# US 9,751,806 B2 · High zirconia electrically fused cast refractory

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- Number: US 9,751,806 B2
- Document ID: US9751806B2
- Status: Granted
- Kind: B2
- Application number: 15/121,682
- Filed: 2015-03-02
- Published: 2016-12-15
- Granted: 2017-09-05
- Earliest claimed: 2015-02-02
- Assignees: Saint-Gobain TM K.K.
- Applicants: Saint-Gobain Tm K.K.
- Inventors: Hiroshi Sugiyama; Toshimitsu Kuboki; Itaru Hashimoto; Yasuo Misu
- Web page: https://patentgrep.com/patent/US9751806B2

## CPC

- C04B 35/484: Refractories by fusion casting
- C03B 5/43: Use of materials for furnace walls, e.g. fire-bricks
- C03C 3/064: containing boron
- C03B 5/02: in electric furnaces {, e.g. by dielectric heating (electric heating in general H05B)}
- C04B 2235/3201: Alkali metal oxides or oxide-forming salts thereof
- C04B 2235/3206: Magnesium oxides or oxide-forming salts thereof
- C04B 2235/3208: Calcium oxide or oxide-forming salts thereof, e.g. lime
- C04B 2235/3213: Strontium oxides or oxide-forming salts thereof
- C04B 2235/3215: Barium oxides or oxide-forming salts thereof
- C04B 2235/3217: Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
- C04B 2235/3225: Yttrium oxide or oxide-forming salts thereof
- C04B 2235/3244: Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
- C04B 2235/3272: Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
- C04B 2235/3281: Copper oxides, cuprates or oxide-forming salts thereof, e.g. CuO or Cu2O
- C04B 2235/3293: Tin oxides, stannates or oxide forming salts thereof, e.g. indium tin oxide [ITO]
- C04B 2235/34: Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B 2235/3409: Boron oxide, borates, boric acids, or oxide forming salts thereof, e.g. borax
- C04B 2235/3418: Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
- C04B 2235/72: Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
- C04B 2235/727: Phosphorus or phosphorus compound content
- C04B 2235/9607: Thermal properties, e.g. thermal expansion coefficient
- C04B 2235/9669: Resistance against chemicals, e.g. against molten glass or molten salts
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS

## Abstract

A high zirconia electrically fused cast refractory of high electric resistance having long time durability, less suffering from cracking during production and upon temperature rising, excellent in productivity, less forming zircon crystals even upon heating the refractory in itself and when the refractory is in contact with molten glass, generating less cracks even when undergoing heat cycles during operation of a glass melting furnace is provided. A high zirconia electrically fused cast refractory has, as chemical components, 85 to 95% by weight of ZrO2, 0.1 to less than 0.8% by weight of Al2O3, 3.5 to 10.0% by weight of SiO2, less than 0.05% by weight of Na2O and K2O in total, 0.1 to 1.5% by weight of B2O3, 0.1% by weight or less of MgO, 0.01 to 0.2% by weight of CaO, in the case where any one of BaO and SrO is contained, from 0.05 to 3.0% by weight of BaO or 0.01 to 3.0% by weight of SrO, or in the case where both of them are contained, 0.01% by weight or more of SrO and from 0.01% to 3.0% by weight in total of SrO and BaO, 0.1 to 0.7% by weight of SnO2, 0.3% by weight or less of Fe2O3 and TiO2 in total, less than 0.01% by weight of P2O5, and less than 0.01% by weight of CuO.

## Claims

### Claim 1

A high zirconia electrically fused cast refractory with higher electric resistance at high temperature and zircon crystals are less formed even upon heating a refractory in itself or heating under the condition where the refractory is in contact with a molten glass, comprising, as chemical components:
85 to 95% by weight of ZrO2
0.1 to less than 1.0% by weight of Al2O3,
3.5 to 10.0% by weight of SiO2,
less than 0.05% by weight of Na2O and K2O in total,
0.1 to 1.5% by weight of B2O3,
0.1% by weight or less of MgO,
0.01 to 0.2% by weight of CaO,
in the case where any one of SrO and BaO is contained, 0.05 to 3.0% by weight of BaO or 0.01 to 3.0% by weight of SrO, or in the case where both of them are contained, 0.01% by weight or more of SrO and 0.01 to 3.0% by weight of SrO and BaO in total,
0.01 to 0.7% by weight of SnO2,
0.3% by weight or less of Fe2O3 and TiO2 in total,
less than 0.01% by weight of P2O5, and
less than 0.01% by weight of CuO.

### Claim 2 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, comprising, as chemical components:
in the case where any one of SrO and BaO is contained, 0.05 to 1.5% by weight of BaO or 0.01 to 1.5% by weight of SrO, or in the case where both of them are contained, 0.01% by weight or more of SrO and 0.01 to 1.5% by weight of SrO and BaO in total.

### Claim 3 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, comprising, as chemical components:
4.0 to 9.5% by weight of SiO2,
less than 0.04% by weight of Na2O and K2O in total,
0.2 to 1.0% by weight of B2O3,
0.01 to 0.15% by weight of CaO,
in the case where any one of SrO and BaO is contained, 0.05 to 1.0% by weight of BaO or 0.01 to 1.0% by weight of SrO, or in the case where both of them are contained, 0.01% by weight or more of SrO and 0.01 to 1.0% by weight of SrO and BaO in total,
0.1 to 0.5% by weight of SnO2.

### Claim 4 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, comprising, as chemical components:
4.0 to 9.5% by weight of SiO2,
less than 0.04% by weight of Na2O and K2O in total,
0.2 to 1.0% by weight of B2O3,
0.01 to 0.15% by weight of CaO,
in the case where any one of SrO and BaO is contained, 0.5 to 1.0% by weight of BaO or 0.2 to 1.0% by weight of SrO, or in the case where both of them are contained, 0.2% by weight or more of SrO and 0.2 to 1.0% by weight of SrO and BaO in total,
0.1 to 0.5% by weight of SnO2.

### Claim 5 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, wherein a residual volume expansion after repetitive heating for 20 cycles is 10% or less assuming a process of rising the temperature up to 1450° C. after keeping at 600° C. for one hour and then keeping at 1450° C. for one hour being as one cycle.

### Claim 6 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, wherein a residual volume expansion is 15% or less after filling liquid crystal glass in a crucible made of a high zirconia electrically fused and cast refractory, and applying repetitive heating for 10 cycles assuming a process of rising the temperature up to 1450° C. after keeping at 800° C. for 3 hours and then keeping at 1450° C. for 3 hours being as one cycle.

### Claim 7 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, wherein a residual volume expansion is 10% or less after filling liquid crystal glass in a crucible made of a high zirconia electrically fused and cast refractory, and applying repetitive heating for 10 cycles assuming a process of rising the temperature up to 1450° C. after keeping at 800° C. for 3 hours and then keeping at 1450° C. for 3 hours being as one cycle.

### Claim 8 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, wherein an electric resistance at 1500° C. is 150 Ω·cm or higher.

### Claim 9 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, wherein an electric resistance at 1500° C. is 200 Ω·cm or higher.

### Claim 10 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, wherein, an electric resistance after heating at 1650° C. for 12 hours is 90 Ω·cm or higher.

### Claim 11 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, wherein an electric resistance after heating at 1650° C. for 12 hours is 150 Ω·cm or higher.

### Claim 12 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1 with 150 Ω·cm or higher at 1500° C. and 10% or less of residual volume expansion upon heating a refractory in itself or 15% or less of residual volume expansion upon heating under the condition where the refractory is in contact with a molten glass, comprising, as chemical components:
0.1 to less than 0.8% by weight of Al2O3,
0.1 to 0.7% by weight of SnO2.

### Claim 13 (depends on 1)

The high zirconia electrically fused cast refractory according to claim 1, which is used for a glass melting furnace.