Glossary
Anions
The ion in an electrolyzed solution that migrates to the anode. A negatively charged ion. Anions are usually formed from a nonmetal or group of atoms.
Atomic number
An experimentally determined number characteristic of a chemical element that represents the number of protons in the nucleus which in a neutral atom equals the number of electrons outside the nucleus.
Backscattered electrons
High-energy electron produced by elastic collision of incident electron beam with electron cone of sample atom. Backscattered electron "yield" is proportional to atomic number of sample electron, so backscattered electorn imaging include atomic number (Z) contrast, as well as, topographical information.
Binding energies
The energy required to break up a molecule, atom, or atomic nucleus completely into its constituent particles.
Bonding information
Information indicative of an elements chemical state, used to determine oxidation states of metals or chemical bonding with other elements.
Cations
The ion in an electrolyzed solution that migrates to the cathode. A positively charged ion. Cations are usually formed from hydrogen or metal atoms.
Chemical attack
Dissolution or breakdown of polymer resin by chemical solvent.
Chemical bonding
The joining together of atoms to form molecules.
Crevice corrosion
Localized corrosion of a metal surface that is partially shielded from the ambient environment due to close proximity of another metal or nonmetallic surface. The difference in the environment inside and outside the crevice result in localized acceleration of the electrolytic corrosion reactions.
Electron
A negatively charged particle that resides in specific orbits around the nucleus of an atom.
Electron beam
A stream of electrons in an electron optical system.
Energy dispersive x-ray
Analytical method used for determination of elemental chemical composition.
Environmental stress cracking
Cracking or crazing of a polymer resin due to exposure to a chemical environment.
Environmentally-assisted fracture
Fracture that is assisted by some condition in the environment. Types of environmentally assisted fracture include: stress corrosion cracking, creep facture, and hydrogen embrittlement in metals and environmental stress cracking and oxidation embrittlement in plastics. Environmentally-assisted fractures occur at stresses that would not cause damage to the component in a more benign environment.
Failure analysis
The systematic investigation of a component failure with the objectives of determining why the component failed and the corrective actions needed to prevent future failures.
Failure mechanism
The basic material behavior that resulted in the failure. Examples of failure mode include: ductile fracture, brittle fracture, fatigue fracture, corrosion, erosion, wear, and distortion.
Failure root cause
The fundamental condition or event that caused a failure. Examples of root cause include: design deficiencies, manufacturing errors, improper material, material defects, inadequate maintenance, abusive service.
Fatigue
Fracture due to successive application and removal of stresses less than the ultimate strength of the component material. Fatigue fracture will require from several hundred to several million cyclical stress applications.
Functional group
A characteristic reactive unit of a chemical compound.
Galvanic corrosion
Accelerated corrosion of a metal in direct contact with a more noble metal or nonmetallic conductor and a corrosive electrolyte.
General corrosion
Electrochemical reaction between a metal and an electrolyte. General corrosion results in a relatively uniform dissolution of the metal across the entire area of exposure to the electrolyte.
Infrared absorption bands
Regions of infrared light spectrum absorbed by excitation of irradiated sample. Wavenumber, shape, and intensity for absorption bands are characteristic of the molecule structure of the sample.
Intra-molecular
Existing or acting within the molecule. Formed by reaction between different parts of the same molecule.
Ion
An atom in a charged state, either having a deficiency (a positive charge) or a surplus (having a negative charge).
Ion beam
Focused stream of atoms or groups of atoms with a negative or positive charge due to the gain or loss of one or more elctrons.
Microns
A metric unit of length measurement=
1x10-6 meters or 0.000001 meters
4x10-5 inches or 0.00004 inches
Human hair is approximately 20 micrometers in diameter
Organic
Materials containing carbon compounds, including plastics, rubbers, and most lubricants.
Overload
Fracture due to forces exceeding the strength of the component material.
Photoelectrons
An electron released in photoemission.
Photooxidation
Embrittlement of polymer materials due to oxidation by exposure to light, usually ultraviolet radiation.
Pitting
Electrochemical dissolution of metal at a confined point or small area. Pitting occurs in select combinations of metals and electrolytes and is more prominent in metals that exhibit surface passivation, such as stainless steel.
Scanning electron microscope (SEM)
An electron microscope in which the image is formed by a beam synchronized with an electron probe scanning the object. The intensity of the image forming beam is proportional to the scattering or secondary emission of the specimen where the probe strikes it.
Secondary electrons
Produced by an incident electron passing "near" an atom in the specimen, near enough to impart some of its energy to a lower energy electron (usually in the K-shell). This causes a slight energy loss and path change in the incident electron and the ionization of the electron in the specimen atom. This ionized electron then leaves the atom with a very small kinetic energy (5eV) and is then termed a "secondary electron". Each incident electron can produce several secondary electrons.
Stress corrosion cracking
Cracking of metals due to the combined action of a corrosive environment and a sustained tensile stress.
X-rays
Electromagnetic radiation of extremely short wavelength, emitted by bombarding a sample with fast electrons, whose energy and wavelength are related to the specimen's elemental composition.
