Refractory products containing high-content zirconia

Abstract

Fused cast refractory products, with the weight percentage of oxides, based on the total of 100%, ZrO2: Complementary amount up to 100% HfO2: <5% SiO2: 8.0%~11.0% Al2O3: 4.0%~6.5% Na2O+K2O+B2O3: 0.40%~1.30% B2O3: <0.60% Y2O3: <1.0% Fe2O3+TiO2: <0.60% Other species: <1.0% Including, wherein the SiO2 / (Na2O+K2O+B2O3) ratio is 19.0 or less; When the Al2O3 content is 5.1% or more, the SiO2 content is 8.5% or more; The above fused cast refractory products.

Description

[Technical Field]

[0001] The present invention relates to cast refractory products having a high zirconia content, and to glass furnaces containing such products. [Background technology]

[0002] Glass furnaces typically contain a large number of refractory products, arranged in various locations according to their properties. For each component of the furnace, the selected product must be durable enough to withstand a sufficiently long period of time to give the furnace a satisfactory service life without causing defects that render the glass unusable (which could reduce production yield).

[0003] Refractory blocks are classified into cast blocks and sintered blocks.

[0004] In contrast to sintered blocks, cast blocks generally contain intergranular glass phases that bind the crystal grains together. Therefore, the problems arising from sintered and cast blocks, and the technical solutions employed to address them, are generally different. Consequently, compositions developed to create sintered blocks cannot, a priori, be used directly to create cast blocks, and vice versa.

[0005] Cast blocks are often referred to as "electroformed" or "molten-cast," and to obtain them, a mixture of suitable raw materials is melted in an arc furnace or by any other suitable technique. The molten material is then conventionally poured into a mold and subsequently solidified. Generally, the resulting product is then subjected to a controlled cooling cycle to return to room temperature without crushing. This operation is referred to by those skilled in the art as "annealing."

[0006] Cast blocks with very high zirconia content (VHZC), generally containing more than 80% by weight of zirconia, or even more than 85% by weight, are known. These cast blocks have gained a reputation for their excellent corrosion resistance and their ability to not color the manufactured glass or cause defects in the glass.

[0007] European Patent Application Publication No. 403387 describes a molten cast product having a high zirconia content, containing, by weight percentage, 4% to 5% SiO2, about 1% Al2O3, 0.3% sodium oxide, and less than 0.05% P2O5.

[0008] French Patent Application Publication No. 2932475 describes a molten cast product having a high zirconia content, containing, by weight percentage, 3.5 to 6.0% SiO2, 0.7 to 1.5% Al2O3, 0.05 to 0.80% boron oxide B2O3, 0.10 to 0.43% Na2O + K2O, and less than 0.55% Fe2O3 + TiO2.

[0009] Conventionally, products with very high zirconia content are distinguished from alumina-zirconia-silica (AZS) castings, which have higher alumina content and lower ZrO2 content. In particular, AZS products conventionally contain less than 80% by weight of zirconia. AZS products also generally contain more than 10% or 30% of corundum (free corundum or corundum in the form of a corundum / zirconia eutectic), a phase that is generally not present in the VHZC product.

[0010] French Patent Application Publication No. 2024526 essentially describes an AZS product for use in glass furnace tanks, stating that a product with a significantly higher Al2O3 content than SiO2 content allows for the limitation of crack and stone formation.

[0011] Cast blocks with very high zirconia content, such as ER1195, manufactured and sold by SEFPRO, are widely used in glass furnaces today. However, the need for even better quality glass and longer service lives for the furnaces, which involves being subjected to increasingly harsh conditions, means that refractory products with increasingly higher resistance to molten glass are required.

[0012] The need for these refractory products is particularly important for certain specific zones of a glass furnace, such as blocks for glass furnace throats. Throat blocks, in contrast to tank blocks, are subjected to a specific environment. The throat blocks are located at the exit of the molten zone in a zone where the furnace cross-section becomes considerably narrower. In this zone, the interface between the molten glass and the refractory product is also horizontal, and the glass is placed beneath the lintel of the throat. This interface is reinforced by the elements of the refractory product that form the throat block, thereby generally increasing its density, and therefore, due to the specific orientation of the refractory product in this zone, gravity-induced settling is exacerbated. In this zone, only the refractory product is in contact with the molten glass, and therefore any bubbles will form at the glass / refractory product interface (not glass / atmosphere as in the case of the tank). The presence of a gas (bubble)-molten glass-refractory product triple point causes accelerated corrosion. This particular type of corrosion, which rises to the throat level, is called "upward drilling." Furthermore, this zone is typically cooled by a water circuit or by blowing in air. Therefore, the temperature at the glass / refractory product interface differs from the temperature of the tank, which can lead to differences in behavior and affect the corrosion rate. Thus, the corrosion is not of the same nature. Existing AZS or VHZC products have insufficient resistance to corrosion in these zones, and chromium oxide-based refractory products cannot be used with any type of glass, especially the clearest glass. [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] Regarding tank blocks, the inventors have conventionally been concerned with corrosion along the line defining the level of the molten glass bath, i.e., at the interface between the refractory material, glass, and air. In fact, corrosion is quite common in this zone. Therefore, corrosion results in material loss at the interface, which usually determines the end of the tank block's lifespan.

[0014] A product that is very suitable for a tank block is not necessarily suitable for a throat block, and vice versa.

[0015] In particular, there is a need for refractory products in glass furnace throats that have high resistance to molten glass while still possessing a very high zirconia content that is feasible. [Means for solving the problem]

[0016] The present invention relates to a molten cast refractory product, wherein the weight percentage relative to the oxide is, in total, 100%. ZrO2: Amount to complete up to 100% HfO2: <5% SiO2: 8.0%~11.0% Al2O3: 4.0%~6.5% Na2O + K2O + B2O3: 0.40% to 1.30%, preferably 1.00% or less B2O3: <0.60% Y2O3: <1.0% Fe2O3+TiO2: <0.60% Other species: <1.0% Includes, Here, the SiO2 / (Na2O+K2O+B2O3) ratio is 19.0 or less, and preferably 10.0 or more. We propose the above-mentioned molten-cast refractory product.

[0017] As can be seen in more detail in the remainder of the description, this composition gives a melt-cast product that is significantly inert to molten glass. Tests have also shown good feasibility. Therefore, the products according to the invention are perfectly suitable for use in glass furnace tanks or throats.

[0018] Preferably, when the Al2O3 content is 5.1% or more, the SiO2 content is 8.5% or more. Surprisingly, this feature enables the industrial production of large blocks, i.e., blocks with all overall dimensions exceeding 150 mm.

[0019] The products according to the invention may further include one or more of the following optional features, including when it follows the following specific embodiments and when any of these optional features is not compatible with the specific embodiments: The total porosity of the product is less than 10% or less than 5%. Preferably, the oxide is more than 90%, more than 95%, more than 99% or even approximately 100% of the weight of the product. The weight content of ZrO2 + HfO2 is less than 87.5% or less than 87.0% or less than 86.5% or less than 86.0% and / or more than 82.0% or more than 83.0% or more than 83.5% or more than 84.0%. The weight content of SiO2 is less than 10.8% or less than 10.6% or less than 10.5% or less than 10.4% or less than 10.3% or less than 10.2% or less than 10.1% or less than 10.0% and / or more than 8.1%, preferably more than 8.2%, preferably more than 8.3%, preferably more than 8.4%, preferably 8.5% or more, or more than 8.6% or more than 8.7% or more than 8.8% or more than 8.9%. The weight content of Al2O3 is less than 6.2%, or less than 6.1%, or less than 6.0%, or less than 5.9%, or less than 5.8%, or less than 5.7%, or less than 5.6%, or less than 5.5%, or less than 5.4%, or less than 5.3%, or less than 5.2%, or less than 5.1%, or less than 5.0%, and / or more than 4.1%, or more than 4.2%, or more than 4.3%, or more than 4.4%, or more than 4.5%. The total weight content of boron oxide (B2O3), sodium oxide (Na2O), and potassium oxide (K2O) is preferably more than 0.45%, preferably more than 0.50%, preferably more than 0.55%, preferably more than 0.60%, or more than 0.65%, or more than 0.70%, or more than 0.75%, more than 0.80%, more than 0.85%, more than 0.90%, more than 0.95%, and / or less than 1.25%, or less than 1.20%, or less than 1.15%, or less than 1.10%, or less than 1.05%, or less than 1.00%. The total weight content of sodium oxide (Na2O) and potassium oxide (K2O) is preferably more than 0.40%, preferably more than 0.45%, preferably more than 0.50%, preferably more than 0.55%, preferably more than 0.60%, or more than 0.65%, or more than 0.70%, or more than 0.75%, more than 0.80%, more than 0.85%, more than 0.90%, more than 0.95%, and / or less than 1.25%, or less than 1.20%, or less than 1.15%, or less than 1.10%, or less than 1.05%, or less than 1.00%. The weight content of Na2O is preferably more than 0.40%, preferably more than 0.45%, or more than 0.50%, or more than 0.55%, or more than 0.60%, or more than 0.65%, or more than 0.70%, or more than 0.75%, or more than 0.80%, or more than 0.85%, or more than 0.90%, or more than 0.95%, and / or less than 1.25%, or less than 1.20%, or less than 1.15%, or less than 1.10%, or less than 1.05%, or less than 1.00%. The weight content of K2O is greater than 0.20%, or greater than 0.30%, or greater than 0.40%, or greater than 0.45%, or greater than 0.50%, or greater than 0.55%, or greater than 0.60%, or greater than 0.65%, or greater than 0.70%, or greater than 0.75%, or greater than 0.80%. In another embodiment, K2O is present as an impurity or partially replaces Na2O, and the weight content of K2O is less than 1.00%, or less than 0.90%, or less than 0.90%, or less than 0.70%, or less than 0.60%, or less than 0.50%, or less than 0.40%, or less than 0.30%, or less than 0.20%. B2O3 is present as an impurity or partially replaces Na2O, and the weight content of boron oxide B2O3 is less than 0.55%, less than 0.50%, or less than 0.40%, or less than 0.30%, or less than 0.20%. The weight content of Y2O3 is less than 0.80%, or less than 0.60%, or less than 0.50%, or less than 0.40%, or less than 0.30%, or less than 0.20%. The total weight content of iron oxide and titanium oxide Fe2O3+TiO2 is less than 0.40%, preferably less than 0.30%, preferably less than 0.20%. The total weight content of "other species" is less than 0.9%, or less than 0.8%, or less than 0.6%, or less than 0.5%, or less than 0.4%. The "other species" consists only of impurities. The weight content of any one "other species" is less than 0.4%, or less than 0.3%, or less than 0.2%. The total weight content of calcium oxide CaO, barium oxide BaO, strontium oxide SrO and magnesium oxide MgO is less than 0.6%, less than 0.5%, less than 0.4%, or less than 0.3%. The weight content of CaO is less than 0.4%, or less than 0.3%. The weight content of BaO is less than 0.4%, or less than 0.3%. The weight content of SrO is less than 0.4%, or less than 0.3%. The weight content of MgO is less than 0.4% or less than 0.3%. The weight ratio of SiO2 / (Na2O+K2O+B2O3) is greater than 10.5, or greater than 11.0, or greater than 11.5, or greater than 12.0, and / or less than 18.5, or even less than 18.0. The weight ratio of SiO2 / Al2O3 is greater than 1.20, or greater than 1.30, or greater than 1.40, or greater than 1.50, or greater than 1.60, and / or less than 2.60, or even less than 2.50. The weight ratio of Al2O3 / (Na2O+K2O) is less than 8.5 and / or greater than 5.5 or greater than 6.0. The content of the corundum phase, either as a free corundum phase or as a corundum / zirconia eutectic, is less than 10% by weight, preferably less than 5%, and preferably less than 2%.

[0020] According to a particular embodiment, the molten cast refractory product according to the present invention has a weight percentage relative to the oxide, SiO2: 8.5%~11.0% Al2O3: 4.0%~6.0% Na2O + K2O: 0.50%~1.00% B2O3: 0.00%~0.40% Includes.

[0021] According to a particular embodiment, the molten cast refractory product according to the present invention has a weight percentage relative to the oxide, SiO2: 8.0%~9.5% Al2O3: 4.0%~<5.1% Na2O + K2O: 0.50%~1.10% B2O3: 0.00%~0.30% Includes.

[0022] According to a particular embodiment, the molten cast refractory product according to the present invention has a weight percentage relative to the oxide, SiO2: 8.4%~9.5% Al2O3: 4.0%~<5.1% Na2O + K2O: 0.50%~1.00% B2O3: 0.00%~0.30% Includes.

[0023] According to a particular embodiment, the molten cast refractory product according to the present invention has a weight percentage relative to the oxide, SiO2: 8.5%~10.5% Al2O3: 4.4%~5.5% Na2O + K2O: 0.55%~0.95% B2O3: 0.00%~0.30% Includes.

[0024] According to a particular embodiment, the molten cast refractory product according to the present invention has a weight percentage relative to the oxide, SiO2: 8.5%~10.5% Al2O3: ≥5.1% Na2O + K2O: 0.60%~1.20% B2O3: 0.00%~0.30% Includes, Here, the SiO2 / (Na2O+K2O+B2O3) ratio is between 10.0 and 19.0.

[0025] Preferably, The SiO2 content is less than 10%, preferably less than 9%, preferably less than 8.7%, preferably less than 8.6%, and greater than 8.1%, preferably greater than 8.2%, preferably greater than 8.3%, preferably greater than 8.4%. The Al2O3 content is less than 5.1%, preferably less than 5.0%, preferably less than 4.9%, preferably less than 4.8%, preferably less than 4.7%, preferably less than 4.6%, and greater than 4.0%, preferably greater than 4.1%, preferably greater than 4.2%, preferably greater than 4.3%, preferably greater than 4.4%. Preferably, the weight content ratio of SiO2 / (Na2O+K2O+B2O3) is 10.0 or more, preferably more than 10.5, preferably more than 11.0, and preferably less than 15.0, preferably less than 14.0, preferably less than 13.0, and preferably less than 12.0.

[0026] The present invention also relates to a method for manufacturing a fire-resistant product according to the present invention, a) Mixing raw materials to form the initial charge, b) Melt the initial input until a molten substance is obtained. c) The molten material is poured and solidified by cooling to obtain a refractory product. Regarding the above method which includes a series of steps, This method is noteworthy in that the raw materials are selected such that the fire-resistant product conforms to the present invention.

[0027] Preferably, oxides or precursors of these oxides, which are required to be present in minimal amounts, are added systematically and systematically. Preferably, the content of these oxides in the source of other oxides present as impurities is taken into consideration.

[0028] Preferably, the cooling is controlled, preferably at a rate of less than 20°C per hour, and preferably at a rate of about 10°C per hour.

[0029] The present invention also relates to a glass furnace containing a refractory product according to the present invention, or a refractory product in a zone intended to be in contact with molten glass, particularly in the tank or throat of the glass furnace, which is manufactured or could have been manufactured by a method according to the present invention.

[0030] definition A product is conventionally called a "casting" if it is obtained by a method that utilizes melting inputs until a molten substance is obtained, and then solidifying this material by cooling.

[0031] A block is an object whose all dimensions are greater than 10 mm, preferably greater than 50 mm, preferably greater than 100 mm. A block may have, for example, a general parallelepiped shape or a specific shape adapted to its use. Blocks of molten-cast refractory products are obtained, in contrast to layers, by a method that conventionally includes a molding operation and removal from the mold.

[0032] Blocks produced from products according to the present invention may have one, two, or three overall dimensions (thickness, length, or width) of at least 150 mm, preferably at least 250 mm, or at least 400 mm, or at least 500 mm, or at least 600 mm, or at least 800 mm, or even at least 1000 mm, and / or less than 2000 mm, after fettling / machining.

[0033] Unless otherwise stated, all oxide content in products according to the present invention is expressed as a weight percentage of the oxide. The weight content of metal element oxides refers to the total content of the element, expressed in the most stable oxide form, according to the common practice in the art.

[0034] HfO2 cannot be chemically separated from ZrO2. However, according to the present invention, HfO2 is not intentionally added to the input. Therefore, HfO2 represents a trace amount of hafnium oxide, which is always naturally present in zirconium oxide sources, typically in amounts of less than 5%, and generally less than 2%. In blocks according to the present invention, the weight content of HfO2 is less than 5%, preferably less than 3%, and preferably less than 2%. For clarity, the total zirconium oxide content and trace amounts of hafnium oxide can be similarly represented by "ZrO2" or "ZrO2 + HfO2". Therefore, HfO2 is not included in the "other species".

[0035] "Impurities" refer to components that are introduced along with the raw materials or are unavoidable results from reactions with these components. These impurities are not essential components but are merely tolerable. For example, oxides, nitrides, oxynitrides, carbides, oxycarbides, carbonitrides, and compounds that form part of the group of metallic species of iron, titanium, vanadium, and chromium are impurities.

[0036] The total porosity as a percentage is conventionally equal to 100 × (1 - the ratio of geometric density to absolute density).

[0037] Geometric density is measured in accordance with ISO standard 5016:1997 or EN1094-4, in g / cm³. 3 It is expressed as follows. Conventionally, geometric density is equal to the ratio of the mass of the test specimen to its apparent volume.

[0038] The absolute density value is g / cm³. 3 It can be expressed as and measured by dividing the mass of a specimen that has been ground to substantially eliminate porosity by the volume of the specimen.

[0039] Other features and advantages of the present invention will become apparent by reading the detailed description of the invention given below and examining the accompanying figures. [Brief explanation of the drawing]

[0040] [Figure 1] A photograph of a product that does not conform to the present invention (Example 1*) is shown. [Figure 2] A photograph of a product according to the present invention (Example 4) is shown. [Modes for carrying out the invention]

[0041] The photographs in Figures 1 and 2 have been digitally processed to more clearly show the roughness.

[0042] In a molten cast product according to the present invention, a high content of ZrO2 enables the product to meet high corrosion resistance requirements without producing defects that are detrimental to the quality of the glass.

[0043] The hafnium oxide, i.e., HfO2, present in the products according to the present invention is hafnium oxide that naturally occurs in ZrO2 sources. Therefore, its content in the products according to the present invention is less than 5%, and generally less than 2%.

[0044] The presence of SiO2 enables the formation of an intergranular glass phase, which can effectively accommodate deformation of the zirconia framework. However, the addition of SiO2 should not exceed 11%, as this addition can impair the zirconia content and therefore have a detrimental effect on corrosion resistance.

[0045] The presence of Al2O3 in the amount claimed according to the present invention is particularly advantageous. Unexpectedly, the presence of Al2O3 in this amount makes it possible to reduce, and even prevent, the migration of zirconia from the refractory product to the molten glass. The presence of Al2O3 in this amount also ensures good fluidity of the molten material in the mold.

[0046] The presence of Na2O+K2O contributes to the feasibility of the product. The weight content of Na2O+K2O is preferably limited in order to maintain good resistance to corrosion by the molten glass. In products according to the present invention, the oxides, namely Na2O and K2O, are considered to have similar effects.

[0047] The presence of B2O3 contributes to the feasibility of the product. However, B2O3 has an unfavorable effect on zircon formation in the product, which can have a detrimental effect on resistance to thermal cycling. Therefore, the weight content of boron oxide (B2O3) must still be limited.

[0048] Y2O3 can have unfavorable effects on feasibility. Therefore, the weight content of boron oxide Y2O3 must still be limited.

[0049] In one embodiment, the Y2O3 content is greater than 0.2%.

[0050] According to the present invention, the weight content of Fe2O3 + TiO2 is less than 0.5%, preferably less than 0.3%. Preferably, the weight content of P2O5 is less than 0.05%. In fact, these oxides are particularly detrimental to the leaching of refractory products or the discoloration of the glass, and their content must be limited to trace amounts introduced as impurities along with the raw materials.

[0051] "Other species" refers to oxide species not listed above, i.e., species other than ZrO2, HfO2, SiO2, Al2O3, Na2O, K2O, B2O3, Y2O3, TiO2, and Fe2O3. In one embodiment, "other species" is limited to species whose presence is particularly undesirable and which generally exist as impurities in the raw material.

[0052] Preferably, the product according to the present invention is in the form of blocks, preferably at least one, preferably at least two, preferably all of which have an overall dimension greater than 150 mm.

[0053] The weight ratio of SiO2 / (Na2O+K2O+B2O3) is preferably greater than 10.0, more preferably greater than 10.5, or greater than 11.0, or greater than 11.5, or greater than 12.0. Such a ratio is particularly advantageous in tank blocks. Such a ratio is also particularly advantageous at an Al2O3 content greater than 5.1%.

[0054] The total porosity of the product according to the present invention is less than 15%, or less than 10%, or less than 5%, or less than 2%, or less than 1%.

[0055] Products according to the present invention may conventionally be manufactured according to the following steps a) to c): a) Mixing raw materials to form the initial input, b) Melt the initial input until a molten substance is obtained. c) To solidify the molten substance by cooling to obtain a refractory product according to the present invention.

[0056] In step a), the raw materials are selected to ensure the oxide content in the final product obtained at the end of step c). Those skilled in the art are fully aware of how to select the raw materials for this purpose.

[0057] In step b), melting is preferably carried out by a combined action of a fairly long electric arc that does not cause reduction and a mixture that promotes the re-oxidation of the product.

[0058] For the intended application, it is preferable to carry out the melting under oxidizing conditions.

[0059] Preferably, a long arc melting technique is used, as described in French Patent Application Publication No. 1208577, and its supplemental publications No. 75893 and No. 82310.

[0060] This method involves using an arc furnace, where an arc is generated between the material being fed and at least one electrode located at a distance from the material being fed, controlling the length of the arc so as to minimize its reducing effect, while simultaneously maintaining an oxidizing atmosphere in the molten bath and stirring the bath, for example, by the action of the arc itself.

[0061] In step c), cooling is preferably carried out at a rate of less than 20°C per hour, preferably at a rate of about 10°C per hour, in a mold having desired dimensions that take into account the gate and riser, as well as any machining after step c).

[0062] Any conventional method for producing zirconia-based cast products intended for application in a glass furnace may be used, and the composition of the initial input will enable the production of products having a composition according to the present invention.

[0063] In the product according to the present invention, ZrO2 is almost entirely (typically up to more than 95% of its weight) in the form of zirconia, and SiO2 and Al2O3 are almost entirely (typically up to more than 95% of their weight) present in the intergranular phase that binds the zirconia crystal grains together. This intergranular phase essentially contains a glassy phase rich in SiO2 and mullite crystals.

[0064] Examples The following non-limiting examples are given for illustrative purposes of the present invention.

[0065] In these examples, the following raw materials were used: Zirconia Q1 containing an average of 99% ZrO2 + HfO2, "Sable BE01 Bedouin" silica, which contains an average of 99% SiO2. AC34 type alumina containing an average of 99% Al2O3, Sodium carbonate, which contains an average of 99.5% Na2CO3, is used as a source of Na2O. Boron oxide containing an average of 98% B2O3.

[0066] The product was prepared by a conventional melting method in an arc furnace, followed by pouring into a mold, and after cleaning the casting surface, a block with a format of 150 mm × 250 mm × 400 mm was obtained.

[0067] The chemical analysis of the obtained products is shown in Table 1 below, which represents the average chemical analysis given as weight percentages. In these examples, K2O, Y2O3, and Fe2O3+TiO2 are optionally present as impurities, with K2O < 0.05%, Y2O3 < 0.2%, and Fe2O3+TiO2 < 0.3%.

[0068] Other species make up the amount that completes the 100%.

[0069] In Table 1, the HfO2 content is always less than 5%.

[0070] Feasibility The external condition of the obtained product is observed. It is possible to estimate industrial feasibility based on its dimensions, where three dimensions are greater than 150 mm and at least one dimension is at least 400 mm. If through cracks are present, the feasibility (F) is deemed insufficient and designated as "0". Next, the product is cut in half and the filling is observed. If the filling is incomplete, the feasibility (F) is deemed insufficient and designated as "0". Otherwise, the feasibility is deemed satisfactory and designated as "1".

[0071] Zirconia elution To study the product's ability to withstand the leaching of zirconia by molten glass, skull melting tests were conducted at 1400°C and 1500°C to study the interface.

[0072] A sample of the refractory product to be tested is machined to form a cylindrical crucible having an outer diameter of 50 mm and a height of 50 mm, in which a coaxial cylindrical hole with a diameter of 30 mm and a height of 30 mm is created. Powdered soda-lime glass (with a zirconia-free composition) is placed into the hole. The crucible thus filled is heated at a specific temperature for 15 hours. After cooling, the crucible is sliced ​​longitudinally and the midline section is observed. The midline section is polished. The longitudinal interface of the glass / refractory product in this polished section is analyzed using a microprobe dot to determine the percentage of zirconia in the glass up to 1000 microns from the boundary between the glass and the refractory product. The maximum percentage of zirconia (D_Zr) is shown in the table.

[0073] Measurement of throat corrosion resistance Corrosion resistance (CR) is measured using a U-shaped specimen cut from a straight block, measuring 75 mm in length, 50 mm in width, and 50 mm in height, with a central groove machined therein that is 45 mm wide and 30 mm high. The specimen is immersed for 200 hours in a platinum crucible filled with borosilicate glass in a furnace at 1500°C or 1550°C (with the groove facing downwards). The thickness loss of the central portion due to corrosion (between the two legs of the U-shape) is measured. The results are given as a percentage.

[0074] Measurement of tank corrosion resistance The corrosion resistance of a glass bath with air at the top is measured using test specimens in the form of cylindrical rods with a diameter of 22 mm and a height of 100 mm. These specimens are immersed for 48 hours in a bath of molten soda-lime glass heated to 1500°C. The rotation speed of the specimens was 6 revolutions per minute. At the end of the test, the residual volume of each corroded specimen is measured. The residual volume of the corroded specimen of the reference product (Example 1) is considered the baseline for comparison. The corrosion index (CI) is obtained by multiplying the ratio of the residual volume of any other corroded specimen to the residual volume of the corroded reference specimen by 100. A CI value less than 100 represents a corrosion loss greater than that of the reference product. Here, a corrosion index CI of 85 or higher, preferably greater than 90, is considered acceptable for use in glass furnace tanks.

[0075] [Table 1] * indicates "not part of the present invention," NT indicates "not tested," and NM indicates "unmeasurable."

[0076] The test is, The alumina content must be sufficient to improve D_Zr. If the alumina content is too high, the feasibility will be reduced by this (Example 10 * ), An overly high silica content results in a decrease in corrosion resistance. In fact, the interface of the glass / refractory product was very irregular and showed a decrease in the resistance of the refractory product to corrosion by molten glass. Therefore, D_Zr could not be measured for Example 27 * ), The content of B2O3+Na2O+K2O, especially Na2O+K2O, especially Na2O, must be sufficient, and / or the SiO2 / (B2O3+Na2O+K2O) ratio must be restricted to ensure the feasibility of the product (comparison between Example 24 or Example 25 and Example 26 * ), When the Al2O3 content is 5.1% or more, the SiO2 content must be sufficient, i.e., 8.5% or more, to ensure the feasibility of the product (comparison of Example 16 * with Example 5 or Example 18), When the Al2O3 content is 5.1% or more, the SiO2 / (B2O3+Na2O+K2O) ratio must be sufficient for the corrosion-resistant CI to enable the assumed use in a glass furnace tank (comparison between Example 23 and Example 5), For conventional products, the products according to the present invention show less elution of zirconia into the molten glass and at the same time good feasibility .

[0077] The corrosion resistance was measured at 1500 °C for the test pieces from Example 7 (Figure 2) and Example 1 * . The corroded thickness (CR) was 1.4% for Example 7 according to the present invention, while it was 2.6% for the product from Example 1 * .

[0078] As shown in Figures 1 and 2, embodiments not of the present invention have a surface with a plurality of small depressions 10, whereas embodiments according to the present invention are substantially without depressions. Therefore, products according to the present invention have the advantage of giving a very regular corrosion profile.

[0079] It is found that enriching the product with alumina stabilizes the glass composition at the interface with the glass, thus limiting the regeneration of the glass at this interface, and thus limiting the erosive effect of the refractory product.

[0080] Corrosion resistance was measured at 1550°C for samples from Example 22 and for a sample of ER1711 (typically containing 41% ZrO2, 12% SiO2, 45% Al2O3, and 1% Na2O) sold by SEFPRO as a reference product. The corroded thickness (CR) was 0% for Example 22 according to the present invention, while it was 17.4% for the reference product.

[0081] Therefore, as is clearly evident, the present invention provides a product that provides excellent performance in the environment of a glass furnace tank or throat.

[0082] Naturally, the present invention is not limited to the embodiments described and presented, which are provided purely for illustrative purposes.

Claims

1. A molten cast refractory product, in terms of weight percentage relative to the oxide, with respect to a total of 100%, ZrO ２ : Amount to complete up to 100% HfO ２ : <5% Yes ２ : 8.0%~11.0% Al ２ O ３ ★ ... Na ２ O+K ２ O+B ２ O ３ 0.40 ~ 1.30 B ２ O ３ : <0.60% Y ２ O ３ : <1.0% Fe ２ O ３ +Tio ２ : <0.60% Other species: <1.0% Includes, Here, SiO ２ / (Na ２ O+K ２ O+B ２ O ３ The ratio is 19.0 or less. The Al ２ O ３ If the content is 5.1% or more, the SiO ２ The content is 8.5% or more. The aforementioned molten cast refractory product.

2. 83.0% < ZrO ２ +HfO ２ <88.0%; and / or, 8.4% < SiO ２ <10.6%; and / or, 3.9% < Al ２ O ３ <6.1%; and / or, Na ２ O+K ２ O+B ２ O ３ ≤ 1.00%; and / or, 0.40% < Na ２ O+K ２ O; and / or, B ２ O ３ <0.50%; and / or, Y ２ O ３ <0.40%; and / or, Fe ２ O ３ +TiO ２ <0.40%; and / or, SiO ２ / (Na ２ O+K ２ O+B ２ O ３ The ratio is between 10.0 and 19.

0. The fire-resistant product according to claim 1.

3. 83.5% < ZrO ２ +HfO ２ <87.0%; and / or, 8.5% < SiO ２ <10.5%; and / or, 4.0% < Al ２ O ３ <6.0%; and / or, 0.50% < Na ２ O+K ２ O; and / or, B ２ O ３ <0.45%; and / or, SiO ２ / (Na ２ O+K ２ O+B ２ O ３ The ratio is between 12.0 and 18.

0. The fire-resistant product according to claim 2.

4. 8.5% ≤ SiO ２ The fire-resistant product according to claim 1.

5. In terms of weight percentage relative to the oxide, Yes ２ : 8.5%~11.0% Al ２ O ３ : 4.00~6.00 Na ２ O+K ２ O: 0.50%~1.00% B ２ O ３ : 0.00%~0.40% A fire-resistant product according to claim 1, including the above.

6. In terms of weight percentage relative to the oxide, Yes ２ : 8.5%~10.5% Al ２ O ３ : 4.45~5.55 Na ２ O+K ２ O: 0.55 ~ 0.95 B ２ O ３ : 0.00%~0.30% A fire-resistant product according to claim 5, including the above.

7. SiO ２ / Al ２ O ３ The ratio is greater than 1.2 and less than 2.6, and / or Al ２ O ３ / (Na ２ O+K ２ O) A fire-resistant product according to any one of claims 1 to 6, wherein the ratio is less than 8.

5.

8. Al ２ O ３ A fire-resistant product according to any one of claims 1 to 6, wherein the content is 5.1%.

9. SiO ２ The content is less than 10% and more than 8.1%, and Al ２ O ３ The content is less than 5.0% and greater than 4.0%. The fire-resistant product according to claim 8.

10. SiO ２ The content is less than 8.7% and greater than 8.3%, and Al ２ O ３ The content is less than 4.7% and more than 4.3%. The fire-resistant product according to claim 9.

11. Al ２ O ３ is ≥ 5.1%, and the ratio of SiO ２ / (Na ２ O + K ２ O + B ２ O ３ is 10.0 or more, the refractory product according to any one of claims 1 to 6.

12. A refractory product according to any one of claims 1 to 6, wherein the weight content of corundum in the form of free corundum or corundum / zirconia eutectic is less than 5%.

13. A glass furnace comprising a block made from a refractory product according to any one of claims 1 to 6.

14. The aforementioned block is placed inside the tank, SiO ２ / (Na ２ O+K ２ O+B ２ O ３ The glass furnace according to claim 13, wherein the weight content ratio of ) is greater than 10.

0.

15. The glass furnace according to claim 13, wherein the block is placed inside the throat.

16. The glass furnace according to claim 13, wherein the total dimensions of all the blocks exceed 150 mm.

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