JP2009166193A - Surface coated cutting tool having hard coating layer exhibiting excellent chipping resistance in high-speed intermittent cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool having hard coating layer exhibiting superior chipping resistance and wear resistance in high-speed intermittent cutting in which high heat is generated and impact is applied to a cutting blade. <P>SOLUTION: In this surface coated cutting tool, the following layers are formed on the surface of a tool base body. A modified Ti based carbonitride layer having a close adhesive Ti compound layer and a longitudinal growth crystal structure is formed as a lower layer, and a hard coating layer made of Al<SB>2</SB>O<SB>3</SB>layer is formed as an upper layer. The modified Ti based carbonitride layer shows crystal orientation such that in the case of measuring an angle of inclination made by a normal of ä112} face and a normal of ä110} face, which are crystal planes of a crystal grain to a normal of a surface polishing face, by applying electron beams to individual crystal grains having cubic crystal lattice, which exist within the measuring range of the surface polishing face using a field emission type scanning electron microscope, and obtaining the total area A and the total area B of the respective crystal grains whose ä112} face and ä110} face have inclination angles in the range of 0-10 degrees to the normal of the surface polishing face, A/B is 2-9. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention is particularly suitable for high-speed interrupted cutting that involves high heat generation, such as steel and cast iron, and an impact load is applied to the cutting edge, and has a hard coating layer that exhibits excellent chipping resistance. The present invention relates to a cutting tool (hereinafter referred to as a coated tool).

Conventionally, on the surface of a tool base made of 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 TiN layer formed by chemical vapor deposition, a TiCN layer, a first adhesion layer having an average layer thickness of 0.1 to 1 μm, and chemical vapor deposition formed, and a Zr content of 0.3 to Ti and Zr carbonitride (hereinafter referred to as conventional TiZrCN) layer having an average layer thickness of 50 to 15% by mass and 2.5 to 15 μm,
(B) a second adhesion layer composed of a TiCO layer and a TiCNO layer as an intermediate layer and having an average layer thickness of 0.1 to 1 μm;
(C) A high-temperature hard layer made of a chemical vapor deposited Al ₂ O ₃ layer and having an average layer thickness of 1 to 15 μm as an upper layer,
A coated tool (hereinafter referred to as a conventional coated tool) formed by forming a hard coating layer composed of the above (a) to (c) is known, and this coated tool is a continuous material such as various steels and cast irons. It is known that it has excellent film adhesion and wear resistance in cutting.
JP 2001-11632 A

  In recent years, there has been a remarkable improvement in the performance of cutting devices. On the other hand, there are strong demands for labor saving and energy saving and further cost reduction for cutting, and with this, cutting has been on the trend of higher speed. In conventional coated tools, the lower layer of the coated tool has a predetermined high-temperature strength, and the upper layer has a predetermined high-temperature hardness and heat resistance, so when this is used under normal cutting conditions Although no particular problem occurs, especially when this is used for high-speed intermittent cutting with high heat generation and impact load acting on the cutting edge, it constitutes the lower layer of the conventional coated tool Since the high-temperature strength of the conventional TiZrCN layer becomes insufficient, chipping (minute chipping) is likely to occur, and the service life is reached in a relatively short time due to these.

In view of the above, the present inventors have studied from the above viewpoint, particularly focusing on the conventional TiZrCN layer in order to improve the chipping resistance of the hard coating layer constituting the conventional coated tool. The following findings were obtained.
(A) The conventional TiZrCN layer constituting the lower layer of the hard coating layer of the conventional coated tool is a normal chemical vapor deposition apparatus,
Reaction gas composition - by _{volume%, TiCl 4: 0.3~2.5%,} ZrCl 4: 0.3~2.5%, CH 3 CN: 0.6~5%, N 2: 25~45% , H ₂ : remaining,
Reaction atmosphere temperature: 750-980 ° C.
Reaction atmosphere pressure: 2.7 to 13.3 kPa,
It is formed by vapor-depositing on condition of this.
Therefore, the conditions for forming the conventional TiZrCN layer are changed,
Reaction gas composition - by _{volume%, TiCl 4: 0.5~5%,} ZrCl 4: 0.5~1.5%, CH 3 CN: 0.5~1.5%, N 2: 10~30% , H ₂ : remaining,
In the reaction gas atmosphere of
During the initial reaction (30 minutes from the start of deposition)
Reaction atmosphere temperature: 750-850 ° C.
Reaction atmosphere pressure: 2.5-5 kPa,
Vapor deposition in a relatively low temperature, low pressure atmosphere,
During the main reaction (after 30 minutes from the start of deposition)
Reaction atmosphere temperature: 870-1000 ° C.
Reaction atmosphere pressure: 6-15 kPa,
Vapor deposition in a relatively high temperature and high pressure atmosphere
When the temperature and pressure of the reaction atmosphere are changed as described above in the initial reaction and the main reaction,
Compositional formula: (Ti _1-X Zr _X ) CN (wherein the atomic ratio is X: 0.05 to 0.15) and has a vertically grown crystal structure (hereinafter referred to as Ti and Zr carbonitrides) The modified TiZrCN layer is formed by vapor deposition, and the modified TiZrCN layer has superior high-temperature strength and superior heat resistance compared to the conventional TiZrCN layer.
(B) The modified TiZrCN layer is a NaCl-type face-centered cubic crystal in which constituent atoms composed of Ti, Zr, carbon (C), and nitrogen (N) are present at lattice points in the same manner as the conventional TiZrCN layer. This modified TiZrCN layer is irradiated with an electron beam to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface, using a field emission scanning electron microscope. Inclination angles (schematic diagrams shown in FIGS. 1A and 1B) and {110} formed by the normal of the {112} plane which is the crystal plane of the crystal grain with respect to the normal of the surface polished surface An inclination angle formed by a normal of the surface (schematic diagrams are shown in FIGS. 2A and 2B), and among the measured inclination angles, the measured inclination angle with respect to the {112} plane is the surface polished surface The total number of crystal grains within a tilt angle range of 0 to 10 degrees with respect to the normal of Measuring the product A, and measuring the total area B of crystal grains in which the measured inclination angle with respect to the {110} plane is within the range of 0 to 10 degrees with respect to the normal of the surface polished surface, When the value A / B of the ratio of the total area A to the total area B is obtained, the value of A / B shows 2 to 9, and as a result, the modified TiZrCN layer has a {112} plane orientation having a vertically grown crystal structure In this TiZrCN crystal grain, a {110} -oriented TiZrCN crystal grain having a vertically grown crystal structure is present.
For the conventional TiZrCN layer, the total area A of crystal grains in which the measured inclination angle with respect to the {112} plane of the crystal grains is within the range of an inclination angle of 0 to 10 degrees with respect to the normal line of the surface polished surface. And measuring the total area B of crystal grains in which the measured inclination angle with respect to the {110} plane is in the range of 0 to 10 degrees with respect to the normal line of the surface polished surface, When the value A / B of the ratio of the total area B was determined, the value of A / B was less than 2 or more than 9.
(C) The coated tool in which the lower layer of the hard coating layer is composed of an adhesive Ti compound layer and a modified TiZrCN layer, and the upper layer is composed of an Al ₂ O ₃ layer is accompanied by high heat generation, and the cutting blade Even when used in high-speed interrupted cutting where impact loads are applied to the steel, the modified TiZrCN layer has excellent high-temperature strength, so there is no chipping, chipping or peeling, and excellent heat resistance Therefore, it will show excellent chipping resistance and wear resistance over a long period of use without causing thermoplastic deformation and uneven wear.
This invention has been made based on the above findings,
"On the surface of the tool base made of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) As a lower layer, an adhesive Ti compound layer and a modified Ti carbonitride (modified TiZrCN) layer each having a total average layer thickness of 3 to 20 μm and formed by chemical vapor deposition,
(B) As an upper layer, an aluminum oxide layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition,
In the surface-coated cutting tool in which the hard coating layer composed of the above (a) and (b) is formed by vapor deposition,
(C) The adhesive Ti compound layer of the lower layer is a Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer having a total average layer thickness of 0.5 to 5 μm. Consisting of one or more layers of
(D) The modified Ti-based carbonitride (modified TiZrCN) layer of the lower layer has an average layer thickness of 2.5 to 15 μm, and
Composition formula: (Ti _1-X Zr _X ) CN
And a composite carbonitride layer of Ti and Zr that satisfies 0.05 ≦ X ≦ 0.15 (however, the atomic ratio) and has a vertically elongated crystal structure,
Furthermore, the modified Ti carbonitride (modified TiZrCN) layer is
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 the crystal grain is normal to the surface polished surface. The inclination angle formed by the normal of the {112} plane and the normal of the {110} plane, which are the crystal planes, is measured, and the measured inclination angle with respect to the {112} plane is the surface polished surface among the measured inclination angles The total area A of the crystal grains in the range of the tilt angle of 0 to 10 degrees with respect to the normal line, and the measured tilt angle for the {110} plane is 0 to 10 degrees with respect to the normal line of the surface polished surface When the total area B of the crystal grains within the range of the inclination angle is determined, it is a modified Ti-based carbonitride (modified TiZrCN) layer exhibiting crystal orientation with A / B being 2-9. A surface-coated cutting tool. "
It has the characteristics.
Next, the constituent layers of the hard coating layer of the coated tool of the present invention will be described in detail.
(A) Adhesive Ti compound layer of lower layer The Ti compound layer itself has high-temperature strength, and the presence of this makes the hard coating layer have high-temperature strength. In addition, the tool substrate and the modified TiZrCN layer It adheres firmly to both, and thus has the effect of contributing to improved adhesion of the hard coating layer to the tool substrate. However, if the total average layer thickness is less than 3 μm, the above effect cannot be fully exhibited. On the other hand, if the total average layer thickness exceeds 20 μm, high-speed cutting with high heat generation tends to cause thermoplastic deformation, which causes uneven wear. Therefore, the total average layer thickness is set to 3 to 20 μm. It was.
(B) Modified Ti-based carbonitride (modified TiZrCN) layer in the lower layer On the adhesive Ti compound layer in the lower layer,
Reaction gas composition - by _{volume%, TiCl 4: 0.5~5%,} ZrCl 4: 0.5~1.5%, CH 3 CN: 0.5~1.5%, N 2: 10~30% , H ₂ : remaining,
In the reaction gas atmosphere of
During the initial reaction (30 minutes from the start of deposition)
Reaction atmosphere temperature: 750-850 ° C.
Reaction atmosphere pressure: 2.5-5 kPa,
Vapor deposition in a relatively low temperature, low pressure atmosphere,
During the main reaction (after 30 minutes from the start of deposition)
Reaction atmosphere temperature: 870-1000 ° C.
Reaction atmosphere pressure: 6-15 kPa,
When deposited in a relatively high temperature and high pressure atmosphere,
Composition formula: (Ti _1-X Zr _X ) CN
In this case, a modified TiZrCN layer containing a Zr component satisfying 0.05 ≦ X ≦ 0.15 (however, atomic ratio) and having a vertically grown crystal structure is formed by vapor deposition.

  Then, with respect to the modified TiZrCN layer, 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 of the modified TiZrCN layer is irradiated with an electron beam. When the inclination angle formed by the normal line of the {112} plane and 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, Then, the total area of the crystal grains in which the measured inclination angle with respect to the {112} plane is within the range of 0 to 10 degrees with respect to the normal of the surface polished surface is A, and the {110} plane When the total area of crystal grains in which the measurement inclination angle is in the range of 0 to 10 degrees with respect to the normal of the surface polished surface is B, the value A / of the ratio of the total area A to the total area B A crystal orientation in which B is 2-9 is formed.

And since the modified TiZrCN layer has a vertically grown crystal structure showing a crystal orientation with A / B of 2 to 9, the high temperature strength of the modified TiZrCN layer is further improved as compared with the conventional TiZrCN layer, In high-speed intermittent cutting with high heat generation and impact load acting on the cutting edge, it exhibits excellent chipping resistance without causing thermoplastic deformation, uneven wear, and the like.
The procedure for obtaining the A / B value is specifically as follows.
First, in the state where the surface of the modified TiZrCN layer is a polished surface, it is set in a lens barrel of a field emission scanning electron microscope, and an electron beam with an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees to 1 nA. Irradiation is performed individually to crystal grains having a cubic crystal lattice existing within the measurement range of the polished surface, and an electron backscatter diffraction image apparatus is used to form a 30 × 50 μm region at 0.1 μm / step. First, the number of pixels γ recognized as a modified TiZrCN layer is counted, and then the {112} plane which is the crystal plane of the crystal grain with respect to the normal line of the surface polished surface Is measured, and the number of pixels α recognized as crystal grains having a value in the range of 0 to 10 degrees among the measured tilt angles is counted, and A = K × α / γ × 100 formula (where K = total surface of the modified TiZrCN layer) Crystal grains having a measured inclination angle with respect to the {112} plane within a range of an inclination angle of 0 to 10 degrees with respect to the normal line of the surface-polished surface from / the area of the modified TiZrCN layer existing within the measurement range) The value of the total area A is calculated.

  Similarly, the number of pixels γ recognized as the modified TiZrCN layer is counted, and then the normal of the {110} plane that is the crystal plane of the crystal grain is the normal of the surface polished surface. The tilt angle formed is measured, and among the measured tilt angles, the number of pixels β recognized as crystal particles having a value in the range of 0 to 10 degrees is counted, and an equation of B = K × β / γ × 100 ( Where K = the total area of the modified TiZrCN layer / the area of the modified TiZrCN layer existing within the measurement range), the measured inclination angle for the {110} plane is 0-10 with respect to the normal of the surface polished surface. The value of the total area B of the crystal grains within the range of the inclination angle of degrees is calculated.

  A / B can be obtained from the values of the total areas A and B calculated as described above.

  With respect to the Zr component contained in the modified TiZrCN layer, if the content ratio X (X = Zr / (Ti + Zr)) (however, the atomic ratio) is less than 0.05, it can be measured by a field emission scanning electron microscope. Since the area ratio of the total area B in the modified TiZrCN layer is reduced, the area ratio of the total area A is 60 to 90%. As a result, the value of the total area ratio A / B exceeds 9. Therefore, both the high temperature strength and wear resistance of the modified TiZrCN layer are insufficient.

On the other hand, when the content ratio X of the Zr component exceeds 0.15, the area ratio of the total area A in the modified TiZrCN layer is less than 60% as measured by a field emission scanning electron microscope. As a result, the total area ratio A / B is less than 2 and the desired high-temperature strength cannot be obtained. Therefore, the Zr content is 0.05 to 0. .15 and the total area ratio value A / B was set to 2-9.
In addition, if the average layer thickness of the modified TiZrCN layer is less than 2.5 μm, the desired excellent high-temperature strength and heat resistance cannot be exhibited. On the other hand, if the average layer thickness exceeds 15 μm, it causes uneven wear. Since the thermoplastic deformation easily occurs and the wear is promoted, the average layer thickness is set to 2.5 to 15 μm.
(C) Al ₂ O ₃ layer (upper layer)
The 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 and becomes too thick, 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.

  Since the modified TiZrCN layer that constitutes one of the lower layers of the hard coating layer has excellent high-temperature strength and heat resistance, the coated tool of the present invention is accompanied by high heat generation and with respect to the cutting edge. Even when used for high-speed intermittent cutting where an impact load is applied, it exhibits excellent chipping resistance and excellent wear resistance, and exhibits excellent cutting performance over a long period of time.

  Next, the coated 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 0.5 to 3 μm as raw material powder These raw material powders were blended into the blending composition shown in Table 1, and then added with wax, ball milled in acetone for 36 hours, dried under reduced pressure, and then formed into a compact with a predetermined shape at a pressure of 98 MPa. The green compact was press-molded and 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 portion had R: 0.07 mm. The tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG120408 were manufactured by performing the honing process.

Further, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, blend these raw material powders into the composition shown in Table 2, wet-mix for 36 hours with a ball mill, dry, and press-mold into green compact at 98 MPa pressure The green compact is sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.07 mm. Tool bases a to f made of TiCN base cermet having a chip shape of ISO standard / CNMG120408 were formed.
Next, a lower layer composed of an adhesive Ti compound layer and a modified TiZrCN layer is used as the lower layer of the hard coating layer on the surfaces of the tool bases A to F and the tool bases a to f using a normal chemical vapor deposition apparatus. Are deposited by the combinations and target layer thicknesses shown in Table 4 under the conditions shown in Table 3, and the Al ₂ O ₃ layer as the upper layer is also shown in Table 4 under the same conditions shown in Table 3. The coated tools 1 to 13 according to the present invention were manufactured by vapor deposition with a target layer thickness.
For the purpose of comparison, after depositing an adhesive Ti compound layer on the tool base, a conventional TiZrCN layer is deposited by the combination shown in Table 5 and the target layer thickness under the conditions shown in Table 3, and further as an upper layer Comparative coating tools 1 to 13 were manufactured by vapor-depositing the Al ₂ O ₃ layers under the conditions shown in Table 3 and with the target layer thicknesses shown in Table 5, respectively.
The above-described modified TiZrCN layers of the inventive coated tools 1 to 13 have a vertically grown crystal structure, whereas the conventional TiZrCN layers of the conventional coated tools 1 to 13 have a granular crystal structure, and A field emission scanning electron microscope is used to irradiate each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface of each TiZrCN layer with an electron beam, thereby normal to the surface polished surface. In contrast, the inclination angle formed by the normal of the {112} plane and the normal of the {110} plane, which are crystal planes of the crystal grains, is measured, and the measurement of the {112} plane is performed among the measurement inclination angles A is the total area of crystal grains whose tilt angle is in the range of 0 to 10 degrees with respect to the normal of the surface polished surface, and the measured tilt angle for the {110} plane is that of the surface polished surface. With a tilt angle of 0 to 10 degrees The total area of crystal grains in the 囲内 as B, was determined value A / B ratio of the total area A and the total area B. The ratio values (A / B) of the total area A and total area B are shown in Tables 4 and 5, respectively.
The A / B value was calculated according to the following procedure as described above.

First, in the state where the surface of the modified TiZrCN layer is a polished surface, it is set in a lens barrel of a field emission scanning electron microscope, and an electron beam with an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees to 1 nA. Irradiation is performed individually to crystal grains having a cubic crystal lattice existing within the measurement range of the polished surface, and an electron backscatter diffraction image apparatus is used to form a 30 × 50 μm region at 0.1 μm / step. First, the number of pixels γ recognized as a modified TiZrCN layer is counted, and then the {112} plane which is the crystal plane of the crystal grain with respect to the normal line of the surface polished surface The inclination angle formed by the normal line is measured, and among the measured inclination angles, the number α of pixels recognized as crystal grains having a value in the range of 0 to 10 degrees is counted, and the normal line of the surface polished surface is further counted. Is the crystal plane of the crystal grain { 110} plane normal angle is measured, and among the measured tilt angles, the number of pixels β recognized as crystal grains having a value in the range of 0 to 10 degrees is counted, and A = K × α / Γ × 100 and B = K × β / γ × 100 (where K = total area of the modified TiZrCN layer / area of the modified TiZrCN layer present in the measurement range), the total area A, the total area The value of B was calculated | required and the value of ratio of A / B was computed.
As shown in Tables 4 and 5, with respect to the modified TiZrCN layer of the coated tool of the present invention, the measured inclination angle with respect to the {112} plane obtained by using a field emission scanning electron microscope is relative to the normal line of the surface polished surface. The total area A of the crystal grains in the range of 0 to 10 degrees, and the measured inclination angle of the {110} plane is in the range of 0 to 10 degrees with respect to the normal of the surface polished surface The ratio (A / B) of the total area B of the crystal grains inside is 2 to 9, whereas in the conventional TiZrCN layer of the comparative coated tool, the value of the area ratio A / B is less than 2 Or it was more than 9.
Further, for the above-described coated tools 1 to 13 and comparative coated tools 1 to 13 described above, the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analyzer (longitudinal section of the layer). As a result, it was confirmed that the former and the latter consisted of an adhesive Ti compound layer, a modified TiZrCN layer, a conventional TiZrCN layer, and an Al ₂ O ₃ layer having substantially the same composition as the target composition. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated tools was measured using a scanning electron microscope (similarly longitudinal section measurement), the average layer thickness (5 The average value of point measurement) was shown.

Next, with the various coated cermet tools described above, the present coated tool 1 to 13 and the comparative coated tools 1 to 13 in a state where all the above-mentioned coated cermet tools are screwed to the tip of the tool steel tool with a fixing jig.
Work material: JIS / SNCM439 round direction bar with 4 equal intervals in the length direction,
Cutting speed: 420 m / min,
Cutting depth: 1.5 mm,
Feed: 0.23 mm / rev,
Cutting time: 10 minutes,
Wet high speed intermittent cutting test of nickel chrome molybdenum steel under the above conditions (referred to as cutting condition A),
Work material: JIS / S50C lengthwise equal 4 round grooved round bars,
Cutting speed: 420 m / min,
Cutting depth: 1.5 mm,
Feed: 0.25 mm / rev,
Cutting time: 10 minutes,
Wet high-speed intermittent cutting test of carbon steel under the above conditions (referred to as cutting condition B),
Work material: JIS / FCD500 lengthwise equidistant 4 round bars with vertical grooves,
Cutting speed: 450 m / min,
Cutting depth: 1.5 mm,
Feed: 0.28 mm / rev,
Cutting time: 10 minutes,
Wet high-speed intermittent cutting test of spheroidal graphite cast iron under the above conditions (referred to as cutting condition C),
In any cutting test (using water-soluble cutting oil), the flank wear width of the cutting edge was measured. The measurement results are shown in Table 6.

表４〜６に示される結果から、本発明被覆工具１〜１３は、硬質被覆層の改質ＴｉＺｒＣＮ層における、｛１１２｝面についての測定傾斜角が０〜１０度の範囲内にある結晶粒子の総面積Ａと、｛１１０｝面についての測定傾斜角が０〜１０度の範囲内にある結晶粒子の総面積Ｂの比の値（Ａ／Ｂ）は２〜９であることから、すぐれた高温強度を備え、さらに、Ｚｒ成分を含有したことによって、すぐれた耐熱性を有することにより、硬質被覆層の耐チッピング性が著しく改善されるとともに、長期にわたってすぐれた耐摩耗性を示すのに対して、硬質被覆層が従来ＴｉＺｒＣＮで構成された比較被覆工具１〜１３においては、高熱発生を伴う高速切削条件下では、硬質被覆層の高温強度が不十分であるために、硬質被覆層にチッピングが発生し、比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆工具は、各種鋼や鋳鉄などの通常の条件での連続切削や断続切削は勿論のこと、特に高い熱発生を伴い、かつ、切刃に対して衝撃的負荷が作用する高速断続切削加工でも、硬質被覆層がすぐれた耐チッピング性とすぐれた耐摩耗性を示し、長期に亘ってすぐれた切削性能を発揮するものであるから、切削装置の高性能化並びに切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。

From the results shown in Tables 4 to 6, the coated tools 1 to 13 of the present invention are crystal grains having a measured inclination angle with respect to the {112} plane in the range of 0 to 10 degrees in the modified TiZrCN layer of the hard coating layer. The ratio (A / B) of the total area A of the crystal grains and the total area B of the crystal grains having a measured inclination angle of 0 to 10 degrees with respect to the {110} plane is 2 to 9, which is excellent. In addition to having high temperature strength and having a Zr component, it has excellent heat resistance, thereby significantly improving the chipping resistance of the hard coating layer and exhibiting excellent wear resistance over a long period of time. On the other hand, in the comparative coating tools 1 to 13 in which the hard coating layer is conventionally composed of TiZrCN, the high temperature strength of the hard coating layer is insufficient under the high-speed cutting conditions with high heat generation. Chipping occurs And, it is apparent that lead to a relatively short time service life.
As described above, the coated tool of the present invention is not only continuous cutting and interrupted cutting under normal conditions such as various steels and cast irons, but also involves particularly high heat generation and has an impact load on the cutting edge. Even in high-speed interrupted cutting where the working force is applied, the hard coating layer exhibits excellent chipping resistance and excellent wear resistance, and exhibits excellent cutting performance over a long period of time. 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 {112} plane of the crystal grain in a modified TiZrCN layer and a conventional TiZrCN layer. It is a schematic explanatory drawing which shows the measurement range of the inclination angle of the {110} plane of the crystal grain in a modified TiZrCN layer and a conventional TiZrCN layer.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) As a lower layer, an adhesive Ti compound layer and a modified Ti carbonitride layer that have a total average layer thickness of 3 to 20 μm, both formed by chemical vapor deposition,
(B) As an upper layer, an aluminum oxide layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition,
In the surface-coated cutting tool in which the hard coating layer composed of the above (a) and (b) is formed by vapor deposition,
(C) The adhesive Ti compound layer of the lower layer is a Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer having a total average layer thickness of 0.5 to 5 μm. Consisting of one or more layers of
(D) The modified Ti-based carbonitride layer of the lower layer has an average layer thickness of 2.5 to 15 μm, and
Composition formula: (Ti _1-X Zr _X ) CN
And a composite carbonitride layer of Ti and Zr that satisfies 0.05 ≦ X ≦ 0.15 (however, the atomic ratio) and has a vertically elongated crystal structure,
Furthermore, the modified Ti carbonitride layer is
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 the crystal grain is normal to the surface polished surface. The inclination angle formed by the normal of the {112} plane and the normal of the {110} plane, which are the crystal planes, is measured, and the measured inclination angle with respect to the {112} plane is the surface polished surface among the measured inclination angles The total area A of the crystal grains in the range of the tilt angle of 0 to 10 degrees with respect to the normal line, and the measured tilt angle for the {110} plane is 0 to 10 degrees with respect to the normal line of the surface polished surface A surface coating characterized by being a modified Ti carbonitride layer exhibiting crystal orientation with A / B being 2 to 9 when the total area B of crystal grains within the range of the inclination angle is obtained Cutting tools.

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