JP2005210135A - Bonded structure and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bonded structure using a magnet adapted to enable the effective elimination of the defective solidification of an adhesive material that is chemically inactive with respect to a nickel plated coating, reduce variations in adhesion strength but obtain large adhesive strength and also obtain high efficiency in adhesion-bonding work. <P>SOLUTION: The magnet 2 has an R-TM-B-based rare earth magnet body 4 that contains R, TM and B wherein the R denotes at least one of rare earth elements including Y and TM denotes transition elements, containing Fe as a base component; a protective film 6 made of a nickel coat film formed on the surface of the magnet body; and a phosphate coated film 8 thinner than 0.1 μm in thickness formed on the surface of the protective film subjected to phosphate treatment using a processing liquid that does not contain fluoride. The adhesively bonded structure is constructed by bonding an iron member to the side of the phosphate coated film 8 of the magnet 2 with an adhesive. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a bonded structure in which a magnet and an iron member are bonded via an adhesive, a method for manufacturing the bonded structure, and a rotating device and an optical pickup device in which the bonded structure is incorporated.

  Nd-Fe-B magnets have high magnetic properties, abundant and inexpensive Fe as the main material, Nd as a rare earth is more advantageous and cheaper than Sm, and supply is unstable In recent years, rare earth magnets have become the mainstream in place of Sm—Co based magnets because they do not use expensive Co.

  Since Nd—Fe—B magnets have the disadvantage that they are very susceptible to corrosion when used as they are, they have been subjected to various surface treatments.

  Nickel plating that is inexpensive and excellent in corrosion resistance is widely used for rust prevention treatment of Nd—Fe—B magnets. And it fixes and uses another member via the adhesive agent on the nickel plating of the magnet surface. Epoxy adhesives and anaerobic acrylic adhesives are often used for this type of adhesive, and especially anaerobic acrylic adhesives have good workability and low thermal demagnetization due to low curing temperature. Therefore, it is often selected.

  However, anaerobic acrylic adhesives are highly active against iron and copper, and as a result, react quickly, whereas when the adherend is nickel, there is a drawback that the reactivity is poor. When adhering reaction-inactive adherends such as nickel, the adhesive surface is treated with an activator (primer), but in the case of small shapes, the workability is significantly reduced and the advantages of anaerobic acrylic adhesives In addition to not being able to make the most of it, it has been a factor in increasing costs in the bonding process.

  By the way, zinc phosphate treatment has been widely adopted as a coating base treatment for steel and aluminum. It is known that when zinc phosphate treatment is applied to steel or aluminum, phosphate crystals are deposited on the surface of the steel or aluminum as a film, thereby improving the adhesion of the paint film.

  However, when the technology used for the coating surface treatment of steel and aluminum is applied to nickel plating as it is, it does not react sufficiently in the treatment solution due to the excellent corrosion resistance of nickel, and phosphate crystals are not formed. It did not precipitate on the surface.

  In Patent Document 1, the surface of the nickel plating film formed on the surface of the Nd—Fe—B magnet main body is activated in advance using an acid containing fluoride, and then zinc phosphate further containing fluoride. A method of forming a zinc phosphate coating having a thickness of 0.1 to 10 μm on the surface of the nickel plating film by treating with a solution, and improving the adhesion of the nickel plating film surface by the effect of such a zinc phosphate coating Is disclosed. Here, since the fluoride forcibly dissolves and activates the surface of the nickel plating, crystals of zinc phosphate are formed as a film on the nickel plating, and the adhesive strength is improved.

However, according to the method described in Patent Document 1, the adhesive strength may vary greatly depending on the state of pretreatment (activation treatment) with an acid containing fluoride, and it is difficult to control the thickness of the zinc phosphate coating. It was difficult to obtain a stable adhesive strength at the production level. For this reason, development of the technique which can obtain the stable adhesive strength at the production level and can realize the efficiency of the bonding operation has been desired.
JP-A-6-318512

  The purpose of the present invention is to effectively eliminate the curing failure of a reaction-inactive adhesive with respect to the nickel plating film, to reduce the adhesive strength variation, and to obtain a large adhesive strength, and to improve the efficiency of the bonding operation. It is providing the joining structure using the magnet which can implement | achieve, and its manufacturing method, and the rotating apparatus and optical pick-up apparatus in which this joining structure was incorporated.

The present inventors perform a phosphate treatment on the surface of the nickel plating film formed on the surface of the magnet main body using a treatment liquid having a specific composition, thereby forming a phosphate film formed on the surface of the nickel plating film. As a result, it was found that the adhesion of the nickel plating film surface can be stably improved at the production level, and that the efficiency of the bonding operation can be realized, and the present invention has been completed.
A bonded structure according to the present invention includes a magnet body containing a rare earth element, a protective film made of a nickel plating film formed on the surface of the magnet body, and a thickness of less than 0.1 μm formed on the surface of the protective film. An iron member is bonded to the phosphate coating side of the magnet having a phosphate coating having an adhesive via an adhesive.

A method of manufacturing a magnet used for a bonded structure according to the present invention includes a step of performing electroplating on the surface of a magnet body containing a rare earth element to form a protective film made of a nickel plating film,
Forming a phosphate coating on the surface of the protective film by performing a phosphate treatment using a treatment liquid not containing fluoride.

  Preferably, the pH of the treatment liquid is 4 or less.

  Preferably, the treatment temperature of the phosphate treatment is 20 to 50 ° C.

  Preferably, the treatment liquid contains nitrate ions at a rate of 2 to 30 g / l.

  Preferably, before forming the protective film, the surface of the magnet body is degreased using an alkaline solution and subjected to chemical etching with an acid to clean the surface of the magnet body. Have

  Preferably, the method includes a second pretreatment step in which the surface of the protective film is degreased using an alkaline solution and washed before the phosphate coating is formed.

  Since NaOH as an example of alkali is inexpensive, easily available, and has a high degreasing effect, it is preferable to use an alkaline solution containing this as a main component.

  Preferably, after the phosphate coating is formed, the magnet body is immersed in alcohol and air-dried.

The magnet used in the joint structure according to the present invention includes a magnet body containing a rare earth element,
A protective film made of a nickel plating film formed on the surface of the magnet body;
And a phosphate film having a thickness of less than 0.1 μm formed on the surface of the protective film.

  Preferably, the phosphate coating is formed by phosphating using a treatment liquid not containing fluoride.

  Preferably, it further has an underlayer mainly composed of copper formed between the magnet body and the protective film.

Common Items Examples of the phosphate include tin phosphate, iron phosphate, manganese phosphate, zinc phosphate, and zinc calcium phosphate.

  The magnet body is not particularly limited as long as it contains a rare earth element in the present invention, but R (where R is one or more of rare earth elements including Y), TM (where TM is a transition mainly composed of Fe). The effect is particularly great in the case of an R-TM-B rare earth magnet containing (element) and B. A typical example of the R-TM-B rare earth magnet is an Nd-Fe-B rare earth magnet.

In the magnet used for the bonded structure according to the present invention, the internal stress applied to the phosphate coating is reduced by forming the phosphate coating as very thin as less than 0.1 μm on the surface of the protective film made of a nickel plating film. Can be small. For this reason, even if various adhesives, such as an anaerobic acrylic adhesive, are adhered to the ultrathin phosphate coating, there is very little possibility that the phosphate coating is destroyed. On the other hand, even if the thickness of the phosphate coating is less than 0.1 μm, it can be expected that the coating is uniformly formed without being broken and a stable adhesive strength is obtained.
That is, in the bonded structure according to the present invention, by forming the thickness of the phosphate coating extremely thin, it prevents destruction due to internal stress of the phosphate coating and ensures uniform thickness, and as a result, Curing inhibition of various adhesives that are inactive to the nickel plating film (for example, anaerobic acrylic adhesives) can be effectively suppressed, and the efficiency of the bonding operation can be realized.

  In the manufacturing method of the magnet used for the joined structure according to the present invention, when forming the phosphate coating on the surface of the protective film made of a nickel plating film formed on the surface of the magnet body containing the rare earth element, fluoride is used. Phosphate treatment is performed using a treatment solution not contained. For this reason, it becomes easy to control the thickness of the phosphate coating, and a phosphate coating having a thickness of less than 0.1 μm can be stably formed at the production level.

  Although the joining structure of the present invention using the magnet is not particularly limited, it is used by being incorporated in various industrial rotating devices, consumer rotating devices, optical pickup devices and the like.

  Examples of industrial rotating equipment include various motors used in automobiles, motorcycles, etc .; drive systems for machine tools, and the like. Examples of consumer rotating devices include various motors used for VTRs, CDs, MDs, DVDs, cassette stereos, and the like; motors for OA devices (computers, printers, copiers, etc.), and the like.

  An optical pickup device is for recording and reproducing information on an optical disk as a recording medium. In general, an optical pickup device moves an objective lens in a tracking direction or a focus direction of the optical disc, and a light source or a light receiving device on a mounting base. And an optical system block for projecting laser light onto the optical disc via the objective lens and detecting the reflected light. When the bonding structure of the present invention using the magnet is incorporated in an optical pickup device, the bonding structure of the present invention using the magnet is used in a magnetic circuit that is a constituent member of the objective lens driving device.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
FIG. 1 is a schematic cross-sectional view showing a permanent magnet according to an embodiment of a magnet used in the bonded structure of the present invention, and FIG. 2 shows the hardening of each permanent magnet sample of Example 1, Comparative Example 1 and Comparative Example 5. It is a graph which shows the relationship between time and adhesive strength.

The joining structure according to the present invention is configured by joining a magnet and an iron member (such as an iron plate) via an adhesive (such as an anaerobic acrylic adhesive), and various industrial rotating devices, consumer rotating devices, optical Used in a pickup device or the like.
In the present embodiment, the permanent magnet 2 shown in FIG. 1 will be described as an example of the magnet.
permanent magnet
As shown in FIG. 1, the permanent magnet 2 according to this embodiment has a protective film 6 formed on the surface of a magnet body 4. A phosphate film 8 is formed on the surface of the protective film 6.

In this embodiment, the magnet body 4 is an R-TM containing R (where R is one or more of rare earth elements including Y), TM (where TM is a transition element mainly composed of Fe), and B. -B type rare earth magnet.

  The contents of R, TM and B are preferably 5.5 atomic% ≦ R ≦ 30 atomic%, 42 atomic% ≦ TM ≦ 90 atomic%, 2 atomic% ≦ B ≦ 28 atomic%.

  The rare earth element R includes at least one of Nd, Pr, Ho, and Tb, or further includes one or more of La, Sm, Ce, Gd, Er, Eu, Pm, Tm, Yb, and Y. preferable.

  In addition, when using 2 or more types of elements as R, mixtures, such as a misch metal, can also be used as a raw material.

  The content of R is preferably 5.5 to 30 atomic%. If the R content is too low, the crystal structure of the magnet becomes a cubic structure having the same structure as that of α-iron, so that a high coercive force (iHc) cannot be obtained. The residual magnetic flux density (Br) is decreased.

  The TM content is preferably 42 to 90 atomic%. If the TM content is too low, Br decreases, and if it is too high, iHc decreases. Note that by replacing part of Fe with Co, the temperature characteristics can be improved without deteriorating the magnetic characteristics. In this case, if the Co substitution amount exceeds 50% of Fe, the magnetic properties deteriorate, so the Co substitution amount is preferably 50% or less.

  The content of B is preferably 2 to 28 atomic%. If the B content is too small, the crystal structure of the magnet has a rhombohedral structure, so iHc is insufficient, and if it is too large, the B-rich nonmagnetic phase increases, so Br decreases.

  In addition to R, TM and B, Ni, Si, Al, Cu, Ca, etc. may be contained as unavoidable impurities in an amount of 3 atomic% or less.

  Furthermore, by replacing a part of B with one or more of C, P, S, and Cu, productivity can be improved and cost can be reduced. In this case, the amount of substitution is preferably 4 atomic% or less. In addition, Al, Ti, V, Cr, Mn, Bi, Nb, Ta, Mo, W, Sb, Ge, Sn, Zr, Ni, Si are used to improve coercive force, improve productivity, and reduce costs. , Hf or the like may be added. In this case, the total amount added is preferably 10 atomic% or less.

  The magnet body 4 in this embodiment has a main phase with a substantially tetragonal crystal structure. The particle size of the main phase is preferably about 1 to 100 μm. And it usually contains 1-50% nonmagnetic phase by volume ratio.

The protective film protective film 6 is composed of a plating film formed by electroplating. The plating film preferably contains nickel as a main component. By using nickel as a main component, the strength of the protective film 6 can be increased and an excellent antirust effect can be exhibited.

  As the protective film 6, rack plating or barrel plating is appropriately selected according to the size and shape of the magnet body 4. Since the protective film 6 made of a nickel plating film formed by electroplating needs to be defect-free in order to obtain excellent corrosion resistance, the thickness T1 of the protective film 6 is preferably 10 to 30 μm, more preferably Is about 10 to 20 μm.

  Note that the adhesiveness does not change significantly depending on the type of nickel plating film constituting the protective film 6. However, in order to reduce the concentration of stress applied to the interface between the magnet body 4 and the protective film 6 and increase the adhesive strength, an underlayer (not shown) is further provided between the magnet body 4 and the protective film 6. It is preferable to have. The underlayer preferably contains Cu as a main component. When such a base layer is provided, when a load is applied to the magnet body after bonding, there is a function of suppressing stress concentration at one place on the interface with the magnet body because Cu is soft, Adhesive strength is improved. The thickness of the underlayer is not particularly limited, but is preferably about 5 to 10 μm.

Phosphate coating The phosphate coating 8 is formed by phosphating. In this embodiment, the thickness T2 of the phosphate coating 8 is less than 0.1 μm, preferably 0.01 μm or less. When the phosphate is laminated thickly, the internal stress applied to the phosphate coating 8 increases, and when the adhesion test is performed, the phosphate coating 8 is easily broken. Depending on the curing conditions of the adhesive, the crystal water of the phosphate may evaporate, and the phosphate coating 8 may be cracked. By setting the thickness T2 of the coating 8 to less than 0.1 μm, the phosphate coating 8 becomes a level that cannot be observed with a microscope as a crystal structure, and the defects that have occurred in the thick coating are eliminated.

  The effect of improving the adhesive strength exerted by the phosphate coating 8, particularly the improvement of the curability for the anaerobic acrylic adhesive, is manifested when the phosphate coating 8 exists on the surface of the protective film 6. The lower limit of the thickness T2 of the coating 8 is about 0.001 μm, preferably about 0.005 μm.

Method for Manufacturing Permanent Magnet Next, an example of a method for manufacturing the permanent magnet 2 according to the present embodiment will be described.

  (1) First, a magnet body is manufactured. For the production of the magnet body 4, it is preferable to use a powder metallurgy method. Manufacture of the magnet body 4 by the powder metallurgy method is performed as follows.

First, an alloy having a desired composition is produced using various alloy manufacturing processes such as a casting method and a strip casting method. Next, the obtained alloy is coarsely pulverized to a particle size of about 10 to 100 μm using a coarse pulverizer such as a jaw crusher, brown mill, stamp mill, etc. Finely pulverize to a particle size of about 5-5 μm. The resulting powder is then preferably molded in a magnetic field. The magnetic field strength at the time of molding is preferably 600 kA / m or more. The molding pressure is preferably about 0.5 to ⁵ ton / cm ² . Next, the obtained molded body is sintered at 1000 to 1200 ° C. for 0.5 to 10 hours and rapidly cooled. The atmosphere during sintering is preferably an inert gas such as Ar gas. Thereafter, heat treatment (aging treatment) is preferably performed in an inert gas atmosphere at 500 to 900 ° C. for 1 to 5 hours.

  It is known that the manufactured magnet body 4 is excellent in magnetic characteristics particularly when R is Nd, but has a negative expansion coefficient in a direction perpendicular to the C axis.

  (2) Next, after degreasing the surface of the obtained magnet body 4, chemical etching with an acid is performed to clean the surface of the magnet body 4 (first pretreatment). Although this first pretreatment is an arbitrary treatment in the present invention, there is an advantage that the surface of the magnet body 4 can be removed by performing the degreasing treatment, and the protective film 6 can be reliably formed. In addition, in order to remove the burr | flash etc. of the surface of the magnet main body 4 before a degreasing process, you may perform barrel grinding | polishing.

  The degreasing liquid used in the degreasing treatment is not particularly limited as long as it is used for ordinary steel. Generally, NaOH is the main component and other additives are not specified.

  Nitric acid is preferably used as the acid used in the chemical etching. When plating a general steel material, non-oxidizing acids such as hydrochloric acid and sulfuric acid are often used. However, as in the case of the magnet body 4 in the present embodiment, when the magnet body contains a rare earth element, when the treatment is performed using these acids, hydrogen generated by the acid is occluded on the surface of the magnet body, The occlusion site becomes brittle and a large amount of powdery undissolved material is generated. Since this powdery undissolved material causes surface roughness, defects and poor adhesion after the surface treatment, it is preferable not to include the above-described non-oxidizing acid in the chemical etching treatment solution. Therefore, it is preferable to use nitric acid, which is an oxidizing acid with little generation of hydrogen, and further, aldonic acid or a salt thereof is contained at the same time, and irregularities at a level that cannot be visually confirmed are formed on the surface. This is even more preferable since the adhesive strength of the is improved. Such an improvement in adhesion is selectively realized by aldonic acid or a salt thereof, but not by other organic acids such as citric acid or tartaric acid.

  The amount of dissolution of the surface of the magnet body 4 by such pretreatment is preferably 5 μm or more, preferably 10 to 15 μm in average thickness from the surface. If the dissolved amount is too small, the deteriorated layer and the oxidized layer due to the processing of the surface of the magnet main body cannot be completely removed, so that the protective film 6 described later is not normally formed on the surface of the magnet main body 4 and deteriorates the corrosion resistance. End up.

  The concentration of nitric acid in the treatment liquid used for the pretreatment is preferably 1 N or less, particularly preferably 0.5 N or less. If the nitric acid concentration is too high, the dissolution rate of the magnet body 4 is extremely fast, and it becomes difficult to control the amount of dissolution. In particular, the dispersion becomes large in large-scale processing such as barrel processing, and the dimensional accuracy of the product cannot be maintained. If the nitric acid concentration is too low, the amount of dissolution becomes insufficient. For this reason, the nitric acid concentration is desirably 1 N or less, particularly 0.5 to 0.05 N or less. The amount of Fe dissolved at the end of the treatment is about 1 to 10 g / l.

  In order to completely remove a small amount of undissolved substances and residual acid components from the surface of the magnet body 4 that has been subjected to pretreatment, it is preferable to perform cleaning using ultrasonic waves. This ultrasonic cleaning is preferably performed in ion-exchanged water with very few chlorine ions that generate rust on the surface of the magnet body 4. Moreover, you may perform the same water washing before and behind the ultrasonic cleaning, and in each process of the said pre-processing as needed.

  (3) Next, a protective film 6 is formed by electroplating on the surface of the magnet body 4 that has been pretreated. By forming the protective film 6 using an electroplating method, the protective film 6 that is a high-performance corrosion-resistant film can be formed at a low cost. Examples of plating baths used for Ni electroplating include Watts baths that do not contain nickel chloride (that is, nickel sulfate and boric acid as main components), sulfamic acid baths, borofluoride baths, nickel bromide baths, and the like. However, in this case, since dissolution of the anode is reduced, it is preferable to replenish the bath with nickel ions. The nickel ions are preferably replenished as a solution of nickel sulfate or nickel bromide.

  In addition, before forming the protective film 6 on the surface of the magnet body 4 after the pretreatment, for example, when forming an underlayer (not shown) containing Cu as a main component, the surface of the magnet body 4 In order to prevent substitutional precipitation of Cu, it is preferable to perform the treatment in a weak alkaline bath having a pH of 7 to 10. In the case of forming a base layer containing Cu as a main component, the nickel plating bath described above is not limited to the above-described examples, and the protective film 6 made of a nickel plating film is formed in a bath containing nickel chloride. However, it does not impair the corrosion resistance. That is, in this case, the protective film 6 may be formed using a bath containing nickel chloride.

  (4) Next, after degreasing the surface of the protective film 6, the surface is sufficiently cleaned with pure water (second pretreatment). This second pretreatment is also an optional treatment in the present invention, but by performing a degreasing treatment, dirt (organic matter such as a brightener) attached to the surface of the protective film 6 can be removed, and the phosphate coating 8 is surely formed. There is a merit that can be formed.

  The degreasing solution used in the degreasing treatment is not particularly limited as long as it can remove organic substances, but the use of an alkaline solution is most effective and preferable. The alkaline solution is not particularly limited as long as it contains NaOH as a main component and is used for ordinary steel.

  (5) Next, a phosphate treatment is performed on the surface of the protective film 6 to form a phosphate coating 8. Specifically, the magnet body 4 on which the protective film 6 is formed is immersed in a phosphate bath adjusted to a predetermined concentration and temperature to form a phosphate coating 8 on the surface of the protective film 6.

  Examples of the treatment liquid used for the phosphate treatment include a tin phosphate treatment liquid, an iron phosphate treatment liquid, a manganese phosphate treatment liquid, a zinc phosphate treatment liquid, and a zinc calcium phosphate treatment liquid. If any of these treatment solutions is used, an adhesion effect is imparted to the protective film 6 made of a nickel plating film. Although it does not specifically limit as a component of the zinc phosphate process liquid as an example in these, A zinc ion, a phosphate ion, nitrate ion etc. are illustrated. Preferred concentrations of each of these ions are zinc ion: 0.4 to 3.0 g / l, particularly 0.5 to 2.0 g / l, phosphate ion: 5 to 40 g / l, particularly 7 to 30 g / l, nitric acid Ions: 2-30 g / l, especially 2-10 g / l.

  If the zinc ion concentration is too low, there is a tendency that a uniform phosphate coating 8 cannot be formed on the surface of the protective film 6. On the other hand, if the zinc ion concentration is too high, the thickness T2 of the phosphate coating 8 tends to be too thick and the adhesive strength tends to be insufficient.

  If the phosphate ion concentration is too low, there is a tendency that a uniform phosphate coating 8 cannot be formed. On the other hand, if the phosphate ion concentration is too high, the formation effect of the phosphate coating 8 cannot be expected.

  The nitrate ions are added as an accelerator for forming the phosphate coating 8 on the protective film 6 made of a nickel plating film. If the nitrate ion concentration is too low, dissolution of the protective film 6 made of a nickel plating film hardly occurs, so that there is a tendency that the phosphate coating 8 cannot be formed on the surface of the protective film 6. On the other hand, when the nitrate ion concentration is too high, not only a film forming effect can be expected, but also nickel passivation is promoted and the formation of the phosphate film 8 tends to be inhibited.

  Other phosphate treatment solutions, that is, manganese phosphate, iron phosphate, calcium calcium phosphate, and the like can be treated in the same manner as zinc phosphate.

  In the case of treating aluminum with zinc phosphate, peroxides and fluorides are used as film formation accelerators, but the Ni surface may be too rough and the adhesive strength may be lowered. For this reason, it is preferable to use nitrate ions whose reaction proceeds relatively slowly.

  The pH of the treatment liquid is preferably 4 or less. If the pH of the treatment liquid is too high, zinc phosphate cannot be dissolved in the treatment liquid, the form of phosphate changes, sludges and precipitates in the solution, so the surface of the protective film 6 made of a nickel plating film This is because there is a tendency that a phosphate film is not formed. If the pH of the treatment solution is too low, the formation of the phosphate coating 8 is hindered, and the protective film 6 made of a nickel plating film may be eroded and the moisture resistance may be impaired. Therefore, the lower limit is preferably 2.

  The treatment temperature in the bath composition in the above range is not particularly limited because it does not cause any problem in the adhesiveness obtained even under conditions performed with ordinary steel. However, when the treatment temperature is too low, the reaction in the treatment liquid is poor and the processability tends to decrease. On the other hand, if the treatment temperature is too high, spots or the like may occur and the aesthetic appearance may be impaired. Therefore, the treatment temperature is preferably 20 to 50 ° C, more preferably 30 to 50 ° C.

  The treatment time in the above range of the bath composition is preferably 3 to 30 minutes, more preferably 5 to 15 minutes. If the treatment time is too short, the treatment liquid does not sufficiently contact the surface of the protective film 6, and the reaction becomes insufficient, and there is a tendency that the uniform phosphate coating 8 cannot be formed. On the other hand, when the treatment time is too long, the thickness T2 of the phosphate coating 8 becomes 0.1 μm or more, and the adhesive strength tends to decrease. That is, by setting the processing time within a specific range, the phosphate coating 8 having a thickness of less than 0.1 μm can be stably formed at the production level.

  (6) Next, it is washed with pure water and dried. At this time, drying is usually carried out at 80 to 150 ° C. to remove moisture on the surface, but it is also preferable to immerse in alcohol and air dry for simplification of the process. Since the phosphate coating 8 formed on the surface of the protective film 6 is a coating that cannot be observed with a microscope, if the moisture has been removed to some extent, moisture evaporation during drying (including crystal water) ) Film cracks and the like hardly occur.

  (7) By passing through the above process, the permanent magnet 2 which concerns on this embodiment shown in FIG. 1 is manufactured.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, it can implement in a various aspect in the range which does not deviate from the summary of this invention. is there.

  Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples.

Example 1
An ingot made of powder metallurgy and having a composition of 14.7Nd-79.2Fe-6.1B (numbers are in atomic ratio) is coarsely pulverized, and further subjected to jet mill pulverization with an inert gas to obtain an average particle size of about A fine powder of 3.5 μm was obtained. The obtained fine powder was magnetically molded, sintered, and heat-treated to obtain a sintered body. The obtained sintered body was cut out to a size of 10 mm × 20 mm × thickness 5 mm, and further chamfered by barrel polishing to obtain a permanent magnet body.

  Next, after washing the sample of the permanent magnet body with an alkaline degreasing solution, an electrolytic nickel plating was performed through an etching process, and a protective film made of an electrical nickel plating film was formed on the surface of the permanent magnet body. The thickness of the protective film made of an electric nickel plating film was 15 μm.

  Next, the permanent magnet body on which the protective film was formed was degreased with an alkaline solution (Endox Q-576S manufactured by Meltex Co., Ltd.), and then washed with pure water.

Subsequently, the phosphate (zinc phosphate) process was performed using the processing liquid which does not contain the fluoride of the composition shown below.
Zinc ion: 1.0 g / l,
Phosphate ion: 15.0 g / l,
Nitrate ion: 3.2 g / l,
Processing temperature: 50 ° C.
Immersion time: 5 minutes.

  After soaking, it was washed with pure water and dried at 100 ° C. for 10 minutes to obtain a permanent magnet sample. When the film thickness of the zinc phosphate coating was observed with an SEM (Scanning Electron Microscope), it was less than 0.1 μm.

Example 2
A permanent magnet sample was obtained in the same manner as in Example 1 except that the immersion time in the treatment solution in the phosphate treatment was 30 minutes. When the film thickness of the zinc phosphate coating was observed by SEM, it was less than 0.1 μm as in Example 1.

Example 3
A permanent magnet sample was obtained in the same manner as in Example 1 except that a phosphate (manganese phosphate) treatment was performed using the treatment liquid shown below. When the film thickness of the manganese phosphate coating was observed by SEM, it was less than 0.1 μm as in Example 1.

Manganese ion: 1.2 g / l,
Iron ion: 0.3 g / l,
Phosphate ion: 16.0 g / l,
Nitrate ion: 4.0 g / l.

Example 4
A permanent magnet sample was obtained in the same manner as in Example 1 except that a phosphate (zinc calcium phosphate) treatment was performed using the treatment liquid shown below. When the film thickness of the zinc calcium phosphate coating was observed by SEM, it was less than 0.1 μm as in Example 1.

Zinc ion: 1.0 g / l,
Calcium ion: 0.3 g / l,
Phosphate ion: 14.0 g / l
Nitrate ion: 3.0 g / l.

Comparative Example 1
A permanent magnet sample was obtained in the same manner as in Example 1 except that the zinc phosphate treatment was not performed.

Comparative Example 2
Permanent in the same manner as in Example 1 except that the zinc phosphate treatment was performed using a treatment solution comprising an acid containing fluoride (Nippon Magdermid Co., Ltd., Metex Acid Salt M-629, 120 g / l). A magnet sample was obtained. It was 3 micrometers when the film thickness of the zinc phosphate coating was computed by observing a cross section using an electron microscope.

Comparative Example 3
A permanent magnet sample was obtained in the same manner as in Example 1 except that the zinc phosphate treatment was performed using the treatment liquid shown below. When the film thickness of the zinc phosphate coating was calculated in the same manner as in Comparative Example 2, it was 8 μm.

Zinc ion: 1.0 g / l,
Phosphate ion: 15.0 g / l,
Nitrate ion: 3.2 g / l,
Silicohydrofluoric acid: 2.0 g / l.

Comparative Example 4
A permanent magnet sample was obtained in the same manner as in Example 1 except that the zinc phosphate treatment was performed using the treatment liquid shown below. When the film thickness of the zinc phosphate coating was calculated in the same manner as in Comparative Example 2, it was 12 μm.

Zinc ion: 1.0 g / l,
Phosphate ion: 15.0 g / l,
Nitrate ion: 3.2 g / l,
Hydrosilicofluoric acid: 5.0 g / l.

Comparative Example 5
A protective film made of a nickel plating film was alkali degreased and then immersed in a 20 g / l chromic anhydride solution at 40 ° C. for 10 minutes to form a chromate film on the surface of the protective film, as in Example 1. Thus, a permanent magnet sample was obtained. When the film thickness of the chromate film was calculated in the same manner as in Comparative Example 2, it was 0.8 μm.

Evaluation method In order to compare the zinc phosphate coating and the adhesive strength, the following tests were conducted. About 0.008-0.010g of anaerobic acrylic adhesive (Loctite 638UV) was applied to the surface of the zinc phosphate coating of each permanent magnet sample obtained in Examples 1-4 and Comparative Examples 1-5. Then, after pressure-bonding to the iron plate whose surface was washed, it was put into a dryer heated to 100 ° C. for 30 minutes and then subjected to a compression shear test. The number of samples was 10 each, and the average value was taken as the adhesive strength. The compression shear test was performed at a rate of 5 mm / min at room temperature. The results are shown in Table 1.

  In order to compare the curing time and the adhesive strength, the following tests were performed. About 0.002-0.003g of anaerobic acrylic adhesive (Loctite 638UV) was applied to the surface of the zinc phosphate coating of each permanent magnet sample obtained in Example 1 and Comparative Examples 1 and 5. After pressure bonding to the iron plate whose surface was cleaned, it was put into a dryer preheated to 100 ° C. for 3 minutes, 5 minutes, 10 minutes, and 15 minutes, and a compression shear test was conducted within 1 minute after removal. In this test, the sample shape was 10 mm × 5 mm × thickness 5 mm, and the strength was measured with a hand press. The results are shown in Table 2 and FIG.

As shown in Table 1, in the magnet samples of Examples 1 to 4 in which the zinc phosphate coating film thickness is less than 0.1 μm, the adhesive strength is remarkably higher than that of the magnet samples of Comparative Examples 1 to 5. It was confirmed that it was excellent and the variation was small.

  As shown in Table 2 and FIG. 2, it was confirmed that the magnet sample of Example 1 can obtain a predetermined adhesive strength in a very short time as compared with the magnet samples of Comparative Examples 1 and 5.

FIG. 1 is a schematic cross-sectional view showing a permanent magnet according to an embodiment of a magnet used in the bonded structure of the present invention. FIG. 2 is a graph showing the relationship between curing time and adhesive strength for each of the permanent magnet samples of Example 1, Comparative Example 1 and Comparative Example 5.

Explanation of symbols

2 ... Permanent magnet 4 ... Magnet body 6 ... Protective film made of nickel plating film 8 ... Phosphate coating

Claims (15)

A magnet body including a rare earth element; a protective film made of a nickel plating film formed on a surface of the magnet body; and a phosphate film having a thickness of less than 0.1 μm formed on the surface of the protective film. A joined structure in which an iron member is joined to the phosphate coating side of the magnet via an adhesive. The joining structure according to claim 1, wherein the phosphate coating is formed by a phosphate treatment using a treatment liquid not containing fluoride. The joining structure according to claim 1 or 2, wherein the adhesive is an anaerobic acrylic adhesive. The joining structure according to any one of claims 1 to 3, further comprising an underlayer mainly composed of copper between the magnet body and the protective film. The magnet body is an R-TM-B rare earth magnet containing R (where R is one or more of rare earth elements including Y), TM (where TM is a transition element mainly composed of Fe), and B. The joining structure according to any one of claims 1 to 4. The bonded structure according to claim 2, wherein the treatment liquid has a pH of 4 or less, and the phosphate treatment has a treatment temperature of 20 to 50 ° C. 4. The bonded structure according to claim 2, wherein the treatment liquid contains nitrate ions at a rate of 2 to 30 g / l. A rotating device in which the joint structure according to claim 1 is incorporated. An optical pickup device in which the joining structure according to claim 1 is incorporated. The phosphate coating side of a magnet in which a protective film made of a nickel plating film is formed on the surface of a magnet body containing a rare earth element, and a phosphate coating having a thickness of less than 0.1 μm is formed on the surface of the protective film In addition, a method for manufacturing a bonded structure in which an iron member is bonded via an adhesive,
Forming a protective film made of a nickel plating film by electroplating the surface of the magnet main body containing the rare earth element;
The surface of the protective film is subjected to a phosphate treatment using a treatment liquid not containing fluoride to form a phosphate coating, thereby manufacturing the magnet. Manufacturing method. The method for manufacturing a joined structure according to claim 10, wherein the phosphate treatment is any one of tin phosphate treatment, iron phosphate treatment, manganese phosphate treatment, zinc phosphate treatment, and zinc calcium phosphate treatment. . 11. The method for manufacturing a joined structure according to claim 10, wherein a pH of the treatment liquid is 4 or less, and a treatment temperature of the phosphate treatment is 20 to 50 ° C. 11. The method for manufacturing a joined structure according to claim 10, wherein the treatment liquid contains nitrate ions at a rate of 2 to 30 g / l. Before forming the protective film, the surface of the magnet main body is degreased using an alkaline solution, subjected to chemical etching with an acid, and has a first pretreatment step for cleaning the surface of the magnet main body. Item 11. A method for manufacturing a joined structure according to Item 10. The manufacturing method of the joining structure of Claim 10 which has a 2nd pre-processing process which degreases and cleans the surface of the said protective film using an alkaline solution before forming the said phosphate film.

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