Non-destructive testing in the high-temperature regime by using a magneto-optical film

The plane of a polarized light beam is rotated when the beam is transmitted through a magneto-optical film (MOF). Magnetic flux leakage (MFL) occurs around a crack when the specimen is magnetized and affects the magnetic domains. Therefore, a crack can be detected using a polarized lighting system and MOF. The crack detection ability depends on the domain width and saturation magnetization of the MOF. Also, crack detection at high temperatures is essential. The physical properties of the MOF at high temperatures were examined, and a nondestructive testing (NDT) method for detecting cracks at high temperatures was proposed in this paper.