EP3145896A2 - Wringing together of ceramics - Google Patents

Abstract

The subject matter of the present invention is an integrally bonded composite component, a method for producing same and the use thereof. The invention relates, in particular, to integrally bonded transparent ceramic composite components, to a method for manufacturing such ceramic composite components, and to the use thereof.

Description

 Wringing ceramic

The present invention is a cohesive composite component, process for its preparation and its use. In particular, the invention relates to cohesive transparent ceramic composite components, methods for producing such ceramic composite components and their use.

Technical ceramics have the advantage over many other materials of being chemically, thermally and / or mechanically stable. For this reason, it would be advantageous if the uses of ceramics could be extended.

In particular, transparent ceramics may have advantages over other transparent materials such as plastics or glasses in heavily loaded areas. Its high chemical, thermal and mechanical resistance predestine it for applications with extreme loads.

However, technical ceramics have disadvantages. For example, the breaking strength of thin ceramic substrates is not sufficient for many applications. For example, a transparent ceramic could be used as a scratch-resistant display panel for mobile electronic devices. However, the standards required here in terms of thickness and weight with ceramic discs are difficult to achieve, since they must have a certain thickness in order to ensure a sufficient breaking strength can. One way to solve this problem is to provide ceramic-substrate composites or laminates in which the ceramic can be made very thin and provide the functional surface. The substrate serves as a support for the ceramic and may provide other functions, such as sufficient bond strength of the composite. However, the ceramic and the substrate must be durable, preferably cohesively, connected to each other.

CONFIRMED U NGSKOPI E Ceramic substrate laminates are known from the prior art, which are interconnected by means of an adhesive layer. However, such an adhesive layer is disadvantageous, in particular if the highest possible strength of the overall laminate in conjunction with extreme layer adhesion is sought.

Bonded composites made of amorphous materials such as glass, which are produced by means of wringing two individual components, are known in the field of optics in particular. It is about establishing a connection between two components that are very good in terms of their surface quality and form fit to each other in terms of their surface shape. In such components, the corresponding surfaces can bring by juxtaposition in such close contact with each other that there is a firm connection between the two components. The force that sustains this connection is, according to common doctrine, attributable to the van der Waals forces between the individual atoms or molecules of the two components.

Oer advantage of Aufenggens is that the connection of the components without using a connecting material, such as an adhesive manages. It is believed that the components are held together mainly due to adhesion forces. The joining mechanism of silicon and quartz wafers is based on Si-O-Si compounds which are formed at elevated temperatures (> 100 ° C.) (Gösele, Tong: Semiconductor wafer bonding, Annual Review of Matehals Science 28 (1), 1998, 215-241). Sufficient hydrophilization of the surface is believed to be necessary to form the Si-O-Si bonds. Prerequisite for the durability of the connection are clean, extremely smooth and precisely fitting surfaces.

In DE 102011012835 A1 a method for the addition of glasses and crystalline ceramics by pretreatment in a low-pressure oxygen plasma with subsequent temperature treatment under reduced pressure conditions (<10 mbar) of at least 100 ° C described. Additional coating processes (eg with S1O2) are not required. This is made possible by the application of high contact pressures in the range of 20 kPa to 5 MPa. The object of the present invention is to provide a solid connection of a technical ceramic with another component. In particular, in the case of transparent ceramics, the compound according to the invention should moreover have no negative effect on the transparency of the composite. According to the invention, a composite component between ceramic and ceramic or ceramic and other materials, ie, for example, ceramic with (tempered) glass or ceramic with plastic is to be provided.

Only by the development of polycrystalline transparent ceramics, as described, for example, in WO 2013/068418 A1, with RIT values> 75% at 600 nm wavelength (thickness: 2 mm) is it possible for the first time according to the invention to have transparent composite materials with at least one ceramic component To make wringing. The transparency is measured by measuring

- Real Inline Transmission (RIT) with a narrow aperture angle <0.5 ⁰

 - stain frequency

 - Haze (haze)

reliably quantify.

The problem underlying the invention is achieved by a composite component having the features of the main claim. Preferred embodiments can be found in the subclaims. The inventive method for producing the composite component according to the invention is characterized by the features of the independent method claim. Accordingly, the method according to the invention provides for a connection of one ceramic component to another component by breaking them up. Preferably embodiments of the method according to the invention can be found in the dependent method claims. According to a preferred embodiment of the invention, the two components are joined together directly, ie without adhesion promoter. For this purpose, a joining pressure is required.

However, according to a further embodiment of the invention, it is also possible to apply a bonding agent to one or both components and then to abut the components via the bonding agent or adhesives. As adhesion promoters, particularly preferred metals or metal oxides are used according to the invention, which can be applied to the individual components by a wide variety of methods. Coating processes, in particular PVD (for example sputtering, electron beam evaporation, ion-assisted deposition), CVD or else sol-gel processes are particularly preferred. The PVD methods have proven to be particularly suitable because they allow the flatnesses required for wringing to be realized. The layer thicknesses are preferably in the range of 1 nm to 10 μm. Of course, the layers can also be applied to the components by screen printing or pad printing or similar methods.

The metals may be provided as metal layers or as oxide layers. Oxide layers can preferably also be formed only during the joining of the components, if, for example, the joining is carried out under oxidizing conditions, for example an oxidizing atmosphere.

As adhesion promoters are preferably Si and Ti, more preferably S1O ₂ , ΤΊΟ ₂ or ITO (indium-tin-oxide), which are transparent, used. Other metals or metal oxides, especially those which are transparent, are also suitable as adhesion promoters according to the invention. For components that do not need to be transparent, of course, non-transparent metals or metal oxides can be used. An alternative method is the surface silicization by means of flame pyrolytic deposition of a silicon precursor. The surface is coated with SiO ₂ by burning monosilane (SiH ₄ ). A pre-cleaning of the surface is particularly preferred in this case (eg by means of plasma cleaning). In order to be able to blast the components, the surfaces to be embossed should have a flatness of <10 m, preferably <1 μm, particularly preferably <100 nm.

According to the invention, it is provided that the distance between the surfaces of the components to be joined during the joining process is very small; it is particularly preferred according to the invention to bring the surfaces of the components to be joined into intimate contact, i. the distance of the surfaces is equal to zero according to the invention, the surfaces of the components to be joined touch as full as possible. In order to ensure this intimate contact, according to the invention, the flatness of the surfaces described above is particularly preferred. In addition, it is preferred according to the invention if the surfaces to be joined are designed precisely matching one another. In particular, when the components are to be sprinkled without bonding agent, extremely high demands are placed on the accuracy of fit.

After or during the joining, according to the invention, an application of pressure and / or temperature may be necessary, depending on which materials are to be connected to one another.

According to preferred pressures are between atmospheric pressure and 2,000 MPa. High pressures can be generated, for example, in a hot isostatic press (HIP) by gas pressure (argon, nitrogen, air).

The preferred temperature range for the joining process is between room temperature and temperatures, below the melting / softening temperature of the component, with the lower melting / softening temperature. If the joining process according to the invention is carried out in a HIP plant, this offers the advantage that it is simultaneously possible to apply temperature and pressure, if necessary even under a certain atmosphere. In addition, a treatment in a vacuum oven, in pressure sintering furnace or in other aggregates are possible, which allow a treatment with pressure and / or temperature. In addition, it is possible to use a mechanical pressure component, so for example a press with subsequent temperature treatment in an oven.

To shorten the process times, the pressure and temperature treatment according to the invention by means of rapid sintering technologies such as the FAST method (Field Assisted Sintering Technology) is possible. Before wringing the components, a cleaning of the surfaces to be joined may be useful. By plasma etching, chemical cleaning, tempering in air, in the vacuum or under H2 atmos- sphere or by ion milling, the surfaces according to the invention of water, OH groups, hydrocarbons and other substances can be freed

According to a preferred embodiment of the invention, the coefficients of thermal expansion (CTE) of the components to be abutted are matched to one another. For certain applications, for example, if the composite component produced according to the invention is to be used under thermal stress, e.g. as stove or fireplace windows, it is advantageous if the CTEs are as similar as possible.

However, there may also be uses for the composite component, for which it is advantageous according to the invention, if the two components have different thermal expansion coefficients. According to the invention, a composite component is provided in which the one component is made of a material having a higher CTE exists, a compressive stress is generated in the respective other component. For example, if a ceramic component with a low CTE is connected to a glass with a higher CTE, a compressive stress is generated in the ceramic surface, which can increase the fracture strength of the ceramic.

According to a particularly preferred embodiment of the invention, the composite component produced is part of a display, for example for a mobile electronic device. Here it is advantageous if the total thickness of the composite component is as small as possible. The ceramic composite component therefore consists of a thin ceramic layer, which has been connected, for example, with a chemically hardened glass or a plastic. For such a purpose, the ceramic layer or the ceramic component has a thickness of <50 mm, preferably a thickness of <1 mm, more preferably a thickness of <0.5 mm and most preferably a thickness of <0.1 mm ,

The principle underlying the invention is based on the generation of a diffusion layer between the ceramic component and the component material to be abutted. A minimum penetration of the component material to be sprayed into the ceramic surface or an adaptation of the grids in the contact layer is also possible.

The connection of the blasted components should be cohesively forming a chemical reaction zone. Surprisingly, it has been found that according to the invention transparent composite components by wringing without a disturbing intermediate layer with

 RIT> 60%, preferably> 70% and more preferably> 75%

 Stain frequencies <10%, preferably <3% and more preferably <1%

Haze <10%, preferably 5% and more preferably <2% let produce. By high demands on flatness (<10 μιη, preferably <1 pm and more preferably <100 nm) and roughness (<20 nm, preferably <10 nm and more preferably <1 nm) can be scattered light, which is generated for example by superficial pores , and avoid interference patterns.

If the joining partners are made thin (thickness <1.5 mm, preferably <0.75 mm and particularly preferably <0.3 mm), even more suitable joining compounds with RIT values> 80% can be produced, since the transparency increases with reduced thickness , The reason for this is that with a thin version of the ceramic component, the already low defect frequency (porosity <100 ppm) is reduced and light strikes the component almost unhindered. In addition, the geometric requirements decrease because the glass and ceramic components become deformable and can cling flexibly. For this a joining pressure is necessary. The thin ceramic components have a polycrystalline structure, preferably the g-Al spinel (MgAl ₂ 0 ₄ ) or the polycrystalline corundum (a-Al ₂ 0 ₃ ) is used.

If a rigid ceramic is made thin enough, it can be flexible: the bending stiffness is proportional to the cube of the thickness, and a thin component design significantly reduces its rigidity. This is particularly pronounced when the ceramic thickness is <300 pm, preferably <200 pm and particularly preferably <100 pm.

In detail, the present invention describes:

• Composite component of a fixed connection of two components, wherein at least one component is a technical ceramic and wherein the components are connected without the use of a connecting material. • Composite component according to the previous point, wherein the two components are materially interconnected to form a chemical reaction zone.

Composite component according to one of the preceding points, wherein one component is a technical ceramic and the other component is selected from a ceramic, a second technical ceramic, a transparent material, a glass, preferably an alkali aluminosilicate glass, particularly preferably one Alkalialumosilikatglas that is biased in the near-surface layer under pressure, made of a tempered glass or a plastic.

Composite component according to one of the preceding points, wherein the technical ceramic has a polycrystalline structure.

Composite component according to one of the preceding claims, characterized in that the technical ceramic is a polycrystalline transparent technical ceramic.

Composite component according to one of the preceding points, wherein the technical ceramic is a polycrystalline transparent technical ceramic, preferably Mg-Al-spinel (MgAbC) or the polycrystalline corundum (a-Al ₂ 0 ₃ ).

Composite component according to one of the preceding points, wherein it is transparent.

Composite component according to one of the preceding points, wherein it is transparent and has an RIT> 60%, preferably> 70% and particularly preferably> 75%, stain frequencies <10%, preferably <3% and particularly preferably <1% and haze (haze) ) of <10%, preferably 5% and more preferably <2%. A method for producing a composite component according to one or more of the preceding points, wherein two components, of which at least one component is a technical ceramic, are joined by wringing without using a connecting material.

Method according to one of the preceding points, wherein two components, of which at least one component is a technical ceramic, are connected without the use of a connecting material by a joining pressure.

Method according to one of the preceding points, wherein an adhesion promoter is applied to the surface of one or both components and then the components are sprinkled over the adhesion promoter (s).

Method according to one of the preceding points, wherein metals or metal oxides are used as adhesion promoters.

Method according to one of the preceding points, wherein the adhesion promoters are applied by means of coating methods, in particular PVD (for example sputtering, electron-beam evaporation, ion-assisted deposition), CVD or sol-gel methods.

Method according to one of the preceding points, wherein the adhesion promoters are applied in layer thicknesses of 1 nm to 10 pm.

Method according to one of the preceding points, wherein Si and Ti, more preferably SiO ₂ , TiO ₂ or ITO (indium tin oxide), which are transparent, are used as adhesion promoters.

Method according to one of the preceding points, wherein a surface silicate is carried out by means of flame pyrolytic deposition of a silicon precursor.

Method according to one of the preceding points, wherein the surface is coated by the burning of monosilane (SiH ₄ ) with S1O ₂ . Method according to one of the preceding points, wherein the surfaces of the components to be blown have a flatness of <10 pm, preferably of <1 pm, particularly preferably of <100 nm.

Method according to one of the preceding points, wherein surfaces to be joined are designed precisely to one another.

Method according to one of the preceding points, wherein after or during the joining, an application of pressure and / or temperature is provided.

Method according to one of the preceding points, wherein the applied pressures between atmospheric pressure and 2,000 MPa.

Method according to one of the preceding points, wherein the application of pressure in a hot isostatic press (HIP) by gas pressure (argon, nitrogen, air) is made.

Method according to one of the preceding points, wherein the temperature range for the joining process between room temperature and temperatures which are below the melting / softening temperature of the component with the lower melting / softening temperature.

Method according to one of the preceding points, wherein to shorten the process times, the pressure and temperature treatment rapid sintering technologies such as the FAST method (Field Assisted Sintering Technology) are used.

Method according to one of the preceding points, wherein prior to wringing of the components, the surfaces to be joined are cleaned.

Method according to one of the preceding points, wherein prior to wringing of the components, the surfaces to be joined by plasma etching, chemical cleaning, tempering in air, in vacuum or under H ₂ - Atmossphäre or be removed by ion milling of interfering substances.

Method according to one of the preceding points, wherein the coefficients of thermal expansion (CTE) of the components to be blown are matched to one another.

Method according to one of the preceding points, wherein the coefficients of thermal expansion (CTE) of the components to be abutted are as similar as possible.

Method according to one of the preceding points, wherein the one component consists of a material with a higher CTE, thereby to generate a compressive stress in the respective other component.

Furthermore, the present invention describes the use of the composite component according to the invention or the composite component produced according to the invention, for example as part of a display, such as for a mobile electronic device or as a stove or chimney window.

In the following, the invention will be illustrated by examples, without thereby limiting it:

Example 1:

Two square spinel tiles with polished (r _a <20 nm, preferably r _a <10 nm and more preferably r _a <4 nm) surface are pretreated by chemical means and plasma cleaning. In a clean room environment, the surfaces are contacted at room temperature, aligned and annealed in a hot isostatic press using isostatic pressure of> 500 bar, preferably> 1000 bar, and more preferably> 1500 bar. The necessary temperatures are> 1200 ° C, preferably> 1350 ° C and more preferably> 1500 ° C. After the temperature treatment has a cohesive connection formed by diffusion processes that allows transparent composite components with RIT values> 75%.

Example 2:

An alkali aluminosilicate glass, which may be biased under pressure in the near-surface layer, is blasted with a transparent spinel ceramic. The dimensions of the square samples are 10 mm x 10 mm. The glass has a thickness of 1 mm, the ceramic thickness is 500 m. The flatness is <5 pm, the roughness is less than 1 nm. Chamfered edges of both joining surfaces allow a precise alignment before the temperature treatment. The joint surfaces are pre-cleaned. The spinel ceramic is provided with a thin Si0 ₂ layer which is rendered hydrophilic by treatment with chemical agents such as nitric acid and an aqueous NH ₄ OH: H ₂ C> 2 solution at elevated temperatures> 80 ° C. After alignment of the samples, the temperature treatment is carried out in a high vacuum oven at temperatures between 200 and 400 ° C. After the temperature treatment, a cohesive bond has formed which allows transparent composite components with RIT values> 75%.

Example 3:

An alkali aluminosilicate glass, which may be biased under pressure in the near-surface layer, is blasted with a transparent spinel ceramic. The dimensions of the square samples are 10 mm x 10 mm. The glass has a thickness of 1 mm, the ceramic thickness is 200 pm. The flatness is <500 nm, the roughness is less than 1 nm. Chamfered edges of both joining surfaces allow precise alignment before the temperature treatment. The joining surfaces are plasma cleaned, uncoated and hydrophilic. After alignment of the samples, the temperature treatment is carried out in a high vacuum oven at temperatures between 200 and 400 ° C. After the temperature treatment, a cohesive bond has formed which enables transparent composite components with RIT values> 75%.

Claims

 claims 1. Composite component of a solid compound of two components, wherein at least one component is a technical ceramic and wherein the components are connected without the use of a connecting material. 2. Composite component according to claim 1, characterized in that the two components are cohesively connected to form a chemical reaction zone. 3. Composite component according to claim 1 or 2, characterized in that the one component is a technical ceramic and the other component is selected from a ceramic, from a second technical ceramic, from a transparent material, from a glass, preferably from a Alkalialumosilikatglas, particularly preferably from an alkali aluminosilicate glass, which is biased in the near-surface layer under pressure, from a hardened glass or from a plastic. 4. Composite component according to one of the preceding claims, characterized in that the technical ceramic has a polycrystalline structure. 5. Composite component according to one of the preceding claims, characterized in that the technical ceramic is a polycrystalline transparent technical ceramic. 6. Composite component according to one of the preceding claims, characterized in that the technical ceramic is a polycrystalline transparent technical ceramic, preferably Mg-Al spinel (MgAI ₂ 0 ₄ ) or the polycrystalline corundum (a-AI ₂ 0 ₃ ). 7. Composite component according to one of the preceding claims, characterized in that it is transparent. Composite component according to one of the preceding claims, characterized in that it is transparent and has a RIT> 60%, preferably> 70% and particularly preferably> 75%, stain frequencies <10%, preferably <3% and particularly preferably <1% and a Haze (Haze) of <10%, preferably 5% and particularly preferably <2%. A method for producing a composite component according to one or more of the preceding claims, characterized in that two components, wherein at least one component is a technical ceramic, are connected without the use of a connecting material by wringing. A method according to claim 9, characterized in that two components, wherein at least one component is a technical ceramic, are connected without the use of a connecting material by a joining pressure. 11. The method according to claim 9 or 10, characterized in that an adhesion promoter is applied to the surface of one or both components and then the components via the adhesion promoter or is blasted. 12. The method according to any one of the preceding claims, characterized in that metals or metal oxides are used as adhesion promoters. 13. The method according to any one of the preceding claims, characterized in that the adhesion promoters are applied by means of coating methods, in particular PVD (eg sputtering, electron beam evaporation, ion-assisted deposition), CVD or sol-gel method , Method according to one of the preceding claims, characterized in that the adhesion promoters are applied in layer thicknesses of 1 nm to 10 pm. 15. The method according to any one of the preceding claims, characterized in that as adhesion promoter Si and Ti, particularly preferably S1O2, T1O2 or ITO (indium tin oxide), which are transparent, can be used. 16. The method according to any one of the preceding claims, characterized 5 characterized in that a surface silicate is carried out by means of flame pyrolytic deposition of a silicon precursor. 17. The method according to any one of the preceding claims, characterized in that the surface is coated by the burning of monosilane (SiH ₄ ) with S1O2. 10. The method according to any one of the preceding claims, characterized in that the surfaces of the abzusenden components have a flatness of <10 pm, preferably of <1 pm, more preferably of <100 nm. 19. The method according to any one of the preceding claims, characterized 15 characterized in that surfaces to be joined are made to fit each other. 20. The method according to any one of the preceding claims, characterized in that after or during the joining an application of pressure and / or temperature is provided. 21. The method according to any one of the preceding claims, characterized in that the applied pressures between atmospheric pressure and 2,000 MPa. 22. The method according to any one of the preceding claims, characterized in that the application of pressure in a hot isostatic Press (HIP) by gas pressure (argon, nitrogen, air) is made. 23. The method according to any one of the preceding claims, characterized in that the temperature range for the joining process between room temperature and temperatures below the melting / softening temperature of the component with the lower melting point 5 / softening temperature are. 24. The method according to any one of the preceding claims, characterized in that to shorten the process times, the pressure and temperature treatment rapid sintering technologies such as the FAST method (Field Assisted Sintering Technology) are used. 10 25. The method according to any one of the preceding claims, characterized in that to be joined surfaces are cleaned before wringing the components. 26. The method according to any one of the preceding claims, characterized in that before the wringing of the components to be joined 15 surfaces by plasma etching, chemical cleaning, tempering in air, in Vacuum or under H ₂ atmosphere or by ion milling of interfering substances are released. 27. The method according to any one of the preceding claims, characterized in that the thermal expansion coefficient (CTE) of the 20 abzusenden components are matched. 28. The method according to any one of the preceding claims, characterized in that the coefficients of thermal expansion (WAK) of the components to be abutted are as similar as possible. 29. The method according to any one of the preceding claims, characterized in that the one component made of a material having a higher CTE exists to thereby generate a compressive stress in the respective other component. 30. Use of the composite component according to one of claims 1 to 9 or of the composite component produced according to one of the method claims as part of a display, for example for a mobile electronic device. 31. Use of the composite component according to one of claims 1 to 9 or of the composite component produced according to one of the method claims as a stove or chimney window.