JP2000024808A - Covered cemented carbide cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the abrasion resistance of a cover layer and prevent the occurrence of damage and peeling by forming an outer layer with κ-type aluminum oxide, and providing a region where grains having the α-type crystal structure and grains having the κ-type crystal structure are mixed directly above an inner layer. SOLUTION: Cemented carbide is used as a base material, an inner layer and an outer layer are provided on the surface, and the inner layer is formed with two layers or more of Ti(CwBxNyOz), where w+x+y+z=1 and w, x, y, z>=0. The mixing ratio of α-type aluminum oxide grains and κ-type aluminum grains directly above the inner layer is preferably set to κ/α=1 to 4 to obtain the κ-type aluminum oxide layer on the outer layer. When the κ/α ratio is kept in this range, high degree of adhesion and the formation of the final κ-type crystal structure aluminum oxide layer can be easily reconciled. The mixed state of κ/αexists not only in the first line, and the κ/α ratio is decreased toward the upper layer and becomes zero in the film.

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 cutting tool which is tough and has excellent wear resistance.

[0002]

2. Description of the Related Art Titanium carbide,
The life of cutting tools is improved by depositing a coating layer such as titanium nitride, titanium carbonitride or aluminum oxide, and is generally produced using a chemical vapor deposition method, a plasma CVD method, a physical vapor deposition method, or the like. Coating layers and the like are widely used.

However, when machining is performed using these coated cutting tools, the wear resistance and crater resistance of the coating layer at high temperatures are required, especially in high-speed cutting of steel and high-speed processing of cast iron. Tool life due to insufficient wear resistance of the coating layer, damage or peeling of the coating layer due to the large number of processing such as the processing of small parts or the processing of a large number of bites on the work material such as the processing of small parts Had been reduced.

As a method of overcoming these problems, as a structure having a multilayer coating layer, the inner layer is made of titanium carbide or titanium carbonitride having high hardness and excellent hardness with a cemented carbide, and the outer layer is made of aluminum oxide. In the structure used, control of the structure and orientation of the coating layer has been studied. For example, Japanese Patent Publication No. Hei 9-507528 discloses that high-temperature-stable aluminum oxide having an α-type crystal structure is formed with a certain orientation in order to improve high-temperature characteristics. Conventionally, aluminum oxide having an α-type crystal structure has been
Because of its excellent high-temperature properties, it is effective in cutting where the temperature of the tool edge is extremely high, such as ultra-high-speed cutting of steel and high-speed cutting of difficult-to-cut materials. However, under the cutting conditions in which aluminum oxide-coated cemented carbide is widely used for general purposes such as high-speed cutting of steel, the adverse effects of coarse crystal grains and low strength become apparent, and At present, it cannot be said that performance has been obtained. For this reason, aluminum oxide having a κ-type crystal structure, which has a finer crystal grain size, higher strength, and relatively good adhesion to the substrate as compared with α-type aluminum oxide, has been widely used. At present, the peeling resistance is not sufficient.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a high level of film quality such as abrasion resistance, crater resistance and film strength of a fine aluminum film having a κ-type crystal structure as compared with a conventional coated cutting tool. An object of the present invention is to stably and dramatically improve the life of a tool by greatly improving the peel resistance of a coating layer during cutting while maintaining the same.

[0006]

To this end, the present invention has the following structure. IV mainly containing tungsten carbide
a, Va, a cemented carbide consisting of a hard phase containing at least one of carbides, nitrides and carbonitrides of Group VIa metals and a binder phase mainly composed of Co as a base material, and having an inner layer and an outer layer on its surface A ceramic coating layer, wherein the inner layer is Ti (C
wBxNyOz) (where w + x + y + z = 1, w, x,
y, z ≧ 0), the outer layer has an aluminum oxide layer at a position in contact with the inner layer, and the aluminum oxide layer is substantially composed of κ-type aluminum oxide. There is a region in which particles having an α-type crystal structure and particles having a κ-type crystal structure coexist immediately above and in contact with, and the α-type aluminum oxide crystal grains in this region have substantially no pores.

Ti (CwBxNyOz) (here, w +
x + y + z = 1, w, x, y, z ≧ 0). In addition, by mixing particles having an α-type crystal structure and particles having a κ-type crystal structure immediately above the inner layer, unprecedented high peeling performance can be obtained. Conventionally, it is known that if the crystal of aluminum oxide at the interface with the base is made only of α-type or a mixture of α-type and κ-type, the α-particles in this part contain many pores. The aluminum oxide film peeled off due to the destruction → film peeling mechanism caused by the decrease in film strength due to pores near the interface.

According to the present invention, the α-type and κ-type aluminum oxide layers are formed while suppressing a decrease in adhesion strength by adopting a structure substantially free of pores in the crystal grains of the α-type aluminum oxide in this region. Is mixed, so that the strength of the aluminum oxide layer near the interface can be greatly improved. The first column on the interface with the underlayer has a structure in which α-type and κ-type aluminum oxide layers are mixed at a certain ratio, and α
Oxidation of the κ-type crystal structure, which has excellent mechanical and chemical wear resistance and film destruction characteristics in a cutting environment, because the layer of the aluminum oxide of the type structure is removed by the layer of aluminum oxide of the κ-type structure. Finally, a layer of aluminum can be grown.

As described above, a κ-type aluminum oxide layer having excellent film quality can be formed on the inner layer with a very high degree of adhesion by the present structure, and the cutting performance can be drastically improved. Becomes

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses a cemented carbide as a base material,
The structure has an inner layer and an outer layer on its surface, and FIG. 1 shows this structure. The inner layer is Ti (CwBxNyOz)
(Here, w + x + y + z = 1, w, x, y, z ≧ 0), characterized by being essentially and mainly composed of a titanium carbonitride layer having a columnar structure, so that intermittent cutting can be performed. In addition to preventing damage from the outer aluminum oxide layer during cutting of parts processing, etc., it also obtains extremely high wear resistance while preventing the destruction of the film in the inner layer and the peeling of the film between the base material and the inner layer And tool performance can be dramatically improved.

Further, in order to obtain a κ-type aluminum oxide layer in the outer layer, the mixing ratio of α-type aluminum oxide particles and κ-type aluminum particles immediately above the inner layer is κ /
It is desirable that α = 1 to 4. By maintaining the κ / α ratio in this range, it becomes easier to achieve both high adhesion and the final formation of the κ-type crystal structure aluminum oxide layer. It is more preferable that the mixed state of κ / α is not only in the first row, but that the ratio decreases toward the upper layer and becomes zero in the film. This is because, when only the particles in the first row are mixed, there is a possibility that distortion due to a rapid change in the distribution of the crystal structure may have an effect of reducing the film strength in this portion. However, these mixed regions are more preferably within 1.5 μm from the interface with the inner layer. This is because when the mixed region exceeds this, the influence of the film quality deterioration due to the presence of the aluminum oxide layer having the α-type crystal structure starts to appear.

In the structure of the present invention, as the density of the initially formed nuclei of the aluminum oxide layer on the inner layer increases, the effect of improving the adhesion strength tends to increase. At this time, α
This effect is remarkably obtained when most of the particles immediately above the inner layer in which the mixed type aluminum oxide and the κ-type aluminum oxide are in contact with each other have a nucleation density at a level of a particle size of 200 nm or less. Here, the particle size is 100,
Using a 000-fold cross-sectional photograph, at an arbitrary length of 1 μm, it was determined by dividing the number by the number of particles arranged in the first layer (1 / number of particles).

In the structure of the present invention, the thickness of the aluminum oxide layer is more preferably 1 to 20 μm. If the thickness is less than 1 μm, there may be a case where the effect of κ alumina having excellent film quality cannot be sufficiently exerted. Conversely, if the film thickness exceeds 20 μm, the strength will be insufficient even with high-strength κ-alumina, and the film will break during cutting, or the wear resistance of the film will decrease due to the coarsening of the crystal grains due to the thickening. This is because a case may occur.

[0014] The fact that the crystal structure of the aluminum oxide layer finally formed is all κ-type means that X
The analysis was performed by means of line diffraction, and it was confirmed that all the diffraction peaks consisted of aluminum oxide having a κ-type structure and did not include an α-type structure. In addition, α-type and κ at the beginning of aluminum oxide film formation
The evaluation of the shaped particles is performed by analyzing an electron beam diffraction pattern by TEM with respect to 10 or more arbitrary particles in the first row immediately above the interface with the inner layer. Using the same method for the second and subsequent columns, analysis is performed until the column where α-type is no longer detected, and after that, all κ-type crystal structures are taken into account by taking into account that all are κ-type by X-ray diffraction from the surface. Judge to have. The presence or absence of pores in the aluminum oxide layer at the beginning of film formation
Judgment is made from a 100,000-fold cross-sectional photograph by TEM.

Further, the structure of the uppermost film of the inner layer in contact with the outer aluminum oxide layer is more preferably formed of a fine needle-like structure having a thickness of 200 nm or less. Thus, the first particles of the aluminum oxide immediately above are likely to be fine and uniform, and a decrease in film strength due to coarsening of the aluminum oxide particles after film formation can be prevented.

The film composition of this layer is Ti (CwBxN
yOz) (where w + x + y + z = 1, x ≧ 0.05). This is because the inclusion of B makes it possible to suppress the oxidation of the inner layer surface at the initial stage of aluminum oxide film formation, and it is easy to obtain higher adhesion of aluminum oxide. In the structure of the present invention, it is more preferable that the orientation of the aluminum oxide layer having the κ-type crystal structure is the strongest when the X-ray diffraction intensity at a plane spacing of 2.79 angstroms is 2θ = 20 to 80 °.

By adopting the structure of the present invention, both the strength and hardness of the film can be further improved, and the tool life can be improved by improving the wear resistance and chipping resistance of the film. Become.

Further, the orientation index TC of the columnar structure titanium carbonitride layer which is an essential component of the inner layer is TC (31
1) is the largest and the value is 1.3 or more and 3 or less, or the orientation index TC (4) of the (422) plane and the (311) plane.
22) and TC (311) are both preferably 1.3 or more and 3 or less.

[0019]

(Equation 2)

By setting the orientation index within the range of the present invention, it is possible to greatly improve the breaking resistance of the inner layer film, and it is possible to prevent fine chipping of the film. As a result, the abrasion resistance is greatly improved. However, if the orientation index exceeds 3, the orientation in one direction becomes too strong, and conversely, the destructibility of the film decreases. The combination of the film quality and the film structure of the inner layer and the outer layer described above makes it possible to further improve the tool life by synergistic effects of the above-described effects.

Hereinafter, a method for manufacturing the structure of the present invention will be described. First, the titanium carbonitride of the present invention has a coating atmosphere of Ti
Cl ₄ , CH ₃ CN, N ₂ and H ₂ are used, and the film is formed by changing the first and second half conditions as follows. That is, the ratio of (TiCl ₄ + CH ₃ CN) / total gas amount during the 120 minutes from the beginning of film formation is made smaller than that in the latter half, and the ratio of N ₂ / total gas amount in the first half is twice that in the latter half. With the above, the present structure is obtained. At this time, the orientation index of TC (311) can be set to 1.3 or more and 3 or less by setting the layer thickness of titanium carbonitride to less than 10 μm, and TC (311) by setting the film thickness to 10 μm or more. Both TC (422) can be 1.3 or more and 3 or less.

Next, the aluminum oxide of the present invention is
It is manufactured by a normal CVD process using ₃ and CO ₂ and H ₂ as source gases. Α-type structure and κ in the early stage of aluminum oxide
A specific manufacturing method of the mixed region of the mold structure is based on the following method. First, after covering up to the inner layer just below the aluminum oxide layer,
After cleaning the inside of the coating furnace in H ₂ atmosphere,
CO ₂ and AlCl ₃ are introduced at the same time.
1 minute later than Cl _{3 and} less amount of C than steady state
O ₂ is introduced, and the amount of CO ₂ is increased until a steady film formation condition is reached. That is, it can be manufactured by continuously or stepwise increasing the amount of initial CO ₂ / the amount of CO ₂ at steady state from 0.1 to 0.5 → 1 over 10 minutes. The temperature at this time is 930 ° C. to 1000 ° C. Thereby, irrespective of the aluminum oxide film formation temperature, α
It is possible to form a κ-type aluminum oxide film having a mixed region of a κ-type and a κ-type. By setting these initial conditions, the mixture ratio and thickness of α-type and κ-type of the initial layer can be adjusted, whereby the orientation of the finally formed aluminum oxide layer can be controlled. It is also possible to change the orientation by changing the film thickness of aluminum oxide under the same oxidation conditions.

If the above-mentioned method for producing an interface phase is not used, or if the conditions are insufficiently set even if it is used, the initial α
A mixed region of mold type and κ type cannot be obtained, or even if it is obtained, an α-type aluminum oxide film is finally formed, and even if a mixed region is obtained, α
Many pores are contained in the aluminum oxide particles having the type crystal structure, and none of them can exhibit the effects of the present invention.

After coating, the surface of the coating layer is subjected to mechanical processing such as blasting or brushing so that the aluminum oxide layer is formed at the center of the flank only at the cutting edge ridge formed by the intersection of the flank and the rake face. By treating the surface until it is smoothed, thinned or removed compared to a flat part, the above-mentioned effect is greater. Here, the surface roughness of the aluminum oxide layer is more effective when Rmax ≦ 0.4 μm as measured over a length of 10 μm at the ridge of the cutting edge. It is preferable that the uppermost layer is an aluminum oxide layer only with the cutting edge, and the outermost layer of the other flat portion is made of TiN. Depending on the cutting conditions, damage due to welding of the work material at a position other than the cutting edge occurs, but the damage is suppressed by the effect of TiN having excellent welding resistance.

The degree of treatment at this time is required to ensure that the alumina layer is smoothly smoothed, thinned or removed at the cutting edge portion of the cutting edge ridge line where the cutting powder actually contacts during cutting. However, depending on the degree of treatment, there is no problem even if the alumina layer is not partially thinned or removed at the ridge portion at a position away from the cutting edge, and the effects of the present invention can be obtained. Further, in the present invention, the alumina layer is smoothed, thinned or removed only at the cutting edge ridge portion. However, depending on the processing method, the alumina layer may be processed even at an angular place not related to cutting, such as around the seating surface of the chip. However, this does not substantially affect the effects of the present invention.

Further, by such a film surface treatment, the tensile residual stress existing in the coating layer after coating is reduced by the TiC of the inner layer.
By reducing it to 10 kg / mm ² or less in the N layer, it is possible to improve the effect on the breakdown resistance of the film.

[0027] Further, the surface of the cemented carbide substrate has a layer in which a hard phase other than tungsten carbide is reduced or disappears,
By combining the coating layer and the surface treatment of the present invention with a toughened superalloy having a surface layer portion having a thickness of 10 μm or more and 50 μm or less in a flat portion, the coating layer falls off along with the surface layer of the cemented carbide portion. Very effective against damage. In particular, Zr is contained in the cemented carbide substrate, and not all are in solid solution in the binder phase, but at least a part thereof constitutes a hard phase component. The strength characteristics can be improved, which is more preferable.

Further, in this structure, by providing a region in which the hardness of the surface layer is lower than the average hardness of the inside of the base material and higher than that of the inside immediately below, the toughness can be increased by the effect of the surface layer, And the effect of improving the plastic deformation resistance by the high hardness region becomes more remarkable. Here, the thickness of the substrate surface layer region was set to 10 μm or more and 50 μm or less because 5
If it exceeds 0 μm, a slight plastic deformation or elastic deformation tends to occur in the surface layer during cutting, and if it is less than 10 μm, the effect of improving toughness is small. Also,
The surface layer is formed by a method using a nitrogen-containing hard phase material as conventionally known, or a nitriding atmosphere during a heating process during sintering, and a denitrification or decarburization atmosphere after the appearance of a liquid phase of a binder phase. And can be manufactured.

[0029]

EXAMPLES (Example 1) WC-9% Co-4 as base material
% TiC-2% TaC-1% NbC
A WC-based cemented carbide substrate having a shape of 20408 was prepared. Four types of inner layer structures shown in Table 1 were used on the surface of the substrate, and outer layers shown in Table 2 were successively laminated thereon. The initial conditions of the aluminum oxide film formation at this time are as follows:
To E (F and G are comparative examples). Table 4 shows samples prepared by combining these aluminum oxides A to E of the present invention (Tables 1 to 3).
Symbol). One minute after the introduction of AlCl ₃ , CO ₂ was introduced in a smaller amount than the steady state, and brought to a steady amount over 10 minutes. On the other hand, under the comparative products, AlCl ₃ , C
O ₂ was added at the same time, and the amount of CO ₂ was constant from the beginning. In Comparative product G, C was added 10 minutes after AlCl _{3 was} introduced.
O ₂ was constantly introduced from the beginning.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

The TiC used in the inner layer of the present invention shown in Table 1
The N layer was broken after coating, and the SEM (scanning electron microscope) observation of the fractured surface revealed that all of the N layers had a columnar structure. Further, the TiBN layer used as the uppermost layer of the inner layer was a layer having a uniform thickness, and its structure was a fine needle-like structure having a thickness of 200 nm or less. When this TiBN layer was analyzed using EDX, it was detected that it contained O (oxygen) although it was quantitatively unknown. Also, 3
Under the conditions of a, a sample in which only the inner layer was formed was prepared, and quantitative analysis was performed from the surface using ESCA.
Of B (boron).
Table 1 also shows the orientation index of the (311) plane and the (422) plane of the inner TiCN layer.

Here, the orientation index of the inner TiCN layer was determined from a diffraction peak by X-ray diffraction. At this time, T
The diffraction peak of the (311) plane of iCN is (1) of WC of the substrate.
11) Overlap with the plane peak, and the peak intensity of the (111) plane is (the intensity of the (101) plane which is the strongest peak of WC) × 0.25.
Therefore, this was subtracted from the intensity at the position (311) of TiCN, and the intensity corresponding to the WC (111) plane was subtracted.

A cross section near the interface between the inner layer and the aluminum oxide layer in contact with the inner layer was taken to be 100,000 by TEM.
In each sample, the orientation of aluminum oxide was evaluated by X-ray diffraction from the surface of the sample after film formation. As a result, in the product of the present invention in the table, 90% or more of the particles present in the first row have a granular structure with a particle size of 200 nm or less, and the α-type crystal particles existing in this region have pores. , And finally, the upper layer had a κ-type crystal structure (X-ray diffraction evaluation from the surface did not detect α-type). On the other hand, in the comparative product F, although the mixed region exists, the α-type particles present in the mixed region of the first example have many pores, and finally have the α-type crystal structure. . In the comparative product F, the crystal grain size in the first row was coarse as a whole, and most of the grains had a grain size of 300 nm or more. Comparative product G finally had a κ-type crystal structure, but did not have an initial mixed region of κ-type and α-type. Regarding the orientation of aluminum oxide, the diffraction intensity of the surface of 2.57 angstroms was the strongest in sample No. 6 of the product of the present invention in which the ratio of κ type and α type was low in the initial stage. In Nos. 1 to 9, the diffraction intensity of the 2.79 Å plane was the strongest. The coating conditions used for forming each layer are shown below.

TiN layer Temperature: 920 ° C., Pressure: 360 torr, Reaction gas composition: 48% H ₂ -2% TiCl ₄ -50 in volume%
% N ₂ TiCN layer of present invention products 1 to 3 TiCN layer (first half 120 minutes) Temperature: 920 ° C., 50 torr, Reaction gas composition: 66.5% H _{2 in} volume%, 3.0% TiCl
_{4 -0.5% CH 3 CN-30} % N 2 TiCN layer (second half left) Temperature: 920 ° C., 50 torr, the reaction gas composition: by _{volume%, 78% H 2 -6%} TiCl 4 -1% CH
₃ CN-15% N ₂ TiC layer 1020 ° C., pressure 50 torr, reaction gas composition: 96.5% H ₂ -2% TiCl ₄ − in volume%
1.5% CH ₄ TiBN layer Temperature: 950 ° C., pressure: 360 torr, reaction gas composition: 46% H ₂ -4% TiCl ₄ -48 by volume%
% N ₂ -2% BCl ₃ Al ₂ O ₃ layer Temperature 930 ° C. (Al ₂ O ₃ -A), 1000 ° C. (Al ₂ O ₃
-B), pressure: 50 torr Reaction gas composition: 93% H ₂ -5% AlCl ₃ -2% C by volume%
O ₂

Using the above samples, performance evaluation was performed under the following cutting conditions 1 and 2. Cutting conditions 1 Work material: SCM415 (HB = 170) 4-groove material Cutting speed: 230 m / min Feed: 0.30 mm / rev Cutting depth: 1.5 mm Number of impacts: 100 Cutting oil: Water solubility Evaluation results are shown in Table 5. Show.

[0039]

[Table 5]

Cutting conditions 2 Work material: FC25 Cutting speed: 180 m / min Feeding: 0.25 mm / rev Cutting depth: 1.5 mm Cutting time: 30 minutes Cutting oil: Water solubility Evaluation results are shown in Table 6.

[0041]

[Table 6]

From these results, it can be seen that the product of the present invention is superior to the conventional product in all of the abrasion resistance, peeling resistance, chipping resistance and crater resistance of the film. Observation of the samples after these cutting evaluations revealed that the amount of deposited work material on the rake face was larger in the samples with the outermost surface coated with TiN than in the samples with exposed alumina. Was kept low. In the range of this evaluation, the quality of the film on the outermost surface did not directly affect the amount of wear and the like, but it is considered that the raked surface has an effect on the damage on the rake face.

Example 2 Using samples 3, 4, and 6 produced in Example 1, after coating, the film surface was treated with a nylon brush containing SiC. Samples with different treatment levels were produced by changing the surface treatment time. Processing time 1
Minutes, 6 minutes, and 12 minutes, H1, H6, and H12
Indicated by Table 7 shows the ratio of the thickness of the alumina at the cutting edge to the thickness of the alumina at the flat portion, the film surface roughness at the cutting edge, and the tensile residual stress at the ridge of the cutting edge of each sample.

[0044]

[Table 7]

The tensile residual stress is a result of measuring the residual stress of the inner TiCN layer by a sin2ψ method using an X-fracture apparatus. Tables 8 and 9 show the results of performing the same cutting evaluation as in Example 1 using these samples.

[0046]

[Table 8]

[0047]

[Table 9]

From these results, it can be seen that by performing these surface treatments, the film strength is improved, and damage due to the film performance is further suppressed. In each of the samples 3 and 6, which were subjected to the surface treatment, TiN on the outermost surface remained in the flat portion, and this was removed in the cutting edge portion. From the results, it can be seen from the results in the table that the effect of improving the abrasion resistance of the sample subjected to the surface treatment was confirmed by this effect. Not only this, but also the welding amount of the work material on the rake face was flat. It was also confirmed that the alumina was kept smaller than that of the sample in which the portion was exposed.

Example 3 Sample 6 used in Example 1
(The used base material is X), and only the base material is Y: WC
-9% Co-2% ZrC-2% TiC-2% TaC-1
% NbC, Z: a sample was changed to WC-9% Co-7% ZrN. Here, P between 1200 and 1400 ° C.
Samples X1, Y1, and Z1 were prepared by sintering at 1450 ° C. and a vacuum of 10 ⁻² torr for 1 hour in a nitrogen atmosphere of N ₂ = 50 torr.
Here, in samples Y, Y1, Z, and Z1, it was confirmed by EPMA surface analysis that Zr constituted a hard phase component. Table 10 shows the thickness (P) of the layer in which the hard phase excluding tungsten carbide disappeared on the surface of each sample,
The difference (Q) between the hardness and the internal hardness of the surface layer portion of the base material and the difference (R) between the internal hardness and the high hardness portion immediately below the surface layer portion are shown. here,
The hardness was measured using a micro Vickers hardness tester under a load of 500 g.

[0050]

[Table 10]

Using these samples, evaluation of fracture resistance under the following cutting conditions 3 and evaluation of plastic deformation resistance under the cutting conditions 4 were performed. Table 11 shows the results. here,
Under the cutting condition 3, the average of 12 corners was used to determine the defect rate. Cutting conditions 3 Work material: SCM435 (HB = 230) 4-groove material Cutting speed: 100 m / min Feed: 0.15 to 0.30 mm / rev Cutting depth: 2.0 mm Time: MAX 30 sec Number of corners: 12 corners Cutting oil: None

Cutting condition 4 Work material; SK5 Cutting speed; 100 m / min Feed; 0.65 mm / rev Depth; 1.5 mm Cutting time; 3 minutes Cutting oil; None

[0053]

[Table 11]

Although this is not shown, an evaluation was made on each of the samples on which the H12 surface treatment shown in Example 2 was performed. As a result, the plastic deformation resistance hardly changed. It was also confirmed that the defect rate of the sample was improved to 以下 or less. Further, even if the composition of the base material was changed to Y or Z, the results of the cutting conditions 1 and 2 shown in Example 1 did not change at all (these evaluations depended only on the film quality). confirmed.

[0055]

When cutting is performed using the coated cemented carbide cutting tool of the present invention, the wear resistance of the coating layer at a high temperature, such as high-speed cutting of steel or machining of cast iron at high speed, is particularly high. By improving the abrasion resistance of the coating layer and preventing damage and delamination in processing requiring crater resistance or processing with a large number of processing such as small parts processing and a large number of bites on the work material This has the effect of significantly improving tool life.

[Brief description of the drawings]

FIG. 1 is a view showing the structure of a coated cemented carbide cutting tool of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23C 28/04 C23C 28/04 // C23C 14/08 14/08 NF term (Reference) 3C046 FF03 FF10 FF13 FF16 FF25 FF27 FF32. BA02 BA10 BA11 BA12 BA18 BB02 BB03 BB04 BC01 CA13 CA14

Claims (19)

[Claims] 1. The method according to claim 1, wherein the main component is tungsten carbide.
a, Va, a cemented carbide consisting of a hard phase containing at least one of carbides, nitrides and carbonitrides of Group VIa metals and a binder phase mainly composed of Co as a base material, and having an inner layer and an outer layer on its surface A ceramic coating layer, wherein the inner layer is Ti (C
wBxNyOz) (where w + x + y + z = 1, w, x,
y, z ≧ 0), the outer layer has an aluminum oxide layer at a position in contact with the inner layer, and the aluminum oxide layer is substantially made of κ-type aluminum oxide and is in contact with the inner layer There is a region in which particles having an α-type crystal structure and particles having a κ-type crystal structure are present directly above, and substantially no pores are contained in the α-type aluminum oxide crystal grains in this region. Coated cemented carbide cutting tool. 2. A position where the outer layer is not in contact with the inner layer,
Ti (CwBxNyOz) (where w + x + y + z = 1,
2. The coated cemented carbide cutting tool according to claim 1, wherein at least one of w, x, y, and z ≧ 0). 3. The coated cemented carbide cutting tool according to claim 1, wherein said inner layer mainly comprises a titanium carbonitride layer having two or more layers and having a columnar structure. 4. The coated cemented carbide cutting tool according to claim 1, wherein the mixture ratio of the α-type aluminum oxide particles and the κ-type aluminum particles is κ / α = 1 to 4. 5. A region in which α-type aluminum oxide and κ-type aluminum oxide are mixed is 1.5 μm from an interface with an inner layer.
The coated cemented carbide cutting tool according to claim 1, wherein the distance is within m. 6. The method according to claim 1, wherein most of the particles immediately above the inner layer in which the α-type aluminum oxide and the κ-type aluminum oxide are mixed have a granular structure having a particle size of 200 nm or less. Coated cemented carbide cutting tool. 7. The aluminum oxide layer has a thickness of 1-2.
The coated cemented carbide cutting tool according to claim 1, wherein the thickness is 0 µm. 8. The coated cemented carbide cutting tool according to claim 1, wherein the inner layer film in contact with the aluminum oxide layer has a needle-like structure having a thickness of 200 nm or less. 9. The film of the inner layer is made of Ti (CwBxNyOz).
(Where w + x + y + z = 1, w, y, z ≧ 0, x ≧
The coated cemented carbide cutting tool according to claim 8, wherein the cutting tool comprises 0.05). 10. The orientation of the κ-type aluminum oxide is such that the X-ray diffraction intensity at an interplanar spacing of 2.79 angstroms is 2θ.
2. The coated cemented carbide cutting tool according to claim 1, wherein the strength is the strongest between 20 ° and 80 °. 11. The orientation index TC of the titanium carbonitride layer having a columnar structure of the inner layer is the largest at TC (311), and the value is 1.3 or more and 3 or less.
2. A coated cemented carbide cutting tool according to item 1. (Equation 1) 12. The method according to claim 1, wherein the orientation index TC is TC (422).
Indices TC (422), TC
The coated cemented carbide cutting tool according to claim 11, wherein (311) is both 1.3 or more and 3 or less. 13. The coated cemented carbide cutting tool according to claim 1, wherein the thickness of the aluminum oxide layer near the cutting edge ridge is thinner or nonexistent as compared with the flat part. 14. The surface roughness of the coating layer in the vicinity of the cutting edge ridge portion is Rm over a width of 10 μm from the cutting edge ridge portion.
14. The coated cemented carbide cutting tool according to claim 1, wherein ax ≦ 0.4 μm. 15. The coating according to claim 14, wherein an uppermost layer of said cutting edge ridge portion is an aluminum oxide layer or said inner layer film, and an outermost layer of another flat portion is made of TiN. Cemented carbide cutting tool. 16. At least at the cutting edge ridge portion,
Tensile residual stress of the inner layer titanium carbonitride is 10 kg / m
The coated cemented carbide cutting tool according to claim 15, wherein m is ² or less. 17. A layer in which a hard phase other than tungsten carbide is reduced or disappears in a surface layer portion of the cemented carbide substrate,
The coated cemented carbide cutting tool according to claim 1, wherein the thickness of the flat portion is 10 µm or more and 50 µm or less. 18. The hardness of a surface layer portion of the cemented carbide substrate,
2. A region having a lower hardness than the average hardness of the inside of the substrate and a hardness higher than the inside immediately below the average hardness.
7. The coated cemented carbide cutting tool according to 7. 19. The coated cemented carbide cutting tool according to claim 1, wherein the cemented carbide substrate contains Zr, at least a part of which constitutes a hard phase component.