JPH07285001A - Coated cutting tool - Google Patents

Abstract

PURPOSE:To provide a coated cutting tool on which a strong and highly abrasion resistant coating is formed. CONSTITUTION:A surface of a base material made of tungsten carbide based carbide alloy is coated by a coating layer comprising an inner layer, which is constructed of a multiple layer consisting of the first layer touching the base material and made of titanium carbide nitride, the second layer formed on the first layer and made of titanium carbide nitride having hardness of 1600-2400kg/mm<2>, and a coating made of titanium carbide, titanium nitride, or the like, and an outer layer, which is constructed of a monolayer or a multiple layer made of one kind or more material selected from aluminum oxide, zirconium oxide, hafnium oxide, titanium carbide, titanium carbide nitride, and titanium nitride. In this way, not only high abrasion resistance in the whole of the coating layer but also strong adhesion between the coating layer and the base material can be provided, while good peeling resistance in cutting is also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated cutting tool having a coating film which is tough and has excellent wear resistance.

[0002]

2. Description of the Related Art As the environment in which cutting tools are used becomes more and more severe, chemical vapor deposition (CVD) or physical vapor deposition (PVD) is applied to the surface of a tungsten carbide based cemented carbide base material.
So-called coated cutting tools having various types of ceramic coatings formed by various means such as a method) have been widely used. Examples of such coatings include titanium carbide (TiC), titanium nitride (TiN) and alumina (Al
₂ O ₃ ) There is a film. These single-layer or multi-layer coatings not only improve the wear resistance of the cutting tool, but also prevent reaction between the work material and the cutting tool during cutting, resulting in a longer tool life. This is already known. However, when these coated cutting tools are used for machining, especially those requiring high wear resistance of the coating layer at high temperatures, such as high-speed cutting, or those requiring large numbers of machining such as small article machining. The wear resistance of the coating layer is insufficient due to processing such as frequent biting of the material, and the tool life is shortened due to damage of the coating layer. Further, the coating film formed by the thermal CVD method is superior in adhesion to the base material as compared with the PVD method, but depending on the type of the base material, the interface between the base material and the cutting edge ridge portion, which particularly contributes to performance, is brittle. The η phase, which is a chemical layer, tends to precipitate thickly, and the coating layer falls off together with this η phase during cutting, which causes wear to progress, leading to variations in tool life, and the coating layer can sufficiently improve the service life. In some cases, it could not be said that it contributed.

Solving these conventional problems
In order to ₃CN) and other organic C
Titanium carbonitride film by thermal CVD method using N compound (T
A method for forming iCN) is drawing attention (Japanese Patent Laid-Open No. 50-1).
17809, Sho 50-109828, etc.). this
The method is performed at a slightly lower temperature than the conventional thermal CVD method.
Generally, medium temperature CVD because coating is possible.
Method (MT-CVD method). Conventional thermal CVD
In the method (high temperature CVD method; referred to as HT-CVD method),
During the formation of the tan-based coating, elements (especially charcoal)
Movement of the base material occurs, and an altered layer (called η phase) on the surface of the base material
Co₃W₃Double carbides such as C) are produced. HT like this
-The cause of element migration in the CVD method is coating
First of all, the temperature is high (usually 1000 ° C to 1050 ° C).
Conceivable. Especially when transferring carbon, the temperature is high.
In addition to the above, the supply of carbon from the gas phase during film formation was insufficient.
Between the coating being formed and the surface of the base metal,
A concentration gradient of element occurs, and the film absorbs carbon from the base material.
It is considered that a phenomenon has occurred. Against this
The MT-CVD method has a slightly low coating temperature (800 ° C).
Up to 900 ° C), the supply of C and N from the gas phase was sufficient.
Therefore, the η phase should not occur even at the interface of the ridge of the cutting edge.
Has been.

A number of patents which have adopted the MT-CVD method have been filed thereafter. For example, in JP-A-3-64469 and JP-A-3-87368, in both cases, a TiCN film is formed directly on the surface of a cemented carbide base material by the MT-CVD method, and then an alumina layer is formed by the HT-CVD method. Al ₂
Tools having a multilayer film of O ₃ ) or titanium nitride (TiN) have been proposed. Further, in JP-A-62-99467, a TiCN film having a crystal grain size of 0.5 μm or less and /
Alternatively, a single-layer or laminated film in which a TiN film is coated with a thickness of 0.5 to 5.0 μm is disclosed. As a method of forming the TiCN film, MT at a deposition temperature of 700 to 900 ° C. is disclosed.
A CVD method is disclosed. However, even in this method, the film in contact with the base material was the TiCN film.

However, while the present inventors proceeded with research on a cemented carbide member coated with a TiCN film, MT-C
The adhesion between the TiCN film by the VD method and the cemented carbide base material is
It became clear that it often became unstable. The cause of this was MT-CV
It was found that during the formation of the TiCN film by the D method, the binding phase cobalt (Co) on the surface of the cemented carbide base material was corroded (etched) by chlorine gas generated as a reaction product. Further, the thermal decomposition of an organic CN compound such as acetonitrile is easily affected by the chemical bonding state on the surface of the base material, and often free carbon is produced. The generation of such free carbon deteriorates the adhesion between the film and the base material, and by combining with the generation of the interface-altered layer described above, MT-CVD
It made the performance of the coated cutting tool by the method unstable. Cemented Carbide as the base material and TiC, TiN,
In a coated cemented carbide in which TiCN is coated on a multilayer film, a coated cemented carbide in which the innermost layer adjacent to the substrate is 0.1 to 1.0 μm TiN is also disclosed (JP-A-61-17).
No. 0559), which relates to a film formed by the PVD method. Further, regarding the hardness of the coating, it is generally considered that the higher the hardness, the better the abrasion resistance, but if the hardness is simply high, the toughness of the coating decreases and the chip tends to chip easily. Had a problem that it was prone to abnormal wear and could not be put to practical use. Therefore, it is necessary to balance hardness and toughness in a well-balanced manner. For the fine structure of the film, see JP-A-62-9946.
No. 7, the TiCN film forming the coating layer and / or
Alternatively, it has been proposed that the TiN film crystal grains having a diameter of 0.5 μm or less is optimal, but it is not realistic because there is no description about the evaluation method of the crystal grain shape and grain size.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and maximizes the merits of the TiCN film by the MT-CVD method, thereby making the coated cutting tool more reliable than before. Is intended to provide. And in order to achieve this object, while preventing the deterioration of the base material surface during coating formation, a coated cutting tool having a coating structure capable of suppressing the precipitation of undesired substances at the interface between the coating and the base material. In addition to providing macroscopic coating structure optimization, it also provides a coated cutting tool that has an optimum structure and an optimum range of mechanical strength from the viewpoint of microscopic structure and hardness. is there.

[0007]

Means for Solving the Problems As a result of various studies conducted by the present inventors to solve the above-mentioned problems, MT-CV
The above problem is that the surface of the base material is first coated with the TiN film as the first layer and then with the TiCN film as the second layer, instead of directly coating the surface of the base material with the TiCN film by the D method. It was found to be effective in solving the problem. Also,
With respect to the TiCN film which is the second layer, it has been found that the microhardness, the crystal structure and the size of the particles have a great influence on the characteristics of the film. The present invention has been completed based on these findings.

That is, according to the present invention, (1) one or more hard components selected from the group consisting of carbides, nitrides and carbonitrides of IVa, Va or VIa group elements in the Periodic Table of Elements as main components and Group VIII. In a coated cutting tool formed by forming a hard coating on the surface of a base material which is an alloy consisting of a metal component by a chemical vapor deposition method, the inner layer on the surface of the base material, the first layer in contact with the base material is titanium nitride, The second layer thereover is titanium carbonitride having a hardness of 1600 to 2400 kg / mm ² , and one or more selected from the group consisting of carbides, nitrides, carbonitrides and boronitrides of titanium. The outer layer is made up of one or more monolayers selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide, titanium carbide, titanium carbonitride, and titanium nitride. Or coated cutting tool characterized by comprising coating the coating layer is composed of multiple layers,
(2) IVa in the Periodic Table of Elements as the main component,
A hard coating is formed on the surface of a base material, which is an alloy of one or more hard components selected from the group consisting of carbides, nitrides and carbonitrides of Va or VIa elements, and a Group VIII metal component, by a chemical vapor deposition method. In the coated cutting tool, the thickness of the first layer on the surface of the base material is 0.1 to 0.1
Titanium nitride having a thickness of 2.0 μm is coated, and titanium carbonitride having a hardness of 1600 to 2400 kg / mm ² is coated thereon as a second layer. Further, titanium carbide, nitride or carbonitride is further coated thereon. And a single layer or multiple layers consisting of one or more selected from the group consisting of boronitride,
These inner layers are coated with, as an outer layer, a coating layer composed of one or more single layers or multiple layers selected from the group consisting of aluminum oxide, titanium carbide, titanium carbonitride and titanium nitride. Coated cutting tools,
(3) The titanium carbonitride of the second layer is composed of columnar crystal grains, and the average crystal grain size of the titanium carbonitride is in the range of 0.1 to 1 μm when the film thickness of the second layer is 4.0 μm or less. The coated cutting tool according to (1) or (2) above, wherein the thickness of the second layer exceeds 4.0 μm and is 20 μm or less, the range is 0.5 to 3.0 μm.

[0009]

The first point of the present invention resides in that the surface of the base material is not directly coated with the TiCN film by the MT-CVD method, but is coated with the TiN film. The reason for doing this is described below. As mentioned above, MT-CVD
The adhesion between the TiCN film and the base material by the method is often unstable. From a thorough analysis of this cause,
Free due to the fact that the binder gas (Co etc.) on the surface of the cemented carbide is corroded (etched) by the chlorine gas contained in the coating atmosphere and the decomposition of the organic CN compound on the base material is unstable. It turned out that carbon is easily generated. Corrosion of the binder phase leads to a decrease in the toughness of the base metal surface, and the generation of free carbon reduces the adhesion between the coating and the base material, and the combination of these reduces the performance of the coated cutting tool by the MT-CVD method. It is thought to have been done. Especially, the corrosion of the binder phase is
This is a phenomenon that has not occurred in the T-CVD method.
-It is considered to be a problem peculiar to the CVD method.

As a result of extensive studies, when the surface of the base material is coated with the TiN film as the first layer, the corrosion of the base material of the cemented carbide is suppressed, and the T-film is formed on the surface of the base material by the MT-CVD method.
It was found that the generation of free carbon and the like is suppressed when the iCN film is coated. This effect can be obtained by using the TiN film as the first layer because the TiN film of the first layer in contact with the base material acts as a protective film against corrosion of the base material such as cemented carbide. At the same time as the TiC by the MT-CVD method.
It is presumed to stabilize the surface reaction when forming the N film. The thickness of the TiN coating film of the first layer is preferably 0.1 μm or more. The thickness of this TiN film is 2.
If it exceeds 0 μm, the wear resistance as a tool rather deteriorates, so 2.0 μm or less is preferable. As a method for forming this TiN film, a known CVD method using nitrogen gas, hydrogen gas, titanium tetrachloride or the like as a raw material can be used. The TiN film of the first layer is used as an intermediate layer, and a TiCN film is formed thereon by the MT-CVD method.

The second point of the present invention is that the TiCN film formed on the TiN film has a specific hardness or a specific hardness and structure. That is, the second layer of TiCN
The hardness of the film is in the range of 1600 to 2400 kg / mm ² , and the TiCN is composed of columnar crystal grains.
The average crystal grain size of CN is in the range of 0.1 to 1 μm when the film thickness of the second layer is 4.0 μm or less, and is 0.1 when the film thickness of the second layer exceeds 4.0 μm and 20 μm or less. 5-
A film in the range of 3.0 μm is most suitable. The hardness of the coating referred to here means micro Vickers hardness or Knoop hardness. Specifically, the coating surface is polished in parallel with the base material or at an appropriate angle, and a Vickers or Knoop impression is made on the polished surface with a load of 25 to 50 g and a load time of 10 to 20 seconds, It is measured by measuring the size of the indentation. When measuring the hardness of a thin film for tools, if the penetration depth of the indenter exceeds the film thickness, the correct hardness cannot be measured.Therefore, it is necessary to select a measurement method and load so that the penetration depth is at least half the film thickness or less. There is. However, the dynamic hardness measurement method developed as a thin film hardness measurement method (a method for obtaining hardness from the relationship between the indenter indentation depth and indentation load) is
Since it is difficult to compare the obtained measured value with the Vickers hardness (or Knoop hardness) in absolute value, it is not preferable as a hardness measuring method for a coated cutting tool.

On the other hand, the average crystal grain size means that the thickness of the film is 0.
When the thickness is 1 to 20 μm, it refers to the size of the crystal grain at the tip of the columnar crystal, that is, the thickness of the tip of the columnar crystal, when observed from the surface of the film with a scanning electron microscope or the like. The average grain size is evaluated by dividing the length of one side of 10 μm by 10 which is the square root of 100 when 100 grains are seen in the visual field of a predetermined size in a surface photograph taken by a microscope. Therefore, it is estimated to be 1 μm. At this time, the crystal grains that slightly protrude from the visual field are counted as 0.5. However, in the case of a laminated film, it is not possible to directly observe the growth surface of the film, so the evaluation method of the average crystal grain size is that the coating layer of the coated cemented carbide member is parallel to the base metal or at an appropriate angle ( 1
It is preferably 0 ° or less) and polished, and the grain boundaries are lifted by using an appropriate corrosive solution (mixed solution of hydrofluoric acid, nitric acid and distilled water), and then observed with a scanning electron microscope. , A method of observing a sample processed into a thin piece with a transmission electron microscope is used. In each case, the crystal grain size is calculated from a photograph taken at an appropriate magnification. However, the calculation of the crystal grain size by the X-ray diffraction method is not preferable because the calculated value is easily affected by the residual stress of the film.

The TiCN film having the specific hardness or the specific hardness and structure as described above can be easily formed by the MT-CVD method. This second layer of TiCN
The film is formed by using acetonitrile, hydrogen gas, titanium tetrachloride, etc. as the main raw material, and further adding nitrogen or argon to the raw material gas, the substrate temperature is 800 to 980 ° C., and the pressure in the reaction tank is 4
It is carried out at 0 to 150 Torr.

The reason why the TiCN film has a specific hardness and structure as described above is as follows. First, regarding the film hardness, it is said that the higher the hardness is, the more excellent the abrasion resistance is, but this is a tendency of so-called rubbing wear, which is mild wear near room temperature. Therefore,
Titanium-based ceramics for cutting tools, namely TiN and TiC
When N and TiC are applied, TiC is said to be the most excellent in order to improve durability against rubbing wear. However, in the case of frictional wear accompanied by shock and heat, such as cutting tools, toughness and oxidation resistance are inferior when the hardness is simply high, so abnormal wear often occurs and stable life is often not exhibited. . Therefore, in order to obtain a stable and long life, it is desirable to have an appropriate hardness as well as a fine structure that is hard to break or that even if it breaks, it ends up on a small scale, and also has oxidation resistance. .
For this purpose, TiN has excellent oxidation resistance.
And TiCN, which has the advantages of both TiC and high hardness, is optimal. In the present invention, the hardness and the fine structure of this TiCN coating are examined to determine the optimum range.

That is, although the fine structure of the TiCN coating will be described later, the hardness of the coating is 1600 kg /
It has been found that a value of mm ² or more and 2400 kg / mm ² or less is optimal for the purpose of the present invention. Titanium-based ceramics have the property that, when the composition is expressed by Ti ₁ C _x N _1-x (where 0 ≦ x ≦ 1), the hardness increases as x increases, and when x = 0 (that is, TiN), When 200
From 0 kgf / mm ² to 3000 kgf / mm ² when x = 1 (ie TiC), with increasing value of x,
It is said that the hardness increases almost linearly. But the hardness is
In addition to the ratio of C and N, it depends on the ratio of Ti, impurities, residual stress, fine structure, and the like. In the present invention, the film called TiCN has a hardness of 16 although it does not matter whether any of these various factors act.
It was found that the most stable tool coating was obtained when the weight was from 0 to 2400 kg / mm ² . Hardness is 1600kg
If it is less than / mm ² , the wear is accelerated, which is not preferable. On the other hand, if the hardness exceeds 2400 kg / mm ² , the toughness is extremely reduced and chipping easily occurs, which is not preferable.

If the hardness of the TiCN coating is within the above range, a tool having a relatively stable life can be obtained. However, if the microstructure of the coating has an optimum structure as described below, further preferable. The TiCN film coated by the MT-CVD method has various fine structures depending on the conditions of coating. According to the research conducted by the present inventors, it has been found that such typical fine structures can be classified into the following three types, types 1-3. (Type 1) A coating surface composed of secondary particles in which dome-shaped primary particles are aggregated. In many cases, the crystal grain size of the primary particles is less than 0.1 μm. This occurs when the growth rate of the film is 2 μm / hour or more because the concentration of the raw material gas in the film forming atmosphere is too high, or when the vapor deposition temperature is low. (Type 2) The coating surface is composed of clear primary particles having a polygonal shape, and has a columnar cross-sectional structure, and each column is relatively thin. In other words, the growth of the columnar crystal grains is initially tapered, but the thickness of the column does not change much after the film thickness exceeds 2 μm. This is observed when the vapor deposition temperature is proper and the concentration and ratio of the source gas are proper. The specific relationship between the average crystal grain size and the film thickness is as follows.・ When the film thickness is 4.0 μm or less, the particle size is 0.1 to 1 μm. ・ When the film thickness is 4.0 to 20 μm, the particle size is 0.5 to 3.
0 μm This type exhibits the preferred properties for the purposes of the present invention. In a cutting tool, a TiCN layer having a thickness of more than 20 μm is not realistic because it causes deterioration of the tool toughness. (Type 3) The surface of the coating is composed of clear primary particles of polygonal shape, and has a columnar cross-sectional structure, and each column becomes thicker as the coating grows. In other words, the growth of the columnar crystal grains is tapered, which does not apply to the relationship between the type 2 crystal grain size and the film thickness, and the column thickness increases as the film thickness increases. . This is observed when the vapor deposition temperature is high or when the film growth rate is slow because the source gas concentration is low.

As described above, a TiN film of the above three types was formed on the base material on which the TiN film was formed as a base intermediate layer, a tool was prototyped, and flank wear resistance in a cutting test was evaluated. It was found that the wear behavior of each type of coating has the following characteristics. (Type 1) The wear resistance of the coating is low, and it progresses rapidly from normal wear of the coating to exposure of the base metal, welding, and abnormal wear. The (Type 2) coating shows normal wear, but because of the high wear resistance of the coating, it exhibits a very long tool life. (Type 3) As with Type 2, the coating has high wear resistance,
Although the tool life is long, the coating often causes localized wear such as chipping, which causes abnormal damage to the base material. It is presumed that the type 1 coating is worn while collapsing because the TiCN coating has low crystallinity and the bonding between the particles forming the coating is weak. On the other hand, although the type 3 coating has excellent wear resistance, the coating tends to be destroyed on a large scale due to the large crystal grain size, which is presumed to lead to abnormal wear such as chipping of the tool cutting edge. On the other hand, the type 2 coating has excellent wear resistance and stably shows normal wear, so that it does not cause abnormal wear of the tool and has extremely suitable characteristics for the purpose of the present invention. ing.

The specific contents of the characteristics of each of these coatings will be described in detail in the examples. In any case, a TiCN film having the characteristics described in the claims has stable and excellent cutting performance. It is necessary to obtain the tool shown. Further, in the present specification, although the base material is described only for the tungsten carbide-based cemented carbide, the same effect can be obtained even in the cermet in which the titanium carbonitride-based hard phase is sintered with the metal bonding phase. Therefore, the coating structure of the tool of the present invention can be applied to titanium carbonitride-based cermet as well as cemented carbide.

[0019]

The present invention will be described in more detail with reference to the following examples. <Example 1> (Structure of Inner Layer) After forming a TiN film having a thickness of 0.6 μm by a known thermal CVD method on the surface of a tungsten carbide based cemented carbide (ISO PI0) having the shape of CNMG120408, MT-
A TiCN film was formed by the CVD method. The TiCN film is formed under the following conditions: TiCl ₄ : 2%, CH ₃ CN 1%,
H ₂ : 90%, Ar: balance (both are flow rate molar ratio), total flow rate 20 liter / min, substrate temperature 900 ° C., reactor pressure 7
It was set to 2 Torr. The thickness of the TiCN film was changed by adjusting the film formation time. Further, a TiBN film and an Al ₂ O film are formed on the second layer TiCN film by a known thermal CVD method.
_Three films were laminated in this order to obtain the coated cutting tool of the present invention. Table 1 shows the results obtained by measuring the thickness, average crystal grain size, hardness, and presence / absence of the interfacial corrosion layer of the obtained TiCN film. The average grain size is measured by polishing the growth surface of the film to remove the Al ₂ O ₃ film and the TiBN film on the surface and smoothing it, and then etching using a mixed solution of hydrofluoric acid, nitric acid and distilled water. Then, a grain boundary of the TiCN film was exposed, and this was observed using a scanning electron microscope, and measured by the method described in the paragraph (0012). The hardness of the TiCN film was measured by polishing the growth surface of the film to make it smooth, and using a Knoop hardness tester (load: 25 g,
Load time: 20 seconds). The unit of hardness is kgf
/ Mm ² . For comparison, when TiN is not used as a base material (Comparative Example 1) and when Ar (Ar) is not used, M
The case of the TiCN film by the T-CVD method (Comparative Example 2) is also described. As in the case of the coated cutting tool of the present invention, both are manufactured by a known thermal CVD method to form a TiBN film and Al ₂ O ₃
The film was laminated in this order. In addition, the obtained TiC _x N
The composition x of the _1-x film is about 0.6 in all cases.
It was confirmed by the line photoelectron spectroscopy (XPS) method and the X-ray diffraction method.

[0020]

[Table 1]

From Table 1, it can be seen that in Comparative Example 1 in which there is no underlying TiN film, a corrosion layer is formed at the interface between the base material and the film. Further, it can be seen that the TiCN film of Comparative Example 2 formed by the MT-CVD method without adding argon has a large average crystal grain size and a high hardness. Inventive products 1 to 1 in Table 1
5, the growth behavior of columnar crystals is changed by the addition of argon to the source gas of MT-CVD, the increase of the average crystal grain size due to the growth of the film is suppressed, or the TiC
The cause of the decrease in the hardness of the N film is not clear. Although not described in detail here, a similar phenomenon is caused by TiCN by MT-CVD in which nitrogen gas is added instead of argon.
It has been confirmed by the present inventors that this is also seen in film formation.

Next, among the samples shown in Table 1, the samples of the present invention product 3 having a similar film thickness, the samples of Comparative Examples 1 and 2 were subjected to a cutting test under the conditions shown in Table 2. The results are shown in Table 3.
Shown in. In this test, the wear resistance of the TiCN film, the adhesion between the inner layer (the TiN film in contact with the base material and the TiCN film on the base material) and the base material, and the fracture resistance of the coating were evaluated.

[0023]

[Table 2]

[0024]

[Table 3]

As can be seen from Table 3, the product of the present invention is excellent in abrasion resistance and at the same time excellent in peeling resistance and chipping resistance. On the other hand, in the case where there is no underlying TiN film (Comparative Example 1), the peeling resistance of the film is inferior, but this is presumably because a corrosion layer is seen at the interface of the base material and the peeling resistance of the film is poor. Next, when the average crystal grain size of the TiCN film was large (Comparative Example 2), the TiCN film of the type 3 described above was obtained, which showed good wear resistance and peeling resistance. It was found that the parts were chipped, abnormal wear was likely to occur, and the life varied.

<Example 2> (Structure of the entire coating layer) A cemented carbide having a shape of CNMG120408 (with a chip breaker) of ISO P30 was used as a base material, and a coating layer having the structure shown in Table 4 was formed on this surface. . Here, the formation of the first layer TiN film and the second layer TiCN film in the product of the present invention was carried out under the film forming conditions of the product of the present invention described in Example 1. In Comparative Example 3, as in Comparative Example 1 of Example 1,
A TiCN film was formed directly on the base material without the TiN base. The formation of the TiCN film in Comparative Example 4 is similar to Comparative Example 2 in Example 1 except that argon is not added.
It was performed by the T-CVD method. Other films were formed by a conventional thermal CVD method to obtain samples having the film thickness and film structure shown in Table 4.

[0027]

[Table 4]

Table 6 shows the results of the cutting test conducted on the samples shown in Table 4 under the cutting conditions shown in Table 5. Table 6
It can be seen from the results that the products 6 to 12 of the present invention are excellent in both wear resistance and peeling resistance and have a stable life.
On the other hand, when the TiN film was not added as the underlying intermediate layer (Comparative Example 3), as confirmed in Example 1, a corrosion layer was formed on the surface of the base material and the peeling resistance was poor. The result was obtained. Next, when the average grain size of the columnar crystals forming the TiCN film and the hardness of the coating did not correspond to the product of the present invention (Comparative Example 4), the coating was easily broken on a large scale during cutting, resulting in chipping. Both Comparative Examples 3 and 4 do not satisfy both wear resistance and peeling resistance, and it is understood that the performance as a cutting tool is poor.

[0029]

[Table 5]

[0030]

[Table 6]

<Embodiment 3> CNMG1 of ISO P01
A titanium carbonitride-based cermet having a shape of 20408 was used as a base material, and a coating layer having a structure shown in Table 7 was formed on this surface. Here, the first layer TiN film and the second layer in the product of the present invention
The TiCN film was formed under the film forming conditions of the product of the present invention described in Example 1. In Comparative Example 5, as in Comparative Example 1 of Example 1, T was directly applied onto the base material without adding TiN as the base.
The iCN film was formed. In addition, TiC in Comparative Example 6
The N film was formed by the MT-CVD method without adding argon, as in Comparative Example 2 of Example 1. Other films were formed by the conventional thermal CVD method to obtain samples having the film thickness and film structure shown in Table 7.

[0032]

[Table 7]

Table 9 shows the results of a cutting test conducted on the samples shown in Table 7 under the cutting conditions shown in Table 8. Table 9
From the results, it is understood that the products 13 to 16 of the present invention have excellent wear resistance and peeling resistance, and have a stable life. On the other hand, when the TiN film was not added as the base intermediate layer (Comparative Example 5), as confirmed in Example 1, the corrosion layer was formed on the surface of the base material, and the peeling resistance was poor. The result was obtained. Next, when the average grain size of the columnar crystals constituting the TiCN film and the hardness of the coating did not correspond to the product of the present invention (Comparative Example 6), the coating was liable to be destroyed on a large scale during cutting, resulting in chipping. Neither of these Comparative Examples 5 and 6 satisfied both wear resistance and peel resistance,
It can be seen that the performance is poor as a cutting tool.

[0034]

[Table 8]

[0035]

[Table 9]

[0036]

As described above, the coated cutting tool of the present invention has not only high wear resistance of the entire coating layer but also close adhesion between the coating film and the base material as compared with the conventional coated cutting tool. It has strong properties and has excellent resistance to peeling during cutting. Further, in the film structure which has been conventionally proposed, TiCN formed by the MT-CVD method is used.
While it was difficult to bring out the characteristics of the film, by inserting the underlying intermediate layer TiN with a specific thickness and forming a TiCN film having a specific structure by the MT-CVD method, It has become possible to stabilize the performance of the coated cutting tool.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C23C 16/40

Claims (3)

[Claims] 1. One or more hard components selected from the group consisting of carbides, nitrides and carbonitrides of IVa, Va or VIa group elements in the Periodic Table of Elements as main components and V.
In a coated cutting tool having a hard coating formed on a surface of a base material, which is an alloy composed of a group III metal component, by a chemical vapor deposition method, an inner layer is formed on the surface of the base material, and a first layer in contact with the base material is titanium nitride. And the second layer on it has a hardness of 1600
It is a titanium carbonitride of 2400 kg / mm ² , and is composed of multiple layers further coated with one or more selected from the group consisting of titanium carbides, nitrides, carbonitrides and boronitrides, and the outer layer is A coating comprising a coating layer composed of one or more single layers or multiple layers selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide, titanium carbide, titanium carbonitride and titanium nitride. Cutting tools. 2. One or more hard components selected from the group consisting of carbides, nitrides and carbonitrides of IVa, Va or VIa group elements in the Periodic Table of Elements as main components and V.
A coated cutting tool having a hard coating formed on a surface of a base material, which is an alloy composed of a group III metal component, by a chemical vapor deposition method, and has a thickness of 0.1 to 2 as a first layer in contact with the base material on the surface of the base material. 0.0 μm of titanium nitride is coated, and titanium carbonitride having a hardness of 1600 to 2400 kg / mm ² is coated thereon as the second layer, and titanium carbide, nitride, carbonitride and titanium carbide are further coated thereon. A single layer or multiple layers consisting of one or more selected from the group consisting of boronitrides, and an outer layer on these inner layers, selected from the group consisting of aluminum oxide, titanium carbide, titanium carbonitride and titanium nitride. A coated cutting tool, which is obtained by coating the above-mentioned coating layer composed of a single layer or multiple layers. 3. The titanium carbonitride of the second layer is composed of columnar crystal grains, and the average crystal grain size of the titanium carbonitride is 0.1 to 1 μm when the thickness of the second layer is 4.0 μm or less. It is a range, and when the film thickness of the second layer exceeds 4.0 μm and is 20 μm or less, it is in the range of 0.5 to 3.0 μm, and the coated cutting tool according to claim 1 or 2.