DE102015100015A1 - Pyrolysis-capable cooking appliance and method of manufacture - Google Patents

Abstract

The method is used to produce a pyrolysis-capable cooking appliance (3) with a construction device (1) comprising a substrate (2). The substrate (2) is coated in a surface area (12) by a coating process. The coating process includes a vapor deposition process. The substrate (2) is brought to a process temperature during the vapor deposition process which is an intended room temperature plus 25% of the difference between the room temperature and a pyrolysis temperature.

Description

The present invention relates to a pyrolysefähiges cooking appliance and a method for producing such a cooking appliance and a coating apparatus for coating a building device for a pyrolysefähiges cooking appliance.

Many home appliances, such. As stoves and ovens, often have metallic components with a surface coating. The coating usually has to take on a wide variety of tasks. For example, the coated parts and areas should be protected against corrosion, the surfaces should be easy to clean, and last but not least, the household appliance should also have an appealing look and feel. A commonly used coating is z. B. a paint job.

In some areas very high and specific requirements for the coating are made, such. B. in the oven of a baking oven or a baking sheet. There, the coating in addition to the tasks already mentioned also to prevent sticking of the food to be prepared and of grease and oil spills. At the same time, however, the coating must be able to withstand the high temperatures in the cooking chamber. For example, temperatures of up to 500 ° C sometimes occur in an oven with pyrolysis cleaning function. Often oven walls and baking trays are therefore provided with a heat-resistant coating of enamel.

Other types of coatings often have the disadvantage that the coating and the metal to be coated have a different thermal expansion coefficient. As a result, the coating expands z. B. when heated unequal to the coated material, whereby the coating can get under an increased tensile stress and destroyed by cracking.

Therefore, there are approaches to make such coatings more elastic by the addition of certain components. However, this has the disadvantage that the coating often offers inferior protection properties for the coated surface. For example, such coatings are generally not sufficiently gas diffusion-tight, so that oxygen get to the metal and thus undesirable oxidation or tarnishing of the metal surfaces occurs, especially at elevated temperature.

It is therefore the object of the present invention to provide a method for producing a pyrolysefähige cooking appliance with a reliable coating and such a cooking appliance.

This object is achieved by a method having the features of claim 1 and a pyrolysefähiges cooking appliance with the features of claim 9 and a coating device having the features of claim 13. Preferred features are the subject of the dependent claims. Further advantages and features will become apparent from the general description of the invention and the description of the embodiment.

The process according to the invention is particularly suitable for the production of a pyrolyse-capable cooking appliance. The cooking appliance has at least one construction device which comprises at least one substrate. The substrate is at least partially coated in at least one surface area by a coating process. In this case, the coating process comprises at least one vapor deposition process. The substrate is at least partially and at least temporarily brought to a process temperature during the vapor deposition process. The process temperature corresponds to at least one intended room temperature plus 25% of the difference between the room temperature and a pyrolysis temperature.

The method according to the invention has many advantages. A significant advantage is that the substrate is brought to a process temperature during the coating process which corresponds at least to room temperature plus 25% of the difference between the room temperature and a pyrolysis temperature. In contrast, in the prior art in vapor deposition usually seeks to keep the temperature of the substrate as low as possible, for. B. by active cooling. Surprisingly, the increased process temperature in the process according to the invention enables a particularly reliable and durable coating of components, so that they can also be heated without problems during operation. Due to the correspondingly adapted process temperature, the coating is applied to an already extended substrate so that the coating can reliably withstand later expansion of the substrate. Thus occur at a later expansion of the substrate, for. As by heating, less or even no tensile stresses in the coating, which could otherwise cause cracks or make the coating permeable to air.

The process temperature according to the invention is selected so that the coating also withstands higher temperatures that occur in a pyrolytic cleaning of the cooking appliance. At the same time, the process temperature according to the invention enables the production of reliably coated components, which also at lower Temperatures such. B. at baking or at room temperature, are easily used.

In particular, the process temperature is the temperature of the substrate during the vapor deposition process. Preferably, the substrate is maintained at the process temperature throughout the vapor deposition. In particular, at least the region of the substrate to be coated is kept at the process temperature. This is z. B. for larger components advantageous because not the entire part must be constantly tempered. It can also be the entire substrate brought to process temperature.

The room temperature is in particular 20 ° C. It may also be provided another common room temperature, for. 25 ° C. It is also possible that an increased room temperature is assumed for operation in kitchens.

It is also possible to provide two or more coatings. The coatings may be the same or different, z. For example, several different coatings with a different layer thickness can be applied one above the other.

The substrate is in particular a component and / or a construction device, such. As a Garraumwandung or a baking sheet or a housing part. The construction device may comprise one or more components, such as. B. a cooking space with food supports, fittings or the like. Also possible are telescopic extensions, grills, screens and / or hinges. Preferably, the substrate is at least partially made of a metallic material and in particular made of stainless steel and / or a titanium alloy and / or anodized and / or steel. Also possible is a bimetallic material and / or a composite material or the like.

In particular, the substrate is at least partially deformed by thermal energy and in particular stretched and / or stretched. The heat energy can be supplied before and / or during the coating process. For example, the substrate may be heated with a heating source during the vapor deposition process. The substrate can also be supplied by the vapor deposition as such heat energy. For this purpose, the coating rate can be increased accordingly to achieve the necessary process temperature. The substrate may also be pre-heated with a heating source and then fed to the vapor deposition process, e.g. B. in a temperature-controlled oven.

Preferably, the substrate is brought to process temperature under vacuum conditions to prevent oxidative changes of the substrate. This is particularly advantageous for stainless steel materials with a transparent coating. Preferably, the vapor deposition process also takes place under vacuum. In particular, the heating and the coating take place in a preferably common vacuum chamber. The vacuum chamber may be formed heated, z. B. with an electrical resistance heating source and / or an infrared heater. The substrate can also serve as an electrical resistor itself.

Preferably, the process temperature is at least the intended room temperature plus 40% of the difference between the room temperature and the pyrolysis temperature. Such a process temperature allows a coating in which no cracking by tensile forces occurs even at very high temperatures. The process temperature may also be at least the intended room temperature plus 35% of the difference between the room temperature and the pyrolysis temperature. The process temperature may also correspond to the pyrolysis temperature. It is also possible that the process temperature is higher than the pyrolysis temperature.

Preferably, the pyrolysis temperature is at least 400 ° C. In particular, the pyrolysis temperature is between 430 ° C and 470 ° C. It is particularly preferred that the pyrolysis temperature is between 440 ° C and 460 ° C. The pyrolysis temperature may also be 500 ° C or more. For the purposes of this application, the pyrolysis temperature is the temperature to which a cooking chamber of the cooking appliance for pyrolytic cleaning is heated, so that the contaminants contained therein can be at least partially burned in a suitable manner.

It is possible and preferred that substrate be heated at least temporarily to at least one process temperature from the temperature range 200 ° C to 300 ° C during the vapor deposition process. Such a temperature is particularly advantageous because the coated substrate can be used particularly well in pyrolysis. The substrate may also be heated to a temperature of at least 100 ° C. Also possible are temperatures of at least 400 ° C or 500 ° C or even 800 ° C or more. The process temperature is particularly adapted to the material properties of the substrate, for. B. based on the expected thermal expansion of the substrate during the pyrolysis operation. In addition, the temperature is adapted to the tolerance of the coating with respect to tensile forces occurring. The more sensitive the coating to the tensile forces of itself expansive substrate reacts, the closer the process temperature can be aligned to the pyrolysis temperature.

In particular, the substrate is subjected to a stretching process at least partially and at least temporarily before the coating process. Preferably, the substrate is at least partially and at least temporarily subjected to a stretching process before and during the coating process. In this case, the expansion process is designed so that the dimensions of the stretched substrate during the coating process at least approximately correspond to the dimensions that the substrate will assume upon expansion in a later operating state.

It is preferred that the substrate is at least partially mechanically deformed in the expansion process and in particular mechanically stretched and / or stretched. Preferably, the deformation is substantially reversible. For example, at least two end portions of the substrate are bent towards each other. In this case, in particular the side is coated, which has a convex curvature or on which the ends are further apart. The coating process is particularly preferably carried out on a region of the substrate that is convex by mechanical stress and / or thermal expansion. In particular, after the stretching process, the substrate substantially returns to an extent and / or shape that the substrate had before the stretching process.

Particularly preferably, the substrate is coated by cathode sputtering and / or anode sputtering. Preference is given to sputter deposition and / or magnetron sputtering and / or a sol-gel process and / or vacuum coating processes or comparable processes for the application of, in particular, thin coatings. It is also possible that two or more of the coating methods mentioned here are combined.

The substrate can be coated by chemical vapor deposition or by a CVD method (chemical vapor deposition). Also possible is a coating by physical vapor deposition or by a PVD process (Physical Vapor Deposition).

It is also possible for the coating to be applied to the substrate by means of plasma-assisted chemical vapor deposition and, for example, a PECVD process (plasma-enhanced chemical vapor deposition). Also possible is a PACVD process (plasma assisted chemical vapor deposition) or the like.

Such coatings have many advantages, such as. B. a comparatively high layer quality, in particular with regard to the chemical resistance. Advantageously, there is also the possibility of being able to adjust the ratio of different constituents in the coating easily and accurately via the gas mixture in the vacuum coating system and the ability to simply change the gas mixture and thus the coating composition during the coating via a mass flow controller or the like and so easy To be able to produce gradient layers. Another advantage is that even extremely thin layers can be produced, for. B. monolayers over nano- to micrometer thick layers. Another advantage is the ability to produce layers that simulate the substrate contour and this essentially not level.

In particular, in the vapor deposition method, the substrate is coated with at least one coating having a layer thickness of less than 20 μm. But also very thin and in particular a few nanometers thick coatings and / or monolayer or single layers are possible. Also possible are thicker coatings.

The cooking appliance according to the invention is equipped with a pyrolytic cleaning function. The cooking appliance has at least one building device. The construction device comprises at least one substrate with at least one surface area which has at least one coating. The coating is applied by means of a vapor deposition process. The coating is at least up to a substrate temperature in the amount of an intended room temperature plus 25% of the difference between the room temperature and a pyrolysis temperature under a compressive stress.

The cooking appliance according to the invention has many advantages. A significant advantage is the coating, which even at an elevated temperature has a compressive stress. As a result, the coated substrate can also be heated to a greater extent and expand, without an undesirable tensile stress building up in the coating, which can lead to cracking and other disruptions in the microstructure of the coating.

It is particularly preferred that the coating is at least up to a substrate temperature in the amount of an intended room temperature plus 40% of the difference between the room temperature and a pyrolysis temperature is under a compressive stress. In this case, the coating has essentially no tensile stresses, in particular up to this substrate temperature. In particular, no effect at these substrate temperatures Tensile stresses between the substrate and the coating. This has the advantage that the coating can be used reliably even at high temperatures of a pyrolysis and shows no cracking. In particular, the coating still has a compressive stress at a substrate temperature of 200 ° C. The coating may still have a compressive stress even at a substrate temperature of 400 ° C or 500 ° C or more.

In particular, the coating is suitable and designed to protect the substrate from corrosion and / or thermal corrosion and / or tarnishing. In particular, the coating is substantially gas-diffusion-tight. The coating is preferably adapted and configured to prevent oxygen from the substrate. In this case, the coating may be formed as a glassy and / or ceramic-like coating or the like, such. Example, a silica (SiOx, SiOxCy, SiOxCyHz) coating. The coating may be formed at least partially transparent. It is possible and preferred that the coating is at least partially applied by the method of the invention described above.

Preferably, the substrate consists at least partially of at least one metallic material, such as. As stainless steel, steel, titanium, anodized or the like. But possible are other materials. Due to the absence of cracking even at higher temperatures, the coating remains gas-diffusion-tight even at pyrolysis temperatures. This has the advantage that coated stainless steel can be subjected to a pyrolysis without it starts.

Particularly preferably, the coating is formed heat-resistant. Preferably, the coating withstands temperatures up to 250 ° C or even up to 500 ° C or more, while keeping oxygen from the substrate. In particular, the coating is heat-resistant for cooking appliances usual temperatures and preferably also for temperatures up to 500 ° C and / or temperatures as they can occur during the pyrolysis of a cooking appliance.

It is also preferable that the coating is under tensile stress only at a substrate temperature higher than the room temperature plus 75% of the difference between the room temperature and the pyrolysis temperature. The coating can also have a tensile stress only at a substrate temperature which corresponds to the pyrolysis temperature. The coating may also have a tensile stress only at a substrate temperature of over 500 ° C. Preferably, the coating has no significant and in particular no tensile and compressive stresses at a substrate temperature corresponding to the process temperature prevailing during the deposition of the coating by the vapor deposition process. In particular, the compressive stress of the coating decreases as the substrate temperature increases and / or as the substrate expands.

It is preferable that at a substrate temperature lower than the room temperature plus 25% of the difference between the room temperature and the pyrolysis temperature, at least a part of the coating is provided on a substantially convex portion of the substrate. In particular, at least a part of the coating is provided on the convex portion of the substrate when the substrate temperature is less than the room temperature plus 40% of the difference between the room temperature and the pyrolysis temperature. Also, at least a part of the coating may be provided on the convex portion of the substrate when the substrate temperature is less than or equal to the pyrolysis temperature. In particular, the coating has a compressive stress in the convex region of the substrate. This has the advantage that no cracks occur due to tensile stresses in the component in this temperature range.

It is also preferable that at a substrate temperature higher than the room temperature plus 75% of the difference between the room temperature and the pyrolysis temperature, at least a part of the coating is provided on a substantially planar or concave area of the substrate. In particular, at least a portion of the coating is provided on a substantially planar or concave portion of the substrate when the substrate temperature is greater than or equal to the pyrolysis temperature. The coating in the concave region of the substrate may have a tensile stress. In this case, the substrate z. B. be a component which is at least partially deformed by heat, wherein at least partially a substantially concave shape and / or curvature by deformation at least one area, section, side and / or surface assumes. In particular, the tensile stress occurring under the threshold for incipient cracking (cohesion) remains.

Preferably, the construction device is provided for a cooking appliance, such. As an electric or gas oven, steamer, combi steamer, a microwave grill with or without and / or a cooking facility. In this case, the substrate is at least a part of a component which is provided and designed to be heated during operation of the cooking appliance to at least 100 ° C. Also possible are 200 ° C or 400 ° C or 500 ° C or more. Particularly preferably, the substrate is suitable and designed to be heated to the pyrolysis temperature during operation of the cooking appliance.

The coating device according to the invention is provided, in particular, for coating a construction device for a cooking device capable of pyrolysis, and comprises at least one coating device for applying the coating to a substrate. In this case, the coating device is suitable and designed to apply the coating by means of a vapor deposition method. The coating device comprises at least one stretching device with at least one heating source for reversibly stretching the substrate by heat.

The coating device according to the invention has many advantages. A significant advantage provides the stretching device with at least one heat source. Thus, the substrate can be heated and thus reversibly stretched. When the stretched substrate is coated with the coater and then cooled and returned to its original dimensions, the coating is under compressive stress. This has the advantage that when a renewed heating of the coated substrate up to a certain temperature no tensile stresses occur in the coating. With the coating device substrates can therefore be coated particularly advantageously with gas-tight, mechanically loadable and in particular inelastic glass or ceramic-like materials which are heated during operation, for. B. components such as cooking chamber walls or the like.

The coating device is preferably suitable for use in the above-described method according to the invention for producing a household appliance construction device, in particular for a cooking appliance. In particular, the coating device comprises a vacuumable chamber for receiving the substrate during the vapor deposition process. In this case, the heat source is preferably suitable and designed to heat the substrate in the chamber. The heating source may also be arranged in the chamber.

Further advantages and features of the present invention will become apparent from the embodiment, which will be explained below with reference to the accompanying figures.

In the figures show:

1 a schematic representation of a cooking appliance according to the invention in a perspective view;

2 a highly schematic representation of a coating device with a device as a substrate;

3 the coating device 2 with a stretched substrate at the beginning of a coating process;

4 the coating device 2 with a stretched substrate toward the end of a coating process;

5 the coating device 2 with a substrate at the end of a coating process; and

6 a substrate with a coating at different temperatures.

The 1 shows an inventive cooking appliance 3 with a construction device 1 , The cooking appliance 3 has a heated and with a door 23 lockable cooking space 13 on. The cooking appliance 3 can via an operating device 5 be operated by a user. For heating the cooking space 13 Various heating sources may be provided, such. B. a top and bottom heat, a Grillheizquelle, a Umluftheizquelle, a Dampfheizquelle or a Mikrowellenheizquelle.

The construction equipment 1 includes here as components 11 a wall 21 of the cooking space 13 and a food support holder 31 , In addition, other, not designated here components can be provided. The wall 21 is made of a stainless steel material and points to a cooking chamber 13 directed surface area 12 a coating 4 on.

The cooking appliance 3 is formed pyrolysefähig and has a pyrolytic cleaning function. This will be the cooking space 13 and the walls 21 as well as objects therein, such as. B. food support, brought to a pyrolysis temperature of 440 ° C to 460 °, so that adhering contaminants burn substantially to fine ash.

The coating 4 Here is a transparent and substantially 20 microns thick glassy silica coating, which was applied by the method according to the invention. Here, the coating was carried out here for example by chemical vapor deposition, wherein the wall 21 was stretched by heat during the coating process. This has the advantage that when re-heating the coated wall 21 , z. B. during cooking, no tensile stresses in the coating 4 that could damage them. Possible but are also other suitable methods, such. As a plasma-enhanced chemical vapor deposition or physical vapor deposition or magnetron sputtering or the like.

The coating 4 is also gas-diffusion-tight, so that oxygen from the surface of the wall 21 is kept away and thus unwanted discoloration or tarnishing of the wall 21 be prevented. For example, this is achieved by using a silicon dioxide coating which is essentially inorganic, ie contains only very little carbon. This is particularly advantageous because stainless steel surfaces of cooking appliances 3 due to frequent heating to higher temperatures, they tend to tarnish. The transparent coating 4 thus has the advantage that the attractive appearance of the stainless steel surface is still preserved and remains visible, while at the same time a thermally induced tarnishing of the wall 21 reliably prevented.

The wall 21 usually expands more when heated than the particular glass or ceramic-like coating 4 , Due to the different expansion during heating, it can occur in conventional coatings to the smallest cracks, which is the gas diffusion tightness of the coating 4 often impair. Through a coating 4 according to the method of the invention are such cracking even at high operating temperatures, as z. B. occur during pyrolysis, avoided. The wall 21 is doing during the coating process z. B. heated to a process temperature of 180 ° C to 250 ° C, so that the coated wall 21 now can be heated to such and in particular to higher temperatures without cracks in the coating 4 arise.

For example, the process temperature set in the vapor deposition results from a given room temperature plus 40% of the difference between the room temperature and a pyrolysis temperature. At a room temperature of 20 ° C and an exemplary pyrolysis temperature of 460 ° C the difference is 440 ° C. 40% then corresponds to 176 ° C. In addition to the room temperature of 20 ° C, this results in a process temperature of 196 ° C to be set. Such a process temperature has the advantage that such a coated wall 21 also in cooking appliances 3 can be used, which have a so-called pyrolysis cleaning function. Deviations of the actually used process temperature from the calculated process temperature up to 10% or more are possible. Accordingly, the process temperature can also be determined in Kelvin.

In the cooking appliance shown here 3 are next to the wall 21 also other components 11 coated accordingly. For example, the food support holder is also 31 coated. In addition, the coating can 4 also for other components 11 be provided, such. As telescopic extensions, grill grids, front frame for the cooking chamber, Wrasenausblas-end pieces and for parts of the front panel, such as the control panel or housing panels. The components 11 were brought during the coating to a process temperature, so that they in their intended task in the operation Gargerätes 3 can be heated without cracking.

The 2 shows a highly schematized coating device according to the invention 100 , The coating device shown here 100 is suitable, by sputtering, also referred to as sputtering, a coating 4 on a substrate 2 apply. The substrate to be coated 2 here is a component 11 a construction facility 1 which is in a surface area 12 should be coated.

Applying the coating 4 takes place in a coating device 101 the coating device 100 , The coating device 101 is adapted to transfer a material not shown here in the vapor phase or to vaporize, for. B by an ionization or an arc method. The vaporized material then becomes an area of the surface by means of an electric field 12 of the component to be coated 11 guided. Within the coating device 101 There is a fine vacuum to prevent a deflection of the evaporated material.

However, the vacuum also has the advantage that the substrate is not exposed to any oxidative atmosphere during the coating. This is particularly important if z. B. stainless steel is coated as a substrate at high temperatures, since thus tarnishing or discoloration of the substrate is avoided. For example, if the substrate is heated under atmospheric pressure during coating, for example in sol-gel processes, the coating is preferably applied under a protective gas atmosphere (eg a nitrogen atmosphere) in order to prevent substrate oxidation.

The coating device 101 may also be designed for other known types of coatings, such as PVD, CVD, PECVD, PACVD, magnetron sputtering, sol-gel method and other suitable types of coatings. Preferably, the respective type of coating depends on the construction equipment to be coated 1 or the desired coating properties selected.

During the coating process, the substrate to be coated is located 2 on a stretching device 102 caused by a heat source 112 is heated and also within the evacuated coating device 101 located. The heat source 112 can be adjusted so that the substrate 2 to a desired process temperature, eg. B. 200 ° C or 400 ° C or more, can be heated. The substrate can also be brought to process temperature completely or partially by the heat energy occurring in the vapor deposition. The heat supply causes a reversible elongation of the substrate 2 and thus also to an increase in length 22 , In addition to the change in length also other changes in shape of the substrate 2 occur, for. B. vaulting.

In the 3 is the substrate 2 from the 2 shown by the stretching device 102 was reversibly stretched under heat. The substrate 2 has now become the length 32 extended. Is the substrate 2 for example, a component 12 , which is during operation of the cooking appliance 3 heated up to 460 ° C, then the heat source 112 controlled accordingly and the substrate 2 heated during the coating process to a process temperature of at least 196 ° C and, for example, 200 ° C or more. That has the advantage that the length 32 of the substrate 2 during the coating process corresponds at least approximately to the expected length at an operating temperature during later operation.

The heat source 112 remains switched on during the coating process. It can also be provided a clocked circuit. The heat source 112 is advantageously already switched on before the start of the coating, so that the substrate 2 can be maintained at the desired process temperature throughout the coating process.

It may also be beneficial to the temperature of the substrate 2 for the coating 4 to choose as high or slightly higher than the expected pyrolysis temperature. This can ensure that the component 12 and the coating 4 not be damaged, even if they are heated to a higher temperature than expected. In the selection of the process temperature, in particular the property of the coating is taken into account, to be able to absorb tensile forces occurring due to the expanding substrate without cracking.

Part of the vaporized material is here on the substrate 2 deposited and condensed, leaving the surface area 12 partially coated. The coating 4 or the evaporated material are shown here for clarity as circles. The coating 4 is also highly schematic and not drawn to scale. Preferably, the coating has 4 a layer thickness less than 20 microns.

The 4 shows the substrate 2 from the 3 with a completely coated surface area 12 , During the entire coating process, the heat was supplied by the heating source 112 so regulated that the length 32 of the substrate 2 remained essentially constant. After the film formation is complete and the coating 4 as desired throughout the surface area 12 is applied, the heat supply is driven down, so that the substrate 2 back to the original or at room temperature usual length 22 can contract. This is the heat source 112 preferably regulated down so that when cooling no distortions or disturbances in the structure of the coating 4 as well as the substrate 2 occur.

The 5 shows a finished coated substrate 2 which has already cooled down and returned to its original length 22 retired. Upon cooling to room temperature, the coating also contracts 4 together, so the coating 4 is under compressive stress at room temperature. The occurrence of the compressive stress is unproblematic and has the advantage that when reheating the substrate 2 no or greatly reduced tensile stresses in the coating 4 occur. This has the particular advantage of having the coating 4 can also be used at higher temperatures without being affected by the expansion of the substrate 2 Cracks or other disturbances in the structure of the coating 4 occur. The temperature of the substrate is preferred 2 during the coating process chosen so that even at higher operating temperatures, such. B. 200 ° C or even 500 ° C, nor a compressive stress of the coating 4 is present.

In the 6 is one with a coating 4 provided substrate 2 shown at different temperatures. Below is the substrate 2 shown at room temperature. In the middle a substrate 2 at 250 ° C and below at 500 ° C. For clarity, the bulges and expansions have been greatly exaggerated. The heat-dependent expansions are illustrated by means of the dashed auxiliary lines. The substrate 2 here is a component 11 which as a wall 21 for a cooking space 13 is trained. The substrate 2 can also be any other construction equipment 1 be.

The coating 4 was applied here at a temperature of 250 ° C. This has the advantage of having the coating 4 at this temperature to the substrate 2 or to the shape and size of the substrate 2 is adjusted. During the coating process, the substrate was 2 essentially planar, as shown in the center. After coating and cooling to room temperature, the substrate has 2 assumed a domed shape, as shown below. The coating 4 is located on a convex area 52 of the substrate 2 , This shows the coating 4 a compressive stress, which is unproblematic for the resistance. It is possible that the coating 4 is additionally provided on other areas, which are not concave, convex or planar.

Becomes the substrate 2 now heated to an operating temperature of 250 ° C, z. B. as a wall 21 in a cooking appliance 3 , picks up the substrate 2 again a planar shape, as shown in the middle. The coating is exposed to any tension and thus reliably used even at such operating temperatures.

If the substrate is heated further, for example in a pyrolysis operation in a cooking appliance 3 , the substrate bulges 2 , where the coating 4 on a concave area 42 is. A domed substrate 2 at 500 ° C is in the 6 pictured above. Well kick in the coating 4 Tensile stresses, which are tolerable and the coating 4 do not affect and z. B. Do not affect the gas diffusion tightness by cracking.

If an even higher operating temperature is to be expected, the process temperature during the vapor deposition process is simply increased accordingly and thus adjusted to the expected operating temperature. The inventive method thus has the advantage that a different thermal expansion coefficient of substrate 2 and coating 4 even at higher operating temperatures and heating not to cracks in the coating 4 leads.

This requires the coating 4 be prepared in particular so that it is initially at room temperature under a higher compressive stress or bias. This compressive stress is optimally greater in magnitude than the tensile stress that it experiences later by increasing the temperature during use. So crack formation can be prevented particularly reliable.

But it is also sufficient if the compressive stress at room temperature is only just so great that the tensile stress on the coating 4 at maximum operating temperature or pyrolysis temperature remains below the threshold, at the cracking of the coating 4 starts. Concrete required values depend on the thermal expansion of substrate 2 and coating 4 as well as chemical composition, adhesion and cohesion, etc.

In the case of z. For example, silicon oxide (SiOx, SiOxCy, SiOxCyHz) coatings can, by substrate heating to a process temperature of about 200 to 250 ° C during the vapor deposition process, determine the later maximum application temperature of the coating 4 be reliably adjusted to about 400 to 600 ° C. The limitation of the SiO x layer quality lies in the mechanical cracking due to the mismatch of the coefficients of thermal expansion of substrate and coating. The SiOx layer itself is resistant to over 1000 ° C or even 1400 ° C and cracking when placed on a substrate 2 is applied that does not expand much more than the coating 4 ,

LIST OF REFERENCE NUMBERS

1

 construction facility

2

 substratum

3

 Cooking appliance

4

 coating

5

 operating device

11

 component

12

 surface area

13

 oven

21

 wall

22

 length

23

 door

31

 Gargutträgeraufnahme

32

 length

42

 concave area

52

 convex area

100

 coater

101

 coater

102

 stretcher

112

 heating source

Claims (13)

Process for producing a pyrolytic cooking appliance ( 3 ) with at least one at least one substrate ( 2 ) ( 1 ), the substrate ( 2 ) in at least one surface area ( 12 ) is at least partially coated by a coating process, characterized in that the coating process comprises at least one vapor deposition process and that the substrate ( 2 ) is brought at least partially and at least temporarily during the gas phase deposition process to a process temperature which corresponds to at least one intended room temperature plus 25% of the difference between the room temperature and a pyrolysis temperature. Method according to the preceding claim, characterized in that the process temperature is at least the intended room temperature plus 40% of the difference between the room temperature and the pyrolysis temperature. Method according to one of the preceding claims, characterized in that the pyrolysis temperature is at least 400 ° C. Method according to one of the preceding claims, characterized in that the substrate ( 2 ) is at least temporarily heated to a process temperature in the temperature range of 200 ° C to 300 ° C during the vapor deposition process. Method according to one of the preceding claims, characterized in that the substrate ( 2 ) is subjected to a stretching process before and / or during the vapor deposition process. Method according to one of the preceding claims, characterized in that the substrate ( 2 ) is coated by sputtering and in particular sputtering. Method according to one of the preceding claims, characterized in that the substrate ( 2 ) is coated by chemical vapor deposition and / or by plasma enhanced chemical vapor deposition and / or by physical vapor deposition. Method according to one of the preceding claims, characterized in that the substrate ( 2 ) in the vapor deposition process with at least one coating ( 4 ) is coated with a layer thickness less than 20 microns. Pyrolysis-capable cooking appliance ( 3 ) with at least one building device ( 1 ) comprising at least one substrate ( 2 ) with at least one surface area ( 12 ), which comprises at least one coating ( 4 ), characterized in that the coating ( 4 ) is applied by means of a vapor deposition method and is under a compressive stress at least up to a substrate temperature in the amount of an intended room temperature plus 25% of the difference between the room temperature and a pyrolysis temperature. Pyrolysis-capable cooking appliance ( 3 ) according to the preceding claim, characterized in that the coating ( 4 ) is only under a tensile temperature at a substrate temperature greater than the room temperature plus 75% of the difference between the room temperature and the pyrolysis temperature. Pyrolysis-capable cooking appliance ( 3 ) according to one of the two preceding claims, characterized in that at a substrate temperature less than the room temperature plus 25% of the difference between the room temperature and the pyrolysis at least a part of the coating ( 4 ) on a substantially convex area ( 52 ) of the substrate ( 2 ) and / or that at a substrate temperature greater than the room temperature plus 75% of the difference between the room temperature and the pyrolysis temperature at least a part of the coating ( 4 ) on a substantially plane or concave area ( 42 ) of the substrate ( 2 ) is provided. Pyrolysis-capable cooking appliance ( 3 ). Construction device according to one of the preceding claims, wherein the substrate ( 2 ) is suitable and designed, during operation of the cooking appliance ( 3 ) to be heated to the pyrolysis temperature. Coating device ( 100 ), in particular for coating a construction device ( 1 ) for a pyrolysefähiges cooking appliance ( 3 ), with at least one coating device ( 101 ) for applying the coating ( 4 ) on a substrate ( 2 ), characterized in that the coating device ( 101 ) is adapted and adapted to apply the coating by means of a vapor deposition method and that the coating device ( 101 ) at least one stretching device ( 102 ) with at least one heat source ( 112 ) for the reversible elongation of the substrate ( 2 ) by heat.

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