JP2009190091A - Cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool, having high abrasion resistance and lubrication performance, and excellent chipping resistance. <P>SOLUTION: The cutting tool 1 comprises a base member 2, and a coating layer 6 coating the surface of the base member 2. The coating layer 6 comprises: a first layer 7 that comprises Ti<SB>1-a-b-c-d</SB>Al<SB>a</SB>W<SB>b</SB>Si<SB>c</SB>M<SB>d</SB>(C<SB>1-x</SB>N<SB>x</SB>) (M is at least one kind selected among Nb, Mo, Ta, Hf and Y, 0.45≤a≤0.55, 0.01≤b≤0.1, 0≤c≤0.05, 0.01≤d≤0.1, 0≤x≤1); and a second layer 8 that comprises (Al<SB>1-h</SB>M'<SB>h</SB>)<SB>v</SB>O<SB>w</SB>(M' is more than one kind selected among Ti, Cr, Zr, Nb, Mo, Ta, Hf, and Y, 0≤h≤0.65, 1≤w/v≤2.5). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cutting tool having a coating layer formed on the surface of a substrate.

  At present, for members that require wear resistance, slidability, and fracture resistance, such as cutting tools, wear-resistant members, and sliding members, sintered alloys such as cemented carbide and cermet, diamond, and cBN (cubic boron nitride) A method of improving the wear resistance, slidability, and fracture resistance by forming a coating layer on the surface of a high hardness sintered body and a substrate made of a ceramic such as alumina or silicon nitride is used.

  Further, it is preferable to form a nitride layer mainly composed of Ti or Al by using an arc ion plating method or a sputtering method as the physical vapor deposition method, and further to extend the tool life. Improvement of the nitride layer is under study. For example, Patent Document 1 discloses a hard coating having a (TiWSi) N composition, and describes that adhesion between a substrate such as a cemented carbide and a coating layer is increased.

In addition, in such physical vapor deposition, recently, a coating layer having a laminated structure of a nitride layer and an oxide layer by sequentially introducing a plurality of gases such as nitrogen gas and oxygen gas into the chamber has been attempted (for example, (See Patent Documents 2 to 4).
JP 2006-111915 A JP 2003-127006 A JP 2006-28600 A JP 2005-125411 A

  However, the (TiWSi) N coating layer of Patent Document 1 has insufficient wear resistance, and a longer life of the cutting tool has been demanded.

  In addition, even with a coating layer made of a laminate of a nitride layer and an oxide layer described in Patent Documents 2 to 4, it cannot be said that the wear resistance and fracture resistance of the entire coating layer are necessarily sufficient, and further improvements Was requested.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a cutting tool provided with a coating layer that improves wear resistance, oxidation resistance and chipping resistance.

The cutting tool of the present invention is a cutting tool comprising a substrate and a coating layer covering the surface of the substrate,
The coating layer is
_{Ti 1-a-b-c} -d Al a W b Si c M d (C 1-x N x) ( where M is at least one Nb, Mo, Ta, selected from Hf and Y, 0.45 ≦ a ≦ 0.55, 0.01 ≦ b ≦ 0.1, 0 ≦ c ≦ 0.05, 0.01 ≦ d ≦ 0.1, 0 ≦ x ≦ 1),
(Al _1-h M ′ _h ) _v O _w (where M ′ is one or more selected from Ti, Cr, Zr, Nb, Mo, Ta, Hf and Y, 0 ≦ h ≦ 0.65, 1 ≦ and w / v ≦ 2.5).

  Here, in the above configuration, it is preferable that the first layer has a thickness of 1 to 7 μm, and the second layer has a thickness of 0.5 to 5 μm. At this time, the average crystal width of the first layer is preferably 0.01 to 0.5 μm, and the average crystal width of the second layer is preferably 0.6 to 3 μm.

  In the above configuration, it is desirable that dispersed particles having an average crystal grain size of 0.05 to 1 μm are scattered in the first layer.

  On the other hand, in the above configuration, it is desirable that the coating layer is formed by alternately laminating two or more layers of the first layer and the second layer. At this time, the thickness of each layer of the first layer is 0.02 to 0.7 μm, the thickness of each layer of the second layer is 0.01 to 0.5 μm, and the total thickness of the first layer is The total thickness of the second layer is preferably 0.5 to 5 μm.

Used as the first layer on the cutting tool of the present invention _{Ti 1-a-b-c} -d Al a W b Si c M d (C 1-x N x) ( however, M is Nb, Mo, Ta, Hf , Y selected from 0.45 ≦ a ≦ 0.55, 0.01 ≦ b ≦ 0.1, 0 ≦ c ≦ 0.05, 0.01 ≦ d ≦ 0.1, 0 ≦ x ≦ 1), the first layer has high hardness and low internal stress. On the other hand, the second layer is excellent in oxidation resistance and welding resistance and has good adhesion to the first layer. Therefore, the coating layer used in the cutting tool of the present invention is excellent in wear resistance, welding resistance, and fracture resistance.

  Further, the film thickness of the first layer is 1 to 7 μm, and the film thickness of the second layer is 0.5 to 5 μm, which suppresses peeling between the first layer and the second layer with respect to the substrate, and is resistant to acid. Desirable in terms of excellent chemical properties. At this time, the average crystal width of the first layer is 0.01 to 0.5 μm, and the average crystal width of the second layer is 0.6 to 3 μm, which increases the hardness of the coating layer and the surface of the coating layer. It is desirable in terms of improving the welding resistance.

  Further, it is desirable that dispersed particles having an average crystal grain size of 0.05 to 1 μm are scattered in the first layer in terms of enhancing the toughness of the coating layer and increasing the fracture resistance of the coating layer.

  On the other hand, the said structure WHEREIN: The structure by which the said 1st layer and the said 2nd layer are laminated | stacked alternately alternately may be sufficient as the said coating layer. According to this configuration, the hardness of the coating layer can be improved. At this time, the thickness of each layer of the first layer is 0.02 to 0.7 μm, the thickness of each layer of the second layer is 0.01 to 0.5 μm, and the total thickness of the first layer is 1 From the viewpoint of improving the hardness and oxidation resistance of the coating layer, it is preferable that the total film thickness of the second layer is 0.5 to 5 μm.

  FIG. 1 is a schematic perspective view of a cutting tool which is a preferred embodiment example, FIG. 2 is a schematic cross-sectional view of the first embodiment of the present invention, and the first embodiment of the present invention. 2 will be described with reference to FIG. 3, which is a schematic sectional view of the second embodiment.

  1 to 3, a cutting tool (hereinafter simply abbreviated as a tool) 1 according to the present invention includes a rake face 3 as a main surface, a flank face 4 as a side face, and an intersection of the rake face 3 and the flank face 4. The cutting edge 5 is provided on the ridge line, and the coating layers 6 and 9 are formed on the surface of the substrate 2.

Coating layer 6 or 9 _{is, Ti 1-a-b-} c-d Al a W b Si c M d (C 1-x N x) ( however, M is selected from Nb, Mo, Ta, Hf, and Y At least one kind, 0.45 ≦ a ≦ 0.55, 0.01 ≦ b ≦ 0.1, 0 ≦ c ≦ 0.05, 0.01 ≦ d ≦ 0.1, 0 ≦ x ≦ 1) The first layer 7 and (Al _1-h M ′ _h ) _v O _w (where M ′ is one or more selected from Ti, Cr, Zr, Nb, Mo, Ta, Hf and Y, 0 ≦ h ≦ 0.65, 1 ≦ w / v ≦ 2.5). With this configuration, the first layer 7 has a high oxidation start temperature, high oxidation resistance, and can reduce internal stress, and has high fracture resistance. In addition, since the second layer 8 is further excellent in welding resistance and oxidation resistance, and has high adhesion to the first layer 7, the covering layers 6 and 9 are resistant to oxidation, welding, and defects. Excellent in properties.

  That is, if a (Al composition ratio) is less than 0.45, the oxidation resistance of the coating layers 6 and 9 is lowered. If a (Al composition ratio) is more than 0.55, the coating layers 6 and 9 are reduced. The crystal structure tends to change from cubic to hexagonal and the hardness decreases. A particularly desirable range of a is 0.48 ≦ a ≦ 0.52. On the other hand, when b (W composition ratio) is less than 0.01, the internal stress of the coating layers 6 and 9 is high and the fracture resistance is lowered, and the adhesion between the substrate 2 and the coating layers 6 and 9 is lowered. Thus, chipping and peeling of the coating layer 7 are likely to occur during cutting, and if b (W composition ratio) is more than 0.1, the hardness of the coating layers 6 and 9 is lowered. A particularly desirable range of b is 0.01 ≦ b ≦ 0.08. Furthermore, when c (Si composition ratio) is more than 0.05, the hardness of the coating layers 6 and 9 is lowered. A particularly desirable range for c is 0.01 ≦ c ≦ 0.04. Further, when d (M composition ratio) is less than 0.01, the oxidation start temperature becomes low, and when d (M composition ratio) is more than 0.1, a part of the metal M is different from the cubic crystal. As a low hardness phase, the hardness of the coating layers 6 and 9 decreases. A particularly desirable range of d is 0.01 ≦ d ≦ 0.08.

  The metal M is at least one selected from Nb, Mo, Ta, Hf, and Y. Among them, the inclusion of Nb or Mo is desirable because it has the most excellent wear resistance and oxidation resistance.

  Moreover, C and N which are non-metallic components of the coating layers 6 and 9 are excellent in hardness and toughness required for the cutting tool, and suppress droplets (coarse particles) generated on the surfaces of the coating layers 6 and 9. Therefore, a particularly desirable range of x (N composition ratio) is 0.5 ≦ x ≦ 1. Here, according to the present invention, the composition of the coating layers 6 and 9 can be measured by energy dispersive X-ray spectroscopy (EDX) or X-ray photoelectron spectroscopy (XPS).

  Further, since the internal stress of the first layer 7 is not so high, the covering layers 6 and 9 are difficult to chip even when the thickness is increased, and the total thickness of the covering layers 6 and 9 is 1.5 to 12 μm. However, it is possible to prevent peeling and chipping due to the internal stress of the coating layers 6 and 9 themselves, and to maintain sufficient wear resistance. A desirable range of the total film thickness of the coating layers 6 and 9 is 5 to 7.5 μm. The first layer 7 has a thickness of 1 to 7 μm, and the second layer 8 has a thickness of 0.5 to 5 μm, which suppresses the separation of the first layer 7 and the second layer 8 from the substrate 2. And desirable in terms of excellent wear resistance.

  At this time, the average crystal width of the first layer 7 is 0.01 to 0.5 μm, and the average crystal width of the second layer 8 is 0.6 to 3 μm, thereby increasing the hardness of the coating layers 6 and 9. In addition, it is desirable in terms of improving the welding resistance on the surfaces of the coating layers 6 and 9. In the present invention, in order to measure the average crystal width of the coating layers 6 and 9, in the cross-sectional photograph of the coating layers 6 and 9, a line A (not shown) is formed in a portion corresponding to the intermediate thickness of the coating layers 6 and 9. )) To measure. Specifically, the average crystal width of the columnar crystals (not shown) in the coating layers 6 and 9 is specified as a line segment A having a length L (not shown) of 100 nm or more. The number of grain boundaries crossing is counted, and the average crystal width = length L / number of grain boundaries is calculated.

Further, the dispersion of dispersed particles (not shown) having an average crystal grain size of 0.05 to 1 μm in the first layer 7 increases the toughness of the first layer 6 and improves the resistance of the coating layers 6 and 9. It is desirable in terms of increasing deficiency. As the composition of the dispersed particles, specifically, the nitride particles having a high W (tungsten) content relative to the matrix other than the dispersed particles, for example, the total composition of the coating layers 6 and 9 is Ti _{1-ab- c-d Al a W b Si} c M d (C 1-x N x) ( however, M is Nb, Mo, Ta, at least one selected from Hf and Y, 0.45 ≦ a ≦ 0.55, In the case of 0.01 ≦ b ≦ 0.1, 0 ≦ c ≦ 0.05, 0.01 ≦ d ≦ 0.1, 0 ≦ x ≦ 1), Ti _{1−a−b−c} Al _{a W b Si c M d (C} 1-y N y) ( however, M is at least one selected from Nb, Mo, Ta, Hf, and Y, 0 ≦ a ≦ 0.4,0.05 ≦ b ≦ 0.8, 0 ≦ c ≦ 0.01, 0 ≦ d ≦ 0.5, and 0.2 ≦ y ≦ 1).

  On the other hand, the configuration of the coating layer is not limited to the configuration of the coating layer 6, and may be, for example, the configuration of the coating layer 9 shown in the second embodiment shown in FIG. 3.

  That is, according to FIG. 3 showing the second embodiment of the present invention, the coating layer 9 is formed by alternately laminating two or more layers of the first layer 7 and the second layer 8. According to this configuration, the presence of the interface between the first layer 7 and the second layer 8 increases the lattice strain energy, improves the hardness, and increases the wear resistance. In addition, when a crack occurs on the surface of the coating layer 9, the crack resistance is hindered by the presence of the interface between the first layer 7 and the second layer 8, so that the fracture resistance of the coating layer 9 is increased.

  At this time, the film thickness of each layer of the first layer 7 is 0.02 to 0.7 μm, the film thickness of each layer of the second layer 8 is 0.01 to 0.5 μm, and the total film thickness of the first layer 7 is The total film thickness of 1 to 7 μm and the second layer 8 is preferably 0.5 to 5 μm from the viewpoint of improving the hardness of the coating layer and improving the fracture resistance.

  The substrate 2 may be a cemented carbide or cermet hard alloy composed of a hard phase mainly composed of tungsten carbide or titanium carbonitride and a binder phase mainly composed of an iron group metal such as cobalt or nickel, or silicon nitride. Hard materials such as ultra-high pressure sintered bodies that fire ceramics and aluminum oxide as a main component, hard phases composed of polycrystalline diamond and cubic boron nitride and binder phases such as ceramics and iron group metals under ultra-high pressure Preferably used.

(Production method)
Next, the manufacturing method of the cutting tool of this invention is demonstrated.

  First, the tool-shaped substrate 2 is manufactured using a conventionally known method. Next, coating layers 6 and 9 are formed on the surface of the substrate 2. A physical vapor deposition (PVD) method such as an ion plating method or a sputtering method can be suitably applied as a method for forming the coating layers 6 and 9.

  As an example of a suitable film forming method of the present invention, for example, there is a method of forming the coating layers 6 and 9 using a film forming apparatus having both an arc ion plating cathode and a magnetron sputtering cathode. That is, it is preferable to form a nitride layer of the first layer 7 by an arc ion plating method and form an oxide layer of the second layer 8 by a magnetron sputtering method.

Specifically, with a bias voltage of 30 to 200 V and a film formation temperature of 400 to 600 ° C., the arc ion plating cathode is irradiated with arc discharge or glow discharge to evaporate and ionize the metal source, and at the same time, nitrogen ( The first layer 7 is formed by reacting N ₂ ) gas or methane (CH ₄ ) / acetylene (C ₂ H ₂ ) gas as a carbon source at a gas pressure of ₂ to 5 Pa.

Next, the film forming temperature is set to 500 to 700 ° C., and pulse power of 3 kW to 7 kW is applied to the magnetron sputtering cathode. At that time, the repetition frequency is set to 20 to 100 kHz, and the duty cycle is set to 5 to 80%. As a bias voltage, a pulse DC voltage of 30 to 150 V, 50 kHz to 350 kHz is applied, and a mixed gas of oxygen and oxygen of 0.3 to 0.8 Pa (oxygen gas pressure 0.05 to 0.2 Pa) is allowed to flow to discharge state Then, the second layer 8 can be coated on the surface of the first layer 7.

  As the cathode, for example, metal titanium (Ti), metal aluminum (Al), metal W, metal Si, metal M (where M is Ti, W, periodic table group 4, 5, 6 elements, rare earth elements) A metal cathode containing one or more selected from the above, an alloy cathode obtained by compounding them, or a mixture cathode composed of a carbide, nitride, boride compound powder or sintered body thereof.

  In addition, the coating layer 9 having a configuration in which two or more first layers 7 and second layers 8 are alternately stacked can be formed by a method of repeating the respective film forming steps using the film forming apparatus.

Mainly composed of tungsten carbide (WC) powder having an average particle diameter of 0.8 μm, 10% by mass of metallic cobalt (Co) powder having an average particle diameter of 1.2 μm, and vanadium carbide (VC) powder having an average particle diameter of 1.0 μm. Chromium carbide (Cr ₃ C ₂ ) powder of 0.1% by mass and average particle size of 1.0 μm was added and mixed at a rate of 0.3% by mass and formed into a throw-away tip shape of CNMG120408MS by press molding. Then, the binder removal process was performed, and it sintered at 1450 degreeC in the vacuum of 0.01 Pa for 1 hour, and produced the cemented carbide alloy. Further, the rake face surface of each sample was polished by blasting, brushing or the like. Further, the prepared cemented carbide was subjected to blade edge processing (honing) by brushing.

  A coating layer having various compositions is formed on the substrate thus prepared according to the film formation conditions shown in Table 1 using a film formation apparatus having both an arc ion plating cathode and a magnetron sputtering cathode. Filmed.

  With respect to the obtained sample, the cross section including the surface of the coating layer was observed with a transmission electron microscope (TEM), and the average crystal width of the crystals constituting the coating layer was determined. Moreover, when observing with TEM, the composition in arbitrary three places of each coating layer was measured by energy dispersive spectroscopy (EDS), and these average values were computed as a composition of each coating layer. Furthermore, the presence or absence of dispersed particles in the coating layer and the composition thereof were confirmed.

  Next, a cutting test was performed under the following cutting conditions using the obtained outer diameter cutting tool CNMG120408MS throw-away tip. The results are shown in Table 3.

Cutting method: Outer turning work material: SUS304
Cutting speed: 150 m / min Feed: 0.2 mm / rev
Cutting depth: 2.0mm
Cutting condition: Wet evaluation method: 30 minutes after cutting side flank wear, tip wear, and chipping
Measured.

  From the results shown in Tables 1 to 3, the sample No. 1 composed of the structure in which the second layer was not formed and only the first layer was formed. In No. 10, chipping occurred. Sample No. 2 in which the second layer is not an oxide layer but a nitride layer is used. Nos. 13 and 14 were insufficient in oxidation resistance and had low wear resistance under severe cutting conditions as in this test. Furthermore, the sample No. 1 is made of a composition in which the first layer does not contain a metal M component (at least one selected from Nb, Mo, Ta, Hf and Y). No. 11 has poor wear resistance, and the sample No. 1 in which the first layer has a composition containing no W is used. In No. 12, the fracture resistance decreased.

  On the other hand, sample No. which is within the scope of the present invention. In each of Nos. 1 to 10, the coating layer was excellent in fracture resistance and oxidation resistance and exhibited good cutting performance.

  Sample No. 1 of Example 1 In the same manner as in Example 1, except that the coating layer of No. 2 was formed by laminating 25 layers with a cycle of a first layer of 0.2 μm and a second layer of 0.1 μm at a film forming temperature of 550 ° C. The cutting performance was similarly evaluated. As a result, no chipping was observed, and the wear width was as small as 0.08 mm.

It is a schematic perspective view which shows an example of the cutting tool of this invention. It is a cross-sectional schematic diagram which shows the 1st embodiment of the cutting tool of FIG. It is a cross-sectional schematic diagram which shows the 2nd embodiment of the cutting tool of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cutting tool 2 Base | substrate 3 Rake face 4 Relief face 5 Cutting edge 6, 9 Coating layer 7 1st layer 8 2nd layer

Claims (6)

A cutting tool comprising a base and a coating layer covering the surface of the base,
The coating layer is
_{Ti 1-a-b-c} -d Al a W b Si c M d (C 1-x N x) ( where M is at least one Nb, Mo, Ta, selected from Hf and Y, 0.45 ≦ a ≦ 0.55, 0.01 ≦ b ≦ 0.1, 0 ≦ c ≦ 0.05, 0.01 ≦ d ≦ 0.1, 0 ≦ x ≦ 1),
(Al _1-h M ′ _h ) _v O _w (where M ′ _h is one or more selected from Ti, Cr, Zr, Nb, Mo, Ta, Hf and Y, 0 ≦ h ≦ 0.65, 1 ≦ w / v ≦ 2.5). A cutting tool comprising the second layer.   The cutting tool according to claim 1, wherein the first layer has a thickness of 1 to 7 μm, and the second layer has a thickness of 0.5 to 5 μm.   The cutting tool according to claim 1 or 2, wherein the average crystal width of the first layer is 0.01 to 0.5 µm, and the average crystal width of the second layer is 0.6 to 3 µm.   The cutting tool according to any one of claims 1 to 3, wherein dispersed particles having an average crystal grain size of 0.05 to 1 µm are scattered in the first layer.   The cutting tool according to claim 1, wherein the coating layer is formed by alternately laminating two or more layers of the first layer and the second layer.   The thickness of each layer of the first layer is 0.02 to 0.7 μm, the thickness of each layer of the second layer is 0.01 to 0.5 μm, and the total thickness of the first layer is 1 to 7 μm. The cutting tool according to claim 5, wherein the total film thickness of the second layer is 0.5 to 5 μm.

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