Covering member

Abstract

The present invention provides a coating material that suppresses crack propagation in hard coatings and also exhibits excellent adhesion resistance. [Solution] A coating member having a hard film on a substrate, wherein the hard film comprises an A layer formed on the substrate side, a B layer formed on the surface side of the A layer, and a C layer formed on the surface side of the B layer, wherein the A layer is an alternating laminated film formed by alternately stacking an a1 layer made of Ti nitride, carbonitride or oxycarbonitride and an a2 layer made of TiAl nitride, carbonitride or oxycarbonitride, the B layer is an alternating laminated film formed by alternately stacking a b1 layer made of Ti nitride, carbonitride or oxycarbonitride, a b2 layer made of TiAl nitride, carbonitride or oxycarbonitride and a b3 layer made of TiSi nitride, carbonitride or oxycarbonitride, and the C layer is a TiSi nitride of 0.3 μm or more.

Description

Technical Field

[0001] The present invention relates to a coating member.

Background Art

[0002] Conventionally, nitride-based hard coatings such as TiN and CrN formed by physical vapor deposition (PVD) or chemical vapor deposition (CVD) have been widely used as surface modification means for cutting tools, press dies, etc. Among them, TiSi-based nitride coatings (hereinafter also referred to as TiSiN coatings) are known to exhibit excellent wear resistance, and many application examples to tools have been reported.

[0003] For example, Patent Document 1 discloses a hard-coated cutting tool characterized by coating a single hard layer of a composite carbonitride or a composite nitride of Ti and Si having a composition of (Ti 1-x Si x )(C 1-y N y ) z [where 0.01 ≦ x ≦ 0.45, 0.01 ≦ y ≦ 1.0, 0.5 ≦ z ≦ 1.34].

[0004] Also, Patent Document 2 discloses a cutting tool in which, for the purpose of obtaining a harder hard coating, an alternating laminated coating of a TiSiN coating and a TiAlCrN coating is coated on a substrate, and a TiSiN coating is provided on the surface of the alternating laminated coating.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Recent trends in plastic deformation technology include efforts to promote near-net-shape deformation and reduce lubricant usage, with the aim of saving energy and resources. Consequently, the operating environment for coating components (e.g., molds) has become harsher, and a decrease in mold life has become a technical challenge. Factors contributing to this decrease in lifespan include cracking, chipping, and adhesion. In particular, cracking and chipping are thought to be caused by insufficient strength of the coating material, while adhesion is thought to be influenced by the chemical affinity between the coating material and the workpiece.

[0007] The hard coating disclosed in Patent Document 1 has a Ti-based nitride formed directly beneath a TiSi-based nitride. However, since the nitride is a single layer, there are concerns that the compressive residual stress accumulated inside the hard coating is high, making it prone to crack propagation. Furthermore, the hard coating disclosed in Patent Document 2 has a coating structure in which an alternating laminate of a TiSiN coating and a TiAlCrN coating is formed directly beneath a TiSiN-based nitride film. While it has excellent strength, its chemical compatibility has not been investigated, leaving room for improvement. Therefore, the object of the present invention is to provide a coating member that can suppress crack propagation in a hard coating and improve adhesion resistance. [Means for solving the problem]

[0008] The present invention has been made in view of the above-mentioned problems. Specifically, the present invention relates to a coating member having a hard film on a substrate, wherein the hard film comprises an A layer formed on the substrate side, a B layer formed on the surface side of the A layer, and a C layer formed on the surface side of the B layer, wherein the A layer is an alternating laminated film formed by alternately stacking an a1 layer made of Ti-based nitride, carbonitride or oxycarbonitride and an a2 layer made of TiAl-based nitride, carbonitride or oxycarbonitride, the B layer is an alternating laminated film formed by alternately stacking a b1 layer made of Ti-based nitride, carbonitride or oxycarbonitride, a b2 layer made of TiAl-based nitride, carbonitride or oxycarbonitride and a b3 layer made of TiSi-based nitride, carbonitride or oxycarbonitride, and the C layer is a TiSi-based nitride film of 0.3 μm or more. Preferably, the a1 and a2 layers constituting the A layer, and the b1, b2, and b3 layers constituting the B layer, are nitrides. Preferably, the combined film thickness of layer A and layer B is in the range of 0.5 to 6.0 μm. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a coating member that can suppress crack propagation in a hard coating and improve adhesion resistance. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows the film structure of an example of the present invention. [Figure 2] This figure shows the evaluation criteria for the indentation test according to this embodiment. [Figure 3] This figure shows the results of the indentation test in this embodiment. [Figure 4] This is a photograph showing the results of the scratch test in this embodiment. [Figure 5] This figure shows the results of the ball-on-disk test in this embodiment. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described herein, and can be appropriately combined and improved without departing from the technical spirit of the invention. The coating member of the present invention can be applied to various machine parts, molds, and tools. Preferably, it is applied to molds. More preferably, it is applied to hot working molds or cold working molds that place a heavy load on the mold, and even more preferably to cold working molds. Furthermore, the hard coating means of the embodiments can be physical vapor deposition methods such as arc ion plating, sputtering, and hollow cathode methods.

[0012] Figure 1 shows a schematic diagram illustrating the coating member of this embodiment. The hard coating of this embodiment comprises an alternating laminated film A layer formed on a substrate, an alternating laminated film B layer formed on the surface side of layer A, and a single-layer TiSi nitride film C layer formed on the surface side of layer B. By forming the film as a multilayer structure as described above, the hardness of the film is gradually increased from the substrate side to the surface side, and the effect of mitigating compressive residual stress that promotes crack formation is obtained. Furthermore, as described later, layers A and B are formed as alternating laminated films in which different coatings are alternately stacked within each layer, thereby dispersing the crack propagation path and dramatically suppressing cracking. In addition, by forming layer C, described later, as the outermost layer of the hard coating, the mechanical properties are improved, and the effect of improving mold life is obtained. The substrate to which the hard coating according to the present invention is applied can be mold steel, structural steel, stainless steel, and cemented carbide. Preferably, it is applied to mold steel.

[0013] In this embodiment, layer A is an alternating laminated film in which layer a1, made of Ti-based nitride, carbonitride, or oxycarbonitride, and layer a2, made of TiAl-based nitride, carbonitride, or oxycarbonitride, are alternately laminated. If layer A is a single-layer structure, when a minute crack is introduced into the film by an external force, the crack tends to propagate along the grain growth direction (grain boundary), and once the crack has grown sufficiently, it becomes visible even in a macroscopic view. When used in harsh environments such as molds, if a crack occurs inside the hard film, there is a concern that it will lead to significant damage to the mold at an early stage. As in this embodiment, by making layer A an alternating laminated film, even if a minute crack is introduced, the crack propagation path is dispersed at the lamination interface, so it is thought that the effect of suppressing cracking inside the film can be obtained. Furthermore, regarding the composition of each layer, since layer a1 is a Ti-based nitride, carbonitride, or oxycarbonitride, and layer a2 is a TiAl-based nitride, carbonitride, or oxycarbonitride, it is expected that misfitting between the lattice and layer B, which is an alternating laminated film containing Ti described later, will be suppressed and the peel strength at the laminated interface between layer A and layer B will be improved. The average composition of layer A can be determined by analysis using a field emission electron probe microanalyzer (FE-EPMA) or the like. In this average composition of layer A of the present invention, when the total amount of metal components contained in the hard film is taken as 100 at%, it is preferable that Ti+Al is 90 at% or more (preferably 95 at% or more, more preferably 99 at% or more) and Ti is 50 at% or more. In addition, metal components other than Ti+Al may be contained in amounts of 10 at% or less (excluding the active addition of Cr) within a range that does not impair the properties. Furthermore, the thickness of each of layers a1 and a2 can be set within the range of 0.1 to 100 nm.

[0014] Next, let's discuss layer B. When layer C, a single-layer film of TiSi-based nitride described later, is formed directly above layer A, there is a concern that the difference in film hardness between the soft layer A and the hard layer C will increase compressive residual stress, thus accelerating crack formation. For this reason, it is effective to form layer B, which is harder than layer A but has the same hardness as layer C, as a buffer layer on the surface side of layer A. Considering the measurement error in minute indentation hardness, if the difference in hardness between layer B and layer C is within 5 GPa, the hardness of layer B is considered to be less than or equal to the hardness of layer C. This B layer is an alternating laminated film formed by alternately laminating a b1 layer made of a Ti-based nitride, carbonitride or oxynitride, a b2 layer made of a TiAl-based nitride, carbonitride or oxynitride, and a b3 layer made of a TiSi-based nitride, carbonitride or oxynitride. A preferred configuration of the B layer is an alternating lamination of a b1 layer made of a Ti-based nitride, a b2 layer made of a TiAl-based nitride, and a b3 layer made of a TiSi-based nitride. By forming a laminated film including the b3 layer which is a TiSi-based nitride, it is possible to improve the average hardness of the B layer and approach the hardness of the high-hardness C layer. Also, by forming an alternating laminated film of the b1 layer, b2 layer and b3 layer, it is considered that the effect of dispersing crack propagation can be dramatically exerted as compared with the case of only the A layer. Here, the "alternating laminated film of the b1 layer, b2 layer and b3 layer" in the present embodiment does not necessarily need to be laminated in the order of b1 layer / b2 layer / b3 layer / b1 layer / b2 layer / b3 layer..., and for example, the lamination order may vary such as b2 layer / b1 layer / b3 layer... or b3 layer / b2 layer / b1 layer.... The average composition of the B layer can be grasped by performing analysis using FE-EPMA or the like, similar to the A layer. In the average composition of the B layer of the present invention, when the total of the metal components contained in the hard film is set to 100 at%, it is preferable that Ti + Al + Si is 90 at% or more (preferably 95 at% or more, more preferably 99 at% or more) and Ti is 50 at% or more. Also, within a range not impairing the properties, it may contain 10 at% or less of metal components other than Ti + Al + Si (excluding the positive addition of Cr). Also, the thickness of each of the b1 layer to b3 layer can be set within the range of 0.1 to 100 nm.

[0015] It is more preferable that the a1 layer, a2 layer constituting the above-described A layer, and the b1 to b3 layers constituting the B layer do not provide a thickness gradient and have a constant content of components (that is, do not provide a concentration gradient) in the growth direction (lamination direction) of crystal grains. By not providing a thickness gradient and keeping the content of components constant, the effect of the alternating laminated film (dispersion of the crack propagation path) can be sufficiently exerted. Regarding the thickness gradient, if the difference between the average thickness of each of the a1 layer, a2 layer, and b1 - b3 layers in the substrate - side region of the A layer or B layer and the average thickness of each of the a1 layer, a2 layer, and b1 - b3 layers in the surface - side region of the A layer or B layer is 5 nm or less, it is defined that no thickness gradient is imparted. Here, the "substrate - side region" in the present embodiment refers to the region from the interface between the substrate and the A layer or the interface between the A layer and the B layer to 1 / 4 of the total thickness of the alternately - laminated film in the thickness direction (surface direction). Also, the "surface - side region" of the alternately - laminated film in the present embodiment refers to the region from the interface between the B layer and the C layer or the interface between the A layer and the B layer to 1 / 4 of the total thickness of the alternately - laminated film in the thickness direction (substrate - side direction). Regarding the content of components, the average composition in the substrate - side region of the A layer or B layer is compared with the average composition in the surface - side region of the A layer or B layer. If the difference in the main metal elements is 5 at% or less, it is defined that the component composition is constant.

[0016] It is preferable not to add Cr to the a1 layer, a2 layer constituting the A layer, and b1 - b3 layers constituting the B layer. For example, when a hard film containing both Al and Cr is formed on the surface of a sliding member such as a mold, due to the heat generation at the sliding interface, O, Al, and Cr contained in the atmosphere generate oxides, and there is a concern that adhesion (here, it refers to the adhesion of oxides to the surface of the sliding member) may occur. Here, considering the measurement error of the apparatus, if the content of Cr is 5 at% or less in the average composition of the A layer or B layer, it is defined that it is not contained.

[0017] In the present embodiment, it is preferable to form the combined film thickness of the A layer and the B layer in the range of 0.5 - 6.0 μm. When the sum of the film thickness of the entire A layer and the film thickness of the entire B layer is extremely small, it becomes difficult to improve the hardness step - by - step, and there is a concern that the compressive residual stress may increase. Also, when it is larger than necessary, there is a concern that the properties of the hard film may be impaired when applied to the coating member (for example, abnormal wear due to a decrease in the clearance of the mold).

[0018] In this embodiment, the C layer formed on the outermost surface of the hard coating determines the mechanical properties of the coated member and plays a role in maintaining durability. This C layer is formed of a TiSi-based nitride. Here, "TiSi-based" refers to a film in which, when the total amount of metal components contained in the hard coating is 100 at%, Ti+Si is 90 at% or more (preferably 95 at% or more, more preferably 99 at% or more), and Ti is 50 at% or more and Si is 3 at% or more. In addition, metal components other than Ti+Si may be included in amounts of 10 at% or less (excluding the active addition of Cr) as long as the properties are not impaired. Furthermore, in order to ensure sufficient durability of the C layer, it is preferable that the total film thickness of the C layer be in the range of 0.3 to 5.0 μm, and that the minute indentation hardness of the C layer be in the range of 10 to 50 (GPa).

[0019] The hard coating of the present invention may have an underlayer between the substrate and layer A in order to improve adhesion to the substrate. This underlayer is preferably a metal film, nitride film, carbonitride film, or oxycarbonitride film containing one or more elements selected from groups 4a, 5a, and 6a of the periodic table. Furthermore, the structure of the underlayer is not limited to a single layer, but may be a multilayer consisting of two or more layers. Furthermore, the underlayer is preferably Ti-based (when the total amount of metal components contained in the underlayer is 100 at%, Ti is 50 at% or more, preferably 90 at% or more). By making the underlayer Ti-based, it is thought that the chemical bond with layer A formed directly above the underlayer is stabilized, and the adhesion between the underlayer and layer A is improved. Furthermore, the overall thickness of the underlayer is preferably in the range of 0.1 to 2.0 μm, and more preferably in the range of 0.1 to 1.5 μm.

[0020] The coating member of the present invention, having the above-described film structure, has reduced compressive residual stress. This compressive residual stress can be calculated using Stoney's formula shown in (Equation 1) below, and in the present invention, it is preferable that the calculated compressive residual stress is 0.400 GPa or less. More preferably, it is 0.300 GPa or less, and even more preferably, 0.250 GPa or less. σ=(ED^2×δ) / 3l^2×(1-v)d…(Equation 1) However, E: Young's modulus of the substrate, D: thickness of the coating substrate, δ: deflection of the test specimen, l: length of the test specimen to the maximum deflection, v: Poisson's ratio of the coating substrate, and d: film thickness. [Examples]

[0021] For this embodiment, we selected a material equivalent to SKH51, a high-speed tool steel (dimensions: 21 mm x 17 mm x 2 mm), and a material equivalent to Z10, an ultrafine-grained cemented carbide (dimensions: 8 mm x 25 mm x 1 mm), as the base materials. These base materials were ultrasonically cleaned using a hydrocarbon-based solvent, and then subjected to the coating treatment described below to produce samples No. 1 to 14.

[0022] The coating method in the present invention example was applied using the sputtering method. Ti, TiAl, and TiSi were selected as targets for hard film formation and installed in the film deposition apparatus. First, the substrate was heated to over 400°C and ion cleaning was performed. Next, power was supplied to the power supply connected to the Ti target, and at least one of nitrogen gas and an inert gas was introduced into the film deposition apparatus to form a base layer by reactive sputtering. Then, layers A and B, which are alternating laminated films, and layer C, which is a single layer film, were formed directly on top of the base layer, and these were designated as samples No. 1 to 11, which are examples of the present invention. Furthermore, layers A, B, and C were formed without forming a base layer, and this was designated as sample No. 12, which is also an example of the present invention. Note that layer a1 is Ti nitride, layer a2 is TiAl nitride, layer b1 is Ti nitride, layer b2 is TiAl nitride, and layer b3 is TiSi nitride.

[0023] Next, a conventional coated member was prepared, which lacked layers A and B of the present invention and instead had a single-layer TiSi nitride film (layer C in the present example) directly on top of a single-layer TiAl nitride film. Arc ion plating was applied as the coating method. TiAl and TiSi were selected as targets for hard film formation and installed in the film deposition apparatus. First, the substrate was heated to over 400°C, and then ion cleaning was performed. Next, power was supplied to a power supply connected to the TiAl target to form a single-layer TiAl nitride film. Subsequently, power was supplied to a power supply connected to the TiSi target to form a TiSi nitride film, which was designated as conventional sample No. 13.

[0024] Next, a conventional coated member having an alternating laminated film containing Cr was prepared. The sputtering method was applied as the coating method. Ti, CrAl, and CrAlSi were selected as targets for hard film formation and installed in the film deposition apparatus. First, the substrate was heated to over 400°C and ion cleaning was performed. Subsequently, nitrogen gas and at least one inert gas were introduced into the film deposition apparatus, and power was supplied to the power supply connected to the Ti target to form a Ti-based underlayer. Next, power was supplied to the power supplies connected to the CrAl and CrAlSi targets to form a CrAlSi-based alternating laminated nitride film, which was designated as conventional sample No. 14.

[0025] After preparing each sample, the hard coatings of samples No. 1-12 (examples of the present invention) and samples No. 13 and 14 (conventional examples) underwent thickness measurement, compositional analysis, and hardness measurement. Furthermore, compression residual stress measurements were performed to confirm the compression residual stress relaxation effect of the alternating laminated coating of the present invention, indentation tests and scratch tests were conducted to evaluate the ease of crack propagation, and ball-on-disk tests were performed to evaluate adhesion resistance.

[0026] [Film thickness measurement and compositional analysis] To prepare test specimens for film thickness measurement and compositional analysis, a hard coating formed on an SKH51 equivalent material was ground using a calorite tester (CSM Instruments, Nanotec Co., Ltd.) to expose the cross-section. Subsequently, the film thickness was measured by observing the cross-section of this test specimen under a microscope. Table 1 shows the results of the film thickness measurement. For samples No. 1 to 12, which are examples of the present invention, the C layer was confirmed to be 0.56 to 1.26 μm, the A+B layer 1.35 to 2.14 μm, and the underlayer 0.41 to 1.18 μm. On the other hand, sample No. 13, a conventional example, did not have the alternating laminated film of the present invention, and the single-layer TiAl nitride (TiAlN) film was confirmed to be 3.42 μm, with the C layer being 1.47 μm. For sample No. 14, a conventional example, the thickness of the Ti underlayer was confirmed to be 0.12 μm, and the thickness of the CrAlSi nitride (CrAlSiN) alternating laminated film was confirmed to be 2.68 μm.

[0027] [Table 1]

[0028] The cross-section of the aforementioned test specimen was analyzed using FE-EPMA (JXA-8500F, manufactured by JEOL Ltd.) to derive the average composition of each layer of the hard coating. The analysis conditions were: acceleration voltage 10kV, irradiation current 5×10⁻¹⁰ -8 A. The beam diameter was 1 μm. Analysis was performed at three points in each layer: on the substrate side, in the center, and on the surface. The average value calculated from the average of these three points was used as the average composition. The results of the compositional analysis are shown in Table 2. Note that in the average composition values ​​[at%] in Table 2, there is a value where the total metal component is 99 at%, but this is because the decimal part has been omitted for notational reasons. It has been confirmed that when the actual values ​​including the decimal part are used for calculation, the total metal component is 100 at%.

[0029] [Table 2]

[0030] [Hardness measurement] To prepare test pieces for hardness measurement, the hard coatings of Sample Nos. 1 to 14 formed on a material equivalent to SKH51 were mirror-polished while being tilted at 5 degrees, exposing the cross-section of the coating. For the hardness measurement device, an ultra-microindentation hardness tester (ENT-1000a manufactured by Elionix, Inc.) was used. The indentation load was 10 mN, and the number of measurement points was 10 for each sample. Considering the measurement error of the device, the average of the 8 measurement values excluding the minimum and maximum values of the measurement values was taken as the hardness of the hard coating. The results of the hardness measurement are shown in Table 3. It was confirmed that in the examples of the present invention (Nos. 1 to 12), the coating hardness (micro-indentation hardness) gradually improved from the substrate side toward the B layer (hardness of A layer < hardness of B layer).

[0031] [Table 3]

[0032] Compressive residual stresses were calculated for Sample Nos. 1, 3 to 6, 10, 13, and 14. For the test pieces for compressive residual stress measurement, samples with a hard coating formed on a material equivalent to Z10 were used. Stoney's formula was used to calculate the compressive residual stress. The said formula is described as (Formula 1). σ=(ED^2×δ) / 3l^2×(1 - v)d (Formula 1) However, E: Young's modulus of the substrate, D: thickness of the coated substrate, δ: deflection amount of the test piece, l: length of the test piece up to the maximum deflection amount, v: Poisson's ratio of the coated substrate, d: film thickness. The calculation results of the compressive residual stress are shown in Table 4. The compressive residual stress of the examples of the present invention showed extremely low values of 0.023 to 0.180 GPa. On the other hand, the compressive residual stress of Sample No. 14, which is a conventional example, was 0.419 (GPa), higher than the maximum value of the compressive residual stress in the examples of the present invention, and for Sample No. 13, which is a conventional example, it showed a value about 20 times the maximum value of the compressive residual stress in the examples of the present invention, i.e., 3.655 (GPa). It is considered that in the examples of the present invention, by gradually improving the hardness in the hard coating and providing an alternating laminated layer, the compressive residual stress could be significantly relaxed.

[0033] [Table 4]

[0034] [Indentation test] For the indentation test, samples No. 1 to 14 were prepared by forming hard coatings on a substrate equivalent to SKH51. A Rockwell hardness tester (Mitutoyo HR-430MS) was used to indent the coated surface of the SKH51 (21 mm x 17 mm), and the ease of crack propagation was qualitatively evaluated by observing the indented area under a microscope. Furthermore, adhesion was also evaluated by comparing it with the criteria shown in Figure 2. The test results are shown in Figure 3. Multiple circular cracks were observed around the indentation of sample No. 13, a conventional example. On the other hand, no cracks were observed around the indentations of samples No. 1 to 12, which are examples of the present invention, and sample No. 14, a conventional example, confirming that the results were better compared to No. 13. This can be interpreted as the presence of an alternating laminated film easing compressive residual stress and suppressing the occurrence of cracks. In particular, samples No. 1 to 11 and 14 showed no delamination around the indentation and demonstrated excellent adhesion. However, although no cracks were observed around the indentation of sample No. 12, an example of the present invention, slight delamination was confirmed. This is thought to be because sample No. 12 lacked a base layer, resulting in a large lattice misfit at the interface between the substrate and the hard coating, thus degrading adhesion.

[0035] [Scratch Test] In this test, a diamond indenter was pressed against the SKH51 coated surface (21 mm x 17 mm) of samples No. 1 and 12-14, and the surface of the hard coating was scratched while gradually increasing the load from 1 to 120 N. The scratch marks formed were then observed under a microscope to evaluate scratch resistance. A scratch tester (Revetest-RST, manufactured by Nanotec) was used for the testing. The test results are shown in Figure 4. In Figure 4, Lc is the critical peeling load, which is the load at the moment the hard coating peels off and the substrate is exposed. In the conventional example, sample No. 13, the scratch marks tended to enlarge with increasing load in the range of 1 to 40 N. In the range of 50 to 70 N, circumferential cracks occurred perpendicular to the scratching direction. At 76.50 N, the hard coating peeled off and the substrate was exposed. On the other hand, in the present invention examples, samples No. 1 and 12, and the conventional example, sample No. 14, no cracks were observed, indicating good results. First, in the present invention example, sample No. 1, similar to sample No. 13, the scratch marks tended to enlarge with increasing load in the range of 1 to 70 N, but it was confirmed that the occurrence of circumferential cracks was suppressed. At 79.67 N, the hard coating peeled off and the substrate was exposed. This is thought to be because the alternating laminated coating relaxed the compressive residual stress, suppressing circumferential cracks. Furthermore, in sample No. 12, which is an example of the present invention without a base layer, and sample No. 14, which is a conventional example, circumferential cracking was suppressed. However, slight delamination was observed in the low load range of 40N, resulting in slightly inferior adhesion compared to sample No. 1. The reason for the slight delamination is thought to be that the absence of a base layer reduced adhesion.

[0036] [Ball-on-disk test] In this test, the adhesion resistance of the hard coating was evaluated by contacting a ball specimen with a rotating disk specimen while applying a load, and observing the damage morphology of the disk specimen. For the disk specimen, samples No. 1 and No. 14 with hard coatings formed on a material equivalent to SKH51 were used, and for the ball specimen, a material equivalent to G4805 (6 mm in diameter) was used. A ball-on-disk tester (Nanotec + csm Instruments) was used as the testing machine. As preparation before the test, the ball specimen was degreased with an alcohol-based cleaning solution. This test was conducted in an atmospheric environment at room temperature. The applied load was 2 (N), and the sliding distance was 100 (m). After the test, observation and analysis were performed using a microscope and FE-EPMA (JXA-8500F, JEOL Ltd.). The test results are shown in Figure 5. Microscopic observation was performed on sample No. 1, which is an example of the present invention, and it was confirmed that sliding marks were formed in the area where the disk test piece and the ball test piece were in contact. Backscattered electron images were collected using FE-EPMA, and it was found that there was a difference in composition between the surface layer of the hard coating and the sliding marks. Furthermore, surface analysis was performed using the same apparatus and it was found that the amount of Fe, a component of the ball, detected directly above the sliding marks was extremely low. From the analysis results, it is thought that in the example of the present invention (No. 1), heat generated at the sliding interface between the disk and the ball caused the metal components (Ti, Al, Si) contained in the hard coating to react with oxygen in the atmosphere, generating Ti-based oxides, which then detached as wear particles, causing wear inside the hard coating. On the other hand, in the conventional example (No. 14), sliding marks were also formed in the area where the disk test piece and the ball test piece were in contact, but a large amount of Fe was detected directly above the sliding marks. In conventional cases, it is believed that heat generated at the sliding interface causes a reaction between Al, Cr, and Si contained in the hard coating, O in the atmosphere, and Fe contained in the ball, forming a highly exfoliable AlCr-based composite oxide, which then deposits on the hard coating (i.e., adhesion). Based on the above test results, it was confirmed that the coating material of the present invention suppresses crack propagation more effectively than conventional examples, while also exhibiting superior adhesion resistance.

Claims

1. A coating member having a hard coating on a base material, The hard coating comprises a layer A formed on the substrate side, a layer B formed on the surface side of layer A, and B It comprises a C layer formed on the surface side of the layer, The aforementioned A layer is an alternating laminated film in which a1 layer made of Ti nitride, carbonitride, or oxycarbonitride and a2 layer made of TiAl nitride, carbonitride, or oxycarbonitride are alternately stacked. The aforementioned B layer is an alternating laminated film in which a b1 layer made of Ti nitride, carbonitride or oxycarbonitride, a b2 layer made of TiAl nitride, carbonitride or oxycarbonitride, and a b3 layer made of TiSi nitride, carbonitride or oxycarbonitride are alternately laminated. The C layer is a TiSi-based nitride with a thickness of 0.3 μm or more, forming a coating member.

2. Layers a1 and a2 that constitute Layer A, and Layers b1 and b2 that constitute Layer B The coating member according to claim 1, wherein the b3 layer is a nitride.

3. The combined thickness of the A layer and the B layer is in the range of 0.5 to 6.0 μm, according to claim 1 or 2. The covering material described.

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