JP2000199074A - Deposition type surface treating liquid of rare earth- iron sintered permanent magnet, its surface treatment, and rare earth-iron sintered permanent magnet having surface treated by that surface treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnet having high corrosion resistance by incorporating specified amts. of one or more kinds of metals of zirconium, chromium, vanadium, tungsten, titanium, manganese, molybdenum and silicon and specifying the pH. SOLUTION: This liquid contains one or more kinds of metal ions of zirconium, chromium (III), vanadium, tungsten, titanium, manganese, molybdenum and silicon in total 0.01 to 50 g/L and its pH is preferably controlled to 0.5 to 4.0. Further, it may contain 0.01 to 50 g/L phosphate ion and/or hypophosphite ion, and 0.01 to 50 g/L chromium (IV). A rare earth iron-based sintered permanent magnet is immersed in the obtd. deposition type surface treating liquid to deposit a compd. containing the aforementioned metal elements on the surface of the magnet to form a deposition layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deposition type surface treatment solution and a surface treatment for rare earth / iron based sintered permanent magnets used in a wide range of fields such as various household electrical appliances, computers and various communication devices. The present invention relates to a treatment method and a rare earth / iron-based sintered permanent magnet having a surface obtained by the surface treatment method.

[0002]

2. Description of the Related Art In recent years, the performance required for permanent magnets has been increasing day by day as electric and electronic devices have become smaller and more efficient. As a typical permanent magnet,
Alnico magnets, hard ferrite magnets, rare earth cobalt magnets and the like can be mentioned. However, since alnico magnets and rare earth cobalt magnets are expensive because they contain cobalt in their components, relatively inexpensive and rare earth / iron sintered permanent magnets with excellent magnetic properties have attracted attention as substitutes. Is growing. Nd.
Fe.B alloys and the like are listed.

This rare earth / iron sintered permanent magnet is composed of Nd,
At least one element selected from the group consisting of rare earth elements such as Pr, La, Tb, Dy, and Ce is 8 to 30% by atomic percentage, and boron (B) is 2 to 28% by atomic percentage.
However, since the main components are rare earth and iron, they are oxidized and cause corrosion (formation of rust).
There is a problem that is easy to occur. In particular, rare earth
Since the iron-based sintered permanent magnet is a sintered body of metal powder, its surface has a porous shape with many pores,
Corrosion easily occurs from the pores. In addition, there has been a problem that the metal fine powder adheres to the magnet surface in a non-sintered state, and is easily separated at the time of use, and the metal fine powder is easily separated from pores on the magnet surface. The presence of such fine powder may erase the recording of magnetic recording media such as computer hard disks and floppy disks,
There is a possibility that a fatal problem such as damage to the disc itself may occur.

As methods for improving the corrosion resistance of rare earth / iron based sintered permanent magnets, there are a method of adding an alloy component having an effect of improving corrosion resistance as a magnet component and a method of surface treatment. However, a method of adding an alloy component having an effect of improving corrosion resistance requires an expensive metal component and also has an effect on magnetic properties. Therefore, a method by surface treatment is usually employed.

As methods for improving the corrosion resistance of rare earth / iron based sintered permanent magnets by surface treatment, there are plating methods such as electroless plating and vapor deposition plating of various metals, and resin coating methods. However, metal plating is expensive and the surface of the rare earth / iron sintered permanent magnet is porous (porous) and has an oxidized surface layer. However, there are problems such as poor heat resistance and continuity, difficulty in obtaining sufficient corrosion resistance, and the possibility that the plating may peel off.

On the other hand, the method of increasing the plating thickness in order to improve the corrosion resistance is not only expensive but cannot be applied to a magnetic circuit or the like that requires strict dimensional accuracy. Also, since the surface of rare earth / iron based sintered permanent magnet is active,
It is also necessary to apply a special method to the pretreatment of plating, which further increases the cost. Therefore, a method using resin coating is usually used as a method that can sufficiently improve corrosion resistance at low cost.

For example, Japanese Patent Publication No. 5-6322 discloses that
Corrosion-resistant permanent magnets characterized by coating a corrosion-resistant acrylic resin or epoxy resin on the surface of a permanent magnet body whose main phase is a tetragonal phase are disclosed. It is described that the oxidation of is prevented. Japanese Patent Application Laid-Open No. 61-168221 discloses a method of coating the surface of a rare earth / iron permanent magnet with a fluororesin by a method such as vacuum evaporation, plasma coating, or sputtering.

However, in the above-described resin coating, since the solvent and water are volatilized in a drying step after the application of the coating liquid, pinholes are generated in the coating film, and the formed coating film has oxygen and moisture. Cannot be completely shut off, and corrosion of the magnet surface or peeling or swelling of the coating film cannot be prevented. Also,
Neither can peeling of the metal fine powder from the pinhole of the coating film be prevented.

As a method for solving the above-mentioned problem, Japanese Patent Publication No. 4-22007 discloses a method in which an oxidation-resistant chemical conversion film and a resin layer are sequentially laminated on the surface of a permanent magnet body whose main phase is a tetragonal phase. A method for manufacturing a permanent magnet is disclosed, which discloses a method of performing resin coating after performing a resin coating base treatment using a reactive conversion coating such as zinc phosphate treatment or chromate treatment. .

JP-A-7-57912 discloses a coating layer containing hexavalent chromium, trivalent chromium and silica on the surface of a rare-earth / iron-based sintered permanent magnet, and coating the total amount of Cr by a coating type chromate treatment. in form so that 0.2 to 2 g / m ^2, a method of forming a resin coating film is disclosed in the upper layer of the coating layer.

However, in the method of performing a resin coating base treatment using a reaction type chemical conversion film, a uniform and stable chemical conversion film is obtained on the magnet surface due to the presence of an oxide film on the magnet surface and an active rare earth element which is a main component of the magnet. It becomes difficult. In addition, in the coating type chromate treatment, since the surface of a rare earth / iron based sintered permanent magnet (hereinafter sometimes simply referred to as “magnet”) is porous, corrosion from the pores is prevented. Since it cannot be suppressed, sufficient corrosion resistance cannot be obtained and the problem of blistering of the upper resin coating cannot be solved.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a rare-earth / iron-based sintered permanent magnet having excellent corrosion resistance.
An object of the present invention is to provide a deposition type surface treatment liquid and a surface treatment method for an iron-based sintered permanent magnet, and a rare earth / iron-based sintered permanent magnet having a surface obtained by the surface treatment method.

[0013]

Means for Solving the Problems The present inventors have conducted intensive studies on means for solving the problems of the prior art, in particular, means for solving corrosion from pores on the surface of a magnet. As a result, zirconium, chromium, vanadium, tungsten , Titanium,
By depositing a layer of a compound containing at least one element selected from the group consisting of manganese, molybdenum and silicon on the surface of a rare earth / iron based sintered permanent magnet, a rare earth / iron based sintered permanent magnet having high corrosion resistance is deposited. Was newly found, and the present invention was completed.

That is, the present invention provides: (1) a total amount of ions of at least one metal selected from the group consisting of zirconium, chromium (III), vanadium, tungsten, titanium, manganese, molybdenum, and silicon; 01 to 50 g / L and its p
A deposition type surface treatment liquid for a rare earth / iron-based sintered permanent magnet, wherein H is adjusted to 0.5 to 4.0. (2) The deposited surface of the rare-earth / iron-based sintered permanent magnet according to (1), further comprising 0.01 to 50 g / L of phosphate ions and / or hypophosphite ions. Processing liquid. (3) The above (1) or (2), further comprising 0.1 to 50 g / L of chromium (VI) ions.
2. A deposition-type surface treatment liquid for a rare-earth / iron-based sintered permanent magnet according to (1). (4) The deposition surface treatment liquid for a rare earth / iron-based sintered permanent magnet according to any one of the above (1) to (3), further comprising an alkali generation precursor. (5) It contains at least one kind of metal ion selected from the group consisting of zirconium, chromium (III), vanadium, tungsten, titanium, manganese, molybdenum and silicon in a total amount of 0.01 to 50 g / L, and its pH is 7.
0 to 12.0, and wherein the selected metal ion is stably dissolved as an ammonium salt or ammonia or an amine complex. It is a deposition type surface treatment liquid. (6) The deposited surface of the rare-earth / iron-based sintered permanent magnet according to (5), further comprising 0.01 to 50 g / L of phosphate ions and / or hypophosphite ions. Processing liquid. (7) The above (5) or (6), further comprising 0.1 to 50 g / L of chromium (VI) ions.
2. A deposition-type surface treatment liquid for a rare-earth / iron-based sintered permanent magnet according to (1). (8) The deposition of the rare-earth / iron-based sintered permanent magnet according to any one of the above (1) to (7), wherein the liquid temperature is adjusted at room temperature to 30 ° C. Mold surface treatment liquid. (9) Rare-earth / iron-based sintering in a deposition type surface treatment solution containing ions of at least one metal selected from the group consisting of zirconium, chromium (III), vanadium, tungsten, titanium, manganese, molybdenum, and silicon A dipping step of dipping a permanent magnet, and a deposition step of depositing a compound containing the selected metal element on the surface of the rare earth / iron-based sintered permanent magnet to form a deposition layer, Surface treatment method for rare earth / iron-based sintered permanent magnets. (10) The rare-earth / iron-based sintering according to (9), wherein the deposition-type surface treatment liquid is the deposition-type surface treatment liquid according to any one of (1) to (4). This is a surface treatment method for a permanent magnet. (11) The deposition type surface treatment liquid is the deposition type surface treatment liquid according to any one of the above (1) to (3),
Further, the liquid temperature of the deposition type surface treatment liquid in the immersion step is from room temperature to 30 ° C., and the liquid temperature of the deposition type surface treatment liquid is heated to 40 ° C. to 90 ° C. in the deposition step. The surface treatment method for a rare earth / iron based sintered permanent magnet according to the above (9). (12) The deposition type surface treatment liquid is the deposition type surface treatment liquid according to any one of the above (1) to (3),
The surface treatment of the rare-earth / iron-based sintered permanent magnet according to (9), wherein in the deposition step, an alkaline aqueous solution is added to the deposition-type surface treatment liquid to adjust the pH to 7.0 to 10.0. Is the way. (13) The deposition type surface treatment liquid is the deposition type surface treatment liquid according to the above (4), and the liquid temperature of the deposition type surface treatment liquid in the immersion step is from room temperature to 30 ° C .; At a temperature of 100 to 180 ° C.
(9) The method for treating a surface of a rare earth / iron-based sintered permanent magnet according to the above (9), wherein (14) The rare-earth / iron-based sintering according to (9), wherein the deposition-type surface treatment liquid is the deposition-type surface treatment liquid according to any one of (5) to (7). This is a surface treatment method for a permanent magnet. (15) The liquid temperature of the deposition type surface treatment liquid in the immersion step is from room temperature to 30 ° C., and the liquid temperature of the deposition type surface treatment liquid is heated to 40 ° C. to 90 ° C. in the deposition step. A surface treatment method for the rare earth / iron sintered permanent magnet according to (14). (16) In the deposition step, a water-soluble polar solvent is added to the deposition-type surface treatment liquid.
The surface treatment method for a rare earth / iron-based sintered permanent magnet described in (1). (17) The method of any one of (9) to (16), further comprising a drying step after the depositing step. (18) The method according to (18), further comprising, after the depositing step, an applying step of applying at least one resin paint selected from the group consisting of an epoxy resin, a phenol resin, an acrylic resin, a urethane resin, and a polyester resin. (9) The method for surface treating a rare earth / iron-based sintered permanent magnet according to any one of (17) to (17). (19) A rare-earth / iron-based sintered body, wherein a deposited layer is formed on the surface by the method for treating a rare-earth / iron-based sintered permanent magnet according to any one of (9) to (18). It is a permanent magnet. (20) attached amount of metal elements, rare earth-iron-based sintered according to (19), characterized in that in total in terms of a single respective element is 0.5mg / m ² ~500mg / m ² It is a permanent magnet.

Although the function and effect of the present invention are not clear, the present inventors presume as follows. The film formation mechanism of the deposited layer according to the present invention is different from the chemical conversion film formation reaction (reaction in which the pH on the material surface rises due to material etching and insoluble salts and the like are precipitated), which is generally carried out. (III), in a treatment solution containing ions of at least one metal selected from the group consisting of vanadium, tungsten, titanium, manganese, molybdenum, and silicon, with time, or by any means, hydrolysis of metal ions or pH adjustment. That is, the compound containing the element of the selected metal is caused to rise, and is deposited on the surface of the porous sintered magnet. Particularly, in the present invention, since a precipitate is uniformly formed in the reaction system, it is possible to form a surface film having excellent corrosion resistance, which cannot be obtained by conventional techniques.

The following can be considered as a reason for this. In a precipitation forming reaction in which a precipitate is uniformly generated in the reaction system, the reaction proceeds in a direction of lowering the free energy in the system in principle, so that the precipitate has a particularly high free energy on the sintered magnet surface. It is thought that the reaction is likely to be formed in the pore portion (that is, the reaction is considered to proceed in the direction of decreasing the surface area). Therefore, the deposition in the present invention has an action of sealing the pores by generating and depositing a precipitate preferentially in the pores (sealing action), for example, washing with water without drying. The properties of the film are essentially different from those of dip coating or the like in which all the deposits are removed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. 1. Rare-Earth / Iron-Based Sintered Permanent Magnet to be Treated In the present invention, the rare-earth / iron-based sintered permanent magnet to be surface-treated includes rare-earth elements such as Nd, Pr, La, Tb, Dy, and Ce, and Fe and boron. (B) is a sintered magnet made of an alloy mainly composed of
d.Fe.B sintered permanent magnets.

The magnetic powder to be used as a raw material can be produced from a molten alloy obtained by melting component metals at a time by a rapid quenching method or an atomizing method, and can be further finely pulverized if desired. By molding and sintering this magnetic powder by powder metallurgy to obtain a sintered body having a desired shape, a rare earth / iron-based sintered permanent magnet can be manufactured.

Since rare earth / iron based sintered magnets exhibit magnetic anisotropy, there is a property that the direction of easy magnetization of the magnetic powder is aligned in one direction by applying a magnetic field during molding. Therefore, it is possible to obtain a magnet having excellent magnetic properties unique to the rare earth / iron-based sintered permanent magnet.

The present invention is not limited to a method of manufacturing the magnet itself, such as a method of manufacturing a magnetic powder as a raw material of a magnet, a method of molding the same, and a method of sintering. The present invention can also be applied to a permanent magnet.

2. Deposition-type surface treatment liquid The deposition-type surface treatment liquid that can be used in the surface treatment method of the rare earth / iron-based sintered permanent magnet of the present invention includes a cation component (zirconium ion, chromium (III) ) Ions, vanadium ions, tungsten ions, titanium ions, manganese ions, molybdenum ions, silicon ions). These cation components are dissolved in the deposition-type surface treatment liquid, and it is important that after dipping the magnet in the deposition-type surface treatment liquid, the magnet is insolubilized by some factor and deposited on the magnet surface. Examples of the deposition surface treatment liquid that acts in this manner include the following first and second deposition surface treatment liquids of the present invention.

The first deposition type surface treatment liquid of the present invention comprises at least one selected from the group consisting of zirconium ion, trivalent chromium ion, vanadium ion, tungsten ion, titanium ion, manganese ion, molybdenum ion and silicon ion. 0.0% of total ions
Contains 1 to 50 g / L. If the amount is less than 0.01 g / L, a sufficient amount of the deposited metal compound cannot be secured, and the corrosion resistance may be insufficient. On the other hand, if the amount exceeds 50 g / L, the amount of the deposited metal becomes excessive, and the deposited layer is likely to be missing. On the other hand, the amount of the acid (anion) to be dissolved increases as a whole, and on the contrary, it is difficult to deposit. The total content of these metal ions is preferably 0.01 to 30 g / L, and more preferably 0.05 to 15 g / L.

Further, the pH of the first deposition type surface treatment solution is adjusted to a range of 0.5 to 4.0. When the pH of the deposition type surface treatment liquid exceeds 4.0, the pH of the deposition type surface treatment liquid
Immediately after H is adjusted, precipitation of the cation component is apt to occur. On the other hand, if it is less than 0.5, precipitation of the cation component is difficult to occur, which is not preferable. The pH is preferably adjusted to a range of 1.0 to 3.5, more preferably a range of 1.0 to 3.0. In the present invention, the pH of the deposition surface treatment liquid refers to the pH at each temperature.

The first deposition-type surface treatment liquid may contain phosphate ions and / or hypophosphite ions, if desired. Phosphate ions and / or hypophosphite ions have the effect of facilitating precipitation of the cation component as a phosphate compound. The content is preferably 0.01 to 50 g / L,
More preferably, the content is from 0.01 to 30 g / L, and 0.05
More preferably, it is set to ２０20 g / L. Content is
If it is less than 0.01 g / L, the effect of improving corrosion resistance by containing phosphate ions and / or hypophosphite ions cannot be obtained. On the other hand, if it exceeds 50 g / L, precipitation of the metal compound occurs from the beginning of preparation of the deposition type surface treatment solution, and particularly, when precipitation of the phosphate compound occurs, the deposition layer becomes large and may be missing from the magnet surface. Therefore, it is not preferable. When chromium (III) ions are contained,
When (III) is difficult to deposit and contains zirconium ions, precipitation of zirconium may occur from the beginning of preparation of the surface treatment solution.

Further, in the first deposition type surface treatment liquid,
If desired, hexavalent chromium (chromium (VI)) ions can be contained. Hexavalent chromium ions are present in the solution as chromate ions, and have the effect of cleaning the surface of the magnet (oxidizing adsorbed dirt (organic matter)) and improving corrosion resistance. The content is 0.1 g / L to 5 g / L.
0 g / L, preferably 0.3 to 30 g / L
L, more preferably 0.5 to 15 g / L. If the content is less than 0.1 g / L, the effect of including the hexavalent chromium ion cannot be exerted. On the other hand, if it exceeds 50 g / L, chromic acid acts as an acid, so that the metal element compound to be deposited may be difficult to deposit. In addition, the above 6
The effect of including chromium ions is saturated,
It is not preferable because it is economically disadvantageous and increases the burden of wastewater treatment.

The first deposition type surface treatment liquid is heated (heated).
As a result, the dissolved metal cation component undergoes hydrolysis and precipitates as an oxide, a hydroxide, a phosphate compound, or the like. Therefore, if the initial temperature of the treatment liquid exceeds 30 ° C., the metal cation component dissolved in the treatment liquid may precipitate (insolubilize) before the magnet is immersed. The deposition type surface treatment liquid is preferably prepared at a liquid temperature of normal temperature to 30 ° C. In the present invention, the normal temperature means 5 to 25 ° C,
Considering the dissolved stability of the metal cation component, etc.
The temperature is preferably 25 ° C. (the same shall apply hereinafter in the present invention).

The second surface treatment liquid of the present invention comprises at least one selected from the group consisting of zirconium ion, trivalent chromium ion, vanadium ion, tungsten ion, titanium ion, manganese ion, molybdenum ion and silicon ion. 0.0% of total ions
Contains 1 to 50 g / L. The critical significance of the upper and lower limits of the content and the preferred value are the same as those of the first deposition type surface treatment liquid.

The second deposition type surface treatment solution has a pH of
Is adjusted to the range of 7.0 to 12.0, and at that pH, the metal ion is stably dissolved as an ammonium salt or an ammonium or amine complex. If the pH of the deposition-type surface treatment solution is less than 7, the dissolution stability of the ammonium salt or the ammonium or amino complex of the metal ion is lowered, and the cationic component cannot be stably dissolved. On the other hand, if the pH of the deposition type surface treatment liquid exceeds 12.0, the cationic component is stably dissolved, so that it is difficult to obtain a deposition layer, which is not preferable. The pH of the deposition type surface treatment solution is 8.0 to 12.
It is preferably in the range of 0, more preferably 9.
It is in the range of 0 to 11.0.

The second deposition type surface treatment liquid may contain phosphate ions and / or hypophosphite ions, if desired, similarly to the first precipitation type surface treatment liquid. The content is preferably 0.01 to 50 g / L, more preferably 0.01 to 30 g / L, and even more preferably 0.05 to 20 g / L. When the content is less than 0.01 g / L, the effect of improving corrosion resistance by containing phosphate ions and / or hypophosphite ions cannot be obtained. On the other hand, 50
If the amount exceeds g / L, precipitation of a metal compound occurs from the beginning of preparation of the deposition type surface treatment solution, and particularly, when precipitation of a phosphoric acid compound occurs, the deposition layer is enlarged and may be missing from the magnet surface. Not preferred.

Further, in the second deposition type surface treatment liquid,
Like the first deposition-type surface treatment liquid, hexavalent chromium ions can be contained, if desired. The content is preferably 0.1 g / L to 50 g / L,
It is more preferably 0.3 to 30 g / L, and 0.5 to 30 g / L.
More preferably, it is set to １５15 g / L. If the content is less than 0.1 g / L, the effect of including the hexavalent chromium ion cannot be exerted. On the other hand, 50 g / L
When the value exceeds, chromic acid acts as an acid, so that the compound of the metal element to be deposited may be difficult to deposit. Further, the effect of including the hexavalent chromium ion is saturated, which is economically disadvantageous and increases the burden of wastewater treatment, which is not preferable.

The second deposition type surface treatment liquid is preferably prepared at a temperature of room temperature to 30 ° C. for the same reason as the first deposition type surface treatment liquid.

The first or second deposition type surface treatment solution of the present invention contains at least one of zirconium ion, trivalent chromium ion, vanadium ion, tungsten ion, titanium ion, manganese ion, molybdenum ion and silicon ion. In order to stably dissolve the species ions, an inorganic or organic acid can be added as desired.

The inorganic acid or organic acid that can be added is not particularly limited, but inorganic acids such as hydrofluoric acid, hydrofluoric acid, nitric acid, sulfuric acid and hydrochloric acid, and formic acid, acetic acid and benzoic acid. Organic acids such as carboxylic acids, organic acids such as oxycarboxylic acids such as tartaric acid and citric acid, and organic acids such as phenols such as tannic acid are preferred. Among them, hydrofluoric acid, hydrofluoric acid and nitric acid are more preferred.

The source of the zirconium ions in the deposition type surface treatment liquid of the present invention is not particularly limited, but zirconium fluoride, ammonium salt of zirconium fluoride, alkali metal salt, zirconium oxynitrate, oxynitrate, Water-soluble compounds such as zirconium chloride and ammonium complexes such as ammonium zirconium carbonate are preferred.

The source of the trivalent chromium ion is not particularly limited, but includes chromium biphosphate, chromium fluoride, chromium nitrate, chromium sulfate, chromium chloride, chromium chromate, and hexavalent chromium (chromium). Trivalent chromium obtained by reducing a part of (acid). The reducing agent that reduces a part of hexavalent chromium (chromic acid) is not particularly limited, but generally known organic compounds can be used. For example, methanol, ethanol, ethylene glycol, glucose, saccharose, dextrin, starch, tannic acid and the like.
It is preferable because it is easily available.

The source of the vanadium ion is not particularly limited, but vanadium may be divalent, trivalent or tetravalent.
It is a transition element that can take an ionic state of each valence of valence and pentavalent, and specifically, a halogen compound such as chloride and fluoride, sulfate, nitrate, vanadate, alkali metal of vanadate Examples thereof include water-soluble salts such as salts, alkaline earth metal salts and ammonium salts, vanadium oxide and vanadium hydroxide dissolved in an acid.

There is no particular limitation on the source of tungsten ions, but tungsten is divalent, tetravalent,
Is a transition element that can assume each of valence states of pentavalent, pentavalent, and hexavalent, and specifically includes halogen compounds such as chlorides and fluorides of respective valences, oxyhalides, tungstic acid, and tungstic acid. Examples thereof include an alkali metal salt, an ammonium salt, and a solution obtained by dissolving an oxide in an acid.

The supply source of titanium ions is not particularly limited. Titanium is a transition element that can take a divalent, trivalent, or tetravalent ion state. In the ionic state. Specifically, titanium chloride, titanium fluoride, titanium sulfate, titanyl sulfate, hexafluorotitanic acid and salts thereof, hexachlorotitanic acid and salts thereof, Ti (OR) ₄
(R is an alkyl group or an aryl group), and a titanium coupling agent.

The source of manganese ions is not particularly limited, but manganese may be divalent, trivalent, tetravalent,
It is a transition element that can take a pentavalent, hexavalent, and heptavalent ionic state, and specifically, halides such as chlorides and fluorides of respective valences, nitrates, sulfates,
Phosphates, manganic acid, alkali metal salts of manganic acid,
Examples thereof include permanganic acid, alkali metal salts of permanganic acid, and ammonium salts.

The source of the molybdenum ion is not particularly limited, but molybdenum may be divalent, trivalent or tetravalent.
Is a transition element that can take each of the valence states of pentavalent, pentavalent, and hexavalent, and specifically includes halogen compounds such as chlorides and fluorides of each valence, oxyhalides, molybdates, and molybdates. Examples thereof include alkali metal salts, ammonium salts, oxides, and hydroxides dissolved in an acid.

The supply source of silicon ions is not particularly limited, but specifically, hexafluorosilicic acid,
Hexafluorosilicate, silicic acid, alkali metal salt of silicic acid,
Examples include ammonium salts, siloxanes, siloxenes, silane coupling agents, and water-dispersed colloidal silica.

3. Surface treatment method for rare earth / iron-based sintered permanent magnet The surface treatment method for rare earth / iron-based sintered permanent magnet in the present invention comprises zirconium, chromium (III), vanadium, tungsten, titanium, manganese, molybdenum, and silicon. An immersion step of immersing the rare earth / iron-based sintered permanent magnet in a deposition type surface treatment solution containing ions of at least one metal selected from the group; Forming a deposition layer for depositing a compound containing a metal element. At this time,
As the deposition type surface treatment liquid, it is desirable to use the above-described first or second deposition type surface treatment liquid. Further, the surface treatment method of the rare earth / iron-based sintered permanent magnet of the present invention includes:
Further, a drying step and a coating step may be provided. Hereinafter, each step will be described separately.

(1) Immersion Step In the step of immersing the rare-earth / iron-based sintered permanent magnet, the liquid temperature during the immersion treatment is not particularly limited, and may be, for example, room temperature. Therefore, when the deposition type surface treatment liquid is prepared at 30 ° C. or lower as described above, the immersion treatment can be performed at the same temperature, and from the viewpoint of economy, the deposition type surface treatment liquid is purposely cooled. No need.

(2) Deposition Step In the present invention, after the immersion step, the metal ion component dissolved in the deposition type surface treatment solution is insolubilized by some means, whereby the metal compound is deposited on the magnet surface to deposit the metal compound. Requires a deposition step to form Of course, if the deposition type surface treatment liquid is unstable to some extent, the deposition step can be simply aged, but in order to increase the processing efficiency and obtain a more corrosion-resistant magnet,
It is effective to take aggressive deposition measures.

When the first deposition type surface treatment liquid is used, there are the following three types of deposition means.

After the immersion step, the deposition surface treatment liquid is heated to 40 ° C. or higher, preferably 50 ° C. or higher, more preferably 60 ° C. or higher to insolubilize metal ions contained in the deposition type surface treatment liquid. By doing so, a method of depositing a compound containing at least one element selected from the group consisting of zirconium, chromium, vanadium, tungsten, titanium, manganese, molybdenum, and silicon on the magnet surface can be mentioned.

At this time, it is preferable to maintain the temperature for at least 10 minutes after the temperature of the deposition type surface treatment solution is raised to a predetermined temperature, more preferably at least 30 minutes. Further, the temperature holding time is preferably within 120 minutes. After the immersion step, it is possible to deposit the metal compound on the magnet surface by leaving the deposition type surface treatment liquid without heating for a certain period of time, but without heating, the deposition rate of the cation component is slow. Not economical.

The rate of temperature rise of the deposition-type surface treatment liquid is not particularly limited, and can be freely set depending on the composition of the deposition-type surface treatment liquid or within a range that can be industrially profitable. However, when the temperature exceeds 90 ° C., the evaporation rate of the deposition surface treatment liquid rapidly increases, so that the concentration of the deposition surface treatment liquid tends to change, which is not appropriate.

After the immersion step, a method of depositing a metal compound on the magnet surface by adding an aqueous alkaline solution to the deposition-type surface treatment solution to raise the pH of the deposition-type surface treatment solution to 7 or more can be mentioned. The concentration of the aqueous alkali solution to be added is preferably 0.05 to 3 N, and 0.1 to 3 N.
It is more preferable to set the concentration to 2 N, and 0.5 to 1.5
More preferably, the concentration is specified.

As the alkaline aqueous solution to be used, NaO
An aqueous solution such as H or KOH or aqueous ammonia is preferred. Further, the rate of dropping (pH adjustment) of the aqueous alkali solution with respect to the deposition type surface treatment liquid is not particularly limited. However, if the dropping rate is too fast, local pH increase in the deposition type surface treatment liquid becomes remarkable, and This is not preferable because the object cannot be deposited on the magnet to be processed (since a precipitate is generated alone).

An alkali (ammonia) generating precursor such as urea is added in advance to the deposition type surface treatment solution, and the deposition type surface treatment solution is heated (heated) to hydrolyze it.
By generating alkali, the deposition type surface treatment liquid
Means for raising H, insolubilizing the compound of the cation component, and depositing a metal compound on the surface of the magnet. In this case, the deposition-type surface treatment liquid needs to contain an alkali-generating precursor in advance. Specific examples of the alkali include urea, hydrazine and derivatives thereof in addition to urea.

The heating temperature required for the hydrolysis of the alkali generation precursor is preferably from 100 ° C. to 180 ° C., more preferably from 120 ° C. to 160 ° C. Although it is possible to hydrolyze at less than 100 ° C., it is not economical because it requires time. Further, if the hydrolysis is performed under pressure (for example, in an autoclave), even if the temperature of the deposition surface treatment liquid is 100 ° C. or more, the evaporation rate of the deposition surface treatment liquid is increased as described above. There is no problem such as sudden increase.

On the other hand, when the second deposition type surface treatment liquid is used, there are the following two types of deposition means. In the case of using the second deposition type surface treatment liquid, the deposition method of the present invention is to heat (heat) to 40 ° C. or higher, preferably 50 ° C. or higher, more preferably 60 ° C. or higher after the above immersion step. By insolubilizing the metal ions contained in the deposition type surface treatment liquid, zirconium,
Means for depositing a layer of a compound containing at least one element selected from the group consisting of chromium, vanadium, tungsten, titanium, manganese, molybdenum, and silicon on the magnet surface.

At this time, after the temperature of the processing solution is raised to a predetermined temperature,
The temperature is preferably maintained for 0 minute or more, more preferably 30 minutes or more. The temperature holding time is 120
It is preferably within minutes. After the immersion step, it is possible to deposit the metal compound on the magnet surface by leaving the deposition type surface treatment liquid without heating for a certain period of time, but without heating, the deposition rate of the cation component is slow. Not economical.

The rate of temperature rise of the deposition-type surface treatment liquid is not particularly limited, and can be freely set according to the composition of the deposition-type surface treatment liquid or within a range that can be industrially profitable. If the treatment temperature in the deposition step exceeds 90 ° C., the evaporation rate of the deposition-type surface treatment liquid rapidly increases, so that the concentration of the deposition-type surface treatment liquid tends to change, which is not appropriate.

After the immersion step, by adding a water-soluble polar solvent to the deposition type surface treatment solution, the salt formed with the cation component or the complex formed with the cation component and the complexing agent is destabilized and dissolved. Means for depositing the cation component that has been used. Examples of the water-soluble polar solvent include formalin, alcohols such as methanol, ethanol, propanol and butanol, ethers such as methyl ether and ethyl ether, and aldehydes such as acetone, formaldehyde and acetaldehyde.

(3) Rinse step In the surface treatment of the rare earth / iron based sintered permanent magnet of the present invention, after the deposition step, the magnet is taken out of the deposition type surface treatment liquid, and it is determined whether or not the magnet should be rinsed. The determination is made based on the composition of the deposited surface treatment solution, the amount of deposition, the presence or absence of post-treatment, and the like. For example, if a deposition type surface treatment solution containing hexavalent chromium is used, drying the magnet without washing it with water is more effective for improving the corrosion resistance, but when performing post-treatment with further resin coating, etc. Has a large amount of hexavalent chromium deposited,
It is preferable to provide a water washing step because it may cause swelling of the coating film and poor adhesion. The water may be ordinary tap water, but it is preferable to use pure water or deionized water.

(4) Drying Step In the surface treatment method for a rare earth / iron-based sintered permanent magnet of the present invention, drying is preferably performed after the above-mentioned deposition step or water washing step. As a drying method, so-called draining drying is sufficient, but from the viewpoint of workability and productivity, it is preferable to dry at a temperature in the range of 50 ° C to 200 ° C, and in the range of 80 ° C to 180 ° C. Drying at a temperature is more preferred.

(5) Coating Step In the surface treatment method for a rare earth / iron-based sintered permanent magnet of the present invention, a resin paint is further applied to the surface of the rare earth / iron-based sintered permanent magnet on which the deposited layer is formed. It is preferable to have a coating step. As a result, the corrosion resistance of the magnet can be further improved, and the loss of unsintered metal powder and metal fine powder on the magnet surface can be prevented.

As such a resin coating, any of a solvent-based coating, a water-based coating, and a powder coating can be used.
Solvent-based or water-based thermosetting resin paints are preferable, and those made of epoxy resin, phenol resin, acrylic resin, urethane resin, polyester resin and the like are preferable. The thickness of the coating film formed by applying the resin paint is not particularly limited, but 1 to 50 μm
Is preferable (however, when powder coating is performed, 30
About 120 μm is preferable, and about 100 μm is more preferable. ). Examples of the method of applying the resin paint include a method of applying the resin paint to the surface of the magnet by a method such as spraying, roll coating, dipping, and electrodeposition. After the application, it is preferable to dry (bake).

4. Rare-earth / iron-based sintered permanent magnets
Rare earth / iron-based sintered permanent magnets with surface treatment are extremely resistant
It becomes excellent in food quality. At this time, the amount of metal compound attached
(In the present invention, the term "adhesion amount"
What happens and what adheres to the gaps and surfaces
Refers to the total amount of ) Is the total converted to each element
0.5mg / m^Two~ 500mg / m^TwoGood to be
0.8mg / m^Two~ 300mg / m^TwoIs
Is more preferable, and 1.0 mg / m^Two~ 100mg / m
^TwoIs more preferable. 500mg /
m ^TwoIf it exceeds the value, the effect of improving the corrosion resistance of the compound layer (film) will
It is not economical because it will add up, and the deposited compound
This is not preferable because the layer may easily be missing.
On the other hand, the adhesion amount is 0.5 mg / m^TwoIf less than the deposition layer
Is not preferred, because the effect of forming is not sufficient.

[0062]

EXAMPLES The present invention will be described specifically with reference to the following examples, but the present invention is not limited to these examples. <Production of target rare earth / iron sintered permanent magnet> Purity 9
482 parts by weight of 9.9% electrolytic iron, 180 parts by weight of Nd having a purity of 99.7% or more, 19.4% by weight of B, 5.3% by weight of Al, 0.7% by weight of Si, and 0% by weight of C. An ingot was obtained by subjecting 0.03% by weight of the ferroboron alloy (360 parts by weight of Fe) to high frequency melting and then casting. The obtained ingot was pulverized by a stamp mill to a size of 35 mesh or less, and further pulverized by a ball mill for 3 hours to obtain an alloy fine powder having a particle size of 10 μm or less. The obtained alloy fine powder was inserted into a mold, and a so-called transverse magnetic field molding was performed in a magnetic field of 15 kOe in which the pressing direction and the magnetic field direction were perpendicular to each other. The applied pressure is 2 ton
/ Cm ² . The obtained molded body was heated and sintered at 1100 ° C. for 1 hour in an argon gas atmosphere to obtain a rare-earth / iron-based sintered permanent magnet to be subjected to surface treatment. The component composition of the obtained magnet was 18Nd-7B-75Fe. 5 mm x 10 mm x from the obtained rare earth / iron based sintered permanent magnet
A test piece was cut out to a size of 2 mm and the surface was ground by barrel polishing.

<Preparation of Surface Treatment Solution> (1) Preparation of Surface Treatment Solution A 200 g of chromic anhydride was dissolved in 500 g of pure water, and tannic acid (concentration: 10%) dissolved in pure water was gradually added thereto. By adding, a part of hexavalent chromium was reduced. At this time, the weight ratio of Cr ³⁺ / Cr ⁶⁺ was 0.28 (the amount of the added tannic acid aqueous solution was 100 g). To this, 15 g of phosphoric acid (H ₃ PO ₄ ) and 15 g of zirconium hydrofluoric acid (H ₂ ZrF ₆ ) were added, and pure water was added to make a total amount of 1 kg. 81.2 g / L, trivalent chromium ion 22.8 g / L, phosphate ion 14.5 g / L, zirconium ion 6.6 g / L). 5 g of this test solution I was taken, and pure water was added thereto to make 1 L (5 g / L bath), which was used as a surface treatment solution A (pH 2.5).

(2) Preparation of Surface Treatment Solution B Test solution I obtained in the process of preparing surface treatment solution A
A bath prepared at 0 g / L was used as a surface treatment solution B (pH 1.2)
And

(3) Preparation of Surface Treatment Solution C 32.3 g of chromium fluoride (CrF ₃ .3H ₂ O) and zirconyl oxynitrate (ZrO (NO ₃ ) ₂ .2H ₂ O)
Was taken in 8.5 g and dissolved in 950 g of pure water. To this, 7 g of phosphoric acid (H ₃ PO ₄ ) was added, and pure water was further added to bring the total amount to 1 kg. Test solution II (10.2 g of trivalent chromium ion)
/ L, 2.9 g / L of zirconium ions and 6.8 g / L of phosphate ions). 5 g of this test solution II was taken, and pure water was added to the solution to make 1 L (5 g / L bath). This was used as a surface treatment solution C (pH 2.0).

(4) Preparation of Surface Treatment Solution D The test solution II obtained in the process of preparing the surface treatment solution C
A bath prepared at 0 g / L was treated with a surface treatment solution D (pH 1.8).
And

(5) Preparation of Surface Treatment Solution E 50% aqueous solution of chromium biphosphate (Cr (H ₂ PO ₄ ) ₃ :
Trivalent chromium ion 76 g / L, phosphate ion 418 g / L
L) was taken in an amount of 10 g, and pure water was added thereto to make the total amount 1 L. This was used as a surface treatment solution E (pH 1.5).

(6) Preparation of Surface Treatment Solution F 15 g of 1 N hydrochloric acid and zirconyl oxynitrate (ZrO (N
_{O 3) 2 · 2H 2 O} ) takes a 0.5g, pure water 1 this
L, then 0.9 g of sodium hypophosphite (NaH ₂ PO ₂ .H ₂ O) was dissolved in 100 g of pure water, and a liquid obtained by mixing these was designated as a surface treatment liquid F (pH 0.9).

(7) Preparation of Surface Treatment Liquid G 14 g of an aqueous solution of zirconium ammonium carbonate (20% as ZrO ₂ ) and 14 g of NaH ₂ PO ₄ .2H ₂ O are dissolved in pure water to make a total volume of 1 L. (PH
9.1).

(8) Preparation of Surface Treatment Solution H 5.4 g of chromium nitrate (Cr (NO ₃ ) ₃ .9H ₂ O)
And 1.7 g of urea were dissolved in pure water to make a total volume of 1 L, which was used as a surface treatment liquid H (pH 3.0).

(9) Preparation of Surface Treatment Solution I The test solution I obtained in the process of preparing the surface treatment solution A was
A bath was prepared at 0 g / L, and the pH was adjusted to 8 by adding a 1 N aqueous solution of NaOH, whereby a precipitate was formed in the liquid. The resulting precipitate was filtered through filter paper, and the obtained filtrate was used as surface treatment solution I (pH 8.1).

(10) Preparation of Surface Treatment Solution J Take 1 L of the same 50% chromium biphosphate aqueous solution as used in the preparation of Surface Treatment Solution E, and use it in Surface Treatment Solution J (pH
0.4).

(11) Preparation of Surface Treatment Solution K To an aqueous solution in which 200 g of chromic anhydride was dissolved in 500 g of pure water, an aqueous methanol (10% methanol content) solution in pure water was gradually added in a separate container, and hexavalent chromium was added. Was partially reduced. However, a precipitate was formed on the way (when 170 g of the aqueous methanol solution was added), and the aqueous solution was gelled, so that the surface treatment liquid K could not be obtained.

(12) Preparation of surface treatment liquid L 200 g of chromic anhydride was dissolved in 500 g of pure water, and 42 g of phosphoric acid (H ₃ PO ₄ ) was added to an aqueous solution. Methanol content 10%) 1
After 90 g was gradually added to reduce a part of hexavalent chromium, pure water was added to make a total amount of 1 kg (weight ratio of Cr ³⁺ / Cr ⁶⁺ was 1/1). To 250 g of the obtained reduced solution of chromic acid,
200 g of colloidal silica (manufactured by Nissan Chemical Industries, ST-O, 20% as SiO ₂ ) was added, and pure water was added thereto to make a total amount of 1 kg to obtain a surface treatment liquid L (pH 2.0).

(13) Preparation of Surface Treatment Solution M The same 50% chromium biphosphate aqueous solution as used for the preparation of the surface treatment solution E was prepared at 350 g / L and treated with the surface treatment solution M (pH 0.8). And

The surface treatment solutions A to J and L to M
2 shows the results of component analysis.

[0077]

[Table 1]

Example 1-1 Forty test pieces were placed in a stainless steel basket, immersed in a surface treatment solution A whose temperature was adjusted to 22 ° C., and heated while stirring the surface treatment solution. 3
The temperature was raised to 80 ° C. in 0 minutes, and the temperature was maintained for 1 hour. Next, 20 test pieces were taken out of the treatment liquid, washed with tap water, and dried in a drying oven at 80 ° C. for 3 minutes to obtain a sample magnet 1-1.

Example 1-2 Ten of the sample magnets 1-1 obtained in Example 1-1 were coated with a commercially available solvent-type epoxy resin paint (Epiclon H-303-, manufactured by Dainippon Ink and Chemicals, Inc.). 45) was spray-coated and baked and dried in a drying oven at 130 ° C. for 25 minutes to obtain a sample magnet 1-2. The thickness of the formed coating film is 20μ.
m.

Example 1-3 Twenty test pieces remaining in the surface treatment liquid A in Example 1-1 were taken out, and the surface treatment liquid was blown off with an air blow without washing with water and dried as it was. The sample was dried in an oven at 80 ° C. for 3 minutes to obtain a sample magnet 1-3.

[Example 1-4] With respect to 10 sample magnets 1-3 obtained in Example 1-3, Example 1-2 was used.
Apply epoxy resin paint in the same manner as in
4 was obtained.

Example 2 Twenty test pieces were immersed in the surface treatment liquid B adjusted to 23 ° C., and heated for 6 minutes in 15 minutes.
The temperature was raised to 0 ° C. and kept at that temperature for 2 hours. Then
Without washing, the surface treatment liquid was blown off by air blow and dried in a drying oven at 110 ° C. for 5 minutes to obtain a sample magnet 2.

Example 3-1 Thirty test pieces were immersed in the surface treatment liquid C adjusted to 25 ° C., heated to 60 ° C. in 25 minutes, and kept at that temperature for 30 minutes. Next, the magnet was taken out of the surface treatment liquid, washed with water,
The sample magnet was dried for 5 minutes in a drying oven at
I got

Example 3-2 Fifteen of the sample magnets 3-1 obtained in Example 3-1 were coated with a water-based epoxy resin paint (Epiclon EXA, manufactured by Dainippon Ink and Chemicals, Inc.).
-8820), and after lifting, blow off excess paint with air blow and dry in a drying oven at 150 ° C.
Baking and drying were performed for 0 minutes to obtain a sample magnet 3-2. The film thickness of the formed coating film was 5 μm.

Example 3-3 Thirty test pieces were immersed in the surface treatment liquid D adjusted to 25 ° C., heated to 70 ° C. in 30 minutes by heating, and kept at that temperature for 1 hour. Next, the magnet was taken out of the surface treatment solution, washed with water, and then heated to 100 ° C.
The sample was dried in an atmosphere drying oven for 5 minutes to obtain a sample magnet 3-3.

[Example 4] 30 test pieces were immersed in the surface treatment solution E adjusted to 26 ° C, and heated for 8 minutes in 40 minutes.
The temperature was raised to 0 ° C., and the temperature was maintained for 1 hour. Next, the test piece was taken out and air-dried at normal temperature without washing with water to obtain a sample magnet 4.

Example 5-1 One liter of the surface treatment solution F adjusted to 30 ° C. was taken, 30 test pieces were immersed in the solution, and the temperature was raised to 80 ° C. by heating for 45 minutes.
By gradually adding the aqueous solution, the pH of the surface treatment solution
Was raised to 7 and held at 80 ° C. for 30 minutes. Next, the test piece was taken out, washed with pure water, and dried in a drying oven at 80 ° C. for 5 minutes to obtain a sample magnet 5-1.

[Example 5-2] An aqueous urethane resin (Neotan UE-1200 manufactured by Toa Gosei Co., Ltd. (provided that the total solid content is 15%) was applied to 15 of the sample magnets 5-1 obtained in Example 5-1. On the other hand, colloidal silica manufactured by Nissan Chemical Co., and Snowtex N is blended so that 15% is silica), spray-coated and baked and dried in a drying oven at 150 ° C. for 10 minutes to obtain a sample magnet 5-2. . The film thickness of the formed coating film was 10 μm.

Example 6-1 Forty test pieces were immersed in the surface treatment liquid G adjusted to 20 ° C., heated to 70 ° C. in 60 minutes, and kept at that temperature for 1 hour. . Next, 20 of the test pieces were taken out, washed with pure water,
The sample was dried in a drying oven at 10 ° C. for 10 minutes to obtain a sample magnet 6-1.

[Example 6-2] The remaining 20 test pieces in the surface treatment liquid G in Example 6-1 were taken out, and the surface treatment liquid adhered to the surface was cut off by air blowing, without washing with water. Drying was performed for 10 minutes in a drying oven at 110 ° C.

Example 7-1 0.8 L of the surface treating solution H adjusted to 23 ° C. and 20 test pieces were placed in an autoclave having a capacity of 1 L, and the temperature was raised to 140 ° C. by heating.
Hold that temperature for hours. Thereafter, the sample was cooled to about 40 ° C., the test piece was taken out, washed with pure water, and dried in a drying furnace at 100 ° C. for 3 minutes to obtain a sample magnet 7-1.

[Example 7-2] For 10 of the sample magnets 7-1 obtained in Example 7-1, a solvent-based acrylic resin paint (resin manufactured by Mitsui Chemicals, product name: Almatex 784, Uvan 20SE60) , Epicoat 1001
Is spray-coated with a solid content of 70:20:10)
Baking and drying were performed in a drying oven at 160 ° C. for 25 minutes to obtain a sample magnet 7-2. The film thickness of the formed coating film was 20 μm.

Example 8-1 Twenty test pieces were immersed in the surface treatment solution M adjusted to 24 ° C., heated to 70 ° C. in 90 minutes, and maintained at that temperature for 20 minutes. .
Next, the test piece was taken out, washed with water, and dried in a drying oven at 100 ° C. for 5 minutes to obtain a sample magnet 8-1.

[Embodiment 8-2] Ten of the sample magnets 8-1 obtained in the embodiment 8-1 were used in the embodiment 1-
Epoxy resin coating was performed in the same manner as in Example 2 to obtain a sample magnet 8-2.

Comparative Example 1-1 Twenty test pieces were placed in acetone taken in a beaker, and an ultrasonic cleaner (device name: U
T-205, manufactured by Sharp Corporation, condition: 200W, 5m
in. ), Then take out and air dry,
A sample magnet H1-1 was obtained.

Comparative Example 1-2 Ten of the sample magnets H1-1 obtained in Comparative Example 1-1 were coated with epoxy resin in the same manner as in Example 1-2 to obtain a sample magnet H1-2. Was.

[Comparative Example 2] Forty test pieces were immersed in the surface treatment solution I adjusted to a solution temperature of 22 ° C, heated to 45 ° C in 15 minutes, and maintained at that temperature for 15 minutes. .
Next, all the test pieces were taken out of the surface treatment solution, washed with pure water, and dried in a drying oven at 100 ° C. for 5 minutes.
A sample magnet H2 was obtained.

Comparative Example 3-1 Twenty test pieces were preheated in an atmosphere oven at 70 ° C., and the treatment liquid L was sprayed on the surface of the preheated test material using a spray, and water was evaporated by latent heat. , Forming a chromate film, sample magnet H3
-1 was obtained.

Comparative Example 3-2 Ten of the sample magnets 3-1 obtained in Comparative Example 3-1 were coated with epoxy resin in the same manner as in Example 1-2, and the sample magnet H3-2 was prepared.
I got

Comparative Example 4-1 Twenty test pieces were immersed in the surface treatment solution J adjusted to 24 ° C., heated to 70 ° C. in 90 minutes, and maintained at that temperature for 20 minutes. .
Then, the test piece was taken out and washed 100 times without washing.
The sample magnet H4-
1 was obtained.

[Comparative Example 4-2] Example 1 was applied to ten of the sample magnets H4-1 obtained in Comparative Example 4-1.
Epoxy resin coating was performed in the same manner as in -2, to obtain a sample magnet H4-2. <Evaluation Method> Each of the surface treatment liquids A to J and LM obtained as described above, or each of the sample magnets obtained in Examples and Comparative Examples was evaluated as follows.

(1) Evaluation of Precipitation Generation in Surface Treatment Solution The surface treatment solutions A to J and LM prepared above were prepared in the corresponding Examples and Comparative Examples except that the test pieces were not immersed in the treatment solution. A deposition means was applied in the same manner as described, and the presence or absence of the formation of a precipitate was observed and evaluated. as a result,
In the surface treatment solutions A to H and M, a precipitate was formed, but in the surface treatment solutions I, J and L, no precipitate was formed.

(2) Evaluation of Deposits The amount of chromium or zirconium adhering to the magnet surface for each sample magnet to which no paint was applied (in addition to the adhesion amount in the present invention, the amount of chromium or zirconium adhering to the magnet surface by coating and drying Was directly measured with a fluorescent X-ray analyzer (device name: System 3270E, manufactured by Rigaku Corporation). Table 2 shows the results.

[0104]

[Table 2]

(3) Corrosion resistance (HCT) Each sample magnet was left in a 60 ° C., 90% RH atmosphere for 240 hours, 480 hours, and 720 hours, respectively, and then rust was generated on the magnet surface. The state was visually evaluated according to the following evaluation criteria. The results are shown in Tables 3 and 4.

(Evaluation Criteria) な し: No change 磁石: Magnet surface is slightly discolored 錆: Rust generation in pores can be confirmed by microscopic observation ×: Rust generation is entirely confirmed Possible XX: Significant rust generation can be confirmed

(4) Surface Peelability For each sample magnet, no. The surface of the magnet was rubbed with a 5B filter paper, and the amount of deposits attached to the filter paper was visually measured before and after the corrosion resistance (after 480 hours of HCT) test, and evaluated according to the following evaluation criteria. Was.
The results are shown in Tables 3 and 4.

(Evaluation Criteria) 付 着: No attached matter attached at all ○: Very little attached matter attached Δ: Apparently attached matter attached X: Extremely attached matter attached

[0109]

[Table 3]

[0110]

[Table 4]

<Consideration of Examples / Comparative Examples> As is clear from the results of evaluation of the occurrence of precipitation in the surface treatment solutions, the surface treatment solutions A to H and M, which are the surface treatment solutions of the present invention, were prepared immediately after preparation. No precipitate was generated, and a precipitate was generated after a predetermined deposition treatment operation. Therefore, the compound layer (film) formed on the surface of the sample magnet of the example
In the deposition treatment, trivalent chromium ions and zirconium ions in the surface treatment liquid are hydrolyzed by heating due to the operation of the deposition treatment, and precipitates generated due to an increase in the pH of the surface treatment liquid are deposited on the magnet surface. It can be seen that it was formed as a result. On the other hand, in the surface treatment liquids I, J and L used in the comparative examples, no precipitate was generated even after the operation of the deposition treatment.

As is clear from Tables 2 to 4, the rare earth / iron sintered permanent magnets obtained in the examples have excellent corrosion resistance. In particular, the present invention is effective in suppressing corrosion from pores. there were. Furthermore, there was little loss of fine powder from the magnet surface, and there was no influence on magnetic properties.

On the other hand, in the magnet obtained in the comparative example, the magnet alone did not have any corrosion resistance (Comparative Example 1-1). It turns out that corrosion resistance is inferior and that the coating film swells (Comparative Example 1-2). In the surface treatment liquid, if a precipitate is generated before the magnet is immersed, the compound layer is not formed on the magnet surface even when the depositing operation is performed thereafter, so that the corrosion resistance may be inferior to the example. It can be seen (Comparative Example 2). Further, when the compound layer was formed on the magnet surface by chromate treatment, even if the amount of Cr was large, the corrosion resistance was poor and the peelability was poor (Comparative Examples 3-1 and 3-
2). This is presumably because corrosion from the pores could not be suppressed. Further, in Comparative Examples 4-1 and 4-2 in which the sample magnet was immersed in the surface treatment liquid J, the amount of adhesion on the surface of the sample magnet was large (950 m).
g / m ² ), which is not due to the deposition in the present invention, but simply because the surface treatment liquid J was applied to the surface of the sample magnet to form a coating film.
Therefore, it is considered that the corrosion resistance was inferior to the sample of the example in which the compound layer was formed by deposition.

[0114]

As described above, according to the present invention, a rare earth element having extremely excellent corrosion resistance, which is not heretofore, and extremely useful as a magnetic material for a magnetic circuit of electric / electronic devices, computers, communication devices, etc. The present invention can provide a deposition type surface treatment liquid and a surface treatment method for an iron-based sintered permanent magnet, and a rare earth / iron-based sintered permanent magnet having a surface obtained by the surface treatment method.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C23C 22/62 C23C 22/62 22/73 22/73 Z 22/82 22/82 28/04 28/04 H01F 1 / 053 H01F 41/02 G 1/08 1/04 H 41/02 1/08 BF term (reference) 4K026 AA02 BA01 BA02 BA06 BA08 BA12 BB08 CA13 CA15 CA18 CA19 CA20 CA21 CA23 CA26 CA27 CA28 CA29 CA30 CA31 CA32 CA37 CA41 DA03 DA11 DA12 DA13 DA16 EB08 EB11 4K044 AA02 AB05 BA12 BA15 BA17 BA21 BB01 BB03 BC02 CA16 CA53 5E040 AA04 AA19 BC01 BC05 BC08 BD01 CA01 HB14 NN05 NN17 NN18 5E062 CC03 CD04 CG03 CG07

Claims (20)

[Claims] 1. The method according to claim 1, wherein the total amount of ions of at least one metal selected from the group consisting of zirconium, chromium (III), vanadium, tungsten, titanium, manganese, molybdenum, and silicon is 0.01 to 50 g / L. And,
A deposition type surface treatment liquid for a rare earth / iron sintered permanent magnet, the pH of which is adjusted to 0.5 to 4.0. 2. The deposited rare earth / iron sintered permanent magnet according to claim 1, further comprising 0.01 to 50 g / L of phosphate ions and / or hypophosphite ions. Surface treatment liquid. 3. The deposition type surface treatment liquid for a rare earth / iron-based sintered permanent magnet according to claim 1, further comprising 0.1 to 50 g / L of chromium (VI) ions. . 4. The deposition surface treatment liquid for a rare earth / iron-based sintered permanent magnet according to claim 1, further comprising an alkali generation precursor. 5. A method according to claim 1, wherein the total amount of ions of at least one metal selected from the group consisting of zirconium, chromium (III), vanadium, tungsten, titanium, manganese, molybdenum and silicon is 0.01 to 50 g / L. That p
H is adjusted to 7.0 to 12.0, and the ion of the selected metal is stably dissolved as an ammonium salt, ammonia, or an amine complex. Deposition type surface treatment liquid for permanent magnets. 6. The deposited rare-earth / iron-based sintered permanent magnet according to claim 5, further comprising 0.01 to 50 g / L of phosphate ions and / or hypophosphite ions. Surface treatment liquid. 7. The deposition surface treatment liquid for a rare earth / iron-based sintered permanent magnet according to claim 5, further comprising 0.1 to 50 g / L of chromium (VI) ions. . 8. The deposition type of a rare earth / iron based sintered permanent magnet according to claim 1, wherein the liquid temperature is adjusted at a normal temperature to 30 ° C. Surface treatment liquid. 9. A rare earth / iron system in a deposition type surface treatment solution containing ions of at least one metal selected from the group consisting of zirconium, chromium (III), vanadium, tungsten, titanium, manganese, molybdenum and silicon. A dipping step of dipping a sintered permanent magnet, and a deposition step of depositing a compound containing an element of the selected metal on the surface of the rare earth / iron-based sintered permanent magnet to form a deposition layer. Characteristic surface treatment method for rare earth and iron-based sintered permanent magnets. 10. The rare-earth / iron-based sintered permanent magnet according to claim 9, wherein the deposition-type surface treatment liquid is the deposition-type surface treatment liquid according to any one of claims 1 to 4. Surface treatment method. 11. The deposition type surface treatment liquid according to claim 1, wherein the temperature of the deposition type surface treatment liquid in the immersion step is from room temperature to 30 ° C. The method of claim 9, wherein the temperature of the deposition type surface treatment liquid is 40 ° C. to 90 ° C. in the deposition step. . 12. The deposition type surface treatment liquid is the deposition type surface treatment liquid according to any one of claims 1 to 3, and in the deposition step, an alkaline aqueous solution is added to the deposition type surface treatment liquid to adjust its pH. The surface treatment method for a rare-earth / iron-based sintered permanent magnet according to claim 9, wherein the surface treatment is set to 7.0 to 10.0. 13. The deposition type surface treatment liquid according to claim 4, wherein the temperature of the deposition type surface treatment liquid in the immersion step is from room temperature to 30 ° C. In the process, the temperature of the deposition type surface treatment liquid is set to 100 to 18
The method of claim 9, wherein the permanent magnet is heated to 0 ° C. 14. The rare earth / iron sintered permanent magnet according to claim 9, wherein the deposition type surface treatment liquid is the deposition type surface treatment liquid according to any one of claims 5 to 7. Surface treatment method. 15. The liquid temperature of the deposition type surface treatment liquid in the immersion step is from room temperature to 30 ° C., and the liquid temperature of the deposition type surface treatment liquid is heated to 40 ° C. to 90 ° C. in the deposition step. The surface treatment method for a rare-earth / iron-based sintered permanent magnet according to claim 14. 16. The surface treatment method for a rare-earth / iron-based sintered permanent magnet according to claim 14, wherein, in the deposition step, a water-soluble polar solvent is added to the deposition-type surface treatment liquid. 17. The method according to claim 9, further comprising a drying step after the depositing step. 18. The method according to claim 18, further comprising, after the depositing step, an applying step of applying at least one resin paint selected from the group consisting of an epoxy resin, a phenol resin, an acrylic resin, a urethane resin, and a polyester resin. The surface treatment method for a rare earth / iron-based sintered permanent magnet according to any one of claims 9 to 17. 19. A rare-earth / iron-based sintered permanent magnet, wherein a deposited layer is formed on the surface by the method for surface-treating a rare-earth / iron-based sintered permanent magnet according to any one of claims 9 to 18. magnet. 20. amount of deposition of the metal elements, rare earth-iron-based sintered according to claim 19, characterized in that in total in terms of a single respective element is 0.5mg / m ² ~500mg / m ² Permanent magnet.