JPS5931205B2 - permanent magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the residual magnetic flux density of a so-called RCO-based permanent magnet alloy, which is mainly composed of a rare earth monocobalt-based alloy.

Intermetallic compounds (RCO) of rare earth metals (Y, Pr, Sm, Ce metals, etc., hereinafter collectively referred to as R) and transition elements, especially Co, are used because the RCO system has extremely high magnetocrystalline anisotropy. Permanent magnets are attracting attention.

The most suitable manufacturing method is to grind the RC05 melt into a fine powder close to a single magnetic domain, then anisotropically mold and sinter it in a magnetic field.The sintering methods include direct sintering and epoxy etc. A method of bonding using a resin as a binder is known.
However, although this RCO-based permanent magnet has a very high coercive force (BHC), its residual magnetic flux density (Br) is not so great, and the ratio (B, /BHCO) is close to 1.

Therefore, although it is very effective for flat shaped magnets, it has the drawback that it cannot exhibit its characteristics in rectangular shaped magnets. Also, the cost is high due to the high price of rare earth metals.
There are significant restrictions on usage. The present invention was made in order to eliminate such drawbacks, and its gist is that by mixing an appropriate amount of RCO-based permanent magnet powder with alnico-based magnet powder, the high residual magnetic flux density of alnico magnets and the high residual magnetic flux density of RCO-based magnets can be achieved. Combined with high coercive force, the Br/BHC ratio is approximately 1.2 to 5.
It is intended to provide a permanent magnet of about 100%. As is already known, Alnico magnets are Al-Ni-Co
This type of permanent magnet has a very high residual magnetic flux density compared to the coercive force, and the Br/BHC ratio is close to 10. Furthermore, although the ratio of ferrite magnets is close to 1, the product of magnetic energy is small. In the present invention, the Br/BHC ratio is around 1.2 to 7,
Provides a magnet with a large magnetic energy product, and also has an RCO
Since the cost is lower than that of other magnets, the applications of the magnet, which was conventionally effective only for flat magnets, can be expanded widely. The RC05 permanent magnet used here has a weight ratio of rare earth metals such as Sm, Pr, and Y of 30 to 3.
The balance of 9% is substantially Co (or a part thereof is Fe, N
i, substituted with transition elements such as Mn) are suitable,
On the other hand, alnico magnets have a basic composition of, for example, A16-1
2%, C025~45%, Ni12~20% balance Fe
It can be used in all so-called alnico magnets in which a part of Fe is replaced with Cu, Ti, etc.

The mixing ratio of alnico magnet powder to RCO5 powder varies depending on the properties (depending on the components) of each magnet powder, but as the amount of alnico magnet powder increases, the residual magnetic flux density Br increases, and the coercive force BHC increases. decreases. Br/BH
The mixing ratio that maintains the C ratio at 1.2 to 7 and makes the gist of the present invention clear is that the Alnico magnet powder has a weight ratio of 10 to 75%. That is, below 10%, the Br/BHC ratio is almost 1.
If it exceeds 75%, the coercive force decreases rapidly, and the ratio approaches 10, making no difference compared to alnico magnets. Next, an example will be described.

Melting an alloy consisting of 33.5% Sm and the balance cobalt,
After heat treatment (3 hours at 115°C), this was made into a fine powder using a ball mill.

This is called RCO5 powder. Next, CO34%, Nil4
．． An alnico magnet alloy consisting essentially of Fe, 7% Al, 4% Cu, and 5% Ti was melted and an ingot was produced by forced cooling. The ingot was solutionized at 1,300°C, tempered at 570°C for 20 hours in a magnetic field of about 20,000 e, and then ground in a ball mill to give a
μ alnico magnet powder. Next, mix appropriate amounts of this RCO5 powder and Alnico powder, add epoxy resin powder at a weight ratio of 3%, and press-form this in a magnetic field.
A magnet body was manufactured by curing the epoxy resin at ℃. R.C.O.
The mixing ratio of No. 5 powder and Alnico powder and the magnetic properties of the magnet body were as shown in Table 1.

As described above, according to the present invention, the following excellent effects can be obtained.

In other words, the magnetic properties of conventional permanent magnets are mostly determined by composition and heat treatment, so in order to meet the magnetic properties required by the application, the manufacturing process must be significantly changed, making mass production difficult. However, according to the present invention, various demands for magnetic properties can be met without changing the manufacturing process by simply changing the mixing ratio of magnetic powder. This greatly improves mass production, and also improves Sm-C, which has high raw material costs.
Since the amount of O-based rare earth intermetallic compound can be reduced, costs can be reduced.

Claims (1)

[Claims] 1. An alnico magnet composition mainly composed of aluminum, cobalt, and nickel is added to an intermetallic compound magnet composition composed of rare earth metals such as cerium, samarium, praseodymium, and yttrium and transition elements such as iron and cobalt in a weight ratio of 10 to 10. A permanent magnet characterized by being made of a 75% mixed powder and an organic resin.