JP2007196364A - Surface-coated cutting tool and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool with an aluminum oxide coating film being directly deposited on the surface of its base material without deteriorating the base material or degrading the surface roughness. <P>SOLUTION: The surface-coated cutting tool has a base material and one or more coating films deposited on the base material. The coating film contains at least an aluminum oxide coating film, and the aluminum oxide coating film contains aluminum oxide, and is directly deposited on the base material. The crystalline structure of aluminum oxide is γ type or a mixed structure of γ type and α type. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface-coated cutting tool formed by forming a film on a substrate and a method for producing the same.

  A base material constituting a cutting tool has been coated with various coatings for the purpose of protecting the surface and further improving various properties such as wear resistance and toughness. Among them, aluminum oxide is particularly effective in wear resistance and is expected to have an effect of preventing surface oxidation of the base material. Therefore, attempts to use it as a coating directly covering the surface of the base material have been used for a long time. Has been done.

  As one of such attempts, it has been proposed to form aluminum oxide directly on a substrate by chemical vapor deposition (CVD) (Patent Document 1). However, according to this proposal, the base material is exposed to a high temperature when aluminum oxide is formed by a chemical vapor deposition method, which may cause deterioration of the base material. Moreover, the aluminum oxide formed by such a chemical vapor deposition method has an α-type crystal structure, but its crystal structure is as large as 0.5 μm or more, and the surface roughness of the tool is deteriorated. There were also problems such as a decrease in wear resistance.

On the other hand, as means for solving such problems, it has been proposed to form aluminum oxide directly on a substrate by physical vapor deposition (PVD method) instead of chemical vapor deposition (Patent Documents 2 to 4). However, according to this proposal, although the problems caused by the chemical vapor deposition method as described above are solved, the pretreatment that the substrate surface must be oxidized prior to the formation by the physical vapor deposition method is an essential requirement. It is said. This oxidation treatment is said to be performed to promote crystal growth of the aluminum oxide film, but has a problem that the substrate may be deteriorated by this oxidation treatment.
Japanese Patent Laid-Open No. 48-17480 JP 2004-332003 A JP 2004-332005 A JP 2004-332006 A

  The present invention has been made to solve the above-mentioned problems, and the object is to directly form an aluminum oxide film on the surface of the substrate without degrading the substrate or deteriorating the surface roughness. It is to provide a surface-coated cutting tool.

  As a result of diligent investigations to solve the above problems, the present inventor found that when the aluminum oxide film was directly formed on the substrate by physical vapor deposition, the crystal structure of the formed aluminum oxide was adjusted. Obtaining the knowledge that an aluminum oxide film can be directly formed on a substrate without performing a pretreatment of oxidation treatment, the present invention is finally completed by conducting further studies based on this knowledge. Has been reached.

  That is, the surface-coated cutting tool of the present invention comprises a substrate and one or more coatings formed on the substrate, and the coating includes at least an aluminum oxide coating, and the aluminum oxide coating Is a film containing aluminum oxide, which is directly formed on the substrate, and the crystal structure of the aluminum oxide is γ-type or a mixed structure of γ-type and α-type It is characterized by that.

  The aluminum oxide film is preferably formed by physical vapor deposition, and the crystal structure of aluminum oxide is preferably 1 nm or more and 500 nm or less.

The aluminum oxide film preferably has a residual stress of −4 GPa or more and 1 GPa or less, and preferably contains at least one of ZrO ₂ , HfO ₂ , B ₂ O ₃ or TiO ₂ . The film thickness is preferably 1 μm or more and 10 μm or less.

  The film is formed on the aluminum oxide film by group IVa elements (Ti, Zr, Hf, etc.), group Va elements (V, Nb, Ta, etc.), group VIa elements (Cr, Mo, W, etc.) of the periodic table. Etc.), at least one metal selected from the group consisting of Al and Si, or at least one of the metals and at least one element selected from the group consisting of carbon, nitrogen, oxygen and boron It is preferable that at least one film composed of the compound is formed.

  In particular, the film formed on the aluminum oxide film includes at least one metal selected from the group consisting of Ti, Cr, Al, and Si, or at least one of the metals, and carbon, nitrogen, oxygen, and It is preferably one or more coatings composed of a compound composed of at least one element selected from the group consisting of boron, and at least one metal selected from the group consisting of Ti, Cr, Al, and Si, Or two or more layers composed of a compound composed of at least one of the metals and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron, each having a thickness of 1 nm or more and 100 nm It is preferable to include one or more films periodically laminated as the following thickness.

  The base material is preferably composed of any one of cemented carbide, cermet, high speed steel, ceramics, cubic boron nitride sintered body, and diamond sintered body.

  In addition, the method for manufacturing a surface-coated cutting tool according to the present invention is a method for manufacturing a surface-coated cutting tool according to any one of the above, and a step of preparing a substrate whose surface is not oxidized, Forming an aluminum oxide film directly on the material by physical vapor deposition.

  The surface-coated cutting tool of the present invention has a configuration as described above, and is obtained by directly forming an aluminum oxide film on the surface of the substrate without deteriorating the substrate or deteriorating the surface roughness.

Hereinafter, the present invention will be described in more detail.
<Surface coated cutting tool>
The surface-coated cutting tool of the present invention comprises a base material and one or more coating films formed on the base material. The surface-coated cutting tool of the present invention having such a basic configuration is a drill, end mill, milling or turning cutting edge replacement cutting tip, metal saw, gear cutting tool, reamer, tap, or crankshaft pin milling It is extremely useful as a processing chip.

<Base material>
As the base material of the surface-coated cutting tool of the present invention, a conventionally known material known as such a cutting tool base material can be used without particular limitation. For example, cemented carbide (for example, WC base cemented carbide, including WC, including Co, or further including carbonitride such as Ti, Ta, Nb, etc.), cermet (TiC, TiN, TiCN, etc.) High-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and mixtures thereof), cubic boron nitride sintered body, diamond sintered body Etc. can be mentioned as examples of such a substrate. When a cemented carbide is used as such a base material, the effect of the present invention is exhibited even if such a cemented carbide contains an abnormal phase called free carbon or η phase in the structure.

  In addition, these base materials may have a modified surface. For example, in the case of cemented carbide, a de-β layer may be formed on the surface, or in the case of cermet, a surface hardened layer may be formed, and even if the surface is modified in this way, The effect is shown.

  And the base material of this invention is characterized by the surface not being oxidized before the below-mentioned aluminum oxide film is formed. Since the present invention uses a base material that has not been oxidized in this way, it fundamentally solves the problem that the base material deteriorates as in the prior art.

<Coating>
The film formed on the substrate of the surface-coated cutting tool of the present invention is formed by laminating one or more films, and includes an aluminum oxide film as at least one of the films. In addition, this film is not restricted only to what coat | covers the whole surface on a base material, The aspect in which the film is not partially formed is also included.

  In addition, such a film is formed on the aluminum oxide film by at least one metal selected from the group consisting of group IVa element, group Va element, group VIa element, Al, and Si in the periodic table, or of the metal It may further include one or more coatings constituted by a compound consisting of at least one element and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron.

  The total thickness (total film thickness) of such a coating is preferably 0.5 μm or more and 15 μm or less, more preferably the upper limit is 10 μm or less, more preferably 7 μm or less, and the lower limit is 1 μm or more. Preferably it is 2 micrometers or more. When the thickness is less than 0.5 μm, the effect of improving various properties such as wear resistance and oxidation resistance may not be sufficiently exhibited. When the thickness exceeds 15 μm, the chipping resistance decreases, which is not preferable. The coating of the present invention includes a case where Mn, Fe, Co, Ni, Cu, Zn or the like is contained in an amount of 10 atomic% or less so as not to reduce the wear resistance. Hereinafter, these coating films will be described in more detail.

<Aluminum oxide coating>
The aluminum oxide film of the present invention is a film containing aluminum oxide (Al ₂ O ₃ ) and is directly formed on the substrate, and the crystal structure of the aluminum oxide is γ-type, or It is characterized by a mixed structure of γ type and α type. Such an aluminum oxide film is particularly preferably formed by physical vapor deposition.

In the present application, the crystal structure of aluminum oxide is simply γ-Al ₂ O ₃ , the α-type crystal is simply α-Al ₂ O ₃ , and the γ-type and α-type mixed structure is used. In some cases, γ, α-Al ₂ O ₃ may be described. In addition, the γ-type crystal structure has a spinel crystal structure crystallographically and can be identified by X-ray diffraction (XRD). Similarly, the α type crystal structure has a crystallographic corundum type crystal structure and can be identified by an X-ray diffraction method. The mixed structure of γ-type and α-type refers to a structure having a diffraction spectrum caused by both the γ-type and the α-type by X-ray diffraction.

  As described above, the crystal structure of aluminum oxide constituting the aluminum oxide film is γ-type or a mixed structure of γ-type and α-type so that the base material is not subjected to any pretreatment such as oxidation treatment. In addition, an aluminum oxide film can be directly formed by physical vapor deposition. Although the detailed mechanism is still unclear, aluminum oxide itself and the base material (metals and metal compounds constituting it) are completely different from each other in nature. It is presumed that aluminum oxide having a mixed structure of γ-type and α-type selectively and advantageously grows crystals on the substrate. This makes it possible to directly form an aluminum oxide film on the surface of the substrate without deteriorating the substrate or deteriorating the surface roughness. In addition, in this application, forming an aluminum oxide film directly on a base material means that a base material and an aluminum oxide film are formed in direct contact without interposing another film.

Here, the film containing aluminum oxide in the above means a film containing aluminum oxide as a main component, and unavoidable impurities may be included. Moreover, such an aluminum oxide film may contain at least one of ZrO ₂ , HfO ₂ , B ₂ O ₃ or TiO ₂ as a component other than aluminum oxide. These components can be included at a compounding ratio of 0.1% by mass or more and 40% by mass or less with respect to aluminum oxide. Still further, the aluminum oxide coating can contain 20 atomic% or less of a metal such as Si, Cr, Y, Yb. Thus, by including each said component other than aluminum oxide, refinement | miniaturization of aluminum oxide is accelerated | stimulated and the characteristic of high hardness and an improvement of heat insulation can be provided. In addition, when the aluminum oxide film contains other components as described above, when these other components enter the normal position of the crystal lattice of aluminum oxide as a substitution type, when entering as an interstitial type between the crystal lattices, In the case of forming an intermetallic compound, it includes any case where it exists as an amorphous material.

  Thus, the aluminum oxide film of the present invention preferably has a crystal structure of aluminum oxide of 1 nm to 500 nm. As a result, the surface roughness of the coating is smoothed and the welding of the work material can be extremely effectively prevented, so that the work surface of the work material can be finished in a very good state and the tool itself Abrasion resistance can also be dramatically improved.

  Here, the size of the crystal structure represents an average value. When the crystal has a columnar structure, the average value of the width in the direction perpendicular to the crystal growth direction is shown. When the crystal has a granular structure, Indicates the average value of the long diameter (maximum particle diameter in each crystal). If this size exceeds 500 nm, smoothing of the surface roughness as described above may not be obtained. If the size is less than 1 nm, various effects such as a sufficient protective effect on the base material and wear resistance can be obtained. In some cases, the effect of improving the characteristics is not shown. More preferably, the upper limit is 200 nm or less, more preferably 100 nm or less, while the lower limit is 1 nm or more.

  Furthermore, the aluminum oxide film preferably has a residual stress of −4 GPa to 1 GPa. Thereby, extremely excellent toughness can be imparted.

  Here, the residual stress is an internal stress (intrinsic strain) remaining in the coating, and is a concept including both compressive residual stress and tensile residual stress. In the present invention, the term “residual stress” includes both compressive residual stress and tensile residual stress (note that the state in which the tensile residual stress is released and the stress becomes 0 GPa is also included for convenience).

  The compressive residual stress is a stress represented by a numerical value “−” (minus) (unit: “GPa” is used in the present invention). In addition, when expressing the magnitude of compressive residual stress without using numerical values, it expresses that the compressive residual stress increases as the absolute value of the numerical value increases, and the compressive residual stress decreases as the absolute value of the numerical value decreases. It shall be expressed that the stress is small. Generally, the higher the compressive residual stress, the higher the toughness. Further, the tensile residual stress refers to a stress represented by a numerical value “+” (plus) (unit: “GPa” is used in the present invention).

Such residual stress can be measured by the sin ² ψ method using an X-ray stress measuring device, and can be measured at any three points (each of these points located on the rake face or flank flat portion of the tool). (The point is preferably selected at a distance of 0.5 mm or more from each other so that the stress of the part can be represented.) The above stress is measured by the sin ² ψ method, and the average value is obtained. Can do.

The sin ² ψ method using X-rays is widely used as a method for measuring the residual stress of a polycrystalline material. For example, “X-ray stress measurement method” (Japan Society of Materials Science, 1981 Corporation) The method described in detail on pages 54 to 66 of Yokendo) may be used.

  The upper limit of the residual stress of such an aluminum oxide film is more preferably 0.2 GPa or less, further preferably 0.1 GPa or less, and the lower limit is −3.5 GPa or more, more preferably −3 GPa or more. Is preferred. In the case where the residual stress (tensile residual stress) exceeds 1 GPa, the toughness may be inferior (breakage resistance is inferior). On the other hand, if the residual stress is less than −4 GPa, the film has a large compressive stress. May cause self-destruction.

  Further, such an aluminum oxide film preferably has a thickness of 0.1 μm or more and 10 μm or less, more preferably the upper limit is 6 μm or less, more preferably 3 μm or less, and the lower limit is 0.2 μm or more, more preferably 0.3 μm or more. If the thickness is less than 0.1 μm, sufficient oxidation resistance may not be exhibited at high temperatures and sufficient wear resistance may not be exhibited. If the thickness exceeds 10 μm, chipping resistance may be reduced, which may be undesirable. .

  The aluminum oxide film of the present invention having excellent characteristics as described above is optimally formed by physical vapor deposition. As such a physical vapor deposition method, a conventionally known physical vapor deposition method can be adopted, but a sputtering method is preferable for coating aluminum oxide which is a non-conductive material. Among these, it is preferable to employ a magnetron sputtering method using a pulse power source for the cathode. Further, a combination of a sputtering method and an arc ion plating method, or a method of forming a film by an arc ion plating method by imparting conductivity by dispersing a conductive substance in aluminum oxide can be employed.

  In order to adjust the crystal structure of the aluminum oxide to a γ-type or a mixed structure of γ-type and α-type, in each of the above methods, the substrate surface is not oxidized, that is, oxidized on the substrate. It is desirable to form an aluminum oxide film directly in the absence of a compound. This is presumably because α-type aluminum oxide is preferentially formed when the substrate surface is oxidized.

<Films other than aluminum oxide film>
The film of the present invention is formed on the above-described aluminum oxide film by a group IVa element (Ti, Zr, Hf, etc.), a group Va element (V, Nb, Ta, etc.), a group VIa element (Cr, Mo, W, etc.) Etc.), at least one metal selected from the group consisting of Al and Si, or at least one of the metals and at least one element selected from the group consisting of carbon, nitrogen, oxygen and boron It is preferable that at least one film composed of the compound is formed.

  In particular, the film formed on the aluminum oxide film includes at least one metal selected from the group consisting of Ti, Cr, Al, and Si, or at least one of the metals, and carbon, nitrogen, oxygen, and It is preferably one or more coatings composed of a compound composed of at least one element selected from the group consisting of boron, and at least one metal selected from the group consisting of Ti, Cr, Al, and Si, Or two or more layers composed of a compound composed of at least one of the metals and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron, each having a thickness of 1 nm or more and 100 nm It is preferable to include one or more films periodically laminated as the following thickness.

  Hereinafter, for convenience, a film other than the aluminum oxide film formed on the aluminum oxide film will be referred to as an outer layer film.

  Such an outer layer coating has high hardness and excellent wear resistance, and exhibits extremely excellent toughness. In particular, at least one metal selected from the group consisting of Ti, Cr, Al, and Si, or at least one element selected from the group consisting of at least one of the metals and carbon, nitrogen, oxygen, and boron One or more coatings composed of the compound consisting of the above are excellent in oxidation resistance and heat resistance, and thus exhibit particularly excellent wear resistance, and are extremely excellent because of excellent adhesion to the aluminum oxide coating. Peel resistance is indicated. These preferred characteristics eliminate various problems caused by the accumulation of cutting heat in other coatings formed on the aluminum oxide coating due to the high thermal insulation properties of the aluminum oxide coating. Is extremely effective.

  The outer layer film is preferably formed by physical vapor deposition, and preferably has compressive residual stress.

  The reason why it is preferable to form such an outer layer film by physical vapor deposition is to firstly apply compressive residual stress to the outer layer film, and secondly, an aluminum oxide film is formed by physical vapor deposition. In this case, the same film formation method as that of the aluminum oxide film is employed to improve the production efficiency. Such a physical vapor deposition method can employ the same method as described for the aluminum oxide film, and it is particularly preferable to employ the same method as that for the aluminum oxide film.

And as a metal or compound which constitutes such an outer layer coat, for example, Cr, Ti, Al, Si, V, Zr, Hf, TiAl, TiSi, AlCr, TiN, TiON, TiCN, TiCNO, TiBN, TiCBN, TiAlCN, AlN, AlCN, AlCrCN, AlON, CrN, CrCN, TiSiN, TiSiCN, Cr 2 O 3, Ti 2 O 3, TiO 2, TiAlON, ZrN, ZrCN, AlZrN, TiAlN, TiAlSiN, TiAlCrSiN, AlCrN, AlCrSiN, TiZrN , TiAlMoN, TiAlNbN, TiSiN, TiSiCN , AlCrTaN, AlTiVN, TiB 2, TiCrHfN, CrSiWN, TiAlCN, TiSiCN, AlZrON, AlCrCN, AlHfN, rSiBON, mention may be made of TiAlWN, AlCrMoCN, TiAlBN, the TiAlCrSiBCNO like.

  In particular, at least one metal selected from the group consisting of Ti, Cr, Al, and Si, or at least one element selected from the group consisting of at least one of the metals and carbon, nitrogen, oxygen, and boron The compounds consisting of Ti, Cr, Al, Si, TiAlN, TiAlNO, TiAlCNO, TiBN, TiCBN, TiSiN, TiSiNO, TiSiCNO, CrTiN, CrTiNO, CrTiCNO, SiAlN, SiAlNO, SiAlCNO, CrSiN, CrSiNO, CrSiCNO, SiAlN SiAlNO, SiAlCNO, CrSiN, CrSiNO, CrSiCNO, TiAlSiN, TiAlSiNO, TiAlSiCNO, TiAlCrN, TiAlCrNO, TiAlCrCNO, TiCr iN, TiCrSiNO, TiCrSiCNO, AlCrN, AlCrNO, AlCrSiNO, there may be mentioned AlCrCNO like, in particular AlCrN, preferred AlCrNO, AlCrSiNO, AlCrCNO the like.

  In addition, this outer layer film can form these metals or compounds as a single layer or multiple layers. In the case of multiple layers, it includes the case where layers of these metals or compounds are laminated with a thickness of 5 nm to 5 μm. In particular, at least one metal selected from the group consisting of Ti, Cr, Al, and Si, or at least one selected from the group consisting of at least one of the metals and carbon, nitrogen, oxygen, and boron It is preferable that two or more types of layers composed of a compound composed of an element include one or more coatings formed by periodically laminating each layer with a thickness of 1 nm to 100 nm. Thus, by periodically laminating the above layers, the oxidation resistance and heat resistance are further improved, and extremely excellent wear resistance is exhibited. Here, periodically laminating means, for example, laminating with a certain periodicity such as alternately laminating two kinds of layers. In addition, when the thickness of each layer is less than 1 nm or exceeds 100 nm, the effect of improving the abrasion resistance due to lamination may not be shown, but even in that case, it is inherent to these metals and compounds. The effect of improving wear resistance is shown. The thickness of each layer is more preferably 5 nm or more and 60 nm or less.

Furthermore, the outer layer coating of the present invention preferably has a compressive residual stress, and thereby exhibits high toughness. Here, the compressive residual stress is an internal stress as already described for the aluminum oxide film, and is preferably −10 GPa to −1 GPa, more preferably the upper limit is −1.5 GPa, more preferably It is preferable that the stress is −2 GPa or less and the lower limit is −8 GPa or more, more preferably −7 GPa or more. When the residual stress exceeds -1 GPa, the toughness is inferior (breakage resistance is poor). On the other hand, when the residual stress is less than -10 GPa, the compressive stress becomes too large and the coating is peeled off due to self-destruction. May occur. Such compressive residual stress can be measured by the same method using the sin ² ψ method described for the aluminum oxide film. When the outer layer coating is formed of multiple layers, the stress of the layer having the maximum compressive stress (the compressive stress having the maximum absolute value) is taken as the compressive residual stress of the outer layer coating.

  Such an outer layer coating preferably has a thickness of 0.3 μm or more and 10 μm or less (when it is formed of multiple layers, its total thickness), more preferably its upper limit is 7 μm or less, more preferably 5 μm or less, The lower limit is 0.5 μm or more, more preferably 1 μm or more. If the thickness is less than 0.3 μm, sufficient wear resistance may not be exhibited and sufficient toughness may not be exhibited. If the thickness exceeds 10 μm, the fracture resistance may decrease, which is not preferable.

<Method for manufacturing surface-coated cutting tool>
The method for producing a surface-coated cutting tool of the present invention includes the steps of preparing a base material that has not been subjected to oxidation treatment on the surface, and forming an aluminum oxide film directly on the base material by physical vapor deposition. Can do. When an outer layer film is further formed on the aluminum oxide film, the method further includes a step of forming the outer layer film on the aluminum oxide film by physical vapor deposition. In addition, as a physical vapor deposition method, the method demonstrated above is employ | adopted.

  Here, the step of preparing a base material that has not been subjected to oxidation treatment on the surface means that a pretreatment of oxidizing the surface of the base material is not performed. Thus, since the base material which has not been oxidized is used, the problem that the base material deteriorates as in the prior art is fundamentally solved.

  Thus, it is preferable to form all the films of the surface-coated cutting tool of the present invention by physical vapor deposition. This is because extremely high production efficiency can be obtained.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. In addition, the chemical composition of each following film was confirmed by XPS (X-ray photoelectron spectroscopy analyzer), and the residual stress was calculated by obtaining an average value of three points by the sin ² ψ method described above. In the following, the coating is formed by a combination of the unbalanced magnetron sputtering method and the cathode arc ion plating method, which are physical vapor deposition methods, but includes cases where the film is formed by other known physical vapor deposition methods.

<Example 1>
<Production of surface-coated cutting tool>
First, the base material is a WC-base cemented carbide of JIS standard M20 and the shape as a cutting tip is JIS standard CNMG120408, which is unbalanced using a pulsed DC power source as a cathode. The magnetron sputtering apparatus (film forming apparatus) was mounted.

  FIG. 1 is a schematic diagram showing a schematic configuration of the film forming apparatus 10. A plurality of arc evaporation sources 11 and 12 and an unbalanced magnetron sputtering evaporation source (hereinafter referred to as UBM sputtering source) 13 are arranged in the film forming apparatus 10 shown in FIG. The above-mentioned cutting tip as the base material 20 was attached to a holder 14 that rotates so as to face each other. The necessary gas is introduced from the gas inlet 15 into the film forming apparatus 10. In addition, a heater 16 is provided in the film forming apparatus 10.

  In this embodiment, a predetermined metal raw material (for example, TiAl or Ti) is set in the arc evaporation sources 11 and 12, and Al (which may include Hf, Zr, B, or the like) is set in the UBM sputtering source. That is, an aluminum oxide film is formed by a UBM sputtering source, and an outer layer film is formed by an arc evaporation source.

Subsequently, the inside of the chamber of the apparatus is depressurized to 1 × 10 ⁻³ Pa or less by a vacuum pump, and the temperature of the substrate 20 is heated to 650 ° C. by the heater 16 installed in the apparatus and held for 1 hour. did.

  Next, argon gas was introduced to maintain the pressure in the chamber at 3.0 Pa, the substrate bias power supply voltage was gradually increased to −1000 V, and the surface of the substrate was cleaned for 15 minutes. Thereafter, argon gas was exhausted. This treatment with argon gas does not involve oxygen and is not an oxidation treatment.

  Next, the target was set in the metal evaporation source so that the chemical composition and the laminated structure (film thickness, residual stress) were as shown in Table 1 below as the film formed on the substrate surface. No. The aluminum oxide coatings of the tools 1 to 11 were formed by a reactive sputtering method while setting the base material (substrate) temperature to 500 to 800 ° C. and applying pulsed DC power to the UBM sputtering source while flowing oxygen gas. For the outer layer coating, the base ion (substrate) temperature is set to 400 to 600 ° C., and one or more gases of nitrogen, methane (as a carbon source), and oxygen are introduced as a vacuum or a reaction gas while arc ion plate is used. A coating film of each constitution was formed on the surface of the base material by a ting method. In Table 1, those having two or more outer layer coatings formed on the aluminum oxide coating in order from the left one.

  Thus, No. 1 shown in Table 1 was obtained. 1 to 16 surface-coated cutting tools were produced. No. 1 to 11 are examples of the present invention, in which an aluminum oxide film is directly formed on a substrate. Nos. 12 to 16 are comparative examples in which a film other than the aluminum oxide film is formed directly on the substrate. In addition, the following film-forming methods were employ | adopted about the following film among each film of a comparative example.

  That is, no. The comparative examples 14 and 15 include an aluminum oxide film as a film, and this aluminum oxide film is formed by the CVD method (coating temperature 1000 ° C.), and the crystal structure of the aluminum oxide shows α-type. It had a tensile residual stress of 4 GPa. No. In Comparative Example 16, the base material was heat-treated at 1000 ° C. for 1 hour in an oxygen-containing atmosphere before forming the coating, and each coating was formed by physical vapor deposition with the base surface oxidized. (For this reason, the crystal form of the aluminum oxide film was α-type). In addition, the film of each comparative example other than this was formed into a film by the physical vapor deposition method similarly to the thing of an Example.

  In Table 1 above, the laminated structure of the film indicates that the film is laminated on the base material in order from the left (the blank in Table 1 indicates that the corresponding film is not formed). ing). Further, in Table 1 above, those with the symbol “*” are comparative examples.

  In addition, No. The outer layer coatings 9 to 11 indicate that the two layers are periodically laminated. For example, no. No. 9 is a layer of TiAlN having a thickness of 15 nm and a layer of AlCrNO having a thickness of 15 nm, which are periodically laminated (alternatingly stacked up and down) to form an outer coating film having a thickness of 2.0 μm (the maximum compressive residual stress is − (Indicating that a layer made of TiAlN is first formed on the aluminum oxide film). No. No. 10 and 11 are also No. The same content as 9 is shown. Such a periodic stack can be formed by adjusting the rotation speed of the holder 14 in the film forming apparatus 10 or by adjusting the type and flow rate of the reaction gas every half rotation.

  These surface-coated cutting tools were subjected to an abrasion resistance test and an intermittent cutting test under the following conditions. The results are shown in Table 2 below. In the wear resistance test, the time for the flank wear amount to be 0.15 mm was measured, and the longer the time, the better the wear resistance. In the intermittent cutting test, the time until the tool is broken is measured, and the longer the time is, the better the toughness is.

<Abrasion resistance test>
Work material: SCM435 round bar Cutting speed: 180m / min
Cutting depth: 2.0mm
Feed: 0.3 mm / rev.
Dry / Wet: Dry <Intermittent cutting test>
Work material: SCM435
Cutting speed: 350 m / min
Cutting depth: 2.0mm
Feed: 0.2 mm / rev.
Dry / Wet: Dry

  In Table 2 above, those with the symbol “*” are comparative examples. As can be seen from Table 2, no. 1-No. Each of the 11 surface-coated cutting tools of the present invention had excellent wear resistance and toughness. In other words, since the surface roughness of the aluminum oxide film is smooth, this contributes to the smoothness of the surface roughness of the tool, which is considered to have exhibited excellent wear resistance, and prevents deterioration of the base material. Therefore, it is considered that the toughness was excellent. The outer layer coating is composed of at least one metal selected from the group consisting of Ti, Cr, Al, and Si and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron. No. 2 in which a film in which two or more layers constituted are periodically laminated is formed. In 9 to 11, it was confirmed that these coatings had excellent oxidation resistance and heat resistance by showing particularly excellent wear resistance.

  In contrast, no. 12-No. The surface-coated cutting tools of 16 comparative examples were inferior in wear resistance and toughness (breakage resistance) as compared with the above examples.

  In the present embodiment, a material having a chip breaker is used as a base material. However, the present embodiment is also applicable to a tool (chip) having no chip breaker or a tool (chip) whose upper and lower surfaces are entirely polished. The same effect can be obtained.

<Example 2>
<Production of surface-coated cutting tool>
As a base material, instead of the base material used in Example 1, the composition is a cermet of JIS standard P30 and the shape as a cutting tip is a JIS standard CNMG120408, except that the base material is used. Were all formed in the same manner as in Example 1, and No. 1 shown in Table 3 were formed. 101-120 surface-coated cutting tools were produced. No. 101-115 is an Example of this invention, and the aluminum oxide film is directly formed on the base material. Reference numerals 116 to 120 are comparative examples in which a film other than the aluminum oxide film is formed directly on the substrate. In addition, each film of the above Examples and Comparative Examples is formed by physical vapor deposition (however, only No. 119 is CVD) under the same conditions as in Example 1. 120 is No. 120 in Example 1. In the same manner as in No. 16, the substrate was oxidized, and an aluminum oxide film was formed by physical vapor deposition.

  In Table 3 above, the sample with the symbol “*” is a comparative example, and the laminated structure of the coating is the same as in Example 1, indicating that the left layer is laminated on the base material in order (Table). No. 3 indicates that the corresponding coating is not formed, and Nos. 113 to 115 are multilayers in which outer layer coatings are periodically laminated as in Nos. 9 to 11 of Example 1. It is formed as a film).

  These surface-coated cutting tools were subjected to an abrasion resistance test and an intermittent cutting test under the following conditions. The results are shown in Table 4 below. In the wear resistance test, the time for the flank wear amount to be 0.15 mm was measured, and the longer the time, the better the wear resistance. In the intermittent cutting test, the time until the tool is broken is measured, and the longer the time is, the better the toughness is.

<Abrasion resistance test>
Work material: SCM435 round bar Cutting speed: 180m / min
Cutting depth: 2.0mm
Feed: 0.3 mm / rev.
Dry / Wet: Dry <Intermittent cutting test>
Work material: SCM435
Cutting speed: 250 m / min
Cutting depth: 2.0mm
Feed: 0.2 mm / rev.
Dry / Wet: Dry

  In Table 4 above, those with the symbol “*” are comparative examples. As is apparent from Table 4, 101-No. Each of the 115 surface-coated cutting tools according to the examples of the present invention had excellent wear resistance and toughness. In other words, since the surface roughness of the aluminum oxide film is smooth, this contributes to the smoothness of the surface roughness of the tool, which is considered to have exhibited excellent wear resistance, and prevents deterioration of the base material. Therefore, it is considered that the toughness was excellent. The outer layer coating is composed of at least one metal selected from the group consisting of Ti, Cr, Al, and Si and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron. No. 2 in which a film in which two or more layers constituted are periodically laminated is formed. In 113-115, it was confirmed that these coatings had excellent oxidation resistance and heat resistance by showing particularly excellent wear resistance.

  In contrast, no. 116-No. The surface-coated cutting tools of 120 comparative examples were inferior in wear resistance and toughness (fracture resistance) as compared with the above examples.

  In the present embodiment, a material having a chip breaker is used as a base material. However, the present embodiment is also applicable to a tool (chip) having no chip breaker or a tool (chip) whose upper and lower surfaces are entirely polished. The same effect can be obtained.

<Example 3>
<Production of surface-coated cutting tool>
As a base material, instead of the base material used in Example 1, a cubic boron nitride sintered body having a cubic boron nitride content of 30 to 95%, the shape as a cutting tip Except for using JIS standard SNGN120408 as the base material, except that No. 1 shown in Table 5 201-210 surface-coated cutting tools were produced. No. Nos. 201 to 205 are examples of the present invention, in which an aluminum oxide film is directly formed on a substrate. Reference numerals 206 to 210 are comparative examples in which a film other than the aluminum oxide film is formed directly on the substrate. In addition, each film of the above Examples and Comparative Examples was formed by physical vapor deposition under the same conditions as Example 1 (however, only No. 208 and No. 209 aluminum oxide films were formed by CVD). . No. 210 in Example 1 In the same manner as in No. 16, the substrate was oxidized, and an aluminum oxide film was formed by physical vapor deposition.

  In Table 5 above, the sample with the symbol “*” is a comparative example, and the laminated structure of the coating is the same as in Example 1, indicating that the left layer is laminated on the base material in order (Table). A blank in 5 indicates that the corresponding film is not formed).

  These surface-coated cutting tools were subjected to an abrasion resistance test under the following conditions. The results are shown in Table 6 below. In the wear resistance test, the time for the flank wear amount to be 0.15 mm was measured, and the longer the time, the better the wear resistance.

<Abrasion resistance test>
Work material: SCM415
Cutting speed: 400 m / min
Cutting depth: 0.4mm
Feed: 0.2 mm / rev.
Dry / Wet: Dry

  In Table 6 above, those with the symbol “*” are comparative examples. As can be seen from Table 6, no. 201-No. All of the 205 surface-coated cutting tools according to the present invention had excellent wear resistance. That is, since the surface roughness of the aluminum oxide film is smooth, this contributes to the smoothness of the surface roughness of the tool, and thus it is considered that excellent wear resistance was exhibited.

  In contrast, no. 206-No. The surface-coated cutting tool of 210 of the comparative example was inferior in wear resistance as compared with the above-mentioned example.

  In the present embodiment, a material having a chip breaker is used as a base material. However, the present embodiment is also applicable to a tool (chip) having no chip breaker or a tool (chip) whose upper and lower surfaces are entirely polished. The same effect can be obtained.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of 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.

It is a schematic diagram which shows schematic structure of the film-forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Film-forming apparatus, 11, 12 Arc evaporation source, 13 Unbalanced magnetron sputtering evaporation source, 14 Holder, 15 Gas inlet, 16 Heater, 20 Base material.

Claims (11)

A surface-coated cutting tool comprising a substrate and one or more coatings formed on the substrate,
The coating includes at least an aluminum oxide coating,
The aluminum oxide film is a film containing aluminum oxide and is directly formed on the substrate, and the crystal structure of the aluminum oxide is γ-type or a mixed structure of γ-type and α-type A surface-coated cutting tool characterized in that   2. The surface-coated cutting tool according to claim 1, wherein the aluminum oxide film is formed by physical vapor deposition.   The surface-coated cutting tool according to claim 1, wherein the aluminum oxide film has a crystal structure of aluminum oxide having a size of 1 nm to 500 nm.   The surface-coated cutting tool according to claim 1, wherein the aluminum oxide film has a residual stress of −4 GPa or more and 1 GPa or less. The aluminum oxide _{coating, ZrO 2, HfO 2, B} 2 O 3 or the surface-coated cutting tool according to any one of claims 1 to 4, characterized in that it contains at least one TiO _2.   The surface-coated cutting tool according to any one of claims 1 to 5, wherein the aluminum oxide coating has a thickness of 0.1 µm to 10 µm.   The film is formed on the aluminum oxide film by at least one metal selected from the group consisting of Group IVa elements, Group Va elements, Group VIa elements, Al, and Si of the Periodic Table, or at least one of the metals And at least one film composed of at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron. A surface-coated cutting tool according to claim 1.   The film formed on the aluminum oxide film is made of at least one metal selected from the group consisting of Ti, Cr, Al, and Si, or at least one of the metals, and carbon, nitrogen, oxygen, and boron. The surface-coated cutting tool according to claim 7, wherein the surface-coated cutting tool comprises one or more coatings composed of a compound comprising at least one element selected from the group consisting of:   The film formed on the aluminum oxide film is made of at least one metal selected from the group consisting of Ti, Cr, Al, and Si, or at least one of the metals, and carbon, nitrogen, oxygen, and boron. 2 or more types of layers composed of a compound composed of at least one element selected from the group consisting of one or more films formed by periodically laminating each layer with a thickness of 1 nm to 100 nm. The surface-coated cutting tool according to claim 7 or 8, characterized in that:   The said base material is comprised with either a cemented carbide alloy, a cermet, high speed steel, ceramics, a cubic boron nitride sintered compact, or a diamond sintered compact, The any one of Claims 1-9 characterized by the above-mentioned. A surface-coated cutting tool according to claim 1. It is a manufacturing method of the surface covering cutting tool in any one of Claims 1-10,
Preparing a substrate that has not been oxidized on the surface;
Forming an aluminum oxide coating directly on the substrate by physical vapor deposition;
The manufacturing method of the surface coating cutting tool characterized by including.

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