JPH04306290A - Production of composite grinding grain - Google Patents

Abstract

PURPOSE:To provide the subject method for production of composite abrasion grain for magnetic grinding, having improved grinding effect and durability. CONSTITUTION:Magnetic metal particles such as iron and grinding material particles such as chromium oxide are blended with stirring together with an acid such as nitric acid in a ball mill. The resultant mixture is then dried or calcined to fix the grinding material to the surface of the magnetic metal particles.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing composite abrasive grains, and more particularly to a method for producing composite abrasive grains for magnetic polishing using acid.

0002

2. Description of the Related Art Recently, a new polishing method called magnetic polishing method has been developed and is attracting attention. This method is used for deburring parts, polishing cylindrical parts, flat parts, inner surfaces of parts, complex-shaped parts such as spherical surfaces, free-form mold surfaces, edge finishing of various shaped parts, and hard and brittle parts such as ceramics and silicon wafers. It can be widely applied to precision finishing of materials. The magnetic polishing abrasive particles in this case are so-called composite abrasive particles that have both magnetism and polishing effect, and are required to have both ferromagnetism and high grindability.

[0003] Conventionally, such composite abrasive particles have been made by press-forming fine powders of iron and high-grind abrasive material, and then sintering them in an atmosphere furnace, hot pressure sintering, or using metal alloys. A method for internally nitriding carbon, a method for producing carbon materials from a melt of metal alloy and carbon, and a method for producing a composite compound of titanium carbide and iron by utilizing an exothermic reaction between carbon and titanium (A.B.Ly
ashehenko and other Poroshkovaya M
etallurgiya 9 44-48 (1983
)), a method in which iron and alumina are mixed and heated in an inert gas atmosphere (Japanese Patent Publication No. 61-250084)
, a method of creating composite abrasive grains by melting a mixture of iron and abrasive material by plasma heating (Masahiro Anzai et al., Journal of the Abrasive Processing Society 33)
, 4, p. 34 (1989)), a method of attaching iron and diamond by electroless plating has been proposed.

However, expensive atmosphere furnaces, crushers,
Although it requires a plasma generator and expensive chemicals, it has the drawbacks of low productivity, low grinding power, and low processing efficiency, making it not an economical method.

[0005]

[Problem to be solved by the invention] The performance required of magnetic abrasive grains is that they can be mass-produced at low cost, in terms of grinding power, surface finish, durability of the abrasive grains, and wide applicability. . There is no abrasive grain obtained by conventional methods that fully satisfies all of these points. An object of the present invention is to obtain excellent magnetic polishing abrasive grains that satisfy all of the above points.

[0006]

[Means for Solving the Problems] In order to achieve the above object, as a result of intensive research, we have developed a method for producing magnetic metals by interacting powder particles of magnetic metals such as iron and abrasive materials with various acids in an aqueous solution or an organic solvent. It was discovered that the abrasive material is firmly fixed to the surface, and the present invention was achieved.

[0007] Thus, the present invention provides a method for synthesizing composite abrasive particles, which is characterized in that an abrasive such as a metal oxide, nitride, carbide, or diamond is fixed to the surface of magnetic metal particles by interacting with an acid. It is.

In the present invention, the magnetic metal used is, for example, iron, cobalt, nickel, or an alloy containing these, and the size thereof is 0.5 to 5000 μm.
m, preferably about 20 to 600 μm.

If the size is smaller than 0.5 μm, the magnetism will be weak and the grinding force will be reduced, and if it is larger than 5000 μm, the magnetism will be strong and the surface finish will be poor, which is not preferable. Furthermore, it can also be used as a needle-shaped body, in which case the appropriate size is approximately 5 to 2000 μm in diameter, preferably 30 to 200 μm, and 1 to 20 mm in length, preferably 3 to 6 mm.

If the diameter is smaller than 5 μm, the needles become entangled and grinding becomes difficult, while if it is larger than 2000 μm, the overall surface area becomes extremely small and the grinding force decreases, which is not preferable.

Examples of the abrasive include metal oxides such as chromium oxide, cerium oxide, and zirconium oxide; metal nitrides such as silicon nitride, niobium nitride, and tungsten nitride;
Metal carbides such as silicon carbide, niobium carbide, titanium carbide, and chromium carbide, diamond, and the like may be used as appropriate.

[0012] The size of such abrasive material is 0.01 to 20
Appropriately, the thickness is about 0 μm, preferably about 0.1 to 20 μm. If the particle size is smaller than 0.01 .mu.m, the grinding force will be reduced, and if it is larger than 200 .mu.m, the surface finish will be poor due to the roughness of the particle size, which is not preferable.

The amount of abrasive fixed to the magnetic metal is 0.01 to 50%, preferably 0.1%, based on the total amount of composite abrasive grains.
It is appropriate to adopt about 30%. If the amount of abrasive is less than 0.01%, the grinding force will be extremely reduced, and if it is more than 50%, the adhesion of the abrasive will be poor and it will easily come off, so both are not preferable. .

As a means of fixing the abrasive material to the magnetic metal, for example, the magnetic metal, the abrasive material, and an acid are placed in a ball mill lined with stainless steel or polyamide resin, etc.
A means for fixing by rotating at a rotation speed of about 100 rpm for about 0.5 to 25 hours, or
Appropriate means may be employed, such as fixing by rotating at a rotation speed of about 5 to 100 rpm for about 0.5 to 25 hours in a stainless steel, FRP, or glass-lined tank equipped with a stirrer.

[0015] Examples of acids used in the present invention include nitric acid,
Mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, formic acid, citric acid,
Organic carboxylic acids such as oxalic acid and tartaric acid are suitable. Among these, it is preferable to use mineral acids because they have particularly strong fixing power and are durable. The concentration of acid used is 0.0
01-2N, preferably 0.1-0.3N is suitable.

If the acid concentration is less than 0.001N, the adhesion of the abrasive to the magnetic metal surface will be incomplete, and if it is higher than 2N, the reaction with the magnetic metal will be too intense.
Neither of these is preferable because the abrasive will not be sufficiently fixed. The temperature of the acid used to fix the abrasive to the magnetic metal is suitably 0 to 100°C, preferably 20 to 40°C.

[0017] When the temperature is lower than 0°C, the reactivity of the acid decreases and the adhesion of the abrasive material becomes incomplete.On the other hand, when the temperature is higher than 100°C, for example, a solution containing an acid may bump. Both are undesirable because the adhesion of the abrasive material becomes incomplete. The thus fixed magnetic metal and abrasive material are separated from the acid and dried or fired to further firmly bond them.

[0018] The temperature required for drying or firing is 80 to 10
It is appropriate to employ a temperature of 00°C, preferably 110 to 500°C. If the temperature is lower than 80° C., the fixed abrasive material will easily come off, and if the temperature is higher than 1000° C., oxidation of the magnetic metal surface will be promoted and the abrasive material will be easy to come off, so both are not preferred.

Although the mechanism of adhesion of the abrasive to the composite abrasive particles or composite abrasive needles synthesized by acid treatment in the present invention is not necessarily clear, it is estimated from the powder X-ray diffraction data that magnetic metals are bonded by the action of the acid. the surface of is ionized,
For example, when a γ-FeOOH phase is generated on the surface, the abrasive particles are fixed by this, and by drying or baking, it is thought that the two become more strongly fixed together.

The composite abrasive grains obtained in the present invention have a large amount of abrasive adhesion of 20 to 30%, and have high grinding power, surface finish, and durability. Therefore, compared to conventional hot pressing methods, alloy nitriding methods, fusion carbonization methods, iron-alumina heating methods, plasma heating methods, electroless plating methods, etc., the composite abrasive particles obtained by the synthesis method of the present invention are Extremely excellent for magnetic polishing.

[0021]

【Example】

[Example 1] 90 g of iron powder (70-80 μm) and 10 g of chromium oxide (1-2 μm) were dispersed in 40 cc of 0.3N nitric acid, and the mixed solution was milled in a ball mill (with gas plate hole, inner container 200 cc, polyamide resin). ) for 1 to 2 hours. After fixing the abrasive particles, the mixed solution was filtered under reduced pressure and washed with water. The fixed chromium oxide particles were dried at 110° C. to obtain 100 g of composite abrasive particles containing 10% chromium oxide. The abrasive grains obtained had about twice the grinding power of commonly used abrasive grains, and about twice the durability of conventional abrasive grains.

[Example 2] Iron powder (10-20 μm) 70
g and 30 g of chromium oxide (1 to 2 μm) were dispersed in 70 cc of 0.2N nitric acid, and in the same manner as in Example 1, 100 g of composite abrasive particles containing 30% chromium oxide were obtained. The grinding power of the obtained abrasive grains is approximately twice that of commonly used abrasive grains, and the durability is also approximately 2 times that of regular products.
It showed double the ability.

[Example 3] Iron powder (70-80 μm) 90
In the same manner as in Example 1, 100 g of composite abrasive grains containing 10% diamond were obtained by dispersing 10 g of diamond (2 to 4 μm) in 40 cc of 0.3N nitric acid. The abrasive grains obtained had a grinding power about three times that of commonly used abrasive grains, and a durability about twice that of conventional products.

[Example 4] Iron powder (800 to 2000 μm
) 97g and 3g of diamond (2-4μm) at 0.3N
100 g of composite abrasive grains containing 3% diamond were obtained in the same manner as in Example 1. The abrasive grains obtained had a grinding power about three times that of commonly used abrasive grains, and a durability about twice that of conventional products.

[Example 5] Iron powder (200-300 μm)
95g and 5g of diamond (8-16μm) at 0.3N
Dispersed in 40 cc of nitric acid, and then in the same manner as in Example 1,
100 g of composite abrasive particles containing 5% diamond were obtained. The abrasive grains obtained had a grinding power about three times that of commonly used abrasive grains, and a durability about twice that of conventional products.

[Example 6] Iron powder (70-80 μm) 80
20g of alumina (WA#4000, 3μm) was added to 0.g.
After dispersing in 40 cc of 3N nitric acid, 100 g of composite abrasive particles containing 20% alumina were obtained in the same manner as in Example 1. The abrasive grains obtained had about twice the grinding power of commonly used abrasive grains, and about twice the durability of conventional abrasive grains.

[Example 7] Iron powder (200-300 μm)
6 g of alumina (WA #1200, 12 μm) was dispersed in 40 cc of 0.3N hydrochloric acid and the same procedure as in Example 1 was carried out to obtain 100 g of composite abrasive particles containing 6% alumina. The abrasive grains obtained had about twice the grinding power of commonly used abrasive grains, and about twice the durability of conventional abrasive grains.

[Example 8] Iron powder (70-80 μm) 85
g, cerium oxide (Luminox EH, 1-2μ) 1
5g was dispersed in 40cc of 0.3N nitric acid, and the following Example 1 was prepared.
In the same manner as above, 100 g of composite abrasive particles containing 15% cerium oxide were obtained. The abrasive grains obtained had about twice the grinding power of commonly used abrasive grains, and about twice the durability of conventional abrasive grains.

[Example 9] Iron powder (70-80 μm) 90
10g of nitrogen silicon (2-3μ) in 4g of 0.3N sulfuric acid
100 g of composite abrasive particles containing 10% silicon nitride were obtained in the same manner as in Example 1. The abrasive grains obtained had about twice the grinding power of commonly used abrasive grains, and about twice the durability of conventional abrasive grains.

[Example 10] Iron powder (70-80 μm) 9
Add 10 g of zirconium oxide (0.5 to 1 μm) to 0 g.
．． Composite abrasive particles 10 containing 10% zirconium oxide were dispersed in 40 cc of 3N acetic acid and prepared in the same manner as in Example 1.
0 g was obtained. The abrasive grains obtained had about twice the grinding power of commonly used abrasive grains, and about twice the durability of conventional abrasive grains.

[Example 11] Iron needle (90 μmφ, 3 mm
L) 96g and 4g of diamond (1-2μm) 0.3
The mixture was separated into 40 cc of N nitric acid, and the same procedure as in Example 1 was carried out to obtain 100 g of composite abrasive particles containing 4% diamond. The abrasive grains obtained had about twice the grinding power of commonly used abrasive grains, and about twice the durability of conventional abrasive grains.

[Example 12] Iron needle (50 μmφ, 3 mm
5 g of alumina (WA#4000, 3μ) was dispersed in 40 cc of 0.3N nitric acid and 100 g of composite abrasive particles containing 5% alumina were obtained in the same manner as in Example 1. The abrasive grains obtained had about twice the grinding power of commonly used abrasive grains, and about twice the durability of conventional abrasive grains.

[Comparative Example 1] Iron powder (70-80 μm) 70
g and 30g of alumina (WA#4000, 3μ) were mixed well, and the mixed powder was heated to 90% at a pressure of 4000kg/cm2.
Hot pressing was carried out at 0°C to obtain 5 pellets each having a diameter of 20 mm and a thickness of 10 mm, totaling 90 g. The pellets were crushed using a jaw crusher and a roller mill to obtain 75 g of composite abrasive particles with a diameter of 80 to 150 μm.

[Comparative Example 2] Iron powder (70-80 μm) 70
g and 30 g of niobium carbide (3 μm) were thoroughly mixed, and the mixed powder was treated in the same manner as in Comparative Example 1 to obtain 75 g of composite abrasive grains of 80 to 150 μm.

[0035] Regarding the composite abrasive grains obtained in Examples 1 to 12 and Comparative Examples 1 and 2, the grinding force, surface finish,
The durability was investigated and the measurement results are shown in Table 1. For comparison, a commercially available electrodeposited diamond composite abrasive grain (Comparative Example 3), which is said to have high strength, and a simple iron needle (90 μmφ, 3 mmL) (
Comparative Example 4) was also tested.

[0036]

[Table 1]

[0037] Grinding power and surface finish of the composite abrasive grain of the present invention,
The test conditions for examining durability were 16 m as the work material.
mφ, 10 mmL silicon nitride ceramic rod (surface roughness 1.5 mm), magnetic polisher used was TMX101 manufactured by Toyo Abrasive Industry Co., Ltd., and peripheral rotational speed was 60 m/s.
, for 10 minutes at an excitation current of 2 A (magnetic flux density: 1.2 terraces). The grinding force was measured by the amount of polishing of the workpiece (mg), and the surface finish was measured by the maximum surface roughness Rmax (mm). As for durability, tests were conducted at 60 minute intervals for a total of 9 hours, and the amount of diamond and alumina on the surface was determined by X-ray diffraction and expressed as the adhesion rate.

[0038]

[Effects of the Invention] The abrasive grains according to the present invention have both grinding power and durability approximately twice as high as those of conventional abrasive grains, and are efficient and excellent in durability.

Claims (8)

[Claims] 1. A method for producing composite abrasive grains, which comprises fixing an abrasive material to the surface of magnetic metal particles by interacting with an acid. 2. The method for producing composite abrasive grains according to claim 1, wherein the magnetic metal is iron, cobalt, nickel, or an alloy containing these. Claim 3: The acid is nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid,
The method for producing composite abrasive grains according to claim 1, wherein the abrasive is formic acid, citric acid, oxalic acid, or tartaric acid. 4. The magnetic metal particles have a diameter of 0.5 to 5000.
The method for producing composite abrasive grains according to claim 1, wherein the composite abrasive grains have a particle size of μm. 5. The method for producing composite abrasive grains according to claim 1, wherein the abrasive is a metal oxide, nitride, carbide, or diamond. [Claim 6] The size of the abrasive material is 0.01 to 200 μm.
The method for producing composite abrasive grains according to claim 1. Claim 7: The amount of abrasive used is 0 based on the total amount of composite abrasive grains.
．． 2. The method for producing composite abrasive grains according to claim 1, wherein the content of the composite abrasive grains is 01 to 50%. 8. The method for producing composite abrasive grains according to claim 1, wherein the acid concentration is 0.001 to 2N.