DE102021200421A1 - Spray unit and method for spraying a solid-derived material - Google Patents

Abstract

The invention describes a spray unit for spraying a material obtained from a solid onto a material surface, in particular a heat-sensitive material surface, by means of a spraying process under atmospheric pressure. In this case, the spray unit has a process gas supply device which is set up to heat a gas guide body in order to provide a process gas flow of at least 1500°C. The spray unit also has a material separating device, which is set up to convert the solid body into a gaseous phase under this atmospheric pressure by heating a material separating body of the material separating device and to feed it to the process gas stream in this phase.

Description

The invention relates to a spray unit and a method for spraying, in particular for thermally spraying, a material obtained from a solid onto heat-sensitive material surfaces.

The document DE 10 2014 103025 A1 deals with a method of thermally coating a heat-sensitive substrate under atmospheric pressure. In this case, the coating should take place by separating particles from a gaseous phase, which is referred to there as a heat transfer medium. In order to obtain the particulate gas that can be separated, the document proposes inductive heating of the heat transfer medium and refers to different technologies. Mentioned are, for example, the electrospray process for dimensioning the droplet size, or the plasma spray process for spraying on the heat carrier. To protect the substrate, the document describes a sol-gel pretreatment of the substrate surface. For this purpose, the device disclosed there uses a flow barrier with an opening which is arranged between the substrate and the outflowing heat transfer medium, a plasma jet also acting in the intermediate space formed by the flow barrier and substrate.

the EP 197 8038 A1 discloses a device and a method which is based on the use of an aerosol generator in combination with a capacitively generated, non-thermal plasma and which is operated under atmospheric pressure. The aerosol generator converts the material to be coated from an initially liquid phase into an aerosol. The aerosol is then fed to the non-thermal plasma for deposition on a surface ( 1 ). UV exposure of the applied layer is proposed to improve the adhesion properties.

Other known methods of gas phase deposition are, for example, the AP-CVD method (Atmospheric Pressure - Chemical Vapor Deposition), which is suitable for the deposition of atomic layers. The AP-CVD process is complex in terms of equipment and requires a high degree of process control. The atoms to be coated must be generated from the gas phase by chemical reactions. The layers produced are expensive due to the time-consuming deposition process.

Alternatives to the deposition of thicker layers are spray or atomization processes, as well as thermal, in particular plasma spray processes.

Forming a coating using plasma spray technology involves melting individual particles while accelerating the particles at high velocity onto the substrate. The particles are typically injected into the plasma as a powder and then thermally decomposed in the plasma. The desired coating is achieved by continuously flattening and solidifying the particles. The usually inductively coupled plasma torches (ICP torches) usually generate plasmas with high gas temperatures, high enthalpy and large plasma volumes. Typically, diatomic gases are used in an IPC torch to produce a plasma with high energy content and good thermal conductivity. The use of conventional ICP burners is therefore only suitable to a limited extent for coating thermally sensitive substrates due to the associated high gas temperature.

The object of the invention is to provide a compact spray unit for coating a substrate with the material of a solid, with the heat transfer to the substrate being reduced. The invention solves this problem by a spray unit according to claim 1 and a method according to claim 15. Preferred configurations are the subject matter of the dependent claims, the description and the figures.

According to the invention there is provided a spray unit as follows.
Spraying unit for spraying a material obtained from a solid onto an, in particular heat-sensitive, material surface by means of a spraying process under atmospheric pressure
a process gas supply device, set up to heat a first gas guide body in order to provide a process gas flow of at least 1500°C, and the process gas flow is heated to 1500°C,
a material separating device, set up to convert the solid body into a gaseous phase under this atmospheric pressure by heating a material separating body of the material separating device and to supply it to the process gas stream in this phase,
a flow guide set up to guide a process gas enriched with this phase in the direction of the material surface to be sprayed.

A spray unit is to be understood in particular as a spray head which is easy to operate and can be guided over a surface to be coated by a user, in particular manually, i.e. manually by the user. However, the spray head can also be held and/or guided mechanically.

The material to be coated is to be understood as a solid in its solid form, which also includes a large number of solid bodies, for example solid bodies in powder form.

The solid body can be partially or completely present in the spray head, i.e. it can be stored in order to be available for a spraying process. The spray unit does not necessarily include the solid. The solid can be fed into the spraying unit from outside, in particular continuously during a spraying process, or loaded into the spraying unit in the form of a cartridge, for example, before a spraying process. The solid body can be removed interchangeably in the spray unit. A spray system can refer to the spray unit, as well as to the combination of the spray unit or the spray head and a material feed unit arranged separately from this. A material feed unit feeds the material to be coated to the spray unit so that material for coating the surface is present in the spray unit. This can be in the form of a liquid or a solid or a combination thereof.

The spray unit also includes a housing which at least partially contains the process gas supply device and the material separation device. In this case, assemblies of the process gas supply device and/or the material separation device can be arranged outside the housing of the spray unit. The housing has holders so that the process gas supply device and the material separation device are fastened in the housing and/or on the housing. The spray unit also has connections to conduct a gas as a process gas into the spray unit, so that the process gas is available in the spray unit.

The spray system may include the spray unit, a material feed unit, a gas bottle, gas lines, and an electronic controller. The spray system can also have a holding device for fastening the spray unit above a surface to be coated. The holding device can be designed manually and/or mechanically, in particular as a robot arm.

The electronic controller of the spray system controls the spray unit. The electronic control device can also be used to control the holding device. The electronic control device controls at least one heater of the spray unit so that the process gas is heated. The electronic control unit controls the gas supply, e.g. in the form of gas quantity, gas velocity and gas pressure, into the spray unit, e.g. by means of a pneumatic valve control which can be part of the spray system.

The electronic control device includes an electrical circuit for controlling the heating of the process gas supply device and/or the material separation device of the spray unit. In particular, an electrical circuit for controlling a heater that operates in particular inductively, particularly preferably an induction coil. However, the electronic control device can also comprise an electrical circuit for controlling an optical heating, e.g. a laser and/or a capacitive heating.

The electronic control device includes a data processing device in order to be able to carry out automated processes such as heating the spray unit, operating the holding device or supplying gas. The electronic control device can also have a user interface for programming the spray system by a user, as well as a memory device for recording process parameters of the spray unit and/or the spray system.

In the present case, a solid is to be understood as meaning a material in its solid phase, which is in particular at room temperature and normal pressure. This can also mean a powder of a solid or a large number of individual solids, in particular also mixtures of powders and/or different solids. Solids (also solid) refers to matter (also material) in the solid state of aggregation. In the narrower sense, this also means a substance that has a solid state of aggregation at a temperature of 20 °C, the term solid in this case being substance-specific but not temperature-specific. In the technical language used, solids have a certain minimum expansion, which is not clearly defined here. They are therefore macroscopic bodies - in contrast to microscopic bodies. For example, as a rule, a macromolecule is not considered a solid on its own. Matter in the transition area should be referred to as a cluster. The term particle is also used here to represent the term cluster. In this case, the particles that are formed by heating the solid body and are present in a gaseous phase should be meant in particular. This also includes the clusters or particles formed by coagulation, nucleation and condensation, which are formed in or from the resulting gaseous phase of the solid after the solid has been heated. In the present case, the gaseous phase of the solid is therefore in particular the gaseous quantity of particles obtained by heating the solid, Atoms, molecules and macromolecules are meant. In the present case, the enriched process gas is to be understood as meaning the quantity of the first and second process gas streams and the in particular gaseous phase of the solid body.

The material to be coated is applied or sprayed onto the substrate surface with the spray head. The term substrate as used herein alternatively for the material to be coated. In this case, the material or the substrate has a material surface or substrate surface in each case. In fact, this surface of the substrate or material is coated. When talking about coating the substrate or the material, the respective surface is meant analogously. As a result of the spraying process or the application, a surface coating made of the material of the solid forms at least partially on the substrate, which is in particular heat-sensitive. The heat-sensitive substrate and/or the heat-sensitive surface of the substrate is at least not significantly damaged by the spraying process. For example, the heat-sensitive substrate may be in the form of organic surfaces or an entirely organic substrate and/or material such as wood. However, a wide variety of substrates, including non-heat-sensitive substrates, are conceivable. Examples are wood, metals, concrete, plastics, paints, stone, marble, textiles, ceramics or combinations thereof. Damage to the heat-sensitive substrate would be understood, for example, as a change in the mechanical, elastic or other properties that characterize the material in particular, in the sense of physical material parameters, which in particular require the use of the material for a typical purpose. The spraying unit does not significantly change the particularly characteristic properties of the substrate as a result of the spraying process. Not essential means that the material can continue to be used for its typical purpose, in particular with no restrictions and/or restrictions.

The invention also relates to a process gas supply device. A process gas supply device is to be understood as a device which heats the gas fed from the outside to the spray unit in the spray unit and feeds it at least in sections into the spray unit, i.e. feeds it through the spray unit. The gas flows into the spray unit via a gas connection at a proximal end of the latter and out of the spray unit at a distal end in the direction of the surface to be coated. For this purpose, the spray unit has a spray opening at the distal end and at least one gas connection, which in particular can also be part of the process gas supply device, and holders for attaching a gas connection to the spray unit. The holders can also be part of the process gas supply device.

The process gas supply device serves to supply the process gas, preferably an inert gas, preferably argon, with the process gas being heated by the process gas supply device to a temperature of > 1500°C, preferably in a range from 1500°C to 3000°C, preferably from 1500°C to 3300 °C, preferably from 1500 °C to 3500 °C, preferably from 1500 °C to 4000 °C, preferably from 1500 °C to 5000 °C, the temperature of the process gas being reached at the outlet of the process gas from the process gas supply device .

Furthermore, the process gas supply device can shape the process gas flow. This is to be understood as meaning the flow-mechanical form of the process gas stream escaping in particular from the process gas supply device. This gas jet formation can be achieved by the geometric shape of the outlet opening of the process gas supply device, e.g. by modifying the outlet opening of at least one gas guide body of the process gas supply device. In one embodiment, the outlet opening can vary geometrically, e.g . Any geometric modifications of the outlet opening are conceivable in order to modify the flow pattern of the process gas stream.

Furthermore, the spray unit or the process gas supply device can have a flow ring. The flow ring can be attached to a housing of the process gas supply device and/or to the housing of the spray unit. The flow ring is preferably positioned in the area of the outlet opening of the process gas from the process gas supply device or particularly preferably at the outlet of the spray unit, ie in the area in which the process gas emerges from the spray unit in the direction of the surface to be coated. The flow ring has a separate gas connection, preferably for argon. The flow ring guides the gas entering it. For this purpose, the flow ring has a cavity. The flow ring also has openings so that the gas can exit the flow ring from the openings in the direction of the surface to be coated, so that the gas flows around the substrate to be coated, or the substrate surface, in order to avoid atmospheric influences (oxidation, hydrolysis) of the process gas, preferably the enriched process gas comprising the gaseous phase of the solid and the process gas, ie preferably the glass vapor, in the condensation phase. The flow ring is preferably made of a heat-resistant ceramic.

The terms gas and process gas are used analogously here and refer to the gas conducted into the spray unit and/or to the gas transported in the spray unit. In some places in the application, this can also mean the process gas heated in the spray unit.

In a particularly preferred embodiment, the process gas supply device has two gas guide bodies for at least partially transporting and guiding the process gas in the spray unit through the process gas supply device. The process gas supply device can comprise one or two or more gas guiding bodies. The gas guide bodies can be fastened to the housing of the spray unit and/or to a housing of the process gas supply device by means of holders.

The gas fed to the spray unit from the outside is introduced into a gas guide body. A gas guide body can be formed from one body and/or from a plurality of bodies. For example, a gas guide body can be shaped as a cylinder and/or cylindrical, having an inner and an outer radius. The inner radius defines an inner wall of the cylinder and the outer radius defines an outer wall. You are not limited to cylindrical geometries, but any spatial geometries are possible. In the simplest case, a process gas stream can flow through the inner volume of the cylinder formed by the inner wall. Alternatively, a process gas flow can also flow through the volume of the wall of the cylinder. This means that the smaller inner radius of the inner wall of the cylinder results in a volume of the wall in relation to the larger outer radius of the outer wall, i.e. a wall volume. A first process gas stream can flow through this wall volume. A second stream of process gas can flow through the interior volume of the cylinder. The inner and outer wall can be made of tungsten, for example. The cylinder can be made of a porous material. In this particularly preferred case, a first stream of process gas can flow through the wall volume formed from the porous material. The porous material can be tungsten. A foil and/or another layer of material can seal the porous wall volume towards the outside and/or in the direction of the inner volume of the cylinder. Such a material layer can be formed from tungsten, preferably from carbides and/or nitrides, in particular from aluminum nitride and/or from silicon carbide and/or tantalum nitride, or can have such a material or several such materials. A second process gas stream can then flow through the interior volume of the porous, cylindrical gas guide body, in particular without materially exchanging with the first process gas stream.

In a particularly preferred embodiment, the process gas supply device has a first and a second cylindrical gas guide body, each made of porous material. A process gas stream flows through each of the gas guide bodies. A distinction is made between a first and a second process gas stream. This means that the first and second process gas streams in the spray unit can be routed differently through the process gas supply device, e.g. spatially separated from one another and/or at different temperatures and/or with other different process parameters, such as the process gas pressure. In this case, the gas can already be guided through separate inlets into the spray unit and then into the corresponding gas guide body, in particular when the inlet pressures are different. The process gas supply device can have inlets for the inflow of the process gas, which are designed in particular as gas connections, i.e. e.g. gas-tight and/or pressure-resistant. The first process gas flow is heated to at least 1500° C., in particular while it is being transported through the process gas supply device. The gas is introduced into the process gas supply device via the inlets in the gas guide bodies. At least part of the process gas is heated in the process gas supply device by at least one heater of the process gas supply device. The heating of the gas guide body can take place by heating a gas guide body and/or by heating the process gas streams in the gas guide body.

By heating the process gas flow to at least 1500° C., a thermal barrier to the colder housing of the spray unit and to the hotter, in particular first, process gas flow is advantageously built up. Furthermore, condensation and/or nucleation and/or coagulation of the gaseous phase of the solid material, for example to form particles, is efficiently reduced, in particular on the first process gas stream and/or on components of the spray unit and/or on gases such as the room air. The housing of the spray unit and/or a housing of the process gas supply device can spatially at least partially surround the process gas supply device. This means that in particular the heating of a process gas flow and/or a gas guide body can be implemented by heating the process gas supply device mounted outside the housing of the spray unit and/or outside a housing of the process gas supply device. This has the advantageous effect that a heater is cooled by an air flow from the outside air.

A material separating device is to be understood as meaning a device which heats the solid body in such a way that it is at least partially converted into the gaseous phase. In a particularly preferred embodiment, the process gas enriched with the gaseous phase of the solid is also heated by the material separation device.

The solid can be present as a powder. The material separating device has a material separating body. The material separating device also has a heater for heating the material separating body in order to convert the solid body into a gaseous phase by heating the material separating body of the material separating device and to feed it to the second process gas stream in this phase. The heating of the material separation device can be arranged outside the housing of the spray unit. This has the advantageous effect that a heater is cooled by an air flow from the outside air.

In one embodiment, the material separating body can be designed as a capsule and/or as a sleeve, in particular as a metallic capsule and/or sleeve. The material separating body is particularly preferably formed as a cylindrical capsule made of tungsten and/or as a cylindrical sleeve made of tungsten. The material separating body is preferably adapted to the geometric shape of a gas guide body of the process gas supply device. This means that the geometric shape of the material separating body is designed at least in part in such a way that, in order to improve thermal coupling, it engages in the gas guiding body. For this purpose, the material separating body particularly preferably has a cylindrical outer skin which can be inserted at least in sections into a cylindrical inner volume of a gas guide body. A heater for the material separation device can be fitted outside the housing of the spray unit and/or the process gas supply device.

Depending on the embodiment of the material separating body and/or the solid body, the material separating body at least partially encloses the latter. For example, the solid body can be present as a solid body, in particular as a glass rod or glass thread or as a quantity of glass beads, i.e. it can be arranged in the material separation unit. Glass, in particular quartz glass (Si02), or soda-lime glasses, or aluminosilicate glasses, or fluoride glass, or glass ceramics, in particular titanium oxide and/or aluminum oxide, is preferably used; mixtures of glasses or glass ceramics and mixtures of glasses and glass ceramics, in particular Mixtures of the aforementioned glasses and glass ceramics.

In this embodiment, the solid body is at least partially inserted, preferably with an end section, into the material separating body. In particular in such a way that there is good heat transfer between the material separation body and the solid body. The solid can also be present as a powder or in powder form. In this embodiment, the powder can be contained entirely in an embodiment of the material separating body designed, for example, as a capsule.

The solid can be refilled. In one embodiment, for example by replacing the capsule. However, it is also possible to exchange or re-equip a solid body, e.g. the glass rod or the glass thread, which is formed as a whole in the spray unit. In another embodiment, a tracking of the solid body for pushing the solid body designed as a glass rod, for example, can be implemented as part of the material separation device, as a particularly continuous tracking. A solid body can be introduced, for example continuously, into the material separating device, in particular the material separating body, and/or at least partially pushed in or filled into it and at least partially surrounded by it, so that when the material separating body is heated, the solid body separates from its solid into a gaseous phase.

The solid body is converted into a gaseous phase by heating the material separating body of the material separating device. The gaseous phase emerges from the material separating device, ie from the material separating body, in particular in the direction of the process gas flow. Due to the escaping material, further material of the solid body is transported into the material separating body, in particular automatically and/or due to gravitation. In a In a particularly preferred embodiment, the gaseous phase mixes with a first and second process gas stream and thereby forms the enriched process gas. In a further preferred embodiment, the enriched process gas is additionally heated by the heating of the material separation device.

The two-part configuration of the spray unit in particular in the form of a material separation device and a process gas supply device has the advantageous effect that no additional energy, for example to melt a solid powder, has to be supplied to the process gas stream, because the gaseous phase of the solid body enters the process gas stream. It is thus advantageously sufficient to supply the enriched process gas with only that amount of energy which is necessary to prevent condensation associated with cooling, for example on the flow guide of the housing. It is also advantageous to supply only that amount of energy that is necessary so that the particles, which have grown in particular during transport to the material surface, do not form a completely solid phase, i.e. have an essentially liquid surface layer or boundary layer. As a result, the particles adhere to the material surface when they hit it, as well as to each other. On the other hand, if the process gas temperature, in particular the first one, were too low, a high condensation rate, for example, would contribute to strong growth of the particles and thus promote the formation of solid particle boundary layers. Consequently, the ability of the particles to form a surface on the substrate would be limited.

If the suitable gas temperatures of in particular greater than 1500°C of the process gas flow of the process gas supply device are present, the temperature of the process gas flow, which is transported in the direction of the substrate surface, must essentially maintain this temperature or not be significantly higher, e.g. at T < 2000°C, or at T < 2500°C, or at T < 3000°C. Consequently, the temperature of the process gas that hits the surface of the substrate is also lower. This favors the coating of heat-sensitive surfaces.

The temperature of the enriched process gas, which is transported in the direction of the substrate surface through the flow guide, must be so high that the particles growing and/or newly formed during transport to the surface have a melted, in particular almost liquid and/or liquid-like surface, i.e. the particle surfaces are essentially deformable into one another when they hit the substrate surface, i.e. can fuse with one another, i.e. have the ability to join together and/or to one another to form larger particle surfaces, i.e. to coagulate, i.e. the particles can at least partially have a common surface, in particular in sections Form area on the surface of the substrate. The surfaces formed can be connected to one another in a number of spraying processes by forming further surfaces.

The provision of a material separation device and a process gas supply device of the spray unit also advantageously means that the heating process for providing a suitable process gas temperature can be implemented according to different technical principles in one of the respective devices.

The technical principle can be based on the direct heating of the process gas flow of the process gas supply device, for example by inductive heating of the process gas flow. Alternatively, the process gas stream can also be heated indirectly in the process gas supply device. In this case, a material of the process gas supply device can be heated, which then gives off the heat to the process gas stream. E.g. by ohmic and/or by optical heating, e.g. laser, and/or by inductive heating of the material of the process gas supply device, preferably by heating the material of the gas guiding body of the process gas supply device. Combinations of the technologies mentioned are also conceivable. In a preferred embodiment, the optical wavelength is selected in such a way that it is maximally absorbed in the material of the gas guide body of the process gas supply device and heats it.

In one embodiment, the technical principle of heating the material separation device can be based on the direct heating of the material of the material separation body. For example, preferably by inductive heating of an at least partially metallic material separating body. Alternatively, the material separating body can be heated indirectly by heating the material separating device, for example by optical heating by means of a laser and/or ohmic heating of the material of the gas guide body. In a particularly preferred embodiment, a further heating of the material separation device is provided, which can in particular also be used at least partially for direct heating of the enriched process gas. This can work inductively and/or also capacitively. Combinations of the technologies mentioned are also conceivable.

The heating of the material separating device is advantageously designed in such a way that the material separating body is heated directly, the second process gas stream directly and the enriched process gas directly. In a particularly preferred embodiment, this can be done by means of a rotationally symmetrical arrangement of the material separator body and the second gas guide body in relation to one another.

An inductive and/or optical heating can advantageously be adapted to the process gas supply device or to the material separation device. This means, for example, that a heater is optimally adapted to the operating parameters of the process gas supply device or the material separation device. For example, by using a specific electrical frequency and/or wavelength, which efficiently heats the material of the process gas supply device, i.e. using the lowest possible electrical power for this material and/or the structure of the process gas supply device, in particular based on electrical induction and/or optical absorption. Furthermore, the material separation device can have in particular inductive heating, which is adapted to the separation of the solid in its gaseous phase. For example, an inductive heating of the material separating body can work in a frequency range which ideally heats up the material of the material separating body and at the same time quickly heats up the process gas enriched with the gaseous phase of the solid. This means that it must be operated in a frequency range and with an electrical output that allows the material and the process gas to be heated. In one embodiment, the thickness of a material separating body designed as a sleeve is determined in such a way that the penetration depth of the electromagnetic wave is adapted to it, i.e. the wave penetrates deep into the material of the material separating body.

The sleeve can be made of tungsten. The sleeve can have a coating of aluminum nitride. The sleeve can be made of tungsten and have a coating of preferably aluminum nitride. One of the following materials can be selected instead of aluminum nitride: Such a material layer can be formed from tungsten, preferably from carbides and/or nitrides, in particular from aluminum nitride and/or silicon carbide and/or tantalum nitride, or can have such a material or several such materials.

A flow guide can be understood to mean an inner surface of the housing. Alternatively, a surface that can be screwed onto the housing can also be meant. In this case, the surface must be adapted to the temperatures of the outflowing process gas stream, i.e. it must not deform or degrade or decompose under the temperatures. The flow guide can also be in the form of a nozzle, in order to additionally accelerate the process gas flow, for example. The flow guide can also be attached to the spray unit so that it can be removed and/or pivoted. The flow guide guides the process gas with the particles of the solid contained therein in the direction of the surface of the substrate.

The gaseous phase of the solid can also mean an aerosol and/or the evaporated solid material in the gas phase, for example in the form of particles and/or coagulated particles and/or nucleated particles and/or ionized particles and/or combinations thereof. An aerosol is a suspension of fine solid particles or liquid droplets in a gas. The liquid or solid particles typically have diameters of less than 1 μm. The particles can also be partially liquid and solid, e.g., having a liquid or soft surface and a solid core. The state of the particles in this gaseous phase, or the gaseous phase itself, can change due to different processes such as coagulation, i.e. a partial attachment of particles to each other, nucleation, ionic bonding or chemical bonding leading to particle growth. The enriched process gas stream has this gaseous phase of the solid.

• Verfahren zum Aufsprühen eines aus einem Festkörper gewonnenen Materials auf eine insbesondere wärmeempfindliche Materialoberfläche mittels Sprühprozess unter Atmosphärendruck, aufweisend die Schritte:
  • Erhitzen eines ersten Gasführungskörpers um einen ersten Prozessgasstrom von mindestens 1500°C bereitzustellen,
  • Erhitzen eines Materialabscheidekörpers einer Materialabscheideeinrichtung, um unter Atmosphärendruck den Festkörper in eine gasförmige Phase umzuwandeln und in dieser Phase Prozessgasstrom zuzuführen;
  • Führen eines mit dieser Phase angereicherten Prozessgases in Richtung der zu besprühenden Materialoberfläche, um die Materialoberfläche mit dem aufzusprühenden Material zu besprühen.

According to a second aspect of the invention there is provided a method according to claim 15 as follows.

• Method for spraying a material obtained from a solid onto a material surface, in particular a heat-sensitive material, by means of a spraying process under atmospheric pressure, comprising the steps:
  • heating a first gas guide body to provide a first process gas stream of at least 1500°C,
  • Heating a material separating body of a material separating device in order to convert the solid body into a gaseous phase under atmospheric pressure and to supply a process gas stream in this phase;
  • Conducting a process gas enriched with this phase in the direction of the material surface to be sprayed in order to spray the material surface with the material to be sprayed on.

Further aspects of the method according to the invention can be found in the description of the spray head according to the invention, as well as its optional configurations, functions and possible uses, which are described and claimed in this application.

According to one embodiment of the invention, a first gas guide body can be formed at least partially from porous material, in particular from tungsten (W). A first stream of process gas flows through the porous material. As a result, for example, an inductive heater can heat the material of the gas guide body. The porosity increases the contact area efficiently, so that the first process gas stream can be heated to the desired temperature efficiently, i.e. in a short time, for example. The porous material increases the contact surface between the gas guide body and the first process gas stream, so that the energy required for heating is advantageously reduced. The gas guide body can have a sealing coating made preferably from aluminum nitride and/or from tungsten. One of the following materials can be selected instead of aluminum nitride: Such a material layer can be formed from tungsten, preferably from carbides and/or nitrides, in particular from aluminum nitride and/or silicon carbide and/or tantalum nitride, or can have such a material or several such materials .

Alternatively, the first gas guide body can also be designed without a porous gas guide volume, for example in the form of a double-walled body, which can have a tungsten coating, in particular for the purpose of inductive heating. The process gas stream flows through the volume formed by the double wall. Alternatively, the first gas guide body can also be heated optically. In particular by a laser of a certain wavelength, which promotes the absorption of the laser energy in the material of the gas guide body.

According to a further embodiment of the invention, the gas guide body can be encased with a foil, in particular with a W foil, and/or additionally coated with a layer, in particular with a W layer and/or with an aluminum nitride layer, or overmolded . In combination with a porous gas guide body, the W foil and/or the W sprayed layer serves to seal the gas guide body, in particular to seal it laterally, so that the gas flow is guided within the gas guide body. An aluminum nitride layer prevents oxidation, in particular oxidation of a tungsten layer, as a result of which the tungsten layer could be degraded. In other words, in one embodiment, a coating layer, in particular an aluminum nitride layer, can protect the gas guide body from chemical decomposition. One of the following materials can be selected instead of aluminum nitride: Such a material layer can be formed from tungsten, preferably from carbides and/or nitrides, in particular from aluminum nitride and/or silicon carbide and/or tantalum nitride, or can have such a material or several such materials . Alternatively, in the absence of a porous gas guide body, the W foil and/or the W sprayed layer can serve to couple an in particular inductive and/or optical heating output into the gas guide body.

According to a further embodiment of the invention, the process gas supply device can have a first process gas heater for heating the first gas guide body. The first process gas heater can be operated inductively and/or optically and/or ohmically. The provision of a first process gas heater offers the advantage of heating a first process gas stream to an individual temperature, in particular one that is adapted to the gaseous phase of the solid body. This can advantageously reduce and/or prevent condensation of the gaseous phase on the first process gas stream.

According to a further aspect of the invention, the process gas heating of the process gas supply device can work inductively, in particular in a range of 250-950 KHz, or preferably 450-850 KHz, or particularly preferably 650 to 850 KHz. It is also possible and preferable to operate the process gas heater in the frequency range from 250 kHz to 4 MHz, preferably from 500 kHz to 3 MHz, preferably from 800 kHz to 3 MHz, more preferably from 800 kHz to 2.8 MHz. In a preferred embodiment, a first and/or a second process gas heater can be operated in the range from 250 kHz to 4 MHz, preferably from 500 kHz to 3 MHz, more preferably from 800 kHz to 2.8 MHz. Advantageously, the gas guide body can thus be heated very efficiently, ie with little energy consumption, since inductive heating is a direct heating process, ie the heat is generated in the workpiece itself and is not supplied via the surface from the outside by thermal conduction, convection or radiation. If the gas guide body is to be thoroughly heated, for example in order to heat the first process gas transported therein, a correspondingly lower frequency is expedient. For thorough heating, a uniform temperature distribution over the cross-section is obtained in the shortest possible time, if the, in particular cylindrical, Workpiece diameter of the gas guide body is about 3.5 times larger than the penetration dimension. These ratios result from a compromise between direct, uniform heating across the cross-section at a correspondingly lower frequency and increasing electrical efficiency at higher frequencies. An inductor used in this case generally consists of a particularly water-cooled copper conductor, the shape of which is adapted to the geometry of the workpiece, ie the gas guide body and the heating task. The inductor can be a cylindrical or flat coil, but line or hairpin coil shapes can alternatively be used. In addition, elements for guiding the magnetic field, e.g. B. laminated cores, ferrite cores or magnetic flux concentrators may be required to further advantageously increase the efficiency of the heating. This results in an overall immediate, rapid heating of the input material, ie the gas guide body and thus the process gas, in particular the porous gas guide body formed from W, with a small space requirement, ie a compact design of the spray unit.

According to a further aspect of the invention, the material separating device has a process gas heater for heating the material separating body and/or the enriched process gas. The process gas heater is particularly preferably an electrically inductive heater. The second heater can thus inductively heat the material separating body of the material separating device, so that the solid body changes into the gaseous phase. In a particularly preferred embodiment, the process gas enriched with the gaseous phase of two process gas streams at different temperatures can also be heated in this way. Therefore, when using an inductive second process gas heater, the material separating body at least partially has a metallic coating and/or metallic components, or is advantageously made of metallic components or of metal in order to enable electrically inductive heating.

Alternatively, the second process gas heater can also be operated, in particular as a further heating unit of the material separation device, using capacitive technology. In this case, the process gas is heated by applying an additional electrical high-frequency voltage field, advantageously an alternating electrical field for heating and/or in combination with an electrical DC field between the substrate and spray unit, also to transport the process gas in the direction of the surface to be coated.

According to a further aspect of the invention, the second process gas heater can be operated inductively and in a range of 1-8 MHz, preferably 2-5 MHz, particularly preferably 2-3 MHz.

Inductive heating results in a current density distribution in the workpiece, ie in the material separating body, which decreases from a maximum value on the surface towards the interior of the workpiece. This characteristic current density distribution is determined by the electrical conductivity κ and the magnetic permeability µ of the workpiece and, in particular, by the frequency f and is described quantitatively by the electromagnetic penetration δ: $$\delta =\sqrt{\frac{1}{\pi ƒ\mu k}}$$

The electromagnetic penetration, also known as current penetration depth, is the key variable for inductive heating. In the area of the current penetration depth, 86% of the total induced energy is converted into heat. Only the remaining 14% of the total induced energy is absorbed by the deeper layers of the conducting body. Since the degree of penetration is directly dependent on the frequency, the thickness of the directly heated surface layer can be adjusted with the frequency of the coil current. The frequency can advantageously be set such that the heating essentially occurs in the transition area between the material separation body and the first and/or second process gas stream, so that an evaporation process of the solid body into the gaseous state is ideally supported in this area. No additional heat input is therefore necessary in order to compensate for heat conduction processes over a larger area of the material separating body.

According to a further embodiment of the invention, an end section of the solid body can be pushed into the material separating body. This is particularly advantageous when the solid body is formed, for example, as a rod, in particular as a glass rod and/or as a glass thread and/or from a large number of glass threads. One end area of the rod is pushed into the material separating body, in particular movably, so that when the volume of the pushed-in end area decreases due to the transition to the gaseous phase, the other areas of the rod are pushed into the material separating body, in particular automatically, in particular by gravitation and/or by a tracking device will. This advantageously ensures that material is continuously available for spraying the substrate surface.

The material separation device can be formed as a sleeve, in particular as a metal sleeve, in particular as a tungsten sleeve.

The solid that is pushed into or introduced into the material separating body or that is at least partially present in another form, e.g. as a powder or as particles, can touch the material separating body, in particular over a large area, so that the largest possible contact surface results between the material separating body and the material of the solid body to be converted, so that efficient heat transfer from the material separation body to the material of the solid takes place. For this purpose, the solid body and the material separating body can have a geometry that is complementary to one another on the inside and outside, which promotes the formation of a common contact surface.

According to a further embodiment of the invention, the material separating body can have outlet openings for the exit of the gaseous phase of the solid body from the material separating device into the process gas stream. The outlet openings can be arranged laterally on an end section of the material separating body. The end section is formed at least partially by that area around which the process gas stream flows. The outlet openings are preferably slit-shaped, in particular circular and/or grid-shaped. The outlet openings are also advantageously distributed uniformly, in particular on an outer surface, of the material separating body, so that a spatially uniform outlet quantity into the second process gas flow is achieved. The outlet openings can also advantageously be arranged uniformly, in particular around a cylindrical end section of the material separating body. The number of outlet openings is set up in such a way that a material outlet rate is achieved at which essentially all of the material emerging from the outlet openings converts into the gaseous phase.

According to a further embodiment of the invention, a second process gas stream can flow through a second gas guide body of the process gas supply device, which gas guide body runs at least partially inside the first gas guide body. The second gas guide body can preferably be constructed in a manner analogous to the first gas guide body. This is implemented in particular in the case of a cylindrical design of a first and second gas guide body in that the opening of the first cylindrical gas guide body accommodates the second cylindrical gas guide body, i.e. this is arranged inside the first cylinder. Such a cascaded arrangement of the gas guide bodies advantageously leads to a compact spray unit. Further advantageously, the second process gas flow running in the second gas guide body is also heated by the waste heat of the first process gas flow. As a result, the heat output of the first heater can advantageously be used to preheat the second process gas.

The spray unit can have a rotationally symmetrical, in particular cylindrically symmetrical design of the first and/or second gas guiding body and/or the housing. As a result, the heating power put into the system can be used optimally, since this allows cavities to be created in sections that are to be thermally separated, which have a thermally insulating effect, and cavities that improve the heat exchange can be created in other sections.

According to a further embodiment of the invention, a second gas guide body can be formed from porous material, in particular from tungsten, and/or covered with a foil, in particular with a W foil, and/or with a layer, in particular with a W layer , be overmoulded. The gas guide body can also have a coating of preferably aluminum nitride in order to protect the material of the gas guide body from chemical reactions, in particular from chemical decomposition. Instead of aluminum nitride, one of the following materials can be selected: Such a material layer can be formed from tungsten, preferably from carbides and /or nitrides, in particular made of aluminum nitride and/or silicon carbide and/or tantalum nitride, or such a material or several such materials. Use of the porous material as a gas-carrying element of the second gas-carrying body advantageously increases the interaction of the second process gas with the second gas-carrying body, which is indirectly heated, for example, by the first gas-carrying body. As a result, less heating power is required to heat the second process gas.

According to a further embodiment of the invention, the material separating body can be pushed at least partially into the, in particular, second gas guiding body. According to a particularly preferred aspect, the material separating body and the gas guiding body are advantageously designed as cylinders or in the shape of a cylinder, so that the material separating body can be arranged in the tubular passage of the gas guiding body. This results in a process gas stream that is preferably rotationally symmetrical, in which the first process gas stream encases the second process gas stream and the second process gas stream flows at least partially around the material separating body and can additionally give off heat to it and/or absorb heat from it.

According to a further embodiment of the invention, the flow guide can be formed by an end area of a housing of the spray unit, which is set up to guide the enriched process gas in the direction of a spray opening of the housing. In this case, the housing is formed in particular from quartz glass, so that the highest possible temperature tolerance of the housing is achieved. For this purpose, the housing can at least partially have a thin, preferably vapour-deposited, preferably highly reflective layer with a reflection property of preferably greater than 90% in the infrared range (IR range), i.e. in the IR range between 0.78 - 1.4 µm wavelength and /or 1.4-3.0 μm wavelength and/or 3-50 μm wavelength and/or 50-1000 μm wavelength metal layer, preferably Pt layer and/or Au layer, so that thermal radiation of the gas guide body can be shielded. When using inductive heating, the metal layer, preferably the Pt layer, is not applied flatly, but in separate areas, e.g. short non-contiguous line segments, so that an electromagnetic field acting on the layer from the outside cannot induce any inductive power in the layer. whereby overvoltages in the metal layer are prevented.

According to a further particularly preferred embodiment of the invention, a second process gas flow envelops at least sections of a first process gas flow, in particular in the case of a rotationally symmetrical arrangement of the gas guide bodies, i.e. an arrangement of the gas guide bodies in which, in particular, a second tubular gas guide body runs inside a first tubular gas guide body and the material separation device is configured in particular in a cylindrical manner and positioned in a distal portion, i.e. the portion of the tubular second gas guide body facing the spray opening of the housing.

According to a further embodiment of the invention, the solid body can be formed from a large number of solid bodies, for example in the form of glass balls, which are arranged in a movably stacked manner in the interior of the, in particular, tubular gas guide body.

According to a further embodiment of the invention, a distal end of the material separating device, i.e. a section of the material separating device pointing towards the spray opening of the housing, can have a flow turbulence-reducing, in particular conical, shape.

According to a further embodiment of the invention, the housing and/or a first gas guiding body and/or a second gas guiding body are of essentially tubular design. In this case, in a distal region of the spray unit, i.e. in the direction of the side of the spray unit facing the substrate, the respective gas guide body and the housing are arranged in sections one inside the other in a conical manner. Furthermore, in a proximal region of the spray unit, i.e. in the direction away from the substrate, the housing and/or the first gas guide body and/or the second gas guide body are connected to one another by a holding element and coupling element, so that the gas guide bodies and the housing are spatially fixed to one another are arranged.

According to a further embodiment of the invention, the process gas contains an inert gas, preferably Ar. The process gas is particularly preferably Ar.

• 1 zeigt eine Seitenansicht einer Ausführungsform der erfindungsgemäßen Sprüheinheit entlang einer Symmetrieachse.
• 2 zeigt eine Querschnittsansicht der Ausführungsform aus 1 der Sprüheinheit.
• 3 zeigt eine Querschnittansicht der Ausführungsform aus 1 der Sprüheinheit entlang der Schnittebene B-B.
• 4 zeigt in einer Querschnittsansicht das distale Ende einer weiteren Ausführungsform der erfindungsgemäßen Sprüheinheit.
• 5 zeigt eine schematische Ansicht der Sprüheinheit aus 1 angeordnet oberhalb einer zu beschichtenden Substratoberfläche.

Further preferred configurations of the spray unit according to the invention and the method according to the invention also result from the following description of the exemplary embodiments in connection with the figures and their description. Identical components of the exemplary embodiments are essentially identified by the same reference symbols, unless this is described differently or the context does not indicate otherwise. Show it:

• 1 shows a side view of an embodiment of the spray unit according to the invention along an axis of symmetry.
• 2 FIG. 12 shows a cross-sectional view of the embodiment of FIG 1 the spray unit.
• 3 FIG. 12 shows a cross-sectional view of the embodiment of FIG 1 of the spray unit along the cutting plane BB.
• 4 shows a cross-sectional view of the distal end of a further embodiment of the spray unit according to the invention.
• 5 Fig. 12 shows a schematic view of the spray unit 1 arranged above a substrate surface to be coated.

In 1 a side view of an embodiment of the spray unit 1 along an axis of symmetry A is shown. The axis of symmetry A runs from a distal end 19 of the housing 8 of the spray unit 1 to a proximal end 20. The distal end 19 of the housing 8 has a spray opening 9 and is aligned in the direction of the material surface 3 to be coated. From the spray opening 9 flows the enriched process gas 7, which is the heated gaseous Material of the solid 2 contains in the direction of the surface to be coated 3 (not shown). The proximal end 20 of the housing 8 of the spray unit 1 points towards a user (not shown). The proximal end 20 includes a first 21 and a second 22 gas inlet. The first gas inlet 21 directs the process gas into the first gas guide body 4a, the second gas inlet 22 directs the process gas into the second gas guide body 4e. In this embodiment, the process gas is Ar and/or N, particularly preferably only Ar. At the proximal end 20 of the spray unit 1 there is a holder for a shaft sealing ring 23. The proximal end 20 also has a screw cap 24. The course of the housing 8 along the axis of symmetry A is conical in sections, with the proximal end 20 to the distal end 19 Housing tapered after a first conical portion 25 and after a second conical portion 26 further tapered. The cone-shaped second section of the housing 8 forms the flow guide 6 by guiding the enriched process gas 7 in the direction of the spray opening 9 . In this embodiment, the housing 8 is made of quartz glass. At the distal end 19 of the housing 8, two areas are marked with a respective rectangle. The rectangle arranged closer to the spray opening 9 delineates that area in which the second process gas heater 5b is positioned. The rectangle extending over the second conical section, that area in which the first process gas heater 4d is positioned.

In 2 FIG. 12 is a cross-sectional view of the embodiment of the spray unit of FIG 1 shown schematically. The cross-sectional view is off to the side view 1 rotated by 90° around the axis of symmetry A. At the in 2 In the shown tubular interlocking arrangement of housing 8, first 4a and second 4e gas guide body, a respective tubular body runs within the tubular body of another body, with the merely tubular wall volumes 28, 29, 30 of the body in 2 are drawn. The material separating body 5a of the material separating device 5 is located starting from the spray opening 9 at the distal end 19 of the housing 8 of the spray unit 1. The material separating body 5a has a streamlined outer contour at its distal end in the direction of the spray opening 9. The streamline shape reduces the formation of vortices in the outflow area of the housing 8 . The distal region of the material separating body 5a has two parallel rows of slit-shaped outlet openings 5c. The respective outlet openings 5c are also drawn inclined at an angle relative to the axis of symmetry A. The proximal area of the material separating body 5a is drawn inserted into the distal area of the second gas guiding body 4e. To hold the material separating body 5a in the proximal area of the second gas guiding body 4e, the proximal end of the separating body is conical, so that the conical section of the material separating body 5a hooks into a corresponding recess 27 of the second gas guiding body 4e. The recess 27 continues as a step in the outer contour of the wall volume 28 of the second gas guide body 4e. The wall volume 29 of the first gas guide body 4a and the wall volume 30 of the housing 8 engage in this step of the wall volume 28, so that the housing of the adjoining wall volumes 28, 29, 30 narrows conically in sections overall. The wall volume 30 of the housing 8, which can be solid, extends to the distal end 19 of the spray unit 1 and forms the spray opening 9 there. The second gas guide body 4e extends slightly beyond the distal end of the first gas guide body 4a, so that the first process gas stream 4b emerging from the material of the wall volume 28 of the first gas guide body 4a runs guided in this area by the wall volume 29 of the second gas guide body 4e. The first process gas flow 4d emerging from the wall volume 29 of the first, in particular porous, gas guide body 4a heats up the wall volume 28 of the second gas guide body 4e in this section. The second gas guide body 4d extends below the slit-shaped outlet openings 5c of the material separating body 5a, so that the second process gas flow 4c emerging from the wall volume 28 of the second gas guide body 4e flows over the outlet openings 5c and the gaseous phase of the solid body 2 emerging from the outlet openings 5c transported to the outlet openings 5c in the direction of the spray opening 9. The outlet openings 5c, which run obliquely to the axis of symmetry, induce a helical, vortex-shaped enriched process gas flow in the direction of the substrate surface as a result of the oblique position.

Since the first gas guide body 4a has a larger inside diameter than the outside diameter of the second gas guide body 4e located therein, a cavity 31 is formed between the wall volumes 28, 29 of the gas guide bodies 4a, 4e. Due to the conical interlocking of the wall volumes 28, 29 of the gas guide bodies 4a, 4e and the wall volume 30 and/or the wall 30 of the housing 8 at the distal end of the spray unit 1, the respective gas guide bodies 4a, 4e are mounted in the housing, in particular rotationally symmetrically, distal to the housing 8 . A proximal mounting of the second gas guide body 4e on the first gas guide body 4a takes place by a coupling element 32. A holding element 33 supports the first gas guide body 4a on the housing 8 near the proximal end 20. The housing 8 and the first gas guide body 4a are then closed at the proximal end 20 by a screw cap 24 to the outside. The respective gas inlets 21 in the, in particular porous, wall volume 28 of the first gas guide body 4a are also integrated in the screw cap 24 . The coupling element 32 engages in the proximal end of the second gas guiding body 4e in the distal direction and a guide cylinder 34 is pushed into the coupling element 32 in the proximal direction. The coupling element 32 and the guide cylinder 34 each have a conical end section so that the guide cylinder rests against the inner wall of the coupling element 32 in a sealing manner. A gas inlet 22 is mounted on the guide cylinder 34 in order to direct the second process gas stream 4c through the guide cylinder to the first gas guide body. The coupling element 32 also serves to introduce the second process gas stream 4c into the, in particular porous, wall volume 29 of the second gas guide body 4e. The guide cylinder 34 is sealed by a radial shaft sealing ring 35 which is arranged in a holder 36 at the proximal end of the guide cylinder 34 . This prevents, on the one hand, oxygen from entering the interior of the spray unit 1 from the outside and, on the other hand, preventing process gas from escaping from the inside to the outside.

In 2 the course of the first and second process gas flow is indicated by arrows. The arrows are drawn running on the respective wall volumes 28, 29 of the cylindrical gas guide body in order to indicate that the gas flow takes place within the wall volumes 28, 29. The wall volumes 28, 29 are advantageously formed from a porous material volume, so that there is a high contact rate between the gas flow and the wall volumes 28, 29. In this case, a first and/or a second gas guide body can be made porous. Alternatively, the gas streams run within double-walled geometries, in particular double-walled cylinders, ie a geometry in which an inner and outer wall forms a cavity through which a gas can flow. In 2 The exit of the gaseous phase from the material separating body 5a is not shown.

Further in 2 The areas marked by rectangles are shown, in which the respective first and second process gas heaters 4d, 5b are arranged. In the present embodiment, the first and second process gas heaters 4d, 5b each preferably work inductively. The first process gas heater 4d essentially serves to heat the first process gas stream 4b to a temperature greater than 1500°C. In this case, the electrical frequency of the inductively operating process gas heating is set to 800 KHz in the embodiment. In the selected range, the frequency has a high penetration depth into the material of the gas guide body 4a, as a result of which it heats up quickly. The process gas heated up as a result also gives off heat to the second gas guide body 4e via the cavity and in particular in the conical distal section, as a result of which the second process gas flow 4c is also heated further. The heating of the second gas guiding body 4c also leads to a heating of the material separating body 5a pushed into the gas guiding body 4c. When the first gas stream 4b emerges from the gas guide body 4a, it flows around the second gas guide body 4e and encases the second process gas stream 4c in a rotationally symmetrical manner. The second process gas heater 5b is arranged in such a way that it heats the distal end 19 of the second gas guide body 4e and the enriched process gas 7 exiting. The second process gas heater 5b is operated at a frequency of 2.8 MHz. The depth of penetration of the second inductively operating process gas heater 5b into the gas guide body 4e is less, since the heater is also intended to heat up the enriched process gas 7 . When the solid material exits through the outlet openings 5c, the course of the flow is disturbed in such a way that a helical, vortex-shaped flow is achieved, with the first process gas flow 4b enveloping the process gas flow enriched from the second 4c and the gaseous phase. This advantageously eliminates the melting of the solid powder in the process gas stream during transport to the substrate surface, which is common in an IPC burner, for example. The amount of energy induced in the second and first process gas flow in the form of, in particular, electrically inductive power can thus be lower.

In 3 12 is a cross-sectional view of the embodiment of FIG 1 of the spray unit along the sectional plane BB is shown schematically. In the rotationally symmetrical arrangement, the housing 8 forms the outer shape of the spray unit, which is adjoined by the cylindrical first gas guide body 4a. The second gas guide body 4e has a significantly smaller outer radius than the first gas guide body 4a, so that a cavity 31 is formed between the two gas guide bodies 4a, 4e. Inside the second gas guide body 4e, the solid body is indicated with oblique hatching. in the in 3 shown embodiment, the solid is designed as a glass rod. The proportions do not reflect the actual proportions. The wall thicknesses of the gas guide body 4a, 4e and that of the housing can vary from those in 3 shown. The process gas flow runs out of the section plane BB and within the wall volumes 28, 29 of the cylinders, which are drawn in a dotted manner and are particularly porous. In an embodiment with porous wall material, preferably porous tungsten (W), a W layer is sprayed onto the respective walls or the respective walls are covered with a W foil to seal the respective wall volumes (not shown). A respective process gas flow is thus transported within the porous wall volumes 28 , 29 . Due to the associated increased interaction of the gas with the wall surfaces, the temperature of the wall volumes 28, 29 is efficiently transferred to the process gas flow.

4 shows in a cross-sectional view the distal end of a further embodiment of the spray unit. The respective coil formers of an inductive first and second process gas heater 4d, 5b are sketched in the rectangular areas drawn with dot-dash lines. The solid body 2 is drawn inserted in a solid phase into the material separation body 5a. In this case, the solid body can be positioned up to the outlet openings of the material separating body 5a, in particular by the solid body 2 sliding down automatically. In this embodiment, the first process gas heater 4d is operated at a frequency of 800 kHz and essentially heats the first gas guide body 4a. In this embodiment, the second process gas heater is operated at a frequency of 2.8 MHz and heats the distal area of the second gas guide body 5b as well as the enriched process gas. In this embodiment, the outlet openings 5c of the material separating body 5a are drawn in at an angle to an axis of symmetry (not shown). The course of the gas flow is indicated by arrows in the area of the flow guide 6 formed by the housing 8 . In this embodiment, the distal end of the material separating body 5a is not shown in a streamlined manner, but drawn in the shape of a rectangle. This leads to an increased formation of vortices at the rectangular edge of the distal end of the material separation device 5, since this acts as a tear-off edge.

In 5 FIG. 12 is a schematic view of the spray unit 1 of FIG 1 shown, which is arranged above a material surface 3 to be coated. When the spray unit 1 is used as intended, the spray unit 1 is arranged vertically, ie at an angle of essentially 90° with respect to the material surface 3 . The material surface 3, also substrate surface 3, can be pretreated for the purpose of coating with a precoating 37, in particular with a silicate-based sol layer. However, the coating of the material surface 3 can also be carried out without this pretreatment. The material surface 3 can be formed from concrete, ceramics, glass, sand-lime brick, marble, wood, plastics, steel or metal, and from combinations of such materials. The enriched process gas 7 emerging from the spray opening 9 flows in the direction of the material surface 3 to be coated and is deposited or sprayed onto this material surface 3 . The particles of the enriched process gas 7 formed from the gaseous phase by, for example, condensation, coagulation and/or nucleation are present, for example as an aerosol. The temperature of the enriched process gas 7 can be in the range between 1500°C - 2500°C. The coating process takes place under atmospheric pressure. The surfaces of the particles formed are soft, in particular in a liquid phase, so that the particles impinging on the material surface 3 or the pre-coating 37 at least partially bond with one another and with the material surface, in particular a pre-coated substrate surface 37 .

The spray unit 1 can be used for coating against the in 5 drawn axis A be inclined. The spray unit 1 is preferably arranged vertically, ie at an angle of 0° to the axis A. If the spray unit 1 is used as intended, however, other conceivable inclinations are possible. For example, the spray unit 1 can be inclined at 30°, 45°, 60° to the axis A, as shown in 5 indicated is outlined.

Reference List

1

Spray unit 1

2

solid 2

3

End portion of the solid 2a

4

material surface 3

5

Process gas supply device 4

6

Gas guide body 4a

7

First process gas stream 4b

8th

Second process gas stream 4c

9

First process gas heater 4d

10

Second gas guide body 4e

11

Material separation device 5

12

Material separation body 5a

13

Second process gas heater 5b

14

outlet openings 5c

15

flow guide 6

16

Enriched process gas 7

17

housing 8

18

Spray hole 9

19

Distal end 19

20

Proximal end 20

21

Gas inlet 21, 22

22

Bracket for oil seal 23

23

screw cap 24

24

Tapered first and second sections 25, 26

25

recess 27

26

Wall volumes 28, 29, 30

27

cavity 31

28

Coupling element 32

29

holding element 33

30

Guide cylinder 34

31

Radial shaft sealing ring 35

32

Bracket for radial shaft seal 36

33

pre-coating

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102014103025 A1 [0002]
• EP 1978038 A1 [0003]

Claims (15)

Spraying unit for spraying a material obtained from a solid onto an, in particular heat-sensitive, material surface by means of a spraying process under atmospheric pressure - a process gas supply device, set up to heat a gas guide body so that a process gas flow of at least 1500°C is provided, - a material separating device, set up to convert the solid body into a gaseous phase under this atmospheric pressure by heating a material separating body of the material separating device and to supply it to the process gas stream in this phase, and - A flow guide set up to guide the process gas enriched with this phase in the direction of the material surface to be sprayed. spray unit after claim 1 , wherein the gas guide body is formed at least partially from porous material, in particular from tungsten (W), through which the process gas stream flows. Spray unit according to one of Claims 1 - 2 , wherein the gas guide body is covered with a film, in particular with a W film, and/or is spray-coated with a layer, in particular with a W layer. Spray unit according to one of Claims 1 - 3 , wherein the process gas supply device on a process gas heater, so that the gas guide body and / or the process gas is heated. spray unit after claim 4 , wherein the process gas heating, in particular that of the process gas supply device, works inductively and in a range of 250-950 KHz, preferably 450-850 KHz, particularly preferably 650 to 850 KHz. Spray unit according to one of Claims 1 - 5 , wherein the material separating device has a process gas heater, so that the material separating body and/or the process gas, in particular the enriched process gas, is heated. spray unit after claim 6 , wherein the process gas heating, in particular that of the material separation device, works inductively and in a range of 1-8 MHz, preferably 2-5 MHz, particularly preferably 2-3 MHz. Spray unit according to one of Claims 1 - 7 , wherein an end portion of the solid body is inserted into the material separating body. Spray unit according to one of Claims 1 - 8th , wherein the material separating body has outlet openings for the exit of the gaseous phase of the solid body from the material separating device into the process gas flow. Spray unit according to one of Claims 1 - 9 , wherein the process gas stream flows through a further gas guide body of the process gas supply device, which runs at least partially inside the first gas guide body. spray unit after claim 10 , wherein the further gas guide body is formed from porous material, in particular from tungsten, and/or is coated with a foil, in particular with a W foil, and/or is spray-coated with a layer, in particular with a W layer. Spray unit according to one of Claims 10 - 11 , wherein the Materialabscheidekörper is at least partially pushed into the other gas guide body. Spray unit according to one of Claims 1 - 12 , wherein the flow guide is formed by an end region of a housing of the spray unit, set up to guide the enriched process gas in the direction of a spray opening of the housing. spray unit after Claim 13 , wherein the housing is formed from quartz glass and at least partially has a Pt layer. Method for spraying a material obtained from a solid onto a material surface, in particular a heat-sensitive material, by means of a spraying process under atmospheric pressure, comprising the steps Heating a first gas guide body so that a process gas flow of at least 1500° C. is provided; Heating a material separating body of a material separating device in order to convert the solid body into a gaseous phase under atmospheric pressure and to feed it to the process gas stream in this phase; Conducting a process gas enriched with this phase in the direction of the material surface to be sprayed in order to spray the material surface with the material to be sprayed on.

Images