关键词： Recycled asphalt pavement   Slag-geopolymer   Microstructure   Pavement structure  

摘要： The integrated transdisciplinary concepts and technologies for greener and more sustainable innovations for recycling waste materials through geopolymer technique into construction materials were developed in this research. The objective of this research was to study the strength and microstructural development of slag (S)-based geopolymer-stabilized recycled asphalt pavement (RAP) as a pavement base material. An attempt was made to study the influence of a liquid alkaline activator (L=NaOH/Na2SiO3 ratio) on the strength development of RAP-S geopolymers, which was evaluated by an unconfined compressive strength (UCS) test and examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The XRD and SEM analyses results indicated that the main geopolymerization reaction product of RAP-S geopolymers was calcium alumino-silicate hydrate (C-A-S-H). Without Na2SiO3 (L=NaOH/Na2SiO3=100:0), the S-geopolymer exhibited a slow geopolymerization reaction. The silica presented in Na2SiO3 was highly soluble;hence, a suitable content of NaOH/Na2SiO3=60:40 can produce RAP+20%S geopolymers as a base material whose 7-day UCS value met the minimum strength requirements specified by the Department of Highways, Thailand. However, when excess Na2SiO3 content (NaOH/Na2SiO3=50:50) was used, the presence of silica retarded the geopolymerization formation rate, leading to UCS reduction. The outcomes of this research were found to be useful for making progress in innovative technologies and applications of geopolymers, which strongly reflected the improvements made in the practical applications of the S-geopolymer as a cleaner production by using the recycled waste material in road work. (C) 2018 American Society of Civil Engineers.

摘要： Rare-earth-transition-metal (RE-TM-based) permanent magnets (PM), which were discovered in the late 1960s, are the most powerful magnets used in industry. PMs have applications in a wide variety of fields, such as medicine, magnetic recording, hard disc drives, wind turbines, and electric motors to name a few. The most popular magnets with the highest maximum energy product of up to ( BH ) max ≈ 450 kJ/m 3 are the neodymium-Iron-Boron: Nd 2 Fe 14 B based magnets (2:14:1 crystal structure). The drawbacks of these PMs are their high cost, their poor corrosion resistance, and the low Curie temperature of T C ∼ 300 ◦ C. Although the Curie temperatures of Cobalt Samarium (Co-Sm) magnets are higher, they are used less frequently due to their cost. Examples for such compounds are SmCo 5, with a ( BH ) max of roughly 200 kJ/m 3 and a maximum operating temperature of up to 250 ◦ C, and Sm 2 Co 17, with a ( BH ) max ≈ 260 kJ/m 3 and a maximum operating temperature of up to 550 ◦ C. The demand for magnetic materials containing more abundant (such as Ce, La) or lower content of RE metals is a focus of research due to the increase in price of Nd and Dy in recent years. Besides the RE 2 Fe 14 B magnets, the compounds with the ThMn 12 crystal structure (1:12) and in particular SmFe 12−x TM x (TM = Ti, V, Mo, W,..) have been a focus of investigation since the 1980s. Since there has recently been a resurgence of interest in these compounds, they were also studied for this thesis. The high-throughput synthesis and analysis method offers an efficient experimental approach for discovering new hard magnetic compounds. The synthesis method used in this thesis was the reaction crucible (RC), which is based on heterogeneous nonequilibrium states. One diffusion couple can in most cases cover the whole Fe-rich area of the phase diagram. The high-throughput analysis method uses correlative microscopy to estimate saturation polarization J s using the domain contrast, the anisotropy constant K

关键词： TiO2团簇   TiO2纳米片   低温合成   影响因素   光催化活性  

摘要： 二维纳米结构二氧化钛由于表面活性位点剧增可带来光催化活性的显著提高.本文通过液相法在低温条件下合成大尺寸TiO_2纳米片,重点研究溶液中硝酸浓度、熟化温度和反应物浓度对其二维结构形成过程的影响.采用透射电子显微镜(TEM)表征样品的微观形态,并结合紫外-可见吸收光谱、X射线衍射谱(XRD)、X射线光电子能谱(XPS)和傅立叶变换红外光谱分析样品的微结构性质.采用光催化还原Cr(VI)作为指示反应,评估各制备参数对二氧化钛光催化性能的影响.结果表明,硝酸浓度为0.0217~0.0721 mol·L^(-1)的样品在0~4℃条件下胶溶及熟化时可得到具有显著量子尺寸效应的超薄锐钛矿型TiO_2纳米片;硝酸浓度过高引起样品晶型和形态的转变,过低导致胶溶时间延长;熟化温度超过4℃会破坏二维结构的形成;提高反应物中乙醇的用量有助于分散水解产物,促进胶溶和二维结构的形成进程.

关键词： 纳米MnO2   介孔   电化学性能   α-MnO2   δ-MnO2  

摘要： 将KMnO4负载在介孔二氧化硅KIT-6模板上,在不同温度(400~700℃)煅烧制备纳米MnO_2,研究了不同煅烧温度下纳米MnO_2的显微结构和电化学性能。结果表明:当煅烧温度为400℃时,制备得到的纳米MnO_2只由具有层状结构的δ-MnO_2组成,当煅烧温度升高至500℃时,纳米MnO_2由具有层状结构的δ-MnO_2和少量具有隧道结构的α-MnO_2组成,当煅烧温度为600,700℃时,纳米MnO_2均由具有隧道结构的α-MnO_2组成,且α-MnO_2分别呈有序介孔形貌和棒状形貌;具有隧道结构的α-MnO_2的循环稳定性优于具有层状结构δ-MnO_2的,在100mA·g-1电流密度下经50次循环充放电后仍具有100mAh·g^(-1)以上的放电容量。

关键词： Ultrasonic noise backscattering   Polycrystalline materials   Grain size effects   Reciprocity theorem   Elastic wave propagation   Finite element modeling  

摘要： The correlation between ultrasonic wave propagation and polycrystalline microstructures has significant implications in nondestructive evaluation. An original numerical approach using the finite element method to quantify in both time and frequency domains the ultrasonic noise scattering due to the elastic heterogeneity of polycrystalline microstructures is presented. Based on the reciprocity theorem, it allows the scattering evaluation using mechanical data recorded only on the boundary of polycrystal instead of within its volume and is applicable to any polycrystalline aggregate regardless of its crystallographic or morphological characteristics. Consequently it gives a more realistic and accurate access of polycrystalline microstructures than the classical analytical models developed under the assumption of single scattering and the Born approximation. The numerical approach is proposed within the same unified theoretical framework as the classical analytical models, so it is possible to validate it in the cases of idealized microstructures for which the considered analytical models remain relevant. As an original result, assuming single phase, untextured and equiaxed microstructures, two-dimensional (2D) theoretical formulas are developed and a frequency-dependent coefficient is found compared to the classical three-dimensional (3D) formulas. 2D numerical simulations are then performed for idealized microstructures composed of hexagonal grains with a uniform grain-size. Three grain sizes are considered herein and involve different scattering regions. Good comparisons are obtained between theoretical and numerical estimates of the backscattering coefficient, which validate the numerical approach. Effects of the grain boundary orientations are analyzed by modeling an irregular hexagonal grain morphology and a random grain morphology generated by an established Voronoi approach. The origin of the significant oscillation level of backscattering is then investigated

关键词： Cluster dynamics   Radiation damage  

摘要： As both the design of material systems for nuclear energy applications and the number of reactor designs being proposed increase the need for material models predicting the evolution of microstructures as a function of chemistry, texture, grain size, precipitate content, etc., and irradiation conditions is steadily increasing. This manuscript aims at presenting a review of the different cluster dynamics modeling schemes that have emerged worldwide over the past decade(s). Further, the manuscript also critically discusses limitations in existing approaches and identifies potential routes for future developments. (C) 2018 Elsevier B.V. All rights reserved.

关键词： 生物质   甘蔗渣   表面改性   偶联剂   显微结构   聚合物基复合材料  

摘要： 采用碱处理、硅烷偶联剂处理以及碱处理配合硅烷偶联剂处理等方式改性甘蔗渣(BF),采用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、热重分析(TGA)以及力学性能测试等研究改性后BF结构的变化。结果表明,不同改性方法均明显改变了BF的结构及改性剂的键合方式。碱处理能够去除BF中的半纤维素等小分子聚合物以及部分非晶区的纤维素,导致BF热稳定性降低,结晶度上升。碱液浓度偏高以及碱处理时间过长会导致BF的纤维表面原纤化,虽然能增加与偶联剂反应的面积,但BF的强度大大下降,不利于BF的增强作用。因此,硅烷偶联剂处理的BF/PLA复合材料的相容性及力学性能最佳,其次为碱处理配合硅烷偶联剂处理的BF/PLA复合材料,最后为碱处理的BF/PLA复合材料。

关键词： Transparent heat regulating coating   Low-emission   Thermo-chromic   Energy saving windows   Dielectric/metal/dielectric   Industrial coatings   Transparent solar cells  

摘要： This review highlights the development of energy saving transparent heat regulating (THR) materials and coating for energy saving window applications. Current state-of-the-art technologies including transparent heat reflecting mirror (THM), thermo-chromic (TC), transparent solar cells (TSC), and luminescent based materials have been discussed. The coating performance primarily depends on the selection of materials, surface and structural morphology, dielectric passivation growth process and architecture of the multi layered structure. The micro-structural properties of thin metal/metal oxide layer, and its impact on the heat reflecting coating have been studied extensively. Growth of high quality continuous thin film with fewer defects is an essential part of the infrared reflecting and/or heat regulating coatings. Henceforth, in this review, detailed analysis of growth of continuous and thin metal layer influence of the seed layer (germanium and nickel) and doping on the growth mechanism of thin metal have been discussed. Surface morphology and electronic properties of metal layer/multi-layered coatings have been studied in detail for THR applications. A wide range of metal oxides and their physical properties have been considered for use as passivation layer in the THR coating structure. Among several THR structures, the architecture comprising of dielectric-metal-dielectric (DMD) stack is known to exhibit the best heat reflecting performances. While the metal component typically comprises of silver (Ag), copper (Cu), and nitride based materials, dielectrics are made from metal oxides such as BaSnO3, TiO2, SnO2, ZnO, HfO2, Cu2O, and ZrO2. Selection of passivation layer and tuning of micro-structural properties are very crucial to enhance the visible transmittance without sacrificing infrared reflectance. Optical properties of the dielectric layer can be controlled with growth mechanism and varying content of impurity dopant. Metal doped dielectrics play a key role

关键词： energy absorption   model materials   strain rate   key factors   energy absorbing property   Dual phase steels   ferrite grain   Vehicle body   Steels   data processing   Volume fraction   microtectonics  

摘要： The increase in use of dual-phase (DP) steel grades by vehicle manufacturers to enhance crash resistance and reduce body car weight requires the development of a clear understanding of the effect of various microstructural parameters on the energy absorption in these materials. Accordingly, DP steelmakers are interested in predicting the effect of various microscopic factors as well as optimizing microstructural properties for application in crash-relevant components of vehicle bodies. This study presents a microstructure-based approach using a multiscale material and structure model. In this approach, Digimat and LS-DYNA software were coupled and employed to provide a full micro-macro multiscale material model, which is then used to simulate tensile tests. Microstructures with varied ferrite grain sizes, martensite volume fractions, and carbon content in DP steels were studied. The impact of these microstructural features at different strain rates on energy absorption characteristics of DP steels is investigated numerically using an elasto-viscoplastic constitutive model. The model is implemented in a multiscale finite-element framework. A comprehensive statistical parametric study using response surface methodology is performed to determine the optimum microstructural features for a required tensile toughness at different strain rates. The simulation results are validated using experimental data found in the literature. The developed methodology proved to be effective for investigating the influence and interaction of key microscopic properties on the energy absorption characteristics of DP steels. Furthermore, it is shown that this method can be used to identify optimum microstructural conditions at different strain-rate conditions. (C) The Minerals, Metals & Materials Society and ASM International 2018

摘要： The main goal of this research was the synthesis of new siliceous materials with controlled microstructures, using low-temperature polycondensation process, and develop the new approach towards 3D microfabrication under two-photon excitation of a sol-gel formulation. Synthesis of microstructured materials is based on the sol-gel process, i.e. hydrolytic polycondensation. Most known siliceous materials with controlled microstructure are synthesized from tetraethoxysilane (TEOS). The materials are generally structured by structuring molecular agents ("templates") such as surfactant compounds, which are then removed by heat treatment or washing with appropriate solvents. This stage of removal of structuring agents is often problematic, particularly at the industrial level, because it uses either high temperatures or large amounts of solvents. Therefore, new methods to obtain materials with controlled porosity without the need to use templates are still being developed. Two strategies are discussed during this research work. First one involved the use of organosilicon precursors with a define structure that at molecular level modify the structure of the final materials. The use of well-defined precursors (silsesquioxanes), in appropriate proportions, allows the control of the porosity of the obtained silica materials. The second approach investigated in this work is the local photo-induced structuration of silicon based pre-hydrolyzed precursors under two-photon excitation allowing high 3D resolution