Neodymium magnets and ferrite magnets dominate the market of permanent magnet motors magnets. Neodymium arc magnets are used in high performance motors or motors with compact size, while ferrite arc magnet in relatively large motors with relatively low torque requirement. Besides, Sm2Co17 magnet (2nd generation of rare earth magnet) always remains in existence in motor application because of its excellent magnetic strength and temperature stability. Neodymium magnets are prone to corrosion and therefore need surface protection. Common coating types include Nickel (NiCuNi), Zinc, Epoxy and Passivation (Phospharization). It’s important to note that nickel is a ferromagnetic material and NiCuNi coating has a slight effect on the magnetic flux. Zinc coating is the best option when it comes to cost but it provides no better corrosion resistance than Nickel and Epoxy coating. Epoxy coating is an organic coating and provides the best corrosion resistance. NdFeB magnet nano coating is characterized by its excellent corrosion resistance and has become an alternative to nickel and epoxy coating.