Magnetic Particle Suspension
Magnetic particle suspension consists of a carrier fluid and finely dispersed ferromagnetic particles. It is used to check metal parts for cracks or damage.
Physical-Chemical Mechanism of Action
The magnetic particle suspension consists of a carrier liquid in which fine ferromagnetic particles (e.g., silicon dioxide) are dispersed. This suspension is sprayed or poured onto the test piece. The magnetic particles are attracted by a magnet and gather at cracks or damage in the material.
Metallurgical Relevance & Welding Risks
The suspension enables precise detection of microcracks that can result from welding processes. Missing or insufficient application of the suspension can cause smaller cracks to go undetected, leading to later material failure.
Workshop Practice & Instructions
Before testing, the test piece must be thoroughly cleaned and dry. The suspension should be stored in a closed container to ensure its stability. During application, an even layer should be spread over the part. The test piece is then placed under a magnet, and the suspension is allowed to drain slowly. The magnetic particles collect at cracks, which can be detected by visual inspection.