KR20090060330A - Prealloyed metal powder, process for obtaining it, and cutting tools produced with it - Google Patents

Abstract

Prealloyed metal powder, especially for the manufacture of cutting tools by sintering, characterized in that its composition, in percentages by weight, is: 48-52% Fe; 14-19% Co; 32-37% Cu; <= 1 % O, the balance being impurities resulting from its manufacture. Process for obtaining this powder and diamond saws and cutting wires produced with this powder.

Description

Free alloy metal powder, manufacturing method thereof and cutting tool manufactured using the same {PREALLOYED METAL POWDER, PROCESS FOR OBTAINING IT, AND CUTTING TOOLS PRODUCED WITH IT}

FIELD OF THE INVENTION The present invention relates to the field of prealloyed metal powders used to produce diamond cutting tools such as saw segments or beads for making wires for cutting of solid materials such as granite.

Metal powders used to make diamond beads are typically formed from particulates containing about 20% tungsten carbide and about 80% cobalt. The granular material is mixed with diamond and compressed into rings, and the green components are sintered according to two methods.

In the first case, each of the graphite molds is filled with a green element equipped with a steel sleeve and sintered under pressure in a conventional hot press. However, because of the unique form of diamond beads:

Graphite molds are disadvantageous to be replaced periodically because of their complex shape and high cost of purchase;

-Green elements and annulus are difficult to fill in molds, so they have to be filled manually and thus there is a big cost problem in terms of labor force;

-In order to obtain uniformly sintered diamond beads, the number of beads sintered in each mold is limited to dozens of elements, which results in low productivity.

In the second case, the green element with the steel sleeve is placed in a fixed or conveyor oven for natural sintering, usually "free sintering". However, cobalt and tungsten carbide based beads are not sufficiently densified after the sintering. That is, a secondary heat treatment is required, which is carried out in an oven operated at a high pressure of 1,500 to 2,000 bar and thus affects the hot isostatic compression of the beads. Such ovens are expensive to buy and maintain.

These conventional methods are therefore both costly in terms of raw materials and production processes.

In this respect, an object of the present invention is diamond beads, which are more economical than conventional processes, because they are relatively low in manufacturing cost and can provide a high-performance product for granite cutting and the like, in spite of natural sintering performed without a mold. It is to provide a free alloy metal powder compatible with the production process. The powder must likewise be compatible with other types of cutting tool manufacturing processes that have a wide range of applications.

Therefore, the present invention is particularly suitable for the production of cutting tools according to sintering and in the composition of the weight percentage of the components:

* Fe = 48-52%

* Co = 14-19%

Cu = 32-37%

O (oxygen) 1.2% or less, and the remainder of the free alloy metal powder, characterized in that consisting of impurities produced during production.

The fischer diameter of the particles is preferably 1 to 3 mu m.

It is preferably composed of a mixture comprising a powder and at least one sintering auxiliary additive in a proportion of 80 to 90% by weight and 10 to 20% by weight.

The sintering auxiliary additive is preferably iron, nickel, copper or cobalt phosphide or a mixture of two or more of these phosphides, or a composite phosphide of at least two or more of the above metals.

The powder is prepared by mixing together a first powder and a second powder, and, if necessary, a sintering auxiliary additive, each of which is composed of:

For the first powder,

* Fe = 27 to 32%

* Co = 24 to 28%

Cu = 42-47%

* O (oxygen) up to 1%, and the remainder are impurities from the manufacture,

For the second powder,

* Fe = 75 to 80%

* Co 5% or less

Cu = 17-22%

* O (oxygen) is characterized in that less than 1%, and the rest are impurities produced during manufacture.

Preferably, the fischer diameter of the first powder particles is 0.8 to 1.5 mu m, the fischer diameter of the second powder particles is 3.0 to 4.0 mu m, and the fischer diameter of the powder obtained by mixing is 1 to 3 mu m.

The present invention also relates to a method for producing a diamond cutting tool, in particular comprising mixing the prealloy metal powder and diamond, cold-pressing the mixture and sintering the compacted mixture. In this case, the metal particles are as described above.

Sintering treatment is preferably natural sintering.

The tool may be a cutting segment of a diamond saw.

The tool may be a diamond bead for cutting wire.

The powder may be of the kind described above.

The present invention also relates to a diamond saw having a cutting segment fixed to the periphery of a metal disc, wherein the segment is manufactured according to the method described above.

The invention also relates to a cutting wire in the form of a diamond bead threaded onto a cable, wherein the bead is manufactured according to the method described above.

As can be seen from the above description, the present invention is based on the use of free alloy powder having a specific composition of iron, cobalt and copper. By using the powder containing no expensive element in a high content, it has been confirmed that diamond cutting tools (saws and beads) of very good performance can be produced according to simple natural sintering, that is, an economical and productive process.

The present invention also provides a method of making such powders that can be used to prepare sintered products of good quality.

The invention can be more clearly understood according to the following detailed description.

Prealloy powders according to the invention must in particular fulfill the following requirements.

The relative density of the green elements obtained with the powder should be at least 60% at a maximum cold pressure of 700 MPa.

It is preferred that it can be easily granulated to a size in the range of 63 to 450 μm and is particularly suitable for filling cold pressed steel molds for the production of beads for diamond wires.

After free sintering at a temperature of 850 to 1,100 ° C. in a conveyor oven (for continuous production) or in a stationary oven (for batch production), the relative density of the resulting urea should be at least 97%.

After sintering, the powder should be able to be used to produce an element having a hardness of at least 220 HB that can be used for granite cutting purposes.

It was confirmed that the above object and the above-described contents can be achieved according to the present invention by using a free alloy powder having the following characteristics.

The composition (weight percentage) of the powder is:

Fe = 48-52%

Co = 14 to 19%

Cu = 32-37%

Up to 1.2% O, and the remainder are impurities as a result of the preparation.

The average Fischer diameter of the particles (measured according to ISP 10070 by the method of determining the envelope-specific surface area by measuring the permeability of air through the powder layer under steady-state flow conditions) is preferably 1 to 3 μm.

Typical theoretical density is 8.4 g / cm ³ .

The relative ratio between iron and cobalt content is adjusted appropriately to prevent the formation of a hard and brittle α 'phase formed when the weight ratio Fe / (Fe + Co) is 30 to 70%. According to the present invention, since the relative ratio is 72 to 78%, it is possible to prevent the formation of the α 'phase.

The amount of copper added may be sufficient to good sintering treatment.

The oxygen content is maintained at up to 1.2% to prevent the formation of oxides that are not fully reduced by hydrogen during natural sintering. Such non-reducing oxides lower the sinterability of the green element, cause non-uniformity in the structure of the sintered element, increase the hardness and thus the cracking of the element, and also react with diamond and at least destroy it at the surface. The cutting power of the tool is therefore inferior.

The powder can be prepared in two ways in particular.

According to the first production method, a powder having a predetermined ingredient composition and shape is prepared according to a conventional wet smelting route.

The wet smelting route is primarily used to prepare metal hydroxides by using sodium hydroxide to precipitate a mixture of metal chlorides according to the following reaction:

xCuCl ₂ + yFeCl ₃ + zCoCl ₂ + (2 + t) NaOH-> Cu _x Fe _y Co _z (OH) ₂ + 2NaCl + tNaOH,

Where x + y + z = 1 and t is the amount of excess NaOH relative to the stoichiometric amount. x, y and z refer to the ratios corresponding to the atomic ratios between the Cu, Fe and Co contents found in the final powder.

Next, solid-liquid separation is performed and the resulting hydroxide cake is washed with demineralized water to remove NaCl. The obtained cake is put in a dryer to obtain a coprecipitation hydroxide powder having a residual water content of about several%.

The hydroxide powder is reduced again to convert to free alloy metal powder. The reduction reaction is preferably carried out in a conveyor oven under H ₂ according to the following reaction:

Cu _x Fe _y Co _z (OH) + H _2- > Cu _x + Fe _y + Co _z + H ₂ O

After reduction, the prealloy powder is ground in a grinder under an inert gas and filtered through a 90 μm sieve.

According to the second production method, the powder of the present invention is prepared by mixing two powders each having a different composition obtained by wet smelting. Table 1 shows the component compositions of the two powders used:

Characteristics of Powder (I) and Powder (II) element Powder (I) Powder (II) Iron (%) 27-32 75-80 Cobalt (%) 24-48 ≤5 Copper (%) 42-47 17-22 Oxygen (%) ≤1 ≤1 Proper fischer diameter (Ø) (μm) 0.8-1.5 3.0-4.0 Proper Fischer Diameter of Mixture (Ø) (μm) 1-3

As described above, the powder according to the present invention is prepared by mixing and mixing the powder (I) and the powder (II) in an appropriate ratio, rather than using the powder directly obtained by the wet smelting process in the first preparation method described above. It has been found that the case of obtaining powders of shows a much better result in many respects.

Generally, the powders of the invention can be obtained when their relative ratios in the mixture of powder (I) and powder (II) are about 60 to 40% by weight.

After obtaining the powder according to the present invention, it may be used directly or formed in the form of particles according to conventional processes as described below. The particles can then be used to make certain diamond tools, such as diamond wire and small thickness diamond segments.

The prealloy powder is mixed with the organic binder powder in a proportion of 2 to 3% by weight of the amount of powder to be granulated in the high shear granulator and also an organic solvent is added. After the granulation step the solvent is evaporated off.

Finally, the particles are successively sieved onto a vibrating screen equipped with two overlapping cloths of different mesh sizes (e.g., 450 μm for the first and 63 μm for the second), thereby producing components having a diameter of 63 to 450 μm. Collect it. The finer or granulated particles are recovered in the subsequent granulation process.

It is also preferred to add to the powder one or more additives that can increase the hardness of the sintered element. Tungsten carbide, a conventional additive used for this purpose, has been found to be unsuitable for use in the present invention and to result in the desired purpose, as it reduces the density and therefore the hardness of the elements upon sintering. It was found that tungsten carbide did not mix with the powder of the present invention and therefore could not be bound to the metal substrate in a metallurgical manner. Iron phosphide, on the other hand, has been found to have significant results and nickel, copper and cobalt phosphide are likewise advantageous.

A spontaneous sintering test was conducted on the powder of the present invention, and as a result, it was confirmed that the powder obtained from the mixture of powder (I) and powder (II) was superior to the powder directly obtained by single wet smelting.

The direct powder ("direct powder") is a wet smelting process as described above, i.e., NaOH is added to a mixture of Co and Fe chlorides, and the hydroxide obtained is dried in a dryer / fine powder maker, reduced and nitrogen sprayed at 660 ° C. nitroge-jet) was prepared by grinding in a grinder. The composition of the result was: Fe = 48.8%, Co = 16.0%, Cu = 34.4%, O = 0.8% and the Fisher diameter was 1.3 mu m.

Mixed preparative powders (“mixed powders”) were obtained by mixing 60% powder (I) and 40% powder (II) in a mixer maintained under CO ₂ , which powders were pre-formed respectively by wet smelting. . The mixing operation ended after 50 minutes. The composition of the resulting powder was: Fe = 49.1%, Co = 16.0%, Cu = 34.4%, O = 0.6% and the Fisher diameter was 1.74 mu m.

Next, the "direct" and "mixed" powders were pressed at 200 MPa to prepare PS21 type elements and their green density was calculated using size and weight. Direct powder was found to have a density corresponding to 58.0% of the powder theory and mixed powder had a density of 55.2% of theory.

Note that the conventional PS21 element is a parallelogram element obtained by cold pressing 6 g of powder at 200 MPa on a steel substrate of size 24.48 × 7.97 mm. The height of the resulting green element depends on the compressibility of the powder and is usually on the order of 5-6 mm.

Next, sintering was carried out in an experimental fixed oven under H ₂ at a temperature of about 850 to 1,000 ° C. In all cases, the rate of temperature increase was 150 ° C./hour, the duration at sintering temperature was 1 hour, and the cooling treatment was natural cooling overnight. The density of the sintered element was calculated as a percentage of the theoretical value (8.35 g / cm ³ ) and the HB hardness and HRB hardness were calculated. The results are shown in Table 2.

Sintering result of direct powder and mixed powder Sintering Temperature (℃) % Of theoretical density HB hardness HRB Hardness Direct powder Mixed powder Direct powder Mixed powder Direct powder Mixed powder 842 95.2 98.0 146 164 82.7 92.6 907 96.9 98.2 152 187 79.7 88.8 958 97.4 98.1 144 179 81.4 87.0 1007 98.4 98.3 153 170 83.2 88.0

Test results showed that the direct powder had better cold compressibility than the mixed powder. Therefore, it is expected that shaping treatment before sintering will be easier.

On the other hand, the mixed powder has better densification upon sintering and hardness after sintering.

Before sintering the direct powder and the mixed powder, iron phosphide (manufactured by BASF) containing 10% by weight of phosphorus component was added to the powder, followed by sintering test. Mixing was carried out for 50 minutes with a Gericke mixer under CO ₂ and the mixing ratio was 85% powder and 15% (wt%) iron phosphide (FeP).

Cold compression test was performed on the same conditions as the above. The density of the direct powder added with FeP was 59.1% of the theoretical density, and the density of the mixed powder was 53.1% of the theoretical density.

Powder sintering was performed under the same conditions as above, and the resulting urea density, HB hardness and HRB hardness were measured. The results are shown in Table 3.

Sintering result of direct powder and mixed powder with FeP Sintering Temperature (℃) % Of theoretical density HB hardness HRB Hardness Direct Powder + FeP Mixed Powder + FeP Direct Powder + FeP Mixed Powder + FeP Direct Powder + FeP Mixed Powder + FeP 860 96.7 98.3 204 225 94.8 97.4 907 97.1 98.4 213 224 97.5 98.9 957 97.8 98.5 213 225 96.6 98.9 1007 98.0 98.7 205 224 95.4 98.4

The performance regime between direct powder and mixed powder with FeP added is the same as for pure powder (without additives). Mixed powders give the best results after sintering.

As can be seen by comparing the results in Tables 2 and 3, the sintered elements when using the additive can have substantially greater hardness than the elements obtained from the additive free powder under the same conditions.

For reference, the powder of the present invention to which FeP is added in a mixing ratio of 85% powder and 15% FeP generally has the following characteristics:

-Ordinary theoretical density 8.21 g / cm ³

Fe = 54 to 58%

Co = 12-16%

Cu = 27 to 31%

P = 1-2%

-Less than or equal to 1.5%

Fischer diameter Ø = 2-5 μm.

In addition, a sintering test was carried out on the mixed powder containing nickel phosphate containing 8.8% by weight of phosphorus, wherein the mixing ratio was 85% powder mixture and 15% nickel phosphide (NiP). The results are shown in Table 4.

Sintering result of mixed powder with NiP Sintering Temperature (℃) % Of theoretical density HB hardness HRB Hardness 856 96.7 258 102.4 907 97.8 280 104.9 954 98.1 300 106 1002 98.1 305 106.2

 If NiP is added under the same conditions as above, a clear result can be obtained in terms of density and hardness of the sintered element.

For reference, the powder of the present invention with NiP added in a mixing ratio of 85% powder and 15% NiP generally has the following characteristics:

-Ordinary theoretical density 8.37 g / cm ³

Fe = 40-44%

Co = 11 to 17%

Cu = 27 to 31%

Ni = 13-15%

P = 1-2%

-Less than or equal to 1.5%

Fischer diameter Ø = 1-4 μm.

Copper phosphide or cobalt phosphide may also be used as an additive. Similarly, a mixture of at least two of iron, nickel, copper and cobalt phosphide, or a composite phosphide of at least two of the above metals may be used.

Granite cutting tests were performed on the urea prepared using the powder of the present invention and the reference powder, respectively, and the following results were obtained.

Granite cutting tests were performed using a diamond saw with a diameter of 500 mm and the saw segment formed according to natural sintering.

Conventional powder (Cobalite ^® CNF) with the following composition (weight percentage): Co = 0%; Cu = 26%; Fe = 68.4%; Ni = O%; Sn = 3%; W = 2%; Y ₂ O ₃ = 0.6%, also

It is prepared using FeP-containing powder (85% -15%) according to the invention as described above.

Using the two kinds of powder, a diamond segment for forming a saw blade was produced. The segment is a "sandwiched segment", ie has a diamond density (1.1 carat / cm ³ segment) that is larger around the center (0.8 carat / cm ³ segment). Standard diamond and titanium coated diamond were used. The selected segment is a complex and expensive kind that is manufactured by a conventional hot pressing process performed in a graphite mold.

Segments prepared using the reference powder and the powder of the present invention were treated by spontaneous sintering in a conveyor oven at 940 ° C for the powder of the present invention and 980 ° C for the reference powder, respectively. It was soldered to form a saw. Various granites were cut with the saw. For each powder, three kinds of diamond mixtures prepared by ELEMENT SIX were tested for reference.

After each cutting test, the cutting speed (cm ² granite cuttings / minute) and the service life of the saw (m ² granite cuttings / mm segment height) were calculated. The larger this value, the better the quality of the saw.

The following results were obtained using a mixture of SDB VB 40-50 mesh diamond (30%) and SDB LBW 50-60 mesh diamond (70%):

The reference saw had a service life of 4.4 m ² / mm and a cutting speed of 520 cm ² / min.

The saw of the present invention had a service life of 4.8 m ² / mm and a cutting speed of 620 cm ² / min.

Using a mixture of SDB VB 30-40 mesh diamonds (10%), SDB VB 40-50 mesh diamonds (40%), and SDB LBW 50-60 mesh diamonds (50%), the following results were obtained:

The reference saw was found to be impossible to cut granite.

The saw of the present invention had a service life of 3 m ² / mm and a cutting speed of 620 cm ² / min.

Using a mixture of SDB VB 30-40 mesh diamond (10%) and SDB TMF 40-50 mesh diamond (40%), and SDB TMF 50-60 mesh diamond (50%), the following results were obtained (TMF type) Diamond is titanium coated):

The reference saw had a service life of 4.1 m ² / mm and a cutting speed of 600 cm ² / min.

The saw of the present invention had a service life of 6.7 m ² / mm and a cutting speed of 900 cm ² / min.

The test results for the saws of the present invention are excellent in absolute criteria and generally good in all respects in relative evaluation of the reference saws. Thus, the top segment manufacturing process of the present invention, which combines the natural sintering of the segment with a free alloy powder of a specific composition, has a satisfactory result of significantly lowering the price compared to the known method using a mold.

The powders of the present invention have also proved to be suitable for the production of diamond beads for use in the manufacture of wire for granite cutting and are thus a preferred application of the present invention.

Beads had an outer diameter of 7.2 mm (beads for multi-wire devices) and an outer diameter of 11 mm (beads for single-wire devices) and were prepared by the following method:

Preparation of the particles according to the method as described above using the powder of the invention (85% / 15%) with FeP added;

Mixing the particles with standard or titanium coated diamond according to the test mode;

Cold pressing the particle / diamond mixture to obtain a green element having a density of about 65% of theoretical density;

The granulation binder is removed at 590 ° C .;

Sintering at 900 ° C .; Also

Soldering at 900 ° C. with solder containing 72% Ag and 28% Cu to ensure adequate bonding to the steel sleeve serving as the support.

Binder removal, sintering and soldering operations were carried out in a conveyor oven under H ₂ .

The resulting beads were threaded on a steel cable at a rate of 37 beads per meter (37 beads / m wire length) and reinforced by plasticizing the whole.

The wire was tested with a number of devices that cut various granites. The test results are listed in Table 5.

Test results on cutting wires (beads made using the powder of the invention with FeP added) Standard or titanium coated diamond Standard diamond Titanium coated diamond Initial outer diameter (ø) 7.2mm 11 mm 11 mm Final outer diameter (ø) 5.3mm 8.6mm 8,4mm Ø, Steel Support 5.0mm 8 mm 8 mm Cutting speed 0.9 to 1.1 m ² / h 0.8m ² / h 0.8m ² / h Service life 10.3m ² / m Length of ship 14m ² / m Length of ship 36m ² / m Length of ship

These results are generally satisfactory and show that the present invention can produce high performance diamond beads at substantially less cost than using conventional methods. In contrast, conventional wire using titanium coated diamond has a service life of 28 m ² / m linear length.

In general, the powder of the present invention exhibits excellent cold compressibility when used in pure form, and in particular, when obtained by mixing powder (I) and powder (II) as described above, an appropriate density at a temperature of 900 ° C. or higher is obtained. (97% of theory density). Hardness after sintering is not sufficient for granite cutting, but marble cutting can be expected to be possible. However, addition of 15% iron phosphide or nickel phosphide improves the density and hardness of the sintered element to a level capable of performing granite cutting.

For the purpose of comparison, the following tests were carried out to demonstrate the need for free alloy powders or mixtures of these powders in the present invention to obtain the desired results.

As shown in Table 6, the mixture, or "mixture (1)", was prepared under CO ₂ for 50 minutes using commercially available Fe, Co and Cu powders.

Characteristics of the mixture (1) element Average Fisher Particle Size, Fisher Diameter (ø) (μm) Weight percentage Iron (%) 4 50 Cobalt (%) 1.5 15 Copper (%) 3 35 Oxygen (%) - 0.8 Fisher diameter (ø) of the mixture (1) (μm) - 3.46

The weight percentage of the metal is expressed without oxygen.

The composition is the median of the composition range of the prealloy according to the present invention.

To 85% by weight of this mixture 15% by weight of BASF's 10% iron phosphide (FeP) having the same quality as in the above test was added (according to the same manner as above). The composition of this mixture (2) is as follows (Table 7):

Composition of mixture (2) element Weight percentage Iron (%) 56 Cobalt (%) 12.75 Copper (%) 29.75 sign 1.5 Oxygen (%) 0.95 Fisher diameter (ø) of the mixture (2) (μm) 2.99

The weight percentages of metal and phosphorus are expressed without oxygen.

For the two mixtures, the PS21 type element was pressed at 200 MPa.

The average density of the elements, calculated using size and weight, is shown in the following table (Table 8):

Percentage of theoretical density of drawn elements Mixture (1) Mixtures (2) Percentage of theoretical density of drawn elements 64.4% 62.1%

Green elements were sintered at 850, 900, 950 and 1000 ° C. The density, HB hardness and HRB hardness, expressed as a percentage of theoretical density with respect to the above elements, were measured in the same manner as described above for the elements produced in the present invention.

After sintering the following results were obtained (Tables 9 and 10):

Sintering result of the mixture (1) Sintering Temperature (℃) % Of theoretical density HB hardness HRB Hardness 850 91.5 99 53.6 900 91.3 117 66.8 950 89.1 96 51.8 1000 88.6 94 51.5

Sintering result of the mixture (2) Sintering Temperature (℃) % Of theoretical density HB hardness HRB Hardness 850 92.6 136 75.3 900 93.8 177 87.4 950 97.2 202 93.1 1000 98.4 213 95.8

In reviewing the above-mentioned results, it can be seen that, in contrast to the free alloy powder according to the present invention, the two commercial metal powder mixtures exhibit the following characteristics:

Very similar particle sizes,

-Better cold compressibility,

-After sintering, the compactness is greatly reduced and the hardness of HB and HRB is lowered,

-Due to the large initial particle size of the component, the structure of the sintered element is very rough.

Under the above conditions:

Diamond tools made from such commercial metal powder mixtures have poor diamond retention due to their high porosity (ie low diamond adhesion in the metal substrate);

It exhibits much lower tool performance (cutting speed and service life) than free alloy powders (pure or iron phosphate type) according to the invention with similar composition and particle size.

The powders of the invention, in particular the powders containing additives, can be easily granulated to enable the production of small thickness segments and diamond wires in a low cost process. As a powder state and a particle state, it can be easily sintered in the presence of diamond in a fixed oven or a conveyor oven. Therefore, the conventional problem can be solved.

The powder of the present invention can be suitably used also when manufacturing a cutting tool through a process other than the above-described method.

Claims (13)

Prealloy metal powder for use in the manufacture of cutting tools following sintering, the composition of which is by weight: Fe = 48-52% Co = 14 to 19% Cu = 32-37% Free alloy metal powder, characterized in that no more than 1.2% of O, and the remainder are impurities as a result of the preparation. The method of claim 1, A free alloy metal powder, wherein the particles have a Fisher diameter of 1 to 3 µm. A free powder comprising a metal powder according to claim 1 or 2 and also a mixture comprising at least one sintering auxiliary additive, the mixing ratio of which is 80 to 90% by weight of the powder and 10 to 20% by weight of the additive. Alloy metal powder. The method of claim 3, wherein And the sintering auxiliary additive is a phosphide of iron, nickel, copper or cobalt, a mixture of at least two kinds of the phosphides, or a composite phosphide of at least two kinds of the metals. The method according to any one of claims 1 to 4, Obtained by mixing a first powder and a second powder and optionally adding a sintering auxiliary additive, wherein the first powder and the second powder have respective properties as follows: For the first powder, * Fe = 27 to 32% * Co = 24 to 28% Cu = 42-47% * O (oxygen) is 1% or less, and the remainder is the resulting impurities, For the second powder, * Fe = 75 to 80% * Co 5% or less Cu = 17-22% * 1% or less of O (oxygen), and the rest are impurities resulting from the preparation. The method of claim 5, Preferably, the fischer diameter of the first powder particles is 0.8 to 1.5 mu m, the fischer diameter of the second powder particles is 3.0 to 4.0 mu m, and the fischer diameter of the powder obtained by mixing is 1 to 3 mu m. Metal powder. 12. A method for producing a diamond cutting tool comprising, in particular, mixing prealloy metal powder and diamond, cold pressing the mixture, and sintering the compacted mixture, wherein the metal particles are prepared according to claims 1 to 6 Manufacturing method characterized in that the kind according to any one of the claims. The method of claim 7, wherein The sintering is a manufacturing method, characterized in that the natural sintering. The method according to claim 7 or 8, Said tool is a cutting segment of a diamond saw. The method according to claim 7 or 8, Said tool is a diamond bead for cutting wire. The method according to any one of claims 7 to 10, The powder is a production method, characterized in that the kind according to claim 5 or 6. 10. A diamond saw, comprising a cutting segment secured to a metal disk periphery, the segment being manufactured by the method according to claim 9. A cutting wire comprising a diamond bead threaded in a cable, said bead produced by the method according to claim 10.