JP2023148467A - Surface coated cutting tool - Google Patents

Abstract

To provide a coated tool with superior abrasion resistance in high-speed intermittent cutting.SOLUTION: A coated tool includes one or more laminate layers of a surface side TiAlCN main body layer and a substrate side TiCN layer, in which the TiAlCN main body layer contains hexagonal crystal TiAlCN grains by 70-99 area% and cubic crystal TiCN grains by at least 1 area% but less than 5 area%, and in which the TiAlCN grains are (Ti1-xAlx)(CyN1-y)(an average value of x is 0.60-0.95, an average value of y is 0.0050-0.3500). The TiCN layer contains cubic crystal grains. In the coated tool, at a minimal thickness L1min and a maximal thickness L1max of the TiAlCN main body layer, and at a minimal thickness L2min and a maximal thickness L2max of the TiCN layer, L1min is 0.5 μm or more, and L1max is 5.0 μm or less, L2min is 1.0 μm or more, and L2max is 19.0 μm or less. A total thickness L1* of the TiAlCN main body layer and a total thickness L2* of the TiCN layer satisfy L1*+L2*=1.5-20.0 μm, and 0.05×L2*≤L1*≤L2* in the coated tool.SELECTED DRAWING: Figure 1

Description

The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool).

Conventionally, a Ti-Al based composite carbonitride layer was formed as a coating layer on the surface of a tool substrate (also referred to as a substrate) such as a tungsten carbide (hereinafter referred to as WC) based cemented carbide by a vapor deposition method. There are tools that are known to exhibit excellent wear resistance.
Various proposals have been made for improving the durability of the coating layer of a coated tool coated with the Ti--Al based composite carbonitride layer.

For example, Patent Document 1 describes a multilayer structure in which a first unit layer made of Ti _1-x Al _x N and a second unit layer made of Ti _1-y Al _y N are alternately laminated as a coating layer. The first unit layer has an FCC type crystal structure, and 0<x<0.65, and the second unit layer has an HCP type crystal structure, and 0.65≦y<1. A coated tool is described that has a coating, and each of the first unit layer and the second unit layer has a thickness of 3 to 30 nm.

Furthermore, for example, Patent Document 2 discloses a lower layer consisting of a titanium aluminum nitride film mainly having an FCC structure with a thickness of 2 to 15 μm, and an upper layer consisting of an aluminum nitride film having a HCP structure with a thickness of 0.2 to 10 μm. The upper layer has a columnar crystal structure, the columnar crystals have an average cross-sectional diameter of 0.05 to 0.6 μm, and the upper layer has an X-ray diffraction peak value Ia of the (100) plane. The ratio of the X-ray diffraction peak value Ia(002) of the (100) and (002) planes satisfies the relationship Ia(002)/Ia(100)≧6, and the upper layer is epitaxially grown on the lower layer. Covered tools are listed.

Japanese Patent Application Publication No. 2015-124407 International Publication No. 2018/008554

In recent years, there has been a strong demand for labor-saving and energy-saving in cutting processes, and as a result, there has been a trend toward faster and more efficient cutting processes. Therefore, coated tools are required to have even greater resistance to abnormal damage such as chipping resistance and chipping resistance, as well as excellent wear resistance over long-term use.

However, when the coated tools proposed in Patent Documents 1 and 2 are used for high-speed interrupted cutting in which the coating layer undergoes plastic deformation, crystal grains constituting the coating layer may fall off. Abnormal wear tends to progress, and due to this, the tool life ends in a relatively short period of time.

Therefore, the present invention provides a coated tool that exhibits excellent wear resistance over a long period of use without causing abnormal wear on the coating layer even when used for high-speed interrupted cutting of alloy steel. The purpose is to

The present inventor has developed a coating layer containing Ti and Al composite nitride or composite carbonitride (hereinafter sometimes referred to as TiAlCN) that is less likely to cause abnormal damage even when used in high-speed interrupted cutting of alloy steel. We conducted extensive research on the structure. As a result, a TiAlCN layer was provided on the TiCN layer as a covering layer, and the TiAlCN layer had hexagonal high Al-containing TiAlCN crystal grains and was made of Ti carbonitride (TiCN) having a NaCl-type face-centered cubic structure. It has been found that when the crystal grains are dispersed, abnormal damage to the coating layer is difficult to progress and wear resistance is improved.

The present invention is based on this knowledge and is as follows.
"(1) A surface-coated cutting tool having a base and a coating layer provided on the base,
(a) The coating layer has one or more unit laminate layers having a layer mainly composed of TiAlCN on the tool surface side and a TiCN layer on the base side,
(b) The layer mainly composed of TiAlCN contains 70% to 99% by area of TiAlCN crystal grains having a wurtzite hexagonal structure, and 1 area of TiCN crystal grains having a NaCl face-centered cubic structure. % or more, including less than 5 area%,
(c) The TiAlCN crystal grains contained in the layer mainly composed of TiAlCN are (Ti _1-x Al _x )(C _y N _1-y ) (the average value of x is 0.60 or more and 0.95 or less, the average value of y is 0.0050 or more and 0.3500 or less),
(d) the TiCN layer has crystal grains with a NaCl-type face-centered cubic structure;
(e) In all of the unit laminate layers, the minimum and maximum thicknesses of the TiAlCN-based layer and the minimum and maximum thicknesses of the TiCN layer are L _1min , L _1max , L _2min , respectively. When L _2max , L _1min satisfies the following conditions: 0.5 μm or more, L _1max 5.0 μm or less, L _2min 1.0 μm or more, and L _2max 19.0 μm or less,
(f) When the total thickness of the layers mainly composed of TiAlCN in all the unit laminate layers and the total thickness of the TiCN layers in all the unit laminate layers are L ₁ ^* and L ₂ ^* , respectively. , L ₁ ^* +L ₂ ^* is 1.5 μm or more and 20.0 μm or less, and also satisfies the relationship 0.05×L ₂ ^* ≦L ₁ ^* ≦L ₂ ^* ,
A surface-coated cutting tool characterized by:
(2) The layer mainly composed of TiAlCN contains Cl, and the content ratio z thereof satisfies 0.005 atomic % or more and 0.500 atomic % or less. Surface coated cutting tool as described.
(3) In the layer mainly composed of TiAlCN, the area ratio occupied by crystal grains having a columnar structure with an aspect ratio of 2.0 or more is 70 area% or more (1) or (2). ) The surface-coated cutting tool described in ).
(4) Any of (1) to (3), characterized in that the coating layer has the layer mainly composed of TiAlCN and the TiCN layer on the rake face, and the TiCN layer on the flank face. The surface-coated cutting tool described in Crab. ”

The surface-coated cutting tool of the present invention exhibits excellent wear resistance over a long period of use, even when used for high-speed interrupted cutting of alloy steel.

It is a schematic diagram which shows an example of the structure of the coating layer of surface coating cutting of this invention.

The surface-coated cutting tool of the present invention will be explained in detail below. In this specification, when a numerical range is expressed as "A to B" (A and B are both numerical values), the range includes the upper limit (B) and lower limit (A), and the upper limit value When a unit is listed only in (B), the units in the upper limit (B) and lower limit (A) are the same.
Further, the composition of a compound whose composition is not specified is not limited to a stoichiometric composition, and includes any conventionally known atomic ratio.

1. Covering Layer As schematically shown in Fig. 1, the coating layer (2) of the base (1) has a layer (3) mainly composed of TiAlCN on the tool surface side and a TiCN layer on the base side (4). It has one or more unit laminate layers (5) (FIG. 1 shows two unit laminate layers).

1-1. Layer mainly composed of TiAlCN (1) Crystal structure and its area ratio The layer mainly composed of TiAlCN contains TiAlCN crystal grains having a wurtzite hexagonal structure in the longitudinal section of the coating layer at 70 area % or more and 99 area % or less , and preferably contains crystal grains of Ti carbonitride having a NaCl type face-centered cubic structure at 1% by area or more and less than 5% by area.
Here, the longitudinal section refers to a section perpendicular to a plane when the substrate is treated as a plane, ignoring minute irregularities.

If TiAlCN crystal grains having a wurtzite hexagonal crystal structure exist in a layer mainly composed of TiAlCN in an area of 70% or more, the amount of crystal grains having a wurtzite hexagonal crystal structure increases, improving lubricity. do. More preferably, it is 85 area % or more. On the other hand, if it exceeds 99 area %, the proportion of TiCN crystal grains decreases, making it difficult to impart the wear resistance provided by TiCN and to improve adhesion with the TiCN layer. Note that even if the layer mainly composed of TiAlCN contains an amorphous phase, there is no problem in achieving the above-mentioned objective.

Further, the layer mainly composed of TiAlCN preferably contains TiCN crystal grains having a NaCl type face-centered cubic structure in order to impart wear resistance and improve adhesion with the TiCN layer. If the area ratio occupied by TiCN crystal grains is 1 area % or more and less than 5 area %, the wear resistance of the layer mainly composed of TiAlCN is improved, and the adhesion between the layer mainly composed of TiAlCN and the TiCN layer is improved. do.
In addition, the crystal grain size of TiAlCN crystal grains and TiCN crystal grains in a layer mainly composed of TiAlCN (the diameter of a circle that gives an area equal to the crystal grain in the average area of the crystal grain calculated as the area weighted average value of multiple crystal grains) It is more preferable for the former to be 100 to 5000 nm and the latter to be 50 to 700 nm. Crystal grains may be unevenly distributed in this observation field.

The area ratio occupied by the crystal grains of each crystal structure described above is determined as follows.
First, a longitudinal section is prepared by polishing the coating layer using a focused ion beam system (FIB), a cross section polisher (CP), etc., and in this longitudinal section, energy dispersive X Elemental mapping was performed using energy dispersive A region that is a candidate for a Ti carbonitride crystal grain having a NaCl-type face-centered cubic structure is defined.

The regions that are candidates for TiAlCN crystal grains having a wurtzite hexagonal structure and the regions that are candidates for Ti carbonitride crystal grains that have an NaCl face-centered cubic structure were examined using a transmission electron microscope (TEM). Using a crystal orientation analyzer attached to the Electron Microscope, an electron beam is tilted, for example, by 0.5 degrees or more and 1.0 degrees or less with respect to the normal direction of the polished surface. ) While irradiating, scan each measurement point with the electron beam at an arbitrary beam diameter and interval, and continuously capture the electron diffraction pattern.

By analyzing each measurement point, in addition to determining whether the crystal is crystalline, it is also possible to determine whether the crystal has a NaCl-type face-centered cubic structure or a wurtzite-type hexagonal structure. You can find the direction. Note that the hexagonal structure of the wurtzite type can be determined more accurately by adjusting the crystal orientation of each measurement point to an orientation that is easy to identify (tilting the sample), but it is not the face-centered cubic structure of the NaCl type. The determined crystalline region may be regarded as a region with a wurtzite hexagonal crystal structure (the following explanation will explain how to consider it as a region with a wurtzite hexagonal crystal structure). For example, grain boundaries are determined for an observation field of view set to have a width of 2000 nm and a height that includes the entire thickness of the coating layer.

Note that the acquisition conditions for the electron diffraction pattern used in the measurement were, for example, an acceleration voltage of 200 kV, a camera length of 20 cm, a beam size of 2.4 nm, and a measurement step of 10.0 nm in the two-dimensional direction. At this time, the measured crystal orientation is obtained by examining the measurement surface discretely, and by representing the region up to the middle between adjacent measurement points with the measurement results, it is obtained as the orientation distribution of the entire measurement surface. be. Note that the area represented by the measurement point (hereinafter sometimes referred to as pixel) may be square-shaped.

If there is an angular difference in crystal orientation of 5 degrees or more between adjacent pixels, or if only one of the adjacent pixels exhibits a NaCl-type face-centered cubic structure, the contact area of these pixels The edges are grain boundaries. Then, a region surrounded by the sides defined as grain boundaries is defined as one crystal grain.

However, a single pixel that has an orientation difference of 5 degrees or more from all adjacent pixels, or where there is no adjacent measurement point with an NaCl-type face-centered cubic structure, is not considered a crystal grain, and two or more pixels or more are treated as crystal grains. In this way, grain boundaries are determined and crystal grains are identified.

Then, in the region that is a candidate for the TiAlCN crystal grain having the wurtzite hexagonal structure and the region that is a candidate for the Ti carbonitride crystal grain that has the NaCl type face-centered cubic structure, the wurtzite hexagonal We confirmed the distribution of crystal grains of Ti carbonitride having a crystal structure and a NaCl-type face-centered cubic structure, and found that TiAlCN crystal grains have a wurtzite-type hexagonal structure and a NaCl-type face-centered cubic structure. Identify the crystal grains of Ti carbonitride.

The area ratio occupied by the crystal grains of each crystal structure is the ratio occupied by the total area of TiAlCN crystal grains having the specified wurtzite hexagonal crystal structure to the total area of the observation field, or It is calculated as the ratio of the total area of Ti carbonitride crystal grains having the specified NaCl type face-centered cubic structure to the total area of the field of view. The average value calculated by performing similar measurements in at least three or more observation fields is defined as the area ratio occupied by the crystal grains of each crystal structure.

(2) Composition The composition of TiAlCN in a layer mainly composed of TiAlCN is _expressed by the composition formula: (Ti _{1- x Al} It is preferable that the average content ratio x satisfies a range of 0.60 or more and 0.95 or less, and the average content ratio y of C in the total amount of C and N satisfies a range of 0.0050 or more and 0.3500 or less.

The reason for this is that when x is less than 0.60, the wurtzite hexagonal structure is not stably formed and lubricity deteriorates, and when x exceeds 0.95, wear resistance deteriorates. This is because as the adhesion with the TiCN layer decreases, the adhesion with the TiCN layer decreases, causing abnormal damage such as occurrence of peeling or progression of uneven wear. Furthermore, the reason why y is set in the above range is that when it is within this range, lubricity improves, reducing the impact during cutting and improving chipping resistance, while when it deviates from this range, the adhesion with the TiCN layer increases. This is because this decreases and causes abnormal damage such as peeling or progression of uneven wear.

Note that the ratio between (Ti _1-x Al _x ) and (C _y N _1-y ) is not particularly limited, but when (Ti _1-x Al _x ) is 1, (C _y N The ratio of _1-y ) is preferably 0.8 to 1.2. The reason is that the object of the present invention can be achieved more reliably if the ratio of (C _y N _1-y ) to (Ti _1-x Al _x ) is within the above range.

When Cl is contained in a layer mainly composed of TiAlCN, it is more preferable that the content is 0.005 atomic % or more and 0.500 atomic % or less. The reason for this is that if it is less than 0.005 atom%, the lubricity may be insufficient and the wear resistance may decrease, while if it exceeds 0.500 atom%, the hardness will decrease and the rake face This is because the wear resistance is insufficient and it may wear out prematurely.

Note that the composition of the TiCN crystal grains having an NaCl-type face-centered cubic structure contained in a layer mainly composed of TiAlCN is not limited to a stoichiometric composition, and may include any conventionally known atomic ratio. include.

(3) Layer Thickness When the unit laminate is 1, the thickness of the layer mainly composed of TiAlCN is 0.5 μm or more, more preferably 5.0 μm.
When there are two or more unit laminates, the thickness of the layer mainly composed of TiAlCN in each unit laminate does not need to be the same as long as it is within the following range.
The minimum thickness and maximum thickness of the layer mainly composed of TiAlCN in all the unit laminate layers, and the minimum thickness and maximum thickness of the TiCN layer in all the unit laminate layers are L _1min and L _1max , respectively. In this case, it is preferable that L _1min satisfies 0.5 μm or more and L _1max satisfies 5.0 μm or less.

The reason why _L1 is set in this range is that if the thickness is less than 0.5 μm, the coating layer will wear out early even on the rake face, and the effect of improving wear resistance will not be exhibited. This is because if it exceeds this, the crystal grains in the TiAlCN layer will become larger and the chipping resistance of the TiAlCN layer will decrease.

(4) Aspect ratio and area ratio of crystal grains In a layer mainly composed of TiAlCN, the area ratio occupied by columnar crystal grains (both TiAlCN crystal grains and TiCN crystal grains) with an average aspect ratio of 2.0 or more is 70 area %. It is more preferable that it is above. If the area ratio occupied by columnar crystal grains with an average aspect ratio of 2.0 or more is 70 area % or more, the occurrence of chipping can be suppressed more reliably. Note that the upper limit of the aspect ratio is preferably 10.0. The reason for this is that the columnar crystal structure tends to break easily, resulting in large chipping.

1-2. TiCN Layer (1) Composition The composition of the TiCN layer is not limited to a stoichiometric composition, and includes any conventionally known atomic ratio.

(2) Crystal structure The TiCN layer preferably contains crystal grains with a NaCl-type face-centered cubic structure, and the area ratio thereof is more preferably 95% or more in the longitudinal section, and there is no restriction on the upper limit of 100%. It may be %.

(3) Layer Thickness When the unit laminate is 1, the thickness of the TiCN layer is more preferably 1.0 μm or more and 19.0 μm or less.
When there are two or more unit laminates, the thickness of the TiCN layer in each unit laminate may be the same as long as it is within the following range, but it does not need to be the same. When the minimum thickness and maximum thickness of the TiCN layer in all the unit laminate layers are _L2min and _L2max , respectively, _L2min satisfies 1.0 μm or more and _L2max satisfies 19.0 μm or less. preferable. The reason why L ₂ is set in this range is that if the layer thickness is less than 1.0 μm, the wear resistance on the flank surface will be insufficient, while if it exceeds 19.0 μm, the crystal grains in the TiCN layer will become large and the TiCN layer will deteriorate. This is because chipping resistance decreases.

When the total thickness of the TiAlCN-based layer included in the coating layer and the total thickness of the TiCN layer are L ₁ ^* and L ₂ ^* , respectively, L ₁ ^* + L ₂ ^* is 1. It is preferable that the thickness is 5 μm or more and 20.0 μm or less, and that the relationship of 0.05×L ₂ ^* ≦L ₁ ^* ≦L ₂ ^* is satisfied. Note that L ₁ ^* +L ₂ ^* represents the total thickness of all unit laminates.

The reason why L ₁ ^* +L ₂ ^* is set in this range is that if the layer thickness is less than 1.5 μm, excellent wear resistance cannot be exhibited over a long period of time. This is because if the thickness exceeds 0 μm, chipping resistance decreases. Furthermore, if L ₁ ^* deviates from the range of 0.05×L ₂ ^* ≦L ₁ ^* ≦L ₂ ^* , the lubricity of the layer mainly composed of TiAlCN cannot be sufficiently exhibited. be.

The layer thickness of the TiCN layer, which is a layer mainly composed of TiAlCN, is determined by polishing the longitudinal section of the coating layer using a focused ion beam system (FIB), a cross section polisher (CP), etc. This refers to the average value obtained by determining the layer thickness at multiple locations (5 locations) in this vertical section.

1-3. Layer structure of rake face and flank face As the coating layer, it is more preferable that the rake face has a layer mainly composed of TiAlCN and a TiCN layer, and the flank face has a TiCN layer. That is, the flank surface does not need to have a layer mainly composed of TiAlCN. The reason for this is that although a layer mainly composed of TiAlCN may be provided on the flank surface, it is better not to have a TiAlCN layer on the surface of the flank surface that rubs against the workpiece the most, as it is better to This is because the TiCN layer can be prevented from falling off, and the tool life can be further improved.

2. Other Layers If the coating layer includes one or more unit laminate layers in which the TiAlCN-based layer of the present invention is on the tool surface side and the TiCN layer is on the base side, the above object can be achieved. However, other layers may be included. Other layers include a base layer that improves adhesion between the unit laminate layer and the tool base, and an upper layer that improves wear resistance on the unit laminate layer. Good too.

The base layer is a Ti nitride layer that improves adhesion between the unit laminate layer and the tool base, and the upper layer is a Ti carbonitride layer or at least one layer of aluminum oxide. , each can be exemplified. The compositions of these layers are not necessarily limited to only the stoichiometric range, but include all conventionally known atomic ratios.

The average thickness of the base layer and the upper layer is preferably in the range of 1.0 to 10.0 μm. In addition, especially when a layer containing an aluminum oxide layer is provided as the outermost layer with a total average layer thickness of 1.0 to 10.0 μm on top of the outermost unit laminate layer, even more excellent wear resistance can be achieved. can demonstrate. The reason for this range is that if the thickness is less than 1.0 μm, the properties of the lower and upper layers may not be fully exhibited, while if it exceeds 10.0 μm, the chipping resistance of the coating layer will decrease. Sometimes I put it away.

3. Substrate (1) Material Any conventionally known substrate of this type can be used as the substrate, as long as it does not interfere with achieving the object of the present invention. Examples include cemented carbide (WC-based cemented carbide, containing WC and Co, and also containing carbonitrides such as Ti, Ta, and Nb), cermets (TiC, TiN, TiCN, etc.), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), or cBN sintered body, and any one of these is preferred.

(2) Shape There are no particular restrictions on the shape of the base as long as it can be used as a cutting tool, and examples include the shape of an insert and the shape of a drill.

4. Manufacturing method The coating layer of the present invention can be formed on a substrate by, for example, the manufacturing method (manufacturing conditions) using the chemical vapor deposition (CVD) method shown below. The unit laminate can be formed by forming a film under the conditions for forming a TiCN layer, and then forming a film under the conditions for forming a TiAlCN layer, and repeating this according to the number of unit laminates (number of layers). It can be manufactured by

<Formation conditions of TiAlCN layer>
Reaction gas composition (% represents volume %, the sum of gas group A and gas group B is 100 volume %)
Gas group A NH ₃ : 0.50 to 1.50%, N ₂ : 0.0 to 5.0%,
CH ₄ : 0.5-5.0%, C ₂ H ₄ : 1.0-10.0%, H ₂ : 20.0-40.0%,
Gas group B AlCl ₃ : 0.11 to 0.70%, Al(CH ₃ ) ₃ : 0.00 to 0.25%,
TiCl ₄ : 0.10-0.20%, N ₂ : 2.0-10.0%,
CH ₃ CN: 0.10 to 0.50%, CH ₄ : 0.0 to 1.0%,
C ₂ H ₄ : 0.0-1.5%, H ₂ : Remaining reaction atmosphere pressure: 4.5-5.0 kPa
Reaction atmosphere temperature: 800-850℃
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.26 to 0.40 seconds Phase difference between gas supply A and gas supply B: 0.10 to 0.20 seconds

<TiCN layer formation conditions>
Reaction gas composition (% represents volume %, the sum of gas group A and gas group B is 100 volume %)
Gas group A N ₂ : 0.0 to 5.0%, H ₂ : 20.0 to 40.0%,
Gas group B TiCl ₄ : 1.0 to 5.0%, CH ₃ CN: 0.5 to 1.5%,
N ₂ : 25.0 to 40.0%, H ₂ : remainder Reaction atmosphere pressure: 5.0 to 10.0 kPa
Reaction atmosphere temperature: 850-900℃
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.26 to 0.40 seconds Phase difference between gas supply A and gas supply B: 0.10 to 0.20 seconds Film-forming gas composition , reaction atmosphere pressure, reaction atmosphere temperature, supply cycle, gas supply time per cycle, and phase difference between supply of gas group A and supply of gas group B are set values.

Next, examples will be described, but the present invention is not limited to these examples. That is, as an example of the coated tool of the present invention, an application to an insert cutting tool using WC-based cemented carbide as the base will be described. The same applies when applied to drills, end mills, etc.

As raw material powders, WC powder _, TiC powder, ZrC powder, TaC powder, NbC powder, _Cr3C2 powder, TiN powder, and Co powder were prepared, and these raw material powders were blended into the composition shown in Table 1, Furthermore, wax was added and mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, and then press-molded into a powder compact of a predetermined shape at a pressure of 98 MPa. Vacuum sintering is performed under conditions of holding at a predetermined temperature for 1 hour, and after sintering, WC-based cemented carbide bases A to C with the insert shape of SEMT13T3AGSN manufactured by Mitsubishi Materials Corporation, and inserts of ISO standard CNMG120408. Each of substrates D to F made of WC-based cemented carbide having a shape was manufactured.

Next, each layer was formed on the surfaces of these substrates A to F by CVD using a CVD apparatus to obtain coated tools 1 to 12 of the present invention shown in Table 6.
The film forming conditions are as described in Tables 2 and 3, and are generally as follows.

<Formation of TiAlCN layer>
Reaction gas composition (% represents volume %, the sum of gas group A and gas group B is 100 volume %)
Gas group A NH ₃ : 0.50 to 1.50%, N ₂ : 0.0 to 5.0%,
CH ₄ : 0.5-5.0%, C ₂ H ₄ : 1.0-10.0%, H ₂ : 20.0-40.0%,
Gas group B AlCl ₃ : 0.11 to 0.70%, Al(CH ₃ ) ₃ : 0.00 to 0.25%,
TiCl ₄ : 0.10-0.20%, N ₂ : 2.0-10.0%,
CH ₃ CN: 0.10 to 0.50%, CH ₄ : 0.0 to 1.0%,
C ₂ H ₄ : 0.0-1.5%, H ₂ : Remaining reaction atmosphere pressure: 4.5-5.0 kPa
Reaction atmosphere temperature: 800-850℃
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.26 to 0.40 seconds Phase difference between gas supply A and gas supply B: 0.10 to 0.20 seconds

<Formation of TiCN layer>
Reaction gas composition (% represents volume %, the sum of gas group A and gas group B is 100 volume %)
Gas group A N ₂ : 0.0 to 5.0%, H ₂ : 20.0 to 40.0%,
Gas group B TiCl ₄ : 1.0 to 5.0%, CH ₃ CN: 0.5 to 1.5%,
N ₂ : 25.0 to 40.0%, H ₂ : remainder Reaction atmosphere pressure: 5.0 to 10.0 kPa
Reaction atmosphere temperature: 800-900℃
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.26 to 0.40 seconds Phase difference between gas supply A and gas supply B: 0.10 to 0.20 seconds

Further, for coated tools 1 to 12 of the present invention, the lower layer and upper layer shown in Table 5 were formed under the film forming conditions shown in Table 4.

For comparison purposes, comparative coated tools 1 to 6 shown in Table 7 were manufactured by forming films on the surfaces of substrates A to F using a CVD apparatus under the conditions shown in Tables 2 and 3. Further, for comparative coated tools 1 to 6, the upper layer shown in Table 5 was formed under the film forming conditions shown in Table 4.

The coated tools 1 to 12 of the present invention and the comparative coated tools 1 to 6 were tested by the method described above to determine the composition of each layer, layer thickness, area ratio of cubic crystal structure and hexagonal crystal grain, and area ratio of columnar crystal grain. The results are shown in Table 6. Note that for coated tools 1 to 12 of the present invention, the crystal grain sizes of the TiAlCN crystal grains and the TiCN crystal grains were within the above-mentioned preferred range.

For comparison process C'*, no TiAlCN layer was provided.

In Table 5, "-" indicates that there is no corresponding layer.

In Table 6,
"-" indicates that there is no applicable item, "○" indicates that it applies, and "×" indicates that it does not apply.
Hexagonal (area %) is the area ratio (%) of crystal grains that have a wurtzite hexagonal crystal structure.
Cubic crystal (area %) is the area ratio (%) of crystal grains having a NaCl-type face-centered cubic structure.
represents.
Further, when the number of stacked layers is 1 (the stacked unit is 1), L _1min = L _1max = L ₁ ^* , L _2min = L _2max = L ₂ ^* .

Next, the following cutting test 1 (coated tools 1 to 6 of the present invention, comparative coated tools 1 to 4) and cutting test 2 (coated tools 1 to 4 of the present invention) were conducted for the coated tools 1 to 12 of the present invention and comparative coated tools 1 to 8. 7 to 12 and comparative coated tools 5 to 8), and the results are shown in Tables 7 and 8, respectively.

Cutting test 1: Dry high speed face milling, center cut cutting Cutter diameter: 80 mm, single blade cutting Work material: JIS SCM440 width 60 mm, length 200 mm block material Rotation speed: 1592/min
Cutting speed: 400m/min
Cut: 1.5mm
Single blade feed rate: 0.3mm/blade Cutting time: 6 minutes (normal cutting speed is 200m/min)

Cutting test 2: Dry high-speed interrupted cutting Work material: JIS SCM440 8 round bars with longitudinal grooves equally spaced in the length direction Cutting speed: 400 m/min
Depth: 1.0mm
Feed: 0.2mm/rev
Cutting time: 6 minutes (normal cutting speed is 150 to 200 m/min)

In Tables 7 and 8, "*: Cutting time (minutes) until the end of life" of the comparative coated tool indicates the cutting time (minutes) until the end of the life due to chipping.

From the results shown in Tables 7 and 8, coated tools 1 to 12 of the present invention all have coating layers with excellent wear resistance, so even when used for high-speed interrupted cutting, they last for a long time. Demonstrates excellent wear resistance over a long period of time. On the other hand, comparative coated tools 1 to 8, which do not satisfy at least one of the requirements specified for the coated tools of the present invention, will chip when used in high-speed interrupted cutting, and their service life will be shortened in a short period of time. It has been reached.

As mentioned above, the coated tool of the present invention can be used as a coated tool for high-speed interrupted cutting, and also exhibits excellent wear resistance over a long period of time, so it can improve the performance of cutting equipment. In addition, it is possible to achieve satisfactory measures for labor saving and energy saving in cutting processing, as well as cost reduction.

1 Base 2 Covering layer 3 Layer mainly composed of TiAlCN 4 TiCN layer 5 Laminated unit layer

Claims (4)

A surface-coated cutting tool having a base body and a coating layer provided on the base body,
(a) The coating layer has one or more unit laminate layers having a layer mainly composed of TiAlCN on the tool surface side and a TiCN layer on the base side,
(b) The layer mainly composed of TiAlCN contains 70% to 99% by area of TiAlCN crystal grains having a wurtzite hexagonal structure, and 1 area of TiCN crystal grains having a NaCl face-centered cubic structure. % or more, including less than 5 area%,
(c) The TiAlCN crystal grains contained in the layer mainly composed of TiAlCN are (Ti _1-x Al _x )(C _y N _1-y ) (the average value of x is 0.60 or more and 0.95 or less, the average value of y is 0.0050 or more and 0.3500 or less),
(d) the TiCN layer has crystal grains with a NaCl-type face-centered cubic structure;
(e) In all of the unit laminate layers, the minimum and maximum thicknesses of the TiAlCN-based layer and the minimum and maximum thicknesses of the TiCN layer are L _1min , L _1max , L _2min , respectively. When L _2max , L _1min satisfies the following conditions: 0.5 μm or more, L _1max 5.0 μm or less, L _2min 1.0 μm or more, and L _2max 19.0 μm or less,
(f) When the total thickness of the layers mainly composed of TiAlCN in all the unit laminate layers and the total thickness of the TiCN layers in all the unit laminate layers are L ₁ ^* and L ₂ ^* , respectively. , L ₁ ^* +L ₂ ^* is 1.5 μm or more and 20.0 μm or less, and also satisfies the relationship 0.05×L ₂ ^* ≦L ₁ ^* ≦L ₂ ^* ,
A surface-coated cutting tool characterized by: The surface according to claim 1, wherein the layer mainly composed of TiAlCN contains Cl, and the content ratio z thereof satisfies 0.005 atomic % or more and 0.500 atomic % or less. Coated cutting tools. The surface according to claim 1 or 2, wherein in the layer mainly composed of TiAlCN, an area ratio occupied by crystal grains having a columnar structure with an aspect ratio of 2.0 or more is 70 area% or more. Coated cutting tools. The surface according to any one of claims 1 to 3, characterized in that the coating layer includes the layer mainly composed of TiAlCN and the TiCN layer on the rake face, and the TiCN layer on the flank face. Coated cutting tools.

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