Naked eye visualization of defects in ferromagnetic materials and components

• Nondestructive detection of defects in materials and component is vital in industries.
• Visual detection of defects with naked eye is extremely user friendly.
• We have developed a new approach to visualize defects by naked eye.
• The new approach enables detection of defect shape, location and dimensions.
• It is simple, user friendly, fast and ideal for inspection of large area surfaces rapidly.

We report a methodology to visualize defects by naked eye using magnetically polarizable nanoemulsions stabilized with different surface active species. The response of the nanoemulsions to the leaked magnetic flux from a defective region is exploited to locate the defect. In the presence of leaked magnetic flux, the nanofluid shows a visually perceivable color change due to the changes in the interparticle spacing within the self-assembled nano-arrays. We discuss the methodologies to detect defect morphologies and the underlying physics. The detection methodologies to quantify the defect shape, location and dimensions are validated in specimens with simulated defects of different geometries. The notable advantage of this technique is that it is simple, user friendly (does not need any processing of electronic data), fast and ideal for inspection of large area surfaces rapidly. This technique is ideal for the detection of surface and subsurface defects such as voids, cracks and inclusions in ferromagnetic materials.

Schematics of the specimens and the corresponding photographic images of nanofluid sensor. The defective regions of each sample are encircled.Figure optionsDownload as PowerPoint slide