MSE Finals PDF - Materials Science and Engineering

Materials Science and Engineering Finals Study online at https://quizlet.com/_g5pa86 Corrosion Destructive electrochemical attack on metals. Oxidation Loss of electrons from a metal atom....

Materials Science and Engineering Finals Study online at https://quizlet.com/_g5pa86 Corrosion Destructive electrochemical attack on metals. Oxidation Loss of electrons from a metal atom. Reduction Gain of electrons by a species. Galvanic Couple Two metals connected in electrolyte causing corrosion. Standard Half-Cell Reference electrode for comparing metal half-cells. Standard Hydrogen Electrode Reference electrode using hydrogen gas at 1 atm. Electrode Potential Voltage indicating tendency to oxidize or reduce. Electrochemical Mechanism Processes governing oxidation and reduction reactions. Corrosion Prevention Strategies to mitigate material degradation. Metal Oxidation Rate Speed at which metals corrode in environments. Corrosion Penetration Rate (CPR) Rate of material loss due to corrosion, mpy or mm/yr. Calculates cell potential considering concentration and tempera- Nernst Equation ture. EMF Series Ranks metals by their electromotive force. Galvanic Series Ranks metals by reactivity in seawater. Current Density Current per unit area affecting corrosion rate. Overvoltage (·) Displacement of electrode potential from equilibrium. Spontaneity of Reaction Reaction occurs if overall potential difference is positive. Active Polarization High Hz concentration near electrode, no diffusion limit. Destructive Attack Unintentional damage to metals, often electrochemical. Corrosion Rates Measure of how quickly materials degrade. Electrodeposition Process where metal ions are reduced and deposited. Half-Cell Potentials Indicate equilibrium conditions, not actual corrosion rates. Reactivity Tendency of metals to undergo oxidation. Weight Loss Material loss measured over time due to corrosion. Density Mass per unit volume of a material. Surface Area Exposed area of a material affecting corrosion. Electrochemical Reactions Reactions involving transfer of electrons. Faraday Constant 96,500 C/mol, relates charge to moles of electrons. Concentration Polarization Diffusion of Hz ions limits the reaction rate. Passivity Metals become inert due to protective oxide film. Uniform Corrosion Electrochemical corrosion occurs uniformly on surfaces. Galvanic Corrosion Corrosion occurs between electrically coupled dissimilar metals. Pitting Corrosion Localized corrosion forms small pits or holes. Crevice Corrosion Corrosion in stagnant areas with lower ion concentration. Intergranular Corrosion Corrosion along grain boundaries of alloys. Selective Leaching One element preferentially removed from solid solution alloys. Erosion-Corrosion Corrosion from chemical attack and mechanical abrasion. Stress Corrosion Cracking Cracking due to tensile stress and corrosive environment. Hydrogen Embrittlement Reduction in ductility from atomic hydrogen penetration. Cathodic Protection Prevention technique converting metal into a cathode. Galvanic Protection Uses sacrificial anode to protect metal. Impressed Current External DC source supplies electrons for protection. Pilling-Bedworth Ratio Determines protective nature of oxide film. 1/6 Materials Science and Engineering Finals Study online at https://quizlet.com/_g5pa86 P-B Ratio < 1 Porous oxide film, unprotective. P-B Ratio = 1 Stable and protective oxide film. P-B Ratio > 1 Dense and protective oxide film. Corrosion of Ceramic Materials Ceramics resist corrosion due to stable structure. Ozone-induced Chain Scission Ozone reacts with double bonds, causing degradation. Weathering Degradation of materials due to outdoor exposure. Thermal Degradation Molecular chain scission at elevated temperatures. Water Absorption Polymer resilience against decomposition influenced by bonds. Thermal Stability Resistance to degradation from thermal effects. Environmental Effects Factors influencing corrosion rates include temperature. Fluid Velocity Increased velocity typically raises corrosion rates. Corrosive Concentration Higher concentration can increase or decrease corrosion. Ferrous Metals Metals containing iron, prone to corrosion. Non-Ferrous Metals Metals without iron, resistant to rust. Electromotive Force (EMF) Voltage measure indicating oxidation tendencies. Low-Carbon Steel Contains less than 0.25 wt.% carbon. Medium-Carbon Steel Contains 0.25-0.60 wt.% carbon. High-Carbon Steel Contains 0.60-1.4 wt.% carbon, very strong. High-Strength Low-Alloy Steel Stronger than low-carbon steels, more corrosion-resistant. Tool Steels High-carbon alloys for cutting and shaping materials. Stainless Steels Corrosion-resistant, with at least 11 wt.% chromium. Heating Treatment Process to enhance metal properties through heat. Mechanical Properties Characteristics like strength, ductility, and toughness. Deteriorative Process Degradation of materials due to environmental factors. Carbon Concentration Influences mechanical properties of steel. Voltage Measurement Indicates driving force for electrochemical reactions. Malleability Ability to be shaped without breaking. Fusibility Ability to be melted and shaped. Environmental Impact Effects of surroundings on material integrity. Preventive Measures Strategies to mitigate material degradation. Mechanical Strength Resistance to deformation under applied forces. Corrosion Resistance Enhanced by nickel and molybdenum additions. Martensitic Stainless Steels Heat treatable with martensite as prime microconstituent. Ferritic Stainless Steels Composed of ±- ferrite (BCC) phase, magnetic. Austenitic Stainless Steels Non-magnetic, high corrosion resistance, widely produced. Cathodic Metals Less reactive, include noble metals like gold. Anodic Metals More reactive, include base metals like zinc. Gray Iron Weak and brittle in tension, strong in compression. Ductile Iron Nodular graphite improves strength and ductility. White Iron Hard, brittle; carbon exists as cementite. Malleable Iron Decomposes cementite, forms graphite clusters. Compacted Graphite Iron Graphite has worm-like shape, enhanced properties. Corrosion Rate Formula CPR = W/(Á AtK), units in mpy or mm/yr. 2/6 Materials Science and Engineering Finals Study online at https://quizlet.com/_g5pa86 Beryllium Coppers Heat-treatable, high strength, used in aerospace. Brasses Copper-zinc alloys, commonly used in applications. Bronzes Copper with tin, aluminum, or nickel. Overvoltage Measured in volts, affects reaction rates. Aluminum Alloys Used in aircraft parts and automotive components. Ductility Ability to be easily formed, like aluminum foil. Melting Temperature Aluminum's melting point is 660°C. Principal Alloying Elements Includes copper, magnesium, silicon, manganese, zinc. Cast Alloys Aluminum alloys formed by pouring into molds. Wrought Alloys Aluminum alloys shaped by mechanical processes. Magnesium Alloys Lightweight, used in aerospace and missile applications. Corrosion Process One element removed, impairing mechanical properties. Titanium Properties Low density (4.5 g/cm³), high melting point (1668°C). Tensile Strength Titanium alloys can reach 1400 MPa at room temperature. Refractory Metals Withstand high temperatures (2468°C to 3410°C). Noble Metals Expensive metals with oxidation resistance properties. Ceramics Compounds resistant to corrosion, stable structure. Chain Scission Molecular chains severed by ozone, causing degradation. Lead and Tin Alloys Mechanically weak, low melting points, corrosion-resistant. Unalloyed Zinc Soft, low melting temperature, corrosion-susceptible. Zirconium Alloys Excellent mechanical properties, corrosion-resistant. Oxide Film Protective layer formed during oxidation processes. Corrosion Mechanisms Involve chemical dissolution, different from metals. Mechanical Abrasion Erodes protective films, exposing bare metal. Chemical Agents Oxygen and ozone accelerate rubber degradation. Forming Operations Processes changing metal shape through plastic deformation. Forging Mechanically deforming hot metal with blows or squeezing. Closed Die Forging Force applied to die halves for metal deformation. Open Die Forging Uses simple dies for large workpieces. Rolling Metal passage between rolls reduces thickness. Cold Rolling Produces high-quality sheet and foil surfaces. Extrusion Forcing metal through a die to shape it. Drawing Pulling metal through a tapered die to elongate. Casting Pouring molten metal into a mold to solidify. Sand Casting Common method using sand molds for casting. Die Casting Forcing liquid metal into molds under pressure. Lost Foam Casting Vaporizes foam pattern to create a mold. Continuous Casting Solidifying molten metal into large ingots continuously. Powder Metallurgy Compacting metal powder and heat treating it. Welding Joining metals through metallurgical bonding. Heat Treatment Process to enhance material properties and strength. Annealing Heating and slowly cooling to relieve stresses. Normalizing Refines grains, heating above critical temperature. Hardening Heating and rapid cooling to increase hardness. 3/6 Materials Science and Engineering Finals Study online at https://quizlet.com/_g5pa86 Ageing Enhancing yield strength through particle distribution. Stress Relieving Reduces internal stresses in metal components. Tempering Heating quenched steel to reduce brittleness. Case Hardening Surface hardening to improve wear resistance. Carburizing Increasing carbon content on steel surface. Cyaniding Hardening low carbon steel in cyanide bath. Nitriding Diffusing nitrogen into steel surface at high temperatures. Traditional Ceramics Includes pottery, one of the oldest technologies. Earthenware Low-fired pottery, porous and coarse. Stoneware High-fired pottery, non-porous and durable. Porcelain Fine china made from kaolin and minerals. Polarization Change in potential due to current flow. Sintering Firing ceramic components to fuse them together. Advanced Ceramics Ceramics based on oxides or non-oxides. Vitrification Process of turning materials into glass-like state. Glaze Finely ground glass coating on ceramics. Cement Systems Materials used in construction, can be ceramic-based. Electromotive Force (emf) Voltage generated by a galvanic cell. Half-Cell Electrode in electrochemical cell contributing to reactions. Standard Electrode Potentials Measure of voltage for half-reactions in cells. Bioceramics Materials like alumina and zirconia for medical implants. Ceramic Bonding Interactions between atoms in ceramic materials. Spontaneous Reaction Occurs when cell potential (”V) is positive. Covalent Bonding Sharing of electron pairs between nonmetals. Ionic Bonding Electrostatic attraction between oppositely charged ions. Metallic Bonds Bonding with free-moving electrons in metals. Ionic Crystals Close-packed structure of anions with cations. Cations Positively charged metallic ions. Anions Negatively charged nonmetallic ions. Half-cell Potentials Equilibrium conditions for corrosion analysis. Corrosion Rate (CPR) Rate of material loss due to corrosion. Weight Loss Formula W = Á ×A × K × t. Coordination Number Number of surrounding atoms or ions. Protective Oxide Film Thin layer that reduces metal reactivity. Electrochemical Corrosion Corrosion from ion concentration differences. Grain Boundary Corrosion Corrosion along the boundaries of grains. Sensitization Heating stainless steels causing corrosion susceptibility. Diffusion Limitation Mass transport limits reaction rates. Activation Energy Barrier Energy needed to initiate a reaction. Chemical Attack Corrosion due to chemical reactions with materials. Transgranular Cracks Cracks that pass through the grains. Intergranular Fractures Fractures occurring along grain boundaries. Corrosion Prevention Technique Supplies electrons to convert metal into cathode. 4/6 Materials Science and Engineering Finals Study online at https://quizlet.com/_g5pa86 Generalized Reaction Oxidation rate influenced by oxide and metal volumes. Pilling-Bedworth (P-B) Ratio Determines protective nature of oxide film. Ionic Character Percentage of ionic bonding in materials. Microstructure Influence Ceramics' properties depend on their microstructure. Polycrystalline Ceramics Made of multiple crystal grains. Monocrystalline Ceramics Consist of a single three-dimensional crystal. Ceramic Fabrication Processes to create ceramic materials. Glass Forming Heating raw materials to produce glass. Hydroplastic Forming Extrusion technique for ceramic mass shaping. Slip Casting Clay mixture poured into porous mold. Drying and Firing Processes to strengthen unfired ceramic pieces. Powder Pressing Compaction of powders into geometric forms. Tape Casting Process for creating advanced ceramic substrates. Types of Polarization Two categories affecting electrochemical reactions. Material Degradation Interactions impairing material properties over time. Natural Polymers Biological materials like proteins and cellulose. Synthetic Polymers Man-made materials with superior properties. Hydrocarbon Molecules Compounds made of hydrogen and carbon atoms. Molecules with double/triple bonds allowing additional attach- Unsaturated Hydrocarbons ments. Saturated Hydrocarbons Molecules with only single bonds, no new attachments possible. Anode Electrode where oxidation occurs, metal loses electrons. Cathode Electrode where reduction occurs, metal gains electrons. Electrochemical Potential Voltage indicating driving force for electrochemical reactions. Monomer Small molecule that forms a polymer chain. Repeat Unit Structural entity repeated in a polymer chain. Homopolymer Polymer made from identical repeating units. Copolymers Polymers composed of two or more different units. Bifunctional Monomer Monomer with two active bonds for polymerization. Trifunctional Monomer Monomer with three active bonds forming networks. Molecular Weight Average mass of polymer chains, affects properties. Molecular Mass Mass of a molecule, often used interchangeably. Activation Energy Energy barrier limiting the slowest reaction step. Corrosion Prevention Strategies Techniques like coatings and inhibitors to reduce corrosion. Molecular Shape Arrangement of atoms in a molecule affecting properties. Chain Length Distribution Variation in lengths of polymer chains during synthesis. Electrochemical Reaction Reaction involving transfer of electrons between species. Hz ions Protons essential for electrochemical reactions at electrodes. Depletion zone Region near electrode with reduced Hz ion concentration. Corrosion rates Influenced by fluid velocity, temperature, and concentration. Stereoisomerism Same atom order, different spatial arrangement. Isotactic configuration Zigzag pattern of carbon chain atoms. Vulcanization Crosslinking process in rubber to enhance elasticity. Thermoplastic Polymer Polymers that can be remolded upon heating. 5/6 Materials Science and Engineering Finals Study online at https://quizlet.com/_g5pa86 Thermosetting Polymer Polymers that cannot be remolded after curing. Oxide film Thin layer protecting metals from further corrosion. Sacrificial Anode More reactive metal protecting less reactive metal. Hydrogen embrittlement Reduction in ductility from hydrogen penetration. Crosslinked Polymers Polymers with chains joined by covalent bonds. Branched Polymers Polymers with side chains attached to main chain. Linear Polymers Polymers with straight chain structures. Mechanical properties Characteristics like strength and ductility of materials. Ozone (Oƒ) Accelerates degradation of vulcanized rubbers. Thermoplastics Soft materials shaped by heat and pressure. Examples of Thermoplastics Polyethylene, polystyrene, PET, PVC. Thermosets Materials with strong covalent crosslinks preventing softening. Examples of Thermosets Vulcanized rubbers, epoxies, phenolics, polyester resins. Random Copolymer Two units randomly dispersed in the chain. Alternating Copolymer Two units alternate positions in the chain. Block Copolymer Identical units clustered in blocks along the chain. Graft Copolymer Homopolymer branches grafted onto different main chains. Polymer Crystallinity Ordered packing of molecular chains in polymers. Semicrystalline Polymers Contain crystalline regions interspersed with amorphous regions. Lamellae Thin platelets formed by polymer single crystals. Spherulites Polymer structures equivalent to grains in metals. Stress-Strain Behavior Classifies polymers as brittle, plastic, or elastic. Viscoelastic Deformation Intermediate behavior between elastic and viscous materials. Relaxation Modulus Time-dependent modulus of elasticity in polymers. Fracture Strength Low relative strength compared to metals and ceramics. Crazing Localized deformation regions leading to increased ductility. Elastic Deformation Molecules elongate in stress direction in semicrystalline polymers. Crystallization Transformation of liquid phase into ordered structures. Melting Solid polymer transforms into a viscous liquid. Polymer Types Includes plastics like polyethylene and polypropylene. Polymerization Synthesis of polymers via addition or condensation. 6/6