JPS6013995B2 - Manufacturing method of oxide permanent magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an oxide permanent magnet, and particularly to an improvement in a strontium ferrite magnet having a magnetoplumbite structure.

Since ferrite magnets are inexpensive in terms of raw materials and manufacturing costs, the production volume of ferrite magnets is rapidly increasing.

On the other hand, recently, there has been an increase in the use of magnets, especially in rotating equipment with large demagnetizing fields, and there is a demand for high-performance magnets with high coercive force. After the strontium ferrite magnet was announced in the Tsubaki Kosumi 39112$G publication, various improvements have been proposed and it has been put into practical use, and it has magnetic properties that are one step better than the barium ferrite magnet.

However, in any ferrite magnet, when trying to obtain a high coercive force (Hc), the remanence (Br) and the maximum energy product ((BH)max) become low, and conversely, Br, (BH)max becomes high. If produced under such conditions, the holding force would be extremely low, and it was quite difficult to produce a high-performance ferrite magnet with high properties.

An object of the present invention is to provide a magnet with higher Br, BHc and (BH)max than conventional strontium ferrite permanent magnets. The present invention relates to .nF of the general formula S
The main component is e203 (where n = 5 to 6), and CaC1
2 to 1. Mix by adding skin t・% or less (not including 0),
Temporarily calcined, then coarsely and finely crushed to reduce the average particle size to 0.
．． This is a method for manufacturing a strontium ferrite permanent magnet, characterized in that the magnetic field is formed to have a magnetic field of 8 Am or less, anisotropically formed, and then fired.

As a result, BrZ4200 (Gauss), 8Hc222
A high performance strontium ferrite permanent magnet having the characteristics of 00 (Oersted), (BH) ma x 24.4 x 1 (Gaussersted) is obtained. The present invention will be described in detail below with reference to examples.

Example 1 Commercially available industrial strontium carbonate (SrCQ) powder with a purity of SO. 025%, Zno.
Weighed Fe2Q/S as the main raw material so that the molar ratio of
C12 was added in an amount of 0 to 1.0% and thoroughly mixed.

Thereafter, the mixture was temporarily held at 123 piC for 1.5 hours, coarsely pulverized, and then finely pulverized using a pulverizer. At this time, the grinding time by the grinder was changed, and one with an average particle diameter of 0.7 to 0.8 rm and one with an average particle diameter of 0.90 to 0.95 m (both measured by gas permeation method). Two types of sample slurries were obtained.
After that, each sample was magnetically formed into a disk shape under the same conditions.
After firing at 126 mm for 2 hours and processing into a block for measurement, the magnetic properties were measured. The results are shown in FIGS. 1 and 2. The one in Figure 1 has an average particle diameter of 0 before magnetic field forming.
．． In the case of a sample with a diameter of 7 to 0.8 m, Figure 2 shows a range of 0.9 to 0.
．． The case of a 95 pm sample is shown. 'As shown in Figure 2, even when the particle size at the time of crushing is 0.9 mm or more,
CaC12 improves both Br and BHc compared to the case without addition, but Br does not exceed 4100 Gauss and (BH)m
ax is 4. Noke. G. It was about ■.

In contrast, as shown in Figure 1, the average particle diameter is reduced to 0 during pulverization.
．． When it is 8 fm or less, Br; 390 without additives
Compared to the one showing e(BH)max:395 for 0 Gauss BHc=210, CaC12 is 1. In the case of adding up to % of
has become significantly larger.

Br shows a peak at 0.75M%, and 8Hc shows a peak at 0.75M%.
It shows a peak at 5 wt%, and at 0.5-0.75 wt% (
BH) max is 4.59M. G. The ratio was extremely large. As is clear from these results, the addition of CaC12 improves both the gunwale and 8Hc, and particularly when the finely pulverized particle size is 0.8 mm or less, the properties are significantly improved.

That is, by adding 1.0% or less of CaC12 and setting the finely pulverized particle size to 0.8 mm or less, the magnetic properties can be significantly improved. The reason why the addition of CaC12 was set to 1.0% or less (not including 0) is that if it exceeds 1.0%, Br, BHc, and (BH)max will deteriorate as shown in Figure 1. The reason why the particle size is set to be 0.8 m or less is because, although the effect of CaC12 can be seen to some extent if it is larger than that, no significant improvement in properties is observed.

As a comparative reference example, in the same process as in the above example, first grade CaC was used as a reagent instead of CaC12 as an additive.
Q is added to increase the average particle size during pulverization from 0.85 to 0.9.
Figure 3 shows the results when the value was set to 0 mm. Example 2 The main raw materials were blended in the same manner as in Example 1 so that the molar ratio of Fe203/Sr0 was 5.55 and 5.60, and CaC
The amount of addition of 12 (i) no addition (ii) 0.5M% (ii
l)1. Added to skin t%, temporary phosphorus temperature 121 pi○
, 125 mm for 2 hours, each sample was finely pulverized to an average particle size of 0.75 to 0.8 r, and magnetic field molded in the same manner as in the previous example.
It was fired at 0°C.

The magnetic properties at this time are shown in FIGS. 4 and 5.

FIG. 4 shows the case where the temporary scale temperature is 121 pi○, and FIG. 5 shows the case when the temporary scale temperature is 1250°C. In the figure, o...o indicates a molar ratio of 5.60, and... indicates a molar ratio of 5.55. Br. due to the difference in temporary phosphorus temperature. A difference is seen in 8Hc.
CaC12 does not show much effect on 8Hc at a temporary scale temperature of 1210°C, but it improves Br and (BH)n loss x
Raise it to the middle of the day. In the case of temporary key abundance 1260qo, B
Both r and 8Hc have been improved, and (BH) max has been raised in the middle. In other words, it can be said that CaC12 is effective even within the range of variation in molar ratio and variation in preliminary temperature during mass production.

The present invention has been described above using examples.

Addition of CaC12 does not lower BHc, but rather improves it by about 0.5%, increases density, and improves Br. In particular, by finely pulverizing CaC12 to a particle size of 0.8 m or less, the effect of CaC12 becomes remarkable, and the properties of CaC12 are improved. Academic understanding of the present invention is insufficient, but C
This is thought to be due to the fact that aC12 becomes a liquid phase at a relatively low temperature.

[Brief explanation of the drawing]

Figures 1 and 2 show the magnetic properties of Sr ferrite magnets according to examples for explaining the present invention. In particular, Figure 1 shows the average particle size during pulverization of 0.7 to 0.8. Figure 2 shows the relationship between the amount of CaC12 added and the magnetic properties when the thickness is 0.90 to 0.95 m. FIG. 3 shows the characteristics of a comparative example using CaC03 as an additive. FIGS. 4 and 5 show the influence of the molar ratio and the pseudo dawn temperature on the magnetic properties when CaC12 is added. Figure 1 Figure 2 Figure 3 Figure 5 Boar Figure

Claims (1)

[Claims] 1 molar ratio of Fe_2O_3/SrO is 5.0 to 6.
In the production of oxide permanent magnets, iron oxide powder or powder that can become iron oxide through sintering reaction and powder that can become strontium oxide through sintering are weighed and mixed to satisfy the above molar ratio. Calcium chloride (CaCl_2) of 1.0% or less (not including zero) is added and mixed, then calcined, then finely pulverized to an average particle size of 0.8 μm or less, and then press molded and baked. 1. A method for producing an oxide permanent magnet, characterized by: