X-ray fluorescence analyzer

Abstract

The present invention provides a fluorescent X-ray analysis device comprising an X-ray source, a detector, and an iron sample chamber, wherein at least a portion of the inner surface of the sample chamber is covered with a layer composed of aluminum derived from molten aluminum; and a fluorescent X-ray analysis device comprising an X-ray source, a detector, and an iron sample chamber, wherein substantially the entire inner surface of the sample chamber is covered with a layer composed of aluminum derived from molten aluminum. The X-ray source is used to irradiate a sample with X-rays, the detector is used to detect fluorescent X-rays emitted from the sample by the irradiation with X-rays, and the iron sample chamber is used to store the sample.

Description

Technical Field

[0001] The present invention relates to a fluorescent X-ray analysis device. Background Art

[0002] Fluorescence X-ray analyzers irradiate solid, powdered, or liquid samples with primary X-rays and detect the fluorescent X-rays emitted by the primary X-rays, thereby performing qualitative or quantitative analysis of the elements contained in the sample. Currently, fluorescence X-ray analyzers are widely used as useful analytical instruments, with applications spanning a wide range of fields, from metals to food.

[0003] Figure 3 1 is a schematic diagram showing the configuration of a conventional general X-ray fluorescence analyzer. The X-ray fluorescence analyzer 101 includes a sample chamber 20 in which a sample S is placed, and an apparatus housing 60 in which an X-ray source 10 and a detector 30 are placed.

[0004] The sample chamber 20 has a sample base 21 in the shape of a quadrilateral plate and an upper chamber 22 in the shape of a square column with an upper surface in the shape of a quadrilateral plate. A circular opening 21a is formed in the central portion of the sample base 21. The upper chamber 22 can be rotatably mounted relative to the sample base 21 so that the lower surface of one side wall of the upper chamber 22 and one side of the upper surface side of the sample base 21 become an axis. Moreover, the interior of the upper chamber 22 is connected to a vacuum pump (not shown) so that it can be exhausted to a vacuum by the vacuum pump. According to such a sample chamber 20, the sample S can be arranged in a manner such that the analysis surface of the sample S blocks the opening 21a by opening the upper chamber 22, and the upper chamber 22 can be closed after the sample S is arranged and the interior of the upper chamber 22 can be exhausted to a vacuum.

[0005] The device housing 60 is a square column with a quadrilateral plate-shaped bottom surface. The sample base 21 is attached to the top surface of the square column side wall at the bottom surface. The X-ray source 10 and the detector 30 are arranged inside the device housing 60 .

[0006] The X-ray source 10 is, for example, a point-focused X-ray tube having a housing within which a target (not shown) serving as an anode and a filament (not shown) serving as a cathode are disposed. By applying a high voltage to the target and a low voltage to the filament, thermal electrons emitted from the filament collide with the end face of the target, thereby emitting primary X-rays generated at the end face of the target.

[0007] The X-ray source 10 is fixedly mounted to the lower left of the opening 21a of the sample base 21. The primary X-rays emitted from the X-ray source 10 are incident on the opening 21a at an incident angle θ. Therefore, the analysis surface of the sample S abuts against the opening 21a, thereby blocking the analysis surface of the sample S and being irradiated with the primary X-rays at an incident angle θ.

[0008] The detector 30 comprises, for example, a housing having an inlet window formed therein. A detection element (semiconductor element) for detecting fluorescent X-rays is disposed within the housing. Furthermore, the detector 30 is fixedly mounted to the lower right side of the opening 21a of the sample base 21 and is configured so that fluorescent X-rays generated on the analysis surface of the sample S are incident on the inlet window. Therefore, when the analysis surface of the sample S is irradiated with primary X-rays, the detector 30 detects the fluorescent X-rays generated there.

[0009] In X-ray analysis apparatus 101, to reduce the risk of X-rays passing through sample S irradiating the user, sample S is housed within sample chamber 20. Sample base 21 and upper chamber 22, which constitute sample chamber 20, are formed from a shielding material. Specifically, sample chamber 20 is formed from a shielding material. Japanese Patent Application Publication No. 2011-022163 (Patent Document 1) discloses the use of, for example, 3.2 mm thick iron as the shielding material. Figure 4 The relationship between the thickness of iron and X-ray transmittance is shown. Figure 4 When 15mm thick iron is used as the shielding material, X-rays transmitted through the sample chamber 20 at a tube voltage of 50kV are attenuated by 10 digits, significantly reducing the risk of X-ray exposure to the user. Furthermore, when iron is generally used as the shielding material for the sample chamber 20, it is typically nickel-plated as a rust-proofing measure. For example, Japanese Patent Application Laid-Open No. 2004-197151 (Patent Document 2) describes rust-proofing iron using nickel.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-022163

[0013] Patent Document 2: Japanese Patent Application Laid-Open No. 2004-197151 Summary of the Invention

[0014] Problems to be solved by the invention

[0015] In the case of a structure in which the inner surface of the iron sample chamber 20 is nickel-plated, when X-rays that have passed through the sample S strike the sample base 21 or the upper chamber 22, nickel fluorescent X-rays (Ni-K: 7478 eV) are generated. Such nickel fluorescent X-rays can be detected by the detector 30 together with the fluorescent X-rays generated on the analysis surface of the sample S. Therefore, there is a concern that the results of the fluorescent X-ray analysis will be adversely affected. In addition, even in the case in which the inner surface of the iron sample chamber 20 is not nickel-plated, when X-rays that have passed through the sample S strike the sample base 21 or the upper chamber 22 of the sample chamber 20, iron fluorescent X-rays (FE-K: 6403 eV) are generated. Such iron fluorescent X-rays can also be detected by the detector 30 together with the fluorescent X-rays generated on the analysis surface of the sample S. Therefore, there is a concern that the results of the fluorescent X-ray analysis will be adversely affected.

[0016] Hereinafter, the fluorescent X-rays of nickel generated by the X-rays that pass through the sample S and hit the sample base 21 or the upper chamber 22 of the sample chamber 20 are also recorded as “impurity rays originating from nickel”, and the fluorescent X-rays of iron generated by the X-rays that pass through the sample S and hit the sample base 21 or the upper chamber 22 of the sample chamber 20 are also recorded as “impurity rays originating from iron”.

[0017] Nickel can be analyzed by the fluorescent X-ray analyzer 101. For example, when the sample S is a pharmaceutical product, food, or chemical, nickel microanalysis can be performed to measure impurities in the sample S. In such cases, impurity radiation from nickel is believed to significantly hinder the microanalysis of nickel in the sample S.

[0018] In addition, in recent years, there has been a surge in demand for trace (ppm-level) analysis using fluorescent X-ray analyzers. To perform trace analysis, it is necessary to prepare standard samples at the ppm level. Acidic solvents such as hydrochloric acid are generally used to prepare such standard samples. When fluorescent X-ray analysis is performed on standard samples containing acidic solvents, the acidic solvents evaporate. The volatilized acidic solvents corrode the nickel plating applied to the inner surface of the iron sample chamber 20. As a result, while this does not affect the performance of the analysis itself, there is still the problem of black stains forming on the inner surface of the sample chamber 20, which detracts from the aesthetics of the fluorescent X-ray analyzer.

[0019] The present invention aims to reduce the influence of impurity radiation originating from nickel and impurity radiation originating from iron on the fluorescent X-ray analysis in a fluorescent X-ray analysis apparatus including a sample chamber made of iron, and to suppress the generation of black stains on the inner surface of the sample chamber caused by acid solvents.

[0020] Solutions for solving problems

[0021] The present invention provides the following fluorescent X-ray analysis device.

[0022] [1] A fluorescent X-ray analysis apparatus comprising: an X-ray source for irradiating a sample with X-rays; a detector for detecting fluorescent X-rays emitted from the sample by the X-ray irradiation; and an iron sample chamber for storing the sample, wherein at least a portion of the inner surface of the sample chamber is coated with a layer of aluminum derived from molten aluminum. This reduces the effect of impurity radiation from nickel and iron on the fluorescent X-ray analysis. It also suppresses the formation of black stains on the inner surface of the sample chamber caused by acid solvents.

[0023] [2] The fluorescent X-ray analysis apparatus according to [1], wherein substantially the entire inner surface of the sample chamber is coated with a layer of aluminum derived from molten aluminum. This can further reduce the effects of impurity radiation from nickel and impurity radiation from iron on the fluorescent X-ray analysis.

[0024] [3] The fluorescent X-ray analysis apparatus according to [1] or [2], further comprising a coating layer on the layer composed of aluminum derived from molten aluminum, the coating layer being a layer for attenuating fluorescent X-rays from the aluminum. This can further reduce the influence of impurity radiation derived from the aluminum on the fluorescent X-ray analysis.

[0025] [4] The fluorescent X-ray analysis device according to [3], wherein the coating layer is a layer composed of carbon. This can further reduce the influence of impurity radiation originating from aluminum on the fluorescent X-ray analysis.

[0026] Effects of the Invention

[0027] According to the present invention, in a fluorescent X-ray analysis apparatus including an iron sample chamber, the influence of impurity radiation originating from nickel and iron on fluorescent X-ray analysis can be reduced, and the generation of black stains on the inner surface of the sample chamber caused by acid solvents can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram showing an example of the X-ray fluorescence analysis device according to the present invention.

[0029] Figure 2 This is a schematic diagram showing another example of the X-ray fluorescence analyzer according to the present invention.

[0030] Figure 3 This is a schematic diagram showing an example of a conventional X-ray fluorescence analyzer.

[0031] Figure 4 It is a graph showing the relationship between the thickness of iron and the X-ray transmittance.

[0032] Figure 5 This is a graph showing the relationship between the thickness of a layer composed of aluminum derived from molten aluminum and the X-ray transmittance.

[0033] Figure 6 This is a graph showing the relationship between the thickness of a carbon layer and the X-ray transmittance. DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention, but the present invention is not limited thereto. In this specification, descriptions in the form of "A to B" refer to the upper and lower limits of a range (i.e., greater than A and less than B). If A does not specify a unit and only B specifies a unit, the unit of A is the same as the unit of B.

[0035] <Fluorescent X-ray Analyzer>

[0036] Figure 1 101 is a schematic diagram showing an example of a fluorescent X-ray analyzer according to an embodiment of the present invention. Components identical to those of the conventional fluorescent X-ray analyzer 101 are denoted by the same reference numerals.

[0037] The fluorescent X-ray analysis apparatus 1 according to the present invention includes an X-ray source 10 for irradiating a sample S with X-rays; a detector 30 for detecting fluorescent X-rays emitted from the sample S by the X-ray irradiation; and an iron sample chamber 20 for housing the sample S. At least a portion of the interior surface of the sample chamber 20 is coated with a layer 40 composed of aluminum derived from molten aluminum. The interior surface of the sample chamber 20 is not nickel-plated. Hereinafter, the "layer 40 composed of aluminum derived from molten aluminum" will also be referred to as the "molten aluminum layer 40."

[0038] In the X-ray fluorescence analyzer 1 according to the present invention, the inner surface of the iron sample chamber 20 is not nickel-plated. Therefore, it is believed that no nickel-derived impurity radiation is generated. In other words, the X-ray fluorescence analyzer 1 according to the present invention suppresses the generation of nickel-derived impurity radiation, thereby reducing the impact of nickel-derived impurity radiation on X-ray fluorescence analysis.

[0039] In the fluorescent X-ray analysis apparatus 1 according to the present invention, at least a portion of the inner surface of the iron sample chamber 20 is covered with a molten aluminum layer 40. X-rays generated by the X-ray source 10 pass through the molten aluminum layer 40 and reach the sample base 21 or the upper chamber 22 of the sample chamber 20. As a result, impurity rays originating from the iron are generated.

[0040] Here, if Figure 5 As shown, the molten aluminum layer 40 attenuates the impurity radiation originating from iron. Figure 1As shown, when the inner surface of the upper chamber 22 is coated with the molten aluminum layer 40, it is believed that the iron-derived impurity radiation generated from the iron upper chamber 22 is attenuated when passing through the molten aluminum layer 40 coating the upper chamber 22. In other words, in the fluorescent X-ray analysis apparatus 1 according to the present invention, the generation of iron-derived impurity radiation is suppressed, thereby reducing the influence of the iron-derived impurity radiation on the fluorescent X-ray analysis.

[0041] The molten aluminum layer 40 covers at least a portion of the inner surface of the iron sample chamber 20. This, as described above, can reduce the effects of iron-derived impurity radiation on fluorescent X-ray analysis. The molten aluminum layer 40 may cover approximately 10% of the inner surface of the iron sample chamber 20, approximately 20% of the inner surface, approximately 30% of the inner surface, approximately 40% of the inner surface, approximately 50% of the inner surface, approximately 60% of the inner surface, approximately 70% of the inner surface, approximately 80% of the inner surface, or substantially the entire inner surface of the iron sample chamber 20. In this specification, "covering substantially the entire inner surface of the sample chamber 20" means that at least 90% of the inner surface of the sample chamber 20 is covered. By increasing the proportion of the inner surface of the sample chamber 20 covered by the molten aluminum layer 40 , the generated iron-derived impurity rays are significantly attenuated by the molten aluminum layer 40 , thereby significantly reducing the influence of the iron-derived impurity rays on the fluorescent X-ray analysis.

[0042] The corrosion resistance of the molten aluminum layer 40 is superior to that of nickel plating. Therefore, since at least a portion of the inner surface of the iron sample chamber 20 is coated with the molten aluminum layer 40, the occurrence of black stains on the inner surface of the sample chamber 20 caused by acid solvents can be expected to be suppressed. When substantially the entire inner surface of the sample chamber 20 is coated with the molten aluminum layer 40, the occurrence of black stains on the sample chamber 20 caused by acid solvents can be expected to be significantly suppressed.

[0043] That is, in the fluorescent X-ray analysis apparatus 1 according to the present invention, the influence of impurity radiation originating from nickel and impurity radiation originating from iron on fluorescent X-ray analysis is reduced, and the generation of black stains on the inner surface of the sample chamber 20 caused by the acid solvent is suppressed.

[0044] Molten aluminum layer

[0045] The molten aluminum layer 40 is a layer composed of aluminum derived from molten aluminum. The molten aluminum layer 40 can be formed, for example, by the following steps (1) to (4).

[0046] (1) Pure steel is prepared as a base material of the iron sample chamber 20 .

[0047] (2) The pure steel is subjected to flux treatment as a pretreatment.

[0048] (3) Prepare molten aluminum maintained above the melting point (approximately 660°C).

[0049] (4) Immerse the pure steel after fluxing treatment in the molten aluminum solution for several minutes.

[0050] In this way, the surface of the steel can be covered with a molten aluminum layer. A passivating oxide film is thought to form on the outermost surface of the molten aluminum layer. This oxide film is expected to suppress the generation of black stains caused by acid solvents.

[0051] The thickness of the molten aluminum layer 40 is not particularly limited. It is preferably a thickness that achieves the superior effect of applying the molten aluminum layer 40 instead of nickel plating (i.e., a greater attenuation effect on iron-derived impurity radiation than would be achieved if the iron sample chamber had nickel plating on its inner surface). The nickel plating typically has a thickness of 5 μm to 15 μm, and it is believed that this thickness can attenuate iron-derived impurity radiation by 30% to 67%. Therefore, the molten aluminum layer 40 preferably has a thickness that attenuates iron-derived impurity radiation to less than 30%.

[0052] For example, according to Figure 5 When the thickness of the molten aluminum layer 40 is, for example, 50 μm, the iron-derived impurity radiation that passes through the molten aluminum layer 40 is attenuated by approximately 17.0% compared to the iron-derived impurity radiation before passing through the molten aluminum layer 40, which is preferable. When the thickness of the molten aluminum layer 40 is, for example, 100 μm, the iron-derived impurity radiation that passes through the molten aluminum layer 40 is attenuated by approximately 8.5% compared to the iron-derived impurity radiation before passing through the molten aluminum layer 40, which is more preferable. When the thickness of the molten aluminum layer 40 is, for example, 200 μm, the iron-derived impurity radiation that passes through the molten aluminum layer 40 is attenuated by approximately 0.8% compared to the iron-derived impurity radiation before passing through the molten aluminum layer 40, which is even more preferable. On the other hand, if the thickness of the molten aluminum layer 40 is less than 25 μm, the attenuation of the iron-derived impurity radiation may still have room for improvement. If the thickness of the molten aluminum layer 40 exceeds 1000 μm, the formation of the molten aluminum layer 40 itself may become difficult. In this case, instead of immersing the fluxed pure steel in molten aluminum for several minutes in (4), it may be reasonable to use other methods such as aluminum casting. Therefore, for example, the thickness of the molten aluminum layer 40 can be 25 μm or more and less than 1000 μm.

[0053] Furthermore, as the X-rays generated by X-ray source 10 strike the molten aluminum layer 40, they generate aluminum fluorescent X-rays (Al-K: 1486 eV). However, these aluminum fluorescent X-rays are believed to have a limited impact on the results of X-ray fluorescence analysis. This is because the energy of aluminum fluorescent X-rays is generally significantly different from the energy of the elements being analyzed in X-ray fluorescence analysis equipment. Hereinafter, "aluminum fluorescent X-rays" will also be referred to as "impurity radiation originating from aluminum."

[0054] Cladding

[0055] Reference Figure 2 The molten aluminum layer 40 may further include a coating layer 50. The coating layer 50 attenuates aluminum-derived impurity radiation. It is believed that aluminum-derived impurity radiation generated from the molten aluminum layer 40 is attenuated when passing through the coating layer 50 disposed on the molten aluminum layer 40. This significantly reduces the impact of aluminum-derived impurity radiation on fluorescent X-ray analysis.

[0056] The material constituting the coating layer 50 is not particularly limited as long as it attenuates impurity radiation originating from aluminum, does not generate fluorescent X-rays that would hinder fluorescent X-ray analysis, and can be disposed on the molten aluminum layer 40 even when the molten aluminum layer 40 has a complex shape, such as a free-form surface. For example, the coating layer 50 may be a layer composed of carbon, boron nitride (BN), polyimide, polymethyl methacrylate (PMMA), or the like.

[0057] The coating layer 50 is preferably a layer composed of carbon. Figure 6 As shown, when the thickness of the carbon coating 50 is 50 μm, the aluminum-origin impurity radiation that passes through the coating 50 is attenuated to approximately 0.04% compared to the aluminum-origin impurity radiation before passing through the coating 50. This significantly reduces the effect of aluminum-origin impurity radiation on fluorescent X-ray analysis. Furthermore, even when the coating 50 is made of BN, polyimide, or PMMA, it is believed that the aluminum-origin impurity radiation is attenuated to the same degree as when the carbon coating 50 is used.

[0058] The fluorescent X-ray analysis device according to the present invention preferably includes an alloy layer composed of a material constituting the sample chamber (e.g., iron) and aluminum between the inner surface of the sample chamber and the layer composed of aluminum derived from molten aluminum. The composition ratio of the material constituting the sample chamber to the aluminum in the alloy layer is preferably 5:1 to 1:5, more preferably 2:1 to 1:2, and most preferably 1:1.

[0059] In this case, the fluorescent X-ray analyzer has a layered structure comprising an alloy layer on the inner surface of the sample chamber and an aluminum layer on the alloy layer as a molten aluminum layer. The molten aluminum layer preferably has a thickness sufficient to attenuate iron-derived impurity radiation to less than 30%. For example, the combined thickness of the alloy layer and the aluminum layer can be 25 μm or greater and less than 1000 μm. Furthermore, when the molten aluminum layer includes the alloy layer and the aluminum layer, the aluminum layer preferably has a thickness of 12.5 μm to 500 μm, more preferably 25 μm to 200 μm, and even more preferably 50 μm to 100 μm.

[0060] The embodiments and examples disclosed herein are to be considered in all respects as illustrative and non-restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments and examples described above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0061] Description of Reference Numerals

[0062] 1. 101: Fluorescent X-ray analysis device; 10: X-ray source; 20: Sample chamber; 21: Sample base; 22: Upper chamber; 30: Detector; 40: Molten aluminum layer; 50: Coating layer; 60: Device housing; 21a: Opening; S: Sample.

Claims

1. A fluorescent X-ray analysis device, comprising: An X-ray source, which is used to irradiate the sample with X-rays; a detector for detecting fluorescent X-rays emitted from the sample by the irradiation of the X-rays; as well as An iron sample chamber for storing the sample. wherein at least a portion of the interior surface of the sample chamber is coated with a layer of aluminum derived from molten aluminum, and Here, a coating layer is further provided on the layer composed of aluminum derived from molten aluminum, and the coating layer is a layer for attenuating fluorescent X-rays of aluminum.

2. The fluorescent X-ray analysis device according to claim 1, wherein More than 90% of the inner surface of the sample chamber is covered with the layer composed of aluminum derived from molten aluminum.

3. The fluorescent X-ray analysis device according to claim 1 or 2, wherein: The coating layer is a layer composed of carbon.

4. The fluorescent X-ray analysis device according to claim 1 or 2, wherein: The sample chamber does not include the X-ray source and the detector, and only the inner surface of the sample chamber is covered with the layer composed of aluminum derived from molten aluminum.

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