JPH1083905A - Corrosion-resistant permanent magnet and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase corrosion resistance and abrasion resistance and stabilize magnetic characteristic by forming a Ti1-x Alx N (0.03<x<0.70) coating layer having a specific thickness via an Al coating film having a specific thickness on the surface of a Fe-B-R permanent magnet having a tetragonal phase as its main phase. SOLUTION: A vacuum container is exhausted to vacuum level of 1×10<-3> pa or less by using an arc ion plating device, and the surface of the Fe-B-R magnet is cleaned by surface sputtering using Ar ions. Next, Al as a target is evaporated to form the Al. coating layer having a thickness of 0.06-5.0 p, by arc ion plating, on the surface of the magnet. Next, the Ti1-x Alx N (0.03 < x < 0.70) coating layer having a thickness of 0.5-10μm is formed, by using Ti1-y Aly (0.03<y<0.80) as a target, while maintaining the magnet temperature of the substrate 250 deg.C, in N2 gas having pressure of 3pa, with a bias voltage of -120V, on the Al coating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Fe-BR-based permanent magnet provided with a corrosion-resistant coating having high magnetic properties, excellent adhesion, and excellent corrosion resistance, acid resistance, alkali resistance and abrasion resistance. In connection with this, a Ti _1-x Al _x N coating layer is provided with a specific film thickness via an Al coating, particularly at 80 ° C. and a relative humidity of 90 °.
% Permanent magnet with little deterioration from initial magnet properties when left in a% atmosphere for a long time and having extremely stable magnet properties, and a method for producing 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, TiN, AN is applied to the surface of the magnet by ion plating, ion sputtering or the like.
It has been proposed to improve the corrosion resistance by applying a 1 film (Japanese Patent Publication No. 5-15043). However, Ti
The N film has poor adhesion due to differences in the thermal expansion coefficient, ductility, etc., besides the crystal structure of the Fe-BR system magnet body, and the Al film has good adhesion and corrosion resistance, but has abrasion resistance. There was a problem such as low.

[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. corrosion resistance of the corrosion-resistant metal coating, the abrasion resistance, the results of various studies on Ti _1-x Al _x N coating film formation method of the stable Fe-B-R based permanent magnet of the magnetic properties to the permanent magnet body surface to the purpose After the surface of the magnet body is cleaned by an ion sputtering 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. _Two
While introducing the gas, a specific layer thickness of Ti is formed by a vapor phase film forming method such as ion plating and ion sputtering.
By forming a _1-x Al _x N coating, the oxide on the magnet surface is reduced by the Al coating to reduce a part or most of the oxide on the magnet surface, and the adhesion between the magnet and the Al coating Properties are significantly improved and Ti _1-x Al _x
In forming the N film, the interface is Ti _{1- ■} Al _■ N _■
Ti, Al, a composite film of N generated composed, the Ti _1-■
The composition and film thickness of Al _■ N _■ vary depending on the substrate temperature, bias voltage, film-forming speed, etc., so that Ti and N continuously increase toward the Ti _1-x Al _xN interface.
It has been found that the adhesion between the Al coating and the Ti _1-x Al _x N coating can be remarkably improved by this, 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
A corrosion-resistant permanent magnet and having a Ti _1-x Al _x N coating layer of 0 .mu.m.

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 a Ti _1-x Al _x N film layer having a thickness of 0.5 μm to 10 μm by a gas phase film forming method in an N ₂ gas atmosphere after forming by a phase film forming method. Is the way.

In the present invention, as a method of forming an Al film and a Ti _1-x Al _x N film to be adhered on the surface of the Fe—BR based permanent magnet body, there are ion plating, ion sputtering, vapor deposition and the like. The so-called vapor phase film forming method can be appropriately used, and ion plating and reactive ion plating are preferable from the viewpoints of film density, uniformity, and film formation speed.

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 a method for producing a corrosion-resistant permanent magnet according to the present invention, characterized in that a Ti _1-x Al _x N 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. 1) The vacuum vessel was evacuated to an ultimate vacuum of 1 × 10 ⁻³ pa or less using an arc ion plating apparatus, and then Fe—B— was sputtered with Ar ions at a surface pressure of −300 V at an Ar gas pressure of 10 Pa. 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) Subsequently, Ti _1-y Al _y (0.03
<Y <0.80), the magnet temperature of the substrate was kept at 250 ° C., the N ₂ gas pressure was 3 pa, the bias voltage was −120 V, and a specific thickness of Ti _1-x Al _x was formed on the Al coating layer. An N coating layer is formed.

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.

The thickness of the Ti _1-x Al _x N coating is 0.5 μm
The reason for limiting the thickness to 10 to 10 μm is that if the thickness is less than 0.5 μm
The corrosion resistance and abrasion resistance of the _1-x Al _x N film are not sufficient, and if it exceeds 10 μm, there is no problem effectively, but it is not preferable because it increases the production cost. Also, Ti _1-x
The reason why the value of x is limited in the Al _x N coating is as follows.
If it is less than 03, the performance as a Ti _1-x Al _x N coating, that is, corrosion resistance and abrasion resistance cannot be obtained, and if it exceeds 0.70, no improvement in performance can be obtained.

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]

EXAMPLES Example 1 A known casting ingot was pulverized, finely pulverized, molded, sintered, heat-treated, and surface-treated to obtain 17Nd-1Dy-76F.
A magnet test piece having a composition of e-6B 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 magnet body surface, 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 0.2 μm and 1.6 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 −120 V and an N ₂ gas of 3 pa, an alloy of Ti _0.5 and Al _0.5 as a target was applied to the surface of the Al film by an arc ion plating method for 3 hours to form a film having a thickness of 3 μm. Ti _1-x Al _x
An N coating layer was formed. The composition of the formed film is Ti _0.55 Al _0.45 N
Met. Then, after cooling, the obtained Ti _0.55 Al
_The properties and deterioration of the permanent magnet having the _0.45 N coating film on the surface after standing for 1000 hours at a temperature of 80 ° C. and a relative humidity of 90% were measured, and the results are shown in Table 3.

COMPARATIVE EXAMPLE 1 A test piece of a magnet body having the same composition as in Example 1 was cleaned under the same conditions as in Example 1, and then directly on the magnet body under the same conditions as in Example 1 with Ti _0.55 Al _0.45 N. The coating was formed to a thickness of 3 μm. Thereafter, the same temperature of 80 ° C. and relative humidity of 9
The properties of the magnet and the state of deterioration after 1000 hours of standing at 0% 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 in which the Ti _1-x Al _x N coating layer was provided on the surface of the Fe—BR based permanent magnet body having the same magnet characteristics was at a temperature of 80 ° C. and a relative humidity of 90 °. % Of the magnets before and after the corrosion resistance test which was left for 1000 hours under the condition of 0.1%, and rusted, whereas the Ti _1-x Al _x N coating layer was provided via the Al coating layer. Fe
It is clear that rust does not occur in the -BR type permanent magnet and the magnet characteristics hardly change.

[0031]

According to the present invention, after the surface of the Fe-BR based permanent magnet is cleaned by ion sputtering or the like, an Al coating is formed on the surface of the magnet by a vapor phase film forming method such as ion plating. After the formation, while introducing N ₂ gas under specific conditions, Ti 2
It is characterized by forming a _1-x Al _x N coating, and by forming an Al coating on the surface of the magnet body, the oxide on the surface of the magnet body is partially or mostly reduced, and the oxide on the magnet body surface and the Al coating Adhesion is improved, and Ti _1-x A
By laminating l _x N film, as in Example, good corrosion resistance, in particular the temperature 80 ° C., even when the left for a long time in an atmosphere under a relative humidity of 90%, good adhesion to the underlying layer, the Due to the corrosion resistance and wear resistance of the deposited corrosion-resistant metal film, a Fe-BR-based permanent magnet having stable magnet properties can be 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.
l 1-0.5 μm to 10 μm-thick Ti _1-x A
l _x N (where, 0.03 <x <0.70) corrosion-resistant permanent magnet and having a coating layer. 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. After forming by a method, a Ti _1-x Al _x N (0.5 to 10 μm thick) film is formed in a N ₂ gas atmosphere by a vapor phase film forming method.
3 <x <0.70) A method for producing a corrosion-resistant permanent magnet, comprising forming a coating layer.