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

Abstract

Metallic part (100) comprising a surface (112) with reduced permeability to hydrogen. Method for structuring such a part (100) by femtosecond laser irradiation. Figure for the abstract: Fig. 2

Description

Title of the invention: Metal part structured by laser irradiation for a device for transporting and / or storing and / or manufacturing hydrogen Technical field

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

[0002] The invention is of particular interest, in no way limiting, in the sectors of manufacturing, transport and storage of hydrogen. State of the art

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

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

[0005] There is a need to reduce such risks. Statement of the invention

[0006] For this purpose, the invention relates to a metal 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 of between 1 nm and 5000 nm, - a layer of oxide(s) having a thickness of between 0.1 nm and 100.0 nm.

[0007] In a first embodiment variant, the spatial periodicity and / or the characteristic dimension of said structures is between 300 nm and 700 nm.

[0008] In a second embodiment, the spatial periodicity and / or the characteristic dimension of said structures is between 1 nm and 100 nm.

[0009] In a non-limiting manner, said characteristic dimension may 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 ones of said structures.

[0010] In one embodiment, said layer of oxide(s) has a thickness of between 5.0 nm and 50.0 nm.

[0011] In one embodiment, said structures have an average height less than or equal to 1000 nm, preferably less than or equal to 500 nm.

[0012] In one embodiment, said structures are formed by femtosecond laser irradiation.

[0013] In one embodiment, the layer of oxide(s) comprises at least one metal oxide, for example an iron oxide and / or a chromium oxide and / or a nickel oxide.

[0014] In one embodiment, the layer of oxide(s) is at least partially amorphous.

[0015] Said part may be entirely or partially made from one or more oxides of said oxide layer(s).

[0016] Thus, in a non-limiting manner, according to a first variant embodiment, all the parts of the part can comprise at least one common metal oxide.

[0017] 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.

[0018] The invention also relates to a device for manufacturing and / or storing and / or transporting hydrogen, comprising at least one part as defined above.

[0019] The invention also relates to a method of structuring such a part.

[0020] In one embodiment, the method comprises a step of providing the part and one or more iterations of a phase of structuring respective portions of a surface of the part.

[0021] The structuring phase may include the following steps: - generation of an input laser beam using laser pulses, - processing the input laser beam so as to form a beam of exit, - irradiation of a part of the surface of the part by the output laser beam.

[0022] Preferably, said laser pulses are femtosecond pulses.

[0023] The pulses may be of a different order of magnitude, for example picosecond pulses.

[0024] In one embodiment, the processing step comprises linear or circular or radial or elliptical or azimuthal or cross polarization of the input laser beam.

[0025] Of course, a combination of several polarizations including those described above can be implemented.

[0026] In a non-limiting manner, the input laser beam may have an intensity distribution of the Gaussian, Bessel, or even annular type.

[0027] 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 of between 1 nm and 1000 nm, for example of between 300 nm and 700 nm, or of between 1 nm and 100 nm.

[0028] 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.

[0029] 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.

[0030] The invention makes it possible to reduce the absorption of hydrogen in a part, by structuring or texturing a metal surface of this part.

[0031] The inventors believe that the invention typically makes it possible to provide a metal part absorbing sixteen times less hydrogen than a polished metal part.

[0032] Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows. Brief description of the figures

[0033] The following detailed description refers to the accompanying drawings in which: - [Fig.l] is a schematic view of a surface texturing device by femtosecond laser irradiation; - [Fig.2] is a schematic view of a metal part comprising a surface structured in accordance with the invention; - [Fig.3] shows a surface of a part comprising two-dimensional periodic surface structures with low spatial frequency; - [Fig.4] shows a surface of a part comprising two-dimensional periodic surface structures with high spatial frequency; - [Fig.5] shows a surface of a part comprising one-dimensional periodic surface structures with low spatial frequency; - [Fig.4] shows a surface of a part comprising one-dimensional periodic surface structures with high spatial frequency. Detailed description of embodiments

[0034] The invention relates to a part, in particular a metal 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 a tap of a network of hydrogen transport, or more generally a part equipping or forming part of a device for manufacturing and / or storing and / or transporting hydrogen.

[0035] The part of the invention has a structured, or textured, surface so as to limit the permeability of the part to hydrogen.

[0036] The following description presents a non-limiting technique for producing structures on the surface of such a part by femtosecond laser irradiation.

[0037] [Fig. 1] shows a non-limiting example of a femtosecond laser irradiation device 1 that can be implemented within the framework of the invention.

[0038] With reference to [Fig.l], the device 1 comprises a system 2 configured to generate an input laser beam 3, as well as a system 4 configured to process the input laser beam 3 in order to form an output laser beam 5 capable of irradiating a surface of a part 100.

[0039] In a manner known per se, the generation 2 system comprises a femtosecond laser source, i.e. a laser emitting light in pulses of very short durations, which can typically be between 1 fs and 1 ns, as well as a diaphragm.

[0040] The system 2 is typically configured to be able to generate a beam with a wavelength X between 100 nm and 5000 nm.

[0041] The processing system 4 of the device 1 comprises a series of optical components including, in the example of [Fig.l]: - a power control member 11 comprising a delay plate, in this case a half-wave plate configured to introduce a delay of X / 2 into the beam 3, - a polarization member 12 comprising a thin film polarizer, - two separators 16 and 18, the separator 16 being configured to separate the input beam 3A processed by organs 11 and 12 into two beams 3B and 3C in a 50 / 50 ratio, - a first optical arm 20 which comprises a power control member 21 and a polarization member 22, the member 21 comprising a delay plate, in this case a half-wave plate configured to introduce a delay of X / 2 into the beam 3B, the member 22 being configured to polarize the laser beam 3B linearly, - a second movable optical arm 30 which comprises a member 31 of the motorized stage type making it possible to modify the length of the arm 30 and thus to temporally control the beam 3C with respect to the beam 3B, in this example in the picosecond regime, the optical arm 30 also comprising a power control member 32 and a polarization member 33, the member 32 comprising a delay plate, in this case a plate half-wave configured to introduce a delay of X / 2 into the 3C beam, the member 33 being configured to polarize the 3C laser beam linearly, - the separator 18 being configured to recombine the 3B and 3C beams leaving the optical arms 20 and 30, - a scanning member 41 of the galvanometer scanner type, - a deflection member 42 comprising in this example a lens of focusing known as “F-theta” having a focal length of 100 mm.

[0042] 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 [Fig. 1] so as to form structures known as “laser-irradiated surface structures” and, more specifically, structures called “laser-induced periodic surface structures (LIPSS)”.

[0043] According to a first embodiment, the structures formed on the surface of the part 100 are structures having a spatial periodicity of 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.

[0044] For this purpose, the device 1 can generally implement a method which comprises a step of providing the 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 the part 100.

[0045] In a non-limiting manner, the structuring phase may comprise, for a given iteration: - a step of generating the input laser beam 3 using femtosecond laser pulses generated by the system 2 of the 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 the 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.

[0046] In this non-limiting example, the device is implemented so that the fluence of the output laser beam 5 is of 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.

[0047] Each possible new iteration of the structuring phase is preferably carried out after relative displacement of the output laser beam 5 with respect to the part. 100, so that the surface parts respectively irradiated during successive structuring phases partially overlap. For example, the coverage rate can be of the order of 80% or 90%.

[0048] In the context of this first embodiment and with reference to [Fig.2], the method described above makes it possible to structure a surface 110 of the part 100 so that the surface 100 comprises: - a sub-layer 111 having mechanical and metallurgical defects induced by the laser, this sub-layer 111 being able to have a thickness of between 5 nm and 50 pm, - a so-called topographic layer 112 forming structures organized for example in the manner illustrated in [Fig. 3], XI indicating a distance of the order of 5 pm, the structures having in this example a spatial periodicity and more generally a characteristic dimension of between 300 nm and 700 nm (approximately 500 nm in the particular case of [Fig. 3]), the thickness of the layer 112 thus being between 300 nm and 700 nm, corresponding to the average maximum height of the peaks and valleys formed by these structures, this average maximum height being able to be measured over a sampling length of 1 pm, - a layer 113 of metal oxide, in this non-limiting example of nickel oxide, crystalline or partially amorphous, the layer 113 possibly having a non-limiting thickness of between 0.1 nm and 5 nm.

[0049] Such a surface 110 makes it possible to limit the permeability of the part 100 to hydrogen, taking into account its topographical layer 112, a fortiori in combination with the sub-layer 111, whose mechanical defects (dislocation density, residual stresses) and metallurgical defects (recrystallization) contribute to trapping the hydrogen and reducing the overall diffusion kinetics, and with the oxide layer 113 which makes it possible to reduce the permeability to hydrogen typically by up to 75% compared to a native oxide layer.

[0050] According to a second embodiment, the structures formed on the surface of the part 100 are structures having a spatial periodicity of 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.

[0051] The part 100 according to this second embodiment as well as an example of a corresponding structuring method are described only according to their differences with respect to the first embodiment, the preceding description applying by analogy.

[0052] In the context of this second embodiment, the 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 duration 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, the part 100 is irradiated by a beam comprising twenty-five pulses.

[0053] In the context of this second embodiment and with reference to figures 2 and 4, the device 1 is thus implemented so that: - the sub-layer 111a in this non-limiting example has a thickness of between 4 nm and 8 nm, - the topographic layer 112 forms structures organized in the non-limiting manner illustrated in [Fig. 4], X2 indicating a distance of the order of 500 nm, the structures having in this example a spatial periodicity and more generally a characteristic dimension of between 1 nm and 100 nm (approximately 90 nm in the particular case of [Fig. 4]), the thickness of the layer 112 thus being between 1 nm and 100 nm, corresponding to the average maximum height of the peaks and valleys formed by these structures, - the layer 113 of metal oxide has a thickness of between 0.1 nm and 5 nm, without limitation.

[0054] 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 thanks to 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 [Fig.l].

[0055] In alternative embodiments, the surface 110 of the part 100 may comprise one-dimensional periodic structures such as those shown in FIGS. 5 and 6.

[0056] [Fig.5] shows 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 of the order of 5 pm.

[0057] [Fig.6] shows high spatial frequency periodic surface structures which are generally designated by the acronym "HSFL" (from the English "high-spatial-frequency LIPSS"), X4 indicating a distance of the order of 5 pm.

[0058] These structures generally appear in the form of striations, the distance between adjacent striations defining the spatial periodicity of these structures.

[0059] Such one-dimensional periodic structures can be obtained, without limitation, using a device which differs mainly from that of [Fig. 1] in that it is devoid of the separators 16 and 18 as well as the optical arm 30, the processing system of this device thus comprising components similar to components 11, 12, 21, 22, 41 and 42 of the device 1 of [Fig.l] the description of which applies here by analogy. Such a device makes it possible to achieve simple and linear polarization.

[0060] In a non-limiting manner, the structures of [Fig.5] 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.

[0061] In a non-limiting manner, the structures of [Fig.6] 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.

[0062] 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 under the Anglo-Saxon name "spikes", said characteristic dimension typically corresponding in this case to the thickness of the layer 112 (cf. [Fig. 2]) formed by such non-periodic structures and may generally be between 1 nm and 1000 nm.

[0063] The invention makes it possible to improve the strength, durability and efficiency of devices dedicated to hydrogen. For example, it makes it easier to design pipelines suitable for transporting pressurized hydrogen, or to create reliable storage units. The invention thus provides a versatile solution for meeting the technological challenges associated with hydrogen, particularly in the fields of transport, storage and production of hydrogen.

Claims

Claims

1. A metal 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 a characteristic dimension of between 1 nm and 5000 nm, for example of between 300 nm and 700 nm, or of between 1 nm and 100 nm, - a layer of oxide(s) (113) having a thickness of between 0.1 nm and 100.0 nm, preferably of between 5.0 nm and 50.0 nm.

2. Part (100) according to claim 1, in which said structures (112) have an average height less than or equal to 1000 nm, preferably less than or equal to 500 nm.

3. The part (100) of claim 1 or 2, wherein said structures (112) are formed by femtosecond laser irradiation.

4. Part (100) according to any one of claims 1 to 3, in which the layer of oxide(s) (113) comprises at least one metal oxide, for example an iron oxide and / or a chromium oxide and / or a nickel oxide.

5. Part (100) according to any one of claims 1 to 4, in which the layer of oxide(s) (113) is at least partially amorphous.

6. Device for manufacturing and / or storing and / or transporting hydrogen, comprising at least one part (100) according to any one of claims 1 to 5.

7. A method of structuring a part (100) according to any one of claims 1 to 5, comprising a step of providing 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: - generating (2) an input laser beam (3) using laser pulses, preferably femtosecond, - processing (4) the input laser beam so as to form an output beam (5), the processing step (4) preferably comprising a linear polarization or circular or radial or elliptical or azimuthal or crossed of the input laser beam (3), - irradiation of a part of the surface (110) of the part (100) by the output laser beam (5).

8. Method according to claim 7, in which, 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 a characteristic dimension of between 1 nm and 1000 nm, for example of between 300 nm and 700 nm, or of between 1 nm and 100 nm.

9. A method according to claim 7 or 8, wherein, during at least one iteration of the structuring phase, the output laser beam (5) comprises a number of pulses ranging from 1 to 100,000.

10. A method according to any one of claims 7 to 9, 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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