JP4730522B2 - 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 the above (a) and (b). It is well known to be used.
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) When forming an α-type Al ₂ O ₃ layer as a hard coating layer on the surface of the tool base by vapor deposition, for example, prior to the vapor deposition formation,
Reaction gas composition:% by volume, AlCl ₃ : 3 to 10%, CO ₂ : 0.5 to 3%, C ₂ H ₄ : 0.01 to 0.3%, H ₂ : remaining,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 3 to 13 kPa,
Under the low temperature conditions, Al ₂ O ₃ nuclei are formed on the surface of the lower Ti compound layer. In this case, the Al ₂ O ₃ nuclei are Al ₂ O ₃ nuclei thin films having an average layer thickness of 30 to 200 nm. Subsequently, the reaction atmosphere is changed to a hydrogen atmosphere at a pressure of 3 to 13 kPa, and the reaction atmosphere temperature is raised to 1100 to 1200 ° C., and the Al ₂ O ₃ core thin film is heated. When the α-type Al ₂ O ₃ layer as the hard coating layer is formed to a layer thickness of 18 to 28 μm exceeding the average layer thickness of 15 μm under normal conditions, the resulting heat-treated Al ₂ O ₃ core thin film In the thickened α-type Al ₂ O ₃ layer (hereinafter referred to as “thickened modified α-type Al ₂ O ₃ layer”) formed by vapor deposition on the thick film, the average layer thickness is 18 to 28 μm. phased Nevertheless, Al ₂ O ₃ grain coarsening significantly suppressed, and the layer itself Since also those held denseness, decrease in high temperature strength been suppressed, to become possible that enhanced rather.

(1-b) Without forming the thickening-modified α-type Al ₂ O ₃ layer and the heat-treated Al ₂ O ₃ core thin film, the surface of the Ti compound layer as the lower layer is usually formed A field emission scanning electron microscope for a thickened α-type Al ₂ O ₃ layer (hereinafter referred to as a thickened normal α-type Al ₂ O ₃ layer) deposited with an average layer thickness of 18 to 28 μm under the above conditions As shown in the schematic explanatory diagrams in FIGS. 4A and 4B, an electron beam is individually applied to each α-type Al ₂ O ₃ crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface. Irradiate and use an electron backscatter diffraction image apparatus, and a predetermined area is spaced at a distance of 0.1 μm / step, and the normal line of the (0001) plane which is the crystal plane of the crystal grain with respect to the normal line of the polished surface Is measured, and the measured inclination angle within the range of 0 to 45 degrees out of the measured inclination angles is a pitch of 0.25 degrees. As with partitioning, if you create a tilt angle frequency distribution graph obtained by aggregating the frequencies present in each segment, the thickened normal α-type Al ₂ O ₃ layer is illustrated in FIG. 6 for each, While the distribution of the measured inclination angle of the (0001) plane shows an unbiased inclination angle number distribution graph within the range of 0 to 45 degrees, the thickness formed by vapor deposition on the heat-treated Al ₂ O ₃ nuclear thin film In the film-modified α-type Al ₂ O ₃ layer, as illustrated in FIG. 5, a sharp maximum peak appears at a specific position in the tilt angle section, and this sharp maximum peak is the same as that of the Al ₂ O ₃ core thin film. By changing the average layer thickness, the position that appears in the tilt angle section on the horizontal axis of the graph changes.

(1-c) According to the test results, in the above-mentioned thickened modified α-type Al ₂ O ₃ layer, when the average layer thickness of the Al ₂ O ₃ core thin film is 30 to 200 nm, the sharpest maximum The peak appears in the range of 1.25 to 10.00 degrees of the tilt angle section, and the total frequency existing in the range of 0 to 10 degrees is 45 to 70 % of the total frequency in the tilt angle frequency distribution graph. To show the distribution graph of the number of inclination angles that occupy the ratio.

(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: 0.6 ~1%} , CH 3 CN: 0.3~ 1.4%, C 2 H 4: 1.6 ~3%, N 2: 15 ~30% , H ₂ : remaining,
Reaction atmosphere temperature: 700 to 750 ° C.
Reaction atmosphere pressure: 25-40 kPa,
And an average layer thickness of 2.5 to 15 μm, the resulting TiCN layer (hereinafter referred to as “modified TiCN layer”) has a higher temperature than the conventional TiCN layer. To be improved in strength.

(2-b) About the above conventional TiCN layer and modified TiCN layer, using a field emission scanning electron microscope, as shown in the schematic explanatory diagrams of FIGS. 1A and 1B, the measurement range of the surface polished surface Each crystal grain having a cubic crystal lattice existing therein is irradiated with an electron beam, and an electron backscatter diffraction image apparatus is used, and a predetermined region is spaced 0.1 μm / step from the normal line of the surface polished surface. Then, the inclination angle formed by the normal line of the {110} plane which is the crystal plane of the crystal grain is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is 0.25 degrees. When the slope angle number distribution graph formed by dividing the pitches and counting the frequencies existing in each section is created, the conventional TiCN layer has a measured slope of the {110} plane as illustrated in FIG. Unbiased inclination angle number distribution in the range of angle distribution of 0 to 45 degrees In contrast to the rough, the modified TiCN layer, as illustrated in FIG. 2, shows a sharp maximum peak at a specific position in the tilt angle section, and this sharp maximum peak is a constituent component in the reaction gas. The position appearing in the tilt angle section of the horizontal axis of the graph changes depending on the content ratio of C ₂ H ₄ added as.

(2-c) As described above, the modified TiCN layer is newly added with C ₂ H ₄ in the reaction gas at a ratio of 1.6 to 3%, while the content ratio of TiCl _{4 in} the reaction gas is as follows. Is formed under the condition that the reaction atmosphere temperature is relatively low as 0.6 to 1%, the reaction atmosphere temperature is relatively low as 700 to 750 ° C., and the reaction atmosphere pressure is relatively high as 25 to 40 kPa. In the tilt angle distribution graph, the modified TiCN layer has a sharp maximum peak in the range of 0.75 to 9.25 degrees of the tilt angle section and in the range of 0 to 10 degrees. total power is, but exhibits a tilt angle frequency distribution graph in a proportion of 56-75% of the total power at the inclination angle frequency distribution graph, in this case, according to the test results, C ₂ H in the reaction gas content of ₄ is less than 1.6% , Even if higher than 3% when the tilt angle segment of appearance of the maximum peak deviates from the range of 0.75 to 9.25 degrees occurs, also or reaction atmosphere temperature exceeds the 750 ° C., or the reaction If the atmospheric pressure is less than 25 kPa, the total ratio of the frequencies existing in the range of 0 to 10 degrees may be less than 56 % of the entire frequencies in the inclination angle frequency distribution graph. In any case, the TiCN layer If the reaction atmosphere temperature is less than 700 ° C. or the reaction atmosphere pressure exceeds 40 kPa, the deposition rate of the layer is remarkably reduced, and the cost is low. Not undesirable.

(3) From the above results, in the inclination angle number distribution graph, the highest peak of the inclination angle section appears in the range of the measured inclination angle distribution of the (0001) plane within the range of 1.25 to 10.00 degrees, and 0 to A thickening-modified α-type Al ₂ O ₃ layer having a power ratio of 45 to 70 % in the range of 10 degrees is used as the upper layer of the hard coating layer, and similarly, the measured inclination angle of the {110} plane Modified TiCN layer in which the highest peak of the tilt angle section appears in the range of 0.75 to 9.25 degrees and the frequency ratio existing in the range of 0 to 10 degrees accounts for 56 to 75% The coated cermet tool formed by vapor deposition with an average layer thickness of 2.5 to 15 μm as the lower layer is the same even if the α-type Al ₂ O ₃ layer is increased to an average layer thickness of 18 to 28 μm. the high temperature strength which includes the forming a film reformed α-type the Al ₂ O ₃ layer and reforming TiCN layer, the thickness The usual α-type the Al ₂ O ₃ layer as an upper layer, and the conventional TiCN layer as compared with the coated cermet tool formed deposited with an average layer thickness of 2.5~15μm as the lower layer, particularly the cutting edge It will be possible to prolong the service life because it will exhibit even better wear resistance without chipping.
The research results shown in (1) to (3) above were obtained.

The present invention was made based on the above research results, and a hard coating layer formed by vapor deposition on the surface of a tool base composed of a WC-based cemented carbide or TiCN-based cermet,
(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 18 to 28 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 having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and an electron backscatter diffraction image apparatus is used to set a predetermined area to 0.1 μm. The inclination angle formed by the normal line of the {110} plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line of the surface polished surface at an interval of / step. In the inclination angle number distribution graph obtained by dividing the measured inclination angles within the range of degrees into pitches of 0.25 degrees and totaling the frequencies existing in the respective sections, 0.75 to 9.25 degrees Inclination angle number distribution in which the highest peak exists in the inclination angle section within the range, and the sum of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 56 to 75% of the entire frequency in the inclination angle frequency distribution graph Graph,
Further, the thickening-modified α-type Al ₂ O ₃ layer in (b) above is
In the state of chemical vapor deposition, it has an α-type crystal structure, and a field emission scanning electron microscope is used to irradiate individual crystal grains having a hexagonal crystal lattice existing within the measurement range of the surface polished surface with an electron beam. Then, using the electron backscatter diffraction image apparatus, the normal of the (0001) plane , which is the crystal plane of the crystal grain, is made with respect to the normal of the surface-polished surface in a predetermined region at an interval of 0.1 μm / step. The inclination angle is measured, and among the measurement inclination angles, the measurement inclination angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees, and the frequencies existing in each division are totaled. In the inclination angle distribution graph, the highest peak exists in the inclination angle section in the range of 1.25 to 10.00 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is the inclination angle distribution graph. accounts for 45-70% of the total power in the Oblique angle frequency distribution graph,
The hard coating 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 As described above, by setting the content ratio of C ₂ H ₄ which is a component of the reaction gas to 1.6 to 3%, an inclination of 0.75 to 9.25 degrees The maximum peak of the measured inclination angle appears in the angular section range, the reaction atmosphere temperature is 700 to 750 ° C., and the reaction atmosphere pressure is 25 to 40 kPa, so that the frequency existing in the inclination angle section of 0 to 10 degrees A modified TiCN layer showing an inclination angle number distribution graph in which the total ratio is 56 to 75% of the entire frequency in the inclination angle number distribution graph is formed, and as a result, the modified TiCN layer has a much higher temperature. However, if the average layer thickness is less than 2.5 μm, the hard coating layer cannot have the desired high-temperature strength, whereas if the average layer thickness exceeds 15 μm, Departure Thermal plastic deformation due to heat is increased beyond the allowable range, since the crack results thickening modified α-type Al ₂ O ₃ layer which is the upper layer is likely to occur, the average layer thickness 2.5 It was defined as ˜15 μm.

(C) Thickened modified α-type Al ₂ O ₃ layer As described above, the thickened modified α-type Al ₂ O ₃ layer formed on the heat-treated Al ₂ O ₃ core thin film includes Al ₂ O ₃ It improves the wear resistance of the hard coating layer by its excellent high-temperature hardness and heat resistance, and also has an improved high-temperature strength compared to the thickened normal α-type Al ₂ O ₃ layer. Therefore, there is an effect of suppressing the occurrence of chipping in the hard coating layer that has been thickened, but if the average layer thickness is less than 18 μm, it cannot sufficiently satisfy the demand for thickening, On the other hand, if the average layer thickness exceeds 28 μm and becomes too thick, chipping tends to occur. Therefore, the average layer thickness was determined to be 18 to 28 μm.

(C) Heat-treated Al ₂ O ₃ core thin film For the thickened modified α-type Al ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool of the present invention, the inclination angle showing the highest peak in the inclination angle number distribution graph There is a close relationship between the classification and the average layer thickness of the heat-treated Al ₂ O ₃ core thin film. In this case, according to the test results, the average layer thickness of the heat-treated Al ₂ O ₃ core thin film is 30 to 200 nm. The maximum peak appears in the inclination angle section within the range of 1.25 to 10.00 degrees, and the total of the frequencies existing within the range of 0 to 10 degrees is represented in the inclination angle number distribution graph. An inclination angle frequency distribution graph occupying a ratio of 45 to 70% of the entire frequency is shown. Therefore, when the average layer thickness of the heat-treated Al ₂ O ₃ core thin film is less than 30 nm, the upper Thickened reformed α-type A Peak height appearing in the range of 1.25 to 10.00 degree inclination angle frequency distribution graph of the ₂ O ₃ layer is insufficient, i.e., the total proportion of the frequencies present in the range of 0 degrees, tilt In some cases, the frequency is less than 45% of the total frequency in the angle distribution graph. In this case, as described above, the high-temperature strength of the thickening-modified α-type Al ₂ O ₃ layer is determined by the hard coating of the conventional coated cermet tool. α-type the Al ₂ O ₃ layer constituting the upper layer of the layer, i.e., can not be held the average layer thickness-temperature strength equivalent to that of the high temperature strength comprising the α-type the Al ₂ O ₃ layer having a 1 to 15 m, As a result, the chipping resistance is lowered. On the other hand, when the average layer thickness exceeds 200 nm, the inclination angle section where the highest peak appears is out of the range of 1.25 to 10.00 degrees. hot strength of thickening modified α type the Al ₂ O ₃ layer Since the decrease in can not be avoided, the Al ₂ O ₃ Average layer thickness of 30 to 200 nm nuclear thin film formed on the Ti compound layer as the lower layer of the hard coating layer, since preferably has the same 30~150nm is there.

  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 0.1-1 μm may be sufficient, 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 thereof is inclined within the range of 1.25 to 10.00 degrees as illustrated in FIG. shows an inclination angle frequency distribution graph the highest peak in the angular segment appears, even thickened this average layer thickness in a layer thickness of 18 to 28 [mu] m, as illustrated in FIG. 2, from 0.75 to 9.25 Combined with the high-temperature strength of the modified TiCN layer, which shows an inclination angle number distribution graph in which the highest peak appears in the inclination angle range within the range of degrees, it exhibits excellent chipping resistance. In the cutting of cast iron, excellent wear resistance is demonstrated over a long period of time, and the service life can be further extended.

  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, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder each having an average particle diameter of 1 to 3 μm are prepared as raw material powders. The raw material powder was blended in the blending composition shown in Table 1, added with wax, ball mill mixed in acetone for 32 hours, dried under reduced pressure, and then pressed into a green compact of a predetermined shape at a pressure of 98 MPa. The green compact is vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. After sintering, the cutting edge is subjected to a honing process of R: 0.05 mm. As a result, tool bases A and C to F made of a WC-based cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 were produced.

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 b and df made of TiCN base cermet having a standard / CNMG12041 chip shape were formed.

Next, on the surfaces of these tool bases A, C to F and tool bases b and df , a normal chemical vapor deposition apparatus is used, and the lower layer of the hard coating layer under the conditions shown in Tables 3 and 4 As the modified TiCN layer and the adhesive Ti compound layer, the combination shown in Table 5 and the target layer thickness are formed by vapor deposition.
Reaction gas composition: volume%, AlCl ₃ : 6.5%, CO ₂ : 1.6%, C ₂ H ₄ : 0.13%, H ₂ : remaining,
Reaction atmosphere temperature: 820 ° C.
Reaction atmosphere pressure: 8 kPa,
Time: 5-80 minutes
After forming an Al ₂ O ₃ nucleus thin film having the target layer thickness shown in Table 6 under the low temperature conditions (the relationship between the layer thickness of the Al ₂ O ₃ nucleus thin film and the processing time has been investigated in advance by experiments), the reaction The atmosphere was changed to a hydrogen atmosphere at a pressure of 8 kPa, and the Al ₂ O ₃ core thin film was subjected to heat treatment under the conditions where the reaction atmosphere temperature was raised to 1135 ° C., and then under the same conditions as shown in Table 3, The coated cermet tools 1 to 10 of the present invention were manufactured by depositing a thickened modified α-type Al ₂ O ₃ layer having a target layer thickness shown in Table 6 as an upper layer of the hard coating layer.

Also, for comparison purposes, the surfaces of the above-mentioned tool bases A, C to F and tool bases b and df are similarly coated with a hard coating under the conditions shown in Tables 3 and 7 using the same chemical vapor deposition apparatus. A conventional TiCN layer and an adhesive Ti compound layer are formed as a lower layer of the layer by vapor deposition in the combination shown in Table 8 and with a target layer thickness, and then also shown in Table 9 under the same conditions as shown in Table 3. Comparative coating cermet tools 1 to 10 were produced by depositing a normal α-type Al ₂ O ₃ layer as the upper layer of the hard coating layer.

Subsequently, the modified TiCN layer and the conventional TiCN layer constituting the hard coating layer of the present invention coated cermet tools 1 to 10 and the comparative coated cermet tools 1 to 10 , and the thickened modified α-type Al ₂ O ₃ layer and For the thickened normal α-type Al ₂ O ₃ layer, an inclination angle number distribution graph was prepared using a field emission scanning electron microscope.
That is, the slope angle distribution graph shows the polished surfaces of the modified TiCN layer and the conventional TiCN layer, and the thickened modified α-type Al ₂ O ₃ layer and the thickened normal α-type Al ₂ O ₃ layer. The surface polished surface was set in a lens barrel of a field emission scanning electron microscope in the state of a plane, and the surface polished surface was measured with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees on the polished surface with an irradiation current of 1 nA. The crystal grains having a cubic crystal lattice (TiCN layer) and a hexagonal crystal lattice (α-type Al ₂ O ₃ layer) existing in the range are individually irradiated, and an electron backscatter diffraction image apparatus is used to measure 30 × 50 μm. For the modified TiCN layer and the conventional TiCN layer with respect to the normal of the surface polished surface at an interval of 0.1 μm / step, the {110} plane which is the crystal plane of the crystal grain, the thickening modification quality α type the Al ₂ O ₃ layer and a thick film normally α type A ₂ for O ₃ layer was measured tilt angles respectively formed by the normal of a crystal plane of the crystal grains (0001) plane, on the basis of the measurement result, of the measurement inclination angle within the range of 0 to 45 degrees The measured inclination angle is divided for each pitch of 0.25 degrees, and the frequency existing in each section is totaled.

In the gradient angle distribution graphs of the various modified TiCN layers and conventional TiCN layers obtained as a result, the {110} plane has the highest peak, and the tilt angle within the range of 0 to 10 degrees. Tables 5 and 8 show the ratio of the existing tilt angle number to the tilt angle number distribution graph as a whole. Further, various thickened modified α-type Al ₂ O ₃ layers and thickened normal α-type In the inclination angle distribution graph of the Al ₂ O ₃ layer, the inclination angle distribution of the inclination angle number existing in the inclination angle section where the (0001) plane has the highest peak and in the inclination angle section in the range of 0 to 10 degrees. Tables 6 and 9 show the ratio of the entire graph to the number of inclination angles.

In the above-mentioned various inclination angle number distribution graphs, as shown in Tables 5 and 6, all of the modified TiCN layers of the coated cermet tools 1 to 10 of the present invention have a measured inclination angle distribution of the {110} plane of 0. An inclination angle in which the highest peak appears in the inclination angle section in the range of .75 to 9.25 degrees and the ratio of the number of inclination angles existing in the inclination angle section in the range of 0 to 10 degrees is 56 to 75%. 2 shows a number distribution graph, and all the (0001) planes of the thickened modified α-type Al ₂ O ₃ layer formed on the heat-treated Al ₂ O ₃ core thin film of the coated cermet tools 1 to 10 of the present invention. The highest peak appears in the inclination angle section in the range of the measured inclination angle of 1.25 to 10.00 degrees, and the ratio of the number of inclination angles existing in the inclination angle section in the range of 0 to 10 degrees is whereas showing the inclination angle frequency distribution graph is 45 to 70% As shown in Tables 8 and 9, the conventional TiCN layer of the comparative coated cermet tool 1-10 are both unbiased manner in within range distribution of 0 to 45 degrees measured inclination angle of the {110} plane, the highest peak The inclination angle number distribution graph in which the ratio of the inclination angle number existing in the inclination angle section in the range of 0 to 10 degrees is 30% or less is shown, and the thickness of the comparative coated cermet tools 1 to 10 All of the normal α-type Al ₂ O ₃ layers formed into a film are unbiased within the range of the measured inclination angle of the (0001) plane within the range of 0 to 45 degrees, the highest peak does not exist, and the range of 0 to 10 degrees. The inclination angle number distribution graph in which the ratio of the inclination angle numbers existing in the inclination angle section is 30% or less was also shown.
2 is an inclination angle distribution graph of the modified TiCN layer of the coated cermet tool 4 of the present invention, FIG. 3 is an inclination angle distribution graph of the conventional TiCN layer of the comparative coated cermet tool 4 , and FIG. thickening modified α type the Al ₂ O ₃ layer inclination angle frequency distribution graph of the coated cermet tool 4, 6, the inclination angle frequency distribution of the thickened normal α type the Al ₂ O ₃ layer of the comparative coated cermet tool 4 Each graph is shown.

Further, regarding the above-described coated cermet tools 1 to 10 and comparative coated cermet tools 1 to 10 , the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analysis device When the longitudinal section was observed), it was confirmed that both the former and the latter were composed of a TiCN layer and a Ti compound layer having substantially the same composition as the target composition, and an 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 10 and comparative coated cermet tools 1 to 10 in a state where all the above-mentioned various coated cermet tools are screwed to the tip of the tool steel tool with a fixing jig.
Work material: JIS / SCM432 round bar,
Cutting speed: 230 m / min,
Cutting depth: 2mm,
Feed: 0.25mm / rev,
Cutting time: 24 minutes
Dry continuous cutting test of alloy steel under the following conditions (referred to as cutting condition A),
Work material: JIS · S33C lengthwise equal four round grooved round bars,
Cutting speed: 250 m / min,
Cutting depth: 2.2mm,
Feed: 0.3mm / rev,
Cutting time: 24 minutes
Dry interrupted cutting test of carbon steel under the conditions (referred to as cutting condition B),
Work material: JIS / FCD350 round bar,
Cutting speed: 220 m / min,
Cutting depth: 2.2mm,
Feed: 0.25mm / rev,
Cutting time: 24 minutes
A dry continuous cutting test of ductile 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 10.

From the results shown in Tables 5 to 10, in the coated cermet tools 1 to 10 of the present invention, one of the lower layers of the hard coating layer has an inclination angle of {110} plane of 0.75 to 9.25. Modified TiCN layer showing an inclination angle distribution graph showing the highest peak in the inclination angle section within the range of degrees and a total proportion of the frequencies existing in the inclination angle section range of 0 to 10 degrees occupying 56 to 75 % In addition, the upper layer has the highest peak in the inclination angle section with the inclination angle of (0001) plane in the range of 1.25 to 10.00 degrees, and exists in the range of 0 to 10 degrees. And a thickened modified α-type Al ₂ O ₃ layer showing an inclination angle frequency distribution graph in which the total frequency ratio is 45 to 70%, and as a result, the hard coating layer has a very high temperature strength. Therefore, the α-type Al ₂ O ₃ layer has an average layer thickness of 18 to Even when the layer thickness is increased to 28 μm, the chipping caused by the thickening of the α-type Al ₂ O ₃ layer is eliminated in the cutting of steel and cast iron, and excellent wear resistance is achieved over a long period of time. As shown in the figure, it is possible to extend the service life, whereas one of the lower layers of the hard coating layer is unbiased within the range of the measured inclination angle of the {110} plane in the range of 0 to 45 degrees. In the conventional TiCN layer showing an inclination angle number distribution graph where the highest peak does not exist, and the upper layer is unbiased within the range of the measured inclination angle of the (0001) plane within a range of 0 to 45 degrees. In the comparative coated cermet tools 1 to 10 composed of a thickened normal α-type Al ₂ O ₃ layer showing an inclination angle number distribution graph in which the highest peak does not exist, all are caused by insufficient high-temperature strength of the hard coating layer Chipping occurs at the cutting edge and the service life is reached in a relatively short time It is clear.

As described above, the coated cermet tool of the present invention can be used in various ways even if the α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer, has an average layer thickness of 18 to 28 μm. In cutting work such as steel and cast iron, it exhibits excellent chipping resistance, exhibits excellent wear resistance over a long period of time, and can extend the service life. It can fully satisfy the labor-saving and energy-saving of cutting and cost reduction.

It is a schematic explanatory drawing which shows the measurement range of the inclination angle of the {110} plane of the crystal grain in the various TiCN layers which comprise a hard coating layer. It is an inclination angle number distribution graph of the {110} plane of the modified TiCN layer constituting the lower layer of the hard coating layer of the coated cermet tool 4 of the present invention. 6 is a graph showing the inclination angle number distribution of the {110} plane of conventional TiCN constituting the lower layer of the hard coating layer of the comparative coated cermet tool 4 . It is a schematic diagram illustrating a measurement range of the inclination angle of the crystal grains (0001) plane in various α type the Al ₂ O ₃ layer constituting the upper layer of the hard coating layer. It is an inclination angle number distribution graph of the (0001) plane of the thickening modified α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the coated cermet tool 4 of the present invention. 6 is a graph showing the distribution of the number of inclination angles of the (0001) plane of the thickened normal α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the comparative coated cermet tool 4 .

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 comprising a thickened modified α-type aluminum oxide layer having an average layer thickness of 18 to 28 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 having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and an electron backscatter diffraction image apparatus is used to set a predetermined area to 0.1 μm. The inclination angle formed by the normal line of the {110} plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line of the surface polished surface at an interval of / step. In the inclination angle number distribution graph obtained by dividing the measured inclination angles within the range of degrees into pitches of 0.25 degrees and totaling the frequencies existing in the respective sections, 0.75 to 9.25 degrees Inclination angle number distribution in which the highest peak exists in the inclination angle section within the range, and the sum of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 56 to 75% of the entire frequency in the inclination angle frequency distribution graph Graph,
Furthermore, the thickening-modified α-type aluminum oxide layer of (b) above is
Using a field emission scanning electron microscope, irradiate an electron beam to each crystal grain having a hexagonal crystal lattice existing in the measurement range of the surface polished surface, and use an electron backscatter diffraction image apparatus to set a predetermined area to 0.1 μm. The inclination angle formed by the normal line of the (0001) plane , which is the crystal plane of the crystal grain, is measured with respect to the normal line of the surface-polished surface at an interval of / step. In the inclination angle number distribution graph obtained by dividing the measured inclination angles within the range of degrees into pitches of 0.25 degrees and totaling the frequencies existing in the respective sections, 1.25 to 10.00 degrees Inclination angle distribution in which the highest peak exists in the inclination angle section within the range, and the sum of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 45 to 70% of the entire frequency in the inclination angle distribution graph Graph,
A surface-coated cermet cutting tool that exhibits excellent chipping resistance with a thickened α-type aluminum oxide layer.

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