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71.
为了研究氯氧镁水泥的长期耐久性机理,用XRD分析了我国实际使用12~16a的氯氧镁水泥材料的物相组成,探讨了氯氧镁水泥在自然环境下的长期水化产物与转变规律。结果表明,氯氧镁水泥的长期水化产物,在室内大气环境下主要是氯氧化镁5Mg(OH)2.MgCl2.8H2O(5.1.8)和氢氧化镁Mg(OH)2,在室外露天环境下主要是Mg(OH)2、5.1.8、碳化氯氧化镁[Mg(OH)2.MgCl2.2MgCO3.6H2O(1.1.2.6)]和水菱镁矿[4MgCO3.Mg(OH)2.4H2O(4.1.4)]。在露天的使用环境中,没有经过改性、或者改性效果不佳的氯氧镁水泥材料中的主要水化产物5.1.8,同时发生了分解-碳化作用和碳化-分解作用,其初级分解产物是Mg(OH)2,初级碳化产物是1.1.2.6,终极碳化产物是4.1.4和MgCO3。氯氧镁水泥材料结构中大量形成4.1.4,是导致其耐久性失效的根本原因。 相似文献
72.
对水菱镁石(3MgCO3.Mg(OH)2.3H2O)和斜方云石(3MgCO3.CaCO3)的开发与应用做了评述。内容包括简史、物化性能和开采加工,以及在氧化镁、重质碱式碳酸镁和镁质阻燃剂制取方面的应用,并展望了开发前景。 相似文献
73.
Nicolas Trcera Delphine Cabaret Stéphanie Rossano François Farges Anne-Marie Flank Pierre Lagarde 《Physics and Chemistry of Minerals》2009,36(5):241-257
X-ray absorption spectroscopy at the Mg K-edge is used to obtain information on magnesium environment in minerals, silicate and alumino-silicate glasses. First-principles
XANES calculations are performed for minerals using a plane-wave density functional formalism with core-hole effects treated
in a supercell approach. The good agreement obtained between experimental and theoretical spectra provides useful information
to interpret the spectral features. With the help of calculation, the position of the first peak of XANES spectra is related
to both coordination and polyhedron distortion changes. In alumino-silicate glasses, magnesium is found to be mainly 5-fold
coordinated to oxygen whatever the aluminum saturation index value. In silicate glasses, magnesium coordination increases
from 4 in Cs-, Rb- and K-bearing glasses to 5 in Na- and Li-bearing glasses but remains equal as the polymerization degree
of the glass varies. The variation of the C feature (position and intensity) is strongly related to the alkali type providing
information on the medium range order.
相似文献
Stéphanie RossanoEmail: |
74.
A method for determining calcium(Ca),potassium(K),magnesium(Mg) and iron(Fe) in four fish species was optimized and validated.It included microwave mineralization of the samples and subsequent quantification by flame atomic absorption spectroscopy(FAAS) with Zeeman-effect background correction.Using HNO3(65%) and H2O2(33%) as extraction solutions,the optimal conditions of extraction were established as follows:0.5 g of sample mass;microwave time program of 300 W/5 min and 600 W/5 min.The method was free of matrix interferences.The linear correlation coefficients were ≥0.9991,the recovery percentage of analytes was from 99.31% to 103.70% and the RSD(relative standard deviation) was lower than 2.06%.The detection limits obtained were 32.3,43.2,14.0 and 68.6 ng mL-1 for Ca,K,Mg and Fe in FAAS respectively.It is shown that the method is rapid,simple,sensitive and accurate.The method was applied to the studies of digestibility and measurement of these nutrients in samples of fish collected from Norway,Japan and China. 相似文献
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High-pressure single crystal X-ray diffraction experiments of phase anhydrous B and superhydrous B have been carried out to 7.3 and 7.7?GPa, respectively, at room temperature. Fitting a third-order Birch-Murnaghan equation of state to the P-V data yields values of V 0?=?838.86?±?0.04?Å3, KT,0?=?151.5?±?0.9?GPa and K′?=?5.5?±?0.3 for Anhy-B and V 0?=?624.71?± 0.03?Å3, KT,0?=?142.6?±?0.8?GPa and K′?=?5.8?±?0.2 for Shy-B. A similar analysis of the axial compressibilities in Anhy-B reveals that the c-axis is most compressible (Kc?=?137?±?3?GPa), the b-axis is least compressible (Kb?=?175?±?4?GPa), and the a-axis is intermediate (Ka?=?148?±?1?GPa). In Shy-B, the a-axis is most compressible (Ka?=?135?±?1?GPa), followed by the b- and c-axes which have similar compressibilities (Kb?=?146?±?3?GPa; Kc?=?148?±?3?GPa). The fact that the b-axis of Shy-B is approximately 16% more compressible than Anhy-B is primarily due to differences in the O-T layer in which the H atoms are located and the linkages with the adjacent O layers. The rigid edge-sharing chains of MgO6 and SiO6 octahedra in the O layer control compressibility along the a- and c-axes in both structures. The net result is a reduction in the overall anisotropic compression from ~22% in Anhy-B to ~9% in Shy-B. 相似文献
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榴辉岩中单斜辉石和石榴子石之间显著的镁同位素平衡分馏,使其成为一种具有潜力的高精度地质温度计。为此本文选取文献中已报道的来自西南天山洋壳冷俯冲造山带、大别-苏鲁陆壳碰撞造山带和南非卡普瓦尔克拉通三种构造环境中的64对单斜辉石—石榴子石矿物对镁同位素数据利用δ~(26)Mg_(Cpx)-δ~(26)Mg_(Grt)图解筛选出50对达到镁同位素平衡分馏的数据,采用Huang et al.(2013)通过第一性原理计算和Wang et al.(2012)、Li et al.(2016)分别通过经验估计得出的镁同位素温度计计算榴辉岩的峰期温度并与前人研究结果进行对比。通过分析计算结果发现对于造山带榴辉岩,Huang et al.(2013)的温度计计算结果与前人通过传统温度计和相平衡模拟研究结果较一致,较好地重现了榴辉岩的峰期温度,而Wang et al.(2012)和Li et al.(2016)的温度计计算结果明显低于前人获得的峰期温度;对于克拉通榴辉岩,三种镁同位素温度计的计算结果与前人通过传统温度计获得的研究结果大多数相差在50℃以上,很可能是早期退变质过程中镁同位素在高温条件下再平衡导致的这表明三种镁同位素温度计均不适用于克拉通榴辉岩。同时,基于这些榴辉岩样品数据,本文利用经验估计的方法进行校准,得到了新的单斜辉石-石榴子石镁同位素公式△~(26)Mg_(Cpx-Grt)=1.11×10~6/[T(K)]~2(R~2=0.92)。此外,本文也对单斜辉石-石榴子石镁同位素地质温度计的应用前景及应用时应当注意的问题进行了简单的探讨。 相似文献