JP2009148856A - Surface coated cutting tool - Google Patents

Abstract

An object of the present invention is to provide a surface-coated cutting tool provided with a coating capable of reducing crater wear and imparting high wear resistance.
The surface-coated cutting tool of the present invention comprises a substrate and a coating formed on the substrate, and the coating comprises one layer or two or more layers, and at least one of the layers is Chemical formula Hf _1-a Zr _a X _b (where a and b represent atomic ratios, respectively, 0 <a ≦ 0.55, 0.1 ≦ b ≦ 2, and X represents boron, oxygen, carbon and A zirconium-containing hafnium layer containing a first compound represented by the following formula: (1) a peak intensity A of (111) plane in X-ray diffraction; 200) has a crystal structure in which the ratio B / A to the peak intensity B of the plane is 0 ≦ B / A ≦ 1.
[Selection figure] None

Description

  The present invention relates to a surface-coated cutting tool comprising a substrate and a coating formed on the substrate.

  Surface-coated cutting tools used to cut various work materials can improve the surface wear resistance of hard substrates such as WC-base cemented carbide, cermet, high-speed steel, etc. For the purpose of improving the protective function, the surface has been coated with a hard coating such as TiN, TiCN, TiAlN or the like. In particular, since a coating made of TiAlN exhibits excellent wear resistance, it is widely used as a coating for such surface-coated cutting tools in place of a coating made of titanium nitride, carbide, carbonitride, or the like.

  However, the life of cutting tools is much shorter than before due to the diversification of work materials and the need for high-speed cutting to improve processing efficiency. Furthermore, as a recent trend of cutting tools, there is a tendency that dry processing (dry processing) without using a cutting fluid is required from the viewpoint of global environmental conservation.

  For this reason, characteristics required for cutting tools such as anti-crater wear are increasingly advanced, and various advanced characteristics are also required for coatings of surface-coated cutting tools.

  As an attempt to meet such a demand, Patent Document 1 discloses a first film made of one compound selected from nitride, carbide, carbonitride, oxynitride and carbonitride of TiSi, Zr, It has been proposed to include one or more second films made of one kind of compound M selected from Hf and ZrHf, and to laminate them alternately. This technology pays attention to the fact that the microstructure of the hard and brittle TiSi layer differs from the layer made of Compound M, and by laminating it, it suppresses crack growth and suppresses chipping of the cutting edge, making it resistant to intermittent cutting. This is intended to improve wear.

However, in the above conventional technique, the mechanical characteristics and cutting performance of the compound M itself are not studied.
JP 2004-42193 A

  The present invention has been made in view of the current situation as described above, and an object of the present invention is to provide a surface-coated cutting tool having a coating capable of reducing crater wear and imparting high wear resistance. Is to provide.

  The present invention has been made by finding that the hardness of HfZr itself is improved by setting Hf and Zr within a specific range.

That is, the surface-coated cutting tool of the present invention is a surface-coated cutting tool comprising a substrate and a coating formed on the substrate, and the coating is composed of one layer or two or more layers. Of these, at least one layer has the chemical formula Hf _1-a Zr _a X _b (where a and b each represent an atomic ratio, where a is 0 <a ≦ 0.55 and b is 0.1 ≦ b ≦ 2. X represents at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen.) Is a zirconium-containing hafnium layer containing a first compound represented by the following formula: It has a crystal structure in which the ratio B / A between the peak intensity A of the (111) plane and the peak intensity B of the (200) plane is 0 ≦ B / A ≦ 1.

A in the chemical Hf _1-a Zr _a X _b is preferably 0 <a ≦ 0.50.
The first compound preferably has a crystal grain size of 0.1 nm or more and 200 nm or less, a peak position 2θ ₍₁₁₁₎ of the (111) plane in X-ray diffraction is 32 ° or more and 34 ° or less, (200 The surface peak position 2θ ₍₂₀₀₎ is preferably 39 ° or more and 40 ° or less.

  The zirconium-containing hafnium layer preferably contains at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta, and W.

  The first compound preferably contains at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta, and W.

  When at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta and W is included, the atomic ratio with respect to Hf is 0.005 or more and 0.3 or less. Preferably there is.

  The zirconium-containing hafnium layer is formed by alternately laminating one or more first layers including the first compound and second layers including the second compound, and the second compound includes Si, Cr, Al, It can be an embodiment containing at least one element selected from the group consisting of Ti, Hf, Ta, Nb and V and at least one element selected from the group consisting of boron, oxygen, carbon and nitrogen, Each of the first layer and the second layer preferably has a thickness of 0.5 nm to 200 nm.

  The coating includes an underlayer, and the underlayer is preferably formed on the base material, and the zirconium-containing hafnium layer is preferably formed thereon, and the underlayer is formed of Ti, boron, oxygen, It is preferable to include a third compound containing at least one element of the group consisting of carbon and nitrogen.

  The zirconium-containing hafnium layer preferably has a thickness of 0.3 μm or more and 10 μm or less.

  A layer made of a compound containing Hf and Zr having the above-mentioned specific composition, and including a layer having a specific crystal structure in the coating of the cutting tool, is made of TiSi nitride as in Patent Document 1 above. Even if the film and the film made of any one of Zr, Hf, and ZrHf are not alternately stacked, excellent wear resistance can be imparted. In particular, HfZrN having a specific composition and crystal structure in the present invention has an effect of suppressing crater wear as well as flank wear during cutting, and can further extend the life.

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 a coating film formed on the base material. The surface-coated cutting tool of the present invention having such a configuration is, for example, a drill, end mill, milling or turning cutting edge exchangeable cutting tip, metal saw, gear cutting tool, reamer, tap, or pin shaft milling of a crankshaft. It can be used very effectively as an industrial chip. The coated cutting tool of the present invention is a drill for cutting a Ti alloy or a heat resistant alloy such as an Inconel alloy, an end mill, a milling or turning cutting edge replacement cutting tip, metal saw, gear cutting tool, reamer, tap. Etc., can be used particularly effectively.

<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 the substrate. When a cemented carbide is used as such a substrate, the effect of the present invention is exhibited even if the 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. Even if the surface is modified in this way, the present invention The effect of is shown.

<Coating>
The film formed on the base material of the surface-coated cutting tool of the present invention comprises one layer or two or more layers. And at least 1 layer of those layers is a zirconium containing hafnium layer containing the 1st compound explained in full detail below. The coating in the present invention may further contain other layers as long as the zirconium-containing hafnium layer is included. In addition, the film in this invention is not limited only to what coat | covers the whole surface on a base material, The case where the film is partially formed may also be included.

  The total thickness of these films (when two or more layers are formed, the total film thickness) is preferably 0.3 μm or more and 15 μm or less, more preferably the upper limit is 10 μm or less, and still more preferably 5 μm or less, and the lower limit is 0.5 μm or more, more preferably 1 μm or more. If the thickness is less than 0.3 μm, the effect of improving various properties such as wear resistance may not be sufficiently exhibited. If the thickness exceeds 15 μm, the residual stress increases and the adhesion to the substrate may decrease. is there. The film thickness can be measured by cutting a cutting tool and observing the cross section using an SEM (scanning electron microscope).

<Zirconium-containing hafnium layer>
In the present invention, the zirconium-containing hafnium layer has the chemical formula Hf _1-a Zr _a X _b (where a and b each represent an atomic ratio, a is 0 <a ≦ 0.55, and b is 0.1 ≦ b ≦ 2). X represents at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen. Such a first compound exhibits high hardness with respect to a compound having a structure not containing Zr. This is probably because, in the crystal lattice of the first compound, Zr is mixed as an interstitial type or a substitution type with respect to Hf at a specific portion of the HfN crystal structure in which the NaCl type cubic crystal is present. It is speculated that it may be due to miniaturization.

  The zirconium-containing hafnium layer in the present invention can be composed of only the first compound except for inevitable impurities. However, it may contain other components (elements) as described later, and may be formed by laminating a layer containing a first compound and a layer containing another compound as described later. .

  In addition, such a zirconium-containing hafnium layer includes a secondary compound (formed simultaneously with the formation of the first compound or formed over time after the formation of the first compound) together with the first compound. It can be included. Such a secondary compound is contained in a small amount with respect to the first compound, for example, a compound composed of Hf and X in the above chemical formula, a compound composed of Zr and X in the above chemical formula, and the like. Hf simple substance and Zr simple substance can also be mentioned.

<First compound>
The first compound contained in the zirconium-containing hafnium layer has the chemical formula Hf _{1 -a} Zr _a X _b (where a and b each represent an atomic ratio, where a is 0 <a ≦ 0.55 and b is 0.1 ≦ b ≦ 2, and X represents a compound represented by at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen. In the above chemical formula, the atomic ratio a is preferably 0 <a ≦ 0.50, and the lower limit is 0.005, more preferably 0.01. When the atomic ratio a exceeds 0.55, the effect of reducing crater wear is inferior and excellent wear resistance is not exhibited.

  In the above chemical formula, X represents at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen. That is, X may be composed of these elements alone or in combination of two or more elements. In the case where two or more elements are combined, the atomic ratio of each element is not particularly limited. However, when nitrogen is included, these elements occupy these constituent elements (that is, with respect to b in the above chemical formula). It is preferable that the atomic ratio of nitrogen is 50% or more.

  Further, the atomic ratio b is not particularly limited as long as 0.1 ≦ b ≦ 2, but more preferably 0.4 ≦ b ≦ 1.8. When b is less than 0.1, the wear resistance is lowered, which is not preferable. On the other hand, if b exceeds 2, the wear resistance is lowered, which is not preferable. In addition, when X is comprised with 2 or more types of elements as mentioned above, the atomic ratio b shall show the total amount of those elements.

<Crystal structure of the first compound>
The first compound has a crystal structure in which a ratio (B / A) of (111) plane peak intensity A to (200) plane peak intensity B in X-ray diffraction satisfies 0 ≦ B / A ≦ 1. And That is, the crystal structure defined in this way indicates that the orientation of the first compound in the present invention is not (200) preferred orientation but (111) preferred orientation. The upper limit of the ratio B / A is more preferably 0.8, still more preferably 0.5, and the lower limit is ideally 0.

  Thus, when the crystal structure of the first compound exhibits (111) preferential orientation, extremely high wear resistance can be exhibited. In the present invention, it has been found that the (111) preferential orientation has extremely high lubricity compared to the case of the (200) preferential orientation, thereby improving the wear resistance during cutting. Conceivable.

In the first compound of the present invention, the peak position 2θ ₍₁₁₁₎ of the (111) plane in X-ray diffraction is 32 ° or more and 34 ° or less, and the peak position 2θ _{(200) of the} (200) plane is 39 ° or more. It preferably has a crystal structure of 40 ° or less. More preferably, the peak position 2θ ₍₁₁₁₎ of the (111) plane is 33.5 ° or more and 34 ° or less, and the peak position 2θ _{(200) of the} (200) plane is 39 ° or more and 39.5 ° or less. Such X-ray diffraction is preferably based on the θ-2θ method.

It is known that the peak position 2θ ₍₁₁₁₎ of the (111) plane of HfN is generally 34.302 °, and the peak position 2θ ₍₂₀₀₎ of the (200) plane is generally 39.817 °. It is known that there is. Therefore, the crystal structure of the first compound in the present invention defined by the peak position as described above shows that the peak position clearly exists on the low angle side in the (111) plane and the (200) plane. Yes. This is presumably because Zr exists as an interstitial or substituted type for Hf at a specific site in the crystal lattice of the first compound.

  Thus, in the crystal structure of the first compound, since the peak positions of the (111) plane and the (200) plane exist at a lower angle than the peak positions of HfN and ZrN alone, a large distortion occurs in the crystal structure. Is considered to exist. This strain is considered to improve the mechanical properties of the coating, such as hardness and toughness, and the synergistic action of these increases the cutting performance.

  Furthermore, the first compound in the present invention preferably has a crystal grain size of 0.1 nm to 200 nm, more preferably the upper limit is 100 nm, and still more preferably the upper limit is 60 nm. The lower limit is more preferably 10 m, and the lower limit is further preferably 20 nm. If the crystal grain size is less than 0.1 nm, the crystallinity is not sufficient and cannot be distinguished from the amorphous state, and if it exceeds 200 nm, the cutting performance may deteriorate.

  As described above, the crystal grain size of the first compound in the present invention is preferably minute as in the range shown above, and the smaller the size, the more dense the membrane structure is promoted and the toughness is improved. Will be improved. Therefore, the smaller the crystal grain size, the better. However, if the crystal grain size is less than 0.1 nm as described above, the crystal state cannot be maintained and an amorphous state is obtained, so that the cutting performance is degraded.

  In addition, such a crystal grain diameter means the average value which can be calculated | required from the half value width of the peak resulting from the (111) plane in X-ray diffraction.

<Other components contained in the zirconium-containing hafnium layer>
The zirconium-containing hafnium layer in the present invention can contain at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta, and W. By containing Si, Ti, Nb, Ta, the hardness is increased and the wear resistance is improved. Moreover, by adding Mo, oxidation resistance can be improved and crater wear can be further reduced. Further, by containing V and W, both hardness and oxidation resistance are improved, and improvement of wear resistance and reduction of crater wear can be achieved.

  The aspect in which the zirconium-containing hafnium layer in the present invention contains at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta and W is not particularly limited, and the first compound is Si, Ti, It may contain at least one element selected from the group consisting of Nb, Mo, V, Ta and W, or may be contained independently of such a first compound. When the first compound contains at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta and W, these elements are interstitial or substitutional in the first compound. It is preferable to contain as.

  In addition, at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta, and W exhibiting excellent effects as described above is 0.005 or more and 0.000 or more in terms of atomic ratio with respect to Hf. It is preferably contained in a ratio of 3 or less. When the atomic ratio is less than 0.005 or exceeds 0.3, the above excellent effects may not be exhibited. In addition, when two or more types of the above elements are included, the atomic ratio between the elements is not particularly limited as long as the total amount is included in the atomic ratio within the above range.

<Laminated structure of zirconium-containing hafnium layer>
In the present invention, the zirconium-containing hafnium layer may be formed by laminating one or more first layers including the first compound and a second layer including the second compound. The two compounds are at least one element selected from the group consisting of Si, Cr, Al, Ti, Hf, Ta, Nb and V, and at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen Can be included. Such a first layer preferably has a thickness of each layer of 0.5 nm or more and 200 nm or less, and similarly, the second layer preferably has a thickness of each layer of 0.5 nm or more and 200 nm or less.

  Here, the second compound is selected from the group consisting of at least one element selected from the group consisting of Si, Cr, Al, Ti, Hf, Ta, Nb and V, and boron, oxygen, carbon, and nitrogen. It is preferable that at least one element is contained in an atomic ratio of 0.1 or more and 2 or less. By setting the atomic ratio within this range, the following excellent effects are exhibited. In addition, when two or more different elements among Si, Cr, Al, Ti, Hf, Ta, Nb, and V are included, the atomic ratio between the elements is sufficient as long as the total amount satisfies the atomic ratio in the above range. Is not particularly limited. Similarly, when two or more different elements of boron, oxygen, carbon, and nitrogen are included, the atomic ratio between the elements is not particularly limited.

  By adopting the laminated structure as described above, the following excellent effects are exhibited. That is, since the second compound is excellent in oxidation resistance, the wear resistance of the entire zirconium-containing hafnium layer is shown in addition to the action of reducing crater wear and the action of improving wear resistance. In addition, by laminating two layers having different compositions in this way, it is possible to extremely effectively prevent cracks from progressing in the thickness direction of the film, and wear phenomenon caused by film destruction due to the progress of the cracks can be suppressed. As a result, the wear resistance can be further improved.

  Here, as described above, each first layer preferably has a thickness of 0.5 nm to 200 nm, and each second layer also preferably has a thickness of 0.5 nm to 200 nm. . This is because having a thickness in this range exhibits particularly excellent wear resistance during cutting. And as for each thickness of the said 1st layer and 2nd layer, More preferably, the upper limit is 100 nm, More preferably, it is 50 nm, The minimum is 1 nm. It is difficult to form each layer with a thickness of less than 0.5 nm, and when the thickness exceeds 200 nm, the above excellent effects may not be exhibited.

  Further, it is preferable that the added total thickness of only the first layer is 0.3 μm or more and 10 μm or less, more preferably 0.7 μm or more and 5 μm or less. By making the added total thickness of only the first layer within these ranges, the above effect is most effectively exhibited. In addition, as long as the added total thickness of only the first layer falls within such a range, the added total thickness of only the second layer is not particularly limited, but a thickness of 1 μm or more and 10 μm or less is usually sufficient. The thicknesses of the first layer and the second layer stacked in this way may be approximately equal or different.

  Note that the laminated structure indicates that the first layer and the second layer are formed by laminating one or more layers, and more preferably, the first layer and the second layer are respectively formed. It is preferable that a plurality of layers are stacked alternately one above the other. In such a laminated structure, the lowermost layer and the uppermost layer may be formed of either the first layer or the second layer. The number of stacked layers is not particularly limited, but each layer may be 1 to 8000 layers, preferably 20 to 5000 layers.

<Thickness of zirconium-containing hafnium layer>
The zirconium-containing hafnium layer of the present invention preferably has a thickness of 0.3 μm or more and 10 μm or less. More preferably, the upper limit is 8 μm, more preferably 6 μm, and the lower limit is 0.7 μm, more preferably 1 μm.

  If the thickness is less than 0.3 μm, the effect of the present invention that reduces crater wear and imparts high wear resistance may not be shown, and if it exceeds 10 μm, the effect may be reduced. is there. In the case where the thickness is 1 μm or more and 6 μm or less, particularly excellent effects are exhibited.

<Underlayer>
In the surface-coated cutting tool of the present invention, a base layer may be formed as a coating on a base material, and the zirconium-containing hafnium layer may be formed on the base layer, and the base layer may include Ti and boron, A third compound containing at least one element selected from the group consisting of oxygen, carbon, and nitrogen can be included. This third compound is excellent in adhesion to the base material. Therefore, if the base layer is formed on the base material so as to be in contact with the base material, and the zirconium-containing hafnium layer is formed on the base layer, these As a whole, the coating film has high adhesion and is formed on the substrate.

  Examples of such a third compound include TiN, TiC, TiCN, TiBN, TiON, TiZrN, and TiWN. In addition, when atomic ratio is not prescribed | regulated especially in these chemical formulas, the atomic ratio of each element does not necessarily become an equivalent ratio, but all the conventionally well-known atomic ratio shall be included. For example, when describing TiN, the atomic ratio of Ti and N includes 1: 1, and includes 2: 1, 1: 0.95, 1: 0.9, etc. (otherwise unless otherwise specified) The same in the description of chemical formulas). That is, the atomic ratio of Ti to at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen (including other (metal) elements in addition to Ti includes the atomic ratio of the elements, boron, In the case where two or more kinds of oxygen, carbon or nitrogen are contained, the atomic ratio between these elements is also not particularly limited, and all conventionally known atomic ratios are included.

  The underlayer as described above preferably has a thickness of 0.05 μm to 2 μm, more preferably 0.1 μm to 1 μm. In addition, such an underlayer can be composed of one layer, or can be composed of two or more layers (when composed of two or more layers, the total thickness is within the above range). ).

<Other layers>
The coating in the present invention may further contain one or more layers other than the zirconium-containing hafnium layer and the underlayer as described above. For example, such other layers can be formed between the underlayer and the zirconium-containing hafnium layer, or can be formed on the zirconium-containing hafnium layer. By forming such other layers, the effect of the present invention of reducing crater wear and imparting high wear resistance can be further improved, or lubricity can be imparted. The effect that adhesion can be suppressed can also be achieved.

Examples of such a compound forming another layer include oxides such as Al ₂ O ₃ , siliconitrides such as TiSiN, and carbonitrides such as TiCN. Note that such other layers preferably have a thickness of 0.05 μm to 5 μm, preferably 0.1 μm to 2 μm.

<Manufacturing method>
Since the layer included in the coating in the present invention, particularly the zirconium-containing hafnium layer, needs to be composed of a highly crystalline compound as described above, the coating of the present invention is composed of such a highly crystalline compound. The film is preferably formed by such a film forming process. Therefore, it is desirable that the film of the present invention is formed by physical vapor deposition (PVD method). Examples of such physical vapor deposition include balanced magnetron sputtering, unbalanced magnetron sputtering, arc ion plating, and combinations of these. Even when the zirconium-containing hafnium layer is formed in the above laminated structure, it can be formed by a conventionally known method under these physical vapor deposition methods.

  In particular, specific conditions for suitably forming the zirconium-containing hafnium layer as described above are as follows. That is, when the arc ion plating method is adopted, a target containing each corresponding element at an appropriate blending ratio is set in an arc evaporation source so as to obtain a first compound having a desired structure, and a substrate (base material) ) The temperature is set to 400 to 700 ° C. and the reaction gas pressure in the apparatus is set to 2.0 to 6.0 Pa, and one or more gases are selected as the reaction gas from, for example, nitrogen, methane, acetylene, oxygen, etc. Introduce this. Then, while maintaining the substrate (negative) bias voltage at −60 V to −200 V, an arc current of 50 to 120 A is supplied to the cathode electrode, and metal ions are generated from the arc evaporation source, thereby forming the zirconium-containing hafnium layer. Can be formed.

When the unbalanced magnetron sputtering method is adopted, the substrate (base material) temperature is set to 400 to 600 ° C., the reaction gas pressure in the apparatus is set to 300 mPa to 800 mPa, and the reaction gas corresponding to the desired first compound For example, select one or more gases from nitrogen, methane, acetylene, and oxygen and introduce them (in addition, when introducing the reaction gas, the volume ratio of the rare gas / reaction gas should be set to 1 to 5) Is preferred). Then, while maintaining the substrate (negative) bias voltage at 0V to -90V (the higher the bias voltage is on the negative side, the orientation of the crystal structure of the first compound tends to be improved). A zirconium-containing hafnium layer can be formed by generating a power density of 12 to 0.3 W / mm ² .

  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 (composition of the compound) of each layer constituting each of the following films is confirmed by an energy dispersive X-ray fluorescence spectrometer (SEM-EDX) attached to a scanning electron microscope (SEM), and the thickness of each layer is It confirmed by observing the cross section of a film using SEM.

  In this example, the coating film formed on the substrate was formed by the cathodic arc ion plating method or the unbalanced magnetron sputtering method as follows.

<Cathode-type arc ion plating method>
First, as a base material, a cutting tip having a grade of P30 (JIS-B-4053, 1998) and a shape of SNGN120408 (JIS-B-4121, 1998) was prepared and washed. Then, it was set at the substrate mounting position in the cathode type arc ion plating apparatus (film forming apparatus).

As such a film forming apparatus, a conventionally known apparatus can be used without any particular limitation. And while reducing the inside of this apparatus to 1x10 <^-4> Pa or less with a vacuum pump, the temperature of the said base material was heated to 650 degreeC with the heater installed in this apparatus, and it hold | maintained for 1 hour.

  Next, argon gas was introduced to maintain the pressure in the apparatus at 3.0 Pa, the substrate (base material) bias voltage was gradually increased to −1500 V, and the surface of the base material was cleaned for 15 minutes. Thereafter, argon gas was exhausted.

  Next, each target containing each corresponding element so that its chemical composition is as shown in Table 1 below, as a film (that is, a zirconium-containing hafnium layer made of the first compound) formed on the substrate surface. Was set in a raw material evaporation source (an arc evaporation source). The substrate (base material) temperature is set to 550 to 650 ° C., the reaction gas pressure in the apparatus is set to 4.0 Pa, and the reaction gas corresponding to the chemical composition shown in Table 1 is selected from among nitrogen, methane, and oxygen. The above gases were selected and introduced. Then, while maintaining the substrate bias voltage at −80 V, an arc current of 50 to 120 A was supplied to the cathode electrode, and metal ions were generated from the arc evaporation source to form a zirconium-containing hafnium layer. That is, a metal ion, a metal element, or a cluster generated from an arc evaporation source reacts with the reaction gas in a plasma atmosphere to form a zirconium-containing hafnium layer (that is, a first compound) on the substrate (deposition). ) Will be. As the reaction gas, nitrogen is selected when the final product (first compound) is a nitride, and methane (a hydrocarbon gas such as acetylene is not limited to methane, but is not limited to methane). And argon gas can be selected as the atmospheric gas (for reactive gas partial pressure control), and in the case of oxide, argon gas can be selected as the oxygen and atmospheric gas (for reactive gas partial pressure control). In the case of other carbonitrides or nitride oxides, two or more kinds of reaction gases were selected and used based on the above example. When boron was included in the chemical composition, a target containing a desired amount of boron element in advance was used.

  And when the thickness described in Table 1 is reached, the current supplied to the arc evaporation source is stopped, and after cooling, the inside of the apparatus is opened to the atmosphere, and then the surface-coated cutting tool with the coating formed on the substrate is used. By taking out from the apparatus, the surface-coated cutting tool of the present invention was produced. In the section of “Production method” in Table 1, the surface-coated cutting tool produced by this cathodic arc ion plating method is indicated as “A”.

<Unbalanced magnetron sputtering method>
First, as a base material, a base material of the same standard as that used in the above-described cathodic arc ion plating method was prepared, washed, and then set at a substrate mounting position in a sputtering apparatus (film forming apparatus). . Next, each target containing each corresponding element so that its chemical composition is as shown in Table 1 below, as a film (that is, a zirconium-containing hafnium layer made of the first compound) formed on the substrate surface. Set. The target may be an alloy target, or a single metal target may be divided and used so as to have the above chemical composition. As such a film forming apparatus, a conventionally known apparatus can be used without any particular limitation.

And while reducing the inside of this apparatus to 1x10 <^-4> Pa or less with a vacuum pump, the temperature of the said base material was heated to 500 degreeC or more with the heater installed in this apparatus, and it hold | maintained for 1 hour.

  Next, argon gas was introduced to maintain the pressure in the apparatus at 500 mPa to 650 mPa, the substrate (base material) bias voltage was gradually increased to −600 V, and the surface of the base material was cleaned for 30 minutes. Subsequently, the substrate bias voltage was set to −350 V, and the substrate surface was further cleaned for 60 minutes using a holocathode gas activation source. Thereafter, argon gas was exhausted.

  Next, the substrate (base material) temperature is set to 500 to 600 ° C., the reaction gas pressure in the apparatus is set to 500 mPa to 650 mPa, and the reaction gas corresponding to the chemical composition shown in Table 1 is selected from among nitrogen, acetylene, and oxygen. One or more gases were selected from and introduced. In introducing the reaction gas, the volume ratio of the rare gas / reaction gas was set to 1 to 5.

Then, a power density of 0.12 to 0.3 W / mm ² is generated on the target while maintaining the substrate bias voltage at −90 V, thereby forming a coating (that is, a zirconium-containing hafnium layer made of the first compound) on the base material. ) Was formed. The power density supplied to the target was stopped when the coating reached the thickness shown in Table 1.

  A DC pulse method was used as the substrate bias power source and the target supply power source. The substrate bias power supply supplies positive and negative voltages at a frequency of 350 kHz, and the time for supplying the positive voltage per cycle is 500 ns. The frequency of the power supply for target supply was 50 kHz, and the supply time of positive and negative voltages per cycle was half each.

  As described above, a rare gas (argon is preferable but not limited to this) is always mixed in the reaction gas at a rare gas / reactive gas volume ratio of 1 to 5. The selection criteria for the reaction gas are the same as those for the cathode arc ion plating method. When boron was included in the chemical composition, a target containing a desired amount of boron element in advance was used.

  Thus, the surface-coated cutting tool of the present invention was produced. In addition, in the section of “Production method” in Table 1, the surface-coated cutting tool produced by this unbalanced magnetron sputtering method was represented as “S”.

<Mixed elements>
The element described in the “mixed element” section of Table 1 represents another element contained in the zirconium-containing hafnium layer. The atomic ratio in the “atomic ratio of mixed element” indicates the atomic ratio of the “mixed element” to Hf contained in the zirconium-containing hafnium layer. In Table 1, “mixed elements” marked with “*” indicates that the mixed element is included in the first compound (those without the “*” sign are the first ones). It is included independently of the compound.)

  In Table 1, an embodiment including such a mixed element can be manufactured by using a target including the corresponding element in the target used in each of the above manufacturing methods. The atomic ratio in the target was approximately the atomic ratio described in the above-mentioned atomic ratio section of the mixed element.

<Laminated structure>
In the section of “Laminated structure” in Table 1, when the zirconium-containing hafnium layer is formed by laminating the first layer and the second layer described above, it is denoted as “present”. When it is not (that is, in the case of a single layer), it is described as “none”.

  In the case where such a laminated structure is formed by the cathodic arc ion plating method, the target 1 for forming the first layer (the composition is set to a composition that can obtain the first compound shown in Table 1) and the first layer A target 2 for forming two layers (the composition is set to a composition that can obtain the second compound shown in Table 3) is set on the inner wall of the apparatus at the same height, and an intermediate point between the two targets (approximately the center of the apparatus). ) Was set on the substrate. Then, by rotating the base material while evaporating both the target 1 and the target 2, a first layer is formed when the base material is located in front of the target 1, and when the base material is located in front of the target 2, the first layer is formed. Two layers were formed. A laminated structure can be formed in this way, but the conditions for evaporating the target were the same as the above conditions for forming the zirconium-containing hafnium layer.

  Further, when such a laminated structure is formed by the unbalanced magnetron sputtering method, the base material, the target 1 and the target 2 are disposed in the apparatus in the same manner as in the case of the cathode arc ion plating method. And the laminated structure was able to be formed by employ | adopting the conditions similar to the said sputtering conditions which form a zirconium containing hafnium layer.

  Details of the laminated structure thus obtained are shown in Table 3. In Table 3, the first layer is composed of the first compound described in Table 1, and the second layer is composed of the second compound described in Table 3. And each layer was laminated | stacked alternately by the thickness described in Table 3, and the zirconium containing hafnium layer of the thickness described in Table 1 was formed. In addition, the lowest layer of each laminated structure was the first layer, and the uppermost layer was the second layer.

As described above, the surface-coated cutting tools of Examples 1 to 22 having the configurations described in Table 1 and Table 3 were manufactured. The surface-coated cutting tools of these examples are provided with a substrate and a coating formed on the substrate, and this coating has the chemical formula Hf _1-a Zr _a X _b (where a and b are Each represents an atomic ratio, a is 0 <a ≦ 0.55, b is 0.1 ≦ b ≦ 2, and X is at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen. The first compound is a zirconium-containing hafnium layer containing the first compound represented by the formula (1), and the first compound has a peak intensity A on the (111) plane and a peak intensity on the (200) plane in X-ray diffraction as will be confirmed below. The ratio B / A with B is characterized by having a crystal structure in which 0 ≦ B / A ≦ 1.

<Confirmation of crystal structure>
The surface-coated cutting tools of Examples 1 to 22 manufactured as described above were subjected to X-ray diffraction by the θ-2θ method, and the crystal structure of the zirconium-containing hafnium layer (that is, the first compound), that is, the (111) plane The ratio B / A of the peak intensity A and the peak intensity B of the (200) plane, the crystal grain size and the peak position were determined. X-rays were CuKα rays, and the crystal grain size (that is, the crystal grain size of the first compound) was calculated from the half width of the (111) plane. These results are shown in Table 3 below.

(Comparative Examples 1-6)
As Comparative Example 1, a surface-coated cutting tool in which a film having a laminated structure with TiSiN in which the atomic ratio a in the above chemical formula exceeds 0.55 in the first compound was produced was produced. In addition, as Comparative Example 2, a surface-coated cutting tool in which a film made of a compound containing no Zr in the first compound (specifically, HfN) was formed on a substrate was manufactured. In Comparative Example 3, a film made of a compound having the same composition as the first compound of Example 2 was formed. By changing the bias voltage during film formation, the peak intensity A on the (111) plane was This is a surface-coated cutting tool different from Example 2 in that the ratio B / A to the peak intensity B of the (200) plane is 1.15.

Comparative Example 4 is a surface-coated cutting tool obtained in the same manner as in Example 2 except that the atomic ratio a in the above chemical formula exceeds 0.55 in the first compound. Comparative Example 5 is a surface-coated cutting tool obtained in the same manner as in Example 2 except that the atomic ratio b in the chemical formula of the first compound is less than 0.1.
Comparative Example 6 is a surface-coated cutting tool obtained in the same manner as in Example 2 except that the atomic ratio b in the chemical formula of the first compound exceeds 2. The physical properties of the surface-coated cutting tools of these comparative examples are shown in Tables 1-3.

<Cutting test>
For the surface-coated cutting tool of the present invention of Examples 1-22 and the surface-coated cutting tool of Comparative Examples 1-6 manufactured as described above, a continuous turning test was performed for 10 minutes under the following cutting conditions, The flank wear amount Vb (mm) and the crater wear amount Kt (mm) were measured. The smaller the flank wear amount, the better the wear resistance, and the smaller the crater wear amount, the lower the crater wear. The results are shown in Table 4 below.

(Cutting conditions)
Work material: SCM435
Cutting speed: 300 m / min
Cutting depth: 1.0mm
Feed: 0.2 mm / rev.
Dry / Wet: Dry

In Tables 1 and 2, “a”, “b”, and “X” represent a, b, and X in the chemical formula Hf _1-a Zr _{a Xb} , which is the first compound, respectively. The “mixed element” refers to an element other than Hf, Zr, and X in the above chemical formula contained in the first compound as described above. In addition, the numerical value described in the item of “X” indicates an atomic ratio (the sum of those numerical values is the numerical value described in “b”). “Atom ratio of mixed element” indicates an atomic ratio with respect to Hf contained in the first compound as described above. “Thickness” indicates the thickness of the zirconium-containing hafnium layer or a layer corresponding thereto. In Table 2, the numerical value described in the “second compound” section indicates the atomic ratio.

  As is apparent from Table 4, the surface-coated cutting tool of the example of the present invention showed superior results in both reducing crater wear and improving wear resistance compared to the surface-coated cutting tool of the comparative example. It is clear that Therefore, the surface-coated cutting tool of the present invention has excellent cutting performance.

  In the above-described embodiments, only the zirconium-containing hafnium layer is formed as a coating on the base material. However, the base layer as described above is formed on the base material, and the zirconium-containing hafnium layer is formed on the base layer. A layer can also be formed and the adhesiveness of a base material and a film can be improved further.

  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.

Claims (11)

A surface-coated cutting tool comprising a substrate and a coating formed on the substrate,
The coating consists of one or more layers,
At least one of the layers has the chemical formula Hf _1-a Zr _a X _b (where a and b each represent an atomic ratio, where a is 0 <a ≦ 0.55 and b is 0.1 ≦ b ≦ 2) X is a zirconium-containing hafnium layer containing a first compound represented by the following formula: X represents at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen;
The first compound has a crystal structure in which the ratio B / A between the peak intensity A of the (111) plane and the peak intensity B of the (200) plane in X-ray diffraction is 0 ≦ B / A ≦ 1. tool. The surface-coated cutting tool according to claim 1, wherein a in the chemical formula Hf _1-a Zr _{a Xb} is 0 <a ≦ 0.50.   The surface-coated cutting tool according to claim 1 or 2, wherein the first compound has a crystal grain size of 0.1 nm or more and 200 nm or less. In the first compound, the peak position 2θ ₍₁₁₁₎ of (111) plane in X-ray diffraction is 32 ° or more and 34 ° or less, and the peak position 2θ _{(200) of} (200) plane is 39 ° or more and 40 ° or less. The surface-coated cutting tool according to any one of claims 1 to 3, which has a certain crystal structure.   The surface-coated cutting tool according to any one of claims 1 to 4, wherein the zirconium-containing hafnium layer includes at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta, and W.   The surface-coated cutting tool according to any one of claims 1 to 5, wherein the first compound includes at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta, and W.   6. The at least one element selected from the group consisting of Si, Ti, Nb, Mo, V, Ta, and W is contained in an atomic ratio of 0.005 or more and 0.3 or less with respect to Hf. Or the surface covering cutting tool of 6. In the zirconium-containing hafnium layer, one or more first layers including the first compound and second layers including the second compound are alternately stacked,
The second compound is at least one element selected from the group consisting of Si, Cr, Al, Ti, Hf, Ta, Nb and V, and at least one selected from the group consisting of boron, oxygen, carbon and nitrogen. The surface covering cutting tool in any one of Claims 1-7 containing these elements. Each of the first layers has a thickness of 0.5 nm or more and 200 nm or less,
The surface-coated cutting tool according to claim 8, wherein each of the second layers has a thickness of 0.5 nm or more and 200 nm or less.   The coating includes a base layer, the base layer is formed on the base material, and the zirconium-containing hafnium layer is formed on the base layer, and the base layer includes Ti, boron, oxygen, carbon, and The surface-coated cutting tool according to any one of claims 1 to 9, comprising a third compound containing at least one element of the group consisting of nitrogen.   The surface-coated cutting tool according to claim 1, wherein the zirconium-containing hafnium layer has a thickness of 0.3 μm or more and 10 μm or less.