JP2007098503A - Cutting tool made of coated cemented carbide having hard coating layer exhibiting excellent chipping resistance in high speed deep cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool made of coated cemented carbide having hard coating layer exhibiting excellent chipping resistance in high speed deep cutting. <P>SOLUTION: In this cutting tool made of coated cemented carbide, the hard coating layer is partially composed of a modified TiC layer and a modified TiCN layer. These layers both have the highest peak in Σ3 in a constitutive atom covalent lattice point distribution graph, which is created based upon the measured angles of inclination obtained by measuring angles of inclination to the normal of surface polishing surface of the normals of a (001) face and (011) face which are crystal faces of crystal grains having an NaCl type face-centered cubic structure using a field emission scanning electron microscope. Further, in the constitutive atom covalent lattice point distribution graph, the distribution percentage of Σ3 occupying the whole ΣN+1 is 60% or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent chipping resistance with a hard coating layer, particularly in high-speed heavy cutting of steel or cast iron.

Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) Titanium carbide (hereinafter referred to as TiC) layer, titanium nitride (hereinafter also referred to as TiN) layer, titanium carbonitride (hereinafter referred to as TiCN) layer, all formed by chemical vapor deposition as the lower layer, A Ti compound layer consisting of one or more of a titanium carbonate (hereinafter referred to as TiCO) layer and a titanium carbonitride oxide (hereinafter referred to as TiCNO) layer and having a total average layer thickness of 3 to 20 μm,
(B) As an upper layer, an average layer thickness of 1 to 15 μm, and an aluminum oxide layer having an α-type crystal structure in a state where chemical vapor deposition is formed (hereinafter referred to as an α-type Al ₂ O ₃ layer),
A coated cermet tool formed by forming a hard coating layer composed of (a) and (b) above is known, and this coated cermet tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is also known that
Japanese Unexamined Patent Publication No. 6-31503

In recent years, the performance of cutting equipment has been remarkable, while there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and with this, cutting speed has been increased for the purpose of improving cutting efficiency, and Cutting tends to be performed under high-speed heavy cutting conditions that increase cutting depth and feed, etc., but the above-mentioned conventional coated cermet tools can be used for continuous cutting and intermittent cutting under normal conditions such as steel and cast iron. There is no problem when it is used, but when it is used for high-speed heavy cutting with severe cutting conditions, that is, when it is used for high-speed heavy cutting where a very high mechanical load is applied to the cutting edge, the hard coating layer constituting this Has high-temperature strength due to the lower Ti compound layer, high-temperature hardness and heat resistance due to the α-type Al ₂ O ₃ layer known as the upper high-temperature hard layer, Due to insufficient high-temperature strength, it is not possible to satisfactorily cope with the above-mentioned mechanical high load, and as a result, chipping (minute chipping) is likely to occur in the hard coating layer. At present, the service life is reached in a short time.

In view of the above, the present inventors have known as a high-temperature strengthening layer among the Ti compound layers, which are the lower layers, in order to improve the chipping resistance of the hard coating layer of the above-mentioned coated cermet tool. TiC layer and TiCN layer, that is, a Ti compound layer having a relatively high high-temperature hardness and high-temperature strength, and the TiCN layer, as shown in the schematic diagram of FIG. A TiCN layer having a crystal structure of NaCl-type face-centered cubic crystal in which each of the constituent atoms composed of Ti, carbon, and nitrogen is present [FIG. 1 (b) shows a state cut by the (011) plane], and As a result of conducting research by paying attention to a TiC layer having an NaCl type face centered cubic crystal structure in which nitrogen at lattice points in the crystal structure of the TiCN layer is replaced by carbon,
(A) The TiCN layer (hereinafter referred to as the conventional TiCN layer) constituting the lower layer of the hard coating layer of the conventional coated cermet tool is, for example, an ordinary chemical vapor deposition apparatus.
Reaction gas composition: by _{volume%, TiCl 4: 2~10%,} CH 3 CN: 0.5~3%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 15-25 kPa,
It is formed by vapor deposition under the conditions (called normal conditions).
Reaction gas composition: by _{volume%, TiCl 4: 0.1~0.8%,} CH 3 CN: 0.05~0.3%, Ar: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 930 to 1000 ° C.
Reaction atmosphere pressure: 6-13 kPa,
The reaction gas composition is relatively low in TiCl ₄ and CH ₃ CN, Ar gas is added instead of N ₂ gas, and the ambient temperature is relatively The TiCN layer formed as a result (hereinafter referred to as a modified TiCN layer) has a further improved high-temperature strength. Contribute to the chipping resistance improvement of the hard coating layer even in high-speed heavy cutting where a very high mechanical load is applied to the part.

(B) Similarly, the TiC layer (hereinafter referred to as the conventional TiC layer) constituting the lower layer of the hard coating layer of the conventional coated cermet tool is, for example, a normal chemical vapor deposition apparatus.
Reaction gas composition:% by volume, TiCl ₄ : 2 to 10%, CH ₄ : 2 to 10%, H ₂ : remaining,
Reaction atmosphere temperature: 950 to 1000 ° C.
Reaction atmosphere pressure: 20-40 kPa,
It is formed by vapor deposition under the conditions (called normal conditions).
Reaction gas composition: by _{volume%, TiCl 4: 0.5~1.5%,} CH 4: 0.5~3%, H 2: remainder,
Reaction atmosphere temperature: 1000 to 1050 ° C.
Reaction atmosphere pressure: 6-15 kPa,
In the reaction gas composition, the TiCl ₄ and CH ₄ are relatively low, the atmospheric temperature is relatively high, and the atmospheric pressure is low. The resulting TiC layer (hereinafter referred to as the modified TiC layer) has been further improved in high-temperature strength, so even in high-speed heavy cutting where a very high mechanical load is applied to the cutting edge, Contribute to improving the chipping resistance of the hard coating layer.

(C) About the conventional TiCN layer and the conventional TiC layer, and the modified TiCN layer and the modified TiC layer.
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams in FIGS. 2A and 2B, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, The inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are the crystal planes of the crystal grains, with respect to the normal line of the surface polished surface (FIG. 2A shows (001) of the crystal planes. When the tilt angle of the surface is 0 degree and the tilt angle of the (011) plane is 45 degrees, the tilt angle of the (001) plane is 45 degrees and the tilt angle of the (011) plane is 0 degree. In this case, all the tilt angles of the crystal grains including these angles are measured. In this case, the crystal grains are at lattice points as described above, and Ti, carbon and nitrogen in the case of a TiCN layer. NaCl type face-centered cubic with Ti atoms and Ti atoms. Lattice points where each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains based on the measured tilt angle obtained as a result of The distribution of (constituent atom shared lattice points) is calculated, and the number of lattice points that do not share constituent atoms between the constituent atom shared lattice points is N (N is an even number of 2 or more in the crystal structure of the NaCl type face centered cubic crystal). ) Constituent atomic shared lattice point distribution is shown as ΣN + 1, and a constituent atomic shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 to the entire ΣN + 1 (however, the upper limit is 28 due to frequency) was created. 3 and 4, the modified TiCN layer and the modified TiC layer both have the highest peak in Σ3, and the extremely high constituent atom sharing in which the distribution ratio of Σ3 is 60% or more. Grid distribution graph In contrast, the conventional TiCN layer and the conventional TiC layer, as illustrated in FIGS. 5 and 6, show a relatively low constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 30% or less, These high Σ3 distribution ratios should be changed by adjusting the above deposition conditions.

(D) The modified TiCN layer and the modified TiC layer have a higher high-temperature strength than the conventional TiCN layer and the conventional TiC layer in addition to the high-temperature hardness and high-temperature strength of the TiCN itself and the TiC itself. Therefore, the coated cermet tool formed by vapor deposition using the modified TiCN layer as the lower high-temperature strengthened layer as the hard coating layer and the modified TiC layer as the upper high-temperature strengthened layer is formed of the high-temperature hard layer as the upper layer. Combined with the excellent high-temperature hardness and heat resistance of the α-type Al ₂ O ₃ layer, the hard coating layer exhibits excellent chipping resistance even in high-speed heavy cutting with extremely high load, To show excellent wear resistance over a long period of time.
The research results shown in (a) to (d) above were obtained.

The present invention has been made based on the above research results. A hard coating layer formed by chemical vapor deposition on the surface of a tool base made of a WC-base cemented carbide or TiCN-base cermet is provided on the tool base side. In order from
(A) a substrate adhesion layer comprising a TiN layer having an average layer thickness of 0.1 to 1 μm;
(B) a lower high-temperature reinforcing layer comprising a TiCN layer having an average layer thickness of 2 to 15 μm,
(C) an upper high-temperature reinforcing layer comprising a TiC layer having an average layer thickness of 2 to 10 μm,
(D) one of the TiCO layer and the TiCNO layer having an average layer thickness of 0.1 to 1 μm, or an interlayer adhesion layer composed of both layers,
(E) a high-temperature hard layer comprising an α-type Al ₂ O ₃ layer having an average layer thickness of 1 to 15 μm,
With the above (a) to (e), the lower high-temperature reinforcing layer and the upper high-temperature reinforcing layer are
Using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal plane of the crystal grain is normal to the surface polished surface ( The inclination angle formed by the normal lines of the (001) plane and the (011) plane is measured. In this case, the crystal grains have Ti and carbon and nitrogen (in the case of the lower high-temperature strengthening layer) or Ti and carbon (upper side) at lattice points. In the case of a high-temperature strengthened layer), each of the atoms has a NaCl-type face-centered cubic crystal structure in which constituent atoms are present, and based on the measured tilt angle obtained as a result, at the interface between adjacent crystal grains, A distribution of lattice points (constituent atom shared lattice points) in which each constituent atom shares one constituent atom among the crystal grains is calculated, and there are N lattice points that do not share constituent atoms between the constituent atom shared lattice points. (N is 2 on the crystal structure of NaCl type face centered cubic crystal) When the existing constituent atom shared lattice point form is expressed by ΣN + 1, the constituent atom sharing indicates the distribution ratio of each ΣN + 1 in the entire ΣN + 1 (however, the upper limit is 28 due to the frequency) In each of the lattice point distribution graphs, a modified TiCN layer and a modified TiC layer each showing a constituent atom shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio of Σ3 to the entire ΣN + 1 is 60% or more ,
It is characterized by a coated cermet tool that exhibits excellent chipping resistance in a high-speed heavy cutting process with a hard coating layer.

Next, the reason why the constituent layers of the hard coating layer of the coated cermet tool of the present invention are numerically limited as described above will be described below.
(A) TiN layer (substrate adhesion layer)
The TiN layer adheres firmly to both the tool substrate and the modified TiCN layer, which is the lower high-temperature reinforcing layer, and thus has an effect of improving the adhesion of the hard coating layer to the tool substrate. If the thickness is less than 0.1 μm, the desired adhesion cannot be ensured. On the other hand, an average layer thickness of 1 μm is sufficient for the adhesion, so the average layer thickness was determined to be 0.1 to 1 μm.

(B) Modified TiCN layer (lower high-temperature reinforcing layer)
As described above, the modified TiCN layer has a further improved high-temperature strength as compared with the conventional TiCN layer. This characteristic indicates that the distribution ratio of Σ3 in the constituent atom sharing lattice distribution graph is the deposition condition. Therefore, when the distribution ratio of Σ3 is less than 60%, it is possible to achieve high temperature strength improvement effect that does not cause chipping in the hard coating layer in high speed heavy cutting. Therefore, the distribution ratio of Σ3 is determined to be 60% or more.
As described above, the modified TiCN layer has a further excellent high-temperature strength in addition to the high-temperature hardness and high-temperature strength of the TiCN itself as described above. However, when the average layer thickness is less than 2 μm, the desired excellent properties are obtained. However, if the average layer thickness exceeds 15 μm, thermoplastic deformation that causes uneven wear tends to occur and the wear accelerates. Therefore, the average layer thickness was determined to be 2 to 15 μm.

(C) Modified TiC layer (upper high temperature strengthened layer)
The above-mentioned modified TiC layer does not reach the point of high-temperature strength as compared with the above-mentioned modified TiCN layer, but has a relatively high high-temperature hardness, and thus contributes to the improvement of the wear resistance of the hard coating layer. In addition, as described above, it has excellent high-temperature strength compared to the conventional TiC layer, so it contributes to the improvement of chipping resistance of the hard coating layer by high-speed heavy cutting. The distribution ratio of Σ3 in the point distribution graph can be adjusted to 60% or more by adjusting the vapor deposition conditions. Therefore, if the distribution ratio of Σ3 is less than 60%, the hard coating layer is formed by high-speed heavy cutting. Therefore, the distribution ratio of Σ3 was determined to be 60% or more because chipping does not occur and an excellent high-temperature strength improvement effect cannot be secured.
As described above, the modified TiC layer has a higher temperature strength than that of the conventional TiC layer in addition to the high temperature hardness of the TiC itself, but it is desirable if the average layer thickness is less than 2 μm. However, if the average layer thickness exceeds 10 μm, chipping is likely to occur, so that the average layer thickness is 2 to 2. It was determined to be 10 μm.

(D) TiCO layer and TiCNO layer (interlayer adhesion layer)
The TiCO layer and the TiCNO layer adhere firmly to both the modified TiC layer, which is the upper high-temperature strengthening layer, and the α-type Al ₂ O ₃ layer, which is the high-temperature hard layer, thereby improving the adhesion of the hard coating layer to the tool substrate. However, if the average layer thickness is less than 0.1 μm, the desired adhesion cannot be ensured, while the excellent adhesion can be sufficiently ensured with an average layer thickness of 1 μm. The average layer thickness was determined to be 0.1 to 1 μm.

(E) α-type Al ₂ O ₃ layer (high-temperature hard layer)
The α-type Al ₂ O ₃ layer has excellent high-temperature hardness and heat resistance and contributes to improving the wear resistance of the hard coating layer. However, if the average layer thickness is less than 1 μm, the hard coating layer has sufficient wear resistance. On the other hand, if the average layer thickness exceeds 15 μm, the chipping tends to occur. Therefore, the average layer thickness is set to 1 to 15 μm.

  In addition, for the purpose of identification before and after the use of the cutting tool, a TiN layer having a golden color tone may be vapor-deposited as necessary, but the average layer thickness in this case may be 0.1 to 1 μm, This is because if the thickness is less than 0.1 μm, a sufficient discrimination effect cannot be obtained, while the discrimination effect by the TiN layer is sufficient with an average layer thickness of up to 1 μm.

  The coated cermet tool of the present invention has a lower high-temperature strengthened layer and an upper high-temperature strengthened layer compared with the conventional TiCN layer and the conventional TiC layer even in high-speed heavy cutting such as steel and cast iron with extremely high mechanical load. In addition, since it is composed of a modified TiCN layer and a modified TiC layer having a further excellent high-temperature strength, the hard coating layer exhibits excellent wear resistance without occurrence of chipping.

  Next, the coated cermet tool of the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By performing the processing, tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG150612 were manufactured.

In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases a to f made of TiCN-based cermet having standard / CNMG150612 chip shapes were formed.

Next, on the surfaces of these tool bases A to F and tool bases a to f, a normal chemical vapor deposition apparatus is used. First, as the base adhesion layer of the hard coating layer, the conditions shown in Table 3 are used. A TiN layer having the target average layer thickness shown is formed, and then, under the conditions shown in Table 4, the modified TiCN layer and the modified TiC layer are shown in Table 6 as the lower high temperature strengthened layer and the upper high temperature strengthened layer. In addition, as an interlayer adhesion layer, either or both of the TiCO layer and the TiCNO layer, or both, are used as the interlayer adhesion layer under the conditions shown in Table 3. By forming the α-type Al ₂ O ₃ layer having the target average layer thickness shown in Table 6 under the conditions shown in Table 3 as the high-temperature hard layer in the state of being formed with a thickness, the coated cermet tool 1 to 1 of the present invention is formed. 12 Each was manufactured.

  For comparison purposes, as shown in Table 7, instead of the above-described modified TiCN layer and modified TiC layer, the lower high temperature strengthened layer and the upper high temperature strengthened layer of the hard coating layer are shown in Table 5. The conventional coated cermet tools 1 to 12 were manufactured under the same conditions except that the conventional TiCN layer and the conventional TiC layer were formed under the same conditions.

Next, the modified TiCN layer and the modified TiC layer constituting the hard coating layer of the above-described coated cermet tool of the present invention and the conventional coated cermet tool, and further the conventional TiCN layer and the conventional TiC layer, using a field emission scanning electron microscope. Each component atom shared lattice distribution graph was created.
That is, the above constituent atomic shared lattice point distribution graph is obtained when the surface of the modified TiCN layer and the modified TiC layer, and the surface of the conventional TiCN layer and the conventional TiC layer are polished surfaces, respectively. Set in the lens barrel, and irradiate the polishing surface with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees with an irradiation current of 1 nA on each crystal grain existing in the measurement range of the surface polishing surface, Using an electron backscatter diffraction image apparatus, a region of 30 × 50 μm is spaced at a spacing of 0.1 μm / step, and the (001) plane and (011) which are crystal planes of the crystal grains with respect to the normal line of the polished surface ) Measure the tilt angle formed by the normals of the surface, and based on the measured tilt angle obtained as a result, each of the constituent atoms forms one structure between the crystal grains at the interface between adjacent crystal grains. Share atoms The distribution of child points (constituent atom shared lattice points) is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (N is an even number of 2 or more in the crystal structure of the NaCl type face centered cubic crystal) In the case where the existing constituent atom shared lattice point form is expressed as ΣN + 1, the distribution ratio is calculated by calculating the distribution ratio of each ΣN + 1 to the whole ΣN + 1 (however, the upper limit value is 28 due to the frequency).

  In the resulting modified TiCN layer and modified TiC layer, and further in the constituent atomic shared lattice distribution graph of the conventional TiCN layer and the conventional TiC layer, the entire ΣN + 1 (N is an even number in the range of 2 to 28). Table 8 shows the distribution ratio of Σ3 in the table.

In each of the above-mentioned various constituent atomic share lattice point distribution graphs, as shown in Table 8, each of the modified TiCN layer and the modified TiC layer of the coated cermet tools 1 to 12 according to the present invention has a distribution ratio of Σ3 of 60. %, The conventional TiCN layer and the conventional TiC layer of the conventional coated cermet tools 1 to 12 both have a Σ3 distribution ratio of 30% or less. A point distribution graph was shown.
3 and 4 are graphs showing the distribution of constituent atomic shared lattice points of the modified TiCN layer (FIG. 3) and the modified TiC layer (FIG. 4) of the coated cermet tool 4 of the present invention, and FIGS. The conventional TiCN layer (FIG. 5) and the conventional TiC layer (FIG. 6) constituent atom share lattice point distribution graph of the tool 4 are shown, respectively.

  Further, for the above-described coated cermet tools 1-12 of the present invention and the conventional coated cermet tools 1-12, the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analyzer (layer When the longitudinal section was observed), it was confirmed that both the former and the latter had substantially the same composition as the target composition, and the thicknesses of the constituent layers of the hard coating layers of these coated cermet tools were measured using a scanning electron microscope. When measured using (same longitudinal section measurement), all showed an average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness.

Next, in the state where each of the various coated cermet tools is screwed to the tip of the tool steel tool with a fixing jig, the present coated cermet tools 1 to 12 and the conventional coated cermet tools 1 to 12,
Work material: JIS / S10C round bar,
Cutting speed: 350 m / min,
Cutting depth: 7.5mm,
Feed: 0.35mm / rev,
Cutting time: 8 minutes
Dry continuous high-speed high-cut cutting test of carbon steel under the following conditions (cutting condition A) (normal cutting speed and cutting are 200 m / min and 3 mm),
Work material: JIS · SCr420H lengthwise equidistant four round grooved round bars,
Cutting speed: 350 m / min,
Cutting depth: 7.5mm,
Feed: 0.3mm / rev,
Cutting time: 8 minutes
Dry interrupted high-speed high-cut cutting test of alloy steel under the following conditions (cutting condition B) (normal cutting speed and cutting are 200 m / min and 2 mm),
Work material: JIS / FCD500 round bar,
Cutting speed: 350 m / min,
Incision: 3mm,
Feed: 0.8mm / rev,
Cutting time: 8 minutes
The dry continuous high-speed, high-feed cutting test (normal cutting speed and feed are 180 m / min and 0.4 mm / rev) of cast iron under the above conditions (cutting condition C). The width was measured. The measurement results are shown in Table 8.

  From the results shown in Tables 6 to 8, in the coated cermet tools 1 to 12 of the present invention, the lower high-temperature reinforced layer and the upper high-temperature reinforced layer of the hard coating layer both share constituent atoms in which the distribution ratio of Σ3 is 60% or more. High-temperature strength consisting of a modified TiCN layer and a modified TiC layer showing a lattice point distribution graph, and the modified TiCN layer and the modified TiC layer are excellent in high-speed heavy cutting of steel and cast iron with extremely high mechanical load. Since it has excellent chipping resistance, the occurrence of chipping in the hard coating layer is remarkably suppressed, while excellent wear resistance is demonstrated over a long period of time. Conventional coated cermet tools 1 to 12 each composed of a conventional TiCN layer and a conventional TiC layer in which the reinforcing layer and the upper high-temperature reinforcing layer show a constituent atomic shared lattice point distribution graph in which the distribution ratio of Σ3 is 30% or less In both cases, in high-speed heavy cutting, it is clear that chipping occurs in the hard coating layer due to insufficient high-temperature strength of the hard coating layer, and the service life is reached in a relatively short time.

  As described above, the coated cermet tool of the present invention has a hard coating layer not only for continuous cutting and interrupted cutting under normal conditions such as various steels and cast iron, but also for high-speed heavy cutting that requires particularly high high-temperature strength. Since it exhibits excellent chipping resistance and exhibits excellent cutting performance over a long period of time, it is fully satisfactory for higher performance of cutting equipment, labor saving and energy saving of cutting, and cost reduction. It can be done.

The crystal structure of NaCl type face centered cubic crystal of the TiCN layer constituting the lower high temperature strengthening layer of the hard coating layer (the TiC layer of the upper high temperature strengthened layer is the same crystal in which N atoms in the TiCN layer are replaced by C atoms) It is a schematic diagram showing a structure. It is a schematic explanatory drawing which shows the measurement aspect of the inclination angle of the (001) plane of a crystal grain and the (011) plane in the TiCN layer and TiC layer which comprise a lower high temperature reinforcement layer and an upper high temperature reinforcement layer of a hard coating layer. It is a constituent atomic share lattice point distribution graph of the modified TiCN layer which comprises the lower high temperature reinforcement layer of the hard coating layer of this invention coated cermet tool 4. FIG. It is a structure atomic share lattice point distribution graph of the modified TiC layer which comprises the upper high temperature reinforcement layer of the hard coating layer of this invention coating | cover cermet tool 4. FIG. 6 is a constituent atomic shared lattice point distribution graph of a conventional TiCN layer constituting a lower high temperature strengthening layer of a hard coating layer of a conventional coated cermet tool 4. It is a structure atomic share lattice point distribution graph of the conventional TiC layer which comprises the upper high temperature reinforcement layer of the hard coating layer of the conventional coating cermet tool 4. FIG.

Claims (1)

The hard coating layer formed by chemical vapor deposition on the surface of the tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet, in order from the tool base side,
(A) a substrate adhesion layer comprising a titanium nitride layer having an average layer thickness of 0.1 to 1 μm;
(B) a lower high-temperature reinforcing layer comprising a titanium carbonitride layer having an average layer thickness of 2 to 15 μm,
(C) an upper high-temperature reinforcing layer comprising a titanium carbide layer having an average layer thickness of 2 to 10 μm,
(D) an interlayer adhesion layer comprising any one of a titanium carbonate layer and a titanium carbonitride oxide layer having an average layer thickness of 0.1 to 1 μm, or both layers;
(E) a high-temperature hard layer composed of an aluminum oxide layer having an α-type crystal structure in an average layer thickness of 1 to 15 μm and chemical vapor deposition;
With the above (a) to (e), the upper high-temperature reinforcing layer and the lower high-temperature reinforcing layer are
Using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal plane of the crystal grain is normal to the surface polished surface ( The inclination angle formed by the normal lines of the (001) plane and the (011) plane is measured. In this case, the crystal grains have Ti and carbon (in the case of the upper high-temperature strengthening layer) or Ti, carbon and nitrogen (lower side) at lattice points. In the case of a high-temperature strengthened layer), each of the atoms has a NaCl-type face-centered cubic crystal structure in which constituent atoms are present, and based on the measured tilt angle obtained as a result, at the interface between adjacent crystal grains, A distribution of lattice points (constituent atom shared lattice points) in which each constituent atom shares one constituent atom among the crystal grains is calculated, and there are N lattice points that do not share constituent atoms between the constituent atom shared lattice points. (N is 2 on the crystal structure of NaCl type face centered cubic crystal) When the existing configuration atom sharing lattice point form is expressed as ΣN + 1, the configuration atom sharing indicating the distribution ratio of each ΣN + 1 in the entire ΣN + 1 (however, the upper limit is 28 due to the frequency) In each of the lattice point distribution graphs, the modified titanium carbide layer and the modified coal showing the constituent atom sharing lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio of the Σ3 to the entire ΣN + 1 is 60% or more Titanium nitride layer,
A surface-coated cermet cutting tool that exhibits excellent chipping resistance in a high-speed heavy-cutting process that features a hard coating layer.

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