JP7021607B2 - Surface-coated cutting tools with excellent chipping resistance and chipping resistance due to the hard coating layer - Google Patents

Description

The present invention is a high-speed intermittent cutting process in which a shocking load acts on the cutting edge while generating high heat of alloy steel or the like, and the hard coating layer has excellent chipping resistance and wear resistance. It relates to a surface-coated cutting tool (hereinafter, may be referred to as a coated tool) that exhibits excellent cutting performance over a long period of use.

Conventionally, it is generally composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide, a titanium carbonitride (hereinafter referred to as TiCN) -based cermet or a cubic boron nitride (hereinafter referred to as cBN) -based ultrahigh-pressure sintered body. As a hard coating layer, there is a coating tool in which a Ti-Al-based composite nitride layer is coated and formed by the PVD method or the CVD method on the surface of the tool substrate (hereinafter, these are collectively referred to as a tool substrate). Is known to exhibit excellent wear resistance.
However, although the conventional coated tool coated with the Ti-Al-based composite nitride layer or composite carbonitride layer has relatively excellent wear resistance, abnormalities such as chipping when used under high-speed intermittent cutting conditions. Since wear is likely to occur, various proposals have been made for improving the hard coating layer.

For example, in Patent Document 1, the diffraction intensity of the (111) plane in the X-ray diffraction of the hard coating layer which is a composite nitride of Ti and Al is I (111), and the diffraction intensity of the (200) plane is I (200). The value of I (200) / I (111) is 2.0 or less, and a surface-coated end mill in which a composite nitrogen oxide of Ti and Al is further coated on the coating layer has been proposed.

Further, Patent Document 2 is coated with a hard film having a single-layer or multi-layer structure, and the layer structure is at least one Ti _1-x Al _x N hard film prepared by CVD without performing plasma excitation. The Ti _1-x Al _x N hard film has a cubic NaCl having a chemical quantitative coefficient of x> 0.75 to x = 0.93 and a lattice constant a _fcc of 0.412 nm to 0.405 nm. It exists as a single-phase layer of the structure, and the chloride content of the Ti _1-x Al _x N hard film is in the range of 0.05 to 0.9 atomic%, or the Ti _1-x Al _x The N-hard film has a cubic NaCl structure in which the main phase has a chemical quantitative coefficient of x> 0.75 to x = 0.93 and a lattice constant a _fcc of 0.412 nm to _0.405 nm. A multi-phase layer consisting of _x Al _x N and containing Ti _1-x Al _x N as another phase as a wurtzite structure and / or as TiN _x of a NaCl structure, and Ti _1-x . A cutting tool is described in which the chlorine content of the Al _x N hard film is in the range of 0.05 to 0.9 atomic%.

In addition, Patent Document 3 proposes a coated cutting tool in which the coating layer contains a refractory layer containing a plurality of subphase groups including aluminum oxynitride or composite aluminum oxynitride and alumina or composite alumina. ..

Japanese Unexamined Patent Publication No. 9-291353 Japanese Patent No. 4996602 Japanese Unexamined Patent Publication No. 2015-47690

In recent years, there has been a strong demand for labor saving and energy saving in cutting, and along with this, cutting tends to be faster and more efficient. Abnormal damage resistance such as peeling resistance is required, and excellent wear resistance is required over a long period of use.
However, the coated tools proposed in Patent Documents 1 to 3 are chipping-resistant and wear-resistant in high-speed intermittent cutting in which high heat is generated from alloy steel or the like and a shocking load is applied to the cutting edge. In some cases, the properties were not sufficient and it could not be said that the tool life was satisfactory.

Therefore, the present invention solves the above-mentioned problems and provides a covering tool that exhibits excellent chipping resistance and wear resistance over a long period of time even when it is used for high-speed intermittent cutting of alloy steel or the like. With the goal.

The present inventor has improved the chipping resistance and wear resistance of a coated tool provided with a hard coating layer including at least a composite carbonitride (sometimes referred to as "TiAlCN") layer of Ti and Al on a tool substrate. In order to achieve this, in particular, not only the surface of the TiAlCN layer but also the positive addition of a small amount of O in the thickness direction affects the improvement of chipping resistance and wear resistance.

That is, the TiAlCN film obtained by adding a small amount of C to the composite nitride (sometimes referred to as "TiAlN") film of Ti and Al is hard because it has lattice strain due to the addition of C as compared with the TiAlN film. However, when a small amount of O is positively added, the oxidation resistance of the TiAlCN film itself is improved, and the chipping resistance and wear resistance in high-speed intermittent cutting are further improved. (Hereinafter, the composite carbon dioxide oxide in which O is positively added to TiAlCN may be referred to as "TiAlCNO"), and further, it is represented by fine aluminum oxide (Al ₂ O ₃ ) in the TiAlCNO film. When Al oxides in the vicinity of the composition are scattered, the thermal stability of the TiAlCNO film is improved, the growth of cracks during cutting is suppressed, and the chipping resistance and chipping resistance are significantly improved. I got amazing findings.
In addition, in Patent Document 1, when oxygen is contained in the composite nitride and carbon nitride of the outermost layer Ti and Al, the coefficient of friction can be reduced and the tool life is improved by reducing the cutting heat. It is possible to improve the oxidation resistance by replacing one or more components of Hf, Y, Si, W, and Cr in the range of 0.05 to 60 at% with respect to Ti, respectively. Although it is described, the former does not mention the improvement of oxidation resistance, and even the guideline for the amount of oxygen contained is not disclosed, and the latter improves the oxidation resistance with respect to Ti. It is only stated that it is brought about by the replacement of Zr and the like, and in each case, the positive addition of a small amount of O causes the formation of TiAlCNO instead of the formation of an oxide only in the vicinity of the outer surface layer, which is acid resistant. It does not even suggest the above-mentioned findings that the chemical resistance is improved, and further, the chipping resistance and the chipping resistance are remarkably improved by the scattered fine particles of aluminum oxide.

The present invention has been made based on the above findings.
"(1) A surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool substrate composed of either a tungsten carbide-based cemented carbide, a titanium nitride-based cermet, or a cubic boron nitride-based ultrahigh-pressure sintered body. In
(A) The hard coating layer contains at least a composite carbon dioxide oxide layer of Ti and Al having an average layer thickness of 3.0 to 20.0 μm.
(B) The Ti and Al composite carbon dioxide oxide layer contains at least the crystal grains of the composite carbon dioxide oxide layer having a NaCl-type face-centered cubic structure.
(C) When the composite carbon dioxide oxide layer of Ti and Al is represented by the composition formula: (Ti _{(1-x) Al x} ) (Cy N _{1-yz Oz} ) (however, Ti of Al). The average content ratio x in the total amount of and Al, the average content ratio y in the total amount of C, N, and O of C, and the average content ratio z, x, y in the total amount of C, N, and O of O. , Z are all atomic ratios), 0.60 ≦ x ≦ 0.95, 0.010 ≦ y ≦ 0.100, 0.060 ≦ z ≦ 0.120, respectively.
(D) Fine particles of aluminum oxide are present in the composite carbon dioxide oxide layer of Ti and Al, and the average area ratio of the fine particles of aluminum oxide is 1 to 20 area%. Surface covering cutting tool.
(2) When the fine particles of aluminum oxide existing in the composite carbon dioxide oxide layer of Ti and Al are represented by the average composition formula: AlO _u , 1.4 ≤ u ≤ 1.6 is satisfied and the oxidation is performed. The surface-coated cutting tool according to (1), wherein the average particle size of the fine particles of aluminum is 0.010 to 0.300 μm.
(3) The Ti and Al composite carbon dioxide oxide layer is characterized in that the ratio of crystal grains of the Ti and Al composite carbon dioxide having a NaCl-type face-centered cubic structure is 40 area% or more. The surface-coated cutting tool according to (1) or (2).
(4) Between the tool substrate composed of the tungsten carbide-based cemented carbide, titanium nitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body and the composite carbonitride oxide layer of Ti and Al. It is composed of one or more layers of a carbide layer, a nitride layer, a carbide layer, a carbide layer and a carbon dioxide oxide layer of Ti, and is a total average layer of 0.1 to 20.0 μm. The surface-coated cutting tool according to any one of (1) to (3), wherein a lower layer including a thick Ti compound layer is present. "
Is.

INDUSTRIAL APPLICABILITY The present invention has excellent chipping resistance and excellent wear resistance over a long period of use even when subjected to high-speed intermittent cutting of alloy steel or the like.

It is a schematic diagram of the hard coating layer which concerns on this invention, and the thickness of a layer, the shape and dimension of the structure in a layer are not based on the actual hard coating layer, and the layer in parentheses is provided as necessary. Is.

The present invention will be described in detail below. When the numerical range is expressed by "-" in the present specification and the claims, the range includes the numerical values of the upper limit and the lower limit.

Average thickness of TiAlCNO layer contained in the hard coating layer:
The hard coating layer of the present invention contains at least a TiAlCNO layer represented by the composition formula: (Ti _1-x Al _x ) (Cy N _{1-y-z Oz )} . This TiAlCNO layer has high hardness and excellent chipping resistance and wear resistance, but the effect is remarkably exhibited particularly when the average layer thickness is 3.0 to 20.0 μm. This is because if the average layer thickness is less than 3.0 μm, the wear resistance cannot be sufficiently ensured over a long period of use because the layer thickness is thin, while if the average layer thickness exceeds 20.0 μm, the TiAlCNO layer cannot be sufficiently secured. Crystal grains are likely to be coarsened, and chipping is likely to occur.
Therefore, the average layer thickness was set to 3.0 to 20.0 μm. The average layer thickness is more preferably 5.0 to 15.0 μm.

Average composition of TiAlCNO layer contained in the hard coating layer:
The average composition of the TiAlCNO layer in the present invention is
The average content ratio (hereinafter referred to as "average content ratio of Al") x in the total amount of Ti and Al of Al is
The average content ratio (hereinafter referred to as "average content ratio of C") y in the total amount of C, N and O of C is
The average content ratio (hereinafter referred to as "the average content ratio of O") z in the total amount of C, N and O of O is
Satisfy 0.60 ≦ x ≦ 0.95, 0.010 ≦ y ≦ 0.100, 0.060 ≦ z ≦ 0.120 (however, x, y, and z are all atomic ratios). stipulate.
The reason is as follows.
When the average content ratio x of Al is less than 0.60, the hardness of the TiAlCNO layer is inferior. Therefore, when the TiAlCNO layer is subjected to high-speed intermittent cutting of alloy steel or the like, the wear resistance is not sufficient, while 0. If it exceeds 95, the average Ti content is relatively reduced, so that embrittlement is likely to occur and the chipping resistance is lowered. Therefore, it is set to 0.60 ≦ x ≦ 0.95, but more preferably 0.70 ≦ x ≦ 0.90.
Further, the reason why the average content ratio y of C is set to 0.010 ≦ y ≦ 0.100 is that the hardness can be improved while maintaining the chipping resistance in the above range.
Further, if the average content ratio z of O is less than 0.060, the oxidation resistance is not sufficiently provided, and if it exceeds 0.120, the oxide segregation occurs and the chipping resistance is lowered, which is not preferable. ..

Crystal grains having a NaCl-type face-centered cubic structure in the TiAlCNO layer and their area ratio:
The TiAlCNO layer needs to have crystal grains having a NaCl-type face-centered cubic structure (hereinafter, the crystal grains may be referred to as cubic crystal grains), and the presence thereof is an area ratio. The (area ratio) is preferably at least 40 area% or more. As a result, the area ratio of the crystal grains having a NaCl-type face-centered cubic structure with high hardness exists at a value that is somewhat high, so that the hardness is improved. Further, when the area ratio is 60 area% or more, the crystal grains having a NaCl-type face-centered cubic structure are relatively higher than the crystal grains having a hexagonal structure, and the effect of further improving the hardness is obtained. Obtainable. This area ratio is more preferably 75 area% or more.
Here, the area ratio of the crystal grains having a NaCl-type surface-centered cubic crystal structure is 100 μm in the vertical cross-sectional direction (direction perpendicular to the vertical cross-section (direction parallel to the surface of the tool substrate)) and the film thickness direction. Is a sufficient length in the measurement range of the film thickness, the vertical cross section of the TiAlCNO layer is polished, and an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees by using an electron backscatter diffraction image device. The crystal structure of each crystal grain was analyzed based on an electron backscatter diffraction image obtained by irradiating the electron beam with an irradiation current of 1 nA at intervals of 0.01 μm.

Presence of aluminum oxide microparticles in the TiAlCNO layer:
It is preferable that fine particles of aluminum oxide (average particle size of 0.500 μm or less) are present in the TiAlCNO layer in an average amount of 1 to 20 area%. The reason why the average area ratio (average area ratio) is in this range is that if it is less than 1 area%, the thermal stability of the TiAlCNO layer is impaired, and the outer layer as a protective layer can be sufficiently played during cutting. If it exceeds 20 area%, the characteristics of the composite carbon dioxide cannot be exhibited and the cutting performance deteriorates. A more preferable range is 3 to 10 area%.
Further, when the average composition of the fine particles of aluminum oxide is expressed as AlO _u , 1.4 ≦ u ≦ 1.6 is satisfied, and the average particle size of the particles is 0.010 to 0.300 μm. Desirable (u is atomic ratio). Here, u and the average particle size of the fine particles of aluminum oxide were observed by observing the vertical cross section (cross section in the layer thickness direction) of the TiAlCNO layer with a transmission electron microscope, and only Al and O were observed from the result of element mapping. By calculating the ratio of Al and O for the grains, the u value is calculated by analyzing the composition of the fine grains specified as AlO _u , the average area of the fine grains specified as AlO _u is obtained, and the average thereof is obtained. The average particle size is the diameter of a circle that gives an area equal to the area.
When u, which represents the average composition of the fine particles of aluminum oxide, satisfies the above range and the average particle size is within the desired range, the thermal stability of the TiAlCNO layer is further improved.

Lower layer:
The present invention comprises one or more layers of a carbide layer, a nitride layer, a carbonic acid nitride layer, a carbonic acid oxide layer and a carbonic acid nitrogen oxide layer of Ti, and has a total average layer of 0.1 to 20.0 μm. When the lower layer including the thick Ti compound layer is provided adjacent to the tool substrate, more excellent wear resistance and thermal stability can be exhibited.
Here, if the total average layer thickness of the lower layer is less than 0.1 μm, the effect of the lower layer is not sufficiently exhibited, while if it exceeds 20.0 μm, the crystal grains of the lower layer tend to be coarsened and chipping occurs. It will be easier to do.

Production method:
Next, the conditions for forming the TiAlCNO layer of the present invention are as follows, for example. Regarding the reaction gas composition, the following% is the volume% of the total of the gas group A and the gas group B.
-TiAlCNO layer Gas group A: NH ₃ : 2.0 to 6.0%, H ₂ : 65.0 to 75.0%
Gas group B: AlCl ₃ : 0.6 to 0.9%, TiCl ₄ : 0.2 to 0.3%, CO ₂ : 0.4 to 0.8%, C ₂ H ₄ : 0.0 to 0 .5%, N ₂ : 0.0 to 10.0%, H ₂ : Remaining reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-800 ° C
Supply cycle: 1.0 to 5.0 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Phase difference between supply of gas group A and gas group B: 0.10 to 0.20 seconds Here The addition of CO ₂ as a component of the gas group B is a feature for manufacturing the covering tool according to the present invention. This CO ₂ gas is a source of C and O in the TiAlCNO layer.
-Heat treatment of TiAlCNO layer After the TiAlCNO layer is formed, heat treatment is performed under the following conditions to generate fine particles of aluminum oxide.
Treatment atmosphere: Ar or N ₂ gas atmosphere Treatment pressure: 4.5-5.0 kPa
Processing temperature: 700-800 ° C
Processing time: 0.5 to 3 hours

FIG. 1 shows a schematic diagram of a hard coating layer in the covering tool of the present invention.

The covering tool of the present invention will be specifically described with reference to Examples.
In the following examples, the case where a WC-based cemented carbide is used as the tool substrate will be described, but the same applies to the case where a TiCN-based cermet or a cBN-based ultrahigh-pressure sintered body is used as the tool substrate.

<Example 1>
As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr _{3C 2} powder and Co powder having an average particle size of 1 to 3 μm are prepared, and these raw material powders are blended as shown in Table 1. It was blended into the composition, further added with wax, mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, press-molded into a green compact having a predetermined shape at a pressure of 98 MPa, and the green powder was pressed into a green compact of a predetermined shape in a vacuum of 5 Pa, 1370. Vacuum sintered at a predetermined temperature within the range of ~ 1470 ° C. under the condition of holding for 1 hour, and after sintering, manufacture tool bases A to C made of WC-based superhard alloy having an insert shape of ISO standard SEEN1203AFSN. did.

Next, a TiAlCNO layer was formed on the surfaces of these tool bases A to C by using a CVD device.
The film forming conditions by the CVD method are as follows.
The formation conditions A to F shown in Table 3, that is, the gas group A consisting of NH ₃ and H ₂ , the gas group B consisting of AlCl ₃ , TiCl ₄ , CO ₂ , N ₂ , and H ₂ , and the supply of each gas. As a method, the reaction gas composition (volume% of the total of the gas group A and the gas group B) is adjusted to NH ₃ : 2.0 to 6.0% and H ₂ : 65.0 to 75.0 as the gas group A. %, As gas group B, AlCl ₃ : 0.6 to 0.9%, TiCl ₄ : 0.2 to 0.3%, CO ₂ : 0.4 to 0.8%, C ₂ H ₄ : 0.0. ~ 0.5%, N ₂ : 0.0 ~ 10.0%, H ₂ : Remaining, reaction atmosphere pressure: 4.5 ~ 5.0 kPa, reaction atmosphere temperature: 700 ~ 800 ° C., supply cycle 1.0 ~ The gas supply time per cycle was set to 5.0 seconds, 0.15 to 0.25 seconds, the phase difference between the supplies of the gas group A and the gas group B was 0.10 to 0.20 seconds, and CVD was performed for a predetermined time. A TiAlCNO layer was formed.
After forming the TiAlCNO layer under the above conditions, the heat treatment conditions G to L shown in Table 4 are 0.5 to 0.5 at a temperature of 700 to 800 ° C. under a pressure of 4.5 to 5.0 kPa in an _N2 gas atmosphere. By performing the heat treatment for about 3 hours, fine particles of aluminum oxide were generated, and the covering tools 1 to 12 of the present invention shown in Table 6 were manufactured.
For the covering tools 4 to 9 of the present invention, the lower layer shown in Table 5 was formed under the formation conditions shown in Table 2.

Further, for the purpose of comparison, a film is formed on the surfaces of the tool substrates A to C by the CVD method under the formation conditions A'to F'shown in Table 3, and the heat treatment is performed under the heat treatment conditions G'to L'shown in Table 4. The comparative covering tools 1 to 12 shown in Table 7 were manufactured.
Similar to the covering tools 4 to 9 of the present invention, for the comparative covering tools 4 to 9, the lower layer shown in Table 5 was formed under the formation conditions shown in Table 2.

The average layer thickness is a cross section (vertical cross section) in the direction perpendicular to the tool substrate of each constituent layer of the covering tools 1 to 12 and the comparative covering tools 1 to 12 of the present invention, and an appropriate magnification (for example, using a scanning electron microscope). (Magnification 5000 times) was selected and observed, and the layer thicknesses of 5 points in the observation field of view were measured and averaged.

The average Al content ratio x of the TiAlCNO layer is obtained by irradiating an electron beam from the sample longitudinal section side in a sample whose longitudinal section has been polished using an electron probe microanalyzer (Electron-Probe-Micro-Analyzer: EPMA). The average content ratio x of Al was obtained from the 10-point average of the analysis results of the characteristic X-rays obtained.
The average content ratio y of C was determined by secondary ion mass spectrometry (Secondary-Ion-Mass-Spectroscopic: SIMS). An ion beam was irradiated in a range of 70 μm × 70 μm from the sample surface side, and the concentration of the component released by the sputtering action was measured up to the center of the TiAlCNO layer in the depth direction. The average content ratio y of C indicates the average value in the depth direction for the TiAlCNO layer.
For the average content ratio z of O, Auger electron spectroscopy (AES) was used to irradiate each layer with an electron beam from the longitudinal section side of the sample with a polished sample cross section, and the obtained Auger electrons were analyzed. From the result, the average content ratio z of O was obtained.
Tables 6 and 7 show the values of x, y, and z obtained above (x, y, and z are all atomic ratios).

Further, the area ratio of the crystal grains having a NaCl-type cubic structure in the TiAlCNO layer is 100 μm in the vertical cross-sectional direction (direction perpendicular to the vertical cross-section (direction parallel to the tool substrate surface)) and the film thickness direction. Is a sufficient length in the measurement range of the film thickness, the vertical cross section of the TiAlCNO layer is polished, and an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees by using an electron backscatter diffraction image device. The crystal structure of each crystal grain was analyzed based on an electron backscatter diffraction image obtained by irradiating the electron beam with an irradiation current of 1 nA at intervals of 0.01 μm. The results are shown in Tables 6 and 7.

Further, the average area ratio and average particle size of the fine particles of aluminum oxide, and the average ratio _u of O to Al when the fine particles of aluminum oxide are expressed as AlOu are the longitudinal cross-sectional directions (longitudinal section) of the composite carbon dioxide oxide layer. Using a transmission electron microscope in the direction perpendicular to the surface (direction parallel to the surface of the tool substrate), observation is performed for any 10 minute regions 1 μm × 1 μm at an acceleration voltage of 200 kV, and each observation is performed. In the region, composition analysis by energy dispersion type X-ray spectroscopy (EDS) is performed to identify fine particles in which only Al and O are detected, and then the average area ratio and the number of the fine particles are counted to determine the fine particles. The average area was calculated, and the average particle size was calculated from the diameter of the circle giving the area equal to the average area. Further, the ratio of Al and O in the fine particles of aluminum oxide was obtained from the result of the composition analysis of the fine particles of aluminum oxide, and the average ratio u of O to Al in the fine particles of aluminum oxide was obtained. The results are shown in Tables 6 and 7.

Next, with the various covering tools clamped to the tip of the tool steel cutter having a cutter diameter of 125 mm with a fixing jig, the covering tools 1 to 12 of the present invention and the comparative covering tools 1 to 12 are described below. A dry high-speed face milling cutter, which is a type of high-speed intermittent cutting of alloy steel, and a center-cut cutting process test were carried out, and the flank wear width of the cutting edge was measured.

Tool base: WC-based cemented carbide Cutting test: Dry high-speed face milling cutter, center cut cutting work Material: JIS / SCM440 Block material with width 100 mm and length 400 mm Rotation speed: 815 min ^-1
Cutting speed: 320 m / min
Notch: 3.0 mm
Single blade feed amount: 0.25 mm / blade Cutting time: 8 minutes (normal cutting speed: 150 to 200 m / min)
Table 8 shows the results.

<Example 2>
As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr _{3C 2} powder, TiN powder and Co powder having an average particle size of 1 to 3 μm are prepared, and these raw material powders are used. It was blended into the blending composition shown in Table 9, further added with wax, mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, and then press-molded into a green compact having a predetermined shape at a pressure of 98 MPa, and this green compact was obtained. ISO standard by vacuum sintering in a vacuum of 5 Pa at a predetermined temperature in the range of 1370 to 1470 ° C. under the condition of holding for 1 hour, and after sintering, honing processing of R: 0.07 mm is applied to the cutting edge. Tool bases α to γ made of WC-based superhard alloy having an insert shape of CNMG120412 were manufactured.

Next, a TiAlCNO layer was formed on the surfaces of these tool substrates α to γ under the formation conditions A to F shown in Table 3 using a CVD device.
After forming the TiAlCNO layer under the above conditions, the heat treatment conditions G to L shown in Table 4 are performed to generate fine particles of aluminum oxide, and the covering tools 13 to 20 of the present invention shown in Table 11 are manufactured. did.
For the covering tools 15 to 18 of the present invention, the lower layer shown in Table 10 was formed under the formation conditions shown in Table 2.

Further, for the purpose of comparison, a TiAlCNO layer is vapor-deposited and formed on the surfaces of the tool substrates α to γ in the same manner as the coated tool of the present invention under the conditions shown in Tables 3 and 4, and heat treatment is performed. The comparative covering tools 13 to 20 shown in Table 12 were manufactured.
Similar to the covering tools 15 to 18 of the present invention, for the comparative covering tools 15 to 18, the lower layer shown in Table 10 was formed under the formation conditions shown in Table 2.

Further, similarly to the covering tools 1 to 12 and the comparative covering tools 1 to 12 of the present invention, the average layer thickness of the covering tools 13 to 20 and the comparative covering tools 13 to 20 of the present invention was obtained, and the TiAlCNO layer contained an average amount of Al. The average content ratio y of the ratio x and C, and the average content ratio z of O are measured, and further, the area ratio of the cubic crystal grains in the TiAlCNO layer, the average area ratio of the fine particles of aluminum oxide, the average particle size, and the aluminum oxide are measured. The average ratio u of O to Al in the fine grain AlO _u was determined. These results are shown in Tables 11 and 12.

Next, with the various covering tools screwed to the tip of the tool steel cutting tool with a fixing jig, the covering tools 13 to 20 of the present invention and the comparative covering tools 13 to 20 are shown below. A dry high-speed intermittent cutting test of carbon steel was carried out, and the flank wear width of the cutting edge was measured in each case.
Tool base: WC-based cemented carbide Work material: JIS / S55C round bar with four vertical grooves at equal intervals in the length direction,
Cutting speed: 330 m / min
Notch: 3.0 mm
Feed: 0.25 mm / rev
Cutting time: 5 minutes (normal cutting speed is 220 m / min)
Table 13 shows the results of the cutting test.

From the results shown in Tables 8 and 13, the coating tool of the present invention contains crystal grains in which the TiAlCNO layer has a NaCl-type surface-centered cubic structure, and has a predetermined average content of Al, C, and O. Furthermore, since aluminum oxide fine particles having a predetermined average area ratio are present, the hardness is high and the oxidation resistance is high. As a result, high heat is generated and the cutting edge is intermittently and shockingly high. Even when used for high-speed intermittent cutting of alloy steel or the like on which a load acts, there is no chipping or chipping, and excellent wear resistance is exhibited over a long period of use.

On the other hand, in the TiAlCNO layer, the comparative covering tool in which the predetermined average contents of Al, C, and O and the fine particles of aluminum oxide do not satisfy the predetermined average area ratio is alloy steel or the like. It is clear that in high-speed intermittent cutting, the life is reached in a short time due to the occurrence of abnormal damage such as chipping or the progress of wear.

As described above, the covering tool of the present invention can be used not only for high-speed intermittent cutting of alloy steel and the like, but also as a covering tool for various work materials, and exhibits excellent cutting performance over a long period of use. Therefore, it is possible to fully satisfy the improvement of the performance of the cutting device, the labor saving and the energy saving of the cutting process, and the cost reduction.

Claims (4)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool substrate composed of either a tungsten carbide-based cemented carbide, a titanium nitride-based cermet, or a cubic boron nitride-based ultrahigh-pressure sintered body.
(A) The hard coating layer contains at least a composite carbon dioxide oxide layer of Ti and Al having an average layer thickness of 3.0 to 20.0 μm.
(B) The composite carbon dioxide oxide layer contains at least crystal grains of the composite carbon dioxide oxide layer having a NaCl-type face-centered cubic structure.
(C) When the composite carbon dioxide oxide layer is represented by the composition formula: (Ti _{(1-x) Al x} ) (Cy N _{1-yz Oz} ) (however, the combination of Ti and Al of Al). The average content ratio x and the average content ratio y in the total amount of C, N and O of C, and the average content ratio z, x, y and z in the total amount of C, N and O of O are any of them. Also atomic ratio), 0.60 ≦ x ≦ 0.95, 0.010 ≦ y ≦ 0.100, 0.060 ≦ z ≦ 0.120, respectively.
(D) A surface-coated cutting tool characterized in that fine particles of aluminum oxide are present in the composite carbon dioxide oxide layer, and the average area ratio of the fine particles of aluminum oxide is 1 to 20 area%. .. When the fine particles of aluminum oxide existing in the composite carbon dioxide oxide layer of Ti and Al are represented by the average composition formula: AlO _u , 1.4 ≦ u ≦ 1.6 is satisfied, and the fine particles of aluminum oxide are satisfied. The surface-coated cutting tool according to claim 1, wherein the average grain size of the grains is 0.010 to 0.300 μm. The Ti and Al composite carbon dioxide oxide layer is characterized in that the ratio of crystal grains of the Ti and Al composite carbon dioxide having a NaCl-type face-centered cubic structure is 40 area% or more. Item 2. The surface-coated cutting tool according to Item 1 or 2. Between the tool substrate composed of the tungsten carbide-based cemented carbide, titanium nitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body and the composite carbonitride oxide layer of Ti and Al, Ti. It is composed of one or more layers of the carbide layer, the nitride layer, the carbonitride layer, the carbide layer and the carbonitride oxide layer, and has a total average layer thickness of 0.1 to 20.0 μm. The surface-coated cutting tool according to any one of claims 1 to 3, wherein a lower layer including a Ti compound layer is present.

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