Effect of Magnetic Flux Concentrator on Magnetic Tunnel Junction Sensor for Magnetic Flux Leakage Testing

摘要

Magnetic flux leakage (MFL) testing is a popular method for detection of defects such as the metal loss due to the corrosion in steel bars located in reinforced concrete. The magnetic flux leak caused by the defect is then measured by a magnetic sensor. However, as the distance between the defect and magnetic sensor (lift-off) increases, the strength of the leaked magnetic flux drops significantly, making it difficult to detect. A candidate of highly sensitive magnetic sensor to detect defects at the condition of large lift-off is the magnetic tunnel junction (MTJ) sensor. In this research, the MFL testing was carried out by MTJ sensor with high sensitivity.