JP2006225703A - Hard film, stacked type hard film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard film having excellent hardness and oxidation resistance and formed on cutting tools and fixtures such as a forging die and a punch, and to provide a method for producing the same. <P>SOLUTION: The hard film is composed of [(Nb<SB>1-d</SB>, Ta<SB>d</SB>)<SB>a</SB>Al<SB>1-a</SB>](C<SB>1-x</SB>N<SB>x</SB>), or [(Nb<SB>1-d'</SB>Ta<SB>d</SB>)<SB>a</SB>(Al<SB>1-a</SB>Si<SB>b</SB>B<SB>c</SB>)](C<SB>1-x</SB>N<SB>x</SB>); wherein, 0.4≤a≤0.6, 0<b+c≤0.15, 0≤d≤1, and 0.4≤X≤1 (in the formula, a, b, c, d and X are mutually independently, an atomic ratio; and, regarding b and c, either may be zero, but both of them are not zero). The hard film is formed by repeating a stage where a film is formed by a cathode discharge type arc ion plating process and a stage where a film is formed by a sputtering process. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hard coating formed on a cutting tool such as a tip, a drill, or an end mill, or a jig such as a forging die or a punch, and a method for manufacturing the same.

Conventionally, in a cutting tool, a hard film such as TiN, TiCN, or TiAlN is formed on a base material such as high-speed steel, cemented carbide, or cermet in order to increase wear resistance. In particular, TiAlN has high wear resistance, and is therefore suitably used in high-hardness material cutting tools such as high-speed cutting tools and hardened steel. Further, with the recent increase in hardness and cutting speed of workpieces, development of hard coatings with better wear resistance has been demanded. Therefore, the present inventors have found that by using TiCrAlN instead of TiAlN, the hardness and oxidation resistance of the coating can be improved by increasing the Al concentration while maintaining the crystal structure of AlN in a high hardness cubic structure. (Patent document 1).
JP 2003-71610 A

  In recent years, the tendency to cut high-speed tool steel (such as SKD11) at a high speed using a cutting tool is higher than that by electric discharge machining, and the development of a hard coating with better oxidation resistance is required. It has been.

  The present invention has been made paying attention to these problems, and is to provide a hard film excellent in hardness and oxidation resistance and a method for producing the same.

The hard coating of the present invention that has solved the above problems is
(1)
[(Nb _1-d , Ta _d ) _a Al _1-a ] (C _1-X N _X )
0.4 ≦ a ≦ 0.6,
0 ≦ d ≦ 1,
0.4 ≦ X ≦ 1,
(Wherein a, d and X independently represent an atomic ratio),
(2)
A hard coating composed of [(Nb _1-d , Ta _d ) _a (Al _1-abc , Si _b , B _c ) _1-a ] (C _1-X N _X ),
0.4 ≦ a ≦ 0.6,
0 <b + c ≦ 0.15,
0 ≦ d ≦ 1,
0.4 ≦ X ≦ 1,
(In the formula, a, b, c, d and X each independently represent an atomic ratio: b and c may be either 0, but neither is 0)
It is characterized by being.

The hard coating of the present invention may be a laminated type,
A layer satisfying the composition of the above (1) or B layer satisfying the composition of the above (2);
[(Nb _{1 -D} , Ta _D ) _A (Al _{1 -ABC} , Si _B , B _C ) _{1 -A} ] (C _{1 -X} N _X )
0.2 ≦ A ≦ 0.5,
0.15 <B + C ≦ 0.5,
0 ≦ D ≦ 1,
0.4 ≦ X ≦ 1
(In the formula, A, B, C, D and X each independently represent an atomic ratio: B and C may be one of B and C, but not both of them)
C layers consisting of are laminated alternately. The thickness of the A layer or the B layer is preferably 5 nm or more, and the thickness of the C layer is preferably 1 nm or more.

  The hard coating is excellent in both hardness and oxidation resistance.

The present invention comprises [(Nb _1-d , Ta _d ) _a Al _1-a ], 0.4 ≦ a ≦ 0.6, 0 ≦ d ≦ 1 (wherein a and d are independent of each other). Or ([indicating atomic ratio)] or [(Nb _{1 -d} , Ta _d ) _a (Al _{1 -abc} , Si _b , B _c ) _{1 -a} ], and 0.4 ≦ a ≦ 0. 6, 0 <b + c ≦ 0.15, 0 ≦ d ≦ 1 (wherein, a, b, c and d independently represent an atomic ratio: b and c may be either 0 or 0 Good, but both cannot be 0)
In a N-containing gas or a mixed gas containing C and N, a hard film obtained by coating with a cathode discharge arc ion plating method,
[(Nb _1-d , Ta _d ) _a Al _1-a ], 0.4 ≦ a ≦ 0.6, 0 ≦ d ≦ 1
(Wherein, a and d independently represent an atomic ratio) or [(Nb _{1 -d} , Ta _d ) _a (Al _{1 -abc} , Si _b , B _c ) _{1 -a} ] 0.4 ≦ a ≦ 0.6, 0 <b + c ≦ 0.15, 0 ≦ d ≦ 1 (wherein a, b, c and d independently represent an atomic ratio: And c may be zero, but neither may be zero)
Forming a film by a cathode discharge arc ion plating method in an N-containing gas or a mixed gas containing C and N;
[(Nb _1-D , Ta _D ) _A (Al _1-ABC , Si _B , B _C ) _1-A ], 0.2 ≦ A ≦ 0.5, 0.15 <B + C ≦ 0.5, 0 ≦ D ≦ 1
(Wherein, A, B, C and D are independently of each other and indicate an atomic ratio: B and C may be one, but not both) Use
A multilayer hard film obtained by repeating a process of forming a film by a sputtering method in an N-containing gas or a mixed gas containing C and N is also included.

The laminated hard coating is, for example,
Using a film forming apparatus equipped with both an arc evaporation source and a sputtering evaporation source, both evaporation sources are discharged at the same time, and the object to be processed is moved in front of the arc evaporation source. It can be manufactured by repeatedly performing the step of forming the layer or the B layer and the step of moving the workpiece to the front of the sputtering evaporation source and forming the C layer by the sputtering method.

  The hard coating of the present invention is extremely excellent in hardness and oxidation resistance because Al in the Al nitride or Al carbonitride-based hard coating is replaced with an appropriate amount of Nb and / or Ta.

  In order to search for a hard film having higher hardness and oxidation resistance than TiAlN and TiAlCN (hereinafter sometimes collectively referred to as TiAl-based hard film), the present inventors have formed various hard films and have a crystal structure. And the hardness, oxidation resistance, and durability with cutting tools were evaluated. As a result, instead of Ti, nitride or carbonitride in which Nb and / or Ta is combined with Al [NbAlCN, TaAlCN, NbTaAlCN; and a compound in which the (CN) portion is (N) (hereinafter referred to as Nb / TaAl system) Has been found to be extremely excellent in terms of hardness and oxidation resistance (oxidation start temperature), leading to the present invention.

  More specifically, the reason why the TiAl-based hard coating exhibits high oxidation resistance is that Al is preferentially oxidized in a high-temperature oxidizing atmosphere, and a highly protective Al oxide coating is formed on the outermost surface. . However, in the TiAl-based hard film, when the temperature exceeds a certain temperature, Ti oxide having a lower protection than the Al oxide film is preferentially formed, and the oxidation resistance is drastically lowered. Therefore, the present inventors considered that the Nb · TaAl hard coating containing no Ti has better oxidation resistance than the TiAl hard coating. As a result, Ta oxide and Nb oxide are amorphous up to a relatively high temperature (about 1000 ° C.) and have no grain boundary. Therefore, the protective property is higher than that of Ti oxide. It was superior in oxidation resistance than TiAl hard coating.

  Regarding the hardness, the TiAl-based hard film has high hardness because cubic AlN (lattice constant: 4.12) in a metastable state is dissolved in the lattice of TiN (lattice constant: 4.24Å). it is conceivable that. On the other hand, in TaN and NbN, the lattice constants are 4.339 and 4.389, and the difference in lattice constant with respect to cubic AlN is larger than that of the TiAl-based hard film, and the strain between the lattices can be increased. Can be increased.

The Nb · TaAl hard coating can be expressed as [(Nb _1-d , Ta _d ) _a Al _1-a ] (C _1-X N _X ). In the formula, “a”, “d” and “X” independently represent an atomic ratio. The “a” is 0.4 or more and 0.6 or less. If the value of “a” is too small, the proportion of Al becomes too high, and the film has a relatively soft hexagonal crystal structure (also called wurtzite type), and the hardness decreases. A preferable value of “a” is 0.4 or more, preferably 0.45 or more, and more preferably 0.5 or more. The hardness increases as the value of “a” increases. However, if the value of “a” becomes too large, the amount of strain accumulated due to the combined use of Al and Nb and / or Ta decreases, so the hardness decreases. Therefore, the value of “a” is 0.6 or less, preferably 0.55 or less. The value of “d” may be 1 (that is, a TaAl hard film) or may be 0 (that is, an NbAl hard film). Further, it may be a hard film containing Ta and Nb.

  The value of “X” may be 1 (that is, the hard film is a nitride), but the hardness of the film improves as the value of X decreases (that is, the amount of C increases). However, if the value of X is too small, an unstable AlC compound is likely to be formed. Therefore, the value of X is 0.4 or more, preferably 0.6 or more, more preferably 0.7 or more.

Si and / or B may be further added to the Nb · TaAl-based hard coating, and this added hard coating (hereinafter sometimes referred to as a Si · B-added Nb · TaAl-based hard coating). can expressed as _{[(Nb 1-d, Ta} d) a (Al 1-abc, Si b, B c) 1-a] (C 1-X N X). Note that [(Nb _{1 -d} , Ta _d ) _a (Al _{1 -abc} , Si _b , B _c ) _{1 -a} ] (C _{1 -X} N _X ) is not limited to the case where B forms carbonitride. , B has a comprehensive meaning in combination with the case of forming a boride with Nb and / or Ta, Al, Si or the like. In the formula, “a”, “b”, “c”, “d” and “X” independently represent an atomic ratio. By adding Si and / or B, Si—N bonds and BN bonds are formed at the crystal grain boundaries, and the growth of crystal grains can be suppressed, and the crystal grains of the Nb / TaAl hard coating can be refined. The hardness could be further improved. Further, although details are not clear, oxidation resistance can be improved. The additional amount (b + c) of Si or B is more than 0, preferably 0.01 or more, more preferably 0.03 or more, and particularly preferably 0.05 or more. Both Si and B may be added, or only one of them may be added. Therefore, one of “b” and “c” may be zero. However, since Si is superior to B in terms of oxidation resistance, it is recommended to add both Si and B or only Si when importance is attached to oxidation resistance. On the other hand, since B forms a BN bond having a lubricating action, it is recommended to add both Si and B, or just B, when importance is also placed on improving lubricity. As the value of “b + c” increases, the hardness and oxidation resistance improve. However, if the value of “b + c” becomes too large, the film becomes difficult to take a cubic structure, and it changes to a hexagonal type or becomes amorphous, resulting in a decrease in hardness. A preferable value of “b + c” is 0.15 or less.

  The hard coating of the present invention may have a crystal structure in which cubic and hexagonal crystals are mixed as long as desired hardness and oxidation resistance can be satisfied, but is preferably a substantially cubic NaCl type. The crystal structure of is shown. The higher the proportion of cubic crystals, the higher the hardness of the film.

  The above-mentioned hard coatings with a single layer structure (Nb / TaAl hard coating and Si / B additional type Nb / TaAl hard coating) are resistant to oxidation by forming a hard coating with higher oxidation resistance on one or both sides. The property can be further improved. However, depending on the hard film to be formed, the adhesion between the films is sufficient, and peeling may occur. Therefore, the inventors of the present invention have a layer satisfying the composition of the Nb · TaAl hard coating (also referred to as A layer in this specification) or a layer satisfying the composition of the Si · B additional type Nb · TaAl hard coating ( In this specification, it is also referred to as B layer), and the ratio of Nb and Ta and the ratio of Si and / or B are increased compared to the above-described Si / B additional type Nb / TaAl hard coating. By forming the hard film (also referred to as C layer in this specification) by alternately laminating it, a hard film (hereinafter sometimes referred to as a laminated hard film) with even better oxidation resistance is obtained. I found out that Since the composition of the C layer of the laminated hard coating is close to the composition of the A layer and the B layer, problems such as the above-described peeling are unlikely to occur.

The C layer can be expressed as [(Nb _{1 -D} , Ta _D ) _A (Al _{1 -ABC} , Si _B , B _C ) _1-A ] (C _{1 -X} N _X ). In the formula, A, B, C, D and X independently represent an atomic ratio. The C layer is required to have sufficient oxidation resistance and not excessively reduce the hardness of the laminated hard film. Therefore, the values of “A”, “B”, “C”, “D”, and “X” may be appropriately selected according to the characteristics of the A layer and the B layer. In general, the “A” is 0.2 or more (preferably 0.25 or more, more preferably 0.3 or more), and is preferably 0.5 or less (preferably 0.45 or less). One of the values of “B” and “C” may be 0, but both of them are not 0, and the value of “B + C” is 0.15 or more (preferably 0.2 or more, Preferably it is 0.25 or more) and is 0.5 or less (preferably 0.4 or less, more preferably 0.3 or less). The value of “X” is 0.4 or more (preferably 0.6 or more, more preferably 0.7 or more), and preferably 1 or less.

  In addition, since the C layer does not require hardness as much as the above-described hard coating and the coating of the A layer, as long as the desired hardness and oxidation resistance can be satisfied, the C layer may have a crystal structure in which cubic crystals and hexagonal crystals are mixed. It may be made of amorphous material.

  In addition, the amorphous refers to those having a crystal grain size of 1 nm or less. Specifically, in the above X-ray diffraction, 2θ = 37.78 °, 43.9 °, 63.8 °, Meaning those that do not show clear peaks at around 32 ° to 33 °, around 48 ° to 50 °, and around 57 ° to 58 °.

  The thickness of the laminated hard film is thicker when the characteristics of the A layer and the B layer (for example, hardness) are emphasized, and when the characteristics of the C layer (for example, oxidation resistance) are emphasized. What is necessary is just to thicken C layer. In particular, the strength and oxidation resistance of the laminated hard coating can be further improved by setting the C layer to about ½ or less of the thickness of the A or B layer. The thickness of the A or B layer is 5 nm or more (preferably 10 nm or more, more preferably 25 nm or more), and the thickness of the C layer is 1 nm or more (preferably 2 nm or more, more preferably 3 nm or more). The strength and oxidation resistance of the laminated hard coating can be further improved. However, if the A layer, B and / or C layer is too thick, the effect of forming a laminate cannot be obtained. Therefore, the A or B layer needs to be 100 nm or less (preferably 50 nm or less), and the C layer needs to be 10 nm or less (preferably 5 nm or less).

  Since the hard coating (including laminated hard coating) is extremely excellent in hardness and oxidation resistance, it is applied to the surface of an iron-based substrate such as high-speed tool steel (SKH51, SKD11, SKD61, etc.) or cemented carbide. By forming, a cutting tool and a jig having excellent hardness and oxidation resistance can be obtained.

  The hard coating (including the laminated hard coating) can be produced using a known method such as physical vapor deposition (PVD method) or chemical vapor deposition (CVD method). From the standpoint of adhesion and the like, it is preferable to manufacture using a PVD method. Specifically, a sputtering method, a vacuum deposition method, an ion plating method, and the like can be given. Among them, the target used in the film formation of the hard film (including the laminated hard film) of the present invention includes Nb and Ta simultaneously with Al, and the melting point of Al and Nb or Ta is greatly different. In the film formation method by the hollow cathode evaporation method, it is difficult to control the evaporation amount of each element in the target. Therefore, it is preferable to employ a sputtering method or an ion plating method in which the evaporation (vaporization) rate of elements in the target does not greatly depend on the melting point. Furthermore, it is preferable to employ an ion plating method (particularly, an arc ion plating method) from the viewpoint of a high film formation rate.

For example, a hard film having a single layer structure consists of [(Nb _1-d , Ta _d ) _a Al _1-a ], and 0.4 ≦ a ≦ 0.6, 0 ≦ d ≦ 1 (where a, c And d are each independently a target) or [(Nb _{1 -d} , Ta _d ) _a (Al _{1 -abc} , Si _b , B _c ) _{1 -a} ]. 4 ≦ a ≦ 0.6, 0 <b + c ≦ 0.15, 0 ≦ d ≦ 1 (wherein, a, b, c and d independently represent an atomic ratio: Can be 0, but both cannot be 0)
It can be produced using a cathode discharge arc ion plating method in an N-containing gas or a mixed gas containing C and N.

However, since the target for forming the C layer of the laminated hard coating has a higher Si and / or B content than the target for forming the A layer or the B layer, the strength of the target is weak. Therefore, if the C layer is formed by the cathode discharge arc ion plating method, the target may be damaged during arc discharge. Furthermore, the C layer needs to be formed relatively thin, and it is difficult to control the thickness because the deposition rate is extremely high in the cathode discharge arc ion plating method. For the above reasons, it is preferable to use a sputtering method for forming the C layer. Specifically, it consists of [(Nb _{1 -D} , Ta _D ) _A (Al ₁ -ABC, Si _B , B _C ) _1-A ], and 0.5 ≦ A ≦ 0.8, 0.15 ≦ B + C ≦ 0.5, 0 ≦ D ≦ 1 (in the formula, A, B and C independently represent an atomic ratio: B and C may be either 0, but both are 0) Use a target that is
In the N-containing gas or the mixed gas containing C and N, it is preferable to form the C layer using a cathode discharge arc ion plating method.

  As an apparatus for producing the laminated hard film, an apparatus described in Japanese Patent Application No. 2004-035474 can be used. Specifically, using a film forming apparatus equipped with both an arc evaporation source and a sputtering evaporation source, both evaporation sources are discharged at the same time, and the object to be processed is moved in front of the arc evaporation source to produce a cathode discharge arc ion plate. The A or B layer is formed by the coating method, the object to be processed is moved in front of the sputtering evaporation source, the C layer is formed by the sputtering method, and this operation is repeated. Is preferably laminated to form a laminated hard coating.

  The N content in the mixed gas can be adjusted by appropriately controlling the amounts of N and C in the mixed gas according to the desired composition of the hard film, film forming conditions, and the like. At that time, Ar may be appropriately added to the film forming gas.

  The cathode discharge arc ion plating method can be performed with reference to the method described in JP-A-2003-7160.

  The temperature of the object to be processed at the time of film formation may be appropriately selected according to the type of object to be processed, but if it is too high, the residual stress of the hard film may be reduced, and excessive residual stress is applied to the hard film. It may act, and adhesiveness with a to-be-processed object may be impaired. Therefore, it is recommended that the temperature is set to 300 ° C. or higher, preferably 400 ° C. or higher. If the temperature of the object to be treated is too high, the residual stress will be reduced, but at the same time the compressive stress will be reduced, and the effect of increasing the bending strength of the object to be treated may be impaired. The object to be processed may be deformed. Therefore, it is recommended that the temperature of the object to be processed is 800 ° C. or lower, preferably 700 ° C. or lower. When a substrate such as high-speed tool steel (SKH51, SKD11, SKD61, etc.) is used as the object to be processed, the substrate temperature at the time of manufacture is set below the tempering temperature of the substrate material, and the mechanical characteristics of the substrate are maintained. It is also preferable to do. The tempering temperature can be appropriately selected depending on the substrate material. In general, when SKH51 is used as the base material, 550 to 570 ° C., when SKD61 is used, 550 to 680 ° C. and SKD11 are used. The temperature may be 500 to 530 ° C. In that case, the temperature of the substrate at the time of manufacture is preferably set lower than these tempering temperatures, and specifically, it is preferably set to 50 ° C. or less with respect to the tempering temperature.

  Note that a hard coating can be more efficiently formed by applying a negative potential to the object to be processed at the time of film formation. The higher the bias voltage, the higher the energy of the plasma-forming film forming gas and metal ions, and the hard film showing the resulting cubic crystal structure can be easily obtained. It is preferable to set it to 10V or more, especially 30V or more. However, when the bias voltage is increased, the film is etched by the plasma forming film forming gas, and the film forming speed may be extremely reduced. Therefore, it is preferable that the negative value is 200 V or less, particularly 150 V or less in absolute value. When the proportion of Al is relatively small, even if the bias voltage is somewhat low, the above-described pulling effect works effectively, and a hard coating film having a cubic crystal structure is easily obtained.

  The physical properties of the hard coating obtained in the following experimental examples were determined according to the following method.

[Composition of hard coating]
Measured by EPMA. At that time, it was confirmed that the amount of impurity elements other than metal elements and nitrogen in the hard coating was 5 at% or less for each of oxygen and carbon.

[Analysis of crystal structure]
Measured by EPMA. At that time, it was confirmed that the amount of impurity elements other than metal elements and nitrogen in the hard coating was 5 at% or less for each of oxygen and carbon.

[Crystal structure analysis conditions]
The crystal structure is evaluated by X-ray analysis of the hard coating by the θ-2θ method using an X-ray diffractometer manufactured by Rigaku Electric Co., Ltd. At that time, for a cubic crystal, a CuKα radiation source is used. For the (111) plane, around 2θ = 37.78 °, for the (200) plane, near 2θ = 43.9 °, for the (220) plane. The peak intensity around 2θ = 63.8 ° is measured. X-ray diffraction of hexagonal crystal uses Cu Kα ray, (110) near (2) = 32 ° to 33 ° for the (100) plane, and around 2θ = 48 ° to 50 ° for the (102) plane. For the surface, the peak intensity around 2θ = 57 ° to 58 ° is measured. Using these values, the following formula (1)

(In the formula, IB (111), IB (200) and IB (220) indicate the peak intensity of each face of the cubic crystal. IH (100), IH (102) and IH (110) are the faces of the hexagonal crystal. Of the peak intensity).
The value calculated by introducing into (in the table, “value of the formula (1)”) of 0.8 or more is recognized as the NaCl type (shown as B in the table), and the value of 0 is hexagonal. It was made of a structure (indicated as H in the table), and a mixed type (indicated as B + H in the table) was greater than 0 and less than 0.8. In addition, 2θ = 37.78 ° vicinity, 43.9 ° vicinity, 63.8 ° vicinity, 32 ° to 33 °, 48 ° to 50 °, 57 ° to 58 ° with no clear peak Was amorphous (shown as a in the table).

[Measurement of hardness]
Using a micro Vickers hardness tester, the load was 0.25 N and the holding time was 15 seconds.

[Measurement of oxidation start temperature]
Using the platinum sample, the temperature at which the weight of the platinum sample changed when heated from room temperature to 5 ° C./min in artificial dry air using a thermobalance was defined as the oxidation start temperature.

[Observation of wear width]
Using a cemented carbide end mill (diameter 10 mm, 2 blades) with the hard coating of the present invention formed on it, SKD11 hardened steel (HRC60) was cut for 10 m under the following cutting conditions and then hard. The cutting edge of the end mill coated with the film was observed with an optical microscope.
Cutting conditions Cutting speed: 150 m / minute Blade feed rate: 0.04 mm / Blade cutting: 4.5 mm
Radial notch: 0.2mm
Other: Down cut, dry cut, air blow only

[Type of object to be processed]
In each experimental example, (I) cemented carbide tip (for crystal structure and hardness measurement), (II) cemented carbide ball end mill (diameter 10 mm, two blades) (for wear width measurement) and (III) white Three types of workpieces of gold foil (30 × 5 × 0.1 mmt) (for oxidation start time measurement) were used.

[Apparatus used to form hard coating]
In this experimental example, a hard film was formed using the apparatus schematically shown in FIG. 1 described in Japanese Patent Application No. 2004-035474. In the figure, reference numeral 1 denotes a sputter evaporation source, 2 denotes an arc evaporation source, and 3 denotes a rotatable table for mounting an object to be processed. In addition, a bias power supply is connected to the object to be processed on the table, and a negative potential can be applied to the object to be processed (not shown).

(Experimental example 1)
[Hard film formation]
The target used for the arc evaporation source 1 was prepared and used having a composition described in “Target composition ratio (atomic ratio)” in Table 1.

  Using the apparatus shown in FIG. 1, the object to be processed was mounted on the table 2, the inside of the apparatus was evacuated, and the object to be processed was heated to 500 ° C. with a heater (not shown). And the single or mixed gas which consists of a composition of C and N of "the composition ratio (atomic ratio) of film-forming gas" of Table 1 was supplied in the apparatus so that the pressure in an apparatus might be 2.7 Pa. A bias power supply (not shown) connected to the object to be processed is applied with a voltage of 20 to 100 V so that the object to be processed has a negative potential with respect to the ground voltage, and arc discharge is started to be processed. A hard film having a thickness of 3 μm was formed on the surface of the body. In the present experimental example, the spatter evaporation source 1 used in the sputtering method is not used.

[Physical properties of hard coating]
Table 1 shows the crystal structure of the obtained hard film and the results of measurement of hardness, oxidation start temperature, and wear width. For comparison, the results of the physical properties of a conventional hard film made of TiAlN (Comparative Example 1) and a hard film made of CrAlN (Comparative Example 2) are also shown.

  The hard coatings (Examples 1 to 5) of the present invention were superior to the conventional hard coatings (Comparative Examples 1 and 2) in hardness, oxidation resistance (evaluated from the oxidation start temperature) and wear width. Further, in cases other than the range limited in the present invention (Comparative Examples 3 to 6), the conventional hard film or the hard film of the present invention is any one of hardness, oxidation resistance (evaluated from the oxidation start temperature) and wear width. It was inferior to the film.

(Experimental example 2)
[Hard film formation]
The target used for the arc evaporation source 1 was prepared by using the composition described in “Target composition ratio (atomic ratio)” in Table 2, and the film forming gas was used as “Film forming gas composition ratio (atomic). The experiment was carried out in the same manner as in Experimental Example 1 except that a single or mixed gas having a composition of C and N in the ratio “)” was used.

[Physical properties of hard coating]
Table 2 shows the crystal structure of the obtained hard film and the results of measurement of hardness, oxidation start temperature, and wear width. For comparison, the results of the physical properties of a conventional hard film made of TiAlN (Comparative Example 1) and a hard film made of CrAlN (Comparative Example 2) are also shown.

  The hard film (Examples 6 to 18) of the present invention was superior to the conventional hard film (Comparative Examples 1 and 2) in hardness, oxidation resistance (evaluated from the oxidation start temperature) and wear width. Furthermore, by adding Si or B to the hard coating, it was possible to further improve the hardness, oxidation resistance, and wear width as compared to the hard coating without adding Si or B (Example 1) (Example) 6-8). In the cases other than the range limited in the present invention (Comparative Examples 7 to 11), the conventional hard film or the hard film of the present invention is any one of hardness, oxidation resistance (evaluated from the oxidation start temperature) and wear width. Was inferior.

(Experimental example 3)
[Hard film formation]
For the target of the arc evaporation source 2, the target having the composition described in the upper part (A layer or B layer) of “Target composition ratio (atomic ratio)” in Table 3 is used. Were prepared and used in the composition described in the lower part (C layer) of “Target composition ratio (atomic ratio)”.

  Using the apparatus shown in FIG. 1, the object to be processed was mounted on the table 3, the inside of the apparatus was evacuated, and the object to be processed was heated to 500 ° C. with a heater (not shown). Then, in the apparatus, a single or mixed gas (including Ar so that the mixing ratio is 1: 1) composed of the composition of C and N in the “composition ratio (atomic ratio) of film forming gas” in Table 3; It supplied so that the pressure in an apparatus might be 2.7 Pa. A voltage of 20 to 100 V is applied to the object to be processed by a bias power source (not shown) connected to the object so that the object has a negative potential with respect to the ground voltage, and arc discharge and sputtering are performed. While discharging was started and the table was rotated, the film was formed so that the film thicknesses of the A or B layer and the C layer were the “thickness” shown in Table 3. The A or B layer and the C layer were laminated on the object to be processed repeatedly.

[Physical properties of hard coating]
Table 3 shows the crystal structure of the obtained hard film and the results of measurement of hardness, oxidation start temperature, and wear width. For comparison, the results of the physical properties of the conventional hard coating made of TiAlN (Comparative Example 1) and the hard coating made of CrAlN (Comparative Example 2) and the hard coating of the present invention consisting of a single layer (Examples 19 to 21). Also shown.

  The laminated hard coatings (Examples 22 to 32) of the present invention were superior in hardness, oxidation resistance and wear width to the conventional hard coatings (Comparative Examples 1 and 2). Further, in the cases other than the range limited in the present invention (Comparative Examples 12 to 14), the hardness and wear width are inferior to those of the laminated hard film of the present invention. In particular, the wear width is the conventional hard film (Comparative Example 1). And inferior to 2). Further, by using the laminated type, the oxidation resistance (oxidation start temperature) could be improved without significantly reducing the hardness as compared with the single-layer hard coating (Examples 19 and 20) (Example 22). ~ 28).

Schematic of the manufacturing apparatus used with the manufacturing method of this invention.

Explanation of symbols

1. 1. Sputter evaporation source 2. Arc evaporation source Table 4. Magnetic field lines

Claims (7)

[(Nb _1-d , Ta _d ) _a Al _1-a ] (C _1-X N _X )
0.4 ≦ a ≦ 0.6,
0 ≦ d ≦ 1,
0.4 ≦ X ≦ 1,
(Wherein a, d and X independently represent an atomic ratio)
Hard coating characterized by being A hard coating composed of [(Nb _1-d , Ta _d ) _a (Al _1-abc , Si _b , B _c ) _1-a ] (C _1-X N _X ),
0.4 ≦ a ≦ 0.6,
0 <b + c ≦ 0.15,
0 ≦ d ≦ 1,
0.4 ≦ X ≦ 1,
(In the formula, a, b, c, d and X each independently represent an atomic ratio: b and c may be either 0, but neither is 0)
Hard coating characterized by being A layer satisfying the composition according to claim 1 or B layer satisfying the composition according to claim 2,
[(Nb _{1 -D} , Ta _D ) _A (Al _{1 -ABC} , Si _B , B _C ) _{1 -A} ] (C _{1 -X} N _X )
0.2 ≦ A ≦ 0.5,
0.15 <B + C ≦ 0.5,
0 ≦ D ≦ 1,
0.4 ≦ X ≦ 1
(In the formula, A, B, C, D and X each independently represent an atomic ratio: B and C may be one of B and C, but not both of them)
Laminated hard coating in which C layers consisting of   The multilayer hard coating according to claim 3, wherein the thickness of the A layer or the B layer is 5 nm or more, and the thickness of the C layer is 1 nm or more. [(Nb _1-d , Ta _d ) _a Al _1-a ], 0.4 ≦ a ≦ 0.6, 0 ≦ d ≦ 1
(Wherein, a and d independently represent an atomic ratio) or [(Nb _{1 -d} , Ta _d ) _a (Al _{1 -abc} , Si _b , B _c ) _{1 -a} ] 0.4 ≦ a ≦ 0.6, 0 <b + c ≦ 0.15, 0 ≦ d ≦ 1
(Wherein, a, b, c and d independently represent an atomic ratio; one of b and c may be 0, but neither is 0) Use
A hard film obtained by forming a film in an N-containing gas or a mixed gas containing C and N by a cathode discharge arc ion plating method. [(Nb _1-d , Ta _d ) _a Al _1-a ], 0.4 ≦ a ≦ 0.6, 0 ≦ d ≦ 1
A target in which a and d independently represent each other an atomic ratio, or
[(Nb _1-d , Ta _d ) _a (Al _1-abc , Si _b , B _c ) _1-a ], 0.4 ≦ a ≦ 0.6, 0 <b + c ≦ 0.15, 0 ≦ d ≦ 1
(Wherein, a, b, c and d independently represent an atomic ratio; one of b and c may be 0, but neither is 0) Use
Forming a film by a cathode discharge arc ion plating method in an N-containing gas or a mixed gas containing C and N;
[(Nb _1-D , Ta _D ) _A (Al _1-ABC , Si _B , B _C ) _1-A ], 0.2 ≦ A ≦ 0.5, 0.15 <B + C ≦ 0.5, 0 ≦ D ≦ 1
(Wherein, A, B, C and D are independently of each other and indicate an atomic ratio: B and C may be one, but not both) Use
A laminated hard coating obtained by repeating a step of forming a coating by sputtering in an N-containing gas or a mixed gas containing C and N. Using a film forming apparatus equipped with both an arc evaporation source and a sputtering evaporation source, both evaporation sources are discharged at the same time, and the object to be processed is moved in front of the arc evaporation source. 5. The method according to claim 3, wherein the step of forming the layer or the B layer and the step of moving the workpiece to the front of the sputtering evaporation source and forming the C layer by a sputtering method are performed repeatedly. A method for producing a laminated hard coating.

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