JPH0551267A - Sintering material for tool - Google Patents

Abstract

PURPOSE:To improve the wear resistance or the like of a sintering material at a high temp., in a sintering material for a tool constituted of hard perticulate matters of cubic BN or the like and a metallic compound series bonding phase by preliminarily coating the hard perticulate matters with a film contg. metals in the bonding phase components. CONSTITUTION:Hard perticulate matters 1 of cubic boron nitride, diamond or the like and bonding phase component 3 selected from the nitrides, borides and carbides of metallic elements or their combined compounds (e.g. TiN) are prepd. Then, the hard perticulate matters 1 are coated with a film 2 of the same components as the bonding phase components (e.g. TiN film) or is coated with a film 2 of a compound other than that of the metallic elements in the bonding phase components. Next, the hard perticulate matters 1 coated with the film 2 and the bonding phase components 3 are mixed to manufacture a sintering material for a tool. In this way, because the surface of the hard perticulate matters 1 is coated with the film 2, the adhesion between the hard perticulate matters 1 and the bonding phase 3 improves, and as a result, its sinterbility improves, by which a cutting tool or the like to be manufactured shows high wear resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered material for tools used in cutting and plastic working of high hardness materials such as hardened steel and cemented carbide or heat resistant alloys.

[0002]

2. Description of the Related Art When processing hardened steel or high hardness materials such as nickel-base heat-resistant alloys and cobalt-base heat-resistant alloys, generally, carbide powder of refractory metal such as tungsten is used for iron-based metals such as iron, cobalt and nickel. Cemented carbide cemented by sinter has been used. In recent years, the above-mentioned cemented carbide is being adopted not as a tool but as an object to be processed, and in order to meet severe requirements for processing conditions, sintered diamond and cubic boron nitride ( Hereinafter, those using a sintered body or the like will be developed. Sintered diamond is obtained by sintering diamond powder particles under high temperature and high pressure using cemented carbide as a binder, but is fundamentally unsuitable for processing steel or the like having a strong affinity with carbon. In this respect, the CBN sintered body, which has the second highest hardness after diamond, has little reaction with iron-based metals, so it can be applied to all processed objects other than diamond, especially hardened materials such as hardened steel and cemented carbide, as well as nickel-based materials. It is effective for processing heat-resistant alloys and cobalt-based heat-resistant alloys.

In a conventional CBN sintered body, ceramics such as titanium carbide and titanium nitride, which serve as a binder phase, are mixed alone with CBN powder particles, and a metal component is added to improve the sinterability, and these are mixed at high temperature and high pressure. Most are sintered below. As the material of the binder phase, in addition to the above, carbides of silicon or zirconium, nitrides of silicon or zirconium, intermetallic compounds of aluminum and titanium, intermetallic compounds of aluminum and zirconium, and the like are known.

[0004]

In the tool using the conventional CBN sintered body, the hardness of the binder phase is lowered in the high temperature region. Therefore, when the tool itself is heated to a high temperature,
The powder particles of CBN tend to fall off from the binder phase, often leading to a decrease in wear resistance. In addition, when such a tool is incorporated into a processing machine that performs automatic operation for a long time, it is absolutely necessary to avoid sudden tool loss from damage to the processing machine or a decrease in equipment operating rate. However, the conventional CBN sintered body of this kind has not been sufficiently tough enough to pursue high wear resistance.

In view of such circumstances, the present invention provides a sintered material for a tool, which has an improved ability to carry hard powder particles such as CBN in the binder phase and which has improved wear resistance particularly at high temperatures. To aim.

[0006]

[Means for Solving the Problems] As a result of various studies to achieve the above object, needle crystals of zirconium oxide, aluminum nitride and silicon carbide containing titanium nitride as a main component and aluminum oxide as a binder phase. Using a mixed powder grain added as a sub-component at a fixed ratio, and further coating the cubic boron nitride powder grain with the same as the binder phase component or other compound of the metal element of each binder phase component. It was found that, by this, the capability of supporting CBN powder particles in the binder phase is increased, and the wear resistance and fracture resistance are improved. Further, the effect of improving wear resistance and fracture resistance by applying a coating of the same compound as the binder phase component or another compound of the metal element of each binder phase component is that diamond powder grains as well as CBN powder grains are effective. It has been found that it is developed in a sintered material for tools, which is composed of hard powder particles such as the above and a binder phase selected from nitrides of metal elements, borides, carbides, and composites thereof. The present invention has been made based on such findings, the sintered material for a tool according to the present invention, cubic boron nitride, hard powder particles such as diamond, nitride of metal elements, boride, carbide, and In a sintered material for tools comprising a binder phase selected from these compounds, the hard powder particles are coated with the same binder component as the binder phase, or with a coating of another compound of a metal element of each binder phase component. Characteristically, 40 to 70% by volume of cubic boron nitride powder particles, 15 to 45% by volume of titanium nitride which is the main component of the binder phase, and aluminum oxide, zirconium oxide and aluminum nitride which are the minor components of the binder phase. And 15 to 35% by volume of mixed powder particles with acicular crystals of silicon carbide, and the composition of the auxiliary components of the binder phase is 50 to 65% by volume of aluminum oxide and 1 to 5% by volume of zirconium oxide. , A sintered material for a tool having a ratio of 20 to 40% by volume of aluminum nitride and 5 to 15% by volume of needle crystals of silicon carbide, which is the same as the binder phase component in the powder particles of cubic boron nitride, or each binder phase. It is characterized in that a film of another compound of a metal element as a component is applied.

In the present invention, the coating applied to the hard powder particles may be formed by, for example, the CVD method. Also, CBN
The composition applied to the powder particles is preferably TiN _x (x = 0.9 to 1.1).

The invention will now be described in comparison with conventional CBN sintering tools.

First, the wear condition of a conventional CBN sintering tool will be described with reference to the drawings. FIGS. 5 (a) and 5 (b) schematically show the wear condition of the flank and rake face of the CBN sintering tool when the hardened steel is cut. As shown in both figures, in the cutting process, when the CBN grains 11 of the tool edge portion 10 fall off from the binder phase 12, and the dropped CBN grains 11 pass through the boundary between the work material 13 and the flank 10a, It is considered that the ridge a is left on the flank 10a, and the ridge a determines the flank wear width (V _B ), that is, the wear resistance. In the figure, 10b indicates a rake face. And
When the CBN grains 11 come off, the portion of the bonding phase 12 of the cutting edge portion having the function of supporting the CBN grains 11 in contact with the work material 13 recedes due to abrasion, and external force (cutting force, thermal stress, etc.) When the force for supporting the CBN grains 11 is exceeded, CB
It is considered that the CBN grains fall off from the cutting edge portion 10 due to the separation of the N grain 11 and the binder phase 12 at the grain boundary or the breakage of the binder phase 12. Further, from the above, it is considered that in the CBN sintering tool, the CBN grains have a function as a cutting edge and the binder phase has a function as a carrier for the cutting edge.

From this point of view, let us consider the functions of the CBN grains and the binder phase when a CBN sintered tool is produced from the sintered material for a tool according to the present invention. First, CB as a cutting edge
Since N grains have hardness second only to diamond and have low reactivity with iron group metals, which are the drawbacks of diamond, they can be expected to have high wear resistance and have the functions required for a cutting edge. It is considered to be fully satisfied.

On the other hand, considering the above-mentioned wear mechanism, it is considered that the binder phase needs to have the following four characteristics. That is, in order to increase the wear resistance of the binder phase and suppress the receding speed of the binder phase of the cutting edge due to wear to be low, the hardness at the cutting edge temperature during cutting is high, and the work material (steel, Low reactivity with iron group metals) is required. Further, in order to prevent the CBN grains and the binder phase from coming off due to delamination at the grain boundary, the CBN grains diffuse and react with each other to firmly adhere to each other, and further, the binder phase is a sintered body. Therefore, it is required that the sinterability be good (becomes densified at a low sintering temperature), and that the strength and toughness be high.

Therefore, let us consider the binder phase according to the present invention with respect to each of these characteristics. FIG. 1 shows the hardness of various binder phases of a CBN sintered tool. Generally, the periodic table 4a, 5a, 6a group transition metal carbides, borides,
High hardness of nitride. Titanium nitride (hereinafter referred to as TiN) used in the present invention is contained in these and has high hardness, and aluminum oxide (hereinafter referred to as alumina or Al ₂
(Denoted as O ₃ ) has a high hardness at the cutting edge temperature during cutting, and therefore the binder phase in the present invention is considered to satisfy the above-mentioned characteristics.

FIG. 2 shows the free energy of formation (ΔG _T °) for steel at the cutting edge temperature during cutting of various binder phases.
When such free energy of formation is used as an index of reactivity with steel or the like, carbides and nitrides of transition metals of Groups 4a, 5a and 6a of the periodic table, that is, TiN and aluminum nitride used in the present invention (hereinafter referred to as AlN) It is assumed that the oxides such as alumina and zirconium oxide (hereinafter, referred to as ZrO ₂ or zirconia) used in the present invention have low reactivity, and that the binder phase used in the present invention satisfies the above-mentioned characteristics. Conceivable.

When the reactivity between the binder phase and the CBN grains is similarly evaluated using the free energy of formation as an index, it is possible that the reaction occurs at the sintering temperature (1400 to 1800 ° C.) Among the carbides, borides, and nitrides of transition metals of the 4a, 5a, and 6a groups of the index table, TiN, AlN,
In addition to niobium nitride (hereinafter referred to as NbN), it is limited to several kinds. Therefore, the present invention uses T
Since AlN is contained as one component of the iN subcomponent, it is considered that the above-mentioned characteristics are also possessed.

Next, in order to investigate the above-mentioned characteristics concerning the soundness of the sintered body, CBN containing only TiN as a binder phase.
A sintering tool was manufactured and a cutting test was performed. CBN made
The sintering tool comprises 50% by volume of CBN particles having a particle size of 1 to 3 μm,
50% by volume of TiN powder having a particle size of 0.5 to 2 μm was mixed in a ball mill, and a pressure of 50 kbar (hereinafter, referred to as Kb) was used and a sintering temperature of 1400 to 1750 using a conventionally known ultrahigh pressure generator described later. Ultra high pressure sintering was carried out under the conditions of ℃ and sintering time of 0.5 to 30 minutes, and this was bladed into a tool shape. This is subjected to a cutting test [workpiece SUJ2 (hardness H _RC 62 or more), cutting speed 100 m / min, feed 0.1 min / rev,
When subjected to a cutting depth of 0.1 mm], it did not reach the wear resistance and fracture resistance of the conventional CBN sintering tool regardless of the conditions such as sintering temperature and sintering time. Further, when the fracture surface of the CBN sintered tool was observed under a microscope, it was observed that the fracture occurred at the TiN grain boundary.

In the present invention, AlN having a high sinterability and having the above-mentioned characteristics, added to TiN, has the following characteristics and has a high activity during sintering.
Is added to obtain a sintered body with high soundness. Further, by adding a small amount of zirconia to alumina, the sinterability is improved, and further, toughness is improved by adding a needle crystal of silicon carbide (hereinafter referred to as a SiC needle crystal).

Further, TiN which is a binder phase component is CBN.
It is difficult to react directly with, but by applying the coating of the present invention, the TiN coating of CBN grains and TiN which is a binder phase component.
Can be easily sintered, greatly improving the sinterability,
The characteristics of are satisfied.

FIG. 3 schematically shows the structure of the sintered material for a tool of the present invention, in which 1 is CBN powder, 2 is TiN coating, and 3 is.
Indicates a bonded phase.

CBN is mainly used as a sintered material for tools, and if it is less than 40% by volume, it becomes difficult to reflect the hardness of CBN itself, and sufficient wear resistance cannot be obtained. On the contrary, if the CBN content exceeds 90% by volume, a part of the CBN undergoes a phase transition in the hexagonal crystal during the sintering to deteriorate the sinterability, so that minute chipping or chipping occurs due to the decrease in toughness.

On the other hand, TiN, which is the main component of the binder phase, has the characteristics of high melting point, high hardness, and low reactivity with steel, and the hardness is in the precision cutting conditions of ordinary hardened steel. It is one of the materials that shows the highest value at the cutting edge temperature. Further, it is considered that TiN shows a rapid decrease in hardness from around 1000 ° C., and is softened in a high temperature region above the sintering temperature (1400 ° C.) to easily flow. Therefore, it can be inferred that TiN can flow between CBN grains during sintering, which is effective for densifying the sintered body.
Further, since TiN is formed by coating TiN on CBN particles, good sinterability can be expected, and the binder phase and CBN particles are firmly bonded to each other, and a sintered body having high soundness and good characteristics can be obtained. ..

Alumina, which is a subcomponent of the binder phase, is
It has high melting point, high hardness, low reactivity with steel, and excellent properties along with TiN as a material component of the binder phase as described above, but reactivity with CBN grains cannot be expected.
Therefore, when alumina is used as the main component of the binder phase, it is necessary to add a metal component or the like in order to improve the reactivity with the CBN grains, but in the present invention, AlN having high activity during sintering is used. By adding it, the sinterability is greatly improved. Thereby, the soundness as a CBN sintered material is improved, and a material having high wear resistance and chipping resistance can be provided as a tool material. In the present invention, alumina and AlN
Is added and sintered so as to fill the gap between the main constituent elements of the CBN sintered material composed of CBN grains and TiN grains, and has a role of adhering the TiN grains and the TiN grains to each other. Fulfill

Considering the role of alumina, it is essential that the alumina itself has good sinterability, and further improvement of toughness is required. In the present invention, however, zirconia and carbonized alumina are used. By using a composition containing silicon needle crystals as an auxiliary component of the binder phase, the sinterability and toughness of the binder phase are improved.

Here, the composition of the subcomponents will be described. As described in the above description, the binder phase of the CBN sintered material itself needs to be a tool having high wear resistance. Therefore, it is not possible to arbitrarily select the composition, but the composition component becomes important. Therefore, a tool material with only the binder phase with different composition components was prototyped, and wear resistance was evaluated by a cutting test. Conditions are cutting speed 170m / min, feed 20μm /
Spindle rotation, notch 20 μm, work material SUJ2 (hardness H
I went to _RC 62).

First, when the compositional components were investigated by limiting the components to alumina and aluminum nitride, when the volume% of aluminum nitride with respect to the volume% of alumina was 1/3 or less, the brittleness of alumina appeared and the flank wear width became 70 μm or more. Also, similarly, it was found that when the hardness was 4/5 or more, the hardness of aluminum nitride was low, and the flank wear width was 70 μm or more. From this study, it was found that alumina and aluminum nitride, which are subcomponents, need to be mixed in the range of 3: 1 to 5: 4 (volume% ratio).

Next, regarding the amount of addition of SiC needle crystals to the two-component system mixed in the above-mentioned appropriate range, from the same experiment, if the addition amount is less than 5% by volume, the effect of addition does not appear.
It was confirmed that if the content is 5% by volume or more, the sinterability is lowered and the toughness is rather lowered.

Further, the effect was examined by changing the amount of zirconia added to the three-component system in which SiC needle crystals were added to the above two components. The results of the test are shown in FIG. 4. When zirconia is added in an amount of less than 1% by volume, the effect of the addition does not appear, while when added in an amount of more than 5% by volume, the sinterability is relatively high. It was found that the abrasion resistance was low due to the poor quality. The evaluation of wear resistance here was carried out under the same conditions as described above.

Next, the composition (blending ratio) of the CBN grains and the main and subcomponents of the binder phase will be described. Secondary components (alumina 50 to 65% by volume and zirconia 1 to 5% by volume) are present in the gaps generated when the CBN particles and the main component of the binder phase are mixed.
And AlN 20 to 40% by volume, SiC needle crystals 5 to 15
(Volume% mixed powder), the secondary component fills the gaps between the CBN grains and the main component of the binder phase after sintering, and the sintered compact of the secondary component is connected in a mesh in the sintered body. Therefore, it is considered that it is theoretically necessary to add the auxiliary component in an amount of 15% by volume or more.

Considering the mixing ratio of the CBN grains and the main component of the binder phase, as described above, the minimum content of the CBN grains is preferably 40% by volume, and the subcomponent of the binder phase is the minimum amount (15% by volume). When, the ratio of the main components becomes maximum. Therefore, the maximum proportion of the binder phase main component is 45% by volume.
Becomes On the other hand, it is necessary to add not less than 15% by volume of the main component in order to make the main component of the binder phase itself have a network-like structure like the sub-component.

Further, when the amount of the subcomponent added in the binder phase exceeds the amount of the main component added, the original wear resistance is impaired, so that the maximum proportion of the subcomponent becomes 35% by volume.

The sintered material for tools of the present invention described above is
It can be manufactured using a conventionally known ultra-high pressure sintering apparatus.
That is, first, the CBN powder particles and the main component and subcomponents of the binder phase are mixed in a predetermined mixing ratio by a ball mill or the like to obtain a uniform mixed powder. Next, the mixed powder is compacted by a compacting press or the like, and this is filled in a container made of a high melting point metal such as zirconium. After that, for example, by the ultrahigh pressure sintering technique described in New Ceramics (1988), Vol. 1, No. 6, P43, the temperature is 1400 to 1800 ° C and the pressure is 4
The pressure is set to 0 to 60 Kb, and the pressure and temperature are maintained for 0.5 to 30 minutes, followed by cooling to remove the pressure to produce a sintered body.

[0031]

EXAMPLES The present invention will be described below based on examples.

(Example 1) A TiN coating film was applied to a CBN having a particle diameter in the range of 1 to 3 micrometers (hereinafter referred to as μm) synthesized by a non-catalytic method by a CVD method. The treatment was carried out at a pressure of 600 torr and a temperature of 910 ° C. for 2 hours using TiCl ₄ , N ₂ and CH ₄ as raw material gases. The thickness of the film is 0.1 to 0.5 depending on the film formation rate on the plate-shaped single crystal CBN.
It is considered to be μm.

Next, the coated CBN grains and the binder phase component were mixed. The binder phase component is T having an average particle size of 0.5 to 1.5 μm.
A mixed powder of iN, alumina having an average particle size of 0.3 μm, zirconia, AlN, and SiC needle crystals (57: 3:
30:10 volume ratio) and these volume ratios are 4
5:30:25 (= CBN: TiN: Al ₂ O ₃ / ZrO
₂ , AlN, and SiC needle crystals) are charged into a small planetary motion mill lined with tungsten carbide (hereinafter referred to as WC) -based cemented carbide, and the mixture is further mixed. For the purpose of accelerating, an amount of methyl alcohol corresponding to 35% of the total volume of these powder particles was added to the inside of the mill, covered with a lid, and kneaded for 3 hours. Then, the lid of the mill was removed in an inert gas atmosphere, the mill was heated to 120 ° C. to evaporate methyl alcohol, and the kneaded raw material powder was dried. On the other hand, sodium chloride (hereinafter referred to as N
NaCl, which is formed by press-molding powder particles of (aCl) into a cylindrical shape having an inner diameter of 8 mm and a length of 10 mm.
A lower lid made of NaCl made in the same manner is integrally attached to a container body made of the same, and a zirconium foil having a thickness of 20 μm is attached to the inner surface thereof, and further, a 7.8 mm diameter and 2 mm thick Prepare a disc on which a WC-based cemented carbide disc is placed.

Then, the raw material powder after completion of the drying is preliminarily compacted to a thickness of 6 mm by a powder compacting press or the like, and the compact is compacted in an inert gas atmosphere onto the disc in the container body. .. Then, the same WC-based cemented carbide disc as described above is placed on top of this, and a thickness of 20
After stacking zirconium foils having a thickness of μm, an NaCl upper lid prepared in the same manner as described above is fitted into the container body, and the raw material powder is sealed in the container including the container body, the lower lid and the upper lid.

Next, the container described above was attached to the ultra-high pressure generator, the pressure of 50 Kb and the temperature of 1650 ° C. were maintained for 30 minutes, the raw material powder was sintered, and a circle in which WC-based cemented carbide was bonded to both ends. A columnar sintered material for tools was obtained. Then, the sintered material for a tool is cut out in a state where the discs are bonded to finish a cutting edge for a bite, and this is prepared in advance with a rectangular WC-based cemented carbide tip through silver brazing. Fixed, rake angle 0 degrees, clearance angle 5 degrees, nose radius of curvature 1
Created a millimeter cutting tool.

Using this cutting tool, a high carbon bearing steel (SUJ2) having a Rockwell hardness of 62 and having a round bar shape has a cutting speed of 170 meters per minute and a cutting depth of 20 μm.
After turning by a distance corresponding to a length of 100 meters so that the feed rate of the cutting tool is 20 μm per rotation of the main spindle, the wear width of the flank of the cutting edge and the C constituting this cutting edge
The Vickers hardness of the BN sintered material was measured by changing the ratio of each powder grain constituting the raw material powder. Note that cutting oil was spray-supplied during the turning process.

The results of these measurements are shown in Table 1. By the way, the Vickers hardness of a commercially available CBN sintering tool using a composition obtained by adding a metal component to titanium nitride as a binder phase is 25.
00, the wear width of the flank of the cutting edge was 45 μm. In addition, the characteristics of the conventional sintered tool material without the TiN coating are shown for comparison.

[0038]

[Table 1]

As is clear from the results shown in Table 1, CB
It can be confirmed that when the TiN coating is applied to N, the flank wear width is reduced probably because the sinterability is improved, and the wear resistance is improved.

Example 2 In the same manner as in Example 1, CBN having a particle size of 1 to 3 μm was formed by titanium carbide (post-TiC) by CVD.
(Notation) was applied. Ti is used as a raw material gas
Cl ₄ , CO ₂ and CH ₄ were used, the pressure was 600 torr, and the temperature was 1025 ° C. for 2 hours. This was mixed with a binder phase component having the same components as in Example 1 to obtain a sintered material for a tool by an ultra high pressure sintering method. The sintering conditions were a pressure of 55 Kb and a temperature of 1750 ° C. When this was attached to a blade and used as a tool and a high carbon bearing steel (SUJ2, Rockwell hardness 62) was subjected to a cutting test as a work material, almost the same results as in Example 1 were obtained. This is probably because TiN, which is the main component of the binder phase, and TiC applied as a coating film are both Ti compounds, and TiCN, which is a composite compound, was formed and bonded, so that the grain boundary between CBN and the binder phase was strengthened. Be done.

(Example 3) In the same manner as in Example 1, diamond having a grain size of 4 to 8 µm was coated with a TiN film by the CVD method. The CVD processing conditions were the same as in Example 1. Further, a cutting test was conducted using the same binder phase component as in Example 1 after the ultrahigh pressure sintering to obtain a cutting tool. The work material is a cast iron round bar (diameter 60 mm), cutting speed 200 m / min, depth of cut 0.1 mm,
The feed was evaluated at 0.1 mm / spindle one revolution. As a result, the surface roughness of the work material after cutting at the same cutting distance is 3 compared with the commercially available diamond sintered tools having a metallic binder phase.
0% improvement (compared to conventional surface roughness of 3.2 μm, surface roughness
2.2 μm).

[0042]

In the sintered material for a tool of the present invention, the surface of hard powder particles such as CBN powder particles is coated with the same coating film of TiN as the main component of the binder phase by, for example, the CVD method.
The adhesion between the powder particles and the binder phase was improved. As a result, sinterability was improved and higher wear resistance was exhibited. Further, it is considered that the coating of hard powder particles such as CBN powder particles contributes to enhancing the cleanliness of the surface of the hard powder particles, and from this point also improvement of sinterability is expected.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing hardness of a binder phase material of a CBN sintering tool.

FIG. 2 is an explanatory diagram showing the reactivity of a binder phase material of a CBN sintering tool with a work material.

FIG. 3 is a schematic diagram of the composition of the sintered material for a tool of the present invention.

FIG. 4 is an explanatory view showing an experimental result when zirconia is added to alumina.

5A and 5B are a schematic diagram illustrating wear of a CBN sintering tool and an enlarged view of an A portion thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CBN powder particles 2 TiN coating 3 Binder phase 10 Tool edge part 10a Flank surface 10b Rake surface 11 CBN particles 12 Binder phase 13 Work material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Kakuda 1-1 Hideoura-cho, Nagasaki-shi, Nagasaki Nagasaki Research Laboratories, Mitsubishi Heavy Industries, Ltd. (72) Fukushi Yamada 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd.

Claims (2)

[Claims] 1. A sintered material for tools comprising hard powder particles such as cubic boron nitride and diamond, and a binder phase selected from nitrides of metal elements, borides, carbides, and complex compounds thereof. A sintered material for a tool, characterized in that the hard powder particles are coated with the same compound as the binder phase component or with another compound of a metal element of each binder phase component. 2. Cubic boron nitride powder particles 40 to 70% by volume
And 15 to 45% by volume of titanium nitride, which is the main component of the binder phase
And 15 to 35% by volume of mixed powder particles of acicular crystals of aluminum oxide, zirconium oxide, aluminum nitride, and silicon carbide, which are subcomponents of the binder phase, and the composition of the subcomponent of the binder phase. Is aluminum oxide 50-6
5% by volume, zirconium oxide 1-5% by volume, aluminum nitride 20-40% by volume, and silicon carbide needle crystals 5-1
A sintered material for tools with a ratio of 5% by volume, characterized in that powders of cubic boron nitride are coated with the same compound as the binder phase component or another compound of the metal element of each binder phase component. And sintered materials for tools.