Inspection method and manufacturing method of sheet-shaped titanium porous material, inspection program, and computer-readable storage medium on which inspection program is recorded

Abstract

To provide an efficient inspection method and manufacturing method of a sheet-shaped titanium porous material.SOLUTION: An inspection method of the present invention includes: acquiring a reflected electron image and a secondary electron image of a sheet-shaped titanium porous material; binarizing the reflected electron image and the secondary electron image according to gradation; respectively extracting a first specific region and a second specific region; and acquiring an intersection region common to the first specific region and the second specific region. This inspection method may further include performing opening processing on the intersection region.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] One embodiment of the present invention relates to an inspection method and a manufacturing method for a sheet-shaped porous titanium body, and an inspection program for the inspection method and the manufacturing method. [Background technology]

[0002] Titanium porous bodies have high liquid permeability, air permeability, electrical conductivity, and excellent corrosion resistance, and are therefore used as electrode materials and filters that can be used in highly corrosive environments. In particular, titanium porous bodies in sheet form with a thickness of several tens of μm to several hundreds of μm are useful as porous transport layers (PTLs) in polymer electrolyte membrane (PEM)-type water electrolysis devices. Titanium porous bodies in sheet form can be produced, for example, by a dry method or a paste method (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-97450 A [Patent Document 2] JP 2023-111138 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment of the present invention is to provide an efficient inspection method and manufacturing method for a porous titanium sheet. Alternatively, an object of one embodiment of the present invention is to provide an inspection program for executing the efficient inspection method and manufacturing method for a porous titanium sheet, and a storage medium on which this inspection program is stored. [Means for solving the problem]

[0005] One embodiment of the present invention is a method for inspecting a sheet-shaped porous titanium body, which includes obtaining a backscattered electron image and a secondary electron image of the sheet-shaped porous titanium body, binarizing the backscattered electron image and the secondary electron image according to gradation, extracting a first specific region and a second specific region, respectively, and obtaining an intersection region common to the first specific region and the second specific region.

[0006] One embodiment of the present invention is a method for producing a sheet-shaped porous titanium body, including the above-mentioned inspection method. Specifically, this method includes obtaining a backscattered electron image and a secondary electron image of the sheet-shaped porous titanium body, binarizing the backscattered electron image and the secondary electron image according to gradation, respectively extracting a first specific region and a second specific region, and obtaining an intersection region common to the first specific region and the second specific region. This method may further include preparing a sheet-shaped porous titanium body by sintering the titanium fine particles, or drying and debinding a paste containing titanium fine particles, a binder, and a solvent, and then sintering the paste.

[0007] One embodiment of the present invention is a test program configured to cause a computing device to execute the test method. Also, one embodiment of the present invention is a computer-readable storage medium having the test program recorded thereon. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic top view of a sheet-shaped porous titanium body. [Diagram 2] 4 is a flowchart of an inspection method according to an embodiment of the present invention. [Diagram 3] 4 is a flowchart of an inspection method according to an embodiment of the present invention. [Figure 4] 5A to 5C are schematic diagrams illustrating tone correction in an inspection method according to an embodiment of the present invention. [Diagram 5] 5A to 5C are schematic diagrams illustrating a method for extracting and acquiring a specific area and an intersection area in an inspection method according to an embodiment of the present invention. [Figure 6] 5A to 5C are schematic diagrams illustrating an opening process in an inspection method according to an embodiment of the present invention. [Figure 7] 1A to 1C are schematic diagrams illustrating a sorting process in an inspection method according to an embodiment of the present invention. [Figure 8] A secondary electron image (A) and a backscattered electron image (B) of a sheet-shaped porous titanium body obtained in an example. [Figure 9] 1A is an image showing a specific region Xs (A) extracted from a corrected secondary electron image I's of a sheet-shaped titanium porous body in an embodiment, a specific region Xb (B) extracted from a corrected backscattered electron image I'b, and an intersection region Xc (C) between them. [Figure 10] 13 is an image after opening processing in an embodiment. [Figure 11] Binarization results of electron images of a sheet-shaped porous titanium body in a comparative example. (A) Extraction result of the region of 250 gradations or more in the secondary electron image, (B) Extraction result of the region of 120 to 145 gradations in the secondary electron image, (C) Extraction result of the region of 30 to 90 gradations in the backscattered electron image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The inspection method for a sheet-shaped porous titanium body (hereinafter, also simply referred to as the present inspection method) and the manufacturing method thereof according to the embodiment of the present invention will be described below with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the gist of the invention, and should not be construed as being limited to the description of the embodiment exemplified below.

[0010] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same functions as those explained in the previous drawings may be given the same reference numerals, and duplicate explanations may be omitted.

[0011] 1. Sheet-shaped porous titanium The subject of inspection in this inspection method is a sheet-shaped porous titanium body having a sponge-like three-dimensional network structure. There are no restrictions on the planar shape of the sheet-shaped porous titanium body, and for example, as shown in Figure 1, a sheet-shaped porous titanium body 100 having a rectangular planar shape can be used. The thickness of the sheet-shaped porous titanium body 100 can also be determined arbitrarily, and the thickness can be selected from the range of, for example, 20 μm to 3000 μm, or 20 μm to 1000 μm, or 40 μm to 500 μm.

[0012] The sheet-shaped titanium porous body 100 used in this inspection method may be prepared by appropriately applying a known method. Specifically, for example, titanium fine particles having a purity of 99% or more are deposited on a setter, then scraped into a sheet shape, and then heated and sintered at a high temperature (for example, 950°C or higher), to obtain the sheet-shaped titanium porous body 100. At this time, in order to facilitate separation from the setter, it is preferable to apply a release agent such as boron nitride or titanium boride to the setter and deposit the titanium fine particles on it. The shape of the titanium fine particles may be spherical, but by using a shape that deviates from a sphere, for example, titanium fine particles (HDH powder) produced by a hydrogenation-dehydrogenation method, the number of junctions between the titanium fine particles increases. As a result, a sheet-shaped titanium porous body having a large number of pores inside, that is, a sponge-like three-dimensional network structure, can be obtained. This preparation method is a so-called dry method.

[0013] Alternatively, the sheet-shaped titanium porous body 100 may be prepared by preparing a paste containing titanium fine particles, a binder, and a solvent, applying the paste to form a sheet-shaped precursor, and then undergoing the steps of drying, binder removal, and sintering. When the paste does not contain water and a foaming agent, the surface smoothness of the sheet-shaped titanium porous body 100 produced tends to be excellent. Even with the paste method, the sheet-shaped titanium porous body 100 having a sponge-like three-dimensional network structure can be obtained. Examples of the binder include cellulose, polyvinyl alcohol, acrylic resin, and polyvinyl butyral resin. Examples of the solvent include alcohols such as ethanol and isopropanol, aromatic solvents such as toluene and xylene, hydrocarbons such as cyclohexane, and ketones such as methyl ethyl ketone. The paste is applied onto a substrate, and the solvent is distilled off at room temperature or under heating conditions (for example, 80°C to 160°C) to obtain a sheet-shaped green body. After the binder is removed from the green body, the sheet-shaped titanium porous body 100 can be obtained by sintering at a high temperature of about 750°C to 1100°C. This preparation method is, so to speak, a paste method.

[0014] The sheet-shaped porous titanium body 100 can also be manufactured by using titanium fibers as the raw material instead of the titanium fine particles. In this case, a sheet-shaped porous titanium body 100 having a nonwoven fabric-like three-dimensional network structure is obtained.

[0015] As shown in the enlarged view of FIG. 1, in the sheet-shaped porous titanium body 100, titanium particles 102 are bonded to each other to form a three-dimensional network structure, which generates a large number of pores. However, the sheet-shaped porous titanium body 100 is not necessarily composed of only titanium particles 102, and a small amount of foreign matter 104 may be mixed in as an impurity. Examples of the foreign matter 104 include components other than titanium contained in the release agent or setter, abrasives used in cutting the sheet-shaped porous titanium body 100, and dust contained in the air. As described in detail below, this inspection method efficiently detects these foreign matters 104. Therefore, by applying this inspection method, it is possible to provide and select a sheet-shaped porous titanium body 100 that does not contain foreign matter 104 or in which the inclusion of foreign matter 104 is significantly suppressed at low cost.

[0016] 2. Testing Method The flow charts of this inspection method are shown in Figures 2 and 3. This inspection method uses both secondary electron images and backscattered electron images of the sheet-shaped porous titanium body obtained using a scanning electron microscope. By appropriately processing these electron images, it becomes possible to distinguish between foreign matter and the porous titanium body and to almost selectively detect foreign matter.

[0017] (1) Acquiring an electron image As shown in the flow chart of FIG. 2, first, a reflected electron image Ib and a secondary electron image Is of the sheet-shaped porous titanium body are obtained. The reflected electron image Ib and the secondary electron image Is are obtained for the same region of the sheet-shaped porous titanium body. These electron images are composed of a plurality of data points arranged in a matrix, and each data point contains grayscale data ranging from 0th grayscale to 255th grayscale. When the electron image is reproduced on a display device, the data points correspond to pixels, and the grayscale corresponds to the brightness of the pixels. Therefore, grayscale and brightness are synonymous.

[0018] As described later, since the electronic image is binarized according to the gradation of the data points, there is a risk that accurate foreign matter detection will not be possible if the brightness, i.e., the average gradation, differs between the electronic images due to the conditions when the electronic images were acquired. Therefore, gradation correction may be performed on each of the backscattered electron image Ib and the secondary electron image Is before binarization. Specifically, the gradation G of each data point when the electronic images were acquired is 0 According to the following formula (1), the gradation G 1 Convert to.

number

[0019] In tone correction, as shown in the flowchart in Figure 2, after acquiring a backscattered electron image Ib, the average tone G aveThe standard deviation SD of the gradation is calculated and the gradation correction is performed according to the above formula. After that, a new backscattered electron image (corrected backscattered electron image I'b) is generated using the gradation of each data point obtained by the gradation correction. Similarly, the secondary electron image I S After obtaining the average gradation G ave The standard deviation SD of the gradation is calculated, and the gradation correction is performed according to the above formula. A new backscattered electron image (corrected backscattered electron image I's) is generated using the gradation of each data point obtained. Note that in the flowchart of Figure 2, the secondary electron image I's is generated after the gradation correction of the backscattered electron image Ib. S These tone corrections are performed in random order. S In parallel with the gradation correction of the secondary electron image I S After the gradation correction of the reflected electron image Ib, the gradation correction of the reflected electron image Ic may be performed.

[0020] (2) Extracting specific regions and obtaining intersection regions Next, the corrected backscattered electron image I'b and the corrected secondary electron image I's are binarized according to the gradation, and the specific region Xb and the specific region Xs are extracted, respectively. In the backscattered electron image Ib and the corrected backscattered electron image I'b, the titanium particles that form the skeleton of the titanium porous body are expressed as relatively high gradations. On the other hand, the pores and the shadows of the titanium particles are expressed as relatively low gradations, and the foreign matter, depending on how it is photographed, has a gradation that is about the same as or slightly higher than that of the pores and the shadows of the titanium particles, but is lower than that of the titanium particles. For this reason, a region that has a higher gradation than that of the pores and the shadows of the titanium particles and a lower gradation than that of the titanium particles is extracted as the specific region Xb from the corrected backscattered electron image I'b. Specifically, a region that is composed of data points whose gradation is within a certain range (extracted gradation range) is extracted as the specific region Xb from the corrected backscattered electron image I'b. The range of extracted gradations may be appropriately determined according to the shadows of pores and titanium fine particles in the corrected reflected electron image I'b and the gradations of the titanium fine particles, for example, from 0 gradation to 120 gradations, from 10 gradation to 100 gradations, or from 20 gradation to 70 gradations. This makes it possible to extract a specific region Xb including a region caused by foreign matter (FIG. 5(A)).

[0021] In the secondary electron image Is and the corrected secondary electron image I's, the titanium particles are also represented as relatively high gradations, while the pores and shadows of the titanium particles are represented as low gradations. However, depending on the type of foreign matter, it may show very high gradations or relatively low gradations. In the former case, the gradations of the foreign matter are considerably higher than those of the titanium particles. On the other hand, in the latter case, the gradations of the foreign matter are not significantly different from those of the titanium particles. In addition, the vicinity of the boundary between the titanium particle and the pores and the vicinity of the boundary between the titanium particles themselves may also have relatively high gradations. For this reason, in the corrected secondary electron image I's, the pores and shadows are excluded, and a specific region Xs is extracted so as to include the titanium particles and the foreign matter. Therefore, in the binarization, a region consisting of data points equal to or greater than a certain threshold (extraction gradation threshold) is extracted as the specific region Xs (Figure 5(B)). The extraction gradation threshold value may also be appropriately determined depending on the pores and shadows of titanium microparticles in the corrected secondary electron image I's, and the gradation of the titanium microparticles. For example, it may be selected from the range of 40 to 80 gradations, which is the average gradation of titanium microparticles.

[0022] 2, the specific region Xs is extracted after the specific region Xb is extracted, but the specific region Xb may be extracted after the specific region Xs is extracted. Also, the specific region Xb and the specific region Xs may be extracted after the corrected reflected electron image I'b and the corrected secondary electron image I's are acquired.

[0023] As described above, the specific region Xb is extracted to include foreign matter and, in some cases, pores and the shadows of titanium particles, while the specific region Xs is extracted to include not only foreign matter but also titanium particles. Therefore, data points common to both the specific region Xb and the specific region Xs mainly constitute foreign matter. Therefore, data points common to both the specific region Xb and the specific region Xs are selected, and the intersection region Xc constituted by these data points is obtained (Figure 5(C)). This operation makes it possible to selectively detect foreign matter. If there is no foreign matter at all, the specific region Xb does not exist, and therefore the intersection region Xc may not exist either.

[0024] (3) Opening process However, the intersection region Xc does not always represent only foreign matter, and may contain noise other than foreign matter. For example, as shown in FIG. 6, the vicinity of the boundary between a low-gradation pore and a high-gradation titanium particle, or the vicinity of the boundary between joined titanium particles, may be obtained as the intersection region Xc (thick line part in FIG. 6). Most of the noise in the intersection region Xc does not give a closed shape, but constitutes a part of the intersection region Xc as a relatively thin curve. Even if the noise forms a closed shape, the intersection region Xc often does not exist inside the closed shape. When such noise is included in a large amount, an opening process may be performed on the intersection region Xc to remove the noise. The opening process is a type of image processing, and is a process in which a contraction process is performed once or multiple times, followed by an expansion process the same number of times. This removes noise such as thin lines, and the intersection region Xc can be detected as a foreign matter (FIG. 6).

[0025] (4) Sorting process Although the above process can detect foreign matter, false detection may occur. Such intersection regions Xc caused by false detection often occur in places where foreign matter does not exist, such as near the boundary between titanium particles, near the boundary between a titanium particle and a pore, or near the outline of a titanium particle. Furthermore, the intersection regions Xc detected falsely are often smaller in area or have a relatively low gradation compared to intersection regions Xc normally detected as foreign matter. In this inspection method, such characteristics may be utilized to perform a sorting process to improve detection accuracy (FIG. 2). FIG. 3 is a flowchart of an example of the sorting process, and as shown in this figure, intersection regions Xc having a certain area (rejection area threshold A) or more are determined to be regions normally detected as foreign matter. The rejection area threshold A may be determined, for example, in the range of 0.005% to 0.100% of the total number of data points constituting the corrected secondary electron image I's or the corrected backscattered electron image I'b.

[0026] Furthermore, for intersection regions Xc that are below the exclusion area threshold A, regions in which the gradation of the intersection region Xc is equal to or greater than the exclusion gradation threshold may be determined as foreign matter regions. As an example, only intersection regions Xc in which the average gradation of a region corresponding to the intersection region Xc using the corrected secondary electron image I's is equal to or greater than a certain threshold (exclusion gradation threshold B) are determined as regions that have been correctly detected as foreign matter. The exclusion gradation threshold B in this case may also be determined arbitrarily, and as an example, the above-mentioned standard deviation constant C SD and the average constant C ave The sum of the standard deviation constant C may be used as the rejection gradation threshold B. This makes it possible to reliably detect foreign matter that is small in area but has a high gradation, especially an area that is clearly identified as a foreign matter on the secondary electron image Is. Therefore, the rejection gradation threshold B is set to the sum of the standard deviation constant C SD and the average constant C ave The value is not limited to the sum of the above, but may be set to a value greater than this.

[0027] Regions whose area is below the exclusion area threshold A and whose average gradation is below the exclusion gradation threshold B are determined to be erroneously detected regions and are excluded. This sorting process can significantly eliminate erroneous detections and improve detection accuracy (see FIG. 7). If necessary, the intersection regions Xc after the sorting process can be visually observed to eliminate intersection regions Xc due to erroneous detections that could not be completely eliminated by the sorting process, and a verification process can be performed to identify the actual foreign matter that has been mixed in.

[0028] Conventionally, detection of foreign matter mixed in a sheet-shaped porous titanium body has been performed by visually observing a secondary electron image. For this reason, it takes a long time to process one secondary electron image, and high skill is required of the operator. In contrast, in the present inspection method, foreign matter can be detected in an extremely short time by processing a secondary electron image and a backscattered electron image obtained by an electron microscope using a computing device. Even if a verification operation is required after the sorting process, the number of intersection regions Xc to be verified is limited, so the burden on the operator is greatly reduced. For this reason, by carrying out the inspection method according to one embodiment of the present invention, the sheet-shaped porous titanium body can be inspected extremely efficiently. As a result, the sheet-shaped porous titanium body can be manufactured and selected at low cost.

[0029] 3. Manufacturing method One embodiment of the present invention is a method for producing a sheet-shaped porous titanium body, which includes preparing a sheet-shaped porous titanium body and inspecting the prepared sheet-shaped porous titanium body according to the inspection method. As described above, the sheet-shaped porous titanium body may be prepared by sintering powdered titanium fine particles, for example, by a dry method or a paste method. The sheet-shaped porous titanium body may also be prepared by using titanium fibers instead of powdered titanium fine particles.

[0030] 4. Inspection Program The above-described inspection method can be implemented by a computing device and an inspection program installed therein. Thus, one embodiment of the present invention is an inspection program for causing a computing device to execute the above-described inspection method. Also, a computer-readable storage medium on which this inspection program is recorded is another embodiment of the present invention.

[0031] The computing device for executing the present inspection method is a device having a calculation function and a communication function, and may be a notebook or stationary personal computer, or a portable communication terminal such as a tablet computer. The inspection program is stored in a storage device of the computing device. Alternatively, the inspection program may be configured to be executed on the cloud. In this case, the computing device is directly or indirectly connected to a wide area network such as the Internet, and operates according to instructions from the inspection program executed on the cloud.

[0032] Examples of computer-readable storage media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, magneto-optical media such as floptical disks, and hardware devices configured to store and execute the inspection program, such as ROM, RAM, flash memory, etc. The instructions of the inspection program include not only machine code, such as that generated by a compiler, but also high-level language code executed by the server using an interpreter, etc. The inspection program is installed on the computing device from the computer-readable medium. It should be noted that the inspection program may be downloadable from a network to the computing device. EXAMPLES

[0033] 1. Example In this example, the results of inspecting a sheet-shaped porous titanium body using an inspection method according to one embodiment of the present invention will be described.

[0034] Using a JEOL Ltd. scanning electron microscope (model number JSM-7900F), an electron image (magnification 500x) of the sheet-shaped titanium porous body prepared by the paste method was obtained. The obtained secondary electron image Is and backscattered electron image Ib are shown in Figures 8(A) and 8(B), respectively. In these figures, the low gradation area surrounded by the dotted circle is one of the foreign bodies. Gradation correction was performed on these secondary electron image Is and backscattered electron image Ib using the above formula (1). The standard deviation constant C SD and the average constant C ave were 32 and 96, respectively.

[0035] Next, the extraction gradation threshold was set to the 60th gradation, and the secondary electron image Is was binarized. That is, data points of the 60th gradation or higher of the corrected secondary electron image I's were extracted as a specific region Xs. On the other hand, for the reflected electron image Ib, the extraction gradation range was set to the 30th to 90th gradation, and a region consisting of data points within the extraction gradation range among the data points of the corrected reflected electron image I'b was extracted as a specific region Xb. The filled regions in Figures 9(A) and 9(B) are the specific regions Xs and Xb, respectively. Then, an intersection region Xc common to the specific regions Xs and Xb was obtained. The filled region in Figure 9(C) is the intersection region Xc.

[0036] In this embodiment, an opening process was performed on this intersection region Xc. Here, the contraction process and the expansion process were performed once each. The filled area in FIG. 10 is the intersection region Xc after the opening process. As shown in FIG. 10, it can be seen that not only foreign objects that can be clearly identified from FIG. 8(A) and FIG. 8(B) (foreign objects surrounded by dotted circles), but also foreign objects smaller than that can be detected as the intersection region Xc. It was confirmed that by performing the above-mentioned sorting process on the intersection region Xc obtained at this stage, false detections were further reduced and detection accuracy was improved.

[0037] The time required from the start of tone correction for the secondary electron image Is and the reflected electron image Ib to the end of the opening process was approximately 5 seconds for 40 images. In contrast, the time required to visually detect all of the foreign matter detected by this method was approximately 20 minutes for 40 images. The above results clearly demonstrate that by carrying out the inspection method according to one embodiment of the present invention, it is possible to detect foreign matter mixed into a sheet-shaped porous titanium body in an extremely short time.

[0038] 2. Comparative Example As a comparative example, foreign object detection was attempted using binarization of either the secondary electron image or the backscattered electron image. Figures 11(A) and 11(B) show the binarization results of the secondary electron image. In Figure 11(A), the area of ​​250 gradations or more is filled in, and in Figure 11(B), the area of ​​120 gradations to 145 gradations is filled in. When a high gradation area in the secondary electron image is extracted as the specific area Xs, as shown in Figure 11(A), the vicinity of the boundary of the titanium fine particles is also extracted, but the high gradation foreign object surrounded by the dotted circle can be extracted. However, it was not possible to extract foreign objects with relatively low gradations. On the other hand, in Figure 11(B), where an intermediate gradation is selected, it was found that normal areas, i.e., titanium fine particles, were also extracted at the same time. Although not shown, when an attempt was made to detect the edges of the specific area Xs obtained in Figure 11(B), it was confirmed that the change in gradation at the edge was small, and one specific area Xs was divided into multiple areas. For these reasons, it is not possible to selectively detect foreign matter using only a binarized secondary electron image.

[0039] The binarization result of the backscattered electron image is shown in Figure 11(C). In the backscattered electron image, the foreign matter is observed as a low gradation region, and the gradation difference between the foreign matter and the pores and the shadows of the titanium particles is small. For this reason, as shown in Figure 11(C), the region from gradation 30 to gradation 90 was extracted as specific region Xb as a low gradation region, and it was confirmed that the pores and shadows were extracted simultaneously with the foreign matter (region surrounded by a dotted circle). Furthermore, when edge detection was attempted, effective edge detection was not possible because the gradation difference between the foreign matter and the pores and between the foreign matter and the shadows was small. From the above, it was confirmed that it is not possible to selectively detect foreign matter using only the binarized backscattered electron image.

[0040] The above results show that foreign particles can be effectively detected by using both secondary electron images and backscattered electron images, as in this inspection method.

[0041] Based on the above-mentioned embodiments of the present invention, those in which a person skilled in the art appropriately adds, removes, or modifies components, or adds, omits, or modifies processes are also included in the scope of the present invention as long as they include the gist of the present invention. Even if there are other effects and advantages different from those provided by the aspects of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally considered to be provided by the present invention. [Explanation of symbols]

[0042] 100: titanium porous sheet, 102: titanium particles, 104: foreign matter

Claims

1. Obtaining a backscattered electron image and a secondary electron image of the sheet-shaped titanium porous body; binarizing the reflected electron image and the secondary electron image according to gradation and extracting a first specific region and a second specific region, respectively; A method for inspecting a sheet-shaped porous titanium body, comprising obtaining an intersection region common to the first specific region and the second specific region.

2. 2. The inspection method according to claim 1, wherein the extraction of the first specific region is performed by acquiring, from among data points constituting the backscattered electron image, data points whose gradations are within an extraction gradation range.

3. 2. The inspection method according to claim 1, wherein the extraction of the second specific region is performed by acquiring, from among data points constituting the secondary electron image, data points whose gradation is equal to or greater than an extraction gradation threshold value.

4. The inspection method according to claim 1 , further comprising performing an opening process on the intersection region.

5. The inspection method according to claim 4, further comprising determining, as a foreign substance region, a region in which the area of ​​the intersection region after the opening process is equal to or greater than an exclusion area threshold and / or a region in which the gradation of the intersection region is equal to or greater than an exclusion gradation threshold.

6. The inspection method according to claim 5 , further comprising: determining whether the foreign matter region is caused by a foreign matter by visually observing the intersection region after the opening process.

7. The inspection method according to claim 1 , further comprising performing tone correction on the reflected electron image and the secondary electron image before extracting the first specific region and the second specific region.

8. The gradation correction is performed by adjusting the gradation G of each of the data points constituting the reflected electron image and the secondary electron image. 0 The following conversion formula is used to convert the gradation G 1 This is done by converting it into [0010] G ave is the average gray level of the data points of the reflected electron image or the secondary electron image before the conversion, SD is the standard deviation of the grayscale of the data points of the backscattered electron image or the secondary electron image before the conversion, C SD is a standard deviation constant selected from the range of 16 to 64, C ave 8. The inspection method according to claim 7, wherein: is an average constant selected from the range of 80 to 176.

9. A method for producing a sheet-shaped porous titanium body, comprising the inspection method according to any one of claims 1 to 8.

10. An inspection program configured to cause a computing device to carry out the inspection method according to any one of claims 1 to 8.

11. A computer-readable storage medium on which the inspection program according to claim 10 is recorded.

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