Coated substrate and method for producing coated substrate

Abstract

Provided is a novel coated substrate (1) which is applicable to various fields and from which high functionality can be expected. In the coated substrate (1), a substrate (5) is coated with a film (3). The thickness of the film (3) is 60 nm or greater and 10 µm or less. Measurement of the film (3) shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm% and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 80 atm% or greater. The relative density of the film (3) is 90% or greater, and the film (3) contains γ-Al2O3.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a coated substrate and a method for producing a coated substrate.BACKGROUND ART

[0002] Patent Literatures 1 to 4 disclose coated substrates having metal oxide films. In Patent Literatures 1 to 4, a wet film-formation method is employed. Meanwhile, in some cases, a dry film-formation method (dry process) has been employed so as to perform thickness control in accordance with complex substrate shapes.

[0003] In consideration of performance of coated substates in the case where they are applied to various fields, conventional coated substrates are not necessarily satisfactory, and development of a novel coated substrate has been desired.CITATION LISTPATENT LITERATURES

[0004] Patent Literature 1: JP2011-32521A Patent Literature 2: JP2009-147192A Patent Literature 3: JP2015-93821A Patent Literature 4: JPH9-202606A SUMMARY OF INVENTIONTECHNICAL PROBLEM

[0005] The present disclosure was made in view of the above-described circumstances, and an object is to provide a novel coated substrate which is applicable to various fields and from which high functionality can be expected. The present disclosure can be realized as the following modes.SOLUTION TO PROBLEM

[0006] [1] A coated substrate in which a substrate is coated with a film, in which the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 80 atm% or greater, the relative density of the film is 90% or greater, and the film contains γ-Al 2 O 3 . [2] The coated substrate recited in [1], wherein the film has a layered structure as a cross-sectional form. [3] The coated substrate recited in [1] or [2], wherein a portion of the substrate where the film is formed is electrically conductive. [4] The coated substrate recited in [2], wherein each layer of the layered structure has a thickness of 30 nm or greater and 500 nm or less. [5] The coated substrate recited in [1] or [2], wherein an oxide film due to oxidation of the substrate is not present between the film and the substate, or, in the case where an oxide film due to oxidation of the substrate is present between the film and the substate, the thickness of the oxide film is less than 100 nm. [6] A method for producing a coated substrate by using a bath liquid containing an organic solvent, wherein the water content of the bath liquid is less than 5 mass% and the bath liquid contains at least one or more types of metal elements and at least one or more types of halogen elements, a voltage is applied to a substrate, serving as a negative electrode, in a state in which the substrate is immersed in the bath liquid, thereby forming a film containing the metal element(s) on the substrate, and γ-Al 2 O 3 is formed by heat treatment in a non-oxidizing atmosphere. ADVANTAGEOUS EFFECT OF INVENTION

[0007] According to the present disclosure, there is provided a novel coated substrate which can be applied to various fields and can be mass produced.

[0008] In addition, in the coated substrate of the present disclosure, the followability of the film to deformation of the substrate is high.

[0009] In addition, in the coated substrate of the present disclosure, adhesion between the film and the substrate is high.BRIEF DESCRIPTION OF DRAWINGS

[0010] [FIG. 1] Schematic view showing a cross section of a coated substrate. [FIG. 2] Schematic view of a film formation apparatus. [FIG. 3] Chart showing the results (x-ray diffraction peak) of XRD measurement of Experimental example 1. DESCRIPTION OF EMBODIMENTS

[0011] The present disclosure will now be described in detail. Notably, in the present specification, in a description in which "-" is used for a numerical range, the numerical range contains its upper and lower limit values, unless otherwise specifically noted. For example, a description of "10 - 20" should be read to contain both "10" (lower limit value) and "20" (upper limit value). Namely, "10 - 20" has the same meaning as "10 or greater and 20 or less." Also, in the present specification, the upper and lower limit values of various numerical ranges may be combined freely.1. Coated substrate 1

[0012] A coated substrate 1 includes a substrate 5 coated with a film 3. The thickness of the film 3 is 60 nm or greater and 10 µm or less. Measurement of the film 3 shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 80 atm% or greater. The relative density of the film 3 is 90% or greater. The film 3 contains γ-Al 2 O 3 .(1) Substrate 5

[0013] No particular limitation is imposed on the substrate 5. In order to enhance adhesion of the film 3 to the substrate 5, at least a portion (region) of the substrate 5, which portion is to be coated with the film 3, is preferably formed of a material which is electrically conductive and can function as a negative electrode 7 (cathode). In the case where the portion of the substrate 5, which portion is to be coated with the film 3, is electrically conductive and functions as the negative electrode 7 (cathode), the film 3 can be easily formed on that portion by voltage application.

[0014] A surface portion of the substrate 5 may be formed of a material which is electrically conductive and can function as the negative electrode 7. The entire substrate 5 may be formed of a material which can function as the negative electrode 7. Examples of preferred materials which can serve as the negative electrode 7 include an iron-based alloy and carbon. Examples of preferred iron-based alloys include one or more types of alloys selected from Fe-Ni-Cr alloy (austenitic stainless steel), Fe-Cr alloy (ferritic stainless steel), Fe-Ni alloy (permalloy), Fe-Si alloy (silicon iron), Fe-Si-Al alloy (Sendust), Fe-Ni-Mo (supermalloy), Fe-Co alloy (permendur), Fe-Ni-Co alloy (Kovar), and Fe-C-B alloy (amorphous).(2) Film 3(2.1) Thickness

[0015] From the viewpoint of enabling the film 3 to exhibit a function corresponding to the material of the film 3, the thickness of the film 3 is 60 nm or greater, preferably 200 nm or greater, more preferably 300 nm or greater. Meanwhile, from the viewpoints of enabling the film 3 to endure stresses generated therein and securing adhesion to the substrate 5, the thickness of the film 3 is 10 µm or less, preferably 1000 nm or less, more preferably 800 nm or less. From these viewpoints, the thickness of the film 3 is 60 nm or greater and 10 µm or less, preferably 200 nm or greater and 1000 nm or less, more preferably 300 nm or greater and 800 nm or less. Notably, in the case where the thickness of the film 3 is not uniform, the film 3 satisfies the requirement regarding the thickness when the thickness of at least a portion of the film 3 falls within the above-described range. The thickness of the film 3 can be obtained through observation under an FIB-SEM (dual-beam scanning electron microscope).(2.2) Percentage of C (carbon) element

[0016] From the viewpoints of suppressing growth of crystal grains in the film 3 and stabilizing the properties of the film 3, the percentage of C (carbon) element determined through measurement by x-ray photoelectron spectroscopy (XPS method) is 0.1 atm% or greater, preferably 0.5 atm% or greater, more preferably 1 atm% or greater. Meanwhile, from the viewpoint of enabling the film 3 to sufficiently function as an inorganic film, the percentage of C (carbon) element is less than 10 atm%, preferably 8 atm% or less, more preferably 5 atm% or less. From these viewpoints, the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, preferably 0.5 atm% or greater and 8 atm% or less, more preferably 1 atm% or greater and 5 atm% or less. Notably, in the case where the composition of the film 3 is not uniform, the film 3 satisfies the requirement regarding the percentage of C (carbon) element when the composition of at least a portion of the film 3 falls within the above-described range.

[0017] The composition analysis by the x-ray photoelectron spectroscopy can be performed by using an x-ray photoelectron spectrometer. The measurement can be performed by scanning a cross section under the following measurement conditions: K-alpha rays of aluminum being used as an x-ray source, the beam diameter being set to 100 µm, and the x-ray incident angle in relation to a surface to be analyzed being set to 45°.(2.3) The sum of the percentage of the metal element and the percentage of O (oxygen) element

[0018] From the viewpoint of enabling the film 3 to sufficiently function as an inorganic film, the sum of the percentage of the metal element and the percentage of O (oxygen) element of the film 3 determined through measurement by the x-ray photoelectron spectroscopy (XPS method) is 80 atm% or greater, preferably 85 atm% or greater, more preferably 90 atm% or greater. Notably, the upper limit of the sum of the percentage of the metal element and the percentage of O (oxygen) element is a value obtained by subtracting the percentage (atm%) of C (carbon) element from 100 atm%. In the case where the composition of the film 3 is not uniform, the film 3 satisfies the requirement regarding the sum of the percentage of the metal element and the percentage of O (oxygen) element when the composition of at least a portion of the film 3 falls within the above-described range.(2.4) Relative density of film 3

[0019] From the viewpoint of enabling the film 3 to sufficiently exhibit the function of the film 3, the relative density of the film 3 is 90% or greater, preferably 95% or greater, more preferably 98% or greater. The relative density of the film 3 may be 100%.

[0020] The relative density of the film 3 is obtained by the following method. A TEM image of a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction is obtained. The area of pores in a field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension) is measured. The relative density (%) is obtained in accordance with the following expression (1). The average of the relative densities of 10 fields of view is the relative density of the film 3. Notably, in the case where the thickness of the film 3 is smaller than the vertical size of 300 nm, measurement is performed in fields of view determined in accordance with the thickness of the film 3. Relative density % = S 1 - S 2 / S 1 × 100 (In the expression, S1 is the area (nm 2< ) of the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension), and S2 is the total area (nm 2< ) of pores in the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension))(2.5) γ-Al 2 O 3

[0021] The film 3 contains γ-Al 2 O 3 . In the case where the film 3 contains γ-Al 2 O 3 (γ-Al 2 O 3 phase), the following action and effect are achieved. Although γ-Al 2 O 3 is lower in strength than α-Al 2 O 3 , γ-Al 2 O 3 is higher in flexibility than α-Al 2 O 3 . In the case where the film contains γ-Al 2 O 3 , the ability (followability) of the film 3 to follow the substrate 5 when the substrate 5 is deformed mechanically or as a result of thermal expansion becomes high.(2.6) Layered structure

[0022] The film 3 preferably has a layered structure as a cross-sectional form. The layered structure of the film 3 can be confirmed through observation of a cross section of the film 3 under the FIB-SEM (dual-beam scanning electron microscope), the cross section being obtained by cutting the film 3 in the film thickness direction.

[0023] Since the film 3 has a layered structure, internal cracking of the film 3 and peeling off of the film 3 from the substrate 5 can be prevented.(2.7) Thickness of each layer in layered structure

[0024] No particular limitation is imposed on the thickness of each layer in the layered structure.

[0025] From the viewpoint of securing the strength of the film 3, the thickness of each layer is preferably 30 nm or greater and 500 nm or less, more preferably 60 nm or greater and 200 nm or less, further preferably 80 nm or greater and 150 nm or less. The thickness of each layer can be obtained through observation of a cross section of the film 3 under the FIB-SEM (dual-beam scanning electron microscope), the cross section being obtained by cutting the film 3 in the film thickness direction.(2.8) Oxide film

[0026] It is preferred that an oxide film due to oxidation of the substrate 5 is not present between the film 3 and the substrate 5. If an oxide film due to oxidation of the substrate 5 is present between the film 3 and the substrate 5, the thickness of oxidation film is preferably less than 100 nm. In the case where this requirement is satisfied, adhesion of the film 3 to the substrate 5 improves, thereby enhancing the ability (followability) of the film 3 to follow the substrate 5 when the substrate 5 is deformed mechanically or as a result of thermal expansion. The determination as to whether or not an oxide film is present and obtainment of the thickness of the oxide film can be performed through observation of a cross section of the film 3 under the FIB-SEM (dual-beam scanning electron microscope), the cross section being obtained by cutting the film 3 in the film thickness direction.(2.9) Halogen element

[0027] The percentage of the halogen element as determined through measurement of the film 3 by x-ray photoelectron spectroscopy is preferably 0.1 atm% or greater, more preferably 0.3 atm% or greater, further preferably 0.5 atm% or greater. The upper limit value of the percentage of the halogen element is 3 atm% or less.

[0028] Since a small amount of halogen element is contained in the film 3, conceivably, the oxide film present on the surface of the substrate 5 is removed by the action of the halogen element, and the film 3 comes into direct contact with the substrate 5. As a result, the adhesion between the substrate 5 and the film 3 is secured. From the viewpoints of enabling quick progress of an organic electrochemical reaction and enabling the film 3 to function as a high-quality protection layer for the substrate 5, the halogen element is preferably at least one or more halogen elements selected from the group consisting of I (iodine), Cl (chlorine), and Br (bromine).(2.10) Metal element

[0029] No particular limitation is imposed on the metal element. From the viewpoint of facilitating formation of the film 3 having an increased strength by the production method described later, the metal element is preferably at least one or more metal elements selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), and Mn (manganese).2. Method for producing coated substrate 1

[0030] No particular limitation is imposed on a method for producing the coated substrate 1 of the present disclosure.

[0031] A preferred production method will now be described below. The preferred production method is a method for producing the coated substrate 1 by using a bath liquid 2 containing an organic solvent. The water content of the bath liquid 2 is less than 5 mass% and the bath liquid 2 contains at least one or more types of metal elements and at least one or more types of halogen elements. The present production method includes a forming step of forming the metal-element-containing film 3 on the substrate 5 on the negative electrode 7 side (on the cathode side), by applying a voltage in a state in which the substrate 5 is immersed in the bath liquid. In addition, in the present production method, γ-Al 2 O 3 is formed by heat treatment in a non-oxidizing atmosphere after the forming step (heat treatment step).

[0032] Notably, in the product method of the present disclosure, since electrodeposition is taken place on the negative electrode 7 side, oxidation of the substrate 5 can be suppressed as compared with the case where electrodeposition is taken place on the positive electrode 6 side (anode side).(1) Bath liquid 2

[0033] The bath liquid 2 contains an organic solvent.(1.1) Water content

[0034] From the viewpoints of guaranteeing the homogeneity of the film 3 and suppressing oxidation of the substrate 5, the water content of the bath liquid 2 is rendered less than 5 mass%. The water content is preferably less than 3 mass%, more preferably less than 0.1 mass%. The water content may be 0 mass%. The water content of the bath liquid 2 can be obtained by GC-MS analysis.(1.2) Metal element

[0035] The bath liquid 2 contains at least one or more types of metal elements. No particular limitation is imposed on the metal elements. From the viewpoint of causing the film 3 to function as a high quality protection film for the substrate 5, the metal element is preferably at least one or more metal elements selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), and Mn (manganese). In the production method of the present disclosure, an oxide film depending on the metal element(s) in the bath liquid 2 is formed as the film 3.

[0036] The metal element(s) contained in the bath liquid 2 may be supplied as a result of elution of the positive electrode 6 (anode). In the case where the metal element(s) elutes from the positive electrode 6 into the bath liquid 2, control of film formation speed becomes easy, and continuous and stable formation of films on a plurality of substrates 5 becomes possible. In the case where the metal element(s) is supplied to the bath liquid 2 as a result of elution of the positive electrode 6, at least one or more types of electrodes selected from an electrode of Al, an electrode of Ti, and an electrode of Mo are preferably used as the positive electrode 6.

[0037] The metal element(s) in the bath liquid 2 may be supplied from a metal alkoxide and / or an inorganic metal compound. In the case where the metal element(s) is supplied as a result of dissolution of a metal alkoxide and / or an inorganic metal compound, it is possible to cope with an element which is difficult to supply by eluting the positive electrode 6 (anode). Also, in this case, it becomes possible to perform film formation in which composition ratios are controlled by combining a plurality of metal elements.

[0038] Examples of the metal alkoxide include an aluminum alkoxide, a titanium alkoxide, and a molybdenum alkoxide.

[0039] Examples of the aluminum alkoxide include an aluminum trialkoxide. Examples of the aluminum trialkoxide include aluminum tripropoxides (e.g., aluminum triisopropoxide and aluminum tri-n-propoxide), aluminum triethoxide, aluminum tributoxides (e.g., aluminum tri-sec-butoxide and aluminum tri-n-butoxide).

[0040] Examples of the titanium alkoxide include a titanium trialkoxide, a titanium tetraalkoxide, and a titanium tetraalkoxide is preferred. Examples of the titanium tetraalkoxide include titanium tetrapropoxides (e.g., titanium tetraisopropoxide and titanium tetra-n-propoxide), titanium tetramethoxide, titanium tetraethoxide, titanium tetrabutoxides (e.g., titanium tetraisobutoxide and titanium tetra-n-butoxide), titanium tetrapentoxides, titanium tetrahexoxides, and titanium tetra (2-ethylhexoxide).

[0041] Examples of the inorganic metal compound include aluminum chloride, aluminum bromide, aluminum iodide, and titanium iodide.

[0042] In the case where the metal element(s) in the bath liquid 2 is supplied from a metal alkoxide and / or an inorganic metal compound, no particular limitation is imposed on the metal element concentration of the bath liquid 2. In this case, from the viewpoint of forming a satisfactory film 3, the metal element concentration of the bath liquid 2 is preferably 1 ppm or greater and 100 ppm or less, more preferably 3 ppm or greater and 10 ppm or less, further preferably 4 ppm or greater and 6 ppm or less. Notably, "ppm" means "parts per million" and "mg / L." Notably, in the case where the bath liquid 2 contains a plurality of metal elements, the above-described metal element concentration means the total concentration with respect to the plurality of metal elements. The metal element concentration of the bath liquid 2 can be measured by ICP-MS analysis.(1.3) Halogen element

[0043] The bath liquid 2 contains at least one or more types of halogen elements. Since the bath liquid 2 contains a halogen element(s), film formation is performed at a practical speed, and the film 3 is likely to become homogeneous. No particular limitation is imposed on the halogen element. From the viewpoints of enabling prompt progress of organic electrochemical reactions and causing the film 3 to function as a high quality protection film for the substrate 5, the halogen element(s) is preferably at least one or more halogen elements selected from the group consisting of Cl (chlorine), Br (bromine), and I (iodine).

[0044] No particular limitation is imposed on the halogen element concentration of the bath liquid 2. From the viewpoints of moderately reducing reaction speed, being advantageous for control of the homogeneity and thickness of the film 3, and preventing separation of the film 3, the halogen element concentration of the bath liquid 2 is preferably 1 ppm or greater and 20000 ppm or less, more preferably 5 ppm or greater and 2000 ppm or less, further preferably 10 ppm or greater and 100 ppm or less. Notably, "ppm" means "parts per million" and "mg / L." The halogen element concentration of the bath liquid 2 can be obtained from the amount of a halogen element(s) added at the time of making-up of the electrolytic bath or by ICP-MS analysis of the bath liquid.(1.4) Organic solvent

[0045] Since an organic solvent is used as the solvent of the bath liquid 2, generation of gas and oxidation of the substrate 5 itself during film formation are suppressed. From the viewpoint of satisfactory formation of the film 3, the solvent preferably contains at least one or more types of solvents selected from the group consisting of ketones and nitriles. In the case where the solvent contains a ketone and / or a nitrile, it is supposed that a condensation reaction occurs on the electrode surface (cathode surface) and electrodeposition becomes possible. Also, in the case where the solvent contains a ketone, conceivably, ketoenol tautomerism occurs in the presence of halogen, and the reactivity of the bath liquid 2 is enhanced.(1.4.1) Ketone

[0046] No particular limitation is imposed on the ketone so long as the ketone is an organic solvent having a carbonyl group (-C(=O)-) other than ester bond.

[0047] Examples of the ketone include acetone, methyl ethyl ketone (MEK), 1-hexanone, 2-hexanone, 4-heptanone, 2-heptanone (methyl amyl ketone), 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, diisobutyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, phenylacetone, acetophenone, methyl naphthyl ketone, cyclohexanone (CHN), and methylcyclohexanone. Among these, acetone and methyl ethyl ketone are preferred, because the film 3 is formed particularly satisfactorily.(1.4.2) Nitrile

[0048] Nitrile is an organic solvent which contains a nitrile group (-CN) in its structure. Examples of the nitrile include acetonitrile, propionitrile, valeronitrile, and butyronitrile. Among these, acetonitrile is preferred, because the film 3 is formed particularly satisfactorily.(2) Substrate 5

[0049] As to the "substrate 5," the description in the column entitled "(1) Substrate 5" in the above-described section entitled "1. Coated substrate 1" is applied as it is.(3) Forming step of forming the film 3 (voltage application)

[0050] In the present disclosure, by applying a voltage to the substrate 5 immersed in the bath liquid 2, a film 3 is formed on the substrate 5 on the negative electrode side. Specifically, the positive electrode 6 and the negative electrode 7 (the substrate 5) are immersed into the bath liquid 2, and a potential gradient is generated between the two electrodes.

[0051] Any of known electrically conductive substrates may be used as the positive electrode 6. In the case where the metal element(s) in the bath liquid 2 is supplied as a result of elution of the positive electrode 6, at least one or more types of electrodes selected from an electrode of Al, an electrode of Ti, and an electrode of Mo are preferably used as the positive electrode 6. No particular limitation is imposed on the shape, thickness, size, etc. of the positive electrode 6. The positive electrode 6 may be, for example, foil like, plate like, foam like, nonwoven fabric like, mesh like, felt like, or expanded metal like.

[0052] The positive electrode 6 and the negative electrode 7 are preferably disposed to face each other.

[0053] The positive electrode 6 and the negative electrode 7 are connected to a DC power supply, which can generate a potential gradient between the positive electrode 6 and the negative electrode 7.

[0054] For generation of a potential gradient between the positive electrode 6 and the negative electrode 7, in a state in which the positive electrode 6 and the negative electrode 7 are immersed in the bath liquid 2, a voltage (for example, constant voltage) is applied to the positive electrode 6 and the negative electrode 7 by the power supply connected to the positive electrode 6 and the negative electrode 7.

[0055] From the viewpoint of performing film formation at a practical speed, in the case where a constant voltage is applied, the potential gradient generated between the two electrodes is preferably 10 V or higher and 300 V or lower, more preferably 20 V or higher and 100 V or lower, further preferably 60 V or higher and 80 V or lower.

[0056] No particular limitation is imposed on an application time during which the volage is applied. The application time is, for example, preferably 10 seconds or longer and 300 seconds or shorter, more preferably 30 seconds or longer and 240 seconds or shorter, further preferably 60 seconds or longer and 180 seconds or shorter.

[0057] Notably, the voltage is not required to be a constant voltage and the magnitude of the voltage may be changed.

[0058] The forming step may be performed one time or a plurality of times. The thickness of the film 3 can be increased by repeating the forming step a plurality of times. The laminated structure (laminated, horizontally-striped structure) of the film 3 can be created by repeating the forming step a plurality of times as described above.(4) Heat treatment step

[0059] γ-Al 2 O 3 can be selectively produced in the film 3 through heat treatment in a non-oxidizing atmosphere.

[0060] The non-oxidizing atmosphere may be a reducing atmosphere, an inert atmosphere, or a vacuum atmosphere. The oxygen concentration in the non-oxidizing atmosphere is desirably less than 100 ppm.

[0061] No particular limitation is imposed on heat treatment temperature. From the viewpoint of selective production of γ-Al 2 O 3 , the heat treatment temperature is preferably 800°C or higher and 1300°C or lower, more preferably 900°C or higher and 1200°C or lower, further preferably 950°C or higher and 1050°C or lower.

[0062] No particular limitation is imposed on heat treatment time. From the viewpoint of selective production of γ-Al 2 O 3 , the heat treatment time is preferably 0.25 hours or longer and 3 hours or shorter, more preferably 0.5 hours or longer and 2 hours or shorter, further preferably 0.75 hours or longer and 1 hour or shorter.(5) Relation between the formation step and the heat treatment step

[0063] In the case where the forming step of forming the film 3 is performed a plurality of times, the heat treatment step may be performed after the last forming step.

[0064] Alternatively, in the case where the forming step of forming the film 3 is performed a plurality of times, the heat treatment step may be performed between the forming steps. In this case, the heat treatment step may be performed between each forming step (each of all the forming steps) and a forming step subsequent thereto. The case of performing the forming steps with performance of the heat treatment step therebetween and the case of performing the forming steps without performance of the heat treatment step may be mixedly present. Even in the case where the forming step of forming the film 3 is performed a plurality of times and the heat treatment step is performed between the forming steps, the heat treatment step may be performed after the last forming step.3. Action and effects of present embodiment

[0065] According to the present embodiment, there is provided the novel coated substrate 1 which is applicable to various fields and from which high functionality can be expected.

[0066] According to the present embodiment, the film 3 which is excellent in terms of adhesion to the substrate 5 can be formed. In addition, the thickness of the film 3 can be made larger as compared with conventional films.

[0067] In the coated substrate 1 of the present embodiment, since a dense protection film of the crystal phase of γ-Al 2 O 3 is formed, the ability (followability) of the film 3 to follow the substrate 5 when the substrate 5 is deformed mechanically or as a result of thermal expansion becomes high.

[0068] The coated substrate 1 of the present embodiment can be mass-produced by using a simple process.

[0069] The coated substrate 1 of the present embodiment can be formed without use of an expensive material or by using only a small amount of an expensive material. Therefore, the coated substrate 1 is advantageous in terms of cost.

[0070] Notably, presumably, the film formation mechanism in the present embodiment is as follows. It is presumed that an oxide film formation process occurs. In the oxide film formation process, a condensation reaction occurs at the negative electrode, while the metal element in the solvent is taken in, subsequently, dew condensation occurs on the surface of the substrate 5 due to heat of vaporization at the time of drying, and then hydrolysis occurs, whereby an oxide film is formed. However, this film formation mechanism is a mere conjecture, and the present disclosure is not bounded by this film formation mechanism.EXAMPLE

[0071] The present disclosure will be described further specifically by means of example.

[0072] Notably, in the following description, measurement conditions of XPS (x-ray photoelectron spectroscopy) are as follows.[Measurement conditions]

[0073] X-ray beam diameter: 100 µmΦ Signal reception angle: 45.0° Path energy: 140 eV Measurement was performed after Ar etching for 30 seconds (etching rate: 10 nm / min corresponding to SiO 2 ). 1. Experimental example (the solvent: acetone, the positive electrode 6: aluminum)(1) Production of the coated substrate 1

[0074] The film formation apparatus 11 shown in FIG. 2 was used. An aluminum wire was used as the positive electrode 6. A kovar plate was used as the negative electrode 7. The negative electrode 7 is a substrate 5 on which a film 3 is to be formed. Acetone was used as the solvent of the bath liquid 2. Iodine (halogen) was dissolved in the bath liquid 2 at a concentration of 50 ppm.

[0075] A forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for one minute in a state in which the positive electrode 6 and the negative electrode 7 were immersed in the bath liquid 2 was repeated 9 times.

[0076] Subsequently, heat treatment was performed at 1000°C in a non-oxidizing atmosphere (in a reducing atmosphere created by hydrogen gas) for 45 minutes.(2) Various measurement results

[0077] Observation of a cross section of the negative electrode 7 under an FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure and having a total thickness of 600 nm was formed on the surface of the substrate 5. The thickness of each layer was 50 nm or greater and 100 nm or less. It was confirmed by this observation that an oxide film due to oxidation of the substrate 5 was not present between the film 3 and the substrate 5. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was aluminum oxide.

[0078] The percentage of carbon element in the film 3 was 5.8 atm%, and the sum of the percentage of of aluminum and the percentage of oxygen was 93.9 atm%.

[0079] The percentage of iodine in this film 3 was 0.1 atm%.

[0080] Analysis was performed by XRD (x-ray crystallography) before heat treatment of the film 3 and after heat treatment of the film 3. As shown in FIG. 3, after the heat treatment, peaks (indicated by black dots) attributable to γ-Al 2 O 3 , which were not observed before the heat treatment, were observed. This result shows that γ-Al 2 O 3 , was produced in the film 3 as a result of the heat treatment.

[0081] The relative density of the film 3 determined by the following method was 100%.

[0082] Specifically, the relative density of the film 3 was determined as follows. A TEM image was obtained from a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction. The area of pores was measured in a field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension). The relative density (%) was obtained in accordance with the following expression (1). The average of the relative densities of 10 fields of view is the relative density of the film 3. Notably, in the case where the thickness of the film 3 is smaller than the vertical size of 300 nm, measurement is performed in fields of view determined in accordance with the thickness of the film 3. Relative density % = S 1 − S 2 / S 1 × 100 (In the expression, S1 is the area (nm 2< ) of the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension), and S2 is the total area (nm 2< ) of pores in the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension))2. Effect of Example

[0083] According to the present example, novel coated substrates 1 which are applicable to various fields and from which high functionality can be expected are provided.

[0084] The present invention is not limited to the embodiment described in detail above and various modifications and changes are possible within the range shown in the claims of the present invention.(Additional note)

[0085] The following inventions are contained in the present specification. [1] A coated substrate in which a substrate is coated with a film, wherein the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 80 atm% or greater, the relative density of the film is 90% or greater, and the film contains γ-Al 2 O 3 . [2] The coated substrate recited in [1], wherein the film has a layered structure as a cross-sectional form. [3] The coated substrate recited in [1] or [2], wherein a portion of the substrate where the film is formed is electrically conductive. [4] The coated substrate recited in [2] or [3], wherein each layer of the layered structure has a thickness of 30 nm or greater and 500 nm or less. [5] The coated substrate recited in any one of [1] to [4], wherein an oxide film due to oxidation of the substrate is not present between the film and the substate, or, in the case where an oxide film due to oxidation of the substrate is present between the film and the substate, the thickness of the oxide film is less than 100 nm. [6] A method for producing a coated substrate by using a bath liquid containing an organic solvent, wherein the water content of the bath liquid is less than 5 mass% and the bath liquid contains at least one or more types of metal elements and at least one or more types of halogen elements, a voltage is applied to a substrate, serving as a negative electrode, in a state in which the substrate is immersed in the bath liquid, thereby forming a film containing the metal element(s) on the substrate, and γ-Al 2 O 3 is formed by heat treatment in a non-oxidizing atmosphere. REFERENCE SIGNS LIST

[0086] 1: coated substrate 2: bath liquid 3: film 5: substrate 6: positive electrode 7: negative electrode 11: film formation apparatus

Examples

example

[0071]The present disclosure will be described further specifically by means of example.

[0072]Notably, in the following description, measurement conditions of XPS (x-ray photoelectron spectroscopy) are as follows.

[Measurement conditions]

[0073] X-ray beam diameter: 100 µmΦ Signal reception angle: 45.0° Path energy: 140 eV Measurement was performed after Ar etching for 30 seconds (etching rate: 10 nm / min corresponding to SiO 2 ).

1. Experimental example (the solvent: acetone, the positive electrode 6: aluminum)

(1) Production of the coated substrate 1

[0074]The film formation apparatus 11 shown in FIG. 2 was used. An aluminum wire was used as the positive electrode 6. A kovar plate was used as the negative electrode 7. The negative electrode 7 is a substrate 5 on which a film 3 is to be formed. Acetone was used as the solvent of the bath liquid 2. Iodine (halogen) was dissolved in the bath liquid 2 at a concentration of 50 ppm.

[0075]A forming step of applying a voltage of 80 V between t...

TECHNICAL FIELD

[0001] The present disclosure relates to a coated substrate and a method for producing a coated substrate.BACKGROUND ART

[0002] Patent Literatures 1 to 4 disclose coated substrates having metal oxide films. In Patent Literatures 1 to 4, a wet film-formation method is employed. Meanwhile, in some cases, a dry film-formation method (dry process) has been employed so as to perform thickness control in accordance with complex substrate shapes.

[0003] In consideration of performance of coated substates in the case where they are applied to various fields, conventional coated substrates are not necessarily satisfactory, and development of a novel coated substrate has been desired.CITATION LISTPATENT LITERATURES

[0004] Patent Literature 1: JP2011-32521A Patent Literature 2: JP2009-147192A Patent Literature 3: JP2015-93821A Patent Literature 4: JPH9-202606A SUMMARY OF INVENTIONTECHNICAL PROBLEM

[0005] The present disclosure was made in view of the above-described circumstances, and an object is to provide a novel coated substrate which is applicable to various fields and from which high functionality can be expected. The present disclosure can be realized as the following modes.SOLUTION TO PROBLEM

[0006] [1] A coated substrate in which a substrate is coated with a film, in which the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 80 atm% or greater, the relative density of the film is 90% or greater, and the film contains γ-Al 2 O 3 . [2] The coated substrate recited in [1], wherein the film has a layered structure as a cross-sectional form. [3] The coated substrate recited in [1] or [2], wherein a portion of the substrate where the film is formed is electrically conductive. [4] The coated substrate recited in [2], wherein each layer of the layered structure has a thickness of 30 nm or greater and 500 nm or less. [5] The coated substrate recited in [1] or [2], wherein an oxide film due to oxidation of the substrate is not present between the film and the substate, or, in the case where an oxide film due to oxidation of the substrate is present between the film and the substate, the thickness of the oxide film is less than 100 nm. [6] A method for producing a coated substrate by using a bath liquid containing an organic solvent, wherein the water content of the bath liquid is less than 5 mass% and the bath liquid contains at least one or more types of metal elements and at least one or more types of halogen elements, a voltage is applied to a substrate, serving as a negative electrode, in a state in which the substrate is immersed in the bath liquid, thereby forming a film containing the metal element(s) on the substrate, and γ-Al 2 O 3 is formed by heat treatment in a non-oxidizing atmosphere. ADVANTAGEOUS EFFECT OF INVENTION

[0007] According to the present disclosure, there is provided a novel coated substrate which can be applied to various fields and can be mass produced.

[0008] In addition, in the coated substrate of the present disclosure, the followability of the film to deformation of the substrate is high.

[0009] In addition, in the coated substrate of the present disclosure, adhesion between the film and the substrate is high.BRIEF DESCRIPTION OF DRAWINGS

[0010] [FIG. 1] Schematic view showing a cross section of a coated substrate. [FIG. 2] Schematic view of a film formation apparatus. [FIG. 3] Chart showing the results (x-ray diffraction peak) of XRD measurement of Experimental example 1. DESCRIPTION OF EMBODIMENTS

[0011] The present disclosure will now be described in detail. Notably, in the present specification, in a description in which "-" is used for a numerical range, the numerical range contains its upper and lower limit values, unless otherwise specifically noted. For example, a description of "10 - 20" should be read to contain both "10" (lower limit value) and "20" (upper limit value). Namely, "10 - 20" has the same meaning as "10 or greater and 20 or less." Also, in the present specification, the upper and lower limit values of various numerical ranges may be combined freely.1. Coated substrate 1

[0012] A coated substrate 1 includes a substrate 5 coated with a film 3. The thickness of the film 3 is 60 nm or greater and 10 µm or less. Measurement of the film 3 shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 80 atm% or greater. The relative density of the film 3 is 90% or greater. The film 3 contains γ-Al 2 O 3 .(1) Substrate 5

[0013] No particular limitation is imposed on the substrate 5. In order to enhance adhesion of the film 3 to the substrate 5, at least a portion (region) of the substrate 5, which portion is to be coated with the film 3, is preferably formed of a material which is electrically conductive and can function as a negative electrode 7 (cathode). In the case where the portion of the substrate 5, which portion is to be coated with the film 3, is electrically conductive and functions as the negative electrode 7 (cathode), the film 3 can be easily formed on that portion by voltage application.

[0014] A surface portion of the substrate 5 may be formed of a material which is electrically conductive and can function as the negative electrode 7. The entire substrate 5 may be formed of a material which can function as the negative electrode 7. Examples of preferred materials which can serve as the negative electrode 7 include an iron-based alloy and carbon. Examples of preferred iron-based alloys include one or more types of alloys selected from Fe-Ni-Cr alloy (austenitic stainless steel), Fe-Cr alloy (ferritic stainless steel), Fe-Ni alloy (permalloy), Fe-Si alloy (silicon iron), Fe-Si-Al alloy (Sendust), Fe-Ni-Mo (supermalloy), Fe-Co alloy (permendur), Fe-Ni-Co alloy (Kovar), and Fe-C-B alloy (amorphous).(2) Film 3(2.1) Thickness

[0015] From the viewpoint of enabling the film 3 to exhibit a function corresponding to the material of the film 3, the thickness of the film 3 is 60 nm or greater, preferably 200 nm or greater, more preferably 300 nm or greater. Meanwhile, from the viewpoints of enabling the film 3 to endure stresses generated therein and securing adhesion to the substrate 5, the thickness of the film 3 is 10 µm or less, preferably 1000 nm or less, more preferably 800 nm or less. From these viewpoints, the thickness of the film 3 is 60 nm or greater and 10 µm or less, preferably 200 nm or greater and 1000 nm or less, more preferably 300 nm or greater and 800 nm or less. Notably, in the case where the thickness of the film 3 is not uniform, the film 3 satisfies the requirement regarding the thickness when the thickness of at least a portion of the film 3 falls within the above-described range. The thickness of the film 3 can be obtained through observation under an FIB-SEM (dual-beam scanning electron microscope).(2.2) Percentage of C (carbon) element

[0016] From the viewpoints of suppressing growth of crystal grains in the film 3 and stabilizing the properties of the film 3, the percentage of C (carbon) element determined through measurement by x-ray photoelectron spectroscopy (XPS method) is 0.1 atm% or greater, preferably 0.5 atm% or greater, more preferably 1 atm% or greater. Meanwhile, from the viewpoint of enabling the film 3 to sufficiently function as an inorganic film, the percentage of C (carbon) element is less than 10 atm%, preferably 8 atm% or less, more preferably 5 atm% or less. From these viewpoints, the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, preferably 0.5 atm% or greater and 8 atm% or less, more preferably 1 atm% or greater and 5 atm% or less. Notably, in the case where the composition of the film 3 is not uniform, the film 3 satisfies the requirement regarding the percentage of C (carbon) element when the composition of at least a portion of the film 3 falls within the above-described range.

[0017] The composition analysis by the x-ray photoelectron spectroscopy can be performed by using an x-ray photoelectron spectrometer. The measurement can be performed by scanning a cross section under the following measurement conditions: K-alpha rays of aluminum being used as an x-ray source, the beam diameter being set to 100 µm, and the x-ray incident angle in relation to a surface to be analyzed being set to 45°.(2.3) The sum of the percentage of the metal element and the percentage of O (oxygen) element

[0018] From the viewpoint of enabling the film 3 to sufficiently function as an inorganic film, the sum of the percentage of the metal element and the percentage of O (oxygen) element of the film 3 determined through measurement by the x-ray photoelectron spectroscopy (XPS method) is 80 atm% or greater, preferably 85 atm% or greater, more preferably 90 atm% or greater. Notably, the upper limit of the sum of the percentage of the metal element and the percentage of O (oxygen) element is a value obtained by subtracting the percentage (atm%) of C (carbon) element from 100 atm%. In the case where the composition of the film 3 is not uniform, the film 3 satisfies the requirement regarding the sum of the percentage of the metal element and the percentage of O (oxygen) element when the composition of at least a portion of the film 3 falls within the above-described range.(2.4) Relative density of film 3

[0019] From the viewpoint of enabling the film 3 to sufficiently exhibit the function of the film 3, the relative density of the film 3 is 90% or greater, preferably 95% or greater, more preferably 98% or greater. The relative density of the film 3 may be 100%.

[0020] The relative density of the film 3 is obtained by the following method. A TEM image of a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction is obtained. The area of pores in a field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension) is measured. The relative density (%) is obtained in accordance with the following expression (1). The average of the relative densities of 10 fields of view is the relative density of the film 3. Notably, in the case where the thickness of the film 3 is smaller than the vertical size of 300 nm, measurement is performed in fields of view determined in accordance with the thickness of the film 3. Relative density % = S 1 - S 2 / S 1 × 100 (In the expression, S1 is the area (nm 2< ) of the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension), and S2 is the total area (nm 2< ) of pores in the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension))(2.5) γ-Al 2 O 3

[0021] The film 3 contains γ-Al 2 O 3 . In the case where the film 3 contains γ-Al 2 O 3 (γ-Al 2 O 3 phase), the following action and effect are achieved. Although γ-Al 2 O 3 is lower in strength than α-Al 2 O 3 , γ-Al 2 O 3 is higher in flexibility than α-Al 2 O 3 . In the case where the film contains γ-Al 2 O 3 , the ability (followability) of the film 3 to follow the substrate 5 when the substrate 5 is deformed mechanically or as a result of thermal expansion becomes high.(2.6) Layered structure

[0022] The film 3 preferably has a layered structure as a cross-sectional form. The layered structure of the film 3 can be confirmed through observation of a cross section of the film 3 under the FIB-SEM (dual-beam scanning electron microscope), the cross section being obtained by cutting the film 3 in the film thickness direction.

[0023] Since the film 3 has a layered structure, internal cracking of the film 3 and peeling off of the film 3 from the substrate 5 can be prevented.(2.7) Thickness of each layer in layered structure

[0024] No particular limitation is imposed on the thickness of each layer in the layered structure.

[0025] From the viewpoint of securing the strength of the film 3, the thickness of each layer is preferably 30 nm or greater and 500 nm or less, more preferably 60 nm or greater and 200 nm or less, further preferably 80 nm or greater and 150 nm or less. The thickness of each layer can be obtained through observation of a cross section of the film 3 under the FIB-SEM (dual-beam scanning electron microscope), the cross section being obtained by cutting the film 3 in the film thickness direction.(2.8) Oxide film

[0026] It is preferred that an oxide film due to oxidation of the substrate 5 is not present between the film 3 and the substrate 5. If an oxide film due to oxidation of the substrate 5 is present between the film 3 and the substrate 5, the thickness of oxidation film is preferably less than 100 nm. In the case where this requirement is satisfied, adhesion of the film 3 to the substrate 5 improves, thereby enhancing the ability (followability) of the film 3 to follow the substrate 5 when the substrate 5 is deformed mechanically or as a result of thermal expansion. The determination as to whether or not an oxide film is present and obtainment of the thickness of the oxide film can be performed through observation of a cross section of the film 3 under the FIB-SEM (dual-beam scanning electron microscope), the cross section being obtained by cutting the film 3 in the film thickness direction.(2.9) Halogen element

[0027] The percentage of the halogen element as determined through measurement of the film 3 by x-ray photoelectron spectroscopy is preferably 0.1 atm% or greater, more preferably 0.3 atm% or greater, further preferably 0.5 atm% or greater. The upper limit value of the percentage of the halogen element is 3 atm% or less.

[0028] Since a small amount of halogen element is contained in the film 3, conceivably, the oxide film present on the surface of the substrate 5 is removed by the action of the halogen element, and the film 3 comes into direct contact with the substrate 5. As a result, the adhesion between the substrate 5 and the film 3 is secured. From the viewpoints of enabling quick progress of an organic electrochemical reaction and enabling the film 3 to function as a high-quality protection layer for the substrate 5, the halogen element is preferably at least one or more halogen elements selected from the group consisting of I (iodine), Cl (chlorine), and Br (bromine).(2.10) Metal element

[0029] No particular limitation is imposed on the metal element. From the viewpoint of facilitating formation of the film 3 having an increased strength by the production method described later, the metal element is preferably at least one or more metal elements selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), and Mn (manganese).2. Method for producing coated substrate 1

[0030] No particular limitation is imposed on a method for producing the coated substrate 1 of the present disclosure.

[0031] A preferred production method will now be described below. The preferred production method is a method for producing the coated substrate 1 by using a bath liquid 2 containing an organic solvent. The water content of the bath liquid 2 is less than 5 mass% and the bath liquid 2 contains at least one or more types of metal elements and at least one or more types of halogen elements. The present production method includes a forming step of forming the metal-element-containing film 3 on the substrate 5 on the negative electrode 7 side (on the cathode side), by applying a voltage in a state in which the substrate 5 is immersed in the bath liquid. In addition, in the present production method, γ-Al 2 O 3 is formed by heat treatment in a non-oxidizing atmosphere after the forming step (heat treatment step).

[0032] Notably, in the product method of the present disclosure, since electrodeposition is taken place on the negative electrode 7 side, oxidation of the substrate 5 can be suppressed as compared with the case where electrodeposition is taken place on the positive electrode 6 side (anode side).(1) Bath liquid 2

[0033] The bath liquid 2 contains an organic solvent.(1.1) Water content

[0034] From the viewpoints of guaranteeing the homogeneity of the film 3 and suppressing oxidation of the substrate 5, the water content of the bath liquid 2 is rendered less than 5 mass%. The water content is preferably less than 3 mass%, more preferably less than 0.1 mass%. The water content may be 0 mass%. The water content of the bath liquid 2 can be obtained by GC-MS analysis.(1.2) Metal element

[0035] The bath liquid 2 contains at least one or more types of metal elements. No particular limitation is imposed on the metal elements. From the viewpoint of causing the film 3 to function as a high quality protection film for the substrate 5, the metal element is preferably at least one or more metal elements selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), and Mn (manganese). In the production method of the present disclosure, an oxide film depending on the metal element(s) in the bath liquid 2 is formed as the film 3.

[0036] The metal element(s) contained in the bath liquid 2 may be supplied as a result of elution of the positive electrode 6 (anode). In the case where the metal element(s) elutes from the positive electrode 6 into the bath liquid 2, control of film formation speed becomes easy, and continuous and stable formation of films on a plurality of substrates 5 becomes possible. In the case where the metal element(s) is supplied to the bath liquid 2 as a result of elution of the positive electrode 6, at least one or more types of electrodes selected from an electrode of Al, an electrode of Ti, and an electrode of Mo are preferably used as the positive electrode 6.

[0037] The metal element(s) in the bath liquid 2 may be supplied from a metal alkoxide and / or an inorganic metal compound. In the case where the metal element(s) is supplied as a result of dissolution of a metal alkoxide and / or an inorganic metal compound, it is possible to cope with an element which is difficult to supply by eluting the positive electrode 6 (anode). Also, in this case, it becomes possible to perform film formation in which composition ratios are controlled by combining a plurality of metal elements.

[0038] Examples of the metal alkoxide include an aluminum alkoxide, a titanium alkoxide, and a molybdenum alkoxide.

[0039] Examples of the aluminum alkoxide include an aluminum trialkoxide. Examples of the aluminum trialkoxide include aluminum tripropoxides (e.g., aluminum triisopropoxide and aluminum tri-n-propoxide), aluminum triethoxide, aluminum tributoxides (e.g., aluminum tri-sec-butoxide and aluminum tri-n-butoxide).

[0040] Examples of the titanium alkoxide include a titanium trialkoxide, a titanium tetraalkoxide, and a titanium tetraalkoxide is preferred. Examples of the titanium tetraalkoxide include titanium tetrapropoxides (e.g., titanium tetraisopropoxide and titanium tetra-n-propoxide), titanium tetramethoxide, titanium tetraethoxide, titanium tetrabutoxides (e.g., titanium tetraisobutoxide and titanium tetra-n-butoxide), titanium tetrapentoxides, titanium tetrahexoxides, and titanium tetra (2-ethylhexoxide).

[0041] Examples of the inorganic metal compound include aluminum chloride, aluminum bromide, aluminum iodide, and titanium iodide.

[0042] In the case where the metal element(s) in the bath liquid 2 is supplied from a metal alkoxide and / or an inorganic metal compound, no particular limitation is imposed on the metal element concentration of the bath liquid 2. In this case, from the viewpoint of forming a satisfactory film 3, the metal element concentration of the bath liquid 2 is preferably 1 ppm or greater and 100 ppm or less, more preferably 3 ppm or greater and 10 ppm or less, further preferably 4 ppm or greater and 6 ppm or less. Notably, "ppm" means "parts per million" and "mg / L." Notably, in the case where the bath liquid 2 contains a plurality of metal elements, the above-described metal element concentration means the total concentration with respect to the plurality of metal elements. The metal element concentration of the bath liquid 2 can be measured by ICP-MS analysis.(1.3) Halogen element

[0043] The bath liquid 2 contains at least one or more types of halogen elements. Since the bath liquid 2 contains a halogen element(s), film formation is performed at a practical speed, and the film 3 is likely to become homogeneous. No particular limitation is imposed on the halogen element. From the viewpoints of enabling prompt progress of organic electrochemical reactions and causing the film 3 to function as a high quality protection film for the substrate 5, the halogen element(s) is preferably at least one or more halogen elements selected from the group consisting of Cl (chlorine), Br (bromine), and I (iodine).

[0044] No particular limitation is imposed on the halogen element concentration of the bath liquid 2. From the viewpoints of moderately reducing reaction speed, being advantageous for control of the homogeneity and thickness of the film 3, and preventing separation of the film 3, the halogen element concentration of the bath liquid 2 is preferably 1 ppm or greater and 20000 ppm or less, more preferably 5 ppm or greater and 2000 ppm or less, further preferably 10 ppm or greater and 100 ppm or less. Notably, "ppm" means "parts per million" and "mg / L." The halogen element concentration of the bath liquid 2 can be obtained from the amount of a halogen element(s) added at the time of making-up of the electrolytic bath or by ICP-MS analysis of the bath liquid.(1.4) Organic solvent

[0045] Since an organic solvent is used as the solvent of the bath liquid 2, generation of gas and oxidation of the substrate 5 itself during film formation are suppressed. From the viewpoint of satisfactory formation of the film 3, the solvent preferably contains at least one or more types of solvents selected from the group consisting of ketones and nitriles. In the case where the solvent contains a ketone and / or a nitrile, it is supposed that a condensation reaction occurs on the electrode surface (cathode surface) and electrodeposition becomes possible. Also, in the case where the solvent contains a ketone, conceivably, ketoenol tautomerism occurs in the presence of halogen, and the reactivity of the bath liquid 2 is enhanced.(1.4.1) Ketone

[0046] No particular limitation is imposed on the ketone so long as the ketone is an organic solvent having a carbonyl group (-C(=O)-) other than ester bond.

[0047] Examples of the ketone include acetone, methyl ethyl ketone (MEK), 1-hexanone, 2-hexanone, 4-heptanone, 2-heptanone (methyl amyl ketone), 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, diisobutyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, phenylacetone, acetophenone, methyl naphthyl ketone, cyclohexanone (CHN), and methylcyclohexanone. Among these, acetone and methyl ethyl ketone are preferred, because the film 3 is formed particularly satisfactorily.(1.4.2) Nitrile

[0048] Nitrile is an organic solvent which contains a nitrile group (-CN) in its structure. Examples of the nitrile include acetonitrile, propionitrile, valeronitrile, and butyronitrile. Among these, acetonitrile is preferred, because the film 3 is formed particularly satisfactorily.(2) Substrate 5

[0049] As to the "substrate 5," the description in the column entitled "(1) Substrate 5" in the above-described section entitled "1. Coated substrate 1" is applied as it is.(3) Forming step of forming the film 3 (voltage application)

[0050] In the present disclosure, by applying a voltage to the substrate 5 immersed in the bath liquid 2, a film 3 is formed on the substrate 5 on the negative electrode side. Specifically, the positive electrode 6 and the negative electrode 7 (the substrate 5) are immersed into the bath liquid 2, and a potential gradient is generated between the two electrodes.

[0051] Any of known electrically conductive substrates may be used as the positive electrode 6. In the case where the metal element(s) in the bath liquid 2 is supplied as a result of elution of the positive electrode 6, at least one or more types of electrodes selected from an electrode of Al, an electrode of Ti, and an electrode of Mo are preferably used as the positive electrode 6. No particular limitation is imposed on the shape, thickness, size, etc. of the positive electrode 6. The positive electrode 6 may be, for example, foil like, plate like, foam like, nonwoven fabric like, mesh like, felt like, or expanded metal like.

[0052] The positive electrode 6 and the negative electrode 7 are preferably disposed to face each other.

[0053] The positive electrode 6 and the negative electrode 7 are connected to a DC power supply, which can generate a potential gradient between the positive electrode 6 and the negative electrode 7.

[0054] For generation of a potential gradient between the positive electrode 6 and the negative electrode 7, in a state in which the positive electrode 6 and the negative electrode 7 are immersed in the bath liquid 2, a voltage (for example, constant voltage) is applied to the positive electrode 6 and the negative electrode 7 by the power supply connected to the positive electrode 6 and the negative electrode 7.

[0055] From the viewpoint of performing film formation at a practical speed, in the case where a constant voltage is applied, the potential gradient generated between the two electrodes is preferably 10 V or higher and 300 V or lower, more preferably 20 V or higher and 100 V or lower, further preferably 60 V or higher and 80 V or lower.

[0056] No particular limitation is imposed on an application time during which the volage is applied. The application time is, for example, preferably 10 seconds or longer and 300 seconds or shorter, more preferably 30 seconds or longer and 240 seconds or shorter, further preferably 60 seconds or longer and 180 seconds or shorter.

[0057] Notably, the voltage is not required to be a constant voltage and the magnitude of the voltage may be changed.

[0058] The forming step may be performed one time or a plurality of times. The thickness of the film 3 can be increased by repeating the forming step a plurality of times. The laminated structure (laminated, horizontally-striped structure) of the film 3 can be created by repeating the forming step a plurality of times as described above.(4) Heat treatment step

[0059] γ-Al 2 O 3 can be selectively produced in the film 3 through heat treatment in a non-oxidizing atmosphere.

[0060] The non-oxidizing atmosphere may be a reducing atmosphere, an inert atmosphere, or a vacuum atmosphere. The oxygen concentration in the non-oxidizing atmosphere is desirably less than 100 ppm.

[0061] No particular limitation is imposed on heat treatment temperature. From the viewpoint of selective production of γ-Al 2 O 3 , the heat treatment temperature is preferably 800°C or higher and 1300°C or lower, more preferably 900°C or higher and 1200°C or lower, further preferably 950°C or higher and 1050°C or lower.

[0062] No particular limitation is imposed on heat treatment time. From the viewpoint of selective production of γ-Al 2 O 3 , the heat treatment time is preferably 0.25 hours or longer and 3 hours or shorter, more preferably 0.5 hours or longer and 2 hours or shorter, further preferably 0.75 hours or longer and 1 hour or shorter.(5) Relation between the formation step and the heat treatment step

[0063] In the case where the forming step of forming the film 3 is performed a plurality of times, the heat treatment step may be performed after the last forming step.

[0064] Alternatively, in the case where the forming step of forming the film 3 is performed a plurality of times, the heat treatment step may be performed between the forming steps. In this case, the heat treatment step may be performed between each forming step (each of all the forming steps) and a forming step subsequent thereto. The case of performing the forming steps with performance of the heat treatment step therebetween and the case of performing the forming steps without performance of the heat treatment step may be mixedly present. Even in the case where the forming step of forming the film 3 is performed a plurality of times and the heat treatment step is performed between the forming steps, the heat treatment step may be performed after the last forming step.3. Action and effects of present embodiment

[0065] According to the present embodiment, there is provided the novel coated substrate 1 which is applicable to various fields and from which high functionality can be expected.

[0066] According to the present embodiment, the film 3 which is excellent in terms of adhesion to the substrate 5 can be formed. In addition, the thickness of the film 3 can be made larger as compared with conventional films.

[0067] In the coated substrate 1 of the present embodiment, since a dense protection film of the crystal phase of γ-Al 2 O 3 is formed, the ability (followability) of the film 3 to follow the substrate 5 when the substrate 5 is deformed mechanically or as a result of thermal expansion becomes high.

[0068] The coated substrate 1 of the present embodiment can be mass-produced by using a simple process.

[0069] The coated substrate 1 of the present embodiment can be formed without use of an expensive material or by using only a small amount of an expensive material. Therefore, the coated substrate 1 is advantageous in terms of cost.

[0070] Notably, presumably, the film formation mechanism in the present embodiment is as follows. It is presumed that an oxide film formation process occurs. In the oxide film formation process, a condensation reaction occurs at the negative electrode, while the metal element in the solvent is taken in, subsequently, dew condensation occurs on the surface of the substrate 5 due to heat of vaporization at the time of drying, and then hydrolysis occurs, whereby an oxide film is formed. However, this film formation mechanism is a mere conjecture, and the present disclosure is not bounded by this film formation mechanism.EXAMPLE

[0071] The present disclosure will be described further specifically by means of example.

[0072] Notably, in the following description, measurement conditions of XPS (x-ray photoelectron spectroscopy) are as follows.[Measurement conditions]

[0073] X-ray beam diameter: 100 µmΦ Signal reception angle: 45.0° Path energy: 140 eV Measurement was performed after Ar etching for 30 seconds (etching rate: 10 nm / min corresponding to SiO 2 ). 1. Experimental example (the solvent: acetone, the positive electrode 6: aluminum)(1) Production of the coated substrate 1

[0074] The film formation apparatus 11 shown in FIG. 2 was used. An aluminum wire was used as the positive electrode 6. A kovar plate was used as the negative electrode 7. The negative electrode 7 is a substrate 5 on which a film 3 is to be formed. Acetone was used as the solvent of the bath liquid 2. Iodine (halogen) was dissolved in the bath liquid 2 at a concentration of 50 ppm.

[0075] A forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for one minute in a state in which the positive electrode 6 and the negative electrode 7 were immersed in the bath liquid 2 was repeated 9 times.

[0076] Subsequently, heat treatment was performed at 1000°C in a non-oxidizing atmosphere (in a reducing atmosphere created by hydrogen gas) for 45 minutes.(2) Various measurement results

[0077] Observation of a cross section of the negative electrode 7 under an FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure and having a total thickness of 600 nm was formed on the surface of the substrate 5. The thickness of each layer was 50 nm or greater and 100 nm or less. It was confirmed by this observation that an oxide film due to oxidation of the substrate 5 was not present between the film 3 and the substrate 5. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was aluminum oxide.

[0078] The percentage of carbon element in the film 3 was 5.8 atm%, and the sum of the percentage of of aluminum and the percentage of oxygen was 93.9 atm%.

[0079] The percentage of iodine in this film 3 was 0.1 atm%.

[0080] Analysis was performed by XRD (x-ray crystallography) before heat treatment of the film 3 and after heat treatment of the film 3. As shown in FIG. 3, after the heat treatment, peaks (indicated by black dots) attributable to γ-Al 2 O 3 , which were not observed before the heat treatment, were observed. This result shows that γ-Al 2 O 3 , was produced in the film 3 as a result of the heat treatment.

[0081] The relative density of the film 3 determined by the following method was 100%.

[0082] Specifically, the relative density of the film 3 was determined as follows. A TEM image was obtained from a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction. The area of pores was measured in a field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension). The relative density (%) was obtained in accordance with the following expression (1). The average of the relative densities of 10 fields of view is the relative density of the film 3. Notably, in the case where the thickness of the film 3 is smaller than the vertical size of 300 nm, measurement is performed in fields of view determined in accordance with the thickness of the film 3. Relative density % = S 1 − S 2 / S 1 × 100 (In the expression, S1 is the area (nm 2< ) of the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension), and S2 is the total area (nm 2< ) of pores in the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension))2. Effect of Example

[0083] According to the present example, novel coated substrates 1 which are applicable to various fields and from which high functionality can be expected are provided.

[0084] The present invention is not limited to the embodiment described in detail above and various modifications and changes are possible within the range shown in the claims of the present invention.(Additional note)

[0085] The following inventions are contained in the present specification. [1] A coated substrate in which a substrate is coated with a film, wherein the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 80 atm% or greater, the relative density of the film is 90% or greater, and the film contains γ-Al 2 O 3 . [2] The coated substrate recited in [1], wherein the film has a layered structure as a cross-sectional form. [3] The coated substrate recited in [1] or [2], wherein a portion of the substrate where the film is formed is electrically conductive. [4] The coated substrate recited in [2] or [3], wherein each layer of the layered structure has a thickness of 30 nm or greater and 500 nm or less. [5] The coated substrate recited in any one of [1] to [4], wherein an oxide film due to oxidation of the substrate is not present between the film and the substate, or, in the case where an oxide film due to oxidation of the substrate is present between the film and the substate, the thickness of the oxide film is less than 100 nm. [6] A method for producing a coated substrate by using a bath liquid containing an organic solvent, wherein the water content of the bath liquid is less than 5 mass% and the bath liquid contains at least one or more types of metal elements and at least one or more types of halogen elements, a voltage is applied to a substrate, serving as a negative electrode, in a state in which the substrate is immersed in the bath liquid, thereby forming a film containing the metal element(s) on the substrate, and γ-Al 2 O 3 is formed by heat treatment in a non-oxidizing atmosphere. REFERENCE SIGNS LIST

[0086] 1: coated substrate 2: bath liquid 3: film 5: substrate 6: positive electrode 7: negative electrode 11: film formation apparatus

Examples

example

[0071]The present disclosure will be described further specifically by means of example.

[0072]Notably, in the following description, measurement conditions of XPS (x-ray photoelectron spectroscopy) are as follows.

[Measurement conditions]

[0073] X-ray beam diameter: 100 µmΦ Signal reception angle: 45.0° Path energy: 140 eV Measurement was performed after Ar etching for 30 seconds (etching rate: 10 nm / min corresponding to SiO 2 ).

1. Experimental example (the solvent: acetone, the positive electrode 6: aluminum)

(1) Production of the coated substrate 1

[0074]The film formation apparatus 11 shown in FIG. 2 was used. An aluminum wire was used as the positive electrode 6. A kovar plate was used as the negative electrode 7. The negative electrode 7 is a substrate 5 on which a film 3 is to be formed. Acetone was used as the solvent of the bath liquid 2. Iodine (halogen) was dissolved in the bath liquid 2 at a concentration of 50 ppm.

[0075]A forming step of applying a voltage of 80 V between t...

Claims

1. A coated substrate in which a substrate is coated with a film, wherein the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 10 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 80 atm% or greater, the relative density of the film is 90% or greater, and the film contains γ-Al2O3.

2. The coated substrate according to claim 1, wherein the film has a layered structure as a cross-sectional form.

3. The coated substrate according to claim 1 or 2, wherein a portion of the substrate where the film is formed is electrically conductive.

4. The coated substrate according to claim 2, wherein each layer of the layered structure has a thickness of 30 nm or greater and 500 nm or less.

5. The coated substrate according to claim 1 or 2, wherein an oxide film due to oxidation of the substrate is not present between the film and the substate, or, in the case where an oxide film due to oxidation of the substrate is present between the film and the substate, the thickness of the oxide film is less than 100 nm.

6. A method for producing a coated substrate by using a bath liquid containing an organic solvent, wherein the water content of the bath liquid is less than 5 mass% and the bath liquid contains at least one or more types of metal elements and at least one or more types of halogen elements, a voltage is applied to a substrate, serving as a negative electrode, in a state in which the substrate is immersed in the bath liquid, thereby forming a film containing the metal element(s) on the substrate, and γ-Al2O3 is formed by heat treatment in a non-oxidizing atmosphere.

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