Prepn. of ferrite permanent-magnet materials

Abstract

This invention relates to a method to prepare permanent ferromagnetic materials. It includes following steps: addition of adhesives into ferro oxide magnetic materials; moisture adjustment; molding, magnetization and compression of moisture-adjusted mixture and sintering at high temperatures. The characteristics is that, the ferro oxide magnetic materials are chosen from one of several species of ferro oxide, manganese-zincum ferrite, manganese ferrite, magnesium ferrite and copper-zincum ferrite, and metal nitrite weighing 1~2wt% of the total magnetic materials mentioned above is also added. The adhesives include thermoplastic resin containing keto-groups and weigh 0.1~0.2wt% of the total mixture. The moisture content in the mixture during moisture adjustment is 0.2~0.4wt%. Finally, the sintering is carried out at a temperature between 350~450 deg. C. This invention has the outstanding specificity that low-temperature sintering can be realized by modification of raw materials and adhesives and thus cost is cut down; orientation can be enhanced and magnetic properties can be optimized.

Description

technical field [0001] The invention relates to a preparation method of a ferrite permanent magnet material, in particular to a preparation method of an oxide magnetic material system permanent magnet formed by a dry molding method. Background technique [0002] At present, the manufacturing methods of permanent magnets are roughly divided into dry forming methods and wet forming methods. In the wet forming method, (such as Chinese Patent No. 03116206.1), since the permanent magnet pellets are easy to rotate in the dispersion medium, the magnetic material can obtain good orientation, thereby obtaining good magnetism. However, since the dispersion medium must be discharged out of the molding space (outside the mold cavity) during press molding, the productivity will be reduced; in addition, a large mold structure is required, which increases the cost of equipment. The dry molding method is to fill the dry state of the permanent magnet material powder into the molding space (...

AI Technical Summary

Problems solved by technology

However, the main problem of this method is that the process is complicated, and it is easy to cause the formation of ferrous ions after high temperature sintering, and the resistivity decreases.

Especially for the case where the ambient temperature is not particularly high, the cost is increased