T.O. 33B-1-1
Glossary 63
PHOTOGRAPHIC INTENSIFICATION (RT): Chemical treatment of a processed emulsion, usually with an oxidizing
agent, to lessen the density. There may be a change of contrast, depending on the process used.
PHOTOGRAPHIC TRANSMISSION DENSITY (RT): See DENSITY.
PHOTON (RT): An electromagnetic packet of radiation. It has a dual character, acting sometimes like a particle and at
other times like a wave. Photons all have equal velocity (the speed of light), have no electric charge, and have no mass.
PHOTO-SENSITIVITY (RT): A property of a photographic emulsion by virtue of which electromagnetic or particulate
radiation may produce chemical or physical changes in the emulsion.
PHOTOTHERMOGRAPHIC FILM (RT): A blue/green sensitive “dry silver” film used in conjunction with special
fluorescent screens in vacuum cassettes which can serve as an alternative to X-ray film for noncritical applications.
The principle advantage of this film is that it is processed thermally, eliminating the need for wet chemicals.
PHYSICAL PROPERTIES: The properties, other than mechanical properties, that pertain to the physics of a material;
for example, density, electrical conductivity, heat conductivity, thermal expansion.
PHYSICAL TESTING: Determination of Physical Properties.
PICKLE: Using acid or other chemicals with suitable inhibitors to remove scale or smeared metal without affecting the
sound metal.
PICKLE PATCH: A tightly adhering oxide or scale coating not properly removed during the pickling process.
PICKLE STAIN: Discoloration of metal due to chemical cleaning without adequate washing and drying.
PICKLING CRACKS: Cracks caused by internal stresses being released as the pickling acid eats away the surface of
the material.
PIEZOELECTRIC (UT): That ability of a material to convert electrical energy into mechanical energy and vice versa.
PIG: A cast slab of primary metal that must be remelted before use.
PINHOLES: Very small holes; sometimes found as a type of porosity in a casting because of microshrinkage or of gas
evolution during solidification.
PINHOLE (RT): A through hole of small diameter in a sheet of material opaque to radiation.
PINHOLE POROSITY: Porosity, in either castings or metal formed by electrodeposition, resulting from numerous
small holes distributed throughout the metal.
PIPE:
(1)
The central cavity formed by contraction in metal, especially ingots, during solidification.
(2)
The defect in wrought or cast products resulting from such a cavity.
(3)
An Extrusion Defect due to the oxidized surface of the billet flowing toward the center of the rod at the
back end.
(4)
A tubular metal product, cast or wrought.
PITCHBLENDE: An ore that contains uranium.
