AT129294B - Process for protecting magnesium and magnesium alloys against attack by heating baths made from molten salt. - Google Patents
Process for protecting magnesium and magnesium alloys against attack by heating baths made from molten salt.Info
- Publication number
- AT129294B AT129294B AT129294DA AT129294B AT 129294 B AT129294 B AT 129294B AT 129294D A AT129294D A AT 129294DA AT 129294 B AT129294 B AT 129294B
- Authority
- AT
- Austria
- Prior art keywords
- sep
- magnesium
- molten salt
- protecting
- against attack
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
- C22B26/20—Obtaining alkaline earth metals or magnesium
- C22B26/22—Obtaining magnesium
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Metallurgy (AREA)
- Environmental & Geological Engineering (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Manufacturing & Machinery (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Description
<Desc/Clms Page number 1>
Verfahren zum Schutz von Magnesium und Magnesiumlegierungen gegen den Angriff von Heizbädern aus Salzschmelzen.
Ein bekanntes Mittel für die Wärmebehandlung von Metallen zum Zwecke der Vergütung usw. sind Salzschmelzen, insonderheit die niedrig schmelzenden Salpeterschmelzen, in welche die Metalle für eine gegebene Zeitdauer eingetaucht werden, worauf je nach den gegebenen Umständen Abkühlung oder Abschreckung und Befreiung von der anhaftenden Salzschmelze erfolgt.
Versuche, welche in dieser Richtung mit Magnesium bzw. Magnesiumlegierungen (insbesondere als Blech) in Salpeterbädern bei 350-4000 C ausgeführt wurden, hatten zwar in physikalischer Hinsicht den gewünschten Erfolg, zeigten aber anderseits, dass die Bleche von der Salpeterschmelze-auch bei verhältnismässig kurzer Berührungsdauer - ganz erheblich korrodiert wurden. Die ermittelten Angriffszahlen liessen eine Gewichtsabnahme erkennen, die sich je nach Länge der Versuchsdauer, beispielsweise zwischen etwa 2-1 und 7'5 g/m2 und Stunde, bewegte.
Es wurde gefunden, dass Zusätze von Alkalichromaten, Alkalibichromaten und Alkalifluoriden zur Salpeterschmelze bereits in niedrigen Konzentrationen, beispielsweise 1-20/o, den Angriff völlig hintanzuhalten vermögen, indem sie anscheinend zur Bildung einer Schutzschicht auf dem Metall bzw. auf der Legierung beitragen.
Derartige,'Zusätze von Alkalifluoriden bzw. Alkalichromaten sind. zur Verhinderung der korrodierenden Wirkung von Salzschmelzen auf Schwermetalle, u. zw. in erster Linie auf Eisen und Stahl, bereits vorgeschlagen worden. In Anbetracht der Tatsache, dass Magnesium und Magnesiumlegierungen einem korrodierenden Angriff schon bei gewöhnlichen Temperaturen in unvergleichlich höherem Masse unterliegen, als dies bei den Schwermetallen der Fall ist, muss im vorliegenden Falle die Schutzwirkung eines verhältnismässig sehr geringen Zusatzes von Alkalifluoriden und Alkalichromaten zu den Salzschmelzen bei den für geschmolzene Salze in Frage kommenden, wesentlich erhöhten Temperaturen trotzdem als überraschend bezeichnet werden.
Folgende Zahlen geben ein Bild von den durch das Verfahren erzielten Ergebnissen :
Beispiel 1 :
EMI1.1
<tb>
<tb> Einwirkungsdauer <SEP> je <SEP> 5 <SEP> Minuten.
<tb>
Zusammensetzung <SEP> der <SEP> Salzschmelze <SEP> : <SEP> Angriff <SEP> in <SEP> glum2 <SEP> und <SEP> Stunde <SEP> :
<tb> KNOg <SEP> -3'42
<tb> KNO3 <SEP> + <SEP> 2% <SEP> K2CrO4 <SEP> ¯ <SEP> 0
<tb> KNOg <SEP> + <SEP> 2% <SEP> K2Cr207 <SEP> + <SEP> 0-6
<tb>
Beispiel 2 :
EMI1.2
<tb>
<tb> Einwirkungsdauer <SEP> je <SEP> 30 <SEP> Minuten.
<tb>
Zusammensetzung <SEP> der <SEP> Salzschmelze <SEP> : <SEP> Angriff <SEP> in <SEP> g/m2 <SEP> und <SEP> Stunde <SEP> :
<tb> KNOs-2-6
<tb> ENO3 <SEP> + <SEP> 20/0 <SEP> NaF <SEP> + <SEP> 2-0
<tb> KNO3 <SEP> + <SEP> 1% <SEP> KHF2 <SEP> + <SEP> KF <SEP> +1#6
<tb> KNOB <SEP> + <SEP> 20/o <SEP> LiF <SEP> + <SEP> 2-6
<tb>
) Die Gewichtszunahme entspricht der Bildung einer dünnen, in Wasser unlöslichen Schutzschicht.
**WARNUNG** Ende DESC Feld kannt Anfang CLMS uberlappen**.
<Desc / Clms Page number 1>
Process for protecting magnesium and magnesium alloys against attack by heating baths made from molten salt.
A well-known means for the heat treatment of metals for the purpose of tempering etc. are molten salts, in particular the low-melting nitric melts, in which the metals are immersed for a given period of time, followed by cooling or quenching and removal of the adhering molten salt, depending on the circumstances .
Tests carried out in this direction with magnesium or magnesium alloys (especially as sheet metal) in saltpeter baths at 350-4000 C had the desired success in physical terms, but on the other hand they showed that the sheets were removed from the molten saltpeter - even if they were relatively short Contact time - have been corroded quite considerably. The determined number of attacks revealed a decrease in weight, depending on the length of the test, for example between about 2-1 and 7'5 g / m2 and hour.
It has been found that additions of alkali dichromates, alkali dichromates and alkali fluorides to the molten nitrate are able to completely prevent the attack even in low concentrations, e.g. 1-20 / o, by apparently contributing to the formation of a protective layer on the metal or on the alloy.
Such 'additions of alkali fluorides or alkali chromates are. to prevent the corrosive effect of molten salts on heavy metals, etc. primarily on iron and steel, has already been proposed. In view of the fact that magnesium and magnesium alloys are subject to corrosive attack even at normal temperatures to an incomparably higher degree than is the case with heavy metals, the protective effect of a relatively very small addition of alkali fluorides and alkali chromates to the molten salt must in the present case which for molten salts in question, substantially elevated temperatures are nevertheless described as surprising.
The following figures give a picture of the results achieved by the process:
Example 1 :
EMI1.1
<tb>
<tb> Duration of action <SEP> per <SEP> 5 <SEP> minutes.
<tb>
Composition <SEP> of the <SEP> molten salt <SEP>: <SEP> attack <SEP> in <SEP> glum2 <SEP> and <SEP> hour <SEP>:
<tb> KNOg <SEP> -3'42
<tb> KNO3 <SEP> + <SEP> 2% <SEP> K2CrO4 <SEP> ¯ <SEP> 0
<tb> KNOg <SEP> + <SEP> 2% <SEP> K2Cr207 <SEP> + <SEP> 0-6
<tb>
Example 2:
EMI1.2
<tb>
<tb> Duration of action <SEP> per <SEP> 30 <SEP> minutes.
<tb>
Composition <SEP> of the <SEP> molten salt <SEP>: <SEP> attack <SEP> in <SEP> g / m2 <SEP> and <SEP> hour <SEP>:
<tb> KNOs-2-6
<tb> ENO3 <SEP> + <SEP> 20/0 <SEP> NaF <SEP> + <SEP> 2-0
<tb> KNO3 <SEP> + <SEP> 1% <SEP> KHF2 <SEP> + <SEP> KF <SEP> + 1 # 6
<tb> KNOB <SEP> + <SEP> 20 / o <SEP> LiF <SEP> + <SEP> 2-6
<tb>
) The increase in weight corresponds to the formation of a thin, water-insoluble protective layer.
** WARNING ** End of DESC field may overlap beginning of CLMS **.
Claims (1)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE357428X | 1929-12-11 |
Publications (1)
Publication Number | Publication Date |
---|---|
AT129294B true AT129294B (en) | 1933-07-25 |
Family
ID=6290567
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AT129294D AT129294B (en) | 1929-12-11 | 1930-11-10 | Process for protecting magnesium and magnesium alloys against attack by heating baths made from molten salt. |
Country Status (3)
Country | Link |
---|---|
AT (1) | AT129294B (en) |
CH (1) | CH150378A (en) |
GB (1) | GB357428A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2458073A (en) * | 1944-01-06 | 1949-01-04 | Parker Appliance Co | Coating magnesium and magnesium alloys |
DE752422C (en) * | 1936-12-31 | 1952-11-04 | Degussa | Process for the treatment of light metals in nitrates or nitrate-nitrite mixtures and fused baths containing bichromate |
-
1930
- 1930-11-10 AT AT129294D patent/AT129294B/en active
- 1930-11-11 CH CH150378D patent/CH150378A/en unknown
- 1930-11-26 GB GB35646/30A patent/GB357428A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE752422C (en) * | 1936-12-31 | 1952-11-04 | Degussa | Process for the treatment of light metals in nitrates or nitrate-nitrite mixtures and fused baths containing bichromate |
US2458073A (en) * | 1944-01-06 | 1949-01-04 | Parker Appliance Co | Coating magnesium and magnesium alloys |
Also Published As
Publication number | Publication date |
---|---|
CH150378A (en) | 1931-10-31 |
GB357428A (en) | 1931-09-24 |
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