T.O. 33B-1-1Glossary 63PHOTOGRAPHIC INTENSIFICATION (RT): Chemical treatment of a processed emulsion, usually with an oxidizingagent, 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 atother 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 particulateradiation may produce chemical or physical changes in the emulsion.PHOTOTHERMOGRAPHIC FILM (RT): A blue/green sensitive “dry silver” film used in conjunction with specialfluorescent 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 thesound 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 ofthe 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 gasevolution 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 numeroussmall 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 theback end.(4)A tubular metal product, cast or wrought.PITCHBLENDE: An ore that contains uranium.
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