济南大学专业英语考试.docx

1、济南大学专业英语考试1. What are composites? Characteristics, types什么是复合材料？特点、类型（p98）Composites: composites are hybrid混合的 creations made of two or more materials that maintain their identities（身份） when combined. They are combinations of materials assembled（组合的） together to obtain properties superior to those o

2、f their single constituent characteristics. They are expensive compete with metal and polymers（高分子） because the manufacturing（制造） of composites involves many steps. Its difficult to recycle.Characteristics:(1) The properties of one constituent（成分） enhance the deficient（不足） properties of the other.(2

3、) Usually, a given property of a composite lies between the values for each constituent.(3) Sometimes, the property of a composite is clearly superior to those of either of the constituents.(4) Because manufacturing of composites involves many steps and is labour intensive（劳动力密集型产业）, composites may

4、be too expensive to compete with metals and polymers,(5) Composites are usually difficult to recycle.Types(P96):Composites are classified according to the nature of their matrix: metal, ceramic（陶瓷）, polymer composite, often designated（指定的） MMCs金属基复合材料, CMCs陶瓷基复合材料, PMCs聚合物基复合材料2. classification of m

5、aterials材料的分类？Materials：Natural、Inorganic Non-Metallic Materials, Ceramics、Organic Materials( Polymers, blends混纺)、Metals(Alloys)、Semiconductors、Composites、Biomaterials（生物材料）According to their properties, materials can be broadly classied into the following groups:Structural materials、Functional mate

6、rials、Smart materials（智能材料）Scale（数值范围）of Materials：1. Nanoscale, sizes of about 1 to 100 nanometers；2. Microscale, relevant for micro-devices and microsystems having sizes of typically 1 to 1000 micrometers（微米）；3. Macroscale materials (宏观材料)have the dimensions of all customary products, devices and

7、plants, ranging from the millimeter（毫米） to the kilometer scale。3. Physical properties (names)物理性质(名称)The mechanical properties（机械性质） of material: bend test（弯曲试验）: ductility（延展性）, elasticity（弹性）, brittleness（脆性）. Tensile test（抗拉试验）: yield strength（屈服强度）, tensile strength（抗张强度）. Hardness test（硬度试验）: h

8、ardness. Impact test（冲击试验）: toughness（韧性） under shock（冲击）. Fatigue test疲劳试验: fatigue behavior. Stiffness(硬度); Creep test蠕变试验: creep. Thermal properties: thermal conductivity（热导率）, specific heat capacity（比热容）; Optical properties（光学性质）: reflection（反射） refraction(折射) dispersion（散射）; Electrical properti

9、es（电学性质）： conductivity（导电性）, resistivity（电阻率）, particle-wave duality of light; Magnetic properties: perneabolity, susceptibility（敏感性）, magnetic induction, 4. How to get the stress-strain curve? What are the parameters can we get from this curve?如何得到应力-应变曲线？我们从这个曲线得到什么参数？The result of a tensile test

10、is commonly displayed in a stressstrain diagram.Y: stress, tensile stress. X: strain. Under tensile stress, the rod becomes longer in the direction of the applied force (and eventually narrower perpendicular to that axis), the change in longitudinal dimension in response to stress is called strain :

11、 Parameters参数 ：(1)yield strength 屈服强度y (2)modulus of elasticity弹性模量 E (3) tensile strength抗张强度 t (4) necking (5) breaking Strength力量 b(6) Stress,压力 ; (7)strain, 张力5. what are toughness under shock, fatigue behavior, creep?什么是冲击韧性、疲劳行为、蠕变？(p22)Toughness under shock: When subjected to a sudden blow, s

12、ome materials break at a lower stress than that measured using a tensile machine. The impact tester investigates the toughness of materials by striking them at the center while fixing both ends. Toughness is defined as the energy (not the force) required to break a material.Fatigue behavior: Materia

13、ls, even when stressed below the yield strength, still may eventually break if a large number of tension and compression cycles are applied. The fatigue test measures the number of bending cycles that need to be applied for a specific load until failure occurs. Creep: The creep test measures the con

14、tinuous and progressive plastic deformation of materials at high temperatures while a constant stress or a constant load below the room temperature yield strength is applied.6. What are phonons? Heat capacity ? 什么是声子？热容？(p272)The heat capacity, C: is the amount of heat, dQ, that needs to be transfer

15、red to a substance in order to raise its temperature by a certain temperature interval. The unit for the heat capacity is J/K.Photons： During the absorption of light by intraband transitions, an additional mechanism may take place. It involves lattice vibration quanta called phonons. They are quanta

16、 of the ionic displacement field which represent classical sound; the word phonon conveys the particle nature of an oscillator（振子）.7. illustrates light interaction with matter说明(举例说明)光与物质的相互作用。Absorption of light ；Emission of light；refraction of light；dispersion of light；reflection of light；transmis

17、sion of light；diffraction of light；interference of light.8. luminescence and mechanism? 发光和机制(p259)What are lasers? 什么是激光？How they are obtained?如何获得激光(P261)？Luminescence: The emission of light due to reversion of electrons from a higher energy state is called luminescence.Mechanism: An electron, onc

18、e excited, must eventually revert back into a lower, empty energy state. This occurs, as a rule, spontaneously within a fraction of a second and is accompanied by the emission of a photon and/or the dissipation of heat-phonons. Laser: light amplification by stimulated emission of radiation.Stimulate

19、d emission of light occurs when electrons are forced by incident radiation to add more photons to an incident beam.9. Thermoelectricity and piezoelectricity? Examples and applications? 热电和压电？举例和应用(p220/p212)Piezoelectricity: The pressure is applied to a ferroelectric material, a change in the just-m

20、entioned polarization may occur which results in a small voltage across the sample. The slight change in dimensions causes a variation in bond lengths between cations and anions. This effect is called piezoelectricity.Examples: Quartz（石英）, BaTiO3, in ZnO, in PbZrTiO6;applications: Piezoelectricity i

21、s utilized in devices that are designed to convert mechanical strain into electricity. Those devices are called transducers. Applications include strain gages, microphones, sonar detectors, and phonograph pickups, to mention a few.Thermoelectricity: Assume two different types of materials (e.g., a c

22、opper and aniron wire) which are connected at their ends to form a loop. One of the junctions is brought to a higher temperature than the other. Then a potential difference, V, between these two thermocouples is observed which is essentially proportional to the temperature difference, T, where: V/T=

23、S is called the thermoelectric power.Examples and applications: Thermocouples made of metal wires are utilized as rigid, inexpensive, and fast probes for measuring temperatures even at otherwise not easily accessible places. Thermoelectric power generators (utilizing the above-mentioned semiconducto

24、rs) are used particularly in remote locations of the earth (Siberia, Alaska, etc.).10. Influence of temperature and impurity on resistence of metals? Explanations温度和杂质对金属电阻的影响？(P187)解释.The resistivity of metals essentially increases linearly with increasing temperature according to the empirical equ

25、ation(经验方程):2=11+(T2-T1)where is the linear temperature coefficient of resistivity, and T1and T2 are two different temperatures.Explanation: At higher temperatures, the lattice atoms increasingly oscillate about their equilibrium positions due to the supply of thermal energy, thus enhancing the prob

26、ability for collisions by the drifting electrons. As a consequence, the resistance rises with higher temperature. At near-zero temperature, the electrical resistance dose not completely vanish and the residual resistivity is essentially temperature-independent.11. band structure of semiconductors半导体

27、的能带结构？Intrinsic semiconductor has three electron bands which are valence band ,conduction band and forbidden band. There is completely filled with valence electrons in valence band and conduction band contains no electrons. The forbidden band is not allowed the electrons reside in the gap.Since the

28、filled valence band possesses no allowed empty energy states in which the electrons can be thermally excited (and then accelerated in an electric field), and since the conduction band contains no electrons at all, silicon, at 0 K, is an insulator.Two electron bands, the lower of which, at 0 K, is co

29、mpletely filled with valence electrons called the valence band. It is separated by a small gap from the conduction band,which, at 0 K, contains no electrons. Further, quantum mechanics stipulates that electrons essentially are not allowed to reside in the gap between these bands (called the forbidde

30、n band). Since the filled valence band possesses no allowed empty energy states in which the electrons can be thermally excited (and then accelerated in an electric field), and since the conduction band contains no electrons at all, silicon, at 0 K, is an insulator.12. types, application, machenisms

31、 of magnetic materials (names, differences) 磁性材料的类型、应用和机理。(名字、差异)paramagnetics, diamagnetics, ferromagnetics, ferriamgnetics, and antiferromagnetics.A qualitative as well as a quantitative distinction between these types can be achieved in a relatively simple way by utilizing a method proposed by Fa

32、raday.Magnetic material to be investigated is suspended from one of the arms of a sensitive balance and is allowed to reach into an inhomogeneous magnetic field. Diamagnetic materials are expelled from this field, where para-, ferro-, antiferro-, and ferrimagnetics are attracted in different degrees.FIGURE 12.2. Schematic representation of magnetic field lines in and around different types of materials. (a) Para- or ferromagnetics铁磁体. The magnetic induction (B)磁感应强度 inside the material consists of the free-space component ( 0H) plus a contribution by the m