Performance characteristics of concrete based on a ternary calcium sulfoaluminate–anhydrite–fly ash cement

This paper reports an assessment of the performance of concrete based on a calcium sulfoaluminate–anhydrite–fly ash cement combination. Concretes were prepared at three different w/c ratios and the properties were compared to those of Portland cement and blast-furnace cement concretes. The assessment involved determination of mechanical and durability properties. The results suggest that an advantageous synergistic effect between and ettringite and fly ash (Ioannou et al., 2014) was reflected in the concrete’s low water absorption rates, high sulfate resistance, and low chloride diffusion coefficients. However, carbonation depths, considering the dense ettringite-rich microstructure developed, were higher than those observed in Portland cement concretes at a given w/c ratio. It was concluded that the amount of alkali hydroxides present in the pore solution is as important factor as the w/c ratio when performance of this type of concrete is addressed.     

含锌离子的聚硅硫酸铝的合成及性能研究

采用一步法制备聚硅硫酸铝絮凝剂合成了含锌离子的聚硅硫酸铝并研究了其性能.含锌离子絮凝剂是一种无毒高效的絮凝剂,且絮凝效果优良,锌离子含量对絮凝剂性能影响很大.     

草酸钙在硫酸软骨素自组装膜上周期沉淀的研究

利用硫酸软骨素(chondroitin sulfate，CS)在云母基底上通过浇铸法制备的自组装膜为基底，诱导草酸钙在其上的凝集生长。发现当硫酸软骨素的浓度为1．Omg／ml时在该膜体系中可形成规整的周期性草酸钙环状沉淀。这种有序的环状结构可能是耗散结构的一种具体表现形式。利用原子力显微镜(atomic forcemicroscope，AFM)和傅立叶红外光谱仪对这种结构进行了表征，实验结果显示合适浓度下形成的CS膜在一定程度上可以抑制草酸钙的凝集结晶，表明高分子基质与无机离子间强烈的相互作用对无机盐的成核结晶有显著影响，为探讨结石的形成与抑制提供了一定的实验依据。     

石膏转化制硫酸钾结晶动力学及结晶添加剂研究

研究了浓氨介质中石膏与氯化钾直接转化制硫酸钾的结晶动力学及结晶添加剂的作用效果。结果表明 ,硫酸钾在氨介质中的成核速率与晶体生长速率、悬浮密度、搅拌速率存在如下关联式 :B0 =5 .64 13×10 8G3.32 0 8Mt0 .0 559np0 .2 92 8。加入异丙醇、OP乳化剂及十二烷基苯磺酸钠等添加剂 ,可使硫酸钾结晶产品纯度提高 ,晶体形态整齐均匀     

镍层耐硝酸腐蚀性测试——一种简单的预先探测ENIG镍层“黑盘”现象的测试方法

随着更加精细的SMT、BGA等表面贴装技术的运用,化学沉镍金(ENIG)作为线路板最终表面处理得到了越来越广泛的应用,同时可怕的“黑盘”现象也随之更广泛地“流行”起来,直接导致贴装后元器件焊接点不规则接触不良。为了贯彻执行最好的流程控制和采取有效的预防措施,了解这种焊接失败的产生机理是非常重要的,及早的观测到可能发生“黑盘”现象的迹象变得同样关键。本文介绍了一种简单的预先探测ENIG镍层“黑盘”现象的测试方法-镍层耐硝酸腐蚀性测试,这种测试可以用于作为一种常规的测试方法监测一般化学沉镍溶液在有效使用寿命范围内新鲜沉积的镍层的质量。利用Weibull概率统计分析在不同的金属置换周期(MTO)下镍层的可靠性能表现。结合试验结果得出了一个镍层耐硝酸腐蚀性的判定标准。     

十二酰胺丙基二甲基羟乙基氯化铵与十二烷基硫酸钠水溶液的表面吸附和胶束形成

利用十二酰胺丙基二甲胺和氯乙醇反应 ,合成了十二酰胺丙基二甲基羟乙基氯化铵 (DDHA)阳离子表面活性剂 ,将其与十二烷基硫酸钠 (SDS)以不同摩尔比进行混合 ,测定了混合系统的表面张力 ,计算了单一系统和混合系统的饱和吸附量、分子最小截面积 ,表面层和胶束中 DDHA的摩尔分率及分子间相互作用参数 ,目视观察了混合系统的浑浊情况。结果表明 :在降低γcmc和 cmc方面 ,DDHA SDS混合系统有协同效应 ,表面层和胶束的组成与二组分配比有关 ,但是非对称的 ,等物质的量混合物中 ,DDHA在胶束和表面层中具有较大的摩尔分数。DDHA与 SDS在实验测定的各混合系统中都不出现混浊     

用硫酸铁铵容量法测定钛精矿中二氧化钛含量

样品在过氧化钠熔融、水浸取及盐酸酸化后，在盐酸和硫酸介质中，隔绝空气，用金属铝将钛(Ⅳ)还原至钛(Ⅲ)，以硫氰酸盐为指示剂，用硫酸铁铵标准溶液滴定。     

Continuous precipitation of calcium sulfate dihydrate from waste sulfuric acid and lime

Precipitation of calcium sulfate dihydrate, gypsum, from (i) a pure sulfuric acid/lime suspension and (ii) a waste sulfuric acid/lime suspension in a continuous pilot plant in the temperature range from 40 °C to 80 °C was studied. It was observed that in the case of waste sulfuric acid with a high content of Mg²⁺ and Fe²⁺ ions, several hours after the beginning of the precipitation, partial dissolution of the product and modification of the crystals from needle‐ and plate‐like to agglomerated structures occurred. It is suggested that the secondary changes occur due to the increased concentration of Mg²⁺ and Fe²⁺ ions in the reactor. Below 60 °C, and above 70 °C plate‐like and needle‐like single crystals respectively were formed. The mean size (d₅₀) of the crystals was found to increase with increasing temperature and decrease with the initial concentration of lime. Gypsum produced between 70 °C and 80 °C is suitable for further processing for construction plaster. In a precipitation process with pure sulfuric acid only single perfect needle‐like crystals occurred. Copyright © 2005 Society of Chemical Industry     

熔融碳酸盐燃料电池阴极材料的导电性

通过交流阻抗方法研究了熔融碳酸盐燃料电池阴极材料锂镍氧化物、锂钴氧化物和锂铁氧化物的导电性能。结果表明:锂镍氧化物电极的导电性最好,锂钴氧化物电极的导电性次之,锂铁氧化物电极的导电性最差;它们的导电性都随着温度的升高而按指数规律增加;在合成锂钴氧化物(或锂铁氧化物)的过程中,使Li2CO3轻微过量,可以提高锂钴氧化物(或锂铁氧化物)电极的导电性,而且在同一温度下,随着nLi∶nCo(或nLi∶nFe,摩尔比)值的增大,锂钴氧化物(或锂铁氧化物)电极的导电性显著增加。     

新型香料苹果酯-B的合成

以硫酸高铈为催化剂,通过乙酰乙酸乙酯和1,2-丙二醇反应合成了苹果酯-B,研究了各有关因素对产品收率的影响。实验表明,硫酸高铈是合成苹果酯-B的良好催化剂,在酯醇物质的量比为1∶1.25、催化剂用量为0.3g/0.1mol乙酰乙酸乙酯、环己烷10mL、反应时间2h的条件下,苹果酯-B的收率可达91.5%。