Installation for depositing or modifying a solid material from a vapour phase, corresponding implementation method and manufacturing assembly

Abstract

The invention relates to an installation which includes a treatment chamber (5) that forms an internal volume for treating the substrate (SUB) in the form of a sheet or strip, the inlet (E') and the outlet (S') of the installation communicating with the inlet (E) and the outlet (S) of the treatment chamber, respectively; means (6) for injecting an active gas mixture into the volume for treating the substrate, intended for depositing, growing or modifying the material; and means (7) for heating the internal volume of the treatment chamber. The treatment chamber (5) extends vertically overall, the inlet and the outlet of the treatment chamber being located at different heights (ZE, ZS), while free spaces (37, 38) are provided on either side of the path of the substrate, in order to separate the respective faces of the substrate from the front walls (50, 51) of the chamber, the injection means and the heating means being provided on the front walls (50, 51) and the injection means being equipped with cooling means (65, 66).

Description

[0001] DESCRIPTION

[0002] Title: Installation for the deposition or modification of a solid material from a vapor phase, implementation method and corresponding manufacturing assembly

[0003] Technical field of the invention

[0004] The invention relates to the field of reactors for the deposition or modification of solid materials from a vapor phase. More specifically, it relates to reactors for the continuous deposition of nanostructured materials, such as carbon nanotubes or nanofibers, from a vapor phase onto a solid substrate. In particular, it relates to an installation for manufacturing a material comprising carbon nanotubes or nanofibers fixed to a substrate, notably vertically aligned carbon nanotubes (VACNTs), deposited typically in a scrolling fashion. Such a material may be composite in nature, it being understood that the invention is applicable to other types of materials. The invention also relates to a method for implementing this installation, as well as an assembly for manufacturing a nanostructured material, which includes this installation.

[0005] State of the art

[0006] Carbon nanotubes (often abbreviated as "CNTs") have walls formed by graphitic monolayers (graphene sheets). Whether single-layered or multi-layered, they exhibit unique mechanical, thermal, electronic, and structural properties; these properties reflect their strong structural anisotropy. Numerous applications have been envisioned that take advantage of these particular properties. For example, polymer materials loaded with nanotubes have been developed and used in the manufacture of tennis rackets, which benefit from mechanical properties combining strength and flexibility.We also considered taking advantage of their high electronic and thermal conductivity in the length direction of the tubes and conversely a lower electronic and thermal conductivity in the transverse direction to the nanotubes which makes them a particularly interesting and unique anisotropic material for applications in the fields of energy (supercapacitors, batteries, fuel cell or electrolyzer and more generally support for catalysts of all kinds, organic, inorganic, biological).

[0007] For about twenty years, it has been possible to deposit vertically aligned carbon nanotubes (CNTs) onto a substrate; this product is known as VACNT (Vertically Aligned Carbon Nanotubes) and is described as a carpet, forest, or array. Hu et al. ("3-omega measurements of vertically oriented carbon nanotubes on silicon," J. Heat Transf. 128 (2006) pp. 1109-1113) describe the possibility of using a carpet of VACNTs as a thermal interface material (TIM). Thermal interface materials are used to dissipate the heat produced by electronic components with which they are in thermal contact. The authors observe that, in a carpet of VACNTs deposited on a silicon crystal, the thermal conductivity along the thickness (i.e., parallel to the length of the aligned tubes) is much higher than that of commercially available thermal interface materials.

[0008] A process for the continuous fabrication of nanostructures aligned on a moving support is known from FR 3 013 061 A1. This process comprises conveying the support through a heated chamber and synthesizing the nanostructures aligned with the support in this chamber by catalytic chemical vapor deposition. According to this process, the heated chamber is divided into at least two consecutive zones along the direction of support conveyance. The synthesis of the nanostructures results from heating and injection operations, in each of the aforementioned zones, of an aerosol stream containing a catalytic precursor and a source precursor of the nanostructure material to be formed, carried by a carrier gas.

[0009] Furthermore, US 2011 / 3182560 discloses a continuous CNT synthesis facility comprising a coating and drying area, a synthesis area, and a collection area. Within the synthesis area, the gas mixture is injected through tubes in a direction perpendicular to the substrate flow. Gas extraction lines are also provided on either side of the synthesis area to remove the gas in a direction also perpendicular to the substrate flow.

[0010] The applicant proposed, by WO 2017 / 187 080, a modular installation for manufacturing a material containing CNTs. According to this solution, the active mixture is conveyed in a first direction within the processing chamber by means of circulation. This active mixture can also be extracted from the chamber in a second direction by means of the same circulation means, which can be configured differently. Typically, the first direction is perpendicular to the direction of substrate flow, while the second direction is parallel to it. Although this solution is particularly satisfactory in terms of modularity, it does have some drawbacks. Specifically, it has been noted that it does not allow for optimal uniformity in the final material.This can be defined as the absence of spatial variations, within the plane of the substrate, in the material's properties once obtained. These properties include the number of tubes, their length, their density, and their diameter. More specifically, it would be desirable to improve the homogeneity of the VACNT deposition aligned on both faces of the substrate during the flow. Furthermore, if this reactor is used to deposit a thin layer of another material, for example, a pretreatment layer such as a metallic catalyst layer, its thickness is also not entirely homogeneous.

[0011] US 2018 / 0342740 describes an installation in which the substrate flows vertically. More specifically, from upstream to downstream, it includes a first injection zone, a buffer station, a second injection zone, and heating equipment. This US document, which references US 2004 / 063320, relates more specifically to reactions in which energy is supplied by plasma.

[0012] WO 2017 / 210575 discloses a multi-zone treatment kit intended for use in a deposition chamber. According to the teachings of this document, the injection is carried out in a direction that lies within the plane of the moving substrate. Consequently, there is a lack of homogeneity in the final deposition.

[0013] US 2024 / 167157 concerns a gas injector designed to deliver precursors. This document, which is more specifically aimed at the technical field of semiconductors, does not describe any reactor in practice that could incorporate the aforementioned injector.

[0014] Finally, JP 2014 152 049 relates to a device for processing carbon nanotubes, which are produced continuously from a substrate with an oxidant. In this device, the nanotubes circulate in a horizontal direction.

[0015] In view of the foregoing, one objective of the present invention is therefore to remedy, at least partially, the disadvantages of the prior art mentioned above.

[0016] Another objective of the invention is to provide an installation that, while allowing for simple implementation, guarantees an improvement in the final quality of a material containing CNTs, in particular an improvement in the uniformity of this material. Another objective of the invention is to provide such an installation that, while allowing the coating of the two opposite faces of the treated substrate with two materials that may be identical or different, is suitable for many types of processing.

[0017] Yet another objective of the invention is to propose such an installation which, while providing the improvements presented in the preceding paragraphs, allows the implementation of a continuous "roll to roll" type process in which the catalyst and the reactive gases are injected simultaneously.

[0018] Objects of the invention

[0019] According to the invention, at least one of the above objectives is achieved by means of an installation for the deposition, growth, or modification of a material on a substrate, in particular a composite material comprising nanotubes or nanofibers fixed to a substrate, such as carbon nanotubes or nanofibers, this installation comprising at least one processing chamber, or reaction chamber, which forms an internal volume for processing said substrate which is in the form of a sheet or strip, this processing chamber comprising an inlet and an outlet, an inlet and an outlet of the installation, this inlet and outlet of the installation communicating respectively with the inlet and outlet of said processing chamber, means for injecting an active gas mixture into the processing volume of the substrate, this gas mixture being intended for the deposition, growth, or modification of said material, heating means,capable of heating the internal volume of the treatment chamber, said installation being characterized in that the treatment chamber extends in a generally vertical manner, the inlet and outlet of the treatment chamber being located at different altitudes, free spaces are provided, in operation, on either side of the substrate path, the free spaces separating in operation each the respective faces of the substrate with respect to front walls facing the chamber, said front walls bordering the internal volume of substrate treatment, both the injection means and the heating means being provided on said front walls, and the injection means are equipped with cooling means, which are capable of cooling these injection means.

[0020] This installation forms the first object of the invention. It can be implemented with numerous variations.

[0021] In variations, which can be combined with each other:

[0022] - the front walls are arranged opposite each other without the interposition of a substrate support base, so as to delimit said free spaces in service;

[0023] - the installation also includes thermal insulation means, suitable for isolating the injection means from the heating means;

[0024] - the injection means comprise several injection modules, each injection module comprising at least one circulation channel allowing the circulation of the heat transfer fluid, as well as at least one injection channel allowing the transport of the gaseous mixture, this injection channel opening onto at least one injection nozzle; in this variant each injection module may comprise a body, in which the circulation channel and the injection channel are provided, as well as a thermal insulation casing extending to the periphery of at least a part of this body, said casing being said thermal insulation means;

[0025] - the heating means comprise several heating modules, while the injection means comprise several injection modules, the heating modules and the injection modules being arranged alternately on at least the majority of the same front wall; in this variant, on at least the majority of each front wall, the heating modules and the injection modules can advantageously be placed in a staggered pattern.

[0026] In one embodiment, the installation according to the invention may include a lower zone bordered by said inlet of the installation and said inlet of the treatment chamber, respectively the outlet of the installation and the outlet of the treatment chamber, as well as an upper zone bordered by said outlet of the installation and said outlet of the treatment chamber, respectively the inlet of the installation and the inlet of the treatment chamber, this lower zone and this upper zone being arranged on either side of an intermediate zone comprising the treatment chamber, the installation having, in side view, a C shape or an S shape, or an L shape, or an inverted L shape, or an I shape.

[0027] This embodiment can be combined with all the variants described above.

[0028] The installation according to the invention advantageously lacks a base that could come into contact with the substrate in use; thus, the substrate is heated primarily by thermal radiation, which ensures better thermal homogeneity than mechanical friction. In other words, the heating means are advantageously positioned directly opposite the substrate in use, that is, without the interposition of a mechanical element such as a base. The active gas mixture within the treatment chamber is heated solely by thermal radiation.

[0029] Advantageously, the treatment chamber is symmetrical about a vertical axis.

[0030] According to an advantageous embodiment of the invention, the installation may comprise a main frame equipped with both said inlet and said outlet, an insert adapted to cooperate with the main frame, and removable fastening means between this frame and this insert. In this embodiment, the frame and the inserts may have respective recesses, forming said processing chamber.

[0031] Another object of the invention is a method for implementing the above installation, in which:

[0032] - the substrate is moved through said chamber in said vertical direction, maintaining said free spaces between each face of the substrate and a respective front wall facing the chamber

[0033] - The internal volume of the treatment chamber is heated by means of the heating devices

[0034] - An active gaseous mixture is injected into the chamber's interior volume via injection means, while the injection means are cooled by means of the heat transfer fluid circulation system, so as to form carbon nanotubes preferentially on the substrate surface. Advantageously, carbon nanotubes can be formed on both opposite sides of the substrate surface; these nanotubes may be of the same or different types.

[0035] Yet another object of the invention is an assembly for the deposition, growth, or modification of a material on a substrate, in particular a composite material, in particular a composite material comprising nanotubes or nanofibers fixed to a substrate, such as carbon nanotubes or nanofibers, said assembly comprising

[0036] - an installation according to the first object of the invention, possibly taken according to any of its variants and combinations of variants,

[0037] - means for moving the substrate intended to form said material along the installation,

[0038] - means of supplying a gaseous mixture, capable of supplying the injection means with a gaseous mixture,

[0039] -means for admitting a heat transfer fluid, capable of admitting the heat transfer fluid into the circulation means equipping the injection means.

[0040] Description of the figures

[0041] The invention will be described below, with reference to the accompanying drawings, given solely by way of non-limiting examples, in which:

[0042] [Fig. 1] is a schematic view, illustrating from above an assembly for the manufacture of a material comprising carbon nanotubes, according to the invention.

[0043] [Fig. 2] is a schematic view illustrating more particularly, side view, a manufacturing installation according to the invention, which belongs to the manufacturing assembly illustrated in figure 1.

[0044] [Fig. 3] is a schematic side view, analogous to figure 2, separately illustrating certain constituent elements of the manufacturing installation according to the invention.

[0045] [Fig. 4] is a schematic view, illustrating a chassis belonging to the manufacturing facility of Figures 2 and 3, according to arrow IV on Figure 3.

[0046] [Fig. 5] is a cross-sectional view along line VV in Figure 4.

[0047] [Fig. 6] is a vertical cross-sectional view, illustrating on a larger scale the upper and lower parts of the installation shown in Figures 2 to 5.

[0048] [Fig. 7] is a cross-sectional view, similar to Figure 5 but on a larger scale, illustrating more precisely the lateral part of the installation in Figures 2 to 6. [Fig. 8] is a perspective view, illustrating a gas mixture injection module equipping the installation in the previous figures.

[0049] [Fig. 9] is a schematic view, analogous to figure 2, illustrating the implementation of the installation according to the invention, as well as the changes in direction of the substrate at the inlet and outlet of the chamber.

[0050] [Fig. 10] is a schematic view, analogous to figure 2, illustrating another possible S-shaped geometry of the installation according to the invention.

[0051] [Fig. 11] is a schematic view, analogous to figure 2, illustrating another possible L-shaped geometry of the installation according to the invention.

[0052] [Fig. 12] is a schematic view, analogous to figure 2, illustrating another possible geometry, in the shape of an inverted L, of the installation according to the invention.

[0053] [Fig. 13] is a schematic view, analogous to figure 2, illustrating another possible I-shaped geometry of the installation according to the invention.

[0054] [Fig. 14] is a graph on which are plotted different curves illustrating the variations in substrate temperature, as a function of the distance separating the substrate from the surface of the facing walls, for different temperatures of these walls.

[0055] [Fig. 15] is a schematic view, schematically illustrating the staggered arrangement of the heating and injection modules, according to an advantageous variant of the invention.

[0056] [Fig. 16] is a schematic view, analogous to figure 15, illustrating an arrangement in which each heating or injection module faces a corresponding module of the same type.

[0057] The following numerical references are used in this description

[0058] I Manufacturing Set

[0059] I. Installation according to the invention 5. Treatment chamber

[0060] 6 Injection Modules 7 Heating Modules

[0061] 8 Corner bearing 10 Lower zone

[0062] II Front edge of 10 12 Base of 1 (lower wall of 10)

[0063] 14 Lower corridor 15, 16 Layers of plates

[0064] 20 Upper zone 21 Front edge of 20

[0065] 22 Roof of 1 (upper wall of 20) 24 Upper corridor

[0066] 25,26 Plate Layers

[0067] 30 Treatment zone (intermediate) 31 Bottom of 1 (rear wall of 30)

[0068] 35, 36 Additional layers 37, 38 Spaces 40 Main frame 41, 46 Recess

[0069] 42.47 Shoulders delimited by 41.46 45 Insert

[0070] 50, 51 Front wall of 5 52, 53 Side wall of 5

[0071] 54.55 Lower and upper walls of 5 60 Body of 6

[0072] 61 Thermal insulation cladding 62 Edge of 60

[0073] 63 Injection channel into 60 64 Injection nozzle

[0074] 65,66 Heat transfer fluid circulation channels

[0075] 80, 81 Angle brackets of 8 82 Path for the passage of the substrate

[0076] 83, 84 Orifices in 81 86 Housing

[0077] 87 Suction Means

[0078] 200 Perimeter wall 202 Access gate of 200

[0079] 300 Gaseous compound feed unit 302 Pipe opening into 300

[0080] 400 Gaseous compound outlet unit 402 Pipe leading into 400

[0081] 500 Heat transfer fluid reservoir 502, 504 Pipe

[0082] 600 Substrate scrolling means 700 Control unit

[0083] Detailed description

[0084] The accompanying figures describe an installation for manufacturing a material comprising carbon nanotubes, which conforms to the invention, and a manufacturing assembly comprising this installation. With reference to Figure 1, this manufacturing assembly, designated by reference numeral I, essentially comprises:

[0085] - the manufacturing installation according to the invention, designated as a whole by reference 1

[0086] - a perimeter wall 200, which is equipped with an access door 202

[0087] - a unit 300 allowing the supply of gaseous compounds, towards installation 1;

[0088] - a unit 400 allowing the release of gaseous compounds, outside of this installation 1;

[0089] - a 500 reservoir containing a heat transfer fluid;

[0090] - means 600 enabling the scrolling of a SUB substrate, intended to be processed within installation 1; and

[0091] - a 700 control unit.

[0092] With reference to Figure 2, installation 1 generally has a C-shape when viewed from the side. Based on the direction of substrate flow, we can distinguish a lower zone 10, an upper zone 20, and a treatment or intermediate zone 30. By convention, we denote: - 11 and 21 as the front edges of the installation, which correspond to the front edges of zones 10 and 20,

[0093] - 12 the base of the installation, which corresponds to the lower wall of the upstream zone 10,

[0094] - 22 the roof of the installation, which corresponds to the upper wall of the downstream zone 20,

[0095] - 31 the bottom of the installation, which corresponds to the rear wall of the treatment area 30.

[0096] According to an advantageous feature of the invention, the installation 1 comprises a main frame 40, located at the front, and an insert 45 located at the rear. Advantageously, the frame 40 and the insert 45 are removably attached to each other. For this purpose, any suitable type of attachment is provided, in particular by locking with a latch. Furthermore, this attachment is ensured in a sealed manner to prevent any ambient air from entering the treatment chamber described below. To ensure this seal, any suitable means may be employed, in particular the use of high-temperature resistant gaskets, for example, made of vermiculite. In Figure 2, the frame and the insert are assembled together, whereas in Figure 3, they are separated.

[0097] This frame and insert have recesses 41 and 46 respectively, which extend over the entire height of the processing area 30, but only across part of its width. Referring to Figure 5, the shoulders delimited by these recesses are denoted 42 and 47 in the horizontal direction. The respective depths of the above recesses, typically equal, are also denoted e41 and e46. These recesses define a processing chamber 5, along which the substrate is intended to move. This processing chamber is symmetrical about a vertical axis Z5, visible in Figure 4.

[0098] In accordance with an advantageous feature of the invention, the installation is equipped with a plurality of injection modules 6, the structure of which will be detailed below. Each of these modules is capable of injecting, into the internal volume of the treatment chamber 5, a so-called active gas mixture of any suitable type, the nature of which will be detailed below. Furthermore, the installation is also equipped with a plurality of heating modules 7, enabling the internal volume of the treatment chamber to be heated in order to enhance the intended reaction. These heating modules, which are of a conventional type, are not illustrated in detail. Each module typically comprises a heating element, which can be heated by means of a resistor. This heating element is associated, for example, with a temperature probe, such as a thermocouple or similar device.

[0099] As shown in Figure 6, the injection modules 6 and the heating modules 7 are located on opposite front walls of the treatment chamber. On each front wall, the different modules are arranged alternately. Thus, on both front walls 50 and 51, there is an alternating succession of injection modules and heating modules. Figure 6 illustrates, on wall 50, the injection modules 6a to 6m and the heating modules 7a to 7n, and on the opposite wall 51, the injection modules 6'a to 6'm and the heating modules 7'a to 7'n.

[0100] Typically, the number n of heating modules 7, present at each wall, is between 6 and 30. Preferably, these different modules are staggered over at least a major part of the height h5 of the treatment chamber 5. In other words, opposite a given injection module present on the first wall 50, for example 6c, there is a heating module 7'd on the opposite wall 51. Furthermore, opposite a given heating module present on the first wall 50, for example 7c, there is an injection module 6'c on the opposite wall 51.

[0101] Advantageously, the modules are not staggered at the upper and lower ends of chamber 5. As shown in Figure 6, the lower heating modules, 7a and 7'a, are positioned opposite each other, as are the upper heating modules 7n and 7'n. Furthermore, the lower injection modules 6a and 6'a are positioned opposite each other, while being located immediately above the heating modules 7a and 7'a. Similarly, the upper injection modules 6m and 6'm are positioned opposite each other, while being located immediately below the heating modules 7n and 7'n.

[0102] According to an advantageous feature of the invention, the treatment chamber is symmetrical about a median horizontal axis, denoted X1 in Figure 6. This allows for reversible use of the chamber, meaning that the substrate can be treated by flowing not only from bottom to top, but also from top to bottom. In the case of bottom-up flow, the substrate is first heated by modules 7a and 7'a before receiving the gas via injection modules 6a and 6'a. Similarly, in the case of top-down flow, the substrate is first heated by modules 7n and 7'n before receiving the gas via injection modules 6m and 6'm. In other words, regardless of the direction of substrate flow, it is first heated before receiving the active gas.

[0103] We will now describe, particularly with reference to Figure 8, an injection module 6, it being understood that all modules have an identical structure. Module 6 comprises, firstly, a parallelepiped-shaped body 60, elongated in shape. This body is surrounded by a casing 61, shown schematically, which can be of any type known per se. This casing is, for example, formed by a stack of plates. It has an overall C-shape, so that it does not cover one 62 of the edges of the body 60, which edge is called the injection edge. This casing 61 forms a means of thermal insulation, allowing the injection module to be isolated from adjacent heating modules, thus maintaining the injection module at the appropriate temperature.

[0104] The body 60 is hollowed out with various longitudinal channels, namely, firstly, an injection channel 63. This channel 63, which is located adjacent to the edge 62, communicates with a plurality of injection nozzles 64, each of which opens onto the edge 62. There are also two channels 65 and 66, opposite the injection edge, which are intended for the circulation of a heat transfer fluid. The attachment of each injection module 6 to the wall, 50 belonging to the frame 40 and 51 belonging to the insert 45 respectively, is achieved by all appropriate means, as illustrated in Figure 7.

[0105] Referring to Figure 9, d6 denotes the distance, or lack thereof, between two injection modules 6b and 6c belonging to the same front wall of chamber 5. This distance is measured, along the vertical axis, between the outlets of the injection nozzles 64 shown in Figure 8. Advantageously, this distance is between 30 mm and 200 mm, being particularly close to 120 mm. Advantageously, the distances between adjacent injection modules, located on the same front wall of the treatment chamber, are identical. It should be noted that, since the lower modules 6a, 6'a and the upper modules 6m, 6'm are placed opposite each other, the distance separating each of these modules from its adjacent module is, conversely, different.

[0106] With particular reference to Figures 1 and 7, we will now describe the means for the flow of both the gas mixture and the heat transfer fluid within each module. As these figures show, a pipe 302, which feeds gaseous compounds into the gas supply unit 300, extends in the vicinity of the injection modules 6. This pipe 302 communicates with fittings (not shown), each of which is associated with a respective injection module, so as to admit the gaseous compound into the injection channel 63 of Figure 8. At its end opposite the injection fitting (not shown), the channel 63 opens into an additional discharge fitting (also not shown). The various discharge fittings communicate with a pipe 402, visible in Figure 1, which opens into the discharge unit 400.

[0107] Furthermore, as shown schematically in Figure 1 and more precisely in Figure 7, two pipes 502 and 504 extend parallel to pipe 302 above. These pipes connect the heat transfer fluid reservoir 500 to a plurality of fittings, which are not shown. One of these fittings delivers heat transfer fluid into channel 65, while the other allows this fluid to be discharged from channel 66.

[0108] The lower zone 10 and the upper zone 20, respectively upstream and downstream in the case described below of a substrate moving from bottom to top in the treatment chamber, are each excavated by a substantially horizontal channel 14 and 24. The lower channel 14 extends from the front edge 11, at which point it delimits the inlet E' of the installation 1, to the inlet E of the treatment chamber 5 (see Figures 2, 3, and 6). Furthermore, the outlet S of this treatment chamber itself opens into the downstream channel 24, which extends to the other front edge 21 (see Figures 2 and 3), at which point it delimits the outlet S' of the installation 1.

[0109] Note, with reference in particular to the cross-sections in figures 4 and 5:

[0110] - 50 and 51 the opposite front walls of chamber 5, which correspond respectively to the bottom of each recess 41 46

[0111] - 52 and 53 the opposite side walls of chamber 5

[0112] - 54 and 55 the lower and upper walls of this chamber respectively.

[0113] Furthermore, we note, again with reference to figures 4 and 5:

[0114] -e5 the depth of the chamber, namely the smallest distance between the front walls 50, 51. This depth is equal to the sum between the depths e41 and e46, defined above.

[0115] -15 the width of the chamber, namely the smallest distance between the side walls 52, 53; and

[0116] -h5 the height of the chamber (see figure 2), namely the difference between the altitude ZS of the outlet S and the altitude ZE of the inlet of the processing chamber 5. In the case of a substrate flowing from top to bottom, the outlet is located below the inlet so that this difference in altitudes is negative: in this case, we consider the absolute value of this difference.

[0117] The installation 1 according to the invention is further equipped with means for thermally insulating the treatment chamber from the outside. To this end, layers of radiant plates are provided, the nature of which is similar to that of the stacks 61. Referring to Figure 6, layers 15 and 16 are shown, extending respectively above and below the corridor 14. Additional layers 35 and 36 are provided, respectively on the front face of the main frame 40 and on the rear face of the insert 45 (see Figure 7). Finally, further layers 25 and 26, similar to those 15 and 16, are positioned below and above the downstream upper corridor 24.

[0118] The installation also includes two corner bearings, 8 and 8', located respectively at the junction between the treatment chamber 5 and the downstream corridor, and at the junction between the upstream corridor and this treatment chamber. We will now briefly describe, with reference to Figure 9, the upper corner bearing 8, it being understood that the other bearing 8' has a similar structure. In Figure 9, the mechanical elements of bearing 8', which are similar to those of bearing 8, are assigned the same numbers followed by the reference "'". Figure 9 is primarily intended to illustrate the displacement of the substrate, as well as the flow of the various gases. Consequently, it does not include some of the mechanical elements already described above, in particular those visible in Figure 6.

[0119] This corner bearing 8 is formed by two concentric arc-shaped angle brackets 80 and 81. These brackets define a curved path 82, forming an overall quarter circle, allowing the passage of the substrate SUB. The facing surfaces of the angle brackets are pierced with orifices 83, allowing the diffusion of a barrier gas of any suitable type. For this purpose, conduits (not shown) are provided, connected to a gas source (also not shown), which open into the aforementioned orifices 83.

[0120] In the vicinity of the outlet S (respectively the inlet E) of the treatment chamber, the opposing walls are pierced with orifices 84 (respectively 84') allowing the diffusion of a suitable inert gas. As above, pipes (not shown) extend between a gas source and these orifices 84. Finally, between the orifices 83 and 84, the installation includes a double wall defining a housing 86 equipped with suction means 87, illustrated schematically.

[0121] We will now describe, with particular reference to Figure 9, the implementation of the installation 1 according to the invention as presented above. The substrate can be, in particular, a metal sheet or strip, or even a carbon fabric. Its thickness can typically be between 15 µm and 200 µm, and its width between 10 mm and 1000 mm or more. The metal constituting the substrate is, for example, pure aluminum or any other grade of aluminum or any suitable aluminum alloy, or even stainless steel. Typically, the substrate SUB is moved using a roll-to-roll method. Such movement is achieved by means not shown, of any suitable known type. Figure 1 illustrates the movement of the substrate, respectively upstream of the installation 1 by the arrow F'sub, and downstream of this same installation by the arrow F”sub.

[0122] According to the main embodiment of the invention, the reaction is carried out on a moving substrate. In other words, the substrate is admitted at the inlet E of the installation, then moves continuously through the treatment chamber 5, undergoing the desired reaction, and is then discharged at the outlet S. In the illustrated example, the substrate SUB moves from bottom to top within the treatment chamber 5, as indicated by arrow Fsub in Figure 9. As an alternative embodiment (not shown), this substrate can be provided for to move from top to bottom within the treatment chamber, therefore in the opposite direction to that indicated by arrow Fsub. However, the upward direction of movement is preferred.

[0123] As a subsidiary variant, the substrate can be admitted to the installation's inlet and then brought to a stop at a precise location. Once stationary, it is subjected to the reaction, and once this reaction is complete, the substrate is set in motion again to be discharged through the installation's outlet. This main variant can be combined with this subsidiary variant. Modulation of the conveying speed can also be provided.

[0124] After being admitted at inlet E, the substrate progresses along the downstream corridor 14, where it is heated to a temperature suitable for the desired treatment. For example, in the case of an aluminum substrate, it is preferable that this temperature be below the metal's melting point, approximately 650 °C. To this end, the walls of this corridor 14 are equipped with heating elements (not shown in the figures). As the substrate progresses through the corridor 14, it carries with it, on both sides, a flow of ambient air, indicated by the arrows AIR. This ambient air flow opposes a barrier gas flow, indicated by the arrows B1, thus preventing any significant entry of this ambient air towards the treatment chamber 5. This barrier gas also performs an additional function: it improves the substrate's sliding relative to the walls opposite the corners 80' and 8T.

[0125] This substrate is then subjected to the actual treatment in reaction chamber 5. The reactive gases depend on the nature of the deposition or surface modification targeted. For depositing carbon nanotubes or nanofibers, the reactive gases may include, in addition to the carbon source gas, a catalyst precursor. The catalyst precursor can advantageously be ferrocene; it decomposes into nanometer-sized iron particles, which act as a catalyst for the formation of carbon nanotubes from the carbon source gas. The carbon source gas can be C2H2. The injection of reactive gases is implemented as follows. Since the preferred catalyst precursor (in this case, ferrocene) is a relatively poorly soluble solid, a sufficient concentration of catalyst precursor will not be obtained in solution to allow for its evaporation in the carbon source carrier gas before introduction.It is dissolved in toluene and injected as an aerosol in such a way that, before coming into contact with the substrate, these droplets evaporate completely. The gaseous phase in contact with the substrate is therefore homogeneous.

[0126] An alternative technique is the prior deposition of the catalyst (in this case, a thin layer of iron or another metal acting as a catalyst for VACNT deposition) onto the substrate surface in a separate process step; in this case, the carbon source gas can be introduced by means other than aerosol (i.e., in a homogeneous gaseous phase). This process can be advantageous for VACNTs of relatively small height, for example, between approximately 10 pm and approximately 150 pm.

[0127] The injection of reactive gases, via modules 6 and 6', is schematically represented by the respective arrows F6 and F6' in Figure 9. This injection is carried out horizontally, that is, perpendicular to the vertical direction of substrate movement. Furthermore, this injection is perpendicular to the substrate's Psub plane, which extends from the back to the front of the sheet. The various heating modules 7 and T are activated to maintain a suitable temperature in chamber 5 during the reaction itself. A suitable temperature range is typically between 400 °C and 900 °C. In practice, one or more temperature sensors, not shown in chamber 5, are used. The control means 700 then act on the heating modules depending on whether the measured temperature value is below or above a predefined setpoint.

[0128] According to the invention, the heating is implemented within spaces 37 and 38, each of which separates a front wall 50 and 51 from a respective face SUB1 and SUB2 of the substrate SUB. These spaces 37 and 38 are said to be free, meaning that they are not occupied by any intervening mechanical element; in other words, each front wall 50 and 51 is located directly opposite a respective face of the substrate, in the absence of such an intervening mechanical element. Advantageously, each dimension d1SUB and d2SUB, namely the smallest distance along a horizontal axis between each face SUB1 SUB2 and the opposite front wall 50, 51, is between approximately 1 mm and approximately 10 mm, preferably between approximately 1.5 mm and approximately 5 mm.

[0129] Figure 9 schematically illustrates the various injection modules 6 and 6', the various heating modules 7 and 7', and the front walls 50 and 51. These elements are, of course, consistent with the more detailed representation shown in Figure 6. Simultaneously, the heat transfer fluid circulates within the body 60 of each injection module. This maintains the walls of the injection nozzles at a sufficiently low temperature to prevent clogging due to carbon deposits. Typically, this temperature ranges from approximately 250 °C to approximately 350 °C. The heat transfer fluid can be an oil with a high heat capacity and sufficient temperature resistance.

[0130] In the vicinity of the outlet S of chamber 5, the substrate being treated carries with it, on both sides, the treatment gas. This gas is retained inside the chamber by the admission of neutral gas through orifices 84, as indicated by arrows N1. A gaseous fraction, composed of neutral gas and treatment gas, is drawn in by suction means 87, as indicated by arrow ASP in Figure 9. Downstream of the outlet S of treatment chamber 5, the treated substrate progresses along the inner faces of angles 80 and 81. Similar to what was described above, the admission of barrier gas via arrows B2 (see Figure 9) improves the substrate's sliding relative to the angles. Downstream of angles 80 and 81, the substrate then flows in the downstream channel 24.The walls of the latter are equipped with cooling means, allowing the temperature to gradually decrease as it moves towards the outlet S' of the installation.

[0131] The invention brings many advantages over the prior art, materialized by the reactor conforming to the teaching of WO 2017 / 187 080. It should be noted first of all that it is to the credit of the applicant, having identified the origin of the disadvantages of this specific prior art.

[0132] More specifically, the applicant observed that when the substrate circulates horizontally, as in WO 2017 / 187 080, the contact between the substrate and the base, which is theoretically perfect, is in practice variable. Indeed, even though the substrate is supported by a flat piece, this contact is not uniform because the substrate is thin, deformable, lightweight, and not perfectly flat. Furthermore, it is subjected to mechanical stresses and deformations during its passage through the reactor, due to its expansion and contraction under the effect of temperature changes. In other words, while there are indeed places where there is contact between the substrate and the base, there are also other places where these parts are separated from each other.

[0133] The applicant has sought to better understand the influence of this distance on the substrate temperature, which is likely to determine the uniformity of the properties. It should be noted that the more homogeneous the substrate temperature, the more uniform the final properties of the VACNTs.

[0134] Figure 14 illustrates the variations in substrate temperature (Tsub) as a function of the distance (sub) between the substrate and the adjacent surface, namely the base in the case of the reactor conforming to WO 2017 / 187 080. In Figure 14, the temperature (Tsub) increases from 540°C at a zero y-coordinate, with a difference of 10° between two horizontal dashed lines, while the distance (sub) increases from 0 at a zero x-coordinate, with a difference of one millimeter between two vertical dashed lines. Figure 14 also incorporates an additional parameter: the temperature of the wall opposite the substrate, but on the opposite side of the base, i.e., the perforated plates in this reactor.

[0135] This allows access to four curves, labeled C1 to C4, for different wall temperatures (TP1 to TP4) of the perforated plates mentioned above. It can be observed that, for a TP1 temperature of 460 °C, which we want to avoid exceeding to prevent any unwanted reactions in the injectors, the substrate temperature changes significantly with the distance from the substrate. More precisely, in a first region R1, the temperature drops rapidly from the point with zero abscissa, corresponding to perfect contact, down to a first threshold point close to 1.5 millimeters. Then, as the distance increases between this first threshold and a second threshold slightly less than 3 millimeters, the temperature decreases less significantly in a second region labeled R2. Finally, beyond the second threshold, in a region labeled R3, the substrate temperature no longer varies significantly.

[0136] For curve C4, with a perforated plate temperature of 600°C, the temperature is essentially invariant with respect to the submersible distance. For the intermediate curves C2 and C3, with respective temperatures of 520°C and 550°C, there are variations depending on the regions R1 to R3, which are, however, less significant than in the case of curve C1.

[0137] As can be seen from the above, the temperature differences between areas of the substrate in contact with the support and other areas of the same substrate located away from the support can reach several tens of degrees. These temperature differences can also affect areas of the substrate that are only a few centimeters apart. To achieve temperature uniformity in the horizontal configuration described in WO 2017 / 187 080, homogeneous contact could be ensured at the interface between the substrate and its support, across the entire surface of the latter. This could be achieved using a mechanical system that forces the substrate to be pressed against its support, such as a magnetic or pneumatic chuck. However, such a solution would be very difficult, if not entirely incompatible, with continuous movement of the substrate within the reactor.

[0138] Based on this observation, the inventors chose, as explained in the present description, to position the substrate vertically. This arrangement allows the substrate to be mechanically held in place by its own weight and the tension applied to it in the reactor's median plane, without any physical contact with a support component. This lack of physical contact is particularly advantageous, since the substrate's thermal equilibrium is achieved solely through heat transfer by radiation and convection. This allows for temperature uniformity across the substrate, which is virtually impossible to achieve when there is point contact between the substrate and one or more support components. Furthermore, the vertical arrangement of the substrate according to the invention represents a more technically practical solution than one involving a mandrel for plating the substrate onto its support.

[0139] Furthermore, thanks to the vertical positioning of the substrate in the treatment chamber, each substrate surface is separated from its respective opposite wall. Under these conditions, as shown in Figure 14, the invention allows operation in the R3 region regardless of the wall temperature TP. In other words, in this region of the curves, the substrate temperature undergoes little variation, even if the distance between the substrate and the opposite walls is not perfectly constant. This is advantageous with regard to the uniformity of the final substrate's properties.

[0140] In conclusion, the VACNT deposition on the substrate, obtained in accordance with the installation according to the invention, presents a much superior quality, in particular a significantly improved uniformity, compared to the prior art.

[0141] The invention also allows for the simultaneous coating of both opposite faces of the substrate with the synthesized material. Indeed, these two faces can be placed simultaneously under similar reaction conditions, particularly with regard to temperature, flow rate, and gas concentration. The materials deposited on both faces are typically identical; however, alternatively, mutually different reaction conditions can be used, allowing different materials to be deposited on opposite faces.

[0142] Furthermore, the use of cooling methods, particularly the circulation of a heat transfer fluid, prevents the injection nozzles from clogging due to unwanted carbon deposition. Consequently, the active gas mixture passing through the injection means does not exceed a threshold value beyond which such a risk of carbon deposition exists, while the temperature inside the treatment chamber is well above this threshold value. The alternation between, on the one hand, zones for injecting the gaseous reaction mixture and, on the other hand, zones for radiant heating constitutes a preferred feature of the invention. Accordingly, these zones are stabilized at different temperatures, respectively below and above the activation temperature threshold of the chemical reactions occurring during the synthesis (in this case, approximately 450°C for carbon nanotubes).This alternation results in a temperature profile of the substrate that varies depending on whether it is located in an injection zone or a heating zone.

[0143] To minimize these variations and, advantageously, to allow synthesis on both sides of the substrate, a staggered arrangement is particularly preferred. As can be seen in Figures 6 and 9, an injection module located on one wall of the treatment chamber is positioned opposite a heating module on the opposite wall. This minimizes temperature variations. In essence, in this preferred configuration, the invention provides, on each wall of the treatment chamber, an alternation between so-called cold zones, corresponding to the injection modules, and so-called hot zones, corresponding to the heating modules.

[0144] Figures 15 and 16 highlight, in another way, the problem of temperature within the installation according to the invention.

[0145] Figure 15 schematically represents the installation according to the invention, with its injection modules 6a to 6c on one wall and 6'a to 6'c on the opposite wall, as well as its heating modules 7a to 7c on one wall and 7'a to 7'c on the opposite wall. According to the preferred arrangement described above, these different modules are staggered.

[0146] Figure 16 schematically represents an installation not conforming to the invention, equipped with similar injection modules 601 to 603 and 611 to 613, respectively, and similar heating modules 701 to 703 and 711 to 713, respectively. In this hypothetical installation, the modules are arranged symmetrically, meaning that each injection module faces an adjacent injection module, while each heating module faces an adjacent heating module. Figures 15 and 16 also illustrate the moving substrate SUB, as well as the temperature profile Tsub to which the substrate is subjected as a function of its altitude Z within the installation. A mean temperature TN is shown, forming the origin of the x-axis, while the y-axis coincides with the substrate.When the Tsub curve, which is represented by dashed lines, is located to the right of TN, it means that the substrate temperature is higher than this average value, whereas when this same curve is located to the left, the substrate temperature is lower than this average temperature.

[0147] The injection devices in the installation shown in Figure 16 do not require additional cooling to prevent unwanted reactions. Because the injection modules are positioned facing each other, they are exposed to relatively low temperatures at which such unwanted reactions occur only marginally. However, the substrate temperature is subject to significant variations. Specifically, when the substrate is placed between the injection devices, it reaches a minimum temperature T'O that is considerably lower than the maximum temperature T'1 observed for substrates placed between heating devices. As explained above, these significant temperature differences are detrimental to the homogeneity of the coating on the substrate surface.

[0148] Conversely, the staggered arrangement, corresponding to the advantageous variant of the invention, minimizes the temperature variations to which the substrate is subjected. T0 and T1 denote the minimum and maximum substrate temperatures, respectively, separated by a temperature difference DT much smaller than the temperature difference DT' between the extreme temperatures shown in Figure 16. Thanks to this relatively small temperature variation at the substrate surface, a very satisfactory coating quality is guaranteed. However, this requires heating the injection equipment to a temperature higher than that of the installation shown in Figure 16, which implies a risk of unwanted reactions. Such reactions are significantly limited, or even prevented, by the presence of the cooling means according to the invention.

[0149] It should be noted that the installation covered by US 2018 / 0342740, mentioned in the preamble to this description, is not subject to the problem of high temperatures. Indeed, this installation utilizes energy supplied by a plasma, and not thermal energy. Consequently, regardless of the arrangement used, the injection means are not subject to significant risks of parasitic reactions. In this regard, it can be emphasized that the present invention makes the vertical configuration compatible with processes for which US 2018 / 0342740, on the contrary, does not provide a technically viable solution. Such processes are, for example, thermally activated CVD processes, such as the synthesis of VACNT.By comparison, US 2018 / 0342740 only provides a solution for plasma-activated CVD (PECVD) processes, for which the problem of not overheating the gas lines while ensuring substrate heating is not encountered.

[0150] In the example described above, the installation according to the invention has a C-shape, namely that the intermediate zone 20 is vertical, while not only the lower zone 10 but also the upper zone 30 extend horizontally, directly above each other. This C-shaped geometry minimizes the overall height of the installation, thereby facilitating its operation. As is clear from the above, it is therefore necessary to provide a so-called turning zone, corresponding to the presence of the angle brackets 80 and 81, which allows the substrate to transition from a vertical to a horizontal arrangement.

[0151] For this purpose, the presence of orifices 83 and 83', which ensure the diffusion of barrier gas, is particularly advantageous. Indeed, this gas then performs, in addition to its initial barrier function, a supplementary function known as a gas cushion. More precisely, this prevents any contact between the substrate and a mechanical part, which could create a sudden temperature difference, while simultaneously facilitating the smooth movement of the substrate.

[0152] Figures 10 to 13 illustrate different variants of the installation architecture according to the invention. In these figures 10 to 13, the mechanical elements, similar to those in the preceding figures, are assigned the same reference numbers augmented respectively by the numbers 1000, 2000, 3000 and 4000.

[0153] Figure 10 shows the same geometry as in the example above, except that the upper zone 1030 extends in the opposite direction from the lower zone 1010. Figure 11 shows the same geometry as Figure 10, except that the upper zone 2030 extends vertically from the intermediate zone 2020. Figure 12 shows a geometry that is symmetrical to that of Figure 11 with respect to a horizontal median axis; that is, the lower zone 3010 is vertical while the upper zone 3030 is horizontal. Finally, Figure 13 shows an overall rectilinear geometry, where the successive lower zone 4010, intermediate zone 4020, and upper zone 4030 extend vertically from one another. This configuration, which is completely vertical, proves to be simpler since it eliminates any bends imposed on the substrate.

[0154] As an alternative (not shown), it is possible to relocate such a bend to an area of ​​the installation where the film is either not yet heated or has already cooled. In this case, the overall installation can be simplified mechanically, as it allows the substrate to come into contact with mechanical parts, particularly rollers.

[0155] In the example described and illustrated, the substrate flows from bottom to top in the treatment chamber. Consequently, the lower zone 10 and the upper zone 20 are located upstream and downstream of the treatment chamber, respectively. As an alternative (not shown), the substrate can flow from top to bottom. In this case, the lower zone 10 and the upper zone 20 are located upstream and downstream of the treatment chamber, respectively. Furthermore, the locations referenced in these figures as inputs E and E' become outputs S and S'. Conversely, the locations referenced as outputs S and S' become inputs E and E' in the case of a substrate flowing from top to bottom.

[0156] The installation according to the invention can be used in various ways. The deposition of VACNTs has been described in detail above. The installation can also be used to deposit the growth catalyst for carbon nanotubes or nanofibers onto a substrate; this deposition can be followed, in a second step, by the decomposition of a gaseous carbon precursor to grow carbon nanotubes or nanofibers on this substrate. The installation can also be used to modify a nanostructured carbon deposit (for example, VACNTs prepared in this same installation, with or without a continuous supply of a catalyst precursor, or VACNTs prepared in a different reactor), this modification being, for example, an oxidation of their surface. Materials, possibly nanostructured, other than carbon can also be deposited.

Claims

DEMANDS 1. Installation (1) for the deposition, growth or modification of a material on a substrate (SUB), in particular of a composite material comprising nanotubes or nanofibers fixed on a substrate (SUB), such as carbon nanotubes or nanofibers, this installation comprising at least one processing chamber (5), or reaction chamber, which forms an internal volume for the treatment of said substrate (SUB) which is in the form of a sheet or strip, this processing chamber comprising an inlet (E) and an outlet (S), an inlet (E') and an outlet (S') of the installation, this inlet and this outlet of the installation communicating respectively with the inlet (E) and outlet (S) of said processing chamber, means (6) for injecting an active gas mixture into the processing volume of the substrate, this gas mixture being intended for the deposition, growth or modification of said material, heating means (7),suitable for heating the internal volume of the treatment chamber, said installation being characterized in that the treatment chamber (5) extends in a generally vertical manner, the inlet and outlet of the treatment chamber being located at different altitudes (ZE, ZS), free spaces (37, 38) are provided, in operation, on either side of the path of the substrate, the free spaces separating in operation each the respective faces of the substrate with respect to front walls (50, 51) facing the chamber, said front walls bordering the internal volume of treatment of the substrate, both the injection means and the heating means being provided on said front walls (50, 51), and the injection means are equipped with cooling means (65, 66), which are suitable for cooling these injection means.

2. Installation according to the preceding claim, in which the front walls are arranged opposite each other without the interposition of a substrate support base, so as to delimit said free spaces (37,38) in service.

3. Installation according to claim 1 or 2, further comprising thermal insulation means (61), suitable for insulating the injection means from the heating means.

4. Installation according to any one of the preceding claims, wherein the injection means comprise several injection modules, each injection module comprising at least one circulation channel (65, 66) allowing the circulation of the heat transfer fluid, and at least one injection channel (63) allowing the transport of the gaseous mixture, this injection channel opening onto at least one injection nozzle (63).

5. Installation according to claim 4, wherein each injection module comprises a body (60), in which the circulation channel and the injection channel are provided, as well as a thermal insulation casing (61) extending to the periphery of at least a part of this body.

6. Installation according to any one of the preceding claims, wherein the heating means comprise several heating modules, while the injection means comprise several injection modules, the heating modules and the injection modules being arranged alternately on at least the majority of the same front wall.

7. Installation according to claim 6 in which, on at least the majority of each front wall, the heating modules and the injection modules are placed in a staggered pattern.

8. Installation according to any one of the preceding claims, comprising a lower zone (10) bordered by said inlet (E') of the installation and said inlet (E) of the treatment chamber, respectively the outlet of the installation and the outlet of the treatment chamber, and an upper zone (30) bordered by said outlet (S') of the installation and said outlet (S) of the treatment chamber, respectively the inlet of the installation and the inlet of the treatment chamber, this lower zone and this upper zone being arranged on either side of an intermediate zone (20) comprising the treatment chamber (5), the installation (1) having, in side view, a C shape or an S shape, or an L shape, or an inverted L shape, or an I shape.

9. Installation according to any one of the preceding claims, wherein the injection means (6) are capable of injecting the active gas mixture in a direction perpendicular to the plane of the substrate (SUB), in service.

10. Installation according to any one of the preceding claims, which is devoid of a base capable of coming into contact with the substrate in service.

11. Installation according to any one of the preceding claims, wherein the treatment chamber is symmetrical with respect to a vertical axis.

12. Installation according to any one of the preceding claims, comprising a main chassis equipped with both said inlet and said outlet, an insert suitable for cooperating with the main chassis, and removable fixing means between this chassis and this insert.

13. Installation according to the preceding claim, in which the frame and the inserts are hollowed out with respective recesses, forming said processing chamber.

14. A method for implementing an installation according to any one of the preceding claims, wherein: - the substrate is moved through said chamber in said vertical direction, maintaining said free spaces between each face of the substrate and a respective front wall facing the chamber - The internal volume of the treatment chamber is heated by means of the heating devices - Active gas mixture is injected into the internal volume of the chamber, via the injection means, while the injection means are cooled, via the heat transfer fluid circulation means, so as to form carbon nanotubes preferentially on the surface of this substrate.

15. A method according to the preceding claim, wherein carbon nanotubes are formed on both opposite sides of the substrate surface, which nanotubes may be of the same nature or of different natures.

16. A method according to any one of claims 14 or 15, wherein the active gas mixture is injected in a direction perpendicular to the plane of the substrate (SUB).

17. An assembly for the deposition, growth, or modification of a material on a substrate, in particular a composite material, in particular a composite material comprising nanotubes or nanofibers fixed to a substrate (SUB), such as carbon nanotubes or nanofibers, said assembly comprising - an installation according to any one of claims 1 to 13, - means for moving the substrate intended to form said material along the installation, - means of supplying a gaseous mixture, capable of supplying the injection means with a gaseous mixture, -means for admitting a heat transfer fluid, capable of admitting the heat transfer fluid into the circulation means equipping the injection means.

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