JP2009248238A - Surface-coated cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool which enables the life of the surface-coated cutting tool to be prolonged. <P>SOLUTION: The surface-coated cutting tool includes a surface-coated layer formed by alternately laminating a first coating layer and a second coating layer at the surface of a base material. One or more A layers and one or more B layers are alternately laminated in the first coating layer. The A layer is made of a nitride containing Al and Cr, and a ratio of atomicity of Cr is >0.1 and ≤0.4. The B layer is made of a nitride containing Al and Ti, and a ratio of atomicity of Ti is ≥0.2 and ≤0.6. One or more C layers and one or more D layers are alternately respectively laminated in the second coating layer. The C layer is made of a nitride containing Ti and Si, and a ratio of atomicity of Si is >0.05 and ≤0.3. The D layer is made of a nitride containing Ti and Cr, and a ratio of atomicity of Cr is ≥0.05 and ≤0.3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface-coated cutting tool, and particularly to a surface-coated cutting tool that can extend the life of a surface-coated cutting tool.

  Conventionally, surface-coated cutting tools in which a surface coating layer is formed on the surface of a substrate have been used for the purpose of protecting the surface of the substrate and further improving various properties such as wear resistance and toughness. .

  In addition, as a trend of surface-coated cutting tools in recent years, dry processing that does not use cutting fluid and semi-dry processing that minimizes the amount of use are required from the viewpoint of global environmental conservation, and work materials have been developed through the development of new materials. Are diversified, and the cutting speed and the feeding speed are higher in order to further improve the processing efficiency. Due to these trends, the cutting edge temperature of surface-coated cutting tools tends to be exposed to higher temperatures during the cutting of work materials, and the characteristics required for the surface coating layer of surface-coated cutting tools are becoming stricter. It is.

  The properties required for the surface coating layer of a surface-coated cutting tool are required not only for stability at high temperatures (oxidation resistance and adhesion), but also for wear resistance related to the life of the surface-coated cutting tool. It is becoming. That is, the improvement in the hardness of the surface coating layer at a high temperature and the lubrication characteristics of the surface coating layer in place of the lubricating oil have come to be regarded as important.

  For example, Japanese Patent No. 3781374 (Patent Document 1) proposes the use of a nitride containing Al and Cr instead of TiAlN that has been used as a hard surface coating layer of a surface-coated cutting tool. . A nitride containing Al and Cr is excellent in stability at high temperature as compared with TiAlN, but tends to have a large residual stress. Therefore, when a nitride layer containing Al and Cr is used for the surface coating layer, there is a problem that the adhesion to the base material and the other surface coating layer becomes insufficient.

Therefore, for example, International Publication No. 2006/070730 pamphlet (Patent Document 2) includes a nitride layer containing Al and Cr, a nitride layer containing Ti, Al, and Si in order to solve such a problem. A surface coating layer having a structure in which the layers are alternately laminated has been proposed.
Japanese Patent No. 3781374 International Publication No. 2006/070730 Pamphlet

  By adopting the structure of the surface coating layer as in International Publication No. 2006/070730 (Patent Document 2), the problem of insufficient adhesion to the substrate and other surface coating layers has been almost solved. However, the following new problems occurred.

  That is, the surface coating layer having this configuration always contains Al, and is formed using an alloy target as a raw material. However, since the melting point of Al is about 660 ° C., the melting point of Al is very low as compared with, for example, about 1688 ° C. that is the melting point of Ti and about 1875 ° C. that is the melting point of Cr. Therefore, when a surface coating layer is formed on the surface of the base material using an alloy target containing Al, there is a problem that molten particles (sometimes called droplets or macro particles) are likely to be generated. .

  When the molten particles are generated during the formation of the surface coating layer, projections made of the molten particles are formed on the surface of the surface coating layer, and the surface roughness of the surface coating layer is deteriorated. When the surface of the workpiece is cut using a surface-coated cutting tool in which the surface coating layer having the projection is formed on the surface of the substrate, the workpiece is likely to be welded to the projection. There was a problem.

  When the work material is welded to the protrusions on the surface of the surface coating layer, part of the surface coating layer is destroyed or dropped when the welded work material is removed, and the entire surface coating layer is completely removed. In some cases, the material peeled off. In this case, the chipping of the cutting edge of the surface-coated cutting tool results in a decrease in the life of the surface-coated cutting tool, which is a problem.

  In view of the above circumstances, an object of the present invention is to provide a surface-coated cutting tool capable of extending the life of the surface-coated cutting tool.

  The present invention is a surface-coated cutting tool comprising a substrate and a surface coating layer in which a first coating layer and a second coating layer are alternately laminated on the surface of the substrate, wherein the first coating layer is , Including a first alternating layer in which one or more A layers and B layers are alternately stacked, and the A layer is made of a nitride containing Al and Cr, and the total number of metal atoms constituting the A layer is 1 And the ratio of the number of Cr atoms is greater than 0.1 and less than or equal to 0.4, the B layer is made of a nitride containing Al and Ti, and the total number of metal atoms constituting the B layer is 1. The ratio of the number of Ti atoms is 0.2 to 0.6, and the second coating layer is a second alternating layer in which one or more C layers and D layers are alternately stacked. The C layer is made of a nitride containing Ti and Si, and the ratio of the number of Si atoms when the total number of metal atoms constituting the C layer is 1 is 0.05. The D layer is made of a nitride containing Ti and Cr, and the ratio of the number of Cr atoms when the total number of metal atoms constituting the D layer is 1 is 0.05 or more. It is a surface-coated cutting tool that is 0.3 or less.

  Here, in the surface-coated cutting tool of the present invention, it is preferable that each thickness of the first coating layer and the second coating layer is 0.1 μm or more and 1 μm or less.

  Moreover, in the surface-coated cutting tool of this invention, it is preferable that each thickness of A layer, B layer, C layer, and D layer is 1 nm or more and 50 nm or less.

  In the surface-coated cutting tool of the present invention, the first intermediate transition layer is formed between the A layer and the B layer in the first coating layer, and the composition of the first intermediate transition layer is the first intermediate transition layer. In the thickness direction of the layer, it is preferable that the composition changes continuously so as to approach the composition of the layer in contact with the upper side of the first intermediate transition layer from the composition of the layer in contact with the lower side of the first intermediate transition layer.

  In the surface-coated cutting tool of the present invention, the second intermediate transition layer is formed between the C layer and the D layer in the second coating layer, and the composition of the second intermediate transition layer is the second intermediate transition layer. In the thickness direction of the layer, it is preferable that the composition changes continuously so as to approach the composition of the layer in contact with the upper part of the second intermediate transition layer from the composition of the layer in contact with the lower part of the second intermediate transition layer.

  In the surface-coated cutting tool of the present invention, the surface coating layer preferably has an average residual stress of −8 GPa or more and 0 GPa or less.

  In the surface-coated cutting tool of the present invention, it is preferable that the residual stress of the surface-coated layer increases in absolute value as the distance from the substrate increases in the thickness direction of the surface-coated layer.

  In the surface-coated cutting tool of the present invention, the crystal structure of the surface-coated layer is preferably a cubic crystal.

  ADVANTAGE OF THE INVENTION According to this invention, the surface coating cutting tool which can prolong the lifetime of a surface coating cutting tool can be provided.

  Hereinafter, embodiments of the present invention will be described. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Configuration of surface coated cutting tool>
In FIG. 1, the typical expanded sectional view of an example of the surface coating cutting tool of this invention is shown. Here, the surface-coated cutting tool 1 has a configuration including a base material 2 and a surface coating layer 3 that is a layer for coating the surface of the base material 2 on the surface of the base material 2.

  FIG. 2 shows an example of a schematic cross section taken along the line XX of FIG. As shown in FIG. 2, the surface coating layer 3 is formed on the surface of the base material 2, and the surface coating layer 3 has a configuration in which the first coating layer 4 and the second coating layer 5 are alternately laminated. have.

<Base material>
As the base material 2, for example, a conventionally known base material for a surface-coated cutting tool can be used without any particular limitation. Examples of the base material 2 include cemented carbide (including WC-based cemented carbide, WC, Co, or further added with carbonitride such as Ti, Ta, Nb, etc.), cermet (TiC , TiN, TiCN, etc.), high-speed steel, ceramics (such as titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide and mixtures thereof), cubic boron nitride sintered body or A diamond sintered body or the like can be used.

  Further, for example, when a cemented carbide is used for the base material 2, an abnormal phase called a free carbon or η phase may be included in the structure of the cemented carbide.

  Moreover, as the base material 2, you may use what the surface of the base material 2 modified | denatured. For example, when a cemented carbide is used for the base material 2, a deβ layer may be formed on the surface of the base material 2. Further, when a cermet is used for the base material 2, a surface hardened layer may be formed on the surface of the base material 2.

<Surface coating layer>
For example, as shown in FIG. 2, the surface coating layer 3 may include other layers as long as it includes a laminate in which one or more first coating layers 4 and second coating layers 5 are alternately laminated. Good. Examples of such other layers include the lowermost layer in contact with the surface of the substrate 2 and / or the uppermost layer of the layers constituting the surface coating layer 3 among the layers constituting the surface coating layer 3. However, it is not limited to these layers.

  Further, the surface coating layer 3 is not limited to the case where the entire surface of the substrate 2 is covered, and there may be a portion where the surface coating layer 3 is not partially formed on the surface of the substrate 2. Further, the configuration of the surface coating layer 3 may be different between a portion of the surface coating layer 3 on the surface of the substrate 2 and another surface coating layer 3.

  In the present invention, the number of the first coating layers 4 and the number of the second coating layers 5 in the surface coating layer 3 are the same as those of the first coating layer 4 and the second coating layer 5 constituting the surface coating layer 3, respectively. This means the number of stacked layers. For example, a configuration in which the surface coating layer 3 is laminated in the order of the first coating layer 4, the second coating layer 5, the first coating layer 4, the second coating layer 5, and the first coating layer 4 in this order from the substrate 2 side. In this case, the number of the first coating layers 4 in the surface coating layer 3 is three, and the number of the second coating layers is two.

  Further, in the surface coating layer 3, the lamination of the first coating layer 4 and the second coating layer 5 may be started from the first coating layer 4 or may be started from the second coating layer 5 (that is, In the surface coating layer 3, the layer closest to the substrate 2 side may be the first coating layer 4 or the second coating layer 5. Further, the lamination in the surface coating layer 3 may be terminated at the first coating layer 4 or may be terminated at the second coating layer 5 (that is, in the surface coating layer 3 from the side of the base material 2). The layer located far away may be the first coating layer 4 or the second coating layer 5).

  The total thickness of the surface coating layer 3 is preferably 0.5 μm or more and 20 μm or less. When the entire thickness of the surface coating layer 3 is less than 0.5 μm, the thickness of the surface coating layer 3 is too thin and the life of the surface coating cutting tool 1 of the present invention tends to be shortened. When the total thickness exceeds 20 μm, the surface coating layer 3 tends to chip during cutting of the surface coated cutting tool 1 of the present invention, and the life of the surface coated cutting tool 1 of the present invention tends to be shortened.

  Moreover, from the viewpoint of extending the life of the surface-coated cutting tool 1 of the present invention, the entire thickness of the surface-coated layer 3 is more preferably 15 μm or less, and further preferably 10 μm or less.

  Further, from the viewpoint of extending the life of the surface-coated cutting tool 1 of the present invention, the entire thickness of the surface-coated layer 3 is more preferably 1 μm or more, and further preferably 1.5 μm or more.

  In the present invention, the entire thickness of the surface coating layer 3, the thickness of each layer to be described later, and the number of laminated layers are all cut from the surface-coated cutting tool 1 of the present invention, and the cross section is SEM (scanning electron microscope). Or it can obtain | require by observing using TEM (transmission electron microscope). Moreover, the composition of each layer as will be described later constituting the surface coating layer 3 can be measured using an XPS (X-ray photoelectron spectrometer).

Furthermore, the lifetime of the surface-coated cutting tool 1 of the present invention from the viewpoint of prolonged, the thickness h ₂ of the first covering layer 4 of thickness h ₁ and the second covering layer 5 constituting the surface coating layer 3 each 0. It is preferable that they are 1 micrometer or more and 1 micrometer or less.

  In FIG. 3, the typical expanded sectional view of an example of the surface coating layer 3 used for this invention is shown. Here, the first coating layer 4 constituting the surface coating layer 3 includes a first alternating layer in which one or more A layers 6 and B layers 7 are alternately laminated, and the second coating layer 5. Includes a second alternating layer in which one or more C layers 8 and D layers 9 are alternately stacked.

  Here, the A layer 6 is made of a nitride containing Al (aluminum) and Cr (chromium), and when the total number of metal atoms constituting the A layer 6 is 1, the ratio of the number of Cr atoms is 0. It is larger than 1 and 0.4 or less.

  The B layer 7 is made of a nitride containing Al (aluminum) and Ti (titanium), and the ratio of the number of Ti atoms when the total number of metal atoms constituting the B layer 7 is 1 is 0.2. It is 0.6 or less.

  The C layer 8 is made of a nitride containing Ti (titanium) and Si (silicon), and the ratio of the number of Si atoms when the total number of metal atoms constituting the C layer 8 is 1 is 0.05. Larger than 0.3.

  The D layer 9 is made of a nitride containing Ti (titanium) and Cr (chromium), and the ratio of the number of Cr atoms when the total number of metal atoms constituting the D layer 9 is 1 is 0.05 or more. 0.3 or less.

  As described above, in the surface-coated cutting tool 1 of the present invention, the first coating layer 4 is formed adjacent to the second coating layer 5 having an effect of improving the surface roughness, so that the molten particles have a low melting point as a constituent element. The first covering layer 4 containing Al that is liable to generate is suppressed, and the stability, wear resistance, and chipping resistance at the time of cutting at a high temperature are excellent as compared with the conventional TiAlN. It is possible to sufficiently exhibit the excellent effects of the coating layer 4. As a result, the stability of the surface-coated cutting tool 1 at a high temperature has been dramatically improved, and the life of the surface-coated cutting tool 1 has been successfully extended.

  In addition, since the second coating layer 5 having an effect of improving the surface roughness does not contain Al, by forming such a second coating layer 5 adjacent to the first coating layer 4 (particularly, the two second coating layers 5 2), the coarsening of crystal growth in the first coating layer 4 containing Al can be effectively prevented, and the first coating layer 4 It is considered that the crystal structure of can be further refined.

  Furthermore, since the second coating layer 5 is also formed adjacent to the first coating layer 4 having a composition different from that of the second coating layer 5, as a result, the crystal growth of the second coating layer 5 itself is simultaneously increased. Can be suppressed.

  Therefore, even under cutting conditions in which a high load is applied at a high temperature, it is possible to sufficiently suppress the occurrence of cracks generated on the surface of the surface coating layer 3 in the direction of the substrate 2, thereby Chipping of the cutting edge of the coated cutting tool 1 can be extremely effectively prevented. In particular, this point is a problem that the conventional patent document 2 has (that is, since the surface coating layer always contains Al, the crystal structure of the surface coating layer can be sufficiently refined). It is possible to solve the problem that it cannot be performed), and it has extremely large industrial applicability.

  By adopting the configuration of the surface coating layer 3 of the surface-coated cutting tool 1 of the present invention, it is considered that the development of cracks in the surface coating layer 3 is suppressed for the following reason. In other words, the first coating layer 4 and the second coating are not developed due to the refinement of the crystal structure of the first coating layer 4, and cracks generated in the surface coating layer 3 do not develop into large-scale delamination with the base material 2. Crack propagation is effective at the interface with the layer 5, the interface between the A layer 6 and the B layer 7 in the first coating layer 4, and the interface between the C layer 8 and the D layer 9 in the second coating layer 5, respectively. This is presumed to be blocked by

  As described above, the surface-coated cutting tool 1 of the present invention has excellent cutting stability at high temperatures and can suppress chipping of the cutting edge. Further, the surface-coated cutting tool 1 is resistant to cutting even under high temperature and high load. Since it is possible to achieve both high wear resistance and chipping resistance, it is considered that the life can be greatly prolonged.

<A layer>
The A layer 6 is made of a nitride containing Al and Cr, but has high oxidation resistance because it contains Al. Further, since the A layer 6 contains not only Al but also Cr, the oxidation resistance is further enhanced. Further, in the A layer 6, even if the Al content becomes high, since it contains Cr, the crystal structure of the A layer 6 tends to be cubic and hardened. These characteristics of the A layer 6 are exhibited even at high temperatures, and exhibit sufficient high temperature stability. The A layer 6 may contain elements other than nitrogen as long as it contains Al and Cr.

  The ratio of the number of Cr atoms when the total number of metal atoms constituting the A layer 6 is 1 is greater than 0.1 and 0.4 or less. Here, when the ratio of the number of Cr atoms contained in the A layer 6 is 0.1 or less, the crystal structure tends to be hexagonal and low hardness, and when larger than 0.4, The hardness of A layer 6 will fall. Further, from the viewpoint of increasing the hardness of the A layer 6, the ratio of the number of Cr atoms in the A layer 6 is preferably 0.2 or more and 0.35 or less.

  In the present invention, the “metal atom” means hydrogen, helium, neon, argon, krypton, xenon, radon, fluorine, chlorine, bromine, iodine, astatine, oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic, An atom of an element other than antimony and carbon.

  Further, in the A layer 6, when the total number of metal atoms including Al and Cr is 1, the ratio of the number of nitrogen atoms is preferably 0.8 or more and 1.5 or less. When the ratio of the number of nitrogen atoms is less than 0.8, the hardness of the A layer 6 tends to decrease, and when it exceeds 1.5, the hardness of the A layer 6 tends to decrease.

<B layer>
The B layer 7 is made of a nitride containing Al and Ti, and may contain elements other than nitrogen as long as Al and Ti are contained. Thus, since the B layer 7 contains Ti together with Al, it has a small residual stress and functions as a stress relaxation layer. Moreover, since the crystal structure of the B layer 7 is a cubic crystal, it exhibits sufficient high-temperature stability.

  Further, the ratio of the number of Ti atoms when the total number of metal atoms constituting the B layer 7 is 1 is 0.2 or more and 0.6 or less. If the ratio of the number of Ti atoms in the B layer 7 exceeds 0.6, the hardness of the B layer 7 decreases to promote wear, and if it is less than 0.2, the residual stress is sufficiently small. Can not do. From the viewpoint of increasing the hardness of the B layer 7, the ratio of the number of Ti atoms in the B layer 7 is preferably 0.3 or more and 0.5 or less.

  Further, in the B layer 7, when the total number of metal atoms including Al and Ti is 1, the ratio of the number of nitrogen atoms is preferably 0.8 or more and 1.5 or less. When the ratio of the number of nitrogen atoms is less than 0.8, the hardness of the B layer 7 tends to decrease, and when it exceeds 1.5, the hardness of the B layer 7 tends to decrease.

<C layer>
The C layer 8 is made of a nitride containing Ti and Si, but has high oxidation resistance because it contains Si. In addition, since the C layer 8 contains Si, it forms a microstructure in which Ti-rich ultrafine nanocrystal grains are dispersed in a Si-based amorphous matrix, so that the hardness is extremely high. Tend to. These characteristics of the C layer 8 are exhibited even at a high temperature of 1000 ° C. or higher, and show sufficient high temperature stability. The C layer 8 may contain elements other than nitrogen as long as it contains Ti and Si.

  When the total number of metal atoms constituting the C layer 8 is 1, the ratio of the number of Si atoms is greater than 0.05 and 0.3 or less. Here, when the ratio of the number of Si atoms in the C layer 8 is 0.05 or less, it does not become an ultrafine nanocrystal structure but tends to be low hardness, and when it is larger than 0.3, The toughness of the C layer 8 is lowered, and the surface-coated cutting tool 1 is easily chipped. Further, from the viewpoint of increasing the hardness of the C layer 8, the ratio of the number of Si atoms in the C layer 8 is preferably 0.1 or more and 0.2 or less.

  In the C layer 8, when the total number of metal atoms including Ti and Si is 1, the ratio of the number of nitrogen atoms is preferably 0.8 or more and 1.5 or less. When the ratio of the number of nitrogen atoms is less than 0.8, the hardness of the C layer 8 tends to decrease, and when it exceeds 1.5, the hardness of the C layer 8 tends to decrease.

<D layer>
The D layer 9 is made of a nitride containing Ti and Cr, and may contain an element other than nitrogen as long as it contains Ti and Cr. Thus, since the D layer 9 contains Cr, it has characteristics excellent in oxidation resistance, and since it contains a relatively large amount of Ti, it has a small residual stress and functions as a stress relaxation layer. ing. Further, the crystal structure of the D layer 9 is a cubic crystal and exhibits sufficient high temperature stability.

  The ratio of the number of Cr atoms when the total number of metal atoms constituting the D layer 9 is 1 is 0.05 or more and 0.3 or less. When the ratio of the number of Cr atoms in the D layer 9 exceeds 0.3, the hardness of the D layer 9 tends to decrease and the wear tends to accelerate, and when it is less than 0.05, sufficient oxidation resistance is obtained. There is a risk of not having. From the viewpoint of increasing the hardness of the D layer 9, the ratio of the number of Cr atoms in the D layer 9 is preferably 0.1 or more and 0.2 or less.

  In the D layer 9, when the total number of metal atoms including Ti and Cr is 1, the ratio of the number of nitrogen atoms is preferably 0.8 or more and 1.5 or less. When the ratio of the number of nitrogen atoms is less than 0.8, the hardness of the D layer 9 tends to decrease, and when it exceeds 1.5, the hardness of the D layer 9 tends to decrease.

<Other elements that can be contained in the A layer, the B layer, the C layer, and the D layer>
In the present invention, at least one of the A layer 6, the B layer 7, the C layer 8 and the D layer 9 may contain vanadium at a content of less than 30 atomic% in atomic%. In this case, even if the surface of the A layer 6, the B layer 7, the C layer 8 and / or the D layer 9 is oxidized in a high temperature environment at the time of cutting of the surface-coated cutting tool 1 of the present invention, the vanadium oxide Since the melting point is low, the oxide of vanadium acts as a lubricant during cutting, and as a result, it tends to be able to suppress the fusion of the work material to the surface-coated cutting tool 1 of the present invention.

  In the present invention, the vanadium content is preferably less than 15 atomic%. In this case, fusion of the work material to the surface-coated cutting tool 1 of the present invention can be suppressed. Further, when vanadium is contained in the A layer 6 and / or the B layer 7, the hardness of the A layer 6 and / or the B layer 7 containing vanadium can be increased. In the present invention, “atomic%” means the ratio (%) of the number of atoms to the total number of atoms of metal atoms constituting the layer.

  In the present invention, at least one of the A layer 6, the B layer 7, the C layer 8 and the D layer 9 may contain boron in an atomic percent of less than 10 atomic percent. In this case, the mechanism is unknown, but the hardness of the layer containing boron tends to be further increased. Further, boron oxide formed by surface oxidation at the time of cutting tends to precipitate at the grain boundaries when the Al nitride in the A layer 6 transforms into Al oxide and densify the crystal. This is also preferable. Furthermore, since the melting point of the oxide of boron is low, it acts as a lubricant during cutting and tends to suppress welding of the work material.

  In the present invention, Si may be contained in at least one of the A layer 6, the B layer 7 and the D layer 9 in atomic percent of less than 10 atomic percent. In this case, the hardness of the A layer 6, B layer 7 and / or D layer 9 containing Si tends to increase, and the crystal structure of the A layer 6, B layer 7 and / or D layer 9 containing Si is also high. It tends to be miniaturized.

<Thickness of A layer, B layer, C layer, D layer>
The thickness h _b of thickness h _a, and B layer 7 of the A layer 6 constituting the first covering layer 4, and the thickness h _d is the thicknesses h _c and D layer 9 of C layer 8 in which the second constituting the coating layer 5 It is preferably 1 nm or more and 50 nm or less. By making the thicknesses of the A layer 6, the B layer 7, the C layer 8, and the D layer 9 within a range of 1 nm or more and 50 nm or less, the progress of cracks generated on the surface of the surface coating layer 3 (in the direction of the substrate 2) Tend to be most effectively suppressed.

Further, when the thickness h _a of the A layer 6, the thickness h _b of the B layer 7, the thickness h _c and the thickness h _d of the D layer 9 of C layer 8 are each less than 1nm is, A layer 6 and the B layer 7 The C layer 8 and the D layer 9 are mixed together, and the effect obtained by alternately laminating the A layer 6 and the B layer 7 and the effect obtained by alternately laminating the C layer 8 and the D layer 9 are obtained. It tends to be impossible. The thickness h _a of the A layer 6, the thickness h _b of the B layer 7, the crack extension of the surface coating layer 3 in the case where the thickness h _d of the thickness h _c and D layer 9 of C layer 8 is more than 50nm, respectively It tends to be difficult to obtain a suppression effect.

  In the present invention, the thicknesses of the A layer 6, the B layer 7, the C layer 8, and the D layer 9 in the surface coating layer 3 are the same for each layer included in the first coating layer 4 or the second coating layer 5. The thickness may be substantially the same or different.

<Intermediate transition layer>
In FIG. 4, the typical expanded sectional view of the other example of the surface coating layer 3 in this invention is shown. Here, a first intermediate transition layer 10 is stacked between the A layer 6 and the B layer 7, and a second intermediate transition layer 11 is stacked between the C layer 8 and the D layer 9. .

  The first intermediate transition layer 10 and the second intermediate transition layer 11 are formed above the first intermediate transition layer 10 in the thickness direction of the first intermediate transition layer 10 from the composition of the layer in contact with the lower side of the first intermediate transition layer 10. The composition continuously changes so as to approach the composition of the contacting layer.

  The composition of the second intermediate transition layer 11 is that of the layer in contact with the upper part of the second intermediate transition layer 11 from the composition of the layer in contact with the lower part of the second intermediate transition layer 11 in the thickness direction of the second intermediate transition layer 11. The composition changes continuously so as to approach the composition.

  For example, as shown in FIG. 4, in the case where stacking is started from the A layer 6, the first intermediate transition layer 10 is first formed on the A layer 6, and then the first intermediate transition layer 10 is formed. B layer 7 is formed on the substrate. Subsequently, the first intermediate transition layer 10 is formed on the B layer 7, and then the A layer 6 is formed on the first intermediate transition layer 10. Thereafter, the first covering layer 4 is formed by repeating such a laminated structure.

  For example, in the second covering layer 5, when the stacking is started from the C layer 8, first, the second intermediate transition layer 11 is formed on the C layer 8, and then the second intermediate transition layer 11 is formed. The D layer 9 is formed on the substrate. Subsequently, the second intermediate transition layer 11 is formed on the D layer 9, and then the C layer 8 is formed on the second intermediate transition layer 11. Thereafter, the second covering layer 5 is formed by repeating such a laminated structure.

  In the present invention, even when the first intermediate transition layer 10 or the like is formed in this way, it can be said that the A layer 6 and the B layer 7 are alternately stacked in the first alternating layer. In addition, even when the second intermediate transition layer 11 and the like are formed, the expression that the C layer 8 and the D layer 9 are alternately stacked in the second alternating layer can be used.

  In the above example, in the case of the first intermediate transition layer 10 formed on the A layer 6 where lamination is started, the lower layer in contact with the first intermediate transition layer 10 is the A layer where lamination is started 6 and the upper layer in contact with the first intermediate transition layer 10 means the B layer 7. Therefore, the composition in the first intermediate transition layer 10 is from the composition of the A layer 6 to the composition of the B layer 7 in the thickness direction of the first intermediate transition layer 10 (that is, from the base material 2 side to the side away from the base material 2). Will change continuously.

  Further, the first intermediate transition layer 10 and the second intermediate transition layer 11 do not need to be formed independently of the A layer 6, the B layer 7, the C layer 8, and the D layer 9, and are in the middle of formation of these layers. Inevitably, it may be formed. For example, the first intermediate transition layer 10 is formed when the B layer 7 is formed after the A layer 6 is formed, when the A layer 6 is formed after the B layer 7 is formed, or during the formation of these layers. Inevitably, it may be formed. Further, the first intermediate transition layer 10 and the second intermediate transition layer 11 may be of a level that is observed or not observed depending on the observation conditions, and the observation magnification by a normal TEM or the like is 2 million times or more. It may be observed in the case of.

  If the first intermediate transition layer 10 is formed at the boundary between the A layer 6 and the B layer 7 and the boundary between the A layer 6 and the B layer 7 cannot be clearly defined, the first intermediate transition layer 10 is formed. The intermediate point in the thickness direction of the intermediate transition layer 10 is regarded as the boundary between the A layer 6 and the B layer 7, and the thickness of each layer is measured.

  In addition, since the second intermediate transition layer 11 is formed at the boundary portion between the C layer 8 and the D layer 9, the boundary portion between the C layer 8 and the D layer 9 cannot be clearly defined. The intermediate point in the thickness direction of the intermediate transition layer 11 is regarded as the boundary between the C layer 8 and the D layer 9, and the thickness of each layer is measured.

<Residual stress of surface coating layer>
In the present invention, the surface coating layer 3 preferably has an average residual stress of −8 GPa to 0 GPa. That is, when the residual stress of the surface coating layer 3 is averaged, it is preferably a compressive residual stress in the above range, and it is preferable to include a case where the stress is released for convenience and has no residual stress. Thus, since the surface coating layer 3 has the average compressive residual stress in the above range, the occurrence of chipping in the surface coating layer 3 of the surface coating cutting tool 1 can be suppressed, and the cutting edge of the surface coating cutting tool 1 can be prevented. Reliability is improved, and thereby the life of the surface-coated cutting tool 1 of the present invention can be extended.

  When the average residual stress of the surface coating layer 3 exceeds 0 GPa and has a positive value, tensile residual stress remains in the surface coating layer 3, so that cracks generated on the surface of the surface coating layer 3 There is a tendency that the progress in the direction of the base material 2 cannot be suppressed.

  On the other hand, when the average residual stress of the surface coating layer 3 is less than −8 GPa, the compressive residual stress becomes too large (that is, the absolute value of the residual stress becomes too large), and the surface-coated cutting tool of the present invention. The surface coating layer 3 may be peeled off from the edge portion of the surface-coated cutting tool 1 before the start of cutting 1, and the life of the surface-coated cutting tool 1 of the present invention may be shortened.

  In the present invention, the average residual stress of the surface coating layer 3 is an average value of the residual stress of the entire surface coating layer 3. In addition, when the description of compressive residual stress and a numerical value are written together, the numerical value is written without a minus sign.

  Further, it is preferable that the residual stress of the surface coating layer 3 changes in the thickness direction, and that the absolute value of the residual stress increases as the distance from the substrate 2 side increases (particularly, the compressive residual stress increases). This is because the progress of the cracks generated on the surface of the surface coating layer 3 to the substrate 2 side can be more effectively suppressed.

In the present invention, the residual stress of the surface coating layer 3 can be measured by the Sin ² ψ method using an X-ray stress measuring device.

<Crystal structure of surface coating layer>
In the present invention, the crystal structure of the surface coating layer 3 is preferably cubic. When the crystal structure of the surface coating layer 3 is cubic, the hardness of the surface coating layer 3 tends to be improved. For example, AlN is a hexagonal crystal, but the lattice constant in the case of a cubic crystal that is a metastable layer is 0.412 nm, whereas the lattice constant of CrN that is a stable layer at normal temperature and pressure is CrN. Is 0.414 nm, and the lattice constant is very close to that of AlN having a cubic crystal structure, so that AlN becomes cubic and high hardness by the pulling effect. Therefore, the A layer 6 can be made cubic by using a nitride containing Al and Cr.

  Thus, it is preferable that the crystal structure of each layer constituting the surface coating layer 3 is cubic because the hardness of the surface coating layer 3 is improved and the wear resistance is excellent. The crystal structure of each layer constituting the surface coating layer 3 can be analyzed by an X-ray diffractometer known in the art.

<Method for manufacturing surface-coated cutting tool>
The surface-coated cutting tool 1 of the present invention includes, for example, a step of forming a first coating layer 4 by alternately laminating one or more A layers 6 and B layers 7 on the surface of a base material 2, and a C layer. 8 and the D layer 9 can be manufactured by forming the surface coating layer 3 by a method including a step of alternately stacking one or more layers and forming the second coating layer 5.

  Here, the A layer 6, the B layer 7, the C layer 8 and the D layer 9 can be formed by, for example, physical vapor deposition. Here, as the physical vapor deposition method, for example, at least one selected from the group consisting of a cathode arc ion plating method, a balanced magnetron sputtering method, and an unbalanced magnetron sputtering method can be used.

  In addition, also when forming layers other than the 1st coating layer 4 and the 2nd coating layer 5 in the surface coating layer 3, it can form by the above physical vapor deposition methods, for example.

  In this invention, in order to form the surface coating layer 3 which has abrasion resistance on the surface of the base material 2, it turned out that it is preferable to form a compound layer with high crystallinity. Then, as a result of examining various methods as the formation method of the surface coating layer 3, it was found that the physical vapor deposition method is preferably used.

  In addition, as the physical vapor deposition method, a cathode arc ion plating method, a balanced magnetron sputtering method, an unbalanced magnetron sputtering method, or the like can be used. The law is considered suitable. When such a cathode arc ion plating method is used, before the surface coating layer 3 is formed, the surface of the substrate 2 can be subjected to metal ion bombardment treatment. This is also preferable from the viewpoint of significantly improving the adhesion with the surface coating layer 3.

  Here, in the cathode arc ion plating method, for example, after the base material 2 is installed in the apparatus and the target is installed as a cathode, a high current is applied to the target to cause arc discharge, thereby forming atoms constituting the target. Can be evaporated and ionized to deposit a substance on the surface of the substrate 2.

  In the balanced magnetron sputtering method, for example, the base material 2 is installed in the apparatus, and a target is installed on the magnetron electrode provided with a magnet that forms a parallel magnetic field. A gas plasma is generated by applying a high frequency power to the gas, and ions of the gas generated by the generation of the gas plasma collide with the target to ionize atoms emitted from the target and deposit them on the surface of the substrate 2. Can be performed.

  In addition, the unbalanced magnetron sputtering method can be performed, for example, by making the magnetic field generated by the magnetron electrode in the above-described balanced magnetron sputtering method non-parallel.

<Applications of surface coated cutting tools>
The surface-coated cutting tool 1 of the present invention is, for example, for pin milling of drills, end mills, milling cutting edge replacement inserts, turning cutting edge replacement inserts, metal saws, cutting tools, reamers, taps, or crankshafts. It can be used very effectively for chips and the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, it cannot be overemphasized that this invention is not what is limited to these.

<Production of surface-coated cutting tool>
(1) Cleaning of substrate FIG. 5 shows a schematic top view of the cathode arc ion plating apparatus used in this example, and FIG. 6 shows a schematic cross-sectional view of the cathode arc ion plating apparatus shown in FIG. .

  A chip having a grade of JIS standard P30 superalloy and having a shape of JIS standard SPGN120308 was mounted in the chamber 101 of the cathode arc ion plating apparatus. Here, the base material 2 was attached to the outer surface of the base material holder 104 provided at the center in the chamber 101.

  Further, the chamber 101 includes a cathode 106 for forming an A layer, a cathode 107 for forming a B layer, a cathode 120 for forming a C layer, and a cathode 120 for forming a D layer, which are alloy targets that are metal raw materials for the surface coating layer 3. A cathode 121 is attached.

  Here, as shown in FIG. 6, an arc power source 108 is attached to the cathode 106 for forming the A layer, and an arc power source 109 is attached to the cathode 107 for forming the B layer. Arc power sources (not shown) are also attached to the cathode 120 for forming the C layer and the cathode 121 for forming the D layer.

  A bias power source 110 is attached to the substrate holder 104. In the chamber 101, a gas inlet 102 for introducing the gas 105 is provided, and a gas outlet 103 for discharging the gas 105 from the chamber 101 is provided. The gas 105 in the chamber 101 can be sucked from the gas discharge port 103 by a vacuum pump.

In the apparatus shown in FIGS. 5 and 6, first, the inside of the chamber 101 is decompressed by a vacuum pump, and a heater (not shown) installed in the apparatus is rotated while the base material holder 104 is rotated. The surface temperature of the substrate 2 was heated to 500 ° C., and evacuation was performed until the pressure in the chamber 101 became 1.0 × 10 ⁻⁴ Pa.

  Next, a gas 105 (argon gas) is introduced from the gas introduction port 102, the pressure in the chamber 101 is maintained at 3.0 Pa, the voltage of the bias power supply 110 is gradually increased to −1000 V, and the substrate 2 The surface was cleaned for 15 minutes. Thereafter, argon gas was exhausted from the chamber 101.

(2) Formation of surface coating layer Subsequent to the cleaning of the base material 2 described above, the lowermost layer having the composition and film thickness shown in Table 1 was formed. In Examples 7 to 9, the lowermost layer was not formed.

  Next, in a state where the substrate 2 is rotated at the center, while introducing nitrogen as a reaction gas, the temperature of the substrate 2 is 500 ° C., the reaction gas pressure is 3.0 Pa, and the voltage of the bias power supply 110 is −50 V to − An arc current of 100 A was supplied to each of the cathode 106 and the cathode 107 while maintaining or gradually changing to a constant value in the range of 200V. Thereby, metal ions are generated from the cathode 106 and the cathode 107, respectively, and when a predetermined time has passed, the supply of the arc current is stopped, and the first coating layer 4 having the composition shown in Table 2 is formed on the surface of the substrate 2. Formed. Here, the first coating layer 4 is formed by alternately laminating the A layer and the B layer having the composition shown in Table 2 and the thickness of one layer (thickness per layer) by the number of layers shown in Table 2. It was produced by. For Comparative Example 1, only one layer A shown in Table 2 was produced. In the column of the second film thickness (μm) from the right in Table 2, the thickness per layer of the first coating layer 4 is described, and in the column of the number of layers (layers) at the right end of Table 2. Describes the number of first covering layers 4 that are alternately stacked one after the other with a second covering layer 5 described later.

  Next, metal ions are generated from the cathode 120 and the cathode 121 by supplying an arc current of 100 A to the cathode 120 and the cathode 121, respectively, while maintaining the temperature, reaction gas pressure and bias voltage of the substrate 2 as described above. When the predetermined time passed, the supply of arc current was stopped, and the second coating layer 5 having the composition shown in Table 3 was formed on the first coating layer 4. Here, the second coating layer 5 is formed by alternately laminating the C layer and the D layer having the composition shown in Table 3 and one layer thickness (thickness per layer) by the number of layers shown in Table 3 alternately. It was produced by. In addition, about the comparative examples 1-2, the 2nd coating layer 5 was not formed. In the column of the second film thickness (μm) from the right in Table 3, the thickness per layer of the second coating layer 5 is described, and in the column of the number of layers (layers) at the right end of Table 3, Describes the number of the second coating layers 5 stacked alternately with the first coating layers 4 described above.

  And the 1st coating layer 4 and the 2nd coating layer 5 were laminated | stacked alternately by repeating the formation operation | work of said 1st coating layer 4, and the formation operation of the 2nd coating layer 5. Thereafter, the uppermost layer having the composition and film thickness shown in Table 4 was formed, and the surface coating layer 3 shown in Table 5 including the lowermost layer, the first coating layer 4, the second coating layer 5, and the uppermost layer was formed. . In Example 9 and Comparative Examples 1 and 2, the uppermost layer was not formed. Further, the thicknesses of the A layer 6, the B layer 7, the C layer 8, and the D layer 9 in the surface coating layer 3 were adjusted by the rotation speed of the substrate 2. Table 5 shows the film thickness, hardness, compressive residual stress, and crystal structure of the entire surface coating layer 3, respectively. As shown in the column of compressive residual stress in Table 5, compressive residual stress is present in all the surface coating layers 3 of Examples 1 to 11 and Comparative Examples 1 and 2. Moreover, as shown in the column of the crystal structure in Table 5, the crystal structures of all the surface coating layers 3 of Examples 1 to 11 and Comparative Examples 1 and 2 are hexagonal.

<Life evaluation of surface-coated cutting tools>
With respect to the surface-coated cutting tools (blade-tip-exchangeable tips) of Examples 1 to 11 and Comparative Examples 1 and 2 produced above, the blade edge is actually obtained by performing a dry continuous cutting test and an intermittent cutting test under the conditions shown in Table 6. The amount of flank wear was measured. The results are shown in Table 7. In Table 7, the smaller the value of the flank wear amount of the blade edge, the longer the life. Moreover, the evaluation of chipping in the column of intermittent cutting in Table 7 indicates that the surface-coated cutting tool was chipped during the intermittent cutting test.

  As shown in Table 7, the surface-coated cutting tools of Examples 1 to 11 were compared with the surface-coated cutting tools of Comparative Examples 1 and 2, and the flank wear amount of the blade edge in both the continuous cutting test and the intermittent cutting test. It was confirmed that the service life of the surface-coated cutting tool was greatly prolonged.

  In the surface-coated cutting tools of Examples 1 to 11, the surface coating layer 3 having the configuration of the present invention is formed on the surface of the base material 2 and has excellent stability at high temperatures and suppresses chipping of the blade edge. Therefore, it is considered that the life of the surface-coated cutting tool has been greatly prolonged.

  In addition, the composition of each layer shown in Tables 1 to 4 was measured using XPS (X-ray photoelectron spectrometer), and the hardness of the entire surface coating layer 3 shown in Table 5 was nanoindenter ( This is a value confirmed by Nano Indenter XP) manufactured by MTS.

Moreover, the thickness of each layer which comprises the surface coating layer 3 shown by Table 1-Table 4, and the thickness of the whole surface coating layer 3 shown by Table 5 are the values measured using SEM or TEM, and show in Table 5 54 of the Sin ² ψ method (“X-ray stress measurement method” (Japan Society of Materials Science, published in 1981 by Yokendo Co., Ltd.)) using an X-ray residual stress measuring device. ~ See page 67).

  As described above, the embodiments and examples of the present invention have been described, but it is also planned from the beginning to appropriately combine the configurations described in the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  ADVANTAGE OF THE INVENTION According to this invention, the surface coating cutting tool which can prolong the lifetime of a surface coating cutting tool can be provided.

It is a typical expanded sectional view of an example of the surface covering cutting tool of the present invention. It is an example of the typical cross section along XX of FIG. It is a typical expanded sectional view of an example of the surface coating layer used for this invention. It is a typical expanded sectional view of another example of the surface coating layer in this invention. It is a schematic top view of the cathode arc ion plating apparatus used in this example. It is a schematic sectional drawing of the cathode arc ion plating apparatus shown in FIG.

Explanation of symbols

  1 surface coating cutting tool, 2 base material, 3 surface coating layer, 4 first coating layer, 5 second coating layer, 6 A layer, 7 B layer, 8 C layer, 9 D layer, 10 first intermediate transition layer, 11 Second intermediate transition layer, 101 chamber, 102 gas inlet, 103 gas outlet, 104 substrate holder, 105 gas, 106, 107, 120, 121 cathode, 108, 109 arc electrode, 110 bias electrode.

Claims (8)

A surface-coated cutting tool comprising a substrate and a surface coating layer in which a first coating layer and a second coating layer are alternately laminated on the surface of the substrate,
The first coating layer includes a first alternating layer in which A layers and B layers are alternately laminated one or more layers,
The A layer is made of a nitride containing Al and Cr, and the ratio of the number of Cr atoms when the total number of metal atoms constituting the A layer is 1 is greater than 0.1 and 0.4 or less. Yes,
The B layer is made of a nitride containing Al and Ti, and the ratio of the number of Ti atoms when the total number of metal atoms constituting the B layer is 1, is 0.2 or more and 0.6 or less. ,
The second coating layer includes a second alternating layer in which one or more C layers and D layers are alternately stacked,
The C layer is made of a nitride containing Ti and Si, and the ratio of the number of Si atoms when the total number of metal atoms constituting the C layer is 1 is greater than 0.05 and 0.3 or less. Yes,
The D layer is made of a nitride containing Ti and Cr, and the ratio of the number of Cr atoms is 0.05 to 0.3 when the total number of metal atoms constituting the D layer is 1. A surface-coated cutting tool characterized by   2. The surface-coated cutting tool according to claim 1, wherein a thickness of each of the first coating layer and the second coating layer is 0.1 μm or more and 1 μm or less.   The surface-coated cutting tool according to claim 1 or 2, wherein each of the A layer, the B layer, the C layer, and the D layer has a thickness of 1 nm or more and 50 nm or less. A first intermediate transition layer is formed between the A layer and the B layer in the first covering layer;
The composition of the first intermediate transition layer is changed from the composition of the layer in contact with the lower side of the first intermediate transition layer to the composition of the layer in contact with the upper side of the first intermediate transition layer in the thickness direction of the first intermediate transition layer. The surface-coated cutting tool according to any one of claims 1 to 3, wherein the surface-coated cutting tool is continuously changed so as to approach. A second intermediate transition layer is formed between the C layer and the D layer in the second coating layer;
The composition of the second intermediate transition layer is changed from the composition of the layer in contact with the second intermediate transition layer to the composition of the layer in contact with the upper part of the second intermediate transition layer in the thickness direction of the second intermediate transition layer. The surface-coated cutting tool according to any one of claims 1 to 4, wherein the surface-coated cutting tool is continuously changed so as to approach.   The surface-coated cutting tool according to any one of claims 1 to 5, wherein the surface-coated layer has an average residual stress of -8 GPa or more and 0 GPa or less.   The residual stress of the surface coating layer is characterized in that the absolute value of the residual stress increases as the distance from the substrate increases in the thickness direction of the surface coating layer. The surface-coated cutting tool described.   The surface-coated cutting tool according to claim 1, wherein the crystal structure of the surface-coated layer is a cubic crystal.

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