JPH0693473A - Coated cemented carbide - Google Patents

Abstract

PURPOSE:To produce a high performance working tool by constituting it of a cemented carbide with a coating layer in which carbides contg. Zr and Ti are coexistent in the hard phase and the coating layer is formed of a single layer or multiple layers of the carbides of specified metals. CONSTITUTION:The coated cemented carbide is a one in which the surface of the base metal of a cemented carbide constituted of bonding layer metals consisting of WC and one or more kinds among iron-group metals and a hard phase of two or more kinds selected from the carbides, nitrides and carbonitrides of 4a, 5a and 6a group metals of the periodic table is applied with a coating layer. In the hard phase, respectively one or more kinds selected from the carbides, nitrides and carbonitrides contg. Zr and/or Hf and Ti are coexistent, and the coating layer is formed of a single layer or multiple layers of one or more kinds selected from the carbides, nitrides, oxides and borides of 4a, 5a and 6a group metals of the periodic table and aluminum oxide. In this way, the cemented carbide utilizable for a tool having wear resistance and toughness under high performance working conditions can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated cemented carbide which is tough and has excellent wear resistance, which is used for cutting tools and the like.

[0002]

2. Description of the Related Art In recent years, there has been a demand for high efficiency in cutting,
A coated cemented carbide obtained by vapor-depositing a coating layer of titanium carbide or the like on the surface of a cemented carbide has both toughness of the base material and wear resistance of the surface, and is therefore widely used as a highly efficient cutting tool. The cutting efficiency is determined by the cutting speed (V) and the feed amount (f), but increasing V shortens the tool life rapidly. Therefore, f has been increased to improve cutting efficiency. In this case, the toughness of the base material that can cope with high cutting stress is required, and as a countermeasure against this, there is a method of increasing the amount of binder phase in the alloy base material. Further, it is also performed to raise both V and f.

[0003]

However, although the increase of the binder phase leads to the improvement of the toughness, the plastic deformation of the cutting edge occurs under the condition of high cutting speed. There is also a method of improving the heat resistance of the alloy and increasing the tool life by increasing carbides such as Ti and Ta in the alloy in order to cope with high-speed cutting conditions. However, there is a drawback in that the strength of the alloy is remarkably lowered by such means.

The present invention solves the above-mentioned drawbacks and provides a coated cemented carbide which can be used for a cutting tool that maintains wear resistance and toughness under conditions of high efficiency machining which could not be achieved by conventional techniques. With the goal.

[0005]

In order to achieve the above object, the coated cemented carbide of the present invention comprises W
C and one or more iron group metals as a binder phase metal, and Periodic Table 4
In a coated cemented carbide having a coating layer on the surface of a cemented carbide base material composed of two or more hard phases selected from carbides, nitrides, and carbonitrides of a, 5a, and 6a group metals, the hard phase Contains at least one selected from carbides, nitrides, and carbonitrides containing Zr and / or Hf and at least one selected from carbides, nitrides, and carbonitrides containing Ti. Is composed of one or more single layers or multiple layers selected from carbides, nitrides, oxides, borides and aluminum oxides of metals of Groups 4a, 5a and 6a of the Periodic Table.

The reason why such a structure is adopted will be described below. Conventionally, carbides of metals of the 4a, 5a and 6a groups of the periodic table have been added to improve the wear resistance of alloys. However, these are liable to form a solid solution with WC, which reduces the amount of WC having the highest strength in the alloy, which has a drawback of lowering the alloy strength.

By the way, as shown in "Powder and Powder Metallurgy Vol. 26, No. 6, 213", Zr carbide is
The alloy strength at room temperature and high temperature belongs to the highest class among 4a, 5a and 6a group metals. Therefore, the cemented carbide containing Zr carbide is considered to be the most preferable alloy for practical use. However, practical examples of cemented carbide to which Zr and Hf carbides and nitrides are added among the 4a group metals are hardly seen.
This is presumably because these carbides have low hardness and are difficult to wear.

The present invention has been completed through various studies in order to put these cemented carbides into practical use.
The feature is that in order to maintain the alloy strength with Zr, Hf carbides and the like and to solve the lack of alloy hardness, Ti carbide and the like are added and coexist.

That is, it was found that when a Zr carbide or the like is added to the alloy, the Ti carbide or the like becomes difficult to form a solid solution with WC, and by utilizing this, it is possible to achieve both hardness and strength. .

Incidentally, Ti, Zr, and Hf are preliminarily written in W and T.
It can be added to the alloy in the form of a carbide or carbonitride in which a, Nb, V, etc. are solid-solved. Zr or the like may be dissolved in advance in Ti carbide coexisting with Zr carbonitride or the like, and the effect of the present invention is lost even if Zr carbonitride is a solid solution with Hf. Absent.

In the coated cemented carbide, Zr and / or
Alternatively, the amount of metal components Zr and Hf (M1) in one or more hard phases selected from carbides, nitrides, and carbonitrides containing Hf.
"Mol") and the amount of metal component Ti (M2 "mol") in one or more hard phases selected from carbides, nitrides, and carbonitrides containing Ti, expressed as a mol ratio, the following relationship It is characterized by being in. 0.2 ≦ M1 / (M1 + M2) ≦ 0.9

If it is less than 0.2, it is difficult to make a hard layer such as a carbide containing Zr and / or Hf coexist with a hard layer such as a carbide containing Ti. That is, the object of the present invention cannot be achieved because double carbides and the like are easily formed. On the other hand, if it exceeds 0.9, the alloy hardness becomes insufficient.
The range is preferably 0.3 to 0.7.

Further, one or more hard phases selected from carbides, nitrides and carbonitrides of metals of Groups 5a and 6a of the Periodic Table disappear from just below the coating layer to the inside of the base material, and Zr
And / or one or more hard phases selected from carbides, nitrides and carbonitrides containing Hf and one or more hard phases selected from carbides, nitrides and carbonitrides containing Ti are reduced or eliminated. Having a surface layer region of 2 to 100 μm
It is characterized by being m.

With this structure, Zr and / or H in the surface layer region
When one or more hard phases selected from carbides, nitrides, and carbonitrides containing f and one or more hard phases selected from carbides, nitrides, and carbonitrides containing Ti are completely disappeared, The region consists of WC and bonded phase only.

With such a structure, the toughness of the alloy surface can be improved. Conventionally, Ti nitride,
It is known that Ti nitrides and the like disappear on the alloy surface when carbonitride is used (for example, Journal of Japan Institute of Metals, Vol. 45, No. 1, 95). , It remained. However. It is known that when a cemented carbide containing a Ti nitride or the like is heat-treated at a temperature exceeding 1500 ° C., the Ti nitride disappears at this ridge (Material Science and Engineering, 1988,225-234).
). In this respect, the alloy according to the present invention does not undergo heat treatment at a temperature exceeding 1500 ° C.
When nitrides such as r and Hf are added to the alloy, 5a, 6a
The nitride of Ti including the hard phase such as the carbide of the group metal disappears or decreases. This structure makes it possible to significantly improve the toughness of the tool cutting edge as compared with the conventional alloy.

The thickness of the surface layer region is 2 μm from the surface of the base material.
If it is less than m, there is no effect of improving toughness, and if it exceeds 100 μm, wear resistance is lowered. Preferably, 5 to 50 μ
It is within m.

The thickness of the surface layer region can be controlled by controlling one or more hard phases selected from carbides, nitrides, and carbonitrides containing Zr and / or Hf in the raw material powder, and carbides and nitrides containing Ti. , One or more hard phases selected from carbonitrides, or a hard phase of a 5a or 6a group metal is added to the alloy as a nitride or carbonitride, 1350 to 15
It is carried out by holding in a vacuum or under a constant nitrogen pressure in the range of 00 ° C. and controlling the holding time.

Incidentally, in an actual tool, a portion which is not used as a tool (for example, the seat surface of the throw-away tip) is ground at the stage of the alloy sintered body in order to obtain dimensional accuracy (thickness, etc.). . As a result, the surface layer region of the seat surface portion disappears, and then the coating layer is formed. As described above, when the alloy of the present invention is processed as a tool, it does not always have a surface layer region on its entire surface.

Further, from the surface layer region to the inside of the alloy, T
An amount of one or more hard phases selected from carbides, nitrides or carbonitrides containing i has a layer larger than that in the inside of the alloy, and the thickness thereof is 1 to 50 μm. .

By providing a hard phase such as a carbide containing Ti inside the surface layer region, it is possible to minimize the plastic deformation of the tool cutting edge caused by the temperature rise. This effect does not occur when the thickness is less than 1 μm inside the surface layer region.
If it exceeds 0 μm, toughness is reduced.

In this region, after the hard phase such as Zr disappears,
It is considered that only Ti carbides, nitrides, and carbonitrides of Ti were precipitated from the liquid phase. In this case, Ti reacts with WC to precipitate as a double carbide and a double nitride, and 5a,
It may also contain elements of group 6a. That is, this region is composed of WC, carbide containing Ti, carbonitride, or Ti and WC.
Containing carbides, carbonitrides, and binder phase metals.

In addition, from the surface layer area toward the inside of the alloy, 1
The maximum hardness in the region of up to 50 μm is Hv hardness, load 500
Expressed in g, it is 1400 to 1900 kg / mm ² .
If it is less than 1400 kg / mm ² , there is no effect in improving the plastic deformation resistance, and if it exceeds 1900 kg / mm ² , toughness decreases. It is preferably 1500 to 1700 kg / mm ² .

Such a structure has an amount (M1) of metal components Zr and Hf in one or more hard phases selected from carbides, nitrides or carbonitrides containing Zr and / or Hf in the alloy.
And the amount (M2) of the metal component Ti in one or more hard phases selected from carbides, nitrides or carbonitrides containing Ti, m
expressed as a ratio of ol, 0.2 to 0.9, preferably 0.3.
It is obtained by holding in vacuum or under a constant nitrogen pressure in the range of 1350-1500 ° C. By controlling the holding time, the thickness and the maximum hardness can be controlled. In general,
When the amount of the hard phase containing Ti increases, that is, M1, M2
When the ratio of is decreased, the area of carbides containing Ti becomes wider and the maximum hardness thereof becomes higher.

Further, from immediately below the coating layer toward the inside of the base material, there is a region composed of WC particles having a coarser grain size than the WC grain size inside the alloy, and the thickness thereof is 1 to 100 μm. And

As described above, it is considered that the structure in which only the WC grain size on the surface of the alloy base material is made coarser enhances the resistance to cracking that occurs during cutting and improves the fracture resistance. If the thickness of the coarse-grained WC region is less than 1 μm, there is no effect, and if it exceeds 100 μm, the wear resistance is reduced. It is preferably 5 to 10 μm.

Here, the average size of the coarse grains WC is 1.5 to 5 times that of the inside of the alloy. Therefore, when the thickness of the coarse grain WC region is 1 μm, the average grain size is about 0.5.
This is the case of having fine particles WC of about μm. This structure is
The effect can be further expressed by combining with each of the above structures.

Although the reason why such a structure is formed is not clear, it can be achieved by including Zr, Hf carbides or carbonitrides in the alloy and heating at 1320 to 1360 ° C. in a nitrogen atmosphere. The WC grain size can be controlled by the nitrogen pressure, the holding temperature, the holding time, and the amount of alloy carbon. Generally, free carbon is present in the alloy, and the lower the nitrogen pressure, the more likely it is to coarsen. Although the reason is not clear, coarsening does not occur outside the temperature range.

A known technique for coarsening the WC grain size on the surface of the alloy is disclosed in Japanese Patent Laid-Open No. 190604/1993. However, the coarsening rate by this technique is about 1.2 times, and the coarsening of 1.5 times or more as in the present invention cannot be achieved at all.

Further, there is a layer in which the amount of the binder phase is enriched as compared with the inside of the alloy from immediately below the coating layer toward the inside of the base material, and the thickness thereof is 1 to 100 μm. . Such a layer improves the alloy surface toughness and is effective in improving the tool toughness. If this thickness is less than 1 μm, there is no effect, and if it exceeds 100 μm, the wear resistance decreases.
The thickness is preferably 5 to 30 μm.

In this structure, the degree of vacuum or nitrogen pressure in the sintering atmosphere is 1 to 5 in the process of disappearing or reducing nitrides such as Zr and carbonitrides, and the process of coarsening WC particles on the alloy surface.
It can be achieved by setting it to torr or less. Alternatively, it can be achieved by cooling in a high vacuum at a cooling rate of 5 ° C./min or less in the cooling process.

Further, a layer made of a nitride or carbonitride of Zr and / or Hf is provided from immediately below the coating layer toward the inside of the base material, and the layer has a thickness of 0.01 to 3.00 μm.
Is characterized in that. This layer has the effect of improving the adhesiveness with the coating layer, and also has the effect of suppressing the wear of the tool when the coating layer is damaged or worn during cutting.

If the thickness is less than 0.01 μm, this effect does not occur.
If it exceeds 3.00 μm, the toughness is lost. Preferably,
It is 0.5 to 2.0 μm. Incidentally, such a structure can be achieved by maintaining the alloy in a nitrogen atmosphere at a liquid phase appearance temperature or higher. Then, the thickness control is performed by controlling the nitrogen pressure, the holding temperature, and the holding time.

Further, the coated cemented carbide of the present invention is based on WC and a binder phase composed of one or more iron group metals, and further contains a metal carbide, nitride or charcoal containing Zr and / or Hf as a main component. Of a cemented carbide base material in which one or more hard phases selected from nitrides and one or more hard phases selected from carbides, nitrides, and carbonitrides of metals containing Ti as a main component coexist It is characterized in that it has one or more single-layer or multi-layer coating layers selected from carbides, nitrides, oxides, borides and aluminum oxides of metals of Groups 4a, 5a and 6a of the Periodic Table on the surface. It is a thing.

As described above, Zr, Hf carbides and the like are characterized in that the alloy strength is less deteriorated as compared with that of Ti and the alloy strength is high at high temperatures. However, a drawback is that the hardness is low. Therefore, in order to eliminate this drawback, the feature of the present invention is that a hard phase such as a Zr and / or Hf carbide and a hard phase such as a Ti carbide are allowed to coexist, thereby achieving both strength and hardness. is there. Here, Ti, Zr, and Hf can be added to the alloy in the form of carbide or carbonitride in which W is previously solid-dissolved. Z
For the carbide of Ti that coexists with the carbonitride of r, etc., Z
r, etc. may be solid-dissolved, and the carbonitride of Zr is H
Even if it is a solid solution with f, the effect of the present invention is not lost.

As described above, in order to make Zr and / or Hf carbides and the like coexist with Ti carbides and the like, they are selected from metal carbides, nitrides and carbonitrides containing Zr and / or Hf as the main components. The amount (M1 “mol”) of the metal components Zr and Hf in the one or more hard phases, and the content of the one or more hard phases selected from carbides, nitrides, and carbonitrides of metals containing Ti as the main component. The amount of metal component Ti (M2 “mol”) is m
When expressed by the ol ratio, it is necessary to have the following relationship for the same reason as above. 0.2 ≦ M1 / (M1 + M2) ≦ 0.9

That is, if it is less than 0.2, Zr and / or H
It is impossible to coexist a hard layer such as a metal carbide containing f as a main component and a hard layer such as a metal carbide containing Ti as a main component. That is, the object of the present invention cannot be achieved because double carbides and the like are easily formed. On the other hand, if it exceeds 0.9, the alloy hardness becomes insufficient. Preferably 0.3-0.
The range is 7.

In addition, one or more hard phases selected from carbides, nitrides, and carbonitrides of metals containing Zr and / or Hf as main components and Ti within a depth of 2 to 100 μm directly below the coating layer, and Ti. Carbides, nitrides of which the main component is
It is characterized by having a region (hereinafter referred to as a surface region) in which one or more hard phases selected from carbonitrides are reduced or eliminated. By having this surface layer region, the toughness of the alloy surface can be improved. Also in this case, similarly to the above, the structure is such that the nitride of Ti disappears or decreases in the entire region immediately below the coating layer by the addition of the nitride of Zr, Hf or the like. This structure makes it possible to significantly improve the toughness of the tool cutting edge as compared with the conventional alloy.

The thickness of this surface layer region is 2 μm from the surface of the base material.
If it is less than m, there is no effect of improving toughness, and if it exceeds 100 μm, wear resistance is lowered. Preferably, 5 to 50 μ
It is within m.

The thickness of the surface layer region can be controlled by controlling the metal carbide containing Zr and / or Hf as a main component in the raw material powder.
At least one hard phase selected from nitrides and carbonitrides, and T
In the range of 1350 to 1500 ° C., any one of one or more hard phases selected from carbide, nitride, and carbonitride of metal having i as a main component is added to the alloy as a nitride or carbonitride. It is carried out by holding in vacuum or under a constant nitrogen pressure and controlling the holding time.

Zr and / or Hf coexisting in the alloy
At least one hard phase selected from metal carbides, nitrides, and carbonitrides containing Ti as a main component and at least one hard phase selected from metal carbides, nitrides, and carbonitrides containing Ti as a main component The phases may be slightly solid-solved. In particular, when the amount of the binder phase is large, the precipitation of solute elements also increases and the mutual solid solution increases. However, essentially, at least one hard phase selected from a metal carbide, nitride, and carbonitride containing Zr and / or Hf as a main component, and a metal carbide and a nitride containing Ti as a main component, It is considered that one or more hard phases selected from carbonitride coexist.

Further, from the surface layer area toward the inside of the alloy, T
The amount of one or more hard phases selected from carbides, nitrides, or carbonitrides of a metal whose main component is i has a layer larger than that inside the alloy, and its thickness is 1 to 50 μm. It is characterized by

By providing a hard phase such as a metal carbide containing Ti as a main component inside the surface layer region, it is possible to minimize the plastic deformation of the cutting edge caused by the rise of the tool temperature. If the thickness is less than 1 μm inside the surface layer region, this effect does not exist, and if it exceeds 50 μm, the toughness decreases. It is preferably 5 to 10 μm.

In this region, after the hard phase such as Zr disappears,
It is considered that only Ti carbides, nitrides, and carbonitrides of Ti were precipitated from the liquid phase. In this case, Ti and WC react with each other to precipitate as a double carbide and a double nitride. That is, this region consists of WC, a metal carbide containing Ti as a main component, a carbonitride, a carbide containing Ti and WC, a carbonitride, and a binder phase metal.

From the surface layer area to the inside of the alloy, 1
The maximum hardness in the region of up to 50 μm is Hv hardness, load 500
Expressed in g, it is 1400 to 1900 kg / mm ² .
If it is less than 1400 kg / mm ² , there is no effect in improving the plastic deformation resistance, and if it exceeds 1900 kg / mm ² , toughness decreases. It is preferably 1500 to 1700 kg / mm ² .

Such a structure has a metal component Zr, H in one or more hard phases selected from carbides, nitrides or carbonitrides of metals containing Zr and / or Hf as a main component in the alloy.
an amount of f (M1) and a carbide of a metal containing Ti as a main component,
The amount (M2) of the metal component Ti in one or more hard phases selected from nitrides or carbonitrides is expressed as a mol ratio,
2 to 0.9, preferably 0.3 to 0.8, 135
It is obtained by holding in vacuum or under a constant nitrogen pressure in the range of 0 to 1500 ° C. By controlling the holding time, the thickness and the maximum hardness can be controlled. Generally, when the amount of hard phase containing Ti as a metal main component increases, that is, when the ratio of M1 and M2 decreases, the region of metal carbide containing Ti as a main component becomes wider, and its maximum hardness is also high. Become.

Further, from just below the coating layer toward the inside of the base material, there is a region composed of WC particles having a coarser grain size than the WC grain size inside the alloy, and the thickness thereof is 1 to 100 μm. And

As described above, it is considered that the structure in which only the WC grain size on the surface of the alloy base material is made coarser enhances the resistance to the occurrence of cracks during cutting and improves the fracture resistance. If the thickness of the coarse-grained WC region is less than 1 μm, there is no effect, and if it exceeds 100 μm, the wear resistance is reduced. It is preferably 5 to 10 μm.

Here, the average size of the coarse grains WC is 1.5 to 5 times that of the inside of the alloy. Therefore, when the thickness of the coarse grain WC region is 1 μm, the average grain size is about 0.5.
This is the case of having fine particles WC of about μm. This structure is
The effect can be further expressed by combining with each of the above structures.

The reason why such a structure is formed is not clear, but it can be achieved by including Zr, Hf carbides or carbonitrides in the alloy and heating at 1320 to 1360 ° C. in a nitrogen atmosphere. The WC grain size can be controlled by the nitrogen pressure, the holding temperature, the holding time, and the amount of alloy carbon. Generally, free carbon is present in the alloy, and the lower the nitrogen pressure, the more likely it is to coarsen.

Further, there is a layer in which the amount of binder phase is enriched as compared with the inside of the alloy from immediately below the coating layer toward the inside of the base material, and the thickness thereof is 1 to 100 μm. . Such a layer improves the alloy surface toughness and is effective in improving the tool toughness. If this thickness is less than 1 μm, there is no effect, and if it exceeds 100 μm, the wear resistance decreases.
The thickness is preferably 5 to 30 μm.

Here, by continuously reducing the amount of the binder phase from the position where the binder phase is most enriched toward the alloy surface, there is an effect of further improving the balance between toughness and wear resistance. By reducing the amount of binder phase in the vicinity of the alloy surface and increasing the hardness in the vicinity of the surface, it is possible to reduce the wear of the tool that occurs after the coating layer wears during cutting. Also, due to the difference in the coefficient of thermal expansion between the interior of the alloy and the binder phase enriched layer, the tensile stress acting on the enriched layer after sintering is relaxed by decreasing the amount of binder phase near the surface, which reduces toughness. Can be prevented.

The means for achieving this is that the degree of vacuum or nitrogen pressure in the sintering atmosphere is set to 1 in the process of disappearing or reducing nitrides such as Zr and carbonitrides, and the process of coarsening WC particles on the alloy surface.
It can be achieved by setting it to 5 torr or less. Alternatively,
In the cooling process, it can also be achieved by cooling under high vacuum at a cooling rate of 5 ° C./min or less.

On the outermost surface of the cemented carbide base material, Zr and / or
Or having a layer of Hf nitride or carbonitride,
The thickness of this layer is 0.01 to 3.00 μm. This layer has the effect of improving the adhesiveness with the coating layer, and also has the effect of suppressing the wear of the tool when the coating layer is damaged or worn during cutting.

If it is less than 0.01 μm, this effect does not occur.
If it exceeds 3.00 μm, the toughness is lost. Preferably,
It is 0.5 to 2.0 μm. Incidentally, such a structure can be achieved by maintaining the alloy in a nitrogen atmosphere at a liquid phase appearance temperature or higher. Then, the thickness control is performed by controlling the nitrogen pressure, the holding temperature, and the holding time.

The above-mentioned alloy base material contains oxygen in an amount of 0.03 to 0.3 wt%. Conventionally,
Poor sinterability is considered as one of the reasons why a cemented carbide containing Zr carbide is not put to practical use. The cause is the high affinity of Zr for oxygen. That is, Z
It is considered that the alloy containing the carbide of r contains a large amount of oxygen, and the poor wettability with the gas or liquid phase generated during the sintering process deteriorates the sinterability.

The present invention solves this problem by controlling the oxygen amount within the above range. Also, the oxygen-containing alloy is
It was also found that the cutting characteristics were improved compared to those that were not. The control of the oxygen amount can be performed by controlling the oxygen amount of the starting material or by setting the temperature raising process to a reducing atmosphere. If the amount of oxygen is less than 0.03 wt%, there is no effect on improving the cutting characteristics, and if it exceeds 0.3 wt%, the sinterability is significantly reduced. Preferably 0.05 to
It is 0.15 wt%.

Further, nitrogen is added to the alloy base material in an amount of 0.05 to 0.
It is characterized by containing 4 wt%. Since Zr and Hf nitrides are thermodynamically stable, they are difficult to decompose during the sintering process, and a relatively large amount of nitrogen can be contained in the alloy. This indicates that the composition ratio of nitride in the alloy is high. In general, nitrides such as Zr are excellent in thermal characteristics such as higher thermal conductivity than carbides and are effective in improving tool characteristics.

The amount of nitrogen is controlled by adjusting the amount of nitride in the alloy composition and the amount of carbon in the alloy, and setting the atmosphere as a nitrogen atmosphere in the temperature rising process and the sintering process and controlling the pressure thereof. If the amount of nitrogen is less than 0.05 wt%, the above effect does not occur and 0.4 w
If it exceeds t%, the sinterability will decrease. Preferably 0.07
˜0.25 wt%.

Then, a coating layer is formed on the surface of the cemented carbide described above as a base material. The coating layer is a single layer or multiple layers of one or more selected from carbides, nitrides, oxides, borides and aluminum oxides of metals of Groups 4a, 5a and 6a of the Periodic Table, and the ordinary CVD or PVD method. To form. By forming the coating layer in this way, the wear resistance of the alloy can be secured.

[0060]

【Example】

Example 1 An example of the present invention will be described below. As the raw material powder, WC, ZrC, ZrN, HfN, (Zr, H
f) C "of 50 mol% Zr composition", TiC, Ti
N, (Ti, W) C “30 wt% TiC, 25 wt% T
iN composition ”, TaC, (Zr, W) C“ 90mo
1% ZrC composition ”, (Hf, W) C“ 90 mol
% HfC composition ”, (Ti, Hf) C“ 50 mol
% Composition ”, TaN, Co, and Ni were prepared. Tables 1 and 2 (Unit of numerical value is wt%, provided that M1 / (M1 + M
2) is CNMG1 which is a complete powder having a composition shown in mol ratio).
After pressing into a chip in the shape of 20408, the temperature was raised from 1000 to 1450 ° C. at a rate of 5 ° C./min in an H ₂ atmosphere, and the sample was held in a vacuum of 10 ⁻¹ torr for 1 hour.
Cooled. The amount of oxygen in these alloys is 0.04w on average
It was t%. Then, using this as the base material, normal CV
In D, the inner layer was coated with 5 μm TiC and the outer layer was coated with 1 μm aluminum oxide.

[0061]

[Table 1]

[0062]

[Table 2]

The cutting performance was evaluated using each of the above samples. The cutting conditions of the evaluation test are shown below. Test 1 is for the flank wear amount, and Test 2 is for the defect rate. Test 1 (Abrasion resistance test) Cutting speed 350m / min Work material SCM415 Feed 0.5mm / rev Cutting time 20min Depth of cut 2.0mm

Test 2 (Fracture resistance test) Cutting speed 100 m / min Work material SCM435: 4-groove material Feed 0.2-0.4 mm / rev Cutting time 30 seconds Cutting 2.0 mm Repeated 8 times

The test results are shown in Table 3 together with the comparative product. Comparative product 1 is 4 wt% (Ti, W, Ta) C-6 wt% Co
And 2 is 4 wt% (Ti, W, Ta) C-10.
wt% Co. Incidentally, carbides such as Zr and Hf in the alloy were present as carbonitrides, and carbides such as Ti were present as double carbides by reacting with TaC.
The A layer in the table is a layer in which a hard layer such as Zr and Hf carbides disappears on the alloy surface.

[0066]

[Table 3]

(Example 2) Next, using Samples J to P of Example 1, after raising the temperature under the same temperature raising condition, 1400
℃ and held for 1 hour in an N ₂ atmosphere 2,10,50torr in, to form a layer consisting of only WC and the coupling layer on the alloy surface entire (WC-Co layer). Using this as a base material, TiC and TiN are formed in an amount of 3 μm each on the inner layer, and Al _{2 is} formed on the outer layer.
O ₃ was formed in a thickness of 4 μm and the same cutting test as in Example 1 was performed. The results are shown in Table 4.

[0068]

[Table 4]

Inside the alloy, a carbonitride of Zr, a carbonitride of Hf, and a double carbide of (Ti, W, Ta) C coexisted. In each of Samples L to N, a region having a binder phase of WC and a carbonitride of Ti or (Ti, W) CN was present inside the layer composed of only WC and Co.
This region is called the B layer. The B layers of J, K, and L are (Ti, T
a) A layer composed of CN, and the M, N, O, and P A layers are (Ti,
W, Ta) CN.

(Embodiment 3) Next, A, C.
Using a composition alloy of G, H, and I, after heating the alloy in vacuum,
After holding at 1450 ° C. for 1 hour, each was held at 1320 to 1360 ° C. in a nitrogen atmosphere at 5 torr for 1 hour and cooled.
A coating layer similar to that in Example 2 was formed using these as base materials,
The same cutting test as in Example 1 was performed. In addition, 0.15 wt% of oxygen was contained in these alloys. Table 5 shows the thickness and coarsening rate of the layer containing coarse grains WC and the thickness of the region enriched with the binder phase in the obtained alloy together with the cutting test results.

[0071]

[Table 5]

In the table, the WC grain coarsening rate is the W inside the alloy.
The average value of C grains is shown. In addition, in the alloy, 1340-13
What was held under the condition of 60 ° C. was that the Zr carbonitride layer was 0.5 μm in A, the same layer was 0.8 μm in C, G, H and I on the outermost surface of the alloy. As a result, Hf carbonitrides were present at 0.6 μm each. These thicknesses increase from 1.2 times to 2 times when the nitrogen pressure is increased from 2 times to 4 times.
On the other hand, the layer thickness of the coarse WC grains decreased rapidly.

Example 4 Sample A of Example 1 was heated in a vacuum atmosphere at a heating rate of 15 ° C./min and 10 ° C./mi.
When the temperature is raised at n, 5 ° C / min, and 1 ° C / min (A1, A2, A3, A4), oxygen is 0.35, 0.20, 0.15, 0.05 wt% in the alloy. Was included. Of these, A1 contained many cavities in the alloy, but almost no cavities were observed in A4, and A2 and A3 were intermediate between the two.

A coating layer of the same quality as in Example 2 was formed on these alloys, and the cutting speed was 45 for Test 1 of Example 1.
It went up to 0 m / min. A1 was defective in the initial stage, but the other ones had a wear resistance of 1.1 as compared with A of Example 1.
~ 1.5 times improved. From the above results, the oxygen content is 0.03 to 0.3 wt%, preferably 0.05.
~ 0.15 wt% is suitable.

(Example 5) Furthermore, the composition alloy J of Example 1 was used.
When the nitrogen contents of ~ P were analyzed, it became as shown in Table 6 (vacuum). Using these, at a temperature rising rate of 5 ° C./min, 120
When nitrogen is used as the atmosphere from 0 ° C. to the sintering temperature, Table 6 shows changes in nitrogen content with changes in nitrogen pressure. As shown in the table, the nitrogen content can be controlled by changing the nitrogen pressure.

[0076]

[Table 6]

(Example 6) As the raw material powder, WC, Zr
C, ZrN, HfC, HfN, (Zr, Hf) C "50
Mol% ZrC composition ”, TiC, TiN, (T
i, W) C “30 wt% TiC, 25 wt% TiN composition”, (Zr, W) C “90 mol% ZrC composition”, (Hf, W) C “90 mol% HfC composition”, (Ti , Hf) C “of 50 mol% composition”,
Co and Ni were prepared. Tables 7 and 8 (Unit of numerical value is wt
%, Where M1 / (M1 + M2) is the mol ratio), the finished powder having a composition of CNMG120408 is pressed into chips, and then heated in an H ₂ atmosphere from 1000 to 1450 ° C. at a rate of 5 ° C./min. It was warmed, held in a vacuum of 10 ^-1 torr for 1 hour and then cooled. The oxygen content in these alloys was 0.04 wt% on average. Then, by using this as a base material and performing ordinary CVD, 5 μm of Ti is formed in the inner layer.
C, the outer layer was coated with 1 μm of aluminum oxide.

[0078]

[Table 7]

[0079]

[Table 8]

Using the above samples, the cutting performance was evaluated (wear resistance and chipping resistance) under the same conditions as in Tests 1 and 2. The test results are shown in Table 9 together with the comparative product. Comparative product 1 is
4 wt% (TiW) C-6 wt% Co, and 2 is
4 wt% (TiW) C-10 wt% Co. Some alloys have an extinction layer such as a hard layer of Zr, Hf carbide on the surface thereof. This layer is abbreviated as A layer.

[0081]

[Table 9]

(Embodiment 7) Next, using Samples J to P of Embodiment 6, after raising the temperature under the same temperature raising condition, 1400
℃ and held for 1 hour in an N ₂ atmosphere 2,10,50torr in, to form a layer consisting of only WC and the coupling layer on the alloy surface entire (WC-Co layer). Inside the alloy, a Zr carbonitride, a Hf carbonitride, and a (TiW) C double carbide coexisted. For samples L to N, this WC
Inside the layer consisting only of Co and Co, WC and the binder phase and Ti
There were regions with carbonitrides or (TiW) CN. This region is abbreviated as B layer. The B layers of J, K and L are made of TiCN, and the A layers of M, N, O and P are (TiW).
It consisted of CN.

Using these as base materials, TiC, Ti
N was formed in an amount of 3 μm each, and Al ₂ O ₃ was formed in an outer layer of 4 μm, and the same cutting test as in Example 1 was performed. The results are shown in Table 10.

[0084]

[Table 10]

(Embodiment 8) Next, A, C.
Using a composition alloy of G, H, and I, after heating the alloy in vacuum,
After holding at 1450 ° C. for 1 hour, each was held at 1320 to 1360 ° C. in a nitrogen atmosphere at 5 torr for 1 hour and cooled.
The obtained alloy contained 0.15 wt% oxygen. Using these as base materials, a coating layer similar to that in Example 7 was formed, and the same cutting test as in Example 1 was performed. Table 11 shows the thickness and coarsening rate of the layer containing coarse grains WC and the thickness of the region enriched with the binder phase in the obtained alloy together with the cutting test results.

[0086]

[Table 11]

In the table, the WC grain coarsening rate is the W inside the alloy.
The average value of C grains is shown. In the alloy held at 1320 ° C., the amount of binder phase continuously decreased from the binder phase enriched region to the surface of the alloy. Also, 1340
What was kept under the condition of ~ 1360 ° C was
In A, the Zr carbonitride layer is 0.5 μm, in C, the same layer is 0.8 μm, and in G, H, and I, the Hf carbonitride layer is 0.6 μm. It was These thicknesses are
When the nitrogen pressure was increased from 2 times to 4 times, it was increased from about 1.2 times to 2 times, while the layer thickness of the coarse WC particles was rapidly reduced.

Example 9 Sample A of Example 6 was heated in a vacuum atmosphere at a heating rate of 15 ° C./min and 10 ° C./mi.
When the temperature is raised at n, 5 ° C / min, and 1 ° C / min (A1, A2, A3, A4), oxygen is 0.35, 0.20, 0.15, 0.05 wt% in the alloy. Was included. Of these, A1 contained many cavities in the alloy, but almost no cavities were observed in A4, and A2 and A3 were intermediate between the two.

A coating layer of the same quality as that of Example 7 was formed on these alloys, and the cutting speed was 45 for Test 1 of Example 1.
It went up to 0 m / min. A1 was damaged at the initial stage, but the other ones had a wear resistance of 1.1 as compared with A of Example 6.
~ 1.5 times improved. From the above results, the oxygen content is 0.03 to 0.3 wt%, preferably 0.05.
~ 0.15 wt% is suitable.

(Example 10) Further, when the nitrogen contents of the composition alloys J to P of Example 6 were analyzed, the results are shown in Table 12 (vacuum). Using these, at a temperature rising rate of 5 ° C./min, 1
If the atmosphere from 200 ° C to the sintering temperature is nitrogen,
Table 6 shows changes in nitrogen content with changes in nitrogen pressure. As shown in the table, the nitrogen content can be controlled by changing the nitrogen pressure.

[0091]

[Table 12]

(Embodiment 11) Samples having the BB composition of Example 1 and the AA composition of Example 6 were used, and the temperature was raised under the same conditions 1
The surface of the alloy was kept at 450 ° C. under a high vacuum of 10 ⁻³ torr for 1 hour to form a surface layer region (A layer made of WC—Co) consisting only of WC and a binder phase. At this time,
The thickness of the A layer was 10 μm in BB as in Example 1, and in AA as well as in Examples 1 and 6, both were enriched from the inside of the alloy. However, the amount of binder phase decreases continuously from the position where the binder phase is most enriched toward the alloy surface,
Only this point was different from the results of Examples 1 and 6. As a result of cutting evaluation of these samples under the conditions of Test 1 and Test 2, the wear amount = 0.19 mm and the loss rate = 20% for the BB composition, and the wear amount = 0.20 mm and the loss rate = 21% for the AA composition. In all cases, the balance between the wear resistance and the fracture resistance was improved as compared with Examples 1 and 6.

Example 12 First, WC-4% TiC-
Complete powder consisting of a composition (wt%) of 2% ZrN-6% Co is pressed into the shape of CNMG120408 to obtain chips. This is vacuum-heated to 1450 ° C. for each 5, 10,
After holding under nitrogen pressure of 30, 50 torr for 1 hour,
After cooling, four types of base materials were obtained. A TiC coating with a thickness of 5 μm was formed on the surface of these base materials by a usual CVD method, and further a 1 μm-thick aluminum oxide coating was further coated thereon. The respective alloys are referred to as Examples A, B, C and D.

As a result of analyzing this alloy, Zr was found in the base metal.
The nitride and the hard phase of TiC coexisted, and a region where these hard phases disappeared was confirmed near the surface of the base material. The thickness of this vanishing layer is A-50, B-30, C-10, D, respectively.
It was -5 μm. In addition, the disappearance layer was twice as rich in the amount of binder phase as compared with the inside of the base material. The ratio of Zr and Ti "Zr (mol%) / (Ti (mol%) + Zr
(Mol%)) was 0.22, and the stoichiometric ratio of Zr nitride in the alloy was 1 or less.

Using such cemented carbide, cutting was performed under the conditions of Test 1 and Test 2 to examine the wear resistance and toughness. For comparison, ordinary cemented carbide (WC-5% Ti
A similar test was performed for C-3% TaC-6% Co "Comparative Example"). The test results are shown in Table 13.

[0096]

[Table 13]

As shown in the table, it was confirmed that the comparative examples had many defects in all the tests, whereas all the examples had excellent wear resistance and toughness.

(Example 13) Next, an example of producing a cemented carbide of the present invention having a composition different from that of Example 12 will be described. WC-6%
4% TiN-2% for each Co composition (% by weight)
ZrC, 2% TiC-4% ZrN, 2% TiC-8% Z
The finished powder containing rN was pressed into a shape of CNMG120408 to obtain chips. Each of these from room temperature to 1300
The temperature was raised up to 10 ° C./min from 1 ° C. to 1450 ° C. in a vacuum at a rate of 2 ° C./min, held at the same temperature for 1 hour, and then cooled to obtain three kinds of base materials. A TiC coating with a thickness of 5 μm was formed on the surface of these base materials by a usual CVD method, and further a 1 μm-thick aluminum oxide coating was further coated thereon. The respective alloys are referred to as Examples E, F and G.

When these alloys were analyzed, Ti nitride and Zr carbonitride were found in Example E, and Ti and Zr were found in F.
The carbonitride of No. 2 and the carbonitride of Ti and the nitride of Zr coexisted in the same G. The thickness of each of the examples E and F was 1
There was a layer in which the 0.5 μm Ti-based and Zr-based hard phases disappeared. In Example G, there was a layer in which only the carbonitride phase of Ti having a thickness of 5 μm disappeared, and the nitride of Zr did not disappear. Further, the ratios of Zr and Ti in Examples E, F and G were 0.22, 0.54 and 0.70, respectively. The same cutting test as in Example 12 was performed on these alloys and comparative examples (same composition as Example 12). The results are shown in Table 14.

[0100]

[Table 14]

As shown in the table, it was confirmed that, in the case of this example as well, the example was superior in wear resistance and toughness to the comparative example.

(Embodiment 14) Next, an example in which a cemented carbide of the present invention having a composition different from that of each of the above-described embodiments is manufactured will be shown. WC-6
% Co composition (wt%) with 2% TiN-8
% ZrC, 2% TiC-10% ZrN, 1% TiC-8
% ZrN, 1% TiC-10% ZrN-added complete powder was pressed into a shape of CNMG120408 to obtain chips. 10 ℃ / m from room temperature to 1250 ℃
in, the temperature was raised in vacuum from 1250 ° C to 1450 ° C at a rate of 2 ° C / min, and at the same temperature in vacuum and nitrogen pressure of 5 to
After holding for 1 hour under two conditions of rr, it was cooled to obtain four kinds of base materials. A TiC coating with a thickness of 5 μm is formed on the surface of these base materials by a normal CVD method, and a thickness of 1
Coated with μm aluminum oxide. The respective alloys are referred to as Examples H, I, J and K.

Analysis of these alloys revealed that the T
i) carbide, nitride, or Zr-based hard phase coexists, and those treated in vacuum near the surface of each base material are Ti carbide,
Nitride or disappeared, and those treated under a nitrogen pressure of 5 torr had reduced this. Further, Examples H, I, J, K
The ratio of Zr and Ti is 0.70, 0.74, 0.8
It was 2,0.85. These alloys were subjected to the same cutting test as Test 1 and Test 2. Table 15 shows the result and the thickness of the layer in which the carbides, nitrides, or the Ti carbides are eliminated or reduced.

[0104]

[Table 15]

As shown in the table, it was confirmed that the wear resistance and toughness of this example are also excellent.

[0106]

As described above, the coated cemented carbide of the present invention has both excellent wear resistance and toughness, and when used as a cutting tool, it can perform high-efficiency machining that could not be achieved by conventional techniques. be able to.

Claims (16)

[Claims] 1. A binder phase metal comprising WC and one or more iron group metals, and a carbide of a group 4a, 5a, 6a metal of the periodic table,
In a coated cemented carbide having a coating layer on the surface of a cemented carbide base material composed of two or more hard phases selected from nitrides and carbonitrides, Zr and / or Hf are mainly contained in the hard phase. One or more selected from a carbide, a nitride and a carbonitride of a metal as a component and one or more selected from a carbide, a nitride and a carbonitride of a metal containing Ti as a main component coexist, and the coating layer Is a single layer or multiple layers of at least one selected from carbides, nitrides, oxides, borides and aluminum oxides of metals of groups 4a, 5a and 6a of the periodic table, a cemented carbide coating alloy characterized in that . 2. One or more selected from a carbide, a nitride and a carbonitride of a metal based on WC and a binder phase composed of one or more iron group metals and further containing Zr and / or Hf as a main component. On the surface of the cemented carbide base material in which the hard phase of (1) and one or more hard phases selected from the carbides, nitrides, and carbonitrides of the metal containing Ti as the main component coexist. 5a, 6
A coated cemented carbide having a single-layer or multi-layer coating layer selected from carbides, nitrides, oxides, borides and aluminum oxides of Group a metals. 3. Amount of metal components Zr and Hf in at least one hard phase selected from carbides, nitrides, and carbonitrides containing Zr and / or Hf as a main component (M1 “mol”).
And the amount of the metal component Ti (M2 “mol”) in one or more hard phases selected from carbides, nitrides, and carbonitrides containing Ti as the main component in terms of mol ratio, The coated cemented carbide according to claim 1 or 2, which is in a relationship. 0.2 ≦ M1 / (M1 + M2) ≦ 0.9 4. The coated cemented carbide according to claim 1 or 3, wherein the periodic table 5a, 6 is provided from immediately below the coating layer toward the inside of the base material.
a carbide of a metal in which at least one hard phase selected from a carbide, a nitride, and a carbonitride of a group a metal disappears and Zr and / or Hf is a main component;
At least one hard phase selected from nitrides and carbonitrides, and T
It has a surface layer region in which one or more hard phases selected from carbides, nitrides, and carbonitrides of metal containing i as a main component are reduced or eliminated, and the thickness thereof is 2 to 100 μm. And coated cemented carbide. 5. The coated cemented carbide according to claim 2 or 3, wherein a metal carbide or nitride containing Zr and / or Hf as a main component is provided over a depth of 2 to 200 μm from immediately below the coating layer. It has one or more hard phases selected from carbonitrides and a surface layer region in which one or more hard phases selected from metal carbides containing Ti as a main component, nitrides and carbonitrides are reduced or eliminated. A coated cemented carbide characterized in that 6. The coated cemented carbide according to claim 4 or 5, wherein from the surface layer region to a depth of 1 to 50 μm inside the alloy,
A coated cemented carbide, characterized in that the amount of at least one hard phase selected from carbides, nitrides, or carbonitrides of a metal containing Ti as a main component has a region larger than that in the interior of the alloy. 7. The coated cemented carbide according to claim 4, 5 or 6, wherein from the surface layer region to a depth of 1 to 50 μm inside the alloy,
A coated cemented carbide having a region consisting of at least one hard phase selected from carbides, nitrides or carbonitrides containing Ti and W as main components, WC and a binder phase. 8. A surface layer region within 50 μm from the surface of the base material, in which only one or more hard phases selected from carbides, nitrides and carbonitrides of a metal containing Ti as a main component are reduced or eliminated. The coated cemented carbide according to claim 2 or 3, characterized in that. 9. The coated cemented carbide according to claim 8, wherein
A region in which the amount of one or more hard phases selected from a carbide containing Ti as a main component, a nitride, or a carbonitride is larger than the inside of the alloy over a depth of 1 to 50 μm from the surface layer region to the inside of the alloy. A coated cemented carbide characterized by having. 10. The coated cemented carbide according to claim 4, 5, 6, 7, 8 or 9, wherein 1 to the inside of the alloy from the surface layer region.
Maximum hardness over a depth of 50 μm is Hv hardness, load 500 g, 1400 to 1900 kg / mm ²
A coated cemented carbide having a region in the range of. 11. Claims 1, 2, 3, 4, 5, 6, 7,
The coated cemented carbide according to 8, 9, or 10, which has a region composed of WC particles having a coarser grain size as compared with the WC grain size inside the alloy from immediately below the coating layer to a depth of 1 to 100 μm inside the base material. A coated cemented carbide characterized in that 12. The method according to claim 4, 5, 6, 7, 8, 9, and 10.
Or the coated cemented carbide according to 11, wherein the coating has a layer in which the amount of binder phase is enriched from immediately below the coating layer to a depth of 1 to 100 μm in the base material as compared with the inside of the alloy. Coated cemented carbide. 13. The method according to claim 4, 5, 6, 7, 8, 9, 1.
The coated cemented carbide according to 0, 11 or 12, which is from immediately below the coating layer to a depth of 1 to 100 μm inside the base material,
Compared to the inside of the alloy, it has a layer enriched in binder phase, and the amount of binder phase decreases continuously from the position where the binder phase is most enriched in this region toward the alloy surface. A coated cemented carbide characterized by: 14. Claims 1, 2, 3, 4, 5, 6, 7,
The coated cemented carbide according to 8, 9, 10, 11, 12 or 13, wherein Zr and / or H are formed on the outermost surface of the cemented carbide base material.
A coated cemented carbide, comprising a layer made of a metal nitride or carbonitride containing f as a main component, and having a thickness of 0.01 to 3.00 μm. 15. A cemented carbide base material containing 0.03 to 0.03% of oxygen.
0.30 wt% is contained, The claim 1 characterized by the above-mentioned.
2,3,4,5,6,7,8,9,10,11,12,
The coated cemented carbide according to 13 or 14. 16. Nitrogen is added to the cemented carbide base material in an amount of 0.05 to 0.05.
The content of 0.40 wt% is included.
2,3,4,5,6,7,8,9,10,11,12,
The coated cemented carbide according to 13, 14 or 15.