Nondestructive technique of measuring heat conductivity of thermal barrier coatings

Abstract

A non-destructive technique for measuring effective thermal conductivity of thermal barrier coatings (TBCs) was developed. The heat conduction problem in the sample is solved numerically, making this technique applicable to bodies of elements shape covered by TBCs. The principle of the experiment relies on locally heating the sample by a laser flash and recording the time and space variation of the so generated temperature field on the heated surface by an IR camera. Both laser and camera are located on the same side of the heated surface. The thermal conductivity is retrieved by an inverse method where the Finite Element solver is invoked iteratively minimizing the discrepancy between the measured and simulated results. The geometry of the sample is captured by a laser scanner twice: before and after the TBC is deposited. Results are compared with measurements conducted by a commercial Laser Flash Apparatus (LFA) achieving good agreements.