EP4232615A1

EP4232615A1 - Method for coating a wall

Info

Publication number: EP4232615A1
Application number: EP21801844.8A
Authority: EP
Inventors: Sascha Larch
Original assignee: Additive Space GmbH
Current assignee: Additive Space GmbH
Priority date: 2019-11-08
Filing date: 2021-10-20
Publication date: 2023-08-30
Also published as: DE102020129355A1; DE102020127874A1; WO2022084411A1; DE202020106328U1; US20230332742A1

Abstract

The invention relates to a method for coating a wall which has an outer wall layer and at least one metal surface layer, said method having the steps of: a) providing a wall main part which is made of the outer wall layer; b) connecting the outer wall layer to an intermediate layer, which is made of a fiber composite material or has a fiber composite material, in order to form the wall to be coated, wherein at least some of the fibers of the fiber composite material of the intermediate layer have a metal surface, and c) coating the wall on the surface of the intermediate layer, comprising the at least one metal surface layer, facing away from the outer wall layer by means of thermal spraying, preferably by means of cold gas spraying, using a spraying device. Alternatively, the following steps are provided prior to step c): a) applying an intermediate layer or the outer wall layer onto at least one molded body; b1) applying the outer wall layer made of the fiber composite material onto the intermediate layer or applying the intermediate layer onto the outer wall layer and connecting the outer wall layer to the inner intermediate layer in order to form the wall to be coated, wherein at least some of the fibers of the fiber composite material of the intermediate layer have a metal surface; and b2) hardening the wall.

Description

Process for coating a wall

This patent application claims the priorities from German patent application 10 2020 127 874.8 from October 22, 2020, from German utility model application 20 2020 106 328.6 from October 22, 2020 and from German patent application 10 2020 129 355.0 from November 6, 2020.

TECHNICAL AREA

The present invention relates to a method for coating a wall according to the preamble of claim 1 and to a wall which has preferably been produced using this method. In a special embodiment, the invention relates to a method for producing a container with such a wall and a container preferably produced according to this method. A technical field in which this special variant of the method according to the invention directed to the manufacture of containers is applied is the manufacture of pressure vessels such as pressure tanks.

BACKGROUND OF THE INVENTION

It is often necessary to coat a wall body with a metal surface. Thermal spraying, in which metal is sprayed onto a surface and mechanically bonded to the material on this surface, is particularly suitable for this purpose. In addition to thermal spraying processes, in which the metal hits the surface to be coated in a molten - i.e. hot - state, cold gas spraying has recently become established, in which solid metal particles are sprayed onto the surface to be coated with high kinetic energy. by the impact energy melt and combine with the material of the surface to be coated.

However, not every surface material is suitable for such thermal spraying processes, since, for example, easily meltable or mechanically sensitive surface materials can be impaired or damaged as a result. This is particularly undesirable when the impaired property of the surface material is a property that is essential for the intended application of the wall body, such as its strength.

A special area in which such walls can be used is the production of special pressure vessels made of pressure-resistant plastic materials, so-called "Composite Overwrapped Pressure Vessels" (COPV). Such containers are used particularly in space technology as pressure tanks, for example as fuel pressure tanks, but are also used, for example as fuel pressure tanks, for example hydrogen tanks, in land, air and water vehicles. For reasons of weight, such tanks are often made of plastic, in particular a fiber composite material, in order to be able to effectively support the forces generated by the pressure difference between the pressurized interior of the container and the environment, which is usually a vacuum in space travel, despite the low material weight. The same applies to containers whose interior is under negative pressure compared to the environment (for example aircraft waste water tanks). However, such tanks with a wall made of plastic or a fiber composite material are often not chemically resistant to the gases or liquids to be stored or (especially in the case of helium or hydrogen) are not sufficiently tight.

Therefore, such pressure tanks today usually consist of a thin metallic liner, which is wrapped with the fiber composite material and connected by gluing in order to secure the liner against bursting. A problem with this is that the metallic liner and the fiber composite material in space prevailing large temperature differences are subject to different thermal expansions and contractions or are subject to strong temperature changes and fluctuations as a result of filling with cryogenic fuels when the pressure tank is being filled. The liner, for example made of titanium, is formed from sheet metal (for example, two drawn hemispheres as a dome and a bent sheet metal with a longitudinal seam as a cylinder) and welded together with the connecting flanges. The surface of the metallic liner usually has to be prepared and primed before the bonding and wrapping process to ensure adequate bonding of the fiber composite material to the surface of the metallic liner. Subsequently, the container, initially formed only by the liner, is pressurized for stabilization and wrapped with the fiber composite material or otherwise surrounded and cured.

Especially in the case of negative pressure inside the container, but also in the case of frequent temperature fluctuations over large temperature ranges, as they regularly occur in space travel, there is still a risk that the metallic liner will detach from the surrounding structure of the fiber composite wall and collapse or tears.

Although the above-mentioned thermal coating methods of thermal spraying have been known for a long time, the sheet metal liners described above are still provided for lining containers, in particular pressure tanks.

STATE OF THE ART

DE 197 47 384 A1 discloses a method for producing composite bodies, in which a base body made of plastic or ceramic, for example, is coated with a layer of metal by thermal spraying using the cold gas spraying method in order to increase the mechanical stability of the base body or to make it gas-tight or vacuum-tight. DE 197 47 386 A1 also discloses a method for thermally coating substrate materials, for example also composite materials, with a metal or a metal alloy, for example, by means of cold gas spraying.

CH 538 549 A discloses a method for applying protective surface layers made of plastic, in which a body to be coated has a wall made of a fiber-synthetic-resin composite. An intermediate layer of a fabric with longitudinal and transverse threads, which are laminated with the synthetic resin, is first applied to this fiber-synthetic-resin composite. A protective surface layer made of metallic or ceramic materials is applied to this intermediate layer by means of flame spraying.

PRESENTATION OF THE INVENTION

The object of the present invention is to develop a method for coating a wall provided with a fiber composite material with at least one metallic surface layer in such a way that when the wall is coated by means of thermal spraying, the surface to be coated and the layer belonging to this surface are not impaired and also when only a very thin layer of coating is applied, it adheres effectively and reliably to the surface to be coated, and specify a correspondingly coated wall. In addition, a corresponding method for producing a container having such a wall is to be specified, with which it can be achieved that with a low overall weight of a container to be produced, it is and remains reliably gas-tight as well as chemically inert and resistant even with large temperature and/or pressure fluctuations . A corresponding container should also be specified.

The part of the task directed towards the method for coating a wall is alternatively achieved both by a method having the features of claim 1 and by a method having the features of claim 2. According to the first alternative, a method for coating a wall having an outer wall layer with at least one metallic surface layer has the following steps: a) providing a wall base body formed by the outer wall layer; b) connecting the outer wall layer to an intermediate layer formed from a fiber composite material or having a fiber composite material to form the wall to be coated, with at least some of the fibers of the fiber composite material of the intermediate layer having a metallic surface, and b) coating the wall on that of the outer Wall layer facing away from the surface of the intermediate layer with the at least one metallic surface layer by means of a spray device by thermal spraying. This is preferably done by cold gas spraying.

According to the second alternative, the wall to be coated formed in steps a) and b) is produced in a slightly modified manner, for which purpose the following steps are provided before step c) instead of steps a) and b): a1) application of an intermediate layer or the outer wall layer on at least one shaped body; b1) applying the outer wall layer made of the fiber composite material to the intermediate layer or applying the intermediate layer to the outer wall layer and connecting the outer wall layer to the inner intermediate layer to form the wall to be coated, with at least some of the fibers of the fiber composite material of the intermediate layer having a metallic surface ; b2) hardening of the wall.

To form the wall to be coated is either the

Intermediate layer applied to a provided wall base (first

Alternative) or the outer wall layer is on the previously on a The intermediate layer is applied to the shaped body (first variant of the second alternative) or the intermediate layer is applied to the outer wall layer previously applied to a shaped body (second variant of the second alternative). The first two steps of the second alternative can consequently also be carried out in reverse order, so that first the outer wall layer is applied to at least one molded body and then the intermediate layer is applied to the outer wall body and only then does curing take place.

Due to the fact that in the second alternative in step b1) the wall layer is applied to the intermediate layer applied in step a1) and not yet or not fully cured (or vice versa), the plastic material of the intermediate layer is ideally connected to the matrix material of the fiber composite material the outer wall layer and cures together in step b2) to form an integral wall. After curing, the shaped body is removed and the wall is then coated according to step c). In principle, however, it is also possible and covered by the invention to alternatively first cure the inner intermediate layer before the outer wall layer is applied.

BENEFITS

By spraying the surface coating onto the intermediate layer by means of a thermal spraying process, such as thermal spraying, in particular by means of cold gas spraying, this surface coating can be applied extremely thinly and yet with intensive adhesion to the wall and thus form a wafer-thin metallic liner. This not only leads to a significant saving in mass compared to a classic metal planking of such a wall with a metal liner made of sheet metal, but also saves costly sheet metal forming, welding and surface preparation work. In addition, the intensive adhesion of the surface coating sprayed using the thermal spray process ensures a intimate connection of the surface coating to the wall, especially if this consists of plastic or a fiber composite material, and significantly reduces the risk of the surface coating detaching from the wall, since the metal particles penetrate the surface of the intermediate layer and form a mechanical form-fitting connection.

Another major advantage of the method according to the invention compared to the planking known from the prior art with a liner made of sheet metal is that in the event of defects found during quality control (e.g. thickness of the underlayer or scratches in the surface coating), repair measures can be taken on the liner forming Surface coating can be easily carried out by repeated spraying. Improvements can also be implemented if, for example, the result of a qualification test shows that local reinforcements of the metallic surface layer may be necessary.

The design of the intermediate layer from or with a fiber composite material with fibers laminated in synthetic resin, of which at least some of the individual fibers have a metallic surface layer, ensures high impact strength of the surface of the fibers, which reduces the risk of damage to the individual fibers when the metal particles sprayed on during thermal spraying, especially during cold gas spraying, in step c). The strength of the wall body is thus not affected or only slightly affected.

The surface coating with metallic material by means of thermal spraying in step c) causes an intimate microscopic positive structural connection of the metallic surface coating with the metallic fiber surfaces due to the (partial) penetration of the metal particles sprayed onto the metallic fiber surface of the intermediate layer into the metallic material. In addition, the adhesion of the sprayed metal particles on the metal surface of the fibers is better than on fibers with a non-metallic surface.

The intermediate layer, which is firmly attached to the outer wall layer, protects the outer wall layer, in particular the fibers responsible for its strength, from damage by thermal spraying on the intermediate layer, for example on an inside of a container body having the wall, and possibly even penetrating metal particles. In this way, sprayed-on metal particles penetrate at most into the intermediate layer in order to firmly anchor themselves and thus the metallic surface coating in the intermediate layer.

So that a strong connection also occurs between the outer wall layer and the intermediate layer, the matrix of the intermediate layer preferably contains the same plastic material as the outer wall layer. This is particularly advantageous when the outer wall layer consists of or has a fiber composite material and when the plastic material of the intermediate layer corresponds to the matrix material of this fiber composite material of the outer wall layer.

Further preferred and advantageous design features of the method according to the invention for coating a wall are the subject matter of dependent claims 2 to 9.

It is also advantageous if the outer wall layer is formed from a plastic or from a fiber composite material or has such a material.

The intermediate layer preferably has a fiber composite fabric or a fiber composite scrim or it is formed from a fiber composite fabric or a fiber composite scrim. It is also of particular advantage if at least some of the individual fibers of the fiber composite material of the intermediate layer have a non-metallic fiber core coated with a metal or a metal alloy.

At least some of the individual fibers of the fiber composite material of the intermediate layer are preferably coated with copper, with nickel or with an alloy of metals that is invariant to thermal expansion.

It is also of particular advantage if the intermediate layer is formed from a fiber composite material in prepreg construction.

In a preferred variant of the method according to the invention, which can be combined with other variants, the respective fiber composite material is a carbon fiber composite material, an aramid fiber composite material or a glass fiber composite material.

An advantageous embodiment of the respective method according to the invention, which can be combined with other embodiments of the method, is characterized in that at least one of the metals aluminum, titanium, stainless steel, copper or nickel and/or at least one alloy of metals, such as For example, an iron-nickel alloy, preferably an iron-nickel alloy that is invariant to thermal expansion, as is known, for example, under the protected brand name Invar®, is applied by thermal spraying, in particular and preferably by cold gas spraying.

It is particularly advantageous if the wall of the wall base body is formed in step a) from a fiber composite material in a prepreg construction or in a wet application construction. These types of wall production ensure high mechanical stability, so that the thin metallic surface coating has to absorb almost no mechanical loads and/or expansions. It can also be advantageous if the wall is formed from or has a ductile matrix plastic. Here, the risk of the plastic being impaired in its strength by the impact and penetration of metal particles during thermal spraying, in particular during cold gas spraying, is significantly reduced.

This advantage can also be achieved if the wall is formed as a laminate, in particular if the laminate is formed from or comprises a short fiber laminate or if the laminate is formed from or comprises a sheet molding compound.

In both alternative methods of the invention, the intermediate layer is formed by a fiber composite material or has such a material, the fiber composite material preferably being formed by a fiber composite fabric impregnated with a plastic matrix, for example carbon fibres, glass fibres, aramid fibers (for example made of Kevlar® or Nomex®) or other fibers. This type of intermediate layer is particularly advantageous when the outer wall is made of a fiber composite material with a unidirectional fiber orientation or has one. By providing the intermediate layer with a fiber composite fabric, the metal particles impacting due to the spraying process, which form a permanent connection with the wall, will build up better resistance and at the same time the risk of damage to the fibers of the outer wall layer, which are oriented unidirectionally, for example, is reduced just as significantly as a through a possible pre-damage of the unidirectionally aligned fibers of the outer wall layer, since the fiber composite fabric of the inner intermediate layer already forms a form fit even without the matrix plastic and has a biaxial load-bearing behavior.

The fibers with the metallic surface layer are preferably glass fibers, aramid fibers or carbon fibers, which are preferably before lamination or before Processing to the fiber composite material in question coated on their respective surface with a metal, for example vaporized, has been. But it can also be fibers made of another base material, which are provided with the metallic surface layer.

At least some of the individual fibers are preferably coated with a metal or a metal alloy, for example vaporized or by means of CVD (chemical vapor deposition), before the fiber fabric, the fiber knitted fabric or the fiber layer is produced, in particular during or after the production of the fibers. coated.

The part of the object directed to the wall is achieved by the features of claim 10, namely by a wall with an outer wall layer and an intermediate layer provided on one side of the outer wall layer and connected to it, which is formed from a fiber composite material or has a fiber composite material At least some of the fibers of the fiber composite material of the intermediate layer have a metallic surface, the surface of the intermediate layer facing away from the outer wall layer being provided with at least one metallic surface layer applied by thermal spraying, preferably by cold gas spraying.

This wall is preferably produced using a method of the invention. Even if it is sufficient if only some of the fibers, ie some of the fibers, of the intermediate layer are metal-coated on their respective surface, all fibers of the fiber composite material of the intermediate layer are preferably coated with a metal or a metal alloy.

The fiber composite material of the intermediate layer preferably has a fiber fabric, a fiber fabric or a fiber fabric with the metal-coated fibers or is formed from a fiber fabric, a fiber fabric or a fiber fabric with the metal-coated fibers. All fibers of the fiber fabric, the knitted fabric or the fiber fabric or only some fibers may be provided with a metallic surface, e.g. metal-coated. In the case of a fiber fabric, fibers running in a first direction as well as fibers running in a second direction at an angle to the first direction of the fabric are preferably provided with a metallic surface.

It is also advantageous if the fiber composite material is a carbon fiber composite material, an aramid fiber composite material or a glass fiber composite material.

The individual metal-coated fibers preferably have a non-metallic fiber core, for example glass fiber, aramid fiber or carbon fiber material, and a metallic outer surface, the metal preferably being or comprising copper or nickel or a thermal expansion-invariant alloy of metals. However, other metals or metal alloys can also be provided for coating the fibers.

The metallic surface layer of the wall applied using the thermal spraying process has at least one of the metals aluminum, titanium, stainless steel, copper or nickel and/or at least one alloy of metals, such as an iron-nickel alloy.

The application according to the invention of at least one - preferably thin - metallic layer to the wall made of fiber composite material (FRP) or another non-metallic material by means of a thermal spraying process, in particular by means of cold gas spraying, serves to improve the basic properties of the material of the wall. This improves the following basic properties: chemical compatibility, for example with liquid oxygen; the permeability or impermeability, for example to hydrogen or helium; the thermal properties and the mechanical properties.

A major technological challenge solved by the inventor when solving the task consisted - in addition to ensuring the desired layer thickness of the surface coating and its properties (e.g. strength, surface quality, homogeneity, etc.) - in overcoming partially contradictory requirements with regard to: one sufficient good adhesion of the sprayed metallic surface coating to the wall and avoidance of damage to the carrier material (e.g. the fiber composite material or the plastic of the wall.

The part of the object directed to the method for manufacturing a container is achieved according to a first variant by a method for manufacturing a container having the features of claim 16 and according to a second variant by a container having the features of claim 17.

In the first variant of the method according to the invention for producing a container with a container body which has a wall according to the invention, the wall is formed according to one of the methods according to the invention described above. The container body is provided with at least one opening and the intermediate layer lies on the inside of the outer wall layer facing the inside of the container body. The wall of the container body is coated with the at least one metallic surface layer on the surface of the intermediate layer facing the inside of the container body by thermal spraying, preferably cold gas spraying, by means of a spraying device inserted through the at least one opening. This variant of the method is used when the container body is designed in one piece or when a multi-part container body has already been assembled before coating. In this case, the container body can be manufactured first, possibly already with connecting flanges, and then the metallic surface coating can be sprayed onto the inside of the container.

According to the invention, this variant of the method for producing a container with a container body that has a wall, the container body being provided with at least one opening, thus has the following steps: a) Manufacturing the container body with a wall that has an outer wall layer made of plastic or a fiber composite material and an inner intermediate layer formed by a fiber composite material on the inside of the outer wall layer facing the inside of the container body, wherein at least some of the fibers of the fiber composite material of the inner intermediate layer are coated with a metal or a metal alloy; b) Coating of the wall of the container body on the surface of the inner intermediate layer facing the inside of the container body with at least one metallic surface layer by thermal spraying using a spraying device inserted through the opening. This is preferably done by cold gas spraying.

The second variant of the method according to the invention for producing a container with a multi-part container body made of container parts, which has a wall according to the invention, the container body being provided with at least one opening, has the following steps: a) producing the container parts of the container body, each with one Wall formed by a method for manufacturing a wall according to the invention, wherein the intermediate layer lies on the inside of the outer wall layer facing the inside of the container body, and wherein the coating of the wall of the respective container part of the container body' takes place on the surface of the inner intermediate layer facing the inside of the container body', and b) assembling the container parts to form the container.

This alternative variant of the method can preferably be used when the container body is designed in several parts. In this case, the individual container parts are first manufactured and the respective surface coating is sprayed on their respective inner side and then the container parts are assembled to form the container.

It is particularly advantageous if the wall of the container body or of the individual container parts is formed from a fiber composite material in a prepreg construction or in a wet-wound construction. These types of production of the wall ensure high mechanical stability, so that the thin metallic surface coating has to absorb almost no pressure difference-related or temperature difference-related loads and/or expansions.

It can also be advantageous if the wall of the container body or of the individual container parts is formed from or has a ductile matrix plastic. Here, the risk of the plastic being impaired in its strength by the impact and penetration of metal particles during thermal spraying, in particular during cold gas spraying, is significantly reduced.

This advantage can also be achieved if the wall of the container body is formed as a laminate, in particular if the laminate is formed from a short-fiber laminate or has one or if the laminate is formed from a sheet molding compound or has one.

It is advantageous if at least some of the individual fibers of the fiber composite fabric of the inner intermediate layer are coated with copper, with nickel or with an alloy of metals that is invariant to thermal expansion. It is of particular advantage if the inner intermediate layer has a fiber composite fabric or is formed from such a fabric.

The wall of the container body or of the respective container part is preferably formed from a fiber composite material in the following partial steps: a1) applying the inner intermediate layer to at least one shaped body; a2) applying the outer wall layer made of the fiber composite material to the inner intermediate layer; a3) hardening of the wall.

Because in step a2) the wall layer is applied to the intermediate layer that was applied in step a1) and has not yet or not yet fully cured, the plastic material of the intermediate layer—as in the first variant—combines in an ideal manner with the matrix material of the fiber composite material the outer wall layer and cures together in step a3) to form an integral wall. After curing, the shaped body is removed from the container body formed in this way, for example melted out, dismantled or stress-relieved, and the wall is then coated from the inside. In principle, however, it is also possible and covered by the invention to alternatively first cure the inner intermediate layer before the outer wall layer is applied.

Here, too, the inner intermediate layer is preferably formed by a fiber composite fabric impregnated with a plastic matrix, which has, for example, carbon fibers, glass fibers, aramid fibers (for example made of Kevlar® or Nomex®) or other fibers. This type of intermediate layer is particularly advantageous when the outer wall is made of a fiber composite material with a unidirectional fiber orientation or has one. By providing the intermediate layer with a fiber composite fabric, the metal particles that hit the spray process and have to form a permanent connection with the wall will build up better resistance and At the same time, the risk of damage to the unidirectionally aligned fibers of the outer wall layer is reduced just as significantly as a risk formed by possible previous damage to the unidirectionally aligned fibers of the outer wall layer, since the fiber composite fabric of the inner intermediate layer already forms a form fit and a has biaxial load-bearing behavior.

The methods according to the invention for producing a container are particularly preferably used when the fiber composite material is a carbon fiber composite material or a glass fiber composite material.

An advantageous embodiment of the method according to the invention for producing a container, which can be combined with other embodiments of the method, is characterized in that at least one of the metals aluminum, titanium, stainless steel, copper or nickel and/or at least one alloy of Metals, such as iron-nickel alloys, preferably iron-nickel alloys that are invariant to thermal expansion, as are known, for example, under the protected brand name Invar®, are applied using the thermal spraying process, in particular cold gas spraying.

The part of the object directed to the container is achieved by the features of claim 18, namely by a container with a container body which has a wall formed according to the invention with an outer wall layer made of plastic or of a fiber composite material and an inner intermediate layer formed of a fiber composite material on the has the inside of the outer wall layer pointing towards the inside of the container body, at least some of the fibers of the fiber composite material of the inner intermediate layer being coated with a metal or a metal alloy, the surface of the inner intermediate layer pointing towards the inside of the container body having at least one through thermal spraying, in particular by cold gas spraying, by means of the coating method according to the invention applied metallic surface layer is provided. Even if only some of the fibers, ie some of the fibers, of the inner intermediate layer can be metal-coated on their respective surface, all fibers of the fiber composite material of the inner intermediate layer are preferably coated with a metal or a metal alloy.

The fiber composite material of the inner intermediate layer of the container wall preferably has a fiber composite fabric, a fiber composite fabric or a fiber composite fabric with the metal-coated fibers or consists of such a fiber composite fabric, fiber composite fabric or fiber composite fabric. All fibers of the woven or knitted fabric or only some fibers can be metal-coated. Preferably, in the case of a fibrous fabric, fibers running in a first direction as well as fibers running in a second direction at an angle to the first direction of the fabric are metal-coated.

The individual fibers are coated with a metal or a metal alloy before the woven or knitted fabric is produced, for example vaporized or coated by means of CVD (chemical vapor deposition). The individual metal-coated fibers have a non-metallic fiber core, for example glass fiber or carbon fiber materials, and a metallic outer surface, the metal preferably being or comprising copper or nickel or a thermally expansion-invariant alloy of metals. However, other metals or metal alloys can also be provided for coating the fibers.

In particular, the container according to the invention forms a pressure tank that is used, for example, in space technology as a satellite tank or rocket tank. Likewise, the container according to the invention can be used as a pressure tank for fuels in land, air or water vehicles. The container according to the invention can also be used as a pressure tank for breathing gases, such as for so-called 'space walks' (Extra Vehicular Activities - EVA) in or on space suits or on earth when diving or for Respiratory protection purposes and for breathing air supply is required by the fire brigade, the military or civil protection.

By spraying the surface coating onto the wall, here on the inside of the wall of the container, using a thermal spraying process, such as thermal spraying, in particular using cold gas spraying, this surface coating can be extremely thin and yet strongly adherent to the wall (here the container). applied to form a wafer-thin metallic liner. This not only leads to a significant saving in mass compared to the classic production of a container with a metal liner made of sheet metal, but also saves costly sheet metal forming, welding and surface preparation work. In addition, the intensive adhesion of the surface coating sprayed by means of the thermal spraying process ensures an intimate connection of the surface coating to the wall of the container, especially if it is made of plastic or a fiber composite material, and significantly reduces the risk of the surface coating detaching from the container wall, since the metal particles penetrate the surface of the container wall and form a mechanical form-fitting connection.

Another major advantage of the method according to the invention compared to the lining of a container with a liner made of sheet metal known from the prior art is that in the event of defects found during quality control (e.g. lower wall thickness or scratches in the surface coating), repair measures can be taken on the den Liner-forming surface coating can be easily carried out by repeated spraying. Improvements can also be implemented if, for example, the result of a qualification test shows that local reinforcements of the metallic liner on the later flight model may be necessary. The intermediate layer on the inside of the container, which is firmly attached to the outer wall layer, protects the outer wall layer, in particular the fibers responsible for its strength (e.g. the metal-coated carbon fibers or glass fibers) from damage caused by thermal spraying impacting the inside of the container body and possibly even metal particles penetrating into it. In this way, sprayed-on metal particles penetrate at most into the intermediate layer in order to firmly anchor themselves and thus the metallic surface coating in the intermediate layer.

BRIEF DESCRIPTION OF THE DRAWINGS

It shows:

1 shows a partially sectioned container body with a wall according to the invention during the coating step according to an advantageous variant of the method according to the invention and

FIG. 2 shows the container body shown in section from FIG. 1 during the step of coating the wall by means of cold gas spraying.

ILLUSTRATION OF PREFERRED EMBODIMENTS

The method according to the invention for coating a wall 12 and the wall 12 according to the invention are described below by way of example using the wall 12 of a container 1, for example a pressure container for a gaseous fuel. However, the method according to the invention and the wall according to the invention are independent of the application and intended use of the wall 12 and are not limited to the wall of a container, such as a pressure tank. In this respect, the container 1 shown here is just one of many examples with a wall constructed and coated as described below. 1 shows a container body 10 of a container 1 in the phase of manufacturing the container body 10 . The wall 12 of the container body 10 consists of an outer wall layer 13, which in the example shown consists of a fiber composite material with unidirectionally aligned fibers with a cross winding, and an inner wall layer, also referred to as an intermediate layer 14, which also consists of a fiber composite material, the matrix material of which is Essentially the matrix material of the fiber composite material of the outer wall layer 13 corresponds.

To manufacture the container body 10, a molded body 2 is first provided, to which the inner wall layer 14 is applied. The inner wall layer 14 has a fiber composite material, for example a fiber composite fabric or fiber composite fabric with a liquid, hardenable plastic as the matrix material, which, for example, is first brushed or sprayed onto the molded body 2 — preferably provided with a release agent — and to which the fiber composite fabric or fiber composite fabric is then applied will. However, the fiber composite fabric or fiber composite knitted fabric can also be present, for example, in the form of so-called prepregs and can be placed on the shaped body 2 in the uncured state. The wall layer, which is also referred to as the intermediate layer 14, thus forms, as a fiber composite layer, a closed plastic layer encasing the surface 2' of the molded body 2.

As long as the intermediate layer 14 has not yet cured or has not yet fully cured, an outer wall layer 13 made of another fiber composite material with unidirectionally aligned fibers is applied to the intermediate layer 14 forming the inner wall layer wrapped in fiber composite material. Since the plastic matrix of the fiber composite material of the outer wall layer 13 essentially corresponds to the matrix material of the intermediate layer 14—the same plastic is preferably used here used - the two wall layers 13, 14 form a close connection and ideally network with one another.

In order to provide access to the subsequent hollow container body 10, a connecting flange 11 provided with a through-opening 11' can be laminated into the wall 12 of the container body 10 during the production of the two wall layers 13, 14. In the example shown, such a connecting flange 11 is provided on the underside of the container body 10 shown in FIG. This connection flange can consist, for example, of a metal or likewise of plastic, fiber composite material or also of ceramic.

After the wall 12 has been built up over the shaped body 2 in the manner described, the container body 10 is cured in a manner known per se to a person skilled in the art. After curing, the shaped body 2 is removed from the interior of the container body 10 through the opening 11 ′ in the connecting flange 11 , for example the shaped body 2 is melted out of the container body 10 .

The hollow container body 10 manufactured in this way is then subjected to the coating process according to the invention shown in connection with FIG the inner wall layer forming the intermediate layer 14 is applied with a surface coating 16 by means of a thermal spraying process, in the example shown by means of cold gas spraying.

In FIG. 2, the container body 10 shown in FIG. 1 is shown with the connecting flange 11 erected upwards, the container 1 being stably supported by means of supports S on a base. The container 1 is shown in a vertical section in order to be able to show the process of coating the inside 10 ′ of the container body 10 . In FIG. 2 it can be seen how the connecting flange 11 , which consists for example of metal, is laminated into the wall 12 of the container body 10 and firmly connected to the wall 12 . For example, the connecting flange 11 is anchored with its collar between the inner wall layer 14 and the outer wall layer 13 by lamination. Alternatively, the collar of the connection flange 11 can also be covered on its outside with the inner wall layer 14 and the outer wall layer 13 .

A spraying device 3 for a thermal spraying process is introduced from above through the opening 11 ′ of the connecting flange 11 into the interior 10″ of the container body 10. The spraying device 3 comprises a guide rod 30 which is controlled by a control and guide mechanism (not shown) in the vertical direction is movable, as illustrated by the double-headed arrow V in FIG. 2, and which can be rotated about its axis X in both directions by means of the actuating and control mechanism, as is symbolized by the double-headed arrow R in FIG.

At the lower end of the guide rod 30 protruding into the container body 10, an injection unit 34 for the thermal spraying process is pivotably attached by means of a pivot joint 32 which can be pivoted about a transverse axis Y perpendicular to the axis X of the guide rod 30. A supply hose unit 35, which is also routed through the opening 1 T of the connecting flange 11 into the interior 10" of the container body 10, is functionally coupled to the injection unit 34 and connects the injection unit 34 to supply sources (not shown) for a working gas and to a supply of powdered particles , in the present case powdered metal particles, which are sprayed by the spraying device 3 onto the surface 14' of the intermediate layer 14 on the inside 10' of the container body 10, which surface faces the interior space 10''. For this purpose, the supply hose unit 35 has a working gas hose 35' and a particle transport hose 35". The spray unit 34 has at least one spray nozzle 36, through which metal material is sprayed by means of a spray jet 38 onto the inside 10' of the container body, namely onto the inner surface 14' of the Intermediate layer 14 may be applied in one coating layer 18 or in multiple coating layers, whereby surface coating 16 is formed.

In the example of the present invention shown, the spraying unit 34 is a known unit for cold gas spraying. In the cold gas spraying process for coating surfaces, a working gas supplied to the spraying unit 34 is first compressed and heated and then accelerated by expanding it in the spray nozzle 36, with particles introduced into the gas jet, in the present case metal particles, falling on a preferably previously heated substrate - in the present case Fall on the surface 14' of the intermediate layer 14 - be shot. There, the particles penetrate partially into the surface 14' to be coated and thus anchor the applied coating layer 18 of the surface coating 16 in the intermediate layer 14 forming the inner wall layer.

The layer structure of the wall 12 according to the invention with the wall base body 12' formed by the outer wall layer 13, the intermediate layer 14 connected to this made of the fabric with fibers 15 with a metallic surface layer 15" (detail B) and by means of cold gas spraying onto the intermediate layer 14 applied, the surface coating 16 forming coating layer 18 can be seen in the enlarged view of detail A in Fig. 2 well.

The detail B in Fig. 2 shows an enlarged representation of a partially sectioned plan view of the intermediate layer 14 in the direction of the arrow B. The surface 14 'of the intermediate layer 14 is mainly formed by the plastic matrix, the fibers 15 of the fiber composite shown here as a fabric of the intermediate layer 14 covered. The individual fibers 15 have a fiber core 15 ', for example made of carbon fiber, aramid fiber or glass fiber material, which is coated on its surface with a metal, for example vaporized, so that the individual fibers of the woven (or knitted) of the intermediate layer 14 with a metallic one Surface layer 15 "are provided. The metallic surface layer 15" is preferably made of copper or nickel or of a metal alloy, which is preferably thermal expansion invariant. Such a thermal expansion-invariant iron-nickel alloy is known, for example, under the protected brand name Invar®.

As can be seen in Fig. 2, in the example shown, almost the upper half of the container body 10, including the inner surface 11" of the connecting flange 11 facing the interior 10" (or the part of the intermediate layer 14 lying thereon) is already removed from the spraying device 3 been coated with the surface coating 16 from the supplied metal particles. The surface coating 16 thus also covers what is known as the shank area of the connecting flange 11 . The metal particles applied by means of cold gas spraying form a closed, homogeneous surface coating 16 which, in the finished state — even though the lower part of the container body 10 will still be provided with the surface coating 16 — covers the interior 10" of the container body 10 (except for the Opening 1 T in the connection flange 11) surrounds.

Due to the fact that the spraying device 3 can be rotated around the vertical axis X according to the double arrow R, the vertical displaceability of the spraying device 3 according to the double arrow V and the ability to pivot the spraying unit 34 around the transverse axis Y, the nozzle 36 can be positioned at any location on the inside 10' of the container body 'Adjust so that the inside 10' of the container body' 10 can be coated without gaps by means of the thermal spraying process, ie cold gas spraying in this case, and a closed and gas-tight surface coating 16 is thus formed.

The surface coating 16 can consist of a single applied layer or of several successively applied layers of the same metal material or of different metal materials. If the container is provided with at least one inner separating floor, which divides the interior of the container into two (or more) separate spaces (e.g. to accommodate different fuel components), then this dividing floor ( "Common bulkhead") provided on at least one of its surfaces (preferably on both surfaces) with a metallic surface coating by the process according to the invention. As a result, both spaces inside the container are or are completely provided with the metallic surface coating on all surfaces of their respective inner side.

The use of the method is particularly advantageous when the container body is designed in one piece. In this case, the wall of the container body can be produced first, possibly already with connecting flanges, and then the metallic surface coating can be sprayed onto the inside of the wall of the container.

However, the method can also be used if the container body is designed in several parts. In this case, the individual container parts, i.e. individual walls, are first produced and the respective surface coating is sprayed on their respective inner side and then the container parts (walls) are assembled to form a container.

Reference signs in the claims, the description and the drawings are only intended for a better understanding of the invention and are not intended to limit the scope of protection. Reference character list

Designate it:

1 container

2 moldings

2' surface of the shaped body

3 spray device

10 container body

10' Inside of the container body

10" interior

11 connection flange

11' opening

11" inner surface

12 wall

12' wall body

13 wall layer

13' inside

14 intermediate layer

14' surface

15 fiber of the intermediate layer

15' fiber core (e.g. carbon fiber, aramid fiber, glass fiber)

15" metallic surface layer of fiber

16 surface coating

18 coating layer

30 rod

32 swivel joint

34 injection unit

35 supply hose assembly

35' working gas hose

35" particle transport hose

36 Spray Nozzle 38 spray jet

110 container body

R rotation double arrow

S supports

V double arrow

X vertical axis

Y transverse axis

Claims

29

Method for coating a wall (12) having an outer wall layer (13) with at least one metallic surface layer (16), with the steps: a) providing a wall base body (12') formed by the outer wall layer; b) Connecting the outer wall layer (13) to an intermediate layer (14) formed from a fiber composite material or having a fiber composite material to form the wall (12) to be coated, with at least some of the fibers of the fiber composite material of the intermediate layer (14) having a metallic surface , and c) coating the wall (12) on the surface (14') of the intermediate layer (14) facing away from the outer wall layer (13) with the at least one metallic surface layer (16) by means of a spraying device (3) by thermal spraying. Method for coating a wall (12) made of a fiber composite material and having an outer wall layer (13) with at least one metallic surface layer (16), with the steps: a1) applying an intermediate layer (14) or the outer wall layer (13) to at least one shaped body ; b1 ) Applying the outer wall layer (13) made of the fiber composite material to the intermediate layer (14) or applying the intermediate layer (14) to the outer wall layer (13) and connecting the outer wall layer (13) to the inner intermediate layer (14) to form the wall to be coated 30

(12), wherein at least some of the fibers of the fiber composite material of the intermediate layer (14) have a metallic surface; b2) curing of the wall (12) and c) coating of the wall (12) on the surface (14') of the intermediate layer (14) facing away from the outer wall layer (13) with the at least one metallic surface layer (16) by means of a spraying device ( 3) by thermal spraying. Method according to Claim 1 or 2, characterized in that the outer wall layer (13) is formed from a plastic or from a fiber composite material or has this. Method according to Claims 1, 2 or 3, characterized in that the intermediate layer (14) has a fiber composite fabric or a fiber composite fabric or is formed from a fiber composite fabric or a fiber composite fabric. Method according to one of the preceding claims, characterized in that at least some of the individual fibers of the fiber composite material of the intermediate layer (14) have a non-metallic fiber core (15') coated with a metal or a metal alloy. Method according to Claim 5, characterized in that at least some of the individual fibers of the fiber composite material of the intermediate layer (14) are coated with copper, with nickel or with an alloy of metals that is invariant to thermal expansion. Method according to one of the preceding claims, characterized in that the respective fiber composite material is a carbon fiber composite material, an aramid fiber composite material or a glass fiber composite material. Method according to one of the preceding claims, characterized in that at least one of the metals aluminium, titanium, stainless steel, copper or nickel and/or at least one alloy of metals is applied using the thermal spraying method to form the surface coating (16). Method according to one of the preceding claims, characterized in that the wall (12) is formed as a laminate. Wall (12) with an outer wall layer (13) and an intermediate layer (14) provided on one side of the outer wall layer (13) and connected thereto, which is formed from a fiber composite material or has a fiber composite material, with at least some of the fibers of the fiber composite material of the intermediate layer (14) has a metallic surface, the surface (14') of the intermediate layer (14) facing away from the outer wall layer (13) being provided with at least one metallic surface layer (16) applied by thermal spraying. Wall according to Claim 10, characterized in that the fiber composite material of the intermediate layer (14) has a fiber fabric, a fiber knitted fabric or a fiber scrim or is formed from a fiber fabric, a fiber knitted fabric or a fiber scrim. Wall according to Claim 10 or 11, characterized in that at least some of the individual fibers of the fiber composite material of the intermediate layer (14) have a non-metallic fiber core (12') coated with a metal or a metal alloy. Method according to Claim 10, 11 or 12, characterized in that at least some of the individual fibers of the fiber composite material of the intermediate layer (14) are coated with copper, with nickel or with an alloy of metals that is invariant to thermal expansion. Wall according to Claim 13, characterized in that the fiber composite material is a carbon fiber composite material, an aramid fiber composite material or a glass fiber composite material. Wall according to one of Claims 10 to 14, characterized in that the metallic surface layer (16) contains at least one of the metals aluminium, titanium, stainless steel, copper or nickel and/or at least one alloy of metals, such as an iron-nickel alloy. having. A method of manufacturing a container (1) having a container body (10) having a wall (12) formed by a method according to any one of claims 1 to 9, wherein the container body (10) is provided with at least one opening (1 T ) is provided, wherein the intermediate layer (14) lies on the inside (13') of the outer wall layer (13) facing the inside (10') of the container body (10), and wherein the coating of the wall (12) of the container body' (10) with the at least one metallic surface layer (16) on the inside (10') of the container body (10) 33-facing surface (14') of the inner intermediate layer (14) by means of a spraying device (3) introduced through the at least one opening (1T) by thermal spraying. Method for producing a container (1) with a container body (10) made up of several parts and provided with at least one opening (11'), with the steps: a) producing the container parts of the container body (10), each with a wall (12) formed by a method according to any one of claims 1 to 9, wherein the intermediate layer (14) on the inside (13') of the outer wall layer (13) facing the inside (10') of the container body (10) and wherein the coating of the wall (12) of the respective container part of the container body (10) with the at least one metallic surface layer (16) on the surface (14') of the container body (10) facing the inside (10') of the inner intermediate layer (14) takes place. b) assembling the container parts to form the container (1). Container produced by a method according to Claim 16 or 17, with a container body (10) which has a wall (12) according to one of Patent Claims 10 to 15 with an outer wall layer (13) made of plastic or of a fiber composite material and one of a fiber composite material formed inner intermediate layer (14) on the inner side (13') of the outer wall layer (13) facing the inner side (10') of the container body (10), with at least some of the fibers of the fiber composite material of the inner intermediate layer (14) having a metal or a metal alloy, the surface (14') of the inner intermediate layer (14) facing the inside (10') of the container body (10) having at least one layer produced by thermal spraying using a method according to one of Patent Claims 1 to 9 applied metallic surface layer (16) is provided.