CN101935209A - Heating electrode for melting tank of glass kiln - Google Patents

Abstract

The invention discloses a heating electrode for a melting tank of a glass kiln, which reduces cost and solves the technical problem that the loss of an electrode material causes defects of glass liquid at the same time. The heating electrode adopts a technical scheme that: electric fluxing electrodes are symmetrically arranged on the tank walls of the melting tank; stannic oxide servers as the base stock of the electrodes; and an additive consisting of 0.8 to 2.0 percent of antimonous oxide (Sb2O3), 0.4 to 1.0 percent of cerium dioxide (CeO2) and 0.4 to 1.0 percent of zinc oxide (ZnO) is added into the stannic oxide. The heating electrode for the melting tank of the glass kiln has the advantages of greatly reducing the cost of electric fluxing devices, increasing the heat absorption ratio of electric fluxing in the glass liquid, optimizing the distribution of a power wire in the glass liquid and reducing the generation ratio of defects of platinum particles.

Description

A kind of heating electrode that is used for the glass furnace melting pool

Technical field

The invention belongs to the manufacturing field of TFT-LCD glass substrate, relate to the support equipment in glass furnace, especially for the glass furnace melting pool, be the heating electrode of base-material with the tindioxide.

Background technology

In the liquid crystal glass base processing procedure, the kiln dissolving tank is the equipment that glass is melted.Liquid-crystalline glasses belongs to borosilicate glass, its feed composition decision, and this glass metal needs higher melting temperature (Tm).The temperature of flame meeting heating for dissolving pond top glass liquid, the glass metal bottom is because far away apart from flame space, and temperature is lower.The thermal conductivity of glass metal and mobile relatively poor makes that the glass metal at the bottom of the dissolving tank pond keeps lower temperature and long residence time.This next step clarification to glass metal is unfavorable, and the long residence time can change the component of dissolving tank bottom glass liquid simultaneously.

Electric glass melting is that electric current is introduced in the glass metal by electrode, and the glass metal that energising back two electrodes are asked produces joule heating under the effect of alternating-current, thereby reaches fusing and thermoregulated purpose.Why glass metal has electroconductibility, and the glass intermediate ion that mainly is based under the liquid state moves under the driving of electrical forces.1902, the Wal gram was got permission a basic patent, and its content is that utilization is to the regulation and control of ionic state electric current, by the preparing glass charge heat effect molten glass that ionic current produces under mixes liquid.Along with the updating and develop of furnace design for glass electric melting and electrode, this electricity fusing-aid method is used widely.

The advantage of the electricity fusing-aid heating technique of glass furnace is:

1), improves melting rate significantly.Melting rate can improve 60%, even 100%.

2), improve the refining quality of glass.Under any circumstance adopt electricity fusing-aid can both improve the quality of glass.This is to have improved because strengthened the mobile homogeneity of glass metal that makes of glass metal.

3), flexible load.The tank furnace that adopts electricity fusing-aid to heat can be regulated the load of tank furnace according to market demand rapidly.

4), the electricity fusing-aid device is particularly useful for high melting glass.TFT-LCD glass is high-boron-silicon glass, belongs to a kind of of high melting glass.After being arranged in the electrifying electrodes of pool wall, the glass metal that is in molten state is a conductor.According to the heat effect principle of resistance, two interelectrode glass metals will generate heat.Simultaneously, because the fringing effect of electrode tip, near the temperature of glass liquid the electrode tip is the highest, herein temperature even can reach more than 1700 ℃.Because the difference of proportion has just formed glass metal stream near electrode, the glass of dark each layer of direction in pond has all fully been participated in this and has been flowed, thereby has eliminated the problem that the high-boron-silicon glass layering is brought.In addition, electrode tip " heat release " phenomenon in glass metal and the glass metal stream that produces have therefrom improved the temperature of bottom glass metal, have accelerated the dissolution rate of quartz particles, have promoted the clarification and homogenization of glass.

Generally the material as the electricity fusing-aid electrode has: Graphite Electrodes, molybdenum electrode, stannic oxide electrode and platinum electrode.

Common stannic oxide electrode generally is used for 1500 ℃ of electrically heated with interior glass because of being subjected to the restriction of tin dioxide material performance.TFT-LCD glass is a kind of high-melting-point borosilicate glass, and its temperature of fusion is about 1600 ℃.The caking power of traditional stannic oxide electrode is poor, normal temperature resistance is very big, density is not enough, contain the deleterious composition of TFT-LCD glass metal in non-refractory and the hotchpotch, the electrode that is used for electricity fusing-aid is because of joule heating effect, working temperature is 1650～1700 ℃, can not directly apply to the electrically heated of such glass.Usually adopt platinum electrode that glass metal is carried out electrically heated in the industry.Because platinum electrode under the driving of power frequency electricity, can produce sputtering phenomenon in glass metal, need to use expensive intermediate frequency power supply.Simultaneously, the restriction that used by platinum electrode, electricity fusing-aid power only accounts for glass metal and absorbs 5～12% of total power.Platinum electrode is distributed in bottom or the pool wall and the bottom of glass furnace dissolving tank, and only the segment glass liquid between counter electrode heats.Power line length differs greatly between electrode, and is not only inhomogeneous to the heating of glass metal, and easily produces the excessive loss of platinum electrode because of the concentrated distribution of current density in the end of platinum electrode.Platinum electrode not only costs an arm and a leg, and the platinum particle that consumption of electrode produces also can cause product defects.

Summary of the invention

The objective of the invention is when reducing cost, to reduce or eliminate the technical barrier of the defective that the electrode materials loss causes glass metal, having designed a kind of glass furnace melting pool that is used for mixes as heating electrode with tindioxide and additive, traditional stannic oxide electrode is transformed, in the selection of electrode hotchpotch, be optimized, select to be suitable for the electrically heated of TFT-LCD glass metal, not produce glass defect and can to promote the clarifying hotchpotch of glass metal.By the design of rational electrically heated loop, make the power line uniform distribution in the glass metal, increase the electrically heated proportion simultaneously, make it to reach the effect of mixed melting.

The present invention for realizing the technical scheme that goal of the invention adopts is, a kind of heating electrode that is used for the glass furnace melting pool, above electricity fusing-aid electrode symmetry is installed on the pool wall of melting pool, above-mentioned electrode is base-material with the tindioxide and adds the additive that comprises that antimonous oxide, cerium dioxide, zinc oxide proportioning form that in tindioxide the composition percentage composition of above antimonous oxide, cerium dioxide, zinc oxide is:

Sb ₂O ₃：0.8％～2.0％；CeO ₂：0.4％～1.0％；ZnO：0.4％～1.0％。

Key of the present invention is traditional stannic oxide electrode is transformed, and adds antimonous oxide Sb on the basis of pure tin dioxide material ₂O ₃, with zinc oxide ZnO, improve its conductivity.Add cerium dioxide CeO simultaneously ₂, improve its Vickers' hardness and fracture toughness property, reach toughness reinforcing purpose.Simultaneously, adopt the isostatic pressing method to increase its density, reduce the erosion of glass metal counter electrode.

According to discovering: oxide compounds such as Cu, Ag, Au, Co, Ni, Fe, Mn, Zn, V, K can be used as agglomerating promotor; And oxide compounds such as As, Sb, Bi, Ta, U, Cr, Te, Nb, V, W, Th can reduce SnO ₂The resistance of electrode.

The invention has the beneficial effects as follows and to use the traditional TFT-LCD vitreous electricity heating electrode that has substituted expensive platinum electrode and intermediate frequency transformer combination of high temperature resistant 1500-1650 ℃ stannic oxide electrode, greatly reduced the cost of electricity fusing-aid device.Simultaneously, increase the ratio of the shared glass metal absorption of electricity fusing-aid heat, optimized the distribution of power line in glass metal, reduced the generation of platinum grain defect.

By add antimonous oxide, cerium dioxide, three kinds of additives of zinc oxide in tindioxide, the Vickers' hardness of electrode reaches 4.65～5.59GPa; Fracture toughness property: 2.10～2.64MPam ^1/2

The present invention is described in detail below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is the Application Example of heating electrode in the electricity fusing-aid device among the present invention.

In the accompanying drawing, the 1st, melting pool, the 2nd, electrode pair, the 3rd, transformer, the 4th, power regulating eqiupment.

Embodiment

A kind of heating electrode that is used for the glass furnace melting pool, above electricity fusing-aid electrode symmetry is installed on the pool wall of melting pool 1, above-mentioned electrode 2 is base-material with the tindioxide and adds the additive that comprises that antimonous oxide, cerium dioxide, zinc oxide proportioning form that in tindioxide the composition percentage composition of above antimonous oxide, cerium dioxide, zinc oxide is:

Sb ₂O ₃：0.8％～2.0％；CeO ₂：0.4％～1.0％；ZnO：0.4％～1.0％。

Tindioxide and antimonous oxide, cerium dioxide all are finingss of TFT-LCD glass metal, and zinc oxide is one of component of this glass metal, so harmless to glass metal.Zirconium dioxide is the main constituent of tank furnace refractory body, because density is bigger, generally gets rid of by blowdown at the bottom of the pond.

SnO ₂Conductivity own is very poor, is the n N-type semiconductorN, and current carrier is mainly the unbound electron in the lattice, unbound electron or hole distribution concentration decision conductivity.Along with the raising of free electronic concentration, SnO ₂Conductivity also with regard to corresponding raising.Therefore, the value volume and range of product of doped element can make the SnO under the liquid state ₂The conductivity that improves.

Through Sb ₂O ₃The back conductivity that mixes significantly improves, because improved SnO by doping Sb ₂Efficient carrier concentration in the lattice.Sb ₂O ₃Under certain temperature condition variation of valence can take place, by Sb ³⁺Change Sb into ⁵⁺And Sb ³⁺The state of coexistence, Sb ⁵⁺And Sb ³⁺Can be solidly soluted into SnO ²In, replace SnO ₂Sn on the lattice ⁴⁺, form two kinds of different mechanism of doping effect.If Sb ⁵⁺Replace Sn ⁴⁺, then introduce the unbound electron current carrier; If Sb ³⁺Replace Sn ⁴⁺, then form more hole.

Not as good as Sb, so Ce can not replace Sb as new additive fully, but Ce is doped with and is beneficial to raising SnO Ce to the effect that reduces resistivity ₂The mechanical property of electrode, Sb then is unfavorable for sintering, therefore replaces Sb with a spot of Ce, promptly can be helpful to the raising of electric property, also improved sintering character simultaneously.

The above-mentioned antimonous oxide and the part by weight of cerium dioxide are: 2: 1≤Sb ₂O ₃: CeO ₂≤ 5: 1.

The above-mentioned cerium dioxide and the part by weight of zinc oxide are: 4: 5≤CeO2: ZnO≤6: 5.

The total weight percent of above-mentioned antimonous oxide, cerium dioxide, zinc oxide is: 1.8%≤Sb2O3+CeO2+ZnO≤3.2%.

Add that to make the room temperature resistivity of electrode 2 behind described three kinds of compositions be 90～280 Ω cm, working temperature resistivity is less than or equal to 10 ^-2Ω cm.

When stannic oxide electrode of the present invention was used in the electricity fusing-aid device, electrode 2 symmetries were installed on the pool wall of melting pool 1, adopted the former limit three phase supply of transformer 3, the single-phase output of secondary; Between transformer 3 and electrode 2, be provided with the single-phase power regulating eqiupment 4 of independent control, and in the electricity fusing-aid device, be provided with the water cooling plant supporting with electrode 2.

In order to eliminate the power line short circuit phenomenon between homonymy pool wall adjacent electrode, the homonymy pool wall adopts the power supply of homophase power supply.The power of electricity fusing-aid is generally bigger, in order to keep three-phase equilibrium, uses one the three monophasic transformer 3 of phase transformation.The adjusting of electric current is undertaken by the single-phase power regulating eqiupment 4 of silicon controlled rectifier independently between each electrode pair.The electrode surface current density generally is controlled at 0.3A/cm ², maximum is no more than 0.5A/cm ²Electrode is provided with suitable continuous pushing away and water cooling plant.By appropriate design, electricity fusing-aid power can be in 40%～70% of glass metal absorption power.

Now enumerate specific embodiment, disclose advantage of the present invention by calculating:

For long (L) 3.6 meters, the TFT-LCD glass furnace dissolving tank that wide (W) is 1.5 meters, if four pairs of high temperature resistant stannic oxide electrodes of left and right sides pool wall uniform distribution, electrode wide (w) 60cm, high (h) 45cm, interelectrode distance (1) 1.2m, metal depth (H) 60cm.If working temperature lower-glass liquid resistivity is (ρ) 60 Ω ... cm, electrical heating power apply (P) 500kVA, and then calculation of correlation is as follows:

Resistance between electrode R=k * R ₀

Wherein k is a scale-up factor, R ₀For glass metal calculates total electrical resistance.

Glass metal calculates total electrical resistance R ₀=ρ * R

Wherein ρ is a glass metal resistivity, and 1 is interelectrode distance, and S is the glass metal sectional area.

Glass metal sectional area S=B * H

Wherein B is a glass metal width between electrode, and H is a depth of metal.

By more than, can get:

Resistance between electrode $R=k\×\mathrm{\ρ}\×\frac{1}{H\×W}$

If k gets 0.8, can get:

Resistance between electrode $R=0.8\×60\×\frac{120}{60\×360}=0.267\mathrm{\Ω}$

Inter-electrode voltage

Total current I=U ÷ R=365 ÷ 0.267=1367A between electrode

Electric current I between every counter electrode ₁=I ÷ 4=1367 ÷ 4=342A

Every counter electrode conductive cross-sectional area s=w * h=60 * 45=2700cm ²

Every counter electrode average current density

$J=I_1\&divide;s=342\&divide;2700=0.13\frac{\mathrm{<figure-callout\; id="2"\; label="A\; cm"\; filenames="HSA00000140432200011.png"\; state="\{\{state\}\}">A</figure-callout>}}{{\mathrm{cm}}^{}}$

The difference of temperature of glass liquid between each counter electrode can cause the difference of this loop glass metal resistance, and then causes the difference of voltage, electric current.Simultaneously, according to the requirement of technology, the power that applies between different electrode pairs has different requirements.Thereby maximum current density can reach 1.5～2.5 times of above calculated value.

Claims (5)

1. heating electrode that is used for the glass furnace melting pool, above electricity fusing-aid electrode symmetry is installed on the pool wall of melting pool (1), it is characterized in that: described electrode (2) is base-material with the tindioxide and adds the additive that comprises that antimonous oxide, cerium dioxide, zinc oxide proportioning form that in tindioxide above antimonous oxide, cerium dioxide, zinc oxide shared weight percent content in the stannic oxide electrode plate is:

Sb ₂O ₃：0.8％～2.0％；CeO ₂：0.4％～1.0％；ZnO：0.4％～1.0％。

2. a kind of heating electrode that is used for the glass furnace melting pool according to claim 1, it is characterized in that: the part by weight of described antimonous oxide and cerium dioxide is:

2∶1≤Sb ₂O ₃∶CeO ₂≤5∶1。

3. a kind of heating electrode that is used for the glass furnace melting pool according to claim 1, it is characterized in that: the part by weight of described cerium dioxide and zinc oxide is:

4∶5≤CeO ₂∶ZnO≤6∶5。

4. a kind of heating electrode that is used for the glass furnace melting pool according to claim 1, it is characterized in that: the total weight percent of described antimonous oxide, cerium dioxide, zinc oxide is:

1.8％≤Sb ₂O ₃+CeO ₂+ZnO≤3.2％。

5. a kind of heating electrode that is used for the glass furnace melting pool according to claim 1 is characterized in that: the room temperature resistivity of electrode (2) is 90～280 Ω cm, and working temperature resistivity is less than or equal to 10 ^-2Ω cm.

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