EP3942658B1 - Spark plug housing having a galvanic nickel and zinc-containing protective layer and a silicon-containing sealing layer, spark plug having said housing, and method for producing said housing - Google Patents

Description

State of the art

The invention relates to a housing for a spark plug according to claim 1 and a spark plug with at least one such housing according to claim 10, as well as a manufacturing method for the housing according to claim 11.

Today's spark plugs have a housing made of steel, which is subject to corrosion, especially rusting, under the conditions prevailing in the engine. That's why the housing of the spark plug has long been coated with a protective layer that is intended to protect the steel housing from corrosion. Nickel-containing and/or zinc-containing protective layers are very common. Protective coatings containing nickel and zinc have a higher corrosive and thermal resistance than pure zinc coatings and are at the same time more cost-effective than pure nickel coatings. However, the corrosion protection of the protective layer containing nickel and zinc is reduced by defects in the protective layer. These defects can range from the surface of the protective layer containing nickel and zinc to the surface of the housing and thus act as routes of attack for corrosion on the housing itself.

For example, from the EP 2 546 938 A1 and the EP 2 605 348 A1 It is known that this problem can be minimized with nickel-containing protective layers by applying a chromium-containing sealing layer to the nickel-containing protective layer and thus sealing the defects.

A chromium-containing sealing layer can, for example, be deposited on the housing surface from a CrVI-containing medium. This creates a sealing layer with bound trivalent chromium. However, depending on the environmental conditions, it can happen that 3-valent chromium that is actually bound to the surface is converted from the sealing layer surface into free 6-valent chromium. The problem is that hexavalent chromium is classified as harmful to health and its use is banned in some countries.

From the DE 102 05 751 A1 a spark plug housing is known with a sealing layer that has organic and/or silicate components.

Disclosure of the invention

It is the object of the present invention to provide a housing for a spark plug with a corrosion protection layer system that offers good corrosion protection and at the same time largely avoids the use of a Cr-containing sealing layer. In particular, the corrosion protection layer system should also have a temperature resistance of 300°C.

This object is achieved by a housing according to the invention for a spark plug in that the sealing layer arranged on a protective layer containing nickel and zinc contains silicon. The use of a silicon-containing sealing layer has the advantage that a chromium-containing sealing layer can be dispensed with and thus the risk of hexavalent chromium forming and leaving the sealing layer is prevented. Furthermore, sealing layers based on silicon have proven to be very temperature-resistant. Specifically, in series of tests for spark plug housings that have a corrosion protection layer system consisting of a nickel-containing protective layer and a silicon-containing sealing layer, it was shown that these housings still had a rust level of 0 after 24 hours in the salt spray test, i.e. the housing shows no rusty areas in the areas of the housing where a corrosion protection layer has been applied. Even after storing the housings at 300°C for 3 hours, the housings still show a rust level of 0 in the salt spray test after 24 hours.

The housing for a spark plug has a hole along its longitudinal axis. This hole gives the housing an outside and an inside. The hole in the housing is typically intended to accommodate an insulator with a center electrode and connection means. The housing is typically made of a steel, such as carbon steel. On at least part of the outside, a protective layer is applied to the surface of the housing, which is intended to protect the housing from corrosion. The protective layer is a protective layer containing nickel and zinc that is applied to the housing using electroplating technology. With electroplating technology this will happen Housing as an anode together with an electrode serving as a cathode are immersed in an electrolyte bath containing nickel and zinc. By applying a voltage between the housing and the electrode, a current flows from the coating electrode through the electrolyte to the housing, whereby a protective layer containing nickel and zinc is deposited on the side of the housing facing the coating electrode. The protective layer essentially consists of nickel and zinc. The nickel content in the protective layer is preferably 12 to 15% by weight. The protective layer then has a thermal resistance up to approx. 500°C. With a lower nickel content, the thermal resistance is lower. If the nickel content is higher, the zinc is not sufficiently stabilized and the protective layer will dezincify under corrosive stress. This means that the zinc is increasingly broken down in the protective layer, for example through oxidation of the zinc in the protective layer. The protective layer loses its anti-corrosion effect. Iron from the coating electrode is also deposited on the housing along with the nickel and zinc. The proportion of iron in the protective layer containing nickel and zinc is typically 2 to 6% by weight. Further impurities in the protective layer containing nickel and zinc, such as sulfur and traces of sodium or potassium, are possible.

The protective layer containing nickel and zinc on the housing serves as cathodic corrosion protection, i.e. the protective layer containing nickel and zinc is electrochemically more noble than the material of the housing and forms a barrier layer against moist media. The corrosion protection that the protective layer containing nickel and zinc offers depends on the layer thickness B of the protective layer containing nickel and zinc and its freedom from defects. The thicker the protective layer containing nickel and zinc, the lower the probability that a defect will extend from the surface of the protective layer containing nickel and zinc through the entire thickness of the protective layer containing nickel and zinc to the surface of the housing extends and thereby opens up a path for corrosion processes on the housing. An additional sealing layer on the protective layer containing nickel and zinc seals these defects and improves the corrosion protection for the housing.

Further advantageous refinements are the subject of the subclaims.

In an advantageous embodiment it is provided that the sealing layer is free of chromium, ie the sealing layer does not contain any intentionally added chromium and contains chromium at most in an amount of technically unavoidable impurities, for example, which are unintentionally incorporated into the sealing layer during the manufacturing process.

It has proven to be advantageous that the sealing layer has a layer thickness A of not less than 10 nm and not more than 10 μm, in particular not less than 100 nm and/or not more than 1 μm. It has been shown that the sealing layer should have a layer thickness A of not smaller than 10 nm so that the sealing layer is sufficiently thick to close the defects in the protective layer containing nickel and zinc. Furthermore, it has been shown that with layer thicknesses of the sealing layer of more than 10 µm, there is no significant improvement in the technical effects of the sealing layer described above.

Additionally or alternatively, the layer thickness B of the protective layer containing nickel and zinc is in a range from 1 μm to 30 μm.

In a further development of the invention it is provided that there is a first intermediate layer between the housing and the protective layer containing nickel and zinc and/or a second intermediate layer between the protective layer containing nickel and zinc and the sealing layer and/or a cover layer on the sealing layer is/are applied.

The advantage of the first intermediate layer is that the protective layer containing nickel and zinc adheres better to the housing. The first intermediate layer serves as an adhesive bonding layer and can consist, for example, of copper or nickel strike.

The second intermediate layer has the advantage that the silicon-containing sealing layer adheres better to the nickel and zinc-containing protective layer and thermal stresses between the layers are reduced. The second intermediate layer serves as an adhesive bonding layer and can, for example, contain at least one of the elements: nickel, copper, chromium, zinc or titanium.

The cover layer on the silicon-containing sealing layer serves to protect the sealing layer from mechanical damage and can, for example, contain at least one of the elements: nickel, copper, zinc, chromium or titanium.

Additionally or alternatively, the first intermediate layer has a layer thickness C of 1 nm to 1000 nm and/or the second intermediate layer has a layer thickness D of 1 nm to 1000 nm and/or the cover layer has a layer thickness E of 1 nm to 2000 nm. It is advantageous If the layer thickness of the intermediate layer and the top layer are significantly less thick than the protective layer containing nickel and zinc, this prevents internal stresses from occurring in the intermediate layers and the top layer. Due to internal stresses in a layer, bonding failures or separation of the layer from another layer, such as the nickel- and zinc-containing protective layer or the sealing layer, may occur.

The advantageous effects of the corrosion protection layer system, comprising a nickel- and zinc-containing protective layer and sealing layer and optionally the first intermediate layer and/or the second intermediate layer and/or the top layer, arise in particular when the nickel- and zinc-containing protective layer and the Sealing layer and the optional first intermediate layer and / or the optional second intermediate layer and / or the optional cover layer are formed on the entire outside of the housing. And the corrosion protection layer system is/are in particular also formed on at least part of the inside of the housing. It is particularly advantageous if the nickel- and zinc-containing protective layer and the sealing layer as well as the optional first intermediate layer and/or the optional second intermediate layer and/or the optional cover layer are/are formed on the entire surface of the housing. The more surface of the housing is covered with the corrosion protection layer system, the less exposed housing surface is that is susceptible to corrosion processes.

The invention also relates to a spark plug, comprising a housing according to the invention, an insulator arranged in the housing, a center electrode arranged in the insulator and a ground electrode arranged at the end of the housing on the combustion chamber side, the ground electrode and the center electrode being designed to jointly form an ignition gap.

• Bereitstellen eines Gehäuses für eine Zündkerze mit einer Nickel- und Zink-haltigen Schutzschicht, die mittels eines galvanischen Beschichtungsverfahrens auf das Gehäuse aufgetragen wurde, wobei das Gehäuse optional eine erste und/oder zweite Zwischenschicht aufweist,
• Anschließend Spülen des mit mindestens der Nickel- und Zink-haltigen Schutzschicht beschichteten Gehäuses,
• Anschließend ein Schritt, bei dem eine Versiegelungsschicht auf die Nickel- und Zink-haltige Schutzschicht oder die zweite Zwischenschicht aufgetragen wird.

Furthermore, the invention also relates to the manufacturing process of a housing according to the invention. The manufacturing process has the following steps:

• Providing a housing for a spark plug with a protective layer containing nickel and zinc using a galvanic coating process was applied to the housing, the housing optionally having a first and/or second intermediate layer,
• Then rinse the housing coated with at least the protective layer containing nickel and zinc,
• Then a step in which a sealing layer is applied to the protective layer containing nickel and zinc or the second intermediate layer.

Optionally, the manufacturing process can also contain a cleaning step before the rinsing step, in which the surface of the housing coated with at least the protective layer containing nickel and zinc is cleaned. The cleaning step serves to clean the surface of the housing and the surface of the nickel- and zinc-containing protective layer or the optional second intermediate layer of, for example, particles, dirt and passivating agents and in particular to hydrolyze or activate the surface for binding the silane solution.

In the rinsing step, the housing, which is coated with at least the protective layer containing nickel and zinc, is freed from cleaning agents or their residues. Or, if there is no separate cleaning step, then coarse dirt, such as dust, is also washed off during the rinsing step.

During the application step of the sealing layer, the sealing layer is applied at least to the nickel- and zinc-containing protective layer or the second intermediate layer.

The sealing layer is a silicon-containing sealing layer which is formed by silanizing the housing surface coated with at least the nickel- and zinc-containing protective layer. Silanization is a chemical bonding of a silane compound to a surface. The connection occurs through a condensation reaction between hydrolyzable groups of the silanes used and chemical groups on the surface. The silanes used for silanization typically have the general form R _m SiX _n , where R stands for organically functionalized residues and

In an advantageous further development, the method has at least one drying step in which the water or a solvent is removed from the surface of the coated and sealed housing. For example, this is where they begin Silane compounds already begin to network. Furthermore, the manufacturing process can also have a polycondensation step for curing the sealing layer. During the curing of silane compounds, the crosslinking of the silane compounds is completed and the crosslinking solidifies, forming a solid and robust sealing layer.

Additionally or alternatively, the manufacturing process can also have a step in which a top layer is applied to the sealing layer. This protects the sealing layer from mechanical damage.

During silanization, for example, the polycondensation can occur both between silane compounds that are coupled to the surface of the second intermediate layer or to the surface of the nickel- and zinc-containing protective layer of the housing, as well as to the surface of the second intermediate layer or to the surface of the Nickel- and zinc-containing protective layer of the housing include coupled silane compounds with uncoupled silane compounds.

In principle, it is also possible for further silicone compounds, such as silicone oils (e.g. diorganopolysiloxanes), to be incorporated into the network of silane compounds created by the polycondensation.

In an advantageous further development of the manufacturing process, a sol-gel process, CCVD or PVD is used as a coating method to apply the sealing layer.

In the sol-gel process, the housing is placed in a silane solution. During silanization, the silanes accumulate on the surface of the housing coated with at least the protective layer containing nickel and zinc and begin to network with each other there and form the sealing layer.

In the CCVD method (combustion chemical vapor deposition), also known as flame coating, a starting compound suitable for producing the desired layer, here the silanes, is added to a fuel gas. The flame is moved at a short distance over the substrate to be coated, here the housing coated with the protective layer containing nickel and zinc. Due to the high combustion energy, the starting compounds form very reactive species that solidify connect to the substrate surface. The thermal load on the substrate itself is low because it only comes into contact with the flame for a short time.

In the PVD method (physical vapor deposition), the material to be deposited, here the silanes, is in solid form in a coating chamber. The material is vaporized by bombardment with laser beams, ions, electrodes or arc discharge. The evaporated material moves through the coating chamber onto the parts to be coated, here the housing coated with at least the protective layer containing nickel and zinc, condenses there and thus forms the protective layer.

It has proven to be advantageous to use silanes with functionalization, in particular alkoxysilanes, aminosilanes or acrylicsilanes, for the production of the silicon-containing sealing layer. In addition, silanes without functionalization, in particular alkyltrialkoxysilanes, can also be used for the silane-containing sealing layer. Partially fluorinated or perfluorinated siloxanes can only be used to a limited extent because layers formed from them have no temperature resistance up to 300°C.

Further features, possible applications and advantages of the invention result from the following description of exemplary embodiments of the invention, which are shown in the figures of the drawing.

drawing

• Figure 1 shows an example of a corrosion protection layer system according to the invention on a housing
• Figure 2 shows another example of a corrosion protection layer system according to the invention on a housing
• Figure 3 shows an example of a spark plug with the housing according to the invention
• Figure 4 shows an example of the manufacturing process for a housing according to the invention

Description of the exemplary embodiment

Figure 1 shows an example of a corrosion protection layer system according to the invention, consisting of the nickel and zinc-containing protective layer 210 and the silicon-containing sealing layer 220. The nickel and zinc-containing protective layer 210 is applied to the surface of a housing 2. The silicon-containing sealing layer 220 is in turn applied to the nickel and zinc-containing protective layer 210.

The protective layer 210 containing nickel and zinc has a layer thickness B. The layer thickness is measured perpendicular to the housing surface. Since the protective layer 210 containing nickel and zinc is applied to the housing 2 using electroplating technology, the layer thickness B of the protective layer 210 containing nickel and zinc can be different at different points on the housing 2. For example, the housing 2 can have no protective layer 210 containing nickel and zinc on its inside 204 or only partially have a protective layer 210 containing nickel and zinc. The housing 2 preferably has a protective layer 210 containing nickel and zinc on its entire outside 205.

The silicon-containing sealing layer 220 has a layer thickness A. In the case of a silicon-containing sealing layer 220, which is applied by means of an immersion bath in a silane solution, a very uniform layer thickness A usually results for the silicon-containing sealing layer 220. In particular, the Silicon-containing sealing layer 220 may be formed on the entire surface of the housing 2, even in places of the housing 2 where there is no nickel- and zinc-containing protective layer 210, such as areas of the inside 204 of the housing 2.

Figure 2 shows a further example of a corrosion protection layer system according to the invention, consisting of the nickel and zinc-containing protective layer 210 and the silicon-containing sealing layer 220 as well as the first intermediate layer 301 and the second intermediate layer 302 and the cover layer 303. On the surface of a housing 2 the first intermediate layer 301 is applied. The protective layer 210 containing nickel and zinc is in turn applied to this. The second intermediate layer 302 is arranged between the protective layer 210 containing nickel and zinc and the sealing layer 220 containing silicon. The cover layer 303 is in turn applied to the silicon-containing sealing layer 220.

The protective layer 210 containing nickel and zinc has a layer thickness B. The first intermediate layer 301 has a layer thickness C and the second intermediate layer 302 has a Layer thickness D. The layer thicknesses are measured perpendicular to the housing surface. If the protective layer 210 containing nickel and zinc is applied to the housing 2 using electroplating technology, the layer thickness B of the protective layer 210 containing nickel and zinc can be different at different points on the housing 2. For example, the housing 2 can have no protective layer 210 containing nickel and zinc on its inside 204 or only partially have a protective layer 210 containing nickel and zinc.

The silicon-containing sealing layer 220 has a layer thickness A. In the case of a silicon-containing sealing layer 220, which is applied by means of an immersion bath in a silane solution, a very uniform layer thickness A usually results for the silicon-containing sealing layer 220. In particular, the Silicon-containing sealing layer 220 may be formed on the entire surface of the housing 2, even in places of the housing 2 where there is no nickel- and zinc-containing protective layer 210, such as areas of the inside 204 of the housing 2. The cover layer 303 has a layer thickness E.

In further embodiments of the housing 2 with the corrosion protection layer system according to the invention, the corrosion protection layer system can, in addition to the nickel and zinc-containing protective layer 210 and the sealing layer 220, only the cover layer 303 or only the first or second intermediate layer 301, 302 or the cover layer 303 in Combination with the first or second intermediate layer 301, 302.

Figure 3 shows a spark plug 1 in a half-sectional view. The spark plug 1 includes a housing 2. An insulator 3 is inserted into the housing 2. The housing 2 and the insulator 3 each have a hole along their longitudinal axis X. Through the hole, the housing 2 has an outside 205 and an inside 204. The longitudinal axis of the housing 2, the longitudinal axis of the insulator 3 and the longitudinal axis of the spark plug 1 coincide. A center electrode 4 is inserted into the insulator 3. Furthermore, a connecting bolt 8 extends into the insulator 3. A connecting nut 9 is arranged on the connecting bolt 8, via which the spark plug 1 can be electrically contacted with a voltage source, not shown here. The connecting nut 9 forms the end of the spark plug 1 facing away from the combustion chamber.

A resistance element 7, also called CCM (Ceramic Compound Material), is located in the insulator 3 between the center electrode 4 and the connecting bolt 8. The resistance element 7 connects the center electrode 4 to the connecting bolt 8 in an electrically conductive manner. The resistance element 7 is constructed, for example, as a layer system consisting of a first contact CCM 72a, a resistance CCM 71 and a second contact CCM 72b. The layers of the resistance element 7 differ in their material composition and the resulting electrical resistance. The first contact CCM 72a and the second contact CCM 72b may have different electrical resistance or the same electrical resistance. The resistance element 7 can also have only one layer of resistance CCM or several different layers of resistance CCM with different material compositions and resistances.

The insulator 3 rests with a shoulder on a housing seat formed on the inside of the housing. To seal the air gap between the inside of the housing and the insulator 3, an inner seal 10 is arranged between the insulator shoulder and the housing seat, which is plastically deformed when the insulator 3 is clamped in the housing 2 and thereby seals the air gap.

A ground electrode 5 is arranged in an electrically conductive manner on the housing 2 on its end face on the combustion chamber side. The ground electrode 5 and the center electrode 4 are arranged relative to one another in such a way that an ignition gap is formed between them, in which the ignition spark is generated.

The housing 2 has a shaft. A polygon 21, a shrink recess and a thread 22 are formed on this shaft. The thread 22 is used to screw the spark plug 1 into an internal combustion engine. An outer sealing element 6 is arranged between the thread 22 and the polygon 21. The outer sealing element 6 is designed as a folding seal in this exemplary embodiment.

The housing 2 is made of a steel such as carbon steel. A protective layer 210 containing nickel and zinc is applied to the housing 2, in particular to its outside. The protective layer 210 containing nickel and zinc has a layer thickness B, where B is preferably not smaller than 1 μm and not larger than 30 μm. The protective layer 210 containing nickel and zinc serves as passive corrosion protection. On the protective layer 210 containing nickel and zinc there is also a layer containing silicon Sealing layer 220 applied. The silicon-containing sealing layer 220 has a layer thickness A, where A is preferably not smaller than 10 nm and not larger than 1000 nm.

Figure 4 shows schematically a section of the exemplary sequence of the method for producing a housing 2 according to the invention:
In a first optional step S1, the housing 2, which was previously coated using electroplating technology with at least the protective layer 210 containing nickel and zinc and optionally with one or two intermediate layers, and its surface is cleaned. For this purpose, the housing 2 coated with at least the protective layer 210 containing nickel and zinc is placed in a bath with a highly alkaline cleaner and additionally irradiated with ultrasound in the bath for approximately 5 minutes. The optional cleaning step serves, on the one hand, to remove particles, dirt and passivating agents that hinder the application of the sealing layer 220, and on the other hand, the surface to which the sealing layer 220 is to be applied is hydrolyzed or activated so that the sealing layer 220 has a good connection option has. Optionally, before the optional cleaning, the housing 2 can also have a first intermediate layer 301 and/or a second intermediate layer 302 in addition to the protective layer 210 containing nickel and zinc.

In the second step S2, the cleaned housing 2 is rinsed with, for example, demineralized water so that any remaining cleaning agent is removed.

In the third step S3, the sealing layer 220 is applied. The application is carried out by silanizing the coated housing 2. The housing 2 is immersed in a silane solution or sprayed with a silane solution. During this step, the silane binds to the hydrolyzed surface of the housing 2 and begins to crosslink, creating the sealing layer 220.

In the optional fourth step S4, the housing 2 is dried and the sealing layer 220 is hardened. After silanization, the housing 2 is placed, for example, in a drying oven at approximately 130 ° C for approximately 15 minutes. In this case, possible water residues or solvent residues, for example from the bath, are removed from the sealing layer 220. At the same time, the crosslinking of the silanes with one another is completed, whereby the sealing layer 220 hardens. The Drying step is particularly advantageous because it supports and accelerates the crosslinking of the silanes with one another.

In the last step S5 shown here, the housing 2 cools down before it is passed on for further processing, such as applying a cover layer 303 to the silicon-containing sealing layer 220 or assembling the spark plug 1.

Claims (18)

1. Housing (2) for a spark plug (1), having a bore along the longitudinal axis X of the housing (2), the housing (2) thus having an outer side (205) and an inner side (204), and where an electrochemically applied nickel- and zinc-containing protective layer (210) is disposed on at least part of the outer side (205) of the housing (2), and a sealing layer (220) is disposed on the nickel- and zinc-containing protective layer (210), where the sealing layer (220) comprises silicon, characterized in that the silicon-containing sealing layer (220) has been formed by silanization.
2. Housing (2) according to Claim 1, characterized in that the sealing layer (220) is free from chromium.
3. Housing (2) according to either of the preceding claims, characterized in that the sealing layer (220) has a layer thickness A of 10 nm to 10 pm, more particularly of 100 nm to 1 µm.
4. Housing (2) according to any of the preceding claims, characterized in that the nickel- and zinc-containing protective layer (210) has a layer thickness B of 1 µm to 30 µm on the housing (2).
5. Housing (2) according to any of the preceding claims, characterized in that a first interlayer (301) is applied between the housing (2) and the nickel- and zinc-containing protective layer (210) and/or a second interlayer (302) is applied between the nickel- and zinc-containing protective layer (210) and the sealing (220) and/or an outer layer (303) is applied on the sealing layer (220).
6. Housing (2) according to Claim 5, characterized in that the first interlayer (301) has a layer thickness C of 1 nm to 1000 nm.
7. Housing (2) according to either of Claims 5 and 6, characterized in that the second interlayer (302) has a layer thickness D of 1 nm to 1000 nm.
8. Housing (2) according to any of Claims 5 to 7, characterized in that the outer layer has a layer thickness (303) E of 1 nm to 2000 nm.
9. Housing (2) according to any of the preceding claims, characterized in that the nickel- and zinc-containing protective layer (210) and the sealing layer (220) are formed on the entire outer side (205) of the housing (2), and in particular are formed on at least part of the inner side (204) of the housing (2), and, if the first interlayer (301) and/or the second interlayer (302) and/or the outer layer (303) are present, the first interlayer (301) and/or the second interlayer (302) and/or the outer layer (303) are formed on the entire outer side (205) of the housing (2), and in particular are formed on at least part of the inner side (204) of the housing (2).
10. Spark plug (1), comprising a housing (2) according to any of Claims 1 to 9, an insulator (3) disposed in the housing (2), a central electrode (4) disposed in the insulator (3), and a ground electrode (5) disposed on the combustion chamber-side end of the housing (2), where the ground electrode (5) and the central electrode (4) are configured to constitute a spark gap together.
11. Method for producing a housing (2) according to any of Claims 1 to 9, comprising the steps of:

    • providing a housing (2) for a spark plug (1) having a nickel- and zinc-containing protective layer (210) applied to the housing (2) by means of an electrochemical coating process, where the housing optionally comprises a first and/or second interlayer (301, 302),

    • subsequently washing the housing (2) coated with the nickel- and zinc-containing protective layer (210) (S2),

    • subsequently a step (S3) in which a sealing layer (220) is applied to the nickel- and zinc-containing protective layer (210) the second interlayer (302).
12. Method for producing a housing (2) according to Claim 11, characterized in that the production method, before the washing step (S2), comprises a step (S1) in which the surface of the housing (2) coated with at least the nickel- and zinc-containing protective layer (210) is cleaned.
13. Method for producing a housing (2) according to either of Claims 11 and 12, characterized in that the production method, after the applying of the sealing layer (220) to the nickel- and zinc-containing protective layer (210) or to the second interlayer (302), a drying step (S4) involving in particular removing possible water or solvents from the application of the sealing layer from the surface of the housing (2).
14. Method for producing a housing (2) according to Claim 13, characterized in that the production method, after the drying step (S4), further comprises a polycondensation step involving curing of the sealing layer (220).
15. Method for producing a housing (2) according to any of Claims 11 to 14, characterized in that the production method further comprises a step in which an outer layer (303) is applied to the sealing layer (220).
16. Method for producing a housing (2) according to any of Claims 11 to 15, characterized in that the sealing layer (220) is applied using as coating technique a sol-gel operation, CCVD or PVD.
17. Method for producing a housing (2) according to any of the preceding Claims 11 to 16, characterized in that silanes with functionalization, more particularly alkoxysilanes, aminosilanes or acrylosilanes, are used for a sealing layer (220).
18. Method for producing a housing (2) according to Claim 17, characterized in that silanes without functionalization, more particularly alkyltrialkoxysilanes, are also used additionally for the sealing layer (220).

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