Glossary of Selected Terms
ABS - A polymer consisting of acrylonitrile, butadiene, and styrene.
Absolute Humidity -The mass of water vapor per unit volume of air.
Accuracy -The degree to which a measured value represents the true value for a specific measurement.
Acid - A chemical compound containing a nonmetal, hydrogen, and sometimes oxygen that neutralizes bases to form salts. Inorganic acids contain H+ ions. Organic acids contain the carboxyl group.
Strong Acids in Water / Weak Acids in WaterChromic / H2CrO4 / Acetic / HC2H3O2
Hydrobromic / HBr / Ascorbic / HC6H7O6 (Vitamin C)
Hydrochloric / HCl / Benzoic / HC7H5O2
Hydroiodic / HI / Formic / HCHO2
Nitric / HNO3 / Hydrocyanic / HCN
Perchloric / HClO4 / Hydroflouric / HF
Permanganic / HMnO4 / Nitrous / HNO2
Sulfuric / H2SO4 / Phosphoric / H3PO4
Acrylic Resin - Any of a group of thermoplastic resins that are formed through polymerization of acrylic acid, methacrylic acid, esters of these acids, or acrylonitrile. Acrylic products are lightweight, weather resistant, and typically clear.
Advanced Composite - A composite material that contains continuous fiber reinforcement.
Age Hardening - Also known as precipitation hardening, because one phase of a two-phase system precipitates and evenly distributes throughout the other phase. This precipitation and dissolution may be accelerated with heat treatment conditioning.
AI - Asphalt Institute.
AISI - American Iron and Steel Institute.
Alcohols - A group of organic chemicals that contain the -OH group, such as methanol (CH3OH) and ethanol (C2H5OH).
Aliphatic Compounds - Organic chemicals that contain long-chain carbons and not ring-type structures.
Alloy - A substance with metallic properties that comprises two or more elements that do not separate upon mixing. Alloys may consist of two or more metals, such as iron and carbon, which combine to form the alloy steel.
Alumina - Term used for pure aluminum oxide.
Amorphous - Noncrystalline-structured materials, such as some types of glass.
Anisotropic Materials - Materials that exhibit different properties along different axes.
Annealing - Heat treatment procedure that converts metal to its softest condition.
Anode - The pole or electrode in a plating cell or electrolytic cell that provides electrons. Typically, the anode is the negative post on a battery or the positive electrode in a plating cell.
Anodizing - Process through which an anode material is coated with ions from the electrolyte to form a hard, chemical-resistant outer surface.
ANSI - American National Standards Institute.
Antiknock Compound - Substances used to raise the antiknock properties of fuels, particularly gasoline, expressed by octane number. Tetraethyl lead was primarily used in the past as an antiknock agent, but it has been replaced due to Environmental Protection Agency (EPA) regulations. Replacements include tertiary butyl alcohol (TBA) and methyl tertiary-butyl ester (MTBE).
API - American Petroleum Institute.
ASM - American Society for Metals.
Asphalt - Bituminous material of a high molecular weight that occurs naturally or as a distillation product of crude oil. It is primarily used as a binding agent in road construction and in roofing products.
Attenuation - Loss or weakening effect, particularly in reference to amplification or reproduction of sound.
Austempering - Heat treatment process by which steel is quenched at a rate that misses the knee of the Time-Temperature-Transformation (TTT) curve until just above the Ms line and held there until transformation is complete.
Austenite - Face-centered cubic structure of steel.
Austenitic Stainless Steel - Nonmagnetic stainless steels whose composition holds them in a face-centered cubic structure at room temperature.
Average - The sum of the data in a set of numerical data divided by the number of data taken.
Base -A substance that contains an excess of hydroxide (-OH) ions. Bases neutralize acids to form salts and water, such as using baking soda to neutralize acid spills.
Benzene - Aromatic hydrocarbon, which consists of six carbon atoms and six hydrogen atoms arranged in a hexagonal ring structure.
Bessemer Converter - Machine that blows air up through the bottom of the melt to aid in converting iron into steel.
Brass -Alloy of copper and zinc.
Brittleness - A lack of ductility. Brittle factures occur through rupture of the interatomic bonds. Brittle fractures occur more readily in tension than shear; therefore, brittle materials have high compressive strengths and lower tensile strengths. Some typically brittle materials are stone, concrete, brick, ceramics, and some metals, such as high-carbon steels and cast iron.
Bronze - Alloy of copper and anything else, traditionally tin.
Calorie - Also known as the gram calorie, the heat required to raise the temperature of one gram of water by one degree Celsius.
Carbonitriding - Heat treatment process through which steels are case hardened by heating them in a gaseous environment rich in both carbon and nitrogen.
Carborundum - Silicon carbide (SiC) abrasive.
Carburizing - Case-hardening treatment of steels in which the metal is submerged in a high-carbon atmosphere and the carbon is allowed to diffuse into the outer layers of the metal.
Case Hardening - Process through which the outer layers of a metal are significantly harder than the inner core.
Cast Iron - Iron product that contains a carbon content greater than 2 percent.
Cathode - Electrode in an electrolytic cell that accepts electrons; the negative electrode in a plating cell or the positive post on a battery.
Cation - An element or radical that is positively charged.
Cement Factor -The number of bags of cement required per cubic yard of concrete.
Cementite - Iron Carbide form.
Ceramic - Compounds of metallic and nonmetallic elements that exhibit properties different than either, including stone, clays, Alumina, Silicon Carbide, and cement.
Cermets - Ceramics that have metals as an ingredient.
Cetane Number - Measure of the ignition quality of diesel fuel. It is expressed as the percentage of cetane that must be mixed with liquid methylnapthalene to produce the same ignition performance as the fuel being tested. Higher cetane numbers designate cleaner-burning fuel and better performance.
Charpy test - Impact test that uses a swinging pendulum to strike a notched specimen to determine the specimen’s resistance to shock loading. The specimen is held on both ends and struck in the middle.
Clay - A fine-grained soil that consists primarily of hydrous aluminum silicate.
Coke - Anthracite or hard coal that has all hydrogen and other atoms removed by heating in an oxygen-free atmosphere, leaving a relatively-pure carbon result.
Composites - Two or more components, which, when joined, exhibit properties unlike those available separately.
Concrete - Any aggregate bonded together with a cementing agent. Typically, an artificial stone product of gravel, sand, cement, and water.
Condensation Reaction - The reaction of two compounds which results in a by-product condensate that is a smaller molecule, such as water or alcohol.
Copolymer - Polymer in which the mer is made up of two or more different molecules.
Cracking - Process of refining petroleum in which large molecules are broken down into smaller units under heat and pressure or in the presence of a catalyst.
Creep -Deformation that results from a load (typically tensile) applied over an extended amount of time and, perhaps, at elevated temperature.
Curing - A treatment that is applied to increase the strength properties of a material such as polymers or concrete. The increased strength is a result of additional linkages being formed between molecules.
Cyaniding - Process of case-hardening a steel by submerging it in a sodium cyanide environment. The carbon and nitrogen in the cyanide are absorbed into the outer layers of the steel.
Deflection - Deformation as a result of an applied bending stress.
Density - Mass per unit volume of a material, e.g. grams per cubic centimeter.
Ductility - Property of materials that allows them to undergo large permanent deformations prior to fracture.
Durometer - Hardness tester used primarily for plastics and elastic materials which measures the elastic deformation on the surface of the material.
Elastic Limit - The greatest amount of stress a material can develop without taking a permanent set.
Elasticity - Property of materials that allows them to deform under load and return to their original condition when the load is removed.
Elastomer - A synthetic material with elastic properties, such as rubber tires.
Electric Arc Converter - Machine that uses large carbon electrodes to carry current through pig iron to burn out excess carbon and help convert iron into steel.
Endurance Limit - A stress below which a load may be repeated indefinitely without failure.
Entrainment - Dispersion of an undissolved liquid or gas in a liquid or gaseous medium, such as entrained air in concrete.
Eutectic - Composition of a system that yields the lowest melting temperature. Also, the composition of a system containing two or more components that allows the system to go directly from a liquid to a two-phase solid without passing through a two-phase region.
Extrusion - Process of pushing a billet of material through a die to produce strips that have uniform cross-sectional forms, such as beams and tubing. Used for a variety of materials, including aluminum and many plastics.
Fatigue - Failure of materials due to cyclic strain. Fatigue can be readily seen as stress cracks at critical holes or joints in metals, such as bending a piece of metal back and forth repeatedly.
Fatigue Limit - Maximum stress below which a material will not fail regardless of the number of cycles.
Ferric Materials - Materials composed of iron in a form which exhibits a valency of +3.
Ferrite - Alpha iron or a solid solution containing less than 0.025% carbon in iron. Generally considered pure iron.
Ferritic Stainless Steels - Low-carbon steels than contain between 20 and 37% chromium; designated as the 400 series of stainless steels.
Ferrous Materials - Materials composed of iron in a form which exhibits a valency of +2.
Flame-Hardening - Hardening of the surface of a metal by heating it with a flame and them quenching it rapidly. Only the surface is heated into the austenitic range; therefore, only the surface goes into martensite.
Flash - Extra material that flows into the joint between mold or die cavity halves, especially in compression molding and die forming. Flash must be removed after molding.
Flash Point - The temperature at which an oil will ignite, but not maintain, a flame.
Fluid - Any material that flows in the liquid, vapor, or gaseous form. Fluidity and viscosity are properties which describe how well a fluid flows.
Gage Length - The length over which a strainometer or other device measures the strain or deformation of a test piece.
Galvanizing - The process of coating iron or steel with zinc to protect the base material from oxidation.
Gamma Iron - Austenite form.
Glass - The amorphous structure of silicates and certain oxide formations. Typically referred to as a super-viscous liquid.
Hardness - The ability of a material to resist surface penetration. Different tests involve various indenters, plastic deformation, elastic deformation, and resistance to surface abrasion.
Hardwoods -Woods that come from deciduous trees, such as oak and walnut.
High Polymers - Also called high-molecular-weight polymers; materials that have combined so many of the same molecules that the structure has an ultra high molecular weight such as UHMWPE (polyethylene).
Holography -The use of lasers to produce interference patterns of true 3-D.
Hybrid - Composite material that contains two or more different reinforcing fibers.
Hydraulic Cement - Term used in the past to distinguish between true cements and those of hydrated lime. Cements will harden under water, whereas lime is water-soluble and will dissolve if submerged under water for an extended period of time.
Index of Refraction - The ratio of the speed of light in a vacuum to the speed of light within a substance. It can be calculated by dividing the sine of the angle of incidence by the sine of the angle of refraction.
Inorganic Compounds - Compounds that do not include hydrocarbons and their derivatives. However, some simple compounds such as carbon dioxide and metallic carbonates are classified as inorganic compounds.
Intermetallic - Material that is a combination of two or more different metal types.
Interply Knitting - The process of sewing together different layers or plys of reinforcing fibers. If the fibers on successive layers are of different types, the product is termed an interply hybrid.
Interstitial - An atom or particle not on a lattice point in a crystal, an imperfection.
Intraply Hybrid - A composite with different fiber types within each layer or ply.
Ion - Electrically-charged atom or group of atoms that has lost or gained electron(s) causing an electrical imbalance.
Isomer - Molecules that have the same number and types of atoms which are arranged differently. Isomers have the same molecular weight but exhibit different properties.
Isotropic Material - A material that exhibits different properties in different axes.
Izod Test - An impact test that uses a swinging pendulum to strike a notched specimen that is held firmly at one end.
Jominy Test -An end-quench test for steel to determine the hardening depth.
Joule - Unit of energy (SI unit) equal to the work done when a force of 1 Newton is exerted over a distance of 1 meter.
Layup - In composite manufacture, the position and direction of the reinforcing material.
Lime - Term used for quicklime (CaO) and hydrated lime [Ca(OH)2].
Linseed Oil - Vegetable oil derivative of flax. Due to oxidation, it darkens and thickens when exposed to air.
Liquid - Material state in which the shape of the material depends on the vessel in which it is contained but its volume does not.
Maraged Steel - A high-nickel-content, low-carbon steel that is heated to 15000F (8220C), air-cooled, and then aged at 9000F (4860C). Maraged steel is generally considered a superalloy.
Martempering - A heat treatment process for steels in which steel is heated into the austenitic temperature range, held at approximately 5000F (2620C) until it is uniformly heated throughout, and then quenched to room temperature.
Martensite - The body-centered tetragonal structure of steel. It is the hardest form of steel, produced by rapidly quenching a steel that has been heated into the austenitic temperature range.