The Microstructure and Performance of a Cement Matrix Composite Material

Through the DSC , XRD , SEM and other experimental methods , the microstructure characteristics of reactive powder concrete( RPC ) are discussed, The results show that RPC has a super high perfomance because of its lower ratio of water-binder, high pock density , optimum hydration products mixture and being strengthened by steel fiber. The high performance results from the special hydration microstructure of RPC, and its superperformance can be well explained by the centrum partile hypothesis.     

超高性能轻质混凝土的力学性能及微观结构

超高性能轻质混凝土(ultra-high performance lightweight concrete,UHPLC)是一种由高强水泥浆体、漂珠和纤维组成的密度低于1 950 kg/m~3的新型水泥基结构材料。本文研究了不同养护制度及养护龄期对UHPLC抗压强度、轴拉力学性能和弯曲性能的影响,最后利用扫描电镜观察了UHPLC中漂珠的微观形貌。结果表明:随着龄期增长,UHPLC的抗压强度、轴拉性能和弯曲性能均提高,并出现明显的应变强化现象,说明养护龄期对UHPLC基体强度和纤维-UHPLC基体的界面黏结强度均有显著提高作用;高温蒸汽养护3 d可促进UHPLC基体早期强度发展,使UHPLC的抗压强度和弯曲性能迅速达到标准养护28 d时的水平,显著缩短养护龄期,但对纤维-基体界面黏结强度的贡献不大,黏结强度仍主要受龄期影响;UHPLC实测密度为1 815.2 kg/m~3,100 mm立方体抗压强度达103.1 MPa,极限抗拉强度达7.60 MPa,极限拉应变达0.431%,出现明显的应变强化现象,弯曲峰值强度达22.43 MPa,满足了RPC160的抗折强度要求,实现了水泥基结构材料轻质高强的目标。     

C—Si—Mn系热轧双相钢显微组织与力学性能之间的关系

通过对热轧试样的组织性能测试,研究了热轧双相钢显微组织与力学性能之间的关系。研究发现,铁素体和马氏体强度是影响力学性能的主要因素。建立了C-Si—Mn系热轧双相钢力学性能的数学模型,可以作为热轧双相钢基本力学性能参数预测的理论依据。     

Synthesis of γ-alkoxy-propylamines and their collecting properties on aluminosilicate minerals

γ-alkoxy-propylamines, C12 H25 O(CH2 )3 NH2, C14 H29 O(CH2)3 NH2, C16 H33 O(CH2)3 NH2, C18 H37 O-(CH2)3NH2 were synthesized from aliphatic alcohol and acrylonitrile. The flotation tests of kaolinite, pyrophyllite and illite were conducted. The flotation mechanisms were explained in view of the structures of reagents and alumin ium silicate minerals, zeta potential and Fourier transform infrared spectrum measurements. The results show that the synthesized r-alkoxy-propylamines are more effective than dodecyl amine for flotation of kaolinite, pyrophyllite and illite. For flotation kaolinite and illite, the collecting ability is in the order of C18 H37 O(CH2)3 NH2 ＞C16 H33O(CH2)3 NH2 ＞C14 H29O(CH2 )3 NH2 ＞C12 H25O(CH2)3 NH2, but the r-alkoxy-propylamines types of collectors have almost the same collecting ability on pyrophyllite,which demonstrating that γ-alkoxy-propylamines are new selective collectors for reverse floatation to remove aluminium silicate minerals from bauxite.     

Occurrence mechanism of silicate and aluminosilicate minerals in Sarcheshmeh copper flotation concentrate

The Sarcheshmeh copper flotation circuit is producing 5×104 t copper concentrate per month with an averaging grade of 28% Cu in rougher,cleaner and recleaner stages.In recent years,with the increase in the open pit depth,the content of aluminosilicate minerals increased in plant feed and subsequently in flotation concentrate.It can motivate some problems,such as unwanted consumption of reagents,decreasing of the copper concentrate grade,increasing of Al2O3 and SiO2 in the copper concentrate,and needing a hi...     

超高性能水泥基材料的力学行为及机理分析

研究安防系统对超高性能水泥基复合材料工作性及超高力学性能的特殊要求,以大掺量超细工业废渣取代水泥,掺加超高硬度细集料,采用高温干热养护制度,成功制备出一种超高性能水泥基复合材料.对其工作性及不同养护温度和养护时间下的力学性能进行测试,结果表明,制备的材料具有较好的工作特性及超高力学性能,可满足安保产品要求,其抗压强度最高可达240 MPa.采用X射线衍射技术、差热-热重分析方法及扫描电镜对其微观结构形成进行分析,结果显示,超高硬度细集料与胶凝材料的强物理结合使其在复合材料中起增强相的作用,高温养护加速了水泥的水化及矿物惨合料的火山灰反应,降低了材料中Ca(OH)2的含量,增加了C-S-H凝胶的含量,提高了材料的密实度,改善了界面微观结构,提高了超高性能水泥基复合材料的宏观力学性能.     

活性矿物掺合料对超高性能水泥基材料的影响

通过复掺粉煤灰和硅灰,制备一种抗压强度超过200 MPa的超高性能水泥基复合材料(UHPCC),采用扫描电镜、微区能谱分析、X射线衍射、汞压入法和差示扫描量热分析等现代测试手段,研究了活性矿物掺合料对UHPCC微观结构及性能的影响.实验结果表明,UHPCC水泥石主要以低mCa/mSi、结构致密的C-S-H凝胶和许多未水化颗粒组成;活性矿物掺合料的火山灰效应使水泥浆体与集料间界面过渡区得以改善;矿物掺合料的微集料效应使体系颗粒级配优化,致使基体内部结构致密,总孔隙率减小,孔尺寸得到细化,孔结构得以优化,材料性能得以提高.     

Effect of cooling modes on microstructure and electrochemical performance of LiFePO4

LiFePO4 was prepared by heating the pre-decomposed precursor mixtures sealed in vacuum quartz-tube. Three kinds of cooling modes including nature cooling, air quenching, and water quenching were applied to comparing the effects of cooling modes on the microstructure and electrochemical characteristics of the material. The results indicate that the water quenching mode can control overgrowth of the grain size of final product and improve its electrochemical performance compared with nature cooling mode and air quenching mode. The sample synthesized by using water quenching mode is of the highest reversible discharge specific capacity and the best cyclic electrochemical performance, demonstrating the first discharge capacity of 138.1 mA·h/g at 0.1C rate and the total loss of capacity of 3.11% after 20 cycles.     

优质翡翠与显微构造的成因关系

在多年研究岩石显微结构和构造的基础上,总结了所带4届博士和硕士研究生的研究数据,认识到翡翠的质量与动力变质作用有密切的关系。脆性变形的碎裂结构使翡翠质量变次,而韧性变形的糜棱结构使质量变好。在较低温度、较强剪切应力和高为速率下的韧性变形,通过位错滑动、亚晶粒化和动态重结晶使硬玉晶粒变细、镶嵌紧密,即各种空隙被很好地填补,透明度增大,质地变得更细腻。在强大剪切应力和钠质流体的共同作用下,铬铁矿的淡化作用是形成绿色的主要原因。剪切应力还控制翡翠绿色色相和绿色空间的分布。绿色一般分布在韧性变形区的中心部位,高应力区有利于铬的富集。     

磁天平在材料组织分析中的应用

介绍了一种根据合金的磁性能半定量、定量地分析合金组织状态的原理和方法.实践证明,这一方法理论正确,设备简单,操作简便,结果可靠,成本低而效率高,能够满足材料组织分析的一般要求     

光学模型研究质子入射镍的反应截面

加速器驱动核能系统设计离不开微观反应数据的支撑,为了这个目的以及研究中高能质子入射镍反应性质的需要,利用光学模型理论表征质子入射镍核反应,用数值方法计算出反应截面和弹性散射角分布,从而得到质子入射镍各同位素,能量到200MeV的光学模型势参数,进而给出相应核反应的反应截面和弹性散射角分布。该组光学模型势参数比G-B光学模型势在高能量处对反应截面的预言更准确,而且这些反应截面微观数据可用于加速器驱动核能系统设计。     

Simulation and control scheme of microstructure in magnetic fluids

By accounting for the external and internal force acting on the suspended magnetic nanoparticles and motion characteristics of the suspended magnetic nanoparticles in the magnetic fluids,the three-dimensional microstructure of magnetic fluids is investigated by means of the molecular dynamics simulation method. The distribu-tion of suspended magnetic nanoparticles and microstructure of the magnetic fluid are simulated in both absence and presence of an external magnetic field. The ef-fects of the nanoparticles volume fraction,the dipole-dipole interaction potential and the particle-field interaction potential on the microstructures of the magnetic fluids are discussed. The main results obtained here are summarized as follows. The suspended magnetic nanoparticles tend to aggregate and make the irregular distribution structure in the absence of an external magnetic field. When the mag-netic fluid is exposed to a magnetic field,the magnetic nanoparticles suspended in the carrier fluid tend to remain chained-alignment in the direction of the external magnetic field. The tendency of chain-alignment morphology of the suspended magnetic nanoparticles is enhanced with the nanoparticles volume fraction,the dipole-dipole interaction potential and the particle-field interaction potential.     

核磁共振和电测深联合解释找水

对VES(Vertical Electrical Soundings)和NMR(Nuclear Magnetic Resonance)两方法找水原理进行介绍,并进一步论述这两方法在联合解释找水中各自方法的任务、实现的目标及具体步骤,利用核磁共振确定含水层、含水层数、含水层厚度、含水层深;利用主剖面和两横剖面调查低电阻率带、结合核磁共振资料确定井位.通过工程实例,说明正确认识影响NMR和VES信号解释的主要因素,是提高联合找水方法资料解释水平的关键.     

高性能混凝土微观结构特征及开发应用

从材料的微观结构层次上设计和制备新材料是２１世纪材料科学技术一个重要课题．分析了高性能混凝土研究现状及实施的要点,探索高性能混凝土微观结构及特征,并开拓配制高性能混凝土的新途径、新技术     

具有二环〔3,3,1〕骨架的桥环化合物的合成

利用分子内的烯烃加成反应合成出具有二环〔３,３,１〕骨架的桥环化合物３～９,并且对其反应机理进行了讨论．所合成的化合物经核磁共振光谱、红外光谱及元素分析证实了其结构．     

Effect of rejuvenators on performance and microstructure of aged asphalt

A composite rejuvenator was used for the rejuvenation of aged asphalt in comparison with the common rejuvenator. The effects of the rejuvenators on the performance and microstructure of the aged asphalt were investigated by physical properties tests, dynamic shear rheometer and atomic force microscopy. The results indicate that the physical and rheological properties of the aged asphalt are restored more significantly by the composite rejuvenator than the common rejuvenator, which can be ascribed to the effective recovery of microstmcture of the aged asphalt. The composite rejuvenator has the potential to be used for the rejuvenation of severely aged asphalt since it can restore the colloidal structure of the aged asphalt effectively through composition regulation and chemical reactions between the composite rejuvenator and asphaltenes.     

Glass forming ability, microstructure and magnetic property of NdAlNiCuFe alloys

The glass forming ability (GFA), microstructure and magnetic property in (Nd60Al10Ni10)Cu20-xFex (0≤ x≤ 20) alloys were investigated by using X-ray diffraction (XRD), differential scanning calorimetry (DSC), high resolution transmission electron mi- croscopy (HRTEM) and magnetic property measurement. It is shown that the GFA of the alloys decreases with Fe content. The sam- ples for bulk cylinders with x≤10 show a distinct endothermic peak in the DSC traces due to a glass transition in the range of 421-438 K. With further increasing Fe, the glass transition is masked by the crystallization. The microstructure of the Nd-based alloy can change progressively from full glassy state into composite state with nanocrystalline particles in the glassy matrix indicating the glass forming ability degrades with increasing Fe. The average size of nanocrystals increases with Fe and the distribution changes from homogenous to heterogeneous. The magnetic property varies from paramagnetic to hard magnetic when the Fe content increases up to about 4at% indicating that the magnetic property is related to the metastable phases.     

基于NMR和SEM的软土微观结构特征试验研究

软土的含水特性和微观结构是决定其物理力学性质的主要因素. 以南沙软土为研究对象,运用核磁共振和扫描电子显微镜两种微观结构试验方法,获取了软土的弛豫时间T₂谱图和扫描电子显微镜图像,总结了两种软土（淤泥和淤泥质土）的水相分布和孔径分布规律. 研究表明,南沙软土的T₂分布曲线呈双峰型,土中存在两种状态的水分,第一种状态水超过质量的99%,孔隙多、孔径小,孔径分布主要集中在0.1~20 μm的区间. 南沙软土常见的微观结构类型为絮状结构、蜂窝结构和凝块结构3类. 计算了平均孔隙半径、平均孔隙面积、面孔隙率、孔隙形状因子和孔隙分维数等微观结构参数. 最后,对比分析了两种测试方法和应用中需注意的几个问题.     

Coordination properties and structural units distribution of Q_T~i in calcium aluminosilicate melts from MD simulation

1　INTRODUCTIONCalciumaluminosilicatemelts ,whicharethemostimportantternarysystemformetallurgistandmineralogist ,havedisplayedcomplicatedmicrostruc tureandproperties.Intheliquidofbinarysystem ,suchasCaO SiO2 ,cationsare partitionedintotwotypes :networkformerSiandmodifierCa .Forcalci umaluminosilicateternarymelt ,Caisstillnetworkmodifier,andSinetworkformer ,butAlisam phiprotic,whichisdeterminedbythepairinterac tionswithoxygen[1] andlocalenvironment .There fore ,thecoordinationnumbersof…     

Coordination properties and structural units distribution of QiT in calcium aluminosilicate melts from MD simulation

The distribution of Al(j) and the structural units distribution of QiT in calcium aluminosilicate melts were studied by means of molecular dynamics simulation. The results show that provided there exists lower-field strength cation relative to Al3 , such as alkaline and alkaline earth metals, Al will be four-coordinated but not six-coordinated. Meanwhile, if there exist a large number of higher-field strength cations such as Si4 and little lower-field strength cation, six-coordinated aluminum will be formed. The relation of structural units distribution of QiT with chemical composition shift was also extracted, showing that as Ca2 exists, the distributions of QiSi, QiAl or QiT have the similar changing trend with the variation of component. Because of high-temperature effect, the Al-tetrahedral units in melts are greatly active and unstable and there exist dynamic transforming equilibria of Al(3)→←Al(4) and Al(5)→←Al(4). The three-coordinated oxygen and charge-compensated bridging oxygen are proposed to explain phe-nomena of the negative charge redundancy of AlO4 and location of network modifier with charge-compensated func-tion in aluminosilicate melts.