Material Science 1-9 PDF

CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 1 Atomic Structure and Bonding Bonding Forces and Energies, Inter-atomic bonds 2 Atomic Structure ▰ Electron ( - ) ▰ Nucleus ▻ Proton ( + ) ▻ Neutron (neutral) 3 Valence Electron ▰ Valence electrons – located at the outer-most shell of the atom ▰ Electrons tend to form pairs for stability ▰ Unpaired electrons tend to gain other electrons from another atom 4 Ionic Bonding ▰ Sodium (Na) ▻ Metal (tends to lose electrons) ▰ Chlorine (Cl) ▻ Non-Metal/Halogen (tend to gain electrons) 5 Ionic Bonding ▰ Sodium (Na) ▻ Metal (tends to lose electrons) ▰ Chlorine (Cl) ▻ Non-Metal/Halogen (tend to gain electrons) 6 Ionic Bonding ▰ Sodium (Na) ▻ Metal (tends to lose electrons) ▰ Chlorine (Cl) ▻ Non-Metal/Halogen (tend to gain electrons) 7 Covalent Bonding ▰ Covalent (Co-valent): means that atoms share electrons to gain stability. 8 Covalent Bonding ▰ Covalent (Co-valent): means that atoms share electrons to gain stability. 9 Covalent Bonding ▰ Covalent (Co-valent): means that atoms share electrons to gain stability. 10 Sample Problem ▰ LiCl ▰ NaF ▰ CO2 ▰ CH4 11 Sample Problem ▰ LiCl – Ionic Bond: Li (+1) and Cl (-1) ▰ NaF ▰ CO2 ▰ CH4 12 Sample Problem ▰ LiCl – Ionic Bond: Li (+1) and Cl (-1) ▰ NaF – Ionic Bond: Na (+1) and F (-1) ▰ CO2 ▰ CH4 13 Sample Problem ▰ LiCl – Ionic Bond: Li (+1) and Cl (-1) ▰ NaF – Ionic Bond: Na (+1) and F (-1) ▰ CO2 – Covalent Bond: C (-4) and O (-2) ▰ CH4 14 Sample Problem ▰ LiCl – Ionic Bond: Li (+1) and Cl (-1) ▰ NaF – Ionic Bond: Na (+1) and F (-1) ▰ CO2 – Covalent Bond: C (-4) and O (-2) ▰ CH4 – Covalent Bond: C (-4) and H (+1) 15 Metallic Bonding ▰ Metals tend to form bonds with each other by collective sharing of delocalized electrons 16 Metallic Bonding ▰ Delocalized electrons gives metals its conductive properties 17 Inter-molecular or Secondary Bonds ▰ Dipole-Dipole Interactions – Occurs when two molecules have polar charges (dipoles) ▰ These charges are weak in general 18 Inter-molecular or Secondary Bonds ▰ Dipole-Dipole Interactions – Occurs when two molecules have polar charges (dipoles) ▰ These charges are weak in general 19 Bonding Forces and Energy 20 Bonding Forces and Energy ▰ Ionic Bonds – Tends to have large bonding energy ▰ Covalent Bonds – Variable but moderate ▰ Metallic Bonds – Variable but moderate ▰ Secondary – Lowest bond energy 21 Bonding Forces and Energy ▰ Elasticity – tendency of material to return to its original shape/form when stress if applied ▰ Stress – Force applied to a material ▰ Strain – deformation caused by stress 22 Bonding Forces and Energy ▰ Elasticity – tendency of material to return to its original shape/form when stress if applied ▰ Stress – Force applied to a material ▰ Strain – deformation caused by stress 23 24 Bonding Forces and Energy Bonding Energies Elastic Modulus ▰ Ionic Bonds – High ▰ Ceramics– High ▰ Covalent – moderate ▰ Crystals – moderate ▰ Metallic – moderate ▰ Metals – moderate ▰ Secondary – Lowest ▰ Polymers – Lowest 25 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 26 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 2.1 Crystalline Structures Properties, Imperfections in Solids 2 Solids ▰ Solid - one of the four fundamental states of matter ▰ The molecules in a solid are closely packed together and contain the least amount of kinetic energy. ▰ A solid is characterized by structural rigidity and resistance to a force applied to the surface. 3 Solids ▰ Solid - one of the four fundamental states of matter ▰ The molecules in a solid are closely packed together and contain the least amount of kinetic energy. ▰ A solid is characterized by structural rigidity and resistance to a force applied to the surface. 4 Crystalline Solids Crystalline Structure ▰ Almost perfect geometric arrangement of molecules (periodic arrangement) 5 Crystalline Solids Crystalline Structure ▰ Almost perfect geometric arrangement of molecules (periodic arrangement) ▰ Can be hard and brittle 6 Crystalline Solids Polycrystalline Structure ▰ Polycrystalline or crystallite is a small or even microscopic crystal which forms, for example, during the cooling of many materials ▰ Has unique strength 7 Crystalline Solids Polycrystalline Structure ▰ Polycrystalline or crystallite is a small or even microscopic crystal which forms, for example, during the cooling of many materials ▰ Has unique strength 8 Crystalline Solids Amorphous solid ▰ Solids that are neither crystalline nor polycrystalline ▰ These have no periodic order 9 Crystalline Solids Amorphous solid ▰ Solids that are neither crystalline nor polycrystalline ▰ These have no periodic order ▰ Easy to break/shatter 10 Examples of Solids Metals ▰ Metals typically are strong, dense, and good conductors of both electricity and heat. ▰ The strength and reliability of metals has led to their widespread use in construction of buildings and other structures ▰ Most metals have crystalline structure, those ions are usually arranged into a periodic lattice 11 Examples of Solids Minerals ▰ Naturally occurring solids formed through various geological processes under high pressures. ▰ Has a crystal structure with uniform physical properties ▰ Has a fairly well defined chemical composition. However, certain crystalline substances with a fixed structure but variable composition 12 Examples of Solids Ceramics ▰ Are composed of inorganic compounds, usually oxides of chemical elements. ▰ They are chemically inert, and often are capable of withstanding chemical erosion that occurs in an acidic or caustic environment. ▰ Ceramics generally can withstand high temperatures ranging from 1,000 to 1,600 °C 13 Examples of Solids Organic Solids ▰ Wood is a natural organic material consisting primarily of cellulose fibers embedded in a matrix of lignin. ▰ The fibers are strong in tension, and the lignin matrix resists compression. ▰ An important construction material since humans began building shelters and packaging (cardboard) 14 Examples of Solids Organic Solids ▰ Polymers are the raw materials (the resins) used to make what are commonly called plastics. ▰ A very workable material. Easy to bend and reshape and has significant strength and elasticity. ▰ include: Nylons in textiles and fabrics, Teflon in non-stick pans, polyvinyl chloride (PVC) in pipes 15 Physical Properties of Solids Mechanical Properties - The mechanical properties of materials describe characteristics such as their strength and resistance to deformation. ▰ Elasticity – When an applied stress is removed, the material returns to its undeformed state. ▰ Plasticity – When an applied stress is removed, the material does not return to its undeformed state but still does not break ▰ Tensile Strength - is the maximum stress that a material can withstand while being stretched or pulled before breaking. ▰ Compressive strength (or compression strength) is the capacity of a material or structure to withstand loads tending to reduce size 16 Physical Properties of Solids ▰ Thermal Properties ▻ Thermal conductivity, which is the property of a material that indicates its ability to conduct heat. ▻ Solids also have a specific heat capacity, which is the capacity of a material to store energy in the form of heat 17 Physical Properties of Solids ▰ Electrical/Magnetic Properties ▻ Electrical conductors such as metals and alloys ▻ Electrical insulators such as glasses and ceramics ▻ Superconductivity: where electrical resistance vanishes and magnetic fields are expelled from the material. 18 Physical Properties of Solids ▰ Optical Properties ▻ Materials can transmit (e.g. glass) or reflect (e.g. metals) visible light. ▻ Optical fibers depend on total internal reflection ▻ Photovoltaic effect - the generation of voltage and electric current in a material upon exposure to light. 19 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 20 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 2.2 Crystalline Structures Imperfections in Solids 2 Solids ▰ Solid - one of the four fundamental states of matter ▰ The molecules in a solid are closely packed together and contain the least amount of kinetic energy. ▰ A solid is characterized by structural rigidity and resistance to a force applied to the surface. 3 Imperfections in Solids ▰ Ideally, there should be a perfect order in this arrangement ▰ However, crystals in nature does not posses perfectly ordered arrangement 4 Imperfections in Solids Imperfection or Defect Any deviation from the perfectly ordered arrangement of atoms or ions in the crystalline structure 5 Imperfections in Solids Causes of Imperfections in Solids ▰ Impurities ▰ Dislocation 6 Types of Defects Point Defects ▰ Point defects are accounted for when the crystallization process occurs at a very fast rate. ▰ When the ideal arrangement of solids is distorted around a point/ atom it is called a point defect. 7 Types of Defects Point Defects ▰ Vacancy defect: When an atom is not present at their lattice sites, then that lattice site is vacant and it creates a vacancy defect. Due to this, the density of a substance decreases 8 Types of Defects Point Defects ▰ Interstitial defect: It is a defect in which an atom or molecule occupies the intermolecular spaces in crystals. In this defect, the density of the substance increases. 9 Types of Defects Point Defects ▰ Frenkel Defect: In ionic solids generally, the smaller ion (cation) moves out of its place and occupies an intermolecular space. In this case, a vacancy defect is created on its original position and the interstitial defect is experienced at its new position. 10 Types of Defects Point Defects ▰ Schottky Defect: This kind of vacancy defects is found in Ionic Solids. But in ionic compounds, we need to balance the electrical neutrality of the compound so an equal number of anions and cations will be missing from the compound. 11 Types of Defects Line Defects ▰ When defect in crystal is centered around a line or the lattice distortion is centered around a line then the type of defect generated is called line defect. ▰ Few reasons of formation of line defects are solidification of solid crystal, plastic deformation of crystals and vacancy condensation. 12 Types of Defects Line Defects ▰ Edge defect causes the nearby lattice structure to distort towards or away from the dislocation line. The displacement distance of atoms around the dislocation line is called Burgers vector and is perpendicular to edge dislocation line. 13 Types of Defects Line Defects ▰ Screw dislocation: Screw dislocation can be formed in a crystal structure by applying upward and downward shear stress to regions of a perfect crystal which have been separated by a cutting plane. In screw dislocation plane of the crystal lattice trace a helical path around the dislocation line. 14 Types of Defects Line Defects ▰ Mechanical properties (such as the strength, ductility, toughness) depend upon the crystal structure and imperfections. ▰ Point defects influence electrical conductivity, mechanical strength, and diffusivity. ▰ Line defects, are relevant in material processing involving solidification, deformation, and powder metallurgy. 15 Types of Defects Semiconductor Doping ▰ Doping is the intentional introduction of impurities into an intrinsic (undoped) semiconductor for the purpose of modulating its electrical, optical and structural properties. 16 Types of Defects Seatwork ▰ Give 5 examples of a material [Concrete] ▰ Explain its most common use [Construction Material] ▰ Describe its Physical Properties (Mechanical, Thermal, Electrical/Magnetic, Optical) [It has no profound optical or electrical properties. Its mechanical property is that it has high compressive strength. Its thermal conductivity is low, making it an effective insulator] ▰ Relate its Physical Property to its Crystalline Structure [Due to its polycrystalline structure, concrete has a relatively high compressive strength] 17 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 18 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 2.3 Crystalline Structures Unit Cell 2 Solids ▰ Solid - one of the four fundamental states of matter ▰ The molecules in a solid are closely packed together and contain the least amount of kinetic energy. ▰ A solid is characterized by structural rigidity and resistance to a force applied to the surface. 3 Unit Cell ▰ A unit cell is the smallest portion of a crystal lattice that shows the three- dimensional pattern of the entire crystal. 4 Unit Cell ▰ A unit cell is the smallest portion of a crystal lattice that shows the three- dimensional pattern of the entire crystal. 5 Unit Cell ▰ A unit cell is the smallest portion of a crystal lattice that shows the three- dimensional pattern of the entire crystal. 6 Unit Cell ▰ Simple Cubic Cell -In each cubic unit cell, there are 8 atoms at the corners. ▰ Therefore, the total number of atoms in one unit cell is 8 × 1/8 = 1 atom. ▰ Coordination No. : 6 7 Unit Cell ▰ A BCC unit cell has atoms at each corner of the cube and an atom at the center of the structure. ▰ Therefore, the total number of atoms in one unit cell is 8 × 1/8 + 1 atom = 2 atom. ▰ Coordination No.: 8 8 Unit Cell ▰ An FCC unit cell contains atoms at all the corners of the crystal lattice and at the center of all the faces of the cube. ▰ Coordination No.: 12 9 Unit Cell ▰ An FCC unit cell contains atoms at all the corners of the crystal lattice and at the center of all the faces of the cube. ▰ Coordination No.: 12 10 Unit Cell ▰ Coordination No.: 12 ▰ a) 8 corners × 1/8 per corner atom = 8 × 1/8 = 1 atom ▰ b) 6 face-centered atoms × 1/2 atom per unit cell = 3 atoms 11 Unit Cell Atomic Packing Factor: ▰ Atomic packing factor (APF), packing efficiency, or packing fraction is the fraction of volume in a crystal structure that is occupied by constituent particles. 12 Unit Cell Atomic Packing Factor: ▰ For Simple Cubic: 13 Unit Cell Atomic Packing Factor: ▰ For Simple Cubic: 14 Unit Cell Atomic Packing Factor: ▰ For Body-Centered Cubic: 15 Unit Cell Atomic Packing Factor: ▰ For Body-Centered Cubic: 16 Unit Cell Atomic Packing Factor: ▰ For Face-Centered Cubic: 17 Unit Cell Atomic Packing Factor: ▰ For Face-Centered Cubic: 18 Unit Cell Crystal Atomic Number of Atomic Packing Density Arrangement Atoms Factor Simple Cubic 1 0.5236 Lowest BCC 2 0.6801 Intermediate FCC 4 0.7404 High 19 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 20 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 3 Diffusion Diffusion in Solids 2 Diffusion Diffusion ▰ The phenomenon of material transport by which atomic diffusion occurs. 3 Diffusion Interdiffusion ▰ Atoms of one metal diffuse into another. ▰ In an alloy, atoms tend to migrate from regions of large concentration. 4 Diffusion 5 Diffusion Self-diffusion ▰ All atoms exchanging positions are of the same type. ▰ In an elemental solid, atoms also migrate. 6 Diffusion Diffusion Mechanism: For an atom to make a move, two conditions must be met ▰ there must be and empty adjacent site ▰ the atom must have suﬃcient energy to break bonds with its neighbor atoms and then cause some lattice distortion during the displacement 7 Diffusion Substitutional Diffusion: ▰ applies to substitutional impurities ▰ atoms exchange with vacancies ▰ rate depends on: --number of vacancies --activation energy to exchange. 8 Diffusion Vacancy Diffusion : ▰ involves the interchange of an atom from a normal lattice position 9 Diffusion Interstitial Diffusion : ▰ Involves the atoms that migrate from an interstitial position to a neighboring one that is empty 10 Diffusion Case Hardening : ▰ Diffuse carbon atoms into the host iron atoms at the surface. ▰ Diffuse carbon atoms into the host iron atoms at the surface. 11 Diffusion Case Hardening : ▰ hard to deform: due to Carbon atoms "lock" planes from shearing. ▰ hard to crack: due to Carbon atoms put the surface in compression. 12 Diffusion Doping: ▰ Doping Silicon with P for n-type semiconductors ▰ Doping is the process of adding some impurity atoms in the semi conductor. ▰ After addition of these dopants some of the properties of the conductors can be changed according to our need. 13 Diffusion Doping: Step 1: Adhesion Step 2: Absorption ▰ Deposit P rich layers on surface (Adhesion: Materials sticks/adheres to the surface of another material) ▰ Heating ▰ Absorption: Materials penetrate inside another materials matrix 14 Diffusion Doping: Step 1: Adhesion Step 2: Absorption ▰ Deposit Phosphorous rich layers on surface (Adhesion: Materials sticks/adheres to the surface of another material) ▰ Heating ▰ Absorption: Materials penetrate inside another materials matrix 15 Diffusion DIFFUSION (FLUX): ▰ Amount of atoms able to penetrate inside the matrix of the material 16 Diffusion DIFFUSION (FLUX): ▰ Amount of atoms able to penetrate inside the matrix of the material 17 Diffusion DIFFUSION (FLUX): ▰ Amount of atoms able to penetrate inside the matrix of the material 18 Diffusion DIFFUSION (FLUX): A plate of iron is exposed to a carburizing (carbonrich) atmosphere on one side and decarburizing (carbon-deﬁcient) atmosphere on the other side at 700oC (1300oF). If a condition of steady state is achieved, calculate the diffusion ﬂux of carbon through the plate if the concentration of carbon at positions of 5 and 10 mm (5 x10-3 and 10-2 m) beneath the carburizing surface are 1.2 and 0.8 kg/m3 , respectively. Assume a diffusion coeﬃcient of 3 x 10-11 m2 /s at this temperature 19 Diffusion DIFFUSION (FLUX): A plate of iron is exposed to a carburizing (carbonrich) atmosphere on one side and decarburizing (carbon-deﬁcient) atmosphere on the other side at 700oC (1300oF). If a condition of steady state is achieved, calculate the diffusion ﬂux of carbon through the plate if the concentration of carbon at positions of 5 and 10 mm (5 x10-3 and 10-2 m) beneath the carburizing surface are 1.2 and 0.8 kg/m3 , respectively. Assume a diffusion coeﬃcient of 3 x 10^-11 m2 /s at this temperature 20 Diffusion Diffusion FASTER for: Diffusion SLOWER for: open crystal structures close-packed structures lower melting T materials higher melting T materials materials w/secondary materials w/covalent bonding bonding smaller diffusing atoms larger diffusing atoms cations anions lower density materials higher density materials 21 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 22 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 4 MECHANICAL PROPERTIES Mechanical Properties of Solids 2 MECHANICAL PROPERTIES ISSUES TO ADDRESS... Stress and strain: What are they and why are they used instead of load and deformation? Elastic behavior: When loads are small, how much deformation occurs? What materials deform least? Plastic behavior: At what point do dislocations cause permanent deformation? What materials are most resistant to permanent deformation? Toughness and ductility: What are they and how do we measure them? 3 Thanks for Listening 4 Thanks for Listening 5 Thanks for Listening 6 Thanks for Listening 7 Thanks for Listening 8 Thanks for Listening 9 Thanks for Listening 10 Thanks for Listening 11 Thanks for Listening 12 Thanks for Listening 13 Thanks for Listening 14 Thanks for Listening 15 Thanks for Listening 16 Thanks for Listening 17 Thanks for Listening 18 Thanks for Listening 19 Thanks for Listening 20 Thanks for Listening 21 DUCTILITY Thanks for Listening 22 Thanks for Listening 23 MECHANICAL PROPERTIES Stress and strain: These are size-independent measures of load and displacement, respectively. Elastic behavior: This reversible behavior often shows a linear relation between stress and strain. To minimize deformation, select a material with a large elastic modulus (E or G). Plastic behavior: This permanent deformation behavior occurs when the tensile (or compressive) uniaxial stress reaches Toughness: The energy needed to break a unit volume of material. Ductility: The plastic strain at failure. 24 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 25 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 4.5 MECHANICAL PROPERTIES Mechanical Properties of Solids 2 Thanks for Listening 3 Thanks for Listening 4 Thanks for Listening 5 Thanks for Listening 6 Thanks for Listening 7 Thanks for Listening 8 Thanks for Listening 9 Thanks for Listening 10 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 11 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 5 PHASE DIAGRAMS Phase Changes, Effects of Temperature and Pressure 2 PHASE DIAGRAMS Phase Change/Transition Phase transition is when a substance changes from a solid, liquid, or gas state to a different state. Every element and substance can transition from one phase to another at a speciﬁc combination of temperature and pressure. 3 PHASE DIAGRAM There are two variables to consider when looking at phase transition, pressure (P) and temperature (T). For the gas state, The relationship between temperature and pressure is deﬁned by the equation PV = nRT 4 PHASE DIAGRAM Temperature can change the phase of a substance. One common example is putting water in a freezer to change it into ice. In the picture above, we have a solid substance in a container. When we put it on a heat source, like a burner, heat is transferred to the substance increasing the kinetic energy of the molecules in the substance. 5 PHASE DIAGRAM Melting point ▰ Each substance has a melting point. The melting point is the temperature that a solid will become a liquid. At different pressures, different temperatures are required to melt a substance. Each pure element on the periodic table has a normal melting point, the temperature that the element will become liquid when the pressure is 1 atmosphere. Boiling Point ▰ Each substance also has a boiling point. The boiling point is the temperature that a liquid will evaporate into a gas. The boiling point will change based on the temperature and pressure. Just like the melting point, each pure element has a normal boiling point at 1 atmosphere. 6 PHASE DIAGRAM Pressure can also be used to change the phase of the substance. In the picture above, we have a container ﬁtted with a piston that seals in a gas. As the piston compresses the gas, the pressure increases. Once the boiling point has been reached, the gas will condense into a liquid. 7 PHASE DIAGRAM Thanks for Listening 8 PHASE DIAGRAM Triple point – the point on a phase diagram at which the three states of matter: gas, liquid, and solid coexist Critical point – the point on a phase diagram at which the substance is Thanks for Listening indistinguishable between liquid and gaseous states Fusion(melting) (or freezing) curve – the curve on a phase diagram which represents the transition between liquid and solid states Vaporization (or condensation) curve – the curve on a phase diagram which represents the transition between gaseous and liquid states Sublimation (or deposition) curve – the curve on a phase diagram which represents the transition between gaseous and solid states 9 Sublimation - is when the substance goes directly from solid to the gas state. Deposition - occurs when a substance goes from a gas state to a solid state; it is the reverse process of sublimation. Melting - occurs when a substance goes from a solid to a liquid state. Fusion - is when a substance goes from a liquid to a solid state, the reverse of melting. Thanks for Listening Vaporization - (or evaporation) is when a substance goes from a liquid to a gaseous state. Condensation - occurs when a substance goes from a gaseous to a liquid state, the reverse of vaporization. Critical Point – the point in temperature and pressure on a phase diagram where the liquid and gaseous phases of a substance merge together into a single phase. Beyond the temperature of the critical point, the merged single phase is known as a supercritical ﬂuid. Triple Point occurs when both the temperature and pressure of the three phases of the substance coexist in equilibrium. 10 Thanks for Listening 11 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 12 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 5.5 PHASE DIAGRAMS Phase Changes, Effects of Temperature and Pressure 2 Thanks for Listening 3 PHASE DIAGRAM Using the phase diagram, try to predict the phase of a certain material Example - Water: 1. 1 atm and 293.15K 2. from this temperature, lower the pressure to 0.005 atm 3. From this pressure, lower the temperature to 263.15K 4. From this temperature, increase pressure to 300 atm 5. From this pressure, increase the temperature to 700K 4 PHASE DIAGRAM Clausius-Clapeyron ▰ Apply the Clausius-Clapeyron equation to estimate the vapor pressure at any temperature. ▰ Estimate the heat of phase transition from the vapor pressures measured at two temperatures. ▰ Heat of Phase Transition – Energy required to change the phase of a material 5 PHASE DIAGRAM Sample Problems: 1. The heat of vaporization of hexane is 30.8 kJ. mol-1. The boiling temperature of hexane at a pressure of 1.00 atm is 68.9˚C. What will the boiling temperature be at a pressure of 0.50 atm? [ans: 48.85˚C] R = 8.314 J/K 2. The vapor pressure of water is 1.0 atm at 373 K, and the enthalpy of vaporization is 40.7 kJ mol. Predict the vapor pressure (boiling pressure) at temperature 363 and 383 K respectively [ans:1.4 atm] R = 8.314 J/K 3. The vapor pressures of ice at 268 K and 273 K are 2.965 and 4.560 torr respectively. Estimate the energy required for sublimation of ice. [ans: 52,370 J/mol] 6 Using the phase diagram, try to predict Sample Problems: the phase of a certain material The vapor pressure of ethanol is 115 torr at Example - Water: 34.9 ˚C. If Heat of vaporization of ethanol is 1. 7 atm and 700K 40.5 kJ/mol, calculate the temperature (in ˚C) when the vapor pressure is 760 torr. [ans: 77C] 2. 1.2 atm and 380K 3. From this pressure, lower theThanks for Listening temperature to 100K 4. 260K and 0.005 atm 5. From this temperature, increase the pressure to 300 atm 7 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 8 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 6 ELECTRICAL PROPERTIES Conductors, Semiconductors, Insulators 2 Electrical Properties Valence Electrons: Valence electrons are the electrons in the outermost shell, or energy level, of an atom. Octet Rule: The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell 3 Electrical Properties In solids, the molecules are closely arranged together, due to this atoms of molecules tend to move into the orbitals of neighboring atoms. Hence, the electron orbitals overlap when atoms come together. In solids, several bands of energy levels are formed due to the intermixing of atoms in solids. We call these set of energy levels as energy bands. 4 Electrical Properties Conduction Band The free electrons conduct current in conductors and are therefore known as conduction electrons. The conduction band is one that contains conduction electrons and has the lowest occupied energy levels. 5 Electrical Properties Valence Bond The electrons in the outermost shell are known as valence electrons. These valence electrons contain a series of energy levels and form an energy band known as the valence band. The valence band has the highest occupied energy. 6 Electrical Properties Conductors Gold, Aluminum, Silver, Copper, all these metals allow an electric current to ﬂow through them. There is no band gap between the valence band and conduction band which results in the overlapping of both the bands. The number of free electrons available at room temperature is large.. 7 Electrical Properties Insulators Glass and wood are examples of the insulator. These substances do not allow electricity to pass through them. They have high resistivity and very low conductivity. The energy gap in the insulator is very high up to 7eV. The material cannot conduct because the movement of the electrons from the valence band to the conduction band is not possible.. 8 Electrical Properties Semiconductors Germanium and Silicon are the most preferable material whose electrical properties lie in between semiconductors and insulators. 9 Electrical Properties Metallic Bonding: Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons and positively charged metal ions. Electrical Conductivity of Metals: Metallic substances have high electrical conductivity because of the continuous electron cloud present in the metallic bond. 10 Electrical Properties Metallic Bonding: Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons and positively charged metal ions. Electrical Conductivity of Metals: Metallic substances have high electrical conductivity because of the continuous electron cloud present in the metallic bond. 11 Electrical Properties Electrical properties of semiconductors are unique, in the sense that their electrical properties are extremely sensitive to even minute concentrations of impurities. Two kinds of semiconductors – intrinsic and extrinsic. For intrinsic semiconductors, their electrical behavior is based on inherent electronic structure of the pure material. On the other hand, if the electrical properties are dominated by impurities, they are called extrinsic semiconductors. In semiconductors, the valence and conduction bands do not overlap as in metals, but they possess enough electrons in the valence band those can be promoted to the conduction band at a certain temperature. 12 Electrical Properties 13 Electrical Properties 14 Electrical Properties Intrinsic semiconduction Conduction is due to promoted electrons, and charged hole left behind by these electrons. This occurs at elevated temperatures. At still higher temperatures, the concentration of thermally excited electrons in the conduction band becomes so high that the semiconductor behaves more like a metal. 15 Electrical Properties Extrinsic semiconduction The charge carrier density can also be increased by adding impurities of either higher or lower valence to intrinsic semiconductors. This addition of impurities is known as doping, and impure atoms in the element are called donor atoms. n-type semiconductor uses higher valence elements as donors, while p-type semiconductors uses lower valence elements. Donor atoms increases number of charge carriers in form negatively charged electrons (n-type) or positively charged holes (p-type). Doping also results in altering the Fermi energy level, and its exact position is a function of both temperature and donor concentration. 16 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 17 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 6.5 ELECTRICAL PROPERTIES Conductors, Semiconductors, Insulators 2 Electrical Properties 3 Electrical Properties R = p L/A Material Resistivity (p) P = resistivity Silver 1.59×10−8 Copper 1.68×10−8 L = length Gold 2.44×10−8 A = Cross-sectional area Aluminum 2.65×10−8 Tungsten 5.60×10−8 Platinum 10.6×10−8 Iron 9.70×10−8 Nickel 6.99×10−8 4 Electrical Properties 1. What is the resistance of a copper wire that is 3.5m long and has a diameter of 2.0mm? R = p L/A P = 1.68 x 10^-8 ohm-m (copper) R = (1.68 x 10^-8 ohm-m)(3.5 / (π)(0.001)^2 R = 0.0187 ohm 5 Electrical Properties 2. A car headlight ﬁlament is made of tungsten and has a resistance of 0.350 Ω. If the ﬁlament is a cylinder 4.00 cm long (it may be coiled to save space), what is its diameter? R = p L/A R = 0.350 ohms P = 5.60 x 10^-8 ohm-meters (tungsten L = 4 cm = 0.04m A = p L/R A = (5.60 x 10^-8 ) (0.04) / 0.350 A = ¼ π d^2 6.4 x 10^-9 = ¼ π d^2 = 9.0270 x 10 ^-5 m 6 Electrical Properties RT = R0 [1+ α (T-T0)] Material Temp Coefficient (p) RT = Resistance at Silver 0.003819 Temperature Copper 0.004041 R0 = Resistance at reference Gold 0.003715 temperature Aluminum 0.004308 α = Temperature coefficient Tungsten 0.004403 T= Temperature Platinum 0.003729 T0 = Temperature Reference Iron 0.005671 Nickel 0.005866 7 Electrical Properties A platinum resistance thermometer uses the change in R to measure temperature. Suppose R0 = 50 Ω at T0=20 ºC. α for Pt is 3.92×10-3 (ºC)-1 in this temperature range. What is R when T = 50.0 ºC? RT = R0 [1+ α (T-T0)] RT = (50 Ω) [1+ (0.00392) (50-20)] RT = 55.88 Ω 8 Electrical Properties A silver wire has a resistance of 1.25 ohm at 0 degree Celsius and the temperature coeﬃcient of resistance of 0.00375 per degree Celsius. To what temperature must the wire be raised to double the resistance? RT = R0 [1+ α (T-T0)] 2.50 Ω = (1.25 Ω) [1+ (0.00375) (T-0)] T = 266.66 Ω 9 Electrical Properties 1. An electrician wishes to cut a copper wire (ρ=1.724∗10−8Ωm) that has no more than 10Ω of resistance. The wire has a radius of 0.725mm. Approximately what length of wire has a resistance equal to the maximum 10Ω ? 2. Calculate the resistivity of a material with a resistance of 2 ohms and a cross-sectional area and length of 25 cm2 and 15 cm, respectively. 3. The length and area of wire are given as 0.2 m and 0.5 m2 respectively. The resistance of that wire is 3 Ω, calculate the resistivity? 4. An experiment uses platinum electrode for electroplating and has a resistance of 0.350 Ω. If the platinum electrode is a cylindrical tube 4.00 cm long, what is its diameter? 5. What is the resistance of a gold electrode that is 21 m long and has a diameter of 3.0 mm? 6. A tungsten ﬁlament has a resistance of 133 ohm at 150 degree Celsius. If a= 0.0045/C what is the resistance of the ﬁlament at 500 degree Celsius? 7. A tungsten wire has a resistance of 7.8 ohm at 10 degree Celsius and the temperature coeﬃcient of resistance of 0.004403 per degree Celsius. To what temperature must the wire be raised to double the 10 resistance? Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 11 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 7 THERMAL PROPERTIES Linear and Volumetric Expansion 2 Electrical Properties Thermal expansion is the tendency of matter to increase in length, area, or volume, changing its size and density, in response to an increase in temperature. 3 Electrical Properties ΔL = (a)(Li )(Δt) ΔL = (b)(Li )(Δt) ΔL = change in length (linear) ΔL = change in length (linear) a = coeﬃcient of linear expansion b = coeﬃcient of volumetric expansion Li = Initial Length of the material Vi = Initial volume of the material (Δt) = change in temperature (Δt) = change in temperature 4 Electrical Properties Material Linear Expansion Coefficient Volumetric Expansion Coefficient Aluminum 25 × 10– 6 75 × 10– 6 Bronze 19 × 10– 6 56 × 10– 6 Copper 17 × 10– 6 51 × 10– 6 Gold 14 × 10– 6 42 × 10– 6 Iron 12 × 10– 6 35 × 10– 6 Silver 18×10−6 54×10−6 Glass 9 × 10– 6 27 × 10– 6 Water - 210 × 10– 6 5 Gasoline - 950 × 10– 6 Electrical Properties LRT Line 1 extension connects Monumento station to Roosevelt station in north EDSA at a distance of 5.7 km. Due to temperature swings in the monsoon season, the rail tracks can experience temperatures ranging from 20 °C to 50 °C. What is its change in length between these temperatures? Assume that the bridge is made entirely of steel. ΔL=αLΔT ΔL =(12×10−6°C)(5700m)(30°C) ΔL =2.052m 6 Electrical Properties The main span of San Francisco’s Golden Gate Bridge is 1275 m long at its coldest. The bridge is exposed to temperatures ranging from –15°C to 40°C. What is its change in length between these temperatures? Assume that the bridge is made entirely of steel. ΔL=αLΔT ΔL =(12×10−6°C)(1275m)(55°C) ΔL =0.84m 7 Electrical Properties A 30cm cube of silver, gold and bronze is put in a high temperature annealing oven at a temperature of 360 °C from 25 °C. It is expected that all material will expand slightly – calculate this expansion ΔV=bViΔT Silver: ΔV=bViΔT = (54×10−6) (30cm^3) (335 °C) = 0.5427 cm^3 Gold: ΔV=bViΔT = (42 × 10– 6) (30cm^3) (335 °C) = 0.4221 cm^3 Bronze: ΔV=bViΔT = (56 × 10– 6) (30cm^3) (335 °C) = 0.5628 cm^3 8 Electrical Properties 1. San Juanico bridge is 2164 meters long and is connected to land by a movable interlocking mechanism to prevent damage from thermal expansion. Due to temperature swings in the monsoon season, the bridge can experience temperatures ranging from 20 °C to 50 °C. What is its change in length between these temperatures that the interlock has to compensate? Assume that the bridge is made entirely of steel. 2. If the San Juanico bridge was somehow made of aluminum, how much longer/shorter the interlock must be? 3. A 55cm cube of copper, iron and aluminum is put in a high temperature annealing oven at a temperature of 500 °C from 35 °C. It is expected that all material will expand slightly – calculate this expansion 4. A water and gasoline container is stored in a 250 cm^3 steel can behind a pickup truck. Since the temperature in the truck ranges from -10 °C to 45 °C, both the steel can is warped due to thermal expansion of the ﬂuid inside. How much larger should the volume of the containers be in order to 9 prevent warping? Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 10 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 8 CORROSION Corrosion and Material Degradation 2 Electrical Properties Corrosion is a natural process that converts a reﬁned metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. 3 Electrical Properties Rusting, the formation of red-orange iron oxides, is a well-known example of electrochemical corrosion. Galvanic corrosion occurs when two different metals have physical or electrical contact with each other and are immersed in a common electrolyte, or when the same metal is exposed to electrolyte with different concentrations. 4 Electrical Properties Basic “rusting” or corrosion requirements 1.The metal is oxidized at the anode of an electrolytic cell 2. Some ions are reduced at the cathode 3. There is a potential or voltage difference between the anode and cathode 4. An electrolyte (ﬂuid) must be present 5. The electrical path must be completed 5 Electrical Properties Basic “rusting” or corrosion factors ▰ Metallurgical composition ▰ Passivity / Activity of metal or element ▰ Environment Conditions ▰ Cold Work ▰ Non-Uniform Stresses 6 Electrical Properties Forms of Corrosion ▰ Uniform Attack Oxidation & reduction occur uniformly over surface. ▰ Selective Leaching Preferred corrosion of one element/constituent ▰ Intergranular Corrosion along grain boundaries, often where special phases exist. ▰ Galvanic Dissimilar metals are physically joined. The more anodic one corrodes. ▰ Stress corrosion Stress & corrosion work together at crack tips. ▰ Pitting Downward propagation of small pits & holes. 7 Electrical Properties 8 Electrical Properties Corrosion Penetration Rate The corrosion penetration rate (CPR) is deﬁned as: The speed at which any metal in a speciﬁc environment deteriorates due to a chemical reaction in the metal when it is exposed to a corrosive environment. CPR = (k x W) / (D x A x T) ▰ where k = a constant ▰ W = total weight lost ▰ T = time taken for the loss of metal ▰ A = the surface area of the exposed metal ▰ D = the metal density in g/cm³ 9 Electrical Properties Sample Problems A piece of corroded steel plate was found in a submerged ocean vessels. It was estimated that the original area of the plate was 10m^2 and that approximately 2.6 kg has corroded away during the submersion. Assuming the CPR of this material is 200 mpy for this alloy in seawater. Estimate the time of submersion in years. The density of steel is 7.9 g/cm^3. The corrosion constant for steel is 536 CPR = (k x W) / (D x A x T) T = (k x W) / (D x A x CPR) T = (536 x 2.6kg) / (7.9kg/m^3 x 10m^2 x 200 m/yr) T = 0.088 years 10 Electrical Properties Sample Problems A steel sheet of area 100m^2 is exposed to air neat the ocean. After 1 year period it was found to experience a weight loss of 0.485kg dues to corrosion and density of the steel material is 7.9 kg/m^3. Calculate the CPR if the corrosion constant for steel is 536 CPR = (k x W) / (D x A x T) CPR = (536 x 0.485kg) / (7.9 kg/m^3 x 100m^2 x 1 yr) CPR = 0.3290 mpy 11 Electrical Properties Seatwork Problems A steel sheet of area 3000m^2 is exposed to seawater. After 2 year period it was found to experience a weight loss of 1.5586kg dues to corrosion and density of the steel material is 7.9 kg/m^3. Calculate the CPR if the corrosion constant for steel is 536 A piece steel plate was found in a train track near an airport. It was estimated that the original area of the plate was 78m^2 and that approximately 1.446 kg has corroded away during the submersion. Assuming the CPR of this material is 200 mpy for this alloy in seawater. Estimate the time of submersion in years. The density of steel is 7.9 g/cm^3. The corrosion constant for steel is 536 An aluminum sheet of area 1500m^2 is exposed to caustic chemicals. After 3.5 year period it was found to experience a weight loss of 1.5586kg dues to corrosion and density of the steel material is 2.7 kg/m^3. Calculate the CPR if the corrosion constant for steel is 677 Galvanized steel is used for a storage tank of sulfuric acid – a corrosive liquid has a surface area of 2400m^2. After 10 year period it was found to experience a weight loss of 45.77kg dues to corrosion and density of the steel material is 7.85 kg/m^3. Calculate the CPR if the corrosion constant for steel is 1540 12 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 13 CHEM 004 – Material Science and Engineering Department of Environmental and Sanitary Engineering Technological Institute of the Philippines – Q.C Engr. Andrey Joshua Antiporta - Presentor 8 OPTICAL PROPERTIES Corrosion and Material Degradation 2 OPTICAL PROPERTIES The optical properties of materials describe how they interact with light. These properties are essential in various applications, including in lenses, ﬁbers, coatings, and displays. 3 OPTICAL PROPERTIES Refraction Refraction occurs when light passes from one medium into another and its speed changes, causing it to bend. The amount of bending is determined by the refractive index of the material, which is a measure of how much the material slows down light compared to a vacuum. 4 OPTICAL PROPERTIES Refraction The refractive index (also known as the index of refraction) is a dimensionless number that describes how light (or any other wave) propagates through a medium. 5 OPTICAL PROPERTIES Refractive Index: N = refractive index of the material. C = speed of light in a vacuum V = speed of light in the material 6 OPTICAL PROPERTIES Example: Suppose the speed of light in water is v=2.25×108 m/s. We can calculate the refractive index of water using the formula: 7 OPTICAL PROPERTIES Example: Let's say the refractive index of a piece of glass is n=1.5, and we want to ﬁnd the speed of light inside the glass. 8 OPTICAL PROPERTIES Snell's Law relates the angles of incidence and refraction to the refractive indices of the two media involved. It is given by the equation: 9 OPTICAL PROPERTIES Example: Refractive index of air n1=1.00 Refractive index of water n2=1.33 Angle of incidence θ1=30° We want to ﬁnd the angle of refraction θ2 10 OPTICAL PROPERTIES Example: Refractive index of air n1=1.5 Refractive index of water n2=1.0- Angle of incidence θ2=45° We want to ﬁnd the angle of refraction θ1 11 OPTICAL PROPERTIES Reﬂection: Reﬂection occurs when light bounces off the surface of a material. The angle at which light strikes the surface (angle of incidence) is equal to the angle at which it is reﬂected (angle of reﬂection). Materials with high reﬂective properties (such as mirrors) can reﬂect most of the light that hits them, whereas materials like black paper absorb more light and reﬂect very little. 12 OPTICAL PROPERTIES Absorption refers to the process where light is absorbed by a material, converting the light energy into other forms, usually heat. Materials that absorb more light appear darker in color. 13 OPTICAL PROPERTIES Dispersion occurs when different wavelengths (colors) of light are refracted by different amounts as they pass through a material. This is why a prism can split white light into a spectrum of colors. Different wavelengths of light is visible as different colors 14 OPTICAL PROPERTIES Transmission is the ability of a material to allow light to pass through it. Materials can be transparent (allowing light to pass through with minimal distortion), translucent (allowing some light through but diffusing it), or opaque (not allowing any light to pass through). 15 OPTICAL PROPERTIES Seatwork Problems 1. A light ray traveling in air (n₁ = 1.00) strikes the surface of water (n₂ = 1.33) at an angle of incidence of 30°. What is the angle of refraction in the water? 2. A beam of light in a glass prism (n₁ = 1.50) strikes the surface of air (n₂ = 1.00) at an angle of incidence of 45°. Find the angle of refraction as the light exits the glass and enters the air. 3. A light ray traveling from water (n₁ = 1.33) enters a medium with an unknown refractive index, and the angle of refraction is 15° when the angle of incidence is 30°. What is the refractive index of the unknown medium? 4. A light ray travels from air (n₁ = 1.00) into a glass block with a refractive index of 1.5. If the angle of incidence is 40°, calculate the angle of refraction in the glass. 5. A ray of light is moving from air (n₁ = 1.00) into a diamond (n₂ = 2.42) with an angle of incidence of 60°. What is the angle of refraction in the diamond? 16 Thanks for Listening CHEM 004 – Material Science and Engineering Lecture 17

Material Science 1-9 PDF

Document Details

Tags

Related

Summary

Full Transcript

Upgrade to continue