JP2006297583A - Surface coated tool and cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated tool having high hardness, high toughness, excellent chipping resistance and wear resistance. <P>SOLUTION: The surface coated tool has a hard coating layer comprising at least TiN layer and TiCN layer in a contact state in this order on the surface of base substance made of a hard alloy. A diffracting plane showing the strongest peak intensity in X-ray diffraction of TiN layer is made to be (hkl) plane (where, (hkl) plane excepts (422) plane). When the ratio I (422)/I (hkl) of a peak intensity I (hkl) of (hkl) plane to the peak intensity I (422) of (422) plane in X-ray diffraction of TiCN layer is set to be R, the ratio R in the outer surface side is made to be larger than the ratio R in TiN layer side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface-coated tool such as a cutting tool in which a hard coating layer is formed on the surface of a substrate.

Conventionally, surface-coated tools having a hard coating layer formed on the surface of a substrate have been used for various purposes. For example, cutting tools widely used in metal cutting work include a TiC layer, a TiN layer, a TiCN layer, an Al ₂ O ₃ layer, a TiAlN layer, etc. on the surface of a hard substrate such as cemented carbide, cermet, or ceramics. A tool having a single hard coating layer or a plurality of hard coating layers is often used.

  On the other hand, further improvement in chipping resistance and wear resistance has been demanded as cutting efficiency has been improved recently. In particular, there is an increasing number of cuttings where a large impact such as heavy interrupted cutting of metal is applied to the cutting edge. Under such severe cutting conditions, the hard coating layer cannot withstand the large impact with conventional tools, and chipping and hard coating Layer delamination is likely to occur. Such chipping or peeling triggers a sudden tool damage such as chipping of the cutting edge or abnormal wear, resulting in a problem that the tool life cannot be extended.

Therefore, in order to improve the characteristics of the hard coating layer, Patent Document 1 discloses that a TiCN layer having the highest peak intensity on the (422) plane is formed as the first layer, thereby increasing the adhesion of the TiCN layer. And it is supposed that the adhesive force with other hard layers can be improved. Patent Document 2 states that excellent wear resistance is exhibited by forming a TiCN layer having the highest peak intensity on the (422) plane in the second and subsequent layers. Furthermore, Patent Document 3 describes a multilayer coating layer in which two or more of a TiC layer, a TiN layer, or a TiCN layer are formed on the surface of a substrate, and the highest peak on the X-ray diffraction peak surface of the first layer is described. It is described that by matching with the highest peak of the second layer, interlayer adhesion can be improved and cracks generated in the upper layer can be suppressed from progressing to the lower layer, resulting in improved fracture resistance.
Japanese Patent Laid-Open No. 5-220604 JP-A-6-158325 Japanese Patent Laid-Open No. 6-116731

  According to Patent Document 1 and Patent Document 2 described above, the TiCN layer exhibiting the highest peak intensity on the (422) plane is excellent in adhesion to the substrate and wear resistance, but is described in the examples of the same publication. Cutting conditions that are more severe than the cutting conditions, especially severe cutting conditions such as heavy interrupted cutting that are subject to suddenly large impacts, still cause chipping of the cutting edge, sudden breakage, etc., resulting in a short tool life. There is a problem.

  Further, as in Patent Document 3, in order to improve the adhesion between the first layer and the second layer and to suppress the progress of cracks, the highest peaks of the first layer and the second layer are simply matched. In this case, although the interlayer adhesion is improved, the wear resistance of the second layer is lowered and the tool life cannot be extended.

  Further, if the thickness of the hard coating layer is reduced for the purpose of preventing chipping or peeling of the hard coating layer, the hard coating layer disappears early due to wear, and the tool life cannot be extended. Furthermore, even when cutting steel or the like, further improvement in fracture resistance and wear resistance is required.

  Accordingly, the present invention has been made to solve the above-mentioned problems, and provides a surface-coated cutting tool such as a cutting tool that has excellent adhesion between the substrate and the hard coating layer and also has excellent wear resistance. Surface coatings such as cutting tools with excellent chipping resistance and wear resistance, especially in severe cutting conditions where the tool cutting edge is subject to strong impact such as cutting of metals such as steel, especially cast iron interrupted cutting The purpose is to provide a tool.

  As a result of studying a method for improving fracture resistance, chipping resistance, and wear resistance in a surface-coated tool having a hard coating layer including at least two layers on the surface of the substrate, the present inventor has found that the TiCN layer has It was found that by controlling the properties on the TiN layer side and the outer surface side to a predetermined state, the surface-coated tool was further improved in chipping resistance, chipping resistance and wear resistance.

That is, the surface coating tool of the present invention is a surface coating tool in which a hard coating layer including at least a TiN layer and a TiCN layer adjacent to each other in this order is formed on the surface of a substrate made of a hard material. The diffraction surface having the strongest peak intensity in the X-ray diffraction analysis is the (hkl) plane (excluding the (422) plane), and the peak intensity I _(hkl) of the (hkl) plane in the X-ray diffraction analysis of the TiCN layer is When the ratio (I ₍₄₂₂₎ / I _(hkl) ) to the peak intensity I ₍₄₂₂₎ of the ₍₄₂₂₎ surface is R, the ratio R in the region on the outer surface side of the surface-coated tool is the value on the TiN layer side. The ratio is larger than the ratio R in the region.

  Here, in the region on the TiN layer side in the TiCN layer, it is desirable that the diffractive surface having the strongest peak intensity is the (hkl) plane in terms of further improving the fracture resistance.

  Further, it is desirable that the ratio R is gradually increased from the TiN layer side toward the outer surface side in terms of further improving the fracture resistance.

Further, in the TiCN layer, when the X-ray diffraction analysis is performed in a state where a region having a thickness of 1.5 μm or less is exposed from the interface on the TiN layer side, the ratio R is _RA, and the thickness is measured from the interface on the outer surface side. when the said ratio R when the X-ray diffraction analysis in a state where 1.5μm following areas are exposed and R _B, the ratio R _a is 0.5 or less, and the ratio R _B is 1 or more It is desirable that the adhesion between the TiCN layer and the adjacent substrate or other layers can be increased.

The hard coating layer in the present invention preferably has an Al ₂ O ₃ layer on the outer surface side of the TiCN layer. Thereby, the improvement of the oxidation resistance of a hard coating layer and the improvement of wear resistance can be aimed at. Furthermore, it is desirable that the Al ₂ O ₃ layer has an α-type crystal structure from the viewpoint of further improving the wear resistance.

In this case, at least one layer selected from a TiN layer, a TiCN layer, a TiC layer, a TiCNO layer, a TiCO layer, and a TiNO layer is provided between the TiCN layer and the Al ₂ O ₃ layer in an amount of 0.01 to The thickness of 0.2 μm is desirable in that the adhesion between the TiCN layer and the Al ₂ O ₃ layer can be improved.

  Furthermore, the surface-coated tool having the above-described configuration can be applied to various uses such as tools such as cutting tools, excavation tools, and cutting tools. In particular, when a rake face and a flank face are formed, a cutting edge is formed at the intersection ridge line portion of the rake face and the flank face, and the cutting edge is applied to a workpiece to be used as a cutting tool Can exhibit the above-described excellent effects and has excellent mechanical reliability even when used for other purposes.

Further, in the cutting tool of the present invention, the ratio R when the X-ray diffraction analysis is performed with the TiCN layer existing on the rake face exposed to a region having a thickness of 1.5 μm or less from the interface on the TiN layer side is R when the _Ar, the ratio R when the X-ray diffraction analysis in a state where the following areas thickness 1.5μm is exposed from the interface of the TiN layer side in TiCN layer present on the flank and R _Af, these The ratio (R _Ar / R _Af ) is 1.1 to 5, and in the TiCN layer existing on the rake face, an area having a thickness of 1.5 μm or less is exposed from the interface on the outer surface side. the said ratio R when the the R _Br, the ratio when the X-ray diffraction analysis in a state where the outer surface side interface thickness 1.5μm following areas from the TiCN layer present on the flank was exposed When the R and _{R Bf,} preferably their ratio _(R Br _{/ R Bf)} is 1.5 to 10. Thereby, chipping resistance and wear resistance can be further improved.

Further, the substrate comprises one or more compounds selected from Group 4, 5, and 6 elements, cubic boron nitride, a hard phase mainly composed of diamond, and a binder phase mainly composed of an iron group metal, binder phase content B _F at the surface portion of the substrate in the flank, that less than the bonding phase amount B _R of the surface portion of the substrate in the rake face, within the above range the crystal orientation of the TiCN layer above It is possible to control the resistance to breakage and wear resistance.

Further, the ratio (B _F / B _I ) between the binding phase amount B _F at the surface portion of the substrate on the flank and the binding phase amount B _I inside the substrate is 0.6 to 0.9. and that the ratio of the binder phase content _{B I} in the base inside the binder phase content _{B R} of the surface portion of the substrate in the rake face _(B R / _{B I)} is 1.1 to 1.6 However, it is possible to control the crystal orientation of the above-described TiCN layer within the above range, and to exhibit excellent fracture resistance and wear resistance.

  According to the surface-coated tool of the present invention, by making the ratio R on the outer surface side larger than the ratio R on the TiN layer side, the outer surface side has high hardness and excellent wear resistance, and On the TiN layer side, the hard coating layer is excellent in toughness and adhesion to the substrate. This ensures high wear resistance to cutting conditions that require wear resistance, such as continuous cutting, and a sudden large impact is applied to the hard coating layer in machining that requires fracture resistance, such as intermittent cutting. Even if it is a case, the impact can be absorbed, and the layers of the hard coating layer and between the hard coating layer and the substrate can be peeled over a wide range, or the entire hard coating layer can be chipped or peeled off. Can be reduced.

  Therefore, not only steel cutting, but especially tool cutting blades when heavy interrupted cutting such as cast iron with dispersed high-hardness graphite particles such as gray cast iron (FC material) and ductile cast iron (FCD material) is used. A cutting tool with excellent fracture resistance and wear resistance is obtained even in severe cutting conditions that are subject to strong impacts, continuous cutting conditions, and combined cutting conditions that combine these intermittent cutting and continuous cutting. be able to.

  The surface-coated tool having the above configuration can be applied to various uses such as a cutting tool, an excavation tool, a tool such as a blade. In particular, when the cutting edge formed at the crossing ridge line portion between the rake face and the flank face is used as a cutting tool for cutting the workpiece, the above-described excellent effect can be exhibited more remarkably. Even if it is used for other purposes, it has excellent mechanical reliability.

  Hereinafter, a surface-coated tool according to an embodiment of the present invention will be described in detail.

  The surface coating tool of the present invention is obtained by depositing a hard coating layer including at least a TiN layer and a TiCN layer adjacent to each other in this order on the surface of a substrate (a cemented carbide or cermet in the present embodiment). .

Examples of the hard material include a hard alloy made of cemented carbide or cermet in which a hard phase is bonded with a bonded phase made of at least one iron group metal such as cobalt (Co) and nickel (Ni). Examples of the hard phase include tungsten carbide (WC), titanium carbide (TiC), or titanium carbonitride (TiCN), and groups of carbides, nitrides, and carbonitrides of Group 4a, 5a, and 6a metals of the periodic table as required. At least one selected from the group consisting of: Other examples of hard materials include, for example, silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ) ceramic sintered body, ultra-hard sintering mainly composed of cubic boron nitride (cBN) and diamond. The body can also be adapted. Among these hard materials, it is preferable to use the hard alloy in that high cutting performance can be exerted on a wide variety of work materials.

In the surface-coated tool of this embodiment, the diffraction surface having the strongest peak intensity in the X-ray diffraction analysis of the TiN layer is the (hkl) plane (however, the (hkl) plane is other than the (422) plane), and the X-ray of the TiCN layer when the ratio of the peak intensity of the (hkl) plane in the diffraction analysis _{I (hkl)} and (422) plane peak intensity _{I (422)} and _{(I (422) / I (hkl))} is R, the outside of the TiCN layer The ratio R on the surface side is larger than the ratio R in the region on the TiN layer side.

  As a result, a hard coating layer having high hardness and excellent wear resistance on the outer surface side and excellent toughness and adhesion to the substrate on the TiN layer side is obtained. As a result, it has high wear resistance for cutting conditions that require wear resistance such as continuous cutting, and in cases where fracture resistance is required such as intermittent cutting, suddenly large impacts are hard coated. Even when applied to a layer, the toughness is high and the adhesive strength of the hard coating layer is high, so the layers of the hard coating layer that peel off the impact can be peeled over a wide range, or the entire hard coating layer can be chipped. It can be reduced.

  Here, the fact that the diffraction surface having the strongest peak intensity in the TiN side region of the TiCN layer, particularly in the vicinity of the TiN side interface, is the (hkl) plane, in that the fracture resistance can be further improved. desirable.

  In addition, it is desirable that the ratio R is gradually increased from the TiN layer side interface to the outer surface side in terms of further improving the fracture resistance.

Further, in the TiCN layer, when the X-ray diffraction analysis is performed in a state where a region having a thickness of 1.5 μm or less is exposed from the interface on the TiN layer side, the ratio R is _RA, and the thickness is 1.5 μm or less from the outer surface side. when the ratio R when the X-ray diffraction analysis in a state where the regions exposed with R _B, the ratio R _a is 0.5 or less, and that the ratio R _B is 1 or more, TiCN layer It is desirable in that the adhesion force between the TiN layer and the substrate adjacent to each other can be increased.

Further, it is desirable that the hard coating layer has an Al ₂ O ₃ layer on the outer surface side of the TiCN layer in terms of improving the oxidation resistance and the wear resistance of the hard coating layer. Furthermore, it is desirable that the Al ₂ O ₃ layer has an α-type crystal structure from the viewpoint of further improving the wear resistance.

Conventionally, aluminum oxide having an α-type crystal structure has excellent wear resistance. However, since the particle size at the time of nucleation is large, the contact area with the TiCN layer is reduced, and the adhesion is weakened. As a result, there is a problem that film peeling is likely to occur. On the other hand, in the present invention, it is possible to control the adhesion between the Al ₂ O ₃ layer and the TiCN layer within a predetermined range by the tissue adjustment described above, even enough to the Al ₂ O ₃ layer as the α-type crystal structure Adhesive force can be obtained. Thereby, since it is possible to obtain excellent wear resistance due to the α-type crystal structure without reducing the adhesion of the Al ₂ O ₃ layer, it is possible to obtain a cutting tool having a longer life. Note that a part of the Al ₂ O ₃ crystal has a κ-type crystal structure other than the α-type crystal structure, that is, the crystal structure of the Al ₂ O ₃ layer is a mixed crystal of the α-type crystal structure and the κ-type crystal structure. Thus, it is also possible to adjust the adhesion of the Al ₂ O ₃ layer.

Further, at least one layer selected from the group consisting of a TiN layer, a TiCN layer, a TiC layer, a TiCNO layer, a TiCO layer, and a TiNO layer (hereinafter referred to as another Ti-based hard layer) between the TiCN layer and the Al ₂ O ₃ layer. .) With a film thickness of 0.01 to 0.2 μm is desirable in that the adhesion between the TiCN layer and the Al ₂ O ₃ layer can be easily adjusted, and the adhesion between them can be improved. . Here, in the case where a TiCN layer is provided between the TiCN layer and the Al ₂ O ₃ layer, these TiCN layers may have the same or different texture form such as a crystal structure.

When the Al ₂ O ₃ layer has an α-type crystal structure, an intermediate layer containing at least titanium and oxygen of 1 μm or less between the TiCN layer and the Al ₂ O ₃ layer, such as a TiCO layer, a TiNO layer, It is desirable to form a hard layer such as a TiCNO layer, a TiO ₂ layer, a Ti ₂ O ₃ layer or the like from the viewpoint that an α-type crystal structure can be stably grown, and the film thickness is particularly set to 0.5 μm or less. Thus, the adhesion of the Al ₂ O ₃ layer can be easily controlled.

Further, by forming the other Ti-based hard layer on the upper layer (outer surface side) of the Al ₂ O ₃ layer, adjustment of the slidability, appearance and the like of the hard coating layer surface is facilitated. Specifically, by forming a surface layer made of TiN on the surface of the hard coating film, the tool exhibits a gold color, so it is easy to determine whether the surface layer is worn and used when the tool is used, It is also desirable because the progress of wear can be easily confirmed. Furthermore, the surface layer is not limited to the TiN layer, and a DLC (diamond-like carbon) layer or a CrN layer may be formed to improve slidability. The thickness of the TiN layer constituting the surface layer is desirably 1 μm or less, and it is desirable that the peel strength of the surface layer is lower than the peel strength of the Al ₂ O ₃ film because it is easy to visually confirm whether it is used or not. .

  The surface-coated tool having the above configuration can be applied to various uses such as cutting tools, excavation tools, tools such as blades, and the like. When the cutting edge formed at the crossing ridge line portion between the rake face and the flank face is used as a cutting tool for applying a cutting work to the workpiece, the above-described excellent effect can be exhibited.

When used as a cutting tool, the ratio R when the X-ray diffraction analysis is performed in a state where a region of 1.5 μm or less in thickness is exposed from the interface on the TiN layer side in the TiCN layer existing on the rake face is R _Ar , and the flank When the ratio R when X-ray diffraction analysis is performed in a state where a region having a thickness of 1.5 μm or less is exposed from the interface on the TiN layer side in the TiCN layer existing in the region is R _Af , these ratios (R _Ar / R _Af ) Is 1.1 to 5, and the ratio R when the X-ray diffraction analysis is performed in a state where the region of 1.5 μm or less in thickness is exposed from the outer surface side interface in the TiCN layer existing on the rake face is R _Br When the ratio R when the X-ray diffraction analysis is performed with the region of 1.5 μm or less in thickness exposed from the interface on the outer surface side in the TiCN layer existing on the flank is R _Bf , these ratios (R _Br / R _Bf ) is preferably 1.5-10. This is desirable in that the fracture resistance can be further improved.

Further, in X-ray diffraction of the TiCN layer, the (311) plane peak intensity _{I (311)} and the ratio of the (220) plane peak intensity _{I (220) I (311) / I (220)} was R ' In some cases, it is desirable that the ratio R ′ on the outer surface side is larger than the ratio R ′ on the TiN layer side in order to improve adhesion to the substrate and at the same time suppress damage to the film itself during cutting.

  The base material used in the tool of the present invention includes a hard phase mainly composed of a compound of Group 4, 5, 6 elements, cubic boron nitride and diamond, and a bond mainly composed of an iron group metal. By using a hard alloy composed of a phase, for example, a cemented carbide composed of a hard phase mainly composed of tungsten carbide and a binder phase composed mainly of cobalt as described above, sufficient for cutting. High hardness and strength.

Furthermore, in order to achieve the performance of the tool of the present invention, binder phase content B _F at the surface of the substrate flank is less than the binding phase weight B _R on the surface of the substrate of the rake face (B F _{<B R)} It is desirable. This makes a difference in the film growth state when the TiCN layer is formed on the rake face and the flank face, and the TiCN layer on the rake face is easily oriented to the (422) face, and the TiCN layer on the flank face becomes (422). ) It becomes difficult to orient on the surface. _{Incidentally,} preferable range of B R / _{B F} is 1.2 to 3.5.

Further, the binder phase content ratio of the binder phase content _{B I} in the interior of _{B F} and the substrate _(B F / _{B I)} is 0.6 to 0.9, and the binder phase content _{B R} and the binder phase When the ratio to the amount B _I (B _R / B _I ) is 1.1 to 1.6, the growth state of TiCN particles in the rake face TiCN layer and the flank TiCN layer is controlled within a predetermined range. This is desirable because it can be done.

Incidentally, the rake surface and the binding phase content in the surface portion of the substrate in the flank face _B R, when measuring the binding amount of phase _{B I} in the interior of _{B F,} and the substrate, X-rays microanalyzer (Electron Probe Micro-Anarysis : EPMA) and surface analysis methods such as Auger Electron Spectroscopy (AES). Specifically, the surface and the inside of the substrate to be measured may be exposed and measured. For example, the hard coating layer is polished, etched, etc., and the surface of the substrate is exposed to cut the sample with a surface or a diamond grindstone. It can be measured in the resulting cross section. The amount of binder phase B _R , _BF of the surface portion of the substrate on the rake face and flank face is in a region of 1.5 μm or less from the interface between the base body and the hard coating layer on the rake face and flank face toward the inside of the substrate. , binder phase content B _I of the interior of the substrate can be measured by 500μm or more depth region toward the surface of the substrate in the interior of substrate.

(Production method)
Next, a method for manufacturing a cutting tool which is an embodiment of the surface-coated tool of the present invention will be described.

  First, metal powder, carbon powder, etc. are appropriately added to and mixed with inorganic powders such as metal carbides, nitrides, carbonitrides, and oxides that can be formed by firing the hard alloy described above, press molding, cast molding, After forming into a predetermined tool shape by a known forming method such as extrusion molding or cold isostatic pressing, a substrate made of the above-described hard alloy is produced by firing in a vacuum or non-oxidizing atmosphere. Then, polishing or honing of the cutting edge portion is performed on the surface of the base as desired.

  The surface roughness of the substrate is such that the arithmetic average roughness (Ra) on the rake face is 0.1 to 1.5 μm and the arithmetic average roughness (Ra) on the flank face is 0 in terms of controlling the adhesive force of the hard coating layer. The particle size of the raw material powder, the molding method, the firing method, and the processing method are controlled so as to be 5 to 3.0 μm.

Next, a hard coating layer is formed on the surface by, for example, chemical vapor deposition (CVD). First, a mixed gas composed of titanium chloride (TiCl ₄ ) gas of 0.1 to 10% by volume, nitrogen (N ₂ ) gas of 5 to 60% by volume, and the balance of hydrogen (H ₂ ) gas as a reaction gas composition Then, it is introduced into the reaction chamber, and a TiN layer (first layer) as a base layer is formed in the chamber under conditions of 800 to 1000 ° C. and 10 to 30 kPa. At this time, the X-ray diffraction of the TiN layer (first layer) is adjusted by adjusting the volume ratio of titanium chloride (TiCl ₄ ) gas and nitrogen (N ₂ ) gas in the film forming conditions and the furnace temperature. The strongest peak in the chart can be changed.

Next, the reaction gas composition is 0.1 to 10% by volume of titanium chloride (TiCl ₄ ) gas, 0 to 60% by volume of nitrogen (N ₂ ) gas, and 0 to 0 of methane (CH ₄ ) gas in volume%. .1% by volume, acetonitrile (CH ₃ CN) gas is 0.1 to 0.4% by volume, and the remaining gas mixture is hydrogen (H ₂ ) gas, and the mixture is introduced into the reaction chamber, and the film formation temperature is adjusted. A TiCN layer (second layer) is formed at 780 to 950 ° C. and 5 to 25 kPa.

Here, among the film formation conditions, the ratio of the introduction flow rate of titanium chloride (TiCl ₄ ) gas in the reaction gas and the introduction flow rate of acetonitrile (CH ₃ CN) gas in the first stage of formation of the TiCN layer (titanium chloride (TiCl ₄ ) / acetonitrile (CH ₃ CN) gas), and the ratio (titanium chloride (TiCl ₄ ) / acetonitrile (CH ₃ CN) gas) in the reaction gas in the late stage of the TiCN layer deposition is larger than that described above. The structure of the TiCN layer can be adopted. More preferably, the ratio in the deposition year of TiCN layer (titanium chloride (TiCl ₄₎ / acetonitrile _(CH 3 CN) gas) the ratio (titanium tetrachloride during deposition late TiCN layer with respect to (TiCl ₄₎ / it is possible to reliably control by acetonitrile _(CH 3 CN) gas) 1.5 times or more.

  In addition, a desirable range of the flow rate of nitrogen gas is 5 to 50% by volume in the initial stage of film formation, and it is desirable that the flow rate in the initial stage of film formation be twice that in the initial stage of film formation. A desirable range of the film formation temperature is 850 to 950 ° C. in the initial stage of film formation, 780 to 900 ° C. in the later stage of film formation, and preferably 50 ° C. or lower than the initial stage of film formation. In particular, it is desirable to gradually change the film formation conditions.

The TiCN layer is adjusted by adjusting CH ₃ CN so that the above conditions are satisfied while observing the film formation conditions of the TiCN layer, ie, the mixed gas composition ratio of the first TiN layer and the film formation temperature. The ratio of the peak of the (hkl) plane (the peak of the same plane as the strongest peak of the TiN layer) on the TiN layer (first layer) side of the (second layer) can be increased.

Next, an intermediate layer is formed as desired. For example, when a TiCNO layer is formed as an intermediate layer, titanium chloride (TiCl ₄ ) gas is 0.1 to 3% by volume, methane (CH ₄ ) gas is 0.1 to 10% by volume, carbon dioxide (CO ₂ ) A mixed gas consisting of 0.01 to 5% by volume of gas, 0 to 60% by volume of nitrogen (N ₂ ) gas, and the remaining hydrogen (H ₂ ) gas is prepared and introduced into the reaction chamber. 800-1100 ° C., 5-30 kPa.

  In the case of forming a TiCN layer as an intermediate layer, for example, the reaction gas composition is 0.1 to 10 vol% of TiCl4 gas, 0 to 60 vol% of N2 gas, 0.1 to 10 vol% of CH4 gas, and the rest Are sequentially adjusted and introduced into the reaction chamber, and the inside of the chamber is set to 800 to 1100 ° C. and 5 to 85 kPa.

Subsequently, an Al ₂ O ₃ layer is formed. As a method for forming the Al ₂ O ₃ layer, ₃ to 20% by volume of aluminum chloride (AlCl ₃ ) gas, 0.5 to 3.5% by volume of hydrogen chloride (HCl) gas, and carbon dioxide (CO ₂ ) gas 0.01 to 5.0% by volume, hydrogen sulfide (H ₂ S) gas is 0 to 0.01% by volume, and the balance is hydrogen (H ₂ ) gas. 10 kPa is desirable.

In order to form a surface layer (TiN layer), the reaction gas composition is titanium chloride (TiCl ₄ ) gas of 0.1 to 10% by volume, nitrogen (N ₂ ) gas of 5 to 60% by volume, and the remainder is hydrogen. A mixed gas composed of (H ₂ ) gas may be adjusted and introduced into the reaction chamber, and the inside of the chamber may be set to 800 to 1100 ° C. and 5 to 85 kPa.

  Then, if desired, at least the cutting edge portion of the surface of the formed hard coating layer is polished. By this polishing process, the residual stress remaining in the hard coating layer is released, and the cutting tool is further excellent in fracture resistance.

  Note that the present invention is not limited to the above embodiment. For example, in the above description, a case where a chemical vapor deposition (CVD) method is used as a film forming method has been described. The whole may be formed by physical vapor deposition (PVD).

  For example, even when a TiCN layer is formed by an ion plating method, by controlling the structure of the TiCN layer within the above-described range, it is possible to produce a tool having excellent fracture resistance and excellent wear resistance. it can.

  Further, in order to control the amount of the binder phase inside and on the surface of the substrate, it is preferable to adopt the following conditions when manufacturing the substrate.

  As described above, after forming into a predetermined tool shape by a known forming method, it is fired in a vacuum or in a non-oxidizing atmosphere at 1500 ° C. to 1550 ° C. for 1 to 1.5 hours. And after baking at the said baking temperature, it hold | maintains for 5 minutes-10 minutes at the temperature 30-30 degreeC higher than a baking temperature, or after baking by the said baking temperature and cooling, once baking is complete | finished again, A heat treatment is performed at a temperature higher by 30 ° C. to 50 ° C. than the firing temperature for 5 minutes to 10 minutes. As a result, a substrate having a binder phase-poor layer in which the binder phase has evaporated on the surface of the substrate and a binder phase-enriched layer having a binder phase content directly below (inside) the interior of the substrate is obtained.

Next, the binder phase-poor layer existing on the surface of the rake face of the substrate is removed, and a polishing process is preferably performed so that the binder phase-enriched layer remains and is exposed to the substrate surface of the rake face. Thus, the binder phase content existing on the rake face surface and the flank face surface of the substrate can be controlled to be within a predetermined range (B _R > B _F ), and when the TiCN layer is formed, The crystal growth state of the TiCN layer on the rake face side and the flank face side can be controlled. Moreover, the effect | action that the smoothness of a rake face is also improved by the grinding | polishing removal process of the said binder phase poor layer is also acquired.

  6% by mass of metallic cobalt (Co) powder with an average particle size of 1.5 μm and 0% titanium carbide (TiC) powder with an average particle size of 2.0 μm with respect to tungsten carbide (WC) powder with an average particle size of 1.5 μm. 0.5% by mass and TaC powder were added and mixed at a rate of 1% by mass and formed into a cutting tool shape (CNMA 12020412) by press molding. Then, binder removal treatment is performed, and the temperature is increased at a rate of 1000 ° C. or higher at a rate of 3 ° C./min. Then, by cooling, a cemented carbide having a binder phase poor layer and a binder phase enriched layer on the surface was produced. Further, polishing was performed so that the surface of the rake face was in the state shown in Table 1.

  Further, on the flank face of the obtained substrate, the arithmetic average roughness (Ra) according to JISB0601-2001 was 1.1 μm, and the arithmetic average roughness (Ra) on the rake face was 0.4 μm.

Next, a hard coating layer composed of a multilayer film having a structure shown in Table 2 was formed on the cemented carbide by a CVD method. The deposition conditions for each layer in Table 2 are shown in Table 3. Then, the surface of the hard coating layer was brushed for 30 seconds from the rake face side, and sample No. 1 to 7 surface-coated tools were produced.

  For the obtained tool, the rake face and flank face of the tool were each polished to a predetermined thickness of the TiCN layer by brushing, and X-ray diffraction measurement was performed for peak identification and quantification. In the X-ray diffraction measurement, measurement was performed using Cu—Kα rays under the conditions of a voltage of 40 kV and a current of 40 mA, and the diffraction chart used data obtained by performing Kα ray removal processing.

In addition, “R _Ar ” in Table 2 is obtained when X-ray diffraction analysis is performed in a state in which a region having a thickness of 0.5 μm to 1.5 μm is exposed from the interface on the TiN layer side in the TiCN layer existing on the rake face. The ratio R represents “R _Af ”, which is a ratio when X-ray diffraction analysis is performed in a state where a region of 0.5 μm to 1.5 μm in thickness is exposed from the interface on the TiN layer side in the TiCN layer existing on the flank. R is represented. Further, “R _Br ” in Table 2 represents the values obtained when X-ray diffraction analysis was performed in a state where a region having a thickness of 0.5 μm to 1.5 μm was exposed from the interface on the outer surface side in the TiCN layer existing on the rake face. The ratio R represents “R _Bf ”, which is a ratio when X-ray diffraction analysis is performed in a state in which a region having a thickness of 0.5 μm to 1.5 μm is exposed from the interface on the outer surface side in the TiCN layer existing on the flank. R is represented.

Further, for the obtained cutting tool, the amount of binder phase B _R , B _F at the surface portion of the substrate on the rake face and flank and the amount of binder phase B _I inside the substrate are measured with an X-ray microanalyzer (Electron Probe). (Micro-Analysis: EPMA), and the results are shown in Table 1. In the cross section obtained by cutting the sample with a diamond grindstone or the like, the exposed surface and the inside of the substrate were measured as described above.

  In addition, a scratch test was performed under the following conditions, and scratches were observed to check the delamination state and the load at which the hard coating layer began to peel from the substrate, and the adhesion was calculated.

Apparatus: CSEM-REVETEST manufactured by Nanotech
Measurement conditions Table speed: 0.17 mm / sec
Load speed: 100 N / min (continuous load)
Scratch distance: 5mm
Indenter Conical diamond indenter (Diamond contactor manufactured by Tokyo Diamond Tool Mfg. Co., Ltd .: N2-1487)
Curvature radius: 0.2mm
Ridge angle: 120 °
Then, using this cutting tool, a continuous cutting test and an intermittent cutting test were performed under the following conditions to evaluate the wear resistance and fracture resistance.

(Continuous cutting conditions)
Work material: Ductile cast iron 4-slot sleeve material (FCD700)
Tool shape: CNMA120204
Cutting speed: 250 m / min Feeding speed: 0.3 mm / rev
Cutting depth: 2mm
Cutting time: 20 minutes Others: Use of water-soluble cutting fluid Evaluation item: Observe the cutting edge with a microscope and measure the amount of flank wear and tip wear (intermittent cutting conditions)
Work material: Ductile cast iron 4-slot sleeve material (FCD700)
Tool shape: CNMA120204
Cutting speed: 250 m / min Feeding speed: 0.3 to 0.5 mm / rev
Cutting depth: 2mm
Other: Use of water-soluble cutting fluid Evaluation item: Number of impacts leading to breakage
Observe the peeling state of the hard coating layer of the cutting edge with a microscope when the number of impacts is 1000. From Tables 2 and 3, Sample No. has a smaller ratio R (I ₍₄₂₂₎ / I _(hkl) ) on the outer surface side than on the TiN layer side . In No. 6, chipping occurred due to film peeling, resulting in poor fracture resistance, and flank wear also increased in continuous cutting. Moreover, the ratio R (I ₍₄₂₂₎ / I _(hkl) ) is the same for sample Nos. On the TiN layer side and the outer surface side. In No. 7, many film peeling occurred in the intermittent cutting, and the abrasion resistance was inferior in the continuous cutting.

On the other hand, the ratio R (I ₍₄₂₂₎ / I _(hkl) ) No. is larger on the outer surface side than on the TiN layer side. In 1-4, no peeling of the hard coating layer occurred in the intermittent cutting, the number of impacts that can withstand the impact in the intermittent cutting test was further improved, long life in both continuous cutting and intermittent cutting, fracture resistance, It had excellent cutting performance as well as chipping resistance.

Claims (11)

In a surface-coated tool in which a hard coating layer including at least a TiN layer and a TiCN layer adjacent to each other in this order is formed on the surface of a substrate made of a hard material, the highest peak intensity is obtained in the X-ray diffraction analysis of the TiN layer. a diffraction surface (hkl) plane (where (422) except for the surface), and the in the X-ray diffraction analysis of the TiCN layer and the (hkl) plane peak intensity _{I (hkl)} (422) plane peak intensity _{I (422 )} And the ratio (I ₍₄₂₂₎ / I _(hkl) ) to R, the ratio R in the region on the outer surface side of the surface-coated tool is larger than the ratio R in the region on the TiN layer side. Characteristic surface coating tool. 2. The surface-coated tool according to claim 1, wherein in the region on the TiN layer side in the TiCN layer, the diffraction surface having the strongest peak intensity is the (hkl) surface. The surface-coated tool according to claim 1 or 2, wherein the ratio R gradually increases from the TiN layer side toward the outer surface side. In the TiCN layer, the ratio R when X-ray diffraction analysis is performed in a state where a region having a thickness of 1.5 μm or less is exposed from the interface on the TiN layer side is R _A, and the thickness 1. when the ratio R when the X-ray diffraction analysis in a state where 5μm following areas are exposed and R _B, wherein said ratio R _a is 0.5 or less, and the ratio R _B is 1 or more Item 4. The surface-coated tool according to any one of Items 1 to 3. The surface coating tool according to any one of claims 1 to 4, wherein the hard coating layer has an Al ₂ O ₃ layer on the outer surface side of the TiCN layer. The surface-coated tool according to claim 5, wherein the Al ₂ O ₃ layer has an α-type crystal structure. Between the TiCN layer and the Al ₂ O ₃ layer, at least one layer selected from a TiN layer, a TiCN layer, a TiC layer, a TiCNO layer, a TiCO layer, and a TiNO layer has a thickness of 0.01 to 0.2 μm. The surface-coated tool according to claim 5 or 6, wherein the surface-coated tool is formed. The surface-coated tool according to any one of claims 1 to 7, wherein a rake face and a flank face are formed, and a cutting edge is formed at a cross ridge line portion between the rake face and the flank face. In the TiCN layer existing on the rake face, the ratio R when an X-ray diffraction analysis is performed in a state where a region having a thickness of 1.5 μm or less is exposed from the interface on the TiN layer side is R _Ar and exists on the flank face. When the ratio R when the X-ray diffraction analysis is performed in a state where a region having a thickness of 1.5 μm or less is exposed from the interface on the TiN layer side in the TiCN layer is R _Af , these ratios (R _Ar / R _Af ) Is 1.1-5,
In the TiCN layer existing on the rake face, the ratio R when the X-ray diffraction analysis is performed in a state where a region having a thickness of 1.5 μm or less is exposed from the interface on the outer surface side is R _Br and exists on the flank face. When the ratio R when the X-ray diffraction analysis is performed with the region having a thickness of 1.5 μm or less exposed from the interface on the outer surface side in the TiCN layer is R _Bf , these ratios (R _Br / R _Bf ) The cutting tool according to claim 8, wherein is 1.5 to 10. The flank is composed of one or more compounds selected from Group 4, 5 and 6 elements, cubic boron nitride, a hard phase mainly composed of diamond, and a binder phase mainly composed of an iron group metal. cutting tool according to claim 8 or 9 binder phase content B _F at the surface portion of said substrate, characterized in that less than the bonding phase amount B _R of the surface portion of the substrate in the rake face in. The ratio (B _F / B _I ) between the binding phase amount B _F at the surface portion of the substrate on the flank and the binding phase amount B _I inside the substrate is 0.6 to 0.9, and wherein the ratio of the binder phase content _{B I} in the base inside the binder phase content _{B R} of the surface portion of the substrate in the rake face _(B R / _{B I)} is 1.1 to 1.6 The cutting tool according to claim 10.