JP2006281361A - Surface coated member and surface coated cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool where a hard coating film including carbonitride titanium film made of a columnar carbonitride titanium is formed on the surface of base material, preventing the occurrence of separation between the base material and the hard coating film even if high-speed and high feed cutting, heavy cutting and intermittent cutting are performed, and lengthening the life. <P>SOLUTION: The titanium nitride film where titanium nitride coarse particles growing from the surface of the base material 2 toward the direction of film thickness are sprinkled in a crystal structure formed of titanium nitride fine particles 11 is formed between the base material 2 and the columnar carbonitride titanium film made of a columnar carbonitride titanium 9, thereby improving the adhesiveness between the base material 3 and the carbonitride titanium film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface covering member and a surface covering cutting tool.

Conventionally, for machining of metals such as cast iron, carbon steel, stainless steel, etc., a compound containing at least one group 4 to 6 metal in the periodic table, particularly a tungsten carbide phase as a main component, is used as an iron group metal. A titanium carbide (TiC) film, a titanium nitride (TiN) film, a charcoal is formed on the surface of a substrate composed of a cemented cemented carbide, a titanium carbonitride-based cermet having a titanium carbonitride phase as a main component and an iron group metal. A surface-coated cutting tool formed by depositing a hard coating film including one or more hard coating films such as a titanium nitride (TiCN) film and an alumina (Al ₂ O ₃ ) film is widely used.

  Of these, titanium-based hard films such as titanium carbide film, titanium nitride film, and titanium carbonitride film are excellent in mechanical strength, toughness, etc., so surface-coated cutting formed by forming a titanium-based hard film on the substrate surface Tools are particularly popular.

  However, the conventional surface-coated cutting tool has insufficient adhesion between the hard coating film and the base material. There is a problem that wear resistance is lowered. In view of such problems, various proposals have been made to improve the adhesion between the titanium-based hard coating film and the substrate.

  For example, a titanium nitride film having a thickness of 5 to 50 nm in which crystal grains have a grain structure and a titanium carbonitride film having a thickness of 1 to 8 μm in which crystal grains have a columnar structure are sequentially formed on the surface of the cemented carbide substrate. A surface-coated cutting tool that is laminated (see Patent Document 1), a cemented carbide base material surface, a titanium carbonitride film having a thickness of 5 to 50 nm having crystal grain structure, and a columnar structure of crystal grains. A surface-coated cutting tool (see Patent Document 2) in which a titanium carbonitride film having a thickness of 1 to 8 μm is sequentially laminated is proposed.

  That is, in Patent Document 1, in order to improve the adhesion between the titanium carbonitride film and the base material, the titanium nitride film made of granular crystals and the carbon made of columnar crystals are interposed between the titanium carbonitride film and the base material. A titanium nitride film is formed. Patent Document 2 describes that a titanium carbonitride film made of granular crystals and a titanium carbonitride film made of columnar crystals are sequentially laminated on the surface of a substrate.

  However, when a hard coating film composed of a uniform structure of granular crystals or columnar crystals described in Patent Documents 1 and 2 is formed on the surface of the base material, the adhesion between the titanium-based hard coating film and the base material is surely Although it is somewhat improved, the hard coating film cannot withstand the impact in intermittent cutting such as high-speed / high-feed milling that suddenly gives a large impact, and the hard coating around the cutting edge and its surroundings. The film is peeled off and the tool life is likely to be shortened. Furthermore, in a titanium carbonitride film having a uniform structure consisting only of columnar crystals, when a crack occurs, the crack tends to extend and often leads to chipping or defects.

  In addition, a titanium carbonitride film made of titanium carbonitride crystal particles having the highest peak intensity on the (311) plane in X-ray diffraction, a titanium carbide film, a titanium nitride film, and carbon It has been proposed to form a hard coating film in which a titanium nitride film, a titanium carbonitride oxide film, an alumina film, and the like are sequentially laminated (see, for example, Patent Document 3). Even when the titanium carbonitride film in contact with the base material as shown in Reference 3 has a (311) plane exhibiting the highest peak intensity in X-ray diffraction, a large impact is instantaneously generated as in the case of strongly interrupted cutting. In such cutting, the adhesiveness is still insufficient, and sudden film peeling often occurs.

  That is, in the conventional techniques such as Patent Documents 1 to 3, the adhesion between the titanium-based hard coating film and the substrate is improved to some extent by controlling the structure and crystal orientation of the titanium nitride film and the titanium carbonitride film. However, it is clear that a sufficiently satisfactory result cannot be obtained for intermittent cutting because of the uniform structure.

JP-A-6-108254 JP-A-6-106402 Japanese Patent Laid-Open No. 5-269606

  An object of the present invention is to provide a surface-coated member and a surface-coated cutting tool that can be processed over a long period of time while suppressing peeling between a base material and a hard coating film even when subjected to severe processing.

  The present invention is a surface coating member in which the surface of a substrate is coated with a hard coating film, and the average particle width in the direction perpendicular to the film thickness direction is 10 nm or less as the lowermost layer of the hard coating film In addition, a titanium nitride coarse particle having a particle width of 20 to 80 nm (20 nm or more and 80 nm or less) in the direction perpendicular to the film thickness is dispersed in the titanium nitride film. This is a surface covering member.

  Here, the second feature of the surface covering member of the present invention is that the titanium nitride coarse particles are vertically long granular crystals that are vertically long in the film thickness direction, and the direction of the long axis length in the film thickness direction is perpendicular to the film thickness direction. The aspect ratio (major axis length / minor axis length) to the minor axis length is 1.5 to 3.0 (1.5 or more and 3.0 or less).

  Furthermore, the 3rd characteristic in the surface coating member of this invention is that the average length of the film thickness direction of the said titanium nitride coarse particle is 25-100 nm (25 nm or more and 100 nm or less).

  Furthermore, the fourth feature of the surface coating member of the present invention is that the hard coating film is formed directly on the titanium nitride film in addition to the titanium nitride film, and the average crystal width in the film thickness direction is the film thickness. A titanium carbonitride film comprising a titanium carbonitride columnar crystal that is larger than the average crystal width in the direction perpendicular to the direction.

  Furthermore, the 5th characteristic in the surface coating member of this invention is that the average crystal width of the direction perpendicular | vertical to the film thickness direction of the said titanium carbonitride columnar crystal is 100-1000 nm (100 nm or more and 1000 nm or less).

  Further, a sixth feature of the surface covering member of the present invention is that the hard coating film is one kind selected from Al, Zr, Hf and Ti in addition to the titanium nitride film and the titanium carbonitride film. It includes one or more coating films selected from carbides, nitrides, carbonitrides, oxides, oxynitrides, carbonates, and carbonitrides of the above elements.

  Furthermore, the seventh feature of the surface covering member of the present invention is that the adhesive force in the scratch test between the base material and the hard coating film is 100 N or more.

  Further, the present invention is a cutting tool for performing a cutting process by applying a cutting edge formed at an intersecting ridge line portion between a rake face and a flank face to a workpiece, and the cutting tool is any one of the aforementioned surfaces. A surface-coated cutting tool comprising a covering member.

  According to the present invention, there is provided a surface covering member in which a hard coating film is deposited on the surface of a substrate. This hard coating film includes a titanium nitride film deposited directly on the substrate surface, and the titanium nitride film is basically composed of titanium nitride fine crystal grains having an average grain width in the direction perpendicular to the film thickness direction of 10 nm or less. The film as the structural unit has a crystal structure in which coarse titanium nitride particles having a particle width in the direction perpendicular to the film thickness direction of 20 to 80 nm are dispersed, and is remarkably excellent in adhesion to the substrate.

  That is, when this titanium nitride film is formed on the substrate surface, the fine crystal particles constituting the basic structure of the titanium nitride film are excellent in impact resistance, are not cracked, and are dispersed in the titanium nitride film. The coarse titanium nitride particles exhibit an anchor effect, and can improve the adhesion between the substrate and the titanium nitride film. Further, even when another hard film is formed on the surface of the titanium nitride film, adhesion with the other hard film can be improved.

  According to the present invention, in the titanium nitride film, the coarse titanium nitride particles are vertically long granular crystals in the film thickness direction, and the major axis length in the film thickness direction and the minor axis length in the direction perpendicular to the film thickness direction are By forming so that the aspect ratio (major axis length / minor axis length) is in the range of 1.5 to 3.0, the anchor effect of the titanium nitride coarse particles is further enhanced, and the titanium nitride film and other materials Adhesion with is further improved.

  According to the present invention, by setting the average length in the film thickness direction of the titanium nitride coarse particles in the titanium nitride film to 25 to 100 nm, in particular, the adhesion between the titanium nitride film and the base material and other hard films is improved. Further improvement.

  According to the present invention, in addition to the titanium nitride film, a titanium carbonitride columnar crystal whose average length in the film thickness direction is larger than the average crystal width in the direction perpendicular to the film thickness direction is arranged immediately above the titanium nitride film. By including the titanium carbonitride film, the hard coating film having high adhesion with the titanium nitride film and having both high wear resistance and chipping resistance can be obtained.

  According to the present invention, the adhesiveness between the titanium nitride film and the titanium carbonitride film is further improved by setting the average crystal width in the direction perpendicular to the film thickness direction of the titanium carbonitride columnar crystal to 100 to 1000 nm. .

  According to the present invention, the hard coating film includes a carbide, nitride, carbonitride of one or more elements selected from Al, Zr, Hf and Ti in addition to the titanium nitride film and the titanium carbonitride film. The hardness and toughness of the hard coating film are further improved by including one or more of the coating film made of an inorganic compound selected from the group consisting of oxides, oxides, oxynitrides, carbonates and carbonitrides. When the surface coating member is used as a surface coating cutting tool, the tool can have a longer life.

  According to the present invention, there is provided a surface covering member having high adhesion between the base material and the hard coating film by having an adhesive force in a scratch test between the base material and the hard coating film of 100 N or more. Obtainable.

  In addition, according to the cutting tool of the present invention, the cutting tool for applying the cutting edge formed at the intersecting ridge line portion between the rake face and the flank face to the work piece is any one of the aforementioned surfaces. A surface-coated cutting tool obtained by comprising a covering member is provided. The surface-coated cutting tool can be suitably used for various metal cutting processes, and even if a severe cutting process such as a high-speed / high-feed cutting process, a heavy cutting process, or an intermittent cutting process is performed, a hard coating film is formed. Peeling between constituent films and peeling between hard coating film and substrate hardly occur, and the surface in contact with the work material has high mechanical strength, excellent grinding performance, and extremely suitable for a long time Can be used for

  The surface covering member of the present invention includes a base material and a hard coating film including a specific titanium nitride film formed immediately above the base material surface.

  The titanium nitride particles constituting the titanium nitride film have an average particle width of 10 nm in a direction perpendicular to the film thickness direction of the titanium nitride film (generally a direction parallel to the film surface, hereinafter simply referred to as “film surface direction” unless otherwise specified). In the following, preferably 5 to 10 nm fine particles are provided as a basic structural unit. When the average particle width exceeds 10 nm, adhesion with other coating films formed on the titanium nitride film is impaired. Moreover, the average particle width (average major axis length) of the titanium nitride fine particles in the film thickness direction is preferably 10 to 200 nm.

  In the titanium nitride film, coarse titanium nitride particles having an average minor axis length of 20 to 80 nm, which is an average particle width in the film surface direction, are dispersed in addition to the fine titanium nitride particles as the basic structural unit. The titanium nitride coarse particles are vertically long granular crystals grown in the film thickness direction of the titanium nitride film from the interface between the base material and the titanium nitride film. In the present invention, the state in which the titanium nitride coarse particles are dispersed in the titanium nitride fine particles refers to a state in which the titanium nitride coarse particles as shown in FIGS. 2 and 3 are independently scattered in the titanium nitride fine particles. .

  When the average minor axis length of the titanium nitride coarse particles is less than 20 nm, the titanium nitride coarse particles do not exhibit a sufficient anchor effect, and the adhesion to the substrate may be lowered. On the other hand, if the average minor axis length exceeds 80 nm, defects are likely to occur between the titanium nitride film and a film formed thereon (hereinafter simply referred to as “upper film”), and the adhesion may be reduced.

  Furthermore, it is desirable that the titanium nitride coarse particles are vertically long granular crystals that are vertically long in the film thickness direction. In particular, the aspect ratio (average major axis length / average minor axis length) of the titanium nitride coarse particles is not particularly limited, but is preferably 1.5 to 3.0. When the aspect ratio is within this range, the anchor effect of the titanium nitride coarse particles is further enhanced, and the adhesion between the titanium nitride film and the base material or the upper film is further improved.

  Moreover, when the titanium nitride coarse particles are vertically long granular crystals, the average major axis length, which is the average particle width in the film thickness direction, is not particularly limited, but is preferably 25 to 100 nm. Within this range, the toughness of the titanium nitride film can be maintained and high adhesion to the substrate and upper film of the titanium nitride film can be maintained.

  The film thickness of the titanium nitride film in the surface covering member of the present invention is not particularly limited and can be appropriately selected from a wide range depending on the material and use of the base material on which the titanium nitride film is formed. Is preferably 30 nm to 200 nm, and more preferably 40 nm to 100 nm.

  Since the titanium nitride film having such a structure has a characteristic that it is firmly adhered to various inorganic materials, the titanium nitride film is applied to the surface of an arbitrary shape made of various inorganic materials by utilizing this characteristic. Thus, coating films having various configurations can be formed. Base materials having high adhesion to the titanium nitride film include titanium carbonitride-based cermet, alumina, tungsten carbide-based cemented carbide, zirconium oxide, zirconium carbide, zirconium carbonitride, silicon nitride, silicon carbide, cubic boron nitride ( cBN) and polycrystalline diamond (PCD). Among these, it is desirable that the cemented carbide is mainly composed of a tungsten carbide phase in terms of adhesion to the hard coating film.

  In addition to the titanium nitride film, the hard coating film in the surface coating member of the present invention is formed on the surface of the titanium nitride film, and has a structure in which titanium carbonitride columnar crystals that are long in the film thickness direction are arranged in a line. A titanium nitride film may be included.

  In the titanium carbonitride film, the average minor axis length, which is the average particle width in the film surface direction of the titanium carbonitride columnar crystal, is preferably 100 to 1000 nm. If the average minor axis length of the titanium carbonitride columnar crystals is within this range, the adhesion with the titanium nitride layer does not decrease, and the titanium carbonitride particles become coarse to reduce the hardness and wear resistance. Can be prevented. Therefore, the above range is excellent in balance between hardness and fracture toughness.

  The thickness of the titanium carbonitride film depends on various conditions such as the thickness of the titanium nitride film to be laminated, the material of the base material that covers the hard film, and the use of the article obtained by coating the hard surface on the surface of the base material. Although it can be suitably selected from a wide range, it is preferably 2 to 20 μm in view of having both excellent fracture resistance and wear resistance, for example.

  In addition to the above titanium nitride film and titanium carbonitride film, the hard coating film in the surface coating member of the present invention is particularly an oxide or oxynitride of one or more elements selected from Al, Zr, Hf, and Cr And a coating film made of an inorganic compound or a metal compound selected from titanium carbide, nitride, oxide, carbonate, oxynitride and carbonitride has wear resistance, fracture resistance, etc. Desirable because of its excellent mechanical properties. Specific examples of such other coating films include other titanium nitride films, titanium carbide films, other titanium carbonitride films, titanium oxynitride films, and aluminum oxide (alumina) films. The other titanium nitride film referred to here may be the titanium nitride film of the present invention, or may be a general film other than the titanium nitride film of the present invention.

  The base material in the surface covering member of the present invention can be produced by, for example, forming a raw material mixture into a desired shape and baking it according to a known method.

  The raw material of the base material is preferably a material obtained by appropriately adding metal powder, carbon powder or the like to an inorganic powder such as metal carbide, nitride, carbonitride, oxide or the like that can form the base material by firing. If necessary, an appropriate amount of a binder is further added to the raw material mixture and mixed. For forming the raw material mixture, any of general methods for forming inorganic powders such as press molding, cast molding, extrusion molding, and cold isostatic pressing can be used, and the raw material mixture is molded into a desired tool shape. A base material is obtained by baking this molded product. Among the substrates, those containing a hard alloy such as a tungsten carbide base hard alloy, a cermet hard alloy, a diamond sintered body, and a cubic boron nitride sintered body are preferable. The surface of the obtained base material is subjected to polishing processing, honing processing of the cutting edge portion, or the like as necessary. If necessary, chemical processing such as mechanical processing such as blasting, lapping, buffing, polishing, barreling, grinding, etching with acid and alkali, etc. to provide recesses on the surface of the cutting edge and rake face of the substrate Processing that combines processing, mechanical processing, and chemical processing is performed. At that time, the processing is controlled so 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 0.5 to 3.0 μm. preferable.

  In forming the hard coating film on the surface of the substrate, for example, a general thin film forming method such as a physical vapor deposition method, a vapor deposition (CVD) method, a plasma CVD method, or a sputtering method can be used.

  Hereinafter, an example of the method for forming the hard coating film of the present invention using the vapor phase growth method will be described. This forming method includes a pretreatment step, a titanium nitride film (underlying film) forming step, a titanium carbonitride film forming step, an α-alumina film forming step, and a surface layer forming step. These steps are all carried out in a sealed reaction vessel having a source gas supply port such as a reaction chamber.

  According to the present invention, pretreatment is first performed before forming a hard film. Specifically, the pretreatment step is performed by supplying a mixed gas containing a titanium source gas and hydrogen gas to the substrate under heating and pressurization. By this pretreatment, a recess is formed on the surface of the substrate, and the titanium nitride film of the present invention can be controlled to the above-described configuration.

  Specific examples of the composition of the mixed gas used in the pretreatment step include, for example, a composition in which titanium chloride gas is 0.5 to 10% by volume and the balance is hydrogen gas. The supply amount of the mixed gas may be appropriately determined according to the capacity of the film forming apparatus and the surface area of the substrate to be processed, and the same applies to the other processes described below. The pretreatment step is performed at a temperature of 800 to 880 ° C. and a pressure of 10 to 30 kPa, and is completed in about 20 to 60 minutes.

  Specific examples of the composition of the mixed gas include a composition in which titanium chloride gas is 0.5 to 5% by volume, nitrogen gas is 15 to 40% by volume, and the balance is hydrogen gas. The titanium nitride film forming step is performed, for example, at a temperature of 800 to 880 ° C. and a pressure of 10 to 30 kPa, and is formed for 10 to 20 minutes. By the pretreatment process and the film forming process, a titanium nitride film in which coarse titanium nitride particles are scattered in a crystal region composed of fine titanium nitride particles is formed. If the film forming conditions are out of the above range, it becomes difficult to control the composition of the titanium nitride film.

The titanium carbonitride film forming step is performed by supplying a mixed gas containing a titanium source gas, a nitrogen source gas, a carbon source gas, and a carrier gas to the surface of the titanium nitride film under heating and pressure. Examples of the carbon source gas include acetonitrile gas, methane gas, carbon dioxide gas, and the like. Acetonitrile gas is also a nitrogen source gas. Specific examples of the composition of the mixed gas include, for example, titanium chloride gas 0.1 to 10% by volume, nitrogen gas 0 to 60% by volume, acetonitrile gas 0.1 to 2.0% by volume, and the balance being hydrogen gas. Is mentioned. In this composition, the acetonitrile gas ratio is preferably adjusted to 0.1 to 0.4% by volume. As a result, columnar crystals (stripe crystals) of titanium carbonitride are reliably formed, the titanium carbonitride columnar crystals are oriented in the film thickness direction, and a titanium carbonitride film excellent in various mechanical strengths is formed. In the mixed gas composition described above, the acetonitrile gas ratio VA is adjusted to 0.3 to 3% by volume, and the ratio of the hydrogen gas ratio V _{H as the} carrier gas to the acetonitrile gas ratio V _A (V _A / V _H ) is controlled to be 0.03 or less, fine nucleation occurs and the average particle width of the titanium carbonitride film can be controlled within the predetermined range described above. Adhesion with the titanium nitride film can be further improved. When using the mixed gas of the said composition, a titanium carbonitride film formation process is implemented under the temperature of 780-880 degreeC, and the pressure of 5-25 kPa, and is complete | finished in about 3-20 minutes. The film formation temperature and the film formation pressure can be appropriately changed according to the composition of the mixed gas supplied to the substrate surface.

  Moreover, in this process, in order to form the titanium carbonitride layer which consists of the columnar particle | grains which have the predetermined | prescribed particle width mentioned above, it is desirable to make film-forming temperature into said 780-880 degreeC.

  In addition, when another hard film is formed on the titanium nitride and titanium carbonitride films described above, for example, when a titanium carbonitride oxide film is formed as an intermediate layer, another mixed gas that can be used in the film forming process is different. Examples of the composition include 0.1 to 3% by volume of titanium chloride gas, 0.01 to 5% by volume of carbon dioxide gas, 0.1 to 10% by volume of methane gas, 1 to 15% by volume of nitrogen gas, and hydrogen gas as the balance. It is done. When this mixed gas is used, the titanium carbonitride oxide film forming step is performed at a temperature of 950 to 1100 ° C. and under a pressure of 5 to 30 kPa, and is completed in about 2 to 30 minutes.

  The alumina film forming step is performed, for example, following the formation of the titanium nitride film, titanium carbonitride film and titanium carbonitride oxide on the surface of the base material. Hydrogen chloride gas 0.5 to 3.5% by volume, carbon dioxide gas 0.01 to 5% by volume, hydrogen sulfide gas 0 to 0.01% by volume, and a mixture gas with the balance being hydrogen gas are supplied. The The alumina film forming step is performed, for example, at a temperature of 950 to 1100 ° C. and a pressure of 5 to 10 kPa, and is completed in about 20 to 800 minutes.

  Further, if desired, a titanium nitride film is formed as the outermost layer of the hard coating film. Such an outermost layer titanium nitride film supplies a mixed gas of 0.1 to 10% by volume of titanium chloride gas, 3 to 60% by volume of nitrogen gas, and the balance being hydrogen gas under the heating temperature, time and pressure described later. Can be formed. The titanium nitride film formed as the outermost layer may be the titanium nitride film of the present invention in which coarse particles are interspersed with the fine particles described above, or has a conventionally known uniform structure. A titanium nitride film may be used. The formation of the titanium nitride film is performed, for example, at a temperature of 800 to 1100 ° C. and a pressure of 50 to 85 kPa, and is completed in about 10 to 100 minutes.

  Thus, as an example, the substrate surface includes a hard material including a titanium nitride film, a titanium carbonitride film, a titanium carbonitride oxide film, an alumina film, and a titanium nitride film of the present invention or a general titanium nitride film. The surface covering member of the present invention in which the covering film is formed is obtained.

  In addition, microscopes, such as a scanning electron microscope (SEM) and a transmission electron microscope (TEM), can be used for observation of the cross section of the hard coating film in the surface coating member of the present invention. In particular, according to a transmission electron microscope (TEM), a minute region can be observed accurately and clearly.

  In order to manufacture the surface-coated cutting tool of the present invention, in the manufacture of the surface-coated member described above, a substrate having a cutting tool shape may be used and manufactured through the same steps as described above. In the surface-coated cutting tool obtained, if necessary, the residual stress remaining in the hard coating film is released by polishing the surface, at least the cutting edge, and the resistance of the surface-coated cutting tool of the present invention is reduced. The deficiency can be further improved.

  In the surface-coated cutting tool of the present invention, it is preferable that the above-described configuration is reliably controlled and the adhesion force in the scratch test between the base material and the hard coating film is 100 N or more. By controlling to this adhesion force, peeling of the hard coating film due to sudden impact during cutting is further prevented.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
(Examples 1-4 and Comparative Examples 1-3)
Metal cobalt powder with an average particle size of 1.2 μm is 8.0% by weight, tantalum carbide with an average particle size of 2.0 μm is 0.7% by weight, titanium carbide is 0.6% by weight, niobium carbide is 0.4% by weight, and the balance is average 2 parts by weight of a binder was added to 100 parts by weight of a mixed powder made of tungsten carbide having a particle size of 1.5 μm, and further mixed. After this was formed into a cutting tool shape (CNMG12041) by press molding, a binder removal treatment was performed. This was put into a firing furnace where the pressure in the furnace was maintained at 0.01 Pa, the temperature rising rate at 1000 ° C. or higher was set to 3 ° C./min, the temperature was raised to 1500 ° C. Time firing was performed to produce a tungsten carbide based hard alloy substrate.

  The surface of Examples 1 to 4 and Comparative Examples 1 to 3 is formed on the surface of this tungsten carbide base hard alloy substrate by chemical vapor deposition under the conditions shown in Table 1 to form hard coating films shown in Table 2. A coated cutting tool was produced. In the hard coating film shown in Table 2, the first layer is made of a titanium nitride film. The second to fourth layers are made of a titanium nitride film. The fifth layer is made of a titanium carbonitride oxide film or a titanium nitride oxide film. The sixth layer is made of an alumina film. The seventh layer is made of an outermost titanium nitride film. In Table 2, “particle shape a / b” in the first layer indicates the aspect ratio of the titanium nitride coarse particles.

(State of hard coating film)
A part of the base material and the hard coating film were cut out as thin films from the surface-coated cutting tools of Examples 1 to 4 and Comparative Examples 1 to 3 by an ion milling method. The sample thin film was photographed with a high-resolution transmission electron microscope (HR-TEM), and a high-angle annular dark field was photographed, and the observation position of the base material-titanium nitride layer-titanium carbonitride layer was determined. Observation was carried out at three places according to the magnification of. 1 to 3 show electron micrographs of a hard coating film formed on the surface of the surface-coated cutting tool of the present invention. FIG. 1 is a photomicrograph of the boundary cross section between the substrate 2 and the hard coating film 3 in the surface cutting tool of Example 1. FIG. 2 is an enlarged photomicrograph showing the boundary cross section shown in FIG. FIG. 3 is a photomicrograph showing a further enlarged portion A of the boundary cross section shown in FIG. Note that, in FIGS. 1-3, the direction of the dotted line _L 1 _{~ 3} is a membrane surface direction. In FIG. 1, a width a between two opposing arrows is a particle width in the film surface direction of columnar titanium carbonitride. In FIG. 3, a width b between two opposing arrows indicates a particle width in the film surface direction of the titanium nitride coarse particles 10. Incidentally, the width b is subtracted dotted L ₃ as shown in FIG. 3 at a height position where the line segment is maximized when lined in a direction perpendicular to the film thickness of the titanium carbonitride coarse crystals, The width b on the line segment was defined as the crystal width of the titanium nitride coarse particles. In the table, the crystal width of each titanium nitride coarse particle was calculated by setting so that 10 or more titanium nitride coarse particles existed in one field of view of the photograph, and expressed as an average value thereof.

  1-3, the hard coating film 3 formed on the surface of the substrate 2 includes a titanium nitride film 4 in which the titanium nitride coarse particles 10 are scattered in the crystal structure of the titanium nitride fine particles 11, and a columnar carbonitriding. It can be seen that the titanium particles 9 include the columnar titanium carbonitride film 5 oriented in the film thickness direction and the alumina film 6.

  Moreover, based on FIGS. 1-3, the titanium nitride film | membrane formed in the base material 2 surface grows in the film thickness direction from the base material 2 surface in the titanium nitride fine particle area | region with an average particle width of 10 nm or less. It can be seen that the structure is dotted with equiaxed or vertically elongated coarse titanium nitride particles 10 having a width of 20 to 100 nm.

Here, in the cross-sectional photograph as shown in FIG. 1, the average crystal width is obtained by drawing a dotted line L ₁ as shown in FIG. 1 at the height position in the middle portion of the thickness of the columnar titanium carbonitride film 5. The number of grain boundaries crossing the minute was measured, and the value converted into the crystal width of the titanium carbonitride particles was calculated. The average value of the crystal widths calculated for each of the five photographs was calculated as the average crystal width. The results are shown in Table 2.

(Scratch strength)
The obtained tool was subjected to a scratch test under the following conditions on the flank of the tool, and scratches were observed to measure the delamination state and the load at which the coating film began to peel from the substrate.
Apparatus: CSEM-REVETEST manufactured by Nanotech
[Measurement condition]
Table speed: 0.17 mm / sec
Load speed: 100 N / min
Scratch distance: 5mm
Indenter: Conical diamond indenter (diamond contactor, trade name: N2-1487, manufactured by Tokyo Diamond Tool Mfg. Co., Ltd.)
Curvature radius: 0.2mm
Ridge angle: 120 °

(Abrasion test)
Using the cutting tools of Examples 1 to 4 and Comparative Examples 1 to 3, FCD700 (work material) was cut for 30 minutes under the following conditions, and the flank wear amount (mm) and the tip wear amount (mm) were measured. .
Work material: FCD700
Tool shape: CNMG12041
Cutting speed: 200 m / min Feeding speed: 0.3 mm / rev
Cutting depth: 2.0mm
Others: Use aqueous cutting fluid

(Intermittent test)
Furthermore, an intermittent test was conducted for each of the 10 cutting tools of Examples 1 to 4 and Comparative Examples 1 to 3 using a grooved steel material under the following cutting conditions, and the average value of the number of impacts at the time of chipping was determined. Further, when the number of impacts reached 1000 in the intermittent test, the state of the cutting edge was observed with a microscope to confirm the presence or absence of peeling of the hard coating film.
Work material: FCD700 with 4 grooves Tool shape: CNMG120212
Cutting speed: 450 m / min Feeding speed: 0.45 mm / rev
Cutting depth: 2.0mm
Other: Table 1 shows the results of using the aqueous cutting fluid.

  From Table 2, the surface cutting tool of the present invention has very high adhesion between the base material and the hard coating film, excellent wear resistance and chipping resistance, and the hard coating film does not peel even after repeated use. It is clear that this is a long-life cutting tool.

It is a microscope picture of the boundary cross section of the base material and hard coating film in the surface coating cutting tool of this invention. It is a microscope picture which expands and shows the boundary cross section of the base material and hard coating film in the surface coating cutting tool of this invention. It is a microscope picture which further expands and shows the A section in FIG. 2 which shows the boundary cross section of the base material and hard coating film in the surface coating cutting tool of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tool 2 Base material 3 Hard coating film 4 Titanium nitride film 5 Columnar titanium carbonitride film 6 Alumina film 9 Columnar titanium nitride particle 10 Granular titanium nitride particle 11 Columnar titanium nitride particle

Claims (8)

  A surface covering member in which a hard coating film is coated on the surface of a substrate, and a titanium nitride fine particle having an average particle width of 10 nm or less in the direction perpendicular to the film thickness direction as the lowermost layer of the hard coating film A surface covering member comprising a titanium nitride film made of particles, and coarse titanium nitride particles having a particle width of 20 to 80 nm in a direction perpendicular to the film thickness direction dispersed in the titanium nitride film .   The coarse titanium nitride particles are vertically long granular crystals in the film thickness direction, and the aspect ratio (major axis length / minor axis length) of the major axis length in the film thickness direction and the minor axis length in the direction perpendicular to the film thickness direction. The surface covering member according to claim 1, wherein the surface covering member is 1.5 to 3.0.   The surface covering member according to claim 1 or 2, wherein an average length of the titanium nitride coarse particles in a film thickness direction is 25 to 100 nm.   In addition to the titanium nitride film, the hard coating film is formed directly on the titanium nitride film, and has a columnar shape of titanium carbonitride in which the average length in the film thickness direction is larger than the average crystal width in the direction perpendicular to the film thickness direction The surface covering member according to any one of claims 1 to 3, further comprising a titanium carbonitride film in which crystals are arranged.   The surface covering member according to claim 4, wherein an average crystal width in a direction perpendicular to the film thickness direction of the titanium carbonitride columnar crystal is 100 to 1000 nm.   In addition to the titanium nitride film and the titanium carbonitride film, the hard coating film further includes a carbide, nitride, carbonitride, oxide of one or more elements selected from aluminum, zirconium, hafnium, and titanium. The surface covering member according to claim 4, comprising one or more coating films selected from oxynitrides, carbonates, and carbonitrides.   The surface covering member according to claim 1, wherein an adhesion force in a scratch test between the base material and the hard coating film is 100 N or more. A cutting tool for performing cutting by applying a cutting edge formed at a crossing ridge line portion between a rake face and a flank to an object to be cut, comprising the surface covering member according to any one of claims 1 to 7. A surface-coated cutting tool characterized by