OP磁石に関する研究(第3報) : OP磁石に対する第2族元素の燐酸塩および砒酸塩の影響

概要

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An attempt to improve magnetic and mechanical properties of OP magnet was made by adding phosphates and arsenates of the element of Group II. Oxides have often been added for such purpose. But we used the above-menti oned salts instead of oxides in expectation of getting the effect surely, because these salts were more stable than oxides up to about 1000°C, the sintering temp. for OP magnet. The experimental results obtained were as follows : 1) These salts can be added with same effect either before or after prefiring. 2) Addition of BaHPO4 by 2 wt. % enables us to get such OP magnet as Hc=1450 Oe., Br=2700 gauss and (BH)max=1.4×106 gauss⋅Oe. In an optimum condition, we have OP magnet of (BH)max=2.2×106 gauss⋅Oe. Also the mechanical property of these OP magnet is better than that of original one. 3) Addition of 1% Ba2As2O7 make OP magnet possible to have the characteristics of He=800 Oe., Br= 3800 gauss and (BH)max=1.5×106 gauss⋅Oe. The mechanical strength of this OP magnet is two or three times of the strength of the magnet without addition. 4) The phosphates not only promote the sitering of OP magnet, but also precipitate in crystal grain or at grain boundary to increase coercive force of the magnet. The arsenates promote the sintering more remarkably than the phosphates do.
社団法人粉体粉末冶金協会の論文