Meaning
Physical deterioration of insulation layers which leads to increased heat transfer and potential structural failure in high temperature environments. Thermal barrier degradation occurs through mechanisms such as oxidation, delamination, sintering or the chemical reaction with environmental contaminants. It reduces the effectiveness of the coating that protects metal components in turbines and exhaust systems.
Physical Mechanism
Exposure to repeated heating and cooling cycles creates internal stresses that eventually cause the protective layer to flake away from the substrate. This type of thermal barrier degradation is accelerated by the presence of salts or volcanic ash in the intake air.
Inspection Metric
Monitoring the health of these coatings requires specialized non destructive testing methods like infrared thermography. During an inspection, thermal barrier degradation is identified by the presence of hot spots on the surface of the component. If the temperature difference exceeds a set threshold, the part is removed for refurbishment.
The thickness of the remaining coating is also measured to estimate the time until the next service interval. These readings are recorded in the maintenance log to track the performance of different coating formulations over time.
Component Life
Management of the maintenance schedule depends on predicting when the insulation will no longer provide sufficient protection. If thermal barrier degradation is not addressed, the underlying metal will overheat and lose its structural integrity.
