JPH1074607A - Corrosion-resisting permanent magnet and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the wear resistance and corrosion resistance of a Fe-B-R permanent magnet body the major phase of which is tetragonal system, by forming an AlN film with a specified film thickness on the surface of the said permanent magnet body with an Al film with a specified film thickness in-between. SOLUTION: The corrosion-resisting permanent magnet is manufactured as follows, the surface of a Fe-B-R permanent magnet body the major phase of which is tetragonal system, is cleaned, and an Al film with a film thickness of 0.06-5.0μm is formed on the surface of the magnet body by a vapor growth film formation method. Thereafter, an AlN film with a film thickness of 0.5-10μm is formed in a N2 gas atmosphere by a vapor growth film formation method. This constitution improves the adhesion between the surface of the magnet body and the Al film. In addition the lamination of the AlN film on the Al film provides stable magnet characteristics due to the corrosion resistance and the wear resistance of the deposited corrosion-resisting metal film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has high magnetic properties and excellent adhesion, corrosion resistance, acid resistance, alkali resistance,
The present invention relates to a Fe-BR-based permanent magnet provided with a corrosion-resistant coating having excellent wear resistance, and in which an AlN coating layer is provided with a specific film thickness via an Al coating, particularly in an atmosphere at 80 ° C and a relative humidity of 90%. The present invention relates to a corrosion-resistant permanent magnet having little deterioration from initial magnet properties when left for a long time and having extremely stable magnet properties, and a method for manufacturing the same.

[0002]

2. Description of the Related Art First, using rare earths, which are abundant in resources, mainly Nd and Pr, B and Fe as main components, do not contain expensive Sm and Co, and are the highest among conventional rare earth cobalt magnets. As a new high-performance permanent magnet that greatly exceeds the characteristics,
e-B-R permanent magnets have been proposed (Japanese Patent Laid-Open No. 59-1984).
46008, JP-A-59-89401).

The Curie point of the above magnet alloy is generally 30
0 ° C. to 370 ° C., but having a higher Curie point by substituting a part of Fe with Co
R-based permanent magnets (JP-A-59-64733, JP-A-59-64733)
-132104), and has a Curie point equal to or higher than that of the Co-containing Fe-BR based rare earth permanent magnet and a higher (BH) max, and improves its temperature characteristics, particularly iHc. Therefore, as a rare earth element (R), Co-containing F mainly containing light rare earth elements such as Nd and Pr is used.
By containing at least one of heavy rare earths such as Dy and Tb in a part of R of the eBR type rare earth permanent magnet, iHc can be increased while retaining a very high (BH) max of 25 MGOe or more. Further improved Co-containing F
e-BR type rare earth permanent magnets have been proposed (JP-A-60-34).
005).

[0004] However, since the permanent magnet made of the Fe-BR based magnetic anisotropic sintered body having the excellent magnetic properties described above contains a rare earth element and iron which are easily oxidized in air as main components, When incorporated in a magnetic circuit, the oxides generated on the magnet surface cause a reduction in the output of the magnetic circuit and variations between the magnetic circuits, and there is a problem of contamination of peripheral devices due to the loss of the surface oxide. Was.

[0005]

Therefore, the above-mentioned Fe-
In order to improve the corrosion resistance of BR permanent magnets, there has been proposed a permanent magnet in which the surface of a magnet body is coated with a corrosion-resistant metal plating layer by an electroless plating method or an electrolytic plating method (Japanese Patent Publication No. 3-74012). However, in this plating method, since the permanent magnet body is a sintered body and is porous, an acidic solution or an alkaline solution in the plating pretreatment remains in the pores, and may corrode with aging. Since the chemical resistance is poor, there has been a problem that the magnet surface is corroded at the time of plating and the adhesion and corrosion resistance are poor. Also, even if corrosion resistant plating is provided,
1 in the corrosion resistance test under the condition of temperature 60 ° C and relative humidity 90%
After leaving for 00 hours, the magnet properties were degraded by 10% or more of the initial magnet properties and were very unstable.

[0006] Therefore, in order to improve the corrosion resistance of the Fe-BR based permanent magnet, Al, Al is formed on the surface of the magnet by ion plating, ion sputtering or the like.
It has been proposed to improve the corrosion resistance by applying an N film (Japanese Patent Publication No. 5-15043). However, Al
The N coating has poor adhesion due to differences in the thermal expansion coefficient, ductility, etc. in addition to the crystal structure of the Fe-BR-based magnet body, and the Al coating has good adhesion and corrosion resistance, but low abrasion resistance. And so on.

[0007] The present invention has excellent adhesion to an Fe-BR-based permanent magnet base, and is intended to improve wear resistance and corrosion resistance. An object of the present invention is to provide an inexpensive Fe-BR-based permanent magnet having stable high magnet properties, abrasion resistance and corrosion resistance while minimizing deterioration from initial magnet properties when left for a long time.

[0008]

Means for Solving the Problems The present inventors have found that excellent corrosion resistance, especially even when left for a long time under an atmosphere condition of a temperature of 80.degree. As a result of various investigations on the method of forming an AlN film on the surface of a permanent magnet body for the purpose of producing a Fe-BR-based permanent magnet having stable magnet properties due to the corrosion resistance and wear resistance of the corrosion-resistant metal film, the magnet body surface was ionized. After cleaning by a sputter method or the like, an Al film having a specific thickness is formed on the surface of the magnet body by a vapor deposition method such as an ion plating method or an ion sputtering method, and then N ₂ gas under specific conditions is introduced. Oxide adhering to the magnet surface is reduced by the Al coating by forming an AlN coating with a specific layer thickness by vapor deposition such as ion plating and ion sputtering. Ri, oxides of the magnet surface part or majority is reduced by generating an AlN coating film on the Al coating film, AlN _x is produced at the interface between Al and AlN, adhesion between the Al coating film and AlN coating film It has been found that the present invention can be significantly improved, and the present invention has been completed.

That is, according to the present invention, the surface of the Fe-BR-based permanent magnet whose main phase is a tetragonal phase
0.5 μm to 1 μm through an Al coating of m to 5.0 μm
It is a corrosion-resistant permanent magnet having an AlN coating layer of 0 μm.

Further, the present invention cleans the surface of an Fe-BR-based permanent magnet having a tetragonal phase as a main phase, and then applies an Al coating having a thickness of 0.06 to 5.0 μm on the surface of the magnet. A method for producing a corrosion-resistant permanent magnet, comprising forming an AlN coating layer having a thickness of 0.5 μm to 10 μm by a vapor phase film forming method in an N ₂ gas atmosphere after forming by a phase film forming method.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, Fe-BR
As a method for forming the Al film and the AlN film to be adhered to the surface of the permanent magnet body, a so-called gas-phase film forming method such as an ion plating method, an ion sputtering method, and a vapor deposition method can be appropriately used. Ion plating and reactive ion plating are preferred from the viewpoints of properties, film formation speed, and the like.

The temperature of the permanent magnet serving as the substrate when the reaction film is formed is preferably set at 200 ° C. to 500 ° C. If the temperature is lower than 200 ° C., the reaction adhesion with the substrate magnet is not sufficient, and the temperature exceeds 500 ° C. The temperature difference between the temperature and normal temperature (25 ° C) increases, and the coating cracks in the cooling process after the treatment,
The temperature of the substrate magnet is set to 2
It is good to set to 00 degreeC-500 degreeC.

An example of the method for producing a corrosion-resistant permanent magnet according to the present invention, characterized in that an AlN coating layer is provided on the surface of an Fe-BR-based permanent magnet body via an Al coating layer, will be described in detail below. 1) After evacuating the vacuum container to an ultimate degree of vacuum of 1 × 10 ⁻³ pa or less using an arc ion plating apparatus, Fe—B— Clean the surface of the R-based magnet body.

2) Next, the target Al is evaporated with an Ar gas pressure of 0.1 pa and a bias voltage of −50 V, and a 0.06 μm to 5.0 μm film thickness is formed on the surface of the magnet body by arc ion plating. Is formed. 3) Then, hold the magnet temperature of the substrate 250 ° C., N ₂
Under the conditions of a gas pressure of 1 pa and a bias voltage of -100 V, A
(1) An AlN coating layer having a specific thickness is formed on the coating layer.

In the present invention, the reason why the thickness of the Al coating on the surface of the Fe—BR type permanent magnet body is limited to 0.06 μm to 5.0 μm is that if the thickness is less than 0.06 μm, Al
Is difficult to apply uniformly, and the effect as a base film is not sufficient. When the thickness exceeds 5.0 μm, there is no problem. However, the cost of the base film is increased, which is not practical and not preferable. , Al coating thickness is set to 0.06 μm to 5.0 μm. In particular, the Al coating thickness is selected according to the surface roughness of the magnet body. When the surface roughness is 0.1 μm or less, the Al coating thickness is preferably 0.06 μm to 5.0 μm, and the surface roughness is 0.1 μm to In the case of 1.2 μm, the desired film thickness is 0.1 μm.
It is 1 μm to 5.0 μm.

Further, the thickness of the AlN film is 0.5 μm to 10 μm.
The reason for limiting to m is that if it is less than 0.5 μm, the corrosion resistance and abrasion resistance as AlN are not sufficient, and if it exceeds 10 μm, there is no problem effectively, but it is not preferable because it increases the manufacturing cost.

In the present invention, the rare earth element R used in the permanent magnet occupies 10 to 30 atomic% of the composition, but at least one of Nd, Pr, Dy, Ho, and Tb.
Species, or additionally, La, Ce, Sm, Gd, Er,
Those containing at least one of Eu, Tm, Yb, Lu, and Y are preferable. Usually, one kind of R is sufficient, but in practice, a mixture of two or more kinds (Misch metal,
Jijim etc.) can be used for reasons such as convenience in obtaining. Note that this R may not be a pure rare earth element,
It may be one containing impurities that are unavoidable in production as far as it is industrially available.

R is an essential element in the above-mentioned permanent magnets. If it is less than 10 atomic%, the crystal structure has the same cubic structure as α-iron, so that high magnetic properties, especially high coercive force cannot be obtained. , More than 30 atomic%, the R-rich nonmagnetic phase increases, the residual magnetic flux density (Br) decreases, and a permanent magnet having excellent characteristics cannot be obtained. Therefore, R10 atomic% or more
A range of 30 atomic% is desirable.

B is an essential element in the above-mentioned permanent magnet. If it is less than 2 atomic%, the rhombohedral structure becomes the main phase, and a high coercive force (iHc) cannot be obtained. Increase in non-magnetic phase, residual magnetic flux density (Br)
, The excellent permanent magnet cannot be obtained. Therefore, B is desirably in the range of 2 to 28 atomic%.

Fe is an essential element in the above-mentioned permanent magnets. When the content is less than 65 atomic%, the residual magnetic flux density (Br) decreases, and when it exceeds 80 atomic%, a high coercive force cannot be obtained. % To 80 atomic%.
Further, substituting a part of Fe with Co can improve the temperature characteristics without impairing the magnetic characteristics of the obtained magnet. However, when the Co substitution amount exceeds 20% of Fe, conversely, It is not preferable because the magnetic properties deteriorate. When the substitution amount of Co is 5 atomic% to 15 atomic% in the total amount of Fe and Co, Br is increased as compared with the case where no substitution is made, and thus it is preferable to obtain a high magnetic flux density.

In addition to R, B, and Fe, it is possible to allow the presence of unavoidable impurities in industrial production. For example, a part of B may be 4.0 wt% or less of C, 2.0 wt% or less of P, .0
By replacing at least one of S by wt% or less and Cu by 2.0 wt% or less with a total amount of 2.0 wt% or less, it is possible to improve the productivity and reduce the cost of the permanent magnet.

Further, Al, Ti, V, Cr, Mn, B
i, Nb, Ta, Mo, W, Sb, Ge, Sn, Zr,
At least one of Ni, Si, Zn, and Hf is F
It can be added to the e-B-R permanent magnet material because it has the effect of improving the coercive force and the squareness of the demagnetization curve, improving the productivity, and reducing the price. The upper limit of the addition amount is preferably in a range that satisfies the above condition, since Br needs to be at least 9 kG or more in order to make (BH) max of the magnet material 20 MGOe or more.

The Fe-BR permanent magnet has a main phase of a compound having a tetragonal crystal structure having an average crystal grain size in a range of 1 to 80 μm, and a non-volume of 1% to 50% by volume. It is characterized by containing a magnetic phase (excluding an oxide phase). Fe
The -BR type permanent magnet has a coercive force iHc ≧ 1 kOe, a residual magnetic flux density Br> 4 kG, and a maximum energy product (B
H) max indicates (BH) max ≧ 10MGOe,
The maximum reaches 25 MGOe or more.

[0024]

【Example】

Example 1 A known casting ingot was pulverized, finely pulverized, then molded, sintered, heat-treated, and surface-processed to obtain 17Nd-1Pr-75F.
A magnet test piece having a composition of e-7B and having a diameter of 12 mm and a thickness of 2 mm was obtained. Table 2 shows the surface roughness of the obtained test piece, and Table 1 shows the magnet characteristics. The inside of the vacuum vessel was evacuated to 1 × 10 ⁻³ pa or less, the surface was sputtered at an Ar gas pressure of 10 pa and −500 V for 20 minutes to clean the surface of the magnet body, and then the ion plating conditions shown in Table 2 were obtained. The substrate magnet temperature was set to 250 ° C., and an Al coating layer having a thickness of 0.1 μm and a thickness of 1.8 μm was formed on the surface of the magnet body by arc ion plating using metal Al as a target.

Next, at a substrate magnet temperature of 350 ° C., a bias voltage of −100 V, and an arc current of 100 A, ₁ Pa of N ₂ gas was used.
, In 3 hours by the arc ion plating method
An AlN coating layer having a thickness of 3 μm was formed on the coating surface. Then, after cooling, the permanent magnet having the obtained AlN coating on the surface was allowed to stand for 1000 hours at a temperature of 80 ° C. and a relative humidity of 90%, and the magnet characteristics and the deterioration thereof were measured. 3 is shown.

COMPARATIVE EXAMPLE 1 A magnet specimen having the same composition as in Example 1 was subjected to surface cleaning under the same conditions as in Example 1, and then an AlN coating was formed on the magnet body to a thickness of 3 μm under the same conditions as in Example 1. Formed. Thereafter, under the same conditions as in Example 1 at a temperature of 80 ° C. and a relative humidity of 90%, 1
The properties of the magnet and its deterioration after being left for 000 hours were measured, and the results are shown in Table 3.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

As shown in Table 3, the comparative magnet having the AlN coating layer provided on the surface of the Fe-BR-based permanent magnet body having the same magnet characteristics has a temperature of 80 ° C. and a relative humidity of 90%. While the magnet properties before and after the corrosion resistance test left for a long time greatly deteriorated and rusted, the Fe-BR-based permanent magnet of the present invention provided with the AlN coating layer via the Al coating layer showed that It is clear that no magnetism occurs and the magnet properties hardly change.

[0031]

According to the present invention, the Fe-BR type permanent magnet body provided with the AlN coating layer on the magnet surface via the Al coating according to the present invention can be subjected to severe corrosion resistance test conditions, particularly at a temperature of 8
After leaving for 1000 hours under the conditions of 0 ° C. and 90% relative humidity, there is almost no deterioration of the magnet properties, and it is extremely suitable as a high performance and inexpensive permanent magnet which is most demanded at present.

That is, according to the present invention, after the surface of an Fe-BR based permanent magnet is cleaned by an ion sputtering method or the like, an Al film is formed on the surface of the magnet by a vapor deposition method such as an ion plating method. After the formation, an AlN film is formed by a vapor phase film forming method such as ion plating while introducing N ₂ gas under specific conditions, and the Al film is formed on the magnet body surface by forming an Al film on the magnet body surface. Oxide is partially or largely reduced, and the adhesion between the magnet body surface and the Al coating is improved. By laminating the AlN coating on the Al coating, the adhesion of the coating is remarkably improved. Corrosion resistance, especially temperature 80 ° C, relative humidity 90%
Even if left for a long time under the atmospheric conditions, the adhesion to the substrate is excellent, and the corrosion-resistant and abrasion resistance of the deposited corrosion-resistant metal film makes the magnetic properties of Fe-B stable.
An -R permanent magnet is obtained.

Claims (2)

[Claims] 1. A 0.06 μm-5.0 μm thick A—B—R based permanent magnet body having a tetragonal phase as a main phase.
(1) A corrosion-resistant permanent magnet having an AlN coating layer having a thickness of 0.5 μm to 10 μm via a coating. 2. After cleaning the surface of an Fe-BR-based permanent magnet whose main phase is a tetragonal phase, an Al film having a thickness of 0.06 μm to 5.0 μm is formed on the surface of the magnet in a vapor phase. A method for producing a corrosion-resistant permanent magnet, comprising: forming an AlN coating layer having a thickness of 0.5 μm to 10 μm by a vapor phase film forming method in an N ₂ gas atmosphere after forming by a method.