Abstract
In recent years the demand for smaller and thinner Nd-Fe-B permanent magnets has increased significantly. The poor flowability of the alloy powder when feeding and compacting has however been an obstacle to their fabrication. In order to improve the powder characteristics, Nd-Fe-B alloy powder was granulated by a spray drying method using a polyvinylalcohol (PVA) binder (0·1−0·5 wt-%). The granulated powder exhibited higher flowability with increased PYA content. The green bodies compacted under a magnetic field of 0·88 MA m−1 were debindered by heating in H2 and then sintered in a vacuum. The magnetic properties of a sintered anisotropic magnet prepared by adding 0·20 wt-% PVA are close to those btained if the spray drying process is not used. The conditions required for the spray drying of Nd-Fe-B alloy powder have been investigated. PM/0779
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