Metal part structured by laser irradiation for a device for transporting and / or storing and / or producing hydrogen

Abstract

Disclosed is a metal part (100) comprising a surface (112) with low hydrogen permeability. Also disclosed is a method for structuring such a part (100) by femtosecond laser irradiation.

Description

Laser-structured metal part for hydrogen transport, storage, and / or production devices

[0001] The invention relates to the field of techniques for structuring, or texturing, the surface of a part, in particular by irradiation of the surface using a pulsed laser beam.

[0002] The invention is of particular interest, but not limited to, the sectors of hydrogen manufacturing, transport and storage. State of the art

[0003] Parts in contact with a hydrogen-rich environment, such as hydrogen engine parts or valves or taps of hydrogen transport devices, undergo hydrogen embrittlement which tends to alter their mechanical properties, for example reducing their tensile strength and / or ductility.

[0004] The action of hydrogen thus leads to industrial risks in the sectors of hydrogen manufacturing, transport and storage.

[0005] There is a need to reduce such risks.

[0006] For this purpose, the invention relates to a metallic part, comprising a surface intended to limit the permeability of the part to hydrogen, said surface forming: structures which have a spatial periodicity and / or a characteristic dimension between 1 nm and 5000 nm, a layer of oxide(s) having a thickness between 0.1 nm and 100.0 nm.

[0007] Any conventional measurement technique known to a person skilled in the art can be used to measure such parameters.

[0008] In a first embodiment variant, the spatial periodicity and / or characteristic dimension of said structures is between 300 nm and 700 nm.

[0009] In a second embodiment variant, the spatial periodicity and / or characteristic dimension of said structures is between 1 nm and 100 nm.

[0010] Without limitation, said characteristic dimension can typically be an average distance between a trough and a peak formed by one of said structures and / or between two peaks formed by two respective of said structures.

[0011] In one embodiment, said oxide layer(s) has a thickness between 5.0 nm and 50.0 nm.

[0012] In one embodiment, said structures have an average height less than or equal to 1000 nm, preferably less than or equal to 500 nm.

[0013] In one embodiment, said structures are formed by femtosecond laser irradiation.

[0014] In one embodiment, the oxide layer(s) comprises at least one metal oxide, for example an iron oxide and / or a chromium oxide and / or a nickel oxide.

[0015] In one embodiment, the oxide layer(s) is at least partially amorphous.

[0016] The said part can be made entirely or partially in one or more oxides of said oxide layer(s).

[0017] Thus, in a non-limiting manner, according to a first variant of the embodiment, all parts of the piece may comprise at least one common metal oxide.

[0018] According to a second embodiment, one or more parts of the part, including a part forming said surface, may comprise at least one metal oxide of a first type, and one or more other parts of the part may comprise at least one metal oxide of a second type. In other words, the part may be composite.

[0019] The invention also relates to a device for manufacturing and / or storing and / or transporting hydrogen, comprising at least one part as defined above.

[0020] The invention also relates to a method for structuring such a part.

[0021] In one embodiment, the process includes a step of supplying the part and one or more iterations of a phase of structuring respective parts of a surface of the part.

[0022] The structuring phase may include the following steps: generation of an input laser beam using laser pulses, processing of the input laser beam to form an output beam, irradiation of a portion of the workpiece surface by the output laser beam.

[0023] Preferably, these laser pulses are femtosecond pulses.

[0024] The pulses can be of a different order of magnitude, for example picosecond pulses.

[0025] In one embodiment, the processing step includes linear, circular, radial, elliptical, azimuthal, or crossed polarization of the input laser beam.

[0026] Of course, a combination of several polarizations including those described above can be implemented.

[0027] Without limitation, the input laser beam can have a Gaussian, Bessel, or annular intensity distribution.

[0028] In one embodiment, during at least one iteration of the structuring phase, the irradiation step is implemented so as to produce on the surface of the part structures having a spatial periodicity and / or a characteristic dimension between 1 nm and 1000 nm, for example between 300 nm and 700 nm, or between 1 nm and 100 nm.

[0029] In one embodiment, during at least one iteration of the structuring phase, the output laser beam comprises a number of pulses ranging from 1 to 100,000.

[0030] In one embodiment, during at least one iteration of the structuring phase, the fluence of the output laser beam is in a range from 0.01 J / cm² to 5 J / cm².

[0031] The invention makes it possible to reduce the absorption of hydrogen in a part, by structuring or texturing a metallic surface of that part.

[0032] The inventors believe that the invention typically makes it possible to provide a metal part that absorbs sixteen times less hydrogen than a polished metal part.

[0033] Without limitation, the structuring according to the invention of a part made of a ferrochrome alloy allows the formation of an ultrathin duplex layer, typically on the order of 5 nm, comprising iron and chromium oxides. It has been experimentally demonstrated that such a layer, combined with the topography obtained by texturing, allows a reduction of nearly 95% in the subsurface hydrogen concentration.

[0034] In an original way, a post-treatment analysis with citric acid highlighted the enhanced protective role of such an ultrathin duplex layer, contributing to the measured reduction of permeability resulting from hydrogen trapping in this layer, at the interface between iron and chromium oxides.

[0035] Other advantages and features of the invention will become apparent from the detailed, non-limiting description that follows. Brief description of the figures

[0036] The detailed description that follows refers to the attached drawings on which: a is a schematic view of a femtosecond laser irradiation surface texturing device; a is a schematic view of a metal part comprising a surface structured according to the invention; a shows a surface of a part comprising two-dimensional periodic surface structures with low spatial frequency; a shows a surface of a part comprising two-dimensional periodic surface structures with high spatial frequency; a shows a surface of a part comprising one-dimensional periodic surface structures with low spatial frequency; a shows a surface of a part comprising one-dimensional periodic surface structures with high spatial frequency. Detailed description of implementation methods

[0037] The invention relates to a part, in particular a metallic part, intended to be in contact with a hydrogen-rich environment, for example a part of a hydrogen engine, a part forming a valve or tap of a hydrogen transport network, or more generally a part equipping or forming part of a device for the production and / or storage and / or transport of hydrogen.

[0038] The part of the invention has a structured, or textured, surface so as to limit the permeability of the part to hydrogen.

[0039] The following description presents a non-limiting technique for creating structures on the surface of such a part by femtosecond laser irradiation.

[0040] A non-limiting example of a femtosecond laser irradiation device 1 that can be implemented within the framework of the invention is shown.

[0041] With reference to the, device 1 includes a system 2 configured to generate an input laser beam 3, and a system 4 configured to process the input laser beam 3 to form an output laser beam 5 capable of irradiating a surface of a part 100.

[0042] As is known in itself, the generation 2 system includes a femtosecond laser source, i.e. a laser emitting light in very short pulses, which can typically be between 1 fs and 1 ns, as well as a diaphragm.

[0043] System 2 is typically configured to be able to generate a beam with a wavelength λ between 100 nm and 5000 nm.

[0044] The processing system 4 of the device 1 comprises a series of optical components including, in the example of: a power control element 11 comprising a delay blade, in this case a half-wave blade configured to introduce a delay of λ / 2 into the beam 3, a polarization element 12 comprising a thin-film polarizer, two splitters 16 and 18, the splitter 16 being configured to split the input beam 3A processed by the elements 11 and 12 into two beams 3B and 3C in a 50 / 50 ratio, a first optical arm 20 which comprises a power control element 21 and a polarization element 22, the element 21 comprising a delay blade, in this case a half-wave blade configured to introduce a delay of λ / 2 into the beam 3B, the element 22 being configured to linearly polarize the laser beam 3B,a second movable optical arm 30 which includes a motorized stage-type component 31 allowing modification of the arm's length and thus temporal control of the beam 3C relative to the beam 3B, in this example in the picosecond regime, the optical arm 30 also including a power control component 32 and a polarization component 33, component 32 including a delay plate, in this case a half-wave plate configured to introduce a delay of λ / 2 into the beam 3C, component 33 being configured to linearly polarize the laser beam 3C, the separator 18 being configured to recombine the beams 3B and 3C exiting the optical arms 20 and 30, a scanning component 41 of the galvanometer scanner type, a deflection component 42 including in this example a focusing lens known as "F-theta" having a focal length of 100 mm.,

[0045] In each of the two non-limiting embodiments which will now be described, a surface of a part is irradiated using the device 1 of lade so as to form structures known as "laser-irradiated surface structures" and, more specifically, structures called "laser-induced periodic surface structures (LIPSS)".

[0046] According to a first embodiment, the structures formed on the surface of part 100 are structures exhibiting a spatial periodicity between 300 nm and 700 nm, corresponding to periodic surface structures with a so-called low spatial frequency, typically a frequency less than half the wavelength of the laser.

[0047] To this end, device 1 can generally implement a process which includes a step of supplying part 100 as well as a structuring phase which can be carried out iteratively in order to successively irradiate different parts of the surface of part 100.

[0048] Without limitation, the structuring phase may include, for a given iteration: a step of generating the input laser beam 3 using femtosecond laser pulses generated by system 2 of device 1, in this example at a wavelength of 1030 nm and with a pulse duration of 230 fs and a rate of 50 kHz, a step of processing the input laser beam 3 using the processing system 4 of device 1, so as to form the output laser beam 5, a step of irradiating a part of the surface of the part 100 by the output laser beam 5.

[0049] In this non-limiting example, device 1 is implemented so that the fluence of the output laser beam 5 is on the order of 0.2 J / cm² and that, for a given iteration of the structuring phase, the surface of the part 100 is irradiated by an output laser beam 5 comprising twenty femtosecond pulses.

[0050] Each subsequent iteration of the structuring phase is preferably performed after relative displacement of the output laser beam 5 with respect to the part 100, so that the surface areas irradiated during successive structuring phases partially overlap. For example, the overlap rate could be on the order of 80% or 90%.

[0051] Within the framework of this first embodiment and with reference to the, the process described above makes it possible to structure a surface 110 of the part 100 such that the surface 100 comprises: a sub-layer 111 exhibiting mechanical and metallurgical defects induced by the laser, this sub-layer 111 being able to have a thickness not limited to between 5 nm and 50 µm, a so-called topographic layer 112 forming structures organized for example in the manner illustrated in the, X1 indicating a distance on the order of 5 µm, the structures exhibiting in this example a spatial periodicity and more generally a characteristic dimension between 300 nm and 700 nm (approximately 500 nm in the particular case of the), the thickness of the layer 112 thus being between 300 nm and 700 nm, corresponding to the average maximum height of the crests and troughs formed by these structures,this average maximum height can be measured over a sampling length of 1 µm, a layer 113 of metal oxide, in this non-limiting example of nickel oxide, crystalline or partially amorphous, the layer 113 having a thickness not limited to between 0.1 nm and 5 nm.

[0052] Such a surface 110 makes it possible to limit the permeability of the part 100 to hydrogen, taking into account its topographic layer 112, a fortiori in combination with the sub-layer 111, whose mechanical (dislocation density, residual stresses) and metallurgical (recrystallization) defects contribute to trapping hydrogen and reducing the overall diffusion kinetics, and with the oxide layer 113 which makes it possible to decrease the permeability to hydrogen typically up to 75% compared to a native oxide layer.

[0053] According to a second embodiment, the structures formed on the surface of part 100 are structures exhibiting a spatial periodicity between 1 nm and 100 nm, corresponding to periodic surface structures with a so-called high spatial frequency, typically a frequency greater than half the wavelength of the laser.

[0054] Part 100 according to this second embodiment and an example of a corresponding structuring process are described only according to their differences from the first embodiment, the preceding description applying by analogy.

[0055] In this second embodiment, device 1 is implemented so that the wavelength of the input laser beam is 800 nm, the duration of a pulse is 900 fs, the time between two pulses is 9 ps, the fluence of the output laser beam is 0.18 J / cm² and, for a given iteration of the structuring phase, part 100 is irradiated by a beam comprising twenty-five pulses.

[0056] In the context of this second embodiment and with reference to figures 2 and 4, device 1 is thus implemented so that: the sublayer 111 has in this non-limiting example a thickness between 4 nm and 8 nm, the topographic layer 112 forms structures organized in the non-limiting manner illustrated in the figure, X2 indicating a distance of the order of 500 nm, the structures exhibiting in this example a spatial periodicity and more generally a characteristic dimension between 1 nm and 100 nm (approximately 90 nm in the particular case of the), the thickness of layer 112 thus being between 1 nm and 100 nm, corresponding to the average maximum height of the crests and troughs formed by these structures, the metal oxide layer 113 has a non-limiting thickness between 0.1 nm and 5 nm.

[0057] In each of the two embodiments described above, the structures of the surface 110 of the part 100 are two-dimensional structures which are obtained by double polarization, in this case by means of the two optical arms 20 and 30 of the device 1. Of course, such periodic structures can be obtained using a device different from that of the.

[0058] In alternative embodiments, the surface 110 of the part 100 may include one-dimensional periodic structures as shown in Figures 5 and 6.

[0059] Lamontre of periodic surface structures with low spatial frequency which are generally designated by the acronym "LSFL" (from the English "low-spatial-frequency LIPSS"), X3 indicating a distance on the order of 5 µm.

[0060] Lamontre of periodic surface structures with high spatial frequency which are generally designated by the acronym "HSFL" (from the English "high-spatial-frequency LIPSS"), X4 indicating a distance on the order of 5 µm.

[0061] These structures generally appear as striations, with the distance between adjacent striations defining the spatial periodicity of these structures.

[0062] Such one-dimensional periodic structures can be obtained, among other possibilities, using a device differing primarily from that of the other in that it lacks the separators 16 and 18 as well as the optical arm 30. The processing system of this device thus comprises components similar to components 11, 12, 21, 22, 41, and 42 of device 1 of the other, the description of which applies here by analogy. Such a device allows for simple and linear polarization.

[0063] Without limitation, the structures of the lapeument can be obtained by irradiation with a laser beam for which the pulse duration is 250 fs, the fluence is 0.3 J / cm² and the number of pulses is thirty for a given iteration of the structuring phase.

[0064] Without limitation, the structures of the lapeument can be obtained by irradiation with a laser beam for which the pulse duration is 250 fs, the fluence is 0.3 J / cm² and the number of pulses is five for a given iteration of the structuring phase.

[0065] The invention is of course not limited to a part comprising surface structures such as those described in the preceding examples. Thus, in a variant not shown, the part of the invention may have a surface comprising non-periodic structures, that is to say structures devoid of spatial periodicity, for example structures known by the Anglo-Saxon name "spikes", said characteristic dimension typically corresponding in this case to the thickness of the layer 112 (cf.) formed by such non-periodic structures and generally being between 1 nm and 1000 nm.

[0066] The invention improves the strength, durability, and efficiency of hydrogen-related devices. For example, it facilitates the design of pipelines suitable for transporting hydrogen under pressure, as well as the development of reliable storage units. The invention thus provides a versatile solution for addressing the technological challenges associated with hydrogen, particularly in the areas of hydrogen transport, storage, and production.

Claims

Metallic part (100), comprising a surface (110) intended to limit the permeability of the part (100) to hydrogen, said surface (110) forming: structures (112) which have a spatial periodicity, and / or an average distance between two vertices formed by two of said structures, of between 1 nm and 5000 nm, for example between 300 nm and 700 nm, or between 1 nm and 100 nm, a layer of oxide(s) (113) comprising at least one metallic oxide and having a thickness of between 0.1 nm and 100.0 nm, preferably between 5.0 nm and 50.0 nm. Part (100) according to claim 1, wherein said structures (112) have an average height less than or equal to 1000 nm, preferably less than or equal to 500 nm. Part (100) according to claim 1 or 2, wherein the oxide layer(s) (113) comprises an iron oxide and / or a chromium oxide and / or a nickel oxide. Part (100) according to any one of claims 1 to 3, wherein the oxide layer(s) (113) is at least partially amorphous. Device for manufacturing and / or storing and / or transporting hydrogen, comprising at least one part (100) according to any one of claims 1 to 4. A method for structuring a part (100) according to any one of claims 1 to 4, comprising a step of supplying the part (100) and one or more iterations of a phase of structuring respective parts of a surface (110) of the part (100), the structuring phase comprising the following steps: generation (2) of an input laser beam (3) using laser pulses, preferably femtosecond, processing (4) of the input laser beam so as to form an output beam (5), the processing step (4) preferably comprising linear or circular or radial or elliptical or azimuthal or crossed polarization of the input laser beam (3), irradiation of a part of the surface (110) of the part (100) by the output laser beam (5). A method according to claim 6, wherein, during at least one iteration of the structuring phase, the irradiation step is implemented so as to produce on the surface (110) of the part (100) structures (112) having a spatial periodicity, and / or an average distance between two vertices formed by two of said structures, of between 1 nm and 1000 nm, for example between 300 nm and 700 nm, or between 1 nm and 100 nm. Method according to claim 6 or 7, wherein, during at least one iteration of the structuring phase, the output laser beam (5) comprises a number of pulses ranging from 1 to 100000. A method according to any one of claims 6 to 8, wherein, during at least one iteration of the structuring phase, the fluence of the output laser beam (5) is in a range from 0.01 J / cm² to 5 J / cm².

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