JP2006176698A - Magnetic abrasive grain, its manufacturing method, electroless plating method and electroless plating activator for activated carbon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic abrasive grain which enables precise surface processing, is lightweight, excellent in abrasive performance and inexpensive, and its manufacturing method. <P>SOLUTION: The above problem is solved by the magnetic abrasive grain having a nickel-containing electroless plating layer that has magnetism formed on particles of activated carbon. This magnetic abrasive grain can be manufactured by immersing the activated carbon particles into a NiSO<SB>4</SB>/picolinic acid solution, then heating and drying them under an inert atmosphere, reducing the chelated anions of the picolinic acid and nickel that have adhered to the activated carbon particles into nickel metal and also carbonizing the picolinic acid, thus forming nickel metal element on the activated carbon particles, thereby performing the activation of the activated carbon particles, and then conducting nickel-containing electroless plating. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic abrasive grain used for a magnetic polishing method, a manufacturing method thereof, an electroless plating method, and an electroless plating activator for activated carbon.

  The magnetic polishing method is a precision processing method for polishing the surface of a workpiece by moving abrasive grains having a polishing action by the action of a magnetic field. This magnetic polishing method is a method that enables polishing of parts that are difficult with conventional machining, such as the surface of a part having a complicated shape, the inner surface of a hole that does not receive a tool, the inner surface of a tube that does not reach the tool, etc. Part of the polishing has been put to practical use.

  In the magnetic polishing method, magnetic polishing abrasive grains (hereinafter referred to as magnetic abrasive grains) used for this are extremely important in order to ensure finishing quality and finishing accuracy.

Conventionally, magnetic abrasive grains comprising magnetic grains and non-magnetic abrasive grains have been used. The non-magnetic abrasive is composed of, for example, Al ₂ O ₃ , SiC, ZrO ₂ , B ₄ C and diamond, cubic boron nitride, MgO, CeO ₂ or fumed silica, and is usually a cutting tool. It is used as. In addition, as a magnetic abrasive grain, the thing with which the magnetic grain and the abrasive grain are not couple | bonded, the thing couple | bonded lightly, or what is couple | bonded (this is called coupling | bonding magnetic abrasive grain) is used. be able to.

  As the bonded magnetic abrasive, aluminum oxide sintered with iron in an inert gas atmosphere at high temperature and high pressure (Non-patent Document 1), or generation of a thermite reaction between aluminum and iron oxide in an inert gas atmosphere A thing etc. can be illustrated typically. The types of commercially available bonded magnetic abrasive grains are limited due to their complex manufacturing processes.

  As magnetic particles used in the magnetic polishing method, iron particles that give a polishing force by a magnetic field are most widely used (Non-Patent Document 2). However, due to the corrosive nature of the iron particles and their softness, the surface finished with the magnetic abrasive containing the iron particles will require post-cleaning, which takes a lot of time, and In some ultra-precision magnetic polishing methods, the subsequent cleaning step becomes rate-limiting reaction. For this reason, other magnetic particles replacing such conventional iron particles have been urgently needed.

  Nickel is a magnetic material, and has attracted the attention of researchers because of its known corrosion resistance and hardness. Since nickel can be easily deposited by electrolytic plating or electroless plating, it attracts attention from researchers who are involved in the research area of magnetic polishing. In particular, electroless plating forms a thin metal film on the surface of the material to be plated, whether the material to be plated is a metal, an inert material, or a molded material. Therefore, it is used as a preferable plating method. Furthermore, electroless nickel composite plating is also a known technique.

Patent Document 1 reports magnetic abrasive grains in which an electroless nickel plating film containing abrasive particles such as diamond is formed on the surface of magnetic particles made of iron particles.
JP 2002-265933 A (Claim 3) Shinmura T., Takazawa K. and Hatano E. "Study on magnetic abrasive finishing", Ann. CIRP, vol. 39, No. 1, pp: 325-328 (1990) Yamaguchi H., Shinmura T and Kashiwagi R., “Internal finishing of austenitic stainless steel tube by a magnetic field assisted finishing process using a slurry circulation system”, Transactions of NAMRI / SME, volume 32, pp: 175-182, 2004.

  However, the magnetic abrasive grain described in Patent Document 1 described above is heavy and has a large polishing effect because most of the volume is occupied by magnetic particles having a high specific gravity, but when performing a more precise polishing process. Is not necessarily a preferable abrasive grain because the surface of the workpiece is polished more than necessary. In addition, as described above, since iron particles are used as the magnetic particles serving as the base material, the above-described problems of the corrosiveness and softness of the iron particles also occur.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a magnetic abrasive grain that is lightweight and capable of performing more precise surface polishing, and a method for manufacturing the same. Moreover, the electroless plating method and the electroless plating activator for activated carbon according to the present invention completed in the process of achieving this object are also provided.

  The magnetic abrasive grains of the present invention for achieving the above object are characterized in that a nickel-containing electroless plating layer having magnetism is formed on activated carbon particles.

  According to the present invention, the activated carbon particles are used as the base material, and the nickel-containing electroless plating layer as the magnetic layer is formed on the surface thereof. Magnetic abrasive grains having polishing ability are obtained.

  In the magnetic abrasive grains of the present invention, the nickel-containing electroless plating layer is an electroless nickel-boron plating layer or an electroless nickel-boron-diamond composite plating layer. According to this invention, the plating layer has excellent corrosion resistance, hardness, and the like, and the magnetic abrasive grains have better polishing ability.

In the method for producing magnetic abrasive grains according to the present invention, activated carbon particles are immersed in a NiSO ₄ / picolinic acid solution, and then the activated carbon particles are heated and dried in an inert atmosphere to form a nickel metal element on the activated carbon particles. The activated carbon particles are activated, and then nickel-containing electroless plating is performed to form a nickel-containing electroless plating layer having magnetism on the surface of the activated carbon particles.

According to the present invention, the activated carbon particles are immersed in a NiSO ₄ / picolinic acid solution, and then the activated carbon particles are heated and dried in an inert atmosphere, thereby chelating anions of picolinic acid and nickel attached to the activated carbon particles. Is reduced to nickel metal and picolinic acid is carbonized. The activated carbon particles are activated by the nickel metal element thus formed, and then a nickel-containing electroless plating layer having magnetism is formed on the surfaces of the activated carbon particles by the subsequent nickel-containing electroless plating. Therefore, according to this manufacturing method, magnetic abrasive grains having excellent characteristics as described above can be manufactured by a relatively simple method.

In addition, the electroless plating method of the present invention completed in the process of achieving the above object is to contact activated carbon with a NiSO ₄ / picolinic acid solution, and then heat dry the activated carbon in an inert atmosphere. The nickel metal element is formed on the activated carbon to activate the activated carbon, and then nickel-containing electroless plating is performed to form a nickel-containing electroless plating layer on the surface of the activated carbon. .

This invention was completed in the course of researching the method for producing magnetic abrasive grains according to the present invention. According to the present invention, as described above, activated carbon is immersed in a NiSO ₄ / picolinic acid solution, and then this activated carbon is heated and dried in an inert atmosphere, whereby a chelating anion of picolinic acid and nickel attached to the activated carbon is obtained. Is reduced to nickel metal and picolinic acid is carbonized. The activated carbon is activated by the nickel metal element thus formed, and a nickel-containing electroless plating layer having magnetism can be formed on the surface of the activated carbon by subsequent nickel-containing electroless plating.

Moreover, the electroless plating activator for activated carbon of the present invention completed in the process of achieving the above object is characterized by comprising a NiSO ₄ / picolinic acid solution.

According to this invention, if a NiSO ₄ / picolinic acid solution is applied as an electroless plating activator for activated carbon, an electroless plating layer can be formed on the activated carbon.

  As described above, according to the magnetic abrasive grains of the present invention and the manufacturing method thereof, magnetic abrasive grains that are lightweight and excellent in polishing performance can be obtained at low cost, and further, magnetic polishing is performed using the magnetic abrasive grains. Precision polishing by the method can be performed. For this reason, precision processing of the surface of a workpiece becomes possible, and a workpiece having a complicated shape can be easily processed.

  Moreover, according to the electroless plating method and the electroless plating activator for activated carbon of the present invention, an electroless plating, particularly a nickel-containing electroless plating layer can be easily formed on the activated carbon.

  Hereinafter, the magnetic abrasive grains and the production method thereof, the electroless plating method and the electroless plating activator for activated carbon of the present invention will be described in detail with reference to the drawings.

  The magnetic abrasive grain of the present invention is characterized in that a nickel-containing electroless plating layer having magnetism is formed on activated carbon particles.

  In the magnetic abrasive grains of the present invention, the plating layer is not only formed on the exposed surface of the activated carbon particles, but also in the pores. As a result, the activated carbon particles that are the base material firmly hold the plating layer. Due to such a so-called anchor effect, the activated carbon particles and the plating layer are bonded with high bonding strength, and the obtained magnetic abrasive grains have excellent mechanical strength.

In the magnetic abrasive grains of the present invention, the particulate activated carbon used as a base material is a porous carbonaceous material having a large specific surface area and adsorption capacity, as is well known. Activated charcoal is generally produced by fully carbonizing charcoal, coconut shells, coal char and other raw materials, and then activating them by high-temperature treatment with water vapor or impregnation with an aqueous solution such as zinc chloride and high-temperature firing. The specific surface area is 800 to 1200 m ² / g, the volume is 0.2 to ² cm ³ / g, and the pore diameter is about 1 to 4 nm.

In addition, although it does not specifically limit as activated carbon used as a base material in this invention, For example, a specific surface area is 800-1200 m < ² > / g, a volume is 0.2-2 cm < ³ > / g, and a pore diameter is 1. A thing of about ~ 4 nm is more desirable.

  In addition, the particle diameter of the activated carbon particles can be appropriately selected according to the material and shape of the workpiece to be processed and the purpose of processing the workpiece, but to some extent from the top of ultra-precision machining, etc. A small particle size is desirable. From such a viewpoint, the average particle diameter of the activated carbon particles is usually 0.02 to 100 μm, more preferably 0.02 to 10 μm.

  The activated carbon particles having a desired particle diameter can be obtained, for example, by pulverizing and classifying commercially available activated carbon by a known appropriate method.

  The electroless plating layer formed on the surface of the activated carbon particles only needs to have a magnetic property capable of moving the activated carbon particles at least by a magnetic field.

  The material for forming the electroless plating layer is particularly preferably a magnetic material made of nickel or a nickel alloy. As a nickel alloy, a Ni-P alloy and a Ni-B alloy can be mentioned preferably, and other elements may be contained in these alloys. If hypophosphite is used as the reducing agent, nickel-phosphorus (Ni-P) alloy plating can be obtained, and if a boron compound is used, nickel-boron (Ni-B) alloy plating can be obtained. Nickel-phosphorus alloy plating using hypophosphite as a reducing agent has excellent mechanical, electrical, and physical characteristics, and it can uniformly coat plated products even on complicated shapes. There are advantages. On the other hand, Ni-B alloy plating using a boron compound such as dimethylaminoboron (DMAB) as a reducing agent is unlikely to form an oxide film on the plating film. It is particularly preferable to form an electroless plating layer made of a Ni-B alloy because it has a feature such that the rate is significantly lower than that of Ni-P alloy plating.

  Furthermore, in the magnetic abrasive grains of the present invention, an electroless nickel composite plating layer in which abrasive grains, particularly diamond particles, are arranged in such a nickel-containing electroless plating layer from the viewpoint of imparting high polishing ability. It can also be. The electroless nickel composite plating layer is preferably a nickel-diamond composite (including nickel alloy-diamond composites such as nickel-boron-diamond composite and nickel-phosphorus-diamond composite). A nickel-boron-diamond composite is particularly desirable.

  The diamond particles used to form such an electroless nickel-containing composite plating layer are not particularly limited. For example, those having an average particle diameter of 1 to 100 nm, more preferably about 1 to 10 nm are used. .

  The thickness of the nickel-containing electroless plating layer only needs to be a thickness that can ensure the magnetic characteristics required for magnetic abrasive grains for magnetic polishing. Therefore, the thickness is the type of material forming the electroless plating layer. It is desirable to change appropriately according to. For example, when a Ni-P alloy, a Ni-B alloy, or the like is used as a material for forming the electroless plating layer, the electroless plating layer made of these materials is about 0.1 to 1 μm on the activated carbon particles described above. It is desirable to form with thickness.

  Next, as a method for producing the magnetic abrasive grains of the present invention, a method for forming a nickel-containing electroless plating layer on the surface of activated carbon particles by electroless plating will be described in detail.

  First, the activated carbon particles having a desired particle diameter are cleaned as necessary. This cleaning treatment can be performed using an appropriate solvent such as an appropriate acid or water. For example, it can be suitably carried out by immersing in an aqueous HCl solution and then in deionized water at room temperature (25 ° C. ± 2 ° C., the same shall apply hereinafter) for about 24 hours.

  The activated carbon particles that become the cleaned substrate are then subjected to an activation treatment.

  In general, in the electroless nickel plating method, it is necessary to activate the surface of the object to be plated. Conventionally, the catalyst application / sensitization treatment for such activation is performed by a tin solution, a palladium solution, or tin-palladium. Using a complex solution or the like, a method is adopted in which a metal element or metal complex is adsorbed on the surface of the object to be plated, and the adsorbed metal element or metal complex is generated on the surface by oxidation-reduction reaction or the like. It was.

In the method for producing magnetic abrasive grains of the present invention, instead of such a conventional method, activated carbon particles are immersed in a NiSO ₄ / picolinic acid solution, and then the activated carbon particles are heated and dried under an inert atmosphere. By the treatment, a seed of nickel metal element as an autocatalyst for nickel-containing electroless plating is formed on the surface of the activated carbon particles as the object to be plated.

Our studies have shown that anions are more easily adsorbed on activated carbon than in neutral and cationic states. Here, picolinic acid acts on NiSO ₄ to form a chelated nickel anion. Because of the excellent reducing ability of activated carbon, the chelated anion of adsorbed picolinic acid and nickel (also referred to as Ni picolinate anion) is, for example, 700 to 1000 ° C. in an inert atmosphere, typically about At 700 ° C., it is reduced to metallic nickel and at the same time picolinic acid is carbonized.

  FIG. 2 shows an X-ray diffraction (XRD) spectrum (curve 1) of activated carbon particles after such Ni picolinate anion is adsorbed and an X-ray diffraction of activated carbon particles after reduction treatment (curve 1) in Examples described later. XRD) shows an example of a spectrum (curve 2). After the reduction treatment at 700 ° C. (curve 2), a peak of nickel metal is observed at 2θ = 44.6 °.

  The seed of metallic nickel formed in this manner functions as an autocatalyst for subsequent nickel-containing electroless nickel plating.

  Next, the activated carbon particles activated by the metallic nickel seed in this way are coated with a nickel-containing plating layer by an electroless plating method. That is, the activated carbon particles that have been activated by being given a metallic nickel seed as described above are immersed in an electroless plating solution containing nickel ion species that will have magnetic properties after film formation. By immersing the activated activated carbon particles in a plating solution, an electroless plating layer having magnetic properties can be generated. The principle of such electroless plating is the above-mentioned autocatalytic nickel element adhering to the surface of the activated carbon particles. The reducing agent in the plating solution is oxidized, and the electrons released at that time cause the magnetism in the plating solution. The ionic species that become the body is reduced, and as a result, an electroless plating layer having magnetic properties is generated.

Here, the electroless plating on the activated carbon particles is technically more technical than the electroless plating on a general object to be plated because of the large specific surface area of the activated carbon particles, which is generally 800 to 1200 m ² / g as described above. Consideration is necessary.

  For example, when performing electroless Ni-B alloy plating using a boron compound such as dimethylaminoboron (DMAB) as a reducing agent, the initial concentration of DMAB, which is a reducing agent in the plating bath, can be increased by a conventional plating method. Also, it is desirable to set a higher value, specifically, for example, approximately twice. In the first half of the electroless plating treatment time, the pores of the activated carbon particles are only filled with the deposited plating layer. If the electroless plating is stopped at this point, the black color of the activated carbon does not change at all, and the shape of the activated carbon particles at this point also shows a significant change from the image of the scanning electron micrograph. Absent. After a further half-period of electroless plating treatment by dropping the reducing agent DMAB into the plating bath, the plated activated carbon particles become metallic. Curve 3 in FIG. 2 according to an example described later shows an XRD spectrum of the activated carbon particles after the electroless plating treatment for 1 hour in total, but the graphite peak of activated carbon disappears at 2θ = 25.2 °. Instead, a peak at 2θ = 44.6 ° representing nickel deposition was observed. The XRD spectrum of the plated activated carbon particles suggests that the surface of the activated carbon is completely covered by deposits.

In the electroless plating treatment, it is preferable to disperse the activated carbon particles uniformly in the plating solution so that an electroless plating layer having a predetermined thickness can be formed on the surface of each activated carbon particle. It is preferable to use stirring means such as mechanical stirring, gas stirring such as air, ultrasonic stirring using an ultrasonic homogenizer, etc. Also, nickel-diamond composite plating (nickel-boron-diamond composite as nickel-containing electroless plating) Including nickel alloy-diamond composite plating, such as nickel-phosphorus-diamond composites) can also be used to produce bonded magnetic abrasive grains. Such composite plating can be formed by dispersing and blending diamond particles in a nickel plating solution, as is well known.

  If the nickel plating layer contains diamond particles at a high content, the magnetic properties of the magnetic abrasive grains may be affected. For this reason, in the electroless plating process, it is desirable to set the blending ratio of the diamond particles in the initial plating solution low. For example, (1) the blending ratio of diamond particles is about 0.1 to 0.3 mg with respect to 100 ml of nickel plating solution, or (2) in order to include diamond particles only in the surface area of the plating layer, It is desirable not to add diamond particles to the initial plating solution, but to add diamond particles to the plating solution in the latter half of the electroless plating treatment time.

  The magnetic abrasive grains according to the present invention thus produced can be used as they are as abrasive grains for precision processing such as a magnetic polishing method, or can be used as a magnetic abrasive liquid together with a liquid medium. it can.

  When using the magnetic abrasive grains of the present invention as a constituent material of the magnetic abrasive liquid, the thickness of the electroless plating layer is changed to adjust the weight of the magnetic abrasive grains, It is also possible to adjust the degree of sedimentation.

  The liquid medium constituting the magnetic abrasive liquid may be any medium that allows the magnetic abrasive grains to freely move, and is appropriately selected in consideration of the type of workpiece and the specific gravity of the magnetic abrasive grains. For example, water, water-based lubricant, oil, oil-based lubricant, etc. can be used. Further, the content of the magnetic abrasive grains in the magnetic abrasive liquid is also appropriately adjusted according to the processing application and the workpiece.

  The magnetic abrasive grains of the present invention can be expected to be applied to precision machining of various workpieces by the magnetic polishing method. For example, precision abrasives such as super clean pipes used in next-generation semiconductors and manufacturing processes in the medical field, etc. It is effective for polishing products that require polishing and products that require high-precision polishing of a minute space such as in a pipe. In addition, for example, application to texture processing of a hard disk substrate surface of a hard disk device can be mentioned. Further, for example, application as an alternative process of chemical mechanical polishing (CMP) used in a damascene process for forming a copper wiring on a semiconductor substrate can be expected. The damascene process is a process of removing unnecessary copper on the surface after forming a barrier layer and a copper plating layer in a wiring groove on an insulating film. The magnetic abrasive grains of the present invention are not limited to such applications, and can be widely applied to various uses that can exhibit the functions of the magnetic abrasive grains of the present invention.

(Electroless plating method and electroless plating activator for activated carbon)
The electroless plating method and the electroless plating activator for activated carbon according to the present invention are achieved in the process of completing the invention of the magnetic abrasive grains and the method for producing the same. The electroless plating method and the electroless plating activator for activated carbon are generally applied to activated carbon, and can be applied regardless of whether the shape of the activated carbon is particulate, It may be a plate and is not particularly limited.

That is, in the electroless plating method of the present invention, activated carbon is brought into contact with a NiSO ₄ / picolinic acid solution, and then the activated carbon is heated and dried in an inert atmosphere to form a nickel metal element on the activated carbon. The activated carbon is activated and then nickel-containing electroless plating is performed to form a nickel-containing electroless plating layer on the surface of the activated carbon. This invention has been completed in the course of researching the method for producing magnetic abrasive grains according to the present invention. According to the present invention, activated carbon is immersed in a NiSO ₄ / picolinic acid solution, and then the activated carbon is heated and dried in an inert atmosphere, so that the chelating anion of picolinic acid and nickel attached to the activated carbon is nickel metal. And picolinic acid is carbonized. The activated carbon is activated by the nickel metal element thus formed, and a nickel-containing electroless plating layer having magnetism can be formed on the surface of the activated carbon by subsequent nickel-containing electroless plating.

Moreover, the electroless plating activator for activated carbon of the present invention is characterized by comprising a NiSO ₄ / picolinic acid solution. According to this invention, if a NiSO ₄ / picolinic acid solution is applied as an electroless plating activator for activated carbon, an electroless plating layer can be formed on the activated carbon.

  Hereinafter, the present invention will be described more specifically with reference to examples.

(Example 1)
Activated carbon (manufactured by Mitsubishi Chemical Corporation, trade name: Mitsubishi Diamond Hope 008) was pulverized into fine particles, sieved, and pulverized particles having a size of 200 to 320 mesh were used as a raw material substrate for electroless plating. FIG. 1 is a flowchart showing each step of manufacturing magnetic abrasive grains using the activated carbon particles in Example 1.

  First, the activated carbon particles having a predetermined size as described above are soaked in a stirred 1M HCl aqueous solution at room temperature (25 ° C. ± 2 ° C., the same applies hereinafter) for 24 hours, and then in stirred deionized water at room temperature. It was cleaned by dipping for 24 hours. Thereafter, the cleaned activated carbon particles were dried in air at 200 ° C. for 5 hours.

Next, for the activation of the activated carbon particles, the cleaned activated carbon particles are placed in a stirred NiSO ₄ / picolinic acid solution (molar ratio 1: 2.5, pH 2.8-3.0) at room temperature 3. Soaked in time. Thereafter, the activated carbon particles were filtered off and separated from excess NiSO ₄ and picolinic acid solution. Next, the treated activated carbon particles were dried at 700 ° C. for 2 hours under a nitrogen atmosphere, whereby Ni ions adsorbed on the activated carbon particles were reduced to metallic Ni, and the adsorbed picolinic acid was carbonized.

  Next, nickel plating on the activated carbon particles was performed using an electroless plating technique. In order to maintain the plating reaction, a modified dropping plating method was used. The plating bath is initially 300 ml of a pH 9.0 solution containing 0.1 M nickel (II) sulfate, 0.025 M dimethylaminoboron complex (DMAB), 0.025 M glycine, and 0.5 M ammonium sulfate, and the bath temperature Used at 70 ° C. Meanwhile, 0.2 g of activated carbon particles was ultrasonically dispersed in 20 ml of a 0.255 M DMAB aqueous solution. Next, the DMAB solution in which the activated carbon particles were dispersed was added to the first plating bath while performing mechanical stirring at a stirring speed of 400 rpm. After plating for 30 minutes, a reducing agent (DMAB) having a concentration of 0.255M was dropped into the plating bath at a rate of 30 ml / h. Further, after 30 minutes, the nickel-plated activated carbon particles were filtered off, washed with deionized water, and dried in an oven.

  The nickel-plated activated carbon particles were observed with an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The obtained results are shown in FIGS. 2 and 3, respectively. XRD was measured using Rint200 / AFC-2C, and SEM images were observed using a field emission scanning electron microscope (manufactured by Hitachi, Ltd., S4500, acceleration voltage 20.0 kV).

  In this example, during the first 30 minutes of electroless plating, the pores of the activated carbon were only filled with the deposited plating layer. When the electroless plating was stopped at this point, the black color of the activated carbon did not change at all, and the shape of the activated carbon at this point also did not show any significant change from the scanning electron micrograph image. . After an additional 30 minutes of electroless plating treatment by dropping the reducing agent, DMAB, into the plating bath, the plated activated carbon particles became metallic. Curve 3 in FIG. 2 shows the XRD spectrum of the activated carbon particles after a total of 1 hour of electroless plating treatment, but the graphite peak of activated carbon at 2θ = 25.2 ° disappeared, instead of nickel deposition. A peak at 2θ = 44.6 ° representing The XRD spectrum of the plated activated carbon particles suggests that the surface of the activated carbon is completely covered by deposits.

  The integrity of the plating on the activated carbon surface is further demonstrated by the SEM image of FIG. The form of the activated carbon before the plating treatment (FIG. 3A) and after the treatment (FIG. 3B) is greatly different. The random and multi-edge shape of the nickel plating layer on the activated carbon was expected as an incisor in the magnetic polishing method.

(Example 2)
In Example 1, 300 mL of a pH 9.0 solution containing 0.1 M nickel (II) sulfate, 0.025 M dimethylaminoboron (DMAB), 0.025 M glycine, and 0.5 M ammonium sulfate in a plating bath was averaged. The activated carbon particles were plated in the same manner as in Example 1 except that 0.1 mg of diamond powder having a particle size of 80 nm (manufactured by Tomei Diamond Co., Ltd.) was added to obtain nickel-diamond composite plated activated carbon particles. . The obtained composite plated activated carbon particles were observed with a scanning electron microscope (SEM). The obtained result is shown in FIG. Although the part of the diamond powder could not be discriminated from the photograph of the particle form shown in FIG. 3, in the particles obtained in Example 1 shown in FIG. 3 (b), the same plating layer formed on the activated carbon surface was used. Completeness could be observed.

(Example 3)
In the same manner as in Example 1, plating was carried out for 30 minutes in a solution of pH 9.0 containing 0.1 M nickel (II) sulfate, 0.025 M dimethylaminoboron (DMAB), 0.025 M glycine, and 0.5 M ammonium sulfate. After the treatment, the activated carbon particles were plated in the same manner as in Example 1 except that 1 mg of diamond powder (Tomei Diamond Co., Ltd.) having an average particle size of 80 nm was added to the plating solution. Diamond composite plated activated carbon particles were obtained. The obtained composite-plated activated carbon particles had a complete plating layer on the surface of the activated carbon, similar to those obtained in Example 2.

(Example 4)
Magnetic polishing was performed using the magnetic abrasive grains produced in Examples 1 and 2. A pure copper plate having a surface roughness Ra of 0.273 was used as a sample, and 10 mm × 10 mm sections were polished. A slurry for polishing the mixture of nickel electroless plating activated carbon produced in Example 1 and processing oil, or the mixture of nickel-diamond composite electroless plating activated carbon produced in Example 2 and processing oil Used as. Table 1 shows the polishing conditions.

  The surface morphology and surface roughness of the sample before and after the polishing treatment were measured using a VK-8500 digital microscope (manufactured by Keyence Corporation) under the conditions of a laser wavelength of 685 nm, an output of 0.45 mW, and a resolution of 0.01 μm.

  FIG. 4 is a photograph of a copper plate sample surface before and after polishing with nickel electroless plating activated carbon for 30 minutes and before and after polishing with nickel-diamond composite electroless plating activated carbon, FIG. 4 (a) is an untreated state, FIG. (B) shows the state after the polishing treatment with nickel electroless plating activated carbon, and FIG. 4 (c) shows the state after the polishing treatment with nickel-diamond composite electroless plating activated carbon. The sample surface finished with nickel electroless plated activated carbon has a surface roughness Ra of 0.221, and the sample surface finished with nickel-diamond composite electroless plated activated carbon improves the surface roughness Ra to 0.05. It was done. A mirror-like surface could be obtained by polishing with nickel-diamond composite electroless plated activated carbon for 30 minutes.

It is the flowchart which showed each process which manufactures a magnetic abrasive grain using activated carbon in one Example of the manufacturing method of the magnetic abrasive grain of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is an XRD chart of the nickel plating activated carbon particle obtained in one Example of the manufacturing method of the magnetic abrasive grain of this invention. Activated carbon particles, curve 3 is an XRD spectrum of nickel-plated activated carbon particles. (A) is a scanning electron micrograph of untreated activated carbon used in one embodiment of the method for producing magnetic abrasive grains of the present invention (magnification 2,300 times), and (b) is nickel electroless plating on this activated carbon. A scanning electron micrograph of the state (magnification 2,300 times) and (c) are scanning electron micrographs (magnification 2,300 times) of the activated carbon obtained by electroless plating of the nickel-diamond complex. It is a photograph of the surface of a copper plate sample before and after polishing with nickel electroless plating activated carbon and with nickel-diamond composite electroless plating activated carbon, (a) is an untreated state, (b) is polishing with nickel electroless plating activated carbon. After the treatment, (c) shows the state after the polishing treatment with the nickel-diamond composite electroless plated activated carbon.

Claims (7)

  A magnetic abrasive comprising a magnetic nickel-containing electroless plating layer formed on activated carbon particles.   The magnetic abrasive grains according to claim 1, wherein the nickel-containing electroless plating layer is an electroless nickel-boron plating layer or an electroless nickel-boron-diamond composite plating layer.   3. The magnetic abrasive according to claim 1, wherein the activated carbon particles have an average particle diameter of 20 to 60 μm.   The magnetic abrasive according to claim 1 or 2, wherein the nickel-containing electroless plating layer has a thickness of 10 to 100 nm. After immersing the activated carbon particles in a NiSO ₄ / picolinic acid solution, the activated carbon particles are heated and dried in an inert atmosphere to form nickel metal elements on the activated carbon particles to activate the activated carbon particles, A method for producing magnetic abrasive grains, wherein nickel-containing electroless plating is performed to form a nickel-containing electroless plating layer having magnetism on the surface of the activated carbon particles. After contacting the activated carbon with the NiSO ₄ / picolinic acid solution, the activated carbon is heated and dried in an inert atmosphere to form a nickel metal element on the activated carbon to activate the activated carbon. An electroless plating method, wherein nickel electroless plating is performed to form a nickel-containing electroless plating layer on the surface of the activated carbon. An electroless plating activator for activated carbon, comprising an NiSO ₄ / picolinic acid solution.

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