Improvement of magnetic interface coupling through a magnetic coupling gel

Surface measurement of magnetic properties is potentially a very advantageous technique for nondestructive evaluation. The effect of a magnetic coupling gel on surface magnetic measurement, is reported in this paper. Test results under three interface conditions are presented and compared. It was found that the magnetic gel reduces the variability of the measurement by improving the magnetic interface coupling between the sensor and test specimen. A simple model of a magnetic circuit is analyzed to show the coupling function of magnetic gel. From these results, it is deduced that the magnetic coupling gel plays an important part in improving reliability of the magnetic measurements.