| 摘要 |
PROBLEM TO BE SOLVED: To provide the manufacturing method of fine magnetic metal powder, which prevents the sintering of particles when heat treatment is performed in reducing atmosphere and has the excellent magnetic properties keeping the needle shape. SOLUTION: At first, the temperature of needle-shaped fine powder containing oxy iron-hydroxide as a main constituent, is increased to a specified temperature within arrange of 400-620 deg.C in nonreducing gas. Then, at the specified temperature, the mixed gas of reducing gas and the nonreducing gas is intruduced, and heating treatment is performed. In the process of the heating treatment, the mixing ratio of the nonreducing gas is made small at the initial period, and the mixing ratio of the reducing gas is raised in stepwise. For example, the mixing ratio of the nonreducing gas at the initial stage is set at 33 volume % or less and the ratio finally set at 50 volume % or more. As the nonreducing gas, the nonreducing gas comprising an element, whose atomic number is 7 or more, is used. Then, the slow deoxidization is performed. |
