Method for producing surface-smoothed metal member

Abstract

To provide a surface-smoothed metallic member which is smoothed to the extent that the maximum height roughness (Rz) of a flat part is ≤ 1.1 μm and the maximum height roughness (Rz) of a part having a curvature radius of 0. 05-2. 5mm is <2 μ m, and to provide a simple and efficient method for producing the same.SOLUTION: A method for producing a surface-smoothed metal member, comprising: anodizing a base material made of titanium or a titanium alloy to form an anodic oxide film on a surface of the base material; and removing the anodic oxide film to smooth the surface of the base material.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a metal member made of titanium or a titanium alloy that requires a smooth surface, and a method for manufacturing the same. [Background technology]

[0002] Titanium and titanium alloys are lightweight, have excellent corrosion resistance and high specific strength, and are used in a variety of applications, including structural components for aircraft and bicycles, engine parts, optical components, electronic components, and decorative items.

[0003] Here, the condition of the surface of components is often considered important, particularly in optical components and decorative items, and methods for smoothing the surface of components made of titanium or titanium alloys have been investigated.

[0004] For example, Patent Document 1 (JP 2008-223139 A) discloses a method for electrolytic polishing and / or electrochemical deburring the surface of titanium or a titanium-containing alloy, characterized in that the electrolytic solution used contains methanesulfonic acid and one or more alkanediphosphonic acids, and the one or more alkanediphosphonic acids may be selectively substituted with hydroxy groups and / or amino groups.

[0005] In the electrolytic polishing and / or electrochemical deburring method described in the above-mentioned Patent Document 1, the electrolyte used is not flammable, not particularly corrosive, easy to handle, and does not, in normal operation, pose a high risk to people working in or around the electrolytic polishing plant, or to the environment. In particular, the electrolyte described therein is said to not produce toxic gases or vapors.

[0006] Furthermore, Patent Document 2 (JP 2004-43850 A) discloses a method for etching titanium or a titanium alloy, characterized by treating the titanium or titanium alloy with an aqueous solution containing (a) 5 to 30 weight percent hydrogen peroxide, (b) 1 to 20 weight percent fluoride, (c) 1 to 10 weight percent of at least one acid selected from sulfuric acid, nitric acid, and phosphoric acid, and (d) 0.001 to 0.1 weight percent fluorine-based surfactant, wherein the weight ratio of [(a) hydrogen peroxide concentration] / [(b) fluorine concentration of fluoride] is 1.5 to 3.0.

[0007] The etching method for titanium or titanium alloys described in Patent Document 2 above is said to be capable of simultaneously removing scale from the surface of titanium or titanium alloys and smoothing the surface by etching with an aqueous solution containing hydrogen peroxide, fluoride, inorganic acid, and a fluorine-based surfactant. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-223139 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-43850 Summary of the Invention [Problem to be solved by the invention]

[0009] However, although the electrolytic polishing and / or electrochemical deburring method described in Patent Document 1 provides a good working environment, it does not improve smoothness compared to the prior art, as it is stated that "surface smoothing or deburring can be achieved to the same extent as, if not superior to, the methods described in the prior art."

[0010] Furthermore, the etching method for titanium or titanium alloys described in Patent Document 2 can simultaneously remove surface scales and smooth the surface, but the surface roughness obtained by smoothing is only about 0.4 μm, which is not sufficient for cases where higher smoothness is required.

[0011] Furthermore, the methods described in Patent Documents 1 and 2 only provide a relatively small area with a satisfactory smooth surface, making it difficult to efficiently reduce foreign matter or achieve a mirror finish over the entire surface of a large metal component. Furthermore, when a metal component has corners with an extremely small radius of curvature, or when the metal component has openings or through-holes, it is extremely difficult to smooth these inner surfaces.

[0012] In view of the problems in the prior art as described above, the present invention aims to provide a surface-smoothed metal component in which the surface of a large metal component made of titanium or a titanium alloy has been smoothed to such an extent that the maximum roughness in height (Rz) of the flat portion is 1.1 μm or less and the maximum roughness in height (Rz) of the portion with a radius of curvature of 0.05 to 2.5 mm is less than 2 μm, and a simple and efficient method for manufacturing the same.

[0013] Another object of the present invention is to provide a surface-smoothed metal component in which the maximum height roughness (Rz) of the inner walls of the through holes or openings is smoothed to a level of less than 2 μm, even for large metal components or metal components made of titanium or a titanium alloy having openings or through holes, and a simple and efficient method for manufacturing such a surface-smoothed metal component. [Means for solving the problem]

[0014] In order to achieve the above object, the inventors of the present invention have conducted extensive research into methods for smoothing the surface of metal components made of titanium or titanium alloys. As a result, they have discovered that removing an anodic oxide film formed under appropriate conditions is extremely effective, and have arrived at the present invention.

[0015] That is, the present invention provides: A metal member made of titanium or a titanium alloy, The maximum length of the metal member is 50 to 1000 mm, The maximum height roughness (Rz) of the surface flat portion of the metal member is 1.1 μm or less, The maximum height roughness (Rz) of a portion of the surface of the metal member having a curvature radius of 0.05 to 2.5 mm is less than 2 μm; Also provided is a surface-smoothed metal member characterized by:

[0016] The maximum length of the metal member is preferably 50 to 1000 mm, and more preferably 100 to 500 mm. It is difficult to smooth the entire surface of a large metal member using conventionally known methods. However, in the surface-smoothed metal member of the present invention, even for metal members with a maximum length of 50 mm or more, the maximum roughness in height (Rz) of the flat surface portion is 1.1 μm or less, and the maximum roughness in height (Rz) of the portion with a radius of curvature of 0.05 to 2.5 mm is less than 2 μm. Furthermore, by setting the maximum length of the metal member to 1000 mm or less, the maximum roughness in height (Rz) of the portion with a radius of curvature of 0.05 to 2.5 mm can be reliably kept to less than 2 μm.

[0017] The surface-smoothed metal member of the present invention preferably has through holes and / or openings in the metal member, and the maximum height roughness (Rz) of the inner walls of the through holes and / or openings is also less than 2 μm. In conventional surface-smoothed metal members, the area where a satisfactory smooth surface is formed is limited, and it is particularly difficult to smooth the inner walls of the through holes and openings, but in the surface-smoothed metal member of the present invention, the entire surface is sufficiently smooth.

[0018] The present invention also provides A metal member made of titanium or a titanium alloy, The maximum length of the metal member is 50 to 1000 mm, The arithmetic mean roughness (Ra) of a portion of the surface of the metal member having a radius of curvature of 0.05 to 2.5 mm is less than 0.4 μm; Also provided is a surface-smoothed metal member characterized by:

[0019] The maximum length of the metal member is preferably 50 to 1000 mm, and more preferably 100 to 500 mm. It is difficult to smooth the entire surface of a large metal member using conventionally known methods. However, in the surface-smoothed metal member of the present invention, even metal members with a maximum length of 50 mm or more have an arithmetic mean roughness (Ra) of less than 0.4 μm in the portion of the member surface where the radius of curvature is 0.05 to 2.5 mm. Furthermore, by setting the maximum length of the metal member to 1000 mm or less, the arithmetic mean roughness (Ra) of the portion of the member surface where the radius of curvature is 0.05 to 2.5 mm can be reliably kept to less than 0.4 μm.

[0020] The surface-smoothed metal member of the present invention preferably has through holes and / or openings in the metal member, and the arithmetic mean roughness (Ra) of the inner walls of the through holes and / or openings is also less than 0.4 μm. In conventional surface-smoothed metal members, the area where a satisfactory smooth surface is formed is limited, and it is particularly difficult to smooth the inner walls of the through holes and openings, but in the surface-smoothed metal member of the present invention, the entire surface is sufficiently smooth.

[0021] In the surface-smoothed metal member of the present invention, the through holes and / or openings preferably have an equivalent circle diameter of 0.1 to 5 mm. The more preferred equivalent circle diameter is 0.2 to 2 mm, and the most preferred equivalent circle diameter is 0.5 to 1 mm. Even when the surface-smoothed metal member of the present invention has fine through holes and / or openings with an equivalent circle diameter of 5 mm or less, the arithmetic mean roughness (Ra) and maximum height roughness (Rz) of the inner surface can be sufficiently reduced. Furthermore, when the equivalent circle diameter of the through holes and / or openings is 0.1 mm or more, the variability in the arithmetic mean roughness (Ra) and maximum height roughness (Rz) of the inner wall can be reduced.

[0022] In the surface-smoothed metal member of the present invention, the through holes and / or openings preferably have a depth of 1 to 50 mm. The opening depth is more preferably 1 to 10 mm, and most preferably 2 to 8 mm. In the surface-smoothed metal member of the present invention, even when deep through holes and / or openings having a depth of 1 mm or more are formed, the arithmetic mean roughness (Ra) and maximum height roughness (Rz) of the inner surface can be sufficiently reduced. Furthermore, if the depth of the through holes and / or openings is 50 mm or less, the arithmetic mean roughness (Ra) and maximum height roughness (Rz) of the inner wall can be reduced.

[0023] In the surface-smoothed metal member of the present invention, the metal member is preferably a frame, which can be suitably used as, for example, a pellicle frame.

[0024] The present invention also provides A substrate made of titanium or a titanium alloy is anodized to form an anodized film on the surface of the substrate; smoothing the surface of the substrate by removing the anodized coating; Also provided is a method for producing a surface-smoothed metal member, characterized by:

[0025] In the method for producing a surface-smoothed metal member of the present invention, the formation of an anodic oxide film consumes the convex portions of the substrate surface (metal member surface), thereby promoting smoothing, and the detachment of the anodic oxide film results in a smoothed surface. Additionally, the detachment of the anodic oxide film removes foreign matter adhering to the substrate surface, resulting in a clean surface. Furthermore, an anodic oxide film can be formed on a large substrate, allowing the surface of a large metal member to be smoothed.

[0026] In the method for producing a surface-smoothed metal member of the present invention, the thickness of the anodic oxide film is preferably 2 to 10 μm, and more preferably 4 to 6 μm, which not only efficiently consumes the protrusions on the substrate surface but also allows the anodic oxide film to naturally peel off without the need for any special process.

[0027] In the method for producing a surface-smoothed metal member of the present invention, the applied voltage in the anodizing treatment is preferably 20 to 100 V. The anodizing treatment conditions are not particularly limited as long as they do not impair the effects of the present invention, and various conventionally known treatment conditions can be used, but it is more preferable to apply a voltage of 40 to 50 V, which not only efficiently consumes the convex portions on the substrate surface but also allows the anodized film to naturally detach without the need for any special process.

[0028] Furthermore, in the method for producing a surface-smoothed metal member of the present invention, it is preferable to repeat the formation and removal of the anodized coating until an arithmetic mean roughness (Ra) of less than 0.4 μm and / or a maximum height roughness (Rz) of less than 2 μm is obtained on the surface of the substrate.

[0029] The formation and removal of the anodic oxide film leads to the smoothing of the substrate surface, and by repeating this process, it is possible to reliably achieve an arithmetic mean roughness (Ra) of less than 0.4 μm and / or a maximum height roughness (Rz) of less than 2 μm on the substrate surface. [Effects of the Invention]

[0030] According to the present invention, it is possible to provide a surface-smoothed metal member in which the surface of a large metal member made of titanium or a titanium alloy is smoothed to such an extent that the roughness in maximum height (Rz) of flat portions is 1.1 μm or less and the roughness in maximum height (Rz) of portions with a radius of curvature of 0.05 to 2.5 mm is less than 2 μm, and a simple and efficient method for producing the same. Furthermore, according to the present invention, it is possible to provide a surface-smoothed metal member in which the surface of a large metal member or a metal member made of titanium or a titanium alloy having openings or through holes is smoothed to such an extent that the roughness in maximum height (Rz) of the inner walls of the through holes or openings is also less than 2 μm, and a simple and efficient method for producing the same. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a schematic diagram of a pellicle frame, which is one embodiment of the surface-smoothed metal member of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line BB′ of FIG. [Figure 3] 1 is a schematic diagram of a surface smoothing process in the present invention. [Figure 4] 1 shows SEM photographs of the surface of a substrate for a pellicle frame before anodizing treatment, the surface of an anodized film, and the surface of a substrate for a pellicle frame from which the anodized film has been removed. [Figure 5] 1 is an SEM photograph of a cross section of a detached anodized coating and a pellicle frame substrate. [Figure 6] 1 shows SEM photographs of the surface of a substrate for a pellicle frame from which an anodized film has been removed, the surface of the anodized film, and a cross section of the anodized film when anodized at each voltage. [Figure 7] 1 shows SEM photographs of the side surface of a through hole before anodizing treatment and after removal of the anodized film. [Figure 8] FIG. 2 is a schematic diagram showing measurement lines of maximum height roughness (Rz) and arithmetic mean roughness (Ra). [Figure 9] These are microscope images of the surface of a pure titanium bar before and after anodizing treatment. [Figure 10] 1 shows microscope images of the inner surface of a through-hole before and after anodizing treatment. [Figure 11] 1 shows SEM photographs of the inner surface of a through-hole before and after anodizing treatment. DETAILED DESCRIPTION OF THE INVENTION

[0032] Below, a pellicle frame will be used as a representative example of a surface-smoothed metal member, and representative embodiments of the surface-smoothed metal member and its manufacturing method of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these. Furthermore, some or all of the components in the embodiments can be combined as appropriate. In the following description, identical or equivalent parts will be designated by the same reference numerals, and redundant explanations may be omitted. Furthermore, since the drawings are intended to conceptually explain the present invention, the dimensions and ratios of the components shown may differ from the actual dimensions.

[0033] 1.Smooth surface metal parts A schematic diagram of a pellicle frame, which is one embodiment of the surface-smoothed metal member of the present invention, is shown in Figure 1. The pellicle frame 1 is made of titanium or a titanium alloy, and all of its surfaces are smoothed.

[0034] The maximum length of the pellicle frame 1 is 50 to 1000 mm. Here, the maximum length of the pellicle frame 1 is the length of the diagonal line indicated by A in FIG. 1. The maximum length is preferably 100 to 500 mm, and more preferably 150 to 300 mm. Although it is difficult to smooth the entire surface of a large metal component using conventionally known techniques, the pellicle frame 1 has a maximum surface roughness (Rz) of 1.1 μm or less in the flat portion and a maximum surface roughness (Rz) of less than 2 μm in the portion with a radius of curvature of 0.05 to 2.5 mm, even when the maximum length is 50 mm or more. Furthermore, by setting the maximum length of the pellicle frame 1 to 1000 mm or less, the maximum surface roughness (Rz) of less than 2 μm in the portion with a radius of curvature of 0.05 to 2.5 mm can be reliably maintained.

[0035] Furthermore, in the pellicle frame 1, even when the maximum length is 50 mm or more, the arithmetic mean roughness (Ra) of the portion having a radius of curvature of 0.05 to 2.5 mm is less than 0.4 μm. Furthermore, by setting the maximum length to 1000 mm or less, the arithmetic mean roughness (Ra) of the portion having a radius of curvature of 0.05 to 2.5 mm can be reliably kept less than 0.4 μm.

[0036] The pellicle frame 1 has through holes and / or openings, and it is preferable that the maximum height roughness (Rz) of the inner walls of the through holes and / or openings is less than 2 μm and the arithmetic mean roughness (Ra) is less than 0.4 μm. Figure 1 shows a case where a through hole 2 is present, and Figure 2 shows a cross-sectional view taken along the line B-B' in Figure 1. The inner surface of the through hole 2, shown by the dotted line, is also sufficiently smoothed, with the maximum height roughness (Rz) being less than 2 μm and the arithmetic mean roughness (Ra) being less than 0.4 μm.

[0037] The equivalent circle diameter (R in FIG. 2) of the opening of the through hole 2 is preferably 0.1 to 5 mm. A more preferable equivalent circle diameter is 0.2 to 2 mm, and the most preferable equivalent circle diameter is 0.5 to 1 mm. In the pellicle frame 1, even when minute through holes 2 having an equivalent circle diameter of 5 mm or less are formed, the maximum height roughness (Rz) and arithmetic mean roughness (Ra) of the inner surface can be sufficiently reduced. Furthermore, if the equivalent circle diameter of the through hole 2 is 0.1 mm or more, the variation in the maximum height roughness (Rz) and arithmetic mean roughness (Ra) of the inner wall can be reduced.

[0038] Furthermore, the depth of the through holes 2 (D in FIG. 2) is preferably 1 to 50 mm. The depth of the through holes 2 is more preferably 1 to 10 mm, and most preferably 2 to 8 mm. In the pellicle frame 1, even when deep through holes having a depth of 1 mm or more are formed, the maximum height roughness (Rz) and arithmetic mean roughness (Ra) of the inner surface can be sufficiently reduced. Furthermore, if the depth of the through holes 2 is 50 mm or less, the variations in the maximum height roughness (Rz) and arithmetic mean roughness (Ra) of the inner wall can be reduced.

[0039] The shape of the pellicle frame 1 is not particularly limited as long as it does not impair the effects of the present invention, and can be any of a variety of conventionally known shapes depending on the shape of the exposure master, but generally, the planar shape of the pellicle frame 1 is ring-shaped, rectangular, or square, and has a size and shape that covers the circuit pattern portion provided on the exposure master.

[0040] The height (thickness) of the pellicle frame 1 is preferably 0.5 to 10 mm, more preferably 1 to 7 mm, and most preferably 1.0 to 3.0 mm. By setting the height (thickness) of the pellicle frame 1 to these values, deformation of the pellicle frame 1 can be suppressed and good handleability can be ensured.

[0041] The cross-sectional shape of the pellicle frame 1 is not particularly limited as long as it does not impair the effects of the present invention, and can be any of a variety of conventionally known shapes, but a quadrilateral with parallel upper and lower edges is preferred. The upper edge of the pellicle frame 1 must be wide enough to stretch the pellicle membrane, and the lower edge must be wide enough to provide an adhesive layer for bonding to the exposure master. For this reason, the widths of the upper and lower edges of the pellicle frame 1 are preferably approximately 1 to 3 mm.

[0042] Because the pellicle frame 1 is made of titanium or a titanium alloy, it has higher strength and Young's modulus than pellicle frames made of aluminum alloys, which have been commonly used in the past. In addition, titanium and titanium alloys are relatively light, with a specific gravity of approximately 4.5, which makes it possible to suppress an increase in the weight of the pellicle frame 1.

[0043] Furthermore, because the pellicle frame 1 is made of titanium or a titanium alloy, it has a lower coefficient of linear expansion than aluminum, effectively suppressing distortion during heating. Titanium and titanium alloys are also metallic materials that have superior toughness compared to ceramics and cemented carbide, making them easy to handle. Furthermore, because they have good processability, manufacturing costs can be reduced and high dimensional accuracy can be achieved for the pellicle frame 1.

[0044] Furthermore, when the surface-smoothed metal member of the present invention is an optical member, the linear expansion coefficient of the optical member is 6×10 -6 ~11×10 -6 / K. The linear expansion coefficient is preferably 6×10 -6 By setting the thermal expansion coefficient to 11×10 or higher, the thermal expansion coefficient of the optical member and that of the material made of ceramic, silicon, etc. become close. This makes it possible to reduce distortion and cracking caused by the difference in deformation due to thermal expansion when the temperature rises between the optical member and the member made of ceramic, silicon, etc. An example of a combination that can achieve this effect is when the optical member is a lens holder and the member made of ceramic, silicon, etc. is a lens for a camera, etc. Furthermore, when the linear expansion coefficient is 11×10 -6 By setting the coefficient of linear expansion to 7×10 or less, distortion during temperature rise can be reduced. -6 ~10×10 -6 / K, and the most preferable linear expansion coefficient is 8×10 -6 ~9×10 -6 / K. In this specification, the linear expansion coefficient represents a value in the temperature range of 0 to 100° C. These linear expansion coefficients can be achieved, for example, by making the optical member from titanium or a titanium alloy.

[0045] The titanium alloy used for the pellicle frame 1 is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known titanium alloys can be used. Examples of titanium alloys include Ti-6Al-4V alloy, Ti-6Al-6V-2Sn alloy, Ti-6Al-2Sn-4Zr-6Mo alloy, Ti-10V-2Fe-3Al alloy, Ti-7Al-4Mo alloy, Ti-5Al-2.5Sn alloy, Ti-6Al-5Zr-0.5Mo-0.2Si alloy, Ti-5.5Al-3.5Sn-3Zr-0.3Mo-1Nb-0.3Si alloy, and Ti i-8Al-1Mo-1V alloy, Ti-6Al-2Sn-4Zr-2Mo alloy, Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy, Ti-11.5Mo-6Zr-4.5Sn alloy, Examples include Ti-15V-3Cr-3Al-3Sn alloy, Ti-15Mo-5Zr-3Al alloy, Ti-15Mo-5Zr alloy, and Ti-13V-11Cr-3Al alloy.

[0046] When workability and corrosion resistance are important, it is preferable to use pure titanium. From the viewpoint of achieving both high strength and good workability, it is preferable to use an α+β type alloy. Furthermore, from the viewpoint of material price and availability, it is even more preferable to use a Ti-6Al-4V alloy.

[0047] In the above-described embodiment, the pellicle frame 1 has been described as an example of a surface-smoothed metal member, but the surface-smoothed metal member is not limited to this. For example, the surface-smoothed metal member can be a variety of optical members, such as a pellicle frame, a lens holder, a barrel, a shade, and a reflector.

[0048] 2. Manufacturing method for surface-smoothed metal parts When manufacturing a pellicle frame 1 with a smoothed surface using the method for manufacturing a surface-smoothed metal member of the present invention, a frame body made of titanium or a titanium alloy is anodized to form an anodized film on the surface of the frame body, and the surface of the frame body is smoothed by removing the anodized film.

[0049] A schematic diagram of the surface smoothing process is shown in Figure 3. The formation of an anodic oxide film consumes the protrusions on the frame surface, resulting in smoothing, and the removal of the anodic oxide film results in a smooth surface. In addition, foreign matter adhering to the frame surface is removed by the removal of the anodic oxide film, resulting in a clean surface.

[0050] It is extremely difficult to uniformly and easily smooth the surface of large components using conventional surface smoothing methods, but by using anodizing, it is possible to smooth the entire surface of a large pellicle frame 1 with a maximum length of 50 to 1000 mm.

[0051] The thickness of the anodic oxide film formed on the surface of the frame is preferably 2 to 10 μm. More preferably, the thickness of the anodic oxide film is 4 to 6 μm, which not only efficiently consumes the protrusions on the surface of the frame, but also allows the anodic oxide film to naturally detach without the need for any special process. If the anodic oxide film remains, it may be detached by applying ultrasonic vibrations, reverse electrolysis, or the like.

[0052] The applied voltage in the anodizing treatment is preferably 20 to 100 V. The anodizing treatment conditions are not particularly limited as long as they do not impair the effects of the present invention, and various conventionally known treatment conditions can be used, but it is more preferable to apply a voltage of 40 to 50 V, which not only efficiently consumes the convex portions on the frame surface but also allows the anodized film to naturally peel off without the need for any special process.

[0053] Furthermore, if the maximum roughness in height (Rz) of the frame surface is 2 μm or more after one anodized oxide film formation and removal, it is preferable to repeat the formation and removal of the anodized oxide film until this value becomes less than 2 μm. Because the formation and removal of the anodized oxide film progresses the smoothing of the frame surface, repeating this process can reliably make the maximum roughness in height (Rz) of the substrate surface less than 2 μm.

[0054] Furthermore, if the arithmetic mean roughness (Ra) of the frame surface is 0.4 μm or more after a single anodized film formation and removal, it is preferable to repeat the formation and removal of the anodized film until this value becomes less than 0.4 μm. Because the formation and removal of the anodized film progresses the smoothing of the frame surface, repeating this process can reliably make the arithmetic mean roughness (Ra) of the substrate surface less than 0.4 μm.

[0055] Representative embodiments of the present invention have been described above, but the present invention is not limited to these, and various design modifications are possible, all of which are included in the technical scope of the present invention. [Example]

[0056] Example 1 A frame body with a long side of 160 mm and a short side of 130 mm was cut out from pure titanium to prepare a pellicle frame substrate. The thickness and width of the pellicle frame substrate were the same, 1 mm and 4 mm, respectively.

[0057] The obtained pellicle frame substrate was subjected to anodizing treatment to form an anodized film over the entire surface. The anodizing treatment was carried out for 15 minutes at a bath temperature of 55°C and a voltage of 30 to 80 V, using an aqueous solution containing 5 g / L of ammonium fluoride and 134 g / L of ammonium sulfate as the anodizing bath.

[0058] When the voltage was 45 V, scanning electron microscope (SEM) photographs of the surface of the pellicle frame substrate before anodizing, the surface of the anodized film, and the surface of the pellicle frame substrate from which the anodized film had been detached are shown in Figure 4. Figure 5 also shows SEM photographs of the detached anodized film and a cross section of the pellicle frame substrate in the detached region. Most of the anodized film detached spontaneously during the anodizing process.

[0059] The surface of the pellicle frame substrate was remarkably smoothed by the removal of the anodized coating, and it was found to have a good smooth surface completely free of foreign matter. Furthermore, the cross-sectional photograph confirmed that the unevenness of the substrate surface was less than 0.4 μm. The smooth surface was formed over the entire surface of the pellicle frame substrate.

[0060] Figure 6 shows SEM photographs of the surface of the pellicle frame substrate from which the anodized film had been removed, the surface of the anodized film, and the cross section of the anodized film, for the pellicle frame substrate anodized at each voltage. The thickness and removal of the anodized film were also evaluated, and the results are shown here. Note that no spontaneous removal of the anodized film was observed when the voltage was 30 V.

[0061] 6 shows that there is a suitable voltage range for spontaneous detachment of the anodic oxide film, and that detachment can be promoted by applying a voltage of 40 to 50 V. The thickness of the anodic oxide film also affects the spontaneous detachment phenomenon, and detachment can be promoted by making the thickness of the anodic oxide film 4 to 6 μm.

[0062] <Example 2> An anodizing treatment was carried out for 10 minutes at a voltage of 45 V in the same manner as in Example 1, except that cylindrical through-holes with a diameter of 800 μm were provided in the thickness direction of the pellicle frame substrate.

[0063] SEM photographs of the side surface of the through-hole before anodizing and after the anodized film was removed are shown in Figure 7. It can be seen that the surface from which the anodized film was removed is significantly smoother than before anodizing.

[0064] Example 3 A 40mm x 4mm x 1mm square bar made of pure titanium was cut out, and a 0.8mm diameter through-hole was drilled through the 40mm x 1mm surface to the backside. Next, the surface of the bar was physically polished to remove burrs, and then chemically polished using a chemical polishing solution (TCP-08) at 30°C for 10 seconds. Next, as in Example 1, an anodizing treatment was performed for 10 minutes at a voltage of 45V.

[0065] The maximum height roughness (Rz) and arithmetic mean roughness (Ra) of the 40 mm × 1 mm surface (surface) and the inner surface of the through-hole were measured before anodizing (after chemical polishing) and after anodizing (after removal of the anodized film). A white light interference microscope was used for the measurements. Figure 8 shows a schematic diagram of the measurement line on the 40 mm × 1 mm surface. The length of the vertical measurement line was 322 μm, and the length of the horizontal measurement line was 244 μm. The measurement line on the inner surface of the through-hole was 322 μm in the axial direction. Measurements were performed in three regions in each of nine fields of view, and a total of 27 measurements were averaged. The results are shown in Table 1.

[0066] [Table 1]

[0067] The maximum roughness in height (Rz) and the arithmetic mean roughness (Ra) both decrease due to the detachment of the anodized film. The maximum roughness in height (Rz) of the flat surface is all 1.1 μm or less, and the maximum roughness in height (Rz) of the inner surface of the through hole is less than 2 μm. Furthermore, after anodizing, the arithmetic mean roughness (Ra) is less than 0.4 μm in all measurement areas.

[0068] The surface conditions before anodizing (after chemical polishing) and after anodizing (after removal of the anodized film) were observed using a scanning electron microscope (SEM) and a microscope. A microscope image of a 40 mm x 1 mm surface is shown in Figure 9, a microscope image of the inner surface of the through-hole is shown in Figure 10, and an SEM image of the inner surface of the through-hole is shown in Figure 11. In all of these images, it can be seen that the surface has been smoothed by the removal of the anodized film. [Explanation of symbols]

[0069] 1. Pellicle frame, 2. Through hole.

Claims

1. A substrate made of titanium or a titanium alloy is anodized to form an anodized film on the surface of the substrate; smoothing the surface of the substrate by removing the anodized coating; A method for producing a surface-smoothed metal member, comprising:

2. The thickness of the anodic oxide coating is 2 to 10 μm.

2. The method for producing a surface-smoothed metal member according to claim 1,

3. The applied voltage in the anodizing treatment is 20 to 100 V; 3. The method for producing a surface-smoothed metal member according to claim 1 or 2,

4. repeating the formation and removal of the anodized coating until an arithmetic mean roughness (Ra) of less than 0.4 μm and / or a maximum height roughness (Rz) of less than 2 μm is obtained on the surface of the substrate; 3. The method for producing a surface-smoothed metal member according to claim 1 or 2,

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