华科材料学英文文献摘要翻译
材料科学英语作文
The Evolving World of Materials ScienceIn the realm of scientific exploration, materials science stands as a dynamic and ever-expanding discipline, encompassing the study, design, and application of various materials. This diverse field, which intersects withmultiple branches of science and engineering, has revolutionized numerous industries, from aerospace to healthcare, and continues to pave the way for technological advancements.The fundamental premise of materials science lies in understanding the properties and behaviors of matter at the atomic and molecular levels. Scientists in this field explore the relationships between the internal structure of materials, their processing methods, and their ultimate performance. This understanding allows for the developmentof new materials with tailored properties, optimized for specific applications.One of the most significant advancements in materials science is the emergence of nanocomposites. These materials, composed of nanoscale components, offer exceptional mechanical, thermal, and electrical properties that farsurpass traditional materials. For instance, nanocomposite polymers exhibit enhanced strength and durability, making them ideal for use in high-performance applications such as automotive parts and aerospace components.Another noteworthy area of research is the developmentof smart materials. These innovative materials possess the ability to respond to external stimuli, such as temperature, pressure, or electromagnetic fields, by changing their physical or chemical properties. Smart materials have the potential to revolutionize fields like medicine, where they can be used to create implantable devices that can monitor and respond to physiological changes in the body.The applications of materials science are vast and diverse. In the field of renewable energy, materials scientists are developing efficient solar cells andbatteries that utilize novel materials to enhance energy storage and conversion. In the healthcare sector, they are exploring the use of biocompatible materials forimplantable medical devices and regenerative medicine. Additionally, materials science plays a crucial role in the development of sustainable technologies, such aslightweight materials for vehicles and eco-friendly construction materials.The future of materials science looks promising, with numerous opportunities for further research and innovation. With the continued advancements in nanotechnology, computational modeling, and additive manufacturing, it is likely that we will see the emergence of even more remarkable materials in the coming years. These materials will not only enhance the performance of existing technologies but also enable the development of entirely new applications that we cannot even imagine today.In conclusion, materials science represents a vibrant and exciting field that is constantly pushing the boundaries of scientific knowledge. Its impact on society is immeasurable, and its future prospects are limitless. As we continue to explore and understand the fundamental properties of matter, we are poised to unlock new possibilities and create a better world through the power of materials.**材料科学的演进世界**在科学探索的领域中，材料科学作为一个动态且不断扩展的学科，涵盖了各种材料的研究、设计与应用。
化学专业外文文献原稿和译文
外文文献原稿和译文原稿Facile synthesis of hierarchical core–shell Fe3O4@MgAl–LDH@Au as magnetically recyclable catalysts for catalytic oxidation of alcoholsA novel core–shell structural Fe3O4@MgAl–LDH@Au nanocatalyst was simply synthesized via supporting Au nanoparticles on the MgAl–LDH surface of Fe3O4@MgAl–LDH nanospheres. The catalyst exhibited excellent activity for the oxidation of 1-phenylethanol, and can be effectively recovered by using an external magnetic field.The selective oxidation of alcohols to the corresponding carbonyl compounds is a greatly important transformation in synthesis chemistry. Recently, it has been disclosed that hydrotalcite (layered double hydroxides: LDH)-supported Cu, Ag and Au nanoparticles as environmentally benign catalysts could catalyse the oxidation of alcohol with good efficiency. In particular, the Au nanoparticles supported on hydrotalcite exhibit high activity for the oxidation of alcohols under atmospheric O2 without additives. It has been extensively demonstrated that the activity of the nanometre-sized catalysts will benefit from decreasing the particle size. However, as the size of the support is decreased, separation using physical methods, such as filtration or centrifugation, becomes a difficult and time-consuming procedure. A possible solution could be the development of catalysts with magnetic properties, allowing easy separation of the catalyst by simply applying an external magnetic field. From the green chemistry point of view, development of highly active, selective and recyclable catalysts has become critical. Therefore, magnetically separable nanocatalysts have received increasing attention in recent years because the minimization in the consumption of auxiliary substances, energy and time used in achieving separations canresult in significant economical and environmental benefits.Magnetic composites with a core–shell structure allow the integration of multiple functionalities into a single nanoparticle system, and offer unique advantages for applications, particularly in biomedicine and catalysis. However it is somewhat of a challenge to directly immobilize hierarchical units onto the magnetic cores. In our previous work, the Fe3O4 submicro-spheres were first coated with a thin carbon layer, then coated with MgAl–LDH to obtain an anticancer agent-containing Fe3O4@DFUR–LDH as drug targeting delivery vector. Li et al. prepared Fe3O4@MgAl–LDH through a layer-by-layer assembly of delaminated LDH nanosheets as a magnetic matrix for loading W7O24as a catalyst. These core–shell structural nanocomposites possess the magnetization of magnetic materials and multiple functionalities of the LDH materials. Nevertheless, these reported synthesis routes need multi-step and sophisticated procedures. Herein, we design a facile synthesis strategy for the fabrication of a novel Fe3O4@MgAl–LDH@Au nanocatalyst, consisting of Au particles supported on oriented grown MgAl–LDH crystals over the Fe3O4 nanospheres, which combines the excellent catalytic properties of Au nanoparticles with the superparamagnetism of the magnetite nanoparticles. To the best of our knowledge, this is the first instance of direct immobilization of vertically oriented MgAl–LDH platelet-like nanocrystals onto the Fe3O4 core particles by a simple coprecipitation method and the fabrication of hierarchical magnetic metal-supported nanocatalysts via further supporting metal nanoparticles.As illustrated in Scheme 1, the synthesis strategy of Fe3O4@MgAl–LDH@Au involves two key aspects. Nearly monodispersed magnetite particles were pre-synthesized using a surfactant-free solvothermal method. First, the Fe3O4 suspension was adjusted to a pH of ca. 10, and thus the obtained fully negatively charged Fe3O4spheres were easily coated with a layer of oriented grown carbonate–MgAl–LDH via electrostatic attraction followed by interface nucleation and crystal growth under dropwise addition of salts and alkaline solutions. Second, Au nanoparticles were effectively supported on thus-formed support Fe3O4@MgAl–LDH by a deposition–precipitation method (see details in ESI).Fig. 1 depicts the SEM/TEM images of the samples at various stages of the fabrication of the Fe3O4@MgAl–LDH@Au nanocatalyst. The Fe3O4nanospheres (Fig. 1a) show asmooth surface and a mean diameter of 450 nm with a narrow size distribution (Fig. S1, ESI). After direct coating with carbonate–MgAl–LDH (Fig. 1b), a honeycomb like morphology with many voids in the size range of 100–200 nm is clearly observed, and the LDH shell is composed of interlaced platelets of ca. 20 nm thickness. Interestingly, the MgAl–LDH shell presents a marked preferred orientation with the c-axis parallel to, and the ab-face perpendicular to the surface of the magnetite cores, quite different from those of a previous report. A similar phenomenon has only been observed for the reported LDH films and the growth of layered hydroxides on cation-exchanged polymer resin beads. The TEM image of two separate nanospheres (Fig. 1d) undoubtedly confirms the core–shell structure of the Fe3O4@MgAl–LDH with the Fe3O4 cores well-coated by a layer of LDH nanocrystals. In detail, the MgAl–LDH crystal monolayers are formed as large thin nanosheet-like particles, showing a edge-curving lamella with a thickness of ca. 20 nm and a width of ca. 100 nm, growing from the magnetite core to the outer surface and perpendicular to the Fe3O4surface. The outer honeycomb like microstructure of the obtained core–shell Fe3O4@MgAl–LDH nanospheres with a surface area of 43.3 m2g_1 provides abundant accessible edge and junction sites of LDH crystals making it possible for this novel hierarchical composite to support metal nanoparticles. With such a structural morphology, interlaced perpendicularly oriented MgAl–LDH nanocrystals can facilitate the immobilization of nano-metal particles along with avoiding the possible aggregation.Scheme 1 The synthetic strategy of an Fe3O4@MgAl–LDH@Au catalyst.Fig. 1 SEM (a, b and c), TEM (d and e) and HRTEM (f) images and EDX spectrum (g) of Fe3O4 (a), Fe3O4@MgAl–LDH (b and d) and Fe3O4@MgAl–LDH@Au (c, e, f and g).Fig. 2 XRD patterns of Fe3O4 (a), Fe3O4@MgAl–LDH (b) and Fe3O4@MgAl–LDH@Au(c).The XRD results (Fig. 2) demonstrate that the Fe3O4@MgAl–LDH nanospheres are composed of an hcp MgAl–LDH (JCPDS 89-5434) and fcc Fe3O4 (JCPDS 19-0629). It canbe clearly seen from Fig. 2b that the series (00l) reflections at low 2θ angles aresignificantly reduced compared with those of single MgAl–LDH (Fig. S2, ESI), while the (110) peak at high 2θangle is clearly distinguished with relatively less decrease, as revealed by greatly reduced I(003)/I(110) = 0.8 of Fe3O4@MgAl–LDH than that of MgAl–LDH (3.9). This phenomenon is a good evidence for an extremely well-oriented assembly of MgAl–LDH platelet-like crystals consistent with the c-axis of the crystals being parallel to the surface of an Fe3O4core. The particle dimension in the c-axis is calculated as ~ 25 nm using the Scherrer equation (eqn S1, ESI) based on the (003) line width (Fig. 2b), in good agreement with the SEM/TEM results. The energy-dispersive X-ray (EDX) result (Fig. S3, ESI) of Fe3O4@MgAl–LDH reveals the existence of Mg, Al, Fe and O elements, and the Mg/Al molar ratio of 2.7 close to the expected one (3.0), indicating the complete coprecipitation of metal cations for MgAl–LDH coating on the surface of Fe3O4.The FTIR data (Fig. S4, ESI) further evidence the chemical compositions and structural characteristics of the composites. The as-prepared Fe3O4@MgAl–LDH nanosphere shows a sharp absorption at ca. 1365 cm_1 being attributed to the ν3 (asymmetric stretching) mode of CO32_ ions and a peak at 584 cm_1 to the Fe–O lattice mode of the magnetite phase, indicating the formation of a CO32–LDH shell on the surface of the Fe3O4 core. Meanwhile, a strong broad band around 3420 cm_1 can be identified as the hydroxyl stretching mode, arising from metal hydroxyl groups and hydrogen-bonded interlayer water molecules. Another absorption resulting from the hydroxyl deformation mode of water, δ(H2O), is recorded at ca. 1630 cm_1.Based on the successful synthesis of honeycomb like core–shell nanospheres, Fe3O4@MgAl–LDH, our recent work further reveals that this facile synthesis approach can be extended to prepare various core–shell structured LDH-based hierarchical magnetic nanocomposites according to the tenability of the LDH layer compositions, such as NiAl–LDH and CuNiAl–LDH (Fig. S3, ESI).Gold nanoparticles were further assembled on the honeycomb likeMgAl–LDH platelet-like nanocrystals of Fe3O4@MgAl–LDH. Though the XRD pattern (Fig. 2c) fails to show the characteristics of Au nanoparticles, it can be clearly seen by the TEM of Fe3O4@MgAl–LDH@Au (Fig. 1e) that Au nanoparticles are evenly distributed on the edgeand junction sites of the interlaced MgAl–LDH nanocrystals with a mean diameter of 7.0 nm (Fig. S5, ESI), implying their promising catalytic activity. Meanwhile, the reduced packing density (large void) and the less sharp edge of LDH platelet-like nanocrystals can be observed (Fig. 1c and e). To get more insight on structural information of Fe3O4@MgAl–LDH@Au, the HRTEM image was obtained (Fig. 1f). It can be observed that both the Au and MgAl–LDH nanophases exhibit clear crystallinity as evidenced by well-defined lattice fringes. The interplanar distances of 0.235 and 0.225 nm for two separate nanophases can be indexed to the (111) plane of cubic Au (JCPDS 89-3697) and the (015) facet of the hexagonal MgAl–LDH phase (inset in Fig. 1f and Fig. S6 (ESI)). The EDX data (Fig. 1g) indicate that the magnetic core–shell particle contains Au, Mg, Al, Fe and O elements. The Au content is determined as 0.5 wt% upon ICP-AES analysis.Table 1 Recycling results on the oxidation of 1-phenylethanol The VSM analysis (Fig. S7, ESI) shows the typical superparamagnetism of the samples. The lower saturation magnetization (Ms) of Fe3O4@MgAl–LDH (20.9 emu g_1) than the Fe3O4 (83.8 emu g_1) is mainly due to the contribution of non-magnetic MgAl–LDH coatings (68 wt%) to the total sample. Interestingly, Ms of Fe3O4@MgAl–LDH@Au is greatly enhanced to 49.2 emu g_1, in line with its reduced MgAl–LDH content (64 wt%). This phenomenon can be ascribed to the removal of weakly linked MgAl–LDH particles among the interlaced MgAl–LDH nanocrystals during the Au loading process, which results in a less densely packed MgAl–LDH shell as indicated by SEM. The strong magnetic sensitivity of Fe3O4@MgAl–LDH@Au provides an easy and effective way to separate nanocatalysts from a reaction system.The catalytic oxidation of 1-phenylethanol as a probe reaction over the present novel magnetic Fe3O4@MgAl–LDH@Au (7.0 nm Au) nanocatalyst demonstrates high catalytic activity. The yield of acetophenone is 99%, with a turnover frequency (TOF) of 66 h_1,which is similar to that of the previously reported Au/MgAl–LDH (TOF, 74 h_1) with a Au average size of 2.7 nm at 40 1C, implying that the catalytic activity of Fe3O4@MgAl–LDH@Au can be further enhanced as the size of Au nanoparticles is decreased. Meanwhile, the high activity and selectivity of the Fe3O4@MgAl–LDH@Au can be related to the honeycomb like morphology of the support Fe3O4@MgAl–LDH being favourable to the high dispersion of Au nanoparticles and possible concerted catalysis of the basic support. Five reaction cycles have been tested for the Au nanocatalysts after easy magnetic separation by using a magnet (4500 G), and no deactivation of the catalyst has been observed (Table 1). Moreover, no Au, Mg and Al leached into the supernatant as confirmed by ICP (detection limit: 0.01 ppm) and almost the same morphology remained as evidenced by SEM of the reclaimed catalyst (Fig. S8, ESI).In conclusion, a novel hierarchical core–shell magnetic gold nanocatalyst Fe3O4@MgAl–LDH@Au is first fabricated via a facile synthesis method. The direct coating of LDH plateletlike nanocrystals vertically oriented to the Fe3O4 surface leads to a honeycomb like core–shell Fe3O4@MgAl–LDH nanosphere. By a deposition–precipitation method, a gold-supported magnetic nanocatalyst Fe3O4@MgAl–LDH@Au has been obtained, which not only presents high 1-phenylethanol oxidation activity, but can be conveniently separated by an external magnetic field as well. Moreover, a series of magnetic Fe3O4@LDH nanospheres involving NiAl–LDH and CuNiAl–LDH can be fabricated based on the LDH layer composition tunability and multi-functionality of the LDH materials, making it possible to take good advantage of these hierarchical core–shell materials in many important applications in catalysis, adsorption and sensors.This work is supported by the 973 Program (2011CBA00508).译文简易合成易回收的分层核壳Fe3O4@MgAl–LDH@Au磁性纳米粒子催化剂催化氧化醇类物质一种新的核壳结构的Fe3O4@MgAl–LDH@Au纳米催化剂的制备只是通过Au离子负载在已合成的纳米粒子Fe3O4@MgAl–LDH球体的MgAl–LDH的表面上。
材料科学与工程专业英语Unit2ClassificationofMaterials译文
Unit 2 Classification of MaterialsSolid materials have been conveniently grouped into three basic classifications: metals, ceramics, and polymers. This scheme is based primarily on chemical makeup and atomic structure, and most materials fall into one distinct grouping or another, although there are some intermediates. In addition, there are three other groups of important engineering materials —composites, semiconductors, and biomaterials.译文：译文：固体材料被便利的分为三个基本的类型：金属，陶瓷和聚合物。
固体材料被便利的分为三个基本的类型：金属，陶瓷和聚合物。
固体材料被便利的分为三个基本的类型：金属，陶瓷和聚合物。
这个分类是首先基于这个分类是首先基于化学组成和原子结构来分的，化学组成和原子结构来分的，大多数材料落在明显的一个类别里面，大多数材料落在明显的一个类别里面，大多数材料落在明显的一个类别里面，尽管有许多中间品。
尽管有许多中间品。
除此之外，此之外， 有三类其他重要的工程材料－复合材料，半导体材料和生物材料。
有三类其他重要的工程材料－复合材料，半导体材料和生物材料。
Composites consist of combinations of two or more different materials, whereas semiconductors are utilized because of their unusual electrical characteristics; biomaterials are implanted into the human body. A brief explanation of the material types and representative characteristics is offered next.译文：复合材料由两种或者两种以上不同的材料组成，然而半导体由于它们非同寻常的电学性质而得到使用；生物材料被移植进入人类的身体中。
《华中科技大学文华学院毕业设计(论文)文献综述及外文文献翻译》
3结论
在调查期间所获得的实验结果的基础上，得出以下结论：对COD和氨氮的浓度不但没有造成厌氧填埋场中的积累，而且迅速下降，并保持300至100毫克/升，分别在48周。同时，减少率达到98.9％和96.9％，分别为：硝酸盐浓度迅速增加并持续24周后，250毫克/升后，持续41周。
Evolution on qualities of leachate and landfill gas in thesemi-aerobic landfill
材料科学专业英语正文课文翻译
材料科学专业英语正文课文翻译
材料科学是一门研究物质的性质和组成以及它们在不同条件下的行为的学科。
它涵盖了从原子和分子到大型结构的各种材料，包括金属、陶瓷、高分子材料和半导体等。
材料科学的发展为各个领域的技术和应用提供了基础和支持。
在材料科学中，有许多不同的性质和特征需要被研究和理解。
这些包括材料的力学性能、热性能、电性能、光学性能以及化学性能等。
通过对这些性能的探究，学者们可以确定材料的适用范围、使用条件和潜在的改进方向。
材料科学的研究还涉及到材料的制备和处理方法。
这些方法包括从原材料中提取纯净物质、合成新材料以及对已有材料进行改性等。
研究人员通过不断改进这些方法，可以制备出更加优良和具有特殊功能的材料，以满足各种需求。
材料科学的应用广泛存在于各个领域中。
在汽车工业中，材料科学帮助开发更轻量化、更强度的材料，提高汽车的燃油效率和安全性能。
在能源领域，材料科学有助于研究和开发更高效的太阳能
电池和电池材料。
在医疗领域，材料科学帮助设计和开发可生物降解的医用材料，用于组织工程和医疗器械等。
总而言之，材料科学在各个方面都起着重要的作用。
通过对材料的研究和理解，我们能够不断改进现有的材料，开发出更加先进和功能性的材料，推动科技的发展和社会的进步。
材料类外文文献翻译
本科毕业论文外文文献及译文文献、资料题目:The effects of heat treatment onthe microstructure and mechani-cal property of laser melting dep-ositionγ-TiAl intermetallic alloys 文献、资料来源：Materials and Design文献、资料发表（出版）日期:2009.10。
25院（部)：材料科学与工程学院专业：材料成型及控制工程班级：姓名：学号:指导教师：翻译日期：2011。
4。
3中文译文：热处理对激光沉积γ—TiAl金属间化合物合金的组织与性能的影响摘要：Ti—47Al—2。
5V—1Cr 和Ti-40Al—2Cr (at.％）金属间化合物合金通过激光沉积（LMD）成形技术制造。
显微组织的特征通过光学显微镜(OM）、扫描电子显微镜(SEM）、投射电子显微镜(TEM）、和X射线衍射仪（XRD）检测。
沿轴向评估热处理后的沉积试样室温下的抗拉性能和维氏硬度。
结果表明：由γ—TiAl 和α2—Ti3Al构成的γ-TiAl基体试样具有全密度柱状晶粒和细的层状显微组织。
Ti-47Al—2.5V—1Cr基体合金和Ti—40Al-2Cr基体合金沿轴向的室温抗拉强度大约分别为650 MPa、600MPa,而最大延伸率大约为0。
6% 。
热处理后的Ti—47Al—2.5V-1Cr和Ti-40Al-2Cr合金可以得到不同的显微组织.应力应变曲线和次表面的拉伸断裂表明沉积和热处理后的试样的断裂方式是沿晶断裂。
1。
简介金属间化合物γ-TiAl合金由于其高熔点（﹥1450℃)、低密度（3g/cm3）、高弹性模量（160—180GPa）和高蠕变强度（直到900℃）成为很有前景的高温结构材料，一直受到广泛研究［1–4］.但是对于其结构应用来说，这种材料主要缺点之一是在室温下缺少延展性。
此外,这种合金运用传统的制造工艺诸如锻压、轧制和焊接,加工起来比较困难［5].对于TiAl组份，传统的铸造技术不利条件是粗大的铸态组织导致室温下的机械性能变差。
材料选择外文文献翻译、中英文翻译
附译文二Selecting MaterialsWe are surrounded by materials and we rarely think about how these materials are selected. Why was your desk made of solid wood, plywood, or plastic-laminated particleboard? Why have so many plastics replaced steel and zinc in automobiles? What is the controversy about using foamed polystyrene plastic to package fast food?While you might take granted the materials that make up your products, you can be sure that the designers did not. People who design homes, cars, aircraft, clothing, furniture, and other products or systems devote a lot of attention to the selection of the materials they use. Material selection might make or break a company. But how do the designers make that selection to arrive at the best material? What selection criteria are most important?The Ideal MaterialWhat is an ideal material? Among other characteristics, we can list the following for the ideal material:1.Endless and readily available source of supply2.Cheap to refine and produce3.Energy efficient4.strong, stiff, and dimensionally stable at all temperatures5.Lighweight6.Corrosion resistant7.No harmful effects on the environment or people8.Biodegradable9.Numerous secondary usesIt is a very complex process for the designer to find the ideal material for a specific product.Obstacles to ChangeSwitching from traditional materials such as steel and concrete to newer materials such as plastic-based composites seem a simple, straightforward approach for the contemporary designer. The newer materials are often superior, but sometimes there are complications. Often, lack of experience with new materials causes hesitation by designers. Departures from tried-and-true materials may be costly. It requires time before both designers and fabricators gain sufficient experience to make products or systems. This problem is exacerbated when human life might be in jeopardy, such as when designing for aircraft. Consequently, new materials and processes are usually slower to enter the marketplace than might be expected. These issues are all a part of engineering problem solving. Materials selection is a problem-solving issue that requires an algorithm for its solution.Algorithm for Materials SelectionEngineering requires clearly stated, unambiguous steps for problem solving. Algorithms are well-defined methods for solving specific problems. Computer programs are written after an algorithm has been developed to lie out clearly the steps that the program is to solve. For example, you could write a simple algorithm to calculate the strength required of a light pole to withstand the pushing forces from a light fixture. A much more complex algorithm would be required to select a piston connecting rod for an internal-combustion engine. The first problem requires only the selection of a material of suitable size/strength to hold up the light fixture, and almost any material would suffice as long as it was sufficiently strong and pleasing to the user. On the other hand, a connecting rod will undergo many types of mechanical stress, ranging from compressive to tensile to torsional to gravity forces, in addition to thermal stress from the combustion chamber. How does the designer match component requirements with available materials?Selection Tools To aid in the creation of materials selection algorithms, databases must be available to answer questions on material suitability. A materials database involves tables listing properties of materials, such as tensile strength, hardness, corrosion resistance, and the ability to withstand heat. Thousands of reference books are available with such data. Much of these data are computerized to allow easier access. Certain graphical techniques aid the designer in materials selection.Properties of Materials Periodicals can provide current data and performance criteria that involve that involve structural materials:1.Strength (tensile, compressive, flexural, shear, and torsional)2.Resistance to elevated temperatures3.Fatigue resistance (repeated loading and unloading)4.Toughness (resistance to impact)5.Wear resistance (harddness)6.Corrosion resistanceSuch publications present values for the performance criteria (properties) for metals, polymers, and ceramics, with updates on newer materials such as aramid fibers, zinc aluminum alloys, and super alloys. Various periodicals have annual materials selectors that provide general information on properties for a long list of materials.The many tables, covering representative materials, provide general data on properties for a simple comparison. Selection of specific materials requires many more detailed specifications. General databases from handbooks will provide much detail, but the final selection often requires that material manufacturers supply their own properties database for their product lines. While databases are imperative in the initial selection steps, there are other factors that complicate materials selection.Materials Systems Materials rarely exist in isolation withoutinteracting with other materials. Rather, a combination of materials is selected to complement one another. In a successful materials system, each component is compatible with the others while contributing its distinctive properties to the overall characteristics of the system of which it is a part. A state-of-the –art telephone is a good example. The casing might be a tough ABS plastic, which houses a microchip (a solid-state ceramic device) that provides memory and sound-transmission capabilities. Copper leads join the circuitry together. There might be a battery and a ceramic must light-emitting diode to show when the battery is low. The acid in the battery must be isolated to prevent corrosion, and the copper leads must be insulated so that they do not short out. Each component is made of materials that meet the demands of the physical and chemical environment normally encountered when using the system.Additional Selection Criteria Existing specifications have a lot of influence on the choice of material. These specifications or “standards” are used when redesigning an improved model of the product. When the materials-selection algorithm results in selection of a new material, I might not be covered by current specifications from standardization agencies. The conditions of safety must be met by those involved in the manufacture or use of goods and services. It might take the new material or they might not approve its use.Availability is another concern of the designer. Will the material be easily available in the quantities and sizes required by the production demands? In addition, will it be available in the shapes required? Aluminum extrusions, for example, are available in many varieties of standard shapes, such as round, oval, and square tubing. In the past, designers were limited to existing materials such as metal alloys, woods, or concrete. Now, it is possible to start from scratch at the synthesis stage to have materials engineers design a materials system to provide properties to meet the expected needs.Processibility, the ease with which raw materials can be transformed into a finished product, is of paramount concern. Much of the current focus is on low-energy processing. Companies may have difficulty processing the new material on existing equipment. Can they afford to invest in new equipment? Today, the reverse question is usually asked: Can we afford to use the new material and process? If we do not, the competition might make the change and run us out of business with their superior product. Many new technologies are now available.Quality and performance are two aspects that achieve consumer satisfaction. The high cost of most durable goods and the competition for customer acceptance has resulted in extended warranties. Materials selection must ensure that parts will not rust, break under repeated stress, or fail to perform in any other way for the predicted service life of the product.Consumer acceptance includes many factors beyond excellent quality and high performance; there are also societal aspects. Society as a whole as well asgovernmental agency is requiring a closer look at manufactured products. Any product has to be considered in terms of its total life cycle. What are the results of the processing methods? Are polluting gases being released into the environment, or are toxic metals and chemicals being flushed into our rivers and streams? During use, does the product safeguard our health? At the end of the product’s useful life, how can it be disposed of safely? Municipal solid waste is a hidden product cost that we pay in the form of higher taxes and poorer quality of life. Fast-food restaurant chains moved away from polystyrene packages because the public felt these plastic containers were more harmful to the environment than paper packaging. Soft-drink manufacturers are moving toward reusable plastic bottles.Design for disassembly has become a theme in much of product design by major corporations. Europe, which has a higher degree of ecological concern, has led the way. With the desire to facilitate recycling, manufacturers of small appliances and durable goods are establishing procedures to ensure that products can be broken into components for easy sorting prior to recycling. Among the procedures are reducing the variety of plastics, adding labels to plastics for easy identification of plastic type, and eliminating screws and adhesives so that parts will disassemble easily.One of the latest software programs is designed specifically to make products easier to fix. Known as Design for Service, this program takes its place alongside previous software programs called Design for Assembly and Design for Manufacturability. This new program helps product designers consider repair issues early in the design stage. Objectives of the program include making repairs less costly and extending the functioning life of products. Environmental issues such as recycling are directly addressed by this new computer software, which may have customers fixing products rather than tossing them out. In addition, this software augments previous software that addresses the need for disassembly of a product for whatever reason.More often than not, cost is the primary selection criterion that will determine the final choice of material. In other words, if several materials have the specified physical, mechanical, and chemical properties, and are suitable for the processing technique selected, the lower-cost materials would be the logical choice. Determining cost is not as simple as it may seem. For example, a variety of plastics, including PET (poly ethylene terephthalate) and HDPE (high-density polyethylene), have replaced glass as containers for soft drinks, milk and juices. Although the initial cost of plastic may be greater, the plastic bottles provide saving due to their toughness (less breakage) and the saving in shipping (PET and HDPE are much lighter than glass bottles).Product liability is civil (as opposed to criminal) liability of the manufacturer to an ultimate user for injury resulting from a defective product. Caveat emptor (let the buyer beware) was once the rule. Today, numerous liability laws are in effect. For those involved in materials selection in the design process, the trend is for courts and juries to identify members of the design team as being responsible forsome fault in a product-liability action. Therefore, it is imperative to obtain and use the latest information about materials selection, particularly long-term characteristics of materials.材料选择我们是被材所包围并且很少思考我们是如何选择材料的。
材料专业文献翻译
Synthesis and Gas Sensitivity of In2O3/CdO Composite Abstract: Indium oxide (In2O3) was synthesized using a hydrothermal process. The crystallography and microstructure of the synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The In2O3 had a flower-like hierarchical nanostructure and was composed of tiny near-spherical crystals with a diameter of approximately 20 nm.When In2O3 was mixed with CdO in a 1:1 molar ratio, it was found that the resulting In2O3/CdO composite showed an interesting grape-like porousmicrostructure following calcinations at elevated temperatures. A gas sensor using this In2O3/CdOcomposite as the sensing material showed higher sensitivity to different concentration of formaldehyde than the gas sensor based on pure flower-like In2O3 nanomaterials. The In2O3/CdO-based sensors showed a high sensitivity to a concentration of 0.05×10-6 formaldehyde at the optimized operating temperature of 410 °C and a good level of selectivity over other possible interference gases such as ethanol, toluene, acetone, methanol, and ammonia. The gas sensing mechanism of In2O3/CdO sensor has been discussed in detail.1 IntroductionFormaldehyde (HCHO) is a colorless and strong-smellinggas coming from building materials, interior decoration materials,wood furniture, carpet and so on.HCHO is one of the most dangerous indoor pollutants among volatile organic compounds (VOCs), and is found to be associated with asthma, nasopharyngeal cancer, and multiple subjective health complaints. In particular, HCHO is considered as a major cause of sick building syndrome (SBS). World Health Organization (WHO) established a standard of 0.08×10-6 (volume fraction)averaged over 30 min for long-term exposure in formaldehyde vapor. Many methods to detect VOCs have been investigated. Among them, semiconductor gas sensors are widely used since they are cheap and easy to be available. The sensing materials, including SnO2,10-12 ZnO,13 NiO,14 and In2O3,15,16 have been explored for formaldehyde detection.In recent years, nanostructure semiconductor materials havebeen extensively studied due to their exceptional propertiesand potential applications in various fields.Among them, indium oxide (energy gap 3.67 eV, Bohr radius 2.14 nm) material has been widely studied because of its unique optoelectronic properties, such as high electrical conductivity and high UV transparency.It has been widely used in the optoelectronic devices such as solar cells, window heaters, and liquid crystal displays。
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Abstract: A supporting body of diatomite-based porous ceramics was prepared by a solid-phase sintering process and low-temperature calcination process. A nano-TiO2 compound membrane was loaded on the supporting body by the hydrolysis precipitation method and using TiCl4 as the forerunner body, and the TiO2/diatomite-based porous ceramic composite structure was characterized by X-ray diffraction and scanning electron microscopy and so on. The photocatalytic activities of TiO2 films were investigated by the degradation of formaldehyde. The results indicate that the TiO2 films in TiO2/diatomite-based porous ceramic composite calcined at 550 ℃are anatase, and the average grain size of TiO2 is 10.9 nm. The elimination rate of the composites for formaldehyde reaches 96.8% in 6 h under an ultraviolet lamp irradiation of 8 W, and the concentration of formaldehyde drops to 0.015 mg/m3 from 0.463 mg/m3.
Key words: diatomite-based porous ceramics; nano-titania compound membrane; water solution precipitation method; formaldehyde;
photocatalytic activity
摘要：采用固相烧结法和低温煅烧工艺，制备了硅藻土基多孔陶瓷支承体。
以四氯化钛为前驱体，采用水解沉淀法在支承体上负载纳米TiO2复合膜。
用X射线衍射仪和扫描电子显微镜等对TiO2复合膜/多孔陶瓷支承体的复合结构进行了表征；并以甲醛为降解对象，考察了TiO2复合膜的光催化性能。
结果表明：纳米TiO2/硅藻土基多孔陶瓷复合膜在550℃煅烧后TiO2为锐钛矿型，平均晶粒粒径为10.9 nm。
在紫外光照射240min后，甲醛气体初始浓度由0.463 mg/m3 降至0.015 mg /m3，复合材料对甲醛的去除率达到96.8%。
关键词：硅藻土基多孔陶瓷；纳米二氧化钛复合膜; 水解沉淀法；甲醛；光催化性能Abstrac:t Photocatalytic ceramic foam filter, the composite of high photo active TiO2 nano mate rials and three dimensional porous ceramic foam materials, has been widely applied in the field of air /water purification, owing to its characteristics of high photoactivity, large surface area, large flowing flux and ceramic heat/ chemical resistance, recycling probability. Applications have been in the fields of industrial exhaust deodorization, agriculture pesticide degradation using sunlight, sterilization of laboratories and hospitals, high-speed train air purification, and so on. The application research progress, problem and future prospect of photo catalytic ceramic foam filter are summarized.
Key words: photo catalyst; ceramic foam filter; application; air /water purification
摘要: 高活性的光催化二氧化钛纳米材料与高气孔率的三维多孔泡沫陶瓷材料复合, 得到的光催化泡沫陶瓷过滤器, 具备高活性、大表面积、大通量、以及陶瓷的耐高温、耐化学腐蚀、循环适用性, 在大气/水净化领域率先得到了广泛应用。
在工业领域的废气脱臭处理、在农业领域的农药废水太阳光降解、在医疗卫生领域的实验室医院空气杀菌处理、在交通领域的高速列车空气净化等, 已经展开应用。
综述了国内外光催化泡沫陶瓷过滤器的应用研究现状、问题及其发展趋势。
关键词: 光催化; 泡沫陶瓷过滤器; 应用研究; 大气/水净化。