阅读说明：本技术 具有高含量氧化锆的耐火制品 (Refractory article having high zirconia content ) 是由 伊莎贝拉·卡波迪 皮埃尔里克·法比安·维斯帕 于 2020-02-11 设计创作，主要内容包括：本发明涉及一种熔铸耐火制品,以基于氧化物的重量百分比计且总计为100％,包含：-ZrO-2：至100％的余量；-Hf-2O：<5％；-SiO-2：8.1％至12.0％；-B-2O-3：0.20％至0.90％；-Na-2O+K-2O：0.40％至0.80％；-Al-2O-3：0.3％至2.0％；-Y-2O-3：<2.0％；-Fe-2O-3+TiO-2：<0.6％；-其他物质：<1.5％。(The invention relates to a fused and cast refractory product comprising, in percentages by weight on the basis of oxides and for a total of 100%: -ZrO 2 : the balance to 100%; -Hf 2 O：<5％；‑SiO 2 : 8.1% to 12.0%; -B 2 O 3 : 0.20% to 0.90%; -Na 2 O+K 2 O: 0.40% to 0.80%;‑Al 2 O 3 : 0.3% to 2.0%; -Y 2 O 3 ：<2.0％；‑Fe 2 O 3 +TiO 2 ：<0.6 percent; -other substances:<1.5％。)

1. A fused-cast refractory product comprising, in percentages by weight on the basis of the oxides and for a total of 100%:

2. the refractory article of claim 1, wherein:

-83.0％<ZrO₂+HfO₂<92.0 percent; and/or

-8.4％<SiO₂<11.5 percent; and/or

-0.25％<B₂O₃<0.75 percent; and/or

-0.45％<Na₂O+K₂O<0.75 percent; and/or

-0.6％<Al₂O₃<1.9 percent; and/or

-0.5％<Y₂O₃<1.9 percent; and/or

-Fe₂O₃+TiO₂<0.4 percent; and/or

-other substances < 1.2%.

3. The refractory article of claim 2, wherein:

-84.0％<ZrO₂+HfO₂<90.0 percent; and/or

-8.8％<SiO₂<11.0 percent; and/or

-0.40％<B₂O₃<0.70 percent; and/or

-Na₂O+K₂O<0.65 percent; and/or

-0.8％<Al₂O₃<1.7 percent; and/or

-0.7％<Y₂O₃<1.7 percent; and/or

-Fe₂O₃+TiO₂<0.3 percent; and/or

-other substances < 1.0%.

4. The refractory article of claim 3, wherein:

-85.0％<ZrO₂+HfO₂<90.0 percent; and/or

-9.1％<SiO₂<10.8 percent; and/or

-B₂O₃<0.60 percent; and/or

-0.9％<Al₂O₃(ii) a And/or

-1.0％<Y₂O₃<1.6 percent; and/or

-Fe₂O₃+TiO₂<0.2 percent; and/or

-is different from ZrO₂、Hf₂O、SiO₂、Y₂O₃、B₂O₃、Al₂O₃、Na₂O、K₂O、TiO₂And Fe₂O₃The substance (c):<0.5％。

5. refractory article according to any one of the preceding claims, comprising, in percentages by weight on the basis of oxides:

6. refractory article according to any one of the preceding claims, comprising, in percentages by weight on the basis of oxides:

7. refractory article according to any one of the preceding claims, comprising, in percentages by weight on the basis of oxides:

8. refractory article according to any one of the preceding claims, wherein CaO + MgO + BaO + SrO < 0.60%.

9. The refractory article according to any one of the preceding claims, having the shape of a block, all dimensions of the block being greater than 10 mm.

10. A glass melting furnace comprising a block made of the refractory article according to any one of the preceding claims.

11. Glass melting furnace according to the immediately preceding claim, wherein the blocks are located in a superstructure.

Technical Field

The present invention relates to a fused refractory article having a high zirconia content and to a glass melting furnace comprising such an article.

Background

Glass melting furnaces typically include an extremely large number of refractory articles that are placed in various locations depending on their characteristics. For each part of the furnace, the article selected will be one that does not cause defects that render the glass unusable (which reduces throughput) and has a long enough withstand time for the furnace to have a satisfactory service life.

Fig. 1 schematically shows a half section of a glass melting furnace 10. Particularly distinguishable are the tank 12, the metal structure 14 and the superstructure 16.

Trough 12 for containing molten glass includes vertical sidewalls 22 and a bottom 24. The side walls 22 are typically comprised of side pocket blocks that extend the entire height of the pocket up to the upper edge 25.

The superstructure 16 generally includes an intermediate layer 18 at its base (by which the superstructure rests on the metal structure), sidewalls 26 resting on the intermediate layer, and a crown 28. Burners, not shown, are located in the side wall 26 and operate alternately. The intermediate layer 18 includes, and preferably consists of, filled tiles 20.

The upper structural member is subjected to various thermomechanical stresses. First, there is a high thermal gradient between the inside of the furnace (at a temperature of about 1500 ℃) and the outside of the furnace (at a temperature close to ambient temperature, usually due to blast cooling). This thermal gradient causes a strain of the material proportional to its thermal expansion, which therefore generates a stress (the product of this strain and the elastic modulus of the material). These components are also subject to thermal shock due to cooling of the furnace or failure of the burner system. Thus, the superstructure component must withstand cracking despite the high thermomechanical stresses.

The superstructure must also withstand corrosion from the corrosive fumes and condensates of the furnace.

To withstand these stresses, the superstructure consists of blocks made of refractory products.

In refractory articles, the clinker and the sintered mass are distinguished.

Unlike sintered masses, fused masses generally include an intercrystalline glass phase connecting the grains. Therefore, the problems encountered with sintered and fused masses and the technical solutions adopted to solve them are generally different. Thus, the compositions developed for the manufacture of sintered masses cannot a priori be used equally for the manufacture of fused masses and vice versa.

The fused mass, commonly referred to as "electrofused" or "fused-cast" mass, is obtained by melting a mixture of suitable raw materials in an electric arc furnace or by any other suitable technique. The molten material is then typically cast in a mold and then solidified. Typically, the obtained product is then subjected to a controlled cooling cycle in order to reach ambient temperature without cracking. This operation is known to those skilled in the art as "annealing".

At present, for the formation of the superstructure, use is mostly made of agglomerates, in particular of the alumina-zirconia-silica type (AZS for short) containing from 30% to 45% of zirconia.

Furthermore, fused blocks with a Very High Zirconia Content (VHZC) are known, which typically contain more than 80% or more than 85% by weight of zirconia. They are distinguished by their very high corrosion resistance and ability to not tint and create defects in the produced glass.

EP 403387 describes fused and cast products with a high zirconia content, containing 4 to 5% by weight of SiO₂About 1% of Al₂O₃0.3% sodium oxide, and less than 0.05% P₂O₅。

FR 2701022 describes fused and cast products with a high zirconia content, containing from 0.05 to 1.0% by weight of P₂O₅And 0.05 to 1.0% of boron oxide B₂O₃。

FR 2723583 describes fused and cast products having a high zirconia content, containing 3 to 8% by weight of SiO₂0.1 to 2.0% of Al₂O₃0.05 to 3.0% of boron oxide B₂O₃0.05 to 3 percent of BaO + SrO + MgO and 0.05 to 0.6 percent of Na₂O+K₂O, and less than 0.3% Fe₂O₃+TiO₂。

Frits with very high zirconia content, such as ER1195, manufactured and sold by SEFPRO corporation, are now widely used in glass furnaces. However, their high cost and their characteristics may limit their use, mainly concentrated on the blocks in contact with the glass, in particular in the areas of maximum stress of the grooves.

It is desirable to have corrosion resistance and to have a breaking strength under mechanical stress so that they are suitable for use in refractory articles in the superstructure of glass melting furnaces.

The present invention is directed to meeting this need.

Disclosure of Invention

The invention provides a fused and cast refractory product comprising, in percentages by weight on the basis of the oxides and for a total of 100%:

as will be seen in more detail in the remainder of the description, such compositions impart significant mechanical properties to the fused article in the context of the superstructure of a glass melting furnace. Tests have also demonstrated low bleed. Thus, the article according to the invention is fully suitable for use in a superstructure.

The article according to the present invention may also have one or more of the following optional features, which when consistent with and when compatible with the specific embodiments described below include:

-the total porosity of the article is less than 10%, or even less than 5%;

preferably, the oxide constitutes more than 90%, more than 95%, more than 99%, or even substantially 100% by weight of the article;

-ZrO₂+HfO₂less than 92.0%, or even less than 90.0%, or even less than 89.0%, and/or greater than 83.0%, or even greater than 84.0%, or greater than 85.0%;

-SiO₂is greater than 8.4%, or even greater than 8.5%, or even greater than 8.6%, or even greater than 8.8%, or even greater than 9.1%, and/or less than 11.5%, or even less than 11.0%, or even less than 10.8%, or even less than 10.6%;

boron oxide B₂O₃Sodium oxide Na₂O and potassium oxide K₂The sum of the contents by weight of O is greater than 0.65%, or even greater than 0.70%, or even greater than 0.75%, and/or less than 1.20%, or even less than 1.10%, or even less than 1.00%;

boron oxide B₂O₃Is greater than 0.25%, or even greater than 0.30%, or even greater than 0.35%, or even greater than 0.40%, and/or less than 0.85%, less than 0.80%, less than 0.75%, less than 0.70%, less than 0.60%, or even less than 0.55%;

-sodium oxide Na₂O and potassium oxide K₂The sum of the weight contents of O is more than 0.45 percent, and/or less than 0.75 percent and less than 0.65 percent;

-Na₂the content by weight of O is greater than 0.40%, or even greater than 0.45%, or even greater than 0.50%, and/or less than 0.80%, or even less than 0.70%, or even less than 0.60%;

-K₂o as an impurity or as a partial replacement for Na₂O, and K₂The content of O by weight is less than 0.70%, or even less than 0.60%, or even less than 0.50%, or even less than 0.40%, or even less than 0.30％；

-Al₂O₃Less than 1.9%, or even less than 1.8%, or less than 1.7%, and/or greater than 0.5%, or even greater than 0.6%, or even greater than 0.7%, or even greater than 0.9%, greater than 1.0%, or even greater than 1.1%, or even greater than 1.2%;

-Y₂O₃is greater than 0.5%, or even greater than 0.7%, or even greater than 0.9%, or even greater than 1.0%, or even greater than 1.1%, and/or less than 1.9%, or even less than 1.8%, or even less than 1.7%, or even less than 1.6%;

iron oxides and titanium oxides Fe₂O₃+TiO₂Less than 0.4%, preferably less than 0.3%, preferably less than 0.2%;

the total weight content of "other substances" is less than 1.2%, or even less than 1.0%, or even less than 0.6%, or even less than 0.5%, or even less than 0.4%;

"other substances" consist only of impurities;

-the weight content of any "other substance" is less than 0.40%, or even less than 0.30%, or even less than 0.20%;

the sum of the contents by weight of the calcium oxide CaO, the barium oxide BaO, the strontium oxide SrO and the magnesium oxide MgO is less than 0.60%, less than 0.50%, less than 0.40%, or even less than 0.30%;

-the weight content of CaO is less than 0.60%, or even less than 0.40%, or even less than 0.30%;

-a weight content of BaO of less than 0.60%, or even less than 0.40%, or even less than 0.30%, less than 0.20%, less than 0.10%, less than 0.05%, or substantially zero;

-the weight content of SrO is less than 0.60%, or even less than 0.40%, or even less than 0.30%, less than 0.20%, less than 0.10%, less than 0.05%, or substantially zero;

-the weight content of MgO is less than 0.60%, or even less than 0.40%, or even less than 0.30%;

-Ta₂O₅less than 0.20%, less than 0.10%, less than 0.05%, or substantially zero;

-Nb₂O₅is less than 0.20%, less than 0.10%, less than 0.05%, or is substantially zero.

According to a particular embodiment, the invention provides a fused cast refractory product comprising, in percentages by weight on the basis of the oxides:

according to a particular embodiment, the invention provides a fused cast refractory product comprising, in percentages by weight on the basis of the oxides:

according to a particular embodiment, the invention provides a fused cast refractory product comprising, in percentages by weight on the basis of the oxides:

the invention also relates to a method for manufacturing a refractory product according to the invention, comprising the following steps carried out in sequence:

a. the raw materials are mixed to form a feedstock,

b. the feed material is melted until a molten material is obtained,

c. casting the molten material and solidifying the molten material by cooling to obtain a refractory article,

the method is noteworthy in that the raw materials are selected such that the refractory article is in accordance with the invention.

Preferably, the minimum content of oxides or precursors of these oxides is required to be added systematically and systematically. Preferably, the content of these oxides in the other oxide sources in which they are present as impurities is considered.

Preferably, the cooling is controlled, preferably so as to be at a rate of less than 20 ℃ per hour, preferably at a rate of about 10 ℃ per hour.

The invention also relates to a glass melting furnace comprising a refractory article according to the invention, or to a refractory article manufactured or capable of being manufactured according to the method according to the invention, in particular in a region not intended to be in contact with molten glass, in particular in a superstructure, in particular in a crown.

Definition of

An article is generally referred to as "fused" when it is obtained by a process in which melting of the charge is carried out until a molten material is obtained, and then solidifying the material by cooling.

A block is an object whose overall dimensions are greater than 10mm, preferably greater than 50mm, preferably greater than 100mm, and which, unlike a layer, is obtained by a process comprising the operations of moulding and removal from a mould. The block may for example have the shape of an overall parallelepiped or a particular shape suitable for its use.

Unless otherwise stated, all oxide contents in the articles according to the invention are in weight percent on the basis of the oxides. According to the industrial practice, the weight content of an oxide of a metallic element relates to the total content of this element expressed in the most stable oxide form.

HfO₂Can not react with ZrO₂And (4) carrying out chemical separation. However, according to the present invention, HfO₂Is not intentionally added to the feed. Thus, HfO₂Only traces of hafnium oxide are indicated, such oxide always being naturally present in the zirconium oxide source in a content generally less than 5%, generally less than 2%. In a block according to the invention, HfO₂In weight percent ofLess than 5%, preferably less than 3%, preferably less than 2%. For the sake of clarity, it is possible to use "ZrO" without distinction₂Or ZrO₂+HfO₂"means the total content of zirconium oxide and trace hafnium oxide. Thus, HfO₂Not included in the "other substances".

The term "impurities" is understood to mean the inevitable ingredients introduced with the raw materials or resulting from the reaction with these ingredients. The impurities are not essential components, but are merely acceptable. For example, compounds belonging to the group of oxides, nitrides, oxynitrides, carbides, oxycarbides, carbonitrides and metallic species of iron, titanium, vanadium and chromium are impurities.

Drawings

Other features and advantages of the present invention will become more apparent upon reading the following detailed description and upon reference to the accompanying drawings, in which figure 1, described in the introductory part, schematically shows a half-section of a glass melting furnace.

Detailed Description

In the fused and cast product according to the invention, the content of ZrO is high₂The requirement of high corrosion resistance can be met without generating defects harmful to the quality of the glass.

Hafnium oxide HfO present in the article according to the invention₂Is naturally present in ZrO₂Hafnium oxide in the source. Thus, its content in the article according to the invention is less than 5%, typically less than 2%.

SiO₂The presence of (b) makes it possible in particular to form an intergranular vitreous phase capable of effectively adapting to the deformations of the zirconia skeleton. On the other hand, SiO₂Should not exceed 12% since such addition is made at the expense of zirconia content and therefore would be detrimental to corrosion resistance.

Al₂O₃Is particularly useful for stabilizing the formation of the glass phase and good castability of the molten material in the mold. However, Al₂O₃Should be limited because too high a weight content would lead to instability of the glassy phase (formation of mullite crystals), especially in the presence of boron oxides.

B₂O₃And Na₂O+K₂The simultaneous presence of O can improve the feasibility of the product. B is₂O₃Adversely affects zircon formation in the article, which adversely affects resistance to thermal cycling. Thus, boron oxide B₂O₃The weight content of (a) should be kept limited.

Preferably, Na₂O+K₂The weight content of O is limited to limit volatilization of raw materials, particularly boron oxide. In the article according to the invention, the oxide Na is considered to be₂O and K₂O has a similar effect.

In one embodiment, Na₂O content and K₂At least one of the O contents is greater than 0.30%, preferably greater than 0.35%, preferably greater than 0.40%.

According to a particular embodiment:

-SiO₂: 8.5 to 10.8 percent

-B₂O₃: 0.30 to 0.70 percent

-Al₂O₃: 1.0 to 1.8 percent

Na₂O content and K₂At least one of the O contents is greater than 0.30%, preferably greater than 0.35%, preferably greater than 0.40%.

Limiting yttrium oxide Y₂O₃In order to maintain good feasibility.

According to the invention, Fe₂O₃+TiO₂Less than 0.50%, preferably less than 0.30% by weight. Preferably, P₂O₅Is less than 0.05% by weight. In particular, these oxides are harmful and their content should be limited to trace amounts introduced as impurities with the raw materials.

"other substances" are oxide substances not listed above, i.e. other than ZrO₂、Hf₂O、SiO₂、Y₂O₃、B₂O₃、Al₂O₃、Na₂O、K₂O、TiO₂And Fe₂O₃Article ofAnd (4) quality. In one embodiment, "other substances" are limited to substances whose presence is not particularly desirable and which are typically present as impurities in the starting materials.

Preferably, the article according to the invention is in the form of a block.

The total porosity of the article according to the invention is less than 15%, or even less than 10%, or even less than 5%, or even less than 2%, or even less than 1%.

The article according to the invention can be conventionally manufactured according to steps a to c described below:

a. the raw materials are mixed to form a feedstock,

b. the feed material is melted until a molten material is obtained,

c. the molten material is solidified by cooling to obtain the refractory article according to the invention.

In step a, the raw material is selected to ensure the content of oxides in the finished product.

In step b, the melting is preferably carried out by the combined action of a relatively long arc that does not produce a reduction and a mix that promotes re-oxidation of the article.

In order to minimize the formation of nodules (nodule) of metallic appearance and to prevent the formation of slits or cracks in the final product, it is preferred to perform the melting under oxidizing conditions.

Preferably, the long arc melting process described in french patent No. 1208577 and its supplementary patents No.75893 and No.82310 is used.

The process consists in using an electric arc furnace in which an electric arc is struck between the charge and at least one electrode separate from the charge and the length of the arc is adjusted to minimize its reducing action while maintaining an oxidizing atmosphere above the molten bath and mixing the bath by the action of the electric arc itself, or by blowing an oxidizing gas (for example air or oxygen) into the bath, or by adding to the bath oxygen-releasing substances such as peroxides or nitrates.

In step c, cooling is preferably carried out at a rate of less than 20 deg.C/hour, preferably at a rate of about 10 deg.C/hour.

Any conventional method for manufacturing a zirconia-based molten article intended for application in a glass melting furnace may be used, provided that the composition of the feed material is such as to obtain an article having a composition in accordance with the composition of the article according to the invention.

In the article according to the invention, ZrO₂Substantially completely (usually more than 95% of its weight) in the form of zirconia, SiO₂And Al₂O₃Substantially completely (typically more than 95% of its weight) in the glass phase.

Examples

The following non-limiting examples are given for the purpose of illustrating the invention.

In these examples, the following raw materials were used:

an average ZrO content of 99%₂+HfO₂The zirconia of (a) is Q1,

an average SiO content of 33%₂And 66% of ZrO₂+HfO₂The zirconium sand of (2) is prepared,

an average SiO content of 99%₂Of "Sable BE01 Bedouin" (BE01 Bedouin sand) silica,

an average of 98% of B₂O₃The boron oxide(s) of (a),

an average content of 99.5% Na₂CO₃As Na₂The sodium carbonate of the source of O,

average Al content of 99%₂O₃Of the type AC34 alumina of (a),

-an average of 99% Y₂O₃Yttrium oxide of (4).

The article was prepared according to a conventional electric arc furnace melting process and then cast to obtain a block measuring 996mm x 203mm x 800 mm.

Chemical analysis of the resulting product is given in table 1; it is the average chemical analysis, given in weight percent.

Resistance to thermal mechanical stress

To investigate the ability of the article to withstand the thermomechanical stresses to which the mass of the superstructure is subjected, the inventors used the Kingery theory relating the MOR/MOE ratio to the thermal shock resistance and the Hasselman theory relating the energy to break to the thermal shock resistance. Furthermore, in linear elastic mechanics, the severity of thermomechanical stress is linked to the ratio between the modulus of rupture (MOR) and the modulus of elasticity (MOE). This ratio should be maximized, as should the energy at break, so that the article is resistant to cracking by thermal mechanical sources. The article was placed at 1000 ℃, which essentially corresponded to the temperature of the core of the block.

MOR measurement

Modulus of rupture (MOR) is for a dimension of 150X 25X 15mm³Is measured in air at 1000 c, placed in a 3-point bending assembly, in which the distance between the two lower supports is 120mm, the rate of descent of the punch (punch) providing the upper support along half of the length of the sample being equal to 0.5 mm/min. The value of MOR is the average of three consecutive measurements.

MOE measurement

To measure the MOE, the same components and displacement sensors as described for MOR were used to monitor the displacement of sample deflection and determine the MOE, i.e., the ratio between stress and elastic strain induced by the stress.

Fracture energy measurement

The energy to break is at 1000 ℃ in air for a size of 150X 25mm³And a sample having a triangular notch with a 60 angle and a base of 25mm in the middle was measured and placed in a 4-point bending assembly with a distance of 120mm between the two lower support members and 40mm between the two upper support members. The lowering rate of the upper support is equal to 20 μm/min.

Corrosion resistance measurement

4 sizes of 110X 100X 30mm by rotation (6rpm) in a furnace at 1450 deg.C³The Corrosion Resistance (CR) was measured by spraying a powder consisting of 50% cullet, 15% silica, 5% dolomite and 30% sodium carbonate at a rate of 180 grams per hour for a total of 20 kilograms. Volume of corrosion by3D scan measurements, the volume is related to the initial volume.

Exudation measurement

The bleed resistance (REx) is 100X 20mm in air³The sample of (2) is subjected to measurement. The sample was subjected to a cycle during which the sample was raised to 1550 ℃ at a rate of 100 ℃ per hour and then held at 1550 ℃ for 6 hours. REx is the percentage of the volume of silicate phase (found on the sample (increase in sample volume) or at the bottom of the crucible) that escaped from the sample after two cycles relative to the initial volume of the sample. The sample was placed at 1550 ℃, which essentially corresponds to the temperature of the surface of the block exposed to the interior of the cell.

Examples 1 and 2 correspond to conventional AZS articles and conventional products with high zirconia content, respectively.

The balance corresponding to ZrO₂+HfO₂And impurities (the content of impurities in these examples is always less than 0.5%).

[ Table 1]

	1*	2*	3	4
					SiO2	15.0	4.3	10.1	8.5
Al2O3	50.9	1.2	1.7	1.6
					Na2O	1.30	0.22	0.43	0.43
B2O3	<0.2	<0.2	0.47	0.26
					Y2O3	<0.2	<0.2	0.51	1.19
MOR/MOE	1.80	1.40	3.16	2.13
					Energy at break	0.4kJ/m2	0.5kJ/m2	4.0kJ/m2	1.2kJ/m2
CR	4.30％	ND	<0.5％	ND
					REx	4.78％	0.77％	0.71％	0.16％

Outside of the invention

The tests show that the articles 3 and 4 according to the invention have an improved resistance to thermo-mechanical stress and a higher energy at break with respect to the comparative article 2.

The articles according to the invention show an excellent degree of exudation.

It is evident that the invention thus provides an article which has significant mechanical properties in the environment of the glass furnace superstructure and low exudation in operation.

Of course, the invention is not limited to the embodiments described and shown, which are provided by way of illustration only.