Titanium materials and methods for manufacturing titanium materials

Abstract

One aspect of the present invention is a titanium material based on pure titanium or titanium alloy. When analyzing the composition of the surface constituting the titanium material using X-ray photoelectron spectroscopy, the maximum Si concentration on the material surface from the outermost surface along the depth direction to a position of 50 nm is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration within the depth direction where either Si or Al concentration is 1 atomic% or more is 20 atomic% or more and 50 atomic% or less. The color measurement value of the surface of the titanium material, determined according to JIS Z 8781-4:2013, is L. * : 55~75, a * : 1.0~2.0, b * : 4.0~8.0.

Description

Technical Field

[0001] This invention relates to titanium materials and methods for manufacturing titanium materials. This application claims priority based on Japanese Patent Application No. 2024-001391, filed on January 9, 2024, the contents of which are incorporated herein by reference. Background Technology

[0002] Titanium materials are broadly classified into non-colorable materials that exhibit the silvery hue of metallic titanium and colored materials that display interference colors. Both non-colorable and colored materials sometimes change color upon prolonged exposure to the atmosphere. This discoloration is known to be caused by interference colors resulting from an increase in the thickness of the oxide coating on the titanium surface to approximately tens of nanometers in acidic environments with a pH below 4.5, such as acid rain. Such a tens-of-nanometers-thickness oxide coating does not impair the corrosion resistance of titanium. However, for aesthetically important areas such as building walls and roofs, there is a demand for titanium materials, especially non-colorable materials, that are less prone to interference colors caused by an increase in the thickness of the oxide coating. The development of such titanium materials is underway.

[0003] For example, Patent Document 1 discloses a titanium material that is not easily discolored in an atmospheric environment, characterized in that the average carbon concentration in the range of 100 nm from the outermost surface is less than 14 atomic%, and the outermost surface has an oxide coating with a thickness of 12 to 40 nm.

[0004] Patent document 2 discloses a titanium material that is not prone to discoloration, characterized in that the fluorine content in the oxide coating on the surface is less than 7 atomic%.

[0005] Patent document 3 discloses a titanium material that is not easily discolored in an atmospheric environment. Its characteristic is that the oxide coating formed on the titanium surface, existing in a range from the titanium surface to 3 nm, has a titanium oxide composition set to TiO₂. x In this case, x is in the range of 0.8 to 1.8, and the density of the oxide coating is 4.2 g / cm³. 3 The titanium material disclosed in Patent Document 3 is manufactured by treating the titanium surface with a mixed solution of nitric acid and hydrofluoric acid, followed by treatment with a nitric acid solution.

[0006] Patent Document 4 discloses a pure titanium material for building materials, characterized in that, as a pure titanium material used in building materials, the impurity elements Fe are suppressed to below 0.08% by mass, Nb to below 0.02% by mass, and Co to below 0.02% by mass. The pure titanium material disclosed in Patent Document 4 is manufactured by heating at 130-280°C for a specified time in the final process, after pickling, in atmosphere or vacuum.

[0007] Patent document 5 discloses a titanium alloy with excellent resistance to discoloration in acid rain environments. The titanium alloy is characterized by a base material of titanium or a titanium alloy, on which a nitrogen-rich titanium layer with a thickness of 0.2–1.5 μm is formed. This nitrogen-rich titanium layer contains 20–60 atomic percent nitrogen and 1–40 atomic percent oxygen on average atomic percent. Furthermore, the ratio of Ti (average atomic percent) to N (average atomic percent) in the outermost 0.1 μm range is in the range of 1.2–4.0. The average carbon concentration in the range from the base material surface to a depth of 0.2 μm inward is 1 atomic percent or more and 15 atomic percent or less. The color measurement value L… * a * b * The values ​​are 40~80, -6~6, and -6~9 respectively, and they have a silvery appearance. The titanium material disclosed in Patent Document 5 is manufactured by ion plating.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2002-12962

[0011] Patent Document 2: Japanese Patent Application Publication No. 2002-47589

[0012] Patent Document 3: Japanese Patent Application Publication No. 2005-154882

[0013] Patent Document 4: Japanese Patent Application Publication No. 2004-300569

[0014] Patent Document 5: Japanese Patent Application Publication No. 2010-265531 Summary of the Invention

[0015] The problem the invention aims to solve

[0016] Uncolored materials require high resistance to discoloration without producing interference colors. Furthermore, in recent years, there has been a demand for titanium materials that do not easily discolor, even in acidic environments below pH 3.0 or in environments where repeated wetting and drying cause the pH of the adhering liquid to drop.

[0017] In Patent Documents 1-4, the evaluation of colorfastness is as follows: The titanium material is immersed in a sulfuric acid aqueous solution at pH 3 or pH 4 at 60°C for several days, and the color difference before and after immersion is used to evaluate the colorfastness. Specifically, it is described that the color difference after immersion in a sulfuric acid aqueous solution at pH 3 at 60°C for 7 or 14 days is 3 to 7 or less, or the color difference after immersion in a sulfuric acid aqueous solution at pH 4 at 60°C for 3 days is less than 5, and further less than 1. However, the above evaluation of colorfastness does not fully reflect its use in high-temperature environments. Furthermore, when the titanium material described in Patent Documents 1-4 is immersed in a sulfuric acid aqueous solution at 80°C and pH 4 for 4 days, the color difference before and after immersion is approximately 15 or more. Conventional titanium materials do not exhibit sufficient colorfastness under higher temperature conditions.

[0018] Furthermore, in the technology described in Patent Document 3, the titanium surface is treated with a mixed solution of nitric acid and hydrofluoric acid, followed by treatment with nitric acid solution, which increases manufacturing costs and environmental impact. Additionally, the technology described in Patent Document 3 manufactures titanium materials through batch processing based on slab cutting; therefore, from this perspective, manufacturing efficiency is not very high, and manufacturing costs are significant.

[0019] The technology described in Patent Document 4 involves heating in the final process, after pickling, in the atmosphere, and in a vacuum, which results in high manufacturing costs.

[0020] The technology described in Patent Document 5 is a batch process for manufacturing titanium materials by means of ion plating, which results in low manufacturing efficiency and high manufacturing cost.

[0021] In other words, in existing technologies, it is difficult to achieve colorfastness in harsh acidic environments while taking into account manufacturing costs and environmental impact.

[0022] The present invention was made in view of the above circumstances, and its object is to provide a titanium material with excellent discoloration resistance that can be manufactured at low cost and with low environmental impact, as well as a method for manufacturing the titanium material.

[0023] Solution for solving the problem

[0024] The inventors conducted a detailed study on the relationship between the elements contained on the surface of titanium materials and their resistance to discoloration. The results showed that the resistance to discoloration is sometimes excellent when the titanium material surface contains SiO2 and Al2O3. Furthermore, the inventors also conducted a detailed study on methods for containing SiO2 and Al2O3 on the surface of titanium materials, thus completing this invention.

[0025] The main points of the present invention, based on the above insights, are as follows.

[0026] [1] One aspect of the titanium material of the present invention is a titanium material based on pure titanium or titanium alloy, wherein, when the composition of the surface constituting the titanium material is analyzed by X-ray photoelectron spectroscopy, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration is 20 atomic% or more and 50 atomic% or less in the depth direction from the outermost surface to a position of 50 nm. The color measurement value of the surface of the titanium material measured according to JIS Z 8781-4:2013 is L. * : 55~75, a * : 1.0~2.0, b * : 4.0~8.0.

[0027] [2] According to the titanium material described in [1] above, when the surface of the material is analyzed by X-ray photoelectron spectroscopy, the maximum value of C concentration can be less than 10 atomic%.

[0028] [3] According to the titanium material described in [1] or [2] above, when the surface of the material is analyzed by X-ray photoelectron spectroscopy, the maximum value of F concentration can be less than 10 atomic%, and the maximum value of N concentration can be more than 0 atomic% and less than 10 atomic%.

[0029] [4] The titanium material according to any one of [1] to [3] above, wherein when the surface of the material is analyzed by X-ray photoelectron spectroscopy, the minimum value of Ti concentration can be more than 1 atomic% and less than 40 atomic%.

[0030] [5] In addition, another embodiment of the present invention has a method for manufacturing titanium material as described in any one of [1] to [4] above, which is a shot peening process, wherein a projection material composed of SiO2 and a projection material composed of Al2O3 are projected onto the surface of a titanium billet with pure titanium or titanium alloy as the base material, wherein the particle size of the projection material composed of SiO2 and the projection material composed of Al2O3 is F20 to F100 according to JIS R 6001-1:2017, and the projection amount is 1 to 50 g / m 2 •s, with a projection speed of 10m / s or higher but less than 100m / s, and a projection time of 10s / m. 2 above.

[0031] [6] In addition, another embodiment of the present invention has a method for manufacturing titanium material as described in any one of [1] to [4] above, which includes: an adhesion step, wherein colloidal silica and alumina colloid are adhered to the surface of a titanium billet with pure titanium or titanium alloy as the substrate; and an annealing step, wherein the titanium billet after the adhesion step is annealed in the atmosphere or in a vacuum at a temperature between 100°C and 500°C for 5 minutes or more and 10 minutes or less.

[0032] The effects of the invention

[0033] As described above, according to the present invention, it is possible to provide a titanium material with excellent discoloration resistance that can be manufactured at low cost and with low environmental impact, as well as a method for manufacturing the titanium material. Attached Figure Description

[0034] Figure 1 This is a graph showing the results of XPS-based quantitative analysis of the depth orientation of examples No.2 and No.5 in the embodiments.

[0035] Figure 2 This is a graph showing the results of XPS-based quantitative analysis of the depth orientation of examples No.1 and No.6 in the embodiments. Detailed Implementation

[0036] The preferred embodiments of the present invention will now be described in detail. It should be noted that the lower and upper limits of the numerical ranges enclosed in "~" are included within these ranges. Values ​​expressed as "less than" or "greater than" are not included in the numerical range.

[0037] Titanium Materials

[0038] The titanium material of the embodiments of the present invention is a titanium material with pure titanium or titanium alloy as the base material. When analyzing the composition of the surface constituting the titanium material using X-ray photoelectron spectroscopy (XPS), the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration is 20 atomic% or more and 50 atomic% or less within the depth direction where either Si or Al concentration is 1 atomic% or more. The color measurement value of the titanium material surface, determined according to JIS Z 8781-4:2013, is L. * : 55~75, a * : 1.0~2.0, b * Version 4.0~8.0. Details are provided below.

[0039] The titanium substrate of this embodiment is composed of either pure titanium or a titanium alloy. For example, the titanium substrate is pure titanium or a titanium alloy with a Ti content of 70% by mass or more.

[0040] Pure titanium includes, for example, JIS standards 1 to 4 and the industrial pure titanium specified in ASTM standards Grades 1 to 4. Specifically, the industrial pure titanium used in this embodiment, by mass percent, contains: C: less than 0.1%, H: less than 0.015%, O: less than 0.4%, N: less than 0.07%, Fe: less than 0.5%, with the balance being Ti and impurities. It should be noted that in buildings, the industrial pure titanium specified in JIS standard 1, its equivalent in ASTM Grade 1, or equivalent materials are primarily used. There are no particular restrictions on the lower limits of the contents of C, H, O, N, and Fe; they can be 0%.

[0041] As titanium alloys, examples include α-type titanium alloys, α+β-type titanium alloys, or β-type titanium alloys.

[0042] As α-type titanium alloys, there are high corrosion-resistant alloys (JIS standards types 11-13, 17, 19-22, and ASTM standards Grades 7, 11, 13, 14, 17, 30, and 31, and further titanium alloys containing small amounts of various elements), Ti-0.05Pd, Ti-0.15Pd, Ti-0.5Cu, Ti-1.0Cu, Ti-1.0Cu-0.5Nb, Ti-1.0Cu-1.0Sn-0.3Si-0.25Nb, etc.

[0043] Examples of α+β type titanium alloys include Ti-3Al-2.5V, Ti-5Al-1Fe, Ti-5.5Al-1.5Fe-0.2Si, and Ti-6Al-4V.

[0044] Examples of β-type titanium alloys include Ti-11.5Mo-6Zr-4.5Sn, Ti-8V-3Al-6Cr-4Mo-4Zr, Ti-13V-11Cr-3Al, Ti-15V-3Al-3Cr-3Sn, Ti-20V-4Al-1Sn, and Ti-22V-4Al.

[0045] Titanium substrate, for example, is expressed as a percentage by mass:

[0046] Cu: 0% or more and 1.2% or less

[0047] Nb: 0% or more and 0.5% or less

[0048] Sn: 0% or more and 4.5% or less

[0049] Si: 0% or more and less than 0.5%

[0050] A1: Above 0% and below 7.0%

[0051] V: Above 0% and below 22.5%

[0052] Fe: 0% or more and 2.5% or less

[0053] Mo: 0% or more and 11.5% or less

[0054] Zr: 0% or higher and 6.0% or lower

[0055] Cr: 0% or more and 11.0% or less

[0056] Pd: 0% or higher and 0.25% or lower

[0057] Co: 0% or more and 0.80% or less

[0058] Ni: 0% or more and 0.80% or less

[0059] N: 0% or more and less than 0.050%

[0060] C: Above 0% and below 0.10%

[0061] H: Above 0% and below 0.015%

[0062] O: 0% or more and 0.35% or less, and

[0063] The balance consists of Ti and impurities.

[0064] Impurities are components that exist in titanium unrelated to the intended addition and are not intended to be present in the resulting titanium material. The term "impurity" encompasses impurities introduced during the industrial manufacture of titanium from raw materials or the manufacturing environment. Examples of impurities include Cl, Na, Mg, Ca, and B. The upper limits for each impurity element are: Cl: 0.1% or less, Na: 0.01% or less, Mg: 0.01% or less, Ca: 0.01% or less, and B: 0.01% or less. There are no particular restrictions on the lower limits for the content of Cl, Na, Mg, Ca, and B, which can be 0%. Furthermore, the total amount of impurities is preferably 0.1% by mass or less.

[0065] The shape of the titanium material in this embodiment is not particularly limited, and it can be a plate, a roll, or a strip, etc.

[0066] For the titanium material of this embodiment, when analyzing the composition of the surface constituting the titanium material using XPS, the maximum Si (silicon) concentration and the maximum Al (aluminum) concentration are both 10 atomic% and 40 atomic% or less along the depth direction from the outermost surface to a position of 50 nm. Furthermore, the minimum O (oxygen) concentration is 20 atomic% and 50 atomic% or less within the depth direction range from the outermost surface to a position of 50 nm, where either the Si or Al concentration is 1 atomic% or more. Hereinafter, the range from the outermost surface to 50 nm along the depth direction will be referred to as the material surface.

[0067] The inventors hypothesize that SiO2 and Al2O3 improve the discoloration resistance of titanium materials through the following effects: Compared to C, TiC, etc., present on the surface of titanium materials, SiO2 and Al2O3 are inactive relative to acidic solutions, thus inhibiting the dissolution of titanium ions by covering the surface with SiO2 and Al2O3. Furthermore, the semiconductor properties of SiO2 and Al2O3 differ from those of TiO2; the precipitation of SiO2 and Al2O3 hinders the movement of electrons from acidic solutions (bipolar film effect). Additionally, Al2O3 is an amphoteric oxide, possessing the property of reacting with acids to decompose into metal salts and water, thereby increasing the pH of adhering rainwater (acidic solution) and inhibiting the dissolution of titanium ions. It is believed that through any one of these three effects or a combination thereof, the dissolution of titanium ions can be inhibited even under severe acid rain conditions, thus improving the discoloration resistance of titanium materials.

[0068] To achieve the anti-discoloration effect provided by SiO2 and Al2O3, SiO2 and Al2O3 are required on the surface of the titanium material. When analyzing the surface of the titanium material using XPS, sufficient anti-discoloration effect can be obtained if the maximum Si concentration and the maximum Al concentration on the surface are both 10 atomic% or more. Conversely, when analyzing the surface of the titanium material using XPS, if the maximum Si concentration and the maximum Al concentration on the surface are both 40 atomic% or less, sufficient anti-discoloration effect can be obtained while maintaining the metallic color. Furthermore, if the minimum O concentration in the depth direction within a depth range where either Si or Al concentration is 1 atomic% or more is 20 atomic% or more and 50 atomic% or less, it can be said that SiO2 and Al2O3 for achieving the anti-discoloration effect have been formed. For even better anti-discoloration effect, it is preferable that the maximum Si concentration or the maximum Al concentration on the surface is 15 atomic% or more. The maximum Si concentration or the maximum Al concentration on the surface is preferably 35 atomic% or less, more preferably 30 atomic% or less.

[0069] On the other hand, if SiO2 and Al2O3 are present in large quantities on the surface of the material, the surface of the titanium material will be covered by them, which may sometimes damage the original silver color of the uncolored material. Therefore, it is preferable to expose Ti (titanium) on at least a portion of the surface. Therefore, when analyzing the surface of the titanium material using XPS, the minimum Ti concentration on the surface is preferably 1 atomic% or more. On the other hand, when analyzing the surface of the titanium material using XPS, if the titanium present on the surface exists in an oxidized state, the minimum Ti concentration on the surface is preferably 40 atomic% or less. When analyzing the surface of the titanium material using XPS, the minimum Ti concentration on the surface is more preferably 5 atomic% or more. Furthermore, when analyzing the surface of the titanium material using XPS, the minimum Ti concentration on the surface is more preferably 35 atomic% or less, more preferably 30 atomic% or less, more preferably 25 atomic% or less, more preferably 20 atomic% or less, and even more preferably 16.0 atomic% or less. In addition, SiO2 and Al2O3 can exist in an island-like manner on the surface of the material.

[0070] In the titanium material of this embodiment, it is preferable that at least 80% of its surface is covered by SiO2 and Al2O3. That is, the surface coverage of the titanium material based on SiO2 and Al2O3 is 80% or more. Specifically, when analyzed using Auger Electron Spectroscopy (AES), the region where Al and Si account for more than 1 atom% is 80% or more. This coverage can be, for example, 85% or more, or 90% or more. Alternatively, this coverage can be, for example, less than 100%, or less than 95%. It should be noted that the balance is a compound composed of titanium and oxygen, nitrogen, or carbon, as well as at least one of carbon compounds or calcium compounds.

[0071] The aforementioned coverage was calculated using the following method: An arbitrary surface of titanium was measured using AES with a 1μm spacing and an area of ​​100μm × 100μm, and the number of points where Al or Si accounts for more than 1 atom was calculated. Specifically, the accelerating voltage of the electron beam in the AES was set to 10kV, and the emission current was set to 10nA. Ar was used in the sputtering process for surface etching. + The composition was analyzed at 0.5 nm sputtering depths using SiO2. The cumulative number of measurements at each measurement point was set to 10. It should be noted that the measurement time at each measurement point was constant, but the cumulative number of measurements can be varied to improve accuracy. The calculated number of points was converted into a proportion relative to the total number of measurement points, thus representing the surface coverage of Al2O3 and SiO2.

[0072] Furthermore, when analyzing the composition of the material surface using XPS, the maximum value of the C (carbon) concentration is preferably 0 atomic% or more and 10 atomic% or less, and the maximum value of the F (fluorine) concentration is preferably 0 atomic% or more and 10 atomic% or less. High C or F concentrations can easily lead to discoloration. This is because titanium is easily leached due to C, F, or their compounds, or C and F exist in the form of compounds with titanium, and the ease of dissolution of these compounds is a major factor contributing to the growth of the oxide coating. It should be noted that C and F may exist not only individually but also in the form of compounds with titanium, hydrogen, oxygen, etc. If the maximum C concentration and the maximum F concentration on the material surface are both 10 atomic% or less, the leaching of titanium and the growth of the oxide coating are suppressed. Therefore, it is preferable that the maximum C concentration and the maximum F concentration are both 10 atomic% or less. More preferably, the C concentration is 8 atomic% or less and the F concentration is 9 atomic% or less. Even more preferably, the C and F concentrations on the material surface are low, and both the C and F concentrations are greater than 0 atomic%. In manufacturing, the practical lower limit is that both the C concentration and F concentration are 0.1 atomic%. The C concentration on the material surface can be 0.5 atomic% or more, preferably 1.0 atomic% or more, and more preferably 1.1 atomic% or more. The F concentration on the material surface can be 0.2 atomic% or more, preferably 0.5 atomic% or more.

[0073] C sometimes exists, for example, in the form of TiC. Additionally, in the manufacture of titanium materials, a pickling process is often performed, where the titanium material is cleaned with a mixture of hydrofluoric acid and nitric acid. If this pickling process is performed, titanium fluorides sometimes form at the interface between the oxide coating and the titanium substrate. In this case, when analyzing the composition of the material surface using XPS, the F in these titanium fluorides can sometimes be detected.

[0074] Furthermore, when analyzing the composition of the material surface using XPS, the maximum N (nitrogen) concentration is preferably 0 atomic% or more and 10 atomic% or less. This is because if the N concentration on the material surface is high, a dense oxide coating cannot be maintained, and sometimes the dissolution of titanium cannot be suppressed due to the cracking and peeling of the oxide coating. If the N concentration is 10 atomic% or less, the dissolution of titanium and the growth of the oxide coating in the aforementioned titanium material can be suppressed. Preferably, the N concentration is 8 atomic% or less, more preferably 6 atomic% or less. More preferably, the N concentration is 5 atomic% or less. The N concentration on the material surface is sometimes undetectable due to control during manufacturing. Therefore, the practical lower limit is 0 atomic% or more. It is also preferable to be greater than 0 atomic%, more preferably 0.1 atomic% or more.

[0075] Regarding the surface composition of the material, for titanium materials ultrasonically cleaned after being immersed in acetone, the composition distribution along the depth direction was determined using XPS while sputtering with Ar ions. The ultrasonic cleaning time could be, for example, 30 seconds or more. After qualitative analysis using XPS to identify the present elements, quantitative analysis values ​​for each element were obtained, yielding quantitative values ​​for the surface composition. The depth-direction composition analysis was performed using SiO2 conversion, with quantitative analysis of each element occurring every 1 nm of sputtering depth, from the surface of the titanium material along the depth direction up to 50 nm, determining the concentrations of Si, Al, O, Ti, C, F, and N. The C concentration at the outermost surface of the titanium material includes the influence of organic matter not originating from the titanium material itself; therefore, the value at a depth of 1 nm from the outermost surface and beyond is taken as the C concentration at the material surface.

[0076] The titanium material used in this embodiment is a silvery, uncolored material. If the surface color measurement value of the titanium material, determined according to JIS Z 8781-4:2013, is L... * : 55~75, a * : 1.0~2.0, b * If the color temperature is 4.0~8.0, the titanium material will appear silver. Color measurement was performed using a Minolta CR-200b colorimeter with light source C. Light source C refers to the auxiliary light source C for color measurement as described in CIE (International Commission on Illumination) 15.3 and JIS Z 8720:2012, which is used to measure the color of objects illuminated by sunlight. The color temperature of light source C is 6777K.

[0077] The thickness of the titanium material in this embodiment is not particularly limited, for example, it is 0.1 to 5.0 mm.

[0078] <Methods for manufacturing titanium>

[0079] Next, an example of a method for manufacturing titanium material according to an embodiment of the present invention will be described. The method for manufacturing titanium material according to this embodiment includes a surface treatment step: distributing SiO2 and Al2O3 on the surface of a titanium billet based on pure titanium or a titanium alloy. The method for manufacturing the titanium material is not particularly limited as long as SiO2 and Al2O3 can be distributed on the surface of the titanium billet. Examples of surface treatment steps include: a shot peening step using a projection material composed of SiO2 and a projection material composed of Al2O3; or an annealing step after adhering a colloid composed of silicon dioxide and silicon dioxide hydrate (colloidal silicon dioxide) and a colloid composed of alumina hydrate (alumina colloid) to the surface of the titanium material. Hereinafter, the method for manufacturing titanium material will be described using an example where a shot peening step, an adsorption step, and an annealing step are employed in the surface treatment step.

[0080] The surface treatment process is performed as the final step in the manufacturing process of titanium materials. In the titanium material manufacturing method of this embodiment, for example, the surface treatment process is performed after sequentially performing the ingot casting process, hot rolling process, cold rolling process, annealing process, and surface finishing / stretching straightening process. Alternatively, for example, if the surface finishing / stretching straightening process is omitted, the surface treatment process is performed after the annealing process. The above-mentioned processes other than the surface treatment process can be performed by known methods.

[0081] (Example of manufacturing method 1: shot peening process)

[0082] When shot peening the surface of titanium materials, SiO2 and Al2O3 are used as the projectile materials. Shot peening not only roughens the surface of the titanium material but also has a surface grinding effect. The finer the particle size of the projectile material, the higher the grinding effect, and the better it can remove impurities such as C and N remaining on the surface of the titanium material. Conversely, if the particle size of the projectile material becomes larger, the grinding effect weakens, and sometimes C and N cannot be completely removed. The particle size of each projectile material is F20 to F100 according to JIS R 6001-1:2017. If the particle size is smaller than F20, the projectile material remains unevenly, and the discoloration resistance of the entire surface of the titanium material cannot be ensured. Preferably, the particle size of any projectile material is F30 or higher, more preferably F36 or higher. On the other hand, if the particle size is larger than F100, the necessary concentration of SiO2 and Al2O3 cannot be achieved, and the discoloration resistance cannot be improved. Furthermore, in order to further improve the synergistic effect of SiO2 and Al2O3 on colorfastness, it is preferable that the difference in particle size between the two is less than 70.

[0083] If both SiO2 and Al2O3 projection materials are used, the shot peening can be performed by mixing the two materials together in one operation, or by performing shot peening using each material separately. Furthermore, the number of shot peening operations is not limited to one; multiple operations are possible. Considering productivity, the maximum number of shot peening operations is preferably 10 or less.

[0084] Projection materials composed of SiO2 contain SiO2 as the main component. For example, a projection material composed of SiO2 may contain more than 50% by mass of SiO2. For example, a projection material composed of SiO2 may be a glass bead containing more than 99% by mass of soda-lime glass. Soda-lime glass, for example, is a substance with CAS registration number 65997-17-3, containing SiO2: 70~74% by mass, Al2O3: 0~2% by mass, CaO: 6~12% by mass, MgO: 0~4% by mass, Na2O: 12~16% by mass, and the balance being impurities. The SiO2 content of a projection material composed of SiO2 may be less than 100% by mass, less than 90% by mass, or less than 80% by mass.

[0085] Projection materials composed of Al2O3 contain Al2O3 as the main component. For example, a projection material composed of Al2O3 may contain 50% by mass or more of Al2O3. For example, a projection material composed of Al2O3 may contain 95% by mass of Al2O3, 2% by mass of SiO2, 2.5% by mass of TiO2, and 0.5% by mass of Fe2O3. The Al2O3 content in the projection material may be less than 100% by mass, less than 95% by mass, or less than 90% by mass.

[0086] The projection amount of the projection material is 1~50g / m 2 ·s. If the projection amount is less than 1g / m 2 If the concentration of SiO2 and Al2O3 is less than 50 g / m, then SiO2 and Al2O3 cannot adhere sufficiently to the surface of the titanium material, and the maximum concentration of Si or Al cannot be greater than 10 atomic% on the material surface. On the other hand, if the projection amount is greater than 50 g / m 2 The residual amount varies depending on the material of the projection material, therefore sometimes it is impossible to achieve a residual SiO2 or Al2O3 concentration that is effective in improving colorfastness. The preferred projection amount of the projection material is 2 g / m³. 2 •s or more, preferably 3g / m 2 •s or more. Furthermore, the preferred projection amount of the projection material is 40 g / m³. 2 Less than 20 g / m², more preferably 20 g / m². 2 The projection amount of the projection material is preferably 2~40 g / m². 2 •s, more preferably 3~20g / m 2 ·s.

[0087] The projection speed of the projection material is 10~100 m / s. If the projection speed is below 10 m / s, SiO2 and Al2O3 cannot sufficiently adhere to the surface of the titanium material, and the maximum Si concentration or Al concentration on the material surface cannot reach 10 atomic% or more. On the other hand, if the projection speed is greater than 100 m / s, neither Si nor Al can remain on the material surface, and the maximum Si concentration or Al concentration cannot reach 10 atomic% or more and less than 40 atomic% or more and less than 40 atomic% or more. Furthermore, if the projection speed is greater than 100 m / s, the surface unevenness of the material becomes greater, and the color cannot be set to L. * : 55~75, a * : 1.0~2.0, b *The surface hardness is 4.0 to 8.0. Furthermore, as the strain increases, it begins to affect the surface hardness, thus negatively impacting the processing of the product during use and the surface design after processing. The projection speed of the projected material is preferably 20 m / s or more, more preferably 30 m / s or more. Additionally, the projection speed of the projected material is preferably 80 m / s or less, more preferably 70 m / s or less. The projection speed of the projected material is preferably 20 to 80 m / s, more preferably 30 to 70 m / s.

[0088] The projection time of the projectile material (shot peening time) is 10 s / m. 2 That's all. If the projection time is less than 10 seconds per minute. 2 If this is not done, SiO2 or Al2O3 will not adhere sufficiently to the surface of the titanium material, and the maximum Si concentration or the maximum Al concentration on the material surface cannot be greater than 10 atomic% or greater. On the other hand, there is no particular limitation on the maximum projection time, but from an operational point of view, 120 s / m is preferred. 2 The projection time of the projected material is preferably 20 s / m. 2 The above is preferred to be 30s / m. 2 above.

[0089] In addition, there are no particular restrictions, the projection pressure can be greater than 0.1 MPa and less than 1.5 MPa, and the projection angle can be greater than 40° and less than 90° (vertical).

[0090] (Manufacturing method example 2: Attachment process and annealing process)

[0091] When attaching colloidal silica and alumina colloids and then annealing them, the following substances can be used for the colloidal silica and alumina colloids. Examples of colloidal silica include OP-S suspension manufactured by Struers and MasterMet2 manufactured by Buehler. Examples of alumina colloids include OP-A suspension manufactured by Struers, AP-D manufactured by Struers, and MasterPrep manufactured by Buehler.

[0092] It is important that the colloidal concentration (concentration of the dispersed phase) of each of the colloidal silica and alumina colloids is 1% by mass or more and less than 50% by mass. If the colloidal concentration of both colloidal silica and alumina colloids is 1% by mass or more, a colorfastness effect can be obtained. If the colloidal concentration of each of the colloidal silica and alumina colloids is less than 50% by mass, the proportion of these colloids adhering to the material surface will not differ significantly, and a colorfastness effect can be obtained while maintaining the metallic color. The colloidal concentration of each of the colloidal silica and alumina colloids can be 45% by mass or less. Preferably, the colloidal concentration of each of the colloidal silica and alumina colloids is 5% by mass or more, more preferably 10% by mass or more, more preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. The colloidal silica and alumina colloids are formed by dispersing SiO2 or Al2O3 in water, alcohol, etc. Colloidal silica can be, for example, SiO2: 5-10% by mass, 1,3-butanediol: 5-20% by mass, balance: water. Alternatively, colloidal alumina can be, for example, Al2O3: 10-30% by mass, balance: water. 1,3-Butanediol is readily soluble in water and ethanol and has a boiling point of approximately 200°C; therefore, it can be removed by washing with water or ethanol, or by heating and drying. Thus, 1,3-Butanediol will not remain on the surface of the titanium material. If the solvent is a readily soluble organic solvent or an organic solvent with a low boiling point, it can be removed in the same way as 1,3-butanediol by washing with water or ethanol, or by heating and drying. Therefore, carbon from the dispersion medium will not remain on the surface of the titanium material. It should be noted that ethanol also has a boiling point of approximately 80°C; therefore, it is completely removed by drying at temperatures above 100°C, and thus carbon from ethanol will not remain on the surface of the titanium material.

[0093] Furthermore, when analyzing the adhesion amounts of colloidal silica and alumina colloids on titanium materials using XPS, the following conditions must be met on the surface of the final titanium product: a maximum Si concentration of 10 atomic% to 40 atomic% and a maximum Al concentration of 10 atomic% to 40 atomic%; and a minimum O concentration of 20 atomic% to 50 atomic% within a depth direction where either the Si or Al concentration is 1 atomic% or higher. For example, this could be 0.01 to 10 g / m³. 2 That's all.

[0094] There are no particular restrictions on the application methods of colloidal silica and alumina colloids. Titanium materials can be impregnated in various solutions, sprayed with the solutions, or coated with the solutions. There are also no particular restrictions on the order of application of the colloidal silica and alumina colloids. Alternatively, a solution containing a mixture of colloidal silica and alumina colloids can also be used.

[0095] Preferably, the surface of the titanium material impregnated with colloidal silica and alumina colloid is cleaned with alcohol or hydrofluoric acid. This cleaning process is optional. Furthermore, by using alcohol for cleaning, organic components other than the colloid can be selectively washed away even when colloidal oxide particles are adsorbed on the surface. It should be noted that the alcohol used to clean the surface of the titanium material can be, for example, ethanol, 1-propanol, 2-propanol, or butanol. The alcohol used is dried by heating after cleaning, so it will not become carbon residue on the surface of the titanium material. By cleaning with alcohol, the maximum carbon concentration when analyzing the material surface using X-ray photoelectron spectroscopy can be 10 atomic% or less. In addition, by cleaning with alcohol, the maximum values ​​of the F concentration and N concentration when analyzing the material surface using X-ray photoelectron spectroscopy can be 10 atomic% or less.

[0096] The annealing conditions are as follows: Heating at a holding temperature between 100°C and 500°C in atmosphere or vacuum for 5 to 10 minutes. During prolonged heating, although the adsorption of colloidal oxide particles becomes stronger, the oxide film grows, and the silvery-white metallic color is lost. Therefore, heating for 10 minutes or less is recommended. The heating atmosphere is either atmosphere or vacuum. Furthermore, when the holding temperature is below 100°C, the adsorption of colloidal oxide particles becomes insufficient, and the improvement in colorfastness cannot be fully achieved. On the other hand, if the holding temperature exceeds 500°C, the oxide film grows rapidly, and the silvery-white metallic color is lost. The holding temperature can be 200°C or higher. Alternatively, the holding temperature can be 400°C or lower. The holding time can be 6 minutes or higher. Alternatively, the holding time can be 9 minutes or less.

[0097] The aforementioned processes, excluding the surface treatment process, can be performed using known methods. For example, in the ingot casting process, using sponge titanium, master alloys for adding alloying elements, etc., as raw materials, ingots of pure titanium or titanium alloys with the above-mentioned composition are produced by various melting methods such as vacuum arc melting, electron beam melting, or plasma melting. Then, the obtained ingots are roughed and hot-forged as needed to produce ingots.

[0098] In the hot rolling process, for example, the ingot is heated to 600-850°C and rolled at a temperature below the phase transformation temperature. The reduction rate is determined based on the characteristics of the final product. The heating temperature is preferably 700-850°C. From the viewpoint of deformation resistance, the lower limit of the heating temperature is preferably above 700°C. Since the thickness of the oxide coating on the hot-rolled titanium billet can be reduced, descaling after hot rolling can be performed under stable conditions; therefore, the upper limit of the heating temperature is preferably below 850°C.

[0099] In the cold rolling process, the hot-rolled titanium billet can be rolled to achieve the desired thickness and properties. In cases involving multiple cold rolling passes, the titanium billet can be annealed between these passes.

[0100] In the annealing process following the cold rolling process, for example, the titanium billet can be annealed in a non-reactive atmosphere after removing impurities such as lubricating oil adhering to it during the cold rolling process using an alkaline cleaning line. Alternatively, for example, the titanium billet after the cold rolling process can be subjected to salt bath descaling and pickling sequentially after the aforementioned annealing process.

[0101] In addition, an annealing process can be performed on the titanium billet before the surface treatment process. The annealing process can be carried out, for example, in an inactive atmosphere, with the annealing temperature set to 350~700℃ and the annealing time set to 1~40 hours. The annealing temperature can be above 400℃. Furthermore, the annealing time can be above 10 hours. This annealing process can remove carbon (C) from the surface of the titanium billet if present. It should be noted that if the annealing process is performed in an atmospheric annealing atmosphere, the oxide coating will become thicker, lose its metallic color, and fail to meet the color measurement values.

[0102] Surface rolling / stretching straightening processes can be appropriately implemented, for example, for the purpose of correcting the shape of titanium billets after annealing.

[0103] According to the above manufacturing method, titanium materials can be manufactured as follows: when analyzed using XPS, the maximum Si concentration on the material surface is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, the minimum O concentration in the depth direction range where either Si or Al concentration is 1 atomic% or more is 20 atomic% or more and 50 atomic% or less, and the surface color measurement value of the titanium material, determined according to JIS Z 8781-4:2013, is L. * : 55~75, a * : 1.0~2.0, b * The temperature range is 4.0 to 8.0. Furthermore, the above-described manufacturing method allows for continuous processing of long strips of titanium, thus reducing manufacturing costs compared to batch processing. Additionally, titanium with excellent discoloration resistance can be obtained even without an acid pickling process, thereby reducing the use of environmentally hazardous chemicals such as nitric acid and hydrofluoric acid, and thus minimizing environmental impact.

[0104] Example

[0105] The embodiments of the present invention will be described in detail below. It should be noted that the embodiments shown below are merely examples of the present invention, and the present invention is not limited to the examples described below.

[0106] (Example 1)

[0107] Manufacturing titanium cold-rolled sheets (titanium substrates) of the varieties shown in Tables 1-3, cutting multiple samples with a length (length in the rolling direction) of 70 mm × a width (length in the direction perpendicular to the rolling direction in the rolled surface) of 70 mm × a thickness of 0.3 mm from the titanium cold-rolled sheets, performing an annealing process under the conditions shown in Tables 1-3, followed by a shot peening process, or an adhesion process and an annealing process for surface treatment. In Tables 1-3, CP1 indicates JIS Type 1 industrial pure titanium, CP2 indicates JIS Type 2 industrial pure titanium, and CP3 indicates JIS Type 3 industrial pure titanium. Ti-1Cu, Ti-3Al-2.5V, Ti-5Al-1Fe, Ti-0.05Pd, Ti-0.15Pd, and Ti-20V-4Al-1Sn are symbols following the hyphen indicating the content (mass %) and type (element symbol) of the element, respectively, representing the nominal composition of the titanium billet. Additionally, "-" in Tables 1-3 indicates that it was not implemented. It should be noted that the underlined lines in Tables 1-3 indicate items outside the scope of this invention.

[0108] [Table 1]

[0109]

[0110] [Table 2]

[0111]

[0112] [Table 3]

[0113]

[0114] After surface treatment, the test pieces were immersed in acetone for ultrasonic cleaning for at least 5 minutes. Then, the surface of the test pieces was wiped with an ethanol-soaked cloth and allowed to dry. Qualitative, quantitative, and depth-direction analyses were performed using XPS on a depth range from the outermost surface of the annealed test piece to a position 50 nm deep. The XPS-based analytical conditions are as follows.

[0115] Device: ULVAC-PHI Versa Probe III

[0116] X-ray source: mono-AlKα (hν: 1486.6 eV)

[0117] Beam diameter: 200 μm φ (≈ analysis area)

[0118] Splashing conditions: Ar + Sputtering rate: 2.0 nm / min (SiO2 equivalent)

[0119] The so-called SiO2 conversion value is the sputtering rate calculated under the same measurement conditions using a SiO2 film whose thickness has been pre-measured with an ellipsometry.

[0120] The O concentrations in Tables 4-6 represent the minimum O concentrations along the depth direction from the outermost surface of the test piece to a depth of 50 nm, provided that either the Si or Al concentration is 1 atom% or higher. Regarding carbon, whose concentration decreases roughly monotonically with respect to depth, there is an effect of organic matter adhesion at the outermost surface. Therefore, the maximum C concentration at a depth of 1 nm from the outermost surface is taken as the maximum C concentration at the material surface. Furthermore, "-" in Tables 4-6 indicates below the detection limit.

[0121] In addition, test pieces measuring 50 mm in length, 25 mm in width, and 0.3 mm in thickness were cut from the sample after surface treatment, and a discoloration-promoting test was conducted. For the discoloration-promoting test, a tropical environment with acid rain was simulated, and the titanium material was immersed in a sulfuric acid aqueous solution with pH 3 at 80°C for 4 days. The color L of the titanium surface before and after the discoloration-promoting test was determined according to JIS Z 8781-4:2013. * a * b * In the color measurement, a Minolta (Co., Ltd.) CR-200b colorimeter was used, and light source C was employed. For a single side of the test piece (length × width), measurements were taken at 5 points (1 point at the center and 4 points at the corners) and 10 points (2 points on the surface and 2 on the back) before and after the color change acceleration test. For the titanium surface before the color change acceleration test, all 10 color measurement points were within the range of L. * : 55~75, a * : 1.0~2.0, b * When the color value is within the range of 4.0 to 8.0, the evaluation result of the color measurement is set to GOOD (acceptable); when it is outside the range, it is set to BAD (unacceptable). Additionally, for examples not evaluated, a "-" is recorded in the evaluation result section of the table. It should be noted that Tables 4-6 record the maximum and minimum values ​​for each measurement point.

[0122] In addition, L was measured before and after the color change promotion test. * a * b * Calculate the color difference ΔE before and after the color change promotion test. * ab.

[0123] Color difference is used to enhance the brightness L before and after the test by measuring the color change at each measurement point. * and chromaticity a * b * Based on the difference ΔL between the color change and the test results at each measurement point before and after the test,* , Δa * Δb * The following calculation is performed:

[0124] .

[0125] Color difference ΔE * ab is calculated for each measurement point, and the results are evaluated across all 10 points. Tables 4-6 record the maximum values ​​for each measurement point.

[0126] Due to the color difference ΔE that is visually recognized as a color change * The threshold for ab is 8.0, therefore the color difference ΔE before and after the color change promotion test will be... * If the maximum value of ab is less than 8.0, the colorfastness is judged to be A (excellent). The color difference ΔE before and after the color change promotion test is then considered. * A maximum ab value of 8.0 or higher but less than 10.0 is considered a B (good) rating for colorfastness. The color difference ΔE before and after the color-changing acceleration test is then used. * A maximum ab value of 10.0 or higher is considered a C (poor) rating for colorfastness. Additionally, for examples not evaluated, a "-" is recorded in the evaluation results section of the table. It should be noted that the underlined conditions in Tables 4-6 represent conditions outside the scope of this invention.

[0127] [Table 4]

[0128]

[0129] [Table 5]

[0130]

[0131] [Table 6]

[0132]

[0133] Example No. 1 is an example where no surface treatment process was performed. In this example, Si and Al were not detected on the material surface, the minimum O concentration was 1.0 atomic%, and the colorfastness was poor.

[0134] Example No. 2 involves using SiO2 with a particle size of F36 as the projectile material in the first shot peening treatment and Al2O3 with a particle size of F36 as the projectile material in the second shot peening treatment. The amount of projectile material used in each shot peening treatment is 5 g / m². 2 The projection speed is 40 m / s, and the projection time is 60 s / m. 2In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, where either the Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0135] Example No. 3 involves using SiO2 with a particle size of F36 as the projectile material in the first shot peening treatment and Al2O3 with a particle size of F100 as the projectile material in the second shot peening treatment. The amount of projectile material used in each shot peening treatment is 5 g / m². 2 The projection speed is 40 m / s, and the projection time is 60 s / m. 2 In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, where either the Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0136] Example No. 4 involves using SiO2 with a particle size of F100 as the projectile material in the first shot peening treatment and Al2O3 with a particle size of F36 as the projectile material in the second shot peening treatment. The amount of projectile material used in each shot peening treatment is 5 g / m². 2 The projection speed is 40 m / s, and the projection time is 60 s / m. 2 In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, where either the Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0137] Example No. 5 is an example in which Al2O3 with a particle size of F36 is used as the projectile material in the first shot peening treatment, and SiO2 with a particle size of F36 is used as the projectile material in the second shot peening treatment. The amount of projectile material in each shot peening treatment is 5 g / m². 2 The projection speed is 40 m / s, and the projection time is 60 s / m. 2In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, where either the Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0138] Example No. 6 is an example of colloidal impregnation treatment. In example No. 6, the sample was impregnated for 2 minutes in a colloidal solution with SiO2 concentration and Al2O3 concentration of 20% by mass and a temperature of 50°C. The surface of the sample, after being removed from the colloidal solution, was cleaned with ethanol and then annealed at 200°C for 5 minutes under atmospheric atmosphere. In this example, on the material surface, the maximum Si concentration was 10 atomic% to 40 atomic% and the maximum Al concentration was 10 atomic% to 40 atomic%; the minimum O concentration in the depth direction was 20 atomic% to 50 atomic% and either Si or Al concentration was 1 atomic% or more; the color measurement evaluation result was qualified; and the colorfastness evaluation result was excellent.

[0139] Example No. 7 also involves colloidal impregnation treatment. Example No. 7 is an example where the SiO2 concentration and Al2O3 concentration are each set to 10% by mass, and other conditions are the same as in Example No. 6. In this example, on the material surface, the maximum Si concentration is 10 atomic% to 40 atomic%, the maximum Al concentration is 10 atomic% to 40 atomic%, and the minimum O concentration in the depth direction is 20 atomic% to 50 atomic% when either Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0140] Example No. 8 is also an example of colloidal impregnation treatment. Example No. 8 is an example where the SiO2 concentration and Al2O3 concentration are each set to 40% by mass, and other conditions are the same as in Example No. 6. In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, either the Si concentration or the Al concentration is 1 atomic% or more, the color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0141] Example No. 9 uses SiO2 with a particle size of F20 as the projectile material in the first shot peening treatment and Al2O3 with a particle size of F20 as the projectile material in the second shot peening treatment. The amount of projectile material used in each shot peening treatment is 5 g / m². 2 The projection speed is 40 m / s, and the projection time is 60 s / m. 2 In this example, on the material surface, the maximum Si concentration is 10 atomic% to 40 atomic% and the maximum Al concentration is 10 atomic% to 40 atomic%; the minimum O concentration within the depth direction where either Si or Al concentration is 1 atomic% or more is 20 atomic% to 50 atomic%; and the discoloration resistance is good. This is believed to be because the diameter of the projected material is relatively large, resulting in uneven residue and the formation of localized areas where discoloration resistance cannot be guaranteed.

[0142] Example No. 10 is an example in which SiO2 with a particle size of F30 is used as the projectile material in the first shot peening treatment, and Al2O3 with a particle size of F30 is used as the projectile material in the second shot peening treatment. The amount of projectile material projected in each shot peening treatment is 5 g / m². 2 The projection speed is 40 m / s, and the projection time is 60 s / m. 2 In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, where either the Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0143] Example No. 11 is an example that uses Al2O3 and SiO2 projectiles with a particle size of F36 in the first shot peening process. The ratio of Al2O3 to SiO2 projectiles is set to 50% by mass and 50% by mass, respectively. The projection amount of the projectiles is 5 g / m³. 2 The projection speed is 40 m / s, and the projection time is 60 s / m. 2 In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, where either the Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0144] Example No. 12 is an example in which Al2O3 with a particle size of F36 was used as the projectile material in the first shot peening treatment, and SiO2 with a particle size of F36 was used as the projectile material in the second shot peening treatment. The amount of projectile material projected in each shot peening treatment was 50 g / m². 2 The projection speed is 10 m / s, and the projection time is 15 s / m. 2 In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, where either the Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0145] Example No. 13 is an example in which Al2O3 with a particle size of F36 was used as the projectile material in the first shot peening treatment, and SiO2 with a particle size of F36 was used as the projectile material in the second shot peening treatment. The amount of projectile material projected in each shot peening treatment was 1 g / m³. 2 The projection speed is 100 m / s, and the projection time is 60 s / m. 2 In this example, on the material surface, the maximum Si concentration is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, and the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, where either the Si or Al concentration is 1 atomic% or more. The color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0146] Example No. 14 is an example of colloidal impregnation treatment. In example No. 14, the sample was immersed in a colloidal solution with SiO2 concentration and Al2O3 concentration of 20% by mass and a temperature of 50°C for 2 minutes. The surface of the sample, after being removed from the colloidal solution, was cleaned with ethanol and then annealed at 500°C for 5 minutes under atmospheric atmosphere. In this example, on the material surface, the maximum Si concentration was 10 atomic% to 40 atomic% and the maximum Al concentration was 10 atomic% to 40 atomic% and the minimum O concentration in the depth direction was 20 atomic% to 50 atomic% or more, and the color measurement evaluation result was qualified, and the colorfastness evaluation result was excellent.

[0147] Example No. 15 is an example of colloidal impregnation treatment. In example No. 15, the sample was impregnated for 2 minutes in a colloidal solution with SiO2 concentration and Al2O3 concentration of 20% by mass and a temperature of 50°C. The surface of the sample, after being removed from the colloidal solution, was cleaned with ethanol and then annealed in a vacuum at 200°C for 5 minutes. In this example, on the material surface, the maximum Si concentration was 10 atomic% to 40 atomic% and the maximum Al concentration was 10 atomic% to 40 atomic%; the minimum O concentration in the depth direction was 20 atomic% to 50 atomic% and either Si or Al concentration was 1 atomic% or more; the color measurement evaluation result was qualified; and the colorfastness evaluation result was excellent.

[0148] Examples No. 16-23 are examples where the titanium blank is changed from example No. 2, and other conditions are the same as in example No. 2. In these examples, when measured using XPS, the maximum Si concentration on the material surface is 10 atomic% or more and 40 atomic% or less, the maximum Al concentration is 10 atomic% or more and 40 atomic% or less, the minimum O concentration in the depth direction is 20 atomic% or more and 50 atomic% or less, either Si or Al concentration is 1 atomic% or more, the color measurement evaluation result is qualified, and the colorfastness evaluation result is excellent.

[0149] Example No. 24 is an example of shot peening performed using SiO2 projectile material with a particle size of F36. In this example, the minimum O concentration in the depth direction within which Al, Si, or either Al concentration or more than 1 atomic% was not detected on the material surface was less than 20%, and the evaluation result for discoloration resistance was poor.

[0150] Example No. 25 is an example of shot peening using Al2O3 projectile material with a particle size of F36. In this example, Si was not detected on the material surface, and the minimum O concentration in the depth direction was less than 20% if either Si or Al concentration was 1 atom% or higher. The evaluation result for discoloration resistance was poor.

[0151] Example No. 26 is an example derived from Example No. 2, except that the particle size of the projected material in each shot peening process is changed to F120, while other conditions are the same as in Example No. 2. In this example, on the material surface, the maximum Si concentration is less than 10 atomic%, the maximum Al concentration is less than 10 atomic%, and the minimum O concentration in the depth direction is less than 20 atomic% if either Si or Al concentration is 1 atomic% or more. The evaluation result for discoloration resistance is poor.

[0152] Example No. 27 is an example derived from Example No. 2, except that the particle size of the projected material in each shot peening process is changed to F14, while other conditions are the same as in Example No. 2. In this example, on the material surface, the maximum Si concentration is less than 10 atomic%, the maximum Al concentration is less than 10 atomic%, and the minimum O concentration in the depth direction is less than 20 atomic% if either Si or Al concentration is 1 atomic% or more. The evaluation result for discoloration resistance is poor.

[0153] Example No. 28 is an example derived from Example No. 2, with the projection speed changed from 40 m / s to 5 m / s, while all other conditions remain the same as in Example No. 2. In this example, on the material surface, the maximum Si concentration is less than 10 atomic%, the maximum Al concentration is less than 10 atomic%, and the minimum O concentration in the depth direction is less than 20 atomic% if either Si or Al concentration is 1 atomic% or higher. The evaluation result for colorfastness is poor.

[0154] Example No. 29 is an example derived from Example No. 2, with the projection speed changed from 40 m / s to 150 m / s, while other conditions remain the same as in Example No. 2. In this example, on the material surface, the maximum Si concentration is less than 10 atomic%, the maximum Al concentration is less than 10 atomic%, and the minimum O concentration in the depth direction is less than 20 atomic% if either Si or Al concentration is 1 atomic% or higher. The color measurement and colorfastness evaluation results are unsatisfactory.

[0155] Example No. 30 is an example of reducing the projection time from 60 s / m in example No. 2. 2 Change to 5s / m 2 This example is conducted under the same conditions as in Example No. 2. In this example, on the material surface, the maximum Si concentration is less than 10 atomic%, the maximum Al concentration is less than 10 atomic%, and the minimum O concentration in the depth direction is less than 20 atomic% if either the Si or Al concentration is 1 atomic% or more. The evaluation result for discoloration resistance is poor.

[0156] Example No. 31 is an example in which SiO2 with a particle size of F36 is used as the projectile material in the first shot peening process, and Al2O3 with a particle size of F36 is used as the projectile material in the second shot peening process. The amount of projectile material in each shot peening process is 0.5 g / m². 2 The projection speed is 40 m / s, and the projection time is 60 s / m. 2In this example, on the material surface, the maximum Si concentration is less than 10 atomic%, the maximum Al concentration is less than 10 atomic%, and the minimum O concentration in the depth direction is less than 20 atomic% if either Si or Al concentration is 1 atomic% or more. The evaluation result for colorfastness is poor.

[0157] Example No. 32 is an example in which SiO2 with a particle size of F36 is used as the projectile material in the first shot peening process, and Al2O3 with a particle size of F36 is used as the projectile material in the second shot peening process. The projection amount of the projectile material in each shot peening process is 60 g / m². 2 The projection speed is 10 m / s, and the projection time is 60 s / m. 2 In this example, the maximum Si concentration on the material surface is less than 10 atomic%, resulting in a poor evaluation of discoloration resistance.

[0158] Example No. 33 involves changing the annealing atmosphere in the annealing process to atmospheric air and the atmosphere pressure to 1.0 × 10⁻⁶. 5 This example was conducted under the same conditions as Example No. 2, except that the annealing time was changed to 1 hour. In this example, because the annealing was carried out in an atmospheric atmosphere, the oxide coating became thicker, and the evaluation result of the color measurement value was unacceptable.

[0159] Example No. 34 involves changing the annealing temperature in the annealing process to 350°C, while other conditions are the same as in Example No. 2. In this example, the annealing temperature is low, and carbon remains on the surface of the titanium billet. The maximum carbon concentration on the material surface is greater than 10 atomic%, and the evaluation result for discoloration resistance is good.

[0160] Example No. 35 involves changing the annealing time in the annealing process to 1 hour, while other conditions are the same as in Example No. 2. In this example, the annealing time is short, and carbon remains on the surface of the titanium billet. The maximum carbon concentration on the material surface is greater than 10 atomic%, and the evaluation result for discoloration resistance is good.

[0161] Example No. 36 is an example of colloidal impregnation treatment. In example No. 36, the sample was impregnated for 2 minutes in a colloidal solution with SiO2 and Al2O3 concentrations of 20% by mass and a temperature of 50°C. The surface of the sample, removed from the colloidal solution, was cleaned with ethanol and then annealed at 550°C for 5 minutes under atmospheric atmosphere. In this example, L * For 51, a * The score was 2.5, indicating that the color measurement result was unsatisfactory.

[0162] Example No. 37 is an example of colloidal impregnation treatment. In example No. 37, the sample was immersed in a colloidal solution with SiO2 concentration and Al2O3 concentration of 20% by mass and a temperature of 50°C for 2 minutes. The surface of the sample, after being removed from the colloidal solution, was cleaned with ethanol and then annealed at 50°C for 5 minutes under atmospheric atmosphere. In this example, the maximum Si concentration on the material surface was less than 10 atomic%, the maximum Al concentration was less than 10 atomic%, and the minimum O concentration in the depth direction was less than 20 atomic% if either Si or Al concentration was 1 atomic% or more; therefore, the evaluation result for colorfastness was poor.

[0163] Example No. 38 illustrates a colloidal impregnation process. In example No. 38, the sample was impregnated for 2 minutes in a colloidal solution with SiO2 and Al2O3 concentrations of 20% by mass and a temperature of 50°C. The surface of the sample, removed from the colloidal solution, was cleaned with ethanol and then annealed at 200°C for 12 minutes under atmospheric conditions. In this example, the long annealing time under atmospheric conditions during the colloidal impregnation process resulted in the growth of an oxide coating, causing the loss of the silvery-white metallic color, and the color measurement result was deemed unacceptable.

[0164] Example No. 39 is an example of colloidal impregnation treatment. In example No. 39, the sample was impregnated for 2 minutes in a colloidal solution with a SiO2 concentration of 50% by mass, an Al2O3 concentration of 0% by mass, and a temperature of 50°C. The surface of the sample, removed from the colloidal solution, was cleaned with ethanol and then annealed at 200°C for 5 minutes under atmospheric conditions. In this example, the colloidal solution did not contain alumina colloid but contained a high concentration of colloidal silica, thus causing the colloidal silica to aggregate. The maximum Si concentration was greater than 40 atomic%, and the maximum Al concentration was less than 10 atomic%. The color measurement result was unacceptable, and the colorfastness evaluation result was poor.

[0165] Example No. 40 is an example of colloidal impregnation treatment. In example No. 39, the sample was impregnated for 2 minutes in a colloidal solution with a SiO2 concentration of 0% by mass, an Al2O3 concentration of 50% by mass, and a temperature of 50°C. The surface of the sample removed from the colloidal solution was cleaned with ethanol and then annealed at 200°C for 5 minutes under atmospheric atmosphere. In this example, the colloidal solution did not contain alumina colloid but contained colloidal silica at a high concentration, thus causing alumina colloid aggregation. The maximum Al concentration was greater than 40 atomic%, and the maximum Si concentration was less than 10 atomic%. The color measurement result was unqualified, and the colorfastness evaluation result was poor.

[0166] Example No. 41 is an example of colloidal impregnation treatment. In example No. 41, the sample was impregnated for 2 minutes in a colloidal solution with SiO2 concentration and Al2O3 concentration of 20% by mass and a temperature of 50°C. The surface of the sample, after being removed from the colloidal solution, was cleaned with 1% by mass hydrofluoric acid, and then annealed at 200°C for 5 minutes under atmospheric conditions. In this example, the color measurement value was rated as acceptable, and the colorfastness was rated as good.

[0167] Example No. 42 involves colloidal impregnation. In example No. 42, the sample was immersed for 2 minutes in a colloidal solution with SiO2 and Al2O3 concentrations of 20% by mass and a temperature of 50°C. After being removed from the colloidal solution, the sample was annealed at 200°C for 5 minutes under atmospheric conditions. In this example, the color measurement result was satisfactory, and the colorfastness was good.

[0168] Example No. 43 is performed in an annealing atmosphere of atmospheric pressure of 1.0 × 10⁻⁶. 5 This example illustrates the annealing of cut samples under conditions of Pa and an annealing time of 40 hours. In this case, significant oxidation occurred, making it impossible to maintain the plate shape. Therefore, no surface treatment process was performed, and no color measurement or evaluation of colorfastness was conducted.

[0169] In addition, Figure 1 The results of XPS-based quantitative analysis of depth orientation for examples No.2 and No.5 are shown below. Figure 2 The results of XPS-based quantitative analysis of depth orientation are shown for examples No.1 and No.6. Figure 1 As shown, in examples No. 2, 5, and 6, Si and Al are present on the material surface. Furthermore, when confirming their binding energies, it is found that Si has a peak at 103.3 eV and Al has a peak at 74.8 eV, both exhibiting binding energies originating from oxides. Additionally, in the presence of these elements, oxygen concentration is present in a certain amount, thus it can be inferred that Si exists in the state of SiO2 and Al exists in the state of Al2O3. Therefore, in this example of the invention, it is indicated that SiO2 and Al2O3 are mixed and present on the material surface.

[0170] Furthermore, in examples No.2, 5, and 6, in addition to Ti and O, F, N, and C were also detected on the material surface. The maximum F concentration and the maximum N concentration on the material surface were both below 10 atomic%, and the maximum C concentration within the range after removing the influence of attached organic matter was below 10 atomic%.

[0171] (Example 2)

[0172] For examples No. 14 and No. 15 in Example 1, the thickness of the oxide coating was measured. Specifically, using XPS, the thickness of the oxide coating was measured from the outermost surface to a depth where the O concentration was half of its maximum value. Table 7 shows the measured thickness and color values ​​of the oxide coating in each example.

[0173] [Table 7]

[0174]

[0175] For example, Non-Patent Document 1 (Hidetoshi Yamaguchi, Hiroshi Sato, Surface Technology, 40(1), 64-65(1992)) shows a graph of color measurement values ​​measured with the voltage used to form the oxide coating as a reference value, and Non-Patent Document 2 (Hiroshi Sato, Surface Technology, 43(11), 1014-1019(1992)) shows a graph of the thickness of the oxide coating measured with the voltage used to form the oxide coating as a reference value. These graphs show that the thickness of the oxide coating affects the color measurement values.

[0176] The relationship between color measurement values ​​and oxide coating thickness for titanium materials manufactured using colloidal silica and alumina colloids is shown in Table 7. For the oxide coatings listed in Table 7, the cross-sections of the oxide coatings processed using focused ion beam microscopy (FE-TEM) were observed. The thickness of the oxide coating was estimated from bright-field images obtained from 10 different locations on the same substrate, and the average value was taken as the oxide coating thickness for each substrate. The oxide coating thickness was very thin, less than 50 nm, and therefore was considered to meet the color measurement values ​​required by this application. The thickness of the oxide coating for titanium materials manufactured using colloidal silica and alumina colloids was confirmed to be 5–50 nm.

[0177] Furthermore, in titanium materials manufactured through shot peening, the oxide coating is embedded into the titanium material through shot peening, making accurate detection of the oxide coating difficult. However, in Example 1 described above, the color value showed a certain range of values, suggesting that this titanium material also possesses an oxide coating of similar thickness to that of titanium materials manufactured using colloidal silica and alumina colloids. Using XPS, defining the thickness of the oxide coating as extending from the outermost surface to a depth of half the maximum O concentration, the oxide coating thickness of the titanium material manufactured through shot peening is approximately 500 nm to 1 μm, while the oxide coating thickness of the titanium material manufactured using colloidal silica and alumina colloids is approximately 10 nm to 1 μm.

[0178] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to these examples. It is obvious to anyone skilled in the art that various modifications or alterations will arise within the scope of the technical concept described in the claims, and these modifications or alterations are naturally understood to fall within the protection scope of the present invention.

Claims

1. A titanium material, which is a titanium material using pure titanium or a titanium alloy as a base material, wherein, When analyzing the composition of the surface of the titanium material using X-ray photoelectron spectroscopy, the material surface from the outermost surface along the depth direction to a position of 50 nm... The maximum Si concentration is between 10 atomic% and 40 atomic%. The maximum Al concentration is between 10 atomic% and 40 atomic%. The minimum O concentration within the depth direction where either the Si concentration or the Al concentration is 1 atom% or more is 20 atom% or more and 50 atom% or less. The color measurement value of the surface of the titanium material, determined according to JIS Z 8781-4:2013, is... L*：55~75、 a*：1.0~2.0、 b*：4.0~8.0。 2. The titanium material of claim 1, wherein, When the surface of the material is analyzed using X-ray photoelectron spectroscopy, the maximum C concentration is below 10 atomic%.

3. The titanium material according to claim 1 or 2, wherein When analyzing the surface of the material using X-ray photoelectron spectroscopy... The maximum value of F concentration is less than 10 atomic percent, and the maximum value of N concentration is more than 0 atomic percent and less than 10 atomic percent.

4. The titanium article of claim 1, wherein, When analyzing the surface of the material using X-ray photoelectron spectroscopy, the minimum Ti concentration is above 1 atom% and below 40 atom%.

5. The method of manufacturing titanium material according to claim 1, comprising: The shot peening process involves projecting a projectile material composed of SiO2 and a projectile material composed of Al2O3 onto the surface of a titanium billet based on pure titanium or titanium alloy. The particle sizes of the SiO2-based projection material and the Al2O3-based projection material are F20~F100 according to JIS R6001-1:2017. The projection amount is 1 to 50 g / m 2 • s, The projection speed is above 10m / s and below 100m / s. The projection time is 10 s / m 2 The above.

6. A method for manufacturing titanium material, comprising the method for manufacturing titanium material as described in claim 1, and comprising: The adhesion process allows colloidal silica and alumina colloids to adhere to the surface of a titanium blank with pure titanium or titanium alloy as the substrate. as well as The annealing process involves annealing the titanium billet after the attachment process at a temperature between 100°C and 500°C in the atmosphere or in a vacuum for at least 5 minutes and less than 10 minutes.

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