EP0578605B1 - Fused-salt bath and process for electrolytic surface coating - Google Patents
Fused-salt bath and process for electrolytic surface coating Download PDFInfo
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- EP0578605B1 EP0578605B1 EP93610041A EP93610041A EP0578605B1 EP 0578605 B1 EP0578605 B1 EP 0578605B1 EP 93610041 A EP93610041 A EP 93610041A EP 93610041 A EP93610041 A EP 93610041A EP 0578605 B1 EP0578605 B1 EP 0578605B1
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/66—Electroplating: Baths therefor from melts
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- the invention relates to a weld pool of the type specified in the introduction to claim 1.
- Refractory metals are generally very resistant against corrosion in acidic and oxidizing media, e.g. Nb and Ta become only slightly to 200 ° C warm concentrated sulfuric acid and elemental chlorine attacked. They can also withstand high temperatures (Melting points> 2000 ° C) in a non-oxidizing atmosphere resist.
- Coatings made of high-melting metals can be precipitated electrolytically from molten salts containing chloride and fluoride.
- Such methods are described in the literature (GW Mellors and S. Senderoff, US Pat. 1969, No. 3,444,058, JE Perry, US Pat. 1968, No. 3,371,020, GP Capsimalis, ES Chen, RE Peterson and I. Ahmad, J Appl. Electrochem. 17 , 253 (1987), P. Los and J. Joslak, B. Electrochem. 5 , 829 (1989), P. Taxil and J. Mahenc, J. Appl. Electrochem.
- the baths for electrolytic surface coating described above have in common that they only contain fluoride and complex fluorides as anions and in some cases chlorides (VI Konstantinov, EG Plolyakov and PT Stangrit, Electrochemica Acta 26 , 445 (1981), AN Baimakov, SA Kuznetsov, EG Polyakov and PT Stangrit, Elektrokhim 21, 597 (1985)).
- chloride-containing baths have mostly resulted in dendritic precipitates or have caused the formation of lower, positive oxidation levels of the high-melting metals. So far, it has been assumed that even small amounts of oxide are detrimental to the precipitation quality when pure fluoride baths are used.
- the present invention is in the introduction of claim 1 specified type, and is characterized by the features specified in the characterizing part of claim 1.
- the previously known disadvantages are avoided, e.g. impure and disjointed surface layers, and plating with the metals mentioned can continuously with an economical and technical satisfactory result.
- the invention also relates to a method of Introduction of claim 4 specified type, which by the in characterizing part of claim 4 specified features is shaped.
- the molten salt baths according to the invention also include the fluoride anions also a substantial amount of oxide anions.
- Such composite baths can be used for electrolytic Plating of fine crystalline coherent and adhesive surface layers made of high-melting Metals are used.
- the content of the weld pool must contain metal ions of the high-melting metal to be precipitated between 1.0 and 8 atomic%, and the molar ratio between oxide and metal must be in the interval 0.1 to 1.5 lie to coherent surface layers of pure Metal at working temperatures between the melting point and reach about 900 ° C.
- the redox level of the weld pool must be determined by adding a Redox agents are kept at a suitable value.
- the electrolytic precipitation must be in an inert, not oxidizing atmosphere from e.g. Argon, neon, dry Nitrogen or under vacuum.
- the bath composition according to the invention is not more corrosive, so that containers and the like from any Material that is not essential can be used the melt reacts, e.g. vitreous carbon, Graphite, stabilizing zirconium oxides, nickel and nickel-containing Materials, sialons and aluminum nitride.
- any Material that is not essential can be used the melt reacts, e.g. vitreous carbon, Graphite, stabilizing zirconium oxides, nickel and nickel-containing Materials, sialons and aluminum nitride.
- the cathode on which the metal is precipitated must be off an electrically conductive, solid material that does not react too much with the molten electrolyte.
- This can be steel, alloy steel, graphite, nickel, nickel-containing Alloys or copper.
- the anode can consist of the metal to be precipitated, e.g. in the form of bars, metal foil or plates in various geometrical designs.
- the anode serves thus as a source for the metal to be precipitated, and holds also the oxidation level of the high-melting metal in the melt in the desired area.
- the electrolyte bath can also be used as a metal source will.
- an inert anode can, for example Graphite, glassy carbon or platinum be used.
- metal ions to the melt be so that the concentration of the metal to be precipitated is kept within the desired interval.
- a reducing agent must also be added, e.g. the relevant high-melting metal, so the oxidation level becomes correct.
- the bath composition according to the invention is based that alkali fluoride melt mixtures with the addition of Niobium / tantalum fluorides, niobium / tantalum oxides, niobium / tantalum Oxofluorides or mixtures thereof are used as the electrolyte be sufficient, as well as oxide in order to the Metal / oxide ratio in the desired interval hold.
- the preferred base melt is eutectic mixture of LiF-NaF-KF. This mix will Niobium / tantalum in the form of fluorides, oxofluorides, complex Fluorides / oxofluorides or oxides added. To get the correct one The oxide content of the melt will reach this possibly with admixed oxides of the 1st or 2nd main group, and / or oxides or oxofluorides of the precipitated Metal adjusted. These components make up that Electrolytic bath.
- Niobium was plated from a melt containing 2.7 mol% niobium and 2.7 mol% oxide with eutectic LiF-NaF-KF as the base melt onto a rod made of low-carbon steel. Niobium was added as K 2 NbF 7 and the oxide as Na 2 O.
- the anode consisted of a 1 mm thick niobium plate. Process temperature 700 ° C, current density (cathodic) 77 mA / cm 2 . Before the electrolysis, the niobium anode was immersed in the electrolyte bath for 3 hours. The cathodic current efficiency was 95%. The precipitated surface layer was crystalline, coherent and adhered well to the low carbon steel substrate. EDX analyzes showed that the layer consisted of 100% niobium.
- Niobium was processed under the same process conditions as in Example 1 plated on carbon steel.
- the melt electrolyte was a eutectic mixture of LiF-NaF-KF with a niobium content of 3.2 mol% and an oxide content of 3.2 mole%.
- the precipitated surface layer consisted of pure niobium (EDX analysis), was fine crystalline, coherent and adhered well to the substrate. The cathodic current efficiency was 77%.
- Niobium was precipitated on carbon steel under the same process conditions as in Example 1.
- the melt electrolyte was a eutectic mixture of LiF-NaF-KF with added oxide-containing NbF 5 .
- the contents of niobium and oxide were 2.7 and about 3.2 mol%, respectively.
- the precipitated layer was coherent, fine crystalline and adhered well to the steel base.
- EDX analysis showed that the surface layer was 100% niobium.
- the cathodic current efficiency was 56%.
- Tantalum was precipitated from a base melt of eutectic LiF-NaF-KF with added K 2 TaF 7 and Na 2 O on carbon steel.
- the mol% of tantalum and oxide were 2.7 and about 2.0, respectively.
- a cylinder made of 1 mm thick tantalum foil was used as the anode.
- the anode was immersed for 3 hours before electrolysis.
- the process temperature was 700 ° C.
- the precipitated surface layer consisted of pure tantalum metal, was coherent, fine-crystalline and adhered well to the base of low-carbon steel.
- the cathodic current efficiency was 78%.
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Abstract
Description
Die Erfindung betrifft ein Schmelzbad der in Einleitung des Anspruchs 1 angegebenen Art.The invention relates to a weld pool of the type specified in the introduction to claim 1.
Hochschmelzende Metalle (Niob, Tantal, Zirkon, Molybdän, Wolfram u.s.w.) sind im allgemeinen sehr widerstandsfähig gegenüber Korrosion in sauren und oxidierenden Medien, z.B. werden Nb und Ta nur in geringem Maße von 200° C warmer konzentrierter Schwefelsäure und elementärem Chlor angegriffen. Außerdem können sie hohen Temperaturen (Schmelzpunkte > 2000°C) in nicht oxidierender Atmosphäre widerstehen.Refractory metals (niobium, tantalum, zircon, molybdenum, Tungsten, etc.) are generally very resistant against corrosion in acidic and oxidizing media, e.g. Nb and Ta become only slightly to 200 ° C warm concentrated sulfuric acid and elemental chlorine attacked. They can also withstand high temperatures (Melting points> 2000 ° C) in a non-oxidizing atmosphere resist.
Die Verwendungsmöglichkeiten für Beschichtungen aus Niob- und Tantalmetall als Korrosionsschutz für besonders beanspruchte Teile in Ventilen, Durchflußmessern, Pumpen und ähnlichem sind in der chemischen Industrie und anderen Industrien zahlreich, weil hier große Forderungen an die Korrosionsfestigkeit gestellt werden.The possible uses for coatings made of niobium and tantalum metal as corrosion protection for particularly stressed Parts in valves, flow meters, pumps and Similar are in the chemical industry and other industries numerous, because here great demands on the Corrosion resistance can be provided.
Beschichtungen aus hochschmelzenden Metallen können elektrolytisch aus chlorid- und fluoridhaltigen Salzschmelzen ausgefällt werden. In der Literatur sind derartige Verfahren beschrieben (G.W. Mellors und S. Senderoff, US Pat. 1969, No. 3,444,058, J.E. Perry, US Pat. 1968, No. 3,371,020, G.P. Capsimalis, E.S. Chen, R.E. Peterson and I. Ahmad, J. Appl. Electrochem. 17, 253 (1987), P. Los and J. Joslak, B. Electrochem. 5, 829 (1989), P. Taxil and J. Mahenc, J. Appl. Electrochem. 17, 261 (1987)), aber es hat sich in der Praxis als sehr schwierig erwiesen, technisch und wirtschaftlich zufriedenstellende Ergebnisse zu erreichen, insbesonder bezüglich Niobbeschichtungen. Es ist unter anderem schwierig, Ausfällungen zu vermeiden, die Alkalimetalle, Oxide und komplexe Oxosalze der hochschmelzenden Metalle beinhalten.Coatings made of high-melting metals can be precipitated electrolytically from molten salts containing chloride and fluoride. Such methods are described in the literature (GW Mellors and S. Senderoff, US Pat. 1969, No. 3,444,058, JE Perry, US Pat. 1968, No. 3,371,020, GP Capsimalis, ES Chen, RE Peterson and I. Ahmad, J Appl. Electrochem. 17 , 253 (1987), P. Los and J. Joslak, B. Electrochem. 5 , 829 (1989), P. Taxil and J. Mahenc, J. Appl. Electrochem. 17, 261 (1987 )), but in practice it has proven to be very difficult to achieve technically and economically satisfactory results, especially with regard to niobium coatings. Among other things, it is difficult to avoid precipitates that include alkali metals, oxides and complex oxo salts of the refractory metals.
Den oben beschriebenen Bädern für elektrolytische Oberflächenbeschichtung ist gemeinsam, daß sie als Anionen nur Fluorid und komplexe Fluoride und in einzelnen Fällen Chloride enthalten (V.I. Konstantinov, E.G. Plolyakov and P.T. Stangrit, Electrochemica Acta 26, 445 (1981), A.N. Baimakov, S.A. Kuznetsov, E.G. Polyakov and P.T. Stangrit, Elektrokhim 21, 597 (1985)). Chloridhaltige Bäder haben jedoch zumeist dendritische Ausfällungen ergeben, oder die Bildung von niedrigeren, positiven Oxidationsstufen der hochschmelzenden Metalle verursacht. Bisher hat man angenommen, daß sogar kleine Oxidmengen für die Ausfällqualität schädlich sind, wenn reine Fluoridbäder verwendet werden. In der Literatur sind allerdings Verfahren beschrieben, wo Niob aus gemischten Fluorid-Chlorid-Schmelzen mit Zusatz von K2NbF7 und Nb2O5 an der Kathode ausgefällt wird (V.I. Konstantinov, E.G. Polyakov and P.T. Stangrit, Electrochemica Acta 26, 445 (1981), A.N. Baimakov, S.A. Kuznetsov, E.G. Polyakov and P.T. Stangrit, Elektrokhim 21, 597 (1985)).The baths for electrolytic surface coating described above have in common that they only contain fluoride and complex fluorides as anions and in some cases chlorides (VI Konstantinov, EG Plolyakov and PT Stangrit, Electrochemica Acta 26 , 445 (1981), AN Baimakov, SA Kuznetsov, EG Polyakov and PT Stangrit, Elektrokhim 21, 597 (1985)). However, chloride-containing baths have mostly resulted in dendritic precipitates or have caused the formation of lower, positive oxidation levels of the high-melting metals. So far, it has been assumed that even small amounts of oxide are detrimental to the precipitation quality when pure fluoride baths are used. However, methods are described in the literature where niobium is precipitated from mixed fluoride-chloride melts with the addition of K 2 NbF 7 and Nb 2 O 5 at the cathode (VI Konstantinov, EG Polyakov and PT Stangrit, Electrochemica Acta 26, 445 ( 1981), AN Baimakov, SA Kuznetsov, EG Polyakov and PT Stangrit, Elektrokhim 21, 597 (1985)).
Aus der US-PS No. 1,815,054 ist ausserdem ein Verfahren bekannt, bei dem hochschmelzende Metalle, insbesondere Tantal, durch Elektrolyse von Schmelzbädern aus Alkalimetallhaliden (insbesondere Fluorid) mit Zusatz von Alkalimetall-hochschmelzendes Metall-halogenid Doppelsalzen und einem ionisierbaren Sauerstoffhaltigen Salz des hochschmelzenden Metalls hergestellt werden können. Bei diesem Verfahren erhält man das hochschmelzende Metall in Pulverform und nicht als eine zusammenhängende Oberflächenschicht auf der Kathode. Es wird keine Reduktion des Schmelzbads verwendet, und die Sauerstoffhaltige Verbindung wird an der Anode zersetzt.From US-PS No. 1,815,054 is also a procedure known, in which high-melting metals, in particular Tantalum, by electrolysis of molten baths from alkali metal halides (especially fluoride) with the addition of alkali metal high-melting Metal halide double salts and an ionizable oxygen-containing salt of the high-melting Metal can be manufactured. With this The process gives the high-melting metal in powder form and not as a coherent surface layer on the cathode. There will be no reduction in the Melting pool used, and the oxygenated compound is decomposed at the anode.
Die vorliegende Erfindung ist von der in der Einleitung des Anspruchs 1 angebenen Art, und ist geprägt durch die im kennzeichnenden Teil des Anspruch 1 angegebenen Merkmale. Bei der erfindungsgemässen Verwendung von Salzschmelzbädern werden die bisher bekannten Nachteile vermieden, z.B. unreine und unzusammenhängende Oberflächenschichten, und die Plattierung mit den genannten Metallen kann kontinuierlich mit einem wirtschaftlich und technisch zufriedenstellendem Ergebnis ausgeführt werden.The present invention is in the introduction of claim 1 specified type, and is characterized by the features specified in the characterizing part of claim 1. When using molten salt baths according to the invention the previously known disadvantages are avoided, e.g. impure and disjointed surface layers, and plating with the metals mentioned can continuously with an economical and technical satisfactory result.
Die Erfindung betrifft ebenfalls ein Verfahren der in der Einleitung des Anspruchs 4 angegeben Art, das durch die im kennzeichnenden Teil des Anspruchs 4 angegebenen Merkmale geprägt ist.The invention also relates to a method of Introduction of claim 4 specified type, which by the in characterizing part of claim 4 specified features is shaped.
Die erfindungsgemässen Salzschmelzbäder beinhalten außer den Fluoridanionen auch eine wesentliche Menge Oxidanionen. Derart zusammengesetzte Bäder können für die elektrolytische Plattierung von feinkristallinen kohärenten und haftenden Oberflächenschichten aus hochschmelzenden Metallen verwendet werden.The molten salt baths according to the invention also include the fluoride anions also a substantial amount of oxide anions. Such composite baths can be used for electrolytic Plating of fine crystalline coherent and adhesive surface layers made of high-melting Metals are used.
Plattierungen mit hochschmelzenden Metallen aus Fluoridbädern mit Zusatz von Oxidanionen sind bisher nicht bekannt gewesen, und die Verwendung dieser Bäder hat wie erwähnt große Vorteile sowohl technischer als auch wirtschaftlicher Art. Dies ist mittels Untersuchung der Stromausbeute sowie durch Elektronmikroskopie und EDX-Analysen (Energiedispersive Röntgenspektroskopie) des ausgefällten Metalls nachgewiesen.High melting metals from fluoride baths with the addition of oxide anions are not yet known has been, and the use of these baths has been mentioned great advantages both technically and economically Art. This is by examining the electricity yield as well as by electron microscopy and EDX analysis (energy dispersive X-ray spectroscopy) of the precipitated metal detected.
Bei Plattierung muß der Inhalt des Schmelzbads an Metallionen des auszufällenden hochschmelzenden Metalls zwischen 1,0 und 8 Atom % liegen, und das Molverhältnis zwischen Oxid und Metall muß im Intervall 0,1 bis 1,5 liegen, um kohärente Oberflächenschichten aus reinem Metall bei Arbeitstemperaturen zwischen dem Schmelzpunkt und etwa 900°C zu erreichen.When plating, the content of the weld pool must contain metal ions of the high-melting metal to be precipitated between 1.0 and 8 atomic%, and the molar ratio between oxide and metal must be in the interval 0.1 to 1.5 lie to coherent surface layers of pure Metal at working temperatures between the melting point and reach about 900 ° C.
Das Redoxniveau des Schmelzbads muß durch Zugabe eines Redoxmittels auf einem passenden Wert gehalten werden. The redox level of the weld pool must be determined by adding a Redox agents are kept at a suitable value.
Dies kann das hochschmelzende Metall in Metallform oder eine Verbindung mit der gleichen Wirkung sein.This can be the high melting metal or metal be a connection with the same effect.
Die elektrolytische Ausfällung muß in einer inerten, nicht oxidierenden Atmosphäre aus z.B. Argon, Neon, trockenem Stickstoff oder unter Vakuum erfolgen.The electrolytic precipitation must be in an inert, not oxidizing atmosphere from e.g. Argon, neon, dry Nitrogen or under vacuum.
Die erfindungsgemäße Badzusammensetzung ist nicht korrosiver, so daß Behälter und ähnliches aus irgendwelchem Material verwendet werden können, das nicht wesentlich mit der Schmelze reagiert, z.B. glasartiger Kohlenstoff, Graphit, stabilisierende Zirkonoxide, Nickel und nickelhaltige Materialien, Sialone und Aluminiumnitrid.The bath composition according to the invention is not more corrosive, so that containers and the like from any Material that is not essential can be used the melt reacts, e.g. vitreous carbon, Graphite, stabilizing zirconium oxides, nickel and nickel-containing Materials, sialons and aluminum nitride.
Die Kathode, auf der das Metall ausgefällt wird, muß aus einem elektrisch leitenden, festen Material bestehen, das nicht in zu hohem Maße mit dem Schmelzelektrolyt reagiert. Dies kann Stahl, legierter Stahl, Graphit, Nickel, nickelhaltige Legierungen oder Kupfer sein.The cathode on which the metal is precipitated must be off an electrically conductive, solid material that does not react too much with the molten electrolyte. This can be steel, alloy steel, graphite, nickel, nickel-containing Alloys or copper.
Die Anode kann aus dem auszufällenden Metall bestehen, z.B. in Form von Stangen, Metallfolie oder Platten in verschiedenen geometrischen Ausbildungen. Die Anode dient somit als Quelle für das auszufällende Metall, und hält außerdem die Oxidationsstufe des hochschmelzenden Metalls im Schmelzbad im gewünschten Bereich fest.The anode can consist of the metal to be precipitated, e.g. in the form of bars, metal foil or plates in various geometrical designs. The anode serves thus as a source for the metal to be precipitated, and holds also the oxidation level of the high-melting metal in the melt in the desired area.
Das Elektrolytbad kann auch als Metallquelle verwendet werden. In diesem Fall kann eine inerte Anode aus beispielsweise Graphit, glasartigem Kohlenstoff oder Platin verwendet werden. Bei Verwendung des Elektolytbads als Metallquelle müssen der Schmelze Metallionen zugesetzt werden, so daß die Konzentration des auszufällenden Metalls innerhalb des gewünschten Intervalls gehalten wird. Außerdem muß ein Reduktionsmittel zugeführt werden, z.B. das betreffende hochschmelzende Metall, damit die Oxidationsstufe korrekt wird.The electrolyte bath can also be used as a metal source will. In this case, an inert anode can, for example Graphite, glassy carbon or platinum be used. When using the electrolyte bath as Metal source must add metal ions to the melt be so that the concentration of the metal to be precipitated is kept within the desired interval. A reducing agent must also be added, e.g. the relevant high-melting metal, so the oxidation level becomes correct.
Die erfindungsgemäße Badzusammensetzung basiert darauf, daß Alkalifluorid-Schmelzmischungen mit Zusatz von Niob/Tantal-Fluoriden, Niob/Tantal-Oxiden, Niob/Tantal Oxofluoriden oder Mischungen hiervon als Elektrolyt verwendet werden, sowie Oxid in ausreichender Menge, um das Metall/Oxid Verhältnis in dem gewünschten Intervall zu halten.The bath composition according to the invention is based that alkali fluoride melt mixtures with the addition of Niobium / tantalum fluorides, niobium / tantalum oxides, niobium / tantalum Oxofluorides or mixtures thereof are used as the electrolyte be sufficient, as well as oxide in order to the Metal / oxide ratio in the desired interval hold.
Die bevorzugte Grundschmelze (Lösungsmittel) ist die eutektische Mischung aus LiF-NaF-KF. Dieser Mischung wird Niob/Tantal in Form von Fluoriden, Oxofluoriden, komplexen Fluoriden/Oxofluoriden oder Oxiden zugesetzt. Um den korrekten Oxidinhalt der Schmelze zu erreichen, wird diese eventuell mit beigemischten Oxiden der 1. oder 2. Hauptgruppe, und/oder Oxiden oder Oxofluoriden des auszufällenden Metalls justiert. Diese Bestandteile bilden das Elektrolytbad.The preferred base melt (solvent) is eutectic mixture of LiF-NaF-KF. This mix will Niobium / tantalum in the form of fluorides, oxofluorides, complex Fluorides / oxofluorides or oxides added. To get the correct one The oxide content of the melt will reach this possibly with admixed oxides of the 1st or 2nd main group, and / or oxides or oxofluorides of the precipitated Metal adjusted. These components make up that Electrolytic bath.
Niob wurde aus einer Schmelze mit dem Inhalt 2,7 Mol % Niob und 2,7 Mol % Oxid mit eutektischem LiF-NaF-KF als Grundschmelze auf eine Stange aus niedriggekohltem Stahl plattiert. Niob wurde als K2NbF7 und das Oxid als Na2O zugesetzt. Die Anode bestand aus einer 1 mm dicken Niob-platte. Prozeßtemperatur 700°C, Stromdichte (kathodisch) 77 mA/cm2. Vor der Elektrolyse war die Niob-Anode 3 Stunden lang in das Elektrolytbad eingetaucht. Die kathodische Stromausbeute war 95%. Die ausgefällte Oberflächenschicht war kristallin, kohärent und haftete gut am Substrat aus niedriggekohltem Stahl. EDX-Analysen zeigten, daß die Schicht aus 100% Niob bestand.Niobium was plated from a melt containing 2.7 mol% niobium and 2.7 mol% oxide with eutectic LiF-NaF-KF as the base melt onto a rod made of low-carbon steel. Niobium was added as K 2 NbF 7 and the oxide as Na 2 O. The anode consisted of a 1 mm thick niobium plate. Process temperature 700 ° C, current density (cathodic) 77 mA / cm 2 . Before the electrolysis, the niobium anode was immersed in the electrolyte bath for 3 hours. The cathodic current efficiency was 95%. The precipitated surface layer was crystalline, coherent and adhered well to the low carbon steel substrate. EDX analyzes showed that the layer consisted of 100% niobium.
Niob wurde unter den gleichen Prozeßbedingungen wie in Beispiel 1 auf Kohlenstoffstahl plattiert. Der Schmelzelektrolyt war eine eutektische Mischung aus LiF-NaF-KF mit einem Niobinhalt von 3,2 Mol % und einem Oxidinhalt von 3,2 Mol%. Die ausgefällte Oberflächenschicht bestand aus reinem Niob (EDX-Analyse), war feinkristallin, kohärent und haftete gut am Substrat. Die kathodische Stromausbeute war 77%.Niobium was processed under the same process conditions as in Example 1 plated on carbon steel. The melt electrolyte was a eutectic mixture of LiF-NaF-KF with a niobium content of 3.2 mol% and an oxide content of 3.2 mole%. The precipitated surface layer consisted of pure niobium (EDX analysis), was fine crystalline, coherent and adhered well to the substrate. The cathodic current efficiency was 77%.
Niob wurde unter den gleichen Prozeßumständen wie in Beispiel 1 auf Kohlenstoffstahl ausgefällt. Der Schmelzelektrolyt war eine eutektische Mischung aus LiF-NaF-KF mit beigefügtem oxidhaltigem NbF5. Der Inhalt von Niob und Oxid, war jeweils 2,7 und etwa 3,2 Mol %. Die ausgefällte Schicht war kohärent, feinkristallin und haftete gut an der Unterlage aus Stahl. EDX-Anlalysen zeigten, daß die Oberflächenschicht 100% Niob war. Die kathodische Stromausbeute war 56%.Niobium was precipitated on carbon steel under the same process conditions as in Example 1. The melt electrolyte was a eutectic mixture of LiF-NaF-KF with added oxide-containing NbF 5 . The contents of niobium and oxide were 2.7 and about 3.2 mol%, respectively. The precipitated layer was coherent, fine crystalline and adhered well to the steel base. EDX analysis showed that the surface layer was 100% niobium. The cathodic current efficiency was 56%.
Tantal wurde aus einer Grundschmelze aus eutektischem LiF-NaF-KF mit zugesetztem K2TaF7 und Na2O auf Kohlenstoffstahl ausgefällt. Der Mol % von Tantal und Oxid, war jeweils 2,7 und etwa 2,0. Als Anode wurde ein Zylinder aus 1 mm dicker Tantalfolie verwendet. Vor der Elektrolyse war die Anode 3 Stunden lang eingetaucht. Die Prozeßtemperatur war 700°C. Die ausgefällte Oberflächenschicht bestand aus reinem Tantalmetall, war kohärent, feinkristallin und haftede gut an der Unterlage aus niedriggekohltem Stahl. Die kathodische Stromausbeute war 78%.Tantalum was precipitated from a base melt of eutectic LiF-NaF-KF with added K 2 TaF 7 and Na 2 O on carbon steel. The mol% of tantalum and oxide were 2.7 and about 2.0, respectively. A cylinder made of 1 mm thick tantalum foil was used as the anode. The anode was immersed for 3 hours before electrolysis. The process temperature was 700 ° C. The precipitated surface layer consisted of pure tantalum metal, was coherent, fine-crystalline and adhered well to the base of low-carbon steel. The cathodic current efficiency was 78%.
Claims (4)
- Melt bath for electrolytic surface-coating with one of the high melting point metals Nb, Ta, W or Mo, especially niobium or tantalum, based on a salt melt of alkali metal fluorides and a fluoride of the high melting point metal,
characterized in thatthe content, in the bath, of metal ions of the high melting point metal is from 1 to 8 atom %;the bath comprises oxide anions andis in contact with the high melting point metal in metallic form orcomprises an appropriate redox agent; andthe molar ratio of oxide anions to metal ions of the high melting point metal is in the range 0.1 to 1.5. - Bath according to claim 1, characterized in that the oxide anions are added in the form of an alkali metal oxide or an oxide, oxofluoride or complex oxofluoride of the high melting point metal.
- Bath according to claim 1-2, characterized in that the metal ions of the high melting point metal are added in the form of a fluoride, a chloride, a complex fluoride, a complex chloride, an oxide, an oxofluoride or a complex oxofluoride of the high melting point metal.
- Process for electrolytic surface-coating with one of the high melting point metals Nb, Ta, W or Mo, especially niobium and tantalum, in an inert, non-oxidising atmosphere or in vacuo, characterized in that a bath having a composition according to any one of claims 1 to 3 is used for the electrolysis.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DK897/92 | 1992-07-08 | ||
| DK89792 | 1992-07-08 | ||
| DK089792A DK169354B1 (en) | 1992-07-08 | 1992-07-08 | Melting bath and method for electrolytic surface coating with refractory metals from fluoride-containing salt melts |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0578605A1 EP0578605A1 (en) | 1994-01-12 |
| EP0578605B1 true EP0578605B1 (en) | 1998-03-04 |
Family
ID=8098774
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP93610041A Expired - Lifetime EP0578605B1 (en) | 1992-07-08 | 1993-07-02 | Fused-salt bath and process for electrolytic surface coating |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0578605B1 (en) |
| AT (1) | ATE163691T1 (en) |
| DE (1) | DE59308195D1 (en) |
| DK (1) | DK169354B1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DK174876B1 (en) | 2001-02-26 | 2004-01-12 | Danfoss As | Implant and implant surface modification process |
| DE112005002435B4 (en) * | 2004-10-01 | 2014-01-02 | Kyoto University | Molten salt bath, deposit obtained using the molten salt bath, production process for a metal product and metal product |
| GB201117335D0 (en) * | 2011-10-07 | 2011-11-23 | Element Six Abrasives Sa | Method of processing a composite body |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2905599A (en) * | 1956-02-15 | 1959-09-22 | Jerome J Wick | Electrolytic cladding of zirconium on uranium |
-
1992
- 1992-07-08 DK DK089792A patent/DK169354B1/en not_active IP Right Cessation
-
1993
- 1993-07-02 DE DE59308195T patent/DE59308195D1/en not_active Expired - Lifetime
- 1993-07-02 AT AT93610041T patent/ATE163691T1/en active
- 1993-07-02 EP EP93610041A patent/EP0578605B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE59308195D1 (en) | 1998-04-09 |
| ATE163691T1 (en) | 1998-03-15 |
| DK169354B1 (en) | 1994-10-10 |
| DK89792D0 (en) | 1992-07-08 |
| DK89792A (en) | 1994-01-09 |
| EP0578605A1 (en) | 1994-01-12 |
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