JP5483071B2 - Surface coated cutting tool - Google Patents

Description

  The present invention relates to a surface-coated cutting tool including a substrate and a coating film formed thereon.

  Recent cutting tool trends include the need for dry machining without cutting fluids from the viewpoint of global environmental conservation, the diversification of work materials, and higher cutting speeds to further improve machining efficiency. For example, the tool edge temperature tends to be higher, and the characteristics required for the tool material are becoming stricter. In particular, as a required characteristic of tool materials, the coating film formed on the base material has high temperature stability (oxidation resistance and coating film adhesion) as well as wear resistance related to the cutting tool life. Improvement in lubrication and lubrication characteristics of coating films that replace lubricants are becoming more important.

To improve wear resistance and surface protection function, a single layer of TiAlN is used as a hard coating on the surface of cutting tools and wear-resistant tools made of hard base materials such as WC-base cemented carbide, cermet, and high-speed steel. Alternatively, it is well known to form a multilayer. As a method for improving the heat resistance and hardness of a coating film made of TiAl nitride and improving wear resistance, a coating film made of TiAlSi nitride obtained by adding Si to TiAl nitride is known. It has been. For example, in Patent Document 1, (Al _x Ti _1-xy Si _y ) (N _z C _1-z ) (where x is 0.05 ≦ x ≦ 0.75, and y is 0.01 ≦ y) A hard film having a chemical composition represented by ≦ 0.1, where z is 0.6 ≦ z ≦ 1) has been proposed.

  However, in recent high-speed and dry processing, a sufficient tool life cannot be obtained with a coating film made of TiAlN or TiAlSiN.

  Under such circumstances, as a method of suppressing the temperature rise of the hard coating film during high-speed cutting and realizing a long tool life, a method of further forming a solid lubricating coating film on the hard coating film made of TiAlN Has been proposed.

  For example, in Patent Document 2, a part or all of a blade including a cutting edge portion of a surface-coated cutting tool using a high-speed steel and a cemented carbide as a base material is made of TiAlN having a film thickness of 0.5 μm to 10.0 μm. There has been proposed a surface-coated cutting tool in which a hard coating film is formed and a solid lubricating coating film made of MoN having a thickness of 0.05 μm to 2.0 μm is further coated on the hard coating film.

JP 07-310174 A JP 2001-179533 A

  The surface-coated cutting tool of Patent Document 2 described above is based on the effect of MoN contained in the solid lubricating coating film formed on the hard coating film, for example, under conditions of low-speed cutting such as a cutting speed of 20 m / min or less. Wear due to welding with the work material can be suppressed, and the tool life can be improved. However, under the conditions of high-speed cutting where the cutting speed exceeds 20 m / min, the solid lubricating coating film made of MoN is worn and lost at an early stage, so that it has the effect of preventing wear due to welding with the work material. There was a problem that the tool life could not be improved as a result.

  The present invention has been made in view of the above situation, and the object of the present invention is to provide a coating film that has both the characteristics of MoN and the characteristics of TiAlSiN, and is particularly excellent in wear resistance. It is to provide a surface-coated cutting tool.

The surface-coated cutting tool of the present invention comprises a substrate and a coating film formed thereon, and the coating film is MoN _z (wherein z is 0.01 ≦ z ≦ 0.2). A solid layer of Mo and N, an A layer made of Mo ₂ N, MoN or a mixture thereof, and Ti _1-xy Al _x Si _y N (where x is 0.3 ≦ x ≦ 0.7 In the formula, y is formed by alternately laminating two or more B layers each having 0.01 ≦ y ≦ 0.25), and the layer thickness λa of the A layer and the layer thickness λb of the B layer are: The layer thickness ratio λa / λb increases from the substrate side to the outermost surface side of the coating film, and the layer thickness ratio λa / λb between the A layer and the B layer closest to the substrate. Is 0.1 or more and 0.7 or less, and the layer thickness ratio λa / λb of the A layer and the B layer closest to the outermost surface side is 1.5 or more and 10 or less.

  Here, the surface-coated cutting tool of the present invention further includes an intermediate layer between the substrate and the coating film, and the intermediate layer has a layer thickness of 0.1 μm to 1 μm, and It is preferably composed of at least one selected from the group consisting of TiN, CrN, Ti, and Cr.

  Moreover, it is preferable that the said coating film has the whole film thickness of 0.5 micrometer or more and 20 micrometers or less, and it is preferable to form by a physical vapor deposition method.

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

  Since the surface-coated cutting tool of the present invention has the above-described configuration, it has both the characteristics of MoN and the characteristics of TiAlSiN, and is particularly excellent in wear resistance.

It is a schematic sectional drawing which shows the coating film of the aspect by which B layer was formed immediately on the base material, and A layer was formed in the outermost surface layer. It is a schematic sectional drawing which shows the coating film of the aspect by which A layer was formed immediately on the base material, and B layer was formed in the outermost surface layer. It is a schematic sectional drawing which shows the coating film of the aspect by which B layer was formed immediately on the base material, and B layer was formed also in the outermost surface layer. It is a schematic sectional drawing which shows the coating film of the aspect by which A layer was formed directly on the base material and A layer was formed also in the outermost surface layer. 6 is a graph conceptually showing that the layer thickness ratio λa / λb continuously increases. 6 is a graph conceptually showing that the layer thickness ratio λa / λb increases stepwise. It is the schematic of an arc ion plating apparatus.

  Hereinafter, the present invention will be described in detail. In the following description of the embodiments, the description is made with reference to the drawings. In the drawings of the present application, the same reference numerals denote the same or corresponding parts. In the present invention, the layer thickness or film thickness is measured by a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and the composition is measured by an energy dispersive X-ray analyzer (EDS). To do.

<Surface coated cutting tool>
The surface-coated cutting tool of the present invention comprises a substrate and a coating film formed thereon. The surface-coated cutting tool of the present invention having such a basic configuration is, for example, a drill, an end mill, a milling or turning cutting edge replacement type cutting tip, a metal saw, a gear cutting tool, a reamer, a tap, or a crankshaft pin. It can be used very effectively as a chip for milling.

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

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

<Coating film>
The coating film of the present invention has a solid solution of Mo and N represented by MoN _z (wherein z is 0.01 ≦ z ≦ 0.2), Mo ₂ N, MoN, or a mixture thereof. And B layers composed of Ti _1-xy Al _x Si _y N (where x is 0.3 ≦ x ≦ 0.7 and y is 0.01 ≦ y ≦ 0.25) alternately Two or more layers are laminated, and the layer thickness λa of the A layer and the layer thickness λb of the B layer are 2 nm or more and 1000 nm or less, respectively, and the layer thickness ratio λa / λb is coated from the substrate side. The layer thickness ratio λa / λb of the A layer and B layer closest to the substrate increases from 0.1 to 0.7 and increases toward the outermost surface side of the film, and is closest to the outermost surface side. The layer thickness ratio λa / λb is 1.5 or more and 10 or less.

  Such a coating film of the present invention includes an aspect in which the entire surface of the substrate is coated, and also includes an aspect in which the coating film is not partially formed. The aspect which the lamination | stacking aspect of a part differs is also included. Moreover, it is preferable that the coating film of this invention is 0.5 micrometer or more and 20 micrometers or less of the whole film thickness. If the thickness is less than 0.5 μm, the wear resistance may be inferior, and if it exceeds 20 μm, the coating film may not withstand the compressive stress remaining in the coating film, and the coating film may self-destruct. A particularly preferable film thickness of such a coating film is 2 μm or more and 15 μm or less.

Hereinafter, such a coating film will be described in more detail.
<A layer>
The A layer constituting the coating film is a solid solution of Mo and N represented by MoN _z (wherein z is 0.01 ≦ z ≦ 0.2), Mo ₂ N, MoN or a mixture thereof. It is characterized by being. Since such A layer is excellent in lubricity and welding resistance, it is effective in improving the work quality of the work material and reducing the cutting edge temperature during high speed and dry processing. In the above, the solid solution of Mo and N represented by MoN _z (wherein z is 0.01 ≦ z ≦ 0.2) may be either a substitutional solid solution or an interstitial solid solution. Mo ₂ N and MoN are crystals composed of Mo and N, respectively, and the ratio of Mo to N is not limited to 2: 1 and 1: 1, but the atomic ratio of these elements is not limited. The ratio may be slightly deviated from the above, or may further include an impurity element such as oxygen, and includes all conventionally known atomic ratios, and the atomic ratio between them is not particularly limited.

<B layer>
The B layer constituting the coating film together with the A layer is Ti _1-xy Al _x Si _y N (wherein x is 0.3 ≦ x ≦ 0.7 and y is 0.01 ≦ y ≦ 0.25). Such a B layer is excellent in the balance between wear resistance and toughness, but in order to cope with higher speed and dry processing, there is a limit in itself, so in the present invention, it is laminated with the above A layer. It is. Here, x is more preferably 0.4 ≦ x ≦ 0.65. In this case, the balance of wear resistance, oxidation resistance and toughness is further improved. In the above formula, when x is less than 0.3, the wear resistance is remarkably lowered, and even when x exceeds 0.7, the wear resistance is remarkably lowered.

  The y is more preferably 0.02 ≦ y ≦ 0.15. In this case, the balance of wear resistance, toughness, and compressive residual stress is good. In the above formula, if y is less than 0.01, the effect of improving the oxidation resistance and hardness due to Si addition cannot be sufficiently obtained. If y exceeds 0.25, the hardness of the coating film is It is not preferable because the coating film is easily peeled off by the tool blade edge due to a significant decrease in wear resistance and an increase in the compressive residual stress of the coating film.

In the notation of Ti _1-xy Al _x Si _y N, the ratio of “Ti _1-x Al _x Si _y ” to “N” is not limited to 1: 1 but can be a composition ratio. All the ratios can be included, and the ratio between the two is not particularly limited.

<Laminated structure of coating film>
The coating film of the present invention is based on the fact that two or more layers of the A layer and the B layer are alternately laminated. This was expected to enjoy the respective characteristics of both layers by alternately laminating the A layer with excellent lubricity and welding resistance and the B layer with excellent wear resistance and toughness. Is. However, by simply laminating these two layers with a uniform layer thickness, the properties of both layers cannot be made compatible, and the wear resistance is particularly insufficient.

  Accordingly, as a result of various investigations, the present invention has shown that when the layer thickness of the A layer is λa and the layer thickness of the B layer is λb, the layer thickness ratio λa / λb is coated from the substrate side. In the case of increasing toward the outermost surface side of the film, there is a tendency that the characteristics of the two layers are compatible, and the layer thickness ratio λa / λb between the A layer and the B layer closest to the substrate is 0.1 or more and 0.00. When the layer thickness ratio λa / λb between the A layer and the B layer closest to the outermost surface side is 1.5 or more and 10 or less, the characteristics of both layers are sufficiently exhibited without any loss. And the present invention has been completed. That is, the coating film of the present invention has succeeded in remarkably improving the tool life in high speed and dry processing.

  Thus, by thickening the B layer on the base material side, the balance among wear resistance, oxidation resistance and toughness is particularly excellent. When the layer thickness ratio λa / λb of the A layer and B layer closest to the substrate is less than 0.1, film formation by the physical vapor deposition method described later becomes difficult, and when it exceeds 0.7, the wear resistance decreases. As a result, the toughness decreases and the coating film breaks during cutting. The layer thickness ratio λa / λb between the A layer and the B layer closest to the substrate is more preferably 0.2 or more and 0.5 or less.

  On the other hand, by increasing the thickness of the A layer on the outermost surface side, the cutting edge temperature is lowered due to the lubrication effect and the work quality of the work material is improved. If the layer thickness ratio λa / λb of the A layer and B layer closest to the outermost surface side is less than 1.5, the effect of improving the lubrication effect and welding resistance by the A layer cannot be exhibited. As a result, the properties and toughness are reduced. The layer thickness ratio λa / λb of the A layer and B layer closest to the outermost surface side is more preferably 2 or more and 5 or less.

  Here, the layer thickness λa of the A layer and the layer thickness λb of the B layer are each 2 nm to 1000 nm, more preferably 5 nm to 100 nm. When these layer thicknesses are less than 2 nm, the number of rotations of the rotary table on which the substrate of the film forming apparatus is set becomes very fast as described later, making film formation difficult due to the apparatus specifications. Since it is too thick, the effect of combining the A layer and the B layer is reduced.

  Further, “A layer and B layer closest to the base material” means that the B layer 103 is in contact with the base material 101 as shown in FIGS. 1 and 3 (if an intermediate layer described later is formed, The layer A 102 may be in contact with the substrate 101 as shown in FIGS. The “A layer and B layer closest to the outermost surface side” may be those in which the A layer 102 constitutes the outermost surface as shown in FIG. 1 and FIG. As shown, the B layer 103 may constitute the outermost surface. As described above, the stacking order of the A layer 102 and the B layer 103 is such that either layer may be formed on the substrate 101 and the stacking may be started as long as these layers are alternately stacked. Either layer may be formed as a layer and the lamination may be finished. 1 to 4 indicate that the stacking is repeated, the minimum number of stacks in the stacking mode of the present invention is that the A layer 102 and the B layer 103 are both two layers. This is the case of four layers.

  On the other hand, the aspect of increasing the layer thickness ratio λa / λb from the base material side to the outermost surface side of the coating film increases, for example, as shown in FIG. Alternatively, it may increase “stepwise” as shown in FIG. Further, when formed in a “stepwise” manner, the level difference (that is, the difference between the layer thickness ratios λa / λb) does not have to be constant as shown in FIG. It is important that the layer thickness ratio λa / λb is different as described above.

<Intermediate layer>
The surface-coated cutting tool of the present invention further includes an intermediate layer between the substrate and the coating film, the intermediate layer has a layer thickness of 0.1 μm or more and 1 μm or less, and TiN, CrN, It is preferably composed of at least one selected from the group consisting of Ti and Cr.

  Since such an intermediate layer has good adhesion to both the substrate surface and the coating film, the adhesion between the substrate and the coating film can be improved. Therefore, the cutting tool life can be further improved without the coating film being peeled off from the substrate. If the thickness of such an intermediate layer is less than 0.1 μm, the adhesion strength is not improved, and conversely if it exceeds 1 μm, the adhesion strength is not further improved. A more preferable thickness of such an intermediate layer is not less than 0.2 μm and not more than 0.5 μm.

<Manufacturing method>
The coating film of the present invention is preferably formed by physical vapor deposition (PVD method). In order to form the coating film of the present invention on the substrate surface, it is indispensable to be a film forming process capable of forming a compound having high crystallinity, and various film forming methods were examined. As a result, it has been found that it is optimal to use physical vapor deposition. Physical vapor deposition methods include, for example, sputtering method, ion plating method, etc. However, when using cathode arc ion plating method or sputtering method, in which the ion ratio of the raw material elements is particularly high, the base layer is formed before the coating film is formed. Since the metal or gas ion bombardment treatment can be performed on the material surface, the adhesion between the coating film and the substrate is remarkably improved, which is preferable.

  Therefore, the coating film of the present invention is preferably formed as follows. First, the case where the cathode arc ion plating method which is a kind of physical vapor deposition method is adopted will be described. FIG. 7 is a schematic diagram of an arc ion plating apparatus 200 used in the cathode arc ion plating method. In the opposing evaporation sources 201 and 202, a Mo target for the A layer is set in the evaporation source 201, and a TiAlSi target for the B layer is set in the evaporation source 202. Further, the base 210 (cutting tool) is set on the rotary table 204.

When a Mo target is set in the evaporation source 201, the composition of the A layer is changed to MoN _z (where z is 0.01 ≦ z ≦) by adjusting the amount of nitrogen gas introduced into the apparatus during film formation. 0.2) and can be adjusted to any composition of a solid solution of Mo and N, Mo ₂ N, MoN, or a mixture thereof. That is, in accordance with increasing the introduction amount of nitrogen gas, MoN _z, mixture of MoN _z and Mo ₂ N, Mo ₂ N, mixture of Mo ₂ N and MoN, in the order of MoN, to the atomic ratio of Mo The composition of the A layer can be adjusted as appropriate so that the atomic ratio of N is high.

  Then, after evacuating the inside of the apparatus to a vacuum and performing sputter cleaning (bombarding) with Ar gas, the rotary table 204 is rotated at 3 rpm, and the evaporation sources 201 and 202 are arced to ionize each target. At the same time, nitrogen, which is a reactive gas, is introduced from the gas inlet 205, and each nitride (that is, the A layer and the B layer) is formed on the surface of the substrate 210.

That is, when the substrate 210 passes in front of the evaporation source 201, a solid solution of Mo and N represented by MoN _z (where z is 0.01 ≦ z ≦ 0.2), Mo ₂ N, MoN Alternatively, an A layer made of a mixture of these is laminated, and a B layer made of Ti _1-xy Al _x Si _y N is formed when the substrate 210 passes in front of the evaporation source 202, and thus the turntable As layer 204 rotates, the A layer and the B layer can be alternately stacked. Note that the composition of the layer A may be different for each layer in the stack.

Here, x and y of Ti _1-xy Al _x Si _y N constituting the B layer can be determined by the composition of the target set in the evaporation source 202 (ratio of Ti, Al, and Si). Immediately after the start of film formation, the arc current value of the evaporation source 201 is made smaller than the arc current value of the evaporation source 202, for example, the arc current of the evaporation source 201 is set to 70A and the arc current of the evaporation source 202 is set to 150A. Accordingly, the layer thickness ratio λa / λb of the A layer and the B layer on the substrate side can be made smaller than that on the outermost surface side. That is, the layer thickness ratio λa / λb between the A layer and the B layer closest to the substrate can be set to satisfy the relationship of 0.1 or more and 0.7 or less.

  On the other hand, during film formation, by increasing the arc current value of the evaporation source 201 continuously or stepwise and decreasing the arc current value of the evaporation source 202, the layer thickness ratio λa / λb is controlled from the substrate side. It can be increased toward the outermost surface side of the covering film. In this case, if the change in current value is continuous, the layer thickness ratio λa / λb increases continuously as shown in FIG. 5, and if the change in current value is made stepwise, it is shown in FIG. Thus, the layer thickness ratio λa / λb increases stepwise.

  Then, the arc current value of the evaporation source 201 is made larger than the arc current value of the evaporation source 202 so that the arc current of the evaporation source 201 immediately before the film formation is 150 A and the arc current of the evaporation source 202 is 70 A. Thus, the layer thickness ratio λa / λb between the A layer and the B layer closest to the outermost surface side can be set to satisfy the relationship of 1.5 or more and 10 or less.

  In addition, the aspect of change of the layer thickness ratio λa / λb can be changed variously by changing the aspect of change of the current value. For example, when either one of the current values is made constant and only the other current value is changed, only the layer thickness of either the A layer or the B layer may be relatively changed. it can. Also, instead of reducing the arc current value of the evaporation source 202, the thickness of the B layer is increased toward the outermost surface side of the coating film by increasing it with an increase width that is smaller than the increase width of the evaporation source 201. Thus, the layer thickness ratio λa / λb can be increased.

  As described above, the layer thickness of each layer can be controlled by the rotation number of the turntable 204 and the arc current value. If the thickness of each of the A layer and the B layer is less than 2 nm, the number of rotations of the turntable becomes very fast, and film formation becomes difficult due to device specifications. Moreover, when each layer thickness exceeds 1000 nm, since the effect of combining A layer and B layer reduces because the layer thickness is too thick, it is not preferable.

  In addition, the arc ion plating apparatus 200 can have the evaporation source 203, and when forming an intermediate layer, a target for the intermediate layer can be set. Further, the apparatus is provided with a plurality of heaters 206.

  On the other hand, when the sputtering method is employed as the method for forming the coating film of the present invention, the method is as follows. When the sputtering method is used, the control range of the layer thickness ratio λa / λb can be widened, and the surface roughness of the coating film can be improved to improve the work quality of the work material.

  First, as an apparatus in the case of employing the sputtering method, in the arc ion plating apparatus of FIG. 7, a sputtering apparatus using a sputtering evaporation source instead of the arc evaporation source may be used as the evaporation sources 201 and 202. Then, by changing the power value (pulse DC sputtering power) to be supplied to the evaporation sources 201 and 202 (sputter evaporation source) in the same manner as the arc current value in the case of the arc ion plating method, the layer thickness ratio λa The value of / λb can be changed.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

  Using an arc ion plating apparatus and a sputtering apparatus as shown in FIG. 7, a target for forming each layer is set in an evaporation source, and a coating film (and an intermediate layer are formed on the substrate at a substrate temperature of 450 ° C. Formed an intermediate layer between the substrate and the coating film.

  There are three types of base materials: cemented carbide end mills (φ10mm, 6 blades), cemented carbide drills (φ8mm), and P20 equivalent cemented carbide turning edge cutting type cutting tips (shape: CNMG120408N). The coating films of Examples 1 to 23 and Comparative Examples 1 to 8 shown in Table 1 were prepared.

In Table 1, “IP” in the column of “Film formation method” indicates that the film was formed by the cathode arc ion plating method (film formation apparatus: arc ion plating apparatus), and “SP” represents the sputtering method (film formation). (Apparatus: Sputtering apparatus) shows that the film was formed. A blank in the “intermediate layer” column indicates that no intermediate layer is formed, and other layers are those in which the intermediate layer having the composition described in the “composition” column is indicated in the “layer thickness” column. It shows that it is formed with thickness. The coating film is formed by laminating “A layer” and “B layer” described in the “Composition” column. For example, “Mo ₂ N + MoN” shown in the A layer column of the composition of Example 7 is: It means that the composition of the A layer is a mixture of Mo ₂ N and MoN, and MoN _z (wherein z is 0), such as “MoN _0.01 ” shown in the column of the A layer of the composition of Example 14. .01 ≦ z ≦ 0.2) means a solid solution of Mo and N. Further, in the columns “base material side” and “outermost surface side”, the layer thickness (λa) of the base material side and the outermost surface side, the layer thickness (λb) of the B layer, and the layer thickness ratio λa / λb are set. Indicated. The layer thickness ratio λa / λb increases from the base material side to the outermost surface side of the coating film. Also, the column “Mode of change in layer thickness ratio” indicates whether the mode of change in the layer thickness ratio λa / λb of the coating film is “continuous” or “stepwise”. The column “total film thickness” indicates the film thickness of the coating film.

For example, Example 1 uses the arc ion plating apparatus of FIG. 7 to form a coating film using Mo and Ti _0.45 Al _0.45 Si _0.1 as target materials of the evaporation source 201 and the evaporation source 202, respectively, The present invention relates to a surface-coated cutting tool in which an intermediate layer is formed using Ti as a target material of an evaporation source 203 for a layer.

  First, Ar gas was introduced, the pressure in the chamber was maintained at 3.0 Pa, the DC bias voltage was gradually increased to −1000 V, and the substrate surface was cleaned (bombarded) for 15 minutes. Thereafter, the argon gas was exhausted. As a result, Ar ions sputter-cleaned the substrate surface, and strong dirt and oxide films were removed.

Next, TiN was deposited as an intermediate layer. N ₂ gas was introduced so that the pressure in the chamber was 3 Pa, and the substrate DC bias voltage was set to −50V. The Ti target was ionized with an arc current of 150 A and reacted with N ₂ gas to form an intermediate layer made of TiN directly on the substrate.

Next, an A layer and a B layer were formed (that is, a coating film was formed). N ₂ gas was introduced so that the pressure in the chamber was 3 Pa, and the substrate DC bias voltage was set to −50V. The Mo target is ionized with an arc current of 80 A and a Ti _0.45 Al _0.45 Si _0.1 target with an arc current of 200 A and reacted with N ₂ gas to react with N ₂ gas on the intermediate layer of TiN and from the A layer of MoN and Ti _0.45 Al _0.45 Si _0.1 N. The B layer was formed so that the layer thickness ratio λa / λb was 0.40.

Thereafter, the arc current is continuously changed, and immediately before the film formation is completed, the Mo target is set to an arc current of 180 A, the Ti _0.45 Al _0.45 Si _0.1 target is set to an arc current of 60 A, and the layer thickness ratio λa / λb on the outermost surface side is 3.00. The surface-coated cutting tool of the present invention was manufactured by forming a film so that The number of layers of the A layer and the B layer was 346 layers.

On the other hand, in Example 2, an unbalanced magnetron sputtering apparatus (that is, sputtering method) was used, and a coating film was formed using Mo and Ti _0.45 Al _0.45 Si _0.1 as target materials of the evaporation source 201 and the evaporation source 202, respectively. In addition, the present invention relates to a surface-coated cutting tool in which an intermediate layer is formed using Cr as a target material of the evaporation source 203 for the intermediate layer.

  First, Ar gas was introduced, the pressure in the chamber was maintained at 3.0 Pa, the DC bias voltage was gradually increased to −1000 V, and the substrate surface was cleaned (bombarded) for 15 minutes. Thereafter, the argon gas was exhausted.

Next, CrN was deposited as an intermediate layer. Ar gas and N ₂ gas were introduced at a flow rate ratio of 1: 1 so that the pressure in the chamber was 0.6 Pa, and the base pulse DC bias voltage was −90V. The Cr target was ionized with a pulse DC sputtering power of 2000 W and reacted with N ₂ gas to form an intermediate layer made of CrN directly on the substrate.

Next, an A layer and a B layer were formed. Ar gas and N ₂ gas were introduced at a flow rate ratio of 1: 1 so that the pressure in the chamber was 0.6 Pa, and the base pulse DC bias voltage was −90V. The Mo target is ionized with a pulse DC sputter power of 600 W and the Ti _0.45 Al _0.45 Si _0.1 target is pulsed with DC sputter power of 2000 W, reacted with N ₂ gas, and an A layer made of Mo ₂ N and Ti on an intermediate layer made of CrN. _A B layer made of _0.45 Al _0.45 Si _0.1 N was formed so that the layer thickness ratio λa / λb was 0.30.

Thereafter, the pulse DC sputtering power is changed stepwise, and immediately before the film formation is finished, the Mo target is set to pulse DC sputtering power 3200 W, the Ti _0.45 Al _0.45 Si _0.1 target is set to pulse DC sputtering power 800 W, and the layer thickness ratio λa on the outermost surface side is set. The surface-coated cutting tool of the present invention was manufactured by forming a film so that / λb was 4.00. The number of layers of the A layer and the B layer was 303 layers.

  The surface-coated cutting tools of other examples and comparative examples were produced in the same manner. The surface-coated cutting tool thus obtained (namely, a surface-coated end mill, a surface-coated drill, and a surface-coated turning edge cutting-type cutting tip) was evaluated under the following cutting conditions. The results of the cutting evaluation are shown in Table 2.

(1) End mill evaluation It performed using the surface coating end mill. That is, the end mill cutting conditions were as follows: a cemented carbide end mill with 6 blades and an outer diameter of 10 mm was used as the base material, the work material was SKD11 (HRC61), the side cutting was downcut, and the cutting speed was 200 m / min. The feed amount was 0.025 mm / blade, the incision amount a _p = 10 mm, a _e = 0.6 mm, and air blow. The wear width of the outer periphery of the cutting edge at the cutting length of 50 m was measured. The smaller the wear width, the better the wear resistance.

(2) Drill evaluation A surface-coated drill was used. That is, the drill cutting conditions are as follows. A hard metal drill having an outer diameter of 8 mm is used as the base material, the work material is S50C, the drilling speed is 80 m / min, the feed rate is 0.25 mm / rev, This was performed without a through hole having a hole depth of 30 mm and without cutting oil. The wear width of the tip margin at the cutting length of 30 m was measured. The smaller the wear width, the better the wear resistance.

(3) Turning tip evaluation It was performed using a blade-tip-exchangeable cutting tip for surface coating turning. The turning conditions were as described above, using a P20-equivalent cemented carbide cutting edge-changing cutting tip (shape: CNMG120408N) as the base material, the work material being SCM435 (diameter 350 mm), cutting speed = 300 m / min, feed Amount = 0.25 mm / rev, depth of cut = 1.5 mm, water-soluble cutting oil. The wear width of the flank at a cutting time of 15 minutes was measured. The smaller the wear width, the better the wear resistance.

  From Table 2, it was found that the surface-coated cutting tool of the example has a significantly improved tool life as compared with the surface-coated cutting tool of the comparative example, and can sufficiently cope with high speed and dry processing. That is, it was confirmed that the surface-coated cutting tool of the present invention has both the characteristics of MoN and the characteristics of TiAlSiN, and is particularly excellent in wear resistance.

  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.

  101, 210 base material, 102 A layer, 103 B layer, 200 arc ion plating apparatus, 201, 202, 203 evaporation source, 204 rotary table, 205 gas inlet, 206 heater.

Claims (4)

A base material , a coating film formed thereon, and an intermediate layer formed between the base material and the coating film ,
The coating film includes a solid solution of Mo and N represented by MoN _z (wherein z is 0.01 ≦ z ≦ 0.2), an A layer made of Mo ₂ N, MoN, or a mixture thereof. ,
Two layers each of which alternately comprise B layers made of Ti _1-xy Al _x Si _y N (where x is 0.3 ≦ x ≦ 0.7 and y is 0.01 ≦ y ≦ 0.25) More than
The layer thickness λa of the A layer and the layer thickness λb of the B layer are 2 nm or more and 1000 nm or less, respectively.
The layer thickness ratio λa / λb increases from the substrate side to the outermost surface side of the coating film, and the layer thickness ratio λa / λb of the A layer and B layer closest to the substrate is 0.1 or more and 0.7 or less, the layer thickness ratio [lambda] a / [lambda] b of the closest a layer and the B layer on the outermost surface side Ri der 1.5 to 10,
The surface-coated cutting tool , wherein the intermediate layer has a layer thickness of 0.1 μm or more and 1 μm or less and is composed of at least one selected from the group consisting of TiN, CrN, Ti, and Cr . The surface-coated cutting tool according to claim 1, wherein the coating film has a total film thickness of 0.5 μm or more and 20 μm or less. The coating film is formed by physical vapor deposition, surface-coated cutting tool according to claim 1 or 2. The substrate is cemented carbide, cermet, high-speed steel, ceramics, cubic boron nitride sintered body or formed by any of the diamond sintered body, according to any one of claims 1 to 3 Surface coated cutting tool.

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