Which material is most commonly utilized as a magnetic powder in magnetic particle testing?

The most commonly utilized material as a magnetic powder in magnetic particle testing is iron oxide. This is primarily due to its ferromagnetic properties, which allow it to be effectively attracted to magnetic fields. During the testing process, iron oxide is used because it is capable of agglomerating and forming visible indications at areas of discontinuities on the surface of a magnetic material.

Iron oxide is finely divided and can either be applied dry or suspended in a liquid carrier, often in a form that enhances visibility under ultraviolet light or daylight. It possesses the ideal characteristics for detecting surface and near-surface defects in ferromagnetic materials, making it essential in non-destructive testing techniques to ensure the integrity and safety of components.

In contrast, the other materials listed do not possess the same ferromagnetic characteristics or practical applications for this specific testing method. They may be useful in other contexts but do not serve the primary role in magnetic particle testing as effectively as iron oxide does.