JPH10106818A - Permanent magnet for ultra high vacuum and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet for ultra high vacuum which has good adhesion of a coating film thereon, is tight, can prevent the generation and release of gas from the magnet body, and has a high magnetic characteristic used for an undulator, etc., in the ultra high vacuum of below 1×10<-9> Pa. SOLUTION: After the surface of an Fe-B-R permanent magnet body is cleaned by an ion sputtering method, etc., an aluminum coating film of 0.06 to 5.0×m thickness is formed on the surface of the permanent magnet body by a method for firming a thin film such as an ion plating method, etc. An AlN coating film of 5.0 to 20μm thickness is formed on the aluminum coating film in an atmosphere of N2 gas by a method for forming a thin film such as an ion reaction plating method, etc. The can prevent the generation of a gas adhering to the magnet or absorbed by the magnet, and enables effective use of high magnetic characteristics of the magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-high vacuum permanent magnet having high magnetic properties which can be used for an undulator or the like in an ultra-high vacuum atmosphere. By forming a film, it is excellent in adhesion of the film, is dense, prevents gas generation and release from the magnet body, can be used in an ultra-high vacuum of 1 × 10 ⁻⁹ Pa or less, and has extremely stable magnetic properties. The present invention relates to an ultra-high vacuum permanent magnet 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).

[0004] The Curie point is higher than or equal to that of the Co-containing Fe-BR based rare earth permanent magnet and the (BH) m is higher.
ax and a part of R of a Co-containing Fe-BR-based rare earth permanent magnet mainly containing light rare earths such as Nd and Pr as rare earth elements (R) in order to improve its temperature characteristics, particularly iHc. At least one of heavy rare earths such as Dy and Tb.
Proposal of a Co-containing Fe-BR based rare earth permanent magnet further improved in iHc while retaining a very high (BH) max of 25 MGOe or more by containing a seed (Japanese Patent Application Laid-Open No. 60-34005) ) Has been.

Conventionally, as a magnet for a vacuum atmosphere, a ferrite magnet has been used in a vacuum of the order of 10 ⁻³ Pa. However, the ferrite magnet has low magnetic properties and does not have sufficient magnetic properties to be used for an undulator or the like. .

That is, as a magnet for an ultra-high vacuum that can be used in an ultra-high vacuum of 1 × 10 ⁻⁹ Pa or less, (1) excellent magnet properties, (2) release of a built-in gas and an attached gas from the magnet, No radiation, (3) 1 ×
It is important that 10 ^-9 Pa or less can be achieved.

Therefore, as described above, since the Fe-BR based magnet has high magnetic properties, it can be used for an undulator for ultra-high vacuum of 1 × 10 ⁻⁹ Pa or less.
Because the BR magnet absorbs and absorbs gas, the degree of vacuum is 1 × due to the gas generated and released from the magnet in a vacuum atmosphere.
In an ultra-high vacuum atmosphere of 10 ⁻⁹ Pa or less, it was difficult to use a Fe—BR magnet.

[0008]

Conventionally, when a Ni-plated Fe-BR-based magnet for corrosion protection is used in an ultra-high vacuum, the magnet cannot be placed in an ultra-high vacuum chamber, Since the mounting, the undulator, and the like were manufactured, the size of the apparatus was increased, and the high magnetic characteristics of the Fe-BR-based magnet could not be effectively used.

[0009] Even a conventional corrosion-resistant Fe-BR permanent magnet having various coatings for the purpose of improving the corrosion resistance of a conventional Fe-BR-based magnet body, the vacuum generated by the magnet in a vacuum atmosphere and the gas released therefrom cause a vacuum. It was difficult to use it in an ultra-high vacuum atmosphere having a degree of 1 × 10 ⁻⁹ Pa or less.

The present invention relates to a conventional corrosion-resistant F-B-R magnet having various coatings for the purpose of improving the corrosion resistance.
Unlike e-B-R permanent magnets, they have excellent adhesion to the surface of the magnet body and have a dense coating that prevents gas generation and release from the magnet body. It is an object of the present invention to provide an ultra-high vacuum permanent magnet having high magnetic properties that can be used for such purposes.

[0011]

Means for Solving the Problems The inventors of the present invention have excellent adhesion to a base and can prevent generation of gas adhering to or occluded by a magnet by a dense metal coating applied thereto. As a result of various studies on a method of forming an AlN coating on the surface of the permanent magnet body for the purpose of producing a stable Fe-BR-based permanent magnet, the magnet body surface was cleaned by an ion sputtering method or the like, and then the magnet body surface was cleaned. After forming an Al film having a specific thickness by a thin film forming method such as an ion plating method, a thin film forming method such as an ion reaction plating is performed in N ₂ gas to form AlN having a specific thickness. Al has excellent adhesion to the base, and when an AlN film is formed on the Al film, a composite film of Al and N, which is AlNx, is formed at the interface. Ba The composition is such that N changes continuously depending on the ass voltage, the film forming speed, etc., and N continuously increases toward the AlN interface, whereby the adhesion between the Al film and the AlN film can be significantly improved. To achieve a degree of vacuum of 1 × 10 ^-9 Pa or less,
The present inventors have found that the present invention is most suitable for an undulator for ultra-high vacuum, and have completed the present invention.

That is, according to the present invention, a film having a thickness of 0.06 mm is formed on the surface of an Fe—BR-based permanent magnet body whose main phase is a tetragonal phase.
forming an Al coating having a thickness of 0.5 μm to 5.0 μm
An ultrahigh vacuum permanent magnet having an AlN coating layer of 10 to 10 μm.

Further, according to the present invention, an Al coating having a thickness of 0.06 μm to 5.0 μm is formed on the surface of the permanent magnet body after cleaning the surface of the Fe—BR based permanent magnet body having a tetragonal phase as a main phase. Forming an AlN coating layer having a film thickness of 0.5 μm to 10 μm in a N ₂ gas atmosphere by a gas phase film forming method after forming the AlN film layer by a gas phase film forming method. It is.

[0014]

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 to 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 manufacturing a permanent magnet for ultra-high vacuum of the present invention, characterized in that an AlN coating layer is provided on the surface of the Fe-BR-based permanent magnet body via an Al coating layer, will be described in detail below. I do. 1) After evacuating the vacuum vessel to an ultimate vacuum of 1 × 10 ⁻³ pa or less using an arc ion plating apparatus, the vacuum vessel is evacuated at an Ar gas pressure of 10 pa and −500 V.
The surface of the Fe-BR-based magnet body is cleaned by surface sputtering using r ions.

2) Next, the target Al is evaporated by an Ar gas pressure of 0.1 pa and a bias voltage of −50 V, and the thickness of the target is 0.06 μm to 5.0 μm on the surface of the magnet body by an arc ion plating method. Is formed.

3) Subsequently, an AlN coating layer having a specific thickness is formed on the Al coating layer under the conditions that the magnet temperature of the substrate is maintained at 250 ° C., the N ₂ gas pressure is 1 pa, and the bias voltage is −100 V.

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, the surface of the magnet body has an aluminum coating.
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 AlN film thickness is set to 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 becomes a cubic structure having the same structure as that of α-iron, so that high magnetic properties, particularly 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 permanent magnets. If it is less than 2 atomic%, the rhombohedral structure becomes the main phase, and a high coercive force (iHc) cannot be obtained. If it exceeds 28 atomic%, B becomes rich. 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, the presence of unavoidable impurities in industrial production can be tolerated. For example, 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-based 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 has 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.

[0028]

【Example】

Example 1 A known casting ingot was pulverized, finely pulverized, molded, sintered, and heat-treated to obtain 16Nd-1Pr-76Fe-7B.
A magnet test piece having a composition having a diameter of 12 mm and a thickness of 2 mm was obtained. Put the magnet in a vacuum vessel,
Exhaust to 0 ^-3 pa or less, Ar gas pressure 5 pa, -600 V
After performing surface sputtering for 20 minutes to clean the surface of the magnet body, an Ar gas pressure of 0.2 pa and a bias voltage of −80 were applied.
V. A 1.5 μm thick Al coating layer is formed on the surface of the magnet body by arc ion plating using metal Al as a target at a substrate magnet temperature of 250 ° C.

Next, the substrate magnet was heated at 350 ° C.
An AlN coating layer having a thickness of 3 μm was formed on the surface of the Al coating by arc ion plating at 100 V and an arc current of 100 A with N ₂ gas at 1 pa. Thereafter, after cooling, the magnetic properties of the obtained permanent magnet having an AlN coating were measured, and the results are shown in Table 1. The ultimate vacuum degree of the obtained permanent magnet was measured by the ultrahigh vacuum apparatus shown in FIG. FIG. 2 shows the measurement results.

The method of measuring the ultimate vacuum by the ultra-high vacuum apparatus shown in FIG. 1 will be described. The ultra-high vacuum apparatus 1 has a long cylindrical body 2 having a Ti getter pump 4, an ion pump 5, and a BA gauge. 6 and an extractor gauge 7 are provided, respectively.
Is provided.

First, without inserting the magnet sample 8 into the sample chamber 3, the Ti getter pump 4 and the ion pump 5 are operated and evacuated, baked at 150 to 200 ° C. for 48 hours, and then cooled and cooled. After the temperature in 2 becomes 70 ° C. or lower, the BA gauge 6 and the extractor gauge 7 are operated to measure the ultimate vacuum degree. The final vacuum degree was 7 × 10 ⁻¹⁰ Pa. This is indicated by a in FIG.

Next, the size, height 8 mm × width 8 are set in the sample chamber 3.
The magnet sample 8 having a size of 50 mm × length 50 mm and a quantity of 60 was inserted, and the Ti getter pump 4 and the ion pump 5 were operated and evacuated, baked at 150 to 200 ° C. for 48 hours, and then allowed to cool. After the temperature in the main body 2 becomes 70 ° C. or lower, the ultimate vacuum degree is measured by operating the BA gauge 6 and the extractor gauge 7. At this time, the relationship between the ultimate vacuum degree and the elapsed time until reaching the final vacuum degree is shown by a curve b in FIG. In addition, ○ indicates a measurement value using a BA gauge, and □ indicates a measurement value using an extractor gauge.

Comparative Example 1 Table 1 shows the magnetic properties of a magnet test piece having the same composition as in Example 1 but without an Al film or an AlN film on the surface. After cleaning the surface of a magnet body test piece having the same size and quantity as in Example 1 under the same conditions as in Example 1, the ultimate vacuum degree was measured using the ultrahigh vacuum apparatus of FIG. 1 under the same conditions as in Example 1. . The result is shown by curve c in FIG.

Comparative Example 2 A magnet test piece having the same composition, the same dimensions and the same number as in Example 1 was cleaned under the same conditions as in Example 1, and then a Ni film was formed to 20 μm by ordinary electroplating. The magnetic properties of the obtained Ni-plated magnet were measured, and the results are shown in Table 1. Then, after the surface of the Ni-plated magnet was washed, the ultimate vacuum degree was measured using the ultrahigh vacuum apparatus of FIG. 1 under the same conditions as in Example 1. The result is shown by a curve d in FIG.

After forming an Al coating on the magnet surface according to the present invention, Fe-B having an AlN coating layer on the Al coating is provided.
The -R permanent magnet body can achieve a degree of vacuum of 1 × 10 ⁻⁹ Pa or less without generating gas from the magnet body as in the embodiment, but the magnet body as it is or a magnet body provided with a Ni plating film It can be seen that the target ultimate vacuum cannot be achieved due to the generation of gas from the magnet body.

[0036]

[Table 1]

[0037]

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 thin film forming method such as an ion plating method. And an AlN film formed by performing a thin film forming method such as ion reaction plating in N ₂ gas. The film is dense, has excellent adhesion, and prevents generation of gas from the magnet body. An Fe-BR-based permanent magnet for ultra-high vacuum that has a function and has high magnetic properties and can be used for an undulator or the like in an ultra-high vacuum atmosphere is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of an ultra-high vacuum device used for measuring a degree of ultimate vacuum.

FIG. 2 is a graph showing the relationship between ultimate vacuum and time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultra-high vacuum apparatus 2 Main body 3 Sample chamber 4 Ti getter pump 5 Ion pump 6 BA gauge 7 Extractor gauge 8 Magnet sample

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) An ultra-high vacuum 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 a 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 by vapor phase deposition. A method for manufacturing an ultra-high vacuum permanent magnet in which an AlN coating layer having a thickness of 0.5 μm to 10 μm is formed by a vapor phase film forming method in an N ₂ gas atmosphere after being formed by a film method.