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1、材料专业英语翻译,主讲：林建国,课程简介：,课堂6学时，课后14学时 考试：开卷，当堂完成,主要内容及课时安排,Introduction to materials science and engineering(4学时) Metallic materials and alloys（4学时） Ceramics（2学时） Composites（2学时） Nanostructured materials（2学时）,Part 1 Introduction to materials science and engineering,Unit 1 Physical and chemical properti
2、es of materials Unit 2 Mechanical properties of materials,Unit 1 Physical and chemical properties of materials,Physical properties are those that can be observed without changing the identity of the substance. The general properties of matter such as color, density, hardness, are examples of physica
3、l properties. Properties that describe how a substance changes into a completely different substance are called chemical properties. Flammability and corrosion/oxidation resistance are examples of chemical properties.,In general, some of the more important physical and chemical properties from an en
4、gineering material standpoint include phase transformation temperatures, density, specific gravity, thermal conductivity, linear coefficient of thermal expansion, electrical conductivity and resistivity, magnetic permeability, and corrosion resistance, and so on.,磁导率,Phase Transformation Temperature
5、s,When temperature rises and pressure is held constant, a typical substance changes from solid to liquid and then to vapor. Transitions from solid to liquid, from liquid to vapor, from vapor to solid and visa versa are called phase transformations or transitions. Since some substances have several c
6、rystal forms, technically there can be solid to another solid from phase transformation.,Melting point: the phase transition temperature where a solid changes to a liquid Boiling point: the temperature at which the vapor pressure of a liquid equals 1 atm (101.3 kPa),Some materials, such as many poly
7、mers, do not go simply from a solid to a liquid with increasing temperature. Instead, at some temperature below the melting point, they start to lose their crystalline structure but the molecules remain linked in chains, which results in a soft and pliable material. The temperature at which a solid,
8、 glassy material begins to soften and flow is called the glass transition temperature.,Density,Mass can be thinly dsitrbuted as in a pillow, or tightly packed as in a block of lead. 质量可以像枕头似地稀疏地分布，也可以像铅那样紧紧地堆积在一起。 The space the mass occupies is its volume, and the mass per unit of volume is its dens
9、ity.,Mass (m) is a fundamental measure of the amount of matter. Weight (w) is a measure of the force exerted by a mass and this force is produced by the acceleration of gravity. Therefore, on the surface of earth, the mass of an object is determined by dividing the weight of an object by 9.8 m/s2 (t
10、he acceleration of gravity on the surface of the earth).,因此，在地球表面，物体的质量由物体的重量和重力加速度 所决定。 Since we are typically comparing things on the surface of the earth, the weight of an object is commonly used rather than calculating its mass.,The density (r) of a material depends on the phase it is in and the
11、 temperature (the density of liquids and gases is very temperature dependent). Water in the liquid state has a density of 1 g/cm3 at 4 . Ice has a density of 0.917 1 g/cm3 at 0 , and it should be noted that this decrease in density for the solid phase is unusual. For almost all other substances, the
12、 density of the solid phase is greater than that of the liquid phase. Water vapor has a density of 0.051 g/cm3.,Specific Gravity,Specific gravity is the ratio of density of a substance compared to the density of fresh water at 4 . At this temperature the density of water is at its greatest value and
13、 equal to 1 g/mL. Since specific gravity is a ratio, so it has no units. An object will float in water if its density is less than the density of water and sink if its density is greater than that of water.,Similarly, an object with specific gravity less than 1 will float and those with a specific g
14、ravity greater than 1 will sink. Specific gravity values for a few common substances are Au, 19.3; mercury, 13.6; alcohol, 0.7893; benzene, 0.8786. Note that since water has density of 1 g/cm3, the specific gravity is the same as the density of the material measured in g/cm3.,Magnetic Permeability,M
15、agnetic permeability or simply permeability is the ease with which a material can be magnetized. It is a constant of proportionality that exists between magnetic induction and magnetic field intensity.,磁感应强度,磁场强度,This constant is equal to approximately 1.25710-6 Henry per meter (H/m) in free space (
16、a vacuum). In other materials it can be much different, often substantially greater than the free-space value, which is symbolized 0 . 其他材料却截然不同，通常远大于真空值。,Materials that cause the lines of flux to move farther apart, resulting in a decrease in magnetic flux density compared with a vacuum, are called diamagnetic. Materials that concentrate magnetic flux by a factor of more than one but less than or equal to ten are called paramagnetic; materials that concentrate the flux by a factor of more than
