Evaluation of bonds in armor plate and other materials using infrared nondestructive testing techniques

Reported here are the results of using an ir technique in evaluating the bond in hot-roll bonded armor plate, a coating bond, and the bonds in the three-layer construction of a small missile motor. When a specimen is exposed to heat, the heat flows into it at a rate that can be determined. If the flow is interrupted by a void, the inclusion of a material of different conductivity, or any similar thermal barrier, a difference in surface temperature will result that can be defined with an ir radiometer or thermograph. Lack of bond, while not presenting a gross void, is shown here to be a sufficient impediment to be distinguishable.