JP2006192545A - Surface-coated cutting tool and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool having a coating which is excellent in oxidation resistance at high temperature, has excellent toughness and does not cause delamination of the coating, and a method for producing the same.
The film includes a first film formed by a chemical vapor deposition method, a second film and a third film formed by a physical vapor deposition method, and the first film is formed of a substrate 1 and a second film. The second coating is located between the IVa group element, the Va group element, the VIa group element of the Periodic Table, It is composed of a compound of at least one element selected from the group consisting of Al and Si, has a compressive residual stress, and the third coating is located between the first coating and the second coating. There is provided a surface-coated cutting tool characterized by comprising α-type aluminum oxide, γ-type aluminum oxide or amorphous aluminum oxide.
[Selection] Figure 1

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.

  Conventionally, surface-coated cutting tools in which various coatings are formed on the surface of a substrate have been used in order to improve the toughness and wear resistance of the cutting tool. In recent years, there is a high demand for high-speed cutting in the cutting technology, and along with this, the number of cases where the cutting edge temperature of the cutting tool is exposed to a higher temperature is increasing. For this reason, improvement of the oxidation resistance at the time of high temperature is requested | required also with respect to the film formed on the base material of a cutting tool.

  As a film satisfying such a requirement, for example, a film made of a nitride or carbonitride containing Si together with Al or Cr (Patent Document 1, Patent Document 2) or a film made of aluminum oxide has been proposed. Among these, a film made of aluminum oxide is one of the most noticeable films because of its high wear resistance.

  For example, a configuration in which a second film made of aluminum oxide is formed on a first film made of a compound of a specific element by a physical vapor deposition method (PVD method) has been proposed (Patent Document 3). This proposal has a problem that the aluminum oxide film as the outermost layer is conventionally formed by a chemical vapor deposition method (CVD method), that is, the problem that the toughness is inferior because tensile stress remains in the aluminum oxide film. It was made to solve. However, in order to form an aluminum oxide film with high crystallinity such as α type on the first film, a considerably high temperature is applied even if the PVD method is adopted as in this proposal. The compressive stress of the first coating is annealed and released, and as a result, high toughness cannot be obtained.

  On the other hand, the thing of the structure which formed the film which consists of TiAlN by the PVD method on the film which consists of aluminum oxide formed by CVD method is proposed (patent document 4, patent document 5). However, in this proposal, since the aluminum oxide film has a tensile stress, high toughness could not be obtained as a result. In addition, when a film made of TiAlN is formed on a film made of aluminum oxide by the CVD method, adhesion between the two films may be inferior, and the film made of TiAlN may be peeled off. Proposals for preventing such a peeling problem have not been made, and in Patent Documents 1 and 2, a film containing Si and a film made of aluminum oxide are used in combination in order to prevent such peeling. There is no mention of that at all.

  Patent Document 6 below discloses a coated cutting tool characterized by performing shot blasting on a hard layer coated cutting tool produced by CVD and further coating the hard layer by a PVD method. Here, in the cutting tool of Patent Document 6, the purpose of shot blasting is to release tensile stress, and cracks are introduced into the film by shot blasting to eliminate the difference in thermal expansion coefficient between the film and the substrate. As a result, it is considered that the purpose is to release the tensile stress.

However, in the present invention, there is a suggestion that the shot-blasted CVD tool has insufficient fracture resistance, and the application of compressive stress is not intended at all. Furthermore, in Patent Document 6, shot blasting using a steel ball is performed, but when a steel ball is used, iron powder adheres to the CVD film, and even if the CVD film is coated with PVD, CVD is performed. There has been a problem that peeling of the film easily occurs at the interface between the layer and the PVD layer.
Japanese Patent No. 2793773 JP 2004-106183 A Japanese Patent No. 3159572 JP 2002-263910 A JP 2002-263911 A JP-A-6-57409

  The present invention has been made in order to solve the above-mentioned problems, and the object of the present invention is a film that has excellent oxidation resistance at high temperatures, excellent toughness, and does not cause delamination of the film. It is an object to provide a surface-coated cutting tool having the following and a manufacturing method thereof.

  As a result of intensive studies to solve the above problems, the present inventor has completed the present invention.

  According to one aspect of the present invention, there is provided a surface-coated cutting tool comprising a base material and a coating film formed on the base material, wherein the coating film is physically formed with a first coating film formed by a chemical vapor deposition method. Including a second film and a third film formed by a vapor deposition method, wherein the first film is located between the substrate and the second film, and includes at least one α-type aluminum oxide. And having a compressive residual stress imparted by a mechanical impact treatment using ceramic particles, and the second coating is composed of IVa group element, Va group element, VIa group element, Al, and Si of the periodic table And at least one layer composed of a compound consisting of at least one element selected from the group consisting of and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron, and compression residual The third coating is located between the first coating and the second coating, and is composed of α-type aluminum oxide, γ-type aluminum oxide, or amorphous aluminum oxide. A surface-coated cutting tool is provided.

  Preferably, at least one layer of the second coating contains Si.

  Preferably, the third coating is formed directly on the first coating.

  Preferably, the second film is formed immediately above the third film.

  Preferably, the α-type aluminum oxide constituting the first coating and / or the α-type aluminum oxide, γ-type aluminum oxide or amorphous aluminum oxide constituting the third coating are combined with an oxide of Zr and / or Hf. It is an oxide.

  Preferably, the average compressive residual stress σ1 in the first coating and the average compressive residual stress σ2 of the second coating have a relationship of σ1 <σ2.

  Preferably, the average compressive residual stress σ1 of the first coating is in the range of 1 to 6 GPa, and the average compressive residual stress σ2 of the second coating is in the range of 1 to 10 GPa.

  Preferably, the coating further includes a fourth coating, and the fourth coating is formed on the second coating and is at least one selected from the group consisting of Ti, Cr, Si, V, Al, Zr and Hf. It is comprised by the compound which consists of an element and at least 1 sort (s) of element chosen from the group which consists of carbon, nitrogen, oxygen, and boron.

  Preferably, the substrate is composed of any one of cemented carbide, cermet, high speed steel, ceramics, cubic boron nitride sintered body, or diamond sintered body.

  According to another aspect of the present invention, there is provided a method for manufacturing a surface-coated cutting tool according to any one of the above, wherein a first step of forming a first coating by a chemical vapor deposition method and a third coating by a physical vapor deposition method. A second step of forming and a third step of forming a second coating by physical vapor deposition, wherein the first coating formed by the first step is machined using ceramic particles prior to the second step. Provided is a method for manufacturing a surface-coated cutting tool, characterized by performing a process of imparting a mechanical impact.

  Preferably, the mechanical shock treatment is performed by a wet method.

  The surface-coated cutting tool of the present invention has a coating as described above, which has excellent oxidation resistance at high temperatures, excellent toughness, and does not cause delamination of the coating.

  Hereinafter, the present invention will be described in more detail. Note that in the following description of the embodiments, with reference to the drawings, the same reference numerals in the drawings denote the same or corresponding parts. Each drawing is a schematic diagram for explanation only, and the ratio of the size indicating each part includes a case where it is different from the actual ratio.

<Surface coated cutting tool>
The surface-coated cutting tool of the present invention comprises a substrate and a film formed on the substrate. The surface-coated cutting tool of the present invention having such a basic configuration is a drill, end mill, milling or turning cutting edge replaceable tip, metal saw, gear cutting tool, reamer, tap, or crankshaft pin milling It is extremely useful as a chip for use.

<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-based cemented carbide, including WC, including Co, or further including carbonitride such as Ti, Ta, Nb), cermet (TiC, TiN, TiCN, etc.) Main component), high-speed steel, ceramics (such as titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide and mixtures thereof), cubic boron nitride sintered bodies, diamond sintered bodies, etc. Examples of such a substrate can be given. 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.

  Here, as shown in FIG. 1, the surface-coated cutting tool of the present invention is such that a coating film is formed on a substrate 1, and on the tool surface, a rake face 2, a flank face 3, and The cutting edge ridge line portion 4 is included.

<Coating>
The film formed on the substrate of the surface-coated cutting tool of the present invention includes at least a first film, a second film, and a third film, which will be described later. The first film is formed so as to be positioned between the base material and a second film described later. The third coating is formed so as to be positioned between the first coating and the second coating.

  Moreover, such a film can contain a 4th film and another film other than these 1st film-2nd film. The fourth film is formed on the second film.

  In addition, it is preferable that the total thickness of such a film shall be 1 micrometer or more and 30 micrometers or less, More preferably, the upper limit is 25 micrometers or less, More preferably, it is 20 micrometers or less, The minimum is 2 micrometers or more, More preferably, it is 3 micrometers or more. When the thickness is less than 1 μm, characteristics such as wear resistance and oxidation resistance may not be sufficiently exhibited, and when it exceeds 30 μm, the chipping resistance decreases, which is not preferable. Hereinafter, these coating films will be described in more detail.

<First coating>
The first coating of the present invention is formed as a single layer or a multilayer by a chemical vapor deposition method (CVD method), and is positioned between the substrate and the second coating, and is formed of α-type aluminum oxide (α-Al ₂ It comprises at least one layer of O ₃ ) and has a compressive residual stress imparted by an impact that gives a mechanical impact using a ceramic described later. In the present specification, α-type aluminum oxide is sometimes referred to as α-type alumina.

  Such a first coating is excellent in oxidation resistance at high temperatures, has high hardness, and requires a high temperature of 800 ° C. or higher when depositing α-alumina by CVD. It has very good wear resistance because of its strong adhesion. In addition, α-type alumina, which has better grain boundary strength than κ-type alumina, is formed by the CVD method, so the introduction of cracks in α-type alumina is suppressed by utilizing the superior grain boundary strength of α-type alumina. Furthermore, it has excellent toughness because large compressive stress is introduced into the α-type alumina by the mechanical impact treatment described later. Especially, since the α-type alumina has residual compressive stress, the fracture resistance is dramatically improved. Is done. In addition, when compressive stress is introduced, since the mechanical impact using ceramic particles is applied as described later, the coating surface can be smoothed, and the surface formed by the CVD method is made of metal or the like. It is prevented from being contaminated and adversely affecting the adhesion with the third coating.

  Note that the introduction of cracks into α-type alumina is low in the α-type alumina film at the site where mechanical shock treatment is difficult (in the case of a holed chip, in the hole) and in the underlying CVD film. This can be confirmed by comparing the number of cracks to be generated and the number of cracks present in the α-type alumina film and the CVD film below it at the site subjected to the mechanical shock treatment.

  The present invention is characterized in that a coating made of α-type aluminum oxide is formed by a chemical vapor deposition method as the first coating that is not the outermost layer but the inner layer, and a mechanical shock treatment using ceramic is performed. One of them. As a result, as compared with the case where the coating is simply formed by the CVD method, it is possible to introduce a compressive stress in the α-type alumina instead of releasing the tensile stress, and to improve the adhesion with the third coating. Can be made. Furthermore, since the α-type aluminum oxide coating is not formed on the coating that contributes to the improvement of toughness, the compressive stress of the coating that contributes to the improvement of toughness is annealed and the toughness decreases. Can be eliminated.

  Note that the α-type aluminum oxide layer having such compressive residual stress does not need to be the entire surface of the tool, and it is effective if it exists on at least a part of the ridge surface, the rake surface, and the edge of the cutting edge that acts as a cutting edge. I can expect.

  As the chemical vapor deposition method for forming such a first film, any conventionally known chemical vapor deposition method can be employed. For example, HT-CVD method, MT-CVD method, MO-CVD method can be adopted. Etc. Among these, it is particularly preferable to employ the HT-CVD method and the MT-CVD method.

  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.

  As described above, the residual stress of the first coating, particularly the residual stress of α-type alumina, is −6 GPa or more and −0.1 GPa or less, more preferably the upper limit is −0.2 GPa or less, and further preferably −0. It is preferable that the stress is 3 GPa or less and the lower limit is −5 GPa or more, more preferably −4 GPa or more. When the residual stress exceeds −0.1 GPa, the toughness is inferior (breakage resistance is inferior). On the other hand, if the residual stress is less than −6 GPa, the film may have a large compressive stress, which may cause self-destruction of the coating.

  Further, such a first coating is composed of α-type aluminum oxide, and is composed of a composite oxide of this α-type aluminum oxide and at least one of Zr and Hf oxides. It can also be. By containing Zr or Hf, it is possible to impart properties such as higher hardness and improved heat insulation by miniaturization of aluminum oxide.

  Note that the α-type aluminum oxide layer of the present invention includes a case in which a metal other than Zr and Hf (for example, B, Si, Ti, Cr, Y, Yb, etc.) is contained in an amount of 20 atomic% or less.

  Here, the composite oxide of α-type aluminum oxide and at least one of Zr and Hf is a normal position of the crystal lattice of α-type aluminum oxide in which at least one or both of Zr and Hf is In this case, oxides in any case are included, for example, when they enter as a substitution type, when they enter as an interstitial type between the crystal lattices, when an intermetallic compound is formed, or when they exist as amorphous.

  Such a first coating preferably has a thickness of 0.5 μm or more and 25 μm or less (when formed in a multilayer, the total thickness thereof), more preferably the upper limit thereof is 20 μm or less, more preferably 15 μm or less, The lower limit is 1 μm or more, more preferably 2 μm or more. If the thickness is less than 0.5 μm, sufficient compressive stress cannot be applied and sufficient wear resistance may not be exhibited. If it exceeds 25 μm, the chipping resistance decreases, which is not preferable.

<Second coating>
The second coating of the present invention is formed as a single layer or a multilayer by physical vapor deposition (PVD method), and includes a group IVa element (Ti, Zr, Hf, etc.) and a group Va element (V, Nb, Ta, etc.) in the periodic table. ), Group VIa elements (Cr, Mo, W, etc.), Al, and Si, and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron And a compound having a compressive residual stress (excluding α-type aluminum oxide). Such a second coating has high hardness and excellent wear resistance, and exhibits extremely excellent toughness. In addition, the 2nd film formed by physical vapor deposition in this way becomes a film which has a compression residual stress and does not have a crack introduced in the film thickness direction.

  The reason why such a second film is formed by physical vapor deposition is to first apply compressive residual stress to the film. As such a physical vapor deposition method, any conventionally known physical vapor deposition method can be adopted, and examples thereof include an ion plating method and a sputtering method. Among these, it is particularly preferable to employ a cathode arc ion plating method, a balanced or unbalanced magnetron sputtering method, or a method combining these. Moreover, such a 2nd film is formed on said 1st film, Comprising: It is preferable to be formed especially just on a 1st film.

The second film comprises at least one element selected from the group consisting of group IVa elements, group Va elements, group VIa elements, Al and Si in the periodic table, and carbon, nitrogen, oxygen, and boron. It is comprised by the compound which consists of at least 1 sort (s) of element chosen from the group which consists of. Examples of such compounds include TiAlN, TiAlSiN, TiAlCrSiN, AlCrN, AlCrSiN, TiZrN, TiAlMoN, TiAlNbN, TiSiN, AlCrTaV, AlTiVN, TiB ₂ TiGrHfN, CrSiWN, TiAlCN, TiSiCN, AlZrON, AlCrN, AlZrON, AlCrN, AlCrMoCN, TiAlBN, TiAlCrSiBCNO, and the like. In addition, the second coating includes a case where these compounds are laminated with a thickness of 5 nm or more and 5 μm.

  In addition, at least one layer of the second coating preferably contains Si. Examples of such compounds include TiAlSiN, AlCrSiN, TiAlCrSiN, TiSiN, CrSiBON, TiAlSiBN, and AlCrSiCN.

  Thus, by including Si as a constituent element of the compound, the adhesion to the third coating is further improved, and the oxidation resistance at high temperature is also greatly improved. Thus, the improvement in oxidation resistance at high temperatures is required at the time of high-speed cutting, and in particular, it is formed on the third film made of α-type aluminum oxide, γ-type aluminum oxide or amorphous aluminum oxide as in the present invention. This is useful when Because such a third coating is a low thermal conductivity coating, the heat generated in the second coating is difficult to dissipate to the base material side, so that the temperature rise of the second coating becomes remarkable and at high temperatures. This is because the oxidation resistance is particularly required.

Furthermore, since the 2nd film of this invention has a compressive residual stress, it will show high toughness. Here, the residual stress is an internal stress as already described with respect to the first coating, and is preferably −10 GPa or more and −1 GPa or less, more preferably the upper limit is −1.5 GPa or less, more preferably − It is suitable 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 in the first film. When the second 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 set as the compressive residual stress of the second coating.

  Such a second coating preferably has a thickness of 0.3 μm or more and 10 μm or less (when formed in a multilayer, the total thickness thereof), more preferably the upper limit thereof 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 decreases, which is not preferable.

<Third coating>
The third coating of the present invention is a single layer or a multilayer, is located between the first coating and the second coating, and is formed by a physical vapor deposition method. By having excellent adhesion to both of the two coatings, it exhibits the action of preventing delamination of the coatings. As the physical vapor deposition method, the same method as described in the second coating can be used.

  Since the third coating is formed on the first coating that has been subjected to the mechanical shock treatment using ceramic particles, the third coating is excellent in adhesion to the first coating and the peel resistance is improved. This is because the mechanical impact treatment does not cause adhesion of iron powder associated with blasting using a conventional steel ball or the like, and thus the coating surface is not contaminated by the media and has a smooth coating surface. . Furthermore, since it has the same composition (oxidized alumina) as the first coating, the adhesion with the first coating is further improved, and the peel resistance is further improved.

  Such a third coating is located between the first coating and the second coating, and is composed of α-type aluminum oxide, γ-type aluminum oxide, or amorphous aluminum oxide. In particular, it is preferably formed immediately above the first film. In addition, the case where the third coating is a multilayer includes the case where aluminum oxides having different crystal systems are alternately laminated, the case where they are continuously laminated, and the case where they are laminated randomly. Either α-type, γ-type, or amorphous aluminum oxide may be formed as a single layer.

Moreover, since the 3rd film is formed by the physical vapor deposition method, it has a residual compressive stress and, as a result, shows a high toughness and a high fracture resistance. Here, the compressive residual stress is the internal stress as already described for the first coating, but when α-type aluminum oxide is formed, the coating temperature is as high as 700 to 800 ° C. Residual stress tends to be a small value of 1 GPa or less, and γ-type and amorphous aluminum oxide do not easily show an X-ray diffraction peak, and it is difficult to quantify the residual stress by the sin ² ψ method. However, if the cross section of the film is mirror-polished and it is confirmed that no crack is introduced in the film thickness direction of the film, it can be considered that compressive residual stress or small tensile residual stress is introduced into the film.

  Such a third coating preferably has a thickness of 0.01 μm or more and 3 μm or less (when it is formed of multiple layers, its total thickness), more preferably its upper limit is 2.5 μm or less, and even more preferably 2 μm. Hereinafter, the lower limit is 0.03 μm or more, and more preferably 0.05 μm or more. If the thickness is less than 0.01 μm, the effect of improving the adhesion may not be sufficiently exhibited, and if it exceeds 3 μm, the effect is economically disadvantageous with no significant difference.

  Such a third coating is composed of α-type aluminum oxide, γ-type aluminum oxide, or amorphous aluminum oxide, and this α-type aluminum oxide, γ-type aluminum oxide, or amorphous aluminum oxide. And a composite oxide of at least one of Zr and Hf oxides. Inclusion of Zr or Hf can be expected to increase the hardness and improve the heat insulating property by making aluminum oxide finer.

  Here, the composite oxide of α-type aluminum oxide, γ-type aluminum oxide, or amorphous aluminum oxide and at least one of Zr and Hf is an oxide of at least one of Zr and Hf, or both When entering a normal position of the crystal lattice of α-type aluminum oxide or γ-type aluminum oxide as a substitution type, entering as an interstitial type between the crystal lattices, forming an intermetallic compound, existing as an amorphous state, etc. In any case, the oxide is included.

  Here, when the compressive residual stress of the first coating film is σ1 and the compressive residual stress of the second coating film is σ2, it is particularly preferable that the relationship is σ1 <σ2, and the relationship of σ1 <σ2 is satisfied. The first film has a residual stress of −6 GPa or more and −0.1 GPa or less, the second film has a residual stress of −10 GPa or more and −1 GPa or less, and the third film has a compressive residual stress or a film It is particularly preferred that there is no crack in the thickness direction. By prescribing in this way, the adhesion between the first film, the second film, and the third film is particularly excellent.

<4th coat>
The fourth coating of the present invention is formed on the second coating as desired, and is improved in finished surface roughness, improved welding resistance, improved peel resistance, improved appearance quality, and use. It shows effects such as easy identification of finished corners and improved protection against the second coating (for example, improved oxidation resistance).

  Such a fourth film is at least one element selected from the group consisting of Ti, Cr, Si, V, Al, Zr and Hf, and at least one selected from the group consisting of carbon, nitrogen, oxygen and boron. A single layer or a multilayer is constituted by a compound composed of a seed element.

Examples of compounds suitable as the fourth coating include AlN, ZrN, CrN, AlZrN, AlON, AlHfN, AlCN, ZrCN, TiN, TiCN, TiSiCN, TiBN, and Al ₂ O ₃ (γ type or amorphous). Can be mentioned.

  Such a fourth coating preferably has a thickness of 0.1 μm or more and 3 μm or less (when it is formed of multiple layers, its total thickness), more preferably its upper limit is 2 μm or less, and even more preferably 1.5 μm. Hereinafter, the lower limit is 0.2 μm or more, and more preferably 0.3 μm or more. When the thickness is less than 0.1 μm, the finish surface roughness is improved, the welding resistance is improved, the peel resistance is improved, the appearance quality is improved, the used corners are easily distinguished, and the second film is protected. In some cases, the effect of improvement (for example, improvement in oxidation resistance) may not be sufficiently exhibited, and even if it exceeds 3 μm, there is no great difference in effect and it is economically disadvantageous.

  Such a fourth film is preferably formed by physical vapor deposition in the same manner as the second film and the third film. This is because the manufacturing efficiency is improved and the adhesion between the layers is also improved.

<Manufacturing method>
The method for manufacturing a surface-coated cutting tool according to the present invention includes a first step of forming the first coating by chemical vapor deposition (CVD), a second step of forming the third coating by physical vapor deposition, and the second step. A third step of forming the film by physical vapor deposition. Here, after the first step, before the second step, a step of forming by mechanical impact treatment using ceramic is performed. In addition, the method demonstrated above is employ | adopted as a chemical vapor deposition method and a physical vapor deposition method.

The mechanical impact treatment is a treatment in which particles given kinetic energy, such as ejection from a nozzle or projection by an impeller, are hit against an object, or a target is hit with a brush holding hard particles such as ceramic. Say. For example, blasting, peening, brush honing, etc. can be used, and wet blasting is particularly preferable. Normally, a film formed by CVD has tensile stress, but residual compressive stress can be introduced by the treatment. In particular, the present invention is characterized in that ceramic is used as a medium in the treatment. This is because the use of ceramic does not contaminate the coating surface during the treatment and does not adversely affect the adhesion with the layer in contact with the coating. As the ceramic material, materials such as Al ₂ O ₃ , SiC, ZrO ₂ , TiC, SiO ₂ and glass can be used. In particular, spherical ceramic particles are preferred. This is because it is easy to suppress the destruction of the CVD film due to the blast treatment. Moreover, as the conditions of the said process, within the range of the projection pressure 0.01-0.5 MPa, the range of the projection distance 0.5-200 mm, the range of fine powder concentration 5-40 vol%, the range of particle size 10-250 micrometers It is preferable to set within.

  Above all, wet blasting makes it possible to cool the high heat generated on the surface of the CVD film during blasting and introduces large compressive residual stress without annealing the compressive residual stress introduced into the CVD film. It becomes possible to do.

  In addition, when the fourth coating is formed in addition to the first coating, the second coating, and the third coating as described above, the method for manufacturing the surface-coated cutting tool according to the present invention also performs physical vapor deposition on the fourth coating. It is preferable to form by a method.

  Thus, in the coating of the surface-coated cutting tool of the present invention, the first coating is subjected to chemical vapor deposition (CVD) and mechanical impact treatment using ceramic, and the second and third coatings are necessary. In some cases, the fourth coating is preferably formed by physical vapor deposition. This is because it is possible to obtain excellent adhesion between the layers and high production efficiency.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. The chemical composition of each film below was confirmed by XPS (X-ray photoelectron spectrometer), and the compressive residual stress was calculated by obtaining an average value by the sin ² ψ method described above. In the following, the film is formed by the cathodic arc ion plating method which is a physical vapor deposition method, but it can also be formed by, for example, a balanced or unbalanced sputtering method or other known physical vapor deposition methods. is there.

<Production of surface-coated cutting tool>
First, the base material is a WC standard cemented carbide of JIS standard K20 and the shape as a cutting tip is JIS standard CNMG120408, and this is performed at a temperature of about 900 ° C. using a known CVD method. A first coating made of TiN, TiCN and an α-type alumina material at about 1000 ° C. was formed.

Next, a ceramic abrasive such as Al ₂ O _{3 having} a particle size of 150 μm or less is applied to the first coating formed by CVD under conditions of a projection pressure of 0.05 to 0.3 MPa, a projection distance of 5 to 100 mm, and a ceramic concentration of 10 to 30 vol%. Residual compressive stress was introduced by applying mechanical impact treatment with the grains.

The substrate after the first coating was formed was attached to a cathode arc ion plating apparatus. Subsequently, the inside of the chamber of the apparatus was depressurized to 1 × 10 ⁻³ Pa or less with a vacuum pump, and the temperature of the substrate was heated to 500 ° C. with a heater installed in the apparatus, and held for 1 hour.

  Next, argon gas was introduced to maintain the pressure in the chamber at 3.0 Pa, the voltage of the substrate bias power supply was gradually increased to −500 V, and the coating surface was cleaned for 15 minutes. Thereafter, argon gas was exhausted.

  Next, as a film formed on the surface of the first film, a target which is a metal evaporation source is set so that the chemical composition and the laminated structure are as shown in Table 1 below, and nitrogen, methane ( While introducing at least one of oxygen or carbon monoxide (as an oxygen source), a base material (substrate) temperature of 650 ° C., a reaction gas pressure of 2.0 Pa, and a substrate bias voltage of −200 V While being maintained, an arc current of 100 A was supplied to the cathode electrode, and metal ions were generated from an arc evaporation source, thereby forming a coating film of each component on the surface of the substrate.

  Thus, No. 1 shown in Table 1 was obtained. 1-19 surface-coated cutting tools were produced. No. 1 to 15 are examples of the present invention. Reference numerals 16 to 19 are comparative examples (however, the following film forming method was adopted for the following films of each comparative example).

  No. The 16 comparative examples are formed by the CVD method (film temperature 900 to 1000 ° C.) together with the first film and the second film, and have a tensile residual stress of 0.4 GPa. No. In Comparative Examples 17 and 19, after the first film was formed by the CVD method (1000 ° C.), the result of dry blasting using a steel ball was that residual stress was introduced into each first film. In addition, each of the second coatings is formed by the PVD method and has residual stresses of -2.9 GPa and -3.0 GPa, respectively. No. In 18 comparative examples, the first film is formed by the CVD method (film temperature 1000 ° C.) and has a residual stress of 0.5 GPa, and then the second film is formed by the PVD method. Has residual stress.

  In the said Table 1, the laminated structure of the film has shown having laminated | stacked on the base material in order from the left thing. Further, in Table 1 above, those given the symbol “*” are comparative examples.

  These surface-coated cutting tools were subjected to an abrasion resistance test and an intermittent cutting test under the following conditions. The results are also shown in Table 1. In the wear resistance test, the time for the flank wear amount to be 0.2 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: 300m / min
Cutting depth d: 1.5 mm
Feed f: 0.30 mm / rev.
Dry / Wet: Wet <Intermittent cutting test>
Work Material: SCM440 (Round bar with 4 grooves)
Cutting speed: 200 m / min
Cutting depth: 1.5mm
Feed: 0.4 mm / rev.
Dry type / wet type: Dry type In Table 1 above, the ones marked with “*” are comparative examples. Further, the columns of “first coating residual stress” and “second and third coating residual stress” show the results of measuring the compressive residual stress of the flat portion of the rake face by the sin ² ψ method.

  In addition, about what a 2nd film consists of a coating layer, it is No .. Nos. 1, 4, 5, 6, 8, 12, 17, 18, and 19 are “TiAlN”, No. 2 and 10, “TiAlSiN”, No. 14 for “AlCrSiN”, No. 14 16 represents the residual stress of “TiCN”.

  As can be seen from Table 1 above, no. 1-No. All of the 15 surface-coated cutting tools of the present invention had excellent wear resistance and toughness and did not cause delamination of the coating. No. 1-No. It is clear that the surface-coated cutting tool of the 15 examples of the present invention is excellent in oxidation resistance at high temperature and chipping resistance of the coating film in consideration of the above-mentioned conditions of the abrasion resistance test. This tendency is remarkable in those having Si in the coating. In contrast, no. 16 and no. Since the surface-coated cutting tool of 18 comparative examples has a tensile residual stress in the first coating, it is inferior in fracture resistance. No. Although the surface-coated cutting tools of Comparative Examples 17 and 19 do not have a tensile residual stress in the first coating, the second coating has low adhesion and poor wear resistance due to blasting using a steel ball. .

  In the present embodiment, a cemented carbide material is used as the base material, but the same effect can be obtained even if a material such as cermet is used. In addition, although a material having a chip breaker was used as a base material, the same effect as in this example was obtained even for a tool without a chip breaker or a tool (chip) in which the entire upper and lower surfaces of the cutting tool were polished. Obtainable.

  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 sectional drawing of the base material in the surface coating cutting tool of this invention.

Explanation of symbols

  1 base material, 2 rake face, 3 flank face, 4 edge edge line part.

Claims (11)

A surface-coated cutting tool comprising a substrate and a coating formed on the substrate,
The coating includes a first coating formed by chemical vapor deposition and a second coating and a third coating formed by physical vapor deposition,
The first coating is located between the base material and the second coating, includes at least one layer of α-type aluminum oxide, and has a mechanical impact using ceramic particles. With applied compressive residual stress,
The second coating is a group consisting of at least one element selected from the group consisting of group IVa elements, group Va elements, group VIa elements, Al, and Si in the periodic table, and carbon, nitrogen, oxygen, and boron. Is composed of at least one layer composed of a compound consisting of at least one element selected from: and has a compressive residual stress,
The third coating is located between the first coating and the second coating, and is composed of α-type aluminum oxide, γ-type aluminum oxide, or amorphous aluminum oxide. A surface-coated cutting tool.   The surface-coated cutting tool according to claim 1, wherein at least one layer of the second coating contains Si.   The surface-coated cutting tool according to claim 1, wherein the third coating is formed immediately above the first coating.   The surface-coated cutting tool according to claim 2, wherein the second coating is formed immediately above the third coating.   The α-type aluminum oxide constituting the first coating and / or the α-type aluminum oxide, γ-type aluminum oxide or amorphous aluminum oxide constituting the third coating is a composite oxidation with an oxide of Zr and / or Hf. The surface-coated cutting tool according to claim 1, wherein the surface-coated cutting tool is a product.   The average compressive residual stress σ1 in the first coating and the average compressive residual stress σ2 of the second coating have a relationship of σ1 <σ2, according to any one of claims 1 to 5. Surface coated cutting tool.   The average compressive residual stress σ1 of the first coating is in the range of 0.1 to 6 GPa, and the average compressive residual stress σ2 of the second coating is in the range of 1 to 10 GPa. Item 6. The surface-coated cutting tool according to any one of Items 1 to 5. The coating further includes a fourth coating,
The fourth film is formed on the second film and includes at least one element selected from the group consisting of Ti, Cr, Si, V, Al, Zr, and Hf, and carbon, nitrogen, oxygen, and boron. The surface-coated cutting tool according to any one of claims 1 to 7, wherein the surface-coated cutting tool is composed of a compound composed of at least one element selected from the group consisting of:   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 1-8 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 1-9,
A first step of forming the first film by chemical vapor deposition;
A second step of forming the third coating by physical vapor deposition;
A third step of forming the second film by physical vapor deposition;
Including
A method for producing a surface-coated cutting tool, wherein the first coating formed in the first step is subjected to a process of applying a mechanical impact using ceramic particles before the second step.   The method for producing a surface-coated cutting tool according to claim 10, wherein the treatment for applying a mechanical impact is performed by a wet process.

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