Nozzle, hydrogen charging method and specimen analysis method

Abstract

To provide a nozzle for injecting a hydrogen containing gas which enables a specimen surface to be analyzed with the passage of time from various angles while safely introducing hydrogen into a specimen.SOLUTION: A first opening is formed in an end at one side and a second opening is formed in an end at the other side. A nozzle comprises a first cavity part, which extends from the first opening to the other side in a first direction, and a second cavity part which extends from the second opening to one side in a second direction. In a case where an intersection of a virtual line, which passes a center of the first opening and is in parallel with the first direction, and a specimen surface is defined as a reference point, the nozzle is not in contact with a specimen, a distance between a center and the reference point is 1000 μm, and the nozzle is formed as to be disposed in such a manner that the reference point does not overlap the nozzle in a view in a direction vertical to the specimen surface. An area of a cross section of the first cavity part is 10 to 12,000 μm2, an area of a cross section of the second cavity part is 0.05 to 1,000 mm2 and a length of the first cavity part in the first direction is more than 0 mm to 1.0 mm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a nozzle, a hydrogen filling method, and a sample analysis method. [Background technology]

[0002] In the development of high-strength steels, hydrogen embrittlement, which causes a deterioration in strength and toughness due to hydrogen, has become a major problem. However, the microstructural changes related to hydrogen embrittlement are unclear, and to clarify the mechanism of hydrogen embrittlement, it is desirable to conduct sample analysis of hydrogen distribution, lattice defects, hydrides, etc. over time while introducing hydrogen into steel.

[0003] Patent Document 1 proposes a sample analysis method in which hydrogen is introduced into the sample by spraying a hydrogen-containing gas onto the sample surface while applying a voltage between the sample surface and an electrode to generate a glow discharge, and at the same time, the sample surface is analyzed with high resolution and over time using an electron beam device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-187872 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology described in Patent Document 1, the shape of the nozzle for injecting the hydrogen-containing gas onto the sample surface is not fully considered. Therefore, in order to analyze the sample surface from various angles with a high degree of freedom and to introduce hydrogen safely, the development of a nozzle suitable for this purpose is required.

[0006] The present invention aims to provide a nozzle for injecting hydrogen-containing gas, which enables the sample surface to be analyzed over time from various angles with a high degree of freedom while safely introducing hydrogen into the sample, as well as a hydrogen filling method and a sample analysis method using the same. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and is summarized as the following nozzle, hydrogen filling method, and sample analysis method.

[0008] (1) A hydrogen-containing gas injected from a nozzle is converted into plasma by glow discharge, and the plasma-contained gas is brought into contact with the surface of a metal sample; a cylindrical nozzle having a first opening formed at one end thereof for injecting the hydrogen-containing gas and a second opening formed at the other end thereof for allowing the hydrogen-containing gas to flow therein; a first cavity portion extending from the first opening toward the other side in a first direction; a second cavity portion extending from the second opening toward the one side in the second direction, When an intersection point between a virtual line passing through the center of the first opening and parallel to the first direction and the surface is set as a reference point, The nozzle is Without contacting the sample, The distance between the center and the reference point is 1000 μm, and The nozzle has a shape that can be disposed so that the reference point does not overlap with the nozzle when viewed from a direction perpendicular to the surface, The area of ​​a cross section of the first cavity, which is perpendicular to the first direction and passes through the edge of the first opening on the other side in the first direction, is 10 to 12,000 μm 2 and The area of ​​a cross section of the second cavity, which is perpendicular to the second direction and passes through the edge of the second opening on the most one side in the second direction, is 0.05 to 1000 mm 2 and The length of the first cavity in the first direction is greater than 0 mm and not more than 1.0 mm. nozzle.

[0009] (2) The second cavity portion includes a tapered portion in which a cross-sectional area perpendicular to the second direction decreases continuously or stepwise toward the one side. The nozzle according to (1) above.

[0010] (3) At least a portion of the one side is made of metal. The nozzle according to (1) or (2) above.

[0011] (4) A method for filling a metal sample with hydrogen, comprising: a step of generating plasma by glow discharge from the hydrogen-containing gas injected from the nozzle described in any one of (1) to (3) above; and bringing the hydrogen-containing gas into plasma contact with the surface of a metal sample. How to fill hydrogen.

[0012] (5) A method for analyzing a sample made of a metal, comprising: a step of generating plasma by glow discharge from the hydrogen-containing gas injected from the nozzle described in any one of (1) to (3) above; A step of bringing the hydrogen-containing gas into plasma contact with a surface of a metal sample; and irradiating the surface in contact with the plasmatized hydrogen-containing gas with a probe beam and analyzing the surface. Sample analysis methods. [Effects of the Invention]

[0013] By using the nozzle according to the present invention, it becomes possible to analyze the sample surface over time from various angles with a high degree of freedom while safely introducing hydrogen into the sample. [Brief explanation of the drawings]

[0014] [Figure 1]FIG. 2 is a cross-sectional view illustrating an example of the structure of a nozzle according to an embodiment of the present invention. [Figure 2] FIG. 10 is a cross-sectional view illustrating an example of the structure of a nozzle according to another embodiment of the present invention. [Figure 3] 1 is a diagram showing an example of a usage mode of a nozzle according to an embodiment of the present invention. FIG. [Figure 4] FIG. 10 is a diagram showing an example of a usage mode of a conventional nozzle. [Figure 5] FIG. 10 is a cross-sectional view illustrating an example of the structure of a nozzle according to another embodiment of the present invention. [Figure 6] FIG. 2 is a diagram illustrating the dimensions and shape of a test piece. [Figure 7] FIG. 2 is a diagram for explaining the dimensions and shape of a wedge. [Figure 8] FIG. 2 is a cross-sectional view showing the shape of a nozzle used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0015] A nozzle according to one embodiment of the present invention will be described with reference to the drawings.

[0016] 1 is a cross-sectional view illustrating an example of the structure of a nozzle according to one embodiment of the present invention. The nozzle of this embodiment is used to inject a hydrogen-containing gas, and more specifically, to convert the injected hydrogen-containing gas into plasma by glow discharge and bring the plasmatized hydrogen-containing gas into contact with the surface of a metal sample.

[0017] The nozzle of this embodiment can be suitably used in the vacuum chamber of an analytical instrument. The sample surface can be analyzed by irradiating the sample surface with a probe beam while introducing hydrogen into the sample using the nozzle of this embodiment. Examples of probe beams include electron beams, ion beams, and electromagnetic waves. Examples of analytical instruments that irradiate a probe beam in a vacuum chamber include scanning electron microscopes (SEMs), secondary ion mass spectroscopy (SIMSs), nuclear reaction analysis (NRAs), elastic recoil detector analysis (ERDAs), X-ray diffraction (XRDs), and X-ray absorption spectroscopy (XAFSs).

[0018] 1, the nozzle 10 has a cylindrical shape with a first opening 11 formed at one end for injecting a hydrogen-containing gas and a second opening 12 formed at the other end for allowing the hydrogen-containing gas to flow in. A first cavity 13 and a second cavity 14 are formed inside the nozzle 10. In order to introduce sufficient hydrogen into the sample, the hydrogen concentration in the hydrogen-containing gas is preferably 5% by volume or more, and more preferably 20% by volume or more.

[0019] First cavity 13 extends from first opening 11 toward the other side in the first direction. Preferably, first cavity 13 has a shape in which the area of ​​a cross section perpendicular to the first direction is substantially uniform in the first direction. The cross section of first cavity 13 perpendicular to the first direction may be polygonal or elliptical, but is preferably circular. Second cavity 14 extends from second opening 12 toward one side in the second direction. In the configuration shown in FIG. 1, the first direction and the second direction are the same direction, but as shown in FIG. 2, the first direction and the second direction may intersect with each other.

[0020] Fig. 3 is a diagram showing an example of a usage mode of a nozzle according to one embodiment of the present invention. Fig. 4 is a diagram showing an example of a usage mode of a conventional nozzle. In order to convert the hydrogen-containing gas injected from the tip of the nozzle into plasma by glow discharge, it is necessary to bring the tip of the nozzle sufficiently close to the sample surface. Furthermore, as described above, analysis of the sample surface is performed by irradiating the sample surface with a probe beam from an analytical device. Therefore, in order to realize time-dependent analysis from various angles with a high degree of freedom, the outer shape of the nozzle needs to be such that it is unlikely to interfere with the probe beam irradiated from the analytical device.

[0021] As shown in Figure 4, conventional nozzles generally have cylindrical or hemispherical tips, which requires the probe beam to be irradiated from a low angle, which reduces the degree of freedom in analysis.

[0022] Therefore, the nozzle 10 has a shape that can be arranged to simultaneously satisfy the following three conditions: Here, as shown in Fig. 3, the intersection of an imaginary line that passes through the center 11a of the first opening 11 and is parallel to the first direction with the surface 20a of the sample 20 is defined as a reference point 20b. Condition 1) The nozzle 10 does not come into contact with the sample 20. Condition 2) The distance between the center 11a and the reference point 20b is 1000 μm. Condition 3) When viewed from a direction perpendicular to the surface 20a, the reference point 20b does not overlap the nozzle 10.

[0023] The outer shape of the nozzle 10 is not limited as long as it satisfies the above conditions, but it is preferable that one side of the nozzle 10 (the side from which the hydrogen-containing gas is ejected) is frustum-shaped and the other side of the nozzle 10 (the side into which the hydrogen-containing gas flows) is cylindrical, as shown in Fig. 3. Furthermore, the outer shape of the nozzle 10 is not limited to this, and one side of the nozzle 10 may be frustum-shaped and the other side of the nozzle 10 may be prism-shaped, and the nozzle 10 may have a shape consisting of only a truncated cone or a truncated pyramid.

[0024] Furthermore, in order to stably convert the injected hydrogen-containing gas into plasma by glow discharge, it is also important to control the internal dimensions of the first cavity 13 and the second cavity 14, which are the flow paths for the hydrogen-containing gas.

[0025] First, the area of ​​the cross section (hereinafter also referred to as the "first cross section") of the first cavity 13, which is perpendicular to the first direction and passes through the edge of the first opening 11 on the other side in the first direction, is set to 10 to 12000 μm 2 The area of ​​the first cross section is 10 μm 2 If the area of ​​the first cross section is less than 12000 μm, it is not possible to maintain a sufficient pressure of the hydrogen-containing gas on the surface 20a to generate a glow discharge. 2 If the supply amount of the hydrogen-containing gas exceeds this value, the amount of the hydrogen-containing gas supplied will be excessive, and the degree of vacuum in the vacuum chamber will decrease, making it difficult to operate the analytical device. Note that when the first opening 11 is formed perpendicular to the first direction, the area of ​​the first cross section and the area of ​​the first opening 11 will be equal.

[0026] The area of ​​the cross section (hereinafter also referred to as the "second cross section") of the second cavity 14, which is perpendicular to the second direction and passes through the edge of the second opening 12 on the most one side in the second direction, is set to 0.05 to 1000 mm 2 The area of ​​the second cross section is 0.05 mm 2 If the area of ​​the second cross section is less than 1000 mm , it is not possible to maintain a sufficient pressure of the hydrogen-containing gas on the surface 20 a to generate a glow discharge. 2 If the nozzle exceeds this value, there is a risk that the nozzle will not fit inside the vacuum chamber. When the second opening 12 is formed perpendicular to the second direction, the area of ​​the second cross section and the area of ​​the second opening 12 are equal.

[0027] From the viewpoint of generating glow discharge more stably and further suppressing a decrease in the degree of vacuum in the vacuum chamber, it is preferable that the ratio of the area of ​​the second cross section to the area of ​​the first cross section is larger.

[0028] Furthermore, the length of the first cavity 13 in the first direction is set to be longer than 0 mm and not more than 1.0 mm. If the length of the first cavity 13 in the first direction is too long, the supply pressure of the hydrogen-containing gas at the second opening must be set to a high pressure, for example, 1 MPa or higher, in order to maintain a pressure of the hydrogen-containing gas in the first cavity sufficient to generate a glow discharge on the surface 20a. In this case, the risk of a hydrogen explosion in the event of a gas leak increases, which would be subject to the High Pressure Gas Safety Act, and the legally required safety measures for installing the equipment would incur enormous costs.

[0029] Therefore, the length in the first direction of first cavity 13 is set to be more than 0 mm and not more than 1.0 mm. When the area S2 of the second opening is in the above range, if the length in the first direction of first cavity 13 is not more than 1.0 mm, it is easy to ensure a flow rate of hydrogen-containing gas in the first cavity that is sufficient to generate glow discharge on surface 20 a when the supply pressure of the hydrogen-containing gas at the second opening is less than 1 MPa.

[0030] The length may be any length greater than 0 mm. From the viewpoint of ensuring sufficient strength at the tip of the nozzle 10, the length is preferably 0.05 mm or greater.

[0031] 1, second cavity 14 includes tapered portion 14a in which the cross-sectional area perpendicular to the second direction continuously decreases toward one side. By including tapered portion 14a, the nozzle can be shaped to be less likely to interfere with the probe beam, and first cavity 13 and second cavity 14 can be smoothly connected. In the configuration shown in FIG. 1, the cross section of tapered portion 14a is straight, but it may be curved, or as shown in FIG. 5, the cross-sectional area perpendicular to the second direction may decrease stepwise toward one side.

[0032] The material of the nozzle 10 is not particularly limited, and may be, for example, an insulator such as resin, ceramic, or glass, with at least a portion of one side (tip side) plated. However, arc discharge may occur when generating glow discharge to convert the hydrogen-containing gas into plasma. When arc discharge occurs in the nozzle, the plating is lost, resulting in a loss of conductivity, which significantly changes the discharge characteristics.

[0033] From this perspective, it is preferable that at least a portion of one side (tip side) of the nozzle 10 is made of metal. Alternatively, the entire nozzle 10 may be made of metal. This is because metals are less likely to change in discharge characteristics even if an arc discharge occurs and the nozzle is worn out. Furthermore, examples of metals that can be used include stainless steel, copper, aluminum, molybdenum, and tungsten, which have high melting points and excellent conductivity.

[0034] Next, a hydrogen filling method and a sample analysis method according to one embodiment of the present invention will be described. The hydrogen filling method according to this embodiment includes the steps of generating plasma from the hydrogen-containing gas injected from the nozzle 10 by glow discharge, and contacting the plasmanized hydrogen-containing gas with the surface of a metal sample.

[0035] As described above, from the viewpoint of safety, the supply pressure of the hydrogen-containing gas is 1 MPa or less. At such a supply pressure, by setting the dimensions of the nozzle 10 within the specified range described above, it becomes possible to adjust the flow rate of the hydrogen-containing gas injected from the first opening 11 to 1 to 200 mL / min, which enables stable generation of glow discharge and suppresses a decrease in the degree of vacuum in the vacuum chamber.

[0036] Furthermore, in order to generate a glow discharge between the surface 20a of the sample 20 and the nozzle 10, it is preferable that the voltage applied between the surface 20a and the nozzle 10 by the power supply (hereinafter also referred to as the "power supply voltage") be 100V or higher. In order to efficiently introduce hydrogen into the sample, it is more preferable that the power supply voltage be 200V or higher. On the other hand, if the power supply voltage is too high, the energy of the hydrogen ions will increase, heating the surface 20a due to collisions with the hydrogen ions, causing an arc discharge and potentially evaporating the elements that make up the sample 20. It is more preferable that the power supply voltage be 5kV or lower.

[0037] In the step of bringing the plasmatized hydrogen-containing gas into contact with the surface of a metal sample, the distance between the center 11a and the reference point 20b shown in Fig. 3 is preferably 10 to 1000 µm. If this distance is too short, the pressure of the hydrogen-containing gas at the surface 20a becomes too high, and the surface 20a is heated by collisions of hydrogen ions, causing an arc discharge and evaporating the elements that make up the sample 20. On the other hand, if this distance is too long, the pressure of the hydrogen-containing gas at the surface 20a becomes insufficient, and glow discharge may not occur.

[0038] In addition to the above steps, the sample analysis method according to this embodiment further includes a step of irradiating a probe beam onto the surface 20a in contact with the hydrogen-containing gas plasma, thereby enabling the sample surface to be analyzed over time from various angles with a high degree of freedom while safely introducing hydrogen into the sample.

[0039] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples. [Example]

[0040] The specimen used was martensitic steel (SCM435 steel) with the chemical composition shown in Table 1 and a tensile strength of 1892 MPa. A test piece with the dimensions and shape shown in Figure 6 was taken from this specimen, and a wedge with the dimensions and shape shown in Figure 7 was inserted into the notch to introduce a precrack. The wedge was held inserted in the specimen, and a constant strain was applied to the specimen.

[0041] [Table 1]

[0042] In this example, the test was carried out inside an SEM. The interior of the SEM sample chamber was evacuated to a vacuum using a turbomolecular pump, and a test piece was placed inside the sample chamber. A glass window was also provided in the sample chamber to allow observation of the test piece. The occurrence of glow discharge was confirmed by observing the light emitted by discharge through the glass window installed in the sample chamber.

[0043] The external dimensions of the nozzle are as shown in Figure 8, with one side being truncated cone-shaped and the other being cylindrical. The first direction in which the first cavity of the nozzle extends and the second direction in which the second cavity extends are the same, and the first opening and the second opening are formed perpendicular to the first and second directions. The internal dimensions of the nozzle are as shown in Table 2, and in this example, the area S1 of the first opening, the area S2 of the second opening, and the length d of the first cavity in the first direction were varied. The nozzle was positioned at a 45° angle with respect to the analysis surface of the test piece. The nozzle was made of stainless steel (SUS316 steel).

[0044] Between the hydrogen cylinder and the nozzle, a mass flow controller was installed to adjust the hydrogen gas flow rate, and a pressure gauge was installed to monitor the pressure supplied to the nozzle. In this example, 100% H2 hydrogen gas was used. The nozzle and test piece were connected to a DC power supply to generate a glow discharge. The SEM was used to observe the surface of the test piece. When the vacuum level in the sample chamber was less than 10 Pa, the test piece was scanned with an electron beam (probe beam) and the intensity of the secondary electrons emitted by the detector was simultaneously detected, thereby obtaining an image (secondary electron image) of the surface condition of the test piece. However, at pressures above 10 Pa, the detector would malfunction and the instrument would not operate. In this instrument, when the flow rate of hydrogen gas injected from the nozzle was approximately 200 mL / min or less, the vacuum level was less than 10 Pa.

[0045] The voltage was applied so that the nozzle served as the anode and the test piece served as the cathode, and the power supply pressure ranged from 0.1 kV to 5.0 kV. The distance between the nozzle center 11a and the test piece reference point 20b was 200 μm. The hydrogen gas supply pressure was set to less than 1 MPa, which is not subject to legal restrictions.

[0046] The electron beam energy was 15 keV, the probe current was 100 pA, and the electron beam was incident from the normal direction to the test piece surface. When hydrogen is introduced into the test piece, hydrogen embrittlement occurs and cracks propagate. The crack positions in these acquired secondary electron images were compared, and the presence or absence of crack propagation was used to determine whether hydrogen was introduced.

[0047] The results are shown in Table 2. Regarding whether or not glow discharge occurred, conditions under which glow discharge occurred stably are indicated with an "O", and conditions under which glow discharge occurred stably for 30 minutes or more are indicated with an "◎". On the other hand, conditions under which glow discharge did not occur stably are indicated with an "X". Regarding whether or not the device could be operated, conditions under which the device operated are indicated with an "O", and conditions under which the device did not operate are indicated with an "X". The results in Table 2 confirmed that for nozzles that meet the specifications of the present invention, the supply pressure was less than 1 MPa, the flow rate was 200 mL / min or less, at which a vacuum was maintained and the device could operate, and glow discharge could be generated to charge hydrogen into the test piece.

[0048] [Table 2]

[0049] Furthermore, for the nozzles in Table 2 in which glow discharge was observed, the voltage was held at 30 kV for 5 seconds to intentionally generate an arc discharge, and then returned to the original voltage. Even after the arc discharge, glow discharge occurred under the conditions in Table 2, and no changes were observed in the flow rate and supply pressure. In this way, it was confirmed that the discharge characteristics of the nozzles according to this embodiment are unlikely to change even if an arc discharge occurs. [Industrial Applicability]

[0050] By using the nozzle according to the present invention, it becomes possible to analyze the sample surface over time from various angles with a high degree of freedom while safely introducing hydrogen into the sample. [Explanation of symbols]

[0051] 10. Nozzle 11.First opening 11a.Center 12.Second opening 13.First cavity 14.Second cavity part 14a.Tapered section 20. Sample 20a.Surface 20b. Reference point

Claims

1. The hydrogen-containing gas injected from the nozzle is converted into plasma by glow discharge, and the plasma-contained gas is brought into contact with the surface of a metal sample, a cylindrical nozzle having a first opening formed at one end thereof for injecting the hydrogen-containing gas and a second opening formed at the other end thereof for allowing the hydrogen-containing gas to flow therein; a first cavity portion extending from the first opening toward the other side in a first direction; a second cavity portion extending from the second opening toward the one side in the second direction, When an intersection point between a virtual line passing through the center of the first opening and parallel to the first direction and the surface is set as a reference point, The nozzle is Without contacting the sample, The distance between the center and the reference point is 1000 μm, and The nozzle has a shape that can be disposed so that the reference point does not overlap with the nozzle when viewed from a direction perpendicular to the surface, The area of ​​a cross section of the first cavity that is perpendicular to the first direction and passes through the othermost side of the edge of the first opening in the first direction is 10 to 12,000 μm ２ and The area of ​​a cross section of the second cavity that is perpendicular to the second direction and passes through the edge of the second opening on the most one side in the second direction is 0.05 to 1000 mm ２ and The length of the first cavity in the first direction is greater than 0 mm and is equal to or less than 1.0 mm. nozzle.

2. the second cavity portion includes a tapered portion in which a cross-sectional area perpendicular to the second direction decreases continuously or stepwise toward the one side, The nozzle of claim 1 .

3. At least a portion of the one side is made of metal. The nozzle according to claim 1 or claim 2.

4. 1. A method for filling a metal sample with hydrogen, comprising: a step of generating plasma by glow discharge from the hydrogen-containing gas injected from the nozzle according to any one of claims 1 to 3; and bringing the hydrogen-containing gas into plasma contact with the surface of a metal sample. How to fill hydrogen.

5. A method for analyzing a metal sample, comprising: a step of generating plasma by glow discharge from the hydrogen-containing gas injected from the nozzle according to any one of claims 1 to 3; A step of bringing the hydrogen-containing gas into contact with a surface of a metal sample; and irradiating the surface in contact with the plasmatized hydrogen-containing gas with a probe beam and analyzing the surface. Sample analysis methods.

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