High-resolution non-destructive detection of grinding burns with NV diamond quantum magnetometer

Grinding burns compromise the mechanical integrity and fatigue life of high-performance mechanical components. Traditional detection methods (nital etching, microstructural imaging, etc.) are either destructive, hazardous, or unsuitable for rapid inspections. Usual magnetic nondestructive testing (NDT) techniques offer an alternative but often fail to isolate the specific effects of grinding burns from other material properties. This study introduces a novel NDT approach utilizing Nitrogen-Vacancy (NV) centers in diamond magnetometer for the detection of grinding burns. NV centers are quantum defects in the diamond lattice that enable chemical-free, contactless quantitative vector magnetic field measurements with high spatial resolution and sensitivity and no calibration effort. NV technology was applied to detect grinding burns, successfully identifying all burns on a 16NiCrMo13 gearwheel regardless of their size or intensity. A preliminary magnetization of 20 mT was sufficient to detect even the weakest burns. Measurements over 10 × 10 mm areas were completed in minutes, with effective measurement times on the order of one second. This approach eliminates the need for hazardous chemicals and offers precise magnetic characterization, opening doors to large-scale industrial deployments.