KR102150161B1 - Nickel-coated super-abrasive particles with excellent magnetic properties and wire saw using the same - Google Patents

Abstract

The problem to be solved by the present invention is an ultra-hard particle that can be used for a wire saw, which has ferromagnetic properties and at the same time exhibits excellent corrosion resistance, so that electrodeposition is satisfactory in various electrolytes used in the electrodeposition process when manufacturing a wire saw. It is to provide a composite particle capable of improving the cutting performance of a wire saw with excellent post adhesion and a wire saw to which the composite particle is attached. In addition, it is to provide a method of producing composite particles having excellent ferromagnetic properties and excellent corrosion resistance in strong acids so that good ultra-hard particles can be adhered even in various electrodeposition processes.
To this end, the present invention is a composite particle comprising an ultra-hard particle and a film formed on the surface of the ultra-hard particle, the film is formed on the surface of the ultra-hard particle, and consists of a metal layer containing nickel and phosphorus, In the metal layer, a composite particle in which particles having ferromagnetic properties are dispersed is provided, and a wire saw in which such composite particles are attached to a wire through an electrodeposition process is provided. In addition, there is provided a method for producing composite particles in which a film in which ferromagnetic particles are dispersed in the metal layer is formed on the surface.

Description

Nickel-coated super-abrasive particles with excellent magnetic properties and wire saw using the same}

The present invention relates to ultra-hard particles coated on a surface of a metal or a metal compound, and a method for producing the same. In addition, it relates to a wire saw (wire saw) comprising ultra-hard particles coated on the surface of the metal or metal compound made according to the present invention.

Wafers are widely applied in the IT industry. Typical examples are silicon wafers for semiconductors, silicon wafers for solar light, sapphire wafers for LEDs, and the like, and these wafers are made into thin disks through slicing from silicon or sapphire single crystal ingots.

In this growing IT industry, in order to secure cost competitiveness, wafers are gradually becoming larger in size and thinner in order to reduce the required amount of expensive wafers. In particular, in the semiconductor industry, the size of ingots is gradually increasing in size to improve productivity, and in the solar industry, attempts to minimize wafer loss during processing and use of thinner wafers for cost competitiveness are continuing. In order to satisfy the demand for improving the performance of cutting tools for slicing ingots is increasing.

A typical tool used in the slicing process is a wire saw, which minimizes material loss during the slicing process and increases the process speed, which is an area where tool makers are focusing on new product development. In the slicing process using such a wire saw, conventionally, the slurry method was mainly carried out by spraying a slurry containing ultra-hard particles around the wire.However, due to the demand for thin and precise slicing, the wafer is sliced by attaching the ultra-hard particles directly to the wire. Progress is being made as a process. Diamond and cBN (cubic boron nitride) are typical examples of ultra-hard particles. The wire saw method with ultra-hard particles has increased processing speed, improved processing precision, and increased yield due to a decrease in the amount of material lost during processing. Its application rate is increasing very rapidly.

The structure of the wire saw has a structure in which ultra-hard particles (diamond, cBN) are attached to a steel wire, and these ultra-hard particles are attached through an electrodeposition process (electrochemical plating method). The ultra-hard particles used in this electrodeposition process must have a metal layer such as nickel or cobalt formed on the surface for imparting conductivity during the electrodeposition process and for adhesion on the wire after attachment.

These metal composite ultrahard particles are mainly made by forming a metal layer using an electroless plating process. In the actual field, the nickel metal layer is most often applied to the metal layer in consideration of corrosion resistance and price that can withstand in the electrolyte used in the electrodeposition process. Most of these nickel metal layers contain phosphorus, which is largely influenced by sodium hypophosphite, which is used as a stable reducing agent.

U.S. Patent No. 8,858,693 discloses a composition and a method for electroless nickel plating of particles. In particular, since all of the reducing agents disclosed in the examples are sodium hypophosphite, phosphorus is inevitably contained in a high content in the nickel metal layer. .

In addition, Korean Patent Registration No. 0545107 discloses a method for producing a nickel-diamond composite powder by an electroless nickel plating method. Here, the reducing agent is bound to contain a large amount of phosphorus by using sodium hypophosphite.

The reason why the nickel coating layer containing phosphorus is formed in this way is that the process control is easy when sodium hypophosphite is used in the process, but the corrosion resistance is improved compared to the case without phosphorus and the adhesion to the ultrahard particles is excellent. However, when phosphorus is contained in a large amount, ferromagnetic properties are lost.

Meanwhile, in recent years, many attempts have been made to facilitate wire attachment by using magnetic properties as well as electrical properties by forming a metal layer having ferromagnetic properties on the surface of ultra-hard particles according to a manufacturing process. However, such a metal layer having ferromagnetic properties has a problem in that the corrosion resistance is inferior to the conventional metal layer without ferromagnetic properties. Therefore, in the electrodeposition process of attaching the ultra-hard particles to the wire during the wire saw manufacturing process, the metal layer having ferromagnetic properties cannot withstand the electrolytic solution of a strong acid used to use the ultra-hard particles formed on the surface of the conventional metal layer without ferromagnetic. Accordingly, in order to utilize the ferromagnetic properties of the powder, there is a problem of developing a new electrolyte to be used in the electrodeposition process of the wire saw manufacturing process.

US Patent No. 8,858,693 Korean Patent Registration No. 0545107

The problem to be solved by the present invention is an ultra-hard particle that can be used for a wire saw, which has ferromagnetic properties and at the same time exhibits excellent corrosion resistance, so that electrodeposition is satisfactory in various electrolytes used in the electrodeposition process when manufacturing a wire saw. It is to provide a composite particle capable of improving the cutting performance of a wire saw with excellent post adhesion and a wire saw to which the composite particle is attached.

In addition, it is to provide a method of manufacturing composite particles having excellent ferromagnetic properties and excellent corrosion resistance in strong acids so that good ultra-hard particles can be adhered even in various wire saw manufacturing processes.

One aspect of the present invention for solving the above problem is a composite particle comprising an ultra-hard particle and a film formed on the surface of the ultra-hard particle, wherein the film is formed on the surface of the ultra-hard particle, and contains nickel and phosphorus. It is made of a containing metal layer, to provide a composite particle in which particles having ferromagnetic properties are dispersed in the metal layer.

Another aspect of the present invention for solving the above problem is to provide a wire saw in which the composite particles are attached to the wire through an electrodeposition process.

Another aspect of the present invention for solving the above problem is to provide a method of manufacturing composite particles in which a film in which ferromagnetic particles are dispersed in the metal layer is formed on the surface.

According to the present invention, a composite particle including a nickel film layer having excellent corrosion resistance as well as excellent ferromagnetic properties can be produced, so that it can be used without limitation in a wire saw manufacturing process under various conditions.

In the case of using the composite particles according to the present invention, the electrolytic solution used in the electrodeposition process of the conventional wire saw manufacturing process can be used in the wire saw manufacturing process using ferromagnetic properties, so there is no need to develop a new electrolyte solution, and various Since it can be applied to electrolyte conditions, it can be usefully applied to an electrodeposition process using a new electrolyte.

In addition, according to the present invention, it is possible to provide a method of efficiently manufacturing composite particles having excellent ferromagnetic properties and corrosion resistance at the same time using a conventional general electroless plating method.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned in the present specification will be clearly understood by those skilled in the art from the following description.

1 is a schematic diagram of a composite particle in which a metal layer and a film in which ferromagnetic particles are dispersed in the metal layer are formed on the surface of an ultra-hard particle according to the present invention.
FIG. 2 is a photograph showing a surface of a composite particle made according to Example 1 after a corrosion resistance test through SEM.
3 is a photograph showing a surface of a composite particle made according to Comparative Example 3 through a SEM after a corrosion resistance test.

Hereinafter, with reference to the accompanying drawings with respect to an embodiment of the present invention will be described the configuration and operation. In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, when a part'includes' a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

The composite particle according to the present invention is a composite particle comprising an ultra-hard particle and a film formed on the surface of the ultra-hard particle, the film formed on the surface of the ultra-hard particle, and composed of a metal layer containing nickel and phosphorus. , In the metal layer, particles having ferromagnetic properties are dispersed. These composite particles have corrosion resistance that can withstand strong acids through a metal layer containing nickel and phosphorus, and magnetic properties can be utilized in the electrodeposition process of a wire saw through ferromagnetic particles dispersed in the metal layer.

Here, the ultra-hard particles, preferably, may be a composite particle comprising particles selected from the group consisting of diamond, cubic boron nitride, silicon carbide, boron carbide, alumina, silicon nitride, tungsten carbide, zirconia, or a combination thereof. . In addition, even if not mentioned as a preferred example, any particle having a hardness of a certain or more that can be used for cutting or polishing applied to the wire saw can be applied without limitation.

In addition, the particles having ferromagnetic properties, preferably, a composite comprising particles selected from the group consisting of nickel particles, cobalt particles, nickel-cobalt alloy particles, iron particles, iron-cobalt alloy particles, iron oxide particles, or a combination thereof. It can be a particle. In addition, even if not mentioned as a preferred example, any particle having ferromagnetic properties may be applied without limitation.

In the present invention, the metal layer containing nickel and phosphorus imparting corrosion resistance may be a composite particle containing 6 to 13% by weight of phosphorus. Generally, in the industry, the phosphorus content of 5% by weight or less is classified as low nickel, 6 to 9% by weight nickel, and 10 to 13% by weight as high phosphorus nickel.Depending on the classification, magnetic properties, electrical conductivity, and mechanical properties The back makes a lot of difference. In particular, in the case of low phosphorus nickel, the corrosion resistance in acid is rapidly deteriorated, and for stable corrosion resistance, it is preferable that the phosphorus content is medium nickel or high phosphorus nickel in a range of 6 to 13% by weight.

Further, in the present invention, the ferromagnetic particles are composite particles having a D ₅₀ of 0.1 to 3 µm, which is a 50% particle diameter of the cumulative volume particle size distribution by a laser diffraction scattering particle size distribution measurement method. Particles having ferromagnetism is there is changed also ferromagnetic properties D No ₅₀ is to obtain the composite particles having ferromagnetic properties intended by the present invention, the ferromagnetic properties are dropped sharply when the nano powder is less than 0.1 ㎛ according to its diameter, D ₅₀ is If it exceeds 3 μm, the frequency of the powder not dispersed in the metal layer but protruding out of the metal layer increases, which may deteriorate the corrosion resistance and make it difficult to adhere to the wire saw, so it is preferable that the D ₅₀ is 0.1 to 3 μm in diameter. .

In addition, in the present invention, the weight of the ferromagnetic particle may be a composite particle of 5 to 20% of the total weight of the composite particle. If it is less than 5%, it is difficult to impart sufficient ferromagnetic properties to the composite particles, and if it exceeds 20%, the total coating layer content becomes too large after coating, resulting in a problem that the machinability of the composite particles is deteriorated.

In addition, in the present invention, the weight of the metal layer containing nickel and phosphorus is preferably a composite particle of 20 to 50% of the total weight of the composite particle. If it is less than 20%, it is difficult to impart sufficient corrosion resistance to the composite particles, and if it exceeds 50%, the content of the entire film including ferromagnetic particles becomes too large, and thus there is a problem that the machinability of the composite particles is deteriorated.

In addition, in the present invention, the weight of the film may be a composite particle, which is 30 to 70% of the total weight of the composite particle. If the film is less than 30%, it is difficult to obtain sufficient ferromagnetic properties and corrosion resistance at the same time, and if it exceeds 70%, there is a problem that the machinability of the composite particles is deteriorated.

It is preferable that the saturation magnetization value of the composite particles provided in the present invention is 3 emu/g or more. In some wire saw manufacturing lines, if it is less than 3 emu/g, it is difficult to utilize magnetic properties in the electrodeposition process.

In addition, through the present invention, it is possible to provide a wire saw, which is made by attaching the composite particles having excellent ferromagnetic properties and corrosion resistance to a wire through an electrodeposition process.

In the present invention, it is also possible to provide a method for producing composite particles including ultrahard particles having excellent ferromagnetic properties and excellent corrosion resistance in strong acids, and a film formed on the surface of the ultrahard particles.

Specifically, in a method of forming a composite particle comprising an ultra-hard particle and a film formed on the surface of the ultra-hard particle, (a) preparing the ultra-hard particle, (b) the surface of the ultra-hard particle Pretreating the pre-treatment using tin chloride and palladium chloride, (c) injecting the pre-treated ultra-hard particles into an aqueous solution containing nickel ions and stirring to disperse them, (d) nickel ions in which the ultra-hard particles are dispersed. Further adding and dispersing ferromagnetic particles to an aqueous solution containing, (e) adding a reducing solution containing sodium hypophosphite to an aqueous solution containing nickel ions in which the ultra-hard particles and ferromagnetic particles are dispersed to obtain nickel ions. Comprising the steps of forming composite particles by depositing nickel-phosphorus metal together with the ferromagnetic particles on the surface of the hard particles, and (f) filtering and washing the formed composite particles, composite particles having excellent ferromagnetic properties and corrosion resistance Provides a method of manufacturing. Basically, by simply injecting ferromagnetic particles during the process using the electroless plating method while using the existing electroless plating method, it is possible to efficiently manufacture composite particles having a high corrosion resistance film in which ferromagnetic particles are dispersed.

In addition, in the present invention, in the step (d), the ferromagnetic particles are added to an aqueous solution containing nickel ions in which the ultra-hard particles are dispersed in a slurry state dispersed in an aqueous solution, having excellent ferromagnetic properties and corrosion resistance. It provides a method of manufacturing composite particles. Through the introduction of the dispersed slurry, ferromagnetic particles are uniformly dispersed in the metal layer having high corrosion resistance to form a more uniform film layer, thereby making a film with improved ferromagnetic properties and corrosion resistance. When making the dispersed slurry state, the dispersibility of ferromagnetic particles may be improved by using a dispersant.

A composite particle comprising an ultrahard particle according to a preferred embodiment of the present invention and a film formed on the surface of the ultrahard particle will be described with reference to the drawings.

1 is a schematic diagram of a superhard particle according to the present invention and a film formed on the surface of the superhard particle. The ultra-hard particles 10 include particles selected from the group consisting of diamond, cubic boron nitride, silicon carbide, boron carbide, alumina, silicon nitride, tungsten carbide, zirconia, or a combination thereof. FIG. 1 shows composite particles in which ferromagnetic particles 12 having ferromagnetic properties are dispersed in a metal layer 11 containing nickel and phosphorus in forming an electrically conductive film on the surface of such ultra-hard particles 10. .

Hereinafter, the present invention will be described in more detail through examples. The following examples illustrate the present invention, and the present invention is not limited thereto.

(Example 1)

Diamond particles were prepared as ultra-hard particles. The diameter of the prepared diamond particles was 4 to 10 μm based on D ₅₀ . 10 g of the prepared diamond particles were stirred and maintained at 60° C. for 30 minutes in ion-exchanged water in which a degreasing agent (ACE CLEAN A-110, Okono Corporation) was dissolved to remove foreign substances on the surface. After washing, the sensitization treatment was performed in an aqueous solution at 60°C containing 1% by weight of tin chloride (SnCl ₂ ), and the activation treatment was performed by stirring for 30 minutes in an aqueous solution at 60°C containing 0.1% by weight of palladium chloride (PdCl ₂ ). .

Nickel powder (NiSO4·6H ₂ O) 50 g and Rossel's salt (C ₄ H ₄ KNaO ₆ ·4H ₂ O) 75 g are dissolved in ion-exchanged water. 1.5 g of Ni-GB0401) manufactured by Guangbo, China was slowly added for 5 minutes. Nickel powder was analyzed using a laser particle size diffraction analyzer (Malvern, MASTERSIZER 3000), and as a result, D _{50, which} is 50% of the cumulative volume particle size distribution, was 0.6 µm. Then, while continuing to stir the solution, a reducing solution made by dissolving 800 g of sodium hypophosphite (NaH ₂ PO ₂ ) and 80 g of ammonia water (NH ₄ OH, 25%) in ion-exchanged water was gradually added to the metal layer containing nickel and phosphorus, A film in which nickel powder was dispersed was formed on the metal layer.

(Example 2)

Composite particles were prepared in the same manner as in Example 1, but 3 g of nickel powder (Gwangbo, China, Ni-GB0401) was added to an aqueous nickel sulfate solution containing activated diamond, and a reducing solution was added to prepare composite particles. .

(Example 3)

Composite particles were prepared in the same manner as in Example 1, but nickel sulfate was reduced to 30 g and other reagents were also proportionally reduced thereto to lower the weight occupied by the metal layer in the final composite particles.

(Example 4)

Composite particles were prepared in the same manner as in Example 1, but 1.5 g of nickel powder (Gwangbo, China, Ni-GB0401) was added to 100 g of ion-exchanged water containing 0.02 g of a dispersant (Sannovco, 5468cf, 10%), and After stirring for 10 minutes to sufficiently disperse, the dispersed nickel powder slurry was added to an aqueous nickel sulfate solution containing activated diamond, and a reducing solution was added to prepare composite particles.

(Example 5)

Composite particles were prepared in the same manner as in Example 1, but 3 g of nickel powder was added to 100 g of ion-exchanged water containing 0.2 g of a dispersant (Sannovco, 10%) and stirred for 10 minutes to sufficiently disperse and then dispersed. The nickel powder slurry was added to an aqueous nickel sulfate solution containing activated diamond, and a reducing solution was added to prepare composite particles.

(Example 6)

Composite particles were prepared in the same manner as in Example 4, but instead of nickel powder, a slurry in which 1.5 g of iron powder (BASF, CIP HQ) was dispersed was added to an aqueous nickel sulfate solution containing activated diamond, and a reducing solution was added. To prepare a composite particle. As a result of analyzing the iron powder using a laser particle size diffraction analyzer (Malvern, MASTERSIZER 3000), D _{50, which} is 50% of the cumulative volume particle size distribution, was 2.1 µm.

(Example 7)

Composite particles were prepared in the same manner as in Example 4, but instead of nickel powder, a slurry in which 3 g of iron powder (BASF, CIP HQ) was dispersed was added to an aqueous nickel sulfate solution containing activated diamond, and a reducing solution was added. Thus, composite particles were prepared.

(Comparative Example 1)

The sensitization treatment and activation treatment of the diamond particles were performed in the same manner as in Example 1, and sodium hypophosphite was added while stirring the treated diamond particles in an aqueous nickel sulfate solution made by dissolving 66 g of nickel sulfate and 100 g of Rossel's salt in ion-exchanged water. A reducing solution made by dissolving 1,200 g and 50 g of ammonia water (25%) in ion-exchanged water was gradually added to form a single layer and a surface film containing nickel and phosphorus.

(Comparative Example 2)

The sensitization treatment and activation treatment of the diamond particles were performed in the same manner as in Example 1, and then the treated diamond particles were added to an aqueous nickel sulfate solution made by dissolving 37 g of nickel sulfate and 60 g of Rossel's salt in distilled water, while stirring, and 650 g of sodium hypophosphite. A reducing solution prepared by dissolving 35 g of ammonia water (25%) in ion-exchanged water was gradually added to form a single layer and a surface film containing nickel and phosphorus.

(Comparative Example 3)

The sensitization treatment and activation treatment of the diamond particles were performed in the same manner as in Example 1, and then, after dissolving 68 g of nickel sulfate and 100 g of Rossel's salt in ion-exchanged water, the treated diamond particles were added to an aqueous solution of nickel sulfate and stirred while 120 g of hydrazine hydrate. Ion-exchanged water mixed with 50 g of sodium hydroxide and sodium hydroxide was gradually added to form a ferromagnetic surface film.

Ferromagnetic properties and corrosion resistance were evaluated for the diamond particles with the surface coating formed as described above, respectively.

Ferromagnetic properties were evaluated by measuring the saturation magnetization value. In order to evaluate the saturation magnetization value of the powder, the coated diamond particles are pressed into pellets, and the resulting sample is drawn at room temperature using a Vibrating-Sample Magnetometer (VSM) to draw a hysteresis curve and based on this. The saturation magnetization value was determined.

Corrosion resistance evaluation depends on whether the film layer has been removed or other reactive compounds have not occurred by observing the surface of the particles through a Scanning Electron Microscope (SEM) after leaving for 10 hours in an electrolyte solution of pH 2.0 containing sulfuric acid. It was judged as good or bad.

Table 1 below summarizes the evaluation results for each Example and Comparative Example. As can be seen from the results, in Examples 1 to 7, both exhibited excellent ferromagnetic properties and at the same time showed excellent corrosion resistance. 2 shows the SEM analysis results after the corrosion resistance test of the composite particles having the metal film formed thereon according to Example 1, and shows that there is no change in the film even when maintained in an electrolyte solution of strong acid for a long time.

On the other hand, as in Comparative Examples 1 to 3, when only a single film for corrosion resistance or only a single film for magnetism is formed on the surface of the ultra-hard particles, the ferromagnetic properties are insignificant or the corrosion resistance is poor, so it can be applied in various electrolytic solutions and electrodeposition processes. No possible powder could be obtained. 3 is a result of observing the composite particles according to Comparative Example 3 through SEM after a corrosion resistance test. It can be seen that the surface was severely detached and plate-shaped nickel hydrate was formed.

Magnetic particles Metal layer Saturation magnetization
(emu/g) Corrosion resistance Particle type Particle weight% Film weight% P content (% by weight) Example 1 Nickel (Ni) 6.7 49 10 4 Good Example 2 Nickel (Ni) 12.5 46 11 6 Good Example 3 Nickel (Ni) 8.3 37 11 9 Good Example 4 Nickel (Ni) 6.7 49 11 5 Good Example 5 Nickel (Ni) 12.5 46 10 7 Good Example 6 Iron (Fe) 6.7 49 11 7 Good Example 7 Iron (Fe) 12.5 46 11 13 Good Comparative Example 1 - - 59.2 13 1 or less Good Comparative Example 2 - - 45 13 1 or less Good Comparative Example 3 - - 59 0 28 Bad

In the present specification, the present invention has been described with reference to some embodiments, but it should be understood that various modifications and changes can be made without departing from the spirit and scope of the present invention that can be understood by those skilled in the art to which the present invention belongs. something to do. In addition, such modifications and changes should be considered to fall within the scope of the claims appended to this specification.

Claims (12)

A composite particle comprising an ultra-hard particle and a film formed on the surface of the ultra-hard particle,
The film,
It is formed on the surface of the ultra-hard particles, and consists of a metal layer containing nickel and phosphorus, and particles having ferromagnetic properties are dispersed in the metal layer,
The particles having ferromagnetic properties include particles selected from the group consisting of nickel particles, cobalt particles, nickel-cobalt alloy particles, iron particles, iron-cobalt alloy particles, iron oxide particles, or combinations thereof. The method of claim 1,
The ultra-hard particles include particles selected from the group consisting of diamond, cubic boron nitride, silicon carbide, boron carbide, alumina, silicon nitride, tungsten carbide, zirconia, or a combination thereof. delete The method of claim 1,
The metal layer containing nickel and phosphorus contains 6 to 13% by weight of phosphorus, composite particles. The method of claim 1,
The ferromagnetic particle is a composite particle having a D ₅₀ of 0.1 to 3 μm, which is a 50% particle diameter of the cumulative volume particle size distribution by laser diffraction scattering particle size distribution measurement method. The method of claim 1,
The weight of the ferromagnetic particles is 5 to 20% of the total weight of the composite particles, composite particles. The method of claim 1,
The weight of the metal layer containing nickel and phosphorus is 20 to 50% of the total weight of the composite particles, composite particles. The method of claim 1,
The weight of the film is 30 to 70% of the total weight of the composite particles, composite particles. The method of claim 1,
The composite particle has a saturation magnetization value of 3 emu/g or more. In a method of forming a composite particle comprising an ultrahard particle and a film formed on the surface of the ultrahard particle,
(a) preparing ultra-hard particles;
(b) pretreating the surface of the ultra-hard particles using tin chloride and palladium chloride;
(c) adding the pretreated ultra-hard particles to an aqueous solution containing nickel ions, stirring, and dispersing;
(d) further injecting and dispersing ferromagnetic particles into an aqueous solution containing nickel ions in which the ultra-hard particles are dispersed;
(e) A reducing solution containing sodium hypophosphite is added to an aqueous solution containing nickel ions in which the ultra-hard particles and the ferromagnetic particles are dispersed, and nickel ions are added to the surface of the ultra-hard particles together with the ferromagnetic particles. Precipitating to form composite particles; And
(f) filtering and washing the formed composite particles,
The particles having ferromagnetic properties include particles selected from the group consisting of nickel particles, cobalt particles, nickel-cobalt alloy particles, iron particles, iron-cobalt alloy particles, iron oxide particles, or a combination thereof, and have ferromagnetic properties and corrosion resistance. How to make good composite particles. The method of claim 10,
In the step (d), the ferromagnetic particles are added to an aqueous solution containing nickel ions in which the ultra-hard particles are dispersed in a slurry state dispersed in an aqueous solution, characterized in that the method for producing composite particles having excellent ferromagnetic properties and corrosion resistance . A wire saw made by allowing the composite particles according to any one of claims 1 to 8 to adhere to a wire through an electrodeposition process.

Images