JPS63301506A - Permanent magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To contrive improvement in the corrosion-resisting property on the surface of a magnet by a method wherein a colloid-silicaalcohol aqueous solution mainly composed of SiO2 is spray-coated on the surface of an R-B-Fe magnet, and it is solidified by heating. CONSTITUTION:A collidal solution, composed of an alcohol aqueous solution and inorganic fine particles (SiO2), is coated on the surface of the R-B-Fe permanent magnet consisting of R (at least a kind selected from the rare-earth elements containing Y), B and Fe, it is solidified by heating, and a resin layer is provided as occasion demands. To be more precise, after a before-coating treatment has been conducted, a colloid-silicon-alcohol aqueous solution containing inorganic fine particle (SiO2) is sprayed on the surface of the magnet, and they are solidified by heating. The corrosion-resisting property of the title permanent magnet can be improved still more by laminating a resin layer after an SiO2 thin film has been formed.

Description

[Detailed Description of the Invention] [Field of Application in Joto] This invention relates to R-B-Fe permanent magnets, and in particular to R-B-Fe permanent magnets with improved corrosion resistance and a method for manufacturing the same. .

[Conventional technology]

In recent years, compared to the conventional Srn-Co Ie stone, it has a higher energy content and does not necessarily contain Sm or Co, which is expensive in terms of mineralogy. A permanent Nd-B-Fe based stone was invented. (Sayo et al., J. Appl., Phys., 55 (
6), 15March1984. p2083-20
87, and JP-A-59-46008, 60-
182104) However, Nd -B -Fe
The surface of sintered magnets is chemically unstable and prone to rust. Therefore, many surface treatment methods aimed at rust prevention have been disclosed.

For example, a metal plating method using Nl + Cu t Zn (Japanese Patent Application Laid-open No. 60-54406), a conversion coating treatment method using phosphate, chromate, etc. (% Japanese Patent Application Laid-open No. 60-63903).

A method of providing a resin layer such as epoxy, acrylic, or melamine (Japanese Patent Application Laid-Open No. 60-63901) and a method of providing an M thin film layer (Japanese Patent Application Laid-Open No. 61-270308) have been proposed.

[Problem that the invention seeks to solve]

However, with these conventional methods, the corrosion resistance of the permanent magnet surface is still insufficient, and improvement has been desired.

[Means for solving problems]

As a result of repeated divine attempts, the present inventor discovered that inorganic fine particles S
It has been discovered that the above-mentioned problems can be solved by a method in which i02 is made into a colloid in an aqueous alcohol solution, spray-painted, and solidified by heating.

Therefore, an object of the present invention is to provide a permanent magnet that can obtain excellent corrosion resistance by providing an inorganic SiO2 thin film on the surface of the R-B-Fe-based magnet, and a method for manufacturing the same.

That is, the present invention uses R (at least one kind of rare earth elements including Y), B, and Fe as essential elements.
-E -Colloidal solution consisting of an alcohol bath solution and inorganic fine particles (Si 02 ) is coated on the surface of a Fe-based permanent magnet, heated and solidified, and a resin layer is further provided according to the No. 8 Noble 66 permanent stone and its production. It's a method.

The present invention will be described in detail below. Prior to applying the present invention, RB-Fe
A system sintered magnet is prepared.

After polishing the necessary parts of the magnet, the magnet is treated with an organic solvent (for example, 1.1.1, trichloroethane, Freon).

Degreased with trichlorethylene, etc.). After degreasing, if surface oxides are removed using a sulfuric acid aqueous solution, Sig
h The adhesion of the thin film is improved. In addition to the acid treatment described above, blasting using Al2O2 fine particles may be used to remove surface oxides.

If necessary, the magnet whose surface has been cleaned can be treated with a chemical treatment J8! If this is done, corrosion resistance will be further improved. The chemical conversion treatment may be a chemical conversion coating treatment using phosphate, chromate, or the like.

After carrying out the pre-painting treatment described in No. 9, an aqueous colloidal silica alcohol solution containing inorganic fine particles (Si 02 ) according to the present invention is sprayed onto the magnet surface and solidified by heating.

In addition to Si 02, which is the main formula substance, the solids include T
i 02 , Cr2O3, Atzo3. MgO, Ca
O, NazO, Ni20, Fe2O3, B2O3, ZrO
It may contain one or more selected from 2O3, B203, and Zr02, and the content in the colloidal solution is preferably 5 to 50% by weight Q%. The above substances are added to adjust the color tone and physical property values of the Si 02 thin film (colorless and transparent).

After applying the Si 02 thin film, the corrosion resistance is further improved by further forming a layer of resin 8. The resin used may be epoxy, acrylic, furan, alkyd, melamine, polyimide, polyethersulfone resin, or a combination of these resins, and the coating method may be spray coating or electrodeposition coating (Japanese Patent Application Laid-open No. 130453/1983). Please refer to the official bulletin).

Note that the present invention relates to isotropic and anisotropic magnets produced by furnace forming,
Furthermore, composite magnets of plastic and R-B-Fe alloy powder, so-called plastic magnets, and amorphous R-B-Fe powder with some crystallinity are molded under high temperature pressure (7), and after pressure molding. , -compositionally R (at least 1 inch of rare earth elements including Y) such as magnets with -axis anisotropy
, B and Fe as essential elements.

Next, to explain the reason for limiting the components of the rare earth/boron/iron magnet to which the present invention is applied, the magnet of the present invention contains the rare earth element R (where LR is at least one rare earth element including Y), boron, and iron. It is an essential element. To explain in more detail, R is neodymium (Nd), praseodymium (Pr
)'F or a mixture thereof (didymium) is preferable, as well as lanthanum (La), cerium (Ce), and terbium (
Tb), dysprosium (Dy).

Holmium (Ho), Erbium (Er), Europium (Eu), Samarium (Srn), Gadolinium (
Gd), glometium (Prn), thulium (Trn)
, ytterpium (Yb), lutetium (Lu), and yttrium (Y), with a total amount of 8 to 60 atoms. This is because if the amount is less than 8 atoms, a sufficient coercive force cannot be obtained, and if it exceeds 30 atoms, the residual magnetic flux density decreases. Boron B has 2 to 28 atoms. If it is less than 2 atoms, sufficient coercive force cannot be obtained, and 28
This is because if it exceeds atomic %, the residual magnetic flux density decreases and excellent magnetic properties cannot be obtained. Fe is essential as an element other than the above-mentioned R and B, and f) contains 40 to 90 atoms.

Below 40 atoms, the residual magnetic flux density (Br) decreases, and 9
This is because if it exceeds 0 atoms, a high coercive force (iHc) cannot be obtained.

A rare earth/boron/iron magnet can be created using the above R-B and Fe as essential elements, but as described below, the effect of the present invention will not be achieved even if some of the iron is replaced with other elements or if impurities are included. not lost.

That is, Fe may be replaced with Car8 atoms or less of 50 atoms or less and Ni of less than 8 atoms. This is because if Co exceeds 50 atoms, a high iHc cannot be obtained, and if Ni exceeds 8%, Br cannot be obtained. In addition, as elements other than the above, one or more of the elements other than the specified atoms below (however, if two or more are included, the total amount of the elements is less than or equal to the value of the maximum value of the contained A elements) The OA elements that do not lose the effect of the present invention even if replaced with are listed below.

〔Example〕

Hereinafter, the present invention will be explained by examples.

(Example 1) JP-A-59-46008 and JP-A-60-18
Based on the known method described in No. 2104, Nd-B
-Fe-based sintered magnets were produced. That is, 63 attacks Nd-
1.1%B-Remaining Fe pair @: (wt%) and magnetic properties Br-11.7KG, Hc=11.1KOe, (B
H) WAX = 33.5MGOe The above millstone is polished to a size of 25X15X5, and after solvent degreasing (1,1,1, trichloroethane), it is spray coated with colloidal silica solution and exposed to the atmosphere. The colloidal silica solution was solidified by heating at 160°C for 20 minutes.
i%).

The composition was Ti (hlo%), 35% pure water, and 65% isopropyl alcohol, and the thickness of the SiOz thin film after heating and solidification was 15 μm.

10 at 60°C and 90% relative humidity for the above sample.
A 0 hour corrosion resistance test was conducted. The results are shown in Table 1.

Table 1 As shown in Table 1, no abnormality in appearance (rust formation) was observed after the 100 hour test.

(Comparative Example 1) An example that differs from Example 1 only in that no spray coating with a colloidal silica solution is performed is shown in Table 1 as Comparative Example 1. (Example 2) As a colloidal silica solution, 20% SiO2 ( Heavy (
1%), TiOz9.0%, A12030,
8%, Fe2030.1%, Mg 00 , 05%,
CaO 0.05%, pure water 35%.

A solution of 65% isopropyl alcohol was prepared, and the same procedure as in Example 1 was carried out except for the spray coating of the fish. The coating film thickness was 14 μm. Furthermore, the epoxy paint was applied twice on the front and back sides using a spray method.
Baking was performed at 20°C for 30 minutes. The thickness of the epoxy coating was 60 μm.

For the above sample, 20°C at 80°C and 90° relative humidity
A 0 hour corrosion resistance test was conducted. The results are shown in Table 2, Example 2
Shown as

The corrosion resistance test was conducted at 80℃ and 90% humidity for 20 minutes.
The adhesion strength test is based on the appearance of the sample after it has been left for 0 hours.The adhesion strength test is performed by pulling the sample after the corrosion resistance test using adhesive tape, and checking whether the surface layer peels off or not. Evaluation was made based on the number of peeled squares/total number of squares).

Table 2 It can be seen that by coating an epoxy resin on the top of the Si 02 thin film shown in Table 2, it can withstand a humidity test at 80° C. and 90% relative humidity for 200 hours.

(Fruitful Example 3) As a colloidal silica solution, St 0220'A
(wt%), TiO27%rCrzOs2%,
Zr(hO, 965%, Na200.02%, 2
00.01%, B20s O, O05 rich, pure water 35%
A solution of 65% inpropyl alcohol was prepared and spray coating was performed in the same manner as in Example 1. The coating film thickness was 15 μm. Furthermore, epoxy paint was applied twice to the front and back surfaces using a spray method, and baked at 120° C. for 30 minutes. The thickness of the epoxy coating was 60 μm.

The above sample was subjected to the same moisture resistance test as in Example 2, and the results are shown as Example 3 in Table 2.

(Effects of the Invention) As described above, the present invention can be applied by spray coating a colloidal silica/alcohol aqueous solution containing Si02 as a main substance on the surface of an R-B-Fe magnet, and heating and solidifying the solution, if necessary. Furthermore, by adding a resin layer, the corrosion resistance of the magnet surface is improved.

The industrial value of this product is extremely significant.

Claims (1)

[Claims] 1. Water/alcohol and inorganic fine particles (SiO_2
) A method for producing a permanent magnet, characterized by coating the colloidal solution and solidifying it by heating. 2. TiO_2, Cr_2O as inorganic fine particles
_3, Al_2O_3, MgO, CaO, Na_2O,
K_2O, Fe_2O_3, B_2O_3, ZrO_2
The manufacturing method according to claim 1, characterized in that it contains at least one of the following. 3. The manufacturing method according to claim 1 or 2, further comprising providing a resin layer on top of the surface thin film made of the inorganic fine particles. 4. Inorganic material (SiO_
2) A permanent magnet characterized by being provided with a thin film comprising: 5. In addition, TiO_2, Cr_2O as inorganic materials
_3, Al_2O_3, MgO, CaO, Na_2O,
K_2O, Fe_2O_3, B_2O_3, ZrO_2
The permanent magnet according to claim 4, characterized in that it contains at least one of the following. 6. The permanent magnet according to claim 4 or 5, further comprising a resin layer on top of the thin film made of an inorganic material.