JP3366659B2 - Heterogeneous layer surface-finished sintered alloy and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cutting tool such as a turning tool, a milling tool, a drill and an end mill, an abrasion resistant tool such as a die, a punch and a slitter, a civil construction tool such as a cutter bit or a nozzle for chemicals, a watch exterior. The present invention relates to a different layer surface-tempered sintered alloy suitable for various tools represented by corrosion-resistant tools such as parts or tool parts, and a method for producing the same.

[0002]

2. Description of the Related Art A cemented carbide or a cermet sintered alloy composed of a hard phase containing tungsten carbide, titanium carbide or titanium nitride as a main component and a binder phase containing Co and / or Ni as a main component is It is used in various tools, depending on the application of the tool, the grain size and type of the hard phase,
The amount and type of binder phase and the type and amount of additives are adjusted to maintain the balance between wear resistance and toughness. However, the wear resistance and toughness of these sintered alloys have the trade-off tendency that when one is improved, the other is decreased, so it is a very difficult problem to improve both at the same time.

To solve this problem, there is an alloy in which the compositional composition of the vicinity of the surface of the sintered alloy is different from that of the inside, and a typical one is Japanese Patent Laid-Open No. 2-209.
No. 448, No. 2-209449, No. 2-15139, No. 2-93036,
JP-A-55-83517 and JP-A-54-877.
No. 19 publication is proposed.

[0004]

Among the prior arts in which the composition structure near the surface of the sintered alloy and that inside the sintered alloy are made different, JP-A-2-209448 and JP-A-2-20944 are known.
The sintered alloy disclosed in Japanese Patent No. 9 has a surface region formed with a smaller amount of binder phase than in the interior of the alloy. However, the surface regions of the cemented carbides disclosed in these publications have a decreased amount of binder phase, and the amount of binder phase does not change continuously, and therefore wear resistance and toughness are improved. At the same time, there is a problem that it is difficult to improve.

Japanese Unexamined Patent Publication Nos. 2-15139 and 2
The TiCN-based cermet disclosed in JP-A-93036 is N
The hard phase in the vicinity of the surface is nitrided by changing the partial pressure for ₂ and the amount of the binder phase is reduced, so that the surface has higher toughness and hardness than the inside. However, although the TiCN-based cermets of both publications have improved wear resistance of the surface portion, they are still insufficient in fracture resistance and plastic deformation resistance, so that all of these characteristics should be improved at the same time as wear resistance. However, there is a problem that the application is practically limited.

The sintered alloy disclosed in JP-A-55-83517 has a toughness improved by forming a surface softening layer having a hardness lower than that of the inside of the alloy. However, since the surface softening layer deteriorates the wear resistance and the plastic deformability, it is difficult to simultaneously improve the wear resistance and the toughness. On the other hand, the coated cemented carbide disclosed in JP-A-54-87719 is WC-TiC (TiN) -containing nitrogen.
By sintering the (Co) -based cemented carbide in a vacuum,
WC-C without (W, Ti) CN phase (β phase) on the alloy surface
It is a high toughness genus composed of o. But,
Although the surface layer containing no β phase has a higher toughness than the inside, there is a problem that its application is limited because the wear resistance and the plastic deformation resistance at high temperature are significantly lowered.

Further, in all of the above-mentioned prior arts, the same surface layer is formed on a part or the whole surface of the sintered alloy, so that various kinds of damages caused when various tools are used are prevented. Not all are available. For example, the flank of the cutting tool must have hardness, that is, wear resistance, the R portion of the cutting edge must have plastic deformation resistance, and the rake surface must have toughness, crater resistance, and thermal shock resistance.

The present invention solves the above-mentioned problems, and specifically, at least two surfaces of the sintered alloy are differently diffused into the surface layers from the respective surfaces to the inside of 0.1 to 5 mm. By making the elements exist as if they were gradually reduced, properties such as wear resistance, plastic deformation resistance, toughness, thermal shock resistance, corrosion resistance, and oxidation resistance are individually imparted to each surface layer, and as a result, quench-bonding is performed. An object of the present invention is to provide a heterogeneous surface-tempered sintered alloy having substantially improved practical performance of gold as a whole and a method for producing the same.

[0009]

The present inventors have found that in conventional sintered alloys of uniform composition and uniform structure, the toughness is improved by improving the wear resistance and the plastic deformation resistance by adjusting the amount of the binder phase and the grain size of the hard phase. ， It was inferior in thermal shock resistance, and conversely, improvement in toughness and thermal shock resistance resulted in deterioration in wear resistance and plastic deformation resistance, and the damage state of the sintered alloy after use was examined. In the gold manufacturing process, it is easy to diffuse during sintering of the powder compact and the surface layer has hardness, that is, wear resistance,
Elements that can impart plastic deformation resistance, toughness, thermal shock resistance, corrosion resistance, oxidation resistance, etc. are individually selected and contacted with at least two surfaces of the powder compact so that they have an inclination over a certain surface area. It has been found that when the above elements are diffused, the above characteristics are individually imparted to at least two surfaces of the sintered alloy, and the practical performance of the sintered alloy is significantly improved as a whole. The present invention has been completed based on this finding.

That is, the different surface-tempered sintered alloy of the present invention comprises 1 to 25% by volume of the binder phase and the remaining 4a of the periodic table.
In a sintered alloy composed of at least one hard phase in carbides and nitrides of Group 5a and 6a metals and their mutual solid solutions, and an inevitable impurity, the binder phase is 50% of the binder phase.
Volume% or more is at least one of Co, Ni, and Fe, and the sintered alloy is a chip obtained by sintering a powder compact.
At least two surfaces of the chip have respective surface layers within 0.1 to 5 mm from the respective surfaces, and each surface layer comprises Cr, Mo, V, Ta, A.
l, Zr, Nb, Hf, W, Si, B, P, C, N at least one kind of diffusing element gradually decreases from the surface toward the inside, and among the diffusing elements existing in the surface layer, ,
At least one is different from the diffusing elements present in other surface layers.
It is characterized by becoming .

The binder phase in the sintered alloy of the present invention is C
When at least one of o, Ni and Fe or a mutual alloy thereof is used, or 50% by volume or more of the binder phase is C
When at least one of o, Ni and Fe and the rest is Cr, Mo, Al, Ti, W and Si, for example, Co and / or Ni, or C
It is preferable that the binder phase contains 10% by volume or less of the above diffusion element in o and / or Ni. In addition to this binder phase, the hard phase constituting the sintered alloy of the present invention is composed of at least one of carbides, nitrides and mutual solid solutions of metals of Groups 4a, 5a and 6a of the Periodic Table, Among these, for example, in the case of only tungsten carbide, in the case of tungsten carbide and carbides of group 4a, 5a, 6a metals of the periodic table, carbonitrides and mutual solid solutions thereof (excluding tungsten carbide alone), titanium carbide , Or titanium carbonitride core with Ti and Cr, Mo, V, Ta, Nb, W
It is particularly preferable that the hard phase has a cored structure surrounded by an outer peripheral portion of a carbide solid solution or a carbonitride solid solution with one or more selected from the above.

The relationship between the amount of binder phase and the amount of hard phase in the sintered alloy of the present invention is such that when the amount of binder phase is less than 1% by volume, the amount of hard phase relatively exceeds 99% by volume. When the strength of the sintered alloy is remarkably decreased, on the contrary, when the amount of the binder phase exceeds 25% by volume, the amount of the hard phase becomes relatively high.
It becomes less than the volume%, and as a result, the wear resistance and the plastic deformation resistance are significantly reduced.

The surface layer in the sintered alloy of the present invention is, in the case of a sintered alloy of a spherical body, a first surface layer extending from the surface of a part of the spherical body to the inside of 0.1 to 5 mm; In the case of a sintered alloy having a polygonal shape, it can be divided into a second surface layer having a distance of 0.1 to 5 mm from the other surface excluding the first surface layer and a similar third surface layer. 0.1 to 5 mm of the first surface layer from the surface of part or all of the divided surfaces, and 0.1 from the other surface excluding the first surface layer
It can be classified into a second surface layer of up to 5 mm inside and a third surface layer excluding the same first surface layer and second surface layer. Specifically, for example, in the case of a throw-away tip as a typical example of a cutting tool, the scooping surface is the first surface layer, the lateral flank is the second surface layer, and the front flank is the third surface layer. In the case of a chip with a breaker, the breaker portion has a first surface layer, the other scooping surface portion has a second surface layer, the lateral flank surface has a third surface layer, and the front flank surface has a fourth surface layer. In particular, in the case of a chip subjected to honing, the honing portion may be the fifth surface layer. In addition to the divided structure of the surface layer, the structure of the diffusing element in the surface layer is specifically, for example, Co-C in which the diffusing element is solid-solved in the binder phase existing in the surface layer.
r, Ni-Mo, Ni-Ti, Ni-Al, and optionally Ni ₃ A in the binder phase.
l, Co ₃ Si, Ni ₃ Ti, Co ₃ W, and the presence of an intermetallic compound such as Cr ₇ C ₃ , Mo ₂ C, (Ti, W) C, (in the binder phase in some cases. Ta, W)
To exist in a hard phase structure such as C, or to form a solid solution in the hard phase in the surface layer, for example, (Ti, Mo) C,
(Ti, Mo) CN, (Ti, W) C, (Ti, W, T
a) It can exist in the structure of CN.

The greatest feature of the sintered alloy of the present invention is that "at least two different diffusion elements among the diffusion elements are present in each surface layer on at least two surfaces of the sintered alloy. That means, specifically,
Cr is present in the above-mentioned first surface layer and is Co.
In contrast to the -Cr alloy, when W is present in the second surface layer and is the Co-W alloy,
Cr and C are present in the first surface layer, and Cr ₃
The second surface layer is Cr, while it is a compound of C _2.
In addition, when the alloy is a Co—Cr alloy, the first surface layer is TiN and the second surface layer is TiC.

It is also preferable that each surface layer gradually increases or decreases the relative concentration of the binder phase present in the surface layer from its surface toward the inside. Wear resistance and plastic deformation resistance are improved by decreasing the binder phase concentration of the surface layer from the inside excluding the surface layer, and by increasing it, toughness,
Since the thermal shock resistance is improved, when combined with the property improving effect of the above diffusion element, the property at a predetermined position can be further improved or a compound property can be imparted.

Particularly, the concentration of the diffusing element in the surface layer is 0.1 mm from the surface of the sintered alloy toward the inside.
Average concentration (Cs) of the diffusing element in the surface layer up to the average concentration (Ci) of the diffusing element in the inside excluding the surface layer
It is preferable that the ratio of Cs / Ci is 1.2 or more because the effect of improving the characteristics of each diffusing element is sufficiently exhibited. Regarding the concentration of the binder phase in the surface layer, the average concentration (bs) of the binder phase in the surface layer from the surface of the sintered alloy to 0.1 mm toward the inside and the average of the binder phase in the inside excluding the surface layer The ratio with the concentration (bi) is bs / bi
= 0.9 or less or 1.05 or more is preferable for enhancing the wear resistance, plastic deformation resistance or toughness, and thermal shock resistance of the surface layer. In addition to such composition and structure of the surface layer, in order to maximize the effect of the sintered alloy of the present invention according to the application or shape, the thickness of each surface layer of the sintered alloy is made uniform. Or they can be unequal.

When the thickness of each surface layer in the sintered alloy of the present invention is less than 0.1 mm, the effect of improving wear resistance, toughness, plastic deformation resistance, thermal shock resistance, corrosion resistance, and oxidation resistance is obtained. Is weak, and conversely, even if the thickness exceeds 5 mm, there is no remarkable effect on improving the above-mentioned various properties, and the thickness is set to 0.1 to 5 mm in consideration of manufacturing and cost reduction. .

The sintered alloy of the present invention can be produced by applying the conventional powder metallurgy method and the method for forming a powder compact such as centrifugal molding and cast molding. This is preferable in terms of easiness of adjusting the thickness of the surface layer, the gradient of the surface layer and the concentration gradient of the binder phase on the surface, workability and cost reduction.

The surface of the surface layer of the sintered alloy of the present invention having the surface layer having the above-mentioned constitution and / or the surface where the surface layer is not formed are partially or entirely covered with a thickness of 0.5 to 20 μm. It is preferable to form a coating film composed of an outer layer because not only the effects of the surface layer and the coating film are added but also the life is remarkably improved. This outer layer is 4a of the periodic table,
At least one of carbides, nitrides, borides, sulfides, Al, Si oxides, nitrides, carbides and their mutual solid solutions of group 5a and 6a metals, or diamond, diamond-like carbon, and cubic boron nitride. It consists of a single-layer or multi-layer coating of the seed. This outer layer is
Further, the thickness of the outer layer and / or the material of the outer layer can be made uniform or non-uniform by the surface layers of the first surface layer and the second surface layer described above.

That is, according to the method for producing a different layer surface-tempered sintered alloy of the present invention, 1 to 25% by volume of a powder containing an iron group metal as a main component, and the remaining 4a, 5a, 6a group metal group of the periodic table. At least one of the carbides, nitrides and their mutual solid solutions of
A first step of pulverizing and mixing a first starting material consisting of seed powder to obtain a mixed powder, a second step of shaping the mixed powder into a predetermined shape to obtain a powder compact, Cr, Mo, V, Ta , A
1, Zr, Nb, Hf, W, Si, B, P, C, a powder of at least one diffusing element, or a compound, alloy, mixture containing these diffusing elements, or a mixture of these and an iron group metal A third step of depositing or contacting at least one second starting material in the at least two surfaces of the powder compact, then in a vacuum or oxidizable atmosphere.
The powder compact is heated to 00 to 1600 ° C. to form a sintered alloy, and at least two surfaces of the surface of the sintered alloy are each formed on the respective surface layers within 0.1 to 5 mm from the respective surfaces. And a fourth step of diffusing the diffusing element.

Of the steps in this method, the second starting material in the third step is used as at least 2% of the surface of the powder compact.
To be attached to or in contact with two surfaces, specifically,
For example, a method of integrally molding the second starting material on the surface of the powder molded body by pressurizing, a method of adding an organic solvent to the second starting material and spraying or coating the surface of the powder molded body with an organic solvent. A method of spraying or applying a second starting material to which a solvent has been added to the surface of a sintering plate (for example, a carbon plate), and placing a powder compact on the surface of the second starting material applied. Alternatively, a method of embedding in the second starting material so that only the desired surface of the powder compact is contacted can be mentioned.

The second starting material used here is Mo _{2 in} addition to a diffusion element or a metal or alloy containing it and an iron group metal, such as Ni--Cr, Co--W, Ni--Al, Fe--Mo. C, Cr ₃ C ₂ , VC, WC, Al ₄ C ₃ ,
A mixture of a compound containing a diffusion element such as WB or NbN and an iron group metal can be used. Especially Periodic Table 4
When the diffusion element of the a, 5a, or 6a metal group is used, its effect on diffusion and reduction of the amount of the binder phase is large because the use of the carbide causes solid solution in the binder phase and appearance of the liquid phase at a low temperature.
It is also preferable because the amount of carbon in the hard phase in the surface layer does not easily decrease. The amount of the diffusing element and the binder phase in the surface layer or the thickness of the surface layer can be adjusted by the amount of the second starting material brought into contact with the powder compact, but the diffusion coefficient of the diffusing element in the binder phase, Heating temperature for sintering,
It is preferable to control by the holding time.

In the method for producing a sintered alloy of the present invention, a specific method for increasing or decreasing the amount of the binder phase in the surface layer is, for example, an increase in the amount of the binder phase is an iron group which becomes the binder phase together with the diffusion element. By diffusing the metal element or reducing the amount of the binder phase, for example, a liquid phase preferentially appears on the surface by diffusing a mixture of carbon of the diffusion element or a compound of the diffusion element and carbon with the surface, It is possible to move the inside rapidly by capillarity.

When the outer layer is formed on the surface of the sintered alloy obtained as described above, it can be carried out by a conventional physical vapor deposition method (PVD method) or chemical vapor deposition method (CVD method). .

[0025]

In the different surface heat-treated sintered alloy of the present invention, the surface layers in which different elements are diffused on the respective surfaces have wear resistance, plastic deformation resistance, toughness, thermal shock resistance, corrosion resistance, and acid resistance. It acts to improve the chemical conversion property, and the inside of the sintered alloy is tough,
It acts to increase the plastic deformation resistance and to improve the practical performance of the entire alloy.

[0026]

EXAMPLES Commercially available average particle diameters of 0.1 μm and 2.5 μm
And 3.5 μm WC powder, 1.5 μm TiC and
TiC_0.5N_0.5Powder, 1.5 μm Ni powder, 1.2 μ
m Co powder, 1.1 μm WC / TiC / TaC = 5
0/30/20 (abbreviated as T) solid solution powder and 1-2 μ
m TiN, Mo₂Show C, WC and TaC powders respectively
Pots made of stainless steel that are weighed and blended with the blend composition shown in 1.
4 with acetone solvent and cemented carbide balls
8Hr mixed and pulverized. While heating to 80 ° C after drying,
1.5 Add and mix wt% paraffin wax and mix
A powder was obtained. Using a mold for each of these mixed powders
1 ton / cm²15 by pressing at a pressure of
A φ × 10 mm powder compact was prepared.

On the other hand, 1 to ₂ μm of Cr ₃ C ₂ , TiC, A
1N, TaC, VC, WC, Mo ₂ C powder or these powders and the above Ni and Co powders were weighed at a predetermined ratio shown in Table 1 and mixed with a hexane solvent, paraffin wax and a dispersant in the above ball mill for 5 hours, Various slurries having a concentration of about 5% by volume were obtained.

Next, a predetermined amount of the above-mentioned slurries of different types are spray-coated with the end surface of the powder compact as the first surface and the outer peripheral surface as the second surface, and then the powder compact is placed on a carbon plate laid with a carbon powder and vacuumed. It is charged in a furnace and sintered in an atmosphere of about 10 ^-2 Torr at the temperature and time conditions shown in Table 1 together.
The products 1 to 7 of the present invention were obtained.

[0029]

[Table 1] The cylindrical sintered alloy (about 12φ × 8 mm) manufactured by the above method and conditions was cut, and the concentration of the diffusing element and the amount of the binder phase were measured for the surface layer and the inside of the first surface and the second surface. The results are shown in Table 2. As a comparison, the results are also shown in Table 2 using a normal sintered alloy that has not been subjected to surface refining treatment. As a comparative product, a commercially available ultrafine particle type cemented carbide was used as Comparative product 1, a commercially available JIS standard V40 equivalent product was used as Comparative product 2, a commercially available JIS standard M10 equivalent product was used as Comparative product 3, and commercially available TiC-TiN- WC-TaC-Mo ₂ C-
The Ni—Co system was used as Comparative product 4.

[0030]

[Table 2] Each of the factors shown in Table 2 was measured by the following: Concentration of diffusing element: By EPMA analysis, the average concentration Cs up to 0.1 mm from the surface and the internal value Ci were measured. Bound phase amount: The average concentration bs up to 0.1 mm from the surface and the internal value bi were measured by EPMA analysis. Next, the practical test results of the product of the present invention will be described.

First, using the product 1 of the present invention and the comparative product 1 in Table 2, the outer diameter was 10 mm, the length of the cutting edge was 60 mm, and the handle 3 was used.
A 0 mm solid drill was manufactured (in the drill of the product 1 of the present invention, the tip cutting edge portion was the second surface layer and the outer circumferential cutting edge portion was the first surface layer), and the ductile casting FCD6.
Cutting speed 50m using 0 plate material (thickness 30mm)
/ Min, and the feed rate was 0.2 to 0.4 mm / rev. Table 3 shows the amount of wear of the corner portion after machining 500 holes.

[0032]

[Table 3] As is clear from this result, the product of the present invention has excellent wear resistance of the outer peripheral cutting edge portion, and at the same time has a long life due to less pressure-bonding separation wear and chipping of the tip cutting edge portion, toughness at the shaft center, and plastic deformation resistance. Since it is high, it is difficult to break.

Next, using the product 3 of the present invention and the comparative product 2 in Table 2, a gang slitter for cutting a silicon steel plate (200φ) was used.
× 80φ × 5 mm) was manufactured. Inventive product 3 was manufactured according to Table 2 so that the outer peripheral surface was the first surface layer and the side surface was the second surface layer. Using these gang slitters, 0.35 mm thick silicon steel plate 500 mm / mi
After cutting at a speed of n, when Comparative product 2 was used, about 4,000 tons of cutting caused abrasion and a pressure-bonded object at the cutting edge portion, and burrs became visible. , 0
Even if 00 tons were cut, there was little wear and pressure-bonded objects, and it was possible to continue cutting. This is because the surface layer on the side surface side of the product 3 of the present invention has excellent wear resistance and weldability,
This is because the outer peripheral surface and the interior of the alloy have high toughness and plastic deformation resistance.

Next, a chip with a breaker of ISO standard TNMG160408 was manufactured using the product 4 of the present invention and the comparative product 3 in Table 2 (the chip of the product 4 of the present invention has a rake face of the first type).
The surface layer was prepared so that the flank surface became the second surface layer. Further, the chip surface of each of the present invention product 4 and the comparative product 3 was coated with a ₃ μm TiC film on the inner layer and a 4 μm film of V ₂ O _{3 on the} outer layer using a CVD apparatus. A fracture resistance test was performed on a lathe using these coated chips under the following conditions.

Work Material: S48C (with 4 Grooves) Cutting Speed: 100 m / min Feed Rate: Increased from 0.1 mm / rev Cutting Depth: 1.5 mm Cutting Oil: None As a result, Comparative Product 3 was used Coated chip feed rate is 0.2
While it was chipped at 5 mm / rev, the coated chip of the product 4 of the present invention was capable of cutting without chipping up to a high feed rate of 0.45 mm / rev. This is because the surface layer of the rake face of the product 4 of the present invention is excellent in toughness and plastic deformation resistance, and at the same time, the surface layer of the flank face is excellent in plastic deformation resistance, and further, the toughness and plastic deformation resistance inside the alloy are also high. It improves the overall defectivity.

Further, a chip with a breaker of ISO standard SNMG120408 was manufactured using the product 7 of the present invention and the comparative product 4 in Table 2 (the rake face of the chip of the product 7 of the present invention was used as the first surface layer according to Table 2). Then, the flanks were made to be the second surface layer), and these were subjected to a wear resistance test (A) and a fracture resistance test (B) using a lathe under the cutting conditions shown in Table 4.

[0037]

[Table 4] The results of the cutting test under the conditions of Table 4 are shown in Table 5.

[0038]

[Table 5] In the product of the present invention, the surface layer of the rake face is excellent in toughness and plastic deformation resistance, and the surface layer of the flank face is excellent in wear resistance, plastic deformation resistance, and at the same time, the toughness of the interior of the alloy is high so that chipping is less likely to occur It depends.

[0039]

EFFECTS OF THE INVENTION The different surface-tempered sintered alloys of the present invention are made to have different diffusing elements in their respective surface layers, so that wear resistance, toughness, impact resistance, thermal shock resistance, and plastic deformation resistance can be improved. Since all of these properties have been added, such as oxidation resistance, it has become possible to improve all properties or adjust the balance between properties, resulting in long life when used as a cutting tool, wear resistant tool or tool part. In particular, when it is used as a rotary tool such as a drill, a cutter, and a slitter component, it has a significantly longer life than conventional sintered alloys.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-52-107242 (JP, A) JP-A-3-146668 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 29/00-29/18 C22C 1/05

Claims (5)

(57) [Claims] 1. A binding phase of 1 to 25% by volume, at least one hard phase in carbides and nitrides of metals of groups 4a, 5a and 6a of the periodic table and their mutual solid solutions, and inevitable impurities. in sintered alloy consisting of, the binder phase becomes less than 50% by volume of said binder phase is Co, Ni, at least one among Fe, said sintered alloy is obtained by sintering powder compacts Ji
At least two surfaces of the chip have respective surface layers within 0.1 to 5 mm from each surface, each surface layer comprising Cr, Mo, V,
Ta, Al, Zr, Nb, Hf, W, Si, B, P,
At least one diffusing element in C and N gradually decreases from the surface toward the inside, and the diffusing element existing in the surface layer
At least one of the elements exists in other surface layers
Different layer surface-tempered sintered alloy characterized by being different from elements . 2. A binder phase of 1 to 25% by volume, at least one hard phase in carbides and nitrides of metals of groups 4a, 5a and 6a of the periodic table and their mutual solid solutions, and inevitable impurities. in sintered alloy consisting of, the binder phase becomes less than 50% by volume of said binder phase is Co, Ni, at least one among Fe, said sintered alloy is obtained by sintering powder compacts Ji
And has a first surface over at least one part or all of the surface of the chip and a second surface over at least one part of the chip except the first surface, A first surface layer is formed on the first surface by 0.1 to 5 mm from the surface, and the second surface is formed by 0.1 to 5 m from the surface.
The second surface layer up to the inside of m is formed, and the first surface layer and the second surface layer are made of Cr, Mo, V, Ta, Al, Z.
At least one diffusing element among r, Nb, Hf, W, Si, B, P, C, and N gradually decreases from the surface toward the inside, and among the diffusing elements present in the first surface layer , , Small
At least one is different from the diffusing element present in the second surface layer.
Different layer surface refining sintered alloy, characterized in that it it. 3. The difference according to claim 2, wherein the concentration of the binder phase in the first surface layer and / or the second surface layer gradually increases or decreases from the surface toward the inside. Layer surface tempered sintered alloy. 4. The chip according to claim 1 , wherein at least a part or all of one surface of the chip is provided.
An outer layer having a film thickness of 0.5 to 20 μm is coated,
The outer layer is a carbide of a metal of group 4a, 5a, 6a of the periodic table,
A nitride or boride, an oxide of Al, Si, a nitride, a carbide, a mutual solid solution thereof, diamond, diamond-like carbon, or cubic boron nitride, which is a single-layer or multi-layer coating. Characteristic of different layer surface tempered sintered alloy. 5. 50% by volume or more of the binder phase is Co, N
1 for the binder phase powder consisting of at least one of i and Fe
˜25% by volume and the first starting material consisting of powders of at least one of carbides and nitrides of metals of groups 4a, 5a and 6a of the periodic table and at least one of these mutual solid solutions in the remaining periodic table is mixed and pulverized to form a mixed powder. , A second step of molding the mixed powder into a predetermined shape to obtain a powder compact, Cr, Mo, V, T
Powder of at least one diffusion element of a, Al, Zr, Nb, Hf, W, Si, B, P and C, or a compound, alloy, mixture or mixture of these and an iron group metal containing the diffusion element. At least one of the second starting materials of the above is attached to or in contact with at least two of the surfaces of the powder compact , and a second output is attached to or in contact with the surfaces.
At least one of the substances is attached to other surfaces
Is a third step different from the second starting material to be contacted ,
Then 1200-1600 in vacuum or non-oxidizing atmosphere
It is common to heat the powder compact to ℃ and sinter the powder compact into chips.
To, the diffusion element definitive on each surface layer of the respective surfaces to the interior 0.1~5mm at least two surfaces of the surface of the chip gradually toward the inside from the surface
Next decrease, less of the diffusion elements present in the surface layer
And one of them is different from the diffusing elements that exist in other surface layers
The fourth step and the different layer surface refining sintered alloy manufacturing method characterized in that it consists of are.