JPS6063902A - Permanent magnet superior in resistance to oxidation - Google Patents

Abstract

PURPOSE:To improve resistance to oxidation of a permanent magnet composed primarily of rare earth elements, boron, and iron by laminating and covering films having resistance to oxidation and resin layers sequentially on a surface of th body of the permanent magnet. CONSTITUTION:As films having resistance to oxidataion, films of phosphate such as zinc phosphate and manganese phosphate or films of chromate are desirable. Laminated resin layers having resistance to oxidation may be synthetic resin for painting or compound resin among these resins. Furthermore, they may contain pigment for rust prevention to enforce and improve rust prevention and film formation. As film formation methods of layers of resin having resistance to oxidation coated on a chemically formed film covering a surface of a permanent magnet, a spray method, a dipping method, and so forth are available, by which the above layers are coated and baked. These layers of resin are assumed to have the thickness 5mum-25mum. The permanent magnet is composed primarily of at least one kind among rare earth elements including Y, that is, R 8- 30atom%, B 2-28atom%, and Fe 42-90atom% and its main phase comprises a tetragonal crystalline phase.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a permanent magnet whose main components are R (R is at least one rare earth element including Y), B, and Fe.
This invention relates to a rare iron-based permanent magnet with improved oxidation resistance of a permanent magnet.

Permanent magnet materials range from various electrical products on general household identification to large-sized items.
It is one of the extremely important electrical and electronic materials used in a wide range of fields, including peripheral terminal equipment for computers. With the recent demand for smaller and more efficient electrical and electronic equipment,
Permanent magnetic materials are becoming increasingly sophisticated.

Current representative permanent magnet materials are Alni, hard ferrite, and rare earth Kobal magnets.

As the raw material situation for cobalt has become unstable in recent years, demand for alnico magnets containing 20 to 30 wt% cobalt has decreased.
Inexpensive hard ferrite, whose main component is iron oxide, is the mainstream of magnet II.

On the other hand, rare earth cobalt magnets have Kobal 1 ~ 50 ~ 60W
It is very expensive because it contains % and uses Sin, which is not contained in rare earth ores, but it has much higher magnetic properties than other magnets, so it is mainly small and has high added value. J, which is often used in magnetic circuits, is now available.

Therefore, the present inventor first developed a new high-performance permanent magnet that does not contain expensive Sm or 6.
proposed a permanent magnet (with at least 1 weight of rare earth elements containing Y) (Japanese Patent Application No. 145072/1982). This permanent magnet uses light rare earths rich in YJ origin, mainly ceramics and circles, as R, and 25M G with Fe as the main component.
It is an outstanding permanent magnet that exhibits an extremely high energy product exceeding Os.

However, Fe-
The permanent magnet f1, which is made of a BR-based magnetic anisotropic sintered body, contains rare earth elements and iron, which tend to oxidize in the air and gradually produce stable oxides, so it can be incorporated into the magnetic circuit.
In this case, oxides formed on the magnet surface cause a decrease in the output of the magnetic circuit and variations between the magnetic circuits, and
There was a problem of contamination of peripheral equipment caused by surface oxides falling on the skin.

This invention is a novel permanent magnet mainly composed of rare earth metals such as 71\ron and iron, which has improved oxidation resistance.
The purpose is to create a permanent magnet that covers money as its main component.

In other words, this invention provides R (wherein R is at least one of the group elements including Y) from 8 atomic % to 30 atomic %, B2
On the surface of a permanent magnet whose main components are from atomic% to 28 atomic%, [e42 atomic% to 90 atomic% and whose main phase is from the tetragonal phase,
There is a permanent magnet (JC) that is characterized by being coated with an oxidation-resistant chemical coating and a resin layer in sequence.

This invention consists of laminating a strong and stable oxidation-resistant chemical conversion coating and a resin layer on the surface of a water-based permanent magnet in order to suppress the formation of oxides on the surface.

The oxidation-resistant chemical coating according to the present invention is preferably a phosphate coating such as zinc phosphate or manganese phosphate, or a chromate coating, and the thickness of the oxidation-resistant chemical coating is: 1. In the case of a phosphate coating is 3ρ~ in terms of oxidation resistance J3, strength, and cost.
In the case of chromate-coated nx+, 2-5% is preferable.

The oxidation-resistant resin layer laminated on the surface of the oxidation-resistant chemical conversion layer according to the present invention includes synthetic resins for paints such as boxy resin, thermosetting acrylic resin, alkyd resin, melamine resin, and silicone resin. Alternatively, a composite resin of these resins may be used.Furthermore, for the purpose of rust prevention and improvement of coating film reinforcement, the above resin may contain rust preventive pigments such as zinc oxide, zinc chromate, and red lead. Alternatively, it may be one containing fj, or penzotrino'zole.

In this invention, the amount of the above-mentioned pigment in the oxidation-resistant resin may be 80% or less based on the amount of the resin, and the amount of benzo-1-lyazole may be 1% or more based on the amount of the resin. It may be included.

In addition, according to J3 of this invention, the oxidation-resistant resin layer coated on the chemical conversion coating coated on the surface of the permanent magnet is applied by spraying, dipping, etc. However, this resin layer only needs to have a thickness of 5 μm or more; if it exceeds 2577 In, it becomes difficult to obtain dimensional accuracy of the product, so the thickness must be 25 μm or less.

Therefore, the permanent magnet of this invention mainly uses resource-rich light rare earths such as ceramics and metals as R, and Fe,
[By using 3,R, as the main component, it has an extremely high energy peak of 25MGOθ or more, a high residual magnetic flux density, a high retention horn, and high oxidation resistance. It is possible to obtain well-defined permanent magnets at low cost.

Moreover, the alloy for permanent magnets of this invention has a grain size of 1 to 100.
The main phase is a compound having a tetragonal crystal structure in the range of Ann, and is characterized by containing a non-magnetic phase (excluding oxide phase) of 1% to 50% by volume.

The reasons for limiting the composition of the permanent magnet according to the present invention will be explained below.

The rare earth element system used in the permanent magnet of the present invention [TE is a rare earth element including yttrium (Y), light nine earths, and heavy rare earths, and at least one of these, preferably Nd, Pr, etc. A light rare earth element is used as the main element, or a mixture with Nd, Pr, etc. is used. That is, as R, neodymium (Nd), brareodymium (yen =).

Lanthanum (La), cerium (Ce).

Terbium (1-[)), dysprosium (DV).

Holmium (Ho), erbium (Er).

Europium (Eu), samarium (Sm).

Cadolinium (Gd), Thulium (Gd).

Ytterum (Yb), lutetium (Lu).

Includes Itsu[・rium (Y).

In addition, it is usually sufficient to use one type of R, but in practice, a mixture of two or more types (Mitushmetal, didymium, etc.) can be used for reasons such as convenience of availability, and Sm, Y, La
, Ce, Gd, etc. can be used as a mixture with other R1, especially Nd, pr, etc.

Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R (at least one rare earth element including Y) is an essential element in the above-mentioned novel permanent magnet, and when it is less than 8 at%, the crystal structure becomes a cubic structure that is the same as α-iron. Therefore, high magnetic properties, especially high coercive force, cannot be obtained.
If it exceeds 30 atomic %, the I-ridge nonmagnetic phase increases, the residual magnetic flux density (Br) decreases, and a permanent magnet with poor characteristics cannot be obtained. Therefore, the rare earth element ranges from 8 atomic % to 30 atomic %.

13 is an essential element in the new above-mentioned system permanent magnet, and when it is not vortexed at 2 atom%, it becomes a rhombohedral structure and a high coercive force (iHc) cannot be obtained, and when it exceeds 28 atom%, B
The rich nonmagnetic phase increases, and the residual magnetic flux density (Br)
As a result, excellent permanent magnets cannot be obtained. Therefore, B is in the range of 2 atomic % to 28 atomic %.

Fe is an essential C1 element in the new permanent magnet of the above system, and if it is less than 42 atom%, the residual magnetic flux density (Br) decreases, and if it exceeds 90 atom%, a high coercive force cannot be obtained. The content is defined as 42 atomic % to 90 atomic %.

In addition, replacing a part of Fe with 6 in the alloy for permanent magnets according to the present invention can improve the temperature characteristics without impairing the magnetic properties of the obtained magnet.
If the amount of substitution exceeds 50% of Fe, the magnetic properties (b) deteriorate, which is not preferable.

Further, the permanent magnet according to the present invention has R,13°1:e
In addition, the presence of unavoidable impurities in industrial production is allowed, but a portion of B must be 4.0 atomic % or more FQ) C13, 5 atomic % or less p, 2.5 atomic % or more 3. At least one of CLI of 3.5% or less, 4, O atom% in combination b1 compensation
By substituting with the following, it is possible to improve the manufacturability and reduce the cost of permanent magnets.

In addition, at least one of the following additional elements is R-BF
It is added to e-based permanent magnets because it is effective in improving the coercive force, etc., improving manufacturability, and reducing costs. However, the residual magnetic flux density (Br
), so it is desirable to add it in a range that is equal to or higher than the residual magnetic flux density of conventional hard ferrite magnets.

9.5 atomic % or less of Ai, 4.5 atomic % or less of Ti.

- 9.5 at% or less Cr, 8.5 at% or less Cr.

1yjn of 8.0 atom% or less, B111 of 5 atom% or less
Nb 2.5 atomic% or less 110,51m % or less T
a.

MO19 of 9.5 atomic % or less, W12 of 51 atomic % or less
．． Sb of 5 atomic % or less, Ge of 1 atomic % or less, So of 35 atomic % or less, Z'' of 5.5 atomic % or less, 5.5 atomic %
Addition of at least one of the following
4 L, If two or more types are included, the maximum S size 1
By avoiding the inclusion of less than 1 quintillion percent of the additive element having the maximum value, it is possible to permanently increase the coercive force of 1 Ilib.

It is essential that the main crystalline phase be tetragonal in order to produce a sintered permanent magnet with superior magnetic properties than a fine and uniform alloy powder.

In addition, the permanent magnet of the present invention can be press-molded in a medium to obtain a magnetically anisotropic magnet, and press-molded in a no-magnetic field to obtain a vA aeroisotropic magnet. .

The permanent magnet according to this invention has a coercive force of +1-10≧1KO
e, the residual magnetic flux density Br > 4KG, the maximum energy 1'A (BH) ll1ax is equal to or higher than that of hard ferrite, and in the most preferable composition range, (B
f-I)llax≧10MGOe, the maximum value is 2
Reach 5MGOθ or more.

In addition, the main component of the permanent magnet alloy of this invention is 5.
When light rare earth metal accounts for 0% or more, R12 atomic%
Sintered magnets exhibit the most excellent magnetic properties, especially when the light rare earth metal is ceramic. (B H) max has a maximum value of 33M
Reach G Oe or higher.

Examples according to the present invention will be shown below to clarify the effects of (a).

Example 1 Electrolytic iron with a purity of 99.9%, 819
．． A ferroboron alloy containing 4% I and the remainder consisting of Fe and impurities such as #, SL, and C, and ceramic with a purity of 99.7% or more was used, and these were high-frequency melted and then cast in a water-cooled copper mold.

Thereafter, the ingot was coarsely ground in a stamp mill to a particle size of 35 mm, and then ground in a ball mill for 3 hours to obtain a fine powder with a particle size of 3 to 10 mm.

This fine powder is inserted into a mold, oriented in a magnetic field of 10 KOθ, and 1. It was molded at a pressure of 'nt4.

The obtained molded body was sintered at 1100°C for 1 hour in Ar, then allowed to cool, and further sintered at 600°C in Ar.
A permanent magnetic material 1 according to the present invention was prepared by subjecting it to an aging treatment at ℃ for 2 hours.

The component composition at this time is 1411-8,5El-7
A 15 mm x 10 mm x 6 mm test piece was cut out from the obtained permanent magnet with 7,5 FeC, and as shown in Table 1, the test piece was degreased, pickled, and then treated with phosphate under the following conditions. l! A, B,
and lead chromate treatment C, and then the test pieces were treated with the paints and coatings (!Ir) shown in Table 1.

Next, the coating thickness, magnetic properties, and blood oxidation properties of each sample were determined.

Adhesive strength and dimensional accuracy were measured. The results are shown in Table 2.

Phosphate treatment conditions A Zinc 4.6 (1/Bath phosphate 17.8 (1/Bath temperature 75°C Holding time 5 minutes) B Manganese 4.2a / Phosphate 14,48 G / Bath temperature 98°C Hold Time: 10 minutes Chromate treatment conditions C: Sodium carbonate 55.OΩ/9 Sodium chromate 17.5g/Sodium silicate 0.8g/Il Bath temperature: 95°C Holding time: 10 minutes For the oxidation resistance test, the above test piece was Temperature in °C, 90%
Evaluation was made based on the oxidation weight gain of the test piece when it was left in an atmosphere of humidity for 3 days.

In addition, in the adhesive strength test, the above test piece, which had been subjected to coating H9 treatment after chemical conversion treatment, was adhered to a holding plate with an adhesive called Araldite A W-106 (trade name), and then a shearing force was applied to the test piece using an Amsler tester. In addition, the adhesive strength per unit area was measured. In addition, the dimensional accuracy is measured by measuring the dimensions of the test piece after coating treatment, and is expressed as (maximum value) - (minimum Q value) - R -0. The results of each sample were left in the same atmosphere at 60°C and 90% humidity for 1, 2, and 3 days as an oxidation test without any chemical conversion treatment or lamination treatment of paint film treatment. The oxidation weight gain and oxide film W (maximum oxide film Pp vessel) were evaluated and shown in Table 3. An oxide film is formed on the surface, and as time passes, oxidation progresses internally, deteriorating the magnetic properties.In addition, the increase in the oxide film due to the oxidation of the magnet incorporated in the magnetic circuit The permanent magnet according to the present invention has poor oxidation resistance. It can be seen that when incorporated into a magnetic circuit, etc., it is extremely effective in stabilizing output characteristics and improving reliability.

Margin below Table 3 Margin below

Claims (1)

[Claims] I R (([, LR is at least one rare earth element containing Y) 8 atomic % to 30 atomic %, B 2 atomic % to 28
%, Fe42 atomic % to 90 atomic % as the main component, and the main phase is a tetragonal phase, and the permanent magnet is coated with an oxidation-resistant chemical conversion film and a resin layer in sequence on the surface of the permanent magnet body. .