COALESCENSE (PT): The merging of two or more particles of a liquid, gas, or solid into a single larger particle: The
uniting by growth in one body.
COBALT-60: A radioisotope of the element cobalt.
COBALT-60 (RT): A radionuclide of the element cobalt, emitting gamma rays with energies of 1.33 and 1.17 MeV,
with a half-life of 5.3 years.
COEFFICIENT OF THERMAL EXPANSION: The linear expansion or contraction per unit length per degree
Fahrenheit between specified lower and upper Fahrenheit temperatures. If aluminum is involved, such values are
multiplied by one million for easier reading.
COERCIVE FORCE (MT): The value of the reversing magnetizing force necessary to bring the flux density back to
COHERENT SCATTER: The result of Compton scattering in which the electron receives none of the energy from the
primary radiation. The resultant scattered radiation is of the same energy as the incident beam.
COHESION: Molecular attraction by which the particles of a solid are held together.
COIL (ET, MT): One or more turns of conductor wound to produce a magnetic field when current passes through the
COIL IMPEDANCE (ET): The total opposition to current flow through a coil and is represented by the ratio of the coil
voltage to the coil current. This impedance is affected by the material within the magnetic field generated by the coil
and is sometimes used to measure eddy current response.
COIL SHOT (MT): A term used colloquially to indicate a shot of magnetizing current passed through a solenoid or coil
surrounding a part, for the purpose of establishing a longitudinal field.
COIL SIZE (ET, MT): The geometry or dimension of a coil; for example, length or diameter.
COIL SPACING: The axial distance between two encircling coils in a different system.
COLD CRACKS: Appear as a straight line, usually continuous throughout its length and generally exist singly. These
cracks start at the surface.
COLD SHORT: A condition of brittleness existing in some metals at temperatures below the recrystallization
A discontinuity that appears on the surface of cast metal as a result of two streams of liquid meeting and
failing to unite.
A portion of the surface of a forging that is separated, in part, from the main body of metal by oxide.
COLD WORKS: Permanent strain produced by an external force in a metal below its recrystallization temperature.
COLD WORKING: Deforming metal plastically at a temperature lower than the recrystallization temperature.
COLLIMATOR (RT): A device used to limit the size, shape, and direction of the primary radiation beam.
COLLIMATOR (UT): A lens assembly attachment designed to reduce the ultrasonic beam spread.