Gas container

Abstract

A gas container having coating on the inner side that is applied directly onto a base material (110) of the gas container. The coating has a plurality of layers of at least one coating material that may be produced by an ALD method.

Claims

1. A gas container comprising: a container made of a base material having an inside coating applied directly on the base material of the container, wherein said coating comprises a plurality of monomolecular layers of coating material, wherein said plurality of monomolecular layers are alternately Al.sub.2O.sub.3 and TiO.sub.2 monomolecular layers, each monomolecular layer having the thickness of one molecule of the respective coating material and in each monomolecular layer the molecules are each situated alongside one another substantially directly in the respective layer, wherein each of the Al.sub.2O.sub.3 and TiO.sub.2 monomolecular layers is produced by an Atomic Layer Deposition process, and wherein coating has a thickness of not more than 500 nm.

2. The gas container as claimed in claim 1, wherein the coating carries an additional applied coating which comprises molecules of the gas intended for filling.

3. The gas container as claimed in claim 1, wherein the base material comprises steel.

4. The gas container as claimed in claim 1, wherein the gas container is substantially cylindrical or bottle-shaped.

5. The gas container as claimed in claim 1, wherein the gas container is a high-pressure container.

6. The gas container as claimed in claim 1, wherein the coating has a thickness of not more than 100 nm.

7. The gas container as claimed in claim 1, wherein the base material comprises chromium-molybdenum steel.

8. The gas container as claimed in claim 1, wherein the base material comprises 34CrMo4 steel.

9. The gas container as claimed in claim 1, wherein said Atomic Layer Deposition process comprises: bringing a first reactant of a coating material into contact with a surface be coated to form a monomolecular layer of the first reactant on the surface; removing excess first reactant not bound on the surface by a rinsing operation; bringing a second reactant of the coating material into contact with the first reactant bound on the surface wherein molecules of the first reactant bound on the surface react with molecules of the second reactant to form molecules of the coating material, and removing excess second reactant by a rinsing operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows schematically a gas container of the invention.

(2) FIG. 2 shows a detail of a wall of a gas container of the invention with a coating in one preferred embodiment.

(3) FIG. 3 shows a detail of a wall of a gas container of the invention with a coating in another preferred embodiment.

EMBODIMENT OF THE INVENTION

(4) Shown schematically in FIG. 1 is a gas container 100 of the invention in the form of a gas bottle. The gas bottle 100 presently comprises a base body 101 which is substantially cylindrical in form, and also a closure cap 102. The detail, identified by A, of the left-hand lower corner of the wall of the gas container 100 is shown in more detail in FIG. 2.

(5) In FIG. 2, the detail A of the wall of the gas container 100 from FIG. 1 is shown larger. The wall comprises a base material 110, which comprises steel, preferably a 34CrMo4 steel customarily used for gas bottles. The thickness of the base material 110 in this case is several millimeters (about 4 mm to 8 mm), and accordingly is no different from a conventional gas bottle made of steel. Now, however, a coating 120 is applied directly on the base material 110.

(6) As already described at the outset, the coating 120 comprises a plurality of layers, produced by means of an ALD process, of at least one coating material such as Al.sub.2O.sub.3 or TiO.sub.2, for example. A further detail of the container wall, particularly of the coating 120, is shown in FIG. 3, which comprises the detail identified by B.

(7) In FIG. 3, the detail B of the wall of the gas container from FIG. 2 is shown larger and in more detail. It can be seen that the coating 120 applied to the base material 110 consists of a plurality of layers. As an example, only three layers 130, 131, and 132 are shown. Depending on the desired embodiment, however, the coating comprises, for example, up to 50 or 100 layers.

(8) Each individual layer has the thickness of the diameter of one molecule of the respective coating material, which is situated within the range of a few nanometers. Furthermore, the molecules of one layer are homogeneous and disposed very closely to one another, this being an effect of the ALD process.

(9) It is evident in particular in FIG. 3 that the individual layers are adapted to the surface structure of the base material 110. Overall, therefore, the coating 120 forms a highly corrosion-resistant protective layer, thus making the gas container 100 of the invention very suitable for filling with highly reactive gases or gas mixtures.

(10) It is further evident from FIG. 3 that the coating 120 consists of layers of different coating materials. The layers 130 and 132 presently consist of a first coating material, preferably Al.sub.2O.sub.3, and the layer 131 in between them consists of a second coating material, preferably TiO.sub.2. In the case of a larger number of layers, this arrangement may be continued accordingly, so that the two coating materials alternate with each layer. This increases the protective effect, i.e., the corrosion resistance, of the coating 120.

(11) For the sake of completeness, however, it should be noted that a coating of just one coating material already achieves a distinct protective effect. Alternatively, other combinations, such as more than two different coating materials and/or a different arrangement of the layers, for example, are also possible. For example, there may be two or three layers of a coating material applied one above another as well, before one or more layers of a different coating material follow.

(12) It should also be mentioned that there may also be additional passivation of the coating 120 with a gas to be filled, thereby further increasing the protective effect. This is sensible and advantageous especially when filling with pure gases. In the case of filling with less reactive gases or gas mixtures (e.g., CO, NO, SO.sub.2), however, this passivation may also be omitted.