Non Destructive Surface and Sub-surface Material Analysis using Scanning SQUID Magnetic Microscope

摘要: Non Destructive Testing (NDT) based on magnetic technique for the investigation of surface and sub-surface material properties is carried out using a room-temperature sample Scanning Magnetic Microscope. The performances such instrument are well suited in field non destructive evaluation, thanks to good combination spatial resolution sensitivity its own superconducting sensor. The aim this work show capability advantages NDT Superconducting Quantum Interference Device (SQUID) sensors. We start by describing our SQUID Microscope terms performances, different techniques we can apply perform measurements, efforts have done improve detect weak variations. Two main applications presented. On high sensor at low frequencies, it consists excite with an alternating (AC). This applied subsurface flaws paramagnetic samples, instance, multilayer structures aeronautical interest. other application concerns detect, resolution, direct (DC) distribution ferromagnetic due their residual magnetization. In way, visualize domain particles. also exploited evaluate changing proximity crack initialization structural steels, subjected fatigue cycles.