feed. Centrifuges can not be easily used for the purge process without the Freon because the amount of metal impurities in the nuclear fuel is usually very small, thus the flow of impurities withdrawn from the product end of the purge cascade needs to be periodically closed down to minimize the loss of uranium hexafluoride. This results in the accumulation of light impurities such as air and HF in stages near the product end of the purge cascade. These light impurities inside the centrifuges may reduce the working effectiveness of the centrifuges or even put them out of service. The additional Freon eliminates this problem, because the light gas can be extracted from the cascade as soon as it reaches the product end of the cascade. Numerical calculations using a typical metal impurity CrO₂F₂ illustrate the effect of the additional Freon feed in the purge process.     

On the Limited Selectivity of Silica-Based Epoxidation Catalysts

Epoxidation of 2-cyclohexen-1-ol with TBHP and TiO₂–SiO₂, Fe₂O₃–SiO₂ and SiO₂ aerogels has been studied. The influence of surface silanol groups and transition metal impurities in titania–silica on the product distribution has been analyzed. The results, supported by literature data, indicate that high surface area silica cannot generally be regarded as an inert matrix in epoxidation catalysts. Contribution of Ti-free silica limits the selectivity of Ti- and Si-containing catalysts in demanding epoxidation reactions. The activity of silica – together with the background oxidation of the olefin – may lead to overestimated intrinsic activities when the reaction rate is related to the Ti content of the catalyst.     

关于200 MW机组汽轮机油颗粒污染度标准的探讨

阐述了准确检测机械杂质的重要性和现行检测方法的局限性，并通过试验和现场考察，证明实行新方法的可行性并对如何实行新方法提出了建议。     

半导体晶圆的污染杂质及清洗技术

介绍了半导体圆片存在的各种污染杂质的类型和去除方法,并概要总结了半导体圆片的清洗技术,对半导体圆片的湿法和干法清洗特点和去除效果进行了比较分析。     

90%乙草胺乳油中杂质的气相色谱分析

本文描述了毛细管柱气相色谱法对90%乙草胺乳油中的主要杂质的定量分析。在没有标样的情况下，采用有效碳数理论计算出杂质组分的相对响应因子。方法的变异系数为3.7%-8.3%，标准值和实测值的误差为0.01%。     

〈211〉方向InSb单晶横截面的均匀性研究

借助于低温下标准样品的霍耳测量分析方法,测定了[111]晶向同[211]晶向(111)面上的杂质浓度分布,为制得径向上杂质浓度分布较均匀的材料指出了一条有效途径。     

Activation Response of Martensitic Steels

A hypothetical martensitic steel has been compositionally designed in order to optimize both metallurgical and reduced activation properties. When compared with two other martensitic steels, its activation characteristics are shown to be superior for all activation indices examined. However, these excellent properties are found to be due to the assumed absence of deleterious tramp impurities. When limiting impurity concentrations are determined for the hypothetical steel, they are found to be extremely stringent, and wholly unachievable using industrial scale production methods. It is concluded that only slight improvements can be made to currently available low activation martensitic steels to reduce residual activity responses further.