Coated tool

A coated tool includes a base and a coating layer on the base. The coating layer includes a first layer including Al2O3 particles, and a second layer on the first layer. The second layer includes, sequentially from the base, a first film, a second film in contact with the first film, and a third film in contact with the second film. The first to third films individually include Ti. The first film, the second film and the third film individually include at least one kind selected from C and N. The coated tool satisfies a relationship of a first N content>a third N content>a second N content, in which the first N content is an N content in the first film, the second N content is an N content in the second film, and the third N content is an N content in the third film.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a National Phase of International Application No. PCT/JP2021/012104 filed Mar. 24, 2021, which claims priority to Japanese Patent Application No. 2020-057684, filed Mar. 27, 2020. The contents of this Japanese application are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a coated tool.

BACKGROUND

For example, a surface-coated cutting tool discussed in Japanese Unexamined Patent Publication No. 2017-221992 (Patent Document 1) has been known as a coated tool. A coating film including an inner layer and an outer layer is disposed on a base in the surface-coated cutting tool discussed in Patent Document 1. The inner layer includes an aluminum oxide layer as a layer in contact with the outer layer. The outer layer includes a multilayer structure with three or more layers laminated one upon another, and individual layers constituting the multilayer structure include titanium.

SUMMARY

A coated tool in a non-limiting embodiment of the present disclosure includes a base and a coating layer located on the base. The coated tool includes a first surface, a second surface adjacent to the first surface, and a cutting edge located on at least a part of a ridge part of the first surface and the second surface. The coating layer includes a first coating layer which includes a first layer including Al2O3particles, and a second layer located on the first layer. The second layer includes, sequentially from a side of the base, a first film, a second film in contact with the first film, and a third film in contact with the second film. The first film, the second film and the third film individually include Ti. The first film, the second film and the third film individually include at least one kind selected from C and N. The coated tool satisfies a relationship of a first N content>a third N content>a second N content, in which the first N content is an N content in the first film, the second N content is an N content in the second film, and the third N content is an N content in the third film.

EMBODIMENT

Coated tools1in non-limiting embodiments of the present disclosure are described in detail below with reference to the drawings. For the convenience of description, the drawings referred to in the following illustrate, in simplified form, only main members necessary for describing the embodiments. The coated tools1may therefore include any arbitrary structural member not illustrated in the drawings referred to. Dimensions of the members in each of the drawings faithfully represent neither dimensions of actual structural members nor dimensional ratios of these members.

FIGS.1to4illustrate, as an embodiment of the coated tools1, a cutting insert applicable to a cutting tool used for a cutting process of a workpiece. The coated tool1is applicable to, besides cutting tools, wear resistant parts such as sliding parts and metal molds, digging tools, tools such as blades, and impact resistant parts. Applications of the coated tools1are not limited to those exemplified above.

The coated tool1may include a base2and a coating layer3located on the base2.

Examples of material of the base2may include hard alloys, ceramics and metals. Examples of the hard alloys may include cemented carbides in which a hard phase composed of WC (tungsten carbide) and, if desired, at least one kind selected from the group consisting of carbide, nitride and carbonitride of group 4, group 5 and group 6 metals in the periodic table other than WC is bonded by a binding phase composed of an iron group metal such as Co (cobalt) or Ni (nickel). Other hard alloys may be Ti-based cermets. The ceramics may be, for example, Si3N4(silicon nitride), Al2O3(aluminum oxide), diamond and cBN (cubic boron nitride). The metals may be, for example, carbon steel, high-speed steel and alloy steel. The material of the base2is however not limited to those exemplified above.

The coating layer3may cover a whole or a part of a surface4of the base2. If the coating layer3covers only the part of the surface4of the base2, it may be said that the coating layer3is located on at least the part of the base2.

The coating layer3may be deposited by chemical vapor deposition (CVD) method. In other words, the coating layer3may be a CVD film.

The coating layer3is not limited to a specific thickness. A thickness of the coating layer3may be set to, for example, 1-30 μm. The thickness and structure of the coating layer3, and shapes of crystals constituting the coating layer3may be measured by, for example, cross-section observation with an electron microscope. Examples of the electron microscope may include Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM).

The coated tool1may include a first surface5(upper surface), a second surface6(lateral surface) adjacent to the first surface5, and a cutting edge7located on at least apart of a ridge part between the first surface5and the second surface6as in a non-limiting embodiment illustrated inFIGS.1and2.

The first surface5may be a rake surface. A whole or a part of the first surface5may be the rake surface. For example, a region extending along the cutting edge7in the first surface5may be the rake surface.

The second surface6may be a flank surface. A whole or a part of the second surface6may be the flank surface. For example, a region extending along the cutting edge7in the second surface6may be the flank surface.

The cutting edge7may be located on a part or a whole of the ridge part. The cutting edge7is usable for cutting out a workpiece.

The coated tool1may have a quadrangular plate shape as in the non-limiting embodiment illustrated inFIG.1. The shape of the coated tool1is not limited to the quadrangular plate shape. For example, the first surface5may have a triangular shape, a pentagonal shape, a hexagonal shape, or a circular shape. The coated tool1may have a columnar shape.

The coated tool1is not limited to a specific size. For example, a length of one side of the first surface5may be set to approximately 3-20 mm. A height from the first surface5to a surface (lower surface) located on a side opposite to the first surface5may be set to approximately 5-20 mm.

The coating layer3may include a first coating layer8as in a non-limiting embodiment illustrated inFIG.3. The first coating layer8may include a first layer9and a second layer10located on the first layer9.

The first layer9may include Al2O3particles. The first layer9may be an Al2O3layer. The Al2O3layer may denote a layer including Al2O3as a main ingredient. The term “main ingredient” may denote an ingredient having the largest value of mass % in comparison to other ingredients.

The second layer10may include, sequentially from a side of the base2, a first film11, a second film12in contact with the first film11, and a third film13in contact with the second film12.

The first film11, the second film12and the third film13may individually include Ti (titanium). The first film11, the second film12and the third film13may also individually include at least one kind selected from C (carbon) and N (nitrogen).

More specifically, the first film11, the second film12and the third film13may individually include a titanium compound. The first film11, the second film12and the third film13may individually include the titanium compound as a main ingredient. Examples of the titanium compound may include carbides, nitrides, oxides, carbonitrides, carbonates and carboxynitrides of titanium.

The embodiments may satisfy a relationship of a first N content>a third N content>a second N content, in which the first N content is an n content in the first film11, the second N content is an N content in the second film12, and the third N content is an N content in the third film13.

If satisfying the above relationship, the first film11is mostly likely to peel off among the first film11, the second film12and the third film13. In other words, the first film11has the lowest adhesion among the first film11, the second film12and the third film13. The first film11is most excellent in welding resistance among the first film11, the second film12and the third film13.

If satisfying the above relationship, the second film12has the highest hardness among the first film11, the second film12and the third film13. Meanwhile, the second film12has the lowest welding resistance among the first film11, the second film12and the third film13.

If satisfying the above relationship, the third film13has hardness, peeling resistance and welding resistance which are intermediate between those of the first film11and the second film12.

The coated tool1, in which the individual films thus configured have the above coating configuration, is excellent in wear resistance and welding resistance.

The first N content, the second N content and the third N content are not limited to a specific value. For example, the first N content may be set to 45-55 atom %. The second N content may be set to 0-25 atom %. The third N content may be set to 25-45 atom %. The N content may be a value measured by, for example, an energy dispersive X-ray spectroscopy (EDS) analysis method.

It may be y1=1. That is, the first film11may include TiN particles. The first film11may be a TiN film. The TiN film may mean a film including TiN as a main ingredient. This may be also true for other films.

It may be x2=1. It may also be 0<x3<1, 0<y3<1, and z3=0. That is, the second film12may include TiC particles, and the third film13may include TiCN particles. The second film12may be a TiC film, and the third film13may be a TiCN film.

It may be 0<x2<1, 0<y2<1, and z2=0. It may also be 0<x3<1, 0<y3<1, and z3=0. That is, the second film12and the third film13may individually include TiCN particles. The second film12and the third film13may individually be a TiCN film.

In cases where the second film12and the third film13individually include TiCN particles, it may be X2>X3. That is, a C content in the second film12may be larger than a C content in the third film13.

The third film13may include C and N. N/(C+N) in the third film13may be 0.7 or more. N/(C+N) in the third film13may be 0.9 or less. The N/(C+N) may be a content ratio of N in atomic ratio to a sum of C and N. The N/(C+N) may be measured by, for example, the energy dispersive X-ray spectroscopy (EDS) analysis method. The N/(C+N) represents an atomic ratio.

The first film11, the second film12and the third film13may have the same or different thicknesses. For example, the second film12may have a larger thickness than each of the first film11and third film13. This leads to enhanced wear resistance.

The thickness of each of the first film11, the second film12and the third film13is not limited to a specific value. For example, the thickness of the first film11may be set to 0.1-0.5 μm. The thickness of the second film12may be set to 0.5-1.0 μm. The thickness of the third film13may be set to 0.3-0.7 μm. The thickness of the second film12may be 40% or more of an entire thickness of the second layer10.

The thickness of the second layer10may be the same as or different from the thickness of the first layer9. For example, the thickness of the second layer10may be larger than the thickness of the first layer9.

The second layer10may or may not be in contact with the first layer9. Similarly, the first layer9may or may not be in contact with the base2. For example, the first coating layer8may include other layer located between the first layer9and the second layer10, or other layer located between the base2and the first layer9. The other layer may include TiN particles, TIC particles or TiCN particles. The other layer may be a TiN film, TiC film or TiCN film.

The first coating layer8may be located on the first surface5(rake surface). This leads to enhanced wear resistance and welding resistance of the first surface5.

The first coating layer8may be located on the second surface6(flank surface). This leads to enhanced wear resistance and welding resistance of the second surface6.

The coating layer3may include a second coating layer14as in a non-limiting embodiment illustrated inFIG.4. The second coating layer14may include a third layer15. The third layer15may include Al2O3particles. The third layer15may be an Al2O3layer. The third layer15may be an outermost layer.

The second coating layer14may be located on the second surface6(flank surface). This leads to enhanced welding resistance of the second surface6.

The second coating layer14may be located on the first surface5(rake surface). This leads to enhanced welding resistance of the first surface5.

The first coating layer8may be located on the first surface5(rake surface), and the second coating layer14may be located on the second surface (flank surface). These lead to enhanced wear resistance and welding resistance of the first surface5, and enhanced welding resistance of the second surface6.

The first coating layer8may be located on the second surface6(flank surface), and the second coating layer14may be located on the first surface5(rake surface). These lead to enhanced welding resistance of the first surface5, and enhanced wear resistance and welding resistance of the second surface6.

<Method for Manufacturing Coated Tool>

A method for manufacturing a coated tool in a non-limiting embodiment of the present disclosure is described below by illustrating an embodiment of manufacturing the coated tool1.

A base2may be firstly manufactured. A description is given by illustrating cases where the base2composed of a hard alloy is manufactured as the base2. Firstly, a mixed powder may be prepared by suitably adding metal powder, carbon powder or the like to an inorganic powder of metal carbide, nitride, carbonitride, oxide or the like, with which it is possible to form the base2by sintering, and by mixing them together. A molded body may be obtained by molding the mixed powder into a predetermined tool shape with a known molding method, such as press molding, casting molding, extrusion molding or cold isostatic pressing. Subsequently, the base2may be obtained by sintering the obtained molded body in a vacuum or a non-oxidizing atmosphere. A surface4of the base2may be subjected to polishing process and honing process.

Subsequently, the coated tool1may be obtained by depositing a coating layer3on the surface4of the obtained base2by CVD method.

In cases where the first layer9is in contact with the base2as in the non-limiting embodiment illustrated inFIG.3, a first layer9(Al2O3layer) may be firstly deposited. First of all, a mixed gas may be prepared as a reaction gas composition. The mixed gas is composed of 0.5-5 vol % of aluminum trichloride (AlCl3) gas, 0.5-3.5 vol % of hydrogen chloride (HCl) gas, 0.5-5 vol % of carbon dioxide (CO2) gas, 0.5 vol % or less of hydrogen sulfide (H2S) gas, and the rest, namely, hydrogen (H2) gas. A first layer9may be deposited by loading the mixed gas into a chamber in which a set temperature is 930-1010° C., a set pressure is 5-10 kPa and a set time is 30-300 minutes. The above deposition conditions are applicable to a third layer15.

Subsequently, a first film11, a second film12and a third film13in a second layer10may be sequentially deposited.

The following description is given by illustrating cases where a TiN film is deposited as the first film11. Firstly, a mixed gas may be prepared as a reaction gas composition. The mixed gas is composed of 0.1-10 vol % of titanium tetrachloride (TiCl4) gas, 10-60 vol % of nitrogen (N2) gas, and the rest, namely, hydrogen (H2) gas. The first film11that is the TiN film may be deposited by loading the mixed gas into the chamber in which a set temperature is 800-1010° C., a set pressure is 10-85 kPa and a set time is 10-60 minutes.

The following description is given by illustrating cases where a TiC film is deposited as the second film12. Firstly, a mixed gas may be prepared as a reaction gas composition. The mixed gas is composed of 0.1-30 vol % of titanium tetrachloride (TiCl4) gas, 0.1-20 vol % of methane (CH4) gas, and the rest, namely, hydrogen (H2) gas. The second film12that is the TiC film may be deposited by loading the mixed gas into the chamber in which a set temperature is 800-1100° C., a set pressure is 10-85 kPa and a set time is 10-120 minutes.

The following description is given by illustrating cases where a TiCN film is deposited as the third film13. Firstly, a mixed gas may be prepared as a reaction gas composition. The mixed gas is composed of 0.1-10 vol % of titanium tetrachloride (TiCl4) gas, 10-60 vol % of nitrogen (N2) gas, 0.1-15 vol % of methane (CH4) gas, and the rest, namely, hydrogen (H2) gas. The third film13that is the TiCN film may be deposited by loading the mixed gas into the chamber in which a set temperature is 800-1100° C., a set pressure is 5-30 kPa and a set time is 20-100 minutes. The above deposition conditions are applicable to cases where the second film12is a TiCN film. For example, a large proportion of N2ingredient in the above reaction gas composition leads to a large N/(C+N), whereas a small proportion of N2ingredient leads to a small N/(C+N).

N contents in the first film11, the second film12and the third film13can be controlled as follows: the first N content>the third N content>the second N content by controlling the reaction gas compositions when depositing the first film11, the second film12and the third film13.

A region including the cutting edge7in the coated tool1thus obtained may be subjected to a polishing process. Consequently, the region including the cutting edge7can be made smooth, so that welding of a workpiece can be reduced to improve fracture resistance of the cutting edge7.

The above manufacturing method is an embodiment of methods for manufacturing the coated tool1. Accordingly, it should be noted that the coated tool1is not limited to ones which are manufactured by the above manufacturing method.

As in a non-limiting embodiment illustrated inFIG.5, a cutting tool101in the non-limiting embodiment of the present disclosure may include a holder102having a length from a first end102ato a second end102band including a pocket103located on a side of the first end102a, and a coated tool1located in the pocket103.FIG.5illustrates the embodiment where the coated tool1includes a through hole and the coated tool1is secured through the through hole to the pocket103with a screw104.

The present disclosure is described in detail below by illustrating examples, however, the present disclosure is not limited to the following examples.

Examples

Firstly, a base was manufactured. Specifically, 6 mass % of metal Co powder having a mean particle diameter of 1.5 μm, 2.0 mass % of TiC (titanium carbide) powder, 0.2 mass % of Cr3C2(chromium carbide) powder were added in their respective proportions to WC powder having a mean particle diameter of 1.2 μm, and these were mixed together. A molded body was obtained by molding a mixture thus obtained into a cutting tool shape (CNMG120408) by press molding. The obtained molded body was then subjected to debinding process, followed by sintering at 1400° C. in a vacuum of 0.5-100 Pa for one hour, thereby manufacturing a base composed of cemented carbide. Thereafter, a side of a rake surface (first surface) of the manufactured base was subjected to cutting edge processing (round honing) by brushing process.

Subsequently, a coating layer (second layer) was deposited on the obtained base by CVD method under deposition conditions presented in Table 1, thereby obtaining a coated tool (cutting insert) presented in Table 2.

All the coated tools presented in Table 2 include the Al2O3layer (first layer) deposited on the base. Deposition conditions and a thickness of the Al2O3layer are as follows.AlCl3gas: 4.0 vol %HCl gas: 1.0 vol %CO2gas: 4.5 vol %H2S gas: 0.3 vol %H2gas: the restTemperature: 1000° C.Pressure: 10 kPaTime: 300 minutesThickness: 5.0 μm

Individual compounds are respectively indicated by chemical symbols in Tables 1 and 2. Thicknesses of the coating films presented in Table 1 and the thickness of the Al2O3layer are values obtained by a cross-section observation using an SEM. In Table 1, a film represented as TiN does not substantially include C, and N/(C+N) is approximately 1. A film represented as TiC does not substantially include N, and N/(C+N) is approximately zero. Additionally, in Table 1, N/(C+N) of the TiCN film in Sample No. 1 is 0.8, N/(C+N) of the TiCN film in each of Samples Nos. 2 to 7 is 0.7, and N/(C+N) of the TiCN film in Sample No. 8 is 0.5.

An appearance color of each of the obtained coated tools was evaluated visually. Results thereof are shown in Table 1. Wear resistance and the presence and absence of welding to the cutting edge were evaluated. A measuring method is described below, and results thereof are shown in Table 2.

Wear Resistance EvaluationMachining method: Turning processWorkpiece: SCM435 round rodCutting speed: 300 m/minFeed rate: 0.3 mm/revDepth of Cut: 1.5 mmMachining state: WetEvaluation item: Determination of a wear amount of the flank surface after cutting out for 20 minutes
Welding Resistance EvaluationMachining method: Turning processWorkpiece: S45C round rodCutting speed: 100 m/minFeed rate: 0.1 mm/revDepth of Cut: 1.0 mmMachining state: WetEvaluation item: Determination of a state of welding to the cutting edge after cutting out for five minutes

Table 2 shows individual amounts of flank wear (Vb) after cutting out for 20 minutes, and individual states of welding to the cutting edge after cutting out for five minutes. In a column of cutting edge welding in Table 2, two parameters of cutting edge welding and chipping are represented by the following evaluation criteria. Regarding the state of welding to the cutting edge, an evaluation result “excellent” means that neither welding nor chipping occurred, an evaluation result “good” means that slight welding was observed though no chipping occurred, an evaluation result “average” means that a larger amount of welding occurred than that in the criterion “good” though no chipping occurred, and an evaluation result “poor” means that welding occurred and chipping due to the welding occurred.

As shown in Table 2, Samples Nos. 3 to 8 respectively corresponding to examples offered better cutting performance than Samples Nos. 1 to 2 respectively corresponding to comparative examples.

DESCRIPTION OF THE REFERENCE NUMERAL