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This is an attempt to explore feasibility to develop an open gradient magnetic separator for mixed powder under dry condition. The magnetic separator proposed here is intended to separate the ferromagnetic particles from mixed powder, being based on the consideration that the separation efficiency depends upon changing systematically the particle sizes and its surface properties such as hydrophobicity and cohesive force. As a result, it is found that the separation efficiency became lower as the particle size of the mixed particles became smaller. This is supposed to be caused by the cohesive force between the particles of ferrite and alumina which are easily affected by the magnetic drag force and the gravity difference. But the result is encouraging because the separation efficiency will be enhanced if the magnetic gradient is increased and if air flow in the separator is optimized in the appropriate system of the open-gradient magnetic separator proposed in this paper.

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This paper describes a wireless hydrogen sensor that employs the resonance frequency change of PdNi-coated magnetic ribbons. A Pd0.9522Ni0.0478-coated magnetic ribbon exhibits a monotonous increase in resonance frequency with increases in hydrogen concentration. Because Pd absorbs hydrogen selectively and expands, the magnetic anisotropy in the ribbon changes from transversal single axis to isotropic in-plane. This weakens the ΔE effect and thus increases the resonance frequency. Consequently, PdNi-coated magnetic ribbon is confirmed as a sensitive wireless hydrogen sensor device.

We prepared large single domain of DyBaCuO (Dy-123) superconductor for future applications such as a superconducting flywheel for energy storage system, magnetic separation, and a bulk magnet. Dy-123 superconductors are expected to have high and trapped field properties. Melt-textured single domain of Dy-123 system superconductor about 48 mm in diameter and 10 mm in thickness was fabricated with a seeding and temperature gradient method in air. Dy-123 and Dy-211 powders were mixed in a molar ratio of 1:0.3, and Ag 2 O of 10 wt% and Pt of 0.5 wt% were added to the mixture. The maximum trapped magnetic field over the bulk was approximately 0.2 T at 77.3 K. We also discussed mechanical properties such as the bending stress, the hardness and the surface roughness of the Dy-123 bulk. Mechanical property results showed important information for evaluating Dy-123 bulks.