EP0672197A1 - Process for producing a protective coating on metal walls subject to attack by hot gases, especially flue gases - Google Patents

Process for producing a protective coating on metal walls subject to attack by hot gases, especially flue gases

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Publication number
EP0672197A1
EP0672197A1 EP93912953A EP93912953A EP0672197A1 EP 0672197 A1 EP0672197 A1 EP 0672197A1 EP 93912953 A EP93912953 A EP 93912953A EP 93912953 A EP93912953 A EP 93912953A EP 0672197 A1 EP0672197 A1 EP 0672197A1
Authority
EP
European Patent Office
Prior art keywords
walls
powder
protective layer
stress
basic material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP93912953A
Other languages
German (de)
French (fr)
Other versions
EP0672197B1 (en
Inventor
Bodo Häuser
Wilhelm Heesen
Johannes Hermsen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HAEUSER & CO. GMBH
Original Assignee
Thyssen Stahl AG
Thyssen Guss AG
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Publication of EP0672197A1 publication Critical patent/EP0672197A1/en
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Publication of EP0672197B1 publication Critical patent/EP0672197B1/en
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
    • C23C4/134—Plasma spraying
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/16—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed
    • B05B7/22—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed electrically, magnetically or electromagnetically, e.g. by arc
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/10—Oxides, borides, carbides, nitrides or silicides; Mixtures thereof

Definitions

  • the invention relates to a method for producing a protective layer on walls of combustion plants, heat exchangers or similar plants, which are exposed to hot gases, in particular flue gases and are loaded in a predetermined temperature range, and in which a plasma spraying process is used a powder of metallic, carbide, oxide ceramic or silicide materials or mixtures of these materials is applied to the previously cleaned, metallic walls to form the protective layer.
  • Such protective layers should e.g. be applied to cooling walls of waste heat boilers on steel converters. These walls are exposed to particularly high loads. On one side flow approx. 1 00 ° -
  • DE 23 55 532 C2 discloses a method for powder deposition welding of metals and alloys on a preheated metal base prepared by sandblasting, in which the metal liage is previously heated to at least 100 to about 650 ° C.
  • the base material is heated very strongly when the protective layer is applied, which leads to an undesirable structural change.
  • the melting temperature is between 980 and 1060 ° C, depending on the spray powder used. Due to the high heat input, this also occurs Warping of the walls to be coated. When installing these walls, problems and additional costs may arise due to the dimensional inaccuracies.
  • the protective layer has a thickness of approximately 8 to 10 mm for build-up welding and 1 to 2 mm for flame spraying.
  • DE-AS 26 30 507 is also a process for the production of
  • the present invention has for its object to propose a generic method in which these problems do not occur and in particular the distortion of the workpieces and crack-forming stresses in the base material are avoided.
  • the base material of the walls is activated in such a way that disturbances are generated in the metallic lattice, as a result of which the adhesive forces are increased.
  • the powder is then applied to the walls under atmospheric conditions after the plasma spraying process, the surface of which thereby maintains approximately room temperature.
  • the composition of the powder is determined depending on the existing base material and the later operating conditions, in particular the specified temperature ranges.
  • tensile stresses of between 50 and 800 N / mm 2 , preferably between 500 and 800 N / mm 2
  • These stress states are calculated by means of the thermal expansion coefficients of the base material on the one hand and of test workpieces made of different powders on the other hand. The mathematical determination can then be checked in accordance with DIN 50121.
  • a heat-resistant and shock-resistant protective layer against hot gas corrosion and / or mechanical wear is generated on flat or curved walls of combustion plants, heat exchangers, in particular of waste heat boilers on steel converters.
  • an 80 KW plasma spraying device with an internal powder supply has proven to be particularly suitable. It becomes powder with a grain size of less than 75 ⁇ m, preferably 20 to
  • the surface of the walls to be treated can be roughened and activated with high-grade corundum, preferably with high-purity white high-grade corundum.
  • the surface is only heated to approximately 40 ° C. at most 60 ° C. by the plasma jet and the powder particles melted therein. As a result, warping of the wall surfaces can be excluded in particular.
  • a powder containing a Ni alloy is expediently used.
  • the stress temperature of the walls treated with a protective layer can be in the range between 300 and 1800 ° C., preferably 600 and 1000 ° C.
  • the voltage behavior in the transition zone of the base material and the applied protective layer in the temperature range between 0 and approximately 1200 ° C. is shown as an example in a voltage-temperature diagram. This is based on the measured, average linear thermal expansion coefficients of the two material partners.
  • the tensile state slowly builds up again after the stress, ie in the diagram, the drawn line of the stress curve is traversed in the opposite direction.
  • the so-called 0 state can naturally also be 400 ° or 800 ° C instead of 700 ° C.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electromagnetism (AREA)
  • Coating By Spraying Or Casting (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
  • Chemical Vapour Deposition (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Laminated Bodies (AREA)

Abstract

A process for producing a protective coating on walls subject to attack by hot gases in a predetermined temperature range, which are made of metal and a predetermined basic material, in combustion plants, heat exchangers or similar installations, in which a powder of metallic, carbide, oxycarbide or silicide materials or mixtures thereof are applied to the metal walls using the plasma jet process. The invention proposes that: a) the surface of the wall is roughened; b) the basic material of the wall is activated; and c) immediately afterwards the powder is applied at room temperature and in atmospheric conditions by the plasma jet process; being d) the composition of the powder selected beforehand so that the stress as a function of the temperature in the unstressed state (at room temperature) found with the aid of the coefficients of heat expansion of the basic material and test-pieces for the transition region between the basic material and the applied coating produced from various powders gives tensile stresses of between 50 and 800 N/mm2 and preferably between 500 and 800 N/mm2, which is reduced to 0 or exhibits slight compression stresses in the predetermined temperature range.

Description

Beschreibung: Description:
Verfahren zur Herstellung einer Schutzschicht auf mit heißen Gasen, insbesondere Rauchgasen beaufschlagten metallischen WändenProcess for producing a protective layer on metallic walls exposed to hot gases, in particular flue gases
Die Erfindung bezieht sich auf ein Verfahren zur Herstellung einer Schutz- schicht auf mit heißen Gasen, insbesondere Rauchgasen beaufschlagten und in einem vorgegebenen Temperaturbereich beanspruchten, metallischen und aus einem vorgegebenen Grundwerkstoff bestehenden Wänden von Verbrennungsanlagen, Wärmetauschern oder ähnlichen Anlagen, bei dem mit Hilfe des Plasmaspritzverfahrens auf die zuvor gereinigten, metallischen Wände zur Bildung der Schutzschicht ein Pulver aus metallischen, karbidischen, oxidkeramischen oder silicidischen Werkstoffen oder Mischungen dieser Werkstoffe aufgetragen wird.The invention relates to a method for producing a protective layer on walls of combustion plants, heat exchangers or similar plants, which are exposed to hot gases, in particular flue gases and are loaded in a predetermined temperature range, and in which a plasma spraying process is used a powder of metallic, carbide, oxide ceramic or silicide materials or mixtures of these materials is applied to the previously cleaned, metallic walls to form the protective layer.
Derartige Schutzschichten sollen z.B. auf Kühlwände von Abhitzekesseln an Stahlkonvertern aufgetragen werden. Diese Wände sind besonders hohen Belastungen ausgesetzt. Auf der einen Seite strömen ca. 1 00° -Such protective layers should e.g. be applied to cooling walls of waste heat boilers on steel converters. These walls are exposed to particularly high loads. On one side flow approx. 1 00 ° -
1800° C heiße, mit Asche und Schlackepartikeln beladene Rauchgase entlang, während auf der anderen Seite Sattdampfdrücke von ca. 20 - 80 bar herrschen. Die sattdampfgekühlten Rohrwände haben dabei Innendruck-Gradienten von bis zu 2 bar/min.1800 ° C hot smoke gases loaded with ash and slag particles along, while on the other hand there are saturated steam pressures of approx. 20 - 80 bar. The saturated steam-cooled tube walls have internal pressure gradients of up to 2 bar / min.
Aus der DE 23 55 532 C2 ist ein Verfahren zum Pulverauftragsschweißen von Metallen und Legierungen auf eine durch Sandstrahlen vorbereitete, vorgewärmte Metallunterlage bekannt, bei dem die Metal lunteriage zuvor auf mindestens 100 bis etwa 650° C erhitzt wird. Sowohl beim Auftragsschweißen mittels Stabelektrode als auch beim Pulverauftragsschweißen oder Flammspritzen mit nachträglichem Ein¬ schmelzen wird beim Aufbringen der Schutzschicht der Grundwerkstoff sehr stark erhitzt, was zu einer unerwünschten Gefügeänderung führt. Insbesondere bei dem Flammspritzen liegt die Einschmelztemperatur in Abhängigkeit von dem verwendeten Spritzpulver zwischen 980 und 1060° C. Bedingt durch die hohe Wärmeeinbringung kommt es außerdem zum Verzug der zu beschichtenden Wände. Beim Einbau dieser Wände kann es dann zu Problemen und zusätzlichen Kosten wegen der Maßun- genauigkeiten kommen. Wenn die Schutzschichten mit diesen bekannten Verfahren nachträglich aufgebracht werden, können die temperaturbedingten Spannungen nicht in Form von Verzug reagieren, sondern führen bei den eingebauten Wandeiementen zu Rissen in der Oberfläche, insbesondere im Bereich der Schweißnähte. Beim Auftragsschweißen hat die Schutzschicht eine Dicke von etwa 8 bis 10 mm und beim Flammspritzen von 1 bis 2 mm.DE 23 55 532 C2 discloses a method for powder deposition welding of metals and alloys on a preheated metal base prepared by sandblasting, in which the metal liage is previously heated to at least 100 to about 650 ° C. Both in the case of build-up welding using a stick electrode and in the case of powder build-up welding or flame spraying with subsequent melting, the base material is heated very strongly when the protective layer is applied, which leads to an undesirable structural change. In the case of flame spraying in particular, the melting temperature is between 980 and 1060 ° C, depending on the spray powder used. Due to the high heat input, this also occurs Warping of the walls to be coated. When installing these walls, problems and additional costs may arise due to the dimensional inaccuracies. If the protective layers are subsequently applied using these known methods, the temperature-related tensions cannot react in the form of warping, but instead lead to cracks in the surface of the installed wall elements, particularly in the area of the weld seams. The protective layer has a thickness of approximately 8 to 10 mm for build-up welding and 1 to 2 mm for flame spraying.
Aus der DE-AS 26 30 507 ist außerdem ein Verfahren zur Herstellung vonDE-AS 26 30 507 is also a process for the production of
Schutzschichten auf Werkstücken gegen Heißgaskorrosion und/oder mechanischen Verschleiß bekannt, bei dem mittels Plasmaspritzen im Vakuum ein aus verschiedenen Legierungen bestehendes Beschichtungspulver auf das Werkstück aufgetragen wird. Bei diesem Vakuumspritzverfahren muß mit erheblichem Aufwand in einer von außen nicht zugänglichen Bearbeitungskammer ein Vakuum erzeugt und die Beschichtung durchgeführt werden. Bei größeren, z.B. im Abhitzekessel eingebauten Wänden ist dies nicht möglich.Protective layers on workpieces against hot gas corrosion and / or mechanical wear are known, in which a coating powder consisting of different alloys is applied to the workpiece by means of plasma spraying. In this vacuum spraying process, a vacuum has to be generated with considerable effort in a processing chamber that is not accessible from the outside and the coating has to be carried out. With larger, e.g. this is not possible in the walls of the waste heat boiler.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein gattungsgemäßes Verfahren vorzuschlagen, bei dem diese Probleme nicht auftreten und insbesondere der Verzug der Werkstücke und rißbildende Spannungen im Grundwerkstoff vermieden werden.The present invention has for its object to propose a generic method in which these problems do not occur and in particular the distortion of the workpieces and crack-forming stresses in the base material are avoided.
Die erfindungsgemäße Lösung der Aufgabe ist im Kennzeichen des Anspruchs 1 wiedergegeben. Die Unteransprüche 2 bis 10 enthalten sinnvolle ergänzende Verfahrensschritte.The achievement of the object is shown in the characterizing part of claim 1. The sub-claims 2 to 10 contain useful additional procedural steps.
Bei dem erfindungsgemäßen Verfahren wird vor dem Auftragen des Pulvers mit dem atmosphärischen Plasmaspritzverfahren nicht nur die Oberfläche der Wände aufgerauht, sondern auch der Grundwerkstoff der Wände in der Weise aktiviert, daß Störungen im metallischen Gitter erzeugt werden, wodurch die Adhäsionskräfte erhöht werden. Unmittelbar anschließend, bevor diese Störungen im Gitter wieder aufgehoben sind, wird dann unter atmosphärischen Bedingungen nach dem Plasmaspritz¬ verfahren das Pulver auf die Wände aufgetragen, deren Oberfläche dabei etwa Raumtemperatur behält.In the method according to the invention, not only is the surface of the walls roughened before the powder is applied with the atmospheric plasma spraying method, but also the base material of the walls is activated in such a way that disturbances are generated in the metallic lattice, as a result of which the adhesive forces are increased. Immediately afterwards, before these disturbances in the grid are eliminated again, the powder is then applied to the walls under atmospheric conditions after the plasma spraying process, the surface of which thereby maintains approximately room temperature.
**
Die Zusammensetzung des Pulvers wird in Abhängigkeit von dem vorhandenen Grundwerkstoff und den späteren Betriebsbedingungen, insbesondere den vorgegebenen Temperaturbereichen, bestimmt. Erfindungsgemäß sollen für den Übergangsbereich zwischen Grundwerkstoff und aufgetragener Schicht im nichtbeanspruchten Zustand, d.h. bei Raumtemperatur, Zugspannungen zwischen 50 und 800 N/mm2, vorzugsweise zwischen 500 und 800 N/mm2 vorliegen, die in dem vorgegebenen beanspruchten Temperaturbereich im wesentlichen auf 0 abgebaut sind oder geringe Druckspannungen aufweisen. Diese Spannungszustände (vgl. beigefügte Figur) werden rechnerisch mit Hilfe der Wärmeausdehnungskoeffizienten von Grundwerkstoff einerseits und von aus verschiedenen Pulvern hergestellten Probewerkstücken andererseits ermittelt. Eine Überprüfung der rechnerischen Bestimmung kann dann nach DIN 50121 durchgeführt werden.The composition of the powder is determined depending on the existing base material and the later operating conditions, in particular the specified temperature ranges. According to the invention, tensile stresses of between 50 and 800 N / mm 2 , preferably between 500 and 800 N / mm 2, should be present for the transition area between the base material and the applied layer in the non-stressed state, ie at room temperature, which are substantially reduced to 0 in the specified temperature range are or have low compressive stresses. These stress states (cf. attached figure) are calculated by means of the thermal expansion coefficients of the base material on the one hand and of test workpieces made of different powders on the other hand. The mathematical determination can then be checked in accordance with DIN 50121.
Mit dem erfindungsgemäßen Verfahren kann z.B. auf ebenen oder gebogenen Wänden von Verbrennungsanlagen, Wärmetauschern, insbesondere von Abhitzekesseln an Stahlkonvertern eine wärmeschockunempfindliche und reparaturfreundliche Schutzschicht gegen Heißgaskorrosion und/oder mechanischen Verschleiß erzeugt werden.With the method according to the invention e.g. A heat-resistant and shock-resistant protective layer against hot gas corrosion and / or mechanical wear is generated on flat or curved walls of combustion plants, heat exchangers, in particular of waste heat boilers on steel converters.
Es hat sich gezeigt, daß eine Endschichtdicke von 0,1 bis 0,5 mm, vorzugsweise 0,15 bis 0,25 mm bereits ausreicht, um auch über einen wesentlich längeren Zeitraum als bisher möglich einen nennenswerten Verschleiß zu verhindern. Zur Aufbringung einer derartigen Schutzschicht hat sich vor allem eine 80 KW-Plasmaspritzaniage mit Innenpulverzuführung als besonders geeignet erwiesen. Es wird dabei Pulver mit einer Korngröße von weniger als 75 μm, vorzugsweise 20 bisIt has been shown that a final layer thickness of 0.1 to 0.5 mm, preferably 0.15 to 0.25 mm, is already sufficient to prevent any noteworthy wear over a much longer period than was previously possible. For the application of such a protective layer, an 80 KW plasma spraying device with an internal powder supply has proven to be particularly suitable. It becomes powder with a grain size of less than 75 μm, preferably 20 to
40 μm verwendet. Mit diesem Pulver kann insbesondere eine sehr dünne Schicht aufgebracht werden, die die Bedingung der Wärmeschock- unempfindlichkeit und der Beständigkeit gegen Heißgaskorrosion erfüllt, und hohe Eigenspannung, bedingt durch den prozeßbedingten laminaren Schichtaufbau, vermeidet. Die Gesamtschicht wird günstigerweise in mindestens zwei Übergängen hergestellt.40 μm used. With this powder, in particular, a very thin layer can be applied, which meets the thermal shock insensitivity and resistance to hot gas corrosion fulfilled, and high internal stress, due to the process-related laminar layer structure, avoided. The entire layer is advantageously produced in at least two transitions.
Vor dem Plasmaspritzen kann die zu behandelnde Oberfläche der Wände mit Edelkorund, vorzugsweise mit hochreinem weißen Edelkorund aufgerauht und aktiviert werden.Before the plasma spraying, the surface of the walls to be treated can be roughened and activated with high-grade corundum, preferably with high-purity white high-grade corundum.
Weiterhin hat es sich als günstig erwiesen, daß beim erfindungs¬ gemäßen Verfahren die Oberfläche durch den Plasmastrahl und die darin aufgeschmolzenen-Pulverpartikel nur auf ca. 40° C maximal 60° C erwärmt wird. Hierdurch kann insbesondere ein Verzug der Wandflächen ausgeschlossen werden.Furthermore, it has proven to be advantageous that in the method according to the invention, the surface is only heated to approximately 40 ° C. at most 60 ° C. by the plasma jet and the powder particles melted therein. As a result, warping of the wall surfaces can be excluded in particular.
Zweckmäßig wird ein eine Ni-Legierung enthaltendes Pulver verwendet.A powder containing a Ni alloy is expediently used.
Es hat sich gezeigt, daß die atmosphärische Plasmabeschichtung spätestens 45 Min., vorzugsweise spätestens 30 Min. nach derIt has been shown that the atmospheric plasma coating at the latest 45 minutes, preferably at the latest 30 minutes after the
Aktivierung der Oberfläche der Wände durchgeführt werden sollte.Activation of the surface of the walls should be done.
Schließlich kann die Beanspruchungstemperatur der mit einer Schutz¬ schicht behandelten Wände im Bereich zwischen 300 und 1800° C, vorzugsweise 600 und 1000° C liegen.Finally, the stress temperature of the walls treated with a protective layer can be in the range between 300 and 1800 ° C., preferably 600 and 1000 ° C.
In der beigefügten Figur wird in einem Spannungs-Temperaturdiagramm beispielhaft das Spannungsverhalten in der Übergangszone des Grundwerkstoffes und der aufgebrachten Schutzschicht im Temperaturbereich zwischen 0 und etwa 1200° C dargestellt. Grundlage sind dabei die gemessenen, mittleren linearen Wärmeausdehnungs- koeffizienten der beiden Werkstoffpartner.In the attached figure, the voltage behavior in the transition zone of the base material and the applied protective layer in the temperature range between 0 and approximately 1200 ° C. is shown as an example in a voltage-temperature diagram. This is based on the measured, average linear thermal expansion coefficients of the two material partners.
Im nichtbeanspruchten Zustand der beschichteten Wandfläche eines Konverter-Abhitzekessels sind in der Übergangszone zwischen dem Grundwerkstoff und dem Beschichtungswerkstoff Zugspannungen oberhalb 600 N/mm2 vorhanden. Im Betriebszustand der beschichteten Abhitzekessel-Wandfläche wird die Spritzschicht plötzlich durch hohe Temperaturen der aus dem Konverter hochspritzenden Stahlschmelze und der heißen Schlacke beaufschlagt. In dem Diagramm ist der Vorgang durch den Spannungsverlauf dargestellt, indem bei ca. 700° C der neutrale Spannungsbereich durchlaufen wird und sich oberhalb 700° C in der Übergangszone Druckspannungen aufbauen, die ein Abplatzen der Schicht oder die Rißbildung in der Schicht verhindern. Durch die üblicherweise wassergekühlten Rohre der Abhitzekesselwände baut sich nach der Beanspruchung langsam der Zugspannungszustand wieder auf, d.h. in dem Diagramm wird die eingezeichnete Linie des Spannungsverlaufes in umgekehrter Richtung durchfahren. In der Figur ist lediglich ein bei¬ spielhafter Spannungsverlauf abhängig von der Temperatur dargestellt. Für andere Beanspruchungsbereiche kann naturgemäß auch der sogenannte 0-Zustand statt bei 700° C auch bei 400° oder bei 800° C liegen. When the coated wall surface of a converter waste heat boiler is not under stress, tensile stresses above 600 N / mm 2 are present in the transition zone between the base material and the coating material. In the operating state of the coated waste heat boiler wall surface, the spray layer is suddenly exposed to high temperatures of the molten steel spraying up from the converter and the hot slag. The diagram shows the process by means of the stress curve, in which the neutral stress range is run through at approx. 700 ° C and compressive stresses build up above 700 ° C in the transition zone, which prevent the layer from flaking off or cracking in the layer. Due to the usually water-cooled pipes of the waste heat boiler walls, the tensile state slowly builds up again after the stress, ie in the diagram, the drawn line of the stress curve is traversed in the opposite direction. In the figure, only an exemplary voltage curve depending on the temperature is shown. For other stress ranges, the so-called 0 state can naturally also be 400 ° or 800 ° C instead of 700 ° C.

Claims

Patentansprüche: Claims:
1. Verfahren zur Herstellung einer Schutzschicht auf mit heißen Gasen, insbesondere Rauchgasen beaufschlagten und in einem vorgegebenen Temperaturbereich beanspruchten, metallischen und aus einem vorgegebenen Grundwerkstoff bestehenden Wänden von1. Process for the production of a protective layer on metallic walls, which are exposed to hot gases, in particular flue gases, and which are subjected to stress in a predetermined temperature range
Verbrennungsanlagen, Wärmetauschern oder ähnlichen Anlagen, bei dem mit Hilfe des Plasmaspritzverfahrens auf die zuvor gereinigten, metallischen Wände zur Bildung der Schutzschicht ein Pulver aus metallischen, karbidischen, oxidkeramischen oder silicidischen Werkstoffen oder Mischungen dieser Werkstoffe aufgetragen wird, dadurch gekennzeichnet, daß a) die Oberfläche der Wände aufgerauht wird, b) der Grundwerkstoff der Wände aktiviert wird und c) unmittelbar anschließend bei Raumtemperatur und unter atmospährischen Bedingungen nach dem Plasmasp tzver fahren das Pulver aufgetragen wird, wobei d) die Zusammensetzung des Pulvers zuvor so gewählt wird,daß.die mit Hilfe der Wärmeausdehnungskoeffizienten von Grundwerkstoff und von aus verschiedenen Pulvern hergestellten Probewerkstücken für den Übergangsbereich zwischen Grundwerkstoff und aufgetragener Schicht ermittelte Spannung als Funktion der Temperatur im nichtbeanspruchten Zustand (bei Raumtemperatur) Zugspannungen zwischen 50 und 800 N/mm2, vorzugsweise zwischen 500 und 800 Nmm2, ergibt, die in dem vorgesehenen beanspruchten Temperaturbereich im wesentlichen auf 0 abgebaut ist oder geringe Druckspannungen aufweist.Incineration plants, heat exchangers or similar plants, in which, with the help of the plasma spraying process, a powder of metallic, carbide, oxide-ceramic or silicide materials or mixtures of these materials is applied to the previously cleaned, metallic walls to form the protective layer, characterized in that a) the surface the walls are roughened, b) the base material of the walls is activated and c) the powder is applied immediately afterwards at room temperature and under atmospheric conditions after the plasma spraying process, d) the composition of the powder being selected beforehand in such a way that With the help of the thermal expansion coefficients of the base material and of test workpieces made from different powders for the transition area between the base material and the applied layer, stress determined as a function of the temperature in the non-stressed state (at room temperature) between the tensile stresses en 50 and 800 N / mm 2 , preferably between 500 and 800 Nmm 2 , results, which in the intended temperature range is substantially reduced to 0 or has low compressive stresses.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß die aufgetragene Schutzschicht eine Enddicke von 0,1 bis 0,5 mm, vorzugsweise 0,15 bis 0,25 mm besitzt. 2. The method according to claim 1, characterized in that the applied protective layer has a final thickness of 0.1 to 0.5 mm, preferably 0.15 to 0.25 mm.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Schutzschicht mit einer 80 KW-Plasmaspritzanlage mit Innenpulverzuführung aufgetragen wird.3. The method according to claim 1 or 2, characterized in that the protective layer is applied with an 80 KW plasma spraying system with internal powder supply.
4. Verfahren nach mindestens einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß Pulver mit einer Korngröße von weniger als 75 μm, vorzugsweise 20 bis 40 μm zum Auftragen der Schutzschicht verwendet wird.4. The method according to at least one of claims 1 to 3, characterized in that powder with a grain size of less than 75 microns, preferably 20 to 40 microns is used to apply the protective layer.
5. Verfahren nach mindestens einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Schutzschicht in mindestens zwei Übergängen hergestellt wird.5. The method according to at least one of claims 1 to 4, characterized in that the protective layer is produced in at least two transitions.
6. Verfahren nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Oberfläche der Wände vor dem Plasmaspritzen mit Edelkorund, vorzugsweise hochreinem Edelkorund aufgerauht und aktiviert wird.6. The method according to at least one of the preceding claims, characterized in that the surface of the walls is roughened and activated before the plasma spraying with high-grade corundum, preferably high-purity high-grade corundum.
7. Verfahren nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Oberfläche der Wände durch den Plasmastrahl mit den darin aufgeschmolzenen Pulverpartikeln nur bis auf ca. 45° C, maximal 60° C erwärmt wird.7. The method according to at least one of the preceding claims, characterized in that the surface of the walls is heated by the plasma jet with the powder particles melted therein only up to approximately 45 ° C, maximum 60 ° C.
8. Verfahren nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß ein eine Ni-Legierung enthaltendes8. The method according to at least one of the preceding claims, characterized in that a containing a Ni alloy
Pulver verwendet wird.Powder is used.
9. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß die atmosphärische Plasmabeschichtung spätestens 45 Min., vorzugsweise spätestens 30 Min. nach der Aktivierung der Ober fläche der Wände durchgeführt wird.9. The method according to claim 1, characterized in that the atmospheric plasma coating is carried out at the latest 45 minutes, preferably at the latest 30 minutes after the activation of the upper surface of the walls.
10. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß die Beanspruchungstemperaturen der Wände im Bereich von 300 bis 1800° C, vorzugsweise 600 bis 1000° C liegen. 10. The method according to claim 1, characterized in that the stress temperatures of the walls are in the range of 300 to 1800 ° C, preferably 600 to 1000 ° C.
EP93912953A 1992-06-19 1993-06-11 Process for producing a protective coating on metal walls subject to attack by hot gases, especially flue gases Expired - Lifetime EP0672197B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4220063 1992-06-19
DE4220063A DE4220063C1 (en) 1992-06-19 1992-06-19 Process for producing a protective layer on metallic walls exposed to hot gases, in particular flue gases
PCT/EP1993/001483 WO1994000616A1 (en) 1992-06-19 1993-06-11 Process for producing a protective coating on metal walls subject to attack by hot gases, especially flue gases

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EP0672197A1 true EP0672197A1 (en) 1995-09-20
EP0672197B1 EP0672197B1 (en) 1999-03-31

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JP (1) JP3150697B2 (en)
KR (1) KR950701983A (en)
AT (1) ATE178364T1 (en)
AU (1) AU672009B2 (en)
BR (1) BR9306566A (en)
CA (1) CA2138255A1 (en)
CZ (1) CZ313794A3 (en)
DE (2) DE4220063C1 (en)
ES (1) ES2132237T3 (en)
PL (1) PL171965B1 (en)
RU (1) RU2107744C1 (en)
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EP0727504A3 (en) * 1995-02-14 1996-10-23 Gen Electric Plasma coating process for improved bonding of coatings on substrates
AT411625B (en) * 2000-04-28 2004-03-25 Vaillant Gmbh Heat exchanger, especially a coiled tube heat exchanger of a water heater, is coated using a plasma stream containing added silicon dioxide, aluminum oxide, silicon compound and-or titanium compound
CZ298780B6 (en) * 2003-12-23 2008-01-23 Koexpro Ostrava, A. S. Protective coating of tools and implements for preventing formation of mechanical incentive sparks
DE102007020420B4 (en) 2007-04-27 2011-02-24 Häuser & Co. GmbH Plasma spraying process for coating superheater pipes and using a metal alloy powder
DE102013010126B4 (en) 2013-06-18 2015-12-31 Häuser & Co. GmbH Plasmapulverspritzverfahren and apparatus for coating panels for boiler walls in conjunction with a laser beam device
CN108101062A (en) * 2018-01-17 2018-06-01 江苏中能硅业科技发展有限公司 A kind of preparation process of polycrystalline silicon reducing furnace and its furnace tube inner wall functional layer
JP7370794B2 (en) 2019-09-30 2023-10-30 セコム株式会社 security equipment
JP7370793B2 (en) 2019-09-30 2023-10-30 セコム株式会社 security equipment

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PL171965B1 (en) 1997-07-31
KR950701983A (en) 1995-05-17
WO1994000616A1 (en) 1994-01-06
CZ313794A3 (en) 1995-08-16
ES2132237T3 (en) 1999-08-16
ATE178364T1 (en) 1999-04-15
AU4325093A (en) 1994-01-24
BR9306566A (en) 1999-01-12
AU672009B2 (en) 1996-09-19
DE59309491D1 (en) 1999-05-06
DE4220063C1 (en) 1993-11-18
JP3150697B2 (en) 2001-03-26
JPH08501350A (en) 1996-02-13
RU2107744C1 (en) 1998-03-27
CA2138255A1 (en) 1994-01-06
EP0672197B1 (en) 1999-03-31
RU94046201A (en) 1996-10-20
SK156394A3 (en) 1997-02-05

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