Which type of magnetic particles is commonly used for highlighting surface defects?

Fluorescent magnetic particles are specifically designed for highlighting surface defects during magnetic particle inspections due to their unique properties. These particles contain fluorescent additives that make them glow under ultraviolet (UV) light. This glow enhances visibility and allows inspectors to easily identify even minute defects on the surface of materials being tested.

When a magnetic field is applied, these fluorescent particles align themselves along the surface-breaking defects, creating a clear indication of any discontinuities. The use of UV light in conjunction with these particles significantly improves the contrast and visibility of defects, making it easier for inspectors to detect issues that may not be visible under normal lighting conditions.

In contrast, other types of magnetic particles mentioned, such as electric magnetic particles, biodegradable magnetic particles, and conductive magnetic particles, are not primarily used for highlighting surface defects. Their applications differ and do not provide the same level of visibility or effectiveness in the context of magnetic particle inspection.