Surface coating material

Abstract

The present invention provides a surface coating member that maintains the integrity of the coating and has excellent adhesion resistance to titanium alloys. [Solution] The surface coating member is a surface coating member having a base material and a hard coating formed on the base material, wherein the hard coating is made of the formula: (Zr 1-x Nd x )N y O 1-y (In the formula, x represents the atomic ratio of Nd to the total amount of Nd and Zr, and y represents the atomic ratio of N to the total amount of N and O, where 0.011)

Description

[Technical Field]

[0001] The present invention relates to a surface coating member having excellent adhesion resistance. [Background technology]

[0002] Titanium alloys are widely used in aircraft and ship components due to their high specific strength, stable passive film formation, and excellent corrosion resistance. However, because titanium itself is a highly reactive metal, it is known that adhesion to mating materials is likely to occur when processing titanium alloys.

[0003] For example, when machining a workpiece made of titanium alloy, the newly exposed surface of the titanium alloy may adhere to the cutting tool, potentially damaging the cutting edge or other parts of the tool. Alternatively, machining a workpiece made of titanium alloy may result in reduced machining accuracy. For similar reasons, it is generally considered difficult to use titanium alloy as a material for sliding parts, as it is anticipated that titanium alloy will seize up with the mating material.

[0004] On the other hand, with regard to hard coatings formed on cutting tools, many attempts have been made to improve the performance of the coating by incorporating a predetermined metal element into the Zr nitride. For example, Patent Document 1 describes a chemical formula Hf that satisfies predetermined conditions. 1-a Zr a X b A surface-coated cutting tool is disclosed, comprising at least a zirconium-containing hafnium layer in the coating, which contains a compound having a predetermined crystalline structure as shown in [the provided formula].

[0005] Furthermore, Patent Document 2 describes a material having an average layer thickness within a predetermined range, and whose composition formula is (Zr 1-γ Y γ A surface-coated cutting tool is disclosed, in which a hard coating layer is formed on the surface of the tool substrate, consisting of a single layer of a composite nitride layer of Zr and Y satisfying )N (where the atomic ratio is 0.01 ≤ γ ≤ 0.15). [Prior art documents] Patent Literature

[0006] Patent Literature 1 Japanese Unexamined Patent Application Publication No. 2009-148856 Patent Literature 2 Japanese Unexamined Patent Application Publication No. 2012-106297 Summary of the Invention Problems to be Solved by the Invention

[0007] It is described that the surface-coated cutting tools described in Patent Literature 1 and Patent Literature 2 provide high wear resistance, and excellent heat resistance, welding resistance and the like in high-speed cutting of difficult-to-cut materials. However, the coatings described in any of these literatures still leave room for improvement from the perspective of adhesion resistance when processing titanium alloys having high activity.

[0008] As a result of intensive studies by the present inventors, it has been found that a hard coating made of a nitride containing zirconium (Zr) and neodymium (Nd) as metal elements may improve adhesion resistance to titanium alloys. However, Zr and Nd do not dissolve in each other even when the temperature is raised, and separate into two phases, so it is difficult to stably form a coating by a general method. In addition, Nd and a single neodymium nitride spontaneously oxidize in the atmosphere, and the oxide is a brittle and easily crumbly substance. Therefore, even if a coating containing Nd is formed by an ordinary method, handling thereof is difficult. Further, as a result of further intensive studies by the present inventors, it has been found that even if a hard coating made of a nitride containing Zr and Nd can be formed, depending on the atomic ratio of Zr and Nd, there are problems in coating integrity such as swelling and peeling.

[0009] Accordingly, an object of the present invention is to provide a surface-coated member that maintains coating integrity and has excellent adhesion resistance to titanium alloys. Means for Solving the Problems

[0010] The inventors of the present invention have conducted intensive studies to solve the above problems and arrived at the present invention. That is, the present invention includes the following preferred embodiments.

[0011] The surface-coated member according to the first aspect of the present invention is a surface-coated member comprising a base material and a hard coating formed on the base material, The hard coating has the formula: (Zr 1-x Nd x )N y O 1-y (wherein in the formula, x represents the atomic ratio of Nd to the total amount of Nd and Zr, y represents the atomic ratio of N to the total amount of N and O, 0.011 < x ≦ 0.607, and 0 ≦ y ≦ 1).

[0012] The surface-coated member according to the second aspect of the present invention is the surface-coated member according to the first aspect, wherein in the above formula, 0.109 ≦ x is satisfied. Effects of the Invention

[0013] According to the present invention, it is possible to provide a surface-coated member that maintains the soundness of the coating and has excellent adhesion resistance against titanium alloys. Brief Description of the Drawings

[0014] [Figure 1] FIG. 1 is a schematic diagram for explaining the arrangement of two target evaporation sources and a base material in a chamber of an unbalanced magnetron sputtering apparatus in the present example. [Figure 2] FIG. 2 is a graph showing the relationship between the atomic ratio (x) of Nd to the total amount of Zr and Nd (total amount of metal elements) and the atomic ratio (y) of N to the total amount of N and O (total amount of non-metal elements) in Examples 1-1 to 1-15 and Comparative Examples 1-1 to 1-10. [Figure 3] FIG. 3 is a schematic diagram for explaining the arrangement of a target evaporation source and a base material in an arc ion plating apparatus in the present example. [Figure 4]Figure 4 is a graph showing the relationship between the atomic ratio (x) of Nd to the total amount of Zr and Nd (total amount of metal elements) and the average coefficient of friction in adhesion resistance evaluation for titanium alloys in Examples 2-1 to 2-12 and Comparative Examples 2-1 to 2-3. Mode for Carrying Out the Invention

[0015] The present inventors conducted intensive experiments on a surface-coated member that maintains film integrity and has excellent adhesion resistance against titanium alloys, from the perspective of the atomic ratio of Nd to the total amount of Nd and Zr (see Examples described below). As a result, the hard film formed on a substrate is represented by the formula: (Zr 1-x Nd x )N y O 1-y (wherein in the formula, x represents the atomic ratio of Nd to the total amount of Nd and Zr, y represents the atomic ratio of N to the total amount of N and O, 0.011 < x ≤ 0.607, and 0 ≤ y ≤ 1). It was found that by adopting the component composition represented by this formula, a surface-coated member having both effects of film integrity and excellent adhesion resistance against titanium alloys can be obtained.

[0016] Hereinafter, embodiments of the present invention will be described in detail. It should be noted that the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the present invention.

[0017] 1. Configuration of Surface-Coated Member First, the configuration of the surface-coated member according to the present embodiment will be described. The surface-coated member includes a base material and a hard film formed on the base material.

[0018] As used herein, the term "member" in a surface-coated member is not particularly limited as long as the member has a base material portion on which a hard film can be formed. In particular, the "member" of the surface-coated member is preferably any member known to those skilled in the art that has a base portion requiring adhesion resistance to titanium alloys. Examples of such members include cutting tools such as end mills, drills, taps, cutting bits, dies, inserts, milling cutters and reamers, and sliding members such as bearings, blades, vanes, packings, seal rings, guides, stages, cylinders and piston members.

[0019] 1-1. Base Material As used herein, the "base material" is at least a part of the aforementioned member on which the hard film is formed, and is the main constituent part of the member. That is, the base material may be at least a part of the outer surface (i.e., a functional part) of the aforementioned member that comes into contact with a material containing titanium alloy (e.g., a work material containing titanium alloy) when the aforementioned member is used.

[0020] The material of the base material is not particularly limited as long as it is any material known to those skilled in the art. Examples of the material of the base material include materials such as cemented carbide, cermet, ceramics and CBN sintered compacts, and steel materials such as high-speed tool steel, die steel and stainless steel.

[0021] 1-2. Hard Film The hard film is formed on the aforementioned base material, for example, by a method described later. The composition and thickness of the hard film will be described in detail below.

[0022] <Composition of Hard Film> In the present embodiment, the hard film has the formula: (Zr 1-x Nd x )N y O 1-y (wherein in the formula, x represents the atomic ratio of Nd to the total amount of Nd and Zr, y represents the atomic ratio of N to the total amount of N and O, 0.011 < x ≦ 0.607, and 0 ≦ y ≦ 1).

[0023] That is, the hard coating is a nitride (when y=1), oxynitride (when 0<y<1) or oxide (when y=0) containing Zr (zirconium) and Nd (neodymium) as metal elements.

[0024] Zirconium nitride is thermodynamically more stable than titanium nitride. Therefore, even when zirconium nitride comes into contact with a titanium alloy, nitrogen in the zirconium nitride is less likely to be abstracted by the titanium alloy, and the zirconium nitride maintains a stable state. By further containing Nd as a metal element, the adhesion resistance to titanium alloys can be improved.

[0025] On the other hand, Nd is an element that is easily oxidized. Therefore, (Zr 1-x Nd x )N (wherein 0.011<x≤0.607 in the formula) even when a hard coating having the component composition represented by the formula is formed on a substrate to produce a surface-coated member, if the member is left in an atmospheric environment, a natural oxide film is formed on the surface of the nitride due to the influence of Nd in the hard coating. As a result, over time, the component composition of the hard coating becomes (Zr having the same atomic ratio x of Nd 1-x Nd x )N y O 1-y (wherein 0<y<1 in the formula) or an oxynitride having the component composition of (Zr 1-x Nd x )O can be changed to the oxide.

[0026] When the atomic ratio x of Nd to the total amount of Nd and Zr (total amount of metal elements) in the above formula is more than 0.011, a hard coating having excellent adhesion resistance to titanium alloys can be obtained.

[0027] The atomic ratio x of Nd to the total amount of Nd and Zr (total amount of metal elements) is preferably 0.109≤x, more preferably 0.151≤x, and still more preferably 0.214≤x. Further, the atomic ratio x of Nd to the total amount of Nd and Zr (total amount of metal elements) is particularly preferably not less than a value selected from the group consisting of 0.275, 0.303, 0.309, and 0.335.

[0028] When the atomic ratio x of Nd relative to the total amount of Nd and Zr (the total amount of metal elements) in the above formula is 0.607 or less, the integrity of the hard coating can be maintained even when the surface-coated member having the hard coating is left in an air atmosphere. Specifically, over time, (Zr 1-x Nd x )N (wherein 0.011 < x ≦ 0.607 in the formula) is a nitride hard coating. Due to the influence of Nd in the coating, (Zr having the same atomic ratio x of Nd 1-x Nd x )N y O 1-y (wherein 0 < y < 1 in the formula) oxynitride or (Zr 1-x Nd x )O oxide, even when the hard coating changes to the above-mentioned hard coating, macroscopic defects such as blistering and peeling do not occur in the coating.

[0029] In the present specification, "coating integrity" means that, for example, when the appearance of the hard coating is visually observed and the visually observed portion is observed with a scanning electron microscope at a magnification of 2000 times, no defects such as blistering and peeling are observed in the appearance of the coating.

[0030] The atomic ratio x of Nd to the total amount of Nd and Zr (the total amount of metal elements) is preferably x ≦ 0.600, more preferably x ≦ 0.586, still more preferably x ≦ 0.551. Further, the atomic ratio x of Nd is particularly preferably not more than a value selected from the group consisting of 0.500, 0.457, 0.430, and 0.400.

[0031] In the present specification, the atomic ratio of Nd or Zr to the total amount of Nd and Zr (specifically, the total amount of metal elements) and the atomic ratio of N or O to the total amount of N and O (specifically, the total amount of non-metal elements) in the hard coating can be measured, for example, by analysis (EDS analysis) using energy dispersive X-ray spectroscopy mounted on a scanning electron microscope energy dispersive X-ray spectrometer.

[0032] In addition to the elements Zr (zirconium), Nd (neodymium), N (nitrogen), and O (oxygen) mentioned above, the composition of the hard coating may also include unavoidable impurities such as metallic, nonmetallic, and metalloid elements, as long as they do not impair the integrity of the coating and its excellent resistance to adhesion to titanium alloys in this embodiment. For example, when the hard coating is formed by sputtering, argon (Ar) may be included in the hard coating as an unavoidable impurity.

[0033] <Thickness of the hard coating> The thickness of the hard coating is not particularly limited as long as it does not impair the integrity of the coating and the excellent adhesion resistance to titanium alloys of this embodiment. For example, it is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and particularly preferably a value selected from the group consisting of 0.2 μm, 0.5 μm, 0.7 μm, and 1 μm or more. When the thickness of the hard coating is 0.01 μm or more, crystallization of the hard coating becomes possible, and a surface coating member with even better adhesion resistance to titanium alloys can be obtained.

[0034] The upper limit of the hard coating thickness is not particularly limited, but for example, from the viewpoint of cost and productivity, the thickness of the hard coating is preferably 10 μm or less.

[0035] The surface-coated member according to this embodiment has a base material and a hard coating formed on the base material, thus maintaining the integrity of the coating and exhibiting excellent resistance to adhesion to titanium alloys. Therefore, the surface-coated member can be suitably used, for example, as a cutting tool for workpieces made of titanium alloys or as a sliding member that comes into contact with parts made of titanium alloys.

[0036] 2. Other configurations of the surface coating member In this embodiment, the surface coating member may, if necessary, have an underlayer between the substrate and the hard coating to further improve adhesion between the substrate and the hard coating, as long as the soundness of the coating and the excellent resistance to adhesion to titanium alloys of this embodiment are not impaired. The underlayer can be formed from, for example, one or more layers of metal, nitride, carbonitride, and carbide.

[0037] Furthermore, as long as the integrity of the coating of this embodiment and the excellent anti-adhesion effect on titanium alloys are not impaired, an upper layer having a composition and / or composition ratio that does not satisfy the aforementioned conditions for the component composition of the hard coating of this embodiment may be formed on top of the hard coating formed on the substrate.

[0038] Furthermore, another hard film (hereinafter referred to as "second hard film") may be formed on top of the hard film formed on the substrate (hereinafter referred to as "first hard film"), having a different composition and / or composition ratio from the first hard film, but satisfying the component composition conditions of the hard film in this embodiment described above. Also, yet another hard film (hereinafter referred to as "third hard film") may be formed on top of the laminated films, satisfying the component composition conditions of the hard film in this embodiment described above.

[0039] Alternatively, the first hard film and the second hard film (or the first hard film, the second hard film, and the third hard film) may be laminated together. Furthermore, the first hard film and the second hard film (or the first hard film, the second hard film, and the third hard film) may be laminated alternately in two or more layers. Alternatively, as long as the integrity of the film of the surface coating member of this embodiment and the excellent adhesion resistance to titanium alloy are not impaired, one or more layers of hard films containing nitrides, carbonitrides, oxides, or oxynitrides of metallic elements, metals, nitrides, carbonitrides, and carbides may be sandwiched between the laminated hard film structures that satisfy the aforementioned component composition conditions for the hard film in this embodiment.

[0040] When one or more such underlayers, upper layers and / or different hard coatings are formed, there is no particular limitation, but the total thickness of the stacked laminate is preferably 10 µm or less.

[0041] 3. Method for producing surface-coated member The surface-coated member according to the present embodiment can be produced by applying any vacuum film-forming method known to those skilled in the art to form (coat) a hard coating on a base material. Specifically, an arc ion plating method, a sputtering method, or the like can be applied for coating the hard coating. As an example, a method for producing a surface-coated member when the arc ion plating method is applied will be described below.

[0042] The film-forming apparatus used in the arc ion plating method includes, for example, an arc evaporation source provided with a target that is a material of the hard coating, an anode that serves as an inflow destination for electrons during arc discharge, an arc power supply for supplying arc current to the target, a chamber (vacuum vessel) for accommodating the base material, a base material rotating mechanism for rotating the base material in the chamber, a bias power supply for applying a bias voltage to the base material, a heater for heating the inside of the chamber and the base material, a vacuum pump for evacuating the inside of the chamber to a vacuum state, and a gas inlet for introducing one or both of an inert gas (argon, helium, neon, krypton, etc.) and a reactive gas (nitrogen gas) into the chamber. The film-forming apparatus may also be provided with a filter mechanism or the like capable of reducing droplets, which are lumps of the film-forming material, by means of a magnetic field.

[0043] In the method for producing a surface-coated member according to the present embodiment, Zr is used as the target 1-x Nd x (provided that 0.011 < x ≦ 0.607) There is no particular limitation as long as a coating having a metal component composition can be formed, and a target composed of Zr and Nd may be used.

[0044] In the film-forming method by arc ion plating, first, the inside of the chamber is evacuated to a vacuum. At this time, the vacuum pressure is 10×10-3 It is preferable to keep the pressure below Pa. By using a vacuum, oxidation of the substrate can be prevented by starting the heating of the substrate while there is a large amount of residual gas in the chamber.

[0045] After vacuuming, the substrate is heated. The heating temperature is preferably 300°C to 650°C at the workpiece temperature. Heating the substrate within this temperature range prevents a decrease in film adhesion due to insufficient diffusion at the substrate-film interface caused by excessively low temperatures, and also prevents the substrate material from softening due to heat.

[0046] Next, the substrate is etched. The etching process can be carried out by introducing an inert gas into the chamber, plasma-generating the inert gas, and causing the inert gas ions to collide with the substrate to which a negative bias voltage has been applied. Alternatively, the mounted arc evaporation source can be discharged together with the inert gas as desired, ionizing a target having a predetermined metal composition (for example, a target made of Ti or Cr) attached to the arc evaporation source, and the inert gas as desired, and causing these to collide with the substrate to carry out the etching process. If the arc evaporation source is discharged without using an inert gas, the etching process can be carried out using only metal ions.

[0047] During etching, a negative bias voltage is applied to the substrate. From the viewpoint of obtaining a sufficient etching effect, the applied voltage is preferably between -100V and -1000V. If the bias voltage applied to the substrate is too low, a sufficient etching effect may not be obtained. On the other hand, if the voltage is too high, abnormal discharge may occur on the substrate surface, potentially damaging the substrate.

[0048] After etching, a hard film is deposited on the substrate. Nitrogen gas is introduced into the chamber during film deposition. To stabilize the discharge, an inert gas may be mixed with the nitrogen gas.

[0049] In order to form a hard coating containing a nitride that is dense and excellent in strength, the pressure inside the chamber during film formation is preferably 0.5 Pa to 6 Pa. If the pressure is too low, the reaction between the evaporated metal and nitrogen gas becomes insufficient, and a desired nitride may not be formed in some cases. On the other hand, if the pressure is too high, collision between evaporated metal ions and the reaction gas may cause these ions to reach the base material in a state where they have lost energy. As a result, these ions cannot diffuse sufficiently on the surface of the base material, a dense coating cannot be formed, and this may cause a decrease in coating strength.

[0050] The bias voltage applied to the base material is preferably -15 V to -300 V. The arc current passed through the target is preferably 50 A to 200 A.

[0051] Through such a method, finally, (Zr 1-x Nd x )N (wherein in the formula, 0.011 < x ≦ 0.607) a hard coating having a component composition represented by the above is formed on a base material, and the surface-coated member according to the present embodiment can be manufactured.

[0052] Furthermore, as described above, when the surface-coated member manufactured in this manner is taken out into the atmosphere and left under the atmospheric atmosphere, a natural oxide film is formed on the surface of the nitride due to the influence of Nd in the hard coating. Therefore, the (Zr 1-x Nd x )N (wherein in the formula, 0.011 < x ≦ 0.607) hard coating having the component composition represented by the above, over time, has the same atomic ratio x of Nd, and becomes (Zr 1-x Nd x )N y O 1-y (wherein in the formula, 0 < y < 1) oxynitride or (Zr 1-x Nd x )O oxide can be changed into a hard coating of the oxide.

Examples

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples.

[0054] In this example, as described below, evaluation tests were conducted on the integrity of the coating according to the atomic ratio x of Nd to the total amount of Nd and Zr (total amount of metal elements), and on the adhesion resistance to titanium alloy according to the atomic ratio x of Nd to the total amount of Nd and Zr (total amount of metal elements).

[0055] [Evaluation Test 1: Evaluation test of film integrity according to the atomic ratio of Nd] In this evaluation test 1, first, multiple surface-coated samples were prepared in which hard coatings with an Nd composition gradient were formed by combinatorial deposition. Then, the atomic ratios of Nd and N were measured at multiple selected locations on the hard coatings of these samples. Furthermore, the integrity of the coatings at these measurement locations was evaluated.

[0056] <Method for manufacturing surface-coated samples> In this evaluation test 1, surface-coated samples with a hard film having a compositional gradient of Nd were manufactured using a UBMS system (UBMS202, manufactured by Kobe Steel, Ltd.) equipped with an unbalanced magnetron sputtering evaporation source.

[0057] In the chamber of the UBMS apparatus, two targets, a pure Zr target and a pure Nd target, and a sample consisting of a 4-inch Si wafer as the substrate were placed. Figure 1 shows a schematic diagram illustrating the arrangement of the two target evaporation sources and the substrate in the chamber of the UBMS apparatus in this embodiment. As shown in Figure 1, the Zr target evaporation source 1 and the Nd target evaporation source 2 were positioned in the chamber such that there was a 90° angle difference between them. Furthermore, in order to ultimately form a hard film with a compositional gradient of Zr and Nd, the sample as the substrate was placed on table 3 in the chamber such that there was a 45° angle difference with respect to both target evaporation sources.

[0058] After placing the target and the substrate, evacuation is performed to bring the inside of the chamber to 1×10 -2 less than Pa. Next, the inside of the chamber was heated at a heater temperature of 700°C for 30 minutes to remove residual moisture inside the chamber and on the sample surface. Furthermore, in order to remove the contaminated layer on the surfaces of the placed Zr target and Nd target, pre-sputtering was performed at 0.5 kW for 10 minutes. Subsequently, in order to improve the adhesion of the sample during film formation, Ar gas was introduced, and bombardment treatment was performed for 2 minutes under the conditions of a filament current of 5 A and a bias voltage of -500 V.

[0059] Thereafter, a hard nitride film having a composition gradient of Zr and Nd was formed on the sample to produce a surface-coated sample. Specifically, combinatorial film formation for forming a hard film having a composition gradient on the sample was performed by setting the inside of the chamber under an atmosphere of nitrogen and argon, setting the bias voltage to -70 V, and performing discharge at a constant input power for each target between 0.25 kW and 1 kW. By changing the value of the input power to each target for each sample, a plurality of surface-coated samples each having a wide range of component compositions on a single surface-coated sample were produced.

[0060] <Method for Measuring Atomic Ratio of Nd and N> Using the plurality of surface-coated samples produced by the aforementioned method, the atomic ratio of Nd and N was measured. Specifically, the atomic ratio of Nd and N was measured at a central portion in the vertical direction and at a plurality of arbitrary points in the horizontal direction during film formation of the surface-coated sample. The same measurement was performed for each surface-coated sample, and measurements were performed at a total of 25 locations. The measurement was carried out by EDX composition analysis using a scanning electron microscope energy dispersive X-ray spectrometer (SEM-EDX) (SEM: "S-3500N" manufactured by Hitachi, Ltd., EDX: "EMAX ENERGY" manufactured by Horiba, Ltd.), to measure the atomic ratio of Nd to the total amount of Zr and Nd (total amount of metal elements) and the atomic ratio of N to the total amount of N and O (total amount of non-metallic elements) at the selected 25 locations. The measurement results are summarized in Table 1 later, together with the evaluation results of the soundness of the coating film described below.

[0061] <Method for evaluating the integrity of the coating> The integrity of the coating was evaluated by visually inspecting the appearance of 25 locations on the film where the atomic ratios of Nd and N were measured using the method described above, and by observing them with the scanning electron microscope described above. Specifically, if defects such as blistering or peeling were observed on the film's appearance when visually inspected and when the visually inspected location was observed with a scanning electron microscope at a magnification of 2000x, the integrity of the coating was evaluated as "failure." On the other hand, if no defects such as blistering or peeling were observed on the film's appearance at the observed location, the integrity of the coating was evaluated as "acceptable."

[0062] The evaluation results of the integrity of the coating, along with the measurement results of the atomic ratios of Nd and N mentioned above, are summarized in Table 1 below. In Table 1 below, "UBMS" in the "Film Formation Method" column means that the hard coating was formed by the sputtering method using "UBMS202".

[0063] [Table 1]

[0064] Furthermore, Figure 2 shows a graph summarizing the results from Table 1 above, illustrating the relationship between the atomic ratio of Nd (x) to the total amount of Zr and Nd (total amount of metallic elements) and the atomic ratio of N (y) to the total amount of N and O (total amount of non-metallic elements) in Examples 1-1 to 1-15 and Comparative Examples 1-1 to 1-10.

[0065] <Consideration> As shown in Examples 1-1 to 1-15 of Table 1 above, when the atomic ratio (x) of Nd to the total amount of Zr and Nd (total amount of metal elements) in the hard coating was 0.607 or less, no defects were observed in the appearance of the coating, and the integrity of the coating was maintained.

[0066] Furthermore, as shown in Figure 2, in Examples 1-1 to 1-15, as the atomic ratio (x) of Nd to the total amount of Zr and Nd in the hard film (total amount of metallic elements) increased from 0.094 to 0.607, the atomic ratio of N to the total amount of N and O (total amount of non-metallic elements) decreased. This is thought to be because Nd forms a native oxide film, and as the atomic ratio x of Nd in the hard film increases, the oxidation rate increases, leading to an increase in the atomic ratio of O.

[0067] On the other hand, as shown in Comparative Examples 1-1 to 1-10 in Table 1 above, when the atomic ratio (x) of Nd to the total amount of Zr and Nd in the hard coating (total amount of metal elements) exceeded 0.607, defects such as blistering and peeling were observed on the surface of the coating, and the integrity of the coating was not maintained.

[0068] Thus, in the hard coatings of Examples 1-1 to 1-15, after the surface-coated samples were removed into the atmosphere, a native oxide film was formed on the surface of the nitride due to the influence of Nd in the hard coating. Although it changed into a hard coating of oxynitride with the same Nd atomic ratio x value, it is assumed that the integrity of the coating was maintained because the Nd atomic ratio x was 0.607 or less. On the other hand, in the hard coatings of Comparative Examples 1-1 to 1-10, the Nd atomic ratio x exceeded 0.607, and the influence of the native oxidation of Nd in the hard coating became excessively large. As a result, the integrity of the coating could not be maintained, and defects appeared in the film.

[0069] [Evaluation Test 2: Evaluation test of adhesion resistance to titanium alloys according to the atomic ratio of Nd] In this evaluation test 2, surface-coated samples were first prepared by combinatorial deposition to form a hard film with a compositional gradient of Nd. Surface-coated samples were also prepared with a hard film containing only Zr as the metallic element. Subsequently, the adhesion resistance to titanium alloys was evaluated at multiple selected locations on the hard film of these samples, corresponding to the atomic ratio of Nd, while measuring the atomic ratios of Nd and N at these measurement locations.

[0070] <Method for manufacturing surface-coated samples> (Preparation of surface-coated samples with a Nd composition gradient by sputtering method) Surface-coated samples with a hard film having an Nd composition gradient were manufactured using the same apparatus, target, and substrate as in Evaluation Test 1 described above, under the same film deposition process and conditions. Hereinafter, a hard film formed by the sputtering method using "UBMS202" will be referred to as "UBMS," as in Table 1 above, and samples manufactured in this manner will be referred to as "UBMS" surface-coated samples.

[0071] (Preparation of surface-coated samples with a compositional gradient of Nd by arc ion plating method) In this evaluation test 2, surface-coated samples were also manufactured using the arc ion plating method. Specifically, surface-coated samples with an Nd composition gradient were manufactured using an AIP (Automated Ion Plating) apparatus (AIP-S40, manufactured by Kobe Steel, Ltd.) equipped with an arc ion plating evaporation source.

[0072] Inside the chamber of the AIP apparatus, two pure Zr targets, one pure Nd target, and four substrates were arranged. Figure 3 shows a schematic diagram illustrating the arrangement of target evaporation sources and substrates in the arc ion plating apparatus in this embodiment. Specifically, as shown in Figure 3, in order to ultimately form a hard coating with a compositional gradient of Zr and Nd, the target evaporation sources were arranged on one side of the AIP apparatus from top to bottom in the order of Zr target evaporation source 1, Nd target evaporation source 2, and Zr target evaporation source 1. In addition, a sample made of cemented carbide (size: 13 mm x 5 mm) was used as the substrate 4 placed on table 3 and attached to the three-axis rotational axis inside the apparatus.

[0073] After positioning the target and substrate as described above, vacuum is applied to the chamber, and the contents of the chamber are 1 × 10 -2 The pressure was set to less than Pa. Next, the chamber was heated at a heater temperature of 900°C for 30 minutes. Subsequently, bombardment was performed for 15 minutes under the conditions of a filament current of 40A and a bias voltage of -400V.

[0074] Subsequently, a hard nitride film with a compositional gradient of Zr and Nd was formed on the sample to produce a surface-coated sample. Specifically, combinatorial deposition was performed by discharging a hard film with a compositional gradient in the longitudinal direction within the chamber under a nitrogen atmosphere, with a bias voltage of -70V, a table rotation of 1.5 rpm, and applying currents of 100A and 150A to the two Zr targets, respectively, and 100A to the Nd target. Hereinafter, the hard film formed by the arc ion plating method using "AIP-S40" will be referred to as "AIP1," and the sample produced in this manner will be referred to as an "AIP1" surface-coated sample.

[0075] (Preparation of surface-coated samples containing only Zr as a metallic element by arc ion plating method) Surface-coated samples containing only Zr as the metallic element were manufactured by the arc ion plating method using the apparatus ("UBMS202" manufactured by Kobe Steel, Ltd.) used in the aforementioned evaluation test 1, with only an evaporation source for a pure Zr target using the arc ion plating method attached.

[0076] Specifically, after placing a sample (size: 13mm x 5mm) consisting of a pure Zr target and a cemented carbide base material, a vacuum is applied, and the chamber is filled to 1 x 10⁻¹⁰ -2 The pressure was set to less than Pa. Next, the chamber was heated at a heater temperature of 700°C for 30 minutes. Subsequently, bombardment was performed for 5 minutes under the conditions of a filament current of 8A and a bias voltage of -400V.

[0077] Subsequently, a hard nitride film containing Zr was formed on the sample to produce a surface-coated sample. Specifically, by discharging while the chamber was under a nitrogen atmosphere, the bias voltage was set to -70V, the table rotation speed was set to 5rpm, and the target input current was set to 150A, a surface-coated sample was obtained in which a hard film containing only Zr as the metallic element was formed on the sample. Hereinafter, the hard film formed by the arc ion plating method using "UBMS202" will be referred to as "AIP2," and the sample produced in this manner will be referred to as an "AIP2" surface-coated sample.

[0078] <Method for evaluating the adhesion resistance of titanium alloys> The adhesion resistance to titanium alloys was evaluated using multiple surface-coated samples manufactured by the three methods described above. Specifically, the "UBMS" surface-coated sample has a gradient in the atomic ratio of Nd to the total amount of Zr and Nd (total amount of metal elements) on the surface where the hard film is formed. Therefore, a total of 12 evaluation points were arbitrarily selected from the hard film. The "AIP1" and "AIP2" surface-coated samples do not have a compositional distribution on the surface where the hard film is formed, so a total of three surface-coated samples were used for evaluation. Next, the adhesion resistance to titanium alloys at each of the selected points on the hard film was evaluated by performing a sliding test using titanium balls and determining the average coefficient of friction (specifically, the average coefficient of friction at a sliding distance of 0m to 3m).

[0079] Since titanium alloy easily adheres, when a sliding test using a titanium ball is performed, if the composition of the hard coating at the selected evaluation site is poor in adhesion resistance to titanium alloy, adhesion of titanium is likely to occur. When adhesion of titanium occurs, the titanium ball slides against the titanium adhered to the site, so it is expected that the average coefficient of friction obtained by the sliding test on the evaluation site will be high. Therefore, when the average coefficient of friction is 0.800 or less, the composition of the hard coating at the evaluation site is determined to be excellent in adhesion resistance to titanium alloy, and the evaluation was "Pass". On the other hand, when the average coefficient of friction exceeds 0.800, the composition of the hard coating at the evaluation site is determined to be poor in adhesion resistance to titanium alloy, and the evaluation was "Fail". Specifically, the sliding test was performed under the following conditions. (Sliding Test Conditions) Sliding tester: Tribometer (manufactured by CSM Instruments, "TRIBOMETER") Sliding method: reciprocating sliding by ball-on-disk Ball material: φ10 pure titanium ball Amplitude distance: 10 mm Maximum sliding speed: 0.02 m / sec Load: 1 N Sliding distance: 3 m

[0080] Note that when a hard coating is formed by an arc ion plating method, the surface roughness of the hard coating is larger than that when a hard coating is formed by a sputtering method. Therefore, the two types of surface-coated samples formed by the arc ion plating method were subjected to wet polishing using diamond paste to adjust the surface roughness to be equivalent to that in the case of film formation by the sputtering method, and then the above sliding test was performed. The evaluation results of adhesion resistance, together with the measurement results of the atomic ratio of Nd and N described below, are collectively shown in Table 2 below.

[0081] <Method for Measuring Atomic Ratio of Nd and N> The atomic ratios of Nd and N were measured at a total of 15 locations on the hard coating of surface-coated samples prepared using the three methods described above to evaluate adhesion resistance to titanium alloys. Specifically, for the unslidable areas in the center of the sliding marks at the evaluation locations on the hard coating where the sliding test was performed, EDX compositional analysis was performed in the same manner as described in Evaluation Test 1 above, and the atomic ratio of Nd to the total amount of Zr and Nd (total amount of metallic elements), and the atomic ratio of N to the total amount of N and O (total amount of non-metallic elements) were measured.

[0082] The measurement results of the atomic ratios of Nd and N, along with the evaluation results of the adhesion resistance to titanium alloys mentioned above, are summarized in Table 2 below. In Table 2 below, the meaning of the classification in the "Film Formation Method" column is as described above.

[0083] [Table 2]

[0084] Furthermore, Figure 4 is a graph summarizing the results from Table 2 above, showing the relationship between the atomic ratio (x) of Nd to the total amount of Zr and Nd (total amount of metallic elements) in Examples 2-1 to 2-12 and Comparative Examples 2-1 to 2-3, and the average coefficient of friction in the evaluation of adhesion resistance to titanium alloys.

[0085] <Consideration> As shown in Table 2 and Examples 2-1 to 2-12 in Figure 4 above, when the atomic ratio (x) of Nd to the total amount of Zr and Nd (total amount of metal elements) in the hard coating is greater than 0.011, the average coefficient of friction in the sliding test using titanium balls is low, and it is assumed that a surface coating member with excellent adhesion resistance to titanium alloys can be obtained. Furthermore, when the atomic ratio (x) of Nd to the total amount of Zr and Nd (total amount of metal elements) in the hard coating is preferably 0.109 or higher, and more preferably 0.303 or higher, the average coefficient of friction can be kept generally stable at a low value, and it is assumed that a surface coating member with even better adhesion resistance to titanium alloys can be obtained.

[0086] Furthermore, as shown in Examples 2-1 to 2-12 in Table 2 and Figure 4, considering the appearance of the film, it is assumed that by setting the atomic ratio (x) of Nd to the total amount of Zr and Nd in the hard film (total amount of metal elements) to be greater than 0.011 and less than or equal to 0.607, the integrity of the film can be maintained, and a surface coating member with excellent adhesion resistance to titanium alloys can be obtained.

[0087] On the other hand, as shown in Comparative Examples 2-2 and 2-3 in Table 2 and Figure 4 above, if the atomic ratio (x) of Nd to the total amount of Zr and Nd in the hard coating (total amount of metal elements) is significantly low, or if only Zr is present as a metal element, it is assumed that titanium adhesion occurs, resulting in a higher average coefficient of friction.

[0088] The embodiments and examples disclosed herein should be understood in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of symbols]

[0089] 1 Zr target evaporation source 2 Nd Target Evaporation Source 3 tables 4 Base material

Claims

1. A surface coating member having a base material and a hard coating formed on the base material, The hard coating is given by formula: (Zr １－ｘ Nd ｘ ) N ｙ O １－ｙ A surface coating member having a component composition represented by (wherein x represents the atomic ratio of Nd to the total amount of Nd and Zr, and y represents the atomic ratio of N to the total amount of N and O, with 0.011 < x ≤ 0.607 and 0 ≤ y ≤ 1).

2. The surface coating member according to claim 1, wherein in the above formula, 0.109 ≤ x.

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