Sintered Nd2Fe14B tends to be vulnerable to corrosion. In particular, corrosion along grain boundaries may cause deterioration of a sintered strong magnet. This problem is addressed in many commercial products by adding a protective coating. Nickel plating or two-layered copper-nickel plating is the standard methods, although plating with other metals or polymer and lacquer protective coatings is also in use.

 

­The biggest and most important component in an MRI system is the strong magnet. The strong magnet in an MRI system is rated using a unit of measure known as a Tesla. Another unit of measure commonly used with strong magnets is the gauss (1 Tesla = 10,000 gauss). The strong magnets in use today in MRI are in the 0.5-Tesla to 3.0-Tesla range, or 5,000 to 30,000 gauss. Extremely powerful strong magnets -- up to 60 Tesla -- are used in research. Compared with the Earth's 0.5-gauss strong magnetic field, you can see how incredibly powerful these strong magnets are. Because of the power of these strong magnets, the MRI suite can be a very dangerous place if strict precautions are not observed. Metal objects can become dangerous projectiles if they are taken into the scan room. For example, paperclips, pens, keys, scissors, hemostats, stethoscopes and any other small objects can be pulled out of pockets and off the body without warning, at which point they fly toward the opening of the strong magnet (where the patient is placed) at very high speeds, posing a threat to everyone in the room. Credit cards, bank cards and anything else with strong magnetic encoding will be erased by most MRI systems. ­