EP3781338A1

EP3781338A1 - Composite body and method for producing a composite body

Info

Publication number: EP3781338A1
Application number: EP19717312.3A
Authority: EP
Inventors: Bernhard Lang; Dietmar Sprenger; Michael O`SULLIVAN; Peter Polcik
Original assignee: Plansee SE; Plansee Composite Materials GmbH
Current assignee: Plansee SE; Plansee Composite Materials GmbH
Priority date: 2018-04-20
Filing date: 2019-04-11
Publication date: 2021-02-24
Also published as: WO2019201724A1; TW201943679A; TWI786289B; CN111989179B; AT16261U1; CN111989179A

Abstract

The present invention relates to a composite body consisting of a first part and a second part, and also a transitional zone, which is located between a surface or a region of a surface of the first part and a surface or a region of a surface of the second part and connects the first part to the second part in a material-bonding manner, wherein the first part consists of a boride, a boride cermet, a doped boride or a doped boride cermet, the second part consists of copper or a copper alloy, and the transitional zone comprises Ti and copper and has a melting temperature of > 600°C. The present invention also describes a method for producing such a composite body.

Description

COMPOSITE BODY AND METHOD FOR PRODUCING A

cOMPOSITE BODY

The present invention relates to a composite body with the features of the preamble of claim 1 and a method for producing a composite body.

Solid boride, boride base ceramic, doped boride or doped boride base ceramic bodies, particularly TiB ₂ , are known for applications such as targets or electrodes. A bulk body is a solid body made by melt metallurgy or powder metallurgy processes.

The production of bulk boride, a boride base ceramic, a doped boride or a doped boride base ceramic, in particular TiB ₂ , generally takes place via a powder metallurgical route due to the high melting points. Examples of powder metallurgical processes include pressing, sintering, hot isostatic pressing (HIP), hot pressing (HP) or spark plasma sintering (SPS), also in combination with one another. In particular, spark plasma sintering (SPS) has proven to be a very good production route since, due to the supporting effect of DC currents or optionally also pulsed currents during the compression process, bulk-shaped boride components, in particular high-TiB ₂ components Density and high strength can be produced.

TiB ₂ is a hard ceramic which has good thermal conductivities and good electrical conductivities. Furthermore, TiB ₂ exhibits good oxidation resistance in different atmospheres and high resistance to corrosion. Due to these properties, TiB _{2 has} an important importance in coating technology. Due to the ceramic composition, TiB ₂ layers are deposited predominantly by physical as well as chemical vapor depositions. Furthermore, TiB ₂ layers can be applied via slurry coatings or else via Thermal spraying be deposited. In particular for physical vapor deposition (PVD), sputtering targets or arc cathodes are produced from TiB ₂ . Due to its electrical conductivity and corrosion resistance, TiB ₂ bulk materials as well as TiB ₂ coatings are used as cathode material in aluminum production. Furthermore, TiB _{2 is used} in evaporator boats, or as an armor material to name just a few examples.

As a production route for ceramic materials that can be used as targets or as cathode material, especially technologies such as hot pressing or spark plasma sintering come into question. Examples of materials relevant here are: WC, SiC, TiB ₂ , TiC, as well as other carbides, nitrides, borides, boride base ceramics, doped borides or doped boride base ceramics. Due to the high brittleness of these materials and the difficult mechanical processing, which can only be achieved with grinding or wire cutting or special chemical processes, it is necessary to equip these targets with backplates, which enable the fixing of the targets in the coating systems. Furthermore, it is particularly advantageous for the application to apply borides, boride base ceramics, doped borides or doped boride base ceramics to an electrically and thermally highly conductive base body, for example a base body made of a copper or a copper alloy. Such composites, consisting of a first part having the composition of a boride, a boride base ceramic, a doped boride or a doped boride base ceramic, in particular a TiB ₂ and a second part, with the composition of copper or a copper alloy, based on The above properties are also used as electrodes.

Targets are generally understood to mean a composite comprising a base plate or back plate and the actual sputtering material which is used for the layer deposition. Furthermore, targets can also be made from a solid material (sputter material only), without backplate. In the case of target applications, the backplate, in particular consisting of materials such as copper or a copper alloy, serves to increase the mechanical strength of the backplate. see load capacity of the targets or the sputtering material. By increasing the strength and ductility of the targets by applying a backplate to the sputtering material (the sputtering material consists essentially of a boride, a boride base ceramic, a doped boride, a doped boride base ceramic, in particular, the sputtering material of Ti B ₂ In the case of use in a PVD system, there is only an insignificant deformation of the target and consequently no failure, for example a break of the target due to, for example, thermal loads. Usually, the targets used are cooled via ductile back plates or also via so-called cooling plates in a PVD system, the back or cooling plates being arranged on the back of the targets. These back or cooling plates exert pressure on the targets, which in turn could lead to deformation of the targets or to mechanical failure in the case of brittle targets. This effect is additionally reinforced by the fact that the thickness of the sputtering material during the coating process is reduced by the process-related removal. As a result, deformation and / or breakage of the target are more likely to occur. By applying a backplate with increased strength or ductility such failure cases are avoided.

The connection or connection of two different materials such as on the one hand a boride, a boride base ceramic, a doped boride or a doped boride base ceramic, in particular TiB ₂ as a sputtering material, on the other hand, the metallic copper or the metallic copper alloy of the back plate, provides a technical challenge. In particular, the wetting behavior and / or bonding behavior of copper or a copper alloy on ceramic materials such as a boride, a boride base ceramic, a doped boride or a doped boride base ceramic, in particular the connection of TiB ₂ on copper, should be as broad as possible be guaranteed and have as few untethered areas (defects) as possible. The connection of ceramic targets with metallic backplates is known for example for tungsten carbide targets. One way to provide tungsten carbide (WC) targets with a backing plate is to back-cast them with copper or a copper alloy, as described in the Research Disclosure publication of May 2014 ("WC-Cu Are Cathode or sputtering target ", Research Disclosure database number 601040, May 2014, ISSN 0374-4353). This publication describes the wetting behavior of copper or a copper alloy on, for example, tungsten carbide (WC). In this case, wetting agents such as boron or nickel can be used and applied by electroplating, or by means of slurry or by means of PVD, as a thin film on the ceramic part in order to increase the wetting behavior before it is back-coated with copper or a copper alloy. This method is for Boride as a result of the bad

Wettability and / or poor bonding of copper or a copper-based alloy unsuitable. The wettability is described in detail in the publication by Passerone et al., "Wetting of Group IV diborides by liquid metals" (J Mater Sei (2006) 41 (Issue 16), pp 5088-5098).

One way to avoid wetting problems is to dope the copper melt with boron, as described in detail in the publication by Aizenshtein et al. in the article "The Nature of TiB ₂ Wetting by Cu and Au" (Journal of Materials Engineering and Performance, Volume 21 (5) May 2012-655). WO 2012063524 describes bonding (bonding) of several target parts to a copper backplate by low-melting solder.

A disadvantage of doping the copper melt with boron is that with increasing doping, the properties of the pure copper are changed. Furthermore, the use of low-melting solders is disadvantageous because they have a low thermal load capacity.

The object of the present invention is to provide an improved composite body, as well as an improved method for producing such a composite body. Furthermore, there is the task of The present invention is to provide a reliable and reproducible, as well as thermally stable compound of copper or a copper alloy with a boride, a boride base ceramic, a doped boride, a doped boride base ceramic, in particular TiB ₂ .

The objects are achieved by providing a first part of a boride, a boride base ceramic, a doped boride or a doped boride base ceramic and a second part consisting of copper or a copper alloy and a transition zone between the first and second part, which Ti and copper and having a melting temperature> 600 ° C, according to claim 1, and a method for producing a composite body having the features of claim 9. Advantageous embodiments of the invention are specified in the dependent claims.

The invention described herein eliminates the problem of wettability by depositing individual or alternating layers of titanium, copper or titanium-copper on a base body consisting of a boride, a boride base ceramic, a doped boride or a doped boride base ceramic, in particular one TiB ₂ body before it is back-cast with liquid copper or a liquid copper alloy, or before the second part is applied by cold gas spraying (CGS).

These individual or alternating titanium or copper layers or titanium-copper layers are thereby by cold gas spraying (CGS) and / or by CVD (Chemical vapor deposition) or by PVD (physical vapor depository) or by slurry or by low-pressure plasma spraying the surface of the boridic body (boride, boride basic ceramic, doped boride, doped boride basic ceramic or TiB ₂ ) is applied. Furthermore, the invention describes a temperature-resistant compound of a first part (boride, boride base ceramic, doped boride, doped boride base ceramic or TiB ₂ ) with a second part (copper or copper alloy) via a transition zone which has a temperature resistance of at least 600 ° C., preferably at least 700 ° C and more preferably at least 800 ° C. The invention describes a reproducible and reliable wettability of the boride, the boride basic ceramic, the doped boride, the doped boride basic ceramic, but in particular the TiB ₂ , with liquid copper or a copper alloy. The advantage of this invention over the prior art lies in the possibility of technologically converting them in production, without the properties of the boride, the boride base ceramic, the doped boride, the doped boride base ceramic, or, for example, the Ti B ₂ , to change. Another advantage of this invention over the prior art is that it does not require changing the composition of the copper or copper alloy used for back casting, such as by adding boron to increase wettability.

According to the present invention, the composite body has a first part, a second part and a transition zone. The transition zone is located between a surface or a region of a surface of the first part and a surface or a region of a surface of the second part, and connects the first part to the second part in a materially bonded manner. The first part consists of a boride, a boride base ceramic, a doped boride or a doped boride base ceramic. In particular, the first part consists of TiB ₂ , a TiB ₂ base ceramic, a doped TiB ₂ or a doped TiB ₂ base ceramic.

Borides are understood as meaning a compound of one metal or even more metals with boron. Borides also include, inter alia, those borides which have the MeB ₂ or the Me ₂ Bs structure by crystallography. Particularly good conductive, hard and highly melting types such as titanium boride (TiB ₂ ) should be mentioned here. Structurally, the titanium boride is constituted by alternating layers of densely packed metal atoms and hexagonal hole networks, resulting in the good conductivities mentioned above. Exemplary of boride compounds, in particular TiB _2, VB _2, CrB _2, ZrB _2, NbB _2, M0B2, HfB _2, TaB _2, UB 2, AlB 2, ReB _2, MgB ₂ and WB ₂ or W ₂ B ₅ may be mentioned , Boride mixed ceramics are understood as meaning the mixtures of at least two of the abovementioned borides. The doped borides or boride mixed ceramics can additionally contain elements or compounds, without the total proportion of additional elements exceeds 20 mol%, in particular 10 mol%. As additional elements, the boride or the boride mixed ceramic pure metals, such as Fe, Ni, Co, Cr, Ti, Mo, Zr or carbides, such as TiC, WC, NbC but also pure elements such as C, B or Si be added. In particular, TiB ₂ with additionally doped B or TiB ₂ with additionally doped Si can be mentioned here.

The first part of the composite consists of a predominantly texture-free microstructure, without preferred grain orientation, with an average particle size <20 μm, preferably <10 μm, particularly preferably <5 μm. The second part of the composite body consists of essentially pure copper or a copper alloy and has an average particle size of> 0.5 mm, preferably> 1 mm, particularly preferably> 1.5 mm. Copper alloys are understood as meaning alloys with copper, copper being the main constituent and the total fraction of alloying elements being less than 50 wt%, preferably <30 wt% and particularly preferably <20 wt%. Examples of copper alloys include CuZn, CuZnSi, CuMg, CuAI, CuBe, CuCrZr and CuZn. The transition zone includes, inter alia, Ti and copper. According to the invention, the transition zone has a melting temperature (or a softening temperature)> 600 ° C., preferably a melting temperature> 700 ° C., and particularly preferably a melting temperature> 800 ° C. The transition zone is free of low-melting phases, in this document being understood as low-melting those temperature ranges which are of the order of the melting points of indium or tin.

The connection thus has a considerably improved thermal load capacity compared with the prior art. This is particularly interesting because higher power densities and / or sputtering rates can thus be realized in a coating system.

With regard to the melting temperature of alloys, reference is made to the liquidus line of the corresponding alloy, with the copper alloys used here being below 600 ° C., preferably below 700 ° C., and particularly preferably below 800 ° C., no formation of liquid phases occurs. The thermal stability of the composite is by a kiln travel at 600 ° C, or 700 ° C or 800 ° C assignable, which must not form any liquid phases, which then inevitably loss of bonding (or a softening of the transition zone) between would lead to the first part and the second part or to a change in shape of the composite body. To check the temperature resistance of the composite and in particular the temperature resistance of the transition zone of the composite body is mounted in an oven so that a part and at least the entire transition zone of the composite are free-standing, ie that a part and at least the entire transition zone are not stretched or fixed. The orientation of the composite in the furnace is further such that the plane of the transition zone, or in other words the transition between the first part and the second part, is oriented parallel to gravity, so that in case of softening of the transition zone or the formation of liquid phases in the transitional zone, by the action of gravity, which can detach one part of the other part or move it against each other. Then the oven is brought to temperature. After reaching the desired temperature of 600 ° C, preferably 700 ° C and more preferably 800 ° C, in the core of the composite body, after a holding time of one hour, the furnace is cooled again. Should the melting temperature or the softening temperature of the transition zone be less than the set temperature of the furnace, the free, non-tensioned or fixed part, from the clamped part of the composite body, will be released or shifted against each other by the action of gravity.

The transition zone is a diffusion zone at the transition between the boride, a boride base ceramic, a doped boride, a doped boride base ceramic, in particular of TiB _{2 of} the first part and the solidified or solidified, back-cast melt, consisting of copper or a Copper alloy (second part) arises. Furthermore, the transition zone may be a zone which, at the transition between the boride, a boride base ceramic, a doped boride, a doped boride base ceramic, in particular of TiB2 of the first part and the second part applied via CGS arises.

In an advantageous embodiment, the transition zone of the composite body is substantially free of typical solder elements such as indium, tin, germanium, silver, palladium, nickel, platinum, cobalt, manganese or gold. The transition zone has an indium, tin, germanium, silver, palladium, nickel, platinum, cobalt, manganese or gold content of in each case <5000 ppm, preferably in each case <2000 ppm, particularly preferably in each case <1000 ppm.

In an advantageous embodiment, the first part of the composite body consists of Ti B ₂ , a TiB ₂ base ceramic having at least 20 mol. % TiB ₂ , preferably a TiB ₂ base ceramic with at least 30 mol. % TiB ₂ and more preferably a TiB ₂ base ceramic having at least 50 mol% TiB ₂ . The invention has proven to be particularly suitable in the application of an Are cathode made of TiB ₂ material. Due to the temperature-resistant, cohesive and highly electrically conductive connection between TiB ₂ and the back plate made of copper, the Are cathode could be operated with a diameter of 63 mm and a height of 32 mm for several hours in the arc process, without the stability of the cathode has been affected would.

In an advantageous embodiment, the first part of the composite body consists of carbon-doped T1B2. Carbon-doped TiB ₂ is understood to mean the addition of up to 10 mol% of carbon to the TiB ₂ , preferably at least 5 mol% of carbon to the TiB _2, and more preferably at least 2 mol% of carbon to the T1B2. The advantages that result from the doping of a TiB ₂ ceramic with graphite, are in the publication

WO201 1 137472A1.

According to a further advantageous embodiment of the invention, the transition zone has an average thickness of between 5 and 500 μm, preferably between 8 and 300 μm, particularly preferably between 10 and 200 μm.

The layer thickness of the transition zone is determined in a stereolithic microscope or also in a light microscope. This becomes a metallographic Cut is placed perpendicular to the plane of the transition zone and then determines the layer thickness in a scanning electron microscope or in a light microscope at a suitable magnification. The determination of the layer thickness of the transition zone should be carried out at representative points of the finish. In this case, at least ten representative sites should be examined and an average value should be created, which represents the mean layer thickness of the transition zone.

According to a further advantageous embodiment of the invention, both the concentration of the copper in the transition zone, and the concentration of titanium in the transition zone, starting from the surface of the first part to the surface of the second part, each show a concentration profile. The concentration of copper drops from the surface of the second part consisting of copper or a copper alloy to the surface of the first part consisting of a boride, a boride base ceramic, a doped boride or a doped boride base ceramic , The concentration of titanium falls from the surface of the first part, which consists of a boride, a boride base ceramic, a doped boride or a doped boride base ceramic, to the surface of the second part, which consists of copper or a copper alloy. The change in concentration can be carried out continuously, but also abruptly. The transition zone is clearly visible in a light microscope or in a scanning electron microscope. The concentration curves of titanium and copper can be determined by scanning electron microscopy using energy-dispersive analysis (EDX).

According to a further advantageous embodiment of the invention, the average hardness in the transition zone is at least 10% higher, preferably at least 20% higher, than the average hardness of the second part, which consists of copper or a copper alloy. Hardness is the mechanical resistance that a body counters when penetrating another, harder body. Standardized test specimens are pressed into the workpiece surface under specified conditions. Preferably, the microhardness test according to Vickers is used, but it can also be a microhardness measurement after Rockwell or Brinell done. The microhardness measurement is preferably carried out in accordance with DIN EN ISO 6507. For representative hardness measurements, at least 10 measurements should be carried out under the same conditions at a respective representative point and an average value is formed from these measurements, which represents the mean hardness value.

According to a further advantageous embodiment, at least 50%, preferably at least 70%, particularly preferably at least 90%, of the transition zone exhibit a metallurgical connection to the surface of the first part and to the surface of the second part. This compound as well as its percentage can be done non-destructively by means of an ultrasound examination or an X-ray examination of the composite body and also by making cross-sections and subsequent examination of the transition zone in a light microscope or in a scanning electron microscope. By means of an ultrasonic test, pores and unattached areas between the boride, the boride base ceramic, the doped boride, the doped boride base ceramic, in particular the TiB ₂ , and the copper or the copper alloy can be visualized. The ultrasonic test, starting from the surface of the copper or the copper alloy, to the ceramic (boride, boride base ceramic, doped boride, doped boride base ceramic or TiB ₂ ), as well as from the ceramic surface starting, towards the copper or the Copper alloy, to be performed. The ultrasound test provides a spatially resolved image, in which mostly in color, the non-bonded areas and other defects at the transition ceramic (boride, boride base ceramic, doped boride, doped boride base ceramic or TiB ₂ ) to copper or copper Alloy, surface visible. The connected and untethered areas are clearly visible in the picture for a person skilled in the art. The area of the non-bonded areas is determined by adding up all unbound single areas occurring in the measuring area. According to the invention, the ratio of the sum of all unattached surfaces to the measurement surface is always <0.5, preferably <0.3 and particularly preferably <0.1. This means that the surface bonding of the ceramic (boride, boride base ceramic, doped boride, doped boride base ceramic or TiB ₂ ) to the copper or to the Copper alloy always higher than 50%, preferably higher than 70%, particularly preferably higher than 90%.

By means of an X-ray test, pores and unattached areas between the ceramic (boride, boride base ceramic, doped boride, doped boride base ceramic or TiB ₂ ) and the copper or the copper alloy can be made visible. The X-ray inspection can be carried out starting from the surface of the copper or the copper alloy, towards the ceramic, as well as from the ceramic surface, to the copper or the copper alloy. The X-ray examination yields a spatially resolved image in which the non-bonded regions and also other defects at the transition ceramic (boride, boride base ceramic, doped boride, doped boride base ceramic or TiB ₂ ) to copper or the copper alloy, flatly visible. The connected and untethered areas are clearly visible in the picture for a person skilled in the art. The area of the non-attached areas is determined by summing up all non-connected individual areas occurring in the measuring area. According to the invention, the ratio of the sum of all unattached areas to the measurement area is always <0.5, preferably <0.3 and particularly preferably <0.1. This means that the areal bonding of the ceramic (boride, boride base ceramic, doped boride, doped boride base ceramic or TiB ₂ ) to the copper or to the copper alloy is always higher than 50%, preferably higher than 70%, particularly preferably higher than 90 % is.

According to a further advantageous embodiment, with a tensile load between the first part and the second part, with a loading direction normal to the surfaces of the first and the second part connected via a transition zone, the breaking stress is at least 15 MPa, preferably> 20 MPa , particularly preferably> 30 MPa, the breaking stress being based on the connected part of the transition zone. With the aid of a tensile test according to, for example, DIN EN ISO 6892-1: 2009 1: 2009-12, the breaking stress of the compound of the ceramic (boride, boride basic ceramic, doped boride, doped boride basic ceramic or TiB ₂ ) with the copper or the copper alloy. In this case, the composite body is clamped in the tensile testing machine so that the pulling direction or the loading direction is normal to the surfaces of the copper or copper alloy connected to the ceramic (boride, boride basic ceramic, doped boride, doped boride basic ceramic or Tiss 2), in particular TiB ₂ , connected via a transition zone. Subsequently, the component is loaded until it breaks. The measured values of the tensile test are related to the connected area, ie to the pure fracture surface. The fracture surface (connected area) is clearly recognizable to a person skilled in the art. According to the invention produced bodies show a tensile strength, based on the fracture surface, of> 15 MPa, preferably> 20 MPa, more preferably> 30 MPa.

The present invention further relates to a method for producing a composite body comprising a first part and a second part, and at least one transition zone which is formed between a surface or a surface region of the first part and a surface or a surface region of the second part, characterized by the following Steps:

- Pulvermetallurgische production of the first part of a boride, a

Boride base ceramic, a doped boride or a doped boride base ceramic,

Coating at least one surface portion of the first part with at least one intermediate layer comprising titanium or alternatively titanium and copper,

The second part of the composite body is produced by back-casting the interlayer-coated surface of the first part with copper or a copper alloy or by CGS-coating the interlayer-coated surface of the first part with copper or a copper alloy,

- Forming a transition zone between the first and second

Part.

With the method according to the invention for producing a composite body, the advantages explained above in relation to the component according to the invention are reliably and reliably achieved. Furthermore, the previously mentioned Advantageous embodiments of the invention also advantageous for the inventive method.

It is particularly preferred that the first part is manufactured by powder metallurgy, the second part by means of back-casting and that prior to the casting the surface or part of the surface of the first part is provided with at least one intermediate layer of titanium or alternatively of titanium and copper.

Among other things, the following positive effects are achieved:

Good wettability of the copper or copper alloy on the first part provided with at least one intermediate layer

High temperature resistance of the composite material thus produced and a transition zone having a melting point higher than 600 ° C.

Under-casting is understood to mean the molten-metallurgical application of a material to a base material, the base material always being in the solid state of aggregation in the process parameters used. The first part is coated on at least one surface portion with at least one intermediate layer, which includes titanium or, alternatively, titanium and copper, before the back-casting. In back-casting, for example, a solid bulk-shaped base material (this is usually surface-coated with at least one intermediate layer) consisting of a boride, a boride mixed ceramic, a doped boride or a doped boride mixed ceramic is introduced into a furnace chamber. Subsequently, a second material consisting of copper or a copper alloy is placed on the base material. Thereafter, the initially loose, not yet cohesively connected composite body is heated under a suitable process atmosphere, possibly with a ramp function, until the overlying material consisting of copper or a copper alloy melts, wetting the non-melting base material. For example, the melting point for pure copper is 1085 ° C. The temperature of the oven should be selected so that the temperature is above the liquidus line of the alloy composition in the phase diagram. When casting, the stove must be for a sufficient time to be maintained at a temperature above the liquidus, so that a complete melt of the overlying copper or copper alloy can form. A transition zone forms between the first part and the second part. The transition zone is formed by dissolving the titanium or, alternatively, the titanium / copper layer (s) in the back-cast copper or copper alloy. After a desired hold time above the melting point, the furnace is again cooled to below the melting point of copper or copper alloy. The cooled composite shows after solidification of the copper or the copper alloy, a first part consisting of a boride, a boride base ceramic, a doped boride or a doped boride base ceramic, and a second part consisting of copper or a copper alloy and a transition zone between the first and second part, which contains Ti and copper and has a melting temperature or softening temperature of> 600 ° C. Optionally, a mechanical machining or reworking of the solidified composite body can take place by turning, milling, cutting, grinding, lapping, pressing, embossing or rolling. Subsequently, welding, soldering, joining or adhesive methods can also be carried out on the composite body. Furthermore, the composite body can subsequently be engraved, etched or eroded. In addition to the mechanical processing of the composite body, thermal post-treatments of the composite body can also be carried out, such as, for example, annealing, oxidation or else reduction in order to achieve desired microstructural properties.

It is preferred that the first part is produced by powder metallurgy, the second part is applied by cold gas spraying (CGS), and that before the application of the second part, the surface or a part of the surface of the first part with at least one intermediate layer of titanium or alternatively of titanium and Copper is provided.

Cold gas spraying (CGS) is a coating process in which powder particles with very high kinetic energy and low thermal energy are applied to a carrier material. A high pressure dessicating gas (for example air, He, N2 or mixtures thereof) is expanded by means of a convergent divergent nozzle (also referred to as supersonic nozzle). A typical nozzle shape is the Laval nozzle. Depending on the process gas used, gas velocities of, for example, 300 to 1200 m / s (at N2) up to 2500 m / s (at He) can be achieved. For example, the coating material is injected into the gas stream in front of the narrowest cross section of the convergent divergent nozzle forming part of the spray gun, typically accelerated to a speed of 300 to 1200 m / s and deposited on a substrate. Heating the gas in front of the convergent-divergent nozzle increases the flow rate of the gas during the expansion of the gas in the nozzle and thus also the particle velocity. Typically, cold gas spraying uses a gas temperature of from room temperature to 1000 ° C. In particular, ductile materials with a cubic face-centered and hexagonal close-packed lattice can be sprayed into dense, well-adhering layers by means of CGS. In general, CGS is used for the deposition of a metallic layer on a metallic substrate, the deposition of a metallic layer on a ceramic substrate is currently not an established method.

In the case of the CGS, the layer build-up takes place in layers from the individual particles of the coating material. For the quality of a CGS layer, the adhesion of the coating material to the substrate and the cohesion between the particles of the coating material are crucial. Basically, the adhesion, both in the area of the coating material / substrate interface, and between the particles of the coating material, is understood to mean an interaction of several physical and chemical adhesive mechanisms and in some cases not yet comprehensively. Due to the low process temperature, the powder is not melted in the cold gas spraying, but in the non-molten state on the substrate to be coated, resulting in a layer builds up. Due to the high kinetic energy, due to the high velocity of the powder moving in the gas stream, mechanical impingement occurs when the powders hit the substrate surface, whereby the clamping is supported by the process temperature. Such layers produced by means of cold gas spraying can be recognized in the microscope by the fact that the layer of individual powder particles consists. The powder particles in a layer applied by cold gas spraying show no melting phase and are still clearly visible in the deposited layer. Due to the high kinetic impact energy, the powder particles undergo deformation and have an aspect ratio greater than 1. The crystal orientation of the individual grains of the applied CGS layer is statistically distributed and shows no preferential direction.

According to an advantageous production method of the invention, it is provided that the step of powder-metallurgical production of the first part by using a TiB ₂ or a carbon-doped TiB ₂ or a TiB ₂ base ceramic with> 20 mol% TiB ₂ , preferably a TiB ₂ Base ceramic with> 30 mol% TiB ₂ and particularly preferably a TiB ₂ base ceramic with> 50 mol% TiB ₂ , takes place. Carbon-doped TiB ₂ is understood as meaning the addition of up to 10 mol% of carbon to the TiB ₂ , preferably at least 5 mol% of carbon to the TiB ₂ and particularly preferably at least 2 mol% of carbon to the TiB ₂ .

According to an advantageous manufacturing method of the invention, it is provided that at least one intermediate layer on a boride first part (boride, boride base ceramic, doped boride, doped boride base ceramic or TiB ₂ ) preferably via cold gas spraying (CGS) or alternatv is applied via low-pressure plasma spraying or via vacuum plasma spraying. Cold gas spraying (CGS) is a coating process in which powder particles with very high kinetic energy and low thermal energy are applied to a carrier material. In plasma spraying, the powder particles are melted in a gas stream and impinge on a substrate to be coated in the molten state. Powder particles of plasma-sprayed layers likewise have an aspect ratio, with plasma-sprayed layers indicating the layer morphology on deposition of molten particles and differing significantly from those produced by CGS-produced layers.

According to an advantageous manufacturing method of the invention, it is provided that at least one intermediate layer on a first part (consisting made of boride, boride basic ceramic, doped boride, doped boride basic ceramic or TiB ₂ ) via PVD (physical vapor deposition) or CVD (Chemical vapor deposition) is applied. PVD and CVD layers generally show a columnar layer growth and a columnar stalk structure and are clearly different from those deposited via CGS or also via plasma spraying. PVD and CVD layers usually show texturing in the coating direction.

According to an advantageous manufacturing method of the invention, it is provided that the intermediate layer is applied in multiple layers and the individual layers of the multilayer intermediate layer may have a different composition. Individual layers of the intermediate layer can consist of essentially pure titanium, essentially pure copper or a mixture of titanium and copper, or of a titanium-copper alloy.

According to an advantageous manufacturing method of the invention, it is provided that the intermediate layer or at least one layer of the intermediate layer, with an average of at least 10 pm layer thickness, preferably with an average of at least 15 pm is applied. The determination of the layer thickness of the intermediate layer takes place in the scanning electron microscope. Here, a metallographic cut is placed perpendicular to the plane of the intermediate layer and then measured the layer thickness in a scanning electron microscope at a suitable magnification. The determination of the layer thickness should be carried out at representative points of the finish. Here, at least ten different, representative points are to be examined with regard to their layer thickness and an average value is to be created, which provides a value for the average thickness of the intermediate layer. According to an advantageous manufacturing method of the invention, it is provided that a substantially pure titanium intermediate layer or in a multilayer structure of the intermediate layer, a layer of the intermediate layer consisting of substantially pure titanium, is applied with a layer thickness of at most 100 pm. According to an advantageous manufacturing method of the invention, it is provided that a copper-titanium intermediate layer or in a multilayer structure of the intermediate layer, a layer of the intermediate layer consisting of substantially pure copper or a layer of the intermediate layer consisting of copper and titanium, with a Layer thickness of a maximum of 500 pm is applied. Due to the ductility of the copper, substantially pure copper layers or copper-titanium layers can be applied thicker than substantially pure titanium layers without delamination of the applied layers.

With a further method according to the invention for producing a composite body, the advantages explained above in relation to the component according to the invention are reliably and reliably achieved. Furthermore, the aforementioned advantageous embodiments of the invention are also advantageous for the method according to the invention.

Further advantages of the invention will become apparent from the following description of embodiments with reference to the accompanying figures.

From the figures show:

1 shows a scanning electron micrograph of the transition zone between TiB ₂ and copper in sample No. 1 (see Tables 1 and 2)

Fig. 2: Surface of the image provided with an intermediate layer

Sample No. 1 (see Tables 1 and 2) before casting with copper

3 shows a scanning electron micrograph of the transition zone between TiB ₂ and copper in sample No. 2 (see Tables 1 and 2)

4: microhardness measurement according to DIN in the transition zone of the composite body in sample No. 1 (see Tables 1 and 2) 5 shows a microhardness measurement according to DIN in the back-cast copper part of the composite body in sample No. 1 (see Table 1 and 2)

Examples:

For the examples according to the invention, two cylindrical TiB ₂ blanks were produced by means of spark plasma sintering and then machined to a diameter of 57 mm and a height of 12 mm. Before casting, each surface of the TiB ₂ blanks was coated with a first Ti intermediate layer by means of CGS. The following CGS process parameters were used for the first interlayer (see Table 1):

After applying the first Ti intermediate layer by means of CGS, a second Cu intermediate layer was applied by means of CGS. The following CGS process parameters were used for the application of the second intermediate layer (see Table 2):

Table 2

Subsequently, the TiB ₂ -carriers provided with a first Ti-intermediate layer and a second Cu-intermediate layer were described as follows, back-cast by means of copper. The CGS coated first part became with the coated side up on the bottom of a graphite cylinder. The graphite cylinder has a larger diameter than the coated TiB ₂ rounds and also has a larger height. On the free space above the TiB ₂ -Ronde copper part (s) (so-called "ingots") were made of essentially pure copper.

Subsequently, the graphite cylinders were placed in an oven and heated to 900 ° C in a H ₂ atmosphere. After reaching 900 ° C, the graphite cylinders were further heated in a N ₂ atmosphere to a temperature of 1 150 ° C (note: above the melting temperature of copper, which is 1085 ° C). After reaching 1 150 ° C, the temperature was maintained for 20 min. Subsequently, the graphite cylinders were led out of the hot zone of the furnace at a speed of 1 cm / min. The cooling of the TiB ₂ copper composite thus took place via a directional solidification of the melt, which led to a stress-free, but rather coarse-crystalline microstructure of the back-cast copper. After cooling, TiB ₂ rounds cast in such a way with copper show a very good bond between the two materials (TiB ₂ and copper), via a formed transition zone. Composites produced in this way show no cracks or delamination in the transition. The slow cooling process also minimizes the thermal stresses between the TiB ₂ blank and the solidified copper backplate.

FIG. 1 shows the TiB ₂ / copper transition in a scanning electron micrograph in transverse section (sample No. 1, see Table 1). 1 shows the first part of TiB ₂ (A, dark area) on the left side of the figure, the second part consisting of copper (C, bright area) on the right side of the figure. The connection of the first part to the second part is completed over the entire surface via a transition zone and there are no cracks or flaws recognizable. The transition zone (B) spreads more or less semicircular starting from the surface of the TiB ₂ toward the copper and has an average thickness of about 15 pm. An exact determination of the layer thickness of the transition zone is difficult in this sample, as due to the layer formation in the cold gas spraying process and the low Layer thickness (in relation to the powder size) was not complete coverage of the TiB2 Rondenoberfläche with an intermediate layer. The Tiss2-Ronden- surface after application of the second intermediate copper layer by means of CGS is shown in Figure 2. The superficial degree of coverage of the CGS-applied intermediate layers is approximately 50%. The original covering of the surface of the round blank with the intermediate layers remains recognizable even after the back-casting in cross-section and is clearly visible in FIG. Despite the rather low coverage rate, which was originally around 50%, Tiss2-copper compounds produced in such a way by casting show a full-area connection between copper and T1B2 without cracks or defects in the transition region.

FIG. 3 shows the transition Tiss2 / copper in a scanning electron micrograph in transverse section (sample No. 2, see Table 1). FIG. 3 shows the first part of T1B2 (A, dark) on the left side of the figure, the second part consisting of copper (C, light) on the right side of the figure. The connection of the first part to the second part is completed over the entire area. The transition zone (B) spreads over the entire surface from the surface of the T1B2 starting to the copper and shows an average thickness of about 200 pm. Due to the significantly thicker deposited intermediate layers in Sample No. 2, compared to Sample No. 1 (Figures 1 and 2), the surface of the T1B2 is completely covered by the intermediate layers, which is clearly visible in the illustrated cross section in Figure 3.

FIG. 4 shows a microhardness measurement in the transition region (B) of sample no. 1 according to DIN EN ISO 6507, and FIG. 5 shows a microhardness measurement in the cast-off second part consisting of copper (C), sample no. The back-poured second part shows a mean microhardness of 83 HV0.1 and the transition zone shows a microhardness of 159 HV0.1 on average. That is, the average hardness in the transition region of Sample No. 1 is more than 90% higher than the average hardness of the second part, consisting of substantially pure copper.

Claims

claims

1) A composite body comprising a first part and a second part, and a transition zone, which is located between a surface or a portion of a surface of the first part and a surface or a portion of a surface of the second part and the first part with the second part cohesively connects, where

the first part consists of a boride, a boride mixed ceramic, a doped boride or a doped boride mixed ceramic,

- the second part consists of copper or a copper alloy, and

- The transition zone includes Ti and copper and has a melting temperature> 600 ° C.

2) A composite body according to claim 1, wherein the transition zone shows an elemental content of indium, tin, germanium, silver, palladium, nickel, platinum, cobalt, manganese or gold of <5000 ppm each.

3) Composite body according to claim 1 or 2, wherein the first part of TiB ₂ , a TiB2 base ceramic with at least 50 mol% of TiB ₂ or of carbon-doped TiB ₂ consists.

4) Composite body according to one of the preceding claims, wherein the

Transition zone has a thickness between 5 and 500 pm. 5) Composite body according to one of the preceding claims, wherein both the concentration of the copper in the transition zone, as well as the concentration of titanium in the transition zone, starting from the surface of the first part, towards the surface of the second part, each a graded concentration Show run.

6) Composite body according to one of the preceding claims, wherein the

average hardness in the transition zone, at least 10% higher than the mean hardness of the second part.

7) A composite body according to any one of the preceding claims, wherein at least 50% of the transition zone exhibits metallurgical cohesive bonding to the surface of the first part and to the surface of the second part.

8) A composite according to any one of the preceding claims, wherein at a tensile load between the first part and the second part, with a loading direction normal to the transition zone connected surfaces of the first and second part, the fracture stress is at least 15 MPa, wherein the fracture stress on the tailed part of the

Transition zone is related.

9) A process for producing a composite body consisting of a

first part and a second part, as well as at least one transition zone which between a surface or a surface region of the first formed part and a surface or a surface region of the second part, characterized by the following steps:

Powder metallurgical production of the first part from a boride, a boride base ceramic, a doped boride or a doped boride base ceramic,

- Forming a transition zone between the first and second part.

10) The method of claim 9, wherein the first part of a TiB ₂ or a carbon-doped TiB ₂ or a TiB ₂ base ceramic with min. 50 mol. % TiB _{2 is} produced.

1 1) Method according to claim 9 or 10, wherein the intermediate layer via

Cold gas spraying (CGS) or low pressure plasma spraying is applied. 12) The method of claim 9 to 1 1, wherein the intermediate layer via PVD or CVD or via a slurry coating (suspension coating) is applied. 13) The method of claim 9 to 12, wherein the intermediate layer is applied in multiple layers and wherein the individual layers of the multilayer intermediate layer may have a different composition.

14) The method of claim 9 to 13, wherein the intermediate layer or a layer of the intermediate layer is applied with at least 10 pm layer thickness.

15) The method of claim 9 to 14, wherein a substantially pure titanium intermediate layer or in a multi-layer structure of the intermediate layer, a layer of the intermediate layer consisting of substantially pure titanium, is applied with a maximum thickness of 100 pm.

16) The method of claim 9 to 15, wherein a copper-titanium intermediate layer or in a multilayer structure of the intermediate layer, a layer of the intermediate layer consisting of substantially pure copper or a layer of the intermediate layer consisting of copper and titanium, with a layer thickness of a maximum of 500 pm is applied.