US3279888A - Method of and apparatus for determining the oxygen content of metals - Google Patents

Method of and apparatus for determining the oxygen content of metals Download PDF

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Publication number
US3279888A
US3279888A US304719A US30471963A US3279888A US 3279888 A US3279888 A US 3279888A US 304719 A US304719 A US 304719A US 30471963 A US30471963 A US 30471963A US 3279888 A US3279888 A US 3279888A
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chamber
analysis
metal
carbon monoxide
gas
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US304719A
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English (en)
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Holler Paul
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Huettenwerk Oberhausen AG
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Huettenwerk Oberhausen AG
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/20—Metals
    • G01N33/202—Constituents thereof
    • G01N33/2022—Non-metallic constituents
    • G01N33/2025—Gaseous constituents

Definitions

  • the oxygen content of the metal is converted, by combination with carbon, to carbon monoxide which is then analyzed.
  • I disclose and claim a method of extracting gases from metal samples with the aid of an electric arc wherein an extraction chamber is, prior to the introduction of a metal sample into the region of the arc, filled with an inert or reducing protective gas designed to eliminate any atmospheric oxygen which may be present in the chamber and to purge therefrom all traces of the residues from an earlier analysis.
  • an electric arc is struck between the electrodes to produce a high temperature in excess of that to be employed subsequently for melting the sample, thereby releasing any impurity gases within the chamber and rendering the electrodes and/or the sample holders free from absorbed and adsorbed gases.
  • the atmosphere within the reaction chamber in accordance with the principles of my application Ser. No. 193,229, consists of argon admixed with hydrogen in an amount between 1 and by volume.
  • the purging of the extraction chamber can be carried out under reducing conditions with the aid of a higher energy electric arc than with the use of the pure inert gas.
  • the metal samples are introduced into the chamber and blanketed with the pure inert gas, whereupon an electric arc is struck between the sample holder and a counterelectrode to free the gases trapped within the sample and, in the case of oxygen, produce carbon monoxide.
  • the extraction chamber is provided with a plurality of sample holders carried by a common support and successively displaceable into the region of the counterelectrode for degassing as described above.
  • the analysis of the extracted gas is effected with the aid of a conventional spectrometer whose sensing element is directed at the electric arc.
  • the sample holders are mounted upon a turntable disposed within the extraction chamber.
  • these earlier systems are characterized by difiiculties to eliminate the getter" effect whereby a large proportion of the gases released from the samples are adsorbed or absorbed by the graphite electrodes, the soot-covered walls of the extraction chamber and by neighboring electrodes.
  • the existence of cold portions of these electrodes and the chamber walls increases the getter efiect.
  • This efiect is all the more inconvenient since it is not for the most part reproducible so that even when a calibration curve is provided for the spectrometric analysis apparatus, this curve is generally only valid for a particular set of circumstances and certain gettering conditions.
  • Another object of the present invention is to provide an apparatus for analyzing metal samples in an efficient and, preferably, automatic manner with a relatively short analysis time.
  • Still another object of the invention is to provide a method of automatically analyzing the oxygen content of steel samples wherein the disadvantages of gettering are eliminated.
  • the melting of the. metal sample is carried out by disposing it within a hollow carbonaceous (i.e.
  • the extracted gas is transferred to the analysis or measuring chamber wherein it is studied by infrared absorption to determine the proportion of carbon monoxide present within the analysis chamber and, consequently, the oxygen content of a sample of a metal of known weight.
  • This method permits an absolute determination of the oxygen content in a steel sample in somewhat less than 2.5 min-utes because in several seconds a one-gram sample can be melted with the aid of an electric-arc discharge of between 20 and 40 amperes, the oxygen being quantitatively converted to carbon monoxide. Since the cloud of carbon monoxide surrounding the arc is drawn into the evacuated analysis chamber in a fraction of a second, there is no possibility that the walls of the vessel or the electrodes will absorb the gas by a getter effect, It is, consequently, an important aspect of this invention that the communication between the extraction chamber and the analysis chamber be established immediately upon termination of the arc discharge so that any tendency toward gettering is reduced if not entirely eliminated.
  • the thorough purging of the extraction chamber by pumping the extracted gas therefrom or forcing it out of the latter in a carrier gas can be eliminated since there is a natural tendency for the gas to enter the previously evacuated analysis chamber and this takes place without the existence of a force stream of inert gas or passing the extracted gas through a pump.
  • This result is important since the gas would otherwise adsorb readily upon the finely divided graphite within the evacuation chamber.
  • the pressure Within the analysis chamber is elevated to a level conducive to spectroanalysis of the gas (e.g. atmospheric pressure or slightly in excess thereof) and facilitating the reproduction of the analysis results by the admission into the analysis chamber of an inert gas, preferably argon.
  • the analysis chamber comprises a large-capacity storage receptacle for the evacuated gas and a detection receptacle remote therefrom, circulating means being provided for rapid displacement of the gas stream between these receptacles in a closed path so as to mix the carrier gas with the extracted gas rapidly and completely.
  • the I-R analysis apparatus may include the usual recorder or the like by means of which the steady-state mixture concentration of carbon monoxide within the analysis chamber can be readily observed. Means can also be provided for indicating that the concentration of carbon monoxide in the gas circulated past the spectroanalysis device is constant before the final reading is taken.
  • the volume of the analysis chamber may be made somewhat larger (e g. three times as large) than the volume of the extraction chamber, it being noted that the eifective volume of the analysis chamber can include the circulating conduits and storage and detection receptacles.
  • FIG. 1 is a diagramma-tical view of the apparatus for carrying out the rapid analysis of steel samples according to the present invention.
  • FIG. 2 is a circuit diagram of a control system for automatically or semiautomatically operating the apparatus of FIG. 1.
  • FIG. 1 I show an extraction chamber 1 which can be generally similar to those illustrated in my copending application Ser. No. 193,229 and which is amply described therein.
  • this chamber 1 has a stationary counterelectrode 5, which can be fed toward the sample electrode 3 by the means described in the copending application upon erosion of the electrodes.
  • the sample electrodes 3 are hollow or can be shifted and distributed around the periphery of a turntable 2, controlled externally of chamber 1, in angularly spaced relationship for successive juxtaposition with the counterelectrode 5. Electrodes 3 receive samples 4 of the metal to be analyzed, these samples having a mass on the order of 1 gram although larger samples can be used, as described.
  • a suction conduit 4% connects chamber 1 with a manometer 11, which indicates the pressure within the chamber 1, and the suction lines 41, 42 connected to a coarse-vacuum pump 7 and a high-vacuum pump 8 which may be of the vapor-lift or diffusion type.
  • Electromagnetic valves 6 and 9 are interposed between pump '7 and 8 and chamber 1.
  • the pump 7 also communicates, in the usual manner, with the high-vacuum pump 8 via an electro-magnetic valve 26, a further manometer 19 indicating the negative pressure produced by pump 7.
  • Suction line 44 also serves as an outlet for the extracted gases and communicates with tube 43 which leads to a storage receptacle 13 of an analysis chamber via a dust filter 17 preventing influx of graphite or metal particles into the analysis chamber.
  • a pair of magnetic valves 15, 16 control the gas flow into the latter chamber, which consists of the storage receptacle 13 and a detection receptacle 1% for the flow analysis of the gas.
  • the analysis chamber further comprises conduits id-43 having valves 19, 2d and 21 and a circulating tube 22 for thoroughly mixing the gas by displacing it between the analysis chamber 18 and the storage chamber 13 in a closed system.
  • An electromagnetic valve 14 connects the analysis chamber with pump 7 via a conduit 49 while again the valve 25 serves for the efllux of the purging gas.
  • the purging gas can be argon which passes from a tank 50 through valve 24 into the analysis chamber, a further valve 399 being provided for the introduction of a calibrating gas with a known carbon-monoxide content.
  • a pipeline 51 is connected to tank 50, which constitutes a common supply means for both chambers, and to the valve 12 of the extraction chamber 1.
  • Example A one-gram cylindrical slug of steel cast from the molten metal withdrawn from an open-hearth furnace is analyzed in an apparatus of the foregoing type by interposing it between graphite electrodes and producing an arc discharge between these electrodes with an intensity of 30 amperes. After 5 seconds, the discharge is reduced to a level of about 20 amperes to avoid undue evaporation of metal from the sample, the extraction operation being terminated after about 29 seconds whereupon the extracted carbon monoxide is passed into the analysis chamber. Pure argon is admitted into the latter to raise the pressure therein to several millimeters of mercury above atmospheric pressure, the pressure within this chamber being about 20 mm. of mercury prior to admission of the extracted gas.
  • the extracted gas is circulated in the analysis chamber for 15 seconds whereupon the I-R absorption recorder showed a levelling off of the carbon monoxide content and this value was taken as the carbon monoxide content of the sample.
  • this method which was carried out in less than 2 minutes, was compared with chemical methods of analysis taking many times as long, almost identical results were obtained.
  • the intensity of the discharge after melting will be between 20% and 50% of that required to melt the sample and will be determined by the composition of the latter and the type of bonding between the oxygen and the metal.
  • a method of determining the oxygen content of a ferrous metal comprising the steps of:
  • Apparatus for determining the oxygen content of a metal comprising;
  • a turntable in said chamber formed with a plurality of angularly spaced first arc-discharge electrodes adapted to receive samples of the metal to be analyzed;
  • a second arcxiischarge electrode in said chamber alignable with said first electrodes
  • said analysis chamber communicating with said extraction chamber, said analysis chamber including a storage receptacle,
  • valve means interposed between said chambers for admitting said carbon monoxide from said extraction chamber into said analysis chamber, said analysis chamber having a volume in excess of that of said extraction chamber;
  • evacuating means connectible with said analysis chamber for evacuating same prior to the introduction of said carbon monoxide into said analysis chamber;
  • detection means at said detection receptacle responsive to said carbon monoxide for determining the amount thereof within said analysis chamber
  • supply means for feeding an inert gas to said analysis chamber to raise the pressure therein upon admission thereto of said carbon monoxide
  • conduit means communicating between said supply means and said extraction chamber, said evacuating means being connecti'ble with said extraction chamber.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
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  • Pathology (AREA)
  • Investigating And Analyzing Materials By Characteristic Methods (AREA)
  • Sampling And Sample Adjustment (AREA)
US304719A 1962-08-21 1963-08-20 Method of and apparatus for determining the oxygen content of metals Expired - Lifetime US3279888A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEH46701A DE1255352B (de) 1962-08-21 1962-08-21 Verfahren und Vorrichtung zur Sauerstoffschnellbestimmung in Metallen, insbesondere Staehlen

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US3279888A true US3279888A (en) 1966-10-18

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US (1) US3279888A (de)
BE (1) BE636360A (de)
DE (1) DE1255352B (de)
GB (1) GB979702A (de)
LU (1) LU43762A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932135A (en) * 1974-11-07 1976-01-13 Centro Sperimentale Metallurgico S.P.A. Method and apparatus for the determination of the oxygen content of metallic baths
US4229412A (en) * 1977-12-14 1980-10-21 Strohlein GmbH & Co. Apparatus for the determination of bond forms of gases
US4719120A (en) * 1986-09-29 1988-01-12 The United States Of America As Represented By The Secretary Of The Navy Detection of oxygen in thin films

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT386287B (de) * 1984-07-09 1988-07-25 Voest Alpine Ag Verfahren zur bestimmung des reduktionsgrades von erzen
JPH068813B2 (ja) * 1985-12-05 1994-02-02 動力炉・核燃料開発事業団 核燃料酸化物の酸素対金属原子数比の測定方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2962360A (en) * 1958-08-22 1960-11-29 Lab Equipment Corp Automatic carbon determinator
US2964389A (en) * 1958-08-15 1960-12-13 Titanium Metals Corp Apparatus for determination of oxygen in metals
US3065060A (en) * 1958-03-05 1962-11-20 Nat Res Corp Metal analysis apparatus

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE922867C (de) * 1952-07-27 1955-01-27 Inst Eisenhuettenwesen Der Rhe Verfahren und Vorrichtung zum Entgasen von Metallen und Metallegierungen im Vakuum zur Bestimmung ihres Gas-, z. B. ihres Sauerstoffgehaltes
DE1124271B (de) * 1959-06-16 1962-02-22 Heinrich Feichtinger Dr Ing Verfahren zur quantitativen Sammlung und UEberfuehrung von unter Vakuum extrahierten Gasen in einen Gaschromatographen und Einrichtung zur gaschromatographischen Gasanalyse

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3065060A (en) * 1958-03-05 1962-11-20 Nat Res Corp Metal analysis apparatus
US2964389A (en) * 1958-08-15 1960-12-13 Titanium Metals Corp Apparatus for determination of oxygen in metals
US2962360A (en) * 1958-08-22 1960-11-29 Lab Equipment Corp Automatic carbon determinator

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932135A (en) * 1974-11-07 1976-01-13 Centro Sperimentale Metallurgico S.P.A. Method and apparatus for the determination of the oxygen content of metallic baths
US4229412A (en) * 1977-12-14 1980-10-21 Strohlein GmbH & Co. Apparatus for the determination of bond forms of gases
US4719120A (en) * 1986-09-29 1988-01-12 The United States Of America As Represented By The Secretary Of The Navy Detection of oxygen in thin films

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Publication number Publication date
BE636360A (de) 1900-01-01
LU43762A1 (de) 1963-07-16
DE1255352B (de) 1967-11-30
GB979702A (en) 1965-01-06

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