Electromagnetic induced infrared thermography for fast detection of interfacial debonding in coating-metal multilayer structure

Coating-metal multilayer structure extends service life of metal-based components by attaching a functional coating to metal surface. Coatings protect the metal from external damage such as thermal, wear, corrosion and so on. This multilayer structure is widely used in industrial applications. One of the most common forms of failure is interfacial debonding between coating and metal substrate. Interfacial debonding defects reduce the bonding force between layers, which leads to coating failure and even safety risks. In order to better realize the integrity evaluation of coating-metal multilayer structure, in this paper, an electromagnetic induced thermography is proposed to enable fast detection of small interfacial debonding defects. The thermal barrier coating system (TBCs) is selected as typical coating-metal multilayer structures. Using eddy current heating as an internal heat source and introduced magnet yoke to confine heating area, the detection of Φ1 mm interfacial debonding defects is firstly achieved in 0.8 s. Furthermore, this method is employed to detect the interfacial debonding between glass fiber reinforced plastics (GFRP) and alloy substrate, thereby reinforcing its viability. Comparing to external heating source, electromagnetic induced thermography shows great advantages in accurate and efficient detection, which is a great inspiration for integrity evaluation of coating-metal multilayer structure.