JPS59214206A - Manufacture of permanent magnet material - Google Patents

Abstract

PURPOSE:To avoid voids, crackings and breakage of a molded magnet body by a method wherein a plurality of organic materials are combined and the maximum value of defatted quantity at the specific temperature within the defatting temperature range is made less than approximately 20 times of the minimum value in heated quantity reduction ratio. CONSTITUTION:Al-Ni-Co system alloy powder is mixed or kneaded with a binder and then subjected to injection molding. Then the binder is defatted. Organic compound is used as the binder. The organic compound is composed of the combination of at least two kinds among thermoplastic resin, thermosetting resin, natural resin, rubber, elastomer, lubricant and plastsizer. Suitable organic materials are combined and the maximum value of defatted quantity at the specific temperature or temperature range within the total defatting temperature range is made less than approximately 20 times of the minimum value in heated quantity reduction ratio. With this constitution, the defatting is performed without producing voids, crackings and breakage in the surface or the inside of the molded body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alnico permanent magnet material obtained by a powder metallurgy method, and more specifically, a kneaded material consisting of the permanent magnet powder and a binder is molded with high dimensional accuracy by an injection molding method. The present invention relates to a permanent cornerstone material which is made into a molded body, which is impregnated with specific elements to obtain high-density sinterability, and which has excellent magnetic properties Z.

Alnico-based permanent cornerstone is generally manufactured by a casting method.

Manufacturing conditions vary depending on the composition, but for example, the weight ratio
QA17-12%, Nj 10-20%, Co2B
~50% pCu 1-7%, Ti 4.0-5.
5% as the main component and at the same time as additives 0002~
0.2%, 801-1.0%, NbO, 5-60%, Ti4. For alnico magnets containing o ~ 5.5% richness and the remainder substantially consisting of Fe, the pouring temperature is approximately 1700°C, and after solution treatment at 1200°C or higher, the cooling rate is o, i ~ 0,
After cooling in a magnetic field at 9℃/S, approximately 10 to 50
Hold in a magnetic field at a constant low temperature of 550~
Magnetic materials are obtained by aging at around 650°C.

Powder metallurgy technology was developed as a method for manufacturing general metal parts, and has been widely applied to automobile parts, electrical equipment parts, mechanical parts, etc., and its effects are well known. If the powder metallurgy method, that is, the sintering method is applied to alnico alloys (hereinafter referred to as this alloy), the process of solution treatment 1 of the molten material becomes an extremely simple process of powder mixing, molding, and sintering. It is possible to obtain a magnet material having a desired shape, or to finish it into a shape that is at least close to the desired shape.

However, even when using this alloy permanent magnet material not only by melting and casting, but also by sintering using normal press forming, it is difficult to manufacture products with complex shapes or products that require a high degree of dimensional accuracy. In some cases, it is necessary to finish and process the material.

In order to manufacture the permanent magnet material of the present invention into products with complex shapes and products requiring high dimensional accuracy,
One of the features is that the injection molding method is applied to the molding process. As is well known, the injection molding method has demonstrated its power in the field of plastic molding, and the tolerance is ±0.0.
A molding precision of about 1+a can be obtained. In order to apply the injection molding method Z to this alloy, it is important to create mold ink minox (compound) with a high content of metal powder, and for this purpose, the following knowledge is necessary. . That is, (1) 65 to 85% of the theoretical density
(2) selection of a binder that matches good fluidity, molding strength, and degreasing properties; and (6) selection of other additives that satisfy these conditions. We were able to obtain a compound suitable for injection molding.

In addition, in order to use this alloy as a permanent magnet material, it is necessary not only to obtain a high degree of dimensional accuracy through injection molding, but also to have excellent arsenic properties. Generally, in magnetic materials manufactured by sintering, there is a close relationship between density and magnetic properties; for example, residual density (Br) is proportional to density. Therefore, in order to obtain a material with excellent magnetic properties, it is important to make the density as close to the theoretical density as possible.

The composition of the present alloy is not particularly limited, and includes the basic composition and additive system of known alnico magnets. That is, At 6 to 12% by weight.

N110-28%, 005-35%, C110-7%,
Tin~8%.

Other additives include CO~0.2%, So~1%, N
It may contain 0 to 4% b, and the remainder is Fe, and is known to have excellent magnetic properties. In addition, change ■ to 0
It has also been reported that by adding 1 to 0.5%, the coercive force 1l-1c and the maximum magnetic energy product (BH) m are significantly increased (% Kosho 47-44409).

That is, regardless of the composition of the alnico magnet, the present invention applies to injection molding of alnico permanent magnet material after mixing or kneading powder of the cornerstone material with a binder. This is a permanent magnet material that is characterized in that it is made by debinding, followed by debinding and sintering.

By the way, when applying the injection molding method to this alloy, the above (1)
), (2) and (6), the selection of organic materials including the degreasing process is extremely important.

Although polystyrene and the like are often used as organic materials for injection molding, most synthetic resins are used, and each has its advantages and disadvantages. The organic material added for molding is generally a combination of thermoplastic resin, lubricant, and plasticizer, but thermosetting resin, natural resin,
Rubbers, nidistomers, etc. can also be used. Among these, the selection of the thermoplastic resin as the main material is particularly important, and the cost of the resin, affinity with the alloy (wetting), heat fluidity (formability), thermal decomposition, decomposition residue components, etc. This is a particularly important point in this molding method.

In the present invention, as a result of various studies on organic materials to be applied to the present alloy, it was possible to obtain a suitable permanent magnet material by the following method.

(1) When the present alloy material powder is mixed or kneaded with a binder, injection molding is performed, and the binder is removed and sintered to obtain a permanent magnet material.

At least two types of organic materials are used as organic materials.

(2) As the organic material, at least two of thermoplastic resins, thermosetting resins, natural resins, rubbers, elastomers, lubricants, and plasticizers are used in combination.

That is, the binder used is binder-removed (degreased)
It is necessary to decompose or volatilize in the process, and organic compounds are used for this purpose. The binder may be a single yuzu type, but in order to perform the binder removal process smoothly, prepare multiple binders that serve as binders, erasers, and plasticizers, and prepare differential binders in advance as shown in Figure 1. The heating loss curve is measured using a thermal analyzer, etc., and then, by appropriately combining these multiple binders, the heating temperature gradient is shown in Fig. 2. Details will be described in Examples. It is desirable to mix so that a substantially constant amount of fat is removed. Depending on the type of binder, surface-modifying particles may be added to improve wettability with the present alloy.

Furthermore, a medium may be used in special cases.

The binder referred to in the present invention includes organic compounds that share each of the above functions and organic-inorganic complex compounds such as organic silicates and organic titanates.

For the manufacture of permanent magnets based on the present alloy system, conventional techniques such as sintering bath formation treatment and Omai aging treatment can be used. Of course,
It is necessary to select and use an alloy powder having an appropriate particle shape and particle size distribution in order to obtain the highest possible sintered density after sintering.

For that purpose, Antriazen's 2P = (x 7'
D) It is desirable to have a particle size distribution 2 close to m (where P is the content of a certain particle size X or less, D is the maximum existing particle size, m-/2 to 4). -! In addition, the degreasing speed depends on the thickness of the molded body, the atmosphere, and the type of binder, but it is approximately 2°C/h to 10°C/'h in the temperature range from the binder's decomposition or volatilization start temperature to the end temperature. degree is suitable. If the degreasing rate, that is, the rate of temperature increase, stops suddenly, foaming, cracking, and cracking will occur on the surface and inside of the molded product, and the product will not be finished.

The sintering temperature is generally 1200-1400℃, but in order to speed up the sintering and improve the sintered density, sintering should be performed at 1500-140℃. . Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 At 7.0% by weight. Ni 15. Co50. Cu4. Ti
5°Nbo, 1. V o1 remainder Fe x r) formed 100 )' 7 s- or less alloy powder) IDP
E, a binder consisting of APP (high molecular weight) and APP (low molecular weight), and the blending ratio powder:) IDPH:APP
(Polymer): APP (Low molecule) = 98: 5: 9
: The mixture was heated and mixed at a ratio of 3, and a cylindrical molded body with a diameter of 2020-1 Ot was obtained using a scree type injection molding machine. Next, degreasing was performed at a temperature increase rate of 3°C/h from 140°C. FIG. 2 shows the degreased state of the organic material used in this example as a function of heating loss versus temperature. The ○ mark in the diagram is the first
These are calculated values obtained from the thermal decomposition curves of each polymer at a temperature increase of 2° C./jlII+ shown in the figure.

Cu in the figure is an actual value measured after degreasing an actual molded product.

It can be seen from FIG. 2 that the amount of degreasing changes approximately linearly with respect to the degreasing temperature. On the other hand, when a molded body is made using only APP (high molecular weight) and paraffin wax (68/66) and degreased, as expected from Fig. 260
℃ and 180 to 210℃, degreasing progressed rapidly, and the molded product was accompanied by clearing and foaming.As a result of various studies on degreasing conditions, the following results were obtained, depending on the wall thickness and shape of the molded product. I got it. That is, by appropriately combining a plurality of organic materials selected from thermoplastic resins, lubricants, and plasticizers, the degreasing can be carried out within the entire degreasing temperature range from the degreasing start temperature to the finish temperature of these organic materials.

It is necessary to control the amount of degreasing so that the maximum value of the amount of degreasing at or within the specified temperature is approximately 20 times or less, preferably approximately 10 times or less, of the minimum value in terms of heating loss ratio. When the heating loss ratio exceeded 20 times 9, even when the temperature was raised at a slow rate of about 2°C/'h, a small amount of co-killen was generated, but below 10 times, the above-mentioned temperature increase caused the generation of co-killen. It was possible to remove fat without causing any damage.

Next iteration, 1100℃Xlam+13001:X2 in vacuum
Sintering was performed at h. The true nitrogen degree at this time is 1O-4to
It was below about rr. 1000℃X1Ojllll
The purpose of this retention is to promote the reaction between C from the binder, which is thought to remain in a very small amount in the powder, and 02 in the powder. After sintering, solution treatment was performed at 1250°C in the field at 20000e, followed by long-term heat treatment at 600°C.

The obtained magnetic properties are Br=7600a, HC=1
350ue.

(BH) m = 5.2 Ivy in MGOe.

Also, the dimensional accuracy for 40 samples is ±0.05w
I encountered the following.

Example 2 At18. Ni14. Co24. The magnetic properties of a magnet material obtained by processing an alloy powder of 100 mesh or less consisting of Cu5 and the balance Fe in a process similar to Example 1 are as follows:
Br=12KG, HC=6000e, (B)l
) may=5.0 MG (Je.) The dimensional accuracy for the 40 samples was also ±05- or less.

As is clear from the above examples, the material of the present invention is a magnetic material with excellent sinterability, dimensional accuracy, and magnetic properties.

[Brief explanation of the drawing]

FIG. 1 shows thermal decomposition curves of polymer materials, lubricants, and plasticizers measured using a differential thermal analyzer. FIG. 2 is a degreasing curve of the present alloy compound using a plurality of organic compounds. O 1 Figure O 'l Figure jE sword (jiCn

Claims (1)

[Claims] In a method for producing an alnico-based permanent magnet material, the powder made of the magnet material is mixed or kneaded with an organic material, injection molded, and then degreased, sintered, and heat treated. By appropriately combining a plurality of electrical materials selected from , degreasing, and plasticizers, it is possible to achieve a specified temperature within the entire degreasing temperature range from the degreasing start temperature to the end temperature of the organic material. A method for producing a permanent magnet material, characterized in that the maximum value of the amount of degreasing in is approximately 20 times or less of the minimum value in terms of heating loss ratio.