EP0388816B1 - Passivation of pyrophoric metals - Google Patents

Passivation of pyrophoric metals Download PDF

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Publication number
EP0388816B1
EP0388816B1 EP90105021A EP90105021A EP0388816B1 EP 0388816 B1 EP0388816 B1 EP 0388816B1 EP 90105021 A EP90105021 A EP 90105021A EP 90105021 A EP90105021 A EP 90105021A EP 0388816 B1 EP0388816 B1 EP 0388816B1
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EP
European Patent Office
Prior art keywords
guanidine
metal
process according
agent
weight
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EP90105021A
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German (de)
French (fr)
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EP0388816A1 (en
Inventor
Helmut Dr. Lischka
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Skw Stahl-Technik degussa AG GmbH
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SKW Trostberg AG
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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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
    • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
    • C23F11/14—Nitrogen-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C21C1/025—Agents used for dephosphorising or desulfurising
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/10—Making spheroidal graphite cast-iron
    • C21C1/105—Nodularising additive agents
    • 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
    • C23C24/00—Coating starting from inorganic powder
    • 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
    • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
    • 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
    • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
    • C23F11/14—Nitrogen-containing compounds
    • C23F11/146—Nitrogen-containing compounds containing a multiple nitrogen-to-carbon bond
    • 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
    • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
    • C23F11/14—Nitrogen-containing compounds
    • C23F11/149—Heterocyclic compounds containing nitrogen as hetero atom

Definitions

  • the present invention relates to a process for the passivation of pyrophoric metals, in particular magnesium.
  • pyrophoric metals such as magnesium, calcium or the alloys of these metals pose particular problems in handling, especially when these pyrophoric substances are used in finely divided form.
  • magnesium powder which is blown into liquid pig iron alone or in combination with calcium carbide or lime for the purpose of desulphurization with the help of a refractory immersion lance, cannot be used easily due to the easy flammability and the severity of the fire behavior. Rather, it must first be passivated using suitable means or methods.
  • the invention is therefore based on the object of developing a method for passivating pyrophoric metals, in particular magnesium, by coating with a passivating agent which does not have the disadvantages of the prior art mentioned, but rather provides the pyrophoric metals with a coating without great technical outlay , which effectively suppresses the flammability of these metals and at the same time does not pose any environmental problems.
  • This object is achieved in that 0.5 to 5% by weight of an s-triazine and / or guanidine derivative, based on the weight of the metal to be passivated, is used as the passivating agent.
  • the pyrophoric metal which can be, in particular, magnesium, calcium or an alloy of these metals, is coated with a passivating agent based on s-triazine and / or guanidine derivatives.
  • a passivating agent based on s-triazine and / or guanidine derivatives.
  • the passivating agent is used in amounts of 0.5 to 5% by weight, preferably 1 to 3% by weight, based on the weight of the metal. In principle, it is possible to use larger quantities, but this excess quickly becomes uneconomical because it has no additional effect.
  • melamine is particularly preferred due to its low cost availability.
  • the s-triazine derivatives ammeline and ammelide and the guanamines benzoguanamine or acetoguanamine are also readily available and easy to use.
  • Compounds which have several s-triazine structural units can also be used for the purpose according to the invention. These include polymeric s-triazines and more highly condensed s-triazine compounds such as Melam, Melem or Melon.
  • condensation products of s-triazines for example melamine and / or benzoguanamine, condensation products with formaldehyde being preferred.
  • guanidines In principle, a large number of compounds from the group of guanidines can also be used, the unsubstituted free guanidine itself and also substituted guanidines, if appropriate in the form of salts, being suitable as guanidines.
  • guanidines will be used, which are relatively easy to manufacture and therefore inexpensive to obtain are.
  • the substituted guanidines this is especially the case with cyanoguanidine (dicyandiamide) and with guanylurea or with guanylurea phosphate, which is why these compounds are used with preference.
  • Simple guanidine salts can also be used, the anions of which do not contain any interfering components such as Contain chlorides.
  • Preferred are guanidine phosphates, guanidine sulfamates and guanidine cyanurates, which are also readily available.
  • a wetting agent which is preferably anhydrous and is used in an amount of 0.1 to 0.5% by weight, based on the weight of the metal .
  • the usual products can be used as water-free wetting agents, the use of highly viscous oils, in particular silicone and / or mineral oils, having proven particularly advantageous.
  • the production of the coatings on the pyrophoric metals can be carried out easily and in a technically simple manner.
  • the finely divided passivating agents e.g. in the form of powders, first optionally sprayed with the wetting agent in an inert gas atmosphere and then using customary methods, e.g. Mix, the passivating agent applied to the surface of the pyrophoric metals.
  • the passivating agents must be in the finest possible form to ensure complete coating and satisfactory adhesion.
  • the passivating agents are therefore preferably used with a particle size of ⁇ 50 ⁇ m, preferably ⁇ 10 ⁇ m.
  • the passivated metals produced by the process according to the invention are also notable for their high flammability and favorable fire behavior. They are therefore particularly suitable as treatment agents for metallurgical melts, preferably for the desulfurization of pig iron, especially since no undesired or disruptive decomposition products are formed during the thermal decomposition of the passivating agents.
  • Example 1 99 parts by weight of metallic magnesium powder (magnesium content 99.8%) with a grain size of 0.2-0.8 mm were coated with 1 part by weight of finely divided cyanoguanidine (particle size 98% ⁇ 10 ⁇ m).
  • Example 1 97 parts by weight of metallic magnesium powder (magnesium content 99.8%) with a grain size of 0.2-0.8 mm were passivated with 3 parts by weight of finely divided melamine (particle size 99% ⁇ 60 ⁇ m).
  • test substance is shaped in a commercial form into an approximately 250 mm long, 20 mm wide and 10 mm high continuous bed and placed on a cold impermeable surface with low thermal conductivity.
  • the fill is ignited at one end with the help of a Bunsen burner.
  • the observed burn-up time is a measure of the pyrophoric character of the test substance.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Fireproofing Substances (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Luminescent Compositions (AREA)
  • Paints Or Removers (AREA)
  • Powder Metallurgy (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
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  • Insulated Metal Substrates For Printed Circuits (AREA)
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Abstract

For the passivation of pyrophoric metals, in particular magnesium, the metal is coated with 0.5 to 5% by weight of an s-triazine derivative, such as melamine, benzoguanamine, melam, melem and/or melon, melamine- and/or benzoguanamine-formaldehyde condensates and/or guanidine, cyanoguanidine, guanylurea, guanidine phosphate, guanidine sulphamate or guanidine cyanurate, based on the weight of the metal, as a passivating agent. Metals passivated in this manner are suitable in particular as treatment agents for metallurgical melts.

Description

Gegenstand der vorliegenden Erfindung ist ein Verfahren zur Passivierung von pyrophoren Metallen, insbesondere Magnesium.The present invention relates to a process for the passivation of pyrophoric metals, in particular magnesium.

Es ist bekannt, daß pyrophore Metalle wie Magnesium, Calcium oder die Legierungen dieser Metalle besondere Probleme bei der Handhabung vor allem dann aufwerfen, wenn diese pyrophoren Stoffe in feinteiliger Form eingesetzt werden.It is known that pyrophoric metals such as magnesium, calcium or the alloys of these metals pose particular problems in handling, especially when these pyrophoric substances are used in finely divided form.

So kann beispielsweise Magnesiumpulver, welches allein oder in Kombination mit Calciumcarbid oder Kalk zum Zwecke der Entschwefelung mit Hilfe einer feuerfesten Tauchlanze in flüssiges Roheisen pneumatisch eingeblasen wird, aufgrund der leichten Entzündbarkeit und der Heftigkeit des Brandverhaltens nicht ohne weiteres verwendet werden. Es muß vielmehr erst durch geeignete Mittel bzw. Methoden passiviert werden.For example, magnesium powder, which is blown into liquid pig iron alone or in combination with calcium carbide or lime for the purpose of desulphurization with the help of a refractory immersion lance, cannot be used easily due to the easy flammability and the severity of the fire behavior. Rather, it must first be passivated using suitable means or methods.

Es sind bereits verschiedene Vorschläge zur Lösung dieses Problems bekannt geworden, die aber bisher alle nicht voll befriedigen können.Various proposals for solving this problem have already become known, but so far not all of them have been fully satisfactory.

So wird gemäß der US-PS 4209325 bzw. der US-PS 3998625 empfohlen, Magnesiumpulver mit inerten oxidischen Pulvern wie Kalk, Aluminiumoxid, SiO₂-Stäuben oder metallurgischen Schlacken zu verdünnen. Diese Metalloxide, die üblicherweise in Mengen von 10 bis 50 Gew.-% dem Magnesiummetallpulver zugemischt werden, nehmen nicht an der Entschwefelungsreaktion teil und verursachen deshalb nur einen schlechten Wirkungsgrad des Entschwefelungsmittels. Probleme ergeben sich auch aus dem Entmischungsverhalten der verschiedenen Gemischkomponenten.It is recommended according to US-PS 4209325 or US-PS 3998625 to dilute magnesium powder with inert oxidic powders such as lime, aluminum oxide, SiO₂ dust or metallurgical slags. These metal oxides, which are usually added to the magnesium metal powder in amounts of 10 to 50% by weight, do not participate in the desulfurization reaction and therefore only cause poor efficiency of the desulfurization agent. Problems also arise from the segregation behavior of the various mixture components.

Anstelle des Mischens mit einem inerten Metalloxid wurde deshalb auch schon die Beschichtung mit einem Metalloxid (ZrO₂, TiO₂ oder Al₂O₃) beschrieben. Das Problem der leichten Entzündbarkeit wird damit aber nur unzureichend gelöst.Instead of mixing with an inert metal oxide, the coating with a metal oxide (ZrO₂, TiO₂ or Al₂O₃) has therefore already been described. However, the problem of easy flammability is only inadequately solved.

Ferner ist es bekannt, pyrophores Magnesiumpulver mit einer Salzschicht zu beschichten, wobei als Salze vorwiegend Alkali- und/oder Erdalkalichloride beschrieben sind (US-Patentschriften 3881913, 4186000 sowie 4279641). Nachteilig bei diesen Lösungsvorschlägen sind die aufwendigen Herstellungsmethoden dieser Salzbeschichtungen (EP-A 58322 oder EP-A 108464) sowie der hygroskopische Charakter dieser Salze. Außerdem können beim metallurgischen Einsatz dieser beschichteten Magnesiumteilchen sehr leicht chlorhaltige Abgase entstehen, die besondere Maßnahmen für die Schonung der Umwelt erforderlich machen.It is also known to coat pyrophoric magnesium powder with a salt layer, the salts primarily being alkali and / or alkaline earth chlorides (US Pat. Nos. 3881913, 4186000 and 4279641). A disadvantage of these proposed solutions is the complex production methods of these salt coatings (EP-A 58322 or EP-A 108464) and the hygroscopic character of these salts. In addition, the metallurgical use of these coated magnesium particles can very easily produce chlorine-containing gases, which require special measures to protect the environment.

Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren zum Passivieren von pyrophoren Metallen, insbesondere Magnesium, durch Beschichtung mit einem Passivierungsmittel zu entwickeln, welches die genannten Nachteile des Standes der Technik nicht aufweist, sondern ohne großen technischen Aufwand die pyrophoren Metalle mit einer Beschichtung versieht, welche die leichte Entzündbarkeit dieser Metalle wirkungsvoll unterdrückt und gleichzeitig keine Umweltprobleme aufwirft.The invention is therefore based on the object of developing a method for passivating pyrophoric metals, in particular magnesium, by coating with a passivating agent which does not have the disadvantages of the prior art mentioned, but rather provides the pyrophoric metals with a coating without great technical outlay , which effectively suppresses the flammability of these metals and at the same time does not pose any environmental problems.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß man als Passivierungsmittel 0,5 bis 5 Gew.-% eines s-Triazin- oder/und Guanidin-Derivates, bezogen auf das Gewicht des zu passivierenden Metalles, einsetzt.This object is achieved in that 0.5 to 5% by weight of an s-triazine and / or guanidine derivative, based on the weight of the metal to be passivated, is used as the passivating agent.

Es hat sich überraschenderweise gezeigt, daß man erfindungsgemäß mit vergleichsweise geringen Mengen an Passivierungsmittel eine sehr starke Unterdrückung der Entzündbarkeit sowie eine positive Beeinflussung des Abbrandverhaltens erreichen kann.Surprisingly, it has been shown that, according to the invention, a comparatively small amount of passivating agent can be used to suppress the flammability very strongly and to have a positive influence on the combustion behavior.

Beim Verfahren der Erfindung wird das pyrophore Metall, welches insbesondere Magnesium, Calcium bzw. eine Legierung dieser Metalle sein kann, mit einem Passivierungsmittel auf Basis von s-Triazin- oder/und Guanidin-Derivaten beschichtet. Für den erfindungsgemäßen Zweck ist es völlig ausreichend, wenn das Passivierungsmittel in Mengen von 0,5 bis 5 Gew.-%, vorzugsweise 1 bis 3 Gew.-%, bezogen auf das Gewicht des Metalls, eingesetzt wird. Es ist grundsätzlich möglich, auch größere Mengen zu verwenden, doch wird dieser Überschuß sehr schnell unwirtschaftlich, weil damit kein zusätzlicher Effekt verbunden ist.In the process of the invention, the pyrophoric metal, which can be, in particular, magnesium, calcium or an alloy of these metals, is coated with a passivating agent based on s-triazine and / or guanidine derivatives. For the purpose according to the invention it is completely sufficient if the passivating agent is used in amounts of 0.5 to 5% by weight, preferably 1 to 3% by weight, based on the weight of the metal. In principle, it is possible to use larger quantities, but this excess quickly becomes uneconomical because it has no additional effect.

Als Passivierungsmittel kommen im Rahmen der Erfindung alle s-Triazin- oder/und Guanidin-Derivate in Frage.All s-triazine and / or guanidine derivatives are suitable as passivating agents in the context of the invention.

Unter den s-Triazin-Derivaten wird das Melamin aufgrund seiner kostengünstigen Verfügbarkeit besonders bevorzugt. Ebenfalls leicht verfügbar sowie problemlos einsetzbar und daher bevorzugt sind die s-Triazin-Derivate Ammelin und Ammelid und die Guanamine Benzoguanamin oder Acetoguanamin. Für den erfindungsgemäßen Zweck können auch Verbindungen verwendet werden, die mehrere s-Triazin-Struktureinheiten aufweisen. Hierzu gehören polymere s-Triazine und höher kondensierte s-Triazinverbindungen wie z.B. Melam, Melem oder Melon. Schließlich ist es auch möglich, Kondensationsprodukte von s-Triazinen beispielsweise des Melamins oder/und des Benzoguanamins einzusetzen, wobei Kondensationsprodukte mit Formaldehyd bevorzugt sind.Among the s-triazine derivatives, melamine is particularly preferred due to its low cost availability. The s-triazine derivatives ammeline and ammelide and the guanamines benzoguanamine or acetoguanamine are also readily available and easy to use. Compounds which have several s-triazine structural units can also be used for the purpose according to the invention. These include polymeric s-triazines and more highly condensed s-triazine compounds such as Melam, Melem or Melon. Finally, it is also possible to use condensation products of s-triazines, for example melamine and / or benzoguanamine, condensation products with formaldehyde being preferred.

Aus der Gruppe der Guanidine sind ebenfalls grundsätzlich eine Vielzahl von Verbindungen einsetzbar, wobei als Guanidine sowohl das unsubstituierte freie Guanidin selbst als auch substituierte Guanidine ggf. in Form von Salzen geeignet sind. In der Regel wird man auf Guanidine zurückgreifen, die relativ einfach herstellbar und somit kostengünstig erhältlich sind. Bei den substituierten Guanidinen ist dies vor allem beim Cyanoguanidin (Dicyandiamid) sowie beim Guanylharnstoff bzw. beim Guanylharnstoffphosphat der Fall, weshalb diese Verbindungen bevorzugt Verwendung finden.In principle, a large number of compounds from the group of guanidines can also be used, the unsubstituted free guanidine itself and also substituted guanidines, if appropriate in the form of salts, being suitable as guanidines. As a rule, guanidines will be used, which are relatively easy to manufacture and therefore inexpensive to obtain are. In the case of the substituted guanidines, this is especially the case with cyanoguanidine (dicyandiamide) and with guanylurea or with guanylurea phosphate, which is why these compounds are used with preference.

Daneben können auch einfache Guanidinsalze verwendet werden, deren Anionen keine störenden Bestandteile wie z.B. Chloride enthalten. Bevorzugt sind Guanidinphosphate, Guanidinsulfamate und Guanidincyanurate, die auch leicht verfügbar sind.Simple guanidine salts can also be used, the anions of which do not contain any interfering components such as Contain chlorides. Preferred are guanidine phosphates, guanidine sulfamates and guanidine cyanurates, which are also readily available.

Um eine gute Haftung des Passivierungsmittels auf dem pyrophoren Metall zu erzielen, setzt man zweckmäßig ein Benetzungsmittel zu, welches vorzugsweise wasserfrei ist und in einer Menge von 0,1 bis 0,5 Gew.-%, bezogen auf das Gewicht des Metalls, verwendet wird. Als wasserfreie Benetzungsmittel können die üblichen Produkte eingesetzt werden, wobei sich die Verwendung von hochviskosen Ölen, insbesondere Silicon- und/oder Mineralöle, als besonders vorteilhaft erwiesen hat.In order to achieve good adhesion of the passivating agent to the pyrophoric metal, it is expedient to add a wetting agent which is preferably anhydrous and is used in an amount of 0.1 to 0.5% by weight, based on the weight of the metal . The usual products can be used as water-free wetting agents, the use of highly viscous oils, in particular silicone and / or mineral oils, having proven particularly advantageous.

Die Herstellung der Überzüge auf den pyrophoren Metallen kann problemlos und in technisch einfacher Weise durchgeführt werden. Beispielsweise werden die feinteiligen Passivierungsmittel, z.B. in Form von Pulvern, zuerst ggf. in einer Inertgasatmosphäre mit dem Benetzungsmittel besprüht und anschließend wird mit üblichen Methoden, wie z.B. Mischen, das Passivierungsmittel auf die Oberfläche der pyrophoren Metalle aufgebracht.The production of the coatings on the pyrophoric metals can be carried out easily and in a technically simple manner. For example, the finely divided passivating agents, e.g. in the form of powders, first optionally sprayed with the wetting agent in an inert gas atmosphere and then using customary methods, e.g. Mix, the passivating agent applied to the surface of the pyrophoric metals.

Die Passivierungsmittel müssen in möglichst feinteiliger Form vorliegen, um eine vollständige Beschichtung und befriedigende Haftung zu gewährleisten. Die Passivierungsmittel werden deshalb vorzugsweise mit einer Teilchengröße von < 50 µm, vorzugsweise < 10 µm verwendet.The passivating agents must be in the finest possible form to ensure complete coating and satisfactory adhesion. The passivating agents are therefore preferably used with a particle size of <50 μm, preferably <10 μm.

Auf diese Weise lassen sich guthaftende Überzüge herstellen, die auch über einen längeren Zeitraum ohne Probleme gelagert werden können.In this way, well-adhering coatings can be produced, which can also be stored over a longer period without problems.

Die nach dem erfindungsgemäßen Verfahren hergestellten passivierten Metalle zeichnen sich außerdem durch schwere Entzündbarkeit sowie durch günstiges Brandverhalten aus. Sie eignen sich deshalb im besonderen Maße als Behandlungsmittel für metallurgische Schmelzen, vorzugsweise für die Entschwefelung von Roheisen, zumal bei der thermischen Zersetzung der Passivierungsmittel keine unerwünschten bzw. störenden Zersetzungsprodukte entstehen.The passivated metals produced by the process according to the invention are also notable for their high flammability and favorable fire behavior. They are therefore particularly suitable as treatment agents for metallurgical melts, preferably for the desulfurization of pig iron, especially since no undesired or disruptive decomposition products are formed during the thermal decomposition of the passivating agents.

Die nachfolgenden Beispiele sollen die Erfindung näher erläutern.The following examples are intended to explain the invention in more detail.

Beispiel 1example 1

97 Gew.-Teile metallisches Magnesiumpulver (Magnesiumgehalt 99,8%) der Körnung 0,2-0,8 mm wurden zunächst mit 0,3 Gew.-Teilen Silikonöl (Wacker AK 100) versetzt. Die Komponenten wurden solange miteinander intensiv vermischt, bis eine vollständige Benetzung der Magnesiumpartikel eingetreten war. Anschließend wurden 3 Gew.-Teile feinteiliges Cyanoguanidin (Teilchengröße 98% < 10 µm) zugegeben und durch intensives Mischen mit dem Magnesiumpulver die Passivierungsschicht gebildet.97 parts by weight of metallic magnesium powder (magnesium content 99.8%) with a grain size of 0.2-0.8 mm were initially mixed with 0.3 part by weight of silicone oil (Wacker AK 100). The components were mixed intensively with one another until complete wetting of the magnesium particles had occurred. Then 3 parts by weight of finely divided cyanoguanidine (particle size 98% <10 μm) were added and the passivation layer was formed by intensive mixing with the magnesium powder.

Beispiel 2Example 2

Entsprechend Beispiel 1 wurden 99 Gew.-Teile metallisches Magnesiumpulver (Magnesiumgehalt 99,8%) der Körnung 0,2-0,8 mm mit 1 Gew.-Teil feinteiligem Cyanoguanidin (Teilchengröße 98% < 10 µm) beschichtet.According to Example 1, 99 parts by weight of metallic magnesium powder (magnesium content 99.8%) with a grain size of 0.2-0.8 mm were coated with 1 part by weight of finely divided cyanoguanidine (particle size 98% <10 μm).

Beispiel 3Example 3

Entsprechend Beispiel 1 wurden 97 Gew.-Teile metallisches Magnesiumpulver (Magnesiumgehalt 99,8%) der Körnung 0,2-0,8 mm mit 3 Gew.-Teilen feinteiligem Melamin (Teilchengröße 99% < 60 µm) passiviert.According to Example 1, 97 parts by weight of metallic magnesium powder (magnesium content 99.8%) with a grain size of 0.2-0.8 mm were passivated with 3 parts by weight of finely divided melamine (particle size 99% <60 μm).

Beispiel 4Example 4 Untersuchung des Brenn- und Zündverhaltens.Investigation of the burning and ignition behavior.

Zur Beurteilung des Passivierungseffektes wurde ein von der BAM (Bundesanstalt für Materialprüfung) empfohlener Brenntest zur Einstufung leicht brennbarer fester Stoffe in die Gefahrengutklassen durchgeführt.To assess the passivation effect, a burn test recommended by the BAM (Federal Institute for Material Testing) was carried out to classify easily flammable solid substances in the hazardous goods classes.

Bei diesem Test wird die Prüfsubstanz in einer handelsüblichen Form zu einer ungefähr 250 mm langen, 20 mm breiten und 10 mm hohen durchgehenden Schüttung geformt und auf eine kalte undurchlässige Unterlage mit geringer Wärmeleitfähigkeit gebracht. Mit Hilfe eines Bunsenbrenners wird die Schüttung an einem Ende gezündet. Die beobachtete Abbrandzeit ist ein Maß für den pyrophoren Charakter der Prüfsubstanz.In this test, the test substance is shaped in a commercial form into an approximately 250 mm long, 20 mm wide and 10 mm high continuous bed and placed on a cold impermeable surface with low thermal conductivity. The fill is ignited at one end with the help of a Bunsen burner. The observed burn-up time is a measure of the pyrophoric character of the test substance.

In der nachfolgenden Tabelle sind Ergebnisse der Brenn- und Zündversuche zusammengefaßt. Getestet wurden sowohl reines unpassiviertes Mg-Pulver (1), Beschichtungen mit dem Stand der Technik entsprechenden oxidischen Substanzen (2)-(4) und erfindungsgemäß passiviertes Mg (5)-(7).The results of the combustion and ignition tests are summarized in the table below. Both pure unpassivated Mg powder (1), coatings with oxidic substances (2) - (4) corresponding to the state of the art and Mg (5) - (7) passivated according to the invention were tested.

Während oxidische Passivierungsmittel gegenüber dem reinen Magnesiumpulver nur leichte Verbesserungen bewirken (2), (4), zeigen die erfindungsgemäßen Produkte eine überraschend starke Passivierungswirkung.While oxidic passivating agents only bring about slight improvements compared to pure magnesium powder (2), (4), the products according to the invention show a surprisingly strong passivating effect.

Eine Zugabe von nur 3 Gew.-% Cyanoguanidin zum Mg-Pulver ist ausreichend, um das Produkt unbrennbar zu machen. Nur mit Mühe konnte es mit der Bunsenbrennflamme entzündet werden und verlosch anschließend von selbst. Eine geringere Zugabemenge von 1 Gew.-% Cyanoguanidin ist immer noch ausreichend, die Brenngeschwindigkeit von reinem Mg-Pulver um den Faktor 4 zu verzögern.

Figure imgb0001
The addition of only 3% by weight of cyanoguanidine to the Mg powder is sufficient to make the product non-flammable. It was difficult to ignite with the Bunsen flame and then went out on its own. A lower addition of 1% by weight of cyanoguanidine is still sufficient to delay the burning rate of pure Mg powder by a factor of 4.
Figure imgb0001

Claims (19)

1. Process for the passivation of pyrophoric metals, especially of magnesium, by coating with a passivation agent, characterised in that, as passivation agent, one uses 0.5 to 5 wt.% of an s-triazine and/or guanidine derivative, referred to the weight of the metal.
2. Process according to claim 1, characterised in that one uses the passivation agent in amounts of 1 to 3 wt.%, referred to the weight of the metal.
3. Process according to claims 1 or 2, characterised in that one uses melamine as s-triazine derivative.
4. Process according to claims 1 or 2, characterised in that one uses benzoguanamine and/or acetoguanamine as s-triazine derivative.
5. Process according to claims 1 or 2, characterised in that one uses melam, melem and/or melon as s-triazine derivative.
6. Process according to claims 1 or 2, characterised in that one uses a melamine- and/or benzoguanamine-formaldehyde condensation product as s-triazine derivative.
7. Process according to claims 1 or 2, characterised in that one uses one or more substituted guanidines as guanidine.
8. Process according to claim 7, characterised in that one uses cyanoguanidine and/or guanylurea as substituted guanidine.
9. Process according to claim 7, characterised in that one uses a guanidine salt selected from the group of guanidine phosphate, guanidine sulphamate and guanidine cyanurate as guanidine derivative.
10. Process according to one of the preceding claims, characterised in that one carries out the coating of the metal with the passivation agent with the help of an anhydrous wetting agent.
11. Process according to claim 10, characterised in that one uses the wetting agent in an amount of 0.1 to 0.5 wt.%, referred to the weight of the metal.
12. Process according to claims 10 or 11, characterised in that one uses silicone oil as wetting agent.
13. Passivated pyrophoric metal, characterised in that the metal particles are coated with 0.5 to 5 wt.% of s-triazine derivative and/or guanidine or a guanidine derivative, referred to the weight of the metal.
14. Passivated pyrophoric magnesium according to claim 13.
15. Passivated pyrophoric metal according to claim 13 or 14, characterised in that it contains 1 to 3 wt.% of the coating agent.
16. Passivated pyrophoric metal according to one of claims 13 to 15, characterised in that the coating agent contains one or more substance from the group melamine, benzoguanamide, acetoguanamine, melam, melem, melon, melamine-formaldehyde condensate, benzoguanamine condensate, guanidine, cyanoguanidine, guanylurea, guanidine phosphate, guanidine sulphamate and guanidine cyanurate.
17. Passivated pyrophoric metal according to one of claims 13 to 16, characterised in that it additionally contains 0.1 to 0.5 wt.% of wetting agent.
18. Passivated pyrophoric metal according to one of claims 13 to 17, characterised in that the coating of s-triazine derivative and/or guanidine or derivative consists of particles of < 50 µm.
19. Use of a passivated pyrophoric metal according to one of claims 13 to 18 as treatment agent for metallurgical melts.
EP90105021A 1989-03-17 1990-03-16 Passivation of pyrophoric metals Expired - Lifetime EP0388816B1 (en)

Priority Applications (1)

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AT90105021T ATE71866T1 (en) 1989-03-17 1990-03-16 PASSIVATION OF PYROPHORIC METALS.

Applications Claiming Priority (2)

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DE3908815 1989-03-17
DE3908815A DE3908815A1 (en) 1989-03-17 1989-03-17 METHOD FOR PASSIVATING PYROPHORIC METALS

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EP0388816B1 true EP0388816B1 (en) 1992-01-22

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DE4138231C1 (en) * 1991-11-21 1992-10-22 Skw Trostberg Ag, 8223 Trostberg, De
US5342430A (en) * 1993-07-28 1994-08-30 Grocela Kathe Teresa A Passivation of methylchlorosilane fines
DE102007061236A1 (en) * 2007-12-19 2009-07-09 Ecka Granulate Gmbh & Co. Kg Transport form for base metal particles and use of the same
JP5361784B2 (en) * 2010-04-15 2013-12-04 日本マテリアル株式会社 Method for protecting metallic calcium and protected metallic calcium
JP5542088B2 (en) * 2011-04-06 2014-07-09 日本マテリアル株式会社 Iron-based metal desulfurization agent, its production method and desulfurization method
JP6595808B2 (en) * 2015-06-05 2019-10-23 久幸 末松 Magnesium metal fine particles and method for producing magnesium metal fine particles
JP7191590B2 (en) * 2018-08-24 2022-12-19 三星電子株式会社 Organic-inorganic hybrid composition, and molded articles and optical parts containing the same
DE102020102628A1 (en) 2020-02-03 2021-08-05 Eos Gmbh Method for moderating a reaction of metal particles

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FI90211B (en) 1993-09-30
CA2011785A1 (en) 1990-09-17
ATE71866T1 (en) 1992-02-15
US5089049A (en) 1992-02-18
KR0137936B1 (en) 1998-07-15
CA2011785C (en) 1995-12-19
DE8915539U1 (en) 1990-10-04
KR900014640A (en) 1990-10-24
JPH02282402A (en) 1990-11-20
JPH0768564B2 (en) 1995-07-26
EP0388816A1 (en) 1990-09-26
DE59000035D1 (en) 1992-03-05
FI901342A0 (en) 1990-03-16
DE3908815A1 (en) 1990-09-20

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