DE69918660T2 - Corrosion resistant permanent magnet and its manufacturing process - Google Patents

Description

Technical area

The The present invention relates to an Fe-B-R based permanent magnet with an excellent corrosion resistant film, and on a Process for producing the same. More specifically, it refers the present invention to an Fe-B-R based permanent magnet, the one on its surface a corrosion resistant film exhibiting excellent adhesion at the Magnet has and a stable high magnetic characteristic can show that even then can not be disturbed, if the magnet for one long period under high temperature and high humidity conditions a temperature of 80 ° C and a relative humidity of 90% is allowed to stand, and where the film is free of hexavalent chromium and a process for the production of the same.

State of the art

One Fe-B-R-based permanent magnet for which an Fe-B-Nd-based permanent magnet representative is conveniently used in various applications, because he is from a budget Material rich in natural Resources is produced and a high magnetic characteristic compared to a Sm-Co based permanent magnet.

however The Fe-B-R based permanent magnet is susceptible to this by oxidation in the Atmosphere too corrode because it contains highly reactive R and Fe. If the Fe-B-R-based Permanent magnet is used without any surface treatment to be subjected to, the corrosion of the magnet of its surface due to the presence of a small amount of acid, alkali and / or water continues to generate rust, causing the degradation and resolution the magnetic characteristic brings with it. If continue the magnet with rust generated thereon in a device, such as a magnetic circuit is inserted, it is possible that the rust dissipates to surrounding parts of the components to pollute.

It already gives a suggestion for a magnet comprising a corrosion-resistant metal-clad film on its surface by a wet-plating process, such as an electroless plating process Deposition method and a galvanic process trained is concerned with the corrosion resistance of the Fe-B-R based permanent magnet to improve the position described above (see Japanese Patent publication No. 3-74012). In this process, however, an acidic or alkaline Solution, used in pretreatment prior to the deposition treatment will remain in pores of the magnet, causing the magnet in some make can corrode over time. In addition, the magnet has low Resistance to Chemicals on, and because of this, the surface of the Magnets during the deposition treatment are corroded. Even if continue the metal plated film on the surface of the magnet as described above is formed, if the magnet a corrosion resistance test under conditions of a temperature of 60 ° C and a relative humidity of 90%, the magnetic characteristic of the magnet by 10% or more degraded to the initial value after the lapse of 100 hours be.

It There is also a conventionally proposed process in which a oxidation resistant chemical conversion coating film, such as such as a phosphate film or a chromate film, on the surface of a Fe-B-R-based permanent magnet is formed (see Japanese Patent publication No. 4-22008). The film formed in this process has excellent adhesion on the magnet but if it does a corrosion resistance test under conditions of a temperature of 60 ° C and a relative humidity of 90% is subjected to the magnetic characteristic of the magnet by 10% or more over one Initial value be degraded after the elapse of 300 hours.

One Method which has been conventionally proposed to corrosion resistance of the Fe-B-R based permanent magnet and in which a chromate treatment after the formation of an aluminum film by a sputtering deposition process carried out is, i. a so-called aluminum chromate treatment process (see Japanese Patent Publication No. 6-66173), the purpose is to remarkably improve the corrosion resistance of the magnet to increase. However, the used in this method used Chromate treatment hexavalent chromate, which is undesirable for the environment, and for this reason is a waste liquid treatment method complicated. It is feared, that a film formed by this method is a human body while influenced the handling of the magnet, just because he has a small Contains amount of hexavalent chromium.

From Patent Abstracts of Japan, vol. 1996; No. 01, 31 January 1996 and JP 07-249509 A, a corrosion-resistant permanent magnet as the closest prior art and its production are known. In order to improve the corrosion resistance of an Fe-BR permanent magnet, a TiN film with an interposed Al film is provided on the surface of the magnet. The TiN film is formed by a vapor-phase film-forming process in an N ₂ gas atmosphere.

In US Pat. No. 4,837,114 describes an Fe-B-R-type permanent magnet, which has an anti-corrosive coating film layer on its surface is available. The anti-corrosive film is made of metals, oxides, Nitrides, carbides, borides, silicides, their composite compositions and their mixtures formed. In addition, a resin may be used be thin around the micropores Impregnate coating film, to further improve its corrosion resistance.

Accordingly, it is an object of the present invention, an Fe-B-R based Permanent magnet, which on its surface is a corrosion resistant Film with excellent adhesion has the magnet and the stable high magnetic characteristic can not be affected even if the Magnet for a long period of time under high temperature and high humidity conditions a temperature of 80 ° C and a relative humidity of 90% is allowed to stand and in which the film is free of hexavalent chromium, and a method to his To provide production.

Disclosure of the invention

The local inventors have, as a result of various zealous studies, that were made in view of the above points, found out that if an aluminum film is based on the surface of an Fe-B-R Permanent magnet is formed and a chemical conversion coating film, containing titanium and / or zirconium as constituent elements is formed on the aluminum film, the chemical conversion coating film with the intervening aluminum film firmly adhering to the magnet, giving it excellent corrosion resistance shows.

The present invention has been achieved by the above knowledge and according to claim 1 of the present invention will be an Fe-B-R based permanent magnet provided, which formed on its surface a chemical Having a conversion coating film with an aluminum film interposed therebetween, wherein the chemical conversion coating film is titanium and / or Zirconium and phosphorus, oxygen and fluorine as constituent elements contains.

According to claim 2 of the present invention in addition to claim 1 the aluminum film has a thickness in the range of 0.01 μm to 50 μm.

According to claim 3 of the present invention, in addition to claim 1, the chemical conversion coating film has a thickness in a range of 0.01 μm up to 1 μm on.

According to claim 4 of the present invention, in addition to claim 1, the content of titanium and / or zirconium in the chemical conversion coating film is in a range of 0.1 mg to 100 mg for a film area formed on 1 m ^{2 of} the surface of the magnet ,

According to claim 5 of the present invention, in addition to claim 1, the content of phosphorus in the chemical conversion coating film is in a range of 0.1 mg to 100 mg for a film area formed on 1 m ^{2 of} the surface of the magnet.

According to claim 6 of the present invention, in addition to claim 1, the content of oxygen in the chemical conversion coating film is in a range of 0.2 mg to 300 mg for a film area formed on 1 m ^{2 of} the surface of the magnet.

According to claim 7 of the present invention, in addition to claim 1, the content of fluorine in the chemical conversion coating film is in a range of 0.05 mg to 100 mg for a film area formed on 1 m ^{2 of} the surface of the magnet.

According to claim 8 of the present invention, in addition to claim 1, is relationship the number of moles of phosphorus to the number of moles of titanium and / or zirconium in a plane near the surface of the chemical conversion coating film larger than that in the whole chemical conversion coating film.

According to claim 9 of the present invention, in addition to claim 1, is relationship the number of moles of phosphorus to the number of moles of titanium and / or zirconium in an area near the surface of the chemical conversion coating film is equal to or greater than 1.

According to claim 10 of the present invention will be a method of manufacturing an Fe-B-R-based permanent magnet is provided which the steps of forming an aluminum film on the surface of a Fe-B-R based Permanent magnets, applying a treatment solution, the at least one titanium component and / or a zirconium component, at least one of phosphoric acid, condensed Phosphoric acid, phytic acid, the hydrolyzate of phytic acid and its salts, and containing a fluorine compound, on the surface of the Aluminum film, and drying the applied processing solution comprises whereby a chemical conversion coating film is formed, at least titanium and / or zirconium and phosphorus, oxygen and fluorine as constituent elements.

According to claim 11 of the present invention, in addition to claim 10, is the aluminum film formed by a vapor deposition method.

According to claim 12 of the present invention, in addition to claim 11 the aluminum film has a thickness in a range of 0.01 μm to 50 μm.

According to claim 13 of the present invention, in addition to claim 10 the Fe-B-R based permanent magnet and aluminum pieces in one Placing the treatment vessel, where they vibrate and / or are moved, causing the aluminum film is trained.

According to claim 14 of the present invention, in addition to claim 13 the aluminum film has a thickness in a range of 0.01 μm to 1 μm.

According to claim 15 of the present invention, in addition to claim 10, is The relationship the number of moles (with respect Phosphorus) of at least one of the phosphoric acid, condensed phosphoric acid, phytic acid, the Hydrolyzate of phytic acid and their salts and the number of moles (based on the metal) of the titanium component and / or the zirconium component in the treatment solution is the same or greater than 1.

Best procedure to run the invention

One Fe-B-R based permanent magnet according to the present invention has as a feature that it is a chemical conversion coating film that is on its surface with an interposed Aluminum film is formed, and the titanium and / or zirconium and phosphorus, oxygen and fluorine from constituent elements.

The Method for forming the aluminum film on the surface of the In particular, Fe-B-R-based permanent magnets is not limited. If however considered Will that magnet and aluminum film for oxidative corrosion susceptible are examples of a desirable one Method a method using a vapor deposition method and a method of placing an Fe-B-R based permanent magnet and aluminum pieces in a treatment vessel, where she vibrates and / or moves.

(1) Method Using Vapor Deposition Examples of Vapor Deposition Method are known methods, such as a vacuum evaporation method, an ion sputtering process and an ion plating method and the like. The aluminum film can be under usual Conditions are formed in each of the procedures, but of the Position of density, uniformity in thickness, speed of training of the film to be formed, and the like, it is desirable that a vacuum evaporation method and an ion plating method can be used. Of course you can the surface the magnet are subjected to a known cleaning treatment, such as washing, degreasing treatment and atomization the training of the film.

It is desirable that the temperature of the magnet during the formation of the film in a range of 200 ° C up to 500 ° C is set. If the temperature is lower than 200 ° C, gives it's the possibility that no film with an excellent adhesion to the surface of the Magnets forms. On the other hand, if the temperature exceeds 500 ° C, the possibility, that cracks are generated in the film, causing the film to while a cooling course peel off the magnet after the formation of the film.

It is desirable the thickness of the aluminum film is in a range of 0.01 μm to 50 μm, more preferably in a range of 0.05 μm up to 25 μm, lies. If the thickness is smaller than 0.01 μm, there is the possibility that the film can not show excellent corrosion resistance. If the thickness exceeds 50 μm, is there a possibility, that there is an increase in production costs, but there are also the possibility that the effective volume of the magnet decreases.

(2) Method which involves placing a Fe-B-R based permanent magnet and aluminum pieces in a treatment vessel, where they vibrate and / or move.

The Aluminum pieces used in this process may be any of a variety Have shapes, such as a needle-like shape (a wire-like shape Shape), a columnar shape and a massive shape. However, it is efficient from the standpoint of Preparation of a source for forming an aluminum film fine aluminum powder desirable, that aluminum pieces with a needle-like shape with sharp tip ends or one column shape to be used with sharp tip ends.

It is from the standpoint of efficient production of fine aluminum powder desirable, that the size (longer diameter) the aluminum pieces in a range of 0.05 mm to 10 mm, more preferably in one Range of 0.3 mm to 5 mm, further preferably in one Range of 0.5 mm to 3 mm. Aluminum pieces with the same shape and the same size can be used but aluminum pieces with different shapes and different sizes can be found in Form of a mixture can be used.

It is desirable that the vibration and / or movement of the magnet and the aluminum pieces in one dry way is, considering the fact that they are for an oxidative corrosion prone are. The vibration and / or movement of the magnet and the aluminum pieces can be carried out in ambient air and at ambient temperature. It is unnecessary, a complicated apparatus as used in the present invention Use treatment vessel, and, for example, the treatment vessel may include a treatment chamber to be a drum machine. The drum apparatus can by well-known Type, such as a rotation type, a vibration type and a centrifugal type. In the case of the rotation type, the rotation speed is desirably in a range of 20 to 50 rpm. In the case of the vibration type it is desirable that the vibration frequency is in a range of 50 Hz to 100 Hz is and the vibration amplitude in a range of 0.3 mm 10 mm. In the case of the centrifugal type, the rotational speed is desirably in a range between 70 and 200 rpm.

It is desirable that the total amount of magnets placed in the treatment vessel and aluminum pieces in the range from 20 to 90 vol.% Of the internal volume of the treatment vessel is. If the total amount is less than 20 vol.%, The throughput is too small, which is not preferred in practical operation. If the total amount exceeds 90 Vol.%, it is possible, that the film can not be formed efficiently. It is desirable that the ratio the amount of magnet to the amount of placed in the treatment vessel aluminum pieces equal to or less than 3 in terms of a volume ratio (of Magnet / aluminum pieces) is. If the volume ratio 3 exceeds it is possible, that a long time for the education of the film needed which is not preferred in practical use. The treatment time depends on Throughput, but is usually in the range of 1 to 10 hours.

According to the above described method is produced from the aluminum pieces fine aluminum powder adhered to the surface of the magnet, to form the aluminum film. It is believed that the phenomenon of adhesion of fine aluminum powder on the surface of the magnet a kind of Mechanochemical reaction is. The fine aluminum powder adheres firmly on the surface the magnet and the trained aluminum film shows an excellent Corrosion resistance. From the point of view of ensuring a sufficient Corrosion resistance, it is desirable that the thickness of the film is equal to or larger than 0.01 μm, such as described above. The upper limit for the thickness is not special limited, but if the thickness exceeds 1 μm, It takes a long time to form the aluminum film. For this reason, this method is suitable for an aluminum film form having a thickness equal to or less than 1 micron.

After forming the aluminum film on the surface of the magnet, the aluminum film may be subjected to a heat treatment to enhance the adhesion of the aluminum film to the surface of the magnet. The temperature in the heat treatment is preferably in a range of 200 ° C to 500 ° C, and more desirably in a range of 200 ° C to 250 ° C, from the viewpoint of productivity and manufacturing cost. If the temperature is lower than 200 ° C, there is a possibility that an interface reaction of the aluminum film with the magnet does not proceed sufficiently and, as a result, the adhesion is not improved. If the temperature exceeds 500 ° C, there is a possibility that deterioration of the magnetic characteristic of the magnet occurs and that the aluminum film melts.

One Method of forming a chemical conversion coating film, titanium and / or zirconium, as well as phosphorus, oxygen and fluorine as constituent elements on the aluminum film is described below. An example of this method is a method which comprises applying a treatment solution to the surface of the Aluminum film containing at least some kind of titanium compound and a zirconium compound, at least one of phosphoric acid, condensed Phosphoric acid, phytic acid, the Hydrolyzate of phytic acid and their salts, and containing a fluorine compound, and exposing the applied solution a drying treatment.

The treatment solution is by dissolving the titanium compound and / or the zirconium compound, and at least one of phosphoric acid, condensed phosphoric acid, phytic acid, the hydrolyzate of phytic acid and their salts, and the fluorine compound prepared in water.

Examples in the treatment solution contained titanium compound which can be used are fluorotitanic acid, alkali metal, Alkaline earth metal and ammonium fluorotitanates, titanium sulfate and nitrate and the same. Examples of the zirconium compound used fluorozirconic acid, alkali metal, alkaline earth metal and ammonium fluorozirconiumates, zirconium sulfate and nitrate, and the like. It is desirable the content of the titanium compound and / or the zirconium compound in the treatment solution in a range of 1 ppm to 2,000 ppm, more preferably in a range of 10 ppm to 1,000 ppm with respect to the metal, is included. If the content is less than 1 ppm, the Possibility, the chemical conversion coating film is not formed becomes. If the content is greater than 2,000 ppm, it is possible that an increase in costs occurs.

Examples from in the treatment solution contained condensed phosphoric acid, which can be used pyrophosphoric, tripolyphosphoric, metaphosphoric, Ultraphosphoric acid and like. Examples of the hydrolyzate of phytic acid, the can be used are myoinositol diphosphate, triphosphate, tetraphosphate and pentaphosphate and the same. Examples of the salts of phosphoric acid, condensed Phosphoric acid, phytic acid and hydrolyzate of phytic acid, which can be used are ammonium, alkali metal and alkaline earth metal salts of phosphoric acid, condensed Phosphoric acid, phytic acid and the hydrolyzate of phytic acid. If any of phosphoric acid, condensed phosphoric acid and their salts, it is desirable that their content in the treatment solution in a range of 1 ppm to 2,000 ppm, more preferably in a range of 5 ppm to 1000 ppm in terms of phosphoric acid. The reason is as follows; if the content is less than 1 ppm, it is possible, that a chemical conversion film is not formed. If the salary exceeds 2,000 ppm, is the adhesion of a chemical conversion coating film on the magnet. If one of phytic acid, the hydrolyzate of phytic acid and their salts are used, it is from a similar one Reason desirable, that their content in the treatment solution is in a range of 50 ppm to 10,000 ppm, more preferably in a range of 100 ppm to 5,000 ppm in terms of phytic acid.

Examples in the treatment solution contained fluorine compound that can be used are Hydrofluoric acid, Ammonium fluoride, ammonium hydrogen fluoride, sodium fluoride and Sodium hydrogen fluoride and the like, in addition to those described above Fluoro titanic acid and its salt, and fluorozirconic acid and its salt. It is desirable, that the content of the fluorine compound in the treatment solution in a range of 10 ppm to 10,000 ppm, more preferably in one Range from 50 ppm to 5,000 ppm. If the content is smaller than 10 ppm, it is possible that the surface of the aluminum film is not effectively etched. If the salary greater than 10,000 ppm, it is possible that the etching speed higher than the film-making speed is what makes it difficult a movie uniform train.

It is desirable that the pH of the treatment solution is in a range of 1 is regulated to 6. If the pH is less than 1, it is the possibility, that the surface of the aluminum film was excessively etched becomes. If the pH exceeds 6, it is possible, that stability the treatment solution being affected.

In addition to the ingredients described above, an organic acid such as tannin acid, an oxidizing agent (hydrogen peroxide, chloric acid and its salts, nitrous acid and its salt, nitric acid and its salt, tungstic acid and its salt, and molybdic acid and its salt) and a water-soluble polymer such as a water-soluble polyamide, the treating solution for the purpose of Reinforcing the chemical conversion reaction, the stability of the processing solution, the adhesion of a chemical conversion coating film to the magnet and the adhesion to an adhesive used for incorporating the magnet into parts.

If it's the treatment solution even in storage stability lacks, the treatment solution can be made as needed. Examples of the treatment solution that can be used in the present invention are one of PALCOAT 3753 (which is a trade name and used by Nihon Parkerizing Co., Ltd.). manufactured) and one of PALCOAT 3756MA and PALCOAT 3756MB (which are both trade names and from the Nihon Parkerizing Co., Ltd. manufactured) treatment solution.

Examples the method for applying the treatment solution to the surface of the Aluminum film that can be used is a dip coating method, a spraying process and a spin-on method. It is desirable that the temperature the treatment solution, when applied, set in a range of 20 ° C to 80 ° C becomes. If the temperature is lower than 20 ° C, it is possible to that the reaction does not progress. If the temperature exceeds 80 ° C, it is possible, that stability the treatment solution impaired is. The treatment time is usually in a range of 10 s to 10 min.

To Application of the treatment solution on the surface of the aluminum film becomes the applied treatment solution of Subjected to drying treatment. The temperature during the drying treatment is desirable in a range of 50 ° C up to 250 ° C and more desirable in a range of 50 ° C up to 150 ° C, from the viewpoints of productivity and manufacturing cost. The reason is as follows: if the temperature is lower than 50 ° C, can the treatment solution is not dried sufficiently and as a result it is possible to that a deterioration of the appearance occurs and that the adhesion to an adhesive used to incorporate the magnet into parts is. If the temperature exceeds 250 ° C, it is possible, that the decomposition of the chemical conversion coating film occurs. The treatment time is usually in one range from 5 seconds to 1 hour.

Of the formed by the method described above and titanium and / or Zirconium, phosphorus, oxygen and fluorine as constituent elements containing chemical conversion coating film adheres with interposed aluminum film stuck on the surface of the magnet. Therefore, if the thickness of the chemical conversion coating film becomes equal to or greater than 0.01 μm is provided a sufficient corrosion resistance. One takes to that during the chemical conversion treatment phosphoric acid or condensed phosphoric acid in the treatment solution with Nd or Fe, which is a magnetic material on the surface of the Magnets reacts, forming a passive film, and therefore even if the aluminum film has a region that is unsatisfactory, the passive film corrosion resistance compensated for such a range. Although the upper limit of Thickness of the chemical conversion coating film is not limited For example, the thickness of the chemical conversion coating film is more desirable equal to or less than 1 μm and more desirably equal to or less than 0.3 μm in terms of reducing the size the magnet itself and the manufacturing costs based requirements.

The content of titanium and / or zirconium in the chemical conversion coating film is desirably in a range of 0.1 mg to 100 mg, and more desirably in a range of 1 mg to 50 mg for a film area formed on 1 m ^{2 of} the surface of the magnet , If the content is less than 0.1 mg, there is a possibility that sufficient corrosion resistance will not be provided. If the salary is greater than 100 mg, there is a possibility that an increase in costs will occur

Of the Content of phosphorus in the chemical conversion coating film desirably in Range from 0.1 mg to 100 mg, and more desirably in the range from 1 mg to 50 mg for a film area formed on 1 m2 of the surface of the magnet is. If the content is less than 0.1 mg, it is possible to that no adequate corrosion resistance is provided. If the salary is greater than 100 mg, it is possible to that the adhesion of an adhesive used to install the magnet in parts is.

Oxygen in the chemical conversion coating film is present in the chemical conversion coating film in titanium, zirconium or phosphorus bound form and is present as a constituent element of the processing solution for the purpose of enhancing adhesion to an adhesive used to incorporate the magnet into the parts. It is desirable that the content of oxygen in the chemical conversion coating film be in the range of 0.2 mg to 300 mg for a film area formed on 1 m ^{2 of} the surface of the magnet. If the content is less than 0.2 mg, there is a possibility that sufficient corrosion resistance will not be provided. If the content is larger than 300 mg, there is a possibility that the adhesion is influenced by an adhesive used for incorporating the magnet into the parts.

Fluorine in the chemical conversion coating film is incorporated in the chemical conversion coating film in forming the chemical conversion coating film due to free fluorine ion or fluorine compound bonded with the Zr compound such as ZrF ₄ HPO _{4 present} in the treating solution for the purpose of etching the surface of the aluminum film , The content of fluorine in the chemical conversion coating film is desirably in a range of 0.05 mg to 100 mg and more desirably in a range of 0.1 mg to 50 mg for a film area formed on 1 m ^{2 of} the surface of the magnet. If the content is less than 0.05 mg, there is a possibility that sufficient corrosion resistance will not be provided. If the content is larger than 100 mg, there is a possibility that the adhesion is influenced by an adhesive used for incorporating the magnet into the parts.

Prefers among the chemical conversion coating films produced by the method described above and titanium and / or Zirconium, phosphorus, oxygen and fluorine as constituent elements included, is a movie in which the ratio of the number of moles of phosphorus to the number of moles of titanium and / or zirconium in a region near the surface of the film (i.e., in a region between the surface of the film) Films and one point 0.002 microns from the surface the film spaced) is greater as in the total film and a film in which the ratio of moles of phosphorus to the number of moles of titanium and / or zirconium in a region near the surface of the movie is equal to or greater than 1, desirably equal to or greater than 2 and more desirably equal to or greater than 3 is. It is believed that even if the film is in contact with Water is brought, a big one Number of molecules of phosphoric acid or condensed phosphoric acid, in the area near the surface of the film, catch the water, thereby preventing is that the corrosion causing water the surface of the Magnet reached. In order to train such a film, it is desirable a treatment solution to use at the ratio the number of moles (with respect Phosphorus) of at least one of phosphoric acid, condensed phosphoric acid, phytic acid, Hydrolyzates of phytic acid and their salts to the number of moles (in terms of metal) of the titanium compound and / or the zirconium compound in the treatment solution are the same or greater than 1 is.

In front the formation of a chemical conversion coating film The aluminum film may be shot-peened (a method of modifying a surface by shooting of hard grains against the surface) as a preliminary step become. The shot peening allows it the aluminum film, smoothed thereby forming a chemical conversion coating film allows that gets thin is, but has excellent corrosion resistance.

One for the Shot peening powder desirably has a hardness equivalent or higher as that of the formed aluminum film and examples of the powder are spherical hard materials with a Mohs hardness of 3 or greater, such as such as those steel balls or spherical beads. The average particle size of the powder is desirable in a range of 30 microns up to 3,000 μm and more desirably in a range of 40 microns up to 2,000 μm. If the average particle size is smaller than 30 μm, the applied to the aluminum film Compressive force small, which leads to that the treatment requires a long time. On the other hand, if the average particle size exceeds 3,000 μm, it is possible, that the roughness of the treated surface is too large and the finished surface uneven is.

The injection pressure in shot peening is desirably in a range of 0.1 MPa (1.0 kg / cm ² ) to 0.5 MPa (5.0 kg / cm ² ). If the injection pressure is lower than 0.1 MPa (1.0 kg / cm ² ), the pressing force on the metallic film is small, resulting in a long time required for the treatment. If the injection pressure exceeds 0.5 MPa (5.0 kg / cm ² ), there is a possibility that the pressing force on the metallic film is uneven, resulting in the deterioration of the surface roughness.

The Injection time in shot peening is desirably in one Range from 1 min to 1 h. If the injection time is shorter than 1 min, there is the possibility that not the entire surface uniform can be treated. If the injection time exceeds 1 h, it is possible, that an impairment the roughness of the surface occurs.

One in an Fe-B-R based permanent magnet used in the present invention The rare earth element (R) contained therein is desirably at least one of Nd, Pr, Dy, Ho, Tb and Sm, in addition to at least one from La, Ce, Gd, Er, Eu, Tm, Yb, Lu and Y.

Usually One of them (R) is enough, but in practice it can be a mixture of two or more rare earth elements (mischmetal and didymium and the like) for the sake of an available convenience become.

Of the Content of R in the Fe-B-R based permanent magnet is desirably in a range of 10 at% to 30 at%. If the R content is lower than 10 at%, the crystal structure is the same cubic Crystal structure such as α-Fe, and for this reason, a high magnetic characteristic, in particular a high coercive force (iHc) was not obtained. If otherwise the R content exceeds 30 atomic%, the content of an R-rich non-magnetic phase and the magnetic increases Residual flux density (Br) is reduced so that no permanent magnet produced with excellent characteristics.

Of the Fe content is desirable in a range of 65 at.% to 80 at.%. If the Fe content lower than 65 at%, the residual magnetic flux density becomes (Br) diminished. If the Fe content exceeds 80 at.%, No high coercive Force (iHc) received.

It is possible, the temperature characteristic without degradation of the magnetic Characteristics of the manufactured magnet to improve by a Part of the iron is substituted by Co. If, however, the amount on substituted Co exceeds 20% of Fe, the magnetic characteristic deteriorates, and therefore becomes such an amount is not preferred. The amount of substituted Co in a range of 5 at.% to 15 at.% is provided a high magnetic flux density preferred because the magnetic Residual flux density (Br) compared to a case where part of the Iron is not substituted, is increased.

Of the B content is desirable in a range of 2 at.% to 28 at.%. If the B content lower than 2 atomic%, a rhombohedral structure is one Main phase and a high coercive force (iHc) is not obtained. If the B content exceeds 28 atomic%, the content of a B-rich non-magnetic increases Phase and the residual magnetic flux density (Br) is reduced, so no permanent magnet is produced with excellent characteristics becomes.

Around to improve the production of the magnet and to reduce costs can at least 2% by weight or less of P and 2.0% by weight or less be contained in S in a total amount of 2 wt .-% or less. Furthermore, the corrosion resistance of the magnet can be replaced by substitution Part of B containing 30% by weight or less of carbon (C) be improved.

Further, the addition of at least one of Al, Ti, V, Cr, Mn, Bi, Nb, Ta, Mo, W, Sb, Ge, Sn, Zr, Ni, Si, Zn, Hf, and Ga increases the coercive force and the squareness of a demagnetization curve and to improve the production and reduction of the cost effectively. It is desirable that at least one of them be added in an amount within a range satisfying a condition that at least 0.9 T (9 kg) of Br is required to ensure that the maximum energy product (BH) max equals or greater than 160 kJ / m ³ (20 MGOe).

In addition to R, Fe and B can be the Fe-B-R based permanent magnet impurities contain which for the industrial production of the magnet are inevitable.

The Fe-BR based permanent magnet used in the present invention has a feature that it includes a main phase which is a compound having a tetragonal crystal structure with an average crystal grain size in a range of 1 to 80 μm and 1%. to 50% by volume of a non-magnetic phase (excluding an oxide phase). This magnet shows an iHc ≧ 80 kA / m (1 kOe), a Br> 0.4 T (4 kg) and a (BH) max ≧ 80 kJ / m ³ (10 MGOe), where the maximum value of (BH) max 200 kJ / cm ³ (25 MGOe) or more.

On the chemical conversion coating film of the present invention Another film can be trained. By using a such configuration it is possible the characteristic of the chemical conversion coating film to improve and chemical conversion coating film further functionality to rent.

EXAMPLES

When Example was as described in U.S. Patent No. 4,770,723 previously known ingot pulverized and then one after the other Pressing, sintering, heat treatment and a surface treatment subjected to a sintered magnet having a size of 23 mm × 10 mm × 6 mm and a composition of 17Nd-1Pr-75Fe-7B (what follows will be referred to as "magnet test piece") was generated. The magnet test piece was subjected to the following experiment, the thickness of a Aluminum film using a fluorescence X-ray thickness gauge (SFT-7000, manufactured by Seiko Instruments and Electronics, Ltd.) has been. The thickness of a chemical conversion coating film was using an analysis towards the depth of the film using from X-ray photoelectron spectroscopy (XPS) (using the product manufactured by Shimadzu, Co.) ESCA-850). The content of each of the ingredients in the film was determined by measured a fluorescence X-ray intensity (using a product manufactured by Rigaku Corporation, Co. RIX-3000).

It It should be noted that the present invention not only on a Fe-B-R based sintered magnet, but also on a Fe-B-R based bonded magnet is applicable.

example 1

A magnetic test piece was subjected to sputtering for 35 minutes in an evacuated vacuum vessel evacuated to 1 × 10 ^-4 Pa under conditions of an argon gas pressure of 10 Pa and a bias voltage of -400 V, and the surface of the magnet was cleaned.

Then became the magnet test piece for 15 min subjected to an arc ion deposition process, wherein metallic aluminum as a target under conditions of argon gas pressure of 0.2 Pa, a bias of -50 V and a magnet temperature of 250 ° C was used, whereby an aluminum film on the surface of the Magnet was formed, and was allowed to cool. The trained Aluminum film had a thickness of 0.5 μm.

35 g of PALCOAT 3753 (which is a trade name and manufactured by Nihon Parkerizing Co., Ltd.) was dissolved in 1 liter of water to prepare a treatment solution (having a pH of 3.8). The magnet having the aluminum film on its surface was immersed in this treating solution at a bath temperature of 40 ° C for 1 minute, and then subjected to a drying treatment at 100 ° C for 20 minutes, whereby a titanium-containing chemical conversion coating film having a thickness of 0.1 μm was formed on the aluminum film. The content of titanium in the chemical conversion coating film was 10 mg (per 1 m ^{2 of} the surface of the magnet); the content of phosphorus was 7 mg (per 1 m ^{2 of} the surface of the magnet); the content of oxygen was 21 mg (per 1 m ^{2 of} the surface of the magnet) and the content of fluorine was 2 mg (per 1 m ^{2 of} the surface of the magnet).

Of the produced in the manner described above and containing the titanium having chemical conversion coating film on its surface Magnet with the interposed Aluminum film was subjected to a corrosion resistance acceleration test at he for 300 h under high temperature and high humidity conditions at a Temperature of 80 ° C and a relative humidity of 90% was allowed to stand. The magnetic Characteristics before and after the test and the situation of the appearance change after the test are shown in Table 1. As a result, it was found that even if the magnet for long time under high temperature and high humidity conditions was left, the magnet a satisfactory corrosion resistance satisfactory fulfilled, where both the magnetic characteristic and the appearance little degraded.

Example 2

The magnet test piece was cleaned under the same conditions as in Example 1. Then, an aluminum (Al) wire as a coating material was heated, evaporated and ionized for an ion deposition process of 1 minute under conditions of an argon gas pressure of 1 Pa and a voltage of 1.5 kV, thereby forming an aluminum film on the surface of the magnet. and let the film cool. The formed aluminum film had a thickness of 0.9 μm.

Thereafter, a powder comprising spherical glass beads having an average particle size of 120 μm and a Mohs hardness of 6 together with a pressurized gas comprising N ₂ gas under an injection pressure of 0.15 MPa (Fig. 5 kg / cm ² ) for 5 minutes against the surface of the aluminum film to effect shot peening of the surface of the aluminum film.

10 g of PALCOAT 3756MA and 10 g of PALCOAT 3756MB (which are both trade names and which are manufactured by Nihon Parkerizing Co., Ltd.) were dissolved in 1 liter of water to prepare a treatment solution (in which the ratio of the number of moles of phosphorus to Mole number of zirconium was 6.2 and which had a pH of 3.2). The magnet having an aluminum film on its surface was immersed in this treating solution at a bath temperature of 50 ° C for 1 minute and 30 seconds, and then subjected to a drying treatment at 120 ° C for 20 minutes, using a zirconium-containing chemical conversion coating film having a thickness of 0.07 .mu.m was formed on the aluminum film. The content of zirconium in the chemical conversion coating film was 16 mg (per 1 m ^{2 of} the surface of the magnet); the content of phosphorus was 11 mg (per 1 m ^{2 of} the surface of the magnet); the content of oxygen was 50 mg (per 1 m ^{2 of} the surface of the magnet) and the content of fluorine was 3 mg (per 1 m ^{2 of} the surface of the magnet).

Of the prepared in the manner described above and contained the zirconium having chemical conversion coating film on its surface Magnets with the interposed Aluminum film became the same among the corrosion resistance acceleration test Conditions as in Example 1 subjected. The results of the test are shown in Table 1. As a result, it was found that the Magnet made a needed Corrosion resistance sufficiently fulfilled.

Example 3

150 Magnet test pieces (with a dummy volume of 0.5 l and a weight of 1.6 kg) and short columnar aluminum pieces (with a dummy volume of 20 l and a weight of 100 kg), the all had a diameter of 0.8 mm and a length of 1 mm were in a treatment chamber in a vibration type drum machine with a volume of 50 l thrown (so the total amount 40 vol.% the internal volume of the treatment chamber was), where they are in a dry Way for 5 h under conditions of a vibration frequency of 60 Hz and a Vibratory amplitude of 1.8 mm were treated, creating an aluminum film on the surface each of the magnets was formed. The trained aluminum film had a thickness of 0.05 μm.

The magnets, all having the aluminum film on their surface, were immersed in the treating solution described in Example 2 at a bath temperature of 50 ° C for 1 minute and 30 seconds, and then subjected to a drying treatment at 120 ° C for 20 minutes to obtain a zirconium formed chemical conversion coating film was formed with a thickness of 0.08 microns on the aluminum film. The content of zirconium in the chemical conversion coating film was 16 mg (per 1 m ^{2 of} the surface of the magnet); the content of phosphorus was 12 mg (per 1 m ^{2 of} the surface of the magnet); the content of oxygen was 38 mg (per 1 m ^{2 of} the surface of the magnet) and the content of fluorine was 3 mg (per 1 m ^{2 of} the surface of the magnet).

The produced in the manner described above and all the zirconium containing chemical conversion coating film on its surface Magnets with the interposed Aluminum film became the same among the corrosion resistance acceleration test Conditions as in Example 1 subjected. Results of the test are shown in Table 1. As a result, it was found that the Magnets produced the necessary corrosion resistance sufficient fulfilled.

Example 4

The Magnet test piece was purified under the same conditions as in Example 1 and then subjected to an arc ion deposition process for 2.5 hours, whereby an aluminum film on the surface of the Magnet was formed and allowed to cool. The educated one Aluminum film had a thickness of 5 μm.

The magnet with the aluminum film on its surface was immersed in the treating solution described in Example 1 at a bath temperature of 40 ° C for 1 minute, and then a drying treatment at 100 ° C for 20 minutes, whereby a titanium-containing chemical conversion coating film having a thickness of 0.09 μm was formed on the aluminum film. The content of titanium in the chemical conversion coating film was 9 mg (per 1 m ^{2 of} the surface of the magnet); the content of phosphorus was 6 mg (per 1 m ^{2 of} the surface of the magnet); the content of oxygen was 20 mg (per 1 m ^{2 of} the surface of the magnet) and the content of fluorine was 2 mg (per 1 m ^{2 of} the surface of the magnet).

Of the produced in the manner described above and that containing titanium, having chemical conversion coating film on its surface Magnet with the interposed Aluminum film was subjected to a corrosion resistance acceleration test at he for 1000 h under high temperature and high humidity conditions at a Temperature of 80 ° C and a relative humidity of 90% was allowed to stand. The magnetic Characteristics before and after the test and the situation of change The appearance after the test are shown in Table 2. In the result It has been found that even if the magnet is under high temperature for a long time and high humidity conditions were left standing, the magnet one required corrosion resistance sufficiently fulfilled, wherein both the magnetic characteristic and the appearance little degraded.

Example 5

One Aluminum film was on the surface of the magnet by a Arc deposition process for 10 minutes under the same conditions formed as in Example 2 and then allowed to cool. The educated one Aluminum film had a thickness of 10 μm.

Thereafter, a powder comprising spherical glass beads having an average particle size of 120 μm and a Mohs hardness of 6, together with a pressurized gas comprising N ₂ gas, was pressed against the surface of the aluminum film at an injection pressure of 0, 15 MPa (1.5 kg / cm ² ) for 5 minutes to carry out shot peening of the surface of the aluminum film.

The magnet having the aluminum film on its surface was immersed in the treating solution described in Example 2 at a bath temperature of 50 ° C for 1 minute and 30 seconds, and then subjected to a drying treatment at 120 ° C for 20 minutes to obtain a zirconium-containing chemical conversion coating film a thickness of 0.07 microns was formed on the aluminum film. The content of zirconium in the chemical conversion coating film was 15 mg (per 1 m ^{2 of} the surface of the magnet); the content of phosphorus was 12 mg (per 1 m ^{2 of} the surface of the magnet); the content of oxygen was 47 mg (per 1 m ^{2 of} the surface of the magnet), the content of fluorine was 2 mg (per 1 m ^{2 of} the surface of the magnet).

Of the produced in the manner described above and containing the zirconium having chemical conversion coating film on its surface Magnet with the interposed Aluminum film became the same among the corrosion resistance acceleration test Conditions as in Example 4 subjected. Results of the test are shown in Table 2. As a result, it was found that the Magnet produced sufficient corrosion resistance required fulfilled.

The relationship the number of moles of phosphorus to the number of moles of zirconium in a range between the surface zirconium-containing chemical conversion coating film and a point of 0.002 μm from the surface was spaced apart by X-ray photoelectron spectroscopy (XPS) (using a method manufactured by Shimadzu, Co. ESCA-850), and the results showed 7. On the other hand, the ratio of Molar number of phosphorus to the number of moles of zirconium throughout the chemical Conversion coating film based on the number of moles of zirconium and phosphorus, calculated by fluorescence X-ray intensity and as a result this ratio was 2.

Example 6

The magnet test piece was cleaned under the same conditions as in Example 1. Then, a billet of metallic aluminum used as a coating material was heated and evaporated, and the magnetic test piece was subjected to a vacuum evaporation process for 50 minutes under the condition of an argon gas pressure of 1 × 10 ^-2 Pa, thereby forming an aluminum film on the surface of the magnet and the film was allowed to cool. The formed aluminum film had a thickness of 8 μm.

The magnet having the aluminum film on its surface was immersed in the treating solution described in Example 2 at a bath temperature of 50 ° C for 1 minute and 30 seconds, and then subjected to a drying treatment at 120 ° C for 20 minutes to obtain a zirconium-containing chemical conversion coating film a thickness of 0.06 microns was formed on the aluminum film. The content of zirconium in the chemical conversion coating film was 15 mg (per 1 m ^{2 of} the surface of the magnet); the content of phosphorus was 13 mg (per 1 m ^{2 of} the surface of the magnet); the content of oxygen was 35 mg (per 1 m ^{2 of} the surface of the magnet), and the content of fluorine was 2 mg (per 1 m ^{2 of} the surface of the magnet).

Of the prepared in the manner described above and the zirconium-containing having chemical conversion coating film on its surface Magnet with the interposed Aluminum film became the same among the corrosion resistance acceleration test Conditions as in Example 4 subjected. Results of the test are shown in Table 2. As a result, it was found that the made magnet of a necessary corrosion resistance sufficient enough.

Table 1

Table 2

Comparative Example 1

The Magnet test piece was degreased, pickled and then at a bath temperature of 70 ° C in one treatment solution which contained 4.6 g / L zinc and 17.8 g / L phosphate, thereby a phosphate film having a thickness of 1 μm on the surface of the Magnet was formed. The generated magnet became the corrosion resistance acceleration test subjected under the same conditions as in Example 1. Results of the test are shown in Table 1. As a result, deterioration occurred the magnetic characteristic was on and on the generated magnet Rust generated.

Comparative Example 2

The Magnet test piece became the corrosion resistance acceleration test subjected under the same conditions as in Example 1. Results of the test are shown in Table 1. As a result, deterioration occurred of the magnetic characteristic and became rust in the magnet test piece educated.

Comparative Example 3

Of the Magnet with the aluminum film on its surface, the shot peening in Example 5 was subjected to the corrosion resistance acceleration test subjected under the same conditions as in Example 4. Results of the test are shown in Table 2. As a result, an impairment occurred the magnetic characteristic was on and in the generated magnet Rust formed.

Comparative Example 4

The magnet having the aluminum film on its surface subjected to shot peening in Example 5 was cleaned and then immersed in a treating solution containing 300 g / l of sodium hydroxide, 40 g / l of zinc oxide at a bath temperature of 23 ° C. 1 g / l of ferric chloride and 30 g / l of Rochelle salt, whereby the surface of the aluminum film was substituted by zinc (Zn). Further, the resultant magnet was subjected to an electroplating treatment under the condition of a current density of 1.8 A / dm ² using a plating solution comprising 240 g / l of nickel sulfate, 48 g / l of nickel chloride, an appropriate amount of nickel carbonate (with a adjusted pH) and 30 g / L boric acid at a bath temperature of 55 ° C and a pH of 4.2, whereby a nickel film was formed with a thickness of 0.9 microns on the aluminum film, wherein its surface is substituted with zinc. The resulting Magnet was subjected to the corrosion resistance acceleration test under the same conditions as in Example 4. Results of the test are shown in Table 2. As a result, deterioration of the magnetic characteristic of the magnet occurred, and a part of the nickel film was peeled off.

industrial applicability

At the Fe-B-R-based permanent magnets having the chemical conversion coating film, the one inserted in between Aluminum film on its surface is formed and the zirconium and / or titanium, phosphorus, oxygen and fluorine as constituent elements is the chemical conversion coating film firmly attached to the magnet with the interposed aluminum film and therefore the magnet has excellent corrosion resistance. Even if the magnet for a long time under high temperature and high humidity conditions a temperature of 80 ° C and a relative humidity of 90% is allowed to stand the magnet has a stable high magnetic characteristic that does not impaired can be. About that In addition, the film is free of hexavalent chromium.

Claims (15)

Fe-B-R-based permanent magnet, one on its surface trained chemical conversion coating film with a inserted in between Aluminum film, wherein the chemical conversion coating film Titanium and / or zirconium, as well as phosphorus, oxygen and fluorine Contains constituent elements. Fe-B-R-based permanent magnet according to claim 1, wherein the aluminum film has a thickness in the range of 0.01 microns to 50 microns. Fe-B-R-based permanent magnet according to claim 1, wherein the chemical conversion coating film has a thickness in the Range of 0.01 microns up to 1 μm having. An Fe-BR based permanent magnet according to claim 1, wherein the content of titanium and / or zirconium in the chemical conversion coating film is in a range of 0.1 mg to 100 mg for a film area formed on 1 m ^{2 of} the surface of the magnet. An Fe-BR-based permanent magnet according to claim 1, wherein the content of phosphorus in the chemical conversion coating film is in the range of 0.1 mg to 100 mg for a film area formed on 1 m ^{2 of} the surface of the magnet. An Fe-BR-based permanent magnet according to claim 1, wherein the content of oxygen in the chemical conversion coating film is in the range of 0.2 mg to 100 mg for a film area formed on 1 m ^{2 of} the surface of the magnet. An Fe-BR-based permanent magnet according to claim 1, wherein the content of fluorine in the chemical conversion coating film is in the range of 0.05 mg to 100 mg for a film area formed on 1 m ^{2 of} the surface of the magnet. Fe-B-R-based permanent magnet according to claim 1, where the ratio the number of moles of phosphorus to the number of moles of titanium and / or zirconium in an area near the surface of the chemical conversion coating film is larger than in the entire chemical Conversion coating film. Fe-B-R-based permanent magnet according to claim 1, where the ratio the number of moles of phosphorus to the number of moles of titanium and / or zirconium in an area near the surface of the chemical conversion coating film is equal to or greater than 1 is. Process for preparing a Fe-B-R based Permanent magnets, comprising the steps of forming an aluminum film on the surface a Fe-B-R based Permanent magnets, applying a treatment solution containing a titanium compound and / or a zirconium compound, and at least one of phosphoric acid condensed Phosphoric acid, phytic acid, the hydrolyzate of phytic acid, and its salts, and containing a fluorine compound, on the surface of the Aluminum film, and drying the applied treatment solution, whereby a chemical conversion coating film is formed, the titanium and / or Zirconium, as well as phosphorus, oxygen and fluorine as constituent elements contains. Method of making a Fe-B-R based Permanent magnets according to claim 10, wherein the aluminum film by a vapor deposition method is trained. Method of making a Fe-B-R based Permanent magnets according to claim 11, wherein the aluminum film has a thickness in the range of 0.01 microns to 50 microns. Method of making a Fe-B-R based Permanent magnets according to claim 10, the Fe-B-R based Permanent magnet and aluminum pieces placed in a treatment vessel be vibrated and / or moved, causing the Aluminum film is formed. Method of making a Fe-B-R based Permanent magnets according to claim 13, wherein the aluminum film has a thickness in a range of 0.1 μm to 1 μm. Method of making a Fe-B-R based Permanent magnets according to claim 10, the ratio the number of moles (with respect Phosphorus) of phosphoric acid, condensed phosphoric acid, phytic acid, the hydrolyzate of phytic acid and / or their salts to the number of moles (with respect to metal) of the titanium compound and / or the zirconium compound in the treatment solution are the same or greater than 1 is.