Titanium plate, processed product, plate-type heat exchanger, and polymer electrolyte water electrolyzer

Abstract

To provide a titanium sheet in which the generation of cracks is suppressed, and which has excellent lubricity and wear resistance.SOLUTION: An average value of area ratios of titanium carbide and the like at all measurement points is 30.0% or more, when measurement is performed using a Raman spectrometer at 80 points in each of a predetermined direction and a direction orthogonal to the predetermined direction on a surface of the titanium plate such that an interval between centers of spots is 2.5 μ m, that is, at 6400 points in total, and area ratios of four of titanium carbide and the like, anatase, rutile, and undetected are obtained at each measurement point such that a total is 100%, An average value of total area ratios of anatase and rutile at all measurement points is 1.0 to 5.0%, and when all the measurement points are divided into 10 equal parts in a predetermined direction and divided into 10 equal parts in a direction orthogonal to the predetermined direction to be divided into 100 sections in total, the number of sections including a point at which the total area ratio of anatase and rutile is 20.0% or more is 10 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a titanium plate, a processed product, a plate heat exchanger, and a solid polymer water electrolysis device. [Background technology]

[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 materials that 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 usually 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. In light of this background, the invention described in Patent Document 1 develops a titanium material that is resistant to adhesion and has good lubricity. The titanium material disclosed in Patent Document 1 has an oxide film made of rutile-type TiO2, which has good lubricity, formed on its surface by heating in air. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-183551 Summary of the Invention [Problem to be solved by the invention]

[0005] Titanium oxide coatings can be formed relatively easily by heat treatment in air, taking advantage of the highly reactive properties of titanium. However, because titanium oxide coatings are hard and brittle, they can develop fine cracks during press forming. If these fine cracks grow during use and expose the titanium base material, sufficient lubricity cannot be achieved.

[0006] Furthermore, for example, in plate-type heat exchangers, solid polymer water electrolysis devices, and the like, multiple press-formed titanium plates are stacked and used. Even if the titanium plates can be press-formed without cracks, they will be exposed to minute vibrations generated during use of the product for a long period of time, causing the titanium plates to rub against each other and localized wear. This may shorten the life of the product. From this perspective, there is still room for improvement in the titanium material disclosed in Patent Document 1.

[0007] In light of the above, an object of the present invention is to provide a titanium plate, a processed product, a plate heat exchanger, and a solid polymer water electrolysis apparatus that are suppressed from generating cracks and have excellent lubricity and wear resistance. [Means for solving the problem]

[0008] The present invention has been made to solve the above-mentioned problems, and is summarized as the following titanium plate, processed product, plate heat exchanger, and solid polymer water electrolysis device.

[0009] (1) Using a Raman spectrometer, measurements were taken at 80 points on the surface of the titanium plate so that the spacing between the centers of the spots was 2.5 μm in a predetermined direction, and at 80 points so that the spacing between the centers of the spots was 2.5 μm in a direction perpendicular to the predetermined direction, for a total of 6,400 points. At each measurement point, the area ratios of titanium carbide, nitride or carbonitride, anatase titanium oxide, rutile titanium oxide, and undetected titanium were calculated so that the total was 100%. The average area ratio of the titanium carbide, nitride or carbonitride at all measurement points is 30.0% or more, the average value of the total area ratio of the anatase-type titanium oxide and the rutile-type titanium oxide at all measurement points is 1.0 to 5.0%, When all of the measurement points are divided into 10 equal sections in the predetermined direction and 10 equal sections in a direction perpendicular to the predetermined direction, resulting in a total of 100 sections, the number of sections containing points where the total area ratio of the anatase titanium oxide and the rutile titanium oxide is 20.0% or more is 10 or more. Titanium plate.

[0010] (2) the average value of the area ratio of the anatase type titanium oxide at all the measurement points is greater than the average value of the area ratio of the rutile type titanium oxide at all the measurement points; The titanium plate according to (1) above.

[0011] (3) A processed titanium plate product, Using a Raman spectrometer, measurements were taken at 80 points on the surface of the processed product so that the spacing between the centers of the spots was 2.5 μm in a predetermined direction, and at 80 points so that the spacing between the centers of the spots was 2.5 μm in a direction perpendicular to the predetermined direction, for a total of 6,400 points. At each measurement point, the area ratios of titanium carbide, nitride or carbonitride, anatase titanium oxide, rutile titanium oxide, and undetected titanium were calculated so that the total was 100%. The average area ratio of the titanium carbide, nitride or carbonitride at all measurement points is 30.0% or more, the average value of the total area ratio of the anatase-type titanium oxide and the rutile-type titanium oxide at all measurement points is 1.0 to 5.0%, When all of the measurement points are divided into 10 equal sections in the predetermined direction and 10 equal sections in a direction perpendicular to the predetermined direction, resulting in a total of 100 sections, the number of sections containing points where the total area ratio of the anatase titanium oxide and the rutile titanium oxide is 20.0% or more is 10 or more. Processed titanium plate.

[0012] (4) the average value of the area ratio of the anatase type titanium oxide at all the measurement points is greater than the average value of the area ratio of the rutile type titanium oxide at all the measurement points; A processed titanium plate according to (3) above.

[0013] (5) The processed product according to (3) or (4) above, which is an expanded metal.

[0014] (6) A plate heat exchanger comprising the titanium plate described in (1) or (2) above, or the processed product described in (3) or (4) above.

[0015] (7) A polymer electrolyte water electrolysis device comprising the titanium plate according to (1) or (2) above, or the processed product according to (3) or (4) above. [Effects of the Invention]

[0016] According to the present invention, it is possible to obtain a titanium plate, a processed product, a plate heat exchanger, and a solid polymer water electrolysis apparatus that are suppressed from generating cracks and have excellent lubricity and wear resistance. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram for explaining a method for measuring the composition of the surface of a titanium plate. [Figure 2] FIG. 2 is a schematic diagram for explaining a method for observing cracks. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present inventors have conducted extensive research to obtain a titanium plate or the like that suppresses cracking and has excellent lubricity and wear resistance, and have reached the following findings.

[0019] From the viewpoint of improving the lubricity of titanium plates, it is effective to form a titanium oxide film on the titanium base material. However, because titanium oxide films are hard and brittle, they are prone to fine cracks during press forming, which may reduce lubricity. Therefore, the present inventors investigated a method for suppressing the occurrence of cracks during press forming of titanium plates and ensuring lubricity.

[0020] To improve the lubricity of titanium plates, it is effective to form a coating containing titanium carbide, titanium nitride, or titanium carbonitride in addition to titanium oxide. Research by the present inventors has shown that, compared to titanium oxide coatings formed by atmospheric oxidation, coatings containing titanium carbide, titanium nitride, or titanium carbonitride are inferior in lubricity, but are more susceptible to deformation due to deformation of the titanium base material during press forming, and thus can suppress the occurrence of cracks in the coating. Therefore, the inventors decided to suppress the occurrence of cracks by increasing the area ratio of titanium carbide, titanium nitride, or titanium carbonitride on the surface of the titanium plate. The present inventors then conducted further research into methods for improving the lubricity and ensuring wear resistance of titanium plates with a high area ratio of titanium carbide, titanium nitride, or titanium carbonitride.

[0021] As a result, it was found that finely dispersing anatase-type titanium oxide and / or rutile-type titanium oxide on the surface of a titanium plate is effective in improving lubricity. Thus, the presence of highly lubricious titanium oxide on the surface of a titanium plate reduces contact between titanium carbide, titanium nitride, or titanium carbonitride and the mating material, thereby suppressing wear. Finely dispersed titanium oxide can suppress cracking of the oxide itself, and even if cracking occurs, it can suppress a significant decrease in lubricity and wear resistance.

[0022] The present invention was made based on the above findings. Below, the requirements of the titanium plate, processed product, plate heat exchanger, expanded metal, and solid polymer water electrolysis device of the present invention will be described in detail.

[0023] 1. Titanium plate In the present invention, the thickness of the titanium plate is preferably 0.2 to 2.0 mm, more preferably 0.2 to 1.6 mm, when the titanium plate is used as a processed product such as expanded metal, or when the titanium plate or processed product is used as a plate heat exchanger or solid polymer electrolysis device.

[0024] 2. Titanium base material The type of base material for the titanium plate according to the present invention is not particularly limited, and examples of the base material include commercially pure titanium and titanium alloys.

[0025] Commercially pure titanium is specified by JIS, ASTM, etc., and typically contains 99% or more Ti by mass. Typical impurity elements in commercially pure titanium are C, H, O, N, and Fe. 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 the above elements in the above 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.

[0026] 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 11-13, 17, 19-22, and ASTM Grades 7, 11, 13, 14, 17, 30, and 31, as well as titanium alloys containing small amounts of various other elements), Ti-0.5Cu, Ti-1.0Cu, Ti-1.0Cu-0.5Nb, and Ti-1.0Cu-1.0Sn-0.3Si-0.25Nb. All of these alloys contain 0.08% or less by mass of C, 0.015% or less by mass of H, 0.40% or less by mass of O, and 0.05% or less by mass 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 within 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.

[0027] 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 up to 0.08% by mass of C, 0.015% by mass of H, 0.40% by mass of O, and 0.05% by mass 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 within 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.

[0028] 3. Titanium plate surface composition In the present invention, the composition of the titanium plate surface is measured using a Raman spectrometer. Specifically, measurements are taken at 80 points on the surface of the titanium plate in a predetermined direction so that the spacing between the centers of the spots is 2.5 μm, and at 80 points in a direction perpendicular to the predetermined direction so that the spacing between the centers of the spots is 2.5 μm, for a total of 6,400 points. The measurement method will now be described.

[0029] 1 is a diagram illustrating a method for measuring the composition of a titanium plate surface. (a) is a diagram showing the relationship between a titanium plate 1 and a measurement area 2, (b) is an enlarged view of the measurement area 2, and (c) is an enlarged view of an area A enclosed by a dashed line in (b). In (c), a measurement spot 3 is indicated by a two-dot dashed line, and the center 4 of the spot is indicated by a black dot. In this embodiment, the spot 3 corresponds to the "measurement point."

[0030] In (b), the left-right direction D1 and the up-down direction D2 on the paper are indicated by arrows. The left-right direction D1 and the up-down direction D2 are perpendicular to each other. In this embodiment, the left-right direction D1 corresponds to the "predetermined direction," and the up-down direction D2 corresponds to the "direction perpendicular to the predetermined direction."

[0031] Referring to (a), first, the position and size of the measurement area 2 on the surface of the titanium plate 1 are determined. The measurement area 2 is located on the surface of the titanium plate 1, near the center in the rolling direction of the titanium plate 1, and near the center in the width direction of the titanium plate 1. The size of the measurement area 2 may be 200 μm × 200 μm so that all of the spots 3, which will be described next, are included.

[0032] Next, the composition of the titanium plate surface is measured using a HORIBA LabRAM HR Evolution microscopic laser Raman spectrometer. As shown in (b) and (c), measurements are taken at a total of 6,400 points, starting from spot 3a, with 80 measurement points in the left-right direction D1 and 80 measurement points in the up-down direction D2, to obtain the Raman spectrum for each spot 3. The measurements are taken so that the distance between the centers 4 of each spot is 2.5 μm in both the left-right direction D1 and the up-down direction D2.

[0033] In the example shown in Figure 1, the diameter of spot 3 is 2.5 µm, but the diameter of spot 3 may be adjusted to fall within the range of 2.0 to 3.0 µm. The excitation wavelength is 458 nm, the diffraction grating has 600 lines / mm, and the objective lens magnification is 100x. Measurements were taken for 5 seconds at each measurement point.

[0034] Next, at each measurement point, the area ratios of titanium carbide, nitride, or carbonitride (hereinafter also referred to as "titanium carbide, etc."), anatase-type titanium oxide (hereinafter also referred to as "anatase"), rutile-type titanium oxide (hereinafter also referred to as "rutile"), and undetected particles are calculated so that the total of these ratios equals 100%. The method for calculating the above four area ratios at each measurement point is explained below.

[0035] <Determination of Representative Spectrum> First, reference Raman spectra (hereinafter also referred to as "reference spectra") of titanium carbide, anatase, and rutile are obtained. These reference spectra may be publicly known spectra described in literature. Alternatively, the reference samples may be TiC, TiN, TiCN, anatase, and rutile, and the Raman spectra measured for each may be used as the reference spectra.

[0036] Next, Raman spectra were obtained at a total of 6,400 measurement points using the method described above. From these Raman spectra, those believed to have the highest proportion of titanium carbide, etc., those believed to have the highest proportion of anatase, those believed to have the highest proportion of rutile, and those that were not detected were selected. These were then used as representative spectra for titanium carbide, etc., anatase, rutile, and those that were not detected, respectively.

[0037] The representative spectrum of titanium carbide has a Raman shift of 300 cm -1 Near and 600cm -1 The spectrum with the closest waveform and peak position to the reference spectrum is visually selected based on the peaks around the center of the spectrum. The representative spectrum of anatase has a Raman shift of 141 cm -1 The spectrum that has the closest waveform and peak position to the reference spectrum is visually selected. The representative spectrum of rutile has a Raman shift of 446 cm -1 and 609 cm -1 The representative spectrum that has the closest waveform and peak position to the reference spectrum is selected by visual inspection, characterized by a large peak. The undetected representative spectrum is selected from the 6400 measurement points without a characteristic peak and with a Raman shift of 100 to 2000 cm. -1 For example, select the one with the lowest intensity between 100 and 2000 cm -1 Select the one with a maximum detection intensity of 4 counts / second or less between these. If the reference spectrum of any of titanium carbide, anatase, and rutile is detected at all measurement points, it is treated as if there are no undetected components, and the area ratio, as described below, is calculated.

[0038] The peak positions of the Raman spectrum can vary depending on the surface condition of the sample, the measurement atmosphere, vibrations, etc. Therefore, in calculating the area ratios described below, it is necessary to use a representative spectrum of each substance determined from the measurement sample itself, rather than a reference spectrum. Therefore, the representative spectrum of each substance is determined using the method described above.

[0039] <Calculating area ratio> The representative spectrum of each substance determined by the method described above is used to fit the Raman spectrum measured at a certain measurement point. Then, the ratio of the four representative spectra described above that best fits the measured Raman spectrum is determined using the least squares method. This ratio is determined using Lab Spec 6, the analysis software for HORIBA's LabRAM HR Evolution.

[0040] The ratios of the representative spectra of titanium carbide, etc., anatase, rutile, and undetected materials obtained in this way are used as the area ratios of titanium carbide, etc., anatase, rutile, and undetected materials at that measurement point. This analysis was performed for 6,400 measurement points, and the area ratios of titanium carbide, etc., anatase, rutile, and undetected materials were determined for each measurement point. Note that "undetected" refers to natural oxide films, etc.

[0041] Area ratio of titanium carbide, etc.: 30.0% or more The average value of the area ratio of titanium carbide and the like obtained by the above method at all measurement points is calculated. In the following explanation, the average value of the area ratio at all measurement points is referred to as the "average area ratio." The average area ratio is obtained using Lab Spec 6, an analysis software for LabRAM HR Evolution manufactured by HORIBA.

[0042] If the average area ratio of titanium carbide, etc. is less than 30.0%, the area of ​​the surface of the titanium material that is not covered with titanium carbide, titanium nitride, and / or titanium carbonitride will be large. As a result, sufficient lubricity and wear resistance will not be obtained. Therefore, the average area ratio of titanium carbide, etc. is set to 30.0% or more. The average area ratio of titanium carbide, etc. is preferably 50.0% or more, and more preferably 70.0% or more. Meanwhile, as described below, in the present invention, the average value of the total area ratio of anatase and rutile at all measurement points (hereinafter also referred to as the "total average area ratio") is 1.0 to 5.0%. Therefore, the average area ratio of titanium carbide, etc. will be 99.0% or less.

[0043] Average area ratio of anatase and rutile: 1.0-5.0% If the average area ratio of anatase and rutile combined is less than 1%, lubricity and wear resistance cannot be ensured. On the other hand, if the average area ratio of anatase and rutile combined is more than 5.0%, cracks originating from anatase and / or rutile are likely to occur. Therefore, the average area ratio of anatase and rutile combined is set to 1.0 to 5.0%.

[0044] As long as the average area ratios of anatase and rutile satisfy the requirement of 1.0 to 5.0%, the ratio of the average area ratio of anatase to the average area ratio of rutile is not particularly limited. The average area ratio of anatase may be 0%, and the average area ratio of rutile may be 0%.

[0045] Furthermore, cracks are less likely to occur in anatase than in rutile, and therefore the average area ratio of anatase is preferably greater than the average area ratio of rutile.

[0046] Number of sections containing points where the total area ratio of anatase and rutile is 20.0% or more: 10 or more Referring to Figure 1, the 6,400 spots 3 described above are divided into 10 equal parts in the left-right direction D1 and also in the up-down direction D2. As a result, the 6,400 spots 3 described above are divided into a total of 100 sections. Each section includes 8 spots 3 in the left-right direction D1 and 8 spots 3 in the up-down direction D2, for a total of 64 spots 3. Then, the number of sections including spots 3 where the sum of the area ratio of anatase and the area ratio of rutile is 20.0% or more is counted.

[0047] Even if the total average area ratio of anatase and rutile satisfies the above requirement, if the number of sections containing points with a total area ratio of anatase and rutile of 20.0% or more is less than 10, anatase and / or rutile may aggregate in a few sections, making it more likely that cracks originating from anatase and / or rutile will occur. Furthermore, the lubricity and wear resistance in areas where anatase and / or rutile are absent will be reduced. Therefore, the number of sections containing points with a total average area ratio of anatase or rutile of 20.0% or more should be 10 or more. The number of sections containing points with a total average area ratio of anatase or rutile of 20.0% or more is preferably 15 or more. There is no upper limit to the total average area ratio of anatase and rutile. However, there is a limit to how finely anatase and / or rutile can be industrially dispersed on the surface of a titanium plate while still achieving the effects of the present invention. For example, under the manufacturing conditions described below, the total average area ratio of anatase and rutile will be 80 or less.

[0048] 4.Processed products The titanium plate according to the present invention has excellent lipophilicity and lubricity, and can be used as a processed product after various processing. That is, the processed product is a processed titanium plate. Examples of processing methods include press processing and shear processing. Examples of processed titanium plate products include expanded metal.

[0049] The chemical composition of the surface layer of the processed product satisfies the above-mentioned specifications for the chemical composition of the titanium plate surface layer. Therefore, further explanation will be omitted. However, measurement of the chemical composition of the surface layer of the processed product shall be performed at the location that will come into contact with other parts during use. Furthermore, the titanium plate or a processed titanium plate may be used to make, for example, a plate-type heat exchanger or a solid polymer water electrolysis device.

[0050] 4. Manufacturing method The method for manufacturing the titanium plate of the present invention is not particularly limited. For example, the titanium plate can be stably manufactured by the following manufacturing method. The preparation process, descaling process, cold rolling process, cleaning process, annealing process, and processed product manufacturing process are described below.

[0051] Possible methods for finely dispersing anatase and / or rutile on the surface of a titanium material include (1) performing cold rolling in a descaling step while leaving an appropriate amount of oxide scale; (2) performing cold rolling using cold-rolling oil mixed with an oxygen supply in a cold-rolling step; or (3) performing cleaning using a cleaning agent mixed with an oxygen supply in a cleaning step. Titanium oxide or an oxygen supply is dispersed on the surface of the cold-rolled material before the annealing step. The titanium oxide is then converted to anatase or rutile by the annealing step. As a result, anatase and / or rutile can be finely dispersed on the surface of the titanium material. Therefore, it is necessary to perform any one of steps (1) to (3). In particular, in the present invention, the cold-rolling step is highly effective in dispersing fine titanium oxide, so it is preferable to perform step (1) and / or step (2). When the amount of the oxygen supply attached to the surface is to be increased, the above step (3) may be carried out as necessary after step (1) and / or step (2).

[0052] 4-1. Preparation process 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 electron beam melting, arc melting, or the like, and then hot forged to form the material for hot rolling. Alternatively, the hot forging may be omitted and the ingot may be used as the material for hot rolling.

[0053] The above-mentioned hot rolling material is hot rolled to produce a hot rolled sheet. The conditions for hot rolling are not particularly limited. They may be appropriately adjusted depending on the desired properties. The obtained hot rolled sheet may be appropriately heat treated.

[0054] 4-2. Scale removal process 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 and / or mechanical grinding using a coil grinder or the like.

[0055] When titanium oxide is dispersed in the descaling step, the oxide scale is appropriately left on the surface of the hot-rolled steel sheet by a method described below. The oxide scale is then finely broken down by cold rolling, allowing titanium oxide to be finely dispersed on the surface of the titanium material.

[0056] The method for appropriately retaining oxide scale is not particularly limited. For example, oxide scale can be appropriately retained on the surface by adjusting the type of shot blasting material, the impact speed of the shot blasting material (projection speed), the amount of shot blasting material (projection amount), the size of the coil grinder, the pressing force, the number of grinding passes (number of passes), or the pickling conditions (concentration, temperature, time, number of passes). For example, the area ratio of the scale remaining on the surface (hereinafter also referred to as "scale area ratio") is 5 to 50%. The scale area ratio is preferably measured by the method described below and used as a control index in manufacturing. By subjecting this to cold rolling, titanium oxide can be more finely dispersed on the surface of the titanium material.

[0057] The scale area ratio is measured as follows: A 1.5 mm x 1.5 mm field of view on the surface of the titanium material is observed using a scanning electron microscope (SEM), and the resulting backscattered electron image is photographed and binarized. The black areas are then determined to be oxide scale, and the area ratio of the black areas to the area of ​​the observed field is calculated. The area ratio of oxide scale is calculated for five separate fields of view, and the average value is taken as the scale area ratio.

[0058] 4-3.Cold rolling process In the cold rolling process, after removing the scale, the hot-rolled sheet is cold-rolled to produce a cold-rolled sheet. In the cold rolling process, cold-rolling oil containing C is used. This allows C to adhere or concentrate on the surface of the cold-rolled sheet, and the average area ratio of titanium carbide, etc. in the titanium sheet can be made 30.0% or more.

[0059] In the method for manufacturing a titanium sheet of the present invention, 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 in the solid solution in the surface layer of the cold-rolled sheet. Note that commercially available cold-rolling oils can be used.

[0060] Cold rolling is usually performed using a Sendzimir mill. In a Sendzimir mill, a titanium plate is rolled by passing it back and forth between a pair of work rolls multiple times. Passing a titanium plate through the work rolls of a rolling mill is called a pass. Therefore, in cold rolling, the plate is usually controlled to the target thickness through multiple passes. In other words, the cold rolling process is a process that involves multiple passes. If the desired amount of C can be deposited or concentrated on the surface of the cold-rolled plate, cold rolling may also be performed using a tandem mill consisting of multiple rolling stands.

[0061] In the production of the titanium plate of the present invention, the average reduction in the cold rolling step is not particularly limited, but it is preferably 5.0 to 19.0%. By setting the average reduction to 5.0 to 19.0%, it is possible to promote the mechanochemical reaction while suppressing the occurrence of surface defects. The average reduction is more preferably greater than 5.0%, and even more preferably greater than 7.0%. Furthermore, the average reduction is more preferably less than 19.0%, and even more preferably less than 17.0%. The higher the average reduction, the more likely the remaining scale is to be broken down into smaller pieces, which may result in scale peeling. Taking this into consideration, it is preferable to adjust the production conditions based on both the scale area ratio and the average reduction.

[0062] The above-mentioned average rolling reduction is the average value of the rolling reductions of the individual passes obtained by the following formula (ii). Reduction rate (%)=(h1-h2) / h1×100 (ii) However, the symbols in the above formula (ii) are defined as follows: h1 (mm): thickness of titanium plate before passing h2 (mm): thickness of titanium plate after passing

[0063] When titanium oxide is dispersed in the cold rolling process, cold rolling is performed under the same conditions as those for the cold rolling process described above, except that an oxygen supply powder is mixed with the cold rolling oil. The type of oxygen supply is not particularly limited. For example, the oxygen supply may be TiO2 powder. Alternatively, the oxygen supply may be a compound of O and a metal that does not dissolve in titanium during annealing, such as MgO or Mg(OH)2. This allows TiO2, MgO, Mg(OH)2, etc. to be dispersed on the surface of the cold-rolled material. Then, in the annealing process described below, O in the oxygen supply combines with Ti in the base material to form titanium oxide. In this way, anatase and / or rutile can be more finely dispersed on the surface of the titanium material.

[0064] The amount of oxygen supply mixed with the cold rolling oil is not particularly limited. By adjusting the amount of oxygen supply mixed as appropriate depending on the number of cold rolling passes, speed, etc., or the types of cold rolling oil and oxygen supply, the dispersion state of anatase and / or rutile on the titanium plate surface can be adjusted.

[0065] 4-4. Cleaning process In the washing step, after cold rolling, the cold-rolled oil adhering to the surface of the cold-rolled sheet is washed away. The conditions for the washing step are not particularly limited. For example, washing is performed using an alkaline detergent and pure water, followed by drying with a dryer. The type of alkaline detergent is not particularly limited. For example, it is preferable to use an alkaline detergent containing NaOH and KOH (Pakuna DST-58-L manufactured by Yuken Kogyo Co., Ltd.). The concentration of the alkaline detergent is also not particularly limited. For example, it may be 2.5 to 5.0 vol%.

[0066] When titanium oxide is dispersed in the cleaning process as needed, cleaning is performed under the same conditions as in the cleaning process described above, except that an oxygen supply is mixed with the alkaline cleaning agent. The oxygen supply may be, for example, TiO2, MgO, or Mg(OH)2. Titanium oxide and the oxygen supply are finely dispersed on the surface of the cold-rolled sheet by the time of the cold-rolling process in 4-3. By performing cleaning using a cleaning agent containing the oxygen supply, the oxygen supply is further added and dispersed and adhered to the surface of the cold-rolled sheet. Then, in the annealing process described below, O in the oxygen supply combines with Ti in the base material to form titanium oxide. In this way, anatase and / or rutile can be more finely dispersed on the surface of the titanium material.

[0067] After cleaning, the surface layer is not removed by pickling, grinding, or other methods, because these methods remove the titanium oxides and oxygen sources dispersed on the surface of the cold-rolled sheet during the cold rolling process, as well as the adhering and concentrated carbon.

[0068] 4-5. Annealing process In the annealing process, the cold-rolled sheet after the cleaning process is annealed to obtain a titanium sheet. The annealing conditions are not particularly limited. For example, the sheet is heated and annealed in an Ar or nitrogen atmosphere. Annealing is preferably performed in a nitrogen atmosphere. This allows the titanium oxide dispersed on the surface of the titanium material to react with the Ti matrix, and the oxygen contained in the oxygen supply reacts with and bonds with the Ti matrix to form titanium oxide. As a result, the titanium oxide becomes anatase or rutile. Furthermore, by setting the average area ratio of titanium carbides, etc. to 30.0% or more, the occurrence of cracks in the titanium sheet can be suppressed.

[0069] An example of annealing conditions is, for example, an Ar or nitrogen atmosphere in a continuous annealing furnace, with a dew point of -50 to -30°C, an annealing temperature of 700 to 900°C, and an annealing time of 0.1 to 60 seconds. Setting the annealing temperature to 900°C or less and the annealing time to 60 seconds or less can prevent the reduction of titanium carbide and titanium oxide on the surface of the titanium sheet due to the diffusion of O and C into the interior of the titanium sheet. Setting the dew point to -30°C or less can also prevent excessive oxidation from causing excessive titanium oxide. The annealing temperature is preferably 880°C or less. After the annealing process, the shape of the titanium sheet may be cold-corrected as needed.

[0070] 4-6. Processed product manufacturing process In the processed product manufacturing process, the titanium plate 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. In addition, products such as plate-type heat exchangers and solid polymer water electrolysis devices may be manufactured using the titanium plate or processed product.

[0071] The titanium plate according to the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Example]

[0072] The types of titanium material 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, and "JIS Class 2" refers to Class 2 commercially pure titanium as specified in JIS H 4600:2012.

[0073] These titanium materials were subjected to cold rolling, washing, and annealing under the conditions shown in Table 1 to obtain titanium plates with the thicknesses shown in Table 1. In Table 1, "anodic oxidation" means that the anodization was carried out in an aqueous solution with a pH of 5 mass% phosphoric acid at an applied voltage of 50 V.

[0074] The "scale area ratio" in Table 1 was calculated using the method described above. The "shot blasting" in Table 1 was performed using iron shot with a particle size of 100 to 300 μm and a projection speed of 30 to 80 m / s. By performing pickling with nitric hydrofluoric acid after such shot blasting, cracks are introduced into the oxide scale by the shot blasting, and the nitric hydrofluoric acid penetrates through these cracks, dissolving the oxide scale. As a result, the scale area ratio can be adjusted.

[0075] [Table 1]

[0076] The composition of the titanium plate surface was measured for each of the titanium plates obtained as described above using the method described above. The measurement area for the titanium plate surface composition was a 200 μm × 200 μm area centered on the center 16 of the test piece 10 shown in Figure 2(b) described below. The lubricity, wear resistance, and cracking of each titanium plate were also evaluated using the following methods.

[0077] <Lubricity> Lubricity was evaluated by the initial coefficient of friction. The initial coefficient of friction was measured using the following method. A pin-on-disk friction and wear tester was used to perform a friction and wear test without lubrication by sliding a pin across the surface of the titanium plate. The test was performed under the following conditions: surface pressure 6.2 MPa, speed 100 mm / s, and sliding distance 20 mm. The friction coefficient was calculated from the 0th to 50th sliding cycle, and the average value was used as the initial coefficient of friction.

[0078] The pins used in the test were 1 mm in diameter and made of SKD11, as specified in the Japanese Industrial Standard JIS G 4404:2015. SKD11 is an alloy tool steel, commonly known as die steel, used for press molding dies. An initial friction coefficient of 0.15 or less, measured in this way, is considered to be acceptable. The initial friction coefficients are shown in Table 2 as evaluation results for "lubricity." The conditions of a surface pressure of 6.2 MPa and up to 50 sliding cycles are intended to simulate severe machining.

[0079] <Wear resistance> Wear resistance was evaluated using the following method. A pin-on-disk friction and wear tester was used to perform the friction and wear test without lubrication, sliding the pin across the surface of the titanium plate. The test was performed using a 1mm diameter pin made of SKD11 as specified in Japanese Industrial Standard JIS G 4404:2015, with a surface pressure of 6.2MPa, a speed of 100mm / s, and a sliding distance of 20mm.

[0080] The average coefficient of friction was then calculated for every 10 slides, and the first number of slides at which the average coefficient of friction reached 0.25 or greater was determined. A test result of 300 slides or greater was deemed to have passed. Table 2 shows the number of slides as the evaluation result for "wear resistance." Note that the condition of 300 slides or greater simulates an environment in which the test piece is exposed to minute vibrations for an extended period of time. The surface pressure of 6.2 MPa was also set to be more severe than the usual test conditions.

[0081] Furthermore, in the above-mentioned evaluation of wear resistance, the type of pin was changed to a pin made of commercially pure titanium type 1 with a diameter of 1 mm, but the test was conducted without changing any other conditions. Furthermore, a pin made of commercially pure titanium type 1 was used, assuming that titanium plates would slide against each other in the usage environment. The number of sliding movements in this case is also shown in Table 2 as an evaluation result of "wear resistance."

[0082] <Crack> 2 is a schematic diagram illustrating a method for observing cracks. (a) is a front view of test piece 10, (b) is a bottom view of test piece 10, and (c) is a front view of test piece 10 after bending. As shown in (a) and (b), the dimensions of test piece 10 were 30 mm in width and 150 mm in length. As shown in FIG. 2, test piece 10 was bent from the flat state shown in (a) and (b) into a U-shape, simulating press forming, as shown in (c).

[0083] Referring to (c), the U-bending process was performed with an R / t value of 15 to ensure that the deformation amount on one surface 12 of the test piece 10, which becomes the outer surface due to the U-bending process, was approximately the same for each test. Here, R is the radius of the semicircle centered at the center point P, and t is the plate thickness. A bending jig having a shape that would result in an R / t value of 15 was selected, and the above-mentioned bending process was performed. After that, the bending process was reversed, and the test piece was returned to the flat surface shown in (a) and (b). Then, during the U-bending process, the presence or absence of cracks was observed on the one surface 12 of the test piece 10, at the center 14 in the circumferential direction of the semicircle centered at point P.

[0084] Specifically, the presence or absence of cracks was observed by the following method: The surface was observed using an SEM at a magnification of 200x at the center 14 in the length direction of one surface 12 of the test piece 10 and the center 16 in the width direction.

[0085] If the maximum crack length was less than 50 μm, the specimen was judged as passing and marked with "A" in Table 2. If the maximum crack length was 50 μm or more, the specimen was judged as failing and marked with "B" in Table 2.

[0086] <Evaluation of lubrication and wear resistance after bending> Assuming the product after press forming, the test specimens shown in Table 2 were subjected to the U-bending process shown in Figure 2(c) as described above, and then returned to the state shown in Figures 2(a) and (b). The compound composition, lubricity, wear resistance, and cracks on the surface of the test specimens were evaluated. For the evaluation of lubricity and wear resistance, friction and wear tests were performed by sliding the center of the test specimen along the dashed line shown in Figure 2(b). The dashed line shown in Figure 2(b) is a line extending from the center 14 in (c) in the sheet width direction. These results are shown in Table 3.

[0087] The results are summarized in Tables 2 and 3. Table 2 shows the results for the as-flat plate, and Table 3 shows the results for the surface after bending. In the remarks columns of Tables 2 and 3, examples in which the initial friction coefficient was greater than 0.12 and 0.15 or less were designated Example 1, and examples in which the initial friction coefficient was 0.12 or less were designated Example 2.

[0088] [Table 2]

[0089] [Table 3]

[0090] In the examples of Test Nos. 1 to 6 and 14 to 32, the preferred manufacturing conditions were met, and therefore the requirements of the present invention were satisfied, resulting in good lubricity and wear resistance. Furthermore, the occurrence of cracks was also suppressed. On the other hand, in the comparative examples of Test Nos. 7 to 13, the preferred manufacturing conditions of the present invention were not met, and therefore the requirements of the present invention were not satisfied, and good lubricity and wear resistance could not be obtained.

[0091] In Tests No. 7 and 8, a large amount of scale was left on the surface of the titanium plate during the descaling process. As a result, the total area ratio of anatase and rutile was high, and good lubricity and wear resistance were not achieved. Furthermore, cracks also occurred on the surface. In Test No. 9, the process of leaving scale and the process of dispersing oxygen-supply materials on the surface of the titanium plate were not carried out, and the plate was pickled with nitric hydrofluoric acid during the cleaning process. This removed the carbon that had adhered to and concentrated on the surface of the titanium plate during the cold rolling process. Furthermore, the annealing process was carried out in a nitrogen atmosphere, resulting in the formation of excessive titanium nitride or titanium carbonitride. As a result, the total area ratio of anatase and rutile was low, the number of divisions was small, and good lubricity and wear resistance were not achieved.

[0092] In Test No. 10, the process of leaving scale and the process of dispersing oxygen supply on the surface of the titanium plate were not carried out. As a result, the total area ratio of anatase and rutile was low, the number of divisions was small, and good lubricity and wear resistance were not obtained. In Test No. 11, annealing was carried out in a vacuum atmosphere, so sufficient anatase and rutile could not be formed on the surface, and good lubricity and wear resistance were not obtained.

[0093] In Test No. 12, the test piece was pickled with nitric hydrofluoric acid, which resulted in the formation of a natural oxide film. As a result, the total area ratio of anatase and rutile was low, the number of divisions was small, and good lubricity and wear resistance were not obtained. In Test No. 13, the test piece was pickled with nitric hydrofluoric acid and then anodized. As a result, the total area ratio of anatase and rutile was 100%, and good lubricity and wear resistance were not obtained. [Industrial Applicability]

[0094] According to the present invention, it is possible to obtain a titanium plate, a processed product, a plate heat exchanger, and a solid polymer water electrolysis apparatus that are suppressed from generating cracks and have excellent lubricity and wear resistance. [Explanation of symbols]

[0095] 1 titanium plate 2 Measurement area 3 Spot 4. Center of the spot 10 test specimens 12 One side 14 Center in the longitudinal direction 16 Center in width direction

Claims

1. Using a Raman spectrometer, measurements were taken at 80 points on the surface of the titanium plate so that the spacing between the centers of the spots was 2.5 μm in a predetermined direction, and at 80 points so that the spacing between the centers of the spots was 2.5 μm in a direction perpendicular to the predetermined direction, for a total of 6,400 points. At each measurement point, the area ratios of titanium carbide, nitride or carbonitride, anatase titanium oxide, rutile titanium oxide, and undetected titanium were calculated so that the total was 100%. the average value of the area ratio of the titanium carbide, nitride or carbonitride at all measurement points is 30.0% or more; the average value of the total area ratio of the anatase titanium oxide and the rutile titanium oxide at all measurement points is 1.0 to 5.0%, when all of the measurement points are divided into 10 equal sections in the predetermined direction and 10 equal sections in a direction perpendicular to the predetermined direction, resulting in a total of 100 sections, the number of sections containing points where the total area ratio of the anatase type titanium oxide and the rutile type titanium oxide is 20.0% or more is 10 or more; Titanium plate.

2. the average value of the area ratio of the anatase titanium oxide at all measurement points is greater than the average value of the area ratio of the rutile titanium oxide at all measurement points; The titanium plate according to claim 1.

3. A processed product of titanium plate, Using a Raman spectrometer, measurements are taken at 80 points on the surface of the processed product so that the spacing between the centers of the spots is 2.5 μm in a predetermined direction, and at 80 points so that the spacing between the centers of the spots is 2.5 μm in a direction perpendicular to the predetermined direction, for a total of 6,400 points. At each measurement point, the area ratios of titanium carbide, nitride or carbonitride, anatase titanium oxide, rutile titanium oxide, and undetected titanium were calculated so that the total was 100%. the average value of the area ratio of the titanium carbide, nitride or carbonitride at all measurement points is 30.0% or more; the average value of the total area ratio of the anatase titanium oxide and the rutile titanium oxide at all measurement points is 1.0 to 5.0%, when all of the measurement points are divided into 10 equal sections in the predetermined direction and 10 equal sections in a direction perpendicular to the predetermined direction, resulting in a total of 100 sections, the number of sections containing points where the total area ratio of the anatase type titanium oxide and the rutile type titanium oxide is 20.0% or more is 10 or more; Titanium plate processed products.

4. the average value of the area ratio of the anatase titanium oxide at all measurement points is greater than the average value of the area ratio of the rutile titanium oxide at all measurement points; A processed product of the titanium plate according to claim 3.

5. 5. The processed product according to claim 3 or 4, which is an expanded metal.

6. A plate heat exchanger comprising the titanium plate according to claim 1 or 2, or the processed product according to claim 3 or 4.

7. A solid polymer water electrolysis device comprising the titanium plate according to claim 1 or 2, or the processed product according to claim 3 or 4.

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