Titanium material, processed product, and product

Abstract

A titanium material wherein: the average value of the C content in regions from the surface of the titanium material to a depth position of 10 to 50 nm is 5.0 mass% or more; and when depth analysis using time-of-flight secondary ion mass spectrometry is performed in a region from the surface to a depth position of 50 nm, the maximum value among values obtained by standardizing the detection intensity of negative ions having an m / z value of 59 by the detection intensity of negative ions having an m / z value of 59 at a depth position of 2,000 nm from the surface is 30.0 or less.

Description

Titanium materials, processed products, and products

[0001] The present invention relates to titanium materials, workpieces, and products.

[0002] Press forming is a common method for forming metal materials by pressing a material against a die and applying pressure. Adhesion between the material and the die can be a problem during press forming. Adhesion can lead to poor lubrication and reduced formability. It can also cause scratches on the surface of the material and shorten the life of the die. Therefore, there is a need for technology to suppress adhesion between the material and the die during press forming.

[0003] Commercially pure titanium or titanium alloys (hereinafter simply referred to as "titanium material") are prone to adhesion, i.e., have poor lubricity. For this reason, when titanium material is press-formed, a chemical called a film-type solid lubricant is typically applied to the surface. This improves lubricity and suppresses adhesion. However, using a film-type solid lubricant requires additional steps to dry the surface after application and to clean the surface after press-forming. This increases manufacturing costs. Therefore, liquid lubricants such as mineral oil are used instead of film-type solid lubricants. The technology described in Patent Document 1 attempts to improve the lubricating effect of liquid lubricants by forming irregularities on the surface of a titanium plate.

[0004] JP 2010-255085 A

[0005] However, because the liquid lubricant contains paraffinic hydrocarbons and the titanium surface has low lipophilicity, the liquid lubricant is repelled by the titanium surface, resulting in partial direct contact between the titanium and the die, making it difficult to sufficiently prevent the titanium from adhering to the die.

[0006] The technology disclosed in Patent Document 1 aims to improve oil retention by forming irregularities on the surface of a titanium plate and using the concave portions as oil reservoirs. However, the lipophilicity of the surface of the convex portions is not considered, and sufficient lubricity cannot be obtained.

[0007] In light of the above, an object of the present invention is to provide a titanium material, processed product, and finished product having excellent lipophilicity and lubricity.

[0008] The present invention has been made to solve the above-mentioned problems, and the gist of the present invention is the following titanium material, processed product, and product.

[0009] (1) A titanium material in which the average C content in a region from the surface to a depth of 10 to 50 nm is 5.0 mass% or more, and when depth analysis is performed using time-of-flight secondary ion mass spectrometry in the region from the surface to a depth of 50 nm, the maximum value of the detection intensity of negative ions with m / z of 59 standardized by the detection intensity of negative ions with m / z of 59 at a depth of 2000 nm from the surface is 30.0 or less.

[0010] (2) The titanium material according to (1) above, wherein the minimum value of the N content in the region from the surface to a depth of 50 nm is 5.0 mass % or more.

[0011] (3) The titanium material is a titanium plate, and an electron probe microanalyzer is used to perform 500 line analyses at 0.4 μm intervals in a predetermined direction on the surface of the titanium plate, and 500 line analyses at 0.4 μm intervals in a direction perpendicular to the predetermined direction on the surface, and the measured concentrations (mass%) of C, N, and O are [C], [N], and [O], respectively. Among all the measurement points, the average value of 36[C] + 3.6[N] is 90 or more, the percentage of the number of measurement points where the value of 36[C] + 3.6[N] is 20 or less is 35% or less, and the percentage of the number of measurement points where [O] / [C] is 0.2 or less is 35% or less, and for each line analysis, a distribution line of [O] is created, and when the number of intersections between the distribution line and a line showing a concentration 0.2 times the average value of [C] is measured, the average number of intersections in the 500 line analyses is 20 to 150. The titanium material according to (1) or (2) above.

[0012] (4) The titanium material according to (3) above, wherein the ratio of the number of measurement points at which [O] / [C] is 2.0 or less is 90% or more.

[0013] (5) A titanium processed product, wherein the average C content in a region 10 to 50 nm deep from the surface of the processed product is 5.0 mass% or more, and when depth analysis is performed using time-of-flight secondary ion mass spectrometry in the region from the surface to a depth of 50 nm, the maximum value of the detection intensity of negative ions with m / z of 59 standardized by the detection intensity of negative ions with m / z of 59 at a depth of 2000 nm from the surface is 30.0 or less.

[0014] (6) The processed titanium material according to (5) above, wherein the minimum value of the N content in the region from the surface to a depth of 50 nm is 5.0 mass % or more.

[0015] (7) The processed product is a processed product of a titanium plate, and when 500 line analyses are performed at 0.4 μm intervals in a predetermined direction on the surface of the processed product using an electron probe microanalyzer, and 500 line analyses are performed at 0.4 μm intervals in a direction perpendicular to the predetermined direction on the surface, and the measured concentrations (mass%) of C, N, and O are [C], [N], and [O], respectively, the average value of 36[C] + 3.6[N] at all measurement points is 90 or more, the percentage of the number of measurement points where the value of 36[C] + 3.6[N] is 20 or less is 35% or less, and the percentage of the number of measurement points where [O] / [C] is 0.2 or less is 35% or less, and when a distribution line of [O] is created for each line analysis and the number of intersections between the distribution line and a line showing a concentration 0.2 times the average value of [C] is measured, the average number of intersections in the 500 line analyses is 20 to 150. A processed titanium material according to (5) or (6) above.

[0016] (8) A processed titanium material according to (7) above, in which the ratio of the number of measurement points where [O] / [C] is 2.0 or less is 90% or more.

[0017] (9) The processed product according to any one of (5) to (8) above, which is an expanded metal.

[0018] (10) A product comprising the titanium material according to any one of (1) to (4) above and / or the processed product according to any one of (5) to (8) above.

[0019] (11) The product according to (10) above, which is a solid polymer water electrolysis device.

[0020] According to the present invention, it is possible to obtain titanium materials, processed products, and finished products having excellent lipophilicity and lubricity.

[0021] FIG. 1A is a diagram illustrating the measurement method for [C], [N], and [O], showing the relationship between the titanium plate and the measurement area. FIG. 1B is a diagram illustrating the measurement method for [C], [N], and [O], showing an enlarged view of the measurement area. FIG. 1C is a diagram illustrating the measurement method for [C], [N], and [O], showing an enlarged view of area A and area B surrounded by a dashed line in FIG. 1B. FIG. 2 is a graph showing the relationship between the value of [O] / [C] and the cumulative relative frequency. FIG. 3A is a graph showing the relationship between the measurement position and the concentration distribution of each element. FIG. 3B is a graph showing the relationship between the measurement position and the concentration distribution of each element. FIG. 4 is a side view when measuring penetration resistance.

[0022] The present inventors have conducted extensive research to obtain titanium materials and the like having excellent lipophilicity and lubricity, and have obtained the following findings.

[0023] As mentioned above, applying a liquid lubricant to the surface of titanium material is considered to improve its lubricity. However, because the surface of titanium material has low lipophilicity, even if a liquid lubricant is applied, sufficient lubrication may not be achieved. Therefore, the inventors investigated the cause of the low lipophilicity of the surface of titanium material. Titanium oxides and other substances are formed on the surface of titanium material due to atmospheric oxidation. They concluded that these titanium oxides and other substances are hydrophilic and therefore repel the applied liquid lubricant.

[0024] Further investigation by the present inventors has revealed that increasing the C content in the surface layer of a titanium material can improve the lipophilicity of the titanium material surface. However, if excessive TiC is formed in the surface layer of the titanium material, the surface layer of the titanium material becomes hard, causing microcracks during press forming. As a result, the base material of the titanium material is exposed, making it impossible to suppress adhesion. Therefore, in order to improve lubricity, it is important to increase the C content in the surface layer of the titanium material while dissolving C in a manner that minimizes the formation of TiC.

[0025] Here, whether the C present in the surface layer of the titanium material is dissolved C or TiC can be determined by depth analysis using time-of-flight secondary ion mass spectrometry (TOF-SIMS). TOF-SIMS performs qualitative and quantitative analysis by irradiating the surface of the titanium material with primary ions and measuring the intensity of secondary ions emitted from the surface of the titanium material.

[0026] In the present invention, the TiC-derived ions emitted as secondary ions are ４７ TiC － We focus on the negative ions (m / z 59) in the surface layer of the titanium material. ４７ TiC － If the detection intensity of ions can be reduced, it is clear that most of the C present in the surface layer of the titanium material exists as solid solution C.

[0027] The present invention was made based on the above findings. Each requirement of the titanium material according to one embodiment of the present invention will be described in detail below.

[0028] 1. Titanium Material In the present embodiment, the titanium material includes, for example, a titanium plate. The thickness of the titanium plate is preferably 0.5 to 5.0 mm when used as a processed product such as an expanded metal, or when used as a product such as a solid polymer water electrolysis device including a titanium material or a processed product.

[0029] 2. Titanium Base Material The type of base material for the titanium material according to this embodiment is not particularly limited. Examples of base materials include commercially pure titanium and titanium alloys.

[0030] Commercially pure titanium is specified by JIS, ASTM, etc., and typically has a Ti content of 99% by mass or more. Typical examples of commercially pure titanium include commercially pure titanium types 1 to 4 specified in JIS H 4600:2012, or ASTM / ASME Grades 1 to 4. Typical impurity elements in commercially pure titanium are C, H, O, N, and Fe. The contents of these elements in the above-mentioned commercially pure titanium are: C: 0.08% by mass or less, H: 0.015% by mass or less, O: 0.40% by mass or less, N: 0.05% by mass or less, and Fe: 0.50% by mass or less. Other elements such as Al, V, Si, Cr, Ni, Zr, Cu, Nb, Mo, Mn, Sn, Ta, Pd, Pt, Ru, B, Au, Ag, Hf, and REM (rare earth elements) may be contained in an amount of 0.1% by mass or less each and 0.4% by mass or less in total, as long as they do not deteriorate performance such as mechanical properties.

[0031] Titanium alloys are generally alloys containing 70% or more by mass of Ti. Examples of titanium alloys include α-type titanium alloys, α+β-type titanium alloys, and β-type titanium alloys. Examples of α-type titanium alloys include highly corrosion-resistant alloys (titanium alloys specified in JIS H 4600:2012 as grades 11 to 13, 17, and 19 to 22, as well as ASTM grades 7, 11, 13, 14, 17, 30, and 31, and titanium alloys containing small amounts of various elements), Ti-0.5Cu, Ti-1.0Cu, Ti-1.0Cu-0.5Nb, and Ti-1.0Cu-1.0Sn-0.3Si-0.25Nb. In all cases, the C content is 0.08 mass% or less, the H content is 0.015 mass% or less, the O content is 0.40 mass% or less, and the N content is 0.05 mass% or less. Furthermore, other elements such as Al, V, Si, Cr, Ni, Zr, Cu, Nb, Mo, Mn, Sn, Ta, Pd, Pt, Ru, B, Au, Ag, Hf, and REM (rare earth elements), which are not included in the elements and main additive elements described in the above-mentioned standards, may be contained in a range of 0.1 mass% or less each, and 0.4 mass% or less in total, as long as they do not deteriorate performance such as mechanical properties.

[0032] Examples of α+β titanium alloys include Ti-3Al-2.5V, Ti-5Al-1Fe, and Ti-6Al-4V. Examples of β 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. All of these alloys contain 0.08% by mass or less of C, 0.015% by mass or less of H, 0.40% by mass or less of O, and 0.05% by mass or less of N. Furthermore, other elements such as Al, V, Si, Cr, Ni, Zr, Cu, Nb, Mo, Mn, Sn, Ta, Pd, Pt, Ru, B, Au, Ag, Hf, and REM (rare earth elements), which are not included in the elements and main additive elements described in the above-mentioned standards, may be contained in an amount of 0.1% by mass or less each, and 0.4% by mass or less in total, as long as they do not deteriorate performance such as mechanical properties.

[0033] 3. Chemical Composition of Titanium Material Surface Layer <C Content> In the titanium material of this embodiment, the average C content in the region 10 to 50 nm deep from the surface of the titanium material is 5.0 mass% or more. To improve affinity with liquid lubricants, it is important to adjust the chemical composition of the titanium material's surface layer. However, when measuring the C content using the method described below, the measurement results for the outermost surface of the titanium material are easily affected by contamination such as attached organic matter. Therefore, in this invention, the region less than 10 nm deep from the surface of the titanium material is excluded, and the C content is specified in the region 10 to 50 nm deep from the surface of the titanium material.

[0034] If the average C content is less than 5.0% by mass, the titanium alloy will not have sufficient affinity with the liquid lubricant and will not provide sufficient lubricity. Therefore, the average C content is set to 5.0% by mass or more. There is no particular upper limit to the average C content. However, if the average C content is too high, C will likely bond with Ti to form TiC. If a large amount of TiC is formed, the surface layer of the titanium material will become hard, which may result in microcracks during press forming. As a result, the titanium material's base material may be exposed, resulting in insufficient affinity with the liquid lubricant. Furthermore, the affinity may be insufficient, and good lubricity may not be achieved. Therefore, the average C content is preferably 40.0% by mass or less, and more preferably 20.0% by mass or less.

[0035] <N Content> In the titanium material of this embodiment, the minimum N content in the region from the surface of the titanium material to a depth of 50 nm is preferably 5.0 mass% or more. To improve affinity with liquid lubricants, it is important to adjust the chemical composition of the surface layer of the titanium material. Furthermore, unlike the C content described above, the measurement results for N content are less susceptible to contamination such as organic matter adhering to the titanium material surface. Therefore, the present invention specifies the N content in the region from the surface of the titanium material to a depth of 50 nm.

[0036] By setting the minimum N content in the surface layer of the titanium material to 5.0% by mass or more, the reaction in which dissolved C and Ti in the surface layer of the titanium material form TiC and the reaction in which N and Ti form TiN are balanced. As a result, the formation of TiC is suppressed, and C can remain in a solid solution state. Note that TiN does not increase the surface hardness as much as TiC, so it does not adversely affect the lubricity of the titanium material. There is no particular upper limit for the N content, but when a titanium material is manufactured using the manufacturing method described below, the upper limit for the N content in the surface layer of the titanium material is 20.0% by mass.

[0037] The chemical composition of the surface layer of the titanium material is measured by the following method. The chemical composition of the surface layer of the titanium material is measured by glow discharge optical emission spectrometry (GD-OES). ＋ The measurement was performed under the following conditions: discharge conditions were a constant power mode of 35 W, Ar pressure of 600 Pa, the discharge area was a planar area of ​​4 mm in diameter, and the measurement pitch was approximately 1 nm. The chemical composition was analyzed while sputtering in the depth direction from the surface of the titanium material to a depth of 50 nm, and a profile of the C and N content (mass%) in the depth direction (hereinafter simply referred to as the "profile"). The elements to be measured were Ti, Fe, O, C, N, and elements contained in the titanium material at a concentration of 0.1% or more, and the total content of all measured elements was converted to 100%.

[0038] Using the sample after measurement, the depth removed by sputtering in the above measurement is measured with a surface roughness meter to confirm. The content at each depth automatically output by the device is then calibrated with the depth measured with the surface roughness meter. From the profile of the C and N content (mass%) measured continuously in the depth direction of the titanium material in this way, the average C content in the region 10 to 50 nm deep from the surface of the titanium material and the minimum N content in the region 50 nm deep from the surface of the titanium material are calculated.

[0039] < ４７ TiC －In the titanium material of this embodiment, the C content in the surface layer satisfies the above-mentioned requirement. In addition, when depth analysis using TOF-SIMS is performed in a region from the surface to a depth position of 50 nm, the detected intensity of the negative ion with m / z of 59 is normalized by the detected intensity of the negative ion with m / z of 59 at a depth position of 2000 nm from the surface (hereinafter referred to as "maximum value of normalized intensity"). ４７ TiC － The maximum value of the normalized intensity (normalized strength) is 30.0 or less. ４７ TiC － Since the lower the maximum value of the normalized strength, the better, there is no need to set a lower limit, but the manufacturable lower limit is 1.5.

[0040] In order to improve the affinity with the liquid lubricant, it is important to adjust the chemical composition of the surface layer of the titanium material. Therefore, in the present invention, attention is focused on the region from the surface of the titanium material to a depth of 50 nm. In the following explanation, ４７ TiC － The profile of normalized intensity in the depth direction is called ４７ TiC － Also called "intensity profile."

[0041] ４７ TiC － If the maximum value of the normalized strength exceeds 30.0, the excess TiC present in the surface layer of the titanium material makes the surface layer of the titanium material hard, causing minute cracks during press forming. As a result, the base material of the titanium material is exposed, and sufficient lubricity and lipophilicity cannot be obtained. Therefore, in the region from the surface of the titanium material to a position 50 nm from the surface, ４７ TiC － The maximum normalized intensity value is 30.0 or less.

[0042] The chemical composition of the surface layer of the titanium material is measured by the following method. The chemical composition of the surface layer of the titanium material is measured by TOF-SIMS. In this device, the primary ion species is Bi ＋ The acceleration voltage of the primary ions is 30 keV, and the measurement range is 50 μm. The sputtering ion species is Cs ＋ The acceleration voltage of the sputtering ions was 1 keV, and the sputtering was SiO ２ ​This is converted to 0.061 nm / time.

[0043] First, the titanium material is immersed in acetone and ultrasonically cleaned for 10 minutes, and then the surface is wiped with ethanol to remove any dirt or other contaminants adhering to the surface of the titanium material. Then, the chemical composition is analyzed by sputtering in the depth direction from the surface of the titanium material to a depth of 50 nm, and secondary ions derived from TiC, which are emitted from the surface of the titanium material, are analyzed. ４７ TiC － A profile of the absolute value of the detected intensity of (m / z: 59) was obtained. Then, sputtering was continued from the surface of the titanium material to a depth of 2000 nm, and the peak intensity at the depth of 2000 nm was measured. ４７ TiC － (m / z: 59) detection intensity at a depth of 2000 nm ４７ TiC － The detection intensity data is representative of the chemical composition of the titanium base material. ４７ TiC － It is used to normalize the profile of the absolute value of the detected intensity.

[0044] Obtained as above ４７ TiC － The absolute value of the detected intensity at each depth position was ４７ TiC － By dividing by the detected intensity and standardizing it, ４７ TiC － Normalized intensity, i.e., ４７ TiC － Obtain an intensity profile, and ４７ TiC － The maximum normalized intensity is determined.

[0045] 4. Characteristics If the surface hardness is too high, cracks may occur on the surface of the titanium material during press forming, exposing the base material of the titanium material. As a result, the affinity with liquid lubricants may decrease. Therefore, the surface hardness of the titanium material according to this embodiment is preferably 400 HV 0.025 or less. As described above, by suppressing the formation of TiC, the surface hardness of the titanium material can be reduced to 400 HV 0.025 or less. Note that "HV 0.025" refers to the "hardness symbol" when a Vickers hardness test is performed with a test force of 0.245 N (25 gf) (see JIS Z 2244-1:2020).

[0046] Surface hardness is measured by the following method. When the titanium material is a titanium plate, the hardness of the titanium plate surface is measured at 10 points at 1 mm intervals in the rolling direction at the center of the titanium plate in the plate width direction in accordance with the method specified in JIS Z 2244-1:2020. Here, the load is 0.245 N (25 gf), and the holding time is 10 seconds. Then, the surface hardness is determined by averaging the measured values ​​at 8 points, excluding the maximum and minimum values, out of the 10 measured values.

[0047] 5. Conductivity When the titanium material according to this embodiment is a titanium plate and is used in products such as a solid polymer water electrolysis device, it is desirable for the titanium material to have excellent thermal conductivity and electrical conductivity (hereinafter, collectively referred to as "conductivity").

[0048] In the titanium plate of this embodiment, the C content in the surface layer is increased, resulting in excellent conductivity. However, the surface layer in such a state is very hard, so cracks may occur during press forming, etc. If cracks occur, voids or the like are formed on the surface of the titanium plate, reducing the area for transmitting heat and electricity, which may deteriorate conductivity.

[0049] Furthermore, the newly formed surface in the voids is oxidized by oxygen in the atmosphere, such as the air, and titanium oxide, which has low conductivity, is formed on the newly formed surface. Therefore, when voids are formed, even if pressure is applied to press the titanium plate against another conductive member or substance, and the newly formed surface of the titanium plate comes into contact with the other conductive member or substance, conductivity may not be ensured.

[0050] Therefore, the present inventors have investigated methods for suppressing the occurrence of cracks during press forming of titanium plates and the like and for ensuring conductivity.

[0051] It was found that titanium carbide is about 10 times more effective at improving conductivity than titanium nitride. Therefore, it is effective to concentrate C in the surface layer of the titanium plate. This reduces the area on the surface of the titanium plate where the C content is extremely low. In this way, by controlling the chemical composition of the surface layer of the titanium plate, the conductivity of the titanium plate can be ensured.

[0052] However, even if the chemical composition of the surface layer of the titanium plate is controlled in this way, the C-enriched areas are more brittle than other areas, and there is a risk of cracks originating from the C-enriched areas during press forming, etc. As a result of further investigation, it was found that by incorporating O into the C-enriched areas, it is possible to suppress the occurrence of cracks without significantly reducing conductivity, and by controlling the distribution of the C and O-enriched areas as described below.

[0053] If C and O are concentrated uniformly on the surface layer of a titanium plate, there is a risk of cracks occurring on the surface of the titanium plate during press forming, etc. As a result of various studies, it was discovered that the occurrence of cracks can be suppressed by distributing regions where C and O are concentrated in an island pattern on the surface of the titanium plate in advance.

[0054] In the present invention, whether or not regions where C and O are concentrated are distributed in an island pattern on the surface of the titanium plate is evaluated using the chemical composition of the titanium plate surface measured using an electron probe microanalyzer (EPMA) as an index.

[0055] Specifically, 500 line analyses were performed at 0.4 μm intervals in a predetermined direction on the surface of the titanium plate. Furthermore, 500 line analyses were performed at 0.4 μm intervals in a direction perpendicular to the predetermined direction on the surface of the titanium plate. The measured concentrations (mass%) of C, N, and O are designated as [C], [N], and [O], respectively. The measurement method will now be described.

[0056] 1A to 1D are diagrams illustrating the measurement method for [C], [N], and [O]. Fig. 1A shows the relationship between titanium plate 11 and measurement area 12, Fig. 1B is an enlarged view of measurement area 12, and Fig. 1C is an enlarged view of areas A and B enclosed by dashed lines in Fig. 1B. In Fig. 1C, measurement points 13 are indicated by black dots, and a virtual line 14 used for line analysis is indicated by a dashed two-dot line.

[0057] 1B, the left-right direction D1 and the up-down direction D2 on the paper surface are indicated by arrows. The left-right direction D1 and the up-down direction D2 are orthogonal to each other. In this embodiment, the left-right direction D1 corresponds to a "predetermined direction," and the up-down direction D2 corresponds to a "direction orthogonal to the predetermined direction."

[0058] 1A, first, the position and size of a measurement area 12 are determined on the surface of titanium plate 11. However, measurement area 12 is located on the surface of titanium plate 11, near the center in the rolling direction of titanium plate 11, and near the center in the width direction of titanium plate 11. Furthermore, measurement area 12 may be 200 μm × 200 μm in size so that all measurement points described below are included.

[0059] Next, the chemical composition of the titanium plate surface was measured using a field emission electron microanalyzer (FE-EPMA). As shown in Figures 1B and 1C, [C], [N], and [O] were measured in the measurement area 12 along the imaginary line 14a connecting the measurement points 13a and 13b. The measurements were performed at 500 points in the left-right direction D1, with the measurement points 13 spaced 0.4 μm apart.

[0060] Then, [C], [N], and [O] are similarly measured along imaginary line 14b connecting measurement point 13c and measurement point 13d. Imaginary line 14b is spaced 0.4 μm from imaginary line 14a. Similarly, measurements are continued until the number of imaginary lines 14 in the vertical direction D2 reaches 500, with the spacing between each imaginary line 14 being 0.4 μm. In this manner, data on [C], [N], and [O] are obtained at a total of 250,000 measurement points 13, 500 in the horizontal direction D1 and 500 in the vertical direction D2.

[0061] The quantitative determination of [C], [N], and [O] in the titanium plate is performed by comparison with the measurement results using a standard sample. Specifically, [C] is quantified by comparison with the measurement results using 100% C (graphite), and the background is the C intensity measured on the mirror surface of pure Ti with a purity of 99.9%. [N] is quantified by comparison with the measurement results using TiN. However, in the measurement of [N], the measured value cannot simply be taken as the N intensity. This is because the TiLι (iota) line of Ti overlaps with the NKα line of N. Therefore, the intensity ratio between the TiKα line and the TiLι line is determined in advance by measuring the TiKα line and the TiLι line on the mirror surface of pure Ti with a purity of 99.9%. Subsequently, when measuring [N] in the titanium plate and TiN, the intensity of the TiKα line is measured, and the intensity of the TiLι line is calculated from the measured value and the above-mentioned intensity ratio. Then, the intensity of the NKα ray is calculated by subtracting the calculated intensity of the TiLι ray from the measured value of the N intensity, and the amount of [N] is quantified based on the obtained intensity. ２ O ３ ) and the background is the O intensity measured on a mirror surface of pure Ti with a purity of 99.9%.

[0062] Average value of 36[C] + 3.6[N] at all measurement points: 90 or more. The value of 36[C] + 3.6[N] is calculated at each of the above measurement points, and the average value is calculated for all measurement points, a total of 250,000 points. If this value is less than 90, the concentration of titanium carbide and titanium nitride may be insufficient, making it difficult to obtain good conductivity. Therefore, if excellent conductivity is desired, the average value of 36[C] + 3.6[N] at all measurement points is preferably 90 or more. The average value of 36[C] + 3.6[N] at all measurement points is more preferably 100 or more, even more preferably 110 or more, and even more preferably 120 or more. There is no need to set an upper limit to the average value of 36[C] + 3.6[N] at all measurement points, but 250 is the upper limit that can be manufactured.

[0063] Proportion of measurement points where the 36[C] + 3.6[N] value is 20 or less: 35% or less. The number of measurement points where the 36[C] + 3.6[N] value is 20 or less at each of the above measurement points is counted, and the proportion of these measurement points relative to the total of 250,000 measurement points is calculated. If this proportion exceeds 35%, there will be areas on the titanium plate surface where the concentration of titanium carbide and titanium nitride is extremely low, resulting in reduced conductivity at these locations, which may prevent the titanium plate from achieving good conductivity. Therefore, it is preferable that the proportion of measurement points where the 36[C] + 3.6[N] value is 20 or less be 35% or less. It is more preferable that the proportion of measurement points where the 36[C] + 3.6[N] value is 20 or less be 30% or less. The percentage of the number of measurement points where the value of 36[C] + 3.6[N] is 20 or less is preferably as low as possible, so there is no need to set a lower limit; it may be 0% or 0.01% or more.

[0064] The proportion of measurement points where [O] / [C] is 0.2 or less: 35% or less. Fig. 2 is a graph showing the relationship between the [O] / [C] value and the cumulative relative frequency. The horizontal axis shows the [O] / [C] value, and the vertical axis shows the cumulative relative frequency at each measurement point for each [O] / [C] value.

[0065] Measurement points where [O] / [C] is 0.2 or less have a higher [C] than [O], making them more brittle and likely to become crack initiation points. When the number of measurement points where [O] / [C] is 0.2 or less exceeds 35% of all measurement points, i.e., in the example shown by the dashed line in Figure 2, cracks may occur on the surface of the titanium plate and develop into large cracks. Therefore, as in the example shown by the solid line in Figure 2, it is preferable that the number of measurement points where [O] / [C] is 0.2 or less is 35% or less. It is more preferable that the number of measurement points where [O] / [C] is 0.2 or less is 30% or less. Furthermore, it is preferable that the number of measurement points where [O] / [C] is 0.1 or less is 20% or less. The lower the percentage of the number of measurement points where [O] / [C] is 0.2 or less and the lower the percentage of the number of measurement points where [O] / [C] is 0.1 or less, the better. Therefore, there is no need to set a lower limit; they may be 0% or 1% or more.

[0066] On the other hand, by setting [O] / [C] to 2.0 or less, it is possible to contain C and O in an appropriate ratio in the surface layer of the titanium plate, and to suppress the occurrence of cracks and the decrease in conductivity due to excessive concentration of O. Therefore, as shown by the solid line in Figure 2, it is preferable that the number ratio of measurement points where [O] / [C] is 2.0 or less is 90% or more. The higher the number ratio of measurement points where [O] / [C] is 2.0 or less, the better, so there is no need to set an upper limit, and it may be 100%.

[0067] Furthermore, by setting the maximum value of [O] / [C] to 7.0 or less, it is possible to suppress a decrease in conductivity due to excessive concentration of O. Therefore, the maximum value of [O] / [C] is preferably set to 7.0 or less, and more preferably set to 4.0 or less.

[0068] Number of intersections between the [O] distribution line and the line indicating a concentration 0.2 times the average value of [C]: 20 to 150. Figures 3A and 3B are graphs showing the relationship between measurement position and the concentration distribution of each element. In Figures 3A and 3B, the horizontal axis represents the position in the left-right direction D1 on the virtual line 14 (see Figure 1B), and the vertical axis at each position represents [C] and [O]. Note that Figures 3A and 3B each show an example of the 500 virtual lines 14 described above. In Figures 3A and 3B, [C] is represented by a dashed line and [O] by a solid line. Also, in Figures 3A and 3B, the dashed line represents the concentration 0.2 times the average value of [C]. Note that for convenience of explanation, the concentration distribution of [N] is omitted.

[0069] The number of intersections between the straight line P shown in Figures 3A and 3B and the distribution line of [O] is measured. For example, in the example shown in Figure 3A, there were 53 intersections, and in the example shown in Figure 3B, there were 209 intersections. This measurement is performed for all 500 virtual lines 14, and the average number of intersections is calculated. For example, in the example shown in Figure 3A, there were 62 intersections, and in the example shown in Figure 3B, there were 208 intersections.

[0070] As mentioned above, if O is uniformly concentrated on the surface layer of the titanium plate, cracks may occur during forming. Therefore, it is necessary that the O-concentrated areas are appropriately dispersed on the surface of the titanium plate. That is, as in the example shown in Figure 3A, it is preferable that areas with low [O] and areas with high [O] are appropriately repeated, and that the [O] peaks are measured at an appropriate frequency.

[0071] If the average value obtained as described above is less than 20, the width of the [O] peak will be too wide or the number of [O] peaks will be too small. As a result, the region where [O] is high or the region where [O] is low will be too wide, respectively, and in either case, cracks may occur. On the other hand, if the average value exceeds 150, the width of the [O] peak will be too narrow or the number of [O] peaks will be too large. As a result, O will be distributed almost uniformly, and cracks may occur. Therefore, it is preferable that the number of intersections between the [O] distribution line and the line representing a concentration 0.2 times the average value of [C] be 20 to 150. It is more preferable that the number of intersections between the [O] distribution line and the line representing a concentration 0.2 times the average value of [C] be 100 or less.

[0072] 5. Processed Products The titanium material according to this embodiment has excellent lipophilicity and lubricity, and can be used as a processed product after various processes. That is, the processed product is obtained by processing the titanium material described above. Examples of processing methods include press processing and shear processing. Examples of processed titanium material products include expanded metal.

[0073] It is preferable that the chemical composition of the surface layer of the processed product satisfies the above-mentioned regulations regarding the chemical composition of the surface layer of the titanium material. ４７ TiC － The maximum value of the standardized strength was also the same as that of the titanium surface layer mentioned above. ４７ TiC －It is preferable that the specifications regarding the maximum normalized strength be satisfied. Furthermore, it is preferable that the hardness of the surface of the processed product satisfy the specifications regarding the hardness of the titanium material surface described above. The reasons why it is preferable to satisfy these specifications are the same as those explained for titanium materials, and therefore will not be explained here.

[0074] However, the chemical composition of the surface layer and ４７ TiC － The maximum normalized strength is measured in an area with a smooth surface suitable for performing surface analysis. Similarly, surface hardness is measured in an area with a smooth surface suitable for hardness measurement, regardless of the rolling direction. If it is not possible to secure 10 measurement points at 1 mm intervals in one smooth surface area, measurements are made as many times as possible at 1 mm intervals in multiple smooth surface areas, each at 1 mm intervals, and the measurement positions are selected so that the total number of measurement points is 10, and Vickers hardness is measured. Titanium material or processed titanium material may also be used to make products such as solid polymer water electrolysis devices.

[0075] 7. Manufacturing Method The manufacturing method of the titanium material of this embodiment is not particularly limited. For example, the titanium material can be stably manufactured by the following manufacturing method.

[0076] 7-1. Preparation Step In the preparation step, a material for hot rolling is prepared. This material may be commercially pure titanium or a titanium alloy, and the type is not particularly limited. The material for hot rolling may be produced according to a conventional method. For example, an ingot of titanium material may be produced by arc melting or the like, and then hot forged to produce the material for hot rolling.

[0077] The above-mentioned hot rolling material is hot rolled to produce a hot rolled material. The conditions for hot rolling are not particularly limited. They may be appropriately adjusted depending on the desired properties. The obtained hot rolled material may be subjected to a heat treatment as appropriate.

[0078] In the descaling step, oxide scale formed by hot rolling, heat treatment, etc. is removed. The method and conditions for descaling are not particularly limited. For example, shot blasting may be followed by pickling or mechanical grinding.

[0079] 7-3. Cold Rolling Process In the cold rolling process, after removing the scale, the hot-rolled material is cold-rolled to produce a cold-rolled material. During cold rolling, a cold-rolling oil containing C is used. In the method for producing a titanium material of this embodiment, for example, mineral oil or soluble oil can be used as the cold-rolling oil. By using mineral oil or soluble oil, a mechanochemical reaction occurs during cold rolling. As a result, C is supersaturated and solid-dissolved in the surface layer of the hot-rolled material. Note that commercially available cold-rolling oil may be used.

[0080] Cold rolling is typically performed using a Sendzimir rolling mill. In a Sendzimir rolling mill, a titanium material is rolled by passing it back and forth between a pair of work rolls multiple times. Here, passing a titanium material through the work rolls of the rolling mill is called a pass. Therefore, in cold rolling, the target thickness is typically controlled through multiple passes. In other words, cold rolling is a process that involves multiple passes.

[0081] If the average rolling reduction is less than 5%, the mechanochemical reaction cannot be promoted. On the other hand, if the average rolling reduction is more than 20%, excessive C is dissolved in the solid solution, resulting in excessive formation of TiC. Therefore, the average rolling reduction is set to 5 to 20%. The average rolling reduction is preferably more than 5%, and more preferably more than 7%. Furthermore, the average rolling reduction is preferably less than 19%, and more preferably less than 17%.

[0082] The average rolling reduction mentioned above is the average value of the rolling reductions of the passes obtained by the following formula (ii): Rolling reduction (%) = (h1 - h2) / h1 x 100 (ii) where the symbols in the formula (ii) above are defined as follows: h1 (mm): thickness of the titanium material before the pass h2 (mm): thickness of the titanium material after the pass

[0083] 7-4. Cleaning Process In the cleaning process, after cold rolling, the cold-rolled material is washed to remove the cold-rolling oil adhering to its surface, followed by rinsing with water. The cold-rolled material is then dried. In the step of cleaning the cold-rolling oil, an alkaline cleaner containing NaOH and KOH is used, with a concentration of 2.5 to 5.0 vol. %. In addition, in the step of drying the cold-rolled material, water droplets remaining on the surface of the cold-rolled material are removed with a rubber roller. This allows the cold-rolling oil to remain appropriately on the surface of the cold-rolled material.

[0084] The type of alkaline detergent used to clean the cold-rolling oil is not particularly limited as long as it contains NaOH and KOH. For example, it is preferable to use an alkaline detergent (Pakuna DST-58-L manufactured by Yuken Industry Co., Ltd.). The concentration of the alkaline detergent is set to 2.5 to 5.0 vol.%. If the concentration of the alkaline detergent is less than 2.5 vol.%, excessive cold-rolling oil remains on the surface of the cold-rolled material, which may result in the formation of TiC during the annealing process. On the other hand, if the concentration of the alkaline detergent is more than 5.0 vol.%, the cold-rolling oil is removed, making it impossible to achieve an average C content of 5.0 mass% or more. Therefore, the concentration of the alkaline detergent is set to 2.5 to 5.0 vol.%.

[0085] In the cleaning process, conditions are not particularly limited except that a 2.5 to 5.0 vol. % alkaline cleaner is used and water droplets are removed with a rubber roller. For example, the following conditions may be used: An alkaline cleaner adjusted to a pH range of 7 to 12 at 25°C is heated to 50 to 70°C, and the cold-rolled material is immersed for 2 to 5 minutes. Subsequently, the cold-rolled material is spray-cleaned for 2 to 5 minutes using pure water at 60°C, or the cold-rolled material is immersed in pure water at 60°C for 2 to 5 minutes. As described above, water droplets remaining on the surface of the cold-rolled material are removed with a rubber roller, and then the material is dried for 2 to 5 minutes with a dryer. Note that removing water droplets with a rubber roller also makes it possible to preliminarily distribute regions where carbon and oxygen are concentrated on the titanium plate surface in an island-like pattern.

[0086] After cleaning, removal of the surface layer by pickling, grinding, etc. is not carried out, because this removes the C that has adhered to and concentrated on the surface of the cold-rolled material during the cold rolling process.

[0087] 7-5. Annealing Step In the annealing step, the titanium material is heated and held in a predetermined atmosphere to adjust the chemical composition of the surface layer of the titanium material, thereby obtaining the titanium material according to this embodiment. The atmosphere is preferably an atmosphere of inert gas at 1 atm or more, or an atmosphere of nitrogen gas with a purity of 99% or more at 1 atm or more. In either atmosphere, components other than the inert gas or nitrogen gas are preferably inert gas and impurity gas, and the dew point is preferably -40°C or less. ２ and H ２ This is to prevent the intrusion of O as much as possible and to prevent the reaction between Ti and C and N on the surface of the titanium material from being inhibited.

[0088] By performing annealing in an inert gas atmosphere of 1 atm or more, the C dissolved and deposited in the cold rolling process can be dissolved in the surface layer of the titanium material while suppressing the formation of TiC. Furthermore, by performing annealing in an atmosphere of nitrogen gas of 1 atm or more, the reaction in which Ti combines with N to form TiN and the reaction in which Ti combines with C to form TiC are antagonized, thereby suppressing the formation of TiC. Note that there are no particular upper limits on the partial pressures of the inert gas and nitrogen gas. Due to the convenience of the annealing equipment, the partial pressure is usually 10 atm or less.

[0089] The annealing temperature in the above atmosphere is 600 to 850°C, and the annealing time is 0.5 to 10 minutes. By setting the annealing temperature to 600°C or higher and the annealing time to 0.5 minutes or longer, the reaction that produces TiC is suppressed, and TiN is preferentially produced. Furthermore, by setting the annealing temperature to 850°C or lower and the annealing time to 10 minutes or shorter, the decrease in the C content in the surface layer due to the diffusion of solute C inside the titanium material can be suppressed.

[0090] 7-6. Processed Product Manufacturing Process In the processed product manufacturing process, the titanium material obtained as described above is processed to obtain a processed product. The processing method is not particularly limited. For example, pressing or shearing may be performed. Examples of processed products obtained by pressing, shearing, etc. include expanded metal. Furthermore, products such as solid polymer water electrolysis devices may be manufactured using the titanium material or the processed product.

[0091] The titanium material according to this embodiment will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0092] The types of titanium materials shown in Table 1 were prepared. These titanium materials were manufactured through processes such as hot rolling. Note that "JIS Class 1" refers to Class 1 commercially pure titanium as specified in JIS H 4600:2012, "JIS Class 2" refers to Class 2 commercially pure titanium as specified in JIS H 4600:2012, and "JIS Class 3" refers to Class 3 commercially pure titanium as specified in JIS H 4600:2012.

[0093] These titanium materials were cold worked using mineral oil at the average reduction shown in Table 1, and then washed and annealed under the conditions shown in Table 1 to obtain titanium plates with the thicknesses shown in Table 1. Note that "NaOH+KOH" in the "Type of cleaning solution" column in Table 1 means that an alkaline cleaning agent (Pakuna DST-58-L manufactured by Yuken Kogyo Co., Ltd.) with the concentration shown in Table 1 was used. Also, "HF+HNO ３ " is a solution of 46.0 to 48.0% by mass of HF in water and 65 to 66% by mass of HNO ３ This means that aqueous solutions of 1 vol. % and 4 vol. % nitric acid were used.

[0094]

[0095] For each titanium plate obtained as described above, the C and N contents in the titanium plate surface layer, and ４７ TiC － The maximum normalized strength was measured, and evaluations were also made of lipophilicity, surface hardness, and lubricity.

[0096] <Contents of C and N in the Surface Layer of Titanium Plate> The chemical composition of the surface layer of the titanium plate was measured by the following method. The chemical composition of the surface layer of the titanium plate was measured by GD-OES using a GD-Profiler 2 manufactured by Horiba Ltd. (JOBIN YVON). Sputtering was performed using Ar ＋The measurement was performed under the following conditions: discharge conditions were a constant power mode of 35 W, an Ar pressure of 600 Pa, a discharge area of ​​a planar area of ​​φ4 mm, and a measurement pitch of approximately 1 nm. Then, the chemical composition was analyzed while sputtering in the depth direction from the surface of the titanium plate to a depth of 50 nm, and profiles of the C and N content (mass%) were obtained. The elements to be measured were Ti, Fe, O, C, N, and elements contained in the titanium material at 0.1% or more, and the total content of all measured elements was calculated to be 100%.

[0097] Using the sample after measurement, the depth scraped by sputtering in the above measurement was measured and confirmed with a surface roughness meter.The content at each depth automatically output by the device was then calibrated with the depth measured with the surface roughness meter.From the profile of the C and N content (mass%) measured continuously in the depth direction of the titanium plate in this way, the average value of the C content in the region from the surface of the titanium plate to a depth of 10 to 50 nm and the minimum value of the N content in the region from the surface of the titanium plate to a depth of 50 nm were calculated.

[0098] < ４７ TiC － Maximum value of normalized strength> The chemical composition of the surface layer of the titanium plate was measured by the following method. ５ The chemical composition of the surface layer of the titanium plate was measured by TOF-SIMS using a Bi ion source. ＋ The acceleration voltage of the primary ions is 30 keV, and the measurement range is 50 μm. The sputtering ion species is Cs ＋ The acceleration voltage of the sputtering ions was 1 keV, and the sputtering was SiO ２ This is converted to 0.061 nm / time.

[0099] First, the titanium plate was immersed in acetone and ultrasonically cleaned for 10 minutes, and then the surface was wiped with ethanol to remove dirt and other contaminants from the surface of the titanium plate. Then, the chemical composition was analyzed while sputtering in the depth direction from the surface of the titanium plate to a depth of 50 nm, and secondary ions derived from TiC, which were emitted from the surface of the titanium plate, were analyzed. ４７ TiC －A profile of the absolute value of the detected intensity of (m / z: 59) was obtained. Subsequently, sputtering was continued from the surface of the titanium plate to a depth of 2000 nm. ４７ TiC － The detected intensity of (m / z: 59) was obtained.

[0100] Obtained as above ４７ TiC － The absolute value of the detected intensity at each depth position was ４７ TiC － By dividing by the detected intensity and standardizing it, ４７ TiC － Normalized intensity, i.e., ４７ TiC － The intensity profile was obtained, and ４７ TiC － The maximum normalized intensity was determined.

[0101] <Evaluation of Lipophilicity> Lipophilicity was evaluated by wettability. Wettability was evaluated by measuring the contact angle between the titanium plate surface and Castor S-811 (hereinafter referred to as "mineral oil"), a liquid lubricant manufactured by Taille, in accordance with the contact angle method specified in JIS Z 0305:1998. For the test specimens, titanium plates were used that had been subjected to the annealing process as described above and then skin-pass rolled at an elongation of 2% to simulate the surface after product processing. A lower contact angle indicates a higher affinity between the titanium plate surface and mineral oil. Therefore, a contact angle of less than 15° was evaluated as an lipophilicity rating of "A," a contact angle of 15° or more but less than 20° was evaluated as an lipophilicity rating of "B," and a contact angle of 20° or less was evaluated as an lipophilicity rating of "C."

[0102] <Measurement of Surface Hardness> The surface hardness was measured by the following method. The hardness of the titanium plate surface was measured at 10 points at 1 mm intervals in the rolling direction at the center of the titanium plate in the plate width direction in accordance with the method specified in JIS Z2244:2009. Here, the load was 25 gf (0.245 N), and the holding time was 10 seconds. Then, the average value of the 8 measurement points excluding the maximum and minimum values ​​out of the 10 measurement points was taken as the surface hardness.

[0103] <Evaluation of Lubricity> The lubricity of the titanium plate was evaluated by the average coefficient of friction. The average coefficient of friction was measured using the following method. Using a pin-on-disk friction and wear tester, a pin was slid across the surface of the titanium plate, and a friction and wear test was performed using a lubricant. Castor S-811 manufactured by Taille was used as the lubricant. The test was performed under conditions of a surface pressure of 1 MPa, a speed of 0.1 m / min, and a sliding distance of 2000 mm, and the average coefficient of friction was calculated. The pins used in the test were made of high-carbon chromium bearing steel SUJ2 specified in Japanese Industrial Standards JIS G 4805:2019, and had a smooth surface with a diameter of 3.5 mm and an arithmetic mean roughness Ra of 0.12. A lubricity rating of "A" was given when the average coefficient of friction was 0.30 or less, and a lubricity rating of "B" was given when it exceeded 0.30.

[0104] The results are summarized in Table 2 below.

[0105]

[0106] Furthermore, for each titanium plate, the [C], [N], and [O] on the surface of the titanium plate were measured using the method described above. The conductivity of each titanium plate was also evaluated by electrical conductivity as described below. Since both electricity and heat are conducted by electrons, the higher the electrical conductivity, the higher the thermal conductivity. Furthermore, the conductivity and cracks after processing simulating press forming were also evaluated for each titanium plate.

[0107] <Evaluation of Electrical Conductivity> The evaluation of electrical conductivity was carried out by the following method. Electrical conductivity was evaluated by penetration resistance. FIG. 4 is a side view when measuring penetration resistance. First, a test piece 21 measuring 1.5 cm x 1.5 cm was taken from the above-mentioned titanium plate without changing the plate thickness. Then, both sides of the test piece 21 were sandwiched between 1 cm x 1 cm conductive carbon sheets 22, and further sandwiched between 2 cm x 2 cm platinum electrodes 23. For the conductive carbon sheets, carbon paper TGP-H-090 manufactured by Toray Industries, Inc. was used. In this state, a pressure of 10 kgf / cm was applied. ２ The electric resistance α was measured with a load of 1.0 MPa and a current of 1 A.

[0108] The carbon conductive sheet 22 alone was sandwiched between the platinum electrodes in advance, and a pressure of 10 kgf / cm ２ The electrical resistance β was measured with a load of 1000 kJ / cm2 and a current of 1 A. This electrical resistance β is the electrical resistance between the electrode and the conductive sheet. The penetration resistance of the titanium plate was determined by subtracting the electrical resistance β from the electrical resistance α. The penetration resistance of Test No. 14 was used as the reference penetration resistance, and the value obtained by dividing the penetration resistance of each test piece by the reference penetration resistance is shown in Table 3 as the relative penetration resistance. The lower the relative penetration resistance, the higher the conductivity.

[0109] In addition, each test piece was subjected to a process simulating press forming, and the penetration resistance was measured. First, from each titanium plate obtained as described above, a tensile test piece was prepared, having a parallel portion with a width of 20 mm and a length of 60 mm, a gauge length of 50 mm in the parallel portion, and a shoulder and a grip portion at both ends, so that the cold rolling direction was parallel to the tensile direction. Then, the tensile test piece was pulled from both ends by the grip portion, and the pulling was stopped when the gauge length of the parallel portion was elongated by 15%. Then, a test piece with a thickness of 1.5 cm x 1.5 cm was taken from the center of the parallel portion, and the penetration resistance was measured by the above-mentioned method. Then, the penetration resistance of Test No. 14 before processing was taken as the reference penetration resistance, and the value obtained by dividing the penetration resistance of each test piece by the reference penetration resistance was shown in Table 3 as the relative penetration resistance.

[0110] <Evaluation of cracks> The surface of each tensile test piece after processing was observed at the center of the parallel section to evaluate the presence or absence of cracks. The surface was observed using a scanning electron microscope (SEM). The surface of the test piece was observed at a magnification of 200 times.

[0111] When the crack length was 50 μm or less, it was considered that there were no cracks and the evaluation was "A". When the crack length was more than 50 μm and less than 100 μm, it was considered that there were no cracks that had a significant effect on the penetration resistance and the evaluation was "B". When the crack length was more than 100 μm and less than 200 μm, it was considered that a fine crack that affected the penetration resistance had occurred and the evaluation was "C". When the crack length was more than 200 μm, it was considered that a coarse crack that affected the penetration resistance had occurred and the evaluation was "D".

[0112]

[0113] In the inventive examples, Test Nos. 2 to 7 and 16 to 21, the preferred manufacturing conditions were met, and therefore the requirements of the present invention were satisfied, resulting in good lipophilicity and lubricity. Furthermore, by preliminarily distributing regions where C and O were concentrated on the titanium plate surface in an island-like pattern, the occurrence of cracks was suppressed, resulting in excellent electrical conductivity. On the other hand, the comparative examples, Test Nos. 1 and 8 to 15, did not meet the preferred manufacturing conditions of the present invention, and therefore did not meet the requirements of the present invention.

[0114] Specifically, in Test No. 1, cold rolling was performed using mineral oil, but no annealing process was performed. As a result, the C attached to the surface of the cold-rolled sheet by cold rolling could not be solid-dissolved, resulting in a low average C content. As a result, lipophilicity and lubricity were insufficient. In Test No. 8, cold rolling was performed using mineral oil, but annealing was performed in a vacuum atmosphere for a long period of time. As a result, C diffused into the interior of the titanium sheet, reducing the average C content in the surface layer. As a result, lipophilicity and lubricity were insufficient.

[0115] In Test No. 9, the average reduction rate in the cold rolling process was high. As a result, excessive C was dissolved, and excessive TiC was formed after the annealing process. As a result, the lipophilicity and lubricity were insufficient. In Test No. 10, the concentration of the cleaning solution was high. As a result, the C remaining on the surface of the cold-rolled sheet in the cold rolling process was removed, and the average C content decreased. As a result, the lipophilicity and lubricity were insufficient.

[0116] In Test No. 11, the partial pressure of nitrogen gas was low and the annealing temperature was high, resulting in a decrease in the average C content on the surface. As a result, lipophilicity and lubricity were insufficient. In Test No. 12, the annealing temperature was low and the annealing time was long, resulting in excessive TiC formation. As a result, lipophilicity and lubricity were insufficient. In Test No. 13, cold rolling was performed using mineral oil, but water droplets were removed using a nonwoven fabric roller in the cleaning process. As a result, the cold-rolling oil could not be adequately left on the surface of the cold-rolled sheet, and C could not be sufficiently solid-dissolved in the surface layer of the titanium sheet. As a result, lipophilicity and lubricity were insufficient.

[0117] In Test No. 14, the concentration of the cleaning solution was high in the cleaning process, and water droplets were removed using a nonwoven fabric roller. As a result, the cold-rolling oil could not be adequately left on the surface of the cold-rolled sheet, and C could not be sufficiently solid-dissolved in the surface layer of the titanium sheet. As a result, the lipophilicity and lubricity were insufficient. In Test No. 15, pickling was performed in the cleaning process. Therefore, the C that had been solid-dissolved in the cold-rolling process was removed by pickling, and C could not be sufficiently solid-dissolved in the surface layer of the titanium sheet. As a result, the lipophilicity and lubricity were insufficient.

[0118] According to the present invention, it is possible to obtain titanium materials, processed products, and finished products having excellent lipophilicity and lubricity.

[0119] 11 Titanium plate 12 Measurement area 13 Measurement point 14 Virtual line 21 Test piece 22 Conductive sheet 23 Electrode

Claims

1. A titanium material in which the average carbon content in a region 10 to 50 nm deep from the surface is 5.0 mass% or more, and when depth analysis is performed using time-of-flight secondary ion mass spectrometry in the region from the surface to a depth of 50 nm, the maximum value of the detection intensity of negative ions with m / z of 59 standardized by the detection intensity of negative ions with m / z of 59 at a depth of 2000 nm from the surface is 30.0 or less.

2. The titanium material according to claim 1, wherein the minimum value of the N content in the region from the surface to a depth of 50 nm is 5.0 mass % or more.

3. The titanium material is a titanium plate, and an electron probe microanalyzer is used to perform 500 line analyses at 0.4 μm intervals in a predetermined direction on the surface of the titanium plate, and 500 line analyses at 0.4 μm intervals in a direction perpendicular to the predetermined direction on the surface, and the measured concentrations of C, N, and O (mass%) are [C], [N], and [O], respectively. Among all the measurement points, the average value of 36[C] + 3.6[N] is 90 or more, the percentage of the number of measurement points where the value of 36[C] + 3.6[N] is 20 or less is 35% or less, and the percentage of the number of measurement points where [O] / [C] is 0.2 or less is 35% or less, and a distribution line of [O] is created for each line analysis, and when the number of intersections between the distribution line and a line showing a concentration 0.2 times the average value of [C] is measured, the average number of intersections among the 500 line analyses is 20 to 150. The titanium material according to claim 1 or 2.

4. The titanium material according to claim 3, wherein the percentage of measurement points where [O] / [C] is 2.0 or less is 90% or more.

5. A titanium processed product, wherein the average carbon content in a region 10 to 50 nm deep from the surface of the processed product is 5.0 mass% or more, and when depth analysis is performed using time-of-flight secondary ion mass spectrometry in the region from the surface to a depth of 50 nm, the maximum value of the detection intensity of negative ions with m / z of 59 standardized by the detection intensity of negative ions with m / z of 59 at a depth of 2000 nm from the surface is 30.0 or less.

6. A processed titanium product according to claim 5, wherein the minimum value of the N content in the region from the surface to a depth of 50 nm is 5.0 mass% or more.

7. The processed product is a titanium plate processed product, and an electron probe microanalyzer is used to perform 500 line analyses at 0.4 μm intervals in a predetermined direction on the surface of the processed product, and 500 line analyses at 0.4 μm intervals in a direction perpendicular to the predetermined direction on the surface, and the measured concentrations of C, N, and O (mass%) are [C], [N], and [O], respectively. Among all the measurement points, the average value of 36[C] + 3.6[N] is 90 or more, the percentage of the number of measurement points where the value of 36[C] + 3.6[N] is 20 or less is 35% or less, and the percentage of the number of measurement points where [O] / [C] is 0.2 or less is 35% or less, and a distribution line of [O] is created for each line analysis, and when the number of intersections between the distribution line and a line showing a concentration 0.2 times the average value of [C] is measured, the average number of intersections among the 500 line analyses is 20 to 150.

7. A processed titanium material according to claim 5 or 6.

8. A processed titanium product according to claim 7, in which the percentage of measurement points where [O] / [C] is 2.0 or less is 90% or more.

9. The processed product according to any one of claims 5 to 8, which is an expanded metal.

10. A product comprising the titanium material according to any one of claims 1 to 4 and / or the processed product according to any one of claims 5 to 8.

11. The product according to claim 10, which is a solid polymer water electrolysis device.

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