Non-destructive technique to detect local buried defects in metal sample by scanning microwave microscopy

Based on the skin effect, our recent developments using scanning microwave microscopy lead to propose a non-destructive method to detect located buried defect in metal samples like stainless steel. A 3D tomography is possible by taking advantage of microwave measurement, using a vector network analyzer in bandwidth frequencies, and the nanometer resolution positioning capabilities with atomic force microscopy. At each used frequency, an incident electromagnetic wave is sent to the sample and the reflected wave gives information on a specific depth layer in the material. With diagnostic tools of nanotechnologies (SEM, AFM, etc.), different stainless steel samples (from Areva NP) presenting local buried defects are studied. The materials used in this study are conventional stainless steels like a 304 stainless steel which is the most versatile and widely used stainless steel. The results of the tomography applied on these samples are in accordance with the skin effect equation.