Hydrogen gas barrier film and hydrogen gas barrier structure

Abstract

To provide a hydrogen gas barrier film having better hydrogen gas barrier characteristics than before, and a hydrogen gas barrier structure including the same.SOLUTION: A hydrogen gas barrier film (3) consisting of AlTiON includes 30 at% or more of N. A hydrogen gas barrier structure (1) includes a base material (2) and the hydrogen gas barrier film formed on the surface (21) of the base material; the base material consists of, for example, iron based material; the hydrogen gas barrier film preferably includes, for example, 32-42 at% of N; and the hydrogen gas barrier film has, for example, a thickness of 200 nm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydrogen gas barrier film and a hydrogen gas barrier structure including the same. [Background technology]

[0002] Many inorganic thin films, primarily made of SiON, have been proposed as gas barrier films, but they are ineffective against hydrogen. One known hydrogen gas barrier film is described in Patent Document 1. The hydrogen barrier film described in Patent Document 1 is a multilayer film in which first and second layers are alternately stacked. If the number of first layers is n and the number of second layers is m, the total number of first and second layers, i.e., n + m, is 10 to 1,000. The hydrogen barrier film has a total thickness of 0.5 μm to 2 μm. The thicknesses of the first and second layers are 5 nm to 10 nm, respectively. The first layer is made of an alloy nitrogen compound selected from TiSiNbN, TiMoN, TiAlN, and AlCrN, and the second layer is made of an alloy nitrogen compound selected from TiSiNbN, TiMoN, TiAlN, and AlCrN that is different from the first layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-139009 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, simply using an amorphous film, as with conventional general gas barrier films, is insufficient to function as a hydrogen gas barrier film. Furthermore, the range of application is limited, making it difficult to apply to complex shapes such as piping. On the other hand, the hydrogen barrier function film described in Patent Document 1 is thick and expensive. Furthermore, nitride films tend to have high stress, and a thick film increases this stress even more. High stress makes cracks and peeling more likely to occur. Furthermore, in crystalline films, cracks occur at grain boundaries, which can become hydrogen permeation paths, potentially reducing barrier performance. On the other hand, to create a single-crystalline film, a large crystal size is required, which is practically impossible.

[0005] The present invention has been made in view of the circumstances exemplified above, etc. That is, the present invention provides, for example, a hydrogen gas barrier film having better hydrogen gas barrier properties than conventional films, and a hydrogen gas barrier structure including the same. [Means for solving the problem]

[0006] The hydrogen gas barrier film according to claim 1 is made of AlTiON and contains N. It contains 32 to 42 at % and is formed to a film thickness of 200 nm or less. Claim 2 to The hydrogen gas barrier structure (1) described is A substrate (2), a hydrogen gas barrier film (3) formed on the surface (21) of the substrate; Equipped with The hydrogen gas barrier film is made of AlTiON and contains N. It contains 32 to 42 at % and is formed to a film thickness of 200 nm or less.

[0007] In addition, in each section of the application documents, each element may be assigned a reference symbol in parentheses. In this case, the reference symbol merely indicates an example of the correspondence between the element and the specific configuration described in the embodiment described below. Therefore, the present invention is not limited in any way by the description of the reference symbol. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a hydrogen gas barrier structure according to one embodiment of the present invention. [Figure 2] 2 is a table comparing the hydrogen gas barrier properties of the hydrogen gas barrier film shown in FIG. 1 with those of comparative examples. [Figure 3] 2 is a graph showing the relationship between the nitrogen content and the hydrogen gas barrier properties in the hydrogen gas barrier film shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that various modifications applicable to one embodiment may be hindered from being understood if they are introduced in the middle of a series of explanations relating to the embodiment. Therefore, the modifications will not be introduced in the middle of a series of explanations relating to the embodiment, but will be explained together after the series of explanations.

[0010] (composition) 1, the hydrogen gas barrier structure 1 according to this embodiment includes a substrate 2 and a hydrogen gas barrier film 3. The hydrogen gas barrier film 3 is formed on a surface 21 of the substrate 2. In other words, the hydrogen gas barrier structure 1 has a structure similar to a bonded body of the substrate 2 and the hydrogen gas barrier film 3.

[0011] The substrate 2 is formed of an iron-based material, for example, a chromium-containing steel material, i.e., stainless steel. Specifically, the substrate 2 may be formed of an austenitic stainless steel such as SUS316L. The surface 21 of the substrate 2 is formed as an interface containing an FeO component.

[0012] The hydrogen gas barrier film 3 is made of AlTiON and contains 30 at % or more of N. Specifically, the nitrogen content is, for example, 30 to 50 at %. If the nitrogen content is higher than 50 at %, the oxygen content becomes extremely low, resulting in a nitride film. Preferably, the hydrogen gas barrier film 3 contains 32 to 42% of N. The hydrogen gas barrier film 3 may also contain 0.4 at % or more of Cl as an impurity. The hydrogen gas barrier film 3 is formed to a thickness of 200 nm or less (i.e., as a thin film). In this embodiment, the hydrogen gas barrier film 3 is provided as a single layer on the surface 21 of the substrate 2. The hydrogen gas barrier film 3 is formed so that AlO is the main component at the outermost surface 31 and the substrate interface 32. The outermost surface 31 is the surface of the hydrogen gas barrier film 3 opposite to the substrate interface 32, which is the bonding interface with the substrate 2. The hydrogen gas barrier film 3 can be formed by a vapor phase deposition method (e.g., ALD). ALD is an abbreviation for atomic layer deposition.

[0013] (Manufacturing method) The method for manufacturing the hydrogen gas barrier structure 1 and the hydrogen gas barrier film 3 according to this embodiment will be outlined below using a specific example in which a substrate 2 made of austenitic stainless steel such as SUS316L is used.

[0014] First, a substrate 2 made of austenitic stainless steel is prepared. The prepared substrate 2 is degreased with an organic solvent such as acetone, and then the surface 21 of the substrate 2 is treated with an alkaline chemical solution. This alkaline chemical treatment improves adhesion between the surface 21 of the substrate 2 and the hydrogen gas barrier film 3. A solution of a quaternary ammonium hydroxide is preferably used as the alkaline chemical solution. Specific examples of usable quaternary ammonium hydroxides include tetramethylammonium hydroxide (i.e., TMAH), tetraethylammonium hydroxide (i.e., TEAH), and tetrapropylammonium hydroxide, with TMAH being particularly preferred. One or more types of quaternary ammonium hydroxide can be used. The hydrogen gas barrier film 3 is formed on the surface 21 of the substrate 2 by vapor deposition (e.g., ALD), thereby obtaining the hydrogen gas barrier structure 1 shown in FIG. 1. The oxygen and nitrogen contents can be controlled by pulsing H2O or NH3.

[0015] (effect) The hydrogen gas barrier performance exhibited by the hydrogen gas barrier structure 1 according to this embodiment, that is, the hydrogen gas barrier film 3, will be described below using examples and comparative examples.

[0016] As described above, the hydrogen barrier function film made of a nitride film described in Patent Document 1 has a large thickness (specifically, 0.5 μm to 2 μm). This results in high costs. It also increases stress. High stress makes cracks and peeling more likely to occur, resulting in a decrease in barrier performance. In particular, because it is a crystalline film, cracks are likely to occur starting from grain boundaries.

[0017] In this regard, although AlTiO, an oxide film, has excellent barrier properties, when it is thinned (for example, to a thickness of 200 nm or less), sufficient barrier properties cannot be obtained. Therefore, as a result of extensive research, the inventors discovered that by doping the AlTiO film with nitrogen, it is possible to achieve both thinning and sufficient barrier properties. According to the inventors' investigations, it is presumed that nitrogen doping densifies the film, making it less permeable to hydrogen. Furthermore, because of its amorphous structure, cracking is effectively suppressed and adhesion to the substrate 2 is improved.

[0018] FIG. 2 compares the hydrogen gas barrier properties of the hydrogen gas barrier film 3 in the examples with those in the comparative examples. The hydrogen gas barrier film 3 in Example 1 is an AlTiON thin film with a thickness of 175 nm, and has a nitrogen content of 42 at %, an aluminum content of 28 at %, a titanium content of 19 at %, and an oxygen content of 8 at %. Example 2 is an example of an AlTiON film with the same nitrogen content as Example 1 but a thickness of 85 nm. Examples 3 and 4 are examples of an AlTiON film with the same thickness as Example 1 but with a different nitrogen content. Comparative Example 1 is an example of an AlTiO thin film with almost the same thickness as Example 1 but with a nitrogen content of 0. Comparative Example 2 is an example of an AlO thin film with a thickness of 160 nm, almost the same thickness as Comparative Example 1. Comparative Example 3 is an example of a TiO thin film with a thickness of 160 nm, the same thickness as Comparative Example 2. FIG. 3 is a graph plotting the relationship between nitrogen content and hydrogen permeability coefficient for Examples 1, 3, and 4, and Comparative Example 1, which have almost the same thickness.

[0019] As shown in Figure 2, Example 1, which had a nitrogen content of 42 at%, achieved very good hydrogen gas barrier performance. Even when the nitrogen content was varied within the ranges of 40-44 at%, the aluminum content was varied within the ranges of 25-30 at%, the titanium content was varied within the ranges of 16-23 at%, and the oxygen content was varied within the ranges of 6-10 at%, the same hydrogen gas barrier performance was achieved. Furthermore, Example 2, in which the thickness of the hydrogen gas barrier film 3 was reduced to a very thin 85 nm, also achieved very good hydrogen gas barrier performance.

[0020] It should be noted that Comparative Example 1, which is an AlTiO thin film, has higher hydrogen gas barrier performance than Comparative Example 2, which is an AlO thin film, and Comparative Example 3, which is a TiO thin film. However, the Examples, which are nitrogen-doped AlTiON thin films, have higher hydrogen gas barrier performance than Comparative Example 1, which is an oxide film not doped with nitrogen, i.e., an AlTiO thin film. In particular, very good hydrogen gas barrier performance was obtained in Examples 1 to 3, which had a nitrogen content of 32 to 42 at%. Referring to the graph in Figure 3, there is a large difference in hydrogen permeability coefficient between the example with a nitrogen content of 21% (i.e., Example 4) and the example with a nitrogen content of 32% (i.e., Example 3). From this graph, it can be seen that by setting the nitrogen content to at least 30%, the hydrogen permeability coefficient can be increased to 10 -16 It is estimated with high certainty that the temperature will drop to the range of

[0021] As described above, the hydrogen gas barrier film 3 according to this embodiment, which is an AlTiON thin film, can exhibit excellent hydrogen gas barrier performance even when formed as a thin single layer. Therefore, this embodiment can simultaneously achieve excellent effects such as low cost, low stress, crack suppression, and improved adhesion.

[0022] (Variation) The present invention is not limited to the above-described embodiment. Therefore, the above-described embodiment can be modified as appropriate. Representative modifications will be described below. In the following description of the modifications, differences from the above-described embodiment will be mainly described. Furthermore, the same reference numerals are used for parts that are identical or equivalent to each other in the above-described embodiment and the modifications. Therefore, in the following description of the modifications, the description of the above-described embodiment can be used as appropriate for components that have the same reference numerals as the above-described embodiment, unless there is a technical contradiction or special additional explanation.

[0023] The substrate 2 is not limited to austenitic stainless steel such as SUS316L. The method for forming the hydrogen gas barrier film 3 is not limited to ALD, and general physical vapor deposition or chemical vapor deposition may be used. There is also no particular limitation on the number of layers in the hydrogen gas barrier film 3, and it may have, for example, a two-layer structure or a three-layer structure.

[0024] It goes without saying that the elements constituting the above-described embodiments are not necessarily essential unless expressly stated as essential or clearly considered essential in principle. Furthermore, when numerical values ​​such as the number, amount, range, etc. of components are mentioned, the present invention is not limited to those specific numerical values ​​unless expressly stated as essential or clearly limited to specific numerical values ​​in principle. Similarly, when the shape, direction, positional relationship, etc. of components are mentioned, the present invention is not limited to those shapes, directions, positional relationship, etc. unless expressly stated as essential or clearly limited to specific shapes, directions, positional relationship, etc. in principle.

[0025] The modified examples are not limited to the above examples. For example, other than those exemplified above, multiple embodiments may be combined with each other as long as there is no technical contradiction. Similarly, multiple modified examples may be combined with each other as long as there is no technical contradiction. [Explanation of symbols]

[0026] 1 Hydrogen gas barrier structure 2 Base material 21 Surface 3 Hydrogen gas barrier film 31 Top surface 32 Base material interface

Claims

1. A hydrogen gas barrier film (3), Made of AlTiON and containing 32 to 42 at% N, Formed with a film thickness of 200 nm or less, Hydrogen gas barrier film.

2. A hydrogen gas barrier structure (1), A substrate (2), a hydrogen gas barrier film (3) formed on the surface (21) of the substrate; Equipped with The hydrogen gas barrier film is made of AlTiON, contains 32 to 42 at % N, and is formed to a film thickness of 200 nm or less. Hydrogen gas barrier structure.

3. The hydrogen gas barrier film is formed on the surface in a single layer or two layers. The hydrogen gas barrier structure according to claim 2 .

4. The substrate is made of an iron-based material. The hydrogen gas barrier structure according to claim 2 or 3.

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