JP2003129165A - Surface coated hard alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface coated hard alloy which has high hardness and toughness, and excellent oxidation resistance, and can improve both fracture resistance and abrasion resistance so as to endure even when the surface is exposed to high temperature. SOLUTION: The surface coated hard alloy comprises a hard alloy 2 consisting of WC and one or more carbides, nitrides, and/or carbonitrides, of Zr and M (M is at least one metallic element except Zr, selected from the group consisting of 4a, 5a and 6a family metals in the periodic table), and a binding material of iron family metals, and a hard coating layer 3 formed thereon. Then, the provided metal has high hardness, high toughness, and excellent oxidation resistance, and is suitable for machining for a hardly machinable material including not only steel and cast iron like carbon steel and alloy steel but also stainless steel. In addition, the above hard coating layer is comprised of one or more layers selected from the group consisting of carbides, nitrides, oxides or the like of 4a, 5a, and 6a family metals or Al, and of diamond, in the periodic table.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated cemented carbide used for a cutting tool or the like, and particularly has high hardness and high toughness and excellent oxidation resistance, and is a steel such as carbon steel or alloy steel or cast iron. In addition, it relates to a surface-coated cemented carbide suitable for cutting difficult-to-cut materials such as stainless steel.

[0002]

2. Description of the Related Art Conventionally, cemented carbide is a WC-Co type alloy composed of a hard phase mainly composed of WC (tungsten carbide) and a binding phase of an iron group metal such as cobalt, or a WC-Co based alloy thereof. 4a, 5a, 6a group metal carbides, nitrides,
A system in which a so-called B-1 type solid solution phase such as carbonitride is dispersed is known, and is widely used for metal cutting and wear resistant materials. Among them, cutting tools such as carbon steel and alloy steel are used. It is mainly used for cutting cast iron, but recently cutting difficult-to-cut materials such as stainless steel has also been advanced.

Further, in such cemented carbide, a method of forming a hard coating layer having a higher hardness on the alloy surface to improve wear resistance is known, and the impact applied to the hard coating layer is mitigated. Therefore, there is known a method of forming a so-called β-free layer in which the content of the B-1 type solid solution is reduced in the surface region on which the hard coating layer of cemented carbide is formed.

Further, in JP-A-6-93473, Ti and Zr are used as a B-1 type solid solution (Nb).
1 to 50 μm from the surface of the base material)
It is described that the Zr content disappears or decreases in the depth region of.

[0005]

However, in these cemented carbides, the surface of the alloy may be oxidized and deteriorated by heat during cutting and oxygen in the environment, resulting in a decrease in both hardness and toughness. It is known that even if a hard coating layer is formed on the surface of an alloy (base material), the base material surface may be exposed to an oxidizing atmosphere due to the presence of defects in the hard coating layer. forming a de-β layer on the surface and _{(p 1suf / p in <0.9} , q 1suf / q in <0.9),
The surface of the base material was likely to be oxidized and deteriorated.

On the other hand, when not forming a de-β layer directly below the hard coating layer _{(p 1suf = p 2suf = p} in, q 1suf = q 2suf = q
_In ), there was a problem that the impact resistance and fracture resistance of the hard coating layer deteriorated.

Further, the content of Zr in the surface area of the base material as disclosed in JP-A-6-93473 is small (q _1suf / q
_In <0.9) coated cemented carbide, there is a problem that the plastic deformation resistance deteriorates and the wear resistance decreases.

Therefore, the present invention has been made to solve the above problems, and its purpose is to have high hardness and toughness as well as excellent oxidation resistance, such that the surface is exposed to high temperatures due to continuous operation or the like. An object of the present invention is to provide a surface-coated cemented carbide capable of improving both high fracture resistance and wear resistance even in a harsh environment.

[0009]

Means for Solving the Problems The present inventor has examined the constitution of the cemented carbide base material with respect to the above problems, and as a result, the Zr content on the surface of the cemented carbide has a variation amount with respect to that of the inside. At least one metal element other than Zr (M is at least one selected from the group of metals of Groups 4a, 5a and 6a of the Periodic Table)
A content of (1 or more) is smaller than that of the inside, and inside the first surface region, the content of Zr has a small change with respect to the inside and a metal other than Zr. By providing a second surface region in which the content of the element M (M is at least one or more selected from the group of metals of groups 4a, 5a and 6a of the periodic table) is higher than that of the inside thereof,
The toughness of the base metal surface can be improved to improve the fracture resistance of the hard coating layer, and the oxidation resistance of the cemented carbide on which the hard coating layer is formed can be increased, either continuously or intermittently. It was found that a surface-coated cemented carbide having excellent fracture resistance and wear resistance can be obtained even when it is operated for a long time and exposed to a high temperature for a long time.

That is, the surface-coated cemented carbide of the present invention is
WC, one or more of carbides, nitrides and / or carbonitrides of at least one metal element M selected from the group of metals of groups 4a, 5a and 6a of the periodic table, and an iron group metal In a surface-coated cemented carbide formed by depositing a hard coating layer on the surface of a cemented carbide containing a binder, the metal element M contains both Zr and Nb, and the surface of the cemented carbide. To a depth of 5 μm or more and 200 μm or less, the first surface region shown below and a second surface region located inside the first surface region are provided.

The total amount of the metal element M in the cemented carbide is
Content: M_in, Inclusion of Zr in the cemented carbide
Amount: Zr_in, W content in the cemented carbide: W
_in, The total content of the metal element M in the first surface region
Amount: M_{1 suf}, Inclusion of Zr in the first surface region
Amount: Zr_{1 suf}, Inclusion of W in the first surface region
Quantity: W _{1 suf}Of the metal element M in the second surface region
Total content: M_{2 suf}, Zr in the second surface region
Content: Zr_{2 suf}, Containing W in the second surface region
Amount: W_{2 suf}And p_in= M_in/ W_in, P_{1 suf}= M_{1 suf}
/ W_{1 suf}, P_{2 suf}= M_{2s uf}/ W_{2 suf}, Q_in= Zr_in/ W
_in, Q_{1 suf}= Zr_{1 suf}/ W_{1 suf}, Q_{2 suf}= Zr_{2s uf}/ W
_{2 suf}And 0.1 ≦ p_{1 suf}/ P_in≤ 0.9, 0.
9 ≦ q_{1 suf}/ Q_in≦ 1.1 and 1.1 ≦ p_{2 suf}/ P_in
≦ 1.5, 0.9 ≦ q_{2 suf}/ Q_in≦ 1.1 where:
Oxidation resistance of surface coated cemented carbide is 0.01mg / mm²Since
Below, in the whole of the cemented carbide, the metal element
Element M is 0.1 ≦ Zr / (Ti + Zr + Hf) ≦ 0.
5 and 0.6 ≦ Nb / (V + Nb + Ta) ≦ 1.0
Satisfying the above requirement, 0.05
It is desirable to satisfy ≦ Zr / (Zr + Nb) ≦ 0.8
Good

Further, the cemented carbide has a ZrC content of 0.1.
~ 1.5 wt%, NbC 0.5-3.5 wt%, Ti
1.0 to 2.5% by weight of C, 0 to 1.0% by weight of TaC, 0 to 1.0% by weight of HfC, and 0 to 1.0 of Cr ₃ C ₂ .
It is desirable that the content of WC and unavoidable impurities is 50% by weight, VC is 0 to 1.0% by weight, Co is 5 to 10% by weight, and the balance is WC and inevitable impurities.

Further, the thickness d ₁ of the first surface region is 1
˜50 μm, the thickness d ₂ of the second surface region is 10 to 2
It is preferably 00 μm.

Further, the hard coating layer is the fourth periodic table.
Consists of a single layer or a plurality of layers selected from the group consisting of carbides, nitrides, oxides, carbonitrides, carbonitrides, carbonitrides and diamonds of a, 5a, 6a group metals or Al. Is desirable.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The surface-coated cemented carbide of the present invention is a cemented carbide (base material) as shown in the schematic sectional view of FIG.
The hard coating layer 3 is adhered and formed on the surface of 2.

The base material 2 comprises WC (tungsten carbide),
At least one metal element M (Ti, V, Cr, Z selected from the group consisting of metals of groups 4a, 5a and 6a of the periodic table)
r, Nb, Mo, Hf, Ta, W) and one or more of carbides, nitrides and / or carbonitrides, and a binder of an iron group metal (Co, Ni, Fe). However, according to the present invention, as the metal element M, Zr and N
The major feature is that b and b are contained together, whereby a surface region having a predetermined depth shown below can be formed. The metal element M includes at least one selected from the group consisting of Ti, V, Cr, Mo, Hf and Ta, in addition to Zr and Nb.

Further, according to the present invention, a cemented carbide (base material)
From the surface of 2 to a depth of 5 μm or more and 50 μm or less,
The total content of the metal element M in the cemented carbide internal 4: M _in,
The content of Zr in the cemented carbide Internal 4: Zr _in, the content of W in the cemented carbide Internal 4: W _in, the first surface region 5
Content of metal element M in M _1suf , content of Zr in first surface region 5: Zr _1suf , content of W in first surface region 5: W _1suf , metal in second surface region 6 Total content of element M: M _2suf , second surface area 6
The content of Zr in: Zr _2Suf, the content of W in the second surface region 6: the _{W 2suf, p in = M in} / W in, p
_1suf = M _1suf / W _1suf , p _2suf = M _2suf / W _2suf , q _in
= Zr _in / W _in , q _1suf = Zr _1suf / W _1suf , q _2suf =
When Zr _2suf / W _2suf , 0.1 ≦ p _1suf / p _in ≦
0.9, 0.9 ≦ q _1suf / q _in ≦ 1.1 and 1.1 ≦
p _2suf / p _in ≤1.5, _{0.9 ≤q 2suf} / q _{in ≤1.1}
And a first surface area 5 that satisfies the
It is important to have the second surface region 6 located further inside.

As a result, the toughness of the surface of the base material 2 can be improved and the fracture resistance of the hard coating layer 3 can be improved, and at the same time, the oxidation resistance of the alloy 1 on which the hard coating layer 3 is formed is increased. It has excellent fracture resistance and wear resistance even when operating in a high temperature environment such as cutting difficult-to-cut materials such as stainless steel as well as steel such as carbon steel and alloy steel and cast iron. It is possible to obtain the surface-coated cemented carbide 1, which is most suitable for cutting work.

Here, in the first surface region 5, p
When _1suf / p _in is less than 0.1, decreases the oxidation resistance at the base material 2 surface, the hard coating layer 3 in particular altered continuously used to the surface of the base material 2 in a high temperature region is It causes peeling and plastic deformation. Conversely, when p _{1s uf} / p _in is greater than 0.9, it decreases the toughness of the base material 2 surface reduces the impact resistance of the hard coating layer 3, chipping is likely to occur. Further, if q _1suf / q _in is less than 0.9, the oxidation resistance on the surface of the base material is lowered, and particularly when continuously used in a high temperature range, the surface of the base material 2 is deteriorated and the hard coating layer 3 Is likely to peel off and chip, and especially the blade edge (cutting edge)
In this case, the plastic deformation resistance is deteriorated and the wear resistance is lowered. On the other hand, when q _1suf / q _in is larger than 1.1, the plastic deformation resistance and wear resistance of the alloy surface decrease.

In the second surface region 6, p_{2 suf}/
p_inIs less than 1.1, the second surface region 6 is odorous
Area where the hardness value is significantly reduced, resulting in wear resistance and plastic resistance.
Deformability decreases. Conversely, p_{2 suf}/ P_inIs from 1.5
Is also large, the toughness value is remarkable in the second surface region 6.
A reduced portion is formed and the fracture resistance is reduced. Also, q
_{2 suf}/ Q_inIs less than 0.9, the second surface area 6
Wear resistance
And plastic deformation resistance decreases. Conversely, q_{2 suf}/ Q_inIs 1.
If it is larger than 1, the toughness value of the second surface region 6
A significantly reduced portion is formed and the fracture resistance is reduced.

The distribution state of the metal element M in the present invention is obtained by measuring the component ratio at each position of the alloy by energy dispersive X-ray analysis (EDS) and mapping it as shown in FIG. 1 (b). be able to.

Further, the total sum of the first surface region 5 and the second surface region 6 in the present invention is preferably 5 to 200 μm, and particularly preferably 5 to 50 μm. If the sum of the first surface region 5 and the second surface region 6 is less than 5 μm, the effect of improving the toughness is small, and if it is 200 μm or more, the surface hardness decreases and the plastic deformation resistance decreases.

Here, the thickness d ₁ of the first surface region is preferably from 1 to 50 μm, and particularly preferably from 1 to 10 μm in order to achieve both oxidation resistance and chipping resistance. Further, the thickness d ₂ of the second surface region 6 is set in order to achieve both wear resistance, plastic deformation resistance and fracture resistance.
The thickness is preferably 10 to 200 μm, particularly preferably 10 to 40 μm. Further, the ratio of d ₁ / d ₂ is preferably 0.1 to 0.6 in order to achieve both oxidation resistance and chipping resistance.

Further, the composition of the cemented carbide (base material) 2 has a composition of 0.1 ≦ Z in order to improve fracture resistance, wear resistance and oxidation resistance.
r / (Ti + Zr + Hf) ≦ 0.5, especially 0.1 ≦ Z
r / (Ti + Zr + Hf) ≦ 0.4 and 0.6 ≦ N
b / (V + Nb + Ta) ≦ 1.0, especially 0.7 ≦ Nb /
It is desirable to contain Nb together with Zr in a predetermined ratio of (V + Nb + Ta) ≦ 1.0. Further, in the whole cemented carbide, 0.05 ≦ Zr / (Zr + Nb) ≦ 0.
It is desirable to satisfy 8 and in particular 0.1 ≦ Zr / (Zr + Nb) ≦ 0.6.

Furthermore, the specific composition of the cemented carbide (base material) 2 is ZrC (zirconium carbide) in order to achieve both oxidation resistance, wear resistance, plastic deformation resistance and fracture resistance.
0.1 to 1.5% by weight, and NbC (niobium carbide) to 0.
5 to 3.5 wt%, TiC (titanium carbide) 1 to 2.5
%, TaC (tantalum carbide) 0 to 1% by weight, Hf
C (hafnium carbide) 0 to 1% by weight, Cr ₃ C ₂ (chromium carbide) 0 to 1% by weight, VC (vanadium carbide) 0
It is desirable that the content of Co is 1 to 1% by weight, Co (cobalt) is 5 to 10% by weight, and the balance is WC (tungsten carbide) and inevitable impurities.

Of the above components, in order to reduce the cost, it is desirable that the content of expensive TaC is 0.5% by weight or less, particularly 0.1% by weight or less, and further it is not substantially contained.

Further, in the above composition range, in order to attach importance to wear resistance and to use as a cutting tool for turning, T
1.5 to 2.0% by weight of iC and 2.0 to 3.5 of NbC
% By weight, 0.1 to 0.8% by weight of ZrC, 5.0 of Co
It is desirable that the content of WC be up to 7.5% by weight and the balance be WC, and that TiC is 1.5 to 2.0% by weight and N in order to use it as a cutting tool for milling with an emphasis on fracture resistance.
bC 0.5 to 2.0% by weight, ZrC 0.8 to 1.5
It is preferable that the content of Co is 7.5 to 10.0% by weight and the balance is WC.

Further, according to the present invention, in order to operate stably in a high temperature range such as when cutting a difficult-to-cut material such as stainless steel, the surface-coated cemented carbide 1 has an oxidation resistance of 0. 0
It is important to set it to 1 mg / mm ² or less. That is, the oxidation resistance of the surface-coated cemented carbide 1 is 0.01 mg / m
If it is larger than m ^{2, the} surface of the cemented carbide (base material) 2 is oxidized during processing due to defects existing in the hard coating layer, and wear resistance and fracture resistance are deteriorated.

The term "oxidation resistance" as used in the present invention means that a surface-coated cemented carbide having a hard coating layer formed thereon has a hardness of 80
When the oxidation test is carried out under the condition of 0 ° C. × 30 minutes, the rate of increase in oxidation before and after the test is shown.

The hard coating layer formed on the surface of the cemented carbide (base material) 2 includes the periodic table 4a, 5a,
At least one selected from the group consisting of 6a group metal or Al carbides, nitrides, oxides, carbonitrides, carbonates, oxynitrides, carbonitrides and diamonds, particularly TiC and T.
It is composed of a single layer or a plurality of layers of iN, TiCN, Al ₂ O ₃ and TiAlN, and in FIG.
Layer, an Al ₂ O ₃ layer, and a TiN layer.

(Manufacturing Method) In order to manufacture the above-mentioned surface-coated cemented carbide, first, for example, the average particle size is 0.5 to 10 μm.
Tungsten carbide powder of 80 to 90% by weight, and Zr carbide, nitride and / or carbonitride powder of Zr having an average particle diameter of 0.5 to 5 μm or a solid solution powder thereof in a total amount of 0.1 to 1
0% by weight, Nb carbide, nitride and / or carbonitride powder of Nb having an average particle size of 0.5 to 5 μm or a solid solution powder thereof in a total amount of 0.1 to 10% by weight, an average particle size of 0.5 to 5 μm
Of at least one carbide, nitride and / or carbonitride powder selected from the group consisting of Ti, V, Cr, Mo, Hf and Ta, or a solid solution powder of two or more of these metals in a total amount of 0.1. -10% by weight, average particle size 0.5-
5 to 15% by weight of iron group metal having a thickness of 10 μm is mixed with metal tungsten (W) powder or carbon (C) powder, if desired.

Next, the powder mixture is molded into a predetermined shape by a known molding method such as press molding, cast molding, extrusion molding, cold isostatic pressing, etc.
In a vacuum of 15 Pa, the temperature rising rate at 1000 ° C. or higher is raised at 0.3 to 4 ° C./minute, particularly 0.5 to 2 ° C./minute, and the vacuum degree is 10 ^{−3 to} 0.05 Pa in a vacuum of 1350. ~ 150
A cemented carbide (base material) is produced by firing at 0 ° C. for 0.2 to 5 hours, particularly 0.5 to 2 hours.

Regarding the above-mentioned firing, in order to control the composition and thickness of the surface region, it is important to control the temperature rising rate and the atmosphere during firing within the above range.

Next, CVD is performed on the surface of the cemented carbide (base material).
Of the hard coating layer by a known thin film forming method such as the PVD method or the PVD method.
The surface-coated cemented carbide of the present invention can be obtained by depositing 1 to 20 μm.

The surface-coated cemented carbide of the present invention described above has excellent mechanical properties such as high hardness, high toughness, high strength, and high oxidation resistance, so that it can be used in molds, wear resistant members, and high temperature structures. It is applicable to materials and the like, and can be suitably used as a cutting tool for machining steel such as carbon steel and alloy steel and cast iron, and for machining difficult-to-cut materials such as stainless steel.

[0036]

EXAMPLES Example 1 Tungsten carbide (WC) powder having an average particle size of 1.5 μm, metallic cobalt (Co) powder having an average particle size of 1.2 μm, and metallic elements shown in Table 1 having an average particle size of 2.0 μm. The M compound powder was added and mixed at the ratio shown in Table 1, and the shape of the cutting tool was obtained by press molding (CNMG12040).
After forming into 8), it is subjected to binder removal treatment, and further 1
Increase the temperature above 000 ° C at a rate of 3 ° C / min to 0.01P
In a vacuum of a, it was fired at 1500 ° C. for 1 hour to produce a cemented carbide.

Ti was formed on the surface of the obtained cemented carbide by the CVD method.
N 1 μm, TiCN 7 μm, Al ₂ O ₃ 3 μm, T
A surface-coated cemented carbide was produced by depositing a hard coating layer of iN in the order of 1 μm.

With respect to the obtained surface-coated cemented carbide, a metal element concentration distribution in an arbitrary region of 200 μm × 200 μm was measured from the surface to the inside by a wavelength dispersive X-ray microanalyzer (EPMA). In addition, EPMA
Regarding the measurement, the surface region was obliquely polished, and 5 points were measured at every 5 μm depth from the surface, and the average value was calculated. Further, the concentration distribution as shown in FIG. 2 was mapped from the metal element concentration distribution, and the thicknesses of the first surface region and the second surface region were calculated. The results are shown in FIG. 1 and Table 1.

Further, oxidation treatment was carried out for 30 minutes in an atmospheric pressure atmosphere of 800 ° C., and the weight increase amount before and after the oxidation was measured to obtain the oxidation resistance. The results are shown in Table 1.

[0040]

[Table 1]

Using this cutting tool, alloy steel was cut for 25 minutes under the following conditions, and the flank wear amount and tip wear amount of the cutting tool were measured. When the flank wear amount or the tip wear amount reached 0.2 mm during the cutting test, the cutting time was measured. Furthermore, an intermittent test was performed on a grooved steel material to compare the number of impacts when chipped. The results are shown in Table 2.

(Abrasion test) Work Material: Alloy Steel (SCM435) Tool shape: CNMG120408 Cutting speed: 250m / min Feed rate: 0.3 mm / rev Notch: 2 mm Others: Using water-soluble cutting fluid (Intermittent test) Work Material: Alloy Steel (SCM440) Tool shape: CNMG120408 Cutting speed: 200m / min Feed rate: 0.4 mm / rev Notch: 1.5 mm Others: Using water-soluble cutting fluid

[0043]

[Table 2]

From the results shown in Tables 1 and 2, sample No. containing no Nb. 1, q _1suf in the first surface region
/ Q _in (content of Zr) was smaller than 0.9, oxidation resistance was lowered, and cutting performance was lowered. When the cross section of the sample after the oxidation test was observed by SEM, it was confirmed that the vicinity of the surface of the base material was deteriorated by oxidation. Moreover, the sample No. containing no Zr. 2, p _1suf in the first surface region
/ P _in (the total content of the metal element M) is greater than 0.9,
q _1suf / q _in (content of Zr) is smaller than 0.9, p _2suf / p _in (total content of metal element M) _in the second surface region is smaller than 1.1, and q _2suf /
The q _in (Zr content) was less than 0.9, and the chipping resistance and oxidation resistance were poor.

In contrast, according to the present invention, Zr and Nb
_Is added together with 0.1 ≦ p _1suf / p _in ≦ 0.
9, 0.9 ≦ q _1suf / q _in ≦ 1.1, and 1.1 ≦ p
And a _{2suf / p in ≦ 1.5,0.9 ≦ q} 2suf / q in the first surface region satisfying ≦ 1.1 and a second surface region located inside than the first surface region Sample No.
In Nos. 3 to 8, all had excellent oxidation resistance, high hardness and toughness, and excellent cutting performance. (Example 2) Sample No. of Example 1 After forming into a milling tool shape (SDK42) for 5 and 11,
A cutting tool made of a surface-coated cemented carbide was prepared in exactly the same manner as in Example 1 except that the TiN film having a film thickness of 2 μm was formed on the surface by firing at 1400 ° C. for 1 hour.

Then, using the obtained cutting tool, the following conditions Work material: Stainless steel (SUS304) Tool shape: SDK42 Cutting speed: 200 m / min Feed speed: 0.2 mm / Flute depth: 2 mm Others: Water-soluble The stainless steel was cut for 15 minutes using a cutting fluid, and the cutting performance was evaluated in the same manner as in Example 1. As a result, Sample No. For No. 2, the flank wear amount is 0.21 mm, while for sample N
o. In No. 7, the flank wear amount was 0.11 mm, which was excellent in wear resistance and chipping resistance.

[0047]

As described above in detail, according to the surface-coated cemented carbide of the present invention, the content of Zr on the surface of the cemented carbide has a small change relative to that inside, and the metal M (M is Z
a first surface region in which the content of at least one selected from the group of metals of groups 4a, 5a, and 6a of the periodic table other than r is smaller than that in the inside, and inside the first surface region , Zr content is less changed with respect to that of the inside, and metal M (M is a periodic table other than Zr 4a, 5
(At least one selected from the group of metals a and 6a)
By disposing the second surface region having a larger content of that with respect to that of the inside, it is possible to improve the toughness of the base material surface and improve the fracture resistance of the hard coating layer,
It is possible to obtain a surface-coated cemented carbide that can improve the oxidation resistance of the alloy and the alloy on which the hard coating layer is formed and that has excellent fracture resistance and wear resistance even when operating in a high temperature environment. To be

[Brief description of drawings]

FIG. 1A is a schematic sectional view of a surface-coated cemented carbide of the present invention, and FIG. 1B is an example of each metal element distribution in the cemented carbide (base material).

[Explanation of symbols]

1 Surface coated cemented carbide 2 Cemented carbide (base material) 3 Hard coating layer 4 inside 5 First surface area 6 Second surface area

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Claims (7)

[Claims] 1. WC and at least one metal element M selected from the group consisting of metals of groups 4a, 5a and 6a of the periodic table.
Surface-coated cemented carbide obtained by depositing a hard coating layer on the surface of a cemented carbide composed of at least one of the above-mentioned carbides, nitrides and / or carbonitrides and a binder of an iron group metal. In the above, the metal element M contains both Zr and Nb, and is 5 μm or more and 20 μm or more from the surface of the cemented carbide.
A surface-coated cemented carbide, comprising a first surface region shown below and a second surface region located inside the first surface region over a depth of 0 μm or less. Total content of the metal element M inside the cemented carbide: M _in Content of Zr inside the cemented carbide: Zr _in Content of W inside the cemented carbide: W _in Metal _in the first surface region Total content of element M: M
_1suf Content of Zr in the first surface region: Zr _1suf Content of W in the first surface region: W _1suf Total content of metal element M in the second surface region: M
_2Suf content of Zr in said second surface region: Zr _2Suf content of W in the second surface _{region: W 2suf p in = M in} / W in p 1suf = M 1suf / W 1suf p 2suf = M 2suf / W _2suf q _in = Zr _in / W _in q _1suf = Zr _1suf / W _1suf q _2suf = Zr _2suf / W _2suf , 0.1 ≦ p _1suf / p _in ≦ 0.9, 0.9 ≦ q _1suf / q _in
≦ 1.1 and 1.1 ≦ p _2suf / p _in ≦ 1.5, 0.9 ≦ q _2suf / q _in
≦ 1.1 2. The oxidation resistance of the surface-coated cemented carbide is 0.
The amount is 01 mg / mm ² or less.
Surface-coated cemented carbide as described. 3. In the entire cemented carbide, the metal element M is 0.1 ≦ Zr / (Ti + Zr + Hf) ≦ 0.
5 and 0.6 ≦ Nb / (V + Nb + Ta) ≦ 1.0
The surface coated cemented carbide according to claim 1 or 2, characterized in that 4. In the whole cemented carbide, 0.05 ≦
The surface-coated cemented carbide according to claim 1, wherein Zr / (Zr + Nb) ≦ 0.8 is satisfied. 5. The cemented carbide contains ZrC in an amount of 0.1 to 1.
5% by weight, NbC 0.5 to 3.5% by weight, TiC 1.0 to 2.5% by weight, TaC 0 to 1.0% by weight, H
fC is 0 to 1.0% by weight, Cr ₃ C ₂ is 0 to 1.0% by weight, VC is 0 to 1.0% by weight, Co is 5 to 10% by weight, and the balance is WC and inevitable impurities. The surface-coated cemented carbide according to any one of claims 1 to 4, wherein 6. The thickness d ₁ of the first surface region is ₁ to 5
0 μm, the thickness d ₂ of the second surface region is 10 to 200
The surface-coated cemented carbide according to any one of claims 1 to 5, which has a thickness of µm. 7. The hard coating layer comprises periodic tables 4a and 5
a, 6a group metal or Al carbide, nitride, oxide,
The surface coating according to any one of claims 1 to 6, wherein the surface coating is composed of a single layer or a plurality of layers selected from the group consisting of carbonitrides, carbon oxides, nitrogen oxides, carbonitrides and diamonds. Cemented carbide.