WO2016052479A1

WO2016052479A1 - Surface-coated cutting tool having excellent chip resistance

Info

Publication number: WO2016052479A1
Application number: PCT/JP2015/077457
Authority: WO
Inventors: 佐藤　賢一; 翔龍岡; 健志山口
Original assignee: 三菱マテリアル株式会社
Priority date: 2014-09-30
Filing date: 2015-09-29
Publication date: 2016-04-07

Abstract

　Provided is a surface-coated cutting tool, the hard coating layer of which exhibits excellent chip resistance and peeling resistance under conditions of high-speed intermittent cutting. This surface-coated cutting tool has a tool base, the surface of which is coated with at least a bottom layer that includes a TiCN layer having an NaCl surface-centered cubic crystal structure and a top layer that comprises a TiAlCN layer having a NaCl surface-centered cubic monophasic crystal structure or a multiphase crystal structure of NaCl surface-centered cubic crystals and hexagonal crystals, and is preferably further coated with an outermost surface layer including an Al₂O₃ layer, wherein a complex nitride or complex carbonitride layer of the Ti and Al, when represented by the compositional formula Ti_{1 – x}Al_x (C_yN_{1 – y}), has an average content ratio Xave of Al in the total amount of Ti and Al, and an average content ratio Yave of C in the total amount of C and N (where Xave and Yave are each atomic ratios), that respectively satisfy the expressions 0.60 ≤ Xave ≤ 0.95 and 0 ≤ Yave ≤ 0.005.

Description

Surface coated cutting tool with excellent chipping resistance

The present invention provides an excellent hard coating layer even when cutting various steels and cast irons at high speed and under high-speed intermittent heavy cutting conditions in which intermittent and impactful high loads act on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent chipping resistance and exhibits excellent cutting performance over a long period of time.

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) The lower layer is a Ti carbide (hereinafter referred to as TiC) layer, a nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as TiCO). And a Ti compound layer composed of one or more of a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) an aluminum oxide layer (hereinafter, referred to as an Al ₂ O ₃ layer) having an α-type crystal structure in a state where the upper layer is chemically vapor-deposited;
There is known a coated tool formed by vapor-depositing a hard coating layer composed of (a) and (b).

However, the above-mentioned conventional coated tools exhibit excellent wear resistance in continuous cutting and intermittent cutting of various steels and cast irons, for example, but when this is used for high-speed intermittent cutting, a hard coating layer is used. Peeling and chipping are likely to occur, and the tool life is shortened.
In view of this, various types of coating tools in which the upper layer is improved have been proposed in order to suppress peeling and chipping of the hard coating layer.

For example, in Patent Document 1, a non-oxide film made of one or more of carbides, nitrides, and carbonitrides of Group 4a, 5a, and 6a metals in the periodic table is formed on the surface of a tool base, and α In an alumina-coated tool in which an oxide film mainly composed of Al ₂ O ₃ is formed, an oxide, an oxycarbide, and an acid of group 4a, 5a, and 6a metals in the periodic table are provided between the non-oxide film and the oxide film. An alumina-coated tool that forms a bonding layer having an fcc structure composed of a nitride or oxycarbonitride oxide-based single-layer film or multilayer film, and has a non-oxide film and a binder phase in an epitaxial relationship; Thus, a coated tool has been proposed in which the adhesion strength between the tool base and the alumina coating is increased, and the fracture resistance, peel resistance, and wear resistance are improved.

Further, for example, in Patent Document 2, a Ti compound layer composed of at least one of TiN, TiC, TiCN, TiCO, and TiCNO is formed as a lower layer on the surface of a tool base, and an Al ₂ O ₃ layer is formed as an upper layer. In the surface-coated cutting tool formed by vapor deposition, fine TiO ₂ particles having a particle diameter of 10 to 100 nm are formed at the interface between the lower layer and the upper layer, and the line segment ratio of the fine TiO ₂ particles per 10 μm of interface length is By setting the content to 10 to 50%, the aluminum oxide crystal grains of the upper layer grow non-epitaxially with respect to the lower layer on the TiO ₂ grains, while at the interface where the TiO ₂ grains do not exist, It has been proposed to improve the chipping resistance and wear resistance of the hard coating layer by epitaxial growth.

JP-A-10-18039 JP 2010-201575 A

In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work. As a result, cutting speed has been further increased, high cutting depth, high feed, etc. There is a tendency for impact and intermittent high loads to act on the cutting edge due to intermittent heavy cutting, etc., but in the above-mentioned conventional coated tools, this is continuous cutting under normal conditions such as steel and cast iron. There is no problem when it is used for intermittent cutting, especially when it is used under high-speed interrupted heavy cutting conditions, cracks generated on the surface of the hard coating layer tend to propagate to the entire hard coating layer, relatively The current situation is that the service life is reached in a short time.

In view of the above, the inventors of the present invention, from the above-mentioned viewpoints, made Ti compound crystal grains constituting the lower layer formed on the surface of the tool substrate and a composite nitride of Ti and Al constituting the upper layer formed thereon. Alternatively, extensive research has been conducted with a focus on controlling the epitaxial relationship between crystal grains of composite carbonitride (hereinafter abbreviated as TiAlCN in some cases).
As a result, a crystal grain of a Ti carbonitride (TiCN) layer having a NaCl type face centered cubic crystal structure constituting at least one of the lower layers and a crystal grain of the TiAlCN layer constituting the upper layer Predetermining the formation ratio of crystal grains that pass through the interface between the TiCN layer and the TiAlCN layer, and that the crystal orientation of the TiCN crystal grains and the crystal orientation of the TiAlCN crystal grains are within 5 degrees. By increasing the amount, the adhesion strength at the interface between the TiCN layer and the TiAlCN layer is improved. As a result, the cutting edge is subjected to high-speed intermittent heavy cutting conditions in which an intermittent and impactful high load acts. In addition, it was found that the hard coating layer exhibits excellent chipping resistance and peeling resistance.

The present invention has been made based on the above findings,
“(1) Hard coating comprising a lower layer and an upper layer on the surface of a tool base made of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh pressure sintered body In a surface-coated cutting tool in which a layer is formed,
(A) The lower layer has a total average layer thickness of 1 to 20 μm composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer. And a Ti carbonitride compound layer having a crystal structure of at least a NaCl type face centered cubic crystal.
(B) The upper layer is a composite of Ti and Al having an NaCl type face centered cubic single phase crystal structure having an average layer thickness of 1 to 20 μm or a mixed phase structure of NaCl type face centered cubic and hexagonal crystals. A nitride or composite carbonitride layer,
(C) When the composite nitride or composite carbonitride layer of Ti and Al is represented by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the total amount of Ti of Ti and Al The average content ratio Xave and the average content ratio Yave (where Xave and Yave are atomic ratios) of the total amount of C and N in C are 0.60 ≦ Xave ≦ 0.95 and 0 ≦ Yave, respectively. ≦ 0.005 is satisfied,
(D) a Ti carbonitride layer having a NaCl-type face-centered cubic crystal structure in the lower layer and a Ti-Al composite nitride or composite charcoal having an NaCl-type face-centered cubic crystal structure in the upper layer For the nitride layer, the crystal orientation of each crystal grain is analyzed from the longitudinal section direction perpendicular to the tool base using an electron beam backscatter diffractometer, and the individual crystal grain is compared with the normal of the base surface. When the inclination angle formed by the normal of the crystal plane is measured, the crystal grains are adjacent to each other via the interface between the upper layer and the lower layer, and have a crystal structure of the NaCl type face centered cubic crystal of the lower layer A crystal grain whose orientation difference between the normal direction of the (hkl) plane of the grain and the normal direction of the (hkl) plane of the crystal grain having the NaCl type face centered cubic crystal structure of the upper layer is within 5 degrees Exists at the interface between the upper layer and the lower layer, and the crystal grain linear density is two Surface-coated cutting tool, characterized in that at 10μm or more.
(2) The Ti carbonitride layer having the NaCl-type face-centered cubic crystal structure of the lower layer and the Ti-Al composite nitride or the composite charcoal having the NaCl-type face-centered cubic crystal structure of the upper layer For the nitride layer, the crystal orientation of each crystal grain is analyzed from the longitudinal section direction perpendicular to the tool base using an electron beam backscatter diffractometer, and the individual crystal grain is compared with the normal of the base surface. When the inclination angle formed by the normal of the crystal plane is measured, the crystal grains are adjacent to each other via the interface between the upper layer and the lower layer, and have a crystal structure of the NaCl type face centered cubic crystal of the lower layer A crystal grain whose orientation difference between the normal direction of the (hkl) plane of the grain and the normal direction of the (hkl) plane of the crystal grain having the NaCl type face centered cubic crystal structure of the upper layer is within 5 degrees The crystal structure of NaCl type face centered cubic crystals of the upper layer and the lower layer The ratio of the area occupied by Ti in the carbonitride layer is 30 area% or more with respect to the total area of crystal grains adjacent via the interface between the upper layer and the lower layer (1) The surface-coated cutting tool according to 1.
(3) When the Ti and Al composite nitride or composite carbonitride layer is observed from the longitudinal sectional direction of the layer, the Ti and Al composite nitridation having a NaCl type face centered cubic structure in the layer is observed. (1) or (2) characterized by having a columnar structure having an average grain width W of 0.1 to 2.0 μm and an average aspect ratio A of 2 to 10 The surface coating cutting tool in any one.
(4) The composite of Ti and Al having the crystal structure of the NaCl type face centered cubic single phase having an average layer thickness of 1 to 20 μm or the mixed type crystal structure of NaCl type face centered cubic and hexagonal crystal as in (b). The outermost layer comprising at least an Al ₂ O ₃ layer having an average layer thickness of 1 to 25 μm is further formed on the surface of the upper layer made of a nitride or composite carbonitride layer, The surface-coated cutting tool according to any one of 1) to (3). "
It has the characteristics.

Below, the structural layer of the hard coating layer of the coating tool of this invention is demonstrated in detail.
Lower layer (Ti compound layer):
Ti compound layers (eg, Ti carbide (TiC) layer, nitride (TiN) layer, carbonitride (TiCN) layer, carbonate (TiCO) layer and carbonitride oxide (TiCNO) layer) are basically Exists as a lower layer of the TiAlCN layer, and the hard coating layer has a high temperature strength due to its excellent high temperature strength. In addition, the hard coating layer adheres to both the tool base and the upper TiAlCN layer. It has the effect | action which maintains the adhesiveness with respect to a tool base | substrate. However, if the average layer thickness is less than 1 μm, the above-mentioned effect cannot be fully exerted. On the other hand, if the average layer thickness exceeds 20 μm, the thermoplastic deformation particularly in high-speed heavy cutting and high-speed intermittent cutting with high heat generation. Since this causes uneven wear, the average layer thickness was set to 1 to 20 μm.
Further, in order to epitaxially grow the upper layer by taking over the orientation of the lower layer and to improve the chipping resistance and peeling resistance of the hard coating layer, the lower layer has at least a NaCl type face centered cubic crystal structure. It is necessary to form a TiCN layer composed of TiCN crystal grains.
The lower layer is formed using a conventional chemical vapor deposition apparatus, for example,
Reaction gas composition (volume%): TiCl ₄ 1.0 to 5.0%, N ₂ 5 to 35%, CO 0 to 5%, CH ₃ CN 0 to 1%, CH ₄ 0 to 10%, balance H ₂ ,
Reaction atmosphere temperature: 780 to 900 ° C.
Reaction atmosphere pressure: 5 to 13 kPa,
It can form by carrying out chemical vapor deposition until it becomes target average layer thickness on the conditions of.

Upper layer (Ti-Al composite nitride or composite carbonitride layer having a NaCl-type face-centered cubic single-phase crystal structure or a NaCl-type face-centered cubic and hexagonal mixed-phase crystal structure):
The upper layer of the hard coating layer of the present invention is a chemical vapor deposited NaCl type face centered cubic single phase crystal structure or an NaCl type face centered cubic and hexagonal mixed crystal structure having an average layer thickness of 1 to 20 μm. And a composite nitride or composite carbonitride layer (TiAlCN layer) of Ti and Al.
The TiAlCN layer constituting the upper layer of the present invention is high in hardness and exhibits excellent wear resistance. However, if the average layer thickness is less than 1 μm, the layer thickness is thin, and thus wear resistance over a long period of use. On the other hand, if the average layer thickness exceeds 20 μm, the crystal grains become coarse and chipping tends to occur.
Therefore, the average thickness of the TiAlCN layer constituting the upper layer is determined to be 1 to 20 μm.

When the TiAlCN layer constituting the upper layer of the present invention is expressed by the composition formula: (Ti _1-x Al _x ) (N _1-y C _y ), the average content ratio Xave in the total amount of Ti and Al in Al And the content ratio Yave (where Xave and Yave are both atomic ratios) of the total amount of C and N in C and C satisfy 0.60 ≦ Xave ≦ 0.95 and 0 ≦ Yave ≦ 0.005, respectively. .
Here, when the average content ratio Xave (atomic ratio) of Al is less than 0.60, the composite nitride or composite carbonitride layer of Ti and Al is inferior in hardness, so high-speed intermittent heavy cutting such as alloy steel When it is used, the wear resistance is not sufficient. On the other hand, when the average content ratio Xave of Al exceeds 0.95, the content ratio of Ti is relatively decreased, so that embrittlement is caused and chipping resistance is lowered.
Therefore, the average content ratio Xave (atomic ratio) of Al is set to 0.60 ≦ Xave ≦ 0.95.
Further, when the average content ratio (atomic ratio) Yave of the C component contained in the composite nitride or composite carbonitride layer is a minute amount in the range of 0 ≦ Yave ≦ 0.005, the adhesion between the upper layer and the lower layer As a result, the impact at the time of cutting is reduced by improving the lubricity, and as a result, the chipping resistance and chipping resistance of the composite nitride or composite carbonitride layer are improved. On the other hand, if the content ratio Yave of the C component is out of the range of 0 ≦ Yave ≦ 0.005, the toughness of the composite nitride or composite carbonitride layer is lowered, so that the chipping resistance and chipping resistance are reduced.
Therefore, the content ratio Yave (atomic ratio) of the C component is 0 ≦ Yave ≦ 0.005.

Orientation difference between TiCN crystal grains of NaCl type face centered cubic structure in the lower layer and TiAlCN crystal grains of NaCl type face centered cubic structure in the upper layer:
The present invention relates to a Ti carbon nitride layer having a NaCl type face centered cubic crystal structure in a lower layer, and a Ti and Al composite nitride or composite carbon having an NaCl type face centered cubic crystal structure in an upper layer. For the nitride layer, the crystal orientation of each crystal grain is analyzed from the longitudinal section direction perpendicular to the tool base using an electron beam backscatter diffraction apparatus, and the individual crystal grains are compared with the normal of the tool base surface. When the inclination angle formed by the normal of the crystal plane is measured, the crystal grains adjacent to each other through the interface between the upper layer and the lower layer, and having the crystal structure of the NaCl type face centered cubic crystal of the lower layer A crystal grain whose orientation difference between the normal direction of the (hkl) plane and the normal direction of the (hkl) plane of the crystal grain having the NaCl type face-centered cubic crystal structure of the upper layer is within 5 degrees is Exists at the interface between the layer and the lower layer, and the linear density of the crystal grains is 2/10 μm. Determine the crystal grains of the orientation so as to above.

FIG. 1 shows a schematic diagram of a layer structure of a TiCN layer (lower layer) having a NaCl type face centered cubic crystal structure and a TiAlCN layer (upper layer) having a NaCl type face centered cubic crystal structure. .
As can be seen from FIG. 1, a crystal structure form in which crystal grains grow through the interface is observed at the interface between the upper layer and the lower layer. The “crystal grains adjacent to each other via the interface between the upper layer and the lower layer” in the present invention are crystal grains having such a crystal structure.
For the “crystal grains adjacent via the interface between the upper layer and the lower layer”, an arbitrary crystal plane (hkl) of the crystal grains having the crystal structure of the NaCl-type face-centered cubic crystal in the lower layer (for example, (112) plane) normal direction is measured with respect to the tool base surface normal, and the measured tilt angle is α (hkl) (degrees). The inclination angle formed by the normal direction of the (hkl) plane in the crystal grain having the center cubic crystal structure with respect to the normal line of the tool base surface is measured, and the measured inclination angle is expressed by β (hkl) (degrees). When the absolute value of the difference between α (hkl) (degrees) and β (hkl) (degrees) is 5 degrees or less (ie, | α (hkl) −β (hkl) | ≦ 5 (degrees) In addition, it can be said that the upper layer performs crystal growth (epitaxial growth) that inherits the orientation of the lower layer.
When the line density of the crystal grains at the interface between the upper layer and the lower layer satisfying | α (hkl) −β (hkl) | ≦ 5 (degrees) is 2/10 μm or more, the upper layer and the lower layer The adhesion strength at the interface is improved, and as a result, the chipping resistance and peel resistance of the hard coating layer can be increased.
On the other hand, when the linear density of crystal grains satisfying | α (hkl) −β (hkl) | ≦ 5 (degrees) is less than 2/10 μm, the upper layer of the hard coating layer as a whole has a sufficient epitaxial growth structure. Therefore, abnormal damage such as chipping and peeling cannot be sufficiently suppressed.
Note that an arbitrary crystal plane can be selected for the (hkl) plane to be measured, and is not particularly limited. Typically, for example, the (100) plane, the (110) plane, ( It is possible to determine the plane orientation difference between the upper layer and the lower layer by measuring the inclination angle formed by the normal lines such as the (111) plane, the (211) plane, and the (210) plane with respect to the normal line on the tool base surface. it can.
In addition, the above-mentioned “linear density is 2/10 μm” means that within the length range of 10 μm along the interface between the upper layer and the lower layer, | α (hkl) −β (hkl) | ≦ 5 ( This means that there are two or more crystal grains satisfying (degree).

Epitaxially grown crystal grain area ratio:
Further, the crystal grains are adjacent to each other through the interface between the upper layer and the lower layer, and the orientation difference (| α (hkl) −β (hkl) |) obtained above satisfies 5 (degrees) or less. The grain density of the crystal grains at the interface between the upper layer and the lower layer is 2/10 μm or more, and at the same time, the area ratio of such epitaxially grown crystal grains passes through the interface between the upper layer and the lower layer. The total area of adjacent crystal grains (that is, the Ti carbonitride layer having the NaCl-type face-centered cubic crystal structure in the adjacent lower layer and the NaCl-type face-centered cubic crystal in the upper layer) In the case of occupying an area ratio of 30% or more with respect to the total area of Ti and Al composite nitride or composite carbonitride layer having a structure), the hard coating layer having such a crystal structure is Since chipping resistance and peel resistance are further improved, Area ratio of Takisharu grown crystal grains is preferably 30% or more.

Crystal grains having a NaCl-type face-centered cubic structure (hereinafter sometimes simply referred to as “cubic”) constituting the composite nitride or composite carbonitride layer:
For each cubic crystal grain in the composite nitride or composite carbonitride layer, when observed and measured from the film cross-section side perpendicular to the tool substrate surface, the particle width in the direction parallel to the tool substrate surface is w, The grain length in the direction perpendicular to the tool substrate surface is l, the ratio l / w between w and l is the aspect ratio a of each crystal grain, and the average of the aspect ratio a obtained for each crystal grain When the average aspect ratio is A and the average value of the particle widths w obtained for individual crystal grains is the average particle width W, the average particle width W is 0.1 to 2.0 μm and the average aspect ratio A is 2 to 10 It is desirable to control so as to satisfy
When this condition is satisfied, the cubic crystal grains constituting the composite nitride or composite carbonitride layer have a columnar structure and exhibit excellent wear resistance. On the other hand, when the average aspect ratio A is less than 2, it becomes difficult to form a periodic distribution of the composition, which is a feature of the present invention, in the crystal grains of the NaCl-type face-centered cubic structure. This is not preferable because cracks are likely to grow along a plane along a periodic distribution of the composition in the cubic crystal phase, which is a feature of the present invention, and a plurality of grain boundaries. Further, when the average particle width W is less than 0.1 μm, the wear resistance is lowered, and when it exceeds 2.0 μm, the toughness is lowered. Therefore, the average grain width W of the cubic crystal grains constituting the composite nitride or composite carbonitride layer is preferably 0.1 to 2.0 μm.

Outermost layer:
The present invention relates to a composite nitride or composite of Ti and Al having an NaCl type face centered cubic single phase crystal structure having an average layer thickness of 1 to 20 μm or a mixed phase structure of NaCl type face centered cubic and hexagonal crystals. An uppermost surface layer including at least an Al ₂ O ₃ layer having an average layer thickness of 1 to 25 μm can be further formed on the surface of the upper layer made of the carbonitride layer.
The outermost Al ₂ O ₃ layer increases the high temperature hardness and heat resistance of the hard coating layer, but if the average surface thickness of the outermost surface layer is less than 1 μm, the above properties cannot be sufficiently provided in the hard coating layer. On the other hand, if the average layer thickness exceeds 25 μm, the high heat generated at the time of cutting and the intermittent and shocking high load acting on the cutting edge make it easier for the thermoplastic deformation to cause uneven wear and accelerate the wear. Therefore, the average layer thickness is desirably 1 to 25 μm.

Deposition method:
The lower layer and the outermost surface layer of the present invention can be formed by, for example, an ordinary chemical vapor deposition method.
The upper layer can also be formed by a normal chemical vapor deposition method, but can also be formed by, for example, the following vapor deposition method.
That is, a gas group A composed of NH ₃ and H ₂ and a gas group B composed of TiCl ₄ , AlCl ₃ , NH ₃ , N ₂ , C ₂ H ₄ , and H ₂ are applied to a chemical vapor deposition reactor equipped with a tool base. The reaction gas composition on the surface of the tool substrate is controlled by adjusting the supply conditions of the gas group A and the gas group B, and the reaction atmosphere pressure is 2 to 5 kPa, the reaction atmosphere. By performing the thermal CVD method at a temperature of 700 to 900 ° C. for a predetermined time, a TiAlCN layer having a predetermined target layer thickness and target composition can be formed.

In the coated tool of the present invention, the normal direction of the (hkl) plane of the TiCN crystal grains of the lower layer and the orientation difference thereof are formed on the lower layer having the TiCN layer having the NaCl type face centered cubic crystal structure. By forming the epitaxially grown upper layer TiAlCN crystal grains that are within 5 degrees, and the epitaxially grown crystal grains have a linear density of 2/10 μm or more at the interface between the upper layer and the lower layer, Alternatively, further, by making the area ratio of the epitaxially grown crystal grains 30% or more of the total area, the adhesion strength between the upper layer and the lower layer is improved, and as a result, the cutting edge is intermittently connected at high speed. Even under high-speed intermittent heavy cutting conditions where high loads such as impact and impact are applied, the hard coating layer exhibits excellent chipping resistance and peeling resistance, and excellent cutting over a long period of use. It is to demonstrate the performance.

The layer structure of the hard coating layer of the present invention comprising a TiCN layer (lower layer) having an NaCl type face centered cubic crystal structure and a TiAlCN layer (upper layer) having an NaCl type face centered cubic crystal structure. A schematic diagram is shown.

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

As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared, and these raw material powders are blended as shown in Table 1. Blended into the composition, added with wax, mixed in a ball mill in acetone for 24 hours, dried under reduced pressure, pressed into a compact of a predetermined shape at a pressure of 98 MPa, and the compact was 1370 in a vacuum of 5 Pa. Vacuum sintered under the condition of holding for 1 hour at a predetermined temperature in the range of ~ 1470 ° C, and after sintering, manufacture tool bodies A to C made of WC-base cemented carbide with ISO standard SEEN1203AFSN insert shape, respectively. did.

In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, WC powder, Co powder all having an average particle diameter of 0.5 to 2 μm. And Ni powder are prepared, these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 98 MPa. The body was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base D made of TiCN-based cermet having an ISO standard SEEN1203AFSN insert shape was produced.

Next, a chemical vapor deposition apparatus is used on the surfaces of these tool bases A to D,
First, under the formation conditions shown in Table 3, the lower layer shown in Table 6 is formed,
Next, from the formation conditions A to J shown in Tables 4 and 5, that is, from the gas group A composed of NH ₃ and H ₂ , TiCl ₄ , AlCl ₃ , NH ₃ , N ₂ , C ₂ H ₄ , H ₂ As the gas group B and the gas supply method, the reaction gas composition (capacity% relative to the total of the gas group A and the gas group B) is set as NH ₃ : 1.5 to 3.0% as the gas group A. , H ₂ : 50 to 75%, gas group B as TiCl ₄ : 0.1 to 0.15%, AlCl ₃ : 0.3 to 0.5%, N ₂ : 0 to 2%, C ₂ H ₄ : 0 to 0.05%, H ₂ : remaining, reaction atmosphere pressure: 2 to 5 kPa, reaction atmosphere temperature: 700 to 900 ° C., supply cycle 1 to 5 seconds, gas supply time 0.15 to 0.25 per cycle Second, the phase difference between gas supply A and gas supply B is 0.10-0.20 seconds, In the meantime, the coated tools 1 to 13 of the present invention were produced by forming a top layer by performing a thermal CVD method.
For the inventive coated tools 11 to 13, the upper layer shown in Table 6 was formed under the formation conditions shown in Table 3.

For comparison purposes, the lower layer shown in Table 6 is formed on the surfaces of the tool bases A to D under the formation conditions shown in Table 3, and the conditions shown in Table 3, Table 4, and Table 5 are set. A hard coating layer including at least a composite nitride or composite carbonitride layer of Ti and Al was formed by vapor deposition in the same manner as the coated tools 1 to 13 of the present invention at a target layer thickness (μm) shown in FIG.
For the comparative coated tools 11 to 13, the upper layer shown in Table 6 was formed under the formation conditions shown in Table 3 in the same manner as the coated tools 11 to 13 of the present invention.

The cross sections in the direction perpendicular to the tool substrate of each component layer of the coated tools 1 to 13 of the present invention and the comparative coated tools 1 to 13 were measured using a scanning electron microscope (magnification 5000 times), and 5 points within the observation field of view. When the average layer thickness was measured and averaged to determine the average layer thickness, the average layer thickness was substantially the same as the target layer thickness shown in Tables 6 and 7.

In addition, regarding the average content ratio Xave of Al in the upper TiAlCN layer, the electron beam was irradiated from the sample surface side in the sample whose surface was polished using an electron beam microanalyzer (Electron-Probe-Micro-Analyzer: EPMA). Then, the average content ratio Xave of Al was determined from the 10-point average of the analysis result of the obtained characteristic X-ray.
The average content ratio Yave of C was determined by secondary ion mass spectrometry (Secondary-Ion-Mass-Spectroscopy: SIMS). The ion beam was irradiated in the range of 70 μm × 70 μm from the sample surface side, and the concentration in the depth direction was measured for the components emitted by the sputtering action. The average content ratio Yave of C indicates the average value in the depth direction for the TiAlCN layer. However, the content ratio of C excludes the inevitable content ratio of C that is included without intentionally using a gas containing C as a gas raw material. Specifically, the content ratio (atomic ratio) of the C component contained in the TiAlCN layer when the supply amount of C ₂ H ₄ is 0 is determined as an unavoidable C content ratio, and C ₂ H ₄ is intentionally determined. A value obtained by subtracting the unavoidable C content from the content (atomic ratio) of the C component contained in the TiAlCN layer obtained when supplied was determined as Yave.

Further, for the TiCN crystal grains in the lower layer of the hard coating layer and the TiAlCN crystal grains in the upper layer, the crystal orientation of the individual crystal grains is analyzed using a field emission scanning electron microscope, and the individual crystal grains with respect to the normal of the tool substrate surface are analyzed. In addition to measuring the inclination angle formed by the normal of the crystal plane of the crystal grain, the crystal planes of the respective crystal grains measured with respect to the TiCN crystal grains of the lower layer and the TiAlCN crystal grains of the upper layer adjacent to each other via the interface ( For example, the difference between the inclination angles formed by the normal line of (hkl) plane and the normal line of the tool substrate surface is obtained, and adjacent to each other via the interface measured above depending on whether or not the difference is within 5 degrees. It is determined whether the lower layer TiCN crystal grains and the upper layer TiAlCN crystal grains correspond to the crystal grains defined in the present invention.
That is, for the coated tools 1 to 13 of the present invention and the comparative coated tools 1 to 13, 1.0 μm in the thickness direction of the lower layer from the interface between the upper layer and the lower layer, and 1. in the thickness direction of the upper layer. A measurement range (2.0 μm × 50 μm) of a cross-sectional polished surface of 0 μm and 50 μm in a direction parallel to the tool base surface is set in a lens barrel of a field emission scanning electron microscope, and incident on the polished surface is 70 degrees. An electron backscatter diffraction image apparatus is used by irradiating an electron beam with an acceleration voltage of 15 kV at an angle with an irradiation current of 1 nA to each crystal grain having a cubic crystal lattice existing within the measurement range of each polished surface. Measure the inclination angle formed by the normal of the (hkl) plane of the crystal grain with respect to the normal of the tool substrate surface in a 2.0 × 50 μm measurement area at an interval of 0.1 μm / step. For example, (h) of the TiCN crystal grains of the lower layer l) The inclination angle formed by the normal of the surface and the normal of the tool substrate surface is α (degrees), and the inclination angle formed by the normal of the (hkl) surface of the TiAlCN crystal grain of the upper layer and the normal of the tool substrate surface Is β (degrees), it is determined whether or not the absolute value of the difference in inclination angles (= | α (degrees) −β (degrees) |) is within 5 degrees. Is within 5 degrees, it is determined that the TiCN crystal grains of the lower layer and the TiAlCN crystal grains of the upper layer which are adjacent to each other through the interface measured above are epitaxially grown crystal grains.
Then, the number of crystal grains determined to be epitaxially grown was determined as the number per unit length of the interface between the upper layer and the lower layer.
In the present invention, in counting the number of crystal grains determined to be epitaxially grown, the number of TiCN crystal grains in contact with the interface is one, and the number of TiAlCN crystal grains in contact with the interface is one. Respectively.
Furthermore, the area ratio (area%) to the total area of the crystal grains in which the crystal grains determined to be epitaxially grown were in contact at the interface between the upper layer and the lower layer was measured.
Tables 6 and 7 show these values.

Further, for the coated tools 1 to 13 of the present invention and the comparative coated tools 1 to 13, using the scanning electron microscope (magnification 5000 times and 20000 times) from the cross-sectional direction perpendicular to the tool substrate, the tool substrate surface and the horizontal direction The individual crystal grains in the (Ti _1-xy Al _x Me _y ) (C _z N _1-z ) layer constituting the composite nitride or composite carbonitride layer existing in the range of 10 μm in length Observed from the cross section side of the film perpendicular to the tool substrate surface, the maximum particle width w in the direction parallel to the substrate surface and the maximum particle length l in the direction perpendicular to the substrate surface were measured, and the aspect ratio a (= l / w), the average value of the aspect ratio a obtained for each crystal grain is calculated as the average aspect ratio A, and the average value of the grain width w obtained for each crystal grain is the average grain width. Calculated as W . Tables 6 and 7 show these values.

Next, the coated tools 1 to 13 and the comparative coated tools 1 to 13 according to the present invention will be described below in a state where each of the various coated tools is clamped to the tip of a cutter made of tool steel having a cutter diameter of 125 mm by a fixing jig. The dry high-speed face milling, which is a kind of high-speed intermittent cutting of carbon steel, and a center-cut cutting test were performed, and the flank wear width of the cutting edge was measured. The results are shown in Table 8.

Tool substrate: Tungsten carbide-based cemented carbide, titanium carbonitride-based cermet,
Cutting test: dry high-speed face milling, center cutting,
Work material: JIS / SCM440 block material with a width of 100 mm and a length of 400 mm,
Rotational speed: 968 min ⁻¹
Cutting speed: 380 m / min,
Cutting depth: 1.5 mm,
Single blade feed: 0.1 mm / tooth,
Cutting time: 8 minutes

As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared. Blended in the composition shown in Table 9, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, pressed into a green compact of a predetermined shape at a pressure of 98 MPa. In a 5 Pa vacuum, vacuum sintering is performed at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge is subjected to a honing process of R: 0.07 mm. Tool bases E to G made of WC-base cemented carbide having an insert shape of CNMG120212 were produced.

In addition, as raw material powders, TiCN (TiC / TiN = 50/50 by mass ratio) powder, NbC powder, WC powder, Co powder, and Ni powder each having an average particle diameter of 0.5 to 2 μm are prepared, These raw material powders were blended into the composition shown in Table 10, wet mixed for 24 hours with a ball mill, dried, and then pressed into a green compact at a pressure of 98 MPa. Sintered in an atmosphere at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge part is subjected to a honing process of R: 0.09 mm so that the TiCN base has an insert shape of ISO standard / CNMG120212 A tool substrate H made of cermet was formed.

Next, on the surfaces of the tool bases E to G and the tool base H, a chemical vapor deposition apparatus is used and the conditions shown in Table 3, Table 4 and Table 5 are applied in the same manner as in Example 1, first, Table 11 Were formed, and then (Ti _1-x Al _x ) (C _y N _1-y ) layer was deposited to produce the coated tools 14 to 26 of the present invention shown in Table 11. .
For the inventive coated tools 20 to 26, the upper layer as shown in Table 11 was formed under the formation conditions shown in Table 3.

For comparison purposes, a normal chemical vapor deposition apparatus was used on the surfaces of the tool bases E to G and the tool base H, and the conditions shown in Tables 3, 4 and 5 and the target layer thicknesses shown in Table 12 were used. Comparative coating tools 14 to 26 shown in Table 12 were produced by vapor-depositing a hard coating layer in the same manner as the coating tool of the present invention.
As with the inventive coated tools 20 to 26, the comparative coated tools 20 to 26 were formed with the upper layer shown in Table 12 under the forming conditions shown in Table 3.

The cross-section of each component layer of the inventive coated tool 14-26 and comparative coated tool 14-26 is measured using a scanning electron microscope (magnification 5000 times), and the layer thicknesses at five points in the observation field are measured and averaged. As a result, the average layer thickness was found to be substantially the same as the target layer thickness shown in Tables 11 and 12.

The average content ratio Xave of Al and the average content ratio Yave of C in the upper TiAlCN layer were determined in the same manner as in Example 1 using an electron beam microanalyzer (Electron-Probe-Micro-Analyzer: EPMA).
Also, the lower layer TiCN crystal grains and the upper layer TiAlCN crystal grains adjacent to each other through the interface are subjected to the method of the (hkl) plane of the lower layer TiCN crystal grains using a field emission scanning electron microscope. The inclination angle formed by the line and the normal of the tool base surface is α (degrees), and the inclination angle formed by the normal of the (hkl) plane of the TiAlCN crystal grain of the upper layer and the normal of the tool base surface is β (degrees) In addition, the absolute value of the difference in inclination angle (= | α (degree) −β (degree) |) is obtained, and the number of TiCN crystal grains in the lower layer and TiAlCN grains in the upper layer, which are 5 degrees or less, is counted. The number per unit length of the interface between the upper layer and the lower layer was determined.
Further, with respect to the total area of the crystal grains in contact with the interface between the upper layer and the lower layer of the lower layer TiCN crystal grain satisfying | α (degree) −β (degree) | ≦ 5 (degrees) and the upper layer TiAlCN crystal grain. The area ratio (area%) was determined.
The average grain width W and average aspect ratio A of the crystal grains were determined in the same manner as in Example 1.
Tables 11 and 12 show these values.

Next, the present coated tools 14 to 26 and the comparative coated tools 14 to 26 in the state where all the various coated tools are screwed to the tip of the tool steel tool with a fixing jig are shown below. A dry high-speed intermittent cutting test for carbon steel and a wet high-speed intermittent cutting test for cast iron were performed, and the flank wear width of the cutting edge was measured for both.
Cutting condition 1:
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 380 m / min,
Cutting depth: 1.5 mm,
Feed: 0.25 mm / rev,
Cutting time: 5 minutes,
(Normal cutting speed is 220 m / min),
Cutting condition 2:
Work material: JIS / FCD700 lengthwise equal length 4 round bar with round groove,
Cutting speed: 320 m / min,
Cutting depth: 1.5 mm,
Feed: 0.1 mm / rev,
Cutting time: 5 minutes,
(Normal cutting speed is 200 m / min),
Table 13 shows the results of the cutting test.

As the raw material powder, cBN powder, TiN powder, TiC powder, Al powder, and Al ₂ O ₃ powder each having an average particle diameter in the range of 0.5 to 4 μm were prepared. These raw material powders are shown in Table 14. After blending into the blended composition, wet mixing with a ball mill for 80 hours, drying, and press-molding into a green compact with a diameter of 50 mm × thickness: 1.5 mm at a pressure of 120 MPa, and then this green compact Is sintered in a vacuum atmosphere at a pressure of 1 Pa at a predetermined temperature in the range of 900 to 1300 ° C. for 60 minutes to obtain a presintered body for a cutting edge piece, and this presintered body is separately prepared. A normal ultra high pressure sintering apparatus in a state of being superposed on a support piece made of WC base cemented carbide having Co: 8 mass%, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm Normal pressure: 4 Pa, temperature: Presence at a predetermined temperature in the range of 1200 to 1400 ° C. Holding time: 0.8 hours under high pressure sintering, and after sintering, the upper and lower surfaces are polished with a diamond grindstone, and used in a wire electric discharge machine. Then, it is divided into predetermined dimensions, and Co: 5 mass%, TaC: 5 mass%, WC: remaining composition and shape of JIS standard CNGA120212 (thickness: 4.76 mm × inscribed circle diameter: 12.7 mm 80) The brazing part (corner part) of the insert body made of a WC-base cemented carbide having a diamond) is Ti- having a composition consisting of Zr: 37.5%, Cu: 25%, Ti: the remainder in mass%. After brazing using a brazing material of Zr-Cu alloy and processing the outer periphery to a predetermined size, the cutting edge is subjected to honing processing with a width of 0.13 mm and an angle of 25 °, and further subjected to final polishing to achieve ISO. Standard CNGA12 Tool substrate b having a 412 insert shape, The filtrate was produced, respectively.

Next, on the surfaces of these tool bases (a) and (b), using ordinary chemical vapor deposition equipment, the conditions shown in Table 3, Table 4 and Table 5 were performed in the same manner as in Examples 1 and 2, and Table 15 shows. And then depositing a hard coating layer including a (Ti _1-x Al _x ) (C _y N _1-y ) layer at a target layer thickness to form a coating according to the invention shown in Table 15 Tools 27-32 were produced.
For the inventive coated tools 30 to 32, the lower layer and the upper layer shown in Table 15 were formed under the forming conditions shown in Table 3.

For comparison purposes, a conventional chemical vapor deposition apparatus was used on the surfaces of the tool bases i and b, and the present invention was coated with the conditions shown in Tables 3, 4 and 5 and the target layer thicknesses shown in Table 16. Comparative coating tools 27 to 32 shown in Table 16 were manufactured by vapor-depositing a hard coating layer in the same manner as the tools.

Further, the cross sections of the inventive coated tools 27 to 32 and comparative example coated tools 27 to 32 were measured using a scanning electron microscope, and the average layer thickness was obtained by measuring and averaging the five layer thicknesses within the observation field. It was.

The average content ratio Xave of Al and the average content ratio Yave of C in the upper TiAlCN layer were determined in the same manner as in Example 1 using an electron beam microanalyzer (Electron-Probe-Micro-Analyzer: EPMA).
Also, the lower layer TiCN crystal grains and the upper layer TiAlCN crystal grains adjacent to each other through the interface are subjected to the method of the (hkl) plane of the lower layer TiCN crystal grains using a field emission scanning electron microscope. The inclination angle formed by the line and the normal of the tool base surface is α (degrees), and the inclination angle formed by the normal of the (hkl) plane of the TiAlCN crystal grain of the upper layer and the normal of the tool base surface is β (degrees) In addition, the absolute value of the difference in inclination angle (= | α (degree) −β (degree) |) is obtained, and the number of TiCN crystal grains in the lower layer and TiAlCN grains in the upper layer, which are 5 degrees or less, is counted. The number per unit length of the interface between the upper layer and the lower layer was determined.
Further, with respect to the total area of the crystal grains in contact with the interface between the upper layer and the lower layer of the lower layer TiCN crystal grain satisfying | α (degree) −β (degree) | ≦ 5 (degrees) and the upper layer TiAlCN crystal grain. The area ratio (area%) was determined.
The average grain width W and average aspect ratio A of the crystal grains were determined in the same manner as in Example 1.
Tables 15 and 16 show these values.

Next, the coated tools 27 to 32 of the present invention and the comparative coated tools 27 to 32 will be described below in a state where any of the various coated tools is screwed to the tip of the tool steel tool with a fixing jig. The carburized and hardened alloy steel was subjected to a dry high-speed intermittent cutting test, and the flank wear width of the cutting edge was measured.
Work material: JIS · SCr420 (Hardness: HRC62) lengthwise equidistant four round bars with vertical grooves,
Cutting speed: 255 m / min,
Cutting depth: 0.12mm,
Feed: 0.1mm / rev,
Cutting time: 4 minutes
Table 17 shows the results of the cutting test.

From the results shown in Tables 6 to 8, 11 to 13, and 15 to 17, in the coated tools 1 to 32 of the present invention, the TiCN crystal grains of the lower layer and the TiAlCN crystal grains of the upper layer that are adjacent through the interface grow epitaxially. Therefore, the adhesion density of the hard coating layer is improved even when used in high-speed intermittent heavy cutting conditions that involve high heat generation and intermittent and shocking high loads on the cutting edge. Excellent chipping and peeling resistance, and excellent cutting performance over a long period of use.
On the other hand, it is clear that the comparative product coated tools 1 to 32 reach the service life in a relatively short time due to occurrence of chipping and peeling of the hard coating layer in high-speed intermittent heavy cutting.

The coated tool of the present invention is not only continuous cutting and intermittent cutting under normal conditions such as various steels and cast irons, but also severe cutting such as high-speed intermittent heavy cutting in which high loads such as intermittent and impact loads act on the cutting blade. Even under conditions, chipping and peeling of the hard coating layer are suppressed, and excellent cutting performance is demonstrated over long-term use. In addition, it can cope with the cost reduction sufficiently satisfactorily.

Claims

A hard coating layer consisting of a lower layer and an upper layer is formed on the surface of the tool base made of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body. Surface coated cutting tools
(A) The lower layer has a total average layer thickness of 1 to 20 μm composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer. And a Ti carbonitride compound layer having a crystal structure of at least a NaCl type face centered cubic crystal.
(B) The upper layer is a composite of Ti and Al having an NaCl type face centered cubic single phase crystal structure having an average layer thickness of 1 to 20 μm or a mixed phase structure of NaCl type face centered cubic and hexagonal crystals. A nitride or composite carbonitride layer,
(C) When the composite nitride or composite carbonitride layer of Ti and Al is represented by a composition formula: (Ti 1-x Al x ) (C y N 1-y ), the total amount of Ti of Ti and Al The average content ratio Xave and the average content ratio Yave (where Xave and Yave are atomic ratios) of the total amount of C and N in C are 0.60 ≦ Xave ≦ 0.95 and 0 ≦ Yave, respectively. ≦ 0.005 is satisfied,
(D) a Ti carbonitride layer having a NaCl-type face-centered cubic crystal structure in the lower layer and a Ti-Al composite nitride or composite charcoal having an NaCl-type face-centered cubic crystal structure in the upper layer For the nitride layer, the crystal orientation of each crystal grain is analyzed from the longitudinal section direction perpendicular to the tool base using an electron beam backscatter diffractometer, and the individual crystal grain is compared with the normal of the base surface. When the inclination angle formed by the normal of the crystal plane is measured, the crystal grains are adjacent to each other via the interface between the upper layer and the lower layer, and have a crystal structure of the NaCl type face centered cubic crystal of the lower layer A crystal grain whose orientation difference between the normal direction of the (hkl) plane of the grain and the normal direction of the (hkl) plane of the crystal grain having the NaCl type face centered cubic crystal structure of the upper layer is within 5 degrees Exists at the interface between the upper layer and the lower layer, and the crystal grain linear density is two Surface-coated cutting tool, characterized in that at 10μm or more.
Ti Ti-Al composite nitride or composite carbonitride layer having NaCl-type face-centered cubic crystal structure in the lower layer and Ti-Al composite nitride or composite carbonitride layer having the NaCl-type face-centered cubic crystal structure in the upper layer About the crystal orientation of the individual crystal grains from the longitudinal cross-sectional direction perpendicular to the tool substrate using an electron beam backscatter diffractometer, the crystal plane of the individual crystal grains with respect to the normal of the substrate surface When the inclination angle formed by the normal line is measured, the crystal grains adjacent to each other through the interface between the upper layer and the lower layer, and having the crystal structure of the NaCl type face centered cubic crystal of the lower layer ( The ratio of the area occupied by crystal grains whose orientation difference between the normal direction of the (hkl) plane and the normal direction of the (hkl) plane of the crystal grains having the NaCl type face centered cubic crystal structure in the upper layer is within 5 degrees Are adjacent through the interface between the upper and lower layers The surface-coated cutting tool according to claim 1, characterized in that 30% by area or more based on the total area.
When the Ti / Al composite nitride or composite carbonitride layer is observed from the longitudinal cross-sectional direction of the layer, the Ti / Al / Me composite nitride having a NaCl-type face-centered cubic structure in the layer is observed. 3. The surface according to claim 1, wherein the composite carbonitride has a columnar structure having an average grain width W of 0.1 to 2.0 μm and an average aspect ratio A of 2 to 10 of crystal grains of the composite carbonitride. Coated cutting tool.
(B) Ti-Al composite nitride having a single-phase NaCl type face-centered cubic crystal structure having an average layer thickness of 1 to 20 μm or a mixed phase structure of NaCl-type face-centered cubic crystals and hexagonal crystals, or The outermost surface layer including at least an Al 2 O 3 layer having an average layer thickness of 1 to 25 μm is further coated on the surface of the upper layer made of the composite carbonitride layer. Item 4. The surface-coated cutting tool according to any one of items 3 to 4.