EP2823293A1 - Sonde pour la mesure en continu de la saturation en oxygène dans des bains de métal fondu - Google Patents

Sonde pour la mesure en continu de la saturation en oxygène dans des bains de métal fondu

Info

Publication number
EP2823293A1
EP2823293A1 EP13702237.2A EP13702237A EP2823293A1 EP 2823293 A1 EP2823293 A1 EP 2823293A1 EP 13702237 A EP13702237 A EP 13702237A EP 2823293 A1 EP2823293 A1 EP 2823293A1
Authority
EP
European Patent Office
Prior art keywords
probe
probe according
tubular anode
metal
tin
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.)
Withdrawn
Application number
EP13702237.2A
Other languages
German (de)
English (en)
Inventor
Andreas Kasper
Amelie NEUMANN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Glass France SAS
Compagnie de Saint Gobain SA
Original Assignee
Saint Gobain Glass France SAS
Compagnie de Saint Gobain SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Saint Gobain Glass France SAS, Compagnie de Saint Gobain SA filed Critical Saint Gobain Glass France SAS
Priority to EP13702237.2A priority Critical patent/EP2823293A1/fr
Publication of EP2823293A1 publication Critical patent/EP2823293A1/fr
Withdrawn legal-status Critical Current

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
    • G01N27/4118—Means for protecting the electrolyte or the electrodes

Definitions

  • the invention relates to a probe for the continuous measurement of the oxygen concentration in molten metals, their use and a method of measurement.
  • Glass is predominantly produced in the endless-continuous float glass process.
  • a molten glass is passed to a bath of liquid metal, in particular tin, and spreads evenly on the surface of the bath due to their lower density.
  • This allows the production of high quality base glass with particularly smooth surfaces.
  • Due to the high oxygen affinity of the tin the process must be carried out under inert conditions.
  • the system must be kept under a slight overpressure of forming gas. A complete exclusion of oxygen is hardly possible in production.
  • the atmospheric oxygen disturbs the production process massively.
  • the Dross causes serious quality problems in the form of glass adhesions.
  • tin oxide (SnO) forms at the hot end of the bath at about 1000 ° C., which is extremely volatile at the present temperatures and condenses in colder areas of the system, such as the bath cover.
  • tin disubstituted tin (II) oxide to liquid tin and tin (IV) oxide. Dripping tin and falling cassiterite particles cause surface defects in the still soft glass surface.
  • the undesirable effects can be reduced by increasing the hydrogen concentration in the forming gas.
  • the tin oxide is reduced to liquid tin.
  • the reduction occurs only at the surface of the particles and therefore only slowly, resulting in very long decay times of the disturbance.
  • An early discovery of the disorder is therefore enormously important.
  • the oxygen concentration of the molten metal must be constantly monitored in the various temperature ranges of the system.
  • probes In modern measuring methods for the in-situ determination of the oxygen content in liquid tin, probes are used which allow a direct monitoring of the local oxygen concentration.
  • US 3,625,026 A discloses a probe for determining the oxygen concentration in molten metals.
  • the probe comprises a cathode of a doped zirconia cylinder as the oxygen ion conducting solid electrolyte, and an anode of platinum outside the cathode with a rhenium tip protruding into the tin.
  • the different oxygen concentrations inside and outside the solid electrolyte create an electrochemical potential.
  • the oxygen concentration in the liquid tin is to be determined by measuring the voltage generated.
  • DE 102004022763 B3 discloses a probe whose solid electrolyte cylinder is coated with a mixture of zirconium silicate and a fluoride. As a result, the measurement of other impurities in molten metal is possible.
  • EP 0562801 B1 discloses a further development of the probe type described in US 3,625,026. Only the probe tip consists of zirconium dioxide, while the other probe body is made of a different heat-resistant material. Furthermore, a thermocouple is inserted in the probe tip.
  • the high fragility and temperature sensitivity of the zirconia probe body is a disadvantage of the described probe. Zirconia has over a high thermal expansion coefficient. For this reason, a so-called thermal shock often occurs when inserting the probe and the probe is completely destroyed. When removing the probe from the molten metal can also occur a thermal shock. Therefore, the probe can not be removed without destruction after installation and used elsewhere.
  • the lifetime of the probe is very limited, since in the float bath environment rapid aging of the probe material takes place.
  • the crystal structure of the zirconia is stable at the temperatures prevailing in the molten metal. However, along the longitudinal direction of the probe, there is a temperature gradient. The upper part of the probe protrudes from the liquid metal and has a lower temperature. At a temperature of about 400 ° C, the crystal structure of the zirconia converts to a second crystalline form. Along the longitudinal direction of the probe thus occur on two different crystal structures. The change in the crystal structure also causes a change in the volume, whereby high material loads occur at the junction of the two crystal structures. At this point, the probe material breaks frequently.
  • the probe described in EP 0562801 Bl of doped zirconia has an improved temperature resistance, since the zirconia tip completely immersed in the liquid tin. Thus, the described crystal structure change along the longitudinal axis of the probe is prevented.
  • the hitherto known probes have an anode with rhenium, tungsten, molybdenum and alloys thereof. Rhenium is preferably used as the anode material.
  • Rhenium is preferably used as the anode material.
  • the components which come into contact with liquid tin must be insoluble in this. This applies only to the refractory metals of the sixth and seventh subgroups of the periodic table. These are produced in the sintering process due to their high melting points.
  • the sintering aids used are preferably cobalt, nickel and alloys thereof which are readily soluble in the liquid tin. Consequently, the sintering aids are dissolved out of the material over time, which leads to the disintegration of the components.
  • the object of the invention is to provide a stable and reversible measuring unit, which allows a continuous monitoring of the oxygen concentration in molten metals.
  • the probe according to the invention for the continuous measurement of oxygen saturation in molten metals comprises a tubular anode in the interior of which a reference electrode is contained as a cathode.
  • the outer tubular anode thus protects the internal thermocouple and the cathode against mechanical stress.
  • tilting can be particularly easy.
  • the reference electrode comprises a deflection electrode immersed in an oxygen ion conducting solid electrolyte cylinder.
  • the solid electrolyte cylinder is filled with a reference material.
  • the tubular anode and the reference electrode lead-off electrode contain silicon carbide, more preferably silicon-doped silicon carbide. Silicon-doped silicon carbide has a low electrical resistance and is therefore particularly suitable.
  • the probe according to the invention is distinguished from the common probes by a high mechanical and chemical stability as well as a resistance to thermal shock.
  • the tubular anode may have both a closed wall surface and one or more slots along the longitudinal axis.
  • the slots generally occupy 5% to 70%, more preferably 10% to 50%, of the circumference of the tubular anode.
  • the opening of the tube anode serves for the entry of the molten metal into the interior of the anode and is preferably arranged at its lower end.
  • the opening is preferably slot-shaped and preferably has a width of 2 mm to 15 mm, particularly preferably 3 mm to 8 mm.
  • the advantages of a slot-shaped opening over other designs are mainly due to their ease of manufacture. However, other embodiments of the opening are conceivable. It must only be ensured that the liquid tin of the metal bath can enter the probe and flow past the reference electrode. For semi-open tubular anodes or channel-shaped anodes, such an opening is not necessary.
  • the solid electrolyte cylinder preferably contains zirconia, more preferably yttria-stabilized zirconia.
  • the solid-state electrolyte cylinder may also contain zirconium dioxide and / or thorium dioxide or zirconium dioxide and / or thorium dioxide doped with calcium oxide, magnesium oxide and / or yttrium oxide.
  • Zirconia or thorium dioxide serves as a diaphragm and allows the migration of oxygen ions between the molten metal and the reference material.
  • the solid electrolyte cylinder is sealed so that the reference material does not evaporate and does not react with the hydrogen of the float bath atmosphere.
  • the solid electrolyte cylinder has an opening through which pressure can escape from its interior.
  • the reference material contains a metal, preferably Sn, Ni, Cu, Cr and a mixture of this metal and its oxide, preferably Sn / SnO 2 , Ni / 10, Cu / Cu 2 O, Cr / CrO.
  • the mixing ratio of metal / metal oxide is between 95/5 weight percent to 65/35 weight percent, preferably between 75/25 weight percent to 85/15 weight percent.
  • the reference electrode thus receives a constant and accurate defined electrochemical potential.
  • Sn / Sn0 2 is preferred as the reference material, since the potential difference is zero at the oxygen saturation critical for tin oxide deposition.
  • the temperature measurement is preferably carried out by means of a commercially available thermocouple, which is surrounded by a protective cover made of a thermostable material.
  • the protective sheath preferably contains AI2O 3, ZrC> 2, quartz glass, SiC, SiSiC, S1 3 N 4, TiB 2, BN and / or mixtures thereof, most preferably AI2O. 3
  • the electrochemical potential is temperature dependent. Consequently, the measurement of the temperature of the tin bath, to avoid deviations, takes place spatially close to the location of the potential measurement.
  • the tubular anode and the discharge electrode of the reference electrode are connected to a contact wire via a conductive metal paste.
  • the conductive metal paste is applied and baked on the electrode portion wrapped with the contact wire. This ensures the permanent electrical contact between the electrode and the contact wire.
  • the metal paste preferably contains silver, gold, platinum, palladium, copper, nickel, manganese, iron and / or mixtures or alloys thereof, particularly preferably silver.
  • the invention further comprises a method for measuring the oxygen saturation in molten metals with the probe according to the invention.
  • the probe is immersed in the molten metal through the installation opening of the float glass plant.
  • the liquid metal enters the probe through the opening of the tubular anode.
  • the probe is attached via a screw in the mounting hole.
  • the anode contacts the float bath casing and is grounded.
  • the generated voltage between anode and reference electrode and the temperature of the liquid metal is measured.
  • the dimensions of the probe holder correspond to those of the usual thermocouples, so that no structural changes to the use of the probe according to the invention are necessary.
  • Special embodiments of the measuring method include the measurement of the oxygen concentration in tin baths of float glass plants.
  • the various temperature ranges of the system are around 600 ° C to 1000 ° C.
  • the solubility of the oxygen in the liquid tin is dependent on the bath temperature. At lower temperatures, supersaturation of the molten metal with oxygen occurs more quickly. Especially at the end of the system with about 600 ° C a measurement of the oxygen concentration is therefore important, because here the fastest supersaturation with oxygen occurs.
  • the probe according to the invention allows monitoring in the entire temperature range of 600 ° C to 1000 ° C.
  • the invention further includes the use of the probe according to the invention for measuring the oxygen concentration in molten metals.
  • the probe is preferably used in metal melts in a bath for the production of glass, particularly preferably in tin baths in float glass plants.
  • the measurement of the oxygen concentration in tin baths for glass production is of particular importance, since too high an oxygen content in the molten metal interferes with the production process.
  • the limit of solubility of the oxygen in the liquid metal is exceeded, the formation of tin dioxide begins. This leads to serious glass defects.
  • the probe according to the invention has a higher thermal shock resistance and lifetime. This makes a permanent in-situ measurement of the oxygen concentration possible.
  • the probe of the invention is assembled so that according to the invention, the internal components are only loosely inserted into the outer tubular anode. As a result, self-destruction is excluded by the different thermal expansion of the various components in normal operation. It must also be ensured in this process step that no tin-containing vapors (Sn, SnO, SnS) get inside the probe, because they would significantly affect the life of the probe by forming undesirable chemical compounds. These unwanted chemical compounds would lead to embrittlement and breakage of the contact wires and the destruction of the solder contacts within a short time. From the point of view of the longest possible duration of use of the exact assembly of the probe is therefore very essential.
  • FIG. 1 is a schematic view of the probe on
  • Figure 2 is a schematic external view of the outer contacting of the probe
  • Figure 3 is a cross-section A-A 'of the probe in Figure 1
  • Figure 4 is a schematic view of the probe used in the float bath
  • Figure 5 is a flow chart of the method according to the invention.
  • FIG 1 shows a schematic view of the inventive probe (15).
  • the probe (15) comprises a tubular anode (3), a reference electrode (4) and a thermocouple (1), the reference electrode (4) and the thermocouple (1) being disposed inside the tubular anode (3).
  • the thermocouple (1) is surrounded by a protective cover (2).
  • the tubular anode (3) has at its lower end an opening (5) through which the liquid tin of the tin bath (6) enters the tubular anode (3).
  • the reference electrode (4) contains a discharge electrode (4.1), which dips into a solid electrolyte cylinder (4.2).
  • the solid electrolyte cylinder (4.2) is filled with a reference material (4.3, 4.4) containing a mixture of tin and tin dioxide (4.3) and tin (4.4).
  • a reference material 4.3, 4.4
  • FIG. 2 shows a schematic external view of the probe (15).
  • the contacting of the tubular anode (3) is carried out by burning a conductive metal paste (9) and wrapping this anode portion with the contact wire of the anode (7.1).
  • FIG. 3 shows a cross-section of the probe (15) in the tin bath (6) along the line A-A '.
  • liquid tin enters the inside of the tubular anode (3).
  • the thermocouple (1) is surrounded by a protective cover (2) and does not directly contact the tin bath (6).
  • the solid electrolyte cylinder (4.2) is sealed and immersed in the tin bath (6).
  • the discharge electrode (4.1) dips into the interior of the solid electrolyte cylinder (4.2) and is not in direct contact with the tin bath (6).
  • FIG. 4 shows a schematic view of the inventive probe (15) used in a float glass plant.
  • the probe (15) is fitted in the mounting hole (13) for thermocouples, wherein the potential measurement via electrical connections (14) takes place while at the same time grounding with the float bath casing (11).
  • the inner components of the probe (15) float freely in the tin bath (6).
  • On the surface of the tin bath (6) is the solidifying glass melt (10).
  • the gas atmosphere within the float bath casing (11) includes forming gas (12).
  • FIG. 5 shows a flow chart of the method according to the invention.
  • the probe (15) is introduced through the installation opening (13) of the float glass line into the tin bath (6).
  • the probe (15) is connected to the ground (8) with the float bath casing (1 1).
  • the temperature and the voltage generated are measured.
  • the probe (15) was inserted at the cold end of the float glass plant at a temperature of 600 ° C in the tin melt.
  • the probe (15) through the mounting hole (13) of the float bath casing (1 1) was introduced into the system.
  • the probe (15) was initially inserted only a short distance into the system so that it did not touch the tin bath (6) yet.
  • the probe (15) was first left in this position for a short time and then further advanced in sections into the tin melt. This allowed the probe (15) to slowly adjust to the temperature of the float bath atmosphere.
  • the inserted probe (15) was fastened by a screwing device with the tubular anode (3) grounded to the float bath casing (11).
  • Comparative Example 2 Measurement of the oxygen concentration in a tin melt with a probe according to the prior art A probe from the model Continox from Heraeus Electro-Nite was used as described for the probe according to the invention in the float glass plant and the oxygen concentration was measured.
  • Table 1 shows the life of the inventive probe (Example 1) and the probe according to the prior art (Comparative Example 2) in comparison.
  • the probe of the prior art is often destroyed by the first insertion of the probe into the system by thermal shock, whereby the short lifetimes of a few minutes come to pass. If the probe known from the prior art could be used successfully in the system, a maximum service life of up to 1.5 years was achieved in individual cases. The fiction, contemporary probe could be successfully used in all cases in the system without a thermal shock occurred. However, the maximum lifetime of the probe according to the invention is not yet known, since it has not come to any failure of the probe.
  • the probe according to the invention has already been heated in total from room temperature to the float bath temperature of 600 ° C. 20 times without damaging the probe.
  • the probe according to the invention is insensitive to thermal shock and thus facilitates a long-term measurement of the oxygen concentration. Such constant monitoring of the oxygen concentration allows a quick detection of the disturbance.
  • the probe of the invention is suitable for the various temperature ranges of the system from 600 ° C to 1000 ° C. Thus, several probes can be used along the system. As a result, the fault can not only be found very quickly, but also the system section in which the fault is present can be located.

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  • 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)

Abstract

L'invention concerne une sonde pour la mesure en continu de la saturation en oxygène dans des bains de métal fondu, comprenant : a) une anode tubulaire (3) dotée d'au moins une ouverture (5) pour la réception du métal liquide provenant d'un bain de métal (6) ; b) une électrode de référence (4) disposée à l'intérieur de l'électrode tubulaire (3), comprenant une électrode de décharge (4.1), laquelle plonge dans un cylindre d'électrolyte solide (4.2) conducteur d'ions oxygène, le cylindre d'électrolyte solide (4.2) conducteur d'ions oxygène étant rempli d'un matériau de référence (4.3, 4.4) ; c) un capteur thermométrique (1) disposé à l'intérieur de l'électrode tubulaire (3) ; et d) l'anode tubulaire (3) et l'électrode de décharge (4.1) contenant du carbure de silicium.
EP13702237.2A 2012-03-05 2013-02-05 Sonde pour la mesure en continu de la saturation en oxygène dans des bains de métal fondu Withdrawn EP2823293A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP13702237.2A EP2823293A1 (fr) 2012-03-05 2013-02-05 Sonde pour la mesure en continu de la saturation en oxygène dans des bains de métal fondu

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP12158007 2012-03-05
PCT/EP2013/052201 WO2013131697A1 (fr) 2012-03-05 2013-02-05 Sonde pour la mesure en continu de la saturation en oxygène dans des bains de métal fondu
EP13702237.2A EP2823293A1 (fr) 2012-03-05 2013-02-05 Sonde pour la mesure en continu de la saturation en oxygène dans des bains de métal fondu

Publications (1)

Publication Number Publication Date
EP2823293A1 true EP2823293A1 (fr) 2015-01-14

Family

ID=47631447

Family Applications (1)

Application Number Title Priority Date Filing Date
EP13702237.2A Withdrawn EP2823293A1 (fr) 2012-03-05 2013-02-05 Sonde pour la mesure en continu de la saturation en oxygène dans des bains de métal fondu

Country Status (2)

Country Link
EP (1) EP2823293A1 (fr)
WO (1) WO2013131697A1 (fr)

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL133730C (fr) * 1965-04-08
GB1277751A (en) 1969-04-17 1972-06-14 Pilkington Brothers Ltd Method of and apparatus for removing dissolved oxygen from molten tin
US3642599A (en) * 1969-05-12 1972-02-15 Kennecott Copper Corp Solid electrolyte probe for determining the oxygen content of molten materials
US3864231A (en) * 1972-01-31 1975-02-04 Metallurgie Hoboken Apparatus for measuring in a continuous manner oxygen in a molten metal
GB9206367D0 (en) 1992-03-24 1992-05-06 Pilkington Plc Oxygen measuring probe
JP3073926B2 (ja) * 1996-04-20 2000-08-07 株式会社フジクラ 溶融金属中の酸素連続測定用プローブ及び測定装置
GB0107724D0 (en) * 2001-03-28 2001-05-16 Foseco Int Electrochemical sensor
DE102004022763B3 (de) 2004-05-05 2005-09-15 Heraeus Electro-Nite International N.V. Messeinrichtung zur Bestimmung der Sauerstoffaktivität in Metall- oder Schlackeschmelzen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2013131697A1 *

Also Published As

Publication number Publication date
WO2013131697A1 (fr) 2013-09-12

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