Materials Technology: Bonding, Ferrous and Non-Ferrous Metals

Practice flashcards covering atomic bonding, non-ferrous and ferrous metallurgy, alloy classification, and steelmaking processes.

Primary Bonding

Strong atom-to-atom bonding characterized by the exchange or sharing of electrons.

Secondary Bonding

Weak bonding between atoms or molecules where electrons are not exchanged, such as van der Waals forces or hydrogen bonds.

Ionic Bond

A primary bond composed of both metallic and non-metallic elements where one atom transfers electrons to another of a different type to form cations and anions.

Covalent Bond

A primary bond characterized by the sharing of valence electrons between atoms to form stable shells, exhibiting directional bonding.

Metallic Bond

A primary bond where valence electrons are shared in a sea of electrons surrounding positive metal ion cores.

Fraction Covalent

The proportion of covalent character in a mixed bond calculated using the formula $\text{Fraction Covalent} = 1 - e^{-0.25(\\text{Delta} E)^2}$, where $\Delta E$ is the difference between electronegativities.

Van der Waals Bonding

Secondary joining of molecules or groups of atoms by weak electrostatic attractions, such as dipole-dipole forces between positive and negative ends of molecules.

Hydrogen Bonding

A type of secondary bonding occurring when a positively charged hydrogen nucleus ($\text{H}^+$) is attracted to unshared, negatively charged electrons of another atom, such as oxygen ($\text{O}^{2-}$).

Thermoplastics

Polymer materials consisting of complex entanglements of polymer chains held together by weak secondary bonds that can be remelted and reshaped.

Thermosets

Polymer structures containing permanent primary cross-linking bonds between chains or atom groups that prevent melting upon reheating.

Allotropic

The characteristic of pure metals (such as pure iron) to exist in two or more distinct crystal structures depending on temperature and pressure.

Polymorphic

The characteristic of non-metallic substances (such as silica, $\text{SiO}_2$) to exist in two or more distinct crystal structures at different temperatures.

Bayer Process

A hydrometallurgical refinement process that converts crushed bauxite ore into dry alumina powder ($\text{Al}_2\text{O}_3$) using lime, caustic soda, water, heat, and pressure.

Hall-Héroult Process

An electrolytic reduction process in which alumina ($\text{Al}_2\text{O}_3$) is dissolved in molten cryolite ($\text{Na}_3\text{AlF}_4$) to lower its melting point from $2072\,^\circ\text{C}$ and electrolyzed to form liquid aluminum.

Dow Process

A chemical and electrolytic process extracting magnesium metal from seawater brine using lime ($\text{Ca(OH)}_2$), hydrochloric acid ($\text{HCl}$), and molten salt electrolysis of $\text{MgCl}_2$.

Mond Process

A refinement process where carbon monoxide ($\text{CO}$) is passed over nickel ore to form volatile nickel carbonyl ($\text{Ni(CO)}_4$), which decomposes at elevated temperature into CO gas and metallic nickel dust.

Pyrometallurgy

Thermal extraction and purification methods for metals operating at elevated temperatures, such as smelting.

Hydrometallurgy

Extraction and purification methods for metals utilizing aqueous chemistry, such as leaching and solvent extraction.

Electrometallurgy

Refining or extraction processes for metals utilizing electrical energy, such as electrowinning or electrorefining.

Refractory Metals

A group of metals characterized by extremely high melting points exceeding $2800\,^\circ\text{F}$ ($1538\,^\circ\text{C}$), including niobium, tantalum, hafnium, tungsten, molybdenum, rhenium, chromium, and vanadium.

Passivation Layer

A thin protective oxide film that spontaneously forms on the surface of metals such as titanium, aluminum, and stainless steel, granting high corrosion resistance.

Magnetite

A primary iron ore mineral with the chemical formula $\text{Fe}_3\text{O}_4$.

Hematite

A primary iron ore mineral with the chemical formula $\text{Fe}_2\text{O}_3$.

Taconite

A low-grade primary iron ore consisting of iron-bearing silica rock that is processed into rounded iron ore pellets.

Coke

Processed coal consisting of nearly pure carbon, used as fuel and a chemical reducing agent in blast furnaces.

Slag

The liquid byproduct floating on top of molten metal in a furnace, formed when flux reacts with non-metallic impurities.

Flux

A mineral agent (such as limestone) added during smelting to react with impurities and separate them into slag.

Pig Iron

The crude molten iron output directly tapped from a blast furnace, containing approximately $4\%$ carbon along with sulfur and silicon impurities.

Blast Furnace

A tall refractory furnace that reacts iron ore, limestone, and coke with hot dry air to continuously produce molten pig iron and slag.

Bessemer Converter

An early steelmaking vessel that converts molten pig iron into steel in $12-15\,\text{minutes}$ by blowing compressed air through tuyeres at the bottom of the vessel.

Electric Arc Furnace (EAF)

A steelmaking furnace that uses high-voltage electric arcs between graphite electrodes to melt recycled steel scrap or direct-reduced iron into refined steel.

Basic Oxygen Furnace (BOF)

A modern steelmaking vessel that uses a water-cooled lance to inject high-purity oxygen into molten pig iron and scrap to rapidly reduce carbon content and refine steel.

Continuous Casting

A manufacturing process in steelmaking where molten steel flows from a ladle into a tundish and cooled mold to directly produce continuous strands of slabs, blooms, or billets.

Iron-Iron Carbide Phase Diagram

An equilibrium phase diagram mapping phases of iron-carbon mixtures up to $6.67\%$ carbon, distinguishing steels ($< 2\%$ carbon) from cast irons ($2\%$ to $4\%$ carbon).

Low-Carbon Steel

Plain carbon steel containing $0.05\%$ to $0.32\%$ carbon by weight, widely used for sheet metal and structural applications.

Medium-Carbon Steel

Plain carbon steel containing $0.35\%$ to $0.55\%$ carbon by weight, commonly used for machine parts and machinery.

High-Carbon Steel

Plain carbon steel containing $0.60\%$ to $1.50\%$ carbon by weight, used for machine tools, cutlery, and high-strength applications.

Austenitic Stainless Steel

Non-magnetic stainless steel alloys (AISI 2xx and 3xx series) containing chromium, nickel, and manganese, providing high formability and corrosion resistance.

Ferritic Stainless Steel

Stainless steel alloys (AISI 405, 430, 445) containing chromium ($11\%$ to $28\%$) with low carbon content, offering good weldability and general corrosion resistance.

Martensitic Stainless Steel

Heat-treatable stainless steel alloys (AISI 403, 410, 420) containing chromium ($11\%$ to $15\%$) and $0.15\%$ carbon, commonly used for turbine blades.

Platinum Group Metals (PGMs)

A set of six transition elements (ruthenium, rhodium, palladium, osmium, iridium, platinum) derived as nickel ore byproducts and used primarily as catalysts.

Galvanic Series

A relative ranking of metals and alloys arranged according to their electrochemical potential and corrosion activity in a given environment.