Nd–Fe–B permanent magnets (thick films) produced by a vacuum-plasma-spraying process

Abstract

Thick, hard-magnetic Nd–Fe–B films (∼1 mm) were deposited on different substrates (Cu, steel) by a low-pressure plasma-spraying process. The properties of the applied Nd–Fe–B powders (e.g., grain size, composition) and the conditions of the spraying process were optimized with respect to the mechanical and magnetic properties of the films. Film thicknesses up to 1.2 mm were achieved with good adhesive properties (bond strength>40 MPa). Cracks at the interface or within the films during the deposition process could be suppressed by adjusting the temperature profile of the substrate and controlling the deposition rate. Depending on the maximum temperature of the substrate and the thickness of the Nd–Fe–B films, either amorphous or microcrystalline structures were obtained. In general, the magnetic properties were improved by a postdeposition annealing treatment. Coercivities HcJ up to 16 kA/cm and isotropic remanences of about 0.6 T were achieved.

Effect of laser beam parameters on magnetic properties of Nd–Fe–B thick-film magnets fabricated by pulsed laser deposition

“…Consequently, thick-film magnets have been extensively studied. [1][2][3][4] In addition to the magnetic properties of a film magnet; its deposition rate and the simplicity with which it can be incorporated in a machine are important factors in determining its usefulness. From the perspective of this latter factor, 5 we have studied rapid fabrication of isotropic Nd-Fe-B thick-film magnets by pulsed laser deposition (PLD).…”

Magnetic properties of Nd–Fe–B film magnets prepared by RF sputtering

“…However, for applications as millimeter-sized motors and micro-machines applications, the film magnets with high-energy product and thickness of several tens of micrometers are required, and sputtering is one of the convenient and popular methods for producing thick-film magnets [5,6]. However, owing to the difficulties in obtaining a high deposition rate through conventional sputtering, Nd-Fe-B thick films have been also fabricated by other methods: YAG laser ablation technique [7], high-speed pulsed laser deposition [8], and vacuum plasma spraying [9]. However, the thick films fabricated by those methods are mostly isotropic on the magnetic property so that the remanence values are still low.…”

Effect of Preparation Condition on Magnetic Properties of ${\rm Nd-Fe-B}/\alpha-{\rm Fe}$ Multi-Layered Thick Film-Magnets Prepared by PLD Method

“…An increase in the remanence is expected to improve characteristics of small motors using a magnet-rotor with multi-polar pairs. As the remanence of isotropic thick film-magnets is lower than that of anisotropic ones [6]- [9], we prepared multi-layered nanocomposite film-magnets by the pulse laser deposition (PLD) method. The prepared film-magnets were composed of approximately 800 layers, and exhibited of 1 T and the coercivity of 430 kA/m [10].…”