JPH07283017A - Corrosion resistant permanent magnet and production thereof - Google Patents

Abstract

PURPOSE:To enhance the corrosion resistance by forming a TiN film of specified thickness on the surface of an Fe-B-R based permanent magnet through an Al coating and a TiAlN coating having specified thicknesses. CONSTITUTION:An Fe-B-R based permanent magnet body having a main phase of tetragonal system is cleaned on the surface thereof and an Al coating of 0.06mum-5.0mum thick is deposited on the surface of the magnet body by vapor- phase filming method. Subsequently, a TixAl1-xNy coating(x=0.1-0.9, y=0.2-1.0) of 0.05-2.0mum thick is formed by vapor-phase filming method in an N2 gas atmosphere followed by formation of a TiN coating of 0.5-10mum thick by vapor-phase filming method in an N2 gas atmosphere thus producing a corrosion resistant permanent magnet. This method produces an Fe-B-R based permanent magnet excellent in the adhesion to the substrate in which the magnet characteristics are stabilized through the corrosion resistance and abrasion resistance of the corrosion resistant metal coating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fe-B-R permanent magnet provided with a corrosion resistant coating having high magnetic properties, excellent adhesion, and excellent corrosion resistance, acid resistance, alkali resistance and wear resistance. However, the corrosion resistance in which a TiN coating layer is provided with a specific film thickness through an Al coating and a Ti _x Al _1-x N _y coating layer, especially 8
The present invention relates to a corrosion-resistant permanent magnet having little deterioration from initial magnet characteristics when left in an atmosphere of 0 ° C. and 90% relative humidity for a long time, and having extremely stable magnet characteristics, and a manufacturing method thereof.

[0002]

2. Description of the Related Art First, a light rare earth which is rich in resources centering on Nd and Pr is used as a main component of B and Fe, and does not contain expensive Sm or Co. As a new high-performance permanent magnet that greatly exceeds the characteristics, F
An e-B-R permanent magnet has been proposed (JP-A-59-59).
46008, JP-A-59-89401).

The Curie point of the magnet alloy is generally 30.
It is 0 ° C to 370 ° C, but Fe-B- having a higher Curie point by substituting a part of Fe with Co.
R-based permanent magnet (JP-A-59-64733, JP-A-59)
-132104), and further has a Curie point equal to or higher than that of the Fe-BR rare earth permanent magnet containing Co and a higher (BH) max, and improves its temperature characteristics, particularly iHc. Therefore, Co-containing F mainly composed of light rare earth elements such as Nd and Pr as rare earth elements (R)
By containing at least one kind of heavy rare earths such as Dy and Tb in a part of R of the e-B-R rare earth permanent magnet, iHc can be maintained while maintaining extremely high (BH) max of 25 MGOe or more. Further improved Co-containing F
Proposed e-BR rare earth permanent magnet (Japanese Patent Laid-Open No. 60-34)
No. 005).

However, the permanent magnet composed of the Fe--BR system magnetically anisotropic sintered body having the above-mentioned excellent magnetic properties is a tetragonal crystal containing, as a main component, a rare earth element which is easily oxidized in air and iron. Since it has a crystalline structure with a phase as the main phase, when it is incorporated in a magnetic circuit, the oxide generated on the surface of the magnet causes a decrease in the output of the magnetic circuit and a variation between the magnetic circuits. There was a problem of contamination of peripheral equipment due to the dropout.

[0005]

Therefore, the above Fe-
In order to improve the corrosion resistance of the B-R permanent magnet, there has been proposed a permanent magnet (Japanese Patent Publication No. 3-74012) in which the surface of the magnet is coated with a corrosion-resistant metal plating layer by electroless plating or electrolytic plating. In this plating method, since the permanent magnet body is a sintered body and has porosity, the acidic solution or alkaline solution in the pretreatment of plating may remain in this hole, and there is a risk of corrosion over time. Since the chemical resistance is poor, the surface of the magnet is corroded during plating, resulting in poor adhesion and corrosion resistance. Moreover, even if corrosion resistant plating is provided,
1 in the corrosion resistance test under the conditions of temperature 60 ℃ and relative humidity 90%
When left standing for 00 hours, the magnet characteristics deteriorated by 10% or more of the initial magnet characteristics and were very unstable.

Therefore, in order to improve the corrosion resistance of the Fe-BR type permanent magnet, TiN and T are formed on the surface of the magnet by an ion plating method, an ion sputtering method or the like.
It has been proposed (Japanese Patent Publication No. 5-15043) to apply an i-coat to improve the corrosion resistance. However, Ti
The N-coating has poor adhesion because it has a different thermal expansion coefficient, ductility, etc. from the Fe-BR magnet, and the Ti coating has good adhesion and corrosion resistance, but low wear resistance. Therefore, it has been proposed (Japanese Patent Laid-Open No. 63-9919) to apply a laminated coating film of Ti and TiN on the surface of the Fe-BR type permanent magnet body. However, since the Ti coating and the TiN coating have different crystal structures, coefficients of thermal expansion, ductility, and the like, there is a problem in that the adhesion is poor, peeling occurs, and the corrosion resistance decreases.

The present invention has excellent adhesion to a Fe-BR system permanent magnet substrate, and has the purpose of improving abrasion resistance and corrosion resistance, and especially for a long time under an atmospheric condition of a temperature of 80 ° C. and a relative humidity of 90%. It is an object of the present invention to provide a Fe-BR permanent magnet having stable high magnet characteristics, abrasion resistance, and corrosion resistance at a low cost by minimizing deterioration from the initial magnet characteristics when left standing for a long time.

[0008]

Means for Solving the Problems The inventors of the present invention have excellent corrosion resistance, and in particular, even when left for a long time under an atmospheric condition of a temperature of 80 ° C. and a relative humidity of 90%, the adhesiveness to a substrate is excellent and the adhesion is excellent. As a result of various studies on the method of forming a TiN coating on the surface of a permanent magnet, for the purpose of an Fe-BR permanent magnet that can obtain stable magnet characteristics due to the corrosion resistance and wear resistance of the corrosion-resistant metal coating, 1) Magnet After cleaning the body surface by an ion sputtering method or the like, 2) Al having a specific film thickness on the surface of the magnet body by a vapor deposition method such as an ion plating method or an ion sputtering method.
After forming the coating film, 3) while introducing N ₂ gas under specific conditions, a Ti _x Al _1-x film with a specific film thickness is formed by a vapor deposition method such as an ion plating method using 2 targets or an ion sputtering method.
N _y (however, x = 0.1~0.9, y = 0.2~1 .
0) After forming the film, 4) while introducing N ₂ gas under specific conditions onto the film,
By forming a TiN film with a specific thickness by the vapor phase film formation method, a) Oxides adhering to the magnet surface are partially or mostly reduced by the deoxidizing action of the Al film. Adhesion between the magnet and the Al coating is significantly improved. B) By forming a Ti _x Al _1-x N _y layer as an intermediate layer, N diffuses as diffusion atoms at the Al coating interface, so N atoms, TiAl with few Ti atoms and many Al atoms
A reaction layer of N is generated, and c) In addition, there are few Al atoms at the TiN coating interface,
By generating a TiAlN reaction layer containing many atoms,
The inventors have found that the adhesion between the Al coating and the TiN coating can be remarkably improved, and completed the present invention.

That is, according to the present invention, a film thickness of 0.06 μm is formed on the surface of the Fe-BR permanent magnet body whose main phase is a tetragonal phase.
m-5.0 μm Al coating layer and film thickness 0.05 μm-
2.0 μm Ti _x Al _1-x N _y coating layer (where x = 0.
1 to 0.9, y = 0.2 to 1.0) and a film thickness of 0.5
It is a corrosion-resistant permanent magnet having a TiN coating layer with a thickness of 10 μm to 10 μm.

Further, according to the present invention, after cleaning the surface of the Fe-BR type permanent magnet body whose main phase is a tetragonal phase, an Al coating having a film thickness of 0.06 μm to 5.0 μm is formed on the surface of the magnet body. After forming by the vapor phase film formation method, Ti _x Al _1-x having a film thickness of 0.05 μm to 2.0 μm by the vapor phase film formation method in an N ₂ gas atmosphere.
N _y coating layer (provided that x = 0.1 to 0.9, y = 0.2 to
1.0), and thereafter, a TiN coating layer having a film thickness of 0.5 μm to 10 μm is formed in a N ₂ gas atmosphere by a vapor phase film forming method, which is a method for producing a corrosion-resistant permanent magnet.

In the present invention, an Al film deposited on the surface of the Fe-BR type permanent magnet body, a Ti _x Al _1-x N _y film,
A so-called vapor phase film forming method such as an ion plating method, an ion sputtering method, or a vapor deposition method can be appropriately used as a method for forming the TiN film. However, due to reasons such as film density, uniformity, and film forming speed, ion plating, Reactive ion plating is preferred. The vapor phase film forming method for forming the Al film is preferably performed in an Ar gas atmosphere.
i _x Al _1-x N _y film formation of Al as the target, Ti
Ion plating is performed by using two targets of No. 2 and separate arc power supplies, but the arc voltage (arc current) applied to each target, which is generally called MA method (multi-arc ion plating method), is changed. Te, Ti _x Al
A method of changing the x value and the y value of the composition ratio of the _{1- xNy} coating layer can be adopted. The TiN film is formed by a vapor phase film forming method in an N ₂ gas atmosphere. Further, the temperature of the permanent magnet serving as the substrate at the time of reaction film formation is preferably set to 200 ° C to 500 ° C, and if the temperature is less than 200 ° C, the reaction adhesion with the substrate magnet is insufficient, and if it exceeds 500 ° C, it is at room temperature ( The temperature difference between the substrate magnet and the substrate magnet is set to 200 to 500 ° C. Therefore, the coating film cracks in the cooling process after the treatment and peels off from the substrate partially.

Manufacture of the corrosion-resistant permanent magnet according to the present invention, characterized in that a TiN coating layer is provided on the surface of the Fe-BR permanent magnet body through an Al coating layer and a Ti _x Al _1-x N _y coating layer. An example of the method will be described in detail below. 1) Using an arc ion plating device, the vacuum container was evacuated to a vacuum degree of 1 × 10 ⁻³ pa or less, and then Fe—B— by surface sputtering with Ar ions at an Ar gas pressure of 10 pa and −500 V. Clean the surface of the R-type magnet body. 2) Next, Ar gas pressure 0.1 pa, bias voltage -50
V, the magnet temperature of the substrate is set to 300 ° C., and the target Al
Is evaporated and an Al coating layer having a thickness of 0.06 μm to 5.0 μm is formed on the surface of the magnet body by an arc ion plating method. 3) Next, N ₂ gas pressure 1.5 Pa, bias voltage −10
0V, the magnet temperature of the substrate is kept at 350 ° C, Al, Ti
_No. 2 target, and a Ti _x Al _1-x N _y coating layer (where x = 0.1 to 0.9, y = 0.2 to 1. 0) is formed. In this case, N diffuses as diffusing atoms at the Al coating interface, so that the Ti _x Al _1-x N _y coating layer is N
Ti with few atoms, few Ti atoms, and many Al atoms
_{A x} Al _1-x N _y reaction layer is formed. 4) Subsequently, Ti was used as a target, the magnet temperature of the substrate was kept at 250 ° C., and the Ti was heated under the conditions of N ₂ gas pressure of 1 pa, bias voltage of −100 V, and arc current of 100 A.
Although a TiN coating film layer of a specific thickness in _x Al _1-x N _y film layer, at the interface of the TiN film and the Ti _x Al _1-x N _y film layer, less Al atom, a lot of Ti atom TiAlN
A reaction layer is produced.

In the present invention, the reason why the Al film thickness on the surface of the Fe-BR permanent magnet body is limited to 0.06 μm to 5.0 μm is that the Al film thickness on the surface of the magnet body is less than 0.06 μm.
Is difficult to apply evenly, and the effect as a base film is not sufficient,
If it exceeds 5.0 μm, there is no problem effectively, but since it causes cost increase as an underlying film and is not practical and preferable, the Al film thickness is set to 0.06 μm to 5.0 μm. In particular, the Al film thickness is selected according to the surface roughness of the magnet body. When the surface roughness is 0.1 μm or less, the Al film thickness is preferably 0.06 μm to 5.0 μm, and the surface roughness is 0.1 μm to When 1.2 μm, the desired film thickness is 0.1
It is μm to 5.0 μm.

In the present invention, the reason why the Ti _x Al _1-x N _y coating thickness is limited to 0.05 μm to 2.0 μm is 0.0.
If it is less than 5 μm, sufficient adhesion with the TiN coating cannot be obtained, and if it exceeds 2.0 μm, there is no problem in terms of effectiveness, but this is not preferable because it causes an increase in manufacturing cost. T
In the i _x Al _1-x N _y coating, if x is less than 0.1 or exceeds 0.9, the reaction at the interface does not proceed and sufficient adhesion cannot be obtained. It is set to 0.9. Further, when y is less than 0.2, the structure of the nitride is unstable, and when it exceeds 1.0, free nitrogen is always liable to cause peeling of the film, so that y is 0.2 to 0. .1.

The TiN film thickness is 0.5 μm to 10 μm.
The reason for limiting to m is less than 0.5 μm, the corrosion resistance and wear resistance as TiN are not sufficient, and if it exceeds 10 μm, there is no problem effectively, but it is not preferable because it causes an increase in manufacturing cost.

In the present invention, the rare earth element R used in the permanent magnet occupies 10 atom% to 30 atom% of the composition, and at least one of Nd, Pr, Dy, Ho and Tb is used.
Seed, or even 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,
Zijim, etc.) can be used for reasons of availability. Incidentally, this R does not have to be a pure rare earth element,
It does not matter even if it contains impurities that are unavoidable in manufacturing within the industrially available range. R is an essential element in the above-mentioned permanent magnet, and if less than 10 atomic%, the crystal structure is α-.
Since it has a cubic structure with the same structure as iron, high magnetic properties, especially high coercive force, cannot be obtained. If it exceeds 30 atomic%, the R-rich nonmagnetic phase increases and the residual magnetic flux density (Br) decreases. A permanent magnet with excellent characteristics cannot be obtained. Therefore, R1
The range of 0 atom% to 30 atom% is desirable.

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

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

In addition to R, B and Fe, the presence of impurities that are unavoidable in industrial production can be tolerated. For example, part of B is 4.0 wt% or less of C, 2.0 wt% or less of P, 2 .0
By substituting at least one of S of 2.0 wt% or less and Cu of 2.0 wt% or less with a total amount of 2.0 wt% or less, it is possible to improve the manufacturability of the permanent magnet and reduce the cost.
Furthermore, Al, Ti, V, Cr, Mn, Bi, Nb, T
a, Mo, W, Sb, Ge, Sn, Zr, Ni, Si,
At least one of Zn and Hf is effective for improving the coercive force and squareness of the demagnetization curve, improving the manufacturability, and lowering the price of the Fe—BR permanent magnet material. It can be added. Note that the upper limit of the addition amount is B in order to make the (BH) max of the magnet material 20 MGOe or more.
Since r is required to be at least 9 kG or more, a range satisfying the condition is desirable.

Further, the Fe-BR permanent magnet has a compound having a tetragonal crystal structure having an average crystal grain size in the range of 1 to 80 μm as a main phase and a volume ratio of 1% to 50% of a non-crystal. It is characterized by containing a magnetic phase (excluding an oxide phase). Fe
The −BR permanent magnet exhibits 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 ≧ 10 MGOe,
The maximum value reaches 25 MGOe or more.

[0021]

According to the present invention, after the surface of the Fe-BR type permanent magnet body is cleaned by the ion sputtering method or the like, the surface of the magnet body is formed by the vapor deposition method such as the ion plating method.
After forming the l coating, Ti _x Al is formed by a vapor deposition method such as ion plating while introducing N ₂ gas under specific conditions.
_1-x N _y coating and TiN coating are formed,
By forming the Al coating on the surface of the magnet body, a part or most of the oxide on the surface of the magnet body is reduced, the adhesion between the surface of the magnet body and the Al coating is improved, and further Ti _x Al _{1 is formed} on the Al coating. by laminating _-x N _y film, in the Al film surface to form a large Ti _x Al _1-x N _y reaction layer of Al atom, a lot of Ti atoms in TiN coating interface T
The iAlN reaction layer is formed, the adhesion of the TiN coating is remarkably improved, and the excellent corrosion resistance, especially the adhesion with the base even when left for a long time under the atmospheric conditions of temperature 80 ° C and relative humidity 90% , The corrosion resistance of the adhered corrosion-resistant metal film and the wear resistance make it possible to obtain a stable magnetic property of F.
An e-B-R permanent magnet is obtained.

[0022]

【Example】

Example 1 A known casting ingot was crushed, finely crushed, and then molded, sintered, heat-treated, and surface-treated, and then 15Nd-77Fe-8B.
A magnet test piece having a composition of 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, and surface sputtering was performed at Ar gas pressure of 10 pa and −500 V for 20 minutes to clean the surface of the magnet body, and then Table 2
Set the substrate magnet temperature to 2 under the ion plating conditions shown in
The temperature is set to 50 ° C. and 0.1 μ is applied to the surface of the magnet body by arc ion plating method using metallic Al as a target.
An Al coating layer having a thickness of m and a thickness of 1.8 μm was formed. Next, the substrate magnet temperature was 350 ° C., and the bias voltage was −100.
V, arc current 100 A, N ₂ gas 1.5 Pa, evaporation was performed for 1 hour by an arc ion plating method using two targets of Al and Ti, and Al was evaporated.
A Ti _0.4 Al _0.6 N _0.8 coating layer having a thickness of 1 μm was formed on the coating. Next, the substrate magnet temperature is 350 ° C., the bias voltage is -1
00V, arc current 100A, N ₂ gas 1pa,
A TiN coating layer having a film thickness of 3 μm was formed in 3 hours by arc ion plating method using metal Ti as a target. Then, after allowing to cool, the permanent magnet having the obtained TiN coating on the surface was placed under the conditions of a temperature of 80 ° C. and a relative humidity of 90%.
The magnet characteristics and its deterioration state after standing for 000 hours were measured, and the results are shown in Table 3.

Comparative Example 1 A magnet body test piece having the same composition as in Example 1 was surface-cleaned under the same conditions as in Example 1, and then a TiN coating film was formed on the magnet body to a thickness of 3 μm under the same conditions as in Example 1. Formed. Then, under the same temperature of 80 ° C. and relative humidity of 90% as in Example 1, 1
The magnet characteristics and its deterioration state after standing for 000 hours were measured, and the results are shown in Table 3.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

As shown in Table 3, the comparative magnet having the TiN coating layer on the surface of the Fe-BR permanent magnet having the same magnet characteristics was 1000 at a temperature of 80 ° C and a relative humidity of 90%. While the deterioration of the magnet characteristics before and after the corrosion resistance test that left for a long time was large and rusting occurred, the Al coating layer and Ti
Fe-B-R based permanent magnet of the present invention in which a TiN coating film layer through the _x Al _1-x N _y layer, rust is not generated, the magnet properties are also apparent that almost no change.

[0028]

EFFECT OF THE INVENTION Fe in which a TiN coating layer is provided on the surface of a magnet according to the present invention through an Al coating and a Ti _x Al _1-x N _y layer
The -B-R permanent magnet body showed almost no deterioration in its magnetic properties after being left for 1000 hours under severe corrosion resistance test conditions, particularly at a temperature of 80 ° C and a relative humidity of 90%, as in the examples. Currently, it is extremely suitable as the most demanded high-performance and inexpensive permanent magnet.

Claims (2)

[Claims] 1. A film having a thickness of 0.06 .mu.m to 5.0 .mu.m is formed on the surface of a Fe-BR permanent magnet whose main phase is a tetragonal phase.
l coating layer and Ti _x A having a thickness of 0.05 μm to 2.0 μm
l _1-x N _y coating layer (where x = 0.1 to 0.9, y = 0.
2 to 1.0), a T having a film thickness of 0.5 μm to 10 μm
A corrosion-resistant permanent magnet having an iN coating layer. 2. After cleaning the surface of the Fe—B—R permanent magnet body whose main phase is a tetragonal phase, an Al coating having a film thickness of 0.06 μm to 5.0 μm is vapor-phase formed on the surface of the magnet body. A Ti _x Al _1-x N _y coating layer having a thickness of 0.05 μm to 2.0 μm (where x = 0.1 to 0.9 and y = 0.2 to 1.
0) is formed, and then a TiN coating layer having a film thickness of 0.5 μm to 10 μm is formed by a vapor phase film forming method in an N ₂ gas atmosphere.