Casting element and method for manufacturing the same using low-temperature solidification

Abstract

This application relates to a casting element for casting and a method for forming the same. The method includes: forming an aqueous slurry containing an inorganic binder precursor, shaping the slurry using a pattern, curing the shaped slurry using a low-temperature solidification process to form a casting element, and removing the pattern from the casting element.

Description

[0001] Cross - reference to Related Application Areas

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 953,360, filed on December 24, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] Aspects of the present invention relate to casting elements and methods of manufacturing such casting elements using low - temperature solidification. Background Art

[0004] Sand casting and investment casting processes involve forming a particulate or granular refractory material around a pattern to form a cavity into which molten material can be poured to form a product having the same shape as the pattern. Once the molten material has sufficiently solidified, the desired product is removed by breaking the mold. The mold material is then discarded or recycled. The disposability of the mold makes these processes similar to other processes using ceramic materials, but in sharp contrast to permanent - mold methods such as die - casting, squeeze - casting, vacuum - casting, or pressure - casting, although the pressure - assisted aspects of these latter methods can be applied in some form to sand casting and investment casting. Among the various casting methods available to manufacturers, sand casting is characterized by relatively low cost, a wide range of castable materials, and the ability to cast large objects. Sand casting is widely used among metal - part manufacturers, with over 100 million tons of material produced globally each year. Ferrous metals such as steel and other ferroalloys, as well as non - ferrous metals such as aluminum, copper, magnesium, lead, zinc, tin, nickel, titanium, precious metals, and refractory alloys can all be processed using some form of sand casting. Non - metallic oxide materials such as glass can also be formed by sand casting. Investment casting is favored for its ability to produce parts with excellent surface finish and tight dimensional tolerances with minimal machining requirements, while sand - cast parts require finishing steps such as grinding and polishing. However, investment casting is more costly than sand casting, mainly due to cycle time. Summary of the Invention

[0005] According to various embodiments, a method of forming a casting element for casting is provided, the method comprising: forming an aqueous slurry comprising a solid inorganic binder material or a precursor thereof; shaping the slurry using a pattern; curing the shaped slurry using reactive low temperature solidification (RLTS) to form a casting element; and removing the pattern from the casting element. In some embodiments, curing occurs only after the slurry is shaped. In some embodiments, the solid inorganic binder material comprises at least one component selected from: magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium carbonate hydrate, calcium oxide, calcium hydroxide, calcium carbonate, calcium silicate monohydrate, dicalcium silicate, tricalcium silicate, calcium aluminate, calcium aluminosilicate, and rare earth oxides; wherein at least one component is combined with one or more clays, colloidal silica, and one or more elements; the one or more elements are selected from magnesium, aluminum, iron, zinc, zirconium, titanium, vanadium, yttrium, lithium, sodium, potassium, bismuth, cerium, strontium, calcium, barium, lanthanum, copper, and boron, and wherein the one or more elements are present in the form of oxides, hydroxides, and / or hydrated oxides. Rare earth metals include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium. In some embodiments, the binder precursor comprises at least a compound of the chemical formula ABO 3 wherein A is magnesium, calcium, strontium, or barium, B is titanium or zirconium, and ABO 3 is in the form of a linear compound, solid solution, or multiphase mixture of the ABO 3 compound; wherein the method comprises permeating the shaped slurry with CO 2 and converting the ABO 3 at least partially into an A-site metal carbonate and a B-site metal dioxide. Applications of the technology include, for example, casting elements for sand casting and investment casting or refractory elements for refractory bricks, castables, gunning mixes, and ramming mixes.

[0006] According to various embodiments, a method of forming a casting element for casting is provided, the method comprising forming an aqueous first slurry comprising refractory sand and a binder polymer; forming an aqueous second slurry comprising a solid inorganic binder material and a thermoreversible additive; applying the first slurry to a pattern to form a first coating; heating the second slurry to a temperature of about 50 °C to about 100 °C; immersing the pattern in the heated second slurry to form a second coating on the first coating; gelling the second coating by cooling the second coating to a temperature below about 50 °C; permeating with CO 2Penetrate the first and second coatings to cure the first and second coatings and form a casting element. In some embodiments, at least two impregnations and gelling are performed to form a three-layer structure. In some embodiments, the refractory sand includes zircon sand; wherein the method further includes applying additional zircon sand to the first coating; the solid inorganic binder material includes at least one component selected from the following: magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, calcium monosilicate, calcium disilicate, calcium trisilicate, calcium aluminate, calcium aluminosilicate, and rare earth oxides.

[0007] According to various embodiments, a casting element for casting is provided, which includes a mixture of refractory sand and a magnesium aluminate phosphate gel mixed with one or more components. In some embodiments, the binder includes MgO - Al 2 O 3 -Fe 2 O 3 -P 2 O 5 -H 2 O gel. Optional additional components include, for example, clay, fumed silica, and soluble precursors of zinc or rare earth lanthanide ions. In some embodiments, the refractory sand includes silica sand, olivine sand, chromite sand, zircon sand, burned clay sand, aluminosilicate sand, or any combination thereof, and wherein the casting element includes a sand casting mold, a sand casting core, an investment casting shell, or a refractory mix, wherein the refractory mix is a brick, a castable, a gunning mix, or a ramming mix.

[0008] According to various embodiments, a refractory brick for a ladle for containing molten metal includes larger MgO particles bonded to each other by smaller magnesium carbonate particles. There is also provided a ladle or blast furnace for containing molten metal, the inner surface of which is lined with the refractory brick disclosed herein.

[0009] According to various embodiments, a method of forming a casting element for casting includes forming an aqueous slurry containing a solid inorganic oxide material, and permeating the slurry with CO 2 to at least partially convert the solid inorganic oxide material into a solid inorganic carbonate material, and forming a casting element for casting. The solid inorganic oxide material contains CaSiO 3 , and permeating the slurry with CO 2 converts CaSiO 3 at least partially into calcium carbonate in a sand casting. The solid inorganic oxide material includes MgO; permeating the shaped slurry with CO 2 partially converts MgO into magnesium carbonate, thereby forming a refractory element for a brick, a castable, a gunning mix, or a ramming mix. The method can generally be used for metallurgical purposes, including, for example, blast furnaces and ladles.

[0010] Brief Description of the Drawings

[0011] Figure 1A and 1B are photographs of refractory bricks according to various embodiments of the present disclosure. Figure 1C is a schematic side cross-sectional view of a ladle lined with refractory bricks according to various embodiments of the present disclosure.

[0012] Figure 2A is a photograph of a sand mold that can be used to form a brake disc according to an embodiment of the present disclosure. Figure 2B is using Figure 2A The sand mold forms photographs of two aluminum castings of the brake disc.

[0013] Figure 3 is a photograph including a wax pattern and an aluminum casting formed using the wax pattern.

[0014] Detailed Description

[0015] Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. References to specific examples and embodiments are for illustrative purposes only and are not intended to limit the scope of the invention or the claims.

[0016] As used herein, "casting element for casting" or "casting element" may refer to a casting brick made of refractory material and can be used for the lining of a ladle used in a metallurgical process (such as metal casting), and / or it may refer to a mold, core, etc. made of refractory material and used in sand casting, investment casting, etc. A range may be expressed herein as from "about" a particular value, and / or to "about" another particular value. When expressing such a range, examples include from one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation, by using the antecedent "about" or "substantially", it will be understood that the particular value forms another aspect. In some embodiments, the value of "about X" may include a value of + / - 1% X. It will be further understood that each endpoint of a range is significant with respect to the other endpoint and independent of the other endpoint.

[0017] It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Since those skilled in the art can conceive of modifications, combinations, sub-combinations, and variations of the embodiments that combine the spirit and substance of the present disclosure, the present disclosure should be construed to include all that falls within the scope of the appended claims and their equivalents.

[0018] The composition of sand casting materials typically includes particulate or granular refractory materials and a binder as the main components. The refractory materials usually constitute the majority of the mass used in sand casting elements (such as sand casting molds or cores). Refractory materials can include silica sand, olivine sand, chromite sand, zircon sand, mullite sand, or any combination thereof. The sand selected for the casting element depends on the chemical nature of the material to be cast as well as cost considerations. On the other hand, binders are used to coat and bond the refractory particles together. The nature of the binder can distinguish various types of sand casting materials and / or methods from one another. For example, green sand is a commonly used sand casting mold that includes a combination of bentonite, water, and other additives most commonly used as binders.

[0019] Green sand is inexpensive and allows a wide range of mold characteristics, although tight tolerances and high aspect ratio features in the cast product are far less feasible than in other sand casting methods. Additionally, green sand casting typically cannot effectively produce high-quality cores, which are used to create cavities within the casting itself. Sand molds and cores with more stringent performance requirements are more often produced using other sand casting methods, such as room temperature curing (airset) / no-bake, cold box, and shell / hot box methods. In these methods, the sand is coated with an organic or inorganic resin that chemically binds the particles after a catalytic curing process.

[0020] In sand casting, many of the state-of-the-art methods for chemically binding the sand used in casting molds have several advantages, including rapid processing times, dimensional stability of the mold, and the ability to produce excellent surface finishes, as well as high aspect ratio features in the final casting. However, unlike green sand, the binder components are much more expensive than clay and water. When using certain organic and inorganic resins, time is also critical because curing begins once the components are mixed, which means that the working time for shaping the mold is short. Additionally, curing continues even after the mold and pattern are separated, so the casting mold requires a rapid pouring time to ensure that the mold has the strength and permeability within the specified range.

[0021] If the mold is allowed to cure for too long, mold knockout is more difficult and may damage the casting. Additionally, the curing process of commonly used organic resins (such as pitch) emits vapors that are harmful to foundry workers and the environment, and the thermal decomposition of these resins during casting releases another round of harmful vapors. This vapor can also create defects in the cast product.

[0022] While inorganic binders (such as sodium silicate systems) do not have this drawback, the performance of sand molds and cores using sodium silicate-based binders is extremely sensitive to humidity, especially difficult to control in the casting environment, and the curing time is longer. Finally, resin-bonded sand can be recycled using energy-intensive thermal recovery processes. The energy costs increase the cost of using it in sand casting operations.

[0023] The molds used in investment casting include a shell formed from a sintered mixture of coarse and fine refractory materials. In a typical mold-making process, a wax pattern having the shape of the desired object is first dipped into a slurry containing fine refractory powder, and then the wet-slurry-coated pattern is dusted with coarse refractory sand. The coated pattern is then dried for an appropriate time, typically several hours. The coating and drying steps are then repeated until the desired coating thickness is achieved. The coated pattern is then autoclaved to remove the wax pattern, leaving a refractory shell mold. The coating slurry typically contains a binder that provides sufficient green strength to the mold to withstand this process. After autoclaving, the mold is heated to a high temperature, and then molten material is poured into the mold. This material is sometimes designed to have the highest strength at such high temperatures.

[0024] The main disadvantages inherent in investment casting are the lack of speed. The long drying cycles between coatings can take days to weeks to complete the manufacture of a single mold. In addition, the continuous dipping process makes it a difficult technical challenge to strengthen the mold with a self-setting binder because the dipping slurry needs to have a long "working life". In addition, molten silica, which is a common component in refractory shells, crystallizes during the heating step, and the resulting crystalline silica is dangerous during the shell knockout process.

[0025] Exemplary Mold and Core Casting Materials and Methods

[0026] According to various embodiments of the present disclosure, novel casting materials and processing methods are provided that overcome the above and / or other disadvantages of conventional casting elements and methods for casting. Various embodiments provide methods for manufacturing casting elements for casting that are relatively low in cost and have high process flexibility, desirable speed, ease of recycling, and excellent casting performance attributes.

[0027] According to various embodiments of the present disclosure, the binder material for casting elements for casting includes a solid inorganic binder material as a main component (e.g., the solid inorganic binder material accounts for more than 50 atomic percent of the entire binder material, e.g., 80 to 100 atomic percent of the binder material). In some embodiments, the solid inorganic binder material can be formed from ceramic powders and / or metal oxide ceramic precursor materials, such as calcium silicate (CaSiO 3 ), titanium dioxide (TiO 2 ), zirconium dioxide (ZrO 2 ), yttria-stabilized zirconia, lanthanum oxide (La 2 O 3 ), magnesium oxide (MgO), iron oxide (Fe 2 O 3) Calcium oxide (CaO), or combinations thereof, etc., and / or metal powders, such as iron and / or magnesium powders containing ceramic precursor materials. In an exemplary embodiment, based on the total weight of the binder, the individual inorganic binder or binder precursor can be present in the range of about 5% to about 100%, about 15% to about 90%, about 25% to about 90%, about 40% to about 90%, about 50% to about 90%, about 60% to about 90%, or about 80% to about 100%. In some more exemplary embodiments, based on the weight of the casting element, the binder material ranges from about 1% to about 95%, about 5% to about 80%, about 5% to about 60%, about 5% to about 40%, about 5% to about 20%, about 10% to about 60%, about 10% to about 40%, or about 10% to about 20%. In a further exemplary embodiment, the weight ratio between the refractory material (such as refractory sand) and one or more binder materials in the casting element is in the range of about 1000:1 to about 1:10, about 200:1 to about 1:1, about 200:1 to about 10:1, about 100:1 to about 10:1, or about 100:1 to about 50:1.

[0028] Through a curing or similar process, this solid inorganic binder material acts as a bonding element that joins refractory material particles (i.e., as a binder or adhesive material). In some embodiments, the refractory material can have a larger particle size than the solid inorganic binder material of the bonding element. The bonding element can include a crystalline phase and an amorphous phase.

[0029] For example, according to various embodiments of the present disclosure, during the sand mold manufacturing process, the particles of the solid inorganic binder material are thoroughly mixed with refractory sand using a grinder, a high-intensity mixer, a blade mixer, or other mixing processes. Water, clay, and other additives can be added to the mixture to form, for example, a homogeneous mixture or a non-setting slurry having a viscosity suitable for molding. Herein, a "non-setting slurry" can refer to a slurry in which the solids remain uniformly mixed in suspension for a long time (e.g., at least one hour, such as at least one day, or at least several days or weeks).

[0030] Then, using a pattern and / or a suitable pattern-making method, such as suspension, shaking, extrusion, ramming, vibratory casting, or blowing, the mixture is formed into a casting element, such as a mold or a core. Then, a curing process is performed on the solid inorganic binder material as described below. Once the casting element for casting is cured to a sufficient strength to maintain its structural integrity, the casting element for casting is separated from the pattern. If the casting element for casting has sufficient strength to be removed from the pattern without curing, the curing reaction can be initiated after removal from the pattern. The curing and drying of the casting element for casting, if applicable, can continue until it is ready for the casting process. In some embodiments, the solid inorganic binder material includes CaSiO 3, at least one of MgO or CaO. In some embodiments, the solid inorganic binder material comprises CaSiO 3 and at least one of MgO and CaO. In some embodiments, curing comprises using CO at a temperature of about 20°C to about 200°C, about 20°C to about 100°C, about 20°C to about 80°C, about 30°C to about 80°C, about 40°C to about 60°C, about 40°C to about 50°C, or about 50°C to about 70°C and a pressure range of about 20 psig to about 100 psig, about 30 psig to about 80 psig, about 40 psig to about 80 psig, about 50 psig to about 80 psig or about 50 psig to about 70 psig 2 to permeate the formed slurry.

[0031] According to various other embodiments of the present disclosure, in an investment casting process, a solid inorganic binder material is mixed with a refractory material (e.g., refractory sand) and water using a high-shear mixer, a paddle mixer, or other mixing processes to form a slurry for coating a wax (or similar material) mold. Additives such as dispersants and gums are added to the resulting slurry to modify the rheology so as to obtain a desired coating thickness during one or more subsequent dip-coating process steps.

[0032] In various embodiments of the present invention, the slurry can optionally be heated and a set of additives can be incorporated into the heated slurry to form a thermoreversible slurry (e.g., sol-gel) in which the solid inorganic binder material particles and the refractory material particles are dispersed. Such additives can include, but are not limited to, carrageenan, potassium chloride, calcium chloride, agarose, and hydroxyethyl cellulose. The slurry can be heated to a temperature of about 50°C to about 100°C, such as about 60°C to about 90°C, or about 65°C to about 85°C.

[0033] Then a pattern made of wax, plastic, or a similar dissolvable material can be immersed in the slurry, thereby forming a uniform coating of the slurry with a desired thickness on the pattern. After removing the pattern from the slurry, the slurry can form a gel upon cooling. Vibration and / or heating can be applied to the slurry to reduce its viscosity during the dipping operation while allowing the coating to thicken rapidly once the pattern has been removed from the slurry. In some embodiments, the dip-coating can be repeated multiple times. However, compared to traditional investment casting processes, the inventors have found that the disclosed slurry compositions can unexpectedly form a thick and / or strong enough coating after only one or two dip-coating processes. At the same time, the coating process can be completed within 3 hours, 2 hours, 1 hour, 45 minutes, 30 minutes, 20 minutes, or 10 minutes.

[0034] Once the dip coating is complete, the coated pattern is subjected to a curing process to strengthen the inorganic binder component. After the curing process is complete, the pattern is removed from the resulting shell and may optionally be soaked at elevated temperatures. Finally, the molten material is poured into the shell to form the desired object.

[0035] A preferred form of curing of the solid inorganic binder of the above-described mold and / or core is based on reactive low-temperature solidification (RLTS), first invented by Atakan and Riman of Rutgers University and known as the reactive hydrothermal liquid-phase densification (rHLPD) method (see U.S. Patent Nos. 8,313,802 and 8,709,960, which are hereby incorporated by reference in their entirety). The general rHLPD process begins with a porous material matrix having interconnected pores. The porous network is infiltrated with a liquid comprising a solvent and soluble reactive cations and / or anions. Infiltration is spontaneous and driven by capillary forces due to the wetting of the solid by the fluid. Subsequently, a thermodynamically favorable and kinetically unstable hydrothermal reaction is initiated to partially dissolve the porous matrix and form reaction products that fill the pore space of the matrix. Sufficiently rapid hydrothermal reaction kinetics allow the process to proceed at temperatures below 500 °C, such as below about 250 °C. For example, the process may occur at relatively low temperatures of about 25 - 300 °C, such as from about 25 °C to 200 °C, including 80 °C to 180 °C, which is much lower than the temperatures employed in most conventional densification processes. The reaction pressure can be less than 100,000 psi, such as 1 to 3 atmospheres.

[0036] By selecting reaction products with a molar volume greater than that of the reactive matrix, the hydrothermal reaction front moves through and fills the matrix pore space, thereby densifying and strengthening the matrix. Crystals growing in the pores may form at the expense of the reactive matrix, but the increase in molar volume is sufficient to compensate for the volume loss of the matrix. Under appropriate reaction conditions, the pore space acts as a template to limit the crystal growth of the reaction products. In this case, product crystals can nucleate uniformly in the pores and can grow epitaxially from other product crystals or can grow on the matrix interface. Under appropriate reaction conditions, the pores act as templates to limit crystal growth such that the particle centers do not move. Thus, the matrix experiences substantially no volume shrinkage during the curing process.

[0037] In the context of embodiments of the present invention, a porous matrix strengthened by RLTS is formed from a mixture of solid inorganic particles and / or refractory particles. The liquid component can be an aqueous solution containing substances that react with the solid inorganic binder material particles and / or the primary refractory. RLTS is compatible with a variety of different starting materials, such as ceramics, metals, cermets, other composite materials, or their precursors. One such material found is calcium monosilicate (CaSiO 3 )). However, conventionally, CaSiO3 It is not a suitable binder material for casting components, at least in part because its melting temperature is significantly lower than that of metals commonly cast, such as steel.

[0038] The volume filling and bonding mechanism can be applied to the preparation of various types of casting components. For example, the volume filling and bonding mechanism may be phosphoric acid (H 3 PO 4 ) aqueous solution reacting with mixed CaSiO 3 to form brushite (CaHPO 4 -2H 2 O) and silica (SiO 2 ). This reaction can be represented by the following equation (1):

[0039] (1) CaSiO 3 (s) + H 3 PO 4 (aq) + H 2 O → CaHPO 4 -2H 2 O(s) + SiO 2 (s).

[0040] The complete conversion of CaSiO 3 to CaHPO 4 -2H 2 O and SiO 2 results in a net volume increase of nearly 300%. Other suitable multi-component binder materials can include MgO / Al 2 O 3 / CaSiO 3 , MgO / Al 2 O 3 / Fe 2 O 3 and CaAl 2 O 4 .

[0041] Phosphate-based curing has previously been used to bond sand for casting, but these applications have led to a decline in the performance of molds and cores over time, especially in humid environments. In addition, in existing phosphate-based sands and other chemically bonded sands, the curing reaction starts immediately when all solid and liquid components are mixed and just before the mixture is consolidated into the mold or core "reaction and filling", which means that the working life of the mixture is actually limited and the most dense filling structure is not possible.

[0042] Compared with traditional reaction and filling methods, various embodiments provide a "fill then react" method where little or no curing occurs before the mixture is formed into a casting element (e.g., a mold or core), giving the mixture an almost infinite working life and the ability to provide high-density filling. Additionally, previous applications of phosphate foundry sand binders do not seem to fully recognize how the initial particle size and morphology of the inorganic components affect the properties and final microstructure of a material that contains both amorphous and crystalline components. The particle size and morphology of the powder are determined by the firing and grinding history of the powder.

[0043] For example, in one embodiment of the present disclosure, the "fill then react" method can be used for the above-mentioned CaSiO 3 -phosphate system. In some embodiments, the mixture for the "fill then react" method can include dense particles with little or no intra-particle porosity. The method can include mixing high-purity phosphoric acid with a CaSiO 3 -refractory sand mixture, shaping the resulting mixture by filling the mixture into a pattern to form a casting element, and then curing the shaped mixture by low-temperature steam penetration. In some embodiments, the combination of high-purity phosphoric acid and the CaSiO 3 -refractory sand mixture is in a suitable porosity configuration after forming the desired shape and can withstand the curing conditions of RLTS.

[0044] In an exemplary embodiment of low-temperature steam penetration, the shaped mixture can be penetrated with pressurized steam at a temperature of about 80 °C to about 200 °C, such as about 105 °C to about 140 °C, about 110 °C to about 130 °C, or about 120 °C. The steam can be applied for a sufficient period of time to react at least 75%, such as at least 80%, 85%, 90%, 95%, 99%, or 99.9% of the inorganic binder material (e.g., converting CaSiO 3 to CaHPO 4 -2H 2 O + SiO 2 ). For example, the steam can be applied for a period of about 5 minutes to about 30 minutes, such as about 10 minutes to about 20 minutes. Regarding binder materials or precursors such as La 2 O 3 , MgO / Al 2 O 3 / CaSiO 3 , MgO / Al 2 O 3 / Fe 2 O 3 and CaAl 2 O 4The curing process can also undergo the above conditions. In some embodiments, the weight ratio between one or more binder materials or their precursors and phosphoric acid is from about 10:1 to about 1:10, about 5:1 to about 1:5, about 5:1 to about 1:5, about 3:1 to about 1:3, about 5:1 to about 3:1, about 3:1 to about 1:1, about 1:1 to about 1:3, or about 1:1 to about 1:5.

[0045] In another embodiment, the carbonation reaction using carbon dioxide can be used to form a casting element. For example, the volume filling mechanism can be from CaSiO 3 reacting with CO 2 dissolved in an aqueous solution to form calcium carbonate (CaCO 3 ) and silicon dioxide (SiO 2 ). This reaction can be represented by the following Equation 2:

[0046] (2)CaSiO 3 (s) + CO 2 (aq) - CaCO 3 (s) + SiO 2 (s).

[0047] CaSiO 3 to CaCO 3 and SiO 2 complete conversion results in a net volume increase of about 60%. In some cases, the reaction does not proceed to complete reaction. For example, the reaction can convert about 50% to about 99%, such as about 60% to about 90%, or about 70% to about 80% of CaSiO 3 to calcium carbonate. However, the partially reacted calcium silicate matrix has a unique bonding structure consisting of CaSiO 3 nuclei, each nucleus encapsulated and bonded together by an inner layer composed of calcium-poor SiO 2 and an outer layer made of CaCO 3 particles.

[0048] In various embodiments, the volume filling mechanism can include the formation of magnesium carbonate (MgCO 3 ) or calcium carbonate (CaCO 3 ) through the reactions represented by the following Equations 3 and 4:

[0049] (3)MgO + CO 2 - MgCO 3 ; and

[0050] (4)CaO + CO 2 - CaCO 3 .

[0051] The carbonation reactions of Formulas 3 and 4 using carbon dioxide can replace the reaction of Formula 1 using water and phosphoric acid, or, in addition to the reaction of Formula 1 using water and phosphoric acid, the carbonation reactions of Formulas 3 and 4 using carbon dioxide can also be carried out. In some embodiments, a autoclave can be used to apply CO 2 to the shaped material. In some embodiments involving a curing process where the shaped material is exposed to CO 2 , the shaped material can be maintained in the autoclave at a temperature of about 30 °C to about 80 °C, such as about 35 °C to about 70 °C, or about 40 °C to about 50 °C, and at a pressure of about 40 psig to about 80 psig, such as about 50 psig to about 70 psig, or about 60 psig. The autoclave can be maintained under these conditions for about 10 hours to about 30 hours, such as about 20 hours.

[0052] Figure 1A and 1B are photographs of refractory brick casting elements according to various embodiments of the present disclosure. Figure 1C is a schematic side cross-sectional view of a ladle 2 lined with a refractory brick 4 according to an embodiment of the present disclosure. The ladle 2 is filled with molten metal, such as steel, aluminum, etc., and then it is poured into a mold or other location. The refractory brick 4 protects the ladle 2 from the molten metal. For example, the refractory brick can be formed by shaping refractory sand or powder such as MgO into a brick shape, and then infiltrating the brick-shaped material with CO 2 to partially convert MgO into MgCO 3 , as shown in Formula 3. For example, MgCO 3 can form submicron-sized particles, which are used to bond the centimeter-sized MgO particles in the refractory brick 4 together. In other words, the smaller magnesium carbonate particles act as a binder for the larger magnesium oxide particles in the refractory brick 4. Such a refractory brick 4 can consist essentially of magnesium oxide and magnesium carbonate and does not include deliberately added organic materials, such as pitch used in prior art refractory bricks and which produces toxic vapors.

[0053] The refractory brick 4 can be used for lining metallurgical ladles 2 and / or furnaces. In use, it is believed that the high temperature of the molten metal may partially decompose the smaller MgCO 3 "binder" particles, thereby producing CO 2 and smaller MgO particles, which can be used to sinter (e.g., bond) the initially larger MgO particles in the refractory brick 4 together.

[0054] In another embodiment, the volume filling mechanism of the casting element can be by magnesium oxide (MgO), iron oxide (Fe 2 O 3 ), aluminum phosphate (H 3 PO 4)The solidification of the material forms MgO - Al 2 O 3 -Fe 2 O 3 -P 2 O 5 -H 2 O gel. This reaction can be represented by the following equation (5):

[0055] (5)MgO + Fe 2 O 3 +Al(H 2 PO 4 ) 3 +H 3 PO 4 +H 2 O → MgHPO 4 -3H 2 O + FePO 4 -H 2 O + AlPO 4 -H 2 O + MgO - Al 2 O 3 -Fe 2 O 3 -P 2 O 5 -H 2 O (gel).

[0056] For example, in some embodiments, the casting element can be formed by mixing about 2000 g to about 2500 g, such as about 2100 g to about 2300 g, or about 2200 g of refractory sand, such as silica sand, with about 50 g to about 100 g, such as about 60 g to about 90 g, or about 75 g of an aqueous solution containing Al(H 2 PO 4 ) 3 、H 3 PO 4 and H 2 O to form a mixture. In some embodiments, the aqueous solution can contain about 35 wt% to about 55 wt%, such as about 40 wt% to about 50 wt% of Al(H 2 PO 4 ) 3 , about 22 wt% to about 42 wt%, such as about 18 wt% to about 28 wt% of H 3 PO 4 , and about 22 wt% to about 42 wt%, such as about 27 wt% to about 37 wt% of H 2 O. About 20 g to about 40 g, such as about 25 g to about 35 g of a composition containing MgO and Fe 2 O 3Powder is added to the mixture to form a slurry. The powder may comprise from about 80 wt% to about 99 wt%, such as from about 85 wt% to about 95 wt% of MgO, and from about 1 wt% to about 20 wt%, such as from about 5 wt% to about 15 wt% of Fe 2 O 3 . The slurry can be formed into a casting element by, for example, filling the slurry into a pattern. The formed slurry can be held in the pattern for a period of about 1 hour to about 24 hours to form a solidified casting element, such as a bonded core material.

[0057] Metals such as superalloys (e.g., nickel-based alloys such as Inconel, etc.), Ti alloys, precious metals, and refractory metals can pose significant technical challenges for sand casting because they have high melting temperatures and potential adverse mold-metal interactions, such as in the case of state-of-the-art chemically bonded sands. On the other hand, aspects of the present invention include chemicals for producing a highly refractory binder phase that provides resistance to the harsh environments presented by such metals. Exemplary chemicals include the following formulas 6-8:

[0058] (6) ZrO 2 (s) + Sr(OH) 2 (aq) - SrZrO 3 (s) + H 2 O;

[0059] (7) TiO 2 (s) + Ba(OH) 2 (aq) - BaTiO 3 (s) + H 2 O; and

[0060] (8) La 2 O 3 (s) + 2H 3 PO 4 (aq) - 2LaPO 4 (s) - H 2 O + 2H 2 O.

[0061] SrTiO 3 can be similarly formed from TiO 2 (s) and Sr(OH) 2 . Precursors of these chemicals can be mixed into sand or other refractory materials and curing does not occur until an appropriate temperature is applied to the system. Such chemicals can also be used to fabricate robust cermets or ceramic-ceramic composites, which can be used to manufacture more durable molds and cores for applications such as die casting.

[0062] In some embodiments of any of the methods disclosed herein, it may include an inert component that is stable at high temperatures and does not react with the binder material. The resulting cast or refractory element incorporated with the inert material can thus exhibit various properties as needed. Non-limiting examples of the inert material or component include oxide sand, diamond, graphite, carbon black, graphene, graphene oxide, metal carbide, silicon carbide, boron carbide, tungsten carbide, niobium carbide, titanium boride, zirconium boride, zirconia, titanium dioxide, alumina, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate, and dolomite.

[0063] Example 1: Calcium silicate-phosphate bonded core sand material

[0064] Mix 150 g of synthetic olivine sand (AFS GFN 70) with 6 g of calcium silicate and 6 g of 85% phosphoric acid. Load the resulting mixture into an AFS standard 2-inch cylindrical specimen tube and ram it with standard sand. Connect the specimen tube to a steam generator and let steam at 120 °C pass through the specimen tube for 10 minutes. Then peel the bonded sand cylinder from the specimen tube. Thereafter, perform hot compressive strength and permeability tests on the cylinder to demonstrate that it has sufficient refractory and mechanical properties for foundry applications. In some embodiments, use La 2 O 3 to replace part or all of CaSiO 3 to produce a bonded sand material with higher refractory robustness.

[0065] Example 2: Calcium silicate-calcium carbonate bonded sand mold

[0066] Mix 15.8 kg of synthetic olivine sand (AFS GFN 70) with 1.6 kg of calcium silicate, 1.6 kg of western bentonite, and 1 kg of water. Ram the mixture into a wooden mold set that contains a brake rotor pattern to form the upper and lower molds. The upper and lower molds formed from the rammed mixture are peeled from the pattern and directly placed into a 230 L autoclave. Seal the autoclave, heat it to 65 °C, and fill it with completely dry CO 2 until a pressure of 60 psig is reached. Keep the autoclave under these conditions for 20 hours with a fan rotating continuously at 500 RPM. After 20 hours. Let the autoclave cool, release the pressure, and turn off the fan.

[0067] Then remove the cured upper and lower mold parts from the autoclave and assemble them into Figure 2AIn the fully - tooled brake disc shown, 4.5 kg of A356.2 alloy was melted in a clay - bonded graphite crucible in a furnace heated to 750 °C for 1 hour. The crucible containing the melt was removed from the furnace. The melt was skimmed of dross and then poured into the mold through a filter. After 1 hour, the solidified metal was shaken out of the mold by breaking the mold material. Excess metal from the mold gate was removed from the casting. Figure 2B The resulting brake disc in the photograph shows visible fine details and a high - quality surface finish.

[0068] Example 3: Magnesium - aluminum - phosphate - bonded sand core material

[0069] 3500 g of silica sand (Wedron grade 410) was mixed with 35 g of magnesium oxide powder (d 50 = ~ 3 μm) and 105 g of ball clay using a vertical mixer. Once the mixture was well - homogenized, 105 g of an aqueous solution containing 40 wt% Al(H 2 PO 4 ) 3 , 30 wt% H 3 PO 4 and 30 wt% water was added and mixing continued for 1.5 minutes. The final mixture was formed into 12 dog - bone - shaped samples, as well as a disc sample and a 500 - mL cup - shaped sample. The working time of the test samples was measured, then the samples were stripped and the tensile strength was tested at different time intervals under different humidity conditions.

[0070] Example 4: Magnesium - aluminum - iron - phosphate - bonded sand core material

[0071] 2200 g of silica sand (Wedron grade 410) was mixed with 77 g of an aqueous solution containing 45 wt% Al(H 2 PO 4 ) 3 , 23 wt% H 3 PO 4 and 32 wt% water. Once the mixture was well - homogenized, 30 g of a powder consisting of 90 wt% MgO and 10 wt% Fe 2 O 3 was added and mixing continued for 1.5 minutes. The MgO and Fe 2 O 3 precursor was fired to 1300 °C before being added to the mixture, and the resulting aggregate was crushed and sieved to 325 mesh. The final mixture was formed into 15 dog - bone - shaped samples, as well as a disc sample. The working time of the test samples was measured, then the samples were stripped and the tensile strength was tested at different time intervals under different humidity conditions. The typical properties of these samples are summarized in Table 1 below.

[0072] Table 1

[0073]

[0074] Example 5: Strontium Titanate - Bonded Sand Core

[0075] 101 g of KOH was dissolved in 6 kg of deionized water by manual stirring for 5 minutes. The solution was sprayed with flowing N 2 gas for 12 hours to remove dissolved CO 2 . Then 783 g of Sr(OH) 2 -8H 2 O was magnetically stirred into the solution for 20 minutes. Additionally, 87 g of synthetic olivine sand (AFS GFN 70) was mixed with 10 g of 3 mol% yttria - stabilized zirconia powder and 3 g of deionized water. The sand mixture was compacted into a borosilicate glass tube with a length and diameter of 37 mm. The tube containing the compacted sand mixture was sealed within a cylindrical stainless - steel housing (50 mm diameter x 100 mm long), which served as a core box and was designed to allow heating and the flow of high - pressure liquid through it. The housing was heated to 200 °C and the KOH / Sr(OH) 2 solution was pumped through the housing at 80 psig for 1 hour. Then the cylinder was removed from the core box and dried in a convection oven at 100 °C to remove residual water.

[0076] After that, the cylinder was subjected to hot - compressive strength and permeability tests to demonstrate that it had sufficient refractory and mechanical properties for casting applications. Alternatively, part or all of the Sr(OH) 2 was replaced with Ba(OH) 2 , and part or all of the ZrO 2 was replaced with TiO 2 to reduce the curing temperature.

[0077] Example 6: Calcium Silicate - Calcium Carbonate - Bonded Investment Casting Mold

[0078] 11 g of Darvan 811 dispersant (sodium polyacrylate solution) and 15 g of potassium chloride were dissolved in 2 kg of deionized water with stirring. The resulting mixture was heated to 80 °C, during which 20 g of κ - carrageenan was dissolved into the mixture with stirring. Once a clear, light - yellow mixture was obtained, 3.8 kg of pre - heated calcium silicate (CaSiO 3 ) powder (NYAD 400) was added to the heated mixture while mixing with a blade mixer rotating at 2500 rpm to form a thermo - reversible slurry containing CaSiO 3 . Once the thermo - reversible slurry reached a satisfactory uniformity, it was placed in a suitable heated container for the impregnation process. In this example, the slurry did not contain refractory sand or stucco, and the only particulate refractory material was CaSiO 3Wash the sprue-mounted beeswax owl statue with a diluted citrus wax cleaning solution, rinse, and dry for use as a casting pattern. Maintain the slurry at a temperature of 70 °C, then immerse the pattern in the slurry for 3 seconds and then remove. Hold the coated pattern for 1 minute and then immerse it again for 3 seconds. This cycle is repeated a total of 5 times. After each immersion step, the slurry is cooled to a temperature of about 50 °C or lower, and a thermoreversible gel is formed on the casting pattern.

[0079] Hang the fully coated casting pattern (i.e., the casting pattern coated with a complete thermoreversible gel coating formed by the immersion steps) in a 230 L autoclave and use CO 2 to cure to form an investment casting mold (such as a shell) on the casting pattern. In particular, the autoclave is sealed, heated to 40 °C, and filled with completely dry CO 2 until a pressure of 60 psig is reached. The autoclave is maintained under these conditions for 20 hours, and the fan on the lid rotates continuously at 500 RPM. After 20 hours have passed, allow the autoclave to cool, release the pressure, and turn off the fan.

[0080] Then remove the cured mold from the autoclave and remove the pattern material by hanging the assembly upside down in a convection oven maintained at 150 °C, thereby obtaining a mostly "dewaxed" mold. Subsequently, heat the mold to 450 °C for 2 hours to remove the residual wax and preheat the mold, while melting 300 g of A356.2 alloy in a clay-bonded graphite crucible in a furnace heated to 750 °C for 1 hour. Remove the hot mold and crucible containing the melt from their respective furnaces. The melt is skimmed of slag and then poured into the mold. After 1 hour, shake the solidified metal out of the mold by breaking the mold material. Figure 3 is a photograph showing the resulting A356.2 alloy owl 10, which has visible fine details and a high-quality surface finish, as well as an example of the wax pattern 12.

[0081] Example 7: Calcium silicate-calcium carbonate bonded investment shell for casting high melting point metals and alloys

[0082] 140 g of a colloidal silica suspension (Nalco 1030) is diluted with 300 g of deionized water. The resulting diluted colloidal silica suspension is magnetically stirred at a speed of 200 rpm for 10 minutes. Next, 50 g of a polymer suspension (Nalco ESP6305) is mixed with the diluted colloidal silica suspension, and the resulting suspension is magnetically stirred again at a speed of 200 rpm for 30 minutes. After that, 2600 g of 200-mesh zircon powder (ZrSiO 4) It was gradually added to the suspension while stirring to form a zircon slurry. Once the zircon slurry was free of visible powder aggregates, it was continuously stirred with an overhead stirrer at low speed for 2 - 3 hours to remove any entrapped air bubbles.

[0083] A clean wax pattern was slowly immersed in the zircon slurry within 60 seconds and held for 3 - 5 seconds, then the pattern was removed from the slurry, tilted and rotated to drain the excess slurry. Then the coated pattern was dusted with zircon powder and dried under ambient conditions for 15 minutes. The wax pattern was again slowly immersed in the zircon slurry within 60 seconds and held for 3 - 5 seconds, then it was removed, drained of slurry, dusted with stucco and dried for 30 minutes. When the coated zircon slurry was dried, colloidal silica and the polymer formed a gel.

[0084] Then the coated and dried pattern was dip - coated with the thermoreversible slurry of Example 5. Then the fully coated pattern was suspended in a 230L autoclave. The autoclave was sealed, heated to 40 °C, and filled with completely dry CO 2 until a pressure of 60 psig was reached. The autoclave was maintained under these conditions for 20 hours with a fan covering rotating continuously at 500 RPM. After 20 hours had passed, the autoclave was allowed to cool, the pressure was released, and the fan was turned off.

[0085] For the following examples, the processing details of the raw material mixing and / or the corresponding thermoreversible slurry preparation are provided for each investment casting mold or shell - forming scenario. Other processing steps capable of forming the mold / shell such as primary slurry preparation, dip - coating, and LTS process are the same as those described in Example 6.

[0086] Example 8: Mixture of calcium silicate and aluminosilicate

[0087] 2 kg of calcium silicate powder and 2 kg of aluminosilicate powder (mullite) (Mulcoa 60) were manually mixed for 30 minutes and then pre - heated in a convection oven at 85 °C for at least 12 hours. 4 kg of the mixture was used to replace 3.8 kg of calcium silicate in the thermoreversible slurry formulation described in Example 6 and then cured as described in Example 6. The aluminosilicate powder was used as a non - reactive filler in this example.

[0088] Example 9: Mixture of calcium silicate, fused silica, and calcium carbonate

[0089] 1494 g of calcium silicate powder, 2490 g of fused silica powder (Ranco - Sil - 200 mesh), and 996 g of calcium carbonate powder were mixed and heated in the same manner as in Example 8. 3.635 kg of this mixture was used to replace 3.8 kg of calcium silicate in the thermoreversible slurry formulation described in Example 6 and then cured as described in Example 6. If the mold material is fired, calcium carbonate can be used as a sintering aid to strengthen the mold material.

[0090] Example 10: Thermoreversible Slurry Incorporating Colloidal Silica Binder

[0091] 7.5 g of potassium chloride (KCl) was added to 1 L of deionized water. The resulting KCl solution was magnetically stirred at a speed of 200 rpm for 10 minutes. Subsequently, 5.5 g of sodium polyacrylate dispersant (Darvan 811) was mixed with the KCl solution and stirring was continued for 30 minutes. Then, 90 g of colloidal silica suspension (Nalco 1030) was added, and the resulting suspension was stirred at 300 rpm for another 10 minutes. Finally, 20 g of κ-carrageenan was added to the suspension, and the resulting thermoreversible suspension was heated to 85 °C and stirred at 550 rpm for 1 hour.

[0092] Separately, 346 g of calcium silicate powder and 1959 g of fused silica powder were mixed and heated in the same manner as in Example 8. The suspension and the powder mixture were mixed to produce a thermoreversible slurry as described in Example 6, and then it was cured as described in Example 6.

[0093] Example 11: Thermoreversible Slurry Containing Magnesium Oxide

[0094] Pure magnesium oxide powder was fired in a muffle furnace at 1500 °C for 3 hours. Then the resulting dead-burned magnesium oxide powder aggregates (MgO) were crushed, ground, and sieved to 170 mesh. 319 g of calcium silicate powder, 1716 g of fused silica powder, and 150 g of sieved dead-burned magnesium oxide powder were mixed and heated as described in Example 8. A thermoreversible suspension was prepared as described in Example 10, and the suspension and 2.185 kg of the powder mixture were mixed to prepare a thermoreversible slurry as described in Example 6, and then it was cured as described in Example 6.

[0095] Example 12: Thermoreversible Slurry Containing Calcium Oxide

[0096] Calcium carbonate powder was fired in a muffle furnace at 1300 °C for 3 hours. Then the resulting dead-burned calcium oxide powder aggregates were crushed, ground, and sieved to 170 mesh. 296 g of calcium silicate powder, 1485 g of fused silica powder, and 198 g of sieved dead-burned calcium oxide powder were mixed and heated as described in Example 8. A thermoreversible suspension was prepared as described in Example 10, and the suspension and 1.979 kg of the powder mixture were mixed to prepare a thermoreversible slurry as described in Example 6, and then it was cured as described in Example 6.

[0097] Example 13: Thermoreversible Slurry Containing Fused and Colloidal Silica

[0098] Prepare a thermoreversible suspension containing colloidal silica as described in Example 9, except that 160 g of colloidal silica is used instead of 90 g and 20 g of carrageenan is used instead of 40 g. Once the suspension is homogeneous and heated to 85 °C, immediately stir it with a blade mixer at a speed of 2000 rpm. Then, slowly add 2200 g of preheated molten silica powder (preheated to 85 °C for 12 hours) to the stirred solution. After the molten silica powder is completely added, continue mixing for 1 - 2 minutes until there are no visible powder aggregates in the slurry. Pour the homogeneous slurry into a preheated plastic container (Bel-Art Products, Wayne, NJ), seal it, and store it in a convection oven at 85 °C for later use.

[0099] Example 14: Refractory matrix sample containing fused magnesia

[0100] Mix 80 g of fused magnesia powder (325 mesh), 20 g of graphite powder (100 mesh), and 4 g of water in a high-strength mixer for 5 minutes. Once the mixture is homogeneous enough, use a hydraulic press with a pressure of ~18 ksi to form it into a disc-shaped sample (5 cm in diameter, 2 cm thick). Then place the sample in a 4 L autoclave. Seal the autoclave, heat it to 60 °C, and fill it with completely dry CO 2 , until a pressure of 120 psig is reached. The autoclave is maintained under these conditions for 20 hours, then allowed to cool and the pressure is released. Then dry the brick overnight at 125 °C and test various physical properties.

[0101] Example R2: Refractory matrix sample containing dead-burned magnesia

[0102] Mix 80 g of dead-burned MgO (d 50 = 3 μm), 20 g of carbon black particles, and 4 g of water in a high-strength mixer for 5 minutes. Then form it into a disc sample, and then cure and test the sample as described in Example R1.

[0103] Example R3: Refractory matrix sample containing mixed carbon

[0104] Mix 80 g of fused MgO (325 mesh), 10 g of graphite powder (100 mesh), 10 g of carbon black particles, and 4 g of water in a high-strength mixer for 10 minutes. Then form it into a disc sample, and then cure and test the sample as described in Example R1.

[0105] Example R4: Refractory matrix sample containing mixed magnesia and carbon

[0106] Mix 40 g of fused MgO (325 mesh), 40 g of dead-burned MgO (d 503 μm), 14 g of graphite powder (100 mesh), 4 g of carbon black particles, 2 g of graphene nanopowder, and 4 g of water were mixed in a high-intensity mixer for 15 minutes. Then it was formed into a disc sample, and then the sample was cured and tested as described in Example R1.

[0107] Example R5: Refractory brick manufacturing

[0108] 16.4 kg of molten magnesium oxide aggregate, 3.2 kg of graphite powder, and 0.4 kg of water were mixed in a high-intensity mixer for 10 minutes. The solids in the resulting mixture had a wide particle size range (e.g., 0.001–4 mm). Once the mixture was sufficiently homogeneous, it was formed into 5 refractory bricks using a hydraulic press with a pressure of ∼18 ksi. Then the bricks were placed in a 230 L autoclave. The autoclave was sealed, heated to 60 °C, and filled with completely dry CO 2 , until a pressure of 60 psig was reached. The autoclave was maintained under these conditions for 20 hours, with the fan on the lid rotating continuously at 500 RPM. After 20 hours had passed, the autoclave was allowed to cool, the pressure was released, and the fan was turned off. Then the bricks were dried overnight at 125 °C and tested for various physical properties.

[0109] The foregoing description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the invention. Thus, the invention is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of forming a casting element for casting, the method comprising: forming an aqueous slurry comprising a solid inorganic binder material or a precursor thereof; pressing the slurry against a pattern to form a shaped slurry; curing the shaped slurry at a temperature below 350 °C to form a casting element; and removing the pattern from the casting element, wherein the solid inorganic binder material comprises at least one component selected from: magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium carbonate hydrate, calcium oxide, calcium hydroxide, calcium carbonate, calcium silicate, dicalcium silicate, tricalcium silicate, calcium aluminate, calcium aluminosilicate and rare earth oxides; wherein said curing comprises permeating the shaped slurry with CO at a temperature of 15 °C to 350 °C and a pressure of 0.5 psig to 5000 psig 2 ; wherein the slurry comprises an inert component selected from: oxide sand, diamond, graphite, carbon black, graphene, graphene oxide, metal carbide, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate and dolomite, wherein the inert component does not react with the binder material or its precursor.

2. A method of forming a casting element for casting, the method comprising: forming an aqueous slurry comprising a solid inorganic binder material or a precursor thereof; pressing the slurry against a pattern to form a shaped slurry; curing the shaped slurry at a temperature below 350 °C to form a casting element; and removing the pattern from the casting element, wherein the solid inorganic binder material comprises at least one component selected from: magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium carbonate hydrate, calcium oxide, calcium hydroxide, calcium carbonate, calcium silicate, dicalcium silicate, tricalcium silicate, calcium aluminate, calcium aluminosilicate and rare earth oxides; wherein said curing comprises permeating the formed slurry with CO at a temperature of 15°C to 350°C and a pressure of 0.5 psig to 5000 psig 2 ; wherein the slurry comprises an inert component selected from: zirconia, titanium dioxide, alumina, diamond, graphite, carbon black, graphene, graphene oxide, metal carbide, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate and dolomite, wherein the inert component does not react with the binder material or its precursor.

3. The method according to claim 1, wherein the metal carbide is selected from tungsten carbide and niobium carbide.

4. The method according to claim 2, wherein the metal carbide is selected from tungsten carbide and niobium carbide.

5. The method according to any one of claims 1-4, wherein the curing occurs only after the slurry is shaped.

6. The method according to any one of claims 1-4, wherein: the solid inorganic binder material is combined with a) one or more clays; b) colloidal silica; and c) one or more elements in the form of oxides, hydroxides and / or hydrated oxides, the elements being selected from magnesium, aluminum, iron, zinc, zirconium, titanium, vanadium, yttrium, lithium, sodium, potassium, bismuth, cerium, strontium, calcium, barium, lanthanum, copper and boron; The slurry further comprises d) H 3 PO 4 and e) refractory sand.

7. The method according to any one of claims 1-4, wherein: wherein the solid inorganic binder material is combined with a) one or more clays; b) colloidal silica; and c) one or more elements in the form of oxides, hydroxides and / or hydrated oxides, said elements being selected from magnesium, aluminum, iron, zinc, zirconium, titanium, vanadium, yttrium, lithium, sodium, potassium, bismuth, cerium, strontium, calcium, barium, lanthanum, copper and boron.

8. The method according to any one of claims 1-4, wherein the solid inorganic binder material comprises calcium monosilicate with a purity of 95 wt% or higher before being added to the binder material.

9. The method according to any one of claims 1-4, wherein the solid inorganic binder comprises calcium monosilicate with a purity ranging from 25 to 95 wt% before being added to the binder material, and the impurities are calcium silicate cement from the kiln.

10. The method according to any one of claims 1-4, wherein the solid inorganic binder comprises calcium monosilicate with a purity of 25-100 wt% before being added to the binder material.

11. The method according to any one of claims 1-4, wherein the solid inorganic binder material comprises calcium monosilicate, and CO 2 permeates the formed slurry to convert at least part of the calcium monosilicate into calcium carbonate and silicon dioxide in the sand casting casting.

12. The method according to any one of claims 1-4, wherein: the solid inorganic binder material comprises magnesium oxide; Using CO 2 Partially convert magnesia to magnesite with infiltrated formed slurry to form a casting element for refractory bricks, castables, gunning mixes or ramming mixes, wherein the resulting casting element contains MgO particles bonded to each other by magnesite particles, and wherein the MgO particles are larger than the magnesite particles.

13. The method according to any one of claims 1-4, wherein the slurry further comprises a thermoreversible additive, and the thermoreversible additive comprises carrageenan, potassium chloride, calcium chloride, agarose, hydroxyethyl cellulose, or any combination thereof.

14. The method according to any one of claims 1-4, wherein: forming the slurry comprises: heating the slurry to a temperature in the range of 4°C to 350°C; dipping the pattern in the slurry to form a coating on the pattern; gelling the coating by cooling the coating to a temperature below 40°C.

15. The method according to claim 14, wherein forming the slurry further comprises repeating the dipping and gelling at least once to form a shaped slurry, and further comprises melting the pattern to form an investment casting mold.

16. The method according to claim 14, wherein the solid inorganic binder material comprises at least one component selected from the following: magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, calcium monosilicate, dicalcium silicate, tricalcium silicate, calcium aluminate, calcium aluminosilicate and rare earth oxides, wherein the solid inorganic binder material is combined with a) one or more clays; b) colloidal silica, and c) one or more elements in the form of oxides, hydroxides and / or hydrated oxides, said elements being selected from magnesium, aluminum, iron, zinc, zirconium, titanium, vanadium, yttrium, lithium, sodium, potassium, bismuth, cerium, strontium, calcium, barium, lanthanum, copper and boron; wherein forming the slurry comprises pressing the slurry against the pattern; Curing comprises permeating the formed slurry with CO at a temperature of 15 °C to 350 °C and a pressure of 0.5 psig to 5000 psig; and 2 and wherein the slurry further comprises refractory sand.

17. The method according to any one of claims 1-4, wherein: The binder precursor includes ZrO 2 and TiO 2 at least one of; the slurry further comprises refractory sand; and curing comprises infiltrating the casting element with an aqueous solution comprising KOH and at least one of calcium, strontium or barium precursors.

18. The method according to any one of claims 1-4, wherein: the binder precursor comprises at least one of zirconia and titanium dioxide; the slurry further comprises refractory sand; and Solidifying includes permeating the casting element with an aqueous solution of a hydroxide, including at least one of calcium, strontium, barium, and their precursors.

19. The method according to any one of claims 1-4, wherein the binder precursor comprises at least one of the chemical formulas ABO 3 wherein A is magnesium, calcium, strontium or barium, B is titanium or zirconium, and ABO 3 is in the form of a linear compound, a solid solution or a multiphase mixture of ABO 3 compounds; and wherein the method includes using CO 2 to infiltrate the formed slurry and convert at least a part of ABO 3 into A-site metal carbonate and B-site metal dioxide.

20. The method according to claim 18, wherein the solidifying includes permeating the casting element with the aqueous solution at a temperature of 150 °C to 350 °C and a pressure of 0.5 psig to 3000 psig for a period of 5 minutes to 48 hours.

21. The method according to claim 19, wherein the solidifying includes permeating the casting element with the aqueous solution at a temperature of 15 °C to 350 °C and a pressure of 0.5 psig to 3000 psig for a period of 5 minutes to 48 hours.

22. The method according to any one of claims 1-4, wherein the solid inorganic binder material comprises at least one of MgO and Fe 2 O 3 ; wherein the slurry further comprises refractory sand; at least one of aluminum hydroxide and hydrated alumina; and phosphoric acid; Shaping the slurry includes pressing the slurry against a pattern.

23. The method according to any one of claims 1 - 4, wherein the solidifying includes holding the shaped slurry in the pattern for a period of 30 seconds to 48 hours.

24. The method according to any one of claims 1 - 4, wherein the slurry further includes silica sand, olivine sand, chromite sand, zircon sand, burned clay sand, aluminosilicate sand, or any combination thereof.

25. The method according to any one of claims 1 - 4, further including applying molten metal to the casting element, wherein the casting element includes a sand casting mold, a sand casting core, an investment casting shell, a refractory mortar, and wherein the refractory mortar is a refractory brick, a gunning mix, a patching mix, or a ramming mix.

26. A method of forming a casting element for casting, the method comprises: forming an aqueous first slurry comprising refractory sand, colloidal silica, and a binder polymer; forming an aqueous second slurry comprising a solid inorganic binder material and a thermoreversible additive; applying the first slurry to a pattern to form a first coating; heating the second slurry to a temperature of 40 °C to 250 °C; immersing the pattern in the heated second slurry to form a second coating on the first coating; gelatinizing the second coating by cooling the second coating to a temperature below 40 °C; By using CO at a temperature of 15°C to 350°C and a pressure of 0.5 psig to 5000 psig 2 to permeate a second coating to form a casting element having a 2 - coating; wherein the solid inorganic binder material includes at least one component selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium carbonate hydrate, calcium oxide, calcium hydroxide, calcium carbonate, calcium monosilicate, dicalcium silicate, tricalcium silicate, calcium aluminate, calcium aluminosilicate, and rare earth oxides; wherein the first slurry and / or the second slurry comprises an inert component selected from the group consisting of oxide sand, diamond, graphite, carbon black, graphene, graphene oxide, metal carbide, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate, and dolomite, and wherein the inert component does not react with the binder material or the binder polymer.

27. A method of forming a casting element for casting, the method comprises: forming an aqueous first slurry comprising refractory sand, colloidal silica, and a binder polymer; forming an aqueous second slurry comprising a solid inorganic binder material and a thermoreversible additive; applying the first slurry to a pattern to form a first coating; Heat the second slurry to a temperature of 40°C to 250°C; immerse the pattern in the heated second slurry to form a second coating on the first coating; Gel the second coating by cooling the second coating to a temperature below 40°C; At a temperature of 15°C to 350°C and a pressure of 0.5 psig to 5000 psig by permeating a second coating with CO 2 to form a 2-coated casting element; Wherein the solid inorganic binder material comprises at least one component selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium carbonate hydrate, calcium oxide, calcium hydroxide, calcium carbonate, calcium silicate monohydrate, dicalcium silicate, tricalcium silicate, calcium aluminate, calcium aluminosilicate, and rare earth oxides; Wherein the first slurry and / or the second slurry comprises an inert component selected from the group consisting of zirconia, titanium dioxide, alumina, diamond, graphite, carbon black, graphene, graphene oxide, metal carbides, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate, and dolomite, wherein the inert component does not react with the binder material or the binder polymer.

28. The method according to claim 26, wherein the metal carbide is selected from tungsten carbide and niobium carbide.

29. The method according to claim 27, wherein the metal carbide is selected from tungsten carbide and niobium carbide.

30. The method according to any one of claims 26-29, wherein the impregnation and gelling are carried out at least twice to form a three-layer structure.

31. The method according to any one of claims 26-29, wherein the refractory sand comprises zircon sand; Wherein the method further comprises applying additional zircon sand to the first coating; the solid inorganic binder material comprises at least one component selected from the group consisting of magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, calcium silicate monohydrate, dicalcium silicate, tricalcium silicate, calcium aluminate, calcium aluminosilicate, and rare earth oxides.

32. A casting element for casting, prepared by the method according to any one of claims 26-31, the casting element comprises: Refractory sand; and A binder comprising an aqueous magnesium aluminum phosphate gel mixed with one or more of clay, fumed silica, and a soluble precursor of zinc or rare earth lanthanide ions; and An inert component selected from oxide sand, diamond, graphite, carbon black, graphene, graphene oxide, metal carbides, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate, and dolomite, wherein the inert component does not react with the binder.

33. A casting element for casting, prepared by the method according to any one of claims 26-31, the casting element comprises: Refractory sand; and A binder comprising an aqueous magnesium aluminum phosphate gel mixed with one or more of clay, fumed silica, and a soluble precursor of zinc or rare earth lanthanide ions; and An inert component selected from zirconia, titanium dioxide, alumina, diamond, graphite, carbon black, graphene, graphene oxide, metal carbides, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate, and dolomite, wherein the inert component does not react with the binder.

34. The casting element according to claim 32, wherein the metal carbide is selected from tungsten carbide and niobium carbide.

35. The casting element according to claim 33, wherein the metal carbide is selected from tungsten carbide and niobium carbide.

36. The casting element according to any one of claims 32-35, wherein the refractory sand comprises silica sand, olivine sand, chromite sand, zircon sand, burned clay sand, aluminosilicate sand, or any combination thereof, and wherein the casting element comprises a sand casting mold, a sand casting core, an investment casting shell, refractory mud, and wherein the refractory mud is refractory brick, castable, gunning mix, or ramming mix.

37. A method of forming a casting element for casting, the method comprises: forming an aqueous slurry comprising a solid inorganic oxide material; at a temperature of from 15°C to 350°C and a pressure of from 0.5 psig to 5000 psig by passing CO 2 through the permeable slurry to at least partially convert the solid inorganic oxide material to a solid inorganic carbonate material and form a casting element for casting for refractory bricks, castables, gunning mixes or ramming mixes; wherein the casting element for casting comprises an inert component selected from oxide sand, diamond, graphite, carbon black, graphene, graphene oxide, metal carbide, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate, and dolomite, wherein the inert component does not react with the inorganic oxide material.

38. A method of forming a casting element for casting, the method comprises: forming an aqueous slurry comprising a solid inorganic oxide material; at a temperature from 15°C to 350°C and a pressure from 0.5 psig to 5000 psig by passing CO 2 through the permeable slurry to at least partially convert the solid inorganic oxide material to a solid inorganic carbonate material and form a casting element for casting for refractory bricks, castables, gunning mixes or ramming mixes; wherein the casting element for casting comprises an inert component selected from zirconia, titanium dioxide, alumina, diamond, graphite, carbon black, graphene, graphene oxide, metal carbide, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate, and dolomite, wherein the inert component does not react with the inorganic oxide material.

39. The method according to claim 37, wherein the metal carbide is selected from tungsten carbide and niobium carbide.

40. The method according to claim 38, wherein the metal carbide is selected from tungsten carbide and niobium carbide.

41. The method according to any one of claims 37 - 40, wherein the solid inorganic oxide material comprises CaSiO 3 , and at least part of the CaSiO 2 is converted into calcium carbonate in the sand casting by infiltrating the slurry with CO 3 .

42. The method according to any one of claims 37-40, wherein: the solid inorganic oxide material comprises MgO; Using CO 2 Partially convert MgO to magnesium carbonate by infiltrating the formed slurry to form a casting element for refractory bricks, castables, gunning mixes or ramming mixes; wherein the refractory brick comprises MgO particles mutually bonded by magnesium carbonate particles, wherein the MgO particles are larger than the magnesium carbonate particles.

43. The method according to any one of claims 37-40, wherein the slurry comprises the inert component and the resulting casting element is mixed with the inert component.

44. A refractory brick, castable, gunning mix, or ramming mix, comprising MgO particles mutually bonded by magnesium carbonate particles, wherein the MgO particles are larger than the magnesium carbonate particles, formed from a casting element for casting prepared by the method of forming a casting element for casting according to any one of claims 37-43, further comprising an inert component selected from the following: oxide sand, diamond, graphite, carbon black, graphene, graphene oxide, metal carbide, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate, and dolomite, wherein the inert component does not react with the MgO particles and the magnesium carbonate particles.

45. A refractory brick, castable, gunning mix or ramming mix, comprising MgO particles bonded to each other by magnesium carbonate particles, wherein the MgO particles are larger than the magnesium carbonate particles, and which is formed from a casting element for casting obtained by the method for forming a casting element for casting according to any one of claims 37 - 43, further comprising an inert component selected from: zirconia, titanium dioxide, alumina, diamond, graphite, carbon black, graphene, graphene oxide, metal carbides, silicon carbide, boron carbide, titanium boride, zirconium boride, olivine, diopside, garnet, spinel, quartz, cristobalite, tridymite, calcium carbonate and dolomite, wherein the inert component does not react with the MgO particles and the magnesium carbonate particles.

46. The refractory brick according to claim 44, wherein the metal carbide is selected from including tungsten carbide and niobium carbide.

47. The refractory brick according to claim 45, wherein the metal carbide is selected from including tungsten carbide and niobium carbide.

48. The refractory brick according to any one of claims 44 - 47, wherein the refractory brick mainly consists of larger MgO particles bonded to each other by smaller magnesium carbonate particles, and the refractory brick does not include organic materials.

49. A ladle or blast furnace for containing molten metal, the inner surface of which is lined with the refractory brick according to any one of claims 44 - 48.

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