超细粉煤灰对衬砌混凝土强度与变形性能的影响

为研究超细粉煤灰对衬砌混凝土材料的强度和变形性能的影响规律及微观改性机制,本文采用5种掺量超细粉煤灰制备胶结混凝土,进行抗压强度试验和电子显微镜扫描试验。结果表明:混凝土立方体的抗压强度随粉煤灰含量增加呈先增后减的趋势,15%超细粉煤灰掺量的混凝土强度性能最佳;掺入超细粉煤灰也可以提高试样抵抗变形的能力,压缩破坏时的最终应变εult在粉煤灰掺入后大幅下降;从电子显微镜扫描结果发现经过粉煤灰改性的试件内部结构有显著改变,粉煤灰细颗粒对混凝土内部孔隙具有填充效应;但超细粉煤灰过大时,水泥含量相对减少反而导致骨料之间的粘结减弱。     

分散剂对硅藻土基多孔陶瓷的影响

选用不同分散剂,研究了不同分散剂含量对硅藻土基多孔陶瓷的影响.试验结果表明,六偏磷酸钠对浆料 的稀释作用最好,加入量为2％时,浆料粘度是7.1 mPa·s;pH值2.6为硅藻土基多孔陶瓷浆料(不含分散剂)的等电点,由于浆料粒子相互吸引而聚集,所以浆料pH值离等电点越远,分散剂对浆料的稀释效果越好.     

蒸压粉煤灰砖墙片抗震性能研究

通过7片蒸压粉煤灰实心砖墙片、2片蒸压粉煤灰多孔砖墙片和2片烧结普通砖墙片的拟静力试验,对比分析了墙片的破坏特征,以及构造柱和竖向压应力对墙体的抗震性能的影响.结果表明,蒸压粉煤灰砖墙片与烧结普通砖墙片的抗剪承载力和其他抗震性能相似,蒸压粉煤灰多孔砖墙片可以参照烧结普通砖砌体墙进行抗震设计.     

硅藻土基多孔陶粒的制备及对Cu~(2+)吸附性能研究

以硅藻土为主要原料,添加适量的成孔剂和烧结助剂,采用湿式研磨、滚球成型和高温煅烧工艺,制备了新型环境材料——硅藻土基多孔陶粒。结合X射线衍射、扫描电镜、压汞仪等对材料结构与性能进行了表征。通过紫外分光光度计,考察了硅藻土基多孔陶粒对Cu2+的吸附性能。结果表明,硅藻土基多孔陶粒以石英晶相为主,孔径集中在500~3 000 nm,比表面积为6.14 m2/g,孔隙率为47.8%。硅藻土基多孔陶粒对Cu2+的去除率可以达到96.5%,吸附过程符合准二级动力学模型。     

钠过量0.94(K0.5Na0.5)NbO3-0.06LiNbO3 无铅压电陶瓷显微结构和电学性能的研究

采用固相合成法制备了0.94(K_(0.5)Na_(0.5+x))NbO_3-0.06LiNbO_3无铅压电陶瓷,并对钠过量对陶瓷的晶体结构、显微形貌、电学性能的影响进行了研究.XRD测试结果显示,所研究的所有陶瓷样品均为单一钙钛矿结构,而且在室温下均为正交相和四方相两相共存.当x=0.01时,陶瓷具有最优的压电性能,其压电常数d33、相对介电常数εr、平面机电耦合系数Kp和厚度机电耦合系数Kt分别为255pC/N,850,0.46和0.42.研究结果可以为KNN基压电陶瓷的结构和性能调控提供有益的参考.     

多孔混凝土抗冲刷性能影响因素试验

水利工程中,多孔混凝土的孔隙结构有利于土壤与水体的物质交换,是一种环境友好型混凝土。为了研究多孔混凝土抗冲刷性能的影响因素及破坏机理,采用正交试验法,利用自行设计的水循环装置,依据《水工(常规)模型试验规程》(SL155-2012)模拟自然的河道环境对多孔混凝土进行冲刷试验,探讨孔隙率、水灰比、掺合料对多孔混凝土抗冲刷性能的影响及多孔混凝土的冲刷破坏机理。试验结果表明:随着孔隙率的增大,多孔混凝土的抗冲刷性能呈现增强的趋势,孔隙率20%的多孔混凝土质量损失率2.91%,孔隙率25%的多孔混凝土质量损失率为1.6%,孔隙率30%的多孔混凝土质量损失率1.4%;水灰比增大多孔混凝土的质量损失率也随之增大,水灰比0.24的多孔混凝土质量损失率1.52%,水灰比0.26的多孔混凝土质量损失率2.39%,水灰比0.28的多孔混凝土质量损失率2.95%,胶结材料剥落现象频繁出现;掺合料对多孔混凝土抗冲刷性能的影响主要取决于其颗粒级配与活性大小,在粉煤灰、硅灰、矿渣这3种掺合料中,硅灰的活性最强且颗粒级配均匀,添加硅灰的多孔混凝土质量损失率为2.03%矿渣活性稍弱,添加矿渣的多孔混凝土质量损失率为2.5%,粉煤灰的活性最低,添加粉煤灰的多孔混凝土质量损失率为2.91%。水力冲刷破坏的主要原因是在水流的反复冲刷下,多孔混凝土内部的裂缝扩展导致界面过渡区破坏,混凝土开裂,骨料脱落,混凝土失去稳定状态。     

粉煤灰制备无机陶瓷材料的研究进展

该文首先简要介绍了粉煤灰和陶瓷材料的特点和性能,综述了以固体废弃物粉煤灰为主要原料制备出莫来石、堇青石、钙长石、硅灰石和硅基复合陶瓷材料的研究进展,并展望了粉煤灰制备陶瓷材料的应用前景。     

粉煤灰改性及其资源化应用进展

粉煤灰作为一种传统的固体废物,因产量大、利用率低而大量堆积,污染周边环境.由于粉煤灰具有独特的玻璃体结构、比表面积大、孔隙度发达、结构稳定等特点,在土壤修复以及废水治理等领域具有较好的应用潜力.因此,对粉煤灰进行资源化利用是解决其堆积与污染的有效途径之一.该文综述了当前改善粉煤灰性能的物理、化学和生物改性方法及其机制,讨论了其在建筑业、农业、环境修复领域的应用进展,并对粉煤灰长期应用风险及改性研究方向进行了展望,以期为改性粉煤灰的制备及其应用提供参考.     

以二甲基-正丁基-磺化木质素基氯化铵为模板剂制备多孔钛材料

以碱木质素为原料合成二甲基-正丁基-磺化木质素基氯化铵两性表面活性剂,并以其为模板剂采用溶胶-凝胶法制备多孔钛材料。结果表明:二甲基-正丁基-磺化木质素基氯化铵含氮量为1.360%,含硫量1.860%;红外光谱和1H NMR证实产物中存在磺化和季胺的化学结构。溴酚蓝和亚甲基蓝实验表明二甲基-正丁基-磺化木质素基氯化铵具有两性化合物结构,溶于碱性、中性和稀酸溶液。随着模板剂与钛酸正丁酯的质量比增加,多孔钛材料的比表面积加大;继续增加模板剂的量,多孔钛材料的比表面积下降。多孔钛材料孔径分布范围较宽,为晶态,主要以锐钛矿形式存在。煅烧后的多孔材钛料中有TiO2特征吸收峰,也有少量残留的木质素。当二甲基-正丁基-磺化木质素基氯化铵与钛酸正丁酯的质量比为0.65∶1、煅烧温度为450 ℃时,可得到最大比表面积、锐钛矿晶态的多孔钛材料。      

路用粉煤灰高性能混凝土的抗硫酸盐侵蚀性能

粉煤灰高性能混凝土是对传统混凝土技术的重大突破,是1种环保的新型"绿色混凝土",用于公路工程建设中会产生重要的技术经济意义和社会效益.粉煤灰在高性能混凝土中的作用机理不同于在普通混凝土中,在高性能混凝土中,粉煤灰可减小混凝土早期温升和自收缩,有利于混凝土形成完好的结构,减少微裂缝的发生,改善混凝土抗侵蚀能力. 通过试验,对路用粉煤灰高性能混凝土的耐硫酸盐侵蚀性能进行了分析和研究,为其在工程中的实际应用提供了理论依据.     

柚子皮制备多孔碳材料处理聚氯乙烯微塑料废水实验研究

柚子皮是福建漳州常见的农业废弃物,作为垃圾处理对环境造成一定压力,急需开展资源化利用。本论文以柚子皮为原料,碱活化和高温碳化制备多孔碳材料,并将其应用于聚氯乙烯微塑料的处理。实验结果表明,制备的多孔碳材料对聚氯乙烯微塑料具有较好的吸附处理效果。聚氯乙烯微塑料去除率随着吸附时间和多孔碳材料投加量的增加而逐渐增大。多孔柚子皮碳材料适宜在弱酸或弱碱性条件下处理聚氯乙烯微塑料废水。这为柚子皮资源化利用提供了新方向和技术。     

优质电极糊的研制

High quality electrode paste produced ty improving general production technique and special treating raw material was introduced. The new paste has higher strength, good anti-thermal shock property, good sintering property, lower uint consumption, and les     

多孔吸附光催化复合材料的制备及其处理含汞废水的研究

以凹凸棒土和活性污泥作为原材料,制备多孔载体。考查了活性污泥与凹凸棒土的不同比例、煅烧温度、保温时间和造孔剂量等因素,分析了样品的抗压强度、表观强度、真密度和孔隙率,确定了最佳制备条件为：凹凸棒土与活性污泥的混合比例为2∶3,添加5%的碳酸氢铵作为造孔剂,在1 100℃下保温1 h。最后,采用溶胶-凝胶法在多孔载体上负载二氧化钛,制备出多孔吸附光催化复合材料。     

Demineralization of porous solids

When a porous ionic solid is placed in acid, the acid will dissolve surface material. When this dissolved material and the acid diffuse into the solid's pores, they can precipitate more solid. If the acid is buffered, the diffusing species can bring about precipitation in some regions and dissolution in others. When the porous solid contains several chemical species, the diffusion can precipitate one species and dissolve another. The results have implications for the demineralization of teeth.     

Carbon compounds in interplanetary dust: evidence for formation by heterogeneous catalysis

Associations of carbonaceous material with iron-nickel alloy, carbides, and oxides were identified by analytical electron microscopy in ten unmelted chondritic porous micrometeorites from the earth's stratosphere. These associations, which may be interpreted in terms of reactions between a carbon-containing gas and catalytically active dust grains, suggest that some of the carbon in the chondritic porous subset of interplanetary dust was emplaced through heterogeneous catalysis.     

Compressibilities of lunar crystalline rock, microbreccia, and fines to 40 kilobars

The compressibilities of three lunar samples were studied at room temperature from 0 to 40 kilobars. The samples were a fine-grained vesicular crystalline rock (type A), a microbreccia (type C), and fines (type D). All samples were porous. The microbreccia and fines were quite compressible at all pressures; the compressibility of the crystalline rock was somewhat less, being 8.4 megabar(-1) at 1 atmosphere and 1.5 megabar(-1) at 35 kilobars. Some porosity appeared to remain in the samples at all pressures. Thus the pressure-volume data derived from these samples may be representative of porous surface and near-surface material in the vicinity of the Apollo 11 landing site but may not be representative of lunar material at depth.     

Chemical modification of the photoluminescence quenching of porous silicon

The photoluminescence of porous silicon can be quenched by adsorbates, and the degree of quenching can be tuned by chemical derivatization of the porous silicon surface. Thus, as-prepared porous silicon has a hydrophobic, hydrogen-terminated surface, and the photoluminescence is strongly quenched by ethanol and weakly quenched by water. Mild chemical oxidation (iodine followed by hydrolysis) produces a hydrophilic porous silicon surface. Photoluminescence from this hydrophilic material is quenched to a lesser extent by ethanol and to a greater extent by water, relative to the original surface. This demonstrates that the visible luminescence from porous silicon is highly surface-sensitive, and the surface interactions can be tuned by specific chemical transformations.     

Comparison of comet 81P/Wild 2 dust with interplanetary dust from comets

The Stardust mission returned the first sample of a known outer solar system body, comet 81P/Wild 2, to Earth. The sample was expected to resemble chondritic porous interplanetary dust particles because many, and possibly all, such particles are derived from comets. Here, we report that the most abundant and most recognizable silicate materials in chondritic porous interplanetary dust particles appear to be absent from the returned sample, indicating that indigenous outer nebula material is probably rare in 81P/Wild 2. Instead, the sample resembles chondritic meteorites from the asteroid belt, composed mostly of inner solar nebula materials. This surprising finding emphasizes the petrogenetic continuum between comets and asteroids and elevates the astrophysical importance of stratospheric chondritic porous interplanetary dust particles as a precious source of the most cosmically primitive astromaterials.