These substances now have dual uses.
Liquid/vapor-phase corrosion inhibitors (LVCIs) have been found to be additionally useful as penetrant dyes for neutron radiography (and perhaps also x-radiography). Enhancement of radiographic contrasts by use of LVCIs can reveal cracks, corrosion, and other defects that may be undetectable by ultrasonic inspection, that are hidden from direct optical inspection, and/or that are difficult or impossible to detect in radiographs made without dyes.
The figure presents two neutron radiographs of part of a frame made of 2219 aluminum alloy. The first radiograph, made before treating the frame with an LVCI, shows some corrosion and includes a faint dark line indicative of a weld crack at a corner. In the second radiograph, made after treating the frame with an LVCI, the weld crack is more clearly visible as a longer, thicker, bright line.
It has been conjectured that LVCIs may be useful as penetrant dyes for x-ray as well as for neutron radiography. Further research is needed to determine which formulations of LVCIs would be most suitable for dual use as corrosion inhibitors and penetrant dyes for radiography. For example, in formulating an LVCI for a particular application it might be possible to add a small amount of x-ray-attenuating material to enhance x-radio-
This work was done by Howard L. Novak and Phillip B. Hall of USBI Co. for Marshall Space Flight Center. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Materials category.