TWI786289B - Composite body and process for producing a composite body - Google Patents

Abstract

The present invention relates to a composite body consisting of a first portion and a second portion, and a transition zone which is between a surface or a region of a surface of the first portion and a surface or a region of a surface of the second portion and materially bonds the first portion to the second portion, wherein the first portion consists of a boride, a mixed boride ceramic, a doped boride or a doped mixed boride ceramic, the second portion consists of copper or a copper alloy, and the transition zone includes Ti and copper and has a melting temperature ＞ 600°C. The present invention further describes a process for producing such a composite body.

Description

Composite body and method of making composite body

The present invention relates to a composite body having the characteristics of the preamble of claim 1, and to a method for manufacturing the composite body.

Bodies consisting of solid borides, boride-based ceramics, doped borides or _doped boride-based ceramics, in particular TiB2, are known for applications such as targets or electrodes. A bulk body is to be understood as a solid produced by melt metallurgy or powder metallurgy.

It is generally effective to manufacture borides, boride-based ceramics, doped borides or doped boride _- based ceramics, especially bulk TiB2, by the powder metallurgy route, which This is due to the high melting point of these blocks. Examples of powder metallurgy methods include pressing, sintering, hot isostatic pressing (HIP), hot pressing (hot pressing; HP) or spark plasma sintering (spark plasma sintering; SPS) and their interactions with each other. combination. In particular, we have found spark plasma sintering (SPS) to be a very good manufacturing route, since bulk boron can be produced with the support of direct current or optional pulsed current in the compaction process. Compound components, especially _TiB2 components with high density and high strength.

TiB ₂ is a hard ceramic with good thermal conductivity and good electrical conductivity. In addition, TiB ₂ exhibits good oxidation resistance and high corrosion resistance in different ambient atmospheres. Because of these properties, _TiB2 is very important in coating technology. Since the _TiB2 layer is a ceramic composition, it is mainly deposited by physical vapor deposition but can also be deposited by chemical vapor deposition. Furthermore, the _TiB2 layer can be deposited by slurry coating or by thermal spraying methods. _In particular, for physical vapor deposition (PVD), sputtering targets or arc cathodes are fabricated from TiB2. Due to the electrical conductivity and corrosion resistance of the TiB ₂ bulk material and TiB ₂ coating, it can be used as a cathode material for the manufacture of aluminum. In addition, TiB ₂ can be used in evaporator boats or armor materials, etc., just to mention a few examples.

As a production route of a ceramic material usable as a target or a cathode material, in particular, techniques such as hot pressing or discharge plasma sintering are possible. Examples of materials referred to here are: WC, SiC, TiB ₂ , TiC, but also other carbides, nitrides, borides, boride-dominated ceramics, boride-doped or boron-doped Chemical-based ceramics. Due to the high brittleness of these materials and the difficulty of machining (which in some cases can only be done by grinding or wire cutting or specific chemical methods), it is necessary to equip these targets with the ability to hold them in place. Backplate in coating line. Furthermore, particularly advantageous applications are the application of borides, boride-based ceramics, doped borides or doped boride-based ceramics to bodies with good electrical and thermal conductivity, for example made of copper or Body made of copper alloy. Due to the above-mentioned properties, this composite body composed of the first part and the second part can also be used as an electrode, wherein the first part contains borides, boride-based ceramics, doped borides or doped Boride-based ceramics, especially TiB ₂ and the like, and the second part includes copper or copper alloys and the like.

We will generally understand target to mean the composite body consisting of the baseplate or backing plate and the actual sputtering material used for layer deposition. Furthermore, targets can also be produced from solid material (only sputtered material) without a backing plate. In the case of target applications, particularly backing plates composed of materials such as copper or copper alloys can be used to increase the mechanical elasticity of the target or sputtering material. Increase the strength and ductility of the target by applying a backing plate on the sputtering material (where the sputtering material is basically boride, boride-based ceramic, doped boride or doped boride-based The main ceramic; the sputtering material essentially consists of TiB ₂ ), when used in a physical vapor deposition system, causes only insignificant deformation of the target and thus no target deformation due to e.g. thermal stress Destroy (e.g. rupture). Usually, the targets used are cooled by means of a ductile backing plate or by means of so-called cooling plates in physical vapor deposition systems, wherein the backing plate or cooling plate is arranged on the rear side of the target. These backing or cooling plates exert pressure on the target, which may in turn cause deformation of the target, or, in the case of brittle targets, rupture of the target when subjected to mechanical stress. This effect can be additionally enhanced by the removal of process dependent material such that the strength of the sputtered material is reduced during coating. Consequently, the target becomes more likely to deform and/or break. Applying a backsheet with increased strength or ductility can avoid this failure scenario.

Joining or bonding two dissimilar materials poses a technical challenge, such as borides, boride-dominated ceramics, doped borides or doped boride-dominated ceramics, In particular, TiB ₂ is used to connect or bond the metal copper or metal copper alloy of the second backplane. In particular the wetting and/or bonding properties of copper or copper alloys on ceramic materials such as borides, boride-dominated ceramics, doped borides or doped boride-dominated ceramics, especially The connection of TiB ₂ to copper should ensure the above characteristics over the largest area and should have the lowest degree of unconnected areas (defects).

The bonding of ceramic targets, such as tungsten carbide targets, to metal backplates is known. One way to provide a tungsten carbide target (WC target) with a back plate is to back cast it with copper or copper alloy, please refer to the "Research Disclosure (Research Disclosure)" publication in May 2014 ("WC-Cu Arc Cathode or Sputtering Target", Research Disclosure Database Number 601040, May 2014, ISSN 0374-4353). This publication describes the wetting behavior of eg copper or copper alloys on tungsten carbide (WC). Wetting agents such as boron or nickel can be used here and applied as a thin film to the ceramic part by electroplating methods, by slurry methods or by physical vapor deposition methods, etc., so that copper or copper alloys to it Adds wetting properties prior to backside casting. This method is not suitable for borides due to poor wettability and/or insufficient bonding of copper or copper-based alloys. In Passerone et al.'s publication "Wetting of Group IV diborides by liquid metals (Wetting of Group IV diborides by liquid metals)" (2006, "J Mater Sci" Vol. 41, No. 16, No. 5088 to No. Wettability is described in detail in page 5098).

One way to avoid the wetting problem is to dope the copper melt with boron, see for example the publication " _{The Nature of TiB 2 Wetting} by Cu and Au" by Aizenshtein et al. ) (May 2012, "Materials Engineering and Performance", Volume 21, Issue 5, pages 655 to 659)" described in detail. WO 2012063524 describes the bonding of multiple target components to a copper backplane by means of low melting point solder.

A disadvantage of doping copper melts with boron is that the properties of pure copper change with increasing doping. Furthermore, it is disadvantageous to use low-melting-point solder because it has low heat resistance.

The problem addressed by the present invention is to propose an improved composite body and an improved method of producing such a composite body. Another problem addressed by the present invention is to ensure that copper or copper alloys and borides, boride-dominated ceramics, doped borides or doped boride-dominated ceramics, especially TiB ₂ , reliable, reproducible and heat-resistant connections.

These problems are solved by the following: according to claim 1, borides, boride-based ceramics, boride-doped or boride-doped first parts are provided, made of copper or copper alloys A second part is formed, and a transition region between the first part and the second part, wherein the transition region comprises titanium and copper, and the transition region has a melting temperature > 600°C; and providing the invention according to claim 9 The manufacturing method of the characteristic complex. Advantageous embodiments of the invention are described in detail in the appended clauses.

The invention described here solves the wettability problem by applying individual or Alternating titanium, copper or titanium-copper layers are applied to a substrate consisting of a body of borides, boride-dominated ceramics, doped borides or doped boride-dominated ceramics, in particular TiB ₂ . These individual or alternating layers of titanium or copper or A titanium-copper layer is applied to the surface of the boride host (boride, boride-dominated ceramic, doped boride or doped boride-dominated ceramic, or TiB2 ₎ . In addition, the present invention describes the first part (boride, boride-dominant ceramic, doped boride or doped boride-dominant ceramic, or TiB2) temperature resistant bonded to the _second region ( copper or copper alloy), wherein the transition region has a melting temperature of at least 600°C, preferably at least 700°C, and more preferably at least 800°C.

The present invention describes the reproducible and reliable wettability of borides, boride-based ceramics, boride-doped or boride- _doped ceramics, in particular TiB2, with liquid copper or copper alloys . An advantage of the present invention over the prior art is that it can be implemented in fabrication without altering borides, boride-dominated ceramics, doped borides or doped boride-dominated ceramics, Or properties such as _TiB2 . Another advantage of the present invention over the prior art is that there is no need to change the composition of the copper or copper alloy used for backside casting, eg, no addition of boron to the alloy to increase wettability.

A: The first part of TiB ₂

B: transition area / transition area

C: The second part made of copper

Other advantages of the invention will become apparent from the following description of working embodiments with reference to the accompanying drawings.

Figure 1: Scanning electron micrograph of the transition region between TiB2 and copper of sample No. ₁ (please refer to Table 1 and Table 2).

Figure 2: Surface image of sample No. 1 (please refer to Table 1 and Table 2), which has been provided with an intermediate layer before backside casting with copper.

Figure 3: Scanning electron micrograph of the transition region between TiB ₂ and copper of sample No. 2 (please refer to Table 1 and Table 2).

Figure 4: DIN microhardness measurements in the transition zone of the composite of sample No. 1 (please refer to Table 1 and Table 2).

Figure 5: DIN microhardness measurements performed in the backside cast copper part of the composite of sample No. 1 (please refer to Table 1 and Table 2).

According to the invention, the composite body has a first part, a second part and a transition region. A transition region is between a surface or surface region of a first part and a surface or surface region of a second part. The first part consists of borides, boride-dominated ceramics, doped borides or doped boride-dominated ceramics. More specifically, the first part consists of TiB2, TiB2 _- dominated ceramics, _doped TiB2 or TiB2 _{- doped} ceramics.

Borides are understood to mean compounds of a metal or metals with boron. Furthermore, borides are to be understood in particular as meaning those borides which have the structure MeB ₂ or Me ₂ B ₅ in crystallography. In this context, special mention should be made of hard and highest melting types with good electrical conductivity, such as titanium boride (TiB ₂ ). In terms of structure, the titanium boride system is formed of alternating layers of closely packed metal atoms and hexagonal boron networks, which lead to the aforementioned good electrical conductivity. Examples of boron compounds include in particular TiB ₂ , VB ₂ , CrB ₂ , ZrB ₂ , NbB ₂ , MoB ₂ , HfB ₂ , TaB ₂ , UB ₂ , AlB ₂ , ReB ₂ , MgB ₂ and WB ₂ or W ₂ B ₅ . Mixed boron nitride is to be understood in particular as meaning a mixture of at least two borides described above. Doped boride or mixed boride ceramics may contain additional elements or compounds, but the total proportion of additional elements must not exceed 20 mol %, in particular not exceed 10 mol %. Additional elements added to boride or mixed boride ceramics can be pure metals such as Fe, Ni, Co, Cr, Ti, Mo, Zr, etc., or carbides such as TiC, WC, NbC, but can also be Such as pure elements such as C, B or Si. Here, boron-doped TiB ₂ or silicon-doped TiB ₂ should be mentioned in particular.

The first part of the composite mainly consists of a non-textured microstructure, wherein the non-textured microstructure has no preferred grain alignment and has an average grain size of <20 μm, preferably <10 μm, more preferably <5 μm. The second part of the composite consists essentially of pure copper or a copper alloy and exhibits an average grain size of >0.5 μm, preferably >1 μm, more preferably >1.5 μm. Copper alloys are understood to mean alloys with copper in which copper is the main constituent and the total proportion of alloying elements is <50% by weight, preferably <30% by weight, and more preferably <20% by weight. Examples of copper alloys include CuZn, CuZnSi, CuMg, CuAl, CuBe, CuCrZr, and CuZn. The transition region contains titanium and copper. According to the invention, the transition zone has a melting temperature (or softening temperature) >600°C, preferably >700°C, and better >800°C. The transition region is free of low-melting phases, and "low-melting" in this document refers to those temperature ranges that are within the order of the melting points of indium or tin.

Thus, the compound has a significantly improved heat resistance compared to the prior art. This is of particular interest because higher power densities and/or sputtering rates can be achieved in coating systems.

With regard to the melting temperature of the alloy, reference is made to the liquidus line of the corresponding alloy, where in the case of copper alloys, below 600°C, preferably below 700°C, and more preferably below 800°C, no liquid phase. The thermal stability of the complex can be demonstrated by passing it through a kiln at 600°C or 700°C or 800°C, in which no liquid phase will form at all, which will inevitably lead to a gap between the first part and the second part. joint loss (or softening of the transition zone) or composite shape change. In order to test the thermal stability of the composite body, especially the thermal stability of the transition zone, the composite body will be loaded into a kiln so that a part of the composite body and at least the entire transition zone are free-standing. Means that a part and at least the entire transition area is not clamped or fixed. In addition, the complex is aligned in the kiln so that the plane of the transition zone, or in other words, the transition zone between the first part and the second part is aligned parallel to gravity, so that in the case of softening of the transition zone or formation of a liquid phase in the transition zone, by One part may be detached from or moved relative to a second part by the force of gravity. Subsequently, the furnace is heated up. After the core of the composite has reached the desired temperature of 600°C, preferably 700°C, and more preferably 800°C, and after a hold time of 1 hour, the kiln is cooled again. If the melting or softening temperature of the transition zone should be lower than the set temperature of the kiln, the freestanding, unclamped or unsecured parts will be separated by gravity from the clamped parts of the composite or relative to the composite The clamped part moves.

The transition region is a diffusion region arising from the boride, boride-dominant ceramic, doped boride or doped boride-dominant ceramic, in particular TiB ₂ , in the first part, and from copper or Transition zone between solidified or solidified back casting melt (second part) composed of copper alloy. Furthermore, the transition region may be a region arising from a boride, boride-dominated ceramic, doped boride or doped boride _- dominated ceramic, in particular TiB2, between the first part, and The transition area between the second parts is applied by cold gas spraying.

In an advantageous embodiment, the transition region of the composite is substantially free of typical solder components such as indium, tin, germanium, silver, palladium, nickel, platinum, cobalt, manganese or gold. In each case, the transition region has a content of <5,000 ppm indium, tin, germanium, silver, palladium, nickel, platinum, cobalt, manganese or gold, preferably <2,000 ppm in each case, more preferably Best has a content of <1,000 ppm in each case.

In an advantageous embodiment, the first part of the composite body is composed of TiB2, a TiB2 _- based ceramic with at least ₂₀ mol% TiB2, preferably a _{TiB2 -} based ceramic with at least 30 mol _% TiB2, And more preferably it consists of a TiB ₂ -based ceramic having at least 50 mol% TiB ₂ . We have found that the invention is particularly suitable for application to arc _cathodes made of the material TiB2. Due to the bonding between TiB ₂ and the copper backplane, it is thermally stable, adhesive and has good electrical conductivity, so arc cathodes with a diameter of 63 mm and a height of 32 mm can be operated for several hours in the light arc process, without compromising the stability of the cathode.

In an advantageous embodiment, the first part of the composite consists of carbon- _doped TiB2. Carbon- _doped TiB2 is understood as adding up to ₁₀ mol% carbon to TiB2, preferably at least ₅ mol% carbon to TiB2, and more preferably up to ₂ mol% carbon to TiB2. Published specification _{WO2011137472A1} discloses the advantages resulting from the doping of TiB2 ceramics with graphite.

In another advantageous embodiment of the invention, the transition region has an average thickness between 5 μm and 500 μm, preferably between 8 μm and 300 μm, more preferably between 10 μm and 200 μm. The thickness of the layer in the transition region is measured by scanning electron microscopy or by optical microscopy. This is done by placing the metallographically polished section at right angles to the plane of the transition region, and then measuring the thickness of the layer by scanning electron microscopy or by optical microscopy at appropriate magnification. Measuring the thickness of the layer in the transition zone should be done at a representative location of the section. In this case, at least 10 representative locations should be inspected, and an average value of the thickness of the layer representing the average of the transition region should be established.

In another advantageous embodiment of the invention, the concentration of copper in the transition region and the concentration of titanium in the transition region each have a graduated concentration profile from the surface of the first part all the way to the surface of the second part ). Concentration of copper at the surface of the second part consisting of copper or copper alloys to the first part consisting of borides, boride-dominated ceramics, doped borides, or doped boride-dominated ceramics surface reduction. The concentration of titanium increases from the surface of the first part consisting of borides, boride-based ceramics, doped borides, or doped boride-dominated ceramics to the second part consisting of copper or copper alloys. surface reduction. In each case, the change in concentration may be continuous or abrupt. Under a scanning electron microscope or an optical microscope, the transition region is clearly defined. The progressive concentration profile of titanium and copper can be measured by scanning electron microscopy and by energy dispersive analysis (EDX).

In another advantageous embodiment of the invention, the average hardness in the transition zone At least 10% higher, preferably at least 20% higher than the average hardness of the second portion consisting of copper or copper alloy. Hardness is the mechanical resistance, which is the resistance offered by a body to the penetration of another, harder body. This involves pressing standardized samples into the workpiece surface in fixed conditions. Preferably a microhardness test according to Vickers is used, but a microhardness test according to Rockwell or Brinell may also be used. The microhardness is preferably measured according to DIN EN ISO 6507. For representative hardness measurements, in each case at least 10 measurements should be made at a representative location under identical conditions, and these measurements should be used to form an average value representing the average hardness value.

In another advantageous embodiment, at least 50%, preferably at least 70%, more preferably at least 90% of the transition zone exhibits a metallurgical bond to the surface of the first portion and a metallurgical bond to the surface of the second portion. This junction and its percentages can be checked first by non-destructive testing by inspecting the composite by means of ultrasound or X-rays; secondly by making laterally polished sections by means of optical microscopy or scanning electron microscopy and following transition areas analyze. With the help of ultrasonic testing, we can see voids and unconnected areas between borides, boride-based ceramics, doped borides, _doped boride-based ceramics, especially TiB2. Ultrasonic testing can be performed from the surface of the copper or copper alloy towards the ceramic (boride, boride-dominated ceramic, doped boride, doped boride-dominated ceramic, or TiB ₂ ), or from the surface of the ceramic Proceed towards copper or copper alloys. Ultrasonic testing gives spatially resolved images in which unconnected regions and ceramics (borides, boride-dominated ceramics, doped borides, doped Other defects at the transition of boride-dominated ceramics, or TiB2 ₎ to copper or copper alloys. For those skilled in the art, the connected and unconnected regions in the image are clear and definite. The area of the unconnected area is determined by summing all unconnected individual areas present in the measurement area. According to the invention, the ratio of the sum of all unconnected areas to the measured area is always <0.5, preferably <0.3, and more preferably <0.1. This means that the connection in terms of area of ceramic (boride, boride-dominated ceramic, doped boride, doped boride-dominated ceramic, or TiB ₂ ) to copper or copper alloy is always Higher than 50%, preferably higher than 70%, more preferably higher than 90%.

With the help of X-ray testing, it is possible to see something between ceramics (borides, boride-dominated ceramics, doped borides, doped boride-dominated ceramics, or TiB ₂ ) and copper or copper alloys holes and unconnected areas between them. X-ray testing can be performed from the surface of the copper or copper alloy towards the ceramic, or from the surface of the ceramic towards the copper or copper alloy. The X-ray test gives a spatially resolved image in which unconnected areas and ceramics (borides, boride-based ceramics, doped borides, doped boride-dominated ceramics) can be seen in two dimensions. Other defects at the transition of ceramic, or TiB2 ₎ to copper or copper alloys. For those skilled in the art, the connected and unconnected regions in the image are clear and definite. The area of the unconnected area is determined by summing all unconnected individual areas present in the measurement area. According to the invention, the ratio of the sum of all unconnected areas to the measured area is always <0.5, preferably <0.3, and more preferably <0.1. This means that the connection in terms of area of ceramic (boride, boride-dominated ceramic, doped boride, doped boride-dominated ceramic, or TiB2 ₎ to copper or copper alloy is always Higher than 50%, preferably higher than 70%, more preferably higher than 90%.

In another advantageous embodiment, in case a tensile stress occurs between the first part and the second part and the direction of the load is perpendicular to the surface where the first part and the second part are joined by the transition zone, the fracture stress is At least 15MPa, preferably >20MPa, more preferably >30MPa, wherein the fracture stress is based on the connecting part of the transition zone. With the aid of tensile tests, for example, according to DIN EN ISO 6892-1:2009 1:2009-12, we can determine the ceramics (borides, boride-dominated ceramics, boride-doped, boride-doped The fracture stress of the main ceramic, or TiB ₂ ) bonded to copper or copper alloy. This test is performed by clamping the composite in a tensile testing machine so that the direction of tension or stress is perpendicular to the copper or copper alloy and ceramic (boride, boride-based ceramic, boride-doped , boride-doped ceramics, or TiB ₂ ), wherein the surfaces are joined by a transition region. Subsequently, the component is subjected to stress until it breaks. The measurement of tensile stress is based on the connected area, ie the pure fracture area. To the person skilled in the art, the region of break (connection region) is clearly defined. The bodies produced according to the invention show, based on the fracture area, a tensile strength of >15 MPa, preferably >20 MPa, more preferably >30 MPa.

The invention also relates to a method for producing a composite system consisting of a first part, a second part and at least one transition zone formed between the surface or surface region of the first part and the second part. Surfaces or between surface regions, characterized by the following steps: - manufacturing the first part by powder metallurgy from borides, boride-dominated ceramics, doped borides or doped boride-dominated ceramics, - Coating at least one surface section of the first part with at least one intermediate layer comprising titanium or titanium and copper, by backcasting the surface of the first part which has been coated with the intermediate layer of copper or copper alloy (back casting), or by cold gas spraying (CGS) the surface of the first part of the intermediate layer which has been coated with copper or copper alloy, to make the second part of the composite body, - thereby forming A transition region between the first portion and the second portion.

The method according to the invention for producing a composite body achieves the advantages explained above in relation to the components according to the invention reliably and in a reliable method. Furthermore, the previously described advantageous embodiments of the invention are also advantageous for the method of the invention.

It is particularly preferred that the first part is produced by powder metallurgy and the second part is produced by back casting, and that, prior to back casting, the surface of the first part or part of the surface of the first part has at least one layer of titanium or titanium and copper middle layer.

Positive effects achieved in this way include the following: - good wettability of copper or copper alloys on the first part with at least one intermediate layer, - thermal stability of the composite material resulting and formation of melting points higher than 600°C the transition area.

Backside casting is understood to mean the powder metallurgical application of material onto a base material, wherein the base material is always in a solid state of matter and using the stated process parameters. Before back casting, the first part is applied in at least one surface section with at least one intermediate layer, wherein the at least one intermediate layer contains titanium or titanium and copper. In backside casting, for example, a bulk substrate material consisting of borides, mixed boride ceramics, doped borides or doped mixed boride ceramics in solid form (usually coated with at least An intermediate layer) is introduced into the kiln space. Subsequently, a second material consisting of copper or a copper alloy is applied to the base material. Thereafter, the composite, initially in loose form and not yet adhesively joined, is heated in a suitable process atmosphere, possibly using a ramp function, until the applied material consisting of copper or copper alloy melts and wets the molten base material. For example, pure copper has a melting point of 1085°C. One should choose the temperature of the furnace so that it is above the liquidus of the alloy composition in the phase diagram. When performing backside casting, one should keep the temperature of the kiln above liquidus long enough so that a fully molten applied copper or copper alloy can form. A transition region is formed between the first portion and the second portion. The transition region is formed as a result of the dissolution of the titanium or titanium/copper layer in the copper or copper alloy applied by back casting. After a desired hold time above the melting point, the furnace is cooled down to below the melting point of the copper or copper alloy. After solidification of the copper or copper alloy, the cooled composite has a first part consisting of a boride, a boride-based ceramic, a doped boride or a doped boride-dominated ceramic, and a copper or copper The alloy comprises a second portion, and a transition region between the first portion and the second portion comprising titanium and copper, and the transition region has a melting or softening temperature >600°C. Alternatively, we can turn (turning), cutting (machining), cutting (cutting), grinding (grinding), lapping (lapping), pressing (pressing), embossing (embossing) or rolling (rolling) To machine or rework the cured composite. Thereafter, welding, soldering, joining or bonding processes may also be performed on the composite body. Furthermore, one can subsequently engraving, etching or etching the composite (eroding). In addition to mechanical processing of the composite body, the composite body can also be thermally post-treated, such as annealed, oxidized or reduced, in order to obtain the desired microstructural properties.

Preferably, the first part is manufactured by powder metallurgy, the second part is applied by cold gas spraying (CGS), and the surface of the first part or part of the surface of the first part has at least one Titanium or an intermediate layer of titanium and copper.

Cold gas spraying is a coating process in which powder particles with very high kinetic energy and low thermal energy are applied to a substrate material. A process gas (eg, air, helium, nitrogen, and mixtures thereof) at high pressure is expanded by a convergent-divergent nozzle (also known as a supersonic nozzle). A typical nozzle form is the Laval nozzle. Depending on the process gas used, gas velocities of, for example, 300 m/s to 1200 m/s for nitrogen up to 2500 m/s for helium can be achieved. For example, the coating material is injected into the gas stream upstream of the narrowest cross-section of the waisted nozzle forming part of the spray gun, is typically accelerated to a velocity of 300 m/s to 1200 m/s, and deposited on the base on the material. Heating the gas upstream of the waisted nozzle increases the velocity of the gas as it expands in the nozzle, and thus increases the velocity of the particles. Typically, in the case of cold gas spraying, gas temperatures ranging from room temperature to 1000° C. are employed. With cold gas spraying, we can spray ductile materials, especially ductile materials with face-centered cubic and hexagonal close-packed lattices, to form dense, well-adhered layers. Typically, cold gas spraying is used to apply metal layers to metal substrates; currently, applying metal layers to ceramic substrates is not a well-established process. In the case of cold gas spraying, the layer formation is done layer by layer from individual particles of coating material. Key factors for the quality of cold gas sprayed coatings are the adhesion of the coating material to the substrate and the cohesion between the particles of the coating material. In principle, the cohesion both in the region of the coating material/substrate interface and between the particles of the coating material is the interplay of several physical and chemical bonding mechanisms and is not yet understood. Due to the low process temperature, the powder in the cold gas spray coating does not melt, but hits the substrate to be coated in an unfused state, which leads to the formation of the layer. Depend on Due to the high kinetic energy and due to the high speed at which the powder moves in the gas stream, the powder is mechanically interlocked when it hits the substrate surface, and the interlock is assisted by the process temperature. The layer produced in this way by cold gas spraying the coating is apparent under the microscope because it is a layer composed of individual powder particles. The powder particles in the layer applied by cold gas spraying do not show any molten phase and the layer is also clearly defined in the deposited layer. Due to the high kinetic impact energy, the powder particles undergo deformation and exhibit an aspect ratio >1. The crystallographic orientation of the individual grains of the applied cold gas sprayed coating shows a statistical distribution and no preferential orientation.

According to an advantageous manufacturing method of the invention, it is provided that the step of manufacturing the first part by powder metallurgy is done by using TiB ₂ or carbon-doped TiB ₂ or TiB ₂ -dominated ceramics with >20 mol% TiB ₂ , Among them, TiB ₂ -based ceramics with >30 mol% TiB ₂ are preferably used, and TiB ₂ -based ceramics with >50 mol% TiB ₂ are more preferably used. Carbon-doped TiB ₂ is understood to mean an addition of up to 10 mol % TiB ₂ to TiB ₂ , preferably at least 5 mol % TiB ₂ to TiB ₂ , and more preferably at least 2 mol % TiB _{2 to TiB 2 .}

According to an advantageous manufacturing method of the invention, it is provided that at least one intermediate layer is applied to the boride first part (boride, boride-dominated ceramic, doped boride, doped boride-dominated ceramic, or TiB ₂ ), the above is preferably by cold gas spraying (CGS) or by low pressure plasma spraying or by vacuum plasma spraying. Cold Gas Spray (CGS) is a coating process in which powder particles are applied to a carrier material with very high kinetic energy and low thermal energy. In the case of plasma spraying, the powder particles are melted in the air stream and hit the substrate to be coated in a molten state. Although the layer morphology in plasma sprayed coatings shows the deposition of molten particles and is clearly different from layers produced by cold gas spraying, the powder particles of plasma sprayed coatings likewise have an aspect ratio.

According to an advantageous manufacturing method of the invention, it is provided that at least one intermediate layer is applied to the first part (which is composed of boride, boride-based ceramics, doped borides, ceramics dominated by _doped borides, or TiB2). Physical vapor deposition and chemical vapor deposition layers generally show columnar layer growth and columnar stem structures and are distinct from layers deposited by cold gas spraying or by plasma spraying. Physical vapor deposited layers, as well as chemical vapor deposited layers, usually show texture in the direction of coating.

According to an advantageous production method of the invention, it is provided that the intermediate layer is applied in a plurality of layers, wherein the individual layers of the plurality of layers can have different compositions. Individual layers of the plurality of layers may consist of substantially pure titanium, substantially pure copper or a mixture of titanium and copper, or a titanium-copper alloy.

An advantageous production method according to the invention provides for applying an intermediate layer or at least one intermediate layer having an average layer thickness of at least 10 μm, wherein the thickness of the layer is preferably at least 15 μm. The layer thickness of the interlayer was determined by scanning electron microscopy. This involves placing the metallographically polished section at right angles to the plane of the intermediate layer, and then measuring the thickness of the layer by means of a scanning electron microscope or at an appropriate magnification. Layer thickness measurements shall be made at representative locations of the section. Here, the thickness of the layer at least 10 different representative locations should be examined, and an average should be established giving the average thickness value of the intermediate layer.

According to an advantageous production method of the invention, an intermediate layer of substantially pure titanium is provided, or in the case of a multi-layer structure of an intermediate layer, a layer of an intermediate layer consisting of substantially pure titanium is applied, the The thickness is not more than 100μm.

According to an advantageous production method of the invention, an intermediate layer of titanium-copper is provided, or in the case of a multilayer structure of the intermediate layer, an intermediate layer consisting of substantially pure copper is applied, or an intermediate layer composed of substantially copper and titanium is applied. Composed of intermediate layers, the thickness of these layers is not greater than 500μm. Due to the ductility of copper, one can apply thicker layers of substantially pure copper or copper-titanium than layers of substantially pure titanium without delamination of the applied layer.

A further method according to the invention for producing a composite body achieves the advantages stated above with respect to the composition according to the invention reliably and in a reliable method. Furthermore, the previously described advantageous embodiments of the invention are also advantageous for the method of the invention.

Example:

For the present examples, _two cylindrical TiB2 blanks were fabricated by spark plasma sintering and then machined to a diameter of 57 mm and a height of 12 mm. Before backside casting, a first titanium intermediate layer was applied in each case to the surface of the TiB ₂ blank by cold gas spraying. The following cold gas spray process parameters are used for the first intermediate layer (see Table 1):

After applying the first titanium intermediate layer by cold gas spraying, a second copper intermediate layer is applied by cold gas spraying. The following cold gas spray process parameters were used to apply the second intermediate layer (see Table 2):

_The TiB2 billet provided with the first intermediate layer of titanium and the second intermediate layer of copper was then back casted by means of copper as described below. The first part, coated with the cold gas spray, was placed on the base of the graphite cylinder with the coated side facing up. The diameter of the graphite cylinder is > the diameter of the coated TiB _billet and also has a higher height. The copper portion of substantially pure copper (referred to as "pig") is placed on the transparent space above the TiB2 _billet .

Subsequently, the graphite cylinder was introduced into the kiln and heated to 900°C in a hydrogen atmosphere. After reaching 900°C, the graphite cylinder was further heated in a nitrogen atmosphere to a temperature of 1150°C (note: above the melting temperature of copper, which is 1085°C). After reaching 1150°C, this temperature was maintained for 20 minutes. Subsequently, the graphite cylinder was moved out of the hot zone of the kiln at a speed of 1 cm/min. Cooling of the TiB2 _- copper composite is accomplished by directional solidification of the melt, which results in a stress-free but coarsely crystalline microstructure of the backside cast copper. After cooling, the TiB ₂ billet back-cast with copper in this way shows a fairly good connection between the two materials (TiB ₂ and copper) above the transition region formed. Composite bodies produced in this way do not show any cracks or delaminations in the transition zone. The slow nature of the cooling also minimizes thermal stress between the TiB2 _billet and the solidified copper backplate.

Figure ₁ shows the TiB2/copper transition region in a scanning electron microscope of a laterally polished section (Sample No. 1, see Table 1). In Figure ₁ , we can identify the first part (A, dark area) of TiB2, which is located on the left side of the diagram; and the second part (C, light area) consisting of copper, which is located in the diagram right side of the formula. The connection of the first part to the second part shall be completed over the complete area of the transition zone and shall be free from visible cracks or defects. The transition region (B) extends approximately in the form of a semicircle from the surface of the TiB ₂ towards the copper and exhibits an average thickness of about 15 μm. Accurate measurement of the layer thickness in the transition region was difficult in this sample because, due to the layer formation in the cold gas spray process and the low layer thickness (compared to the powder size), the TiB2 _billet surface There is incomplete coverage with the middle layer. The surface of the TiB ₂ billet after application of the second copper interlayer by cold gas spraying is shown in FIG. 2 . The surface area coverage of the intermediate layer applied by cold gas spraying is about 50%. Even after backside casting, the coverage of the original stock surface is still evident in the transverse polished sections and is clearly visible in FIG. 1 . Although the original coverage of about 50% is rather low, the TiB2 _- copper bond produced by backside casting in this way shows a complete connection between copper and _TiB2 with no cracks or cracks in the transition region. defect.

Figure 3 shows the TiB2/copper transition region in a scanning electron micrograph of a laterally polished section (Sample No. ₂ , see Table 1). In Fig. ₃ , the first part of TiB2 (A, dark) on the left side of the diagram is evident, and the second part (C, bright) on the right side of the diagram is composed of copper. The connection of the first part to the second part is done over the complete area of the transition area. The transition region (B) extends from the surface of TiB ₂ towards copper and exhibits an average thickness of about 200 μm. Since the applied intermediate layer was significantly thicker in the case of sample No. 2 compared to the applied intermediate layer in sample No. 1 (Fig. 1 and Fig. 2), the surface of the TiB ₂ was completely coated with the intermediate layer Yes, this is also clear in the cross-section shown in Figure 3.

Figure 4 shows the microhardness measurement of the transition zone (B) of sample No. 1 according to DIN EN ISO 6507, and Fig. 5 shows the microhardness in the backside cast copper second part of sample No. 1 consisting of copper (C). Microhardness measurement. The back cast second part showed a microhardness of 83 HV0.1 on average and the transition zone showed a microhardness of 159 HV0.1 on average. This means that the average hardness of the transition region of sample No. 1 is more than 90% higher than the average hardness of the second portion consisting of substantially pure copper.

A‧‧‧TiB ₂ part one

B‧‧‧Transition Area/Transition Area

C‧‧‧The second part composed of copper

Claims (16)

A composite comprising a first part and a second part between a surface or surface region of the first part and a surface or surface region of the second part and materially joining the first part to the second part wherein- the first part consists of a boride, mixed boride ceramic, doped boride or doped mixed boride ceramic,- the second part consists of copper or a copper alloy, and- the The transition region contains titanium and copper and has a melting temperature >600°C. Composite as claimed in claim 1, wherein the transition region exhibits, in each case, a content of the elements indium, tin, germanium, silver, palladium, nickel, platinum, cobalt, manganese or gold of <5,000 ppm . The composite body as described in claim 1, wherein the first part is composed of TiB ₂ , TiB ₂ -based ceramics with at least 50 mol% TiB ₂ , or carbon-doped TiB ₂ . The composite body as described in claim 1, wherein the thickness of the transition region is between 5 μm and 500 μm. The composite body as described in claim 1, wherein the concentration of copper in the transition region and the concentration of titanium in the transition region are from the surface of the first part towards the surface of the second part, Both showed graduated concentration curves. The composite body according to claim 1, wherein the average hardness in the transition region is at least 10% higher than the average hardness in the second portion. The composite body of claim 1, wherein at least 50% of the transition region exhibits a metallurgical bond to the surface of the first portion and to the surface of the second portion. The composite body as described in item 1 of the scope of the patent application, wherein there is a tensile stress between the first part and the second part, and the stress direction is perpendicular to the first part connected by the transition region In the case of dividing the surface and the surface of the second portion, the fracture stress is at least 15 MPa, wherein the fracture stress is based on the connecting portion of the transition region. A method of manufacturing a composite body consisting of a first part, a second part and at least one transition region formed between a surface or surface region of the first part and a surface or surface region of the second part between, characterized by the following steps: - manufacturing the first part by powder metallurgy from borides, boride-based ceramics, doped borides or doped boride-based ceramics, - comprising titanium in at least one layer or an intermediate layer of titanium and copper to coat at least one surface section of the first part, - by back casting (back casting) to the surface of the first part which has been coated with the intermediate layer of copper or copper alloy, or by cold gas spraying (CGS) the surface of the first part of the intermediate layer which has been coated with copper or copper alloy, to make the second part of the composite, - thereby forming the intervening and the transition region between this second part. The method of claim ₉ , wherein the first part is made of TiB2, carbon _{- doped} TiB2, or a TiB2 _- based ceramic having at least 50 mol% TiB2. The method of claim 9, wherein the intermediate layer is applied by cold gas spraying (CGS) or low pressure plasma spraying. The method of claim 9, wherein the intermediate layer is applied by PVD or CVD or slurry coating. The method according to claim 9, wherein the intermediate layer is applied in a plurality of layers, and the individual layers of the plurality of intermediate layers may have different compositions. The method according to any one of claims 9 to 13, wherein the intermediate layer or one of the intermediate layers is coated with a layer thickness of at least 10 μm. The method according to claim 9, wherein an intermediate layer of substantially pure titanium, or in the case of a multi-layer structure of the intermediate layer, one of the intermediate layers consisting of substantially pure titanium is applied , wherein the thickness of the layer is not greater than 100 μm. A method as described in claim 9, wherein the titanium-copper interlayer, or in the case of a multi-layer structure, one of the interlayers consisting of substantially pure copper or One of the intermediate layers is composed of copper or titanium, wherein the thickness of the layer is not greater than 500 μm.

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