专业英语重点句子(带单词翻译版).doc

Unit 1 (5个)1. Materials science and engineering (MSE) is an interdisciplinary field concerned with inventing new materials and improving previously known materials by developing a deeper understanding of the microstructure-composition-synthesis-processing relationships. 2. Materials scientists and engineers not only deal with the development of materials, but also with the synthesis and processing of materials and manufacturing processes related to the production of components.3. One of the most important functions of materials scientists and engineers is to establish the relationships between a material or a devices properties and performance and the microstructure of that material, its composition, and the way the material or the device was synthesized and processed. 4. In materials science, the emphasis is on the underlying relationships between the synthesis and processing, structure, and properties of materials.5. In materials engineering, the focus is on how to translate or transform materials into a useful device or structure. Unit 2（3个）6. What is also fascinating about van der Waals forces is that they begin as inter actions between atoms and molecules that ultimately lead to considerable forces between fine particles of any material. 7. We make use of metal and ceramic powders (dry or slurries) in processing many ceramic and metallic materials through routes collectively known as powder processing (Processing technique for metals involving the solid-state bonding of a fine grained powder into a fully dense product). 8.We can accomplish this by introducing like charges on the particles (electrostatic stabilization) or adsorbing soap like surfactant molecules on the surfaces of particles (steric stabilization).Unit 3（8个）9. The Si-O bond in the SiO44- structure in about 50 percent covalent and 50 percent ionic according to calculations from Paulings equation. 10. The tetrahedral coordination of SiO44- satisfies the directionality requirement of covalent bonding and the radius ratio requirement of ionic bonding. 11. If two corners of each SiO44- tetrahedron are bonded with the corners of other tetrahedra, a chain or ring structure with the unit chemical formula of SiO32- results. 12. Silicate sheet structure form when three corners in the same plane of a silicate tetrahedron are bonded to the corners of three silicate tetrahedra.13. The mineralmnrl(矿物的,矿物) kaolinitekelnat (高岭石) consists (in its pure form) of every small, flat plates roughly hexagonalheksnl( 六边的，六角形的) in shape, with their average size being about 0.7um in diameterdamt( 直径) and 0.05 um thick. 14. Another example of a sheet silicate is the mineral talctlk( 滑石；云母), in which a sheet of Mg3(OH)24+ bonds with two outer-layer Si2O52- sheets (one on each side) to form a compositekmpzt( 复合的；合成的) sheet with the unit chemical formulafmjl(公式,方程式) Mg3(OH)2(Si2O5)2. 15. Crystallinekrst()lan( 结晶的) silica exists in several polymorphic,plmfk( 多态的) forms that correspond to different ways in which the silicate tetrahedral are arranged with all corners shared. 16. The most stable forms of silica and the temperature ranges in which they exist at atmospheric pressure are low quartzkwts(石英) below 573, high quartz between 573 to 867, high tridymitetrdmat( 鳞石英) between 867 and 1470, and high cristobitekristu,blait(方石英) between 1470 and 1710.Unit 4（15个）17. Point defects(点缺陷) are localizedloklazd( 局部的；地区的；小范围的) disruptionsdsrpn(破坏) in otherwise perfect atomic or ionic arrangements in a crystal structure. 18. These imperfections, may be introduced by movement of the atoms or ions when they gain energy by heating, during processing of the material, by introduction of impurities, or dopingdop(掺杂). 19. An important point about point defects is that although the defect occurs at one or two sites, their presence is felt over much larger distances in the crystalline material. 20. When atoms or ions are missing (i.e., when vacancies are present), the overall randomnessrndmns( 随意；无安排；不可测性) or entropyentrp(熵) of the material increases, which increases the thermodynamic,mdanmk( 热力学的) stability of a crystalline material. 21. Vacanciesveknsi(空位) play an important role in determining the rate at which atoms or ions can move around, or diffusedfjuz(弥散,扩散) in a solid material, especially in pure metals.22. If we conduct(管理；引导；表现) this sinteringsntr(烧结) treatment in a reducing or inert atmosphere (e.g., hydrogen or nitrogen), some of the oxygen ions from BaTiOa will leave the material in the form of oxygen gas. 23. In some cases, we can introduce vacancies at specific ion sites so as to enhance the movement of ions in ceramic materials, which can help sinter ceramicsnhns( 提高；加强；增加) at lower temperatures. 24. At room temperature(298K), the concentrationkns()ntre()n(集中,浓度) of vacancies is small, but the concentration of vacancies increases exponentially,ksponnli( 以指数方式) as we increase the temperature, as shown by the following Arrhenius type behavior:25. Interstitial,ntst()l( 间质的；空隙的；填隙的) atoms or ions，although much smaller than the atoms or ions located at the latticelts( 晶格；格子) points，are still larger than the interstitial sites that they occupy; consequently, the surrounding crystal regionrid()n(范围) is compressed and distorteddstrtd(扭曲). 26. Interstitial atoms such as hydrogenhadrd()n(氢) are often present as impurities; whereaswerz( 然而；鉴于；反之) carbon atoms are intentionally added to iron to produce steel.27. If there are dislocations(变位；位移；断错) in the crystals trying to move around these types of defects, they face a resistance to their motion, making it difficult to create permanent deformation(永久性变形) in metals and alloys. 28. Substitutional,sbsttjnl(置换) atoms or ions may either be larger than the normal atoms or ions in the crystal structure, in which case the surrounding inter-atomic spacings are reduced, or smaller causing the surrounding atoms to have larger inter-atomic spacings. 29. Whether atoms or ions added go into interstitial or substitutional sites depends upon the size and valence of guest atoms or ions compared to the size and valence of host ions.Unit 5（10个）30. Semiconductors(半导体) which do not contain appreciableprib()l( 可感知的；可评估的；相当可观的) levels of dopants or impurities are known as intrinsicntrnsk( 本质的，固有的) semiconductors, When we add small concentrations of P or B to silicon crystal, these atoms occupy crystallographic,krstlrfk( 结晶的) sites where silicon atoms usually reside(住，居住；属于). 31. The result is each P atom added has one extra electron that cannot pair with a Si atom to form a fifth Si-P bond. 32. The entire microelectronics,makrlektrnks微电子学) industry, as we know it today, would not exist if we did not have a good understanding of the diffusion of different atoms into silicon or other semiconductors.33. Strong covalent,kovelnt( 共价的) and ionic bonds along with microstructural features contribute to the relatively poor electrical conductivity exhibitedgzbt by many ceramics. 34. The ability of ions to diffuse and provide a pathway for electrical conduction plays an important role in enabling these applications.35. This is one of the major reasons why we use polyethylene terephthalate (PET聚对苯二甲酸乙二醇酯) to make bottles which ensure that the carbonated beveragesbev()rd(饮料) they contain will not loose their fizz(兴奋，活力；嘶嘶声；充气饮料) for a reasonable period of time.36. In reality, aluminumljumnm oxidizesksdaz(氧化) (rusts) more easily than iron. However, the aluminum oxide (Al2O3) forms a very protective but thin coating on the aluminums surface preventing any further diffusion of oxygen and hindering(妨碍) further oxidation of the underlying aluminum.37. We distinguishdstgw( 区分) between the movement of atoms, moleculesml,kjl, ions, electrons, holes, etc. as a result of concentration gradientgrednt(梯度) and temperature (diffusion) or some other driving force, such as gradients in densitydenst(密度), electric field, or magnetic field gradients. 38. This equation is derived from(来自，源自于) a statistical analysis(统计分析) of the probability that the atoms will have the extra energy Q needed to cause movement. 39. The disorder vacancies create (i.e., increased entropy) helps minimize the free energy and, therefore, enhance the thermodynamic stability of a crystalline material. 40. In chapter 3, we have seen that for many ceramics with ionic bonding the structure can be considered as close packing(密集流水) of anions(阴离子)with cations(阳离子；正离子) in the interstitial sites.41. At higher temperatures, the thermalm()l(热的) energy supplied to the diffusing atoms permits the atoms to overcome the activation energy(活化能) barrier and more easily move to new sites in the atomic arrangements. Unit 6（9个）42. Since melting, casting, and thermomechanical,:mumiknikl( 热 热机的，热 热机械的) processing is not a viablevabl( 可行的；能养活的；能生育的) option for polycrystalline,plkrstlan(多晶) ceramics, we typically process ceramics into useful shapes starting with ceramic powders.43. In this process, the green ceramic is heated to a high temperature, using a controlled heat and atmosphere, so that a dense material is obtained.44. Powders consist of particles that are loosely bonded, and powder processing involves the consolidationkn,slden( 巩固；合并；团结) of these powders into a desired shape.45. In some cases, very large pieces (up to a few feet in diameter and six to eight feet long) can be produced using a process called cold isostatic pressing (CIP冷等静压制) where pressure is applied using oil. 46. Similarly, large pieces of metals and alloys compactedkmpktid( . 压实的；压紧的) using CIP can be sintered under pressure in a process known as hot isostatic pressing (HIP热等静压；高温等静力压制). 47. Some recent innovativenvetv( 革新的，创新的) processes that make use of microwaves (similar to the way food gets heated in microwave oven) have also been developed for the drying and sintering of ceramic materials.48. Some ceramics, such as silicon nitridenatrad( 氮化物) (Si3N4), are produced by reaction bonding(反应粘合).49. Reaction bonding, which can be done at lower temperatures, provides better dimensionaldmennl(空间的,尺寸的) control compared with hot pressing; however, lower densities and mechanical properties are obtained. 50. This mixture has a clay(粘土)-lake consistencyknsst()ns( 一致性；稠度；相容性), which is then fed to an extruderkstrud( 挤出机；挤压机) where it is mixed well in a pug mill(搅拌机), shearedd(修剪), deaerateddiret(出去空气), and then injected(注入的) into a die(冲模，钢模；骰子)where a continuous shape of green ceramic is produced by the extruder. Unit 7（2个）51. The combination of transparencytrnspr()ns( 透明，透明度) and hardness at room temperature along with sufficient(足够的；充分的) strength and excellent corrosion kr()n( 腐蚀)resistance to most normal environments make glasses indispensable for many engineering applications such as construction and vehicle glazing(上釉；玻璃装配业). 52. However, in borosilicate,brslket glasses(硼硅酸盐玻璃) that have additions of alkalilkla( 碱；可溶性无机盐) and alkaline earth(碱土金属) oxides, BO33- triangles can be converted(转化) to BO44- tetrahedra, with the alkali or alkaline earth cations providing the necessary electroneutrality. Unit 8（14个）53. It reacts relatively quickly with water, and in normal Portland cements(波特兰水泥，硅酸盐水泥，普通水泥) is the most important of the constituentknsttjnt( 成分；选民；委托人) phases for strength development; at ages up to 28 days, it is by far the most important.54. The rate at which it reacts with water appears to be somewhat variable, perhaps due to differences in composition or other characteristics, but in general is high initiallyn()l(起初的) and low or very low at later ages.55. The standard specifications(标准技术规范；标准规格) with which such cements(水泥；胶合剂) must complykmpla( 遵守) are similar, but not identicaladentk()l( 同一的；完全相同的), in all countries and various names are used to define the materials, such as Class 42.5 Portland cement in current European and British standards (42.5 is the minimum 28-days compressive strength in MPa), Type I and II Portland cement in the ASTM (American Society for Testing and Materials) specifications used in USA, or Ordinary Portland Cement(OPC) in former British standards.56. Standard specifications are, in general, based partly on chemical composition or physical properties such as specific surface area, and partly on performance tests, such as setting time or compressive strength developed under standard conditions. 57. The content of MgO is usually limited to 4%-5%, because quantities of this component in excess of about 2%can occur as periclase (magnesium oxide), which through slow reaction with water can cause destructive expansion of hardened concretekkrit( 具体物；凝结物).58. Many other minorman(次要的,未成年的) components are limited in content by their effects on the manufacturing process, or the properties, or both, and in some cases the limits are defined in specifications. 59. Rapid-hardening Portland cements have been produced in various ways, such as varying the composition to increase the aliteeilait( 硅酸三钙石；A-水泥石) content, finer grindingrand(磨的) of the clinkerklk (渣块；炼砖), and improvements in the manufacturing process, e.g., finer grinding or better mixing of the raw materials.60. The alite contents of Portland cements have increased steadily over the one and a half centuries during which the latter have been produced, and many cements that would be considered ordinary today would have been described as rapid hardening only a few decades ago. 61. For both ordinary and rapid-hardening cements, both lower and upper limits may be imposed on(利用；欺骗；施加影响于) strength at 28 days, upper limits being a safeguard against poor durability,djrblti( 耐久性；坚固；耐用年限) resulting from the use of inadequatendkwt( 不充分的，不适当的) cement contents in concrete.62. Destructive expansion from reaction with sulfatesslfet( 硫酸盐) can occur not only if the latter are present in excessiveksesv( 过多的，极度的) proportion(比例) in the cement, but also from attack on concrete by sulfate solutions. 63. The reaction involves the Al2O3-containging phases in the hardened cement, and in sulfate-resisting Portland cements its effects are reduced by decreasing the proportion of the aluminate phase, sometimes to zero.64. The reaction of Portland cement with water is exothermic,eks()mk(发热的), and while this can be advantage under some conditions because it accelerates hardening, it is a disadvantage under others, such as in the construction of large dams or in the lining of oil wells, when a cement slurry(水泥渣) has to be pumped over a large distance under pressure and sometimes at a high temperature. 65. lower heat evolution,ivlu()n( 演变；进化论；进展) can be achieved by coarse ks(粗糙的)grinding, and decreased total heat evolution by lowering the contents of alite and aluminate. 66. The ASTM specifications include definitions of a Type II or “moderate heat of hardening” cement, and a more extreme Type IV or “low heat” cement.Unit 9（无）Unit 10（7个）67. Composites(复合材料) are combinations of two materials in which one of the mater