阅读说明：本技术 被覆模具、被覆模具的制造方法及硬质皮膜形成用靶 (Coated mold, method for producing coated mold, and target for forming hard coating ) 是由 庄司辰也 本多史明 于 2020-03-18 设计创作，主要内容包括：提供一种能够发挥良好的滑动特性,进一步减少微滴且耐久性也优异的被覆模具。一种被覆模具、被覆模具的制造方法,所述被覆模具在作业面具有硬质皮膜,所述硬质皮膜包括A层,所述A层是a1层与a2层交替层叠而成,所述a1层是Cr系氮化物且厚度为100nm以下,所述a2层包含(V-(1-a)M-(a))(M是选自Mo、W中的至少一种)的氮化物或碳氮化物,M相对于V与M的合计的原子比a为0.05以上且0.45以下,且厚度为80nm以下。另外,提供一种硬质皮膜形成用靶,其可用于所述被覆模具的制造方法中。(Provided is a coated mold which can exhibit good sliding properties, can reduce droplets, and has excellent durability. A coated mold having a hard coating on a working surface, the hard coating comprising a layer A comprising a layer a1 and a layer a2 laminated alternately, the layer a1 being a Cr-based nitride and having a thickness of 100nm or less, the layer a2 comprising (V) and a method for producing a coated mold 1‑a M a ) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 80nm or less. Further, a target for forming a hard coating film is provided, which can be used inThe method for manufacturing the coated mold.)

1. A coated mold having a hard coating film on a working surface, wherein,

the hard coating comprises an A layer which is formed by alternately laminating a1 layer and a2 layer, wherein the a1 layer is Cr nitride and has a thickness of 100nm or less,

the a2 layer contains (V)_1-aM_a) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 80nm or less.

2. A coated mold according to claim 1, further comprising a B layer formed on the upper layer of the a layer and containing (V)_1-aM_a) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 0.1 μ M or more.

3. The coated mold according to claim 1 or 2, wherein the A layer of the hard film has a Young's modulus of 250GPa or more and a nanoindentation hardness of 25GPa or more.

4. A method for manufacturing a coated mold having a hard coating film on a working surface, comprising:

a step of coating an A layer in which a1 layers and a2 layers are alternately laminated, the a1 layer is a Cr-based nitride and has a thickness of 100nm or less,

the a2 layer contains (V)_1-aM_a) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 80nm or less;

the layer a2 uses a target for forming a hard coating film, and the target for forming a hard coating film contains (V)_1-aM_a) (M is at least one selected from Mo and W), and the atomic ratio a of M to the total of V and M is 0.05 to 0.45.

5. The method of manufacturing a covered mold according to claim 4, further comprising:

a step of coating the layer A with a layer B containing (V)_1-aM_a) (M is at least one selected from Mo and W), the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 0.1 μ M or more,

the layer B is a target for forming a hard coating, and the target for forming a hard coating contains (V)_1-aM_a) (M is at least one selected from Mo and W), and the atomic ratio a of M to the total of V and M is 0.05 to 0.45.

6. A target for forming a hard coating film, comprising (V)_1-aM_a) (M is at least one selected from Mo and W), and the atomic ratio a of M to the total of V and M is 0.05 to 0.45.

Technical Field

The present invention relates to a coated mold coated with a hard coating, a method for manufacturing the coated mold, and a target for forming the hard coating.

Background

Conventionally, in plastic working such as forging and press working, a die using a tool steel such as cold die steel, hot die steel, and high-speed steel, a cemented carbide, or the like as a base material has been used. In plastic working using such a press-working or forging die, since the working surface of the die slides against the workpiece, wear such as abrasion or seizure easily occurs on the working surface of the die, and it is desired to increase the life of the die. In particular, a bending die or a drawing die applies a high forming pressure, and the material to be processed is likely to be engaged with the die by sliding. The term "bite" as used herein refers to a phenomenon in which a chemically active surface is formed on the working surface of either or both of the members sliding against each other, and the chemically active surface is firmly aggregated and fixed to the target side, or a structural material on either surface is peeled off and transferred to the target side. Therefore, a die used for a bending die or a drawing die is particularly required to have a high level of strength and seizure resistance.

As a method for improving seizure resistance of a mold, it is effective to form a hard film containing a nitride or a carbide by surface treatment. As the surface treatment, a molten salt immersion method (hereinafter, referred to as a thermal-reactive deposition and diffusion (TRD) method), a chemical vapor deposition method (hereinafter, referred to as a Chemical Vapor Deposition (CVD) method), a physical vapor deposition method (hereinafter, referred to as a Physical Vapor Deposition (PVD) method), or the like can be used. The TRD method or the CVD method is used by performing treatment at a temperature close to the quenching temperature of a mold made of steel as a base material and then tempering (partially re-quenching before that), but there is a problem that the mold is deformed or dimensionally changed by the high-temperature treatment. Further, although these treatments are repeatedly used, the TRD method or the CVD method uses carbon in the steel material of the mold base material to produce a film, and therefore, if the treatment is repeatedly performed, carbon in the vicinity of the surface of the mold is reduced, which may cause a decrease in hardness or a decrease in adhesion to the film. On the other hand, in the PVD method, since the coating temperature is lower than the tempering temperature of the steel in various coating forming methods, the softening of the mold due to the coating is small, and the deformation and dimensional change of the mold are not easily generated. As PVD coatings for improving the wear resistance of a mold, titanium (Ti) -based coatings such as TiN, TiCN, TiAlN, chromium (Cr) -based coatings such as CrN, cran, AlCrN, and vanadium (V) -based coatings such as VCN, VC, and the like have been conventionally applied.

Various studies have been made on a coated mold to which the coating film is applied. For example, the applicant of patent document 1 proposes a coated tool coated with a hard film in which nitrides of AlCrSi and nitrides of V are alternately laminated, for the purpose of improving sliding characteristics such as wear resistance and seizure resistance in a sliding environment with a workpiece. In addition, the applicant of patent document 2 proposes a coated member having excellent sliding characteristics, which includes an a1 layer containing a nitride or carbonitride in which chromium is 30% or more in terms of an atomic ratio of a metal portion of a coating film and a2 layer containing a nitride or carbonitride in which vanadium is 60% or more in terms of an atomic ratio of a metal portion, and a B layer located on an upper layer of the a layer and containing a nitride or carbonitride in which vanadium is 60% or more in terms of an atomic ratio of a metal portion, and which is provided for the purpose of improving wear resistance or seizure resistance of a mold.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-183545

Patent document 2: international publication No. 2013/047548

Disclosure of Invention

Problems to be solved by the invention

In recent years, in order to cope with a case where a workpiece has higher strength or a case where a workpiece is processed under a severe environment such as a hot press method in which a workpiece is heated and press-formed and tempered at the same time, a film for a die is also required to have further improved durability. On the other hand, in particular, the arc ion plating method inevitably forms droplets (droplets) in the film and on the film surface. The droplets are a factor of film damage such as reduction in adhesion of the film and cracks, and therefore, in order to improve durability, it is necessary to reduce the droplets. The coated tool described in patent document 1 or patent document 2 discloses an excellent technique in which a nitride of V having excellent sliding properties is contained in a hard film, and a smooth film structure in which a protruding portion of a film surface that is a starting point of attacking a workpiece is reduced, and which has excellent sliding properties. However, regarding the reduction of droplets, only smoothing the surface of the coating film is described, and there is no description or suggestion of reduction of droplets in the film, and therefore, there is room for further improvement of durability. In view of the above problems, an object of the present invention is to provide a coated mold that can exhibit good sliding properties and has excellent durability by further reducing droplets.

Means for solving the problems

The present inventors have made extensive studies and, as a result, have found an element and a film structure that can reduce droplets, and have arrived at the present invention.

That is, one embodiment of the present invention is a coated mold having a hard coating film on a working surface, wherein,

the hard coating comprises an A layer which is formed by alternately laminating a1 layer and a2 layer, wherein the a1 layer is Cr nitride and has a thickness of 100nm or less,

the a2 layer contains (V)_1-aM_a) (M is at least one selected from molybdenum (Mo) and tungsten (W)), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 80nm or less.

Preferably further comprises a B layer formed on the upper layer of the A layer and containing (V)_1-aM_a) (M is at least one selected from Mo and W) or a nitride or carbonitride thereof, and M isThe atomic ratio a to the total of V and M is 0.05 to 0.45, and the thickness is 0.1 μ M or more.

Preferably, the A layer of the hard film has a Young's modulus of 250GPa or more and a nanoindentation hardness of 25GPa or more.

Another aspect of the present invention is a method for manufacturing a coated mold having a hard coating film on a working surface, including:

a step of coating an A layer in which a1 layers and a2 layers are alternately laminated, the a1 layer is a Cr-based nitride and has a thickness of 100nm or less,

the a2 layer contains (V)_1-aM_a) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the target for forming a hard coating is coated with (V)_1-aM_a) The nitride or carbonitride of (2), wherein the atomic ratio a of M to the total of V and M is 0.05 or more and 0.45 or less, and the thickness is 80nm or less.

Preferably, the method further comprises a step of coating a layer A with a layer B containing (V)_1-aM_a) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the target for forming a hard coating is coated with (V)_1-aM_a) The nitride or carbonitride of (2), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 0.1 μ M or more.

Still another embodiment of the present invention is a target for forming a hard coating, comprising (V)_1-aM_a) (M is at least one selected from Mo and W), and the atomic ratio a of M to the total of V and M is 0.05 to 0.45.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a coated mold having a hard coating film which can exhibit good sliding properties and has excellent durability by reducing droplets can be provided. Further, a target suitable for forming the hard coating can be provided.

Drawings

FIG. 1 is an image of the surface of a sample of an example of the present invention observed with an optical microscope.

Fig. 2 is an image of the surface of a sample of a comparative example observed with an optical microscope.

Fig. 3 is an image of the surface of a sample of an example of the present invention observed with an Electron Probe Microanalyzer (EPMA).

Fig. 4 is an image of the surface of a sample of a comparative example observed by EPMA.

Fig. 5 is a schematic top surface view of the sliding test apparatus used in the examples.

FIG. 6 is a side view schematically showing a slide test apparatus used in the examples. Fig. 6(a) is a schematic side view showing a state where the circular plate-like portion is separated from the sample, and fig. 6(b) is a schematic side view showing a state where the circular plate-like portion is in contact with the sample.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the present embodiment. The coated mold of the present embodiment has a hard coating on the working surface. The hard coating film has an alternating lamination part (layer A) in which a1 layers and a2 layers are alternately laminated, the a1 layer is a Cr-based nitride and has a thickness of 100nm or less, and the a2 layer contains (V2 layer)_1-aM_a) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 80nm or less.

The Cr nitride film (hereinafter also referred to as CrN film) as the a1 layer of the present embodiment is excellent in heat resistance and wear resistance, and contributes to improvement of the life of the mold under a high load environment. The CrN-based coating film is a coating film containing 30% or more of Cr in the atomic ratio of the metal portion including the semimetal. If Cr is 30% or more, at least one or two or more of a group iv transition metal, a group v transition metal, a group vi transition metal, Al, Si, and B may be contained in addition to Cr within a range in which the effect of the a1 layer is not impaired. Of course, Cr may be 100%. For example, the CrN-based coating is formed by a coating selected from the group consisting of CrN, CrTiN, CrVN, CrSiN, CrBN, CrSiBN, CrTiSiN, CrVSiN, AlCrN, AlTiCrN, AlVCrN, and,AlCrSiN, AlTiCrSiN, and AlVCrSiN are preferable because they can improve the wear resistance in a high-temperature region. When V is contained in the a1 layer, the content of V contained in the CrN-based film is preferably less than 50%. More preferably AlCrSiN is applied. When the Cr content is less than 30%, the effect of improving the heat resistance and wear resistance tends to be difficult to obtain. The upper limit of the Cr content is not particularly limited, and may be appropriately changed depending on the type and use of the coating. For example, when AlCrSiN is used, the content of Cr may be set to 80% or less in terms of atomic ratio in order to easily obtain an effect of improving heat resistance or wear resistance. Preference is given to using AlCrSiN in the case of Al_xCr_ySi_zIn the composition formula (1), it is preferable to control the composition to 20 ≦ x < 70, 30 ≦ y < 75, and 0 < z < 10 because the brittle hexagonal crystal structure is suppressed mainly, and the wear resistance and heat resistance are stably improved mainly by the cubic crystal structure. The crystal structure can be confirmed by, for example, X-ray diffraction, and if the peak of the cubic crystal structure reaches the maximum intensity, the cubic crystal structure can be regarded as a main body even if other crystal structures are included.

One of the important features of the a2 layer of the present embodiment is: comprises (V)_1-aM_a) (M is at least one selected from Mo and W) or a nitride or carbonitride thereof (hereinafter also referred to as VMN-based coating film). The VMN-based coating film is appropriately oxidized during processing to form an oxide layer, thereby forming a low-melting-point composite oxide containing the component of the material to be processed. Therefore, the material to be processed is prevented from being coagulated, and local seizure and coagulation abrasion at the initial stage of processing are suppressed. On the other hand, since V has a lower thermal conductivity than other metal elements used for the hard coating film, when arc ion plating is performed using a single V target, a microscopic molten pool caused by arc discharge to the V target is large and is likely to be formed deep, and therefore, it is confirmed that the number of droplets generated is large, and the size of the droplets tends to be large. Therefore, in the present embodiment, by using the VMN-based film as described above, droplets can be suppressed to improve the durability of the film without impairing excellent sliding characteristics. In the present embodiment, M is at least one of Mo and WOne kind of the medicine. This is because Mo, W, and V are completely dissolved in a solid solution, and no intermetallic compound is produced, so that discharge can be stably performed during PVD film formation, and a dense film with few defects can be stably coated. Further, since Mo and W have higher melting points and higher thermal conductivities than V, the area of a molten pool formed on the target surface tends to be small as described later, and generation of droplets can be suppressed. Further, by forming a VMN-based coating film containing Mo or W, the young's modulus or hardness can be increased. Increasing the young's modulus and hardness of a hard film improves the resistance to fracture by external force, and contributes to improving the durability of the film in addition to the effect of suppressing droplets. That is, it is preferable that the young's modulus of the a layer of the hard film is 250GPa or more and the nanoindentation hardness is 25GPa or more because the above-mentioned effect of improving durability is more easily obtained. More preferably, the Young's modulus is 300GPa or more, and the indentation hardness is more preferably 30GPa or more.

In the present embodiment, the atomic ratio a of M is 0.05 or more and 0.45 or less. When the atomic ratio of M exceeds 0.45, the film formation rate is liable to decrease, which is not preferable. Further, since V in the alloy is reduced, the effect of suppressing the solidification wear may not be sufficiently exhibited. When the atomic ratio of M is less than 0.05, the effect of V is dominant, and the droplet-suppressing effect cannot be obtained. In addition, at least one or two or more of group iv transition metals, group V transition metals, group vi transition metals, Al, Si, and B may be contained in addition to V, Mo, and W within a range not to impair the effects of the present invention. The upper limit of the atomic ratio a of M is preferably 0.40, and the lower limit of the atomic ratio a of M is preferably 0.1. The upper limit of the atomic ratio a of M is preferably 0.35, and the lower limit of the atomic ratio a of M is preferably 0.15.

In the a1 layer and the a2 layer of the present embodiment, when the total of the metal element and the nonmetal element in the entire film is defined as 100%, the atomic ratio of the nitrogen element in the film is preferably 45% or more and 55% or less. By controlling the nitrogen content within the above range, the heat resistance of the coating film can be further improved.

The hard coating of the present embodiment has a structure in which the above-described a1 layers and a2 layers are alternately stacked. With such a structure, the wear resistance and heat resistance of the CrN-based film and the seizure resistance and coagulation resistance of the VMN-based film can be effectively exhibited without interfering with each other. It is preferable to set the film thickness of the a1 layer to 100nm or less and the film thickness of the a2 layer to 80nm or less because the above characteristics can be exhibited in a well-balanced manner. The film thickness of each of the a1 layer and the a2 layer is more preferably 30nm or less. More preferably 20nm or less, and still more preferably 15nm or less. These film thicknesses can be adjusted by controlling the load power applied to the target, the chamber volume of the apparatus for film formation, the stage rotation speed, and the like. Further, in order to more reliably obtain the effect of improving the wear resistance, the film thicknesses of the a1 layer and the a2 layer are preferably set to 2nm or more.

As described above, in the ranges where the film thickness of the a1 layer is 100nm or less and the film thickness of the a2 layer is 80nm or less, the layers may be stacked at a constant film thickness or may be stacked while varying the film thickness. For example, when the sliding characteristics are emphasized in the case of stacking the layers at a constant thickness, the thickness of the a2 layer may be thicker than that of the a1 layer, and when the wear resistance is emphasized, the thickness of the a1 layer may be thicker than that of the a2 layer. In addition, when the thickness is varied, the inclined or stepwise form can exhibit the effect, and may be appropriately selected according to the purpose. For example, in the case of stepwise change, the PVD coating can be easily manufactured by a general PVD apparatus, and in the case of oblique change, the stress distribution in the coating is stabilized, and delamination is less likely to occur. Here, "obliquely changes" means that at least one of the a1 layer and the a2 layer changes in each layer. The term "stepwise change" means that the a1 layer and the a2 layer contain two or more layers having the same thickness.

For example, when it is desired to improve the sliding characteristics of the coated tool in the early stage of machining and to improve the wear resistance in the middle and subsequent stages of machining, the thickness of the a2 layer may be increased toward the surface layer side, or the thickness of the a1 layer may be decreased toward the surface layer side.

In the present embodiment, in order to further enhance the wear resistance at the middle stage and thereafter of the machining, it is preferable to form a CrN-based film directly below (on the mold side) the alternately laminated portion (a layer). The reason for this is that, as described above, when the wear progresses and reaches the CrN-based film, coagulation is likely to occur, and a sufficient effect of the coagulation resistance may not be exhibited, but by specially coagulating the film on the substrate side, the wear of the film can be detected, and the wear can be suppressed from reaching the substrate. The CrN-based coating is preferably a Cr-based nitride layer having the same composition as that of the a1 layer in terms of industrial production, but may be a Cr-based nitride layer having a composition different from that of the a1 layer. The CrN-based coating film may have a single-layer or multi-layer (including an alternating laminated structure) structure of two or more layers depending on desired characteristics. In particular, when the CrN-based film is formed in an alternate lamination structure, the crack is preferably developed in a complicated path and the rapid development is suppressed because the crack passes through the lamination interface at the time of film breakage, and as a result, the breakage resistance of the film can be improved. Here, in the case where the alternating layered structure of the b1 layer and the b2 layer is selected for the CrN-based coating film directly below the alternating layered portion, the b1 layer and the b2 layer may be selected from CrN, CrTiN, CrVN, CrSiN, CrBN, CrSiBN, CrTiSiN, CrVSiN, AlCrN, AlTiCrN, AlVCrN, AlCrSiN, AlTiCrSiN, and AlVCrSiN.

The total thickness of the CrN-based film formed directly below the alternately laminated portion is preferably 0.5 μm or more, and preferably 50 μm or less. The thickness of the CrN-based film is more preferably 40 μm or less, and the thickness of the CrN-based film is preferably 30 μm or less, 20 μm or less, or 10 μm or less. When the alternating lamination structure of the b1 layer and the b2 layer is selected, the film thicknesses of the b1 layer and the b2 layer are preferably 0.002 μm to 0.1 μm, respectively. The CrN-based coating film formed directly below the alternate laminated portion is preferably formed to be 1.2 times or more thicker than the a1 layer.

In the present embodiment, in order to further improve the affinity between the mold and the workpiece in the initial stage of the processing and to suppress the abrupt engagement, it is preferable to form a B layer including (V) on the upper layer of the alternately laminated part (a layer)_1-aM_a) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 0.1 μ M or more. The layer B also has a VMN-based coating layer having the same composition as the layer a2It is industrially reasonable, and therefore, the layer is preferable, but not limited thereto, and may be a layer having a composition different from that of the a2 layer. The thickness of the B layer is preferably 0.1 μm or more, more preferably 0.2 μm or more. The upper limit of the thickness is not particularly limited, but if the thickness is too large, it takes time to form a film, and productivity is deteriorated, so that it is preferably 8 μm or less. Further, since the wear resistance of the entire film may be lowered depending on the use environment, the film thickness is more preferably 5 μm or less, and still more preferably 3 μm or less. The B layer is preferably formed to be 1.2 times or more thicker than the a2 layer.

The total thickness of the alternately laminated part (layer a) of the present embodiment is preferably 1 μm to 50 μm. More preferably 2 to 30 μm. The reason for this is that: if the thickness is too thin, the wear resistance and the coagulation resistance as described above cannot be sufficiently improved, and the film tends to be worn out early, whereas if the thickness is too thick, the dimensional tolerance of the die is exceeded, the clearance of the molding surface is insufficient, and excessive drawing may be performed, thereby increasing the molding load.

Next, the hard coating film-forming target of the present invention will be described.

The target of the present embodiment is a hard film-forming target having substantially the same composition as the hard film of the present invention, and includes (V) for coating the VMN-based film used for the a2 layer and the B layer of the hard film of the present embodiment_1-aM_a) (M is at least one selected from Mo and W), and the atomic ratio a of M to the total of V and M is 0.05 to 0.45%.

In the target of the present embodiment, at least one of Mo and W is selected as the M element, and therefore, the molten pool area formed on the target surface tends to be smaller than that of the target of V alone, contributing to suppression of droplets. That is, as the molten pool is reduced, droplets generated from the molten pool are reduced, and the number of droplets is also reduced. It is considered that the droplet-suppressing effect exhibited by containing Mo or W having a higher melting point and higher thermal conductivity than V in the target depends on the concentration distribution of the additive element in the target. That is, in the case of manufacturing a target by the powder metallurgy method, the above-described effect is exhibited by distributing the additive element in the target in a scale of about the same size as or smaller than a molten pool (about 10 μm to 200 μm in the present invention) generated by arc discharge, and dividing only the region of V by the additive element. For this reason, in order to improve the dispersibility of the additive element, it is preferable that the particle diameter of the additive element powder is smaller than the particle diameter of the V powder, except that the particle diameter of the V powder as the main component is set to be the same as or smaller than the size of the molten pool. In the case of producing a V alloy target by dissolving a metal, it is preferable to sufficiently diffuse the additive element. When the concentration distribution of the additive element is generated, it is preferable that the dimension of the region of only V be controlled to be equal to or smaller than the dimension (about 10 to 200 μm) of the molten pool formed on the target surface of V alone. Specifically, the evaluation can be performed by determining the concentration distribution by line analysis or element mapping using an Electron Probe Microanalyzer (EPMA) and comparing it with the molten pool.

The content of other elements and impurity elements may be contained in a trace amount (0.1% to 1%) within a range not impairing the film characteristics of the present invention. Examples of the impurity elements include Fe, C, O, and N.

(V) of the present embodiment_1-aM_a) In the alloy target, the atomic ratio a of M to the total of V and M is 0.05 to 0.45. By controlling the composition within the above range, the difference between the composition of the coating and the composition of the target can be reduced, and the coating having desired properties can be stably formed. When the atomic ratio a of M exceeds 0.45, the film formation rate tends to decrease, which leads to a decrease in productivity. When the atomic ratio a of M is less than 0.05, a coating film of a V host is formed, and thus a droplet suppressing effect cannot be obtained. The lower limit of the atomic ratio a is preferably 0.1, and the upper limit of the atomic ratio a is preferably 0.40. In addition, (V) of the present embodiment_{1- a}M_a) The alloy target can be applied to a conventional film forming method, but is preferably used in a Physical Vapor Deposition (PVD) method such as an arc ion plating method or a sputtering method, in which a coating process can be performed at a temperature lower than the tempering temperature of a mold and fluctuation in the size of the mold can be suppressed. More preferably, the plating solution is used in arc ion plating which is particularly excellent in adhesion and throwing power to a sample but is likely to form droplets. Further, (V) of the present embodiment_1-aM_a) The alloy target is preferably the a2 layer used for the hard coating film of the present embodimentAnd a B layer, but in addition to this, the present invention is also applicable to applications in which a VMN-based single-layer film or a VMN-based film is coated on a multilayer film other than the present embodiment.

The method for manufacturing a coated mold according to the present invention is a method for manufacturing a coated mold having a hard coating on a working surface, and includes: a step of coating an A layer in which a1 layers and a2 layers are alternately laminated, the a1 layer is a Cr-based nitride and has a thickness of 100nm or less, and the a2 layer contains (V)_1-aM_a) (M is at least one selected from Mo and W), wherein the atomic ratio a of M to the total of V and M is 0.05 to 0.45, and the thickness is 80nm or less; and coating a layer B having a thickness of 0.1 [ mu ] m or more on the layer A using a target for forming a hard coating, the target comprising (V)_1-aM_a) (M is at least one selected from Mo and W), and the atomic ratio a of M to the total of V and M is 0.05 to 0.45. The hard coating forming method is preferably a Physical Vapor Deposition (PVD) method such as an arc ion plating method or a sputtering method, which is selected so that the coating treatment can be performed at a temperature lower than the tempering temperature of the mold and the fluctuation in the size of the mold can be suppressed. More preferably, arc ion plating, which is susceptible to droplet formation, is used. In order to obtain a hard film that is smoother and has excellent sliding properties, the surface of the hard film may be polished during or after coating.

The material (base material ) used in the mold of the present invention is not particularly limited, but tool steel such as cold die steel, hot die steel, and high-speed steel, cemented carbide, and the like can be suitably used. The mold may be subjected to surface hardening treatment by diffusion such as nitriding or carburizing. In addition, a film different from the hard film may be formed on the mold surface within a range not to impair the effects of the hard film of the present invention.

Examples

(example 1)

First, target materials of the present invention examples and comparative examples were produced. V powder and Cr, Fe, Nb, Mo, and W powder each having a purity of 99.9% or more were prepared, and the composition formula thereof was such that the atomic ratio is shown in Table 1The mixed powder was prepared by weighing and mixing with a V-blender. Next, the obtained mixed powder was filled into a soft steel capsule, hermetically sealed, and then sintered by hot hydrostatic pressing under the conditions of 1250 ℃, 120MPa, and a holding time of 10 hours, to produce a sintered body. The V powder was a pulverized powder, and a powder having a particle size of 150 μm or less and a D50 value of 87 μm was used. The Cr, Fe and Nb powders are pulverized powders, and the particle size is 150 μm or less. The Mo powder is obtained by a hydrogen reduction method of molybdenum trioxide powder, and a powder having a particle diameter (Fisher diameter) of 4 to 6 μm is used. The W powder is obtained by chemical extraction, and has a particle diameter (Fisher diameter) of 0.6-1.0 μm. The obtained sintered body was machined to prepare a sintered body (V) having a diameter of 105mm and a thickness of 16mm_1-aM_a) An alloy target. The composition of the prepared target is shown in table 1. Table 1 shows the thermal conductivity and melting point (thermal conductivity and melting point of V for a 100V target) of the additive element M extracted from the reference (revision 4 th metal data manual, japan metal institute, pill, 2004).

For the coated substrate, a substrate subjected to mirror polishing and degreasing cleaning of SKH51(21mm × 17mm × 2mm) was prepared, and the prepared substrate was set in an arc ion plating apparatus having a structure in which the substrate rotated around the center surrounded by a plurality of targets. AlCrSi target (Al) was used as the target for the a1 layer₆₀Cr₃₇Si₃(at%)), the target for the a2 layer was used as prepared (V)_1-aM_a) An alloy target. Thereafter, as an initial step, the substrate was degassed by heating at 450 ℃ in the apparatus, and then Ar gas was introduced to perform plasma cleaning treatment (Ar ion etching) of the substrate surface. Next, samples No.1 to No.6 were produced in which the substrates after the plasma cleaning treatment were coated. Each of the films had a structure in which an AlCrSiN layer having a thickness of 1 μm was formed and an AlCrSiN layer having a thickness of 17 μm to 20 μm was laminated with (V)_1-aM_a) An alternating N layer structure (hereinafter also referred to as AlCrSiN/(V)_1-aM_a) N) (layer a: alternate stacked portion), 0.5 μm (V) was formed as a film on the uppermost layer_1-aM_a) N film (B layer). Further, sample No.6 is a sample of V100% (a ═ 0%). This is achieved byIn addition, in samples No.1 to No.6, the thickness of the a1 layer was about 9nm, and the thickness of the a2 layer was about 12 nm.

Next, the cross section of the film of the prepared sample, which was inclined at 5 degrees to the outermost surface of the hard film, was adjusted by mirror polishing, and the observation surface corresponding to the alternate stacked portion (layer a) was observed with an optical microscope. FIG. 1 shows a photograph of sample No.2 as an inventive example, and FIG. 2 shows a photograph of sample No.6 as a comparative example. In the light micrograph of the figure, white spots are microdroplets. In the a layer produced using the targets of nos. 1 and 2 (M: Mo, W) as the examples of the present invention, droplets were significantly reduced, indicating that droplets could be reduced by the additive element having high thermal conductivity or melting point, as compared with the case of using the targets of nos. 3 to 5 (M: Cr, Fe, Nb) and No.6 having V100% (a: 0%) as the comparative examples.

[ Table 1]

(example 2)

Next, the amount of the additive element M (W, Mo) which exhibited the droplet reduction effect in example 1 was examined. A compositional formula of an atomic ratio is V_1-aM_aIn the same manner as in example 1, a target material as an example of the present invention was produced. The composition of the prepared target is shown in table 2. The coating step was performed in the same manner as in example 1 except for the material of the coating film, and samples No.7 to No.13 were produced. The same sample as sample No.1 of example 1 was used for sample No.8, the same sample as sample No.2 of example 1 was used for sample No.11, and the same sample as sample No.6 of example 1 was used for sample No. 13.

Next, with respect to the prepared sample, the film cross section of the test piece inclined by 5 degrees with respect to the outermost surface of the hard film was adjusted by mirror polishing, and the measurement of hardness and the quantitative analysis of the film component were performed on the observation surface corresponding to the alternate laminated portion (a layer) among them. The hardness (nanoindentation hardness) and young's modulus of the observed surface were measured using a nanoindentation device manufactured by bruker axs (bruker axs). The hardness and the modulus of elasticity were measured at 10 points under an indentation load of 5000 μ N and determined from the average values thereof. Quantitative analysis of the film component was carried out using an electron probe microanalyzer (EPMA; JXA-8900R manufactured by Japan Electron Ltd.). The analysis value was measured at five points with the acceleration voltage set to 15kV, and the average value was determined. The amounts of Mo and W in (V, M) were determined from the measured values of Al, Cr, Si, V, Mo, W and N, and the amounts were determined as the metal component composition of the a2 layer. The results are shown in table 2. It is also confirmed that the metal component ratio of the B layer is at the same level as that of the a2 layer, although not shown in the table. In addition, although not described in the table, 50V-50Mo and 50V-50W were also investigated as comparative examples. As a result, the arc discharge was unstable in all targets and it was difficult to form a film having a desired thickness, compared to the other examples, and therefore the experiment was terminated.

[ Table 2]

As a result of the quantitative analysis, it was found that 70% or more of the amount of Mo and W contained in the target was absorbed in the coating layer in Mo and W composed of the metal components of the a2 layer, and the ratio of the amount of Mo and W contained in the a2 layer increased as the amount of Mo and W contained in the target increased, and thus the a2 layer was able to be alloyed efficiently in the present invention. As a result of the hardness test, the hardness and young's modulus of the film containing much Mo and W in the a2 layer were increased. Since hardness is proportional to abrasion resistance and young's modulus is proportional to rigidity, the present invention is effective in abrasion resistance and durability of the coating film.

Next, quantitative evaluation of droplets contained in the film was performed. Five regions of 100 μm in the vertical direction and 100 μm in the horizontal direction were extracted from the film cross section corresponding to the same alternate lamination portion as the portion observed in the example. Then, the number and area of V, Mo, and W droplets having an equivalent circle diameter of 0.1 μm or more were determined by EPMA elemental mapping analysis for each of the above-mentioned regions. Open source software (open source software) ImageJ was used in image processing and analysis. Fig. 1 shows an element map image of V in the region and an image (field area 100 μm × 100 μm) obtained by binarizing the element map image for sample No.2 and sample No.13 in fig. 2. In fig. 3 and 4, the white spots are droplets.

Then, the number and area ratio of the droplets of samples No.7 to No.13 were determined by summing up the numerical values of the number and area of the droplets determined in each of the five regions. The number of droplets in sample No.13 indicates the number of droplets of V, and the droplet is used (V)_1-aM_a) Sample Nos. 7 to 12 of the alloy targets represent the total number of droplets of V and droplets of M (Mo or W). The measurement results are shown in table 3. As shown in table 3, fig. 3, and fig. 4, it was confirmed that the area ratio and the number of droplets in the alternately laminated part were significantly reduced in the VMN-based coating film of the present invention, and the effect was more significant as the content of M with respect to V was higher.

[ Table 3]

(example 3)

Next, a test for comparing the sliding characteristics of the samples of the present invention example and the comparative example was performed. The coated substrate was prepared by mirror polishing and degreasing and cleaning a pre-hardened steel (15mm × 10mm × 10mm) adjusted to 60HRC, and was set in an arc ion plating apparatus having a structure in which the substrate was rotated around the center surrounded by a plurality of targets. AlCrSi target (Al) was used as the target for the a1 layer₆₀Cr₃₇Si₃(at%)), an (V80W20 (at%)) alloy target or a V target was used as the target for the a2 layer. Thereafter, as an initial step, the substrate was degassed by heating at 450 ℃ in the apparatus, and then Ar gas was introduced to perform plasma cleaning treatment (Ar ion etching) of the substrate surface. Next, samples No.14 to No.20 were produced in which the substrates after the plasma cleaning treatment were coated. Sample No.14 was prepared by forming an AlCrSiN layer of 3.0 μm on a substrate and laminating a layer of 9.3 μm containing AlCrSiN (a1 layer) and VWN (a2 layer)The coating film (layer A: alternate lamination part) having an alternate lamination structure. Samples 15 and 16 each had a CrN layer of 4.4 μm formed on a substrate, and then a film having an AlCrSiN/CrN alternate lamination structure of 2.8 μm was formed directly on the CrN layer, and a film having an AlCrSiN/CrN alternate lamination structure of 2.4 μm (a1 layer) and VWN (a2 layer) was formed on the CrN layer (layer A: alternate lamination). Samples nos. 17 to 20 were coated with a film having an alternating lamination structure of 13 μm AlCrSiN (corresponding to a1 layer) and VWN (corresponding to a2 layer). In samples No.14 to No.20, the thickness of the a1 layer was about 9nm, and the thickness of the a2 layer was about 12 nm.

Schematic diagrams of the apparatus used in the sliding test are shown in fig. 5 and fig. 6(a) (b). FIG. 5 is a plan view of the test apparatus, and FIGS. 6(a) and (b) are side views of FIG. 5. As shown in the above-mentioned figure, the test apparatus used in the present embodiment includes: a holding mechanism 11 including an arm portion 15 for attaching and holding a sample to the sample setting portion 14; a contact jig 10 that repeatedly contacts and does not contact the sample while rotating; and a rotation mechanism (not shown) for rotatably holding the contact jig 10. The contact jig 10 includes a shaft portion 12 having a rotation axis Ax1, and a circular plate-shaped portion 13 having a central axis Ax2 eccentric from the rotation axis Ax 1. Although not shown in fig. 5 and 6, a housing hole for housing and holding the arm portion 15 is formed in the main body of the holding mechanism provided with the arm portion so as to be able to advance and retreat, and a spring mechanism is provided in the housing hole, so that the vertical resistance applied to the sample in advance is kept constant even during the test. In addition, a force sensor is incorporated in the main body of the holding mechanism, and vertical resistance applied to the sample and frictional force applied in the horizontal direction in the sliding test can be measured in real time. With this configuration, the test apparatus used in the present embodiment can evaluate the wear of the mold material close to the actual use environment without preparing a mold simulating the actual machining state. The samples of the present invention and comparative examples were mounted on the tip of the arm 15, and the circular plate-shaped portion (corresponding to the workpiece) made of SKD61 having a hardness of 45HRC was rotated at a rotation speed of 500mm/s, and the samples of the present invention and comparative examples and the circular plate-shaped portion were slid 7000 times. For lubrication in the sliding test, in order to reproduce oil film breakage in the actual use environment, an intermittent lubrication system is also employed in which a lubricating oil is applied to the surface of the sample when the friction coefficient μ between the circular plate-like portion and the sample reaches 0.25. The friction coefficient is determined in real time in a test as the ratio of the friction force measured with the force sensor to the vertical resistance. Further, samples in which the maximum frictional work (derived from the maximum frictional force [ N ] x the sliding length [ mm ]) was changed in the present invention examples and comparative examples were prepared, and the sliding portions of the samples were observed every 1000 times (every 100 times in the case of less than 1000 times). The test results of each sample are shown in table 4.

[ Table 4]

Film failure before the sliding times reach 7000 times

As is clear from table 4, even when the number of sliding times reached 7000 times, no breakage of the film was observed in samples nos. 14 to 16 as examples of the present invention, and the test was continued further, and very good sliding characteristics were observed. On the other hand, in all of the samples nos. 17 to 20 as comparative examples, the film was broken within 6000 times of sliding, and it was confirmed that the breakage occurred earlier as the maximum frictional work was larger. As described above, the coating film of the present invention can significantly improve the sliding characteristics and is effective in improving the life of the mold, compared to conventional coating films.

Description of the symbols

10: contact clamp

11: workpiece holding mechanism

12: shaft part

13: plate-shaped part

14: sample setting unit

15: arm part

Ax 1: rotating shaft

Ax 2: center axis of plate-like part