CA1208287A - High speed oxygen sensor for molten metals - Google Patents
High speed oxygen sensor for molten metalsInfo
- Publication number
- CA1208287A CA1208287A CA000420891A CA420891A CA1208287A CA 1208287 A CA1208287 A CA 1208287A CA 000420891 A CA000420891 A CA 000420891A CA 420891 A CA420891 A CA 420891A CA 1208287 A CA1208287 A CA 1208287A
- Authority
- CA
- Canada
- Prior art keywords
- sheath
- cell
- oxygen
- reference material
- closed end
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/411—Cells and probes with solid electrolytes for investigating or analysing of liquid metals
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/411—Cells and probes with solid electrolytes for investigating or analysing of liquid metals
- G01N27/4115—Composition or fabrication of the electrodes and coatings thereon, e.g. catalysts
- G01N27/4117—Reference electrodes or reference mixtures
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Measuring Oxygen Concentration In Cells (AREA)
- Investigating And Analyzing Materials By Characteristic Methods (AREA)
Abstract
ABSTRACT
An oxygen sensor of the immersion type for the determination of dissolved oxygen in molten steel having a fast speed of response with a calcium stabilized zirconium oxide closed end sheath with a small mass of oxygen reference material composed of 75% powdered chromium and 25% chromic oxide and the remainder of the sheath filled with aluminum oxide and sealed.
An oxygen sensor of the immersion type for the determination of dissolved oxygen in molten steel having a fast speed of response with a calcium stabilized zirconium oxide closed end sheath with a small mass of oxygen reference material composed of 75% powdered chromium and 25% chromic oxide and the remainder of the sheath filled with aluminum oxide and sealed.
Description
~ C~8213~ `
HIGH SPEED OXYGE~ SENSOR FOR MOLTEN METALS
BACKGROUND OF THE INVENTION
This invention relates to devices for developlng a voltage related to the level of dissolved oxygen in molten metal~ and particularly to such devices which produce an output voltage related to the dissolved oxygen content w,hen the device is immersed in molten steel.
For some tlme galvanic cells have been used for determining the concentration o~ oxygen in molten metal wherein the cell includes a solid'electrolyte which is in conkact with material to provide a re~erence ~alue of oxygen. The voltage output of the cell is related to the difference in partial pressure of oxygen applied to opposite faces of the electrolyte.
For the measurement of oxygen in liquid steel, the electrolyte is generally calcium stabili,zed zlrconium oxide and ~he re~erence electrode may be metal in combination with an oxide of the metal. U. S. Patent 3,723,279 teaches that the oxygen re~erence is produced by a mixture o~ ¦
chromium and chromic oxide.
~ .
In using such devices, the cell is generally supported in one end'of a cardboard tube for immersion in the liquid steel. It has been ~ound that with the devices taught by the prior art that it is generally necessary to .~
I ' ' '~
(` ~LZ()&12~17 maintaln the cell tmmersed in the liquid steel for l0 seconds or longer. In order to suppo~t the oxygen sensor in the liquid steel for such a length o~ time, it has been necessary to use cardboard tubes of significant thickness to prevent the llquid steel ~rom burning through the cardboard tube and destroying the electrical contact elements for the cell.
Furthermore, cells produced in accordance with the prior art have produced output voltages that show signiPicant erratic . variations which make it difficult to determine with any degree of accuraey the dissolved oxygen in.the molten steel.
It is an.ob~ect of this invention to provide a cell for immersion in molten metal that will have a much faster speed of response and a more stable output voltage.
. ., , . .
BRIEF DESCRIPTION OF THE DRAWING . .
Fig. l is a side elevation partially in section o~ a sensor manu~actured in accordance wlth this invention.
Referring to the Figure, there is shown an , expendable..immersion sensing device l0 comprised of a molded plastic body structure which may include a cup portion ll and a tubular portion 13. The cup portion ll contains a -quantlty of refractory cement.14 which supports in protruding relation with the cup.ll a connector. electrode 15 which is connected at the end embedded in the refractory cement l4 with an electrical.conductor 16 having an end I ~LZ(~8Z~
. ' .
portion i6a bent over through a notch 13a in the tubular portion~ 13 in order to provide a plug-in contact ~or the I .
- connector electrode 15.
An electrolyte cell electrode structure 17 is also supported by the re~ractory cement 14 in a manner to extend.outwardly there~rom in substantially parallel relation to the connector electrode 15. The cell structure 17 is comprised o~ a closed end tube 18 made o~ a material suitable for use as a solid electrolyte which for oxygen may be calcium stabllized z~rconium oxide. The tube 18 . contains a small mass 20 o~ a reference material in the .
~orm of a powder. When the element.to be measured is oxygen, a re~erence partial pressure o~ oxygen may be provided by a powdered metal and a stable oxide thereo~g such as chromium.in powdered form mixed with chromic oxide powder. In order to provide.for a high speed o~ response ~or the cell? it has been ~ound that the mass 20 o~
re~erence material should be kept small and should not more than 1/8th o~ an.inch o~ the tube 18. ~.urther to enhance the speed of response, and to provide the desired stability, it has been ~ound that the ratio o~ chromium powder to chromic oxide powder is ~uite critical and should be substantially 75~ chromium and 25% chromic oxide.
The mixture of chromium-chromic oxide ~orming the small mass 20 is preferably tamped in place in order to effeot a good mecha~ical and electrical contact in the end . . .
I '`'' 1.2()8Z8~ ) of the tube 18. To insure that .the.'chr'omium-chr'om~c oxide retains its contact with the end of the tube''18, a thin layer of fibrous alumlnum oxide 21l is pressed firmly against the exposed surface of the powder mass.20. To reduce the tlme for the partial pressure of oxygen produced.by,the mass 20 of reference material to reach a stable equ~libr~um value and thus to insure a high speed.o~ response from the cell, .
that portion of the tube 18 that is not ~illed w~th'the small mass 20 and the layer 24 should contain a filler 21 to reduce substantially to zero the air contained ln the tube 1.8.
; .
While any suitable dry filler material may be used, ,~
it has been found that a cell having a high speed of response can be obtained.by introducing into the tube 18 above the ' ,:
layer 24 a.quantity of aluminum oxide which preferably is ,:
introduced into the,tube 18 in powdered form to provide the filler 21. When the aluminum oxide powder is used,as the ~iller 21 to eliminate air in the tube 18, the powder should be quite :fine or at least contain a percentage of , fine powder to eliminate interstlces that could form air , pockets within the filler 21. The elimination of air within , the tube 18 may also be accomplished in other ways by inserting other types of powder, or by inserting within . ~ the tube 18 a solid materia]. such as quartz or ~ycor, or I.
.' utilizing a supercooled liquid to constitute the ~iller 21. ' Whatever substance is.used to fill the void within the tube 18 above the small mass 20 and layer 24, there must be provided a passageway to permit a conductor 22 to pass .~ k ,.
. .' . -4- I .
. I
I ( ~ ~zO~g7 ,,) ~ LF 2791 .
. ` , ' , through the lengkh of the tube 18 to make an electri.cal connection to the inner sur~ace of the electrolyte tube 18.
This electrical connection may be completed ~rom the . conductor 22 to the inner surrace o~ the tube 18 by way of the small mass 20 o~ the reference material. The end of the tube 18 with the conductor 22 in place is preferably sealed by an epoxy or other suitable cement 19 which serves to retain the aluminum oxide powder 21 and the mass 20 of the re~erence electrode in position. ¦
. , '', The electrical connection to the inner sur~ace of the electrolyte tube l8 is completed by way of the conductor 22 and.a conductor 23 which.is connected to the conductor 22 at a point submerged in the re~ractory cement . 14. The conductor 23 extends upwardly into tubular portion 13 and has a terminal end 23a bent in a conventional manner through a slot or notch 13b to ~orm a plug-in contact for the cell electrode structure 17. ~ metal cap, not shownl serves to protect the electrode structures prior to and during the time the device 10 is being immersed to a sub-surface level in a bath Or molten steel.
While there has been described an lmmersion device.comprising an oxygen determinlng.cell,.it is to be understood.that in practice such a cel-l is generally used in combination with other devices, such as, ~or example~
. ~amplers,temperature measuring devices, and thermal arrest . .
. ~`' , , .
.. ` -5- ` .
.." , .
HIGH SPEED OXYGE~ SENSOR FOR MOLTEN METALS
BACKGROUND OF THE INVENTION
This invention relates to devices for developlng a voltage related to the level of dissolved oxygen in molten metal~ and particularly to such devices which produce an output voltage related to the dissolved oxygen content w,hen the device is immersed in molten steel.
For some tlme galvanic cells have been used for determining the concentration o~ oxygen in molten metal wherein the cell includes a solid'electrolyte which is in conkact with material to provide a re~erence ~alue of oxygen. The voltage output of the cell is related to the difference in partial pressure of oxygen applied to opposite faces of the electrolyte.
For the measurement of oxygen in liquid steel, the electrolyte is generally calcium stabili,zed zlrconium oxide and ~he re~erence electrode may be metal in combination with an oxide of the metal. U. S. Patent 3,723,279 teaches that the oxygen re~erence is produced by a mixture o~ ¦
chromium and chromic oxide.
~ .
In using such devices, the cell is generally supported in one end'of a cardboard tube for immersion in the liquid steel. It has been ~ound that with the devices taught by the prior art that it is generally necessary to .~
I ' ' '~
(` ~LZ()&12~17 maintaln the cell tmmersed in the liquid steel for l0 seconds or longer. In order to suppo~t the oxygen sensor in the liquid steel for such a length o~ time, it has been necessary to use cardboard tubes of significant thickness to prevent the llquid steel ~rom burning through the cardboard tube and destroying the electrical contact elements for the cell.
Furthermore, cells produced in accordance with the prior art have produced output voltages that show signiPicant erratic . variations which make it difficult to determine with any degree of accuraey the dissolved oxygen in.the molten steel.
It is an.ob~ect of this invention to provide a cell for immersion in molten metal that will have a much faster speed of response and a more stable output voltage.
. ., , . .
BRIEF DESCRIPTION OF THE DRAWING . .
Fig. l is a side elevation partially in section o~ a sensor manu~actured in accordance wlth this invention.
Referring to the Figure, there is shown an , expendable..immersion sensing device l0 comprised of a molded plastic body structure which may include a cup portion ll and a tubular portion 13. The cup portion ll contains a -quantlty of refractory cement.14 which supports in protruding relation with the cup.ll a connector. electrode 15 which is connected at the end embedded in the refractory cement l4 with an electrical.conductor 16 having an end I ~LZ(~8Z~
. ' .
portion i6a bent over through a notch 13a in the tubular portion~ 13 in order to provide a plug-in contact ~or the I .
- connector electrode 15.
An electrolyte cell electrode structure 17 is also supported by the re~ractory cement 14 in a manner to extend.outwardly there~rom in substantially parallel relation to the connector electrode 15. The cell structure 17 is comprised o~ a closed end tube 18 made o~ a material suitable for use as a solid electrolyte which for oxygen may be calcium stabllized z~rconium oxide. The tube 18 . contains a small mass 20 o~ a reference material in the .
~orm of a powder. When the element.to be measured is oxygen, a re~erence partial pressure o~ oxygen may be provided by a powdered metal and a stable oxide thereo~g such as chromium.in powdered form mixed with chromic oxide powder. In order to provide.for a high speed o~ response ~or the cell? it has been ~ound that the mass 20 o~
re~erence material should be kept small and should not more than 1/8th o~ an.inch o~ the tube 18. ~.urther to enhance the speed of response, and to provide the desired stability, it has been ~ound that the ratio o~ chromium powder to chromic oxide powder is ~uite critical and should be substantially 75~ chromium and 25% chromic oxide.
The mixture of chromium-chromic oxide ~orming the small mass 20 is preferably tamped in place in order to effeot a good mecha~ical and electrical contact in the end . . .
I '`'' 1.2()8Z8~ ) of the tube 18. To insure that .the.'chr'omium-chr'om~c oxide retains its contact with the end of the tube''18, a thin layer of fibrous alumlnum oxide 21l is pressed firmly against the exposed surface of the powder mass.20. To reduce the tlme for the partial pressure of oxygen produced.by,the mass 20 of reference material to reach a stable equ~libr~um value and thus to insure a high speed.o~ response from the cell, .
that portion of the tube 18 that is not ~illed w~th'the small mass 20 and the layer 24 should contain a filler 21 to reduce substantially to zero the air contained ln the tube 1.8.
; .
While any suitable dry filler material may be used, ,~
it has been found that a cell having a high speed of response can be obtained.by introducing into the tube 18 above the ' ,:
layer 24 a.quantity of aluminum oxide which preferably is ,:
introduced into the,tube 18 in powdered form to provide the filler 21. When the aluminum oxide powder is used,as the ~iller 21 to eliminate air in the tube 18, the powder should be quite :fine or at least contain a percentage of , fine powder to eliminate interstlces that could form air , pockets within the filler 21. The elimination of air within , the tube 18 may also be accomplished in other ways by inserting other types of powder, or by inserting within . ~ the tube 18 a solid materia]. such as quartz or ~ycor, or I.
.' utilizing a supercooled liquid to constitute the ~iller 21. ' Whatever substance is.used to fill the void within the tube 18 above the small mass 20 and layer 24, there must be provided a passageway to permit a conductor 22 to pass .~ k ,.
. .' . -4- I .
. I
I ( ~ ~zO~g7 ,,) ~ LF 2791 .
. ` , ' , through the lengkh of the tube 18 to make an electri.cal connection to the inner sur~ace of the electrolyte tube 18.
This electrical connection may be completed ~rom the . conductor 22 to the inner surrace o~ the tube 18 by way of the small mass 20 o~ the reference material. The end of the tube 18 with the conductor 22 in place is preferably sealed by an epoxy or other suitable cement 19 which serves to retain the aluminum oxide powder 21 and the mass 20 of the re~erence electrode in position. ¦
. , '', The electrical connection to the inner sur~ace of the electrolyte tube l8 is completed by way of the conductor 22 and.a conductor 23 which.is connected to the conductor 22 at a point submerged in the re~ractory cement . 14. The conductor 23 extends upwardly into tubular portion 13 and has a terminal end 23a bent in a conventional manner through a slot or notch 13b to ~orm a plug-in contact for the cell electrode structure 17. ~ metal cap, not shownl serves to protect the electrode structures prior to and during the time the device 10 is being immersed to a sub-surface level in a bath Or molten steel.
While there has been described an lmmersion device.comprising an oxygen determinlng.cell,.it is to be understood.that in practice such a cel-l is generally used in combination with other devices, such as, ~or example~
. ~amplers,temperature measuring devices, and thermal arrest . .
. ~`' , , .
.. ` -5- ` .
.." , .
2(~8 LF 27gl analysis deviaes~ combined into a single unlk for .
simultaneous immersion into the molten metal.
. Cells constructed in accordance with the above : teachings have responded rapidly upon.immersion in molten steel achieving full output within ~our seconds. This is a significant improvement over the response o~ the devices o~ the prior art which have required ten seconds, Because of the speed of response of the cell.of this inventlon, it is possible to use a cardboard tube having a thinner wall and thus provide a device that is easier to handle and less expensive to manufacture without in any way sacrificing the performance o~ the oxygen : : :
. : ;
~:
,` ' ' ~.
. -6- : ~
. .
. ,.
simultaneous immersion into the molten metal.
. Cells constructed in accordance with the above : teachings have responded rapidly upon.immersion in molten steel achieving full output within ~our seconds. This is a significant improvement over the response o~ the devices o~ the prior art which have required ten seconds, Because of the speed of response of the cell.of this inventlon, it is possible to use a cardboard tube having a thinner wall and thus provide a device that is easier to handle and less expensive to manufacture without in any way sacrificing the performance o~ the oxygen : : :
. : ;
~:
,` ' ' ~.
. -6- : ~
. .
. ,.
Claims (6)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fast responding oxygen cell for immersion into molten metal for the determination of dissolved oxygen in said molten metal comprising:
a sheath of solid electrolyte closed at one end and open at the other end;
a mass of oxygen reference material in said closed end of said sheath;
electrical conducting means extending through said sheath from said mass of oxygen reference material and extending out of said open end of said sheath; and filler means within said sheath to fill the open space within said sheath to substantially exclude all of the air from the space inside said sheath.
a sheath of solid electrolyte closed at one end and open at the other end;
a mass of oxygen reference material in said closed end of said sheath;
electrical conducting means extending through said sheath from said mass of oxygen reference material and extending out of said open end of said sheath; and filler means within said sheath to fill the open space within said sheath to substantially exclude all of the air from the space inside said sheath.
2. The cell of claim 1, wherein the solid electrolyte is calcium stabilized zirconium oxide.
3. The cell of claim 1, wherein the oxygen reference material occupies not more than 1/8" in said closed end of said sheath.
4. The cell of claim 1, wherein the oxygen reference material is powdered chromium-chromic oxide mixture with the mixture comprising 75% chromium and 25% chromic oxide.
5. The cell of claim 1, including sealing means applied to said open and of said sheath to retain said filler means within said sheath.
6. The cell of claim 1, wherein said oxygen reference material extends less than 1/8" from the closed end of said sheath, and further including holding means for holding said reference material into intimate contact with said closed end of said sheath.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US34634782A | 1982-02-05 | 1982-02-05 | |
| US06/346,347 | 1982-02-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1208287A true CA1208287A (en) | 1986-07-22 |
Family
ID=23358969
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000420891A Expired CA1208287A (en) | 1982-02-05 | 1983-02-04 | High speed oxygen sensor for molten metals |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS58139060A (en) |
| AU (1) | AU1039583A (en) |
| BE (1) | BE895720A (en) |
| BR (1) | BR8300568A (en) |
| CA (1) | CA1208287A (en) |
| DE (1) | DE3303851A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3444474A1 (en) * | 1984-12-06 | 1986-06-12 | Ferrotron Elektronik Gmbh | FESTELEKTROLYT SUBMERSIBLE PROBE |
| JPH0632614Y2 (en) * | 1985-10-14 | 1994-08-24 | 東京窯業株式会社 | Sensor element of hydrogen sensor for molten metal |
| US5902468A (en) * | 1996-06-14 | 1999-05-11 | Heraeus Electro-Nite International N.V. | Device for conducting electrochemical measurements in glass or salt melts |
| DE19623683C1 (en) * | 1996-06-14 | 1997-11-13 | Heraeus Electro Nite Int | Device for carrying out electrochemical measurements in glass or salt melts |
| DE19623687C1 (en) * | 1996-06-14 | 1997-10-16 | Heraeus Electro Nite Int | Inexpensive precision electrochemical measuring probe |
-
1983
- 1983-01-12 JP JP58002384A patent/JPS58139060A/en active Pending
- 1983-01-14 AU AU10395/83A patent/AU1039583A/en not_active Abandoned
- 1983-01-27 BE BE0/209981A patent/BE895720A/en not_active IP Right Cessation
- 1983-02-04 CA CA000420891A patent/CA1208287A/en not_active Expired
- 1983-02-04 BR BR8300568A patent/BR8300568A/en unknown
- 1983-02-04 DE DE19833303851 patent/DE3303851A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| BR8300568A (en) | 1983-11-08 |
| BE895720A (en) | 1983-07-27 |
| JPS58139060A (en) | 1983-08-18 |
| DE3303851A1 (en) | 1983-08-18 |
| AU1039583A (en) | 1983-08-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |