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水化硅酸钙纳米结构研究进展 总被引:6,自引:0,他引:6
介绍了水化硅酸钙凝胶(C-S-H)的几种主要结构模型,重点阐述了纳米尺度的凝胶模型及其发展。在纳米凝胶模型中C-S-H是由最小结构单元近似为直径小于5nm的胶束堆积而成。根据胶束堆积密度的差异,C-S-H分为高密度和低密度2种不同的凝胶相。总结了现代微观测试手段对C-S-H纳米模型的验证结果,分析了当前研究存在的问题并对今后研究提出了建议。 相似文献
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水化硅酸钙(C-S-H)凝胶是影响水泥基胶凝材料宏观力学性能与长期耐久性的核心组分,阐明结构和性能间的关联关系有利于实现C-S-H凝胶的合成及推广应用。本文首先对C-S-H凝胶不同阶段的典型结构进行了综述,并引出结构与性能间的内在联系;随后,介绍水热合成法对不同结构C-S-H凝胶的精确调控,并详细阐述了合成要素对其组成、形貌以及结构的影响规律;最后,综述了合成C-S-H凝胶在相关应用领域的基础研究。本文聚焦于C-S-H凝胶构效关系的梳理总结以及C-S-H凝胶工程应用的前景探索,可为充分完善水泥水化机理、开发高性能绿色化建材提供理论参考。 相似文献
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C-S-H 凝胶及其研究方法 总被引:5,自引:3,他引:2
在分析C-S-H凝胶的复杂性和特征的基础上,就测定它的化学组成、C-S-H凝胶中[SiO4]4-四面体的聚合度及其结构的化学和物理的方法作了简要介绍.现代各种测试方法的出现和使用,对C-S-H凝胶的组成和集中[SiO4]4-四面体的聚合结构有了较为完整的概念. 相似文献
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水化硅酸钙(C-S-H)作为水泥基胶凝材料的基因,其结构变化对混凝土宏观性能发展至关重要。为了明确纤维素纳米晶(CNCs)在水泥中的改性机理,采用共沉淀法制备C-S-H凝胶,探讨了CNCs的形态效应及成核效应对C-S-H凝胶结构的影响。基于X射线衍射、透射电子显微镜、纳米压痕以及核磁共振等测试,结果显示CNCs表面携带的羟基(—OH)可络合Ca2+,随后与溶液中的SiO42–反应形成C-S-H凝胶,包裹在CNCs周围形成致密的网络结构。CNCs为C-S-H凝胶的沉淀和生长提供了额外的成核位点,促进了C-S-H凝胶聚合度的降低以及链长的缩短,并且显著提升了高密度C-S-H凝胶的含量。 相似文献
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以分析纯Ca(NO3)2·4H2O、Na2SiO3·9H2O、Pb(NO3)2为原料,通过溶液反应法,制备纯净的C-S-H凝胶和掺杂Pb的C-S-H凝胶,研究了C-S-H凝胶在形成过程中对Pb的吸附固化作用及掺杂Pb后C-S-H凝胶的结构变化.结果表明,可溶铅盐由2%增至6%时,C-S-H凝胶对Pb均有良好的吸附固化作用,俘获Pb总量增大.XRD图谱发现掺杂Pb的C-S-H凝胶,其主峰位置发生偏移,出现明显的Ca(OH)2衍射峰.红外测试表明含Pb C-S-H凝胶硅氧四面体的链接方式发生变化,Q2伸缩振动峰向低波数方向偏移,Q1伸缩振动峰吸收强度增加. 相似文献
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以分析纯Ca(NO3)2·4H2O、Na2SiO3·9H2O和重金属硝酸盐为原料,通过溶液反应法分别制备钙硅比为0.8和1.8的纯净及含Cd2+、Zn2+和Cu2+的C-S-H凝胶,研究了C-S-H凝胶在形成过程中对三种重金属离子的吸附固化作用.结果表明,两种钙硅比的C-S-H凝胶均能吸附固化Cd2+、Zn2+和Cu2+,重金属离子较易进入低钙硅比C-S-H凝胶夹层结构中,可以置换高钙硅比C-S-H凝胶结构中的Ca2+,在水化液相中形成Ca(OH)2.C-S-H凝胶对Cd2+和Cu2+的固化能力好于对Zn2+的,低钙硅比C-S-H凝胶对Zn2+的吸附固化作用优于高钙硅比C-S-H凝胶. 相似文献
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水化硅酸钙(C-S-H)凝胶是硅酸盐水泥的主要水化产物,是水泥胶凝能力的主要来源。C-S-H凝胶的纳米结构由长程无序、短程有序的类Tobermorite纳米晶组成。明确类Tobermorite相纳米晶的分子结构、氢键等分子间作用力组成及性质、H2O和羟基基团与硅氧主链的相互作用机理对理解C-S-H凝胶的胶凝能力形成机理、调控水化产物的胶凝能力具有重要意义。本文在总结固体核磁共振分析技术研究C-S-H凝胶硅氧主链结构研究进展的基础上,提出其钙硅比对硅氧主链聚合度和平均链长的影响规律,并运用固体核磁测试与第一性原理计算核磁结果相结合的研究方法,揭示了C-S-H凝胶分子结构中氢键的组成及性质,明确了水分子及羟基基团与硅氧主链的相互作用机理。 相似文献
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Simple estimates of the coefficient of dynamic viscosity of some metals are considered. Experimental results on shock loading of aluminum, copper, and steel plane specimens are given. It is shown that the coefficient of dynamic viscosity depends on the characteristic size of the structural level of plastic strain at which loading-energy dissipation is considered. It was found that the main level that determines the viscosity of materials under high-velocity loading is the mesoscopic level with a characteristic size of 10 m. Key words: viscosity, high-velocity loading, mesoscopic level, interferogram. 相似文献
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The structure of metadickite, which was a dehydration phase of a dickite from Shokozan mine, Hiroshima, Japan calcined at 600°C for 24 h, was investigated by X-ray radial distribution function (RDF) analysis and the correlation method. The RDF curve showed the coordination numbers of both Si and Al atoms to be four and the structural regularity was observed up to ∼0.8 nm. Several structural models for metadickite were examined by the correlation method and the most likely model is considered to be the arrangement built up of SiO4 tet-rahedral sheets, similar to the original dickite, and an adjacent edge-shared AlO4 tetrahedral chain, with a 6-4-4 type oxygen atom distribution. 相似文献
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Fine structural aspects of cellophane have been investigated using X-ray and electron diffraction techniques as well as a kinetic study of the dissolution of cellophane in 0.5 M cupriethylene diamine solution. The X-ray diffraction pattern for cellophane shows a typical cellulose II structure while the electron diffraction pattern highlights a typical cellulose I structure with very weak reflection for a cellulose II type lattice. The kinetics study of cellophane dissolution in cupriethylene diamine confirms the presence of these polymorphic forms of cellulose in cellophane. The paper also reports studies of the X-ray and electron diffraction patterns of cellophane in relation to crystallite size and degradation under electron beam. It is shown that the observed anomaly between the X-ray and electron diffraction patterns of cellophane is a consequence of (i) the larger minimum crystallite size requirement for producing diffraction patterns with X-rays than with the electron beam (ii) the much faster degradation of cellulose II crystallites than that of cellulose I crystallites under the electron beam and (iii) the reduction in the crystallite size of cellulose II in cellophane from that in wood pulp alkali cellulose during the process of regeneration. 相似文献
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煤制酚醛树脂的结构特征 总被引:1,自引:0,他引:1
采用红外光谱、核磁共振、热重分析、分子量测定等现代分析方法,对煤制酚醛树脂进行了全面分析,初步 煤制酚醛树脂的结构特征,认为煤制酚醛树脂与线性酚醛树脂(基本芳环骨架上有-OH、-CH2等基因在1,2,4位取代的酚醛树脂)有极为相似的红外谱图,具有相似的分子结构。煤制酚醛树脂性能好、成本低(硝化煤可部分代替昂贵的苯酚),是十分具有工业化前景的方法。 相似文献
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A carbon nanospring is formed by coiling a single-walled carbon nanotube (n, m) surrounding a cylinder surface with a uniform pitch length and spring rising angle. Both armchair and zigzag carbon nanosprings are studied. Due to the limitations of hexagonal carbon-atom rings and the bond length of carbon–carbon atoms, a maximum rising angle exists for each type of nanospring (n, m), and zigzag nanosprings have greater maximum rising angles than armchair nanosprings with the same spring radius. In this study, a molecular mechanics (MMs) calculation is performed to investigate the structural properties of carbon nanosprings. Flat carbon nanosprings are obtained with small spring radii and rising angles, and round carbon nanosprings are found to have a larger spring radius than flat ones. The results show that the structural stability of a nanospring mainly depends on the parameters of its tube radius, spring radius, and rising angle, whereas its chiral type has little effect. 相似文献