Bonded thin cylinder magnets using Sm-Fe-N anisotropic powder
Anisotropic bonded Sm-Fe-N thin cylinder magnets have been developed by an injection-molding technology using unsaturated polyester resin, because thin and high-performance magnets are needed in order to downsize the motor. A special point for forming was a control of the rate of shrinkage. A multioriented cylinder magnet of 0.8 mm thickness was made by an insertion forming an aluminum column of 18.4 mm diameter and 18 mm height. A radial-oriented cylinder magnet of 15 mm outer diameter, 16 mm height, and 0.5 mm thickness was also made.
Preparation and characterization of Sm2Fe17 alloy in LiF-CaF2-SmF3 molten salt
Abstract A suitable temperature range of Sm2Fe17 alloy formed only was chosen to investigate the electroreduction of Sm3+ on molybdenum and iron electrode in LiF-CaF2-SmF3 molten salt, which were studied by CV and SWV at different temperatures and concentrations of Sm3+. The reduction of Sm3+ to Sm0 on the iron electrode included two steps. Firstly, a soluble-soluble reaction appears at −0.33 V vs. Cr/Cr2O3 corresponds to the electroreduction of Sm3+ to Sm2+. The electroreduction of Sm3+ to Sm2+ is a reversible process, which is controlled by the diffusion of Sm3+ in the LiF-CaF2-SmF3 molten salt. Secondly, Sm2+ can be reduced at −0.78 V vs. Cr/Cr2O3 on the iron electrode in LiF-CaF2-SmF3 molten salt due to a lower activity of metallic samarium in the Sm2Fe17 alloy than that of samarium metal, and that makes samarium in Sm-Fe alloy more stable while that of Sm2+ could be not reduced by a molybdenum electrode. By experiment of potentiostatic electrolysis it was confirmed that the cathode product from LiF-CaF2-SmF3 melts at −1 V vs. Cr/Cr2O3 for 4 h is a thin layer metallic plate only composing Sm2Fe17 alloy.
Influence of milling conditions on magnetic properties of Sm/sub 2/Fe/sub 17/N/sub 3/ particles
Ball milling conditions were examined for the preparation of fine Sm/sub 2/Fe/sub 17/N/sub 3/ particles. The milling process with high ball/bottle volume ratio produced Sm/sub 2/Fe/sub 17/N/sub 3/ particles with low /sub i/H/sub c/ and 4 /spl pi/I/sub r/. The decrease in 4 /spl pi/I/sub r/ and /sub i/H/sub c/ were attributed to particle aggregates formed during the milling. The addition of a surfactant (e,g. polystearic acid) prevented aggregation in the ball milling, and yielded high-performance Sm/sub 2/Fe/sub 17/N/sub 3/ particles (4 /spl pi/I/sub r/: 14.1 kG, /sub i/H/sub c/: 9 kOe, (BW)max: 34 MGOe); cf. (BH)max=20 MGOe for typical epoxy-bonded magnets.