Measuring the damage to a turbine-blade thermal barrier

A method for evaluating damage to a thermal barrier deposited on a metal substrate of a component, the thermal barrier including an aluminum underlayer and a layer of ceramic material with a columnar structure oriented perpendicularly to the substrate, the underlayer being positioned between the substrate and the ceramic layer, the damage being defined by thickness of oxidized metal present in the underlayer, the method comprising:

• selecting a given number of calibration elements including a substrate which is covered by the thermal barrier, the calibration elements having been subjected to damage by exposure for different periods of time to oxidation conditions representative of use;
• exposing, for a given period of time, the calibration elements to an electromagnetic radiation;
• measuring a temperature obtained on a surface of the calibration element after the given period of time, for each calibration element;
• establishing a calibration curve based on an increase in measured temperature on the surface of the calibration element to damage suffered by the calibration element, for each calibration element;
• exposing an element to be evaluated to radiation for the given period of time, the element to be evaluated including a substrate which is covered by the thermal barrier;
• measuring the temperature obtained on the surface of the element to be evaluated after the given period of time;
• plotting, on the calibration curve, an increase in measured temperature on the surface of the element to be evaluated after the given period of time;
• and
• determining the damage of the thermal barrier of the element to be evaluated from the calibration curve based on the increase in measured temperature on the surface of the element to be evaluated.