JPH06124813A - Manufacture of r-tm-b magnet - Google Patents

Abstract

PURPOSE:To suppress occurrence of pin holes in a plated film. CONSTITUTION:A plate-layer is farmed on the surface of R-TM-B group permanent magnet, consisting of R (here, R is one or more kinds of rare earth elements including Y), TM (here, TM is one or more kinds of transition metal elements) and B (boron), for an R-TM-B magnet to be formed. In its manufacture, supersonic wave vibration is applied at formation of a plate-layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an R-TM-B system permanent magnet having a corrosion resistant coating formed thereon, and more particularly to a method for producing an R-TM-B system permanent magnet having a plating layer such as Ni plating formed thereon. .

[0002]

2. Description of the Related Art As electric and electronic equipments have become higher in performance and smaller in size, the same requirement has been increased for a permanent magnet as one component thereof. That is, the strongest permanent magnet before was a rare earth / cobalt (R-Co) system, but in recent years, a stronger R-co
TM-B permanent magnets have emerged (Japanese Patent Laid-Open No. 59-46).
No. 008). Here, R is one kind or a combination of two or more kinds of rare earth elements including Y, TM is a transition metal center such as Fe or Co, and a part thereof is replaced with another metal element or non-metal element, B Is boron. However, R-TM-B
The system permanent magnet has a problem that it is extremely rusty. Therefore, in order to improve the corrosion resistance, a measure has been taken to provide an oxidation resistant coating layer on the surface of the permanent magnet body. As the type of coating layer, Ni plating, oxidation resistant resin, Al ion plating, etc. have been proposed. In particular, Ni plating is noted as improving the corrosion resistance of the R-TM-B type permanent magnet with a simple treatment. (JP-A-60-544)
06). The Ni plating has an advantage that the surface coating layer has excellent mechanical strength as compared with the oxidation resistant resin, and that the coating layer itself has almost no hygroscopicity.

[0003]

However, unlike the oxidation resistant resin layer, there is a problem that pinholes exist on the surface of the Ni plating coating layer. Therefore, regardless of whether or not the coating layer itself has hygroscopicity, there is a problem that moisture permeates into the magnet body through the pinhole with time and causes corrosion deterioration. Then, this invention makes it a subject to provide the manufacturing method of the R-TM-B type | system | group permanent magnet which suppresses generation | occurrence | production of the pinhole of a plating film.

[0004]

In order to solve the above problems, in the present technology, ultrasonic vibration is applied during the plating process to vibrate the material to be processed and suppress the generation of pinholes. That is, the present invention provides R (where R is one or more of rare earth elements including Y), TM (where TM is
In the method for producing an R-TM-B magnet, in which a plating layer is formed on the surface of an R-TM-B based permanent magnet made of B (boron), one or more kinds of transition metal elements) It is characterized in that ultrasonic vibration is applied.

In the magnet according to the present invention, a part of TM of Fe, Co, Ni, etc. is Ga, Al, Ti, V, Cr, Mn, Z.
r, Hf, Nb, Ta, Mo, Ge, Sb, Sn, B
It can be replaced with an element such as i. The manufacturing method thereof may be a sintering method, a melt quenching method, or a modification thereof.

The plating is performed after degreasing with an organic solvent, the current density is preferably 1 to ^{2 A} / dm ² , and the thickness of the plating layer is preferably 5 to 20 μm. Regarding the pre-plating treatment, in order to remove the work-affected layer and activate the pre-plating,
It is better to use an acidic solution. A strong acid such as sulfuric acid or hydrochloric acid is effective for pre-plating activation, but in order to avoid the influence of the pre-plating treatment on the material as much as possible, first etching with 2 to 10 vol% nitric acid and then hydrogen peroxide 5 -10v
The second etching with a mixed acid of ol% and acetic acid of 10 to 30 vol% is most desirable. Next, a plating process is performed. The type of plating is not limited, but Ni plating is most preferable as described above. In this case, any of the Watts bath, the sulfamic acid bath, and the ammonium bath may be used, but bright plating is preferable. Matte plating is not preferable because it has a columnar crystal structure. However, since it has good adhesion and little stress, it is effective as a base for multilayer plating. The plating layer is not limited to one layer and may be a multilayer plating layer having two or more layers.

[0007]

EXAMPLES Nd (Fe _0.7 Co _0.2 B _0.07 Ga _0.03 ) _6.5
An alloy having the following composition was produced by arc melting, and the obtained ingot was roughly crushed by a stamp mill and a disc mill.
Fine pulverization with a pulverized particle size of 3.5 μm (FSSS) was performed by pulverizing with a jet mill using N ₂ gas as the pulverizing medium.
The obtained raw material powder was subjected to transverse magnetic field molding in a magnetic field of 15 KOe. The molding pressure was ² Ton / cm ² . The compact was sintered in vacuum at 1090 ° C for 2 hours. 18 × sintered body
Cut out to a size of 10 × 6 mm, then heat and hold in an argon atmosphere at 900 ° C. for 2 hours and then rapidly cool to a temperature of 6
It was kept for 1 hour in an atmosphere of argon kept at 00 ° C. The sample thus obtained was subjected to the following surface treatment.
The obtained sample was degreased with IPA, then HNO ₃ 2vol%, etched with a solution for 1 minute, and then washed with water to obtain acetic acid 20vol.
%, Hydrogen peroxide solution 5 vol% mixed acid for 30 seconds, washed with water, and then plated. After that, Ni plating was applied under the working conditions shown in Table 1. A Watt bath was used as the Ni plating solution, and saccharin or the like was added as a brightening agent. Also,
The film thickness was 15 μm.

[0008]

[Table 1] The number of samples was 100 each. Table 2 shows the results of the corrosion resistance test. In the corrosion resistance test, the sample was left in a state of 119.6 ° C. × 2 atm and 100% for a specified time (judged by the presence or absence of blisters on the surface).

[0009]

[Table 2]

[0010]

According to the present invention, the metal plating layer is made more complete by applying vibration by the ultrasonic oscillator when the plating layer is formed, and the corrosion resistance of the R-TM-B magnet is remarkably improved. .

Claims (1)

[Claims] 1. From R (where R is one or more kinds of rare earth elements including Y), TM (where TM is one or more kinds of transition metal elements), and B (boron) R-TM
-R-TM with a plating layer formed on the surface of a B-based permanent magnet
-A method for producing an R-TM-B permanent magnet, characterized in that ultrasonic vibration is applied during the formation of the plating layer in the method for producing a B magnet.