JP4758288B2 - Manufacturing method of hard coating - Google Patents

Description

  The present invention relates to a method for producing a hard coating for improving the wear resistance of a cutting tool such as a tip, a drill or an end mill.

  Conventionally, a hard coating such as TiN, TiCN, TiAlN or the like has been applied for the purpose of improving the wear resistance of a cutting tool based on cemented carbide, cermet or high-speed tool steel. .

  In particular, since a composite nitride film of Ti and Al (hereinafter referred to as TiAlN) exhibits excellent wear resistance, it can be used for high-speed cutting in place of a film made of titanium nitride, carbide, carbonitride, or the like. It is being applied to cutting tools for cutting hard materials such as hardened steel.

The TiAlN film is known to increase the hardness of the film and improve the wear resistance when Al is added. However, Patent Document 1 discloses that TiAlN is (Al _x , Ti _1-x ) N. It is shown that ZnS-type soft AlN is precipitated when the Al composition ratio x is 0.7 or more. The patent also states that “when the Al amount (x) exceeds 0.75, the hard film approximates to AlN, which leads to softening of the film, resulting in insufficient hardness and easy flank wear. To cause. " Further, FIG. 3 of the same patent shows the relationship between the Al composition ratio and the film hardness, and the hardness is reduced from the vicinity where the Al composition exceeds 0.6. This is because the Al composition ratio x is 0.6. It is suggested that ZnS-type AlN starts to be precipitated between ˜0.7, and that the precipitation of ZnS-type AlN increases as the Al composition ratio increases, suggesting that the film strength decreases. Furthermore, the same patent shows that with respect to oxidation resistance, when the Al composition ratio x is 0.56 or more and the oxidation start temperature is 800 ° C. or more, the oxidation start temperature tends to increase as the x value increases. However, the upper limit of the Al composition ratio defined in consideration of hardness is about 850 ° C. at 0.75.

  That is, in the TiAlN film, there is a limit to increase the hardness by increasing the Al composition ratio. Therefore, the hardness and the oxidation resistance cannot be increased at the same time. As a result, there is a limit to improving the wear resistance.

However, in recent years, there has been a demand for higher speed and higher efficiency as the usage conditions of cutting tools, and in order to realize such cutting tools, a hard coating for cutting tools that exhibits even higher wear resistance is required. It has been.
Japanese Patent No. 2644710 Patent Claim etc.

  The present invention has been made in view of such circumstances, and the purpose thereof is useful for obtaining a hard coating for a cutting tool that is capable of high-speed and high-efficiency cutting and is superior in wear resistance to TiAlN. It is to provide a manufacturing method.

  The method for producing a hard coating for a cutting tool according to the present invention is a method for producing the following hard coating, in an arc ion plating method in which evaporation and ionization of a metal constituting a target is performed by arc discharge. A magnetic field line that diverges forward or travels in a direction substantially perpendicular to the evaporation surface of the target is formed. The magnetic field line promotes the plasma formation of the film forming gas in the vicinity of the target object and applies it to the target object. The gist is to form a film with a bias potential of −50 V to −300 V with respect to the ground potential.

A hard film made of (Ti _a , Al _b , Cr _c ) (C _1-d N _d ),
A, b, c, d above
0.02 ≦ a ≦ 0.30,
0.55 ≦ b ≦ 0.765,
0.06 ≦ c,
a + b + c = 1,
0.5 ≦ d ≦ 1
(A, b, and c represent the atomic ratio of Ti, Al, and Cr, respectively, d represents the atomic ratio of N, and so on)
Or 0.02 ≦ a ≦ 0.175,
0.765 ≦ b,
4 (b−0.75) ≦ c,
a + b + c = 1,
0.5 ≦ d ≦ 1 is satisfied, and the crystal structure is mainly composed of a rock salt structure type.

  In this case, the temperature of the object to be processed (hereinafter sometimes referred to as substrate temperature) during film formation is set to 300 ° C. or higher and 800 ° C. or lower, and the partial pressure or total pressure of the reaction gas during film formation is set to 0.5 Pa. It is desirable that the pressure be 7 Pa or less.

  In addition, the said reaction gas in this invention means nitrogen gas, methane gas, ethylene, acetylene, ammonia, hydrogen, or the gas containing the element required for the component composition of the film | membrane which mixed these 2 or more types other than these. A rare gas such as Ar used is called an assist gas, and these are collectively referred to as a film forming gas.

  In the method of the present invention, by adding Cr to conventional TiAlN and manufacturing while controlling the component composition of these Ti, Al, and Cr as in the present invention, it is more wear resistant than conventional hard coatings for cutting tools. An excellent hard film could be obtained. By realizing such a hard coating, it has become possible to supply a long-life cutting tool that can be used for cutting high-hardness steel such as high-speed cutting and hardened steel.

  Under the circumstances as described above, the present inventors have conducted intensive research aiming at realization of a hard coating for a cutting tool that exhibits superior wear resistance. As a result, it has been found that if the hardness and oxidation resistance of the film can be increased simultaneously as an index, the wear resistance is remarkably improved. And as a result of this research, we focused on the TiAlN film and found that adding Cr to TiAlN improves the hardness and oxidation resistance of the film, resulting in a dramatic improvement in wear resistance. As a result of further pursuing the quantitative effects of TiAlN and Cr, the present invention has been conceived.

That is, the hard film obtained by the method of the present invention is a film made of nitride, carbonitride (Ti _a , Al _b , Cr _c ) (C _1-d N _d ) of Ti, Al, and Cr, The composition of the nitride or carbonitride is
0.02 ≦ a ≦ 0.30, 0.55 ≦ b ≦ 0.765, 0.06 ≦ c,
a + b + c = 1, 0.5 ≦ d ≦ 1
Or 0.02 ≦ a ≦ 0.175, 0.765 ≦ b, 4 (b−0.75) ≦ c,
a + b + c = 1, 0.5 ≦ d ≦ 1
The reason why the composition of Ti, Al, Cr, C and N in the film is defined in this way will be described in detail below.

  TiAlN is a rock salt structure type crystal, and is a rock salt structure type composite nitride in which Al is substituted into the Ti site of the rock salt structure type TiN. Since the rock salt structure type AlN is a high-temperature and high-pressure phase, it is expected to be a high-hardness substance. Therefore, if the ratio of Al in TiAlN is increased while maintaining the rock salt structure, the hardness of the TiAlN film can be increased. However, since rock salt structure type AlN is a non-equilibrium phase at room temperature and normal pressure and high temperature and low pressure, it usually produces only soft ZnS type AlN even when vapor phase coating is performed, and it produces rock salt structure type AlN alone. I can't.

However, TiN is a rock salt structure type and has a lattice constant close to that of rock salt structure type AlN. Therefore, if Al is added to Ti to form a nitride film, AlN is drawn into the structure of TiN, so The rock salt structure type TiAlN can be produced even at high temperature and low pressure. However, as described above, when the Al composition ratio x exceeds 0.6 to 0.7 when TiAlN is expressed as (Al _x , Ti _1-x ) N, the pulling effect by TiN is weakened and the softness is reduced. ZnS type AlN is deposited.

  By the way, since the lattice constant of CrN is closer to that of rock salt structure type AlN than TiN, the ratio of rock salt structure type AlN can be further increased by partially replacing Ti in TiAlN with Cr. If the ratio of the rock salt structure type AlN in the film can be increased by adding Cr in this way, it is considered that the hardness can be made higher than that of the TiAlN film.

  On the other hand, since AlN and CrN are superior in oxidation resistance to TiN, it is preferable to add Al and Cr while reducing the Ti ratio from the viewpoint of improving oxidation resistance.

The reason why the atomic ratios a, b, and c of the metal elements Ti, Al, and Cr constituting the (Ti _a , Al _b , Cr _c ) (C _1-d N _d ) film of the present invention will be described in detail below. .

  First, for Al, the lower limit of the atomic ratio b is set to 0.55 in order to obtain a hardness and oxidation resistance equal to or higher than those of the above-described prior art; TiAlN (0.56 ≦ Al ≦ 0.75). Moreover, by adding Cr, as described above, the ratio of the rock salt structure type AlN in the film can be increased to increase the hardness and the oxidation resistance can be improved, but such an effect is effectively exhibited. For this, the lower limit of the atomic ratio c of Cr needs to be 0.06. However, when the atomic ratio b of Al exceeds 0.765, the atomic ratio c of Cr is set within the following range.

  That is, FIG. 1 shows a composition diagram of the metal components Ti, Al, and Cr in the (Ti, Al, Cr) N film. The line c = 4 (b−0.75) in FIG. On the left side, that is, when c <4 (b-0.75), even when Cr is added, the AlN crystal structure in the film has a higher proportion of soft ZnS type, so the hardness of the film rapidly increases. descend. Therefore, when the Al atomic ratio b exceeds 0.765, in order to obtain a hardness equal to or higher than the TiAlN (0.56 ≦ Al ≦ 0.75), the Cr ratio is set to c ≧ 4 (b−0). .75).

  Further, in order to obtain a hardness equal to or higher than that of TiAlN (0.56 ≦ Al ≦ 0.75), the atomic ratio a of Ti needs to be 0.02 or more. The reason is that by adding Cr as described above, the ratio of the rock salt structure type AlN can be increased. However, since CrN is a substance having a lower hardness than TiN, if Ti is replaced with Cr, the hardness decreases accordingly. Is concerned. Therefore, in order to obtain a certain level of hardness, it is necessary to include a certain amount of Ti, and TiN (4.24 Å) whose lattice constant is slightly different from CrN (4.14 Å) and rock salt structure type AlN (4.12 Å). When mixed, the crystal lattice is distorted and hardened.

  On the other hand, if the atomic ratio of Ti is too high, the oxidation resistance is inferior to that of TiAlN (0.56 ≦ Al ≦ 0.75), so the atomic ratio a of Ti is set to 0.30 or less.

In addition, by making the atomic ratio of Ti less than 0.20, the oxidation resistance is further improved and is further higher than the maximum value 850 ° C. of the oxidation start temperature exhibited by the TiAlN (0.56 ≦ Al ≦ 0.75) film. A high oxidation start temperature is exhibited, and better oxidation resistance can be ensured. Therefore, even within the ranges of a, b and c defined above,
0.02 ≦ a <0.20, 0.55 ≦ b ≦ 0.765, 0.06 ≦ c
a + b + c = 1
Or 0.02 ≦ a <0.20, 0.765 ≦ b, 4 (b−0.75) ≦ c
It is preferable that a + b + c = 1.

In addition, the Al atomic ratio b is set to 0.6 or more, and the upper limit of the Al atomic ratio is limited to a region where the crystal structure of the film is almost a rock salt single phase, so that not only oxidation resistance but also TiAlN ( Among 0.56 ≦ Al ≦ 0.75), it is possible to obtain a higher hardness than Ti _0.4 Al _0.6 N, which shows the highest hardness.

Therefore, the more preferable range of a, b and c is
0.02 ≦ a <0.20, 0.60 ≦ b ≦ 0.709,
a + b + c = 1,
Or 0.02 ≦ a <0.20, 0.709 ≦ b,
11/6 × (b−0.66) ≦ c,
a + b + c = 1.

By adding C to the film, a hard carbide such as TiC can be precipitated in the film to increase the hardness of the film itself. However, if excessively added, a chemically unstable aluminum carbide precipitates, and the oxidation resistance tends to deteriorate. Accordingly, the value of d in (Ti _a , Al _b , Cr _c ) (C _1-d N _d ) is set to 0.5 or more. The value of d is desirably equivalent to the total addition amount of Al and Cr (b + c), preferably 0.7 or more, more preferably 0.8 or more, and most preferably d = 1. It is.

  The crystal structure of the hard coating of the present invention is substantially composed mainly of a rock salt structure type. This is because high strength cannot be secured when a ZnS structure is mixed as described above.

  The crystal structure mainly composed of the rock salt structure type is a (111) plane, a (200) plane, a (220) plane, a (311) plane among peaks indicating a rock salt structure in X-ray diffraction by the θ-2θ method, The peak intensities of the (222) plane and (400) plane are IB (111), IB (200), IB (220), IB (311), IB (222), and IB (400), respectively, and a ZnS type structure is formed. Of the peaks shown, when the peak intensities of the (100) plane, (102) plane, and (110) plane are IH (100), IH (102), and IH (110), respectively, A crystal structure whose value is 0.8 or more. This is because when it is less than 0.8, the hardness of the film is lower than the hardness that is preferable in the present invention.

As for the peak intensity of the ZnS type structure, Cu _Kα rays are used in an X-ray diffractometer, the (100) plane is around 2θ = 32 ° to 33 °, and the (102) plane is around 2θ = 48 ° to 50 °. The (110) plane is obtained by measuring the intensity of the peak appearing in the vicinity of 2θ = 57 ° to 58 °. Although the ZnS type crystal is mainly AlN, Ti and Cr are mixed, so that the measured peak position of ZnS type AlN is slightly shifted from the peak position of ZnS type AlN on the JCPDS card.

  When the crystal structure of the film of the present invention is measured by X-ray diffraction, the diffraction line intensity in the rock salt structure type crystal structure is I (220) ≦ I (111) and / or I (220) ≦ I (200 ) Is desirable. This is because the (111) plane and (200) plane, which are densely packed surfaces of the rock salt structure type, are oriented in parallel to the coating surface, thereby improving the wear resistance.

  Further, the diffraction line intensity ratio of (200) plane to (111) plane; I (200) / I (111) is preferably 0.1 or more. I (200) / I (111) varies within a range of about 0.1 to 5 depending on conditions such as a bias voltage applied to the substrate during film formation, gas pressure, and film formation temperature. Then, when I (200) / I (111) satisfied 0.1 or more, it discovered that the cutting characteristic of the film | membrane became favorable. The details are not clear, but can be considered as follows.

  That is, in the crystal structure of the rock salt structure type, the metal element (Ti, Al, Cr) basically bonds with nitrogen or carbon, and there is almost no bond between metal elements, between nitrogen atoms, or between carbon atoms, In the (111) plane, the nearest neighbor atoms are metal elements, nitrogen atoms, or carbon atoms, but it is considered that they are not bonded to each other. On the other hand, in the (200) plane, adjacent atoms (nearest neighbor atoms) are a combination of a metal element and nitrogen or a metal element and carbon, and a metal element and a nitrogen atom or carbon atom in the (200) plane are It is considered stable because of the high proportion of bonding. Therefore, if the in-plane highly stable (200) plane is oriented with respect to the surface at a certain ratio with respect to the (111) plane, the hardness increases and the cutting characteristics can be improved. it is conceivable that. The value of I (200) / I (111) is preferably 0.2 or more.

(111) plane diffraction angle of the diffraction lines of the composition of the coating, which can vary depending on the type of the state of residual stress or substrate, for the hard film of the present invention using the K _alpha line of Cu theta- As a result of X-ray diffraction by the 2θ method, the diffraction angle changed within a range of approximately 37.0 ° to 38.0 °, and the diffraction angle tended to decrease as the amount of Ti in the film increased. . Thus, as described above, the diffraction angle of the (111) plane becomes lower, that is, the distance between the (111) planes increases as the amount of Ti in the film increases. .24 cm) is considered to be caused by the fact that it is larger than the lattice constant (4.12 cm) of AlN of the rock salt structure type and the lattice constant of CrN (4.14 cm).

The diffraction angle in the (111) plane of the rock salt structure type can be calculated by substituting into the following Bragg equation (5). The distance between the (111) planes in the formula (5) is the standard lattice constants (4.24, 4.12, and 4.14) of the rock salt structure type TiN, AlN, and CrN, and their composition ratios. From the following equation (6) obtained by using a mixing rule (low of mixture).
2 x distance between planes (Å) x sin (diffraction angle 2θ / 2) = wavelength of X-ray used (Å) ... (5)
[Wavelength of X-ray used: Kα ray of Cu 1.54056Å]
(111) Distance between planes (Å) = [2.4492 × Ti amount (at%) + 2.379 × Al amount (at%) + 2.394 × Cr amount (at%)] / 100 (6)
[The amount of each element is 100% equivalent only for metal elements]

For example, when the hard coating of the present invention; (Ti _0.1 Al _0.72 Cr _0.18 ) N coating is formed on a cemented carbide substrate, the diffraction angle obtained from the above formula (5) is 37.6 °. However, it varies within the range of 37.2 ° to 37.7 ° due to the influence of film forming conditions and residual stress. In the case of the hard coating of the present invention, since the compressive stress was acting on the coating as it was formed, the inter-surface distance of the surface located in the direction parallel to the substrate was reduced to the standard state [the above formula ( 6), the diffraction angle of the (111) plane in the X-ray diffraction method of θ-2θ is the standard state [the inter-surface distance in the standard state obtained from the above formula (6) The diffraction angle obtained by substituting for (5)] was detected at a lower angle side.

Note that the diffraction angle of the (111) plane obtained by X-ray diffraction by the θ-2θ method using Cu K _α- ray is obtained by the above formulas (5) and (6) from the composition of the metal elements in the film. It is desirable that it is within a range of ± 0.3 ° with respect to the standard diffraction angle calculated using the above.

In addition, the half width of the diffraction line on the (111) plane [usually FWHM (Full Width Half Maximum), that is, the width of the diffraction line at the half of the diffraction line maximum intensity] indicates the crystal size of the film, However, when the full width at half maximum increases, the crystals of the film tend to be small. In the case of a hard coating that satisfies the requirements of the present invention, the half width is approximately 0.2 ° or more and 1 ° or less, and the (Ti _0.1 Al _0.72 Cr _0.18 ) N coating shown as an example. In this case, it changed within the range of 0.3 ° to 0.8 ° depending on the film forming conditions.

  The hard film according to the present invention can be used by laminating a plurality of different films satisfying the above requirements, in addition to a single layer film satisfying the above requirements. Further, depending on the application, it has a crystal structure mainly composed of a rock salt structure type on one side or both sides of the (Ti, Cr, Al) (CN) film defined in the present invention of one layer or two or more layers, and At least one layer selected from the group consisting of a metal nitride layer, a metal carbide layer, and a metal carbonitride layer having a composition different from that of the hard film may be laminated.

  In addition, as mentioned above, the “crystal structure mainly composed of a rock salt structure type” here also includes the (111) plane, the (200) plane, and the (220) of the peaks indicating the rock salt structure in the X-ray diffraction by the θ-2θ method. The peak intensities of the plane, (311) plane, (222) plane, and (400) plane are IB (111), IB (200), IB (220), IB (311), IB (222), and IB (400), respectively. ) And the peak intensity of the (100) plane, (102) plane, and (110) plane among the peaks showing the ZnS type structure are IH (100), IH (102), and IH (110), respectively. A crystal structure in which the value of the above formula (4) is 0.8 or more. Examples of the metal nitride layer, metal carbide layer, or metal carbonitride layer having a rock salt structure type and different composition from the hard film include films such as TiN, TiAlN, TiVAlN, TiCN, TiAlCN, TiNbAlCN, and TiC. It is done.

  Further, the hard film for a cutting tool of the present invention is selected from the group consisting of 4A group, 5A group, 6A group, Al and Si on one or both sides of the hard film of the present invention having one or more layers. One or more metal layers or alloy layers containing at least one kind of metal may be laminated. Examples of the 4A group, 5A group, and 6A group metals include Cr, Ti, and Nb. Ti-Al or the like can be used as the alloy. The formation of such a laminated film is particularly effective when an iron-based base material (HSS, SKH51, SKD, etc.) whose adhesion to the hard film is lower than the cemented carbide base material is used as the substrate. A film of CrN, TiN, TiAlN or the like having a relatively lower hardness than the film specified in the present invention or a metal intermediate layer of Cr, Ti, Ti-Al, or the like is formed on the base material. By forming the hard film of the invention, a hard film having good adhesion to the substrate can be obtained.

  (I) a film satisfying the requirements of the present invention and different from each other, and (ii) a metal nitride layer, a metal carbide layer or a metal carbonitride layer having a rock salt structure type and a composition different from that of the hard film , (Iii) When forming a plurality of metal layers or alloy layers containing at least one metal selected from the group consisting of Group 4A, Group 5A, Group 6A, Al and Si to form the hard coating of the present invention The thickness of one layer should be in the range of 0.005 to 2 μm. However, the hard coating of the present invention can be used as a total, whether it is a single layer or a plurality of layers. The film thickness is preferably in the range of 0.5 μm to 20 μm. If the thickness is less than 0.5 μm, the film thickness is too thin and wear resistance is not preferable. On the other hand, if the thickness exceeds 20 μm, the film is broken or peeled off during cutting. A more preferable film thickness is 1 μm or more and 15 μm or less.

  Furthermore, even when the Al composition ratio is high, it is very effective to form a film by the method defined in the present invention in order to produce the hard film of the present invention whose crystal structure is mainly composed of a rock salt structure type. It is. That is, arc discharge is performed in a film forming gas atmosphere to evaporate and ionize the metal constituting the target, and form the hard film of the present invention on the object to be processed. It is necessary to form the film while promoting the formation of the film. At this time, the film formation gas in the vicinity of the object to be processed is formed so as to diverge forward or parallel to the evaporation surface of the target. It is preferable that the film be formed while being accelerated by the lines of magnetic force.

  The film forming method of the present invention is effective for forming a (Ti, Al, Cr) (CN) film mainly composed of a rock salt structure type defined in the present invention, and other films. Needless to say, this is also a very effective method for film formation.

  In an arc ion plating (AIP) apparatus, it is difficult to produce the coating of the present invention with a cathode evaporation source in which a magnetic field is arranged on the back side of a target as in the prior art, and a magnet is arranged on the side or front of the target. In order to form the hard coating of the present invention, it is very effective to form a magnetic field line that diverges in front of the target evaporating surface and travels in parallel with the target evaporation surface and promotes the formation of plasma of the deposition gas by this magnetic field line. That's it.

  As an example of an apparatus for carrying out the present invention, an AIP apparatus will be briefly described with reference to FIG.

  This AIP apparatus includes a vacuum vessel 1 having an exhaust port 11 for evacuating and a gas supply port 12 for supplying a film forming gas, and an arc evaporation source 2 for evaporating and ionizing a target constituting a cathode by arc discharge. The support base 3 that supports the target object (cutting tool) W to be coated, and a negative bias voltage is applied to the target object W through the support base 3 between the support base 3 and the vacuum vessel 1. And a bias power source 4.

  The arc evaporation source 2 includes a target 6 constituting a cathode, an arc power source 7 connected between the target 6 and a vacuum vessel 1 constituting an anode, and an evaporation surface S of the target 6 substantially orthogonally. A magnet (permanent magnet) 8 is provided as magnetic field forming means that forms magnetic lines of force that diverge forward or parallel to the front and extend to the vicinity of the workpiece W. As the magnetic flux density in the vicinity of the object to be processed W, the magnetic flux density at the center of the object to be processed is 10 G (Gauss) or more, preferably 30 G or more. Note that “substantially perpendicular to the evaporation surface” means that the angle is about 30 ° or less, including 0 ° with respect to the normal direction of the evaporation surface.

  FIG. 3 is an enlarged schematic cross-sectional view of an example of the main part of the arc evaporation source used for the implementation of the present invention. The magnet 8 as the magnetic field forming means is disposed so as to surround the evaporation surface S of the target 6. ing. The magnetic field forming means is not limited to the magnet, but may be an electromagnet including a coil and a coil power source. Further, as shown in FIG. 4, the magnets may be disposed so as to surround the front (the object side) of the evaporation surface S of the target 6. In FIG. 2, the chamber is an anode. However, for example, a cylindrical dedicated anode surrounding the front of the target side surface may be provided.

  Note that the arc evaporation source 102 of the conventional AIP apparatus shown in FIG. 5 includes an electromagnet 109 for concentrating arc discharge on the target 106, but the electromagnet 109 is located on the back side of the target 106. Therefore, the magnetic field lines are parallel to the target surface in the vicinity of the target evaporation surface, and the magnetic field lines do not extend to the vicinity of the workpiece W.

  The difference in the magnetic field structure between the arc evaporation source of the AIP apparatus used in the present invention and the conventional one is in the difference in how the plasma of the deposition gas spreads.

  As shown in FIG. 4, the electron e generated by the discharge moves so as to wrap around the lines of magnetic force, and the electrons collide with nitrogen molecules constituting the film forming gas, so that the film forming gas is plasma. Turn into. In the conventional evaporation source 102 in FIG. 5, since the magnetic field lines are limited to the vicinity of the target, the plasma density of the film forming gas generated as described above is highest in the vicinity of the target, and in the vicinity of the workpiece W, the plasma is high. The density is quite low. On the other hand, in the evaporation source used in the present invention as shown in FIGS. 3 and 4, the lines of magnetic force extend to the object to be processed W, so that the plasma density of the film forming gas in the vicinity of the object to be processed W is the conventional evaporation source. It is much higher than.

Such a difference in plasma density of the film forming gas is considered to affect the crystal structure of the generated film. FIG. 6 shows an example in which such an effect has been confirmed. A film having a composition of (Ti _0.1 , Cr _0.2 , Al _0.7 ) N is used for the conventional evaporation source and the evaporation source of the present invention. The X-ray-diffraction result of the TiCrAlN film | membrane when forming into a film using each is shown. In FIG. 6, “B1” represents a rock salt structure, “Hex” represents a ZnS type structure, and () represents a crystal plane. Moreover, the peak without a symbol in FIG. 6 has shown the peak of the board | substrate (the cemented carbide). The film formation conditions are as follows: both the evaporation source has an arc current of 100 A, a nitrogen gas pressure of 2.66 Pa, a substrate (object to be processed) temperature of 400 ° C., and the substrate (object to be processed) bias voltage is changed within a range of 50V to 300V. ing. The bias potential is applied so as to be negative with respect to the ground potential. For example, the bias voltage of 100 V indicates that the bias potential is -100 V with respect to the ground potential.

  As shown in FIG. 6 (2), in the evaporation source of the conventional AIP apparatus in which the magnet is located on the back surface of the target, even if the bias voltage is increased to 300V, the rock salt structure type and hexagonal crystal are cubic. However, when the evaporation source of the AIP apparatus of the present invention in which the magnet is located on the side surface of the target is used as shown in FIG. It can be seen that a rock salt structure type single-phase film can be obtained by adjusting the voltage to 70 V or higher.

  Originally, rock salt structure type AlN is a non-equilibrium phase at room temperature and normal pressure and is difficult to generate, but the evaporation source of the present invention promotes the conversion of nitrogen into plasma, and nitrogen becomes high energy particles. It is considered that the rock salt structure type AlN which is a non-equilibrium phase is easily generated.

  Increasing the bias voltage increases the energy of the plasma-forming film forming gas and metal ions, and promotes the formation of a rock salt structure in the film. Therefore, the bias voltage is preferably 50 V or more, and more preferably. Is 70 V or higher, more preferably 100 V or higher. However, if the bias voltage is too high, the film is etched by the plasma-forming film forming gas, and the film forming speed becomes extremely small, which is not practical. Therefore, the bias voltage is preferably 300 V or less, more preferably 260 V or less, and even more preferably 200 V or less. The purpose of applying the bias voltage is to impart energy to the metal film ions and the ions of the metal atoms coming from the target as described above to promote the rock salt structuring of the film. In the formation of a film having a relatively large amount of Cr, even if the bias voltage is somewhat low, the above-described pulling effect is effective, and a rock salt structure can be easily achieved. In the formation of a film having an Al content of about 65 atomic% or less or a Cr content exceeding about 25 atomic%, a rock salt structure type single-layer film can be obtained even when the bias voltage is 70 V or less.

In the present invention, it is preferable that the range of the substrate temperature during film formation is 300 ° C. or higher and 800 ° C. or lower, which is related to the stress of the formed film. FIG. 7 shows, as an example, the relationship between the substrate (object to be processed) temperature during (Ti _0.1 Al _0.7 Cr _0.2 ) N film formation and the residual stress of the formed film, with an arc current of 100 A and during film formation. The experiment was conducted with a substrate bias voltage of 150 V and a nitrogen gas pressure of 2.66 Pa.

  FIG. 7 shows that the residual stress of the hard film obtained tends to decrease as the substrate temperature rises. When excessive residual stress is acting on the obtained hard film, peeling is likely to occur in a film-formed state, resulting in poor adhesion. Therefore, the substrate temperature is preferably 300 ° C. or higher, more preferably 400 ° C. or higher. On the other hand, if the temperature of the substrate (object to be processed) is increased, the residual stress is reduced. However, if the residual stress is too small, the compressive stress is reduced, and the effect of increasing the bending strength of the substrate is impaired. Thermal alteration will also occur. Therefore, the substrate temperature is preferably 800 ° C. or lower. More preferably, it is 700 degrees C or less.

  When the substrate is a cemented carbide base material, the base material temperature is not particularly limited, but the base material is HSS (high speed tool steel, SKH51, etc.) or hot tool steel such as SKD11, SKD61, etc. For this purpose, it is preferable to maintain the mechanical characteristics of the substrate by setting the substrate temperature at the time of film formation to a tempering temperature of the substrate material or less. The tempering temperature varies depending on the substrate material, for example, about 550 to 570 ° C. for the SKH51, 550 to 680 ° C. for the SKD61, and 500 to 530 ° C. for the high temperature tempering of the SKD11. The tempering temperature or lower is preferable. More preferably, the substrate temperature is about 50 ° C. lower than the respective tempering temperatures.

  Furthermore, in the present invention, it is preferable that the partial pressure or the total pressure of the reaction gas at the time of formation is in a range of 0.5 Pa to 7 Pa. Here, the “partial pressure or total pressure” of the reaction gas is indicated by the fact that the present invention refers to a gas containing an element necessary for the composition of the film, such as nitrogen gas or methane gas, as described above. A rare gas such as argon is called an assist gas, and these are combined to form a film-forming gas. When only the reaction gas is used as the film-forming gas, the total pressure of the reaction gas is controlled. This is because it is effective to control the partial pressure of the reaction gas when both the reaction gas and the assist gas are used. When the partial pressure or total pressure of this reaction gas is less than 0.5 Pa, the generation of macroparticles (melt of the target) generated in the case of arc evaporation increases and the surface roughness increases, which may cause inconveniences depending on the application. It is not preferable. On the other hand, when the partial pressure or total pressure of the reactive gas exceeds 7 Pa, scattering due to collision of the evaporated particles with the reactive gas increases, which is not preferable because the film formation rate is reduced. Preferably it is 1 Pa or more and 5 Pa or less, More preferably, it is 1.5 Pa or more and 4 Pa or less.

  In the present invention, the AIP method has been described as the film forming method. However, the film forming method is not limited to the AIP method as long as the film forming method promotes the plasma formation of the film forming gas together with the metal element. Alternatively, the film can be formed by an ion beam assisted deposition method using nitrogen or nitrogen.

  The hard coating according to the present invention is effective to be produced by vapor phase coating methods such as ion plating and sputtering, in which the target is evaporated or ionized as described above and deposited on the object to be processed. When the characteristics of the target are not preferable, there is a problem that the stable discharge state cannot be maintained at the time of film formation, and the component composition of the obtained film is not uniform. Then, in obtaining the hard film for a cutting tool of the present invention that exhibits excellent wear resistance, the characteristics of the target used were also examined, and the following knowledge was obtained.

  First, it was found that by setting the relative density of the target to 95% or more, the discharge state during film formation was stabilized and the hard coating of the present invention was efficiently obtained. That is, when the relative density of the target is less than 95%, a rough portion of an alloy component such as micropores is generated in the target. When such a target is used for film formation, the alloy component is evaporated. It becomes non-uniform | heterogenous and the component composition of the film | membrane obtained will vary or a film thickness will become non-uniform | heterogenous. In addition, since the void portion is locally and rapidly consumed during film formation, the depletion rate is increased and the life of the target is shortened. When there are a large number of holes, not only the local wear proceeds rapidly, but also the strength of the target deteriorates and causes cracks. The relative density of the target is preferably 96% or more, and more preferably 98% or more.

  Even if the relative density of the target is 95% or more, if the vacancies present in the target are large, the discharge state becomes unstable and a film cannot be formed satisfactorily. It is known that when a hole having a radius of 0.5 mm or more exists in the target, the arc discharge for the evaporation or ionization of the alloy component constituting the target is interrupted and the film formation cannot be performed. As a result of studies by the present inventors, it has been found that when the radius of the hole is 0.3 mm or more, the discharge state becomes unstable even if the discharge is not interrupted. Therefore, in order to maintain a stable discharge state and perform film formation satisfactorily and efficiently, the radius of the vacancy existing in the target should be less than 0.3 mm, preferably 0.2 mm or less.

In the vapor phase coating method such as the AIP method, the component composition of the target to be used determines the component composition of the film to be formed. Therefore, the component composition of the target may be the same as the component composition of the target film. preferable. In other words, to obtain a hard coating excellent present invention in wear resistance, as the _target, be made of a _{(Ti x, Al y, Cr} z),
0.02 ≦ x ≦ 0.30,
0.55 ≦ y ≦ 0.765,
0.06 ≦ z,
x + y + z = 1
(X, y, and z represent atomic ratios of Ti, Al, and Cr, respectively, the same applies below),
Or 0.02 ≦ x ≦ 0.175,
0.765 ≦ y,
4 (y−0.75) ≦ z,
x + y + z = 1
It is preferable to use one that satisfies the above.

  Even if the component composition of the target is satisfied, if the component composition distribution of the target varies, the component composition distribution of the resulting hard coating also becomes non-uniform, and the wear resistance of the coating is partially different. End up. In addition, if there is variation in the component composition distribution of the target, differences in local electrical conductivity, melting point, and the like occur in the target, which makes the discharge state unstable and does not form a film well. Therefore, the target of the present invention preferably has a variation in composition distribution within 0.5 at%.

  Furthermore, the present inventors have determined that the content of impurities (oxygen, hydrogen, chlorine, copper, and magnesium) inevitably mixed in the target due to the raw material used for target production or the atmosphere during target production is film formation. The influence on the discharge state at the time was also investigated.

  As a result, if a large amount of oxygen, hydrogen and chlorine is contained in the target, these gases are suddenly generated from the target during film formation, and the discharge state becomes unstable or in the worst case the target itself. It was found that the film was damaged and the film was not formed well. Therefore, oxygen contained in the target should be suppressed to 0.3% by mass or less, hydrogen to 0.05% by mass or less, and chlorine to 0.2% by mass or less. More preferably, oxygen is controlled to 0.2% by mass or less, hydrogen to 0.02% by mass or less, and chlorine to 0.15% by mass or less.

  Also, since copper and magnesium have higher vapor pressures and are more easily vaporized than Ti, Al and Cr constituting the target of the present invention, when they are contained in a large amount, they are gasified at the time of target production and have voids inside the target. It is formed, and the discharge state at the time of film formation becomes unstable due to such defects. Therefore, the content of copper contained in the target is preferably suppressed to 0.05% by mass or less, and more preferably 0.02% by mass or less. Moreover, it is preferable to suppress content of magnesium to 0.03 mass% or less, More preferably, it is 0.02 mass% or less.

  Examples of a method for reducing the content of such impurities to the range specified in the present invention include, for example, vacuum melting of the raw material powder and blending and mixing of the raw material powder in a clean atmosphere.

  By the way, although this invention does not specify even about the manufacturing method of a target, for example, the raw material Ti powder, Cr powder, and Al powder which adjusted the amount ratio, the particle size, etc. appropriately are uniformly made with a V-type mixer etc. An effective method for obtaining the target of the present invention is to apply a cold isostatic pressing process (CIP process) or a hot isostatic pressing process (HIP process) to the mixed powder after mixing. . In addition to these methods, the target of the present invention can also be produced by a hot extrusion method, an ultra-high pressure hot press method, or the like.

  In addition, after preparing mixed powder as mentioned above, the method of manufacturing a target by hot press processing (HP) is also mentioned, but in this method, since Cr used in the present invention is a refractory metal, the relative density There is a problem that it is difficult to obtain a high target. In addition to the method of manufacturing using a mixed powder as described above, a method of obtaining a target by performing a CIP process or a HIP process using a powder that has been alloyed in advance, or by dissolving and solidifying the powder is also included. However, the method of performing CIP treatment or HIP treatment using the alloyed powder has an advantage that a target having a uniform composition can be obtained. However, since the alloy powder is difficult to sinter, it is difficult to obtain a high-density target. There is a problem. In addition, the latter method of melting and solidifying the alloyed powder has an advantage that a target having a relatively uniform composition can be obtained. However, there is a problem that cracks and shrinkage cavities are easily generated during solidification, and the target of the present invention is used. Difficult to get.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

[Example 1]
A target alloy made of Ti, Cr, Al is attached to the cathode of the AIP apparatus shown in FIG. 2, and a cemented carbide chip, a cemented carbide square end mill (diameter 10 mm) as a substrate (object to be processed) on a support base. 2 blades) and platinum foil (0.1 mm thickness) were attached. And after evacuating the inside of the chamber, the temperature of the object to be processed is heated to 400 ° C. with a heater in the chamber to obtain a vacuum degree of 3 × 10 ⁻³ Pa or less, and then in an Ar gas atmosphere of 0.66 Pa. Then, a bias voltage of 700 V was applied to the substrate (object to be processed), and the substrate was cleaned with Ar ions for 10 minutes. Thereafter, nitrogen gas was introduced, arc discharge was started with the pressure in the chamber being 2.66 Pa and the arc current being 100 A, and a film having a thickness of 4 μm was formed on the surface of the substrate (object to be processed). During the film formation, a bias voltage of 150 V was applied to the substrate (object to be processed) so that the substrate (object to be processed) had a negative potential with respect to the ground potential.

After the film formation, the metal component composition in the film, the crystal structure of the film, the Vickers hardness and the oxidation start temperature were examined. The Vickers hardness was measured using a micro Vickers hardness measuring instrument with a load of 0.25 N and a holding time of 15 seconds. The component composition of Ti, Cr, and Al in the film was measured by EPMA. The amount of impurity elements such as O and C excluding metal elements and N in the film was at a level of 1 at% or less for oxygen and 2 at% or less for carbon in the quantitative analysis by the EPMA. The crystal structure of the film was identified by X-ray diffraction. The oxidation start temperature is a temperature at which a weight change occurs when a platinum sample is heated in an artificial dry air with a thermobalance at a rate of temperature increase of 5 ° C./min. did. The value of the formula (4) was determined by measuring the peak intensity of each crystal plane using K _alpha ray of Cu by X-ray diffraction apparatus as described above. Table 1 shows the component composition, crystal structure, Vickers hardness, oxidation start temperature, and value of the formula (4) of the obtained film.

  From Table 1, No. The film hardness of TiAlN (0.56 ≦ Al ≦ 0.75) shown in 21, 22 and 23 is 2700 to 3050 and the oxidation start temperature is 800 to 850 ° C. It cannot be raised. In contrast, No. 1 satisfying the component composition range of the present invention. In 1-17, high Vickers hardness and oxidation start temperature could be achieved simultaneously.

  FIG. 8 is a composition diagram of the metal components Ti, Al, and Cr in the (Ti, Al, Cr) N film, and the range of the present invention and Examples 1 to 27 are shown, but as shown by ●, ▲ and ■ in FIG. Nos. 1 to 17 were able to simultaneously achieve the high hardness and high oxidation start temperature indicated by TiAlN (0.56 ≦ Al ≦ 0.75). In particular, No. No. in the preferred component composition range indicated by ▪ in FIG. Nos. 3 to 5 have an oxidation start temperature almost equal to that of TiAlN (0.56 ≦ Al ≦ 0.75) and extremely high hardness. Nos. 15 to 17 resulted in a high oxidation start temperature with a hardness equivalent to the highest level of TiAlN (0.56 ≦ Al ≦ 0.75).

  In addition, No. in the more preferable component composition range indicated by ● in FIG. 6 to 9 and 10 to 14 can achieve the highest hardness and the highest oxidation start temperature that could not be realized by conventional TiAlN (0.56 ≦ Al ≦ 0.75). Thus, the wear resistance higher than that of the TiAlN (0.56 ≦ Al ≦ 0.75) film can be exhibited.

  On the other hand, No. which does not satisfy the prescribed component composition of the present invention indicated by ○ in FIG. 18 to 20 and 24 to 27 do not indicate high Vickers hardness and oxidation start temperature at the same time, and are similar to or lower than the above TiAlN (0.56 ≦ Al ≦ 0.75). Wear resistance superior to .56 ≦ Al ≦ 0.75) cannot be expected.

[Example 2]
Of the end mills coated with the hard coating obtained in Example 1, No. A cutting test was conducted on 1, 4, 7, 11, 16, 18, 19, 22, 24 and 27 to evaluate wear. SKD61 hardened steel (HRC50) was used as the work material. Cutting conditions are as follows. In the wear evaluation, the work width was measured by observing the cutting edge with an optical microscope after cutting the work material by 20 m using each of the end mills. The results are shown in Table 2.
Cutting conditions Cutting speed: 200 m / min
Feeding speed: 0.07mm / blade Cutting depth: 5mm
Pick feed: 1mm
Cutting oil: Air blow only Cutting direction: Down cut

  From Table 2, No. coated with a film satisfying the requirements of the present invention. The 1, 4, 7, 11 and 16 end mills are No. 1 coated with a coating which does not satisfy the requirements of the present invention. It can be seen that the wear width is small compared to the end mills of 18, 19, 22, 24 and 27 and the wear resistance is excellent.

[Example 3]
A cemented carbide square end mill (same as in Example 1 above) except that an alloy target having a composition of Ti: 9 at%, Cr: 19 at%, Al: 72 at% was used and the film formation time was changed. TiCrAlN films having various film thicknesses shown in Table 3 were formed on a 10 mm diameter and two blades). At this time, the evaporation source shown in FIG. 4 was used as the evaporation source. The bias voltage during film formation was 100V. The composition of the metal component of the obtained film was analyzed by EPMA. The results were Ti: 10 at%, Cr: 20 at%, and Al: 70 at%. The abrasion resistance of the end mill after film formation was evaluated by performing a cutting test in the same manner as in Example 2. The results are also shown in Table 3.

  From Table 3, No. of the film thickness which is preferable in the present invention. Nos. 1 to 5 have a small wear width and excellent wear resistance. No. 6 was inferior in wear resistance because of its thin film thickness. No. In No. 7, the cutting edge was lost during cutting because the film thickness was too thick.

[Example 4]
Using an alloy target with a composition of Ti: 13 at%, Cr: 15 at%, Al: 72 at%, a cemented carbide chip as a workpiece on a support base, a cemented carbide square end mill (diameter 10 mm, 2 blades) And platinum foil (0.1 mm thickness) was attached to the AIP apparatus shown in the said FIG. 2, and the inside of a chamber was made into the vacuum state. Thereafter, the temperature of the object to be processed is heated to 550 ° C. with a heater in the chamber, a mixed gas of nitrogen and methane is introduced, the pressure in the chamber is set to 2.66 Pa, and arc discharge is started at an arc current of 100 A, A (TiAlCr) (CN) film having a thickness of 3 μm was formed on the surface of the substrate (object to be processed). During film formation, a bias voltage of 150 V was applied to the substrate (object to be processed) so that the substrate (object to be processed) had a negative potential with respect to the ground potential. Other film forming conditions are the same as those in the first embodiment.

  After completion of the film formation, the metal component composition, oxidation start temperature and wear resistance in the film were examined. The component composition of Ti, Al, and Cr in the obtained film was measured by EPMA. The amount of impurity elements in the film excluding metallic elements and C and N was oxygen at a level of 1 at% or less in the quantitative analysis by EPMA. The oxidation start temperature was measured in the same manner as in Example 1. The wear resistance of the end mill after film formation was evaluated by performing a cutting test in the same manner as in Example 2. These results are also shown in Table 4.

  From Table 4, No. 1 coated with a film satisfying the requirements of the present invention. No. 1 to No. 3 in which the ratio of C and N in the (TiAlCr) (CN) coating is out of the scope of the present invention. 4 shows that the oxidation start temperature is high, the wear width in the cutting test is small, and the wear resistance is excellent compared with the end mill of No. 4.

[Example 5]
An alloy target having a composition of Ti: 9 at%, Cr: 19 at%, Al: 72 at% was used, and a cemented carbide end mill (diameter: 10 mm, 2 blades) was used as a base material (object to be processed) in the same manner as in Example 1 above. The following film was formed.

That is, (Ti, Al, Cr) N films having different crystal orientations were formed by changing the bias voltage, the film formation temperature, etc., and using (nitrogen + methane) gas as the film formation gas, (Ti, Al, Cr) (CN) films with different ratios were formed. Further, a laminated film of (Ti, Al, Cr) N film and Ti ₅₀ Al ₅₀ N film was formed. Experiment No. shown in Table 5 No. 8 was obtained by forming a (Ti, Cr, Al) (CN) film on the cemented carbide end mill surface and further forming a Ti ₅₀ Al ₅₀ N film. No. 9 is obtained by alternately laminating 10 layers of (Ti, Cr, Al) (CN) coating and Ti ₅₀ Al ₅₀ N coating on the surface of the cemented carbide end mill. The total film thickness was about 3 μm. The abrasion resistance of the obtained film was evaluated by a wear width by performing a cutting test in the same manner as in Example 2.

  From Table 5, Experiment No. In 3, 6 and 7, since the wear width in the wear test is large, the crystal orientation and the ratio of C and N in the (Ti, Al, Cr) (CN) film should be controlled to satisfy the requirements of the present invention. Thus, it can be seen that a hard film having more excellent wear resistance can be obtained.

[Example 6]
Using an alloy target having a composition of Ti: 10 at%, Cr: 18 at%, Al: 72 at%, and using the AIP apparatus shown in FIG. 2, the bias voltage, substrate temperature, By changing the nitrogen gas pressure, a (Ti, Al, Cr) N film having a film thickness of about 3 μm was formed on a cemented carbide square end mill (diameter 10 mm, two blades) or a cemented carbide chip. The arc current during film formation was 150 A, and other film formation conditions were the same as in Example 1.

  After completion of the film formation, the metal component composition, crystal structure, crystal orientation, diffraction angle and half-value width of the diffraction line of the (111) plane of the rock salt structure type, Vickers hardness and wear resistance were examined. Crystal structure, crystal orientation, diffraction angle and half width of diffraction line of (111) plane of rock salt structure type were measured by X-ray diffraction of θ-2θ method using Kα of Cu. Abrasion resistance was evaluated by a wear width by performing a cutting test in the same manner as in Example 2. The metal component composition of the obtained film was measured by EPMA. As a result, as shown in Table 7, it was found that the component composition was slightly different within the ranges of Ti: 10 to 12 at%, Cr: 10 to 23 at%, and Al: 66 to 68 at% depending on the film forming conditions. These results are shown in Tables 6 and 7. The amount of metallic elements and impurity elements other than nitrogen in the film was at a level of 1 atomic% or less for oxygen and 2 atomic% or less for carbon in the quantitative analysis by EPMA. Further, the ratio of the total amount of metal elements and nitrogen was in the range of 0.9 to 1.1 in terms of atomic ratio.

  From Tables 6 and 7, No. 1 controlled to the substrate voltage, reaction gas pressure, and substrate temperature, which are preferable in the present invention. 1-6, 9-12, and 15-17 are No.1. Compared with 7, 8, 13, 14, and 18, the film has a high hardness, a small wear width, and excellent wear resistance. It can be seen that the crystal orientation, the angle of the diffraction line, and the half-value width can be within the preferable ranges in the present invention, and as a result, a film having excellent wear resistance can be obtained.

[Example 7]
Using an alloy target having a composition of Ti: 10 at%, Cr: 18 at%, Al: 72 at%, using the AIP apparatus shown in FIG. 2 (however, in this case, two evaporation sources 2 are installed) The arc current is 100 to 150 A, the nitrogen (or mixed nitrogen and methane) gas pressure is 0 Pa (metal film) to 2.66 Pa, and the bias voltage applied to the substrate is 30 to 150 V depending on the film type. Varying, substrate temperature is set to 550 ° C., and various metal nitride, carbide, carbonitride or metal film laminated films shown in Table 8 are formed on a cemented carbide square end mill (diameter 10 mm, 2 blades). did. Other film forming conditions are the same as those in the first embodiment. The method of lamination was such that the film thicknesses shown in Table 8 were laminated on the cemented carbide end mill in the order of film 1 in Table 8 and then film 2 in Table 8 by alternately switching the evaporation source. The number of layers shown in Table 8 indicates the number of repetitions when [Coating 1 + Coating 2] is taken as 1 unit. The total film thickness was about 3 μm. The abrasion resistance of the film after film formation was evaluated by performing a cutting test in the same manner as in Example 2. These results are shown in Table 8.

  Experiment No. in Table 8 From 1 to 12, even when the hard film for a cutting tool is formed in a plurality of layers, if the film satisfying the requirements of the present invention is coated, the wear width of the cutting test is excellent at 30 μm or less. It can be seen that

[Example 8]
Using an alloy target having a composition of Ti: 9 at%, Cr: 19 at%, Al: 72 at%, the arc current is 100 A, the substrate (object to be processed) temperature is 500 ° C., and the substrate (object to be processed) with respect to the ground potential. A cemented carbide tip or a cemented carbide square end mill (similar to that of Example 1 above) except that the film was formed for 30 minutes while changing the bias voltage within a range of 50 to 400 V so that the negative side was negative. A film was formed on a 10 mm diameter, two blades). The crystal structure of the obtained film was identified by X-ray diffraction. Moreover, the chip | tip made from the cemented carbide after film-forming was fractured | ruptured, the cross section was observed with the scanning electron microscope, and the film thickness was measured. Further, a cutting test was performed in the same manner as in Example 2. These results are shown in Table 9. In addition, when the metal element composition of the obtained film was measured by EMPA, it was within the range of Ti: 9 to 11 at%, Cr: 19 to 21 at%, Al: 68 to 71 at% due to the difference in bias voltage during film formation. It was found that the component composition was slightly different.

  From Table 9, No. Nos. 2 to 5 are within the bias voltage range preferable in the present invention, and an optimum crystal structure or film thickness can be obtained by forming a film with such a bias voltage. In contrast, no. Since 1 is lower than the bias voltage that is preferable in the present invention, the crystal structure becomes a mixed phase of B1 + Hex, and excellent wear resistance cannot be expected. No. Nos. 6 and 7 are higher than the bias voltage preferred in the present invention, and the film thickness is thin or hardly formed, so that excellent wear resistance cannot be expected. As for the result of the cutting test, it can be seen that the film formed with the bias voltage desired in the present invention has a small wear amount and excellent cutting performance.

[Example 9]
Using an alloy target having a composition of Ti: 10 at%, Cr: 18 at%, Al: 72 at%, an alloy target of Ti: 50 at%, Al: 50 at%, or a target of pure Ti metal or pure Cr metal, FIG. Using the AIP apparatus shown, a TiAlCrN, TiAlN, TiN or CrN film having a film thickness of about 3 μm is formed on a cemented carbide tip and a cemented carbide ball end mill (diameter 10 mm, center radius 5R, 2 blades). did. The bias voltage applied to the substrate is 150 V when forming a TiAlCrN film, 50 V when forming a TiAlN, TiN, or CrN film, the substrate temperature is in the range of 550 to 580 ° C., the pressure of the reactive gas (nitrogen) is 2.66 Pa, and the arc The current was 150A. Other film forming conditions are the same as those in Example 1.

After the film formation was completed, the metal component composition, Vickers hardness, and wear resistance of the obtained film were examined. The wear resistance was evaluated based on the wear width at the tip of the ball end mill and the wear width at the boundary by performing a cutting test under the following conditions. As a result of measuring the component composition by EPMA, the component composition of the TiCrAlN film and the TiAlN film formed using the alloy target is slightly different from the component composition of the target, and each has a slightly smaller amount of Al (Ti _0.1 Cr) than the target. _Films with compositions of _0.22 Al _0.68 ) N and (Ti _0.54 Al _0.46 ) N were obtained. Moreover, the ratio of the metal element and nitrogen atom in the film was within a range of 0.9 to 1.1 in terms of atomic ratio in any film.
Cutting test conditions Work material: S55C (Brinell hardness 220)
Cutting speed: 100 m / min Feed rate: 0.05 mm / blade Depth cut: 4.5 mm
Pick feed: 0.5mm
Others: Down cut, air blow Cutting length: 30m

  From Table 10, the film satisfying the requirements of the present invention is smaller in the tip wear amount and the boundary wear amount in the cutting test than the conventionally known TiAlN, TiN, and CrN films, and the material to be cut; S55C It can be seen that excellent cutting characteristics are exhibited with respect to (HB220).

[Example 10]
The influence of the relative density and impurity content of the target on the discharge state during film formation was investigated.

Predetermined amounts of Ti powder, Cr powder and Al powder of 100 mesh or less were mixed, and HIP treatment was performed under the conditions of temperature: 900 ° C. and pressure: 8 × 10 ⁷ Pa, and targets of each component composition shown in Table 11 were obtained. Produced. The component composition of the target was measured by ICP-MS. In addition, in order to investigate the discharge characteristics of the obtained target, a target formed to have an outer diameter of 254 mm and a thickness of 5 mm is mounted on a sputtering apparatus, and a film having a film thickness of 3 μm is manufactured by a cemented carbide alloy to be processed by reactive sputtering A film was formed on the chip. The film formation was performed at an output of 500 W using N ₂ gas as a reaction gas.

  The component composition of the obtained hard film was measured by XPS, and the wear resistance was evaluated by conducting a cutting test under the following conditions. The discharge state during film formation was performed by visually observing the discharge state on the surface or observing the discharge voltage monitor. These results are shown in Table 11.

Cutting test conditions Work material: SKD61 (HRC50)
End mill: Cemented carbide 4 blades Cutting speed: 200m / min
Cutting depth: 1mm
Feed rate: 0.05mm / blade Cutting length: 20m
Evaluation criteria A: Rake face wear depth is less than 25 μm B: Rake face wear depth is 25-50 μm
Δ: Rake face wear depth of 50 μm or more Discharge state • Stable: No instantaneous rise in discharge voltage or local bias in discharge
・ Slightly unstable: Some momentary increase in discharge voltage and / or local bias in discharge
・ Unstable: Instantaneous rise in discharge voltage and local bias in discharge are recognized.
・ Discharge interruption: Discharge stops

  From Table 11, No. Nos. 1 to 7 satisfy the relative density specified in the present invention, so that the discharge state is good. As a result, a film having the same composition as the target and exhibiting good wear resistance is obtained. I understand that. In contrast, no. 8-10, since the relative density of the target does not satisfy the requirements of the present invention, the discharge state is unstable or cannot be continued. As a result, the component composition of the resulting film is the same as the component composition of the target. The result was that the film was greatly deviated and an unfavorable wear resistance film was obtained.

[Example 11]
A predetermined amount of Ti powder of 100 mesh or less, Cr powder of 100 mesh or less, and Al powder of 240 mesh or less were mixed and subjected to HIP treatment under conditions of temperature: 500 to 900 ° C. and pressure: 8 × 10 ⁷ Pa. Table 12 The target of each component composition shown in FIG. The obtained target is cut out or a copper backing plate is brazed to produce a target having a fixed collar having an outer diameter of 104 mm and a thickness of 2 mm on the bottom surface. A target was mounted, and a film having a thickness of 3 μm was formed on a cemented carbide chip as the object to be processed. The film formation was performed using N ₂ gas or N ₂ / CH ₄ gas as a reaction gas, the temperature of the object to be processed being 500 ° C., the arc current being 100 A, and the bias voltage of the object to be processed being 150 V.

  The component composition of the target was measured by ICP-MS. The abrasion resistance of the obtained film was evaluated by the same cutting test method as in Example 6. Moreover, when the component composition of the obtained film | membrane was measured by XPS, the component composition of any film | membrane was in the range of +/- 2at% of the component composition of a target, and was substantially corresponded with the component composition of a target. The presence / absence of defects (holes) in the target and the measurement of the hole size were measured by an ultrasonic flaw detection method. The discharge state during film formation was evaluated by the same method as in Example 6. These results are shown in Table 12.

  From Table 12, no. 1 to 10, since the relative density of the target and the size of the holes present in the target satisfy the requirements defined in the present invention, the discharge state during the film formation is stable, and good wear resistance It turns out that the film | membrane which has is obtained.

  In contrast, no. In Nos. 5 and 7, the size of the holes present in the target does not satisfy the definition of the present invention. Nos. 9 and 10 indicate that the relative density of the target does not satisfy the provisions of the present invention. Nos. 6 and 8 satisfy neither the relative density of the target defined in the present invention nor the size of the vacancies existing in the target, so that the discharge state becomes unstable or interrupted during the film formation. It became impossible or even when the film was obtained, the abrasion resistance was poor.

[Example 12]
Next, the influence of the content of impurities (oxygen, hydrogen, chlorine, copper and magnesium) in the target on the discharge state during film formation was investigated.

Targets having respective component compositions shown in Table 13 were produced in the same manner as in Example 7. The relative density of the obtained targets was 99% or more, and there were no vacancies of 0.3 mm or more or continuous defects. Using the obtained target, a film was formed under the same conditions as in Example 7 except that only N ₂ gas was used as the reaction gas. The content of impurities in the target was measured by atomic absorption method. The discharge state during film formation was evaluated in the same manner as in Example 6. These results are shown in Table 13.

  From Table 13, No. 1,3-9,16 and 17 have good discharge conditions because the contents of all impurities of oxygen, hydrogen, chlorine, copper and magnesium satisfy the requirements of the present invention. I understand. In contrast, no. 2, 10 and 11, the oxygen content, No. No. 12, hydrogen content, no. In No. 13, the chlorine content, no. In No. 14, the copper content, no. 15, the magnesium content, No. 18 contains oxygen and magnesium contents. In No. 19, the contents of chlorine, copper and magnesium exceed the specified range preferred in the present invention. From this result, in order to obtain a hard film for a cutting tool of the present invention efficiently by improving the discharge state during film formation, the content of impurities (oxygen, hydrogen, chlorine, copper and magnesium) in the target is determined according to the present invention. It can be seen that it is preferable to be within the specified range.

The range of the present invention is shown in the composition diagram of the metal components Ti, Al and Cr in the (Ti, Al, Cr) N film. It is the schematic which showed an example of the arc ion plating (AIP) apparatus used for implementation of this invention. It is the cross-sectional schematic which expanded an example of the arc type evaporation source principal part with which this invention is implemented. It is the cross-sectional schematic which expanded another arc type evaporation source principal part with which it uses for implementation of this invention. It is the cross-sectional schematic which expanded an example of the arc type evaporation source principal part with which implementation of the conventional this invention was carried out. The X-ray diffraction result of the (Ti _0.1 Al _0.7 Cr _0.2 ) N film formed is shown, (1) is the evaporation source of the present inventors, and (2) is the film formation using a conventional evaporation source. The results are shown. As an example, it is a graph showing the relationship between the substrate (object to be processed) temperature and the residual stress of the film when a (Ti _0.1 Al _0.7 Cr _0.2 ) N film is formed. The scope and examples of the present invention are shown in the composition diagrams of the metal components Ti, Al and Cr in the (Ti, Al, Cr) N film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum vessel 2, 2A Arc type evaporation source 3 Support stand 4 Bias power supply 6 Target 7 Arc power supply 8 Magnet (magnetic field formation means)
9 Electromagnet (magnetic field forming means)
11 Exhaust port 12 Gas supply port W Processed object S Target evaporation surface

Claims (4)

In arc ion plating method for performing evaporation and ionization of the metal constituting the data Getto by arc discharge to form a magnetic lines of force traveling diverging or parallel to the front and substantially perpendicular to the evaporation surface of the target, the this magnetic field lines The film formation gas in the vicinity of the processing object is promoted into plasma, and the following hard film is formed by setting the bias potential applied to the object to be processed to −50 V to −300 V with respect to the ground potential. method of manufacturing a hard substance coating that.
A hard film made of (Ti _a , Al _b , Cr _c ) (C _1-d N _d ),
A, b, c, d above
0.02 ≦ a ≦ 0.30,
0.6 ≦ b ≦ 0.765,
0.06 ≦ c,
a + b + c = 1,
0.5 ≦ d ≦ 1
(A, b, and c represent the atomic ratio of Ti, Al, and Cr, respectively, d represents the atomic ratio of N, and so on)
Or 0.02 ≦ a ≦ 0.175,
0.765 ≦ b,
4 (b−0.75) ≦ c,
a + b + c = 1,
0.5 ≦ d ≦ 1 is satisfied, and the crystal structure is mainly composed of a rock salt structure type. The method for producing a hard film according to claim 1, wherein the hard film constitutes an outermost surface of the hard film. The method for producing a hard coating according to claim 1, wherein the hard coating is for a cutting tool. Wherein with the workpiece temperature to 300 ° C. or higher 800 ° C. or less during the film formation, to any one of claims 1 to 3 for the partial pressure or total pressure of the reaction gas during the deposition and less than 0.5 Pa 7 Pa method for producing a hard substance coating according.

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