粉煤灰的激发形式及其对混凝土性能的影响

采用硫酸盐单掺、硫酸盐和熟石灰复掺,磨细、非磨细等低等级粉煤灰的活性激发手段,取水胶比为0.25和0.30,分别对不同掺量粉煤灰的混凝土进行对比试验,研究激发方式、粉煤灰掺量与高性能混凝土强度的关系。研究表明:硫酸盐和熟石灰与粉煤灰共同磨细的激发方式,对粉煤灰火山灰活性激发效果最明显,能配制得到粉煤灰掺量达50%～70%,强度为80MPa的高强混凝土;不磨细处理时,单掺和复掺激发剂对混凝土强度影响效果相差不大。     

石膏在粉煤灰-石灰-硫酸盐系统中的作用

粉煤灰-石灰-硫酸盐(FLS)系统是一类粉煤灰活性激发体系,其性能与硫酸盐密切相关.目前该系统中硫酸盐一般选用硫酸钠和石膏.本文就选用石膏作为硫酸盐激发剂的情况,结合已有的研究成果和理论基础,初步分析了FLS系统中石膏对系统性能的影响作用.     

粉煤灰活性复合激发剂的配制及应用研究

粉煤灰混凝土早期强度低，采用碱激发剂熟石灰和硫酸盐激发剂硫酸钠相复合的化学激发方法，配制粉煤灰活性复合激发剂，使粉煤灰混凝土早期强度发展加快，能满足对早期的设计强度要求。     

化学激发粉煤灰-水泥体系的膨胀和抗侵蚀性研究

采用化学途径激发粉煤灰-水泥体系中粉煤灰的活性,在此基础上研究了化学激发粉煤灰-水泥体系的自膨胀性能和抗硫酸盐侵蚀性能,并对试验结果进行了分析和比较,得出一些结论供参考。     

硫酸盐类及氯盐类激发剂对粉煤灰活性的影响

实验表明硫酸盐类及氯盐类激发剂对粉煤灰早期活性的激发有一定的作用,并且能够较好地激发粉煤灰在水化后期的活性。几种盐类激发剂中NaSO4的活性激发作用最明显,复合盐类激发剂的激发效果好于单一无机盐激发剂的效果。NaSO4和CaCl2复合在几种盐类复合激发剂中激发效果最好。     

粉煤灰对脱硫石膏-矿渣-粉煤灰复合胶凝材料力学性能的影响

通过研究粉煤灰自身在硫酸盐和石灰双重激发下产生的活性、粉煤灰的碱性以及颗粒Zeta（电位）等,分析不同粉煤灰对脱硫石膏-矿渣-粉煤灰复合胶凝材料力学性能的影响。结果表明,粉煤灰的种类对复合胶凝材料的力学性能影响很大,粉煤灰本身活性的差异不是造成这种影响的主要原因,其主要原因是粉煤灰对矿渣粉的激发程度。粉煤灰的碱性对矿渣粉的激发影响很大,对于普通含钙粉煤灰,碱性越强,激发越好,复合胶凝材料力学性能越好。矿渣粉颗粒的Zeta电位为负,因此粉煤灰颗粒表面的正电荷密度过高,不利于矿渣粉活性的激发。     

蒸养条件下粉煤灰活性激发试验研究

研究了蒸养条件下机械粉磨和不同化学激发剂对粉煤灰活性的激发效果并得出其最佳掺量值。试验结果表明：蒸养条件下,粉煤灰的机械活化激发效果最好;碱性激发剂Ca（OH）2和CaO最佳掺量为2%,Na2SiO3.9H2O和NaOH为6%;硫酸盐激发剂CaSO.2HO合理掺量为4%左右;氯盐激发剂NaCl对粉煤灰活性激发效果不明显。     

粉煤灰在复合胶凝材料水化过程中的作用机理

分析了粉煤灰在复合胶凝材料水化硬化过程中的作用。探讨了化学激发、物理激发和热激发对于粉煤灰的活性的促进作用以及确定粉煤灰反应程度的方法。粉煤灰的火山灰活性可以用碱性物质或硫酸盐来激发,但是,这种化学激发措施不适合在商品混凝土生产过程中使用。物理激发和热激发是两种简单实用的提高粉煤灰使用效能的技术路线。热激发特别适用于大体积混凝土结构。在复合胶凝材料中,粉煤灰的反应程度很低,不会大量消耗Ca(OH)_2,在水化硬化初期,矿物掺和料主要以物理填充作用参与复合胶凝材料的水化硬化过程;随龄期延长,粉煤灰的火山灰活性作用逐渐明显。     

砌筑水泥生产中大掺量粉煤灰试验

笔者1999年4月在宝坻水泥厂利用秦皇岛热电厂的粉煤灰,采用复合外加剂生产高掺量粉煤灰砌筑水泥试验。下面就此试验原理和技术措施阐述如下。1 简介 粉煤灰中的石英含量可波动在3％～20％;莫来石5％～30％;Fe2O3＋Fe3O4 1％～4％,玻璃体50％～80％。由于其所潜在活性的铝硅酸盐玻璃微球很高,且粉煤灰的活性主要来自低铁玻璃体,玻璃体含量高,则活性高。笔者利用高掺量粉煤灰潜在的高水化活性来生产砌筑水泥。根据粉煤灰的结构和水化特点,采用复合碱激发,硫酸盐激发和复合早强减水剂等多种化学、物理方法,充分激发粉煤灰的潜在活…     

不同激发剂对粉煤灰火山灰活性的影响

探讨不同激发剂对粉煤灰不同时期火山灰活性的影响。结果表明：单掺适量的不同激发剂可以不同程度地提高粉煤灰早期、中期与后期的火山灰活性，其中早期的激发作用最大，后期的激发作用最小。且不同时期激发作用效果从大到小的顺序依次为氯化物、硫酸盐、氢氧化物，其中当氯化钠掺量为2％时激发作用效果最大。当水灰比为0．48时激发剂对粉煤灰不同时期火山灰活性的激发效果均优于水灰比为0．46时的激发效果。且当水灰比从0．46增至0．48时,各水泥试样的3d抗压强度比值增幅最大，28d抗压强度比值增幅最小。     

Electrocatalysts on supports—III. Electrocatalytic and adsorption properties of microdeposits and thin films of platinum group metals

The adsorption and electrocatalytic properties of the microdeposits of rhodium on gold, palladium on niobium, ruthenium and osmium on titanium, and palladium thin films on glass carbon and nickel have been investigated. It is shown that hydrogen adsorption on rhodium and ruthenium microdeposits is characterized by a low binding energy and that on palladium films by a high binding energy. The cathodic hydrogen evolution rate on ruthenium microdeposits and palladium films on glass carbon and nickel is lower than that on the corresponding bulk metals. These results are consistent with the assumption of the predominant effect of the electronic interaction between microdeposits and thin films on the one hand and the supports on the other, which affects the hydrogen adsorption energy parameters.     

An interpretation on the origin of the specular reflectance change caused by the submonolayer formation of foreign metals on some precious metal electrodes

The optical properties of foreign metal submonolayers formed on Au, Ag, Cu, Pt and Pd electrodes through the underpotential deposition have been investigated by specular reflectivity measurement. Based on the spectral characteristics, 14 adsorbate-substrate systems were classified into 2 groups. The first group, involving Bi on Au, Cu on Au, Pb on Au, Tl on Au, Tl on Ag and Cd on Cu, is characterized by the similarity of the optical properties of the adsorbed metal in the submonolayer to those of bulk metal. The first monolayer was found to form through several submonolayer stages, in which the optical constants are slightly different from each other. In the second group, involving Cd on Au, In on Au, Sn on Au, Ag on Pt, Bi on Pt, Cu on Pt, Pb on Pt and Bi on Pd, the spectra of submonolayer observed experimentally differ from those calculated with the assumption that the optical properties of adatom and substrate are the same as those of corresponding bulk metal. The difference in the work functions between adsorbate and substrate materials in this group is larger than those in the first group.From these findings, some considerations were made to interpret the origin of the specular reflectance change due to the presence of metal adlayer on the electrode surface. The results allow a tentative conclusion that the reflectivity change is predominantly attributed to the optical properties of the adsorbed submonolayer, but at the same time the work function of the substrate and the interband transition in visible should also be taken into consideration.     

水合氧化铝阻燃EPDM/PP的性能研究

用氧指数测定和力学性能测定方法研究了水合氧化铝 ( ATH)的用量及粒径对共混物性能的影响。结果表明 ATH对 EPDM/ PP有一定的阻燃作用和消烟作用 ,但使其拉伸强度和断裂伸长率降低。随其用量增加和粒径变小 ,阻燃效果提高 ;粒径对阻燃性能的影响随用量增大影响也增大。少量使用 ATH时 ,粒径对拉伸强度影响不大 ,但对断裂伸长率影响明显 ;随用量增大 ,粒径对拉伸强度和断裂伸长率的影响也增大。     

颜料色浆的选择对外墙涂料耐候性的影响

探讨色浆的选择对外墙涂料色漆耐候性的影响因素。重点讨论色浆类型的选择对性能的影响,同一种颜色用不同的复合色浆对耐候性的影响,色浆与调色基础漆配方设计对耐候性的影响以及墙面基材对保色性的影响。     

Deactivation of the metal and acidic functions for Pt, Pt-Sn and Pt-Sn-K using physically mixed catalysts

The effect of K addition on the amount and dispersion of carbon deposition on metal sites and support sites was investigated on a physical mixture for hexane dehydrogenation. TPO, BET and ESR experiments were used for characterization. The K addition significantly decreases catalyst deactivation involving the amount of coke deposits and the density of carbon radicals on the metal and support sites because of ensemble and electronic effects, especially on the metal sites. Coke on the metal sites associated with carbonaceous species rich in hydrogen is less polymerized than coke on the support sites, corresponding to a more graphitic-like carbon.     

三聚磷酸二氢铝对氨气的吸附动力学研究

在真空干燥器中,加入一定量待测气体的水溶液,保持真空干燥器中待测气体浓度恒定。利用此装置研究了氨气浓度、三聚磷酸二氢铝吸附大气和水蒸气后,对三聚磷酸二氢铝吸附氨气动力学的影响。结果表明,三聚磷酸二氢铝吸附氨气,可用一级动力学方程和Elovich动力学方程模型描述;氨水浓度对吸附量和平衡吸附时间有显著影响;三聚磷酸二氢铝吸附空气后,对吸附量和平衡吸附时间无影响;三聚磷酸二氢铝吸附水蒸气后,对吸附量和平衡吸附时间均有影响。     

Ammoximation of ketones on titanium silicalite. A study of the reaction byproducts

In the new EniChem process cyclohexanone oxime is directly synthesized by ammoximation of cyclohexanone with ammonia and hydrogen peroxide on titanium silicalite catalyst. The ammoximation reaction is suitable for the synthesis of several oximes by reaction of the corresponding ketones with ammonia and hydrogen peroxide on titanium silicalite. New results on ketones ammoximation and on reaction byproducts are reported. The effect of some reaction parameters on the oxime yield and on byproducts formation is discussed.     

热镀锌板的镀层成分对其表面电泳漆膜抗石击腐蚀性能的影响

研究了热镀锌板的镀层成分对其表面电泳漆膜抗石击腐蚀性能的影响。结果表明,经过合金化退火得到的GA板镀层中含有一定量的Fe,镀层较未经合金化退火的GI板硬。GA板镀层表面疏松多孔,电泳漆膜能够充满其缝隙或凹陷之处,固化后在界面区产生了类似勾键作用的机械作用力。因此,GA板与电泳漆膜的附着力优于GI板,石击处的扩蚀速率小于GI板。     

High performance liquid chromatography of oxygenated cholesterols and related compounds

Twenty-four oxygenated cholesterols and structurally related compounds were analyzed by high performance liquid chromatography with silicic acid column and various mobile phases. Hexane–propanol was superior to hexane/tetrahydrofuran and hexane/ethyl acetate for the separation of oxygenated cholesterols. The retention volumes of oxygenated cholesterols depended on the characteristics of the substituting group, its position of substitution, as well as its orientation. The effect of various functional groups at different positions on cholesterol molecules, in general order of decreasing retention volumes, were: hydroxy on the ring, carbonyl on the ring, epoxy on the ring, hydroxy on the side chain, and carbonyl on the side chain. Synergistic effect of multiple hydroxyl substitutions on cholesterol was observed.     

Electrocatalysts on supports—I. Electrochemical and adsorptive properties of platinum microdeposits on inert supports

Adsorptive and electrocatalytic properties of platinum microdeposits on high-melting metals (Ti, Ta, Zr and Nb) and gold have been studied. It has been found that hydrogen adsorption on such microdeposits is characterized by some lower mean bond energy. Hydrogen spillover has been observed on the samples of high-melting metals, however, its intensity is less than for samples of carbon materials with platinum microdeposits. The rate of cathodic hydrogen evolution on the microdeposits is higher than on massive platinum and increases as the particle sizes of microdeposits decrease. The properties of microdeposits in terms of hydrogen adsorption and evolution have been the same for samples of all examined metals both in the initial state and after being oxidized in air at temperatures of 550–650 K. Oxygen adsorption on the microdeposits has been characterized by a slightly elevated bond energy and has exceeded that on massive platinum. The rate of oxygen ionization on the microdeposits has been much less than on massive platinum due to almost complete conversion of the microdeposits into PtO. The rate of formic acid oxidation on platinum microdeposits only slightly depends on the potential and is governed by the rate of chemisorption. The exchange current of the redox reaction Fe³⁺ + e ? Fe²⁺ on platinum microdeposits on gold exceeds that on pure platinum and increases as the mean particle size of the microdeposits decreases. The features of the microdeposits found are explained by the assumption of their electronic interaction with support.