DE102013106396A1 - Process for producing a ceramic shielding part and ceramic shielding part - Google Patents

Abstract

The invention relates to a ceramic shielding part (1) with at least a first ceramic layer (2) and at least a second ceramic layer (3), which include a ceramic intermediate layer (5), the ceramic layers (2, 3) and the intermediate layer ( 5) Limit chambers (4) within the shielding part (1). The invention also describes a method for producing the ceramic shielding part (1) with the following steps: a) providing a first ceramic layer (2) in the green state; b) applying a ceramic intermediate layer (5) having or forming chambers (4) in the green state to a free side (6) of the first ceramic layer (2); c) providing a second ceramic layer (3) in the green state and applying the second ceramic layer (3) to the intermediate layer (5); d) firing the composite of first layer (2), intermediate layer (5) and second layer (3).

Description

The invention relates to a ceramic shielding part according to claim 11 and a method for producing a ceramic shielding part according to claim 1.

Shielding parts are used in the environment of sources of thermal energy such as internal combustion engines, turbocharger systems or exhaust ducts. The current state of the art describes multi-layer shielding parts, wherein the two cover layers are made of metal or metal. The interposed between the metallic cover layers intermediate layer comprises one or more insulating materials, which prevents transport of heat in the direction of heat-sensitive components, so that the heat remains in the shielding composite. Depending on the temperature of the unit to be shielded, either technical papers, glass or Silikatfaservliese be used as insulating intermediate layer. Conventional shielding parts are designed for use at very high temperatures, which prevail in modern turbocharger systems, for example, either as direct shielding with a silicate fiber fleece insulating layer or as a multilayer shielding element with metallic cover layers, the multilayer shielding parts having to be attached some distance from the heat source. Therefore, these shielding are disadvantageous when the design space given structurally are too small to arrange the shielding at a reasonable distance from the heat source. Direct shields have the disadvantage that, when used, heat build-up or greatly increased wear can occur in the direct shielding part. In addition, there is a risk that these components overheat.

The invention has for its object to provide a shielding of ceramic with improved shielding properties and a method for producing such a shielding.

This object is achieved by the shielding part according to the invention according to claim 11 or by application of the method according to claim 1. Advantageous developments and refinements are the subject of the dependent claims.

An embodiment of a shielding part according to the invention comprises at least a first layer and at least one second layer. According to the invention, the use of metallic layers as cover layers is dispensed with. Advantageously, the intermediate layer is also made of ceramic. To improve the heat shielding properties, chambers are provided within the shielding part according to the invention of ceramic, which are bounded by the two ceramic cover layers and the webs forming, ceramic intermediate layer.

In an embodiment for further optimization of the ceramic shielding part according to the invention, it is provided that the chambers are provided with a filler. Advantageously, this filler is an airgel, granules or powder having high heat resistance and optimum heat insulating properties.

The inventive idea in the ceramic shielding part extends to the fact that the first layer, the intermediate layer and the second layer are integrally connected to each other after firing, so that a stable and compact shape for the shielding is given and this built after firing or can be installed.

The method according to the invention for producing this ceramic shielding part comprises the following steps:
A first ceramic layer is provided in the green state. Subsequently, the intermediate layer is generated on a free side of the first ceramic layer. Advantageously, the formation of the intermediate layer also takes place in the green state. According to the inventive idea, the intermediate layer forms chambers or basins on the first layer, in that the intermediate layer forms webs in the longitudinal direction of the first layer and also webs in the transverse direction of the first layer. The final processing step for the shielding part in the green state is to place a second ceramic layer in the green state on the basin formed by the intermediate layer, so that the basins now become closed chambers. Finally, the composite of the first layer, intermediate layer and second layer is fired to the ceramic shielding part.

An embodiment of the method according to the invention includes that the first and second layers are formed from preceramic paper before firing. The advantage here is that pre-ceramic paper can be processed flexibly before the sintering process, so that it is easy to form an intermediate layer of strips of preceramic paper in a lattice-like or honeycomb-like prefabricated form.

According to the invention, before the application of the second layer, the honeycomb or the chambers of the intermediate layer are charged with at least one filler, so that the thermal insulation effect predetermined by the ceramic cover layers is additionally improved.

The invention provides that a contour cut of the first and second layer and the intermediate layer takes place in the green state. In addition, to the Shaping the ceramic layers provided that they are inserted into a mold having a particular open cavity. Advantageously, the molding tool can be used as a support structure for the ceramic shielding part during firing.

It is advantageous if the first or second layer of two or more layers of different ceramic materials are laminated in the green state or the first or second layer are at least partially coated, so that an additional shielding effect can be achieved. In this way, functional differences in the cover layers can be integrated or a cover layer finely graduated exactly matched to the application and their specific requirements. A graduation of the cover layers of the shielding parts can also be carried out by the unmixed structure of a core and subsequent coating, for example in the dip coating process, and can be represented cost-effectively in series processes

Advantageously, the connection of the first layer and the second layer with the intermediate layer in the green state by means of an adhesive or other suitable binder is carried out.

It is advantageous in the present invention that pre-ceramic papers in the non-sintered state can be shaped and processed in such a way that a top layer and a base can be combined to form a shielding part. Advantageously, the use of a ceramic support structure forms cavities that can be charged with a very low heat-conductive filler. In addition, it is advantageous that the support structure has a large surface, so that the insulation effect is enhanced. This support structure arranged in the interior of the shielding part according to the invention ideally shows a very low thermal heat conduction with a high mechanical load capacity.

Shielding parts according to the invention can be used in a very high temperature range and still offer good shielding performance even with very small installation spaces. By presenting a hollow structure with airgel filling lightweight construction aspects can also be tracked. The production by the aid of preceramic papers can be carried out with conventional tools and methods and also be represented in a large industrial setting, for example as a series process. A function-graded representation of individual cover layers or entire shielding or shielding extends the potential application of ceramic shielding and can bring a particular cost-benefit advantage when individual cover layers are combined from inexpensive core layers with thin, more efficient and expensive materials, either by lamination or in downstream coating process.

Hereinafter, embodiments of the present invention will be described by way of example with reference to the drawings.

Show it:

1 a perspective view (obliquely from above) of a cover layer (first layer or second layer) of a ceramic shielding according to the invention;

2 a perspective view (obliquely from above) of a first layer having a structure-forming intermediate layer of a ceramic shielding according to the invention;

3 an enlarged view of an edge region of two ceramic layers before the burning process and

4 an enlarged view of an edge region of two ceramic layers after the firing process.

1 shows a perspective view (obliquely from above) of a cover layer (first ceramic layer 2 or second ceramic layer 3 ) of a shielding part according to the invention 1 made of ceramic. The ceramic shielding part according to the invention 1 consists of the first ceramic layer 2 and the second ceramic layer 3 , between these two layers 2 . 3 a ceramic liner 5 is provided. The liner 5 also consists of ceramic, wherein they are within the shielding according to the invention 1 chambers 4 forms. In the 1 shown first ceramic layer 2 or second ceramic layer 3 is here in the green state, ie the final shape of the first ceramic layer 2 in combination with the second ceramic layer 3 and the liner 5 results only after a burning process.

2 shows a perspective view (obliquely from above) of a first ceramic layer 2 with a structure-forming ceramic intermediate layer 5 a shielding part according to the invention 1 made of ceramic. Shown is the first ceramic layer 2 the shielding part according to the invention 1 , being on a free site 6 the first ceramic layer 2 in the green state, a structure is formed. The structure that the liner 5 is also produced in the green state. The chambers 4 inside the liner 5 are with a filler 8th Mistake. The filler 8th may be an airgel, a granule or a powder. After burning are the first ceramic layer 2 , the liner 5 and the second ceramic layer 3 integrally connected.

3 shows the first ceramic layer 2 and the second ceramic layer 3 in cross section in an enlarged view, where clearly a transition or an overlap 10 between first location 2 and second location 3 can be seen in the green state.

4 shows the first ceramic layer 2 and the second ceramic layer 3 after burning. It can be seen that the transition 10a between the two layers deleted and the two layers are closed at the edge, ie are baked together.

• – Bereitstellen einer ersten keramischen Lage 2 im Grünzustand;
• – Anschließend wird eine Zwischenlage 5 beispielsweise aus keramischem Papier aufgebracht. Die Zwischenlage 5 weist Kammern 4 auf, welche aus Streifen 7 gebildet werden. Die aus den Kammern 4 und den Streifen 7 gebildete Zwischenlage 5 kann auch als Stützstruktur bezeichnet werden. In einer Ausführungsform der Erfindung kann die Stützstruktur sortengleich ausgeführt werden, um einerseits eine gute Verbindung zur ersten keramischen Lage 2 und zur zweiten keramischen Lage 3 sicher zustellen und außerdem Spannungen im hitzebelasteten Bauteil durch unterschiedliche Wärmeausdehnungskoeffizienten zu vermeiden. In diesem Zusammenhang ist es günstig als Stützstruktur eine Honigwabenstruktur anzuwenden, die sowohl eine optimale mechanische Stabilität aufweist als auch Anforderungen im Hinblick auf Leichtbauweise erfüllen kann.
• – Im dritten Schritt erfolgt das Bereitstellen einer zweiten keramischen Lage 3 im Grünzustand, wobei die zweite keramische Lage 3 auf die Zwischenlage 5 aufgebracht wird, so dass die Kammern 4 dann geschlossen sind. Vor dem Aufbringen der zweiten keramischen Lage 3 auf die Zwischenlage 5 können die Kammern 4 noch mit einem Füllmittel 8 gefüllt werden.
• – Der abschließende Schritt des erfindungsgemäßen Verfahrens besteht darin, dass der Verbund aus erster keramischer Lage 2, Zwischenlage 5 und zweiter keramischer Lage 3 gebrannt wird, wodurch das erfindungsgemäße keramische Abschirmteil 1 seine endgültige Gestalt bekommt.

The inventive method for producing a ceramic shielding 1 has the following steps:

• - Providing a first ceramic layer 2 in the green state;
• - Subsequently, an intermediate layer 5 for example, applied from ceramic paper. The liner 5 has chambers 4 on which strip 7 be formed. The from the chambers 4 and the strip 7 formed liner 5 can also be referred to as a support structure. In one embodiment of the invention, the support structure can be made identical in order, on the one hand, a good connection to the first ceramic layer 2 and to the second ceramic layer 3 ensure safe and also to avoid stresses in the heat-stressed component by different thermal expansion coefficients. In this context, it is advantageous to use as a support structure, a honeycomb structure, which has both an optimal mechanical stability and can meet requirements in terms of lightweight construction.
• - In the third step, the provision of a second ceramic layer 3 in the green state, the second ceramic layer 3 on the liner 5 is applied, leaving the chambers 4 then closed. Before applying the second ceramic layer 3 on the liner 5 can the chambers 4 still with a filler 8th be filled.
• - The final step of the method according to the invention is that the composite of the first ceramic layer 2 , Liner 5 and second ceramic layer 3 is fired, whereby the ceramic shielding according to the invention 1 gets his final shape.

In one embodiment of the invention it is provided that both the first ceramic layer 2 , as well as the second ceramic layer 3 is formed from preceramic paper before firing. The liner 5 can also be made from stripes 7 pre-ceramic paper exist, these paper strips are then created grid-like or honeycomb prefabricated, so that closed chambers 4 form when the second ceramic layer 3 on the liner 5 is applied.

Before applying the second ceramic layer 3 to the chambers 4 the liner 5 can these with a filler 8th be charged. The filler 8th with which the chambers are fed can be aerogels or granules or powders of aerogels.

A contour cut 9 the first ceramic layer 2 and the second ceramic layer 3 as well as the structure-forming elements of the intermediate layer 5 takes place in the green state before burning. For the shaping of the first ceramic layer 2 , the second ceramic location 3 and the liner 5 , which form a composite layer, they are placed in an open cavity of a mold and then fed to the firing process. The mold with the cavity can serve as a support structure for the ceramic shielding part according to the invention 1 be used.

Furthermore, it is provided that the first ceramic layer 2 and / or the second ceramic layer 3 can be laminated in green state from two or more layers of different ceramic materials. In addition, the first ceramic layer 2 and / or the second ceramic layer 3 at least partially coated. According to the invention it can be provided that the connection of the two ceramic layers 2 . 3 with the intermediate layer 5 in the green state, using either an adhesive or another suitable binder.

A further embodiment of the invention provides a first ceramic layer with regard to the material 2 and second ceramic layer 3 deliberately choose different, or different individual layers of differently constructed preceramic paper to a top layer 2 or 3 to laminate.

LIST OF REFERENCE NUMBERS

1

ceramic shielding part

2

first ceramic layer

3

second ceramic layer

4

chamber

5

ceramic liner

6

free page

7

strip

8th

filler

9

Konturbeschnitt

10

Overlap in the green state

10a

Overlap in the fired state

Claims (14)

Method for producing a ceramic shielding part, comprising the steps of: a) providing a first ceramic layer ( 2 ) in the green state; b) Applying a chamber ( 4 ) or chambers ( 4 ) forming ceramic intermediate layer ( 5 ) in the green state on a free side ( 6 ) of the first ceramic layer ( 2 ); c) providing a second ceramic layer ( 3 ) in the green state and applying the second ceramic layer ( 3 ) on the intermediate layer ( 5 ); d) firing the composite from the first layer ( 2 ), Intermediate layer ( 5 ) and second layer ( 3 ). Method according to claim 1, characterized in that the first layer ( 2 ) and the second layer ( 3 ) are formed from preceramic paper before firing. Method according to claim 1 or 2, characterized in that the intermediate layer ( 5 ) from strips ( 7 ) Pre ceramic paper is formed like a lattice or honeycomb prefabricated. Method according to one of the preceding claims, characterized in that before the application of the second layer ( 3 ) the chambers ( 4 ) of the intermediate layer with at least one filler ( 8th ). Method according to one of the preceding claims, characterized in that the filler ( 8th ) is formed from aerogels or granules or powder of aerogels. Method according to one of the preceding claims, characterized in that a contour cut ( 9 ) of the first layer ( 2 ) and the second layer ( 3 ) and the interim layer ( 5 ) takes place in the green state. Method according to one of the preceding claims, characterized in that for the shaping of the layers ( 2 . 3 ) These are inserted into a mold having a particular open cavity. Method according to one of the preceding claims, characterized in that the molding tool as support structure for the ceramic shielding part ( 1 ) is used when burning. Method according to one of the preceding claims, characterized in that the first layer ( 2 ) or the second layer ( 3 ) are laminated from two or more layers of different ceramic materials in the green state or the first layer ( 2 ) or the second layer ( 3 ) at least partially coated. Method according to one of the preceding claims, characterized in that the connection of the layers ( 2 . 3 ) with the intermediate layer ( 5 ) in the green state by means of an adhesive or other suitable binder. Ceramic shielding part ( 1 ), in particular produced by the method according to one of claims 1 to 10, have at least one first ceramic layer ( 2 ), at least one second ceramic layer ( 3 ) and a ceramic intermediate layer ( 5 ), wherein the ceramic layers ( 2 . 3 ) and the intermediate layer ( 5 ) Chambers ( 4 ) within the shielding part ( 1 ) limit. Ceramic shielding part according to claim 11, characterized in that the chambers ( 4 ) with a filler ( 8th ) are provided. Ceramic shielding part according to claim 11 or 12, characterized in that the filler ( 8th ) is formed from aerogels or granules or powder of aerogels. Ceramic shielding part according to one of claims 11 to 13, characterized in that the first layer ( 2 ), the intermediate layer ( 5 ) and the second layer ( 3 ) are integrally connected to each other after firing.

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