JPS62149108A - Manufacture of permanent magnet - Google Patents

Abstract

PURPOSE:To prevent a magnetic alloy from being oxdized during treatments thereof, by applying a metallic alcoholate on a permanent magnet formed by molding and sintering a R2T14B permanent magnet material and hydrolyzing the metallic alcoholate to form a coat of a metal oxide on the surface of the permanent magnet. CONSTITUTION:Nb having a purity of 95% or over, electrolytic iron and crystal born are melted and cooled in the atmosphere of argon to obtain an ingot. The ingot is then ground and molded under pressure. The pressure-molded powder body is sintered and cooled slowly. The body is further heated and quenched to obtain a permanent magnet. The permanent magnet thus obtained is degreased with trichloroethylene, and Si alcoholate is applied thereon by spraying the same. The permanent magnet is then heated for 20min at a temperature of 100-200 deg.C. In this manner, a transparent SiO2 film can be formed on the surface of the magnet.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to R, 'r,
Among B-based intermetallic compound magnets, the present invention relates to a method for producing an R-Fe-B magnet material, particularly a permanent magnet material containing R (at least one rare earth element including Y) and Fe-B as a main component. It is something.

[Conventional technology]

Conventionally, R-Fe-B magnet materials represented by Nd-Fe-B have higher magnetic properties than 5nCo permanent magnet materials currently on the market. However, this R-Fe-B magnet material contains rare earth elements and iron that are extremely easily oxidized in the atmosphere, so if it is incorporated into a device such as a magnetic circuit without any treatment, the magnet material may oxidize. This causes deterioration and variation in characteristics due to the magnet material, and furthermore, contamination of surrounding components occurs due to scattering of oxides generated from the magnet material. Therefore, in the past, an oxidation-resistant film was formed on the magnet surface to prevent the above-mentioned variations and contamination. The inventions described in JP-A-60-54406 and JP-A-60-63902 are known examples of improvements in oxidation resistance.

[Problems to be solved by the invention] However, since the oxidation-resistant coatings according to these known examples use a large amount of water during the coating formation process, there is a risk that the magnet material may be oxidized during the treatment process. , the oxidation resistance was insufficient.

Therefore, it is an object of the present invention to provide a method for producing a permanent magnet that does not require the use of water in the oxidation-resistant film forming process.

[Failure to solve the problem]

The method for producing a permanent magnet of the present invention uses R (at least one rare earth element including yttrium).

R, T, whose main components are Fe (iron) and B (boron).
A method for manufacturing a permanent magnet in which a B-based permanent magnet material is molded and sintered, and then its surface is coated with a metal oxide, including the step of coating the surface with a metal oxide.

The method is characterized in that a metal alcoholate is applied to the surface and thermally decomposed to form a metal oxide film.

According to the method of the present invention, no water is included during the oxide film coating process, so unlike conventional plating and chemical conversion treatments that use a large amount of water, the magnet alloy itself is oxidized during the process. restrain from doing.

〔Example〕

The method for manufacturing a permanent magnet with excellent oxidation resistance according to the present invention will be described below with reference to Examples.

First, Nd (neodymium) with a purity of 95% or more, electrolytic iron, and crystal B are melted by high-frequency heating in an argon atmosphere, and after casting, the mixture is cooled to 200°C at a rate of 100°C/min to obtain an alloy with an alloy composition of 33 wt% Nd. -1wt%B -baA
Obtain an Fe ingot.

Next, the ingot was roughly pulverized in an argon atmosphere, then wet pulverized in a ball mill to about 4 μm, and this powder was
1. In a magnetic field of 0 KOe. Molding is performed at a pressure of Ot/, L2. Then, the green compact was heated to 1o50~1100℃ for 2 hours.
The material is sintered during the heating process, and then slowly cooled at a cooling rate of 100° C./hr or less.

Thereafter, a permanent magnet can be obtained by heat-treating this sintered body at 500 to 600° C. for 1 hour and rapidly cooling it.

From the permanent magnet thus obtained, 10wnX 10
A test piece of m×8 mm was cut out.

After degreasing the above test piece with trichlene, sl-alcoholate was applied by spray, and then heated at 100 to 200°C for 20 minutes. Then, transparent 5102 on the surface of the magnet
A membrane can be obtained. The minimum thickness of this film is 5μ
m, maximum 15 μm.

In this way, the permanent magnet test piece coated with 5in2 and the untreated test piece without coating were tested.
Based on IS-Z-2371'', a salt spray test for <72 hours for 5 hours was conducted and found that no oxidation occurred on any part of the surface when 9 coating was applied, but a large amount of oxidation occurred on the entire surface when no coating was applied. Red rust occurred.

Furthermore, when 5in2 coating is applied.

As can be seen from Table 1 and the explanation of the magnetic properties compared to the case without coating, the permanent magnet coated with the oxide of this example has excellent oxidation resistance, and has no effect on the magnetic properties. It turns out that it doesn't have any effect.

Still another example is the following method.

After degreasing and drying the above-mentioned permanent magnet test piece, T
100-2 after applying i-alcolate by spray
After heating at 00° C. for 20 minutes, one surface is sprayed with alcoholate and heated at a temperature of ioo~200'C for a period of time to obtain a transparent 5in2 film on the white Tie2 film. The film thickness of these two phases is 5 μm at the minimum and 20 μm at the maximum.
It is μm.

The permanent magnet coated with two phases of Tl 02.5in2 obtained as described above and the uncoated permanent magnet were prepared based on JIS-Z-2371.
As a result of a 72-hour 5% salt water spray test, no oxidation occurred when coated.

Without coating, a large amount of red rust appeared on the entire surface.

Furthermore, Table 2 shows the magnetic properties when a two-phase coating of TiO2+ 5in2 was applied and when no coating was applied.

Table 1 - From Table 2, it can be seen that the magnetic properties of the permanent magnet are not affected even when the two-phase coating is used.

The above embodiment is a case in which a two-phase coating of TiO2+ 5i02 is used, but it is more effective to use a three-phase coating in which At203 is further added, and even more effective if a larger number of layers are stacked.

The thickness of the oxidation-resistant film is 9 dimensional accuracy in terms of cost.

From the viewpoint of oxidation resistance, the thickness is preferably 2 to 20 μm.

μ Lower Mill [Effect of the Invention] As described above, in the method of the present invention, no water is used at all including pretreatment to form the oxide coating, so the magnet alloy itself is not oxidized during the treatment process. Therefore, the magnetic properties of the permanent magnet are not affected in any way, and contamination of the surrounding area due to scattering of oxides can be prevented.

Claims (1)

[Claims] 1. R whose main components are R (at least one rare earth element including yttrium), Fe (iron), and B (boron)
_2T_1_4B Permanent magnet material is molded and sintered, and then the surface thereof is coated with a metal oxide. In the method for manufacturing a permanent magnet, the step of coating the surface with a metal oxide comprises coating the surface with a metal alcoholate. A method for producing a permanent magnet, which comprises forming a metal oxide film through thermal decomposition.