Thickness evaluation of thermal barrier coating by using pulsed laser array spots infrared thermography

Thickness of thermal barrier coating (TBC) system of gas turbine blades is one of the pivotal parameters that significantly affects its thermal insulation capacity and other working performance, and therefore, is essential to be properly evaluated non-destructively. It is still lack of efficient nondestructive evaluation technique to evaluate the thickness of TBC of a large area. In this paper, the pulsed laser array spots thermography method was adopted to measure the thickness of TBCs by using time at the minimum 2nd logarithmic derivative of the cooling stage of the temperature evolution curve. Both numerical and experimental validations are conducted and the results demonstrated the validity of the proposed method for coating thickness evaluation of TBC specimens fabricated by using the atmospheric plasma spraying technique.