Isotropic Nd-Fe-B thick-film magnets applied for micro-rotors prepared by PLD method

The flexibility of magnetization of isotropic thick-film magnets enabled us to enhance the torque of a millimeter-size motor comprising a multi-polar magnetized rotor compared to the torque of a miniaturized motor using an anisotropic Nd-Fe-B sintered magnet. In order to upgrade the torque of the small motor further, increase in the remanence value of the isotropic films is indispensable. In this study, therefore, we prepared nano-composite Nd-Fe-B thick-films by using a high-speed PLD (Pulsed Laser Deposition) method with the deposition rate of approximately 40 μm/h. Resultantly, use of additive (Zr or Nb) was effective to enhance the coercivity value of Nd-Fe-B thick-film magnets with Nd-poor composition, however it was difficult to increase the values of remanence. In order to apply the thick films to a micro-rotor, investigation on several experiments related to mechanical property was also carried out.