JP4716252B2 - Surface-coated cermet cutting tool with excellent chipping resistance thanks to thick α-type aluminum oxide layer - Google Patents

Description

In the present invention, an upper layer of a hard coating layer, that is, an aluminum oxide layer (hereinafter referred to as an α-type Al ₂ O ₃ layer) having an α-type crystal structure in a state where chemical vapor deposition is formed is particularly thick. The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent chipping resistance even when used for cutting various steels and 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) As a lower layer, a Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer formed by chemical vapor deposition, Ti compound layer composed of one or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having an overall average layer thickness of 3 to 20 μm ,
(B) an α-type Al ₂ O ₃ layer having an average layer thickness of 1 to 15 μm as an upper layer;
There is known a coated cermet tool formed by vapor-depositing a hard coating layer composed of (a) and (b) above, and this coated cermet tool can be used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is well known to be used.
Further, the TiCN layer constituting the lower layer of the hard coating layer has a NaCl-type face center in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points, as schematically shown in FIG. It has a cubic crystal structure [FIG. 8 (b) shows a state cut along the (011) plane], and the α-type Al ₂ O ₃ layer, which is the same upper layer, is shown in FIG. Corundum-type hexagonal close-packed crystal in which constituent atoms composed of Al and oxygen are present at lattice points as shown in the schematic diagram (perspective view and plan view of cross sections 1 to 9) of the unit lattice of ₂ O ₃ It is also known to have a crystal structure of
Japanese Unexamined Patent Publication No. 6-31503

In recent years, the use of FA for cutting devices has been remarkable. On the other hand, there has been a strong demand for labor saving and energy saving and further cost reduction for cutting work, and with this purpose, especially for the purpose of further extending the service life of cutting tools. upper layer constituting the hard coating layer, i.e. excellent but the hot hardness and thickening of one step in the α-type the Al ₂ O ₃ layer having heat resistance is strongly demanded, of the α-type the Al ₂ O ₃ layer When the layer thickness exceeds 15 μm, which is the maximum average layer thickness that has been practically used in the past, the Al ₂ O ₃ crystal grains become coarser and the denseness of the layer itself is significantly reduced. since the decrease in the high-temperature strength can not be avoided, the coated cermet tool formed by depositing formed as an upper layer of such thickening α type the Al ₂ O ₃ layer a hard coating layer, the thickening α-type Al ₂ O ₃ layer due to chipping to the cutting edge (fine Chipping) is likely to occur, since it becomes very short for this result useful life, it can not be put to practical use at present.

Therefore, the present inventors focused on the α-type Al ₂ O ₃ layer having an average layer thickness of 1 to 15 μm constituting the hard coating layer of the above-described conventional coated cermet tool from the above viewpoint, Research was conducted to develop a coated cermet tool in which chipping caused by the thickened α-type Al ₂ O ₃ layer does not occur at the cutting edge even if the layer thickness is increased to an average layer thickness exceeding 15 μm. result,
(1-a) An α-type Al ₂ O ₃ layer (hereinafter referred to as “conventional α-type Al ₂ O ₃ layer”) as an upper layer constituting the hard coating layer of the conventional coated cermet tool is, for example, a normal In chemical vapor deposition equipment,
Reaction gas composition: volume%, AlCl ₃ : 2 to 4%, CO ₂ : 6 to 8%, HCl: 1.5 to 3%, H ₂ S: 0.05 to 0.2%, H ₂ : remaining ,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
It is formed by vapor deposition under the conditions (called normal conditions).
Reaction gas composition: by _{volume%, AlCl 3: 6~10%,} CO 2: 10~15%, HCl: 3~5%, H 2 S: 0.05~0.2%, H 2: remainder,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 3 to 5 kPa,
In other words, in the reaction gas composition, the content ratio of AlCl ₃ , CO ₂ , and HCl is relatively high and the atmospheric pressure is relatively low (reaction gas component high). When the layer thickness is 16-30 μm, which exceeds 15 μm in average layer thickness under the content-adjusting low-pressure conditions, the resulting thickened α-type Al ₂ O ₃ layer (hereinafter referred to as “thickened modified α-type”) is formed. (Al ₂ O ₃ layer), although the average layer thickness is increased to 16-30 μm, the coarsening of Al ₂ O ₃ crystal grains is remarkably suppressed and the layer itself is dense. Since it is also retained, the decrease in high-temperature strength is suppressed and rather improved.

(1-b) The above-described thickened modified α-type Al ₂ O ₃ layer and the thickened α-type Al ₂ O ₃ layer formed by vapor deposition with an average layer thickness of 16 to 30 μm under the above-described normal conditions ( (Hereinafter referred to as a thickened normal α-type Al ₂ O ₃ layer)
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams in FIGS. 1A and 1B, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, The tilt angle formed by the normal lines of the (0001) plane and the (10-10) plane, which are the crystal planes of the crystal grains, with respect to the normal line of the polished surface [FIG. 1 (a) shows the tilt angle of the crystal plane. (B) shows the case where the inclination angle is 45 degrees, all the inclination angles of the individual crystal grains including these angles are measured. In this case, the crystal grains Has a crystal structure of a corundum type hexagonal close-packed crystal in which constituent atoms composed of Al and oxygen are present at lattice points as described above, and based on the measured tilt angle, crystal grains adjacent to each other are obtained. Each of the constituent atoms shares one constituent atom between the crystal grains at the interface 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 (where N is two or more on the crystal structure of the corundum hexagonal close-packed crystal) Even if the upper limit of N is 28 from the point of distribution frequency, the even number of 4, 8, 14, 24, and 26 does not exist), and the existing constituent atomic shared lattice point form is expressed as ΣN + 1, When a constituent atom shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1 is created (in this case, the constituent atom shared lattice point forms of Σ5, Σ9, Σ15, Σ25, and Σ27 exist) The thickened normal α-type Al ₂ O ₃ layer shows a relatively low constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 30% or less as illustrated in FIG. In contrast, the thickening reforming -Type Al ₂ O ₃ layer as illustrated in FIG. 3, shows an extremely high atom sharing lattice point distribution graph of the distribution ratio is 60% or more of the [sum] 3, the distribution ratio of the high [sum] 3 constitutes a reaction gas Vary depending on the AlCl ₃ , CO ₂ , and HCl content, and the atmospheric reaction pressure.
In addition, in the above-described thickened modified α-type Al ₂ O ₃ layer and thickened normal α-type Al ₂ O ₃ layer, Σ3 of constituent atomic shared lattice point forms at the interface between adjacent crystal grains, The unit forms of Σ7 and Σ11 are schematically illustrated as shown in FIGS. 2A to 2C (the same applies to the modified TiCN layer and the conventional TiCN layer described below).

(2-a) Furthermore, the TiCN layer (hereinafter referred to as “conventional TiCN layer”) constituting the Ti compound layer, which is the lower layer of the hard coating layer of the conventional coated cermet tool, is a normal 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: 6-20 kPa,
It is formed under the conditions of, but this is also a normal chemical vapor deposition device,
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: 6-20 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 When the vapor deposition is carried out under the condition (reaction gas composition adjustment high temperature condition), the TiCN layer (hereinafter referred to as “modified TiCN layer”) formed under the reaction gas composition adjustment high temperature condition as a result is further improved in high temperature strength. To be like that.

(2-b) Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams of FIGS. 5A and 5B, an electron beam is individually applied to each crystal grain existing within the measurement range of the surface polished surface. The tilt angle formed by the normal lines of the (001) plane and the (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the surface polished surface upon irradiation (the crystal plane in FIG. When the inclination angle of the (001) plane is 0 degree and the inclination angle of the (011) plane is 45 degrees, the inclination angle of the (001) plane is 45 degrees and the inclination angle of the (011) plane is (b). , The inclination angle of each of the crystal grains including these angles is measured, and in this case, the crystal grains have Ti, carbon, and nitrogen at lattice points as described above. The crystal structure of the NaCl type face centered cubic crystal in which each of the constituent atoms is present, and based on the measured tilt angle obtained as a result. The distribution of lattice points (constituent atom sharing lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains is calculated, and the constituent atom sharing is calculated. The constitutive atom shared lattice point form in which N lattice points that do not share the constitutive atom between the lattice points (N is an even number of 2 or more on the crystal structure of the NaCl type face-centered cubic crystal) is expressed by ΣN + 1, and each ΣN + 1 When a constituent atomic shared lattice point distribution graph showing the distribution ratio of ΣN + 1 in the whole ΣN + 1 (however, the upper limit value is 28 due to frequency) is created, the highest peak exists in Σ3 in any TiCN layer, As shown in FIG. 7, the conventional TiCN layer shows a relatively low constituent atom sharing lattice distribution graph in which the distribution ratio of Σ3 is 30% or less, whereas the modified TiCN layer is shown in FIG. 6. As illustrated, Σ 3 shows a very high constituent atom shared lattice point distribution graph in which the distribution ratio of 3 is 60% or more, and this high distribution ratio of Σ3 is the content of TiCl ₄ and CH ₃ CN constituting the reaction gas, the content of Ar, and the atmospheric reaction Change with temperature.

(3) From the above results, the thickened modified α-type Al ₂ O ₃ layer showing an extremely high constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 60% or more is used as the upper layer of the hard coating layer. A coated cermet tool formed by vapor-depositing an average layer thickness of 2.5 to 15 μm with a modified TiCN layer showing a very high constituent atomic shared lattice point distribution graph having a distribution ratio of Σ3 of 60% or more is α Even if the type Al ₂ O ₃ layer is thickened to an average thickness of 16 to 30 μm, the above thick film is formed by the high temperature strength of the thickened modified α-type Al ₂ O ₃ layer and the modified TiCN layer. Compared to a coated cermet tool having a normal α-type Al ₂ O ₃ layer as the upper layer and the conventional TiCN layer as the lower layer and deposited with an average layer thickness of 2.5 to 15 μm, particularly in the cutting edge portion Excellent wear resistance with no chipping From becoming so, it is possible to stage a life extension of the service life.
The research results shown in (1) to (3) above were obtained.

This invention has been made based on the above research results, and a hard coating layer formed by vapor deposition on the surface of the tool base is provided.
(A) All formed by chemical vapor deposition, comprising one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, and having a total average layer thickness of 0.1 to 5 μm A lower layer comprising a Ti compound layer and a modified TiCN layer having an average layer thickness of 2.5 to 15 μm,
(B) an upper layer composed of a thickened modified α-type Al ₂ O ₃ layer having an average layer thickness of 16 to 30 μm;
The modified TiCN layer composed of the above (a) and (b), and the lower layer of (a),
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 are NaCl-type face-centered cubic crystals each having a constituent atom composed of Ti, carbon, and nitrogen at lattice points. A lattice point having a crystal structure, and 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 ( The distribution of the constituent atomic shared lattice points) is calculated, and N lattice points that do not share the constituent atoms between the constituent atomic shared lattice points (N is an even number of 2 or more on the crystal structure of the NaCl type face centered cubic crystal) Existing constituent atomic shared lattice point form is ΣN + 1 In the constituent atom sharing lattice distribution graph showing the distribution ratio of each ΣN + 1 in the whole ΣN + 1 (however, the upper limit value is 28 due to the frequency), the highest peak exists in Σ3, and the Σ3 Constituent atom shared lattice distribution graph in which the distribution ratio in the entire ΣN + 1 is 60% or more,
Further, the thickening-modified α-type Al ₂ O ₃ layer in (b) above is
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angles formed by the normal lines of the (0001) plane and the (10-10) plane, which are crystal planes of the above, are measured. In this case, the crystal grains are corundum type in which constituent atoms composed of Al and oxygen are present at lattice points. Based on the measured tilt angle obtained as a result of the hexagonal close-packed crystal structure, each of the constituent atoms forms one constituent atom between the crystal grains at the interface between adjacent crystal grains. The distribution of shared lattice points (constituent atom shared lattice points) is calculated, and there are N lattice points that do not share constituent atoms between the constituent atom shared lattice points (where N is the crystal structure of the corundum hexagonal close-packed crystal) Even number of 2 or more, but distribution frequency When the upper limit of N from the point is 28, the even number of 4, 8, 14, 24, and 26 does not exist.) When the existing constituent atom shared lattice point form is expressed as ΣN + 1, each ΣN + 1 is included in the entire ΣN + 1 In the constituent atom shared lattice point distribution graph showing the distribution ratio, a constituent atom shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio in the entire ΣN + 1 of Σ3 is 60% or more,
The thickened α-type Al ₂ O ₃ layer is characterized by a coated cermet tool that exhibits excellent chipping resistance.

In addition, the reason why the numerical values of the constituent layers of the hard coating layer of the coated cermet tool of the present invention are limited as described above will be described below.
(A) Lower layer adhesive Ti compound layer The adhesive Ti compound layer firmly adheres to both the tool substrate and the upper layer thickened modified α-type Al ₂ O ₃ layer and modified TiCN layer. Therefore, it has an effect of improving the adhesion of the hard coating layer to the tool substrate, but if the total average layer thickness is less than 0.1 μm, the desired excellent adhesion cannot be secured, while the adhesion Since the total average layer thickness up to 5 μm is sufficient, the total average layer thickness was determined to be 0.1 to 5 μm.

(B) Modified TiCN layer of lower layer The distribution ratio of Σ3 in the constituent atomic shared lattice point distribution graph of the modified TiCN layer is the content of TiCl ₄ and CH ₃ CN constituting the reaction gas and Ar as described above The amount and further the atmospheric reaction temperature can be adjusted to 60% or more. In this case, when the distribution ratio of Σ3 is less than 60%, the chipping does not occur in the hard coating layer by high-speed intermittent cutting, which is excellent. Since the effect of improving the high temperature strength cannot be ensured, the distribution ratio of Σ3 was 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 TiCN itself as described above. However, if the average layer thickness is less than 2.5 μm, it is desirable. However, if the average layer thickness exceeds 15 μm, thermoplastic deformation that causes uneven wear tends to occur and wear accelerates. Therefore, the average layer thickness was set to 2.5 to 15 μm.

(C) the distribution ratio of Σ3 in the atom sharing lattice point distribution graph of the thickening modified α type the Al ₂ O ₃ layer above thickening modified α-type Al ₂ O ₃ layer is the street reactive gas By adjusting the AlCl ₃ , CO ₂ , and HCl content ratios, and the atmospheric reaction pressure, it can be made 60% or more. In this case, if the distribution ratio of Σ3 is less than 60%, the average layer thickness is 16 When the film thickness is increased to ˜30 μm, chipping does not occur in the hard coating layer, and an excellent high-temperature strength improvement effect cannot be ensured. Therefore, the distribution ratio of Σ3 is determined to be 60% or more.
Further, the above-mentioned thickening modified α-type Al ₂ O ₃ layer contributes to the improvement of the wear resistance of the hard coating layer due to the excellent high temperature hardness and heat resistance of the Al ₂ O ₃ layer itself, but its average layer If the thickness is less than 16 μm, it is not possible to sufficiently satisfy the demand for thickening. On the other hand, if the average layer thickness exceeds 30 μm, chipping is likely to occur. It was determined to be 16 to 30 μm.

  For the purpose of identification before and after the use of the coated cermet tool, a TiN layer having a golden color tone may be vapor-deposited as the outermost surface layer of the hard coating layer, but the average layer thickness in this case May be 0.1 to 1 μm, 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. .

In the coated cermet tool of the present invention, the thickened modified α-type Al ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool has a very high constituent atom in which the distribution ratio of Σ3 is 60% or more as illustrated in FIG. Even if the shared lattice point distribution graph is shown and the average layer thickness is increased to a layer thickness of 16 to 30 μm, as shown in FIG. 4, as shown in FIG. Combined with the high-temperature strength of the modified TiCN layer showing the lattice distribution graph, it exhibits excellent chipping resistance, so long-term excellent wear resistance can be achieved by cutting various types of steel and cast iron. It is demonstrated over a long period of time, leading to a further increase in service life.

  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 are blended into the blending composition shown in Table 1, added with wax, ball milled in acetone for 32 hours, dried under reduced pressure, and pressed into a green compact of a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge portion was R: 0.06 mm honing By performing the processing, tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 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 32 hours, dried, and then 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 a standard / CNMG12041 chip shape were formed.

Next, on the surfaces of the tool bases A to F and the tool bases a to f, a normal chemical vapor deposition apparatus is used, and first, the lower layer of the hard coating layer is configured under the conditions shown in Tables 3 and 4. The adhesion Ti compound layer and the modified TiCN layers a to k are formed by vapor deposition with the combination shown in Table 5 and with a target layer thickness, and then the upper layer thickened modified α-type Al ₂ O ₃ layer ( The coated cermet tools 1 to 13 of the present invention were manufactured by vapor-depositing a) to (f) with the combinations and target layer thicknesses shown in Table 5 under the same conditions as shown in Table 4.

For the purpose of comparison, the lower layers of the hard coating layer are formed on the surfaces of the tool bases A to F and the tool bases a to f using the same ordinary chemical vapor deposition apparatus under the conditions shown in Tables 3 and 6. Conventional TiCN layers (a) to (i) and an adhesive Ti compound layer are formed by vapor deposition in the combinations shown in Table 7 and with a target layer thickness, and then the upper layer is made thicker usually α-type Al ₂ O Comparative coated cermet tools 1 to 13 were produced by vapor-depositing the _three layers (a) to (f) under the conditions shown in Table 6 and the combinations and target layer thicknesses shown in Table 7, respectively.

Subsequently, the modified TiCN layer and the conventional TiCN layer constituting the hard coating layers of the above-described coated cermet tools 1 to 13 of the present invention and the comparative coated cermet tools 1 to 13, and the thickened modified α-type Al ₂ O ₃ layer and For the thickened normal α-type Al ₂ O ₃ layer, a constituent atom sharing lattice point distribution graph was created using a field emission scanning electron microscope.
That is, the constituent atom sharing lattice point distribution graph shows the surface of the modified TiCN layer and the conventional TiCN layer, the thickened modified α-type Al ₂ O ₃ layer, and the thickened normal α-type Al ₂ O ₃ layer. Is set in a lens barrel of a field emission scanning electron microscope, and the surface polished surface is irradiated with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees and an irradiation current of 1 nA. Each of the crystal grains existing within the measurement range is irradiated with an electron backscatter diffraction image apparatus, and a 30 × 50 μm region is spaced at a spacing of 0.1 μm / step with respect to the normal line of the surface polished surface. Regarding the modified TiCN layer and the conventional TiCN layer, the (001) plane and (011) plane which are crystal planes of crystal grains, the thickened modified α-type Al ₂ O ₃ layer and the thickened normal α-type Al ₂ The O ₃ layer is the crystal plane of the crystal grain (000 1) Measure the tilt angles formed by the normals of the plane and (10-10) plane, and based on the measured tilt angles obtained as a result, each of the constituent atoms at the interface between adjacent crystal grains The distribution of lattice points that share one constituent atom between the crystal grains (constituent atom shared lattice points) is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (in this case, Regarding the modified TiCN layer and the conventional TiCN layer, N is an even number of 2 or more in the crystal structure of the NaCl type face centered cubic crystal, while the thickened modified α type Al ₂ O ₃ layer and the thickened normal α As for the type Al ₂ O ₃ layer, N is an even number of 2 or more due to the crystal structure of the corundum hexagonal close-packed crystal, but when the upper limit of N is 28 from the point of distribution frequency, 4, 8, 14, 24 , And the even number of 26 will not be present) If represents the child sharing lattice points form in .SIGMA.N + 1, each .SIGMA.N + 1 is created by obtaining a distribution ratio of total .SIGMA.N + 1.

In the various constituent atomic share lattice point distribution graphs obtained as a result, for the modified TiCN layer and the conventional TiCN layer, the distribution ratio of Σ3 in the entire ΣN + 1 consisting of all even numbers in the range of N from 2 to 28, For the thickened modified α-type Al ₂ O ₃ layer and the thickened normal α-type Al ₂ O ₃ layer, Σ3, Σ7, Σ11, Σ13, Σ17, Σ19, Σ21, Σ23, and Tables 5 and 7 show the distribution ratio of Σ3 in the entire ΣN + 1, which is the sum of the distribution ratios of Σ29.

In the above-mentioned various constituent atomic share lattice point distribution graphs, as shown in Tables 5 and 7, respectively, the modified TiCN layer and the thickened modified α-type Al ₂ O ₃ layer of the coated cermet tool of the present invention are both In contrast to the constituent atomic shared lattice distribution graph in which the distribution ratio of Σ3 is 60% or more, the conventional TiCN layer and the thickened normal α-type Al ₂ O ₃ layer of the comparative coated cermet tool are both Σ3 This shows a distribution graph of constituent atom shared lattice points with a distribution ratio of 30% or less.
6 shows a constituent atomic shared lattice point distribution graph of the modified TiCN layer of the coated cermet tool 8 of the present invention, and FIG. 7 shows a constituent atomic shared lattice point distribution graph of the conventional TiCN layer of the comparative coated cermet tool 8. FIG. 3 is a graph showing the distribution of constituent atomic shared lattice points of the thickened modified α-type Al ₂ O ₃ layer of the coated cermet tool 8 according to the present invention, and FIG. ₃ shows a constituent atomic shared lattice point distribution graph of a type Al ₂ O ₃ layer.

Further, for the above-described coated cermet tools 1 to 13 and comparative coated cermet tools 1 to 13, 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 were composed of a TiCN layer and an adhesive Ti compound layer having substantially the same composition as the target composition, and a thickened α-type Al ₂ O ₃ layer. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated cermet tools was measured using a scanning electron microscope (same longitudinal section measurement), the average layer thickness (substantially the same as the target layer thickness) Average value of 5-point measurement) was shown.

Next, with the various coated cermet tools described above, the present coated cermet tools 1 to 13 and the comparative coated cermet tools 1 to 13 in a state where all of the various coated cermet tools are screwed to the tip of the tool steel tool with a fixing jig.
Work material: JIS / SCM420 round bar,
Cutting speed: 240 m / min,
Cutting depth: 1.8mm,
Feed: 0.3mm / rev,
Cutting time: 20 minutes,
Dry continuous cutting test of alloy steel under the following conditions (referred to as cutting condition A),
Work material: JIS-S35C lengthwise equal length 4 round fluted round bars,
Cutting speed: 250 m / min,
Incision: 1.5mm,
Feed: 0.25mm / rev,
Cutting time: 20 minutes,
Dry interrupted cutting test of carbon steel under the conditions (referred to as cutting condition B),
Work material: JIS / FC350 round bar,
Cutting speed: 280 m / min,
Cutting depth: 1.2mm,
Feed: 0.3mm / rev,
Cutting time: 20 minutes,
The dry continuous cutting test of cast iron was performed under the above conditions (referred to as cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 8.

From the results shown in Tables 5 and 7 and Table 8, the coated cermet tools 1 to 13 of the present invention all have a constituent atomic shared lattice in which one of the lower layers of the hard coating layer has a distribution ratio of Σ3 of 60% or more. A thickened modified α-type Al ₂ O ₃ layer composed of a modified TiCN layer showing a point distribution graph, and the upper layer also showing a constituent atomic shared lattice point distribution graph in which the distribution ratio of Σ3 is 60% or more As a result, the modified TiCN layer and the thickened modified α-type Al ₂ O ₃ layer are further improved in high-temperature strength, so that the α-type Al ₂ O ₃ layer has an average layer thickness. Even when the layer thickness is increased to 16 to 30 μm, chipping caused by the thickening of the α-type Al ₂ O ₃ layer is eliminated in cutting of steel and cast iron, and excellent wear resistance over a long period of time. It is possible to extend the service life, while the hard coating layer In comparison coated cermet tools 1 to 13, also the distribution ratio of Σ3 is composed of TiCN layer and thicker usual α-type the Al ₂ O ₃ layer prior to showing the atom sharing lattice point distribution graph of the 30%, both It is apparent that chipping occurs at the cutting edge 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 according to the present invention can be used for various steels even when the α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer, has an average layer thickness of 16 to 30 μm. It shows excellent chipping resistance in cutting work such as cast iron and cast iron, exhibits excellent wear resistance over a long period of time, and can extend the service life. It can cope with labor saving, energy saving and cost reduction of processing sufficiently satisfactorily.

It is a schematic diagram showing the measurement mode of the inclination angle of the crystal grains (0001) plane and (10-10) plane in the α-type the Al ₂ O ₃ layer. FIG. 3 is a schematic diagram showing unit forms of constituent atomic shared lattice points at the interface between adjacent crystal grains, where (a) shows Σ3, (b) shows Σ7 (c) and Σ11 unit forms. . 6 is a constituent atomic shared lattice point distribution graph of a thickened modified α-type Al ₂ O ₃ layer of the coated cermet tool 8 of the present invention. 6 is a graph showing the distribution of constituent atomic shared lattice points of a thickened normal α-type Al ₂ O ₃ layer of a comparative coated cermet tool 8. 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 which comprises the lower layer of a hard coating layer. 4 is a constituent atomic shared lattice point distribution graph of a modified TiCN layer constituting a lower layer of a hard coating layer of a coated cermet tool 8 of the present invention. 5 is a constituent atomic shared lattice point distribution graph of a conventional TiCN layer constituting a lower layer of a hard coating layer of a comparative coated cermet tool 8. It is a schematic diagram which shows the crystal structure of the NaCl type face centered cubic crystal which the TiCN layer which comprises the lower layer of a hard coating layer has. It is a schematic diagram showing an atomic arrangement of a unit cell of a corundum type hexagonal close-packed crystal constituting an α-type Al ₂ O ₃ layer.

Claims (1)

A hard coating layer formed by vapor deposition on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) All are formed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer formed by chemical vapor deposition, and 0.1 to 5 μm An adhesive Ti compound layer having a total average layer thickness, and a lower layer comprising a modified titanium carbonitride layer having an average layer thickness of 2.5 to 15 μm,
(B) an upper layer composed of a thickened modified α-type aluminum oxide layer having an average layer thickness of 16 to 30 μm and having an α-type crystal structure in a state of chemical vapor deposition;
The modified titanium carbonitride layer in the lower layer of the above (a) is composed of the above (a) and (b),
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 are NaCl-type face-centered cubic crystals each having a constituent atom composed of Ti, carbon, and nitrogen at lattice points. A lattice point having a crystal structure, and 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 ( The distribution of the constituent atomic shared lattice points) is calculated, and N lattice points that do not share the constituent atoms between the constituent atomic shared lattice points (N is an even number of 2 or more on the crystal structure of the NaCl type face centered cubic crystal) Existing constituent atomic shared lattice point form is ΣN + 1 In the constituent atom sharing lattice distribution graph showing the distribution ratio of each ΣN + 1 in the whole ΣN + 1 (however, the upper limit value is 28 due to the frequency), the highest peak exists in Σ3, and the Σ3 Constituent atom shared lattice distribution graph in which the distribution ratio in the entire ΣN + 1 is 60% or more,
Furthermore, the thickening-modified α-type aluminum oxide layer of (b) above is
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angles formed by the normal lines of the (0001) plane and the (10-10) plane, which are crystal planes of the above, are measured. In this case, the crystal grains are corundum type in which constituent atoms composed of Al and oxygen are present at lattice points. Based on the measured tilt angle obtained as a result of the hexagonal close-packed crystal structure, each of the constituent atoms forms one constituent atom between the crystal grains at the interface between adjacent crystal grains. The distribution of shared lattice points (constituent atom shared lattice points) is calculated, and there are N lattice points that do not share constituent atoms between the constituent atom shared lattice points (where N is the crystal structure of the corundum hexagonal close-packed crystal) Even number of 2 or more, but distribution frequency When the upper limit of N from the point is 28, the even number of 4, 8, 14, 24, and 26 does not exist.) When the existing constituent atom shared lattice point form is expressed as ΣN + 1, each ΣN + 1 is included in the entire ΣN + 1 In the constituent atom shared lattice point distribution graph showing the distribution ratio, a constituent atom shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio in the entire ΣN + 1 of Σ3 is 60% or more,
A surface-coated cermet cutting tool that exhibits excellent chipping resistance with a thickened α-type aluminum oxide layer.

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