JP2008279562A - Surface-coated cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool having a coating capable of reducing crater wear and applying sophisticated wear resistance. <P>SOLUTION: This surface-coated cutting tool has a base material and the coating formed on the base material. The coating includes one or more layers, and at least one of the layers is a hafnium-containing silicon layer including an amorphous first compound indicated by a chemical formula of Si<SB>1-X</SB>Hf<SB>X</SB>Z<SB>Y</SB>(wherein, X and Y indicate an atomic composition ratio, respectively, and 0< X ≤0.4 and 0.8≤ Y ≤1.2, and Z indicates at least one element selected from a group comprising boron, oxygen, carbon and nitrogen.). <P>COPYRIGHT: (C)2009,JPO&INPIT

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 addition, sintered silicon nitride is widely used as a base material for cutting tools because of its excellent mechanical strength, toughness, and thermal shock resistance, but the work materials are diversified and the processing efficiency is improved. In view of the fact that high-speed cutting is required to achieve this, the life of the cutting tool is much shorter than before.

  For this reason, the characteristics required for the cutting tool, in particular, the wear resistance, are becoming increasingly sophisticated, and various advanced characteristics are also required for the coating of the surface-coated cutting tool.

  Conventionally, as a method of modifying the surface characteristics of the base material with a coating, a method of providing a coating made of a mixture containing SiN and HfN has been proposed (Patent Documents 1 and 2). However, none of these proposals relate to a cutting tool, but to a thin film interference filter, a thermal printer head, and a magneto-optical recording medium. Therefore, it hardens the surface of the base material, imparts chemical resistance, or improves the flatness of the surface of the base material, and the wear resistance has not been studied at all.

  Also, composite materials containing SiHfN have been proposed as coatings for modifying the surface characteristics of the base material (Patent Documents 3 and 4), but none of them relate to cutting tools, and cover window glass for automobiles or thermal The purpose is to cover the printer head. For this reason, the wear resistance under high temperature conditions in cutting of steel or the like has not been evaluated at all.

On the other hand, although a method for improving the wear resistance and thermal shock resistance of a cutting tool using silicon nitride has been proposed (Patent Document 5), the composition of the substrate itself is modified instead of the coating. It is not a study of the characteristics. Therefore, almost no attempt has been made to improve various characteristics such as wear resistance of a cutting tool by using a silicon-based compound as a coating.
Japanese Patent Laid-Open No. 06-003523 Japanese Patent Laid-Open No. 06-256939 Japanese Patent Laid-Open No. 05-170489 Japanese Patent Application Laid-Open No. 07-180044 Japanese Patent Laid-Open No. 06-329470

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a surface-coated cutting tool provided with a coating that can reduce crater wear and can impart high wear resistance. To do.

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, the coating including one or more layers, and at least one of the layers. The layer has the chemical formula Si _1-X Hf _X Z _Y (where X and Y each represent an atomic composition ratio, 0 <X ≦ 0.4 and 0.8 ≦ Y ≦ 1.2. Z represents at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen.) And is a hafnium-containing silicon layer containing an amorphous first compound.

  The hafnium-containing silicon layer preferably has a thickness of 0.1 μm to 10 μm.

  Further, the hafnium-containing silicon layer is formed by laminating one or more layers each including a first layer containing the first compound and a second layer containing a second compound, and the second compound contains Si, Containing at least one element selected from the group consisting of 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 do.

  The first layer preferably has a thickness of 0.5 nm to 200 nm, and the second layer preferably has a thickness of 0.5 nm to 200 nm.

  The coating may include one or more hard layers in addition to the hafnium-containing silicon layer, and the hard layers include groups IVa, Va, VIa, Al, and Si of the periodic table. Or at least one element selected from the group consisting of at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen. .

  The hard layer is at least one element selected from the group consisting of Cr, Al, Ti, and Si, or at least one selected from the group consisting of boron, oxygen, carbon, and nitrogen. It is preferable to include a compound composed of one element, and at least one element selected from the group consisting of Cr, Al, Ti, and Si, or at least one element selected from boron, oxygen, Two or more types of layers containing a compound consisting of at least one element selected from the group consisting of carbon and nitrogen may be laminated with each layer having a thickness of 1 nm or more and 100 nm or less and periodically repeated. preferable.

  Further, a cemented carbide, cermet, cubic boron nitride sintered body, high-speed steel, ceramics, or diamond sintered body can be applied to the base material of the surface-coated cutting tool of the present invention.

  The surface-coated cutting tool of the present invention can provide high wear resistance while reducing crater wear by providing a coating containing a specific hafnium-containing silicon layer on a substrate.

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 substrate and a film formed on the substrate. 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 extremely useful as a chip for an automobile. And, the surface-coated cutting tool of the present invention is a drill for heat-resistant alloy processing such as Ti alloy processing or Inconel alloy, end mill, milling or turning cutting edge replaceable cutting tip, metal saw, gear cutting tool, reamer, Particularly useful as a tap or the like.

<Base material>
As the base material of the surface-coated cutting tool of the present invention, a conventionally known material known as the base material of the cutting tool as described above can be used without any particular limitation. As such a base material, for example, a cemented carbide (for example, WC-based cemented carbide, including WC, including Co, or further including a carbonitride such as Ti, Ta, Nb, etc.), Cermet (mainly composed of TiC, TiN, TiCN, etc.), cubic boron nitride sintered body, high speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and mixtures thereof) Body), a diamond sintered body, and the like. When a cemented carbide is used as the 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. Even if the surface is modified in this way, the present invention The effect of is shown.

<Coating>
The coating film formed on the base material of the surface-coated cutting tool of the present invention includes one or more layers. And at least 1 layer is a hafnium containing silicon layer containing the 1st compound explained in full detail below among those layers. As long as the film in the present invention includes the hafnium-containing silicon layer, it may further include another layer. In addition, the film in this invention is not restricted only to what coat | covers the whole surface on a base material, The aspect in which the film was partially formed is also included.

  The total thickness of the coating film in the present invention (when two or more layers are formed, the total film thickness) is preferably 0.1 μm or more and 10 μm or less, more preferably the upper limit is 7.0 μm or less, The lower limit is preferably 0.5 μm or more, more preferably 1.0 μm or more. When the total thickness of the coating is less than 0.1 μm, the effect of improving various properties such as wear resistance may not be sufficiently exhibited. When the thickness exceeds 10 μm, the residual stress (referred to as compressive stress or compressive residual stress) increases. Adhesion with the material may be reduced. In addition, as a measuring method of the total thickness of a film, it can obtain | require by cut | disconnecting a surface coating cutting tool and observing the cross section using SEM (scanning electron microscope). Hereinafter, the coating will be described in more detail.

<Hafnium-containing silicon layer>
The hafnium-containing silicon layer according to the present invention has a chemical formula Si _1-X Hf _X Z _Y (where X and Y represent atomic composition ratios, 0 <X ≦ 0.4, 0.8 ≦ Y ≦ 1. And Z represents an amorphous first compound represented by the following formula: at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen. Such a first compound exhibits higher hardness than a compound having a structure not containing Hf. Although a clear cause is unknown, it is thought that stress will become low (compressive stress will become large) and hardness will become high as a result.

  The hafnium-containing silicon layer in the present invention can be composed of only the first compound except for inevitable impurities.

  Such a hafnium-containing silicon 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, and examples thereof include a compound composed of Si and Z in the chemical formula, and a compound composed of Hf and Z in the chemical formula. Si simple substance and Hf simple substance can also be mentioned.

  The hafnium-containing silicon layer may contain other compounds in addition to the first compound. Examples of such other compounds include 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. Examples thereof include a second compound containing at least one element selected from the group.

  In the present invention, the “hafnium-containing silicon layer” refers to a layer containing the first compound as described above, and only needs to include at least one layer containing the first compound. For example, in addition to the first compound, the hafnium-containing silicon is also used when the above-described other compound is included or when the first layer including the first compound and the second layer including the second compound are stacked. It shall be called a layer. In addition, the first compound may include those in which a part of Si or Hf is substituted with another element (for example, Zr, Cr, Ti, Mo, Al, W, Nb, V, etc.) in the chemical formula Even in such a case, it does not depart from the scope of the present invention.

<First compound>
The first compound contained in the hafnium-containing silicon layer has a chemical formula Si _1-X Hf _X Z _Y (where X and Y represent atomic composition ratios, 0 <X ≦ 0.4, 0.8 ≦ Y ≦ 1.2, and Z 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 composition ratio X is preferably 0 <X ≦ 0.25, and the upper limit thereof is more preferably 0.12, further preferably 0.1, and the lower limit thereof is more preferably 0.005. More preferably, it is 0.01. When the atomic composition ratio X exceeds 0.4, the hardness is lowered, the effect of reducing crater wear is inferior, and excellent wear resistance is not exhibited.

  The 1st compound in this invention has the characteristic that both wear of a flank and crater wear can be reduced effectively among the various characteristics requested | required of a cutting tool. This is because the residual stress is adjusted by including Hf at the atomic composition ratio as described above, the hardness is increased, and the original oxidation resistance provided by Si acts synergistically, thereby causing a flank. Wear and crater wear can be drastically reduced, and extremely excellent wear resistance can be imparted to the entire cutting tool.

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

  Further, the atomic composition ratio Y is not particularly limited as long as 0.8 ≦ Y ≦ 1.2. When Y is less than 0.8, the wear resistance is lowered, which is not preferable. On the other hand, if Y exceeds 1.2, the wear resistance is also lowered, which is not preferable. In addition, when Z is comprised with 2 or more types of elements as mentioned above, the atomic composition ratio Y shall show the total number of those elements.

<Structure of the first compound>
The first compound is amorphous. When the first compound is in an amorphous state, there is no crystal grain boundary between the compounds in the hafnium-containing silicon layer containing the compound, so that extension can be suppressed when cracks occur, and as a result It is considered to show excellent wear resistance. Moreover, since it is amorphous, abnormal crystal growth can be suppressed, and the surface of the resulting layer becomes smooth and exhibits excellent welding resistance.

<Laminated structure of hafnium-containing silicon layer>
The hafnium-containing silicon layer in the present invention may have a structure in which one or more layers each including a first compound having a different composition are laminated (for example, a layer containing SiHfN and a layer containing SiHfNO). Can be mentioned.) When it is set as such a laminated structure, the thickness of each layer, the number of layers, etc. can be made the same as the laminated structure of the 1st layer and 2nd layer which are mentioned later. In the case where the hafnium-containing silicon layer includes a laminated structure of a first compound composed of two or more layers containing a first compound having a different composition, not only the film has excellent wear resistance but also the interface between the layers. The presence of the can further suppress the extension of cracks.

  In the present invention, the hafnium-containing silicon layer may be formed by laminating one or more first layers including the first compound and second layers including the second compound. The second compound is composed of at least one element selected from the group consisting of Si, Cr, Al, Ti, Hf, Ta, Nb, and V, as described above, and boron, oxygen, carbon, and nitrogen. And at least one element selected from the group. Such a first layer preferably has a thickness of 0.5 nm to 200 nm, and similarly, the second layer preferably has a thickness of 0.5 nm to 200 nm.

  Here, the second compound is composed of boron, oxygen, carbon, and nitrogen with respect to at least one element selected from the group consisting of Si, Cr, Al, Ti, Hf, Ta, Nb, and V. It is preferable to contain at least one element selected from the group in an atomic composition ratio of 0.1 or more and 2 or less. By setting the atomic composition 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 composition between each element is sufficient as long as the total number satisfies the atomic composition ratio in the above range. The ratio is not particularly limited. Similarly, when two or more different elements of boron, oxygen, carbon, and nitrogen are included, the atomic composition 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 hafnium-containing silicon layer as a whole exhibits excellent oxidation resistance 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 the wear phenomenon caused by the film breakage due to the progress of the cracks is effective. As a result, the wear resistance can be further improved.

  As described above, the first layer preferably has a thickness of 0.5 nm to 200 nm, and the second layer also preferably has a thickness of 0.5 nm to 200 nm. This is because each layer has a thickness in this range, so that the wear resistance during cutting is particularly excellent. And as for each thickness of the said 1st layer and the 2nd layer, More preferably, the upper limit is 100 nm, More preferably, it is 50 nm, The lower limit is more preferably 1 nm. It is difficult to form each layer with a thickness of less than 0.5 nm. When the thickness exceeds 200 nm, the above-described excellent effects may not be shown. And it is a case where the addition total thickness of only the first layer is preferably 0.2 μm or more and 10 μm or less, and more preferably 0.7 μm or more and 5 μm or less. By making the total thickness of only the first layer within these ranges, the above effect is most effectively exhibited. As long as the total thickness of only the first layer falls within such a range, the 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.

  The laminated structure here means 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. It is preferable that a plurality of layers are alternately stacked. In such a laminated structure, the lowermost layer and the uppermost layer may be formed of either the first layer or the second layer. In addition, the number of stacked layers is not particularly limited, but each layer may be 1 layer or more and 8000 layers or less, more preferably 20 layers or more and 5000 layers or less.

<Thickness of hafnium-containing silicon layer>
The hafnium-containing silicon layer (except for the case including the above laminated structure) in the present invention preferably has a thickness of 0.1 μm or more and 10 μm or less. More preferably, the upper limit is 8 μm, more preferably 6 μm, and particularly preferably 3 μm. The lower limit is more preferably 0.3 μm.

  When the thickness is less than 0.1 μm, the effect of the present invention for reducing crater wear and imparting high wear resistance may not be shown. When the thickness exceeds 10 μm, the effect may be reduced. is there. In the case where the thickness is not less than 0.3 μm and not more than 3 μm, particularly excellent effects are exhibited.

  In the case where the hafnium-containing layer has a structure in which two or more layers each containing a first compound having a different composition are laminated one or more layers, the thickness is 0.1 μm or more and 10 μm or less, as in the case of not including the laminated structure The upper limit is more preferably 8 μm, still more preferably 6 μm, and particularly preferably 3 μm. The lower limit is more preferably 0.3 μm.

  Further, when the hafnium-containing layer includes a laminated structure formed by laminating one or more of the first layer and the second layer, the thickness of the layer is preferably 0.3 μm or more and 12 μm or less. More preferably, the upper limit is 8 μm and the lower limit is 0.5 μm.

  When the laminated structure and the laminated structure are included, if the thickness of the hafnium-containing layer is out of the above range, the effect of the present invention is not shown or the effect tends to decrease.

<Method for forming hafnium-containing silicon layer>
The method for forming the hafnium-containing silicon layer in the present invention is not particularly limited, but it is desirable to use a physical vapor deposition method (PVD method) in which the surface of the obtained film is smooth and the degree of freedom of composition is high. Specific examples include a balanced magnetron sputtering method, an unbalanced magnetron sputtering method, and a combination of these methods. Note that even if the hafnium-containing silicon layer is formed in the laminated structure as described above, it can be formed by a conventionally known method under these physical vapor deposition methods.

  In particular, specific conditions for suitably forming the above-described hafnium-containing silicon layer are as follows. That is, when the thickness of the hafnium-containing silicon layer is less than 0.3 μm and the unbalanced magnetron sputtering method is adopted, the substrate (base material) temperature is 350 to 650 ° C. and the reaction gas pressure in the apparatus is 400 mPa to Set to 1000 mPa, set a target having a composition for the desired first compound, and select, for example, one or more gases from nitrogen, oxygen, and methane as the reaction gas corresponding to the desired first compound, This is introduced (in addition, when introducing the reaction gas, the ratio of the rare gas / reaction gas is preferably set to 1 to 5). Then, an amorphous hafnium-containing silicon layer can be formed under the condition that the discharge power is 5 kW to 9.5 kW while the substrate (negative) bias voltage is maintained at 0 V to −90 V.

  The target having a composition corresponding to the desired first compound may be any target that provides a metal composition (a composition of silicon and hafnium) in the first compound. For example, a metal powder of silicon and hafnium may have a desired final composition. The Si—Hf sintered target prepared by mixing and sintering with the same composition as above, and the target made of Hf in the erosion part of the Si target, the area ratio of the erosion region satisfies X of the desired first compound. A bonding target or the like bonded with indium in composition can be used. Further, when boron is contained in the first compound, the target may contain boron element in advance, and the content may be the same as Y of the desired first compound.

  Further, when the thickness of the hafnium-containing silicon layer containing the amorphous first compound is 0.3 μm or more, the bias voltage is set within a range of −50 V to −550 V every time a certain thickness is formed. What is necessary is just to repeat the operation which changes rapidly more than 200V (for example, changing from -50V to -350V). Specifically, first, a substrate bias voltage of −50 V to −90 V is applied, and when the film is formed to 0.25 μm to 0.35 μm, the substrate bias voltage is rapidly changed from −350 V to −550 V, The substrate bias voltage is maintained until a film (total thickness) of 0.55 μm to 0.65 μm is formed again. Thereafter, the substrate bias voltage is rapidly changed from −350 V to 550 V to −50 V to −90 V again, and the substrate bias voltage is −350 V to −550 V until a coating is further formed to 0.85 μm to 0.95 μm (total thickness). Maintain a specific value in the range. Thus, the layer containing the amorphous first compound can be formed by rapidly changing the substrate bias voltage every time the film is formed to 0.25 μm to 0.35 μm.

<Hard layer>
In addition to the hafnium-containing silicon layer, the coating film according to the present invention further includes IVa group elements (Ti, Zr, Hf, etc.), Va group elements (V, Nb, Ta, etc.), VIa group elements (Cr, Mo, etc.) in the periodic table. , W, etc.), Al, and Si, or at least one element selected from the group consisting of at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen 1 or more hard layers comprised by the compound which consists of can be included.

  The hard layer is particularly selected from the group consisting of at least one element selected from the group consisting of Cr, Al, Ti, and Si, or at least one of the elements, and boron, oxygen, carbon, and nitrogen. It is preferable to include one or more films composed of a compound composed of at least one element.

  Such a hard layer preferably has a high hardness and excellent wear resistance, and exhibits extremely excellent toughness. In particular, at least one element selected from the group consisting of Cr, Al, Ti, and Si, or at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen, and at least one of the elements One or more coating films composed of a compound composed of an element are extremely effective because they have particularly excellent wear resistance because they are excellent in oxidation resistance and heat resistance.

Specific examples of the elements or compounds constituting the hard layer include, for example, Cr, Ti, Al, Si, V, Zr, Hf, TiAl, TiSi, AlCr, TiN, TiON, TiCN, TiCNO, TiBN, and TiCBN. , TiAlCN, AlN, AlCN, AlCrCN , AlON, CrN, CrCN, TiSiN, TiSiCN, Ti 2 O 3, TiAlON, ZrN, ZrCN, AlZrN, TiAlN, TiAlSiN, TiAlCrSiN, AlCrN, AlCrSiN, TiZrN, TiAlMoN, TiAlNbN, TiSiN, _{TiSiCN, AlCrTaN, AlTiVN, TiB 2} , TiCrHfN, CrSiWN, TiAlCN, TiSiCN, AlZrON, AlCrCN, AlHfN, CrSiBON, TiAlW , Mention may be made of AlCrMoCN, TiAlBN, the TiAlCrSiBCNO like.

  Also, at least one element selected from the group consisting of Cr, Al, Ti, and Si, or at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen, and at least one of the elements As the compound composed of elements, Ti, Cr, Al, Si, TiAlN, TiAlNO, TiAlCNO, TiBN, TiCBN, TiSiN, TiSiNO, TiSiCNO, CrTiN, CrTiNO, CrTiCNO, SiAlN, SiAlNO, SiAlCNO, CrSiN, CrSiNO, CrSiCNO, SiAlN, SiAlNO, SiAlCNO, CrSiN, CrSiNO, CrSiCNO, TiAlSiN, TiAlSiNO, TiAlSiCNO, TiAlCrN, TiAlCrNO, TiAlCrCNO, TiCrS N, TiCrSiNO, TiCrSiCNO, AlCrN, AlCrNO, AlCrSiNO, AlCrCNO, there may be mentioned AlCrSiBNO like, particularly AlCrN, AlCrNO, AlCrSiNO, AlCrSiBNO, AlCrCNO the like.

  In the above chemical formula, those in which the atomic composition ratio of each element is not particularly described do not necessarily mean an equivalence ratio, and all conventionally known atomic composition ratios are included. For example, when simply describing TiN, the atomic composition ratio of Ti and N includes 1: 1, and includes 2: 1, 1: 0.95, 1: 0.9, etc. (unless otherwise noted, The same applies below).

<Structure of hard layer>
The element and / or compound constituting the hard layer is preferably crystalline. When the element and / or compound constituting the hard layer is crystalline, the resulting coating film has high hardness, good oxidation resistance, and improved performance as a cutting tool.

<Laminated structure of hard layer>
As the hard layer, in particular, at least one element selected from the group consisting of Cr, Al, Ti, and Si, or a group consisting of boron, oxygen, carbon, and nitrogen with at least one element selected from the group It is preferable that two or more layers composed of a compound composed of at least one element selected from the above include one or more coatings that are laminated repeatedly with each layer having a thickness of 1 nm to 100 nm. In addition, the film in this invention can contain 2 or more of hard layers which have a multilayer structure.

  The thickness of each layer of the hard layer is more preferably 5 nm or more and 60 nm or less. As described above, by periodically repeating the above layers, the oxidation resistance and heat resistance are further improved, and extremely excellent wear resistance is exhibited. Here, “repetitively laminating” means laminating with a certain periodicity, for example, alternately laminating two kinds of layers. In addition, when the thickness of each layer is less than 1 nm or exceeds 100 nm, the effect of improving the abrasion resistance due to lamination may not be shown, but even in that case, the inherent effects brought about by these elements and compounds The effect of improving the wear resistance is shown.

<Thickness of hard layer>
The hard layer 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 may decrease, which is not preferable.

<Hard layer formation position>
The layered arrangement of the hard layers is not particularly limited, and can be formed between the base material and the hafnium-containing silicon layer, or on the hafnium-containing silicon layer, and formed on both the upper and lower sides of the hafnium-containing silicon layer. You can also

<Method for forming hard layer>
In the present invention, the hard layer is preferably formed by physical vapor deposition, and preferably has compressive residual stress. By forming the hard layer by physical vapor deposition, compressive residual stress can be imparted to the hard layer, and a coating film having high toughness can be obtained. Further, when the above-mentioned hafnium-containing silicon layer is formed by physical vapor deposition, the production efficiency can be improved by adopting the same film formation method as these films.

  As the physical vapor deposition method for forming the hard layer, a conventionally known physical vapor deposition method, for example, a sputtering method, a magnetron sputtering method, an arc ion plating method, an ion plating method, etc. can be employed. The arc ion plating method is preferred because it has the advantage of high productivity and high adhesion. Examples of the target include a sintered target having the same composition as a desired final composition.

<Other layers>
The coating film according to the present invention may further include one or more layers other than the above-described hafnium-containing silicon layer and hard layer. For example, such other layers can be formed between the hard layer and the hafnium-containing silicon layer, or can be formed on the hafnium-containing silicon 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 welding can be suppressed can also be achieved.

Examples of the compound constituting such another layer include oxides other than those exemplified as the compound forming the hard layer (for example, Al ₂ O ₃ ), nitrides, carbonitrides and the like. The thickness of such other layers is preferably 0.05 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 2 μm or less.

  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 the secondary electron microscope, and the thickness of each layer is determined by the thickness of the film. The cross section was confirmed by observing with a secondary electron microscope (SEM). The structure of each layer was analyzed with an X-ray diffractometer (XRD) and a transmission electron microscope (TEM).

<Base material>
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 used after cleaning.

<Method for forming film>
In each of the examples and comparative examples, each film is formed of a hafnium-containing silicon layer containing the first compound (Si _1-X Hf _X Z _Y ) by an unbalanced magnetron sputtering (UBMS) method. ) Was formed by a cathodic arc ion plating method. However, the case where the hafnium-containing silicon layer has a laminated structure composed only of the first compound (Example 12) and the case where the hafnium-containing silicon layer has a laminated structure composed of the first layer and the second layer (Examples 13 to 18, 24 and 25). ) Was formed by the UBMS method. Further, when the hard layer had a structure in which two or more kinds of layers were periodically laminated (Examples 20 to 22, 24, and 25 and Comparative Example 4), the hard layer was formed by an arc ion plating method. A conventionally known film-forming apparatus can be used without any particular limitation, but in this example and the comparative example, film formation by the UBMS method and film formation by the arc ion plating method are one. A film forming apparatus that can be performed in the apparatus was used. By using the apparatus, when a film is formed by combining the UBMS method and the arc ion plating method, the film can be formed continuously without taking the substrate out of the apparatus.

<Method for forming hafnium-containing silicon layer>
Each target including each corresponding element (having the same atomic composition ratio as that of the first compound in Table 1) was set so that the composition of the first compound was as shown in Table 1 below. . As the target, any of the above-mentioned sintered target, bonding target, etc. can be used, but in this example, Si and Hf powder are mixed at the respective atomic composition ratios, and sintered Si-Hf sintered target is used. did.

Then, the inside of the apparatus is reduced to 1 × 10 ⁻⁴ Pa or less by a vacuum pump, and the temperature of the base material is heated to 500 ° C. or more by a heater installed in the apparatus, and kept at about 500 ° C. for 1 hour. did.

  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. The cleaning is performed on the base material, and the cleaning is not performed on the coating surface of the base material on which the coating has already been formed (the same applies hereinafter).

  Next, the substrate (base material) temperature is set to 500 to 650 ° C., the reaction gas pressure in the apparatus is set to 400 mPa to 1000 mPa, and the reaction gas corresponding to the chemical composition shown in Table 1 is selected from among nitrogen, methane, and oxygen. This was introduced by selecting one or more gases from When introducing the reaction gas, the ratio of rare gas / reaction gas was set to 1-5.

  When the hafnium-containing silicon layer to be formed has a thickness of less than 0.3 μm, the discharge power applied to the target is set to 5 kW to 9.5 kW while the substrate bias voltage is maintained at −70 V, and the base material (the film is formed). A hafnium-containing silicon layer made of the first compound was formed on the substrate, and when the thickness shown in Table 1 was reached, the discharge power supplied to the target was stopped.

  On the other hand, when the thickness of the hafnium-containing silicon layer to be formed exceeds 0.3 μm, in order to make the entire layer amorphous (that is, to form the first compound in an amorphous state), as follows: An operation for changing the substrate bias voltage was performed. That is, when the layer was formed to 0.3 μm as described above, the substrate bias voltage was rapidly changed from −70 V to −350 V and maintained until a thickness of 0.3 μm was further formed. Thereafter, the substrate bias voltage was rapidly changed again from -350 V to -70 V, and the substrate bias voltage was maintained at -70 V until the layer was formed to a thickness of 0.3 μm. Thus, the hafnium-containing silicon layer having a desired thickness was formed by repeating the operation of rapidly changing the substrate bias voltage every time the layer was formed to have a thickness of 0.3 μm. The discharge power supplied to the target was stopped when the hafnium-containing silicon layer reached the thickness shown in Table 1.

  Here, 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.

  The reaction gas was always mixed with a rare gas (argon is preferable, but not limited thereto). Here, when the final product (first compound) is a nitride, nitrogen is selected as the reactive gas, and when it is a nitrogen oxide, nitrogen, oxygen, and atmospheric gas (for controlling the reactive gas partial pressure) are used as argon. Gas was selected. In the case of carbonitrous oxide, methane (a hydrocarbon gas such as acetylene can be used without limitation), nitrogen, oxygen, and atmospheric gas (for controlling the reaction gas partial pressure) are used. Gas was selected. When boron was included in the chemical composition, a target containing a desired amount of boron element in advance was used.

<Method for forming hard layer>
The hard layer was formed by the cathodic arc ion plating method as described above. A base material (including a film on which a film was already formed) was set at a substrate mounting position in the film forming apparatus. In addition, each target having the same composition as each corresponding composition was set as a raw material evaporation source (an arc evaporation source) so that the chemical composition of the hard layer was as shown in Table 1 below.

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 bias voltage was gradually increased to −1500 V, and the surface of the substrate was cleaned for 15 minutes. Thereafter, argon gas was exhausted. The cleaning was performed only on the base material as in the UBMS method.

  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. This was introduced by selecting the above gas. 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 hard layer.

  Then, when the thickness shown in Table 1 was reached, the current supplied to the arc evaporation source was stopped, and after cooling, the inside of the apparatus was opened to the atmosphere to form a hard layer.

<Method for forming hafnium-containing silicon layer having a laminated structure>
Example 12 shows that the hafnium-containing silicon layer has a structure in which the first compound (SiHfN) in Table 1 and the first compound (SiHfNO) in Table 2 are alternately stacked at a thickness of 3 nm and 2 nm ( Details of the structure will be described later). This laminated structure is formed by the UBMS method as described above. First, a target having the same composition as the desired first compound (common to the first compounds described in Tables 1 and 2) and a substrate were set in the apparatus. Then, the substrate was rotated while evaporating the target, and simultaneously, nitrogen, nitrogen, and oxygen as reaction gases were alternately supplied every time the desired thickness was formed. Each of the layers had a thickness of less than 0.3 μm, and a laminated structure could be formed by adopting the same conditions as those of the UBMS method when the substrate bias voltage was maintained at a constant value.

  On the other hand, Examples 13-18, 24, and 25 show that the hafnium-containing silicon layer has a structure in which the first layer and the second layer are alternately stacked with the thicknesses shown in Table 2. This laminated structure is also formed by the UBMS method as described above, and the conditions are the same as described above. However, as a target, a target for forming the first layer (the composition is the same as the first compound shown in Table 1) and a target for forming the second layer (the composition is shown in Table 2) Two types having the same composition as the second compound were used.

<Method for forming a hard layer having a structure in which two or more layers are periodically laminated>
The hard layer 1 of Examples 20-22, 24, 25 and Comparative Example 4 shows that it has the structure which laminated | stacked two types of compounds alternately as described in the term of the composition of Table 1. FIG. This structure is formed by the arc ion plating method as described above. That is, a target for forming a layer made of one compound and a target for forming a layer made of the other compound are set at the same height on the inner wall of the apparatus, and an intermediate point between both targets (approximately the center of the apparatus). Part). Then, by rotating the substrate while evaporating both these targets together, a layer made of the compound is formed when the substrate is located in front of one target, and when the substrate is located in front of the other target, A layer made of another compound was formed. In this manner, a periodically stacked structure can be formed, but the conditions for evaporating the target were the same as the above conditions.

As described above, the surface-coated cutting tools of Examples 1 to 25 and Comparative Examples 1 to 6 having the configurations described in Tables 1 and 2 were manufactured by appropriately combining the methods for forming the coating film. The surface-coated cutting tools of these examples comprise a substrate and a coating formed on the substrate, and this coating has the chemical formula Si _1-X Hf _X Z _Y (where X and Y are Each represents an atomic composition ratio, 0 <X ≦ 0.4, 0.8 ≦ Y ≦ 1.2, and Z is at least one selected from the group consisting of boron, oxygen, carbon, and nitrogen At least a hafnium-containing silicon layer characterized in that it contains an amorphous first compound represented by (1).

  On the other hand, the surface-coated cutting tools of Comparative Examples 1 to 6 are for comparison, and Comparative Examples 1, 5, and 6 are compounds that form a hafnium-containing silicon layer, and the atomic composition ratio X is 0 <X ≦ 0. A film is formed on a substrate using a compound that does not satisfy 4. Moreover, Comparative Examples 2-4 formed the film which does not contain a hafnium containing silicon layer. Specifically, in Comparative Example 2, a cutting tool in which a film made of TiAlN is formed is manufactured. In Comparative Example 3, a hard layer made of AlCrN is formed on a hard layer made of TiAlN, and a film made of TiN is formed on the uppermost layer. The formed cutting tool was manufactured. Moreover, in the comparative example 4, the cutting tool which formed the hard layer which has the structure which laminated | stacked the layer which consists of TiAlN and AlCrN periodically on the base material was manufactured.

  The numerical value described in the section “Z” in Table 1 indicates the atomic composition ratio (the sum of those numerical values is the numerical value described in “Y”). The numerical values described in the “Composition” section of Table 1 also indicate the atomic composition ratio. Further, in Table 1, the hafnium-containing silicon layers of Comparative Examples 1, 5, and 6 do not satisfy the range of the first compound of the present invention in the atomic composition ratio, but are included in the section of “hafnium-containing silicon layer” for convenience. It is described. Further, although Comparative Example 3 does not have a hafnium-containing silicon layer, AlCrN is described in the section of the first compound for convenience in order to clarify the order of film formation. The first compounds of Examples 1 to 25 and the compounds formed in Comparative Examples 1 and 5 to 6 described in the “Hafnium-containing silicon layer” section of Table 1 were amorphous. Moreover, the compound which comprises the hard layers 1 and 2 was crystalline.

Each coating film of this example and comparative example was formed on the base material in order from the left column side in Table 1. That is, the hard layer 1 was formed on the substrate surface, the hafnium-containing silicon layer was formed, and the hard layer 2 was formed on the uppermost surface. In addition, the blank ("-") in Table 1 indicates that no layer is formed. For example, in Examples 1, 2, 23, and Comparative Example 1, the hard layer 1 was not formed. It shows that a hafnium-containing silicon layer was formed on the substrate surface. In addition, in Example 23 (Note), a 2.0 μm first hard layer 2 made of Ti _0.5 Al _0.5 N _1.0 is formed on a hafnium-containing silicon layer, and an upper surface made of Ti _1.0 N _1.0 is formed with a thickness of 0. It shows that the 5 μm second hard layer 2 was formed.

  When the hard layer has a structure in which two or more kinds of layers are periodically laminated, the term “composition” is expressed in the form of “compound A / compound B” (the lowest layer is a layer containing compound A). And each layer was alternately laminated with the thickness described in Table 1 so that the uppermost layer was a layer containing Compound B). For example, in Example 20, a 5 nm layer of TiAlN is formed on the lowermost layer, a 5 nm layer of AlCrN is formed thereon, and a 5 nm layer of TiAlN and a 5 nm layer of AlCrN are formed in this order. It shows that the hard layer 1 having a total thickness of 2.0 μm was formed by repeating the forming operation to form a layer made of AlCrN as the uppermost layer.

  In Table 1, “Present” in the section of “Lamination” of the hafnium-containing silicon layer means that the hafnium-containing silicon layer has a laminated structure. 2 shows that the first compound or the second compound described in 2 is alternately laminated with the thickness described in Table 2 in each layer. In Table 1, “thickness” when the term of lamination is “present” indicates the thickness of the entire hafnium-containing silicon layer. In the case of “Yes”, the first compound is the first layer, and the second compound described in Table 2 below is the second layer. For example, in Example 13, the thicknesses of the first layer and the second layer are each 100 nm, and the layers are alternately stacked, and the total thickness of the hafnium-containing silicon layer is 1.5 μm.

  In Table 2, “Note” in the section “Thickness of the first layer” in Example 12 is a layer containing the first compound described in Table 2 having a thickness of 3 nm including the first compound described in Table 1. It shows that the thickness of is 2 nm. The first compound and the second compound shown in Table 2 were all crystalline.

  Here, in each of Examples 12, 13, 14, 18, 24, and 25, the stacked structure of each hafnium-containing silicon layer is the second layer containing the second compound (the first layer containing the first compound as the lowermost layer). Each layer was alternately laminated with the thickness described in Table 2 so that the layer containing the first compound described in Table 2 only in Example 12 was the uppermost layer. In Examples 15 to 17, each layer was listed in Table 2 in the same manner as described above, with the second layer containing the second compound being the bottom layer and the first layer containing the first compound being the top layer. It laminated | stacked alternately by thickness.

<Cutting test>
For the surface-coated cutting tool of the present invention manufactured in Examples 1 to 25 and the surface-coated cutting tool manufactured in Comparative Examples 1 to 6, a continuous turning test was carried out for 10 minutes under the following cutting conditions to obtain a flank surface. The amount of wear and the amount of crater wear 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 3 below.

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

  As is apparent from Table 3, 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.

  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 (8)

A surface-coated cutting tool comprising a substrate and a coating formed on the substrate,
The coating comprises one or more layers;
At least one of the layers has the chemical formula Si _1-X Hf _X Z _Y (where X and Y each represent an atomic composition ratio, 0 <X ≦ 0.4, 0.8 ≦ Y ≦ 1 Z is a hafnium-containing silicon layer containing an amorphous first compound represented by the following: Z represents at least one element selected from the group consisting of boron, oxygen, carbon, and nitrogen. A surface-coated cutting tool characterized by that.   The surface-coated cutting tool according to claim 1, wherein the hafnium-containing silicon layer has a thickness of 0.1 μm to 10 μm. The hafnium-containing silicon layer is formed by laminating one or more layers each including a first layer containing the first compound and a second layer containing a second compound,
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 selected from the group consisting of boron, oxygen, carbon, and nitrogen. The surface-coated cutting tool according to claim 1 or 2, comprising one kind of element. The first layer has a thickness of 0.5 nm or more and 200 nm or less,
The surface-coated cutting tool according to claim 3, wherein the second layer has a thickness of 0.5 nm to 200 nm. The coating includes one or more hard layers in addition to the hafnium-containing silicon layer,
The hard layer includes at least one element selected from the group consisting of group IVa element, group Va element, group VIa element, Al, and Si in the periodic table, or at least one of the elements, boron, oxygen 5. The surface-coated cutting tool according to claim 1, comprising a compound comprising at least one element selected from the group consisting of carbon, nitrogen, and nitrogen.   The hard layer is at least one element selected from the group consisting of Cr, Al, Ti, and Si, or at least one selected from the group consisting of boron, oxygen, carbon, and nitrogen. The surface-coated cutting tool according to claim 5, comprising a compound composed of one kind of element.   The hard layer is at least one element selected from the group consisting of Cr, Al, Ti, and Si, or at least one selected from the group consisting of boron, oxygen, carbon, and nitrogen. The two or more types of layers containing the compound which consists of one type of element are what was laminated | stacked periodically repeating the thickness of each layer as 1 nm or more and 100 nm or less, The Claim 5 or 6 characterized by the above-mentioned. Surface coated cutting tool.   The base material is any one of cemented carbide, cermet, cubic boron nitride sintered body, high-speed steel, ceramics, or diamond sintered body. The surface-coated cutting tool described.