材料科學與工程導論Chapter 1 - Chapter 2

1、7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology1Introduction to Materials ScienceLei Xu7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology2Chapter 1. IntroductionHistorical PerspectiveStone AgeBronze Ag

2、eIron AgeMalachite CuCO3, Cu(OH)2 Cassiterite SnO2Melting pointBronze 700 900 CIron 1500C7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology3Chapter 1. IntroductionMaterials Science and EngineeringlStructure PropertylMicroscopic, macroscopiclMechanical

3、properties Other properties (electrical, thermal, magnetic, optical, deteriorative)7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology45 nm7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology5Chapter 1. Intr

4、oductionThe structure and composition of a material, including the type of atoms and their arrangement as viewed over the range of length scales (nano-, meso-, micro-, macro-scale).The synthesis and processing by which the particular arrangement of atoms achieved.The properties of the material resul

5、ting from the atoms and their arrangement, that make material interesting or useful.The performance of the material, that is, the measurement of its usefulness in actual conditions, taking account of economic and social costs and benefits.7/1/2022College of Materials Science and Engineering, Qingdao

6、 University of Science and Technology6Chapter 1. IntroductionRelationshipPerformanceSynthesisProcessingStructureCompositionProperties7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology7Chapter 1. IntroductionMicro Structure (Micro-) (Meso-)(Macro-)10-91

7、0-810-710-610-510-410-310-210-1100m10-1010-1110-12101(Nano-)Chpt. 2 Atomic StructuresChpt. 3, 5, 6Chpt. 7, 8, 9, 11, 12SEMXRD, TEMOpticalCrystalline structureMetallograph 7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology8Chapter 1. Introduction7/1/202

8、2College of Materials Science and Engineering, Qingdao University of Science and Technology9Chapter 1. IntroductionClassification of MaterialslMetalslCeramicslPolymerslCompositeslSemiconductorslBiomaterialsImportant Engineering Materials7/1/2022College of Materials Science and Engineering, Qingdao U

9、niversity of Science and Technology10Chapter 1. IntroductionMetalsSeveral uses of steel and pressed aluminum. 7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology11Chapter 1. IntroductionCeramicsExamples of ceramic materials ranging from household to hig

10、h performance combustion engines which utilize both metals and ceramics. 7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology12Chapter 1. IntroductionPolymersPolymers include “Plastics” and rubber materials 7/1/2022College of Materials Science and Engine

11、ering, Qingdao University of Science and Technology13Chapter 1. IntroductionCompositesPolymer composite materials: reinforcing glass fibers in a polymer matrix7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology14Chapter 1. IntroductionSemiconductorsMicr

12、o-Electrical- Mechanical Systems (MEMS)Si wafer for computer chip devices.7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology15Chapter 1. IntroductionBiomaterialsDental biomaterials offer probably the largest range of biomaterials available to a profess

13、ional. 7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology16Chapter 1. IntroductionModern Materials NeedslReducing weight of vehicleslIncrease engine operating temperatureslHigh strength, low density structural materialslSolar cells (convert 15% solar e

14、nergy)lRenewable materials7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology17Chapter 2. Atomic Structure and Interatomic BondingMain contentlAtomic bonding in solidslPeriodic TablelPrimary interatomic bondingslSecondary bondinglMolecules and molecular

15、 solidsEmphasislThe atomic bonding types and atomic Structures7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology182.1 Fundamental ConceptsCharges: Electrons and protons have negative and positive charges of the same magnitude, 1.6 10-19 Coulombs. Neutr

16、ons are electrically neutral. Masses: Protons and Neutrons have the same mass, 1.67 10-27 kg. Mass of an electron is much smaller, 9.11 10-31 kg and can be neglected in calculation of atomic mass. The atomic mass (A) = mass of protons + mass of neutrons protons gives chemical identification of the e

17、lement# protons = atomic number (Z)# neutrons defines isotope number7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology192.1 Fundamental ConceptsThe atomic mass unit (amu) is often used to express atomic weight. 1 amu is defined as 1/12 of the atomic ma

18、ss of the most common isotope of carbon atom that has 6 protons (Z=6) and six neutrons (N=6). Mproton Mneutron = 1.66 x 10-24 g = 1 amu. The atomic mass of the 12C atom is 12 amu.The atomic weight of an element = weighted average of the atomic masses of the atoms naturally occurring isotopes. Atomic

19、 weight of carbon is 12.011 amu. The atomic weight is often specified in mass per mole. A mole is the amount of matter that has a mass in grams equal to the atomic mass in amu of the atoms (A mole of carbon has a mass of 12 grams). The number of atoms in a mole is called the Avogadro number, Nav = 6

20、.023 1023. Nav = 1 gram/1 amu.Example: Atomic weight of iron = 55.85 amu/atom = 55.85 g/mol7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology202.1 Fundamental ConceptsSome simple calculations:The number of atoms per cm3, n, for material of density d (g

21、/cm3) and atomic mass M (g/mol): n = Nav d / MGraphite (carbon): d = 2.3 g/cm3, M = 12 g/mol n = 61023 atoms/mol 2.3 g/cm3 / 12 g/mol = 11.5 1022 atoms/cm3Diamond (carbon): d = 3.5 g/cm3, M = 12 g/mol n = 61023 atoms/mol 3.5 g/cm3 / 12 g/mol = 17.5 1022 atoms/cm3Water (H2O) d = 1 g/cm3, M = 18 g/mol

22、 n = 61023 molecules/mol 1 g/cm3 / 18 g/mol = 3.3 1022 molecules/cm3For material with n = 6 1022 atoms/cm3 we can calculate mean distance between atoms L = (1/n)1/3 = 0.25 nm. the scale of atomic structures in solids a fraction of 1 nm or a few A 7/1/2022College of Materials Science and Engineering,

23、 Qingdao University of Science and Technology212.2 Electrons in Atoms7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology222.2 Electrons in AtomsElectrons move not in circular orbits, but in fuzzy orbits. Actually, we cannot tell how it moves, but only c

24、an say what is the probability of finding it at some distance from the nucleus.Only certain “orbits” or shells of electron probability densities are allowed.The shells are identified by a principal quantum number n, which can be related to the size of the shell, n = 1 is the smallest; n = 2, 3 . are

25、 larger. The second quantum number l, defines subshells within each shell. Two more quantum numbers characterize states within the subshells.7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology232.2 Electrons in AtomsElectron configurationsElectron state

26、s values of energy that are permitted for electronsPaulic exclusion principle stipulates that electron state can hold no more than two electrons, which must have opposite spins. For example, s, p, d, and f subshell can accommodate a total of 2, 6, 10, and 14 electrons respectively.Example: Iron, Z =

27、 26: 1s22s22p63s23p63d64s2Ground state - when all electrons occupy the lowest possible energiesValence electrons - are those that occupy the outermost shell.7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology242.3 The Periodic TableHalogenAlkali MetalIn

28、ert Gas7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology252.3 The Periodic TableElectronegativity - a measure of how willing atoms are to accept electronsSubshells with one electron - low electronegativity Subshells with one missing electron -high ele

29、ctronegativity Electronegativity increases from left to right Metals are electropositive they can give up their few valence electrons to become positively charged ionsElectropositive elements are capable of giving up their few valence electrons to become positive charged ions.Eletronegative elements

30、 are readily to accept electrons to form negatively charged ions.7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology262.4 Bonding Force and EnergiesThis is typical potential well for two interacting atoms The repulsion between atoms, when they are broug

31、ht close to each other, is related to the Pauli principleThe origin of the attractive part, dominating at large distances, depends on the particular type of bonding. repulsionequilibriumattractionPotential Energy, E7/1/2022College of Materials Science and Engineering, Qingdao University of Science a

32、nd Technology272.5 Primary Interatomic BondsPrimary bonding: e- are transferred or shared Strong (100-1000 KJ/mol or 1-10 eV/atom) Ionic bonding: lStrong coulombic interaction among negative atoms (have an extra electron each) and positive atoms (lost an electron). Example - Na+Cl- Covalent: electro

33、ns are shared between the molecules, to saturate the valency. Example - H2 Metallic: the atoms are ionized, loosing some electrons from the valence band. Those electrons form a electron sea, which binds the charged nuclei in place 7/1/2022College of Materials Science and Engineering, Qingdao Univers

34、ity of Science and Technology282.5 Primary Interatomic BondsIonic BondingFormation of ionic bond1. Mutual ionization occurs by electron transfer (remember electronegativity table) Ion = charged atom Anion = negatively charged atom Cation = positively charged atom2. Ions are attracted by strong coulu

35、mbic interaction lOppositely charged atoms attractlAn ionic bond is non-directional (ions may be attracted to one another in any direction7/1/2022College of Materials Science and Engineering, Qingdao University of Science and Technology292.5 Primary Interatomic BondsCovalent BondingIn covalent bonding, electrons are shared between the molecules, to saturate the valency.Formation of covalent bonds: lCooperative sharing of valence electrons lCan be described by orbital overlap lCovalent bonds are HIGHLY directional7/1/2022College of Materials Scienc