Ceramic particles for crucible having excellent corrosion resistance

Abstract

Ceramic particles for a crucible according to embodiments of the present invention comprise: a ceramic core part containing silicon; and a first shell part located on the surface of the ceramic core part and having a lower silicon content than the ceramic core part. In a crucible manufacturing method according to embodiments of the present invention, the ceramic core part is manufactured by mixing inorganic materials including cordierite. The ceramic particles for manufacturing a crucible are manufactured by mixing an inorganic mixture, a binder, and spinel. The ceramic particles for manufacturing a crucible are compression-molded.

Description

Ceramic particles for crucibles with excellent corrosion resistance

[0001] The present invention relates to ceramic particles for crucibles having excellent corrosion resistance. More particularly, it relates to ceramic particles for crucibles having a core-shell structure.

[0002] Ceramics are a general term for inorganic compounds containing metallic elements and one or more non-metallic elements. Ceramics typically include materials with a crystal structure formed by combining metallic elements and non-metallic elements, such as metal oxides, nitrides, and silicides. The characteristics of ceramic particles can vary depending on the type and mixing ratio of the materials contained within them.

[0003] Ceramics generally possess excellent heat resistance, corrosion resistance, and wear resistance, and depending on the material type, they can exhibit properties such as magnetism, dielectric properties, and biocompatibility, making them useful in a variety of technical fields. Examples include glass, lime, cement, gypsum, and crucibles.

[0004] A crucible is a vessel used for firing inorganic materials or inorganic / organic hybrid materials. It can be used in a variety of fields requiring high-temperature firing. Examples include heat treatment of cathode materials for secondary batteries, melting of metals like aluminum or copper alloys, melting of glass, and firing and analyzing chemical raw materials.

[0005] Crucibles require heat resistance, impact resistance, and chemical resistance depending on their intended use. The required crucible properties may vary depending on the application, and accordingly, crucibles are manufactured using a variety of materials, including ceramics. For example, alumina, zirconia, graphite, platinum, and quartz are used in crucible manufacturing, and the properties of the crucible vary depending on the mixing ratio of each material.

[0006] Crucibles can be used for the high-temperature sintering of metal components used in lithium secondary batteries, such as lithium composite metal oxides. However, during the repeated high-temperature sintering of lithium composite metal oxides, side reactions can occur, leading to cracks, corrosion, and peeling in the crucibles, resulting in their short-lived disposal.

[0007] Therefore, there is a need for materials that enhance the durability and chemical resistance of crucibles and produce crucibles with improved service life. In this regard, Korean Patent Publication No. 2012-0102396 discloses a crucible with a reduced coefficient of thermal expansion by controlling the composition of inorganic raw materials. However, due to its inadequate chemical resistance, a crucible with improved service life remains in demand.

[0008] One object of the present invention is to provide ceramic particles for crucibles with improved durability and chemical resistance.

[0009] One object of the present invention is to provide a crucible comprising ceramic particles for a crucible having improved durability and chemical resistance.

[0010] One object of the present invention is to provide a method for manufacturing a crucible with improved durability and chemical resistance.

[0011] One object of the present invention is to provide ceramic particles for manufacturing a crucible with improved durability and chemical resistance.

[0012] Ceramic particles for a crucible according to exemplary embodiments of the present invention include a ceramic core portion containing silicon and a first shell portion located on a surface of the ceramic core portion and having a lower silicon content than the ceramic core portion.

[0013] According to exemplary embodiments, the ceramic core portion and the first shell portion may further include aluminum.

[0014] According to exemplary embodiments, the aluminum content included in the first shell portion may be greater than the aluminum content included in the ceramic core portion.

[0015] According to exemplary embodiments, the ceramic core portion may include cordierite.

[0016] According to exemplary embodiments, the first shell portion may include spinel.

[0017] According to exemplary embodiments, the content of silicon among the total metal atoms included in the ceramic core portion may be 40% to 60%, and the content of silicon among the total metal atoms included in the first shell portion may be 5% or less.

[0018] According to exemplary embodiments, the content of aluminum among the total metal atoms included in the ceramic core portion may be 20% to 50%, and the content of aluminum among the total metal atoms included in the first shell portion may be 60% or more.

[0019] According to exemplary embodiments, the ceramic core portion and the first shell portion further include magnesium, and the content of magnesium among the total metal atoms included in the ceramic core portion may be 5% to 20%, and the content of magnesium among the total metal atoms included in the first shell portion may be 20% or more.

[0020] A method for manufacturing a crucible according to exemplary embodiments of the present invention includes a step of manufacturing a ceramic core by mixing an inorganic material including cordierite, a step of manufacturing ceramic particles for manufacturing a crucible by mixing the ceramic core, a binder, and spinel, and a step of compression molding the ceramic particles for manufacturing a crucible.

[0021] According to exemplary embodiments, the inorganic material may include at least one selected from the group consisting of alumina, mullite, kaolinite, clay, and ceramic fiber.

[0022] According to exemplary embodiments, the spinel in the step of manufacturing the ceramic particles for manufacturing the crucible may be coated on the ceramic core portion.

[0023] A crucible according to exemplary embodiments of the present invention comprises the ceramic particles for a crucible described above.

[0024] Ceramic particles for manufacturing a crucible according to exemplary embodiments of the present invention include a ceramic core portion containing silicon, a second shell portion located on a surface of the ceramic core portion and having a lower silicon content than the ceramic core portion, and a first shell portion located on a surface of the second shell portion and having a lower silicon content than the second shell portion.

[0025] According to exemplary embodiments, the ceramic core portion and the second shell portion further include aluminum atoms, and the content of aluminum atoms included in the second shell portion may be higher than the content of aluminum atoms included in the ceramic core portion.

[0026] According to exemplary embodiments, the first shell portion and the second shell portion further include aluminum atoms, and the content of aluminum atoms included in the first shell portion may be higher than the content of aluminum atoms included in the second shell portion.

[0027] Ceramic particles for crucibles according to exemplary embodiments of the present invention can have improved chemical resistance by lowering the reactivity of the ceramic particles.

[0028] Ceramic particles for crucibles according to exemplary embodiments of the present invention can have improved chemical resistance by suppressing side reactions due to lithium atoms, etc.

[0029] According to the method for manufacturing a crucible according to exemplary embodiments of the present invention, the silicon content in the first shell portion can be reduced, thereby improving the chemical resistance of the crucible.

[0030] The average particle diameter of the ceramic particles for manufacturing a crucible according to exemplary embodiments of the present invention may have a unimodal distribution. Accordingly, the first shell portion may suppress side reactions, thereby improving the lifespan characteristics of the crucible.

[0031] FIG. 1A and FIG. 1B are schematic diagrams showing the structure of ceramic particles for a crucible and ceramic particles for manufacturing a crucible according to exemplary embodiments.

[0032] Figure 2 is a schematic diagram showing a method for manufacturing a crucible.

[0033] FIGS. 3A and 3B are diagrams showing the appearance of ceramic particles for crucibles according to exemplary embodiments and comparative examples of the present invention.

[0034] FIG. 4 is a cross-sectional view of a crucible manufactured using ceramic particles for a crucible according to exemplary embodiments of the present invention.

[0035] FIG. 5 is a diagram showing the results of SEM analysis of a cross-section of a crucible manufactured using ceramic particles for a crucible according to exemplary embodiments of the present invention.

[0036] FIGS. 6A and 6B are SEM images of ceramic particles according to exemplary embodiments and comparative examples of the present invention.

[0037] FIGS. 7A and 7B are SEM images of crucibles containing ceramic particles according to exemplary embodiments and comparative examples of the present invention.

[0038] FIGS. 8A to 9B are diagrams showing EDS analysis images and analysis results of ceramic particles according to exemplary embodiments and comparative examples of the present invention.

[0039] FIGS. 10a to 11b are diagrams showing EDS analysis images and analysis results of crucibles containing ceramic particles according to exemplary embodiments and comparative examples of the present invention.

[0040] FIG. 12 is a diagram showing the results of evaluating the life characteristics of a crucible containing ceramic particles according to exemplary embodiments of the present invention.

[0041] Hereinafter, the present invention will be described in detail. The accompanying drawings will be described in detail, but they are provided as examples for explaining the present invention and are not intended to limit the present invention to the specific embodiments described as examples.

[0042] Throughout the specification of the present invention, when it is said that a component "includes", it means that other components may be included, rather than excluding other components, unless specifically stated otherwise.

[0043] Throughout the specification of the present invention, the content of a component may be expressed on a weight basis unless otherwise specifically defined. For example, a ceramic core portion having a silicon content of 40% to 60% may indicate that the weight of silicon is 40% to 60% of the total weight of the ceramic core portion.

[0044] The crucible of the present invention can be used for the purpose of calcining anode materials, but is not limited to the purpose of calcining anode materials, and can be used for, for example, calcining inorganic materials, gravimetric analysis, etc.

[0045] FIG. 1A is a schematic diagram illustrating ceramic particles for a crucible according to exemplary embodiments. FIG. 1B is a schematic diagram illustrating ceramic particles for manufacturing a crucible according to exemplary embodiments.

[0046] Referring to FIG. 1a, a ceramic particle (100) for a crucible includes a ceramic core portion (110) containing silicon and a first shell portion (150) having a lower silicon content than the ceramic core portion.

[0047] Ceramic particles (100) for a crucible can improve the life characteristics of the crucible by a core-shell structure including a ceramic core portion (110) and a first shell portion (150).

[0048] If a core-shell structure is not formed, the life characteristics of the crucible may deteriorate. For example, the silicon content may steadily decrease from the inside of the ceramic particles (100) for the crucible toward the outside or surface. However, if the silicon content does not change rapidly, the ceramic core portion (110) and the first shell portion (150) may not appear, and thus, side reactions due to lithium salts may occur inside the crucible, thereby accelerating the volume expansion of the crucible.

[0049] According to exemplary embodiments, the ceramic core portion (110) may further include aluminum or magnesium.

[0050] The ceramic core portion (110) may further include a metal element. For example, the metal element may include sodium (Na), potassium (K), calcium (Ca), zirconium (Zr), iron (Fe), zinc (Zn), lithium (Li), titanium (Ti), etc. The metal element may be included within a content range that does not change the physical properties of the crucible.

[0051] According to exemplary embodiments, the content of silicon among the total metal atoms included in the ceramic core portion (110) may be 40% to 60%.

[0052] According to exemplary embodiments, the content of aluminum among the total metal atoms included in the ceramic core portion (110) may be 20% to 50%.

[0053] According to exemplary embodiments, the content of magnesium among the total metal atoms included in the ceramic core portion (110) may be 5% to 20%.

[0054] Within the above content range, the porosity of the crucible can be reduced and the strength can be improved, thereby improving the durability of the crucible.

[0055] According to some embodiments, silicon, aluminum or magnesium may be included in the ceramic core portion (110) in the form of oxides.

[0056] For example, silicon may be included in silica in the form of an oxide, and the silica may be included in the ceramic core portion (110). Additionally, silicon, aluminum, or magnesium may be included in cordierite having a crystal structure, and the cordierite may be included in the ceramic core portion (110).

[0057] For example, the ceramic core (110) may include cordierite, silica, mullite, clay, alumina, etc.

[0058] According to exemplary embodiments, the ceramic core portion (110) may include cordierite.

[0059] Cordierite may contain MgO, Al2O3, and SiO2. Cordierite is a crystal containing the above three-component oxides, for example, cordierite may be expressed as 2MgO·2Al2O3·5SiO2.

[0060] The ceramic core (110) including cordierite can improve the porosity characteristics of the crucible and suppress cracking of the crucible caused by a material being fired within the crucible.

[0061] According to exemplary embodiments, the ceramic core portion (110) may further include silica.

[0062] In some embodiments, the ceramic core (110) may include an inorganic material obtained from a waste crucible.

[0063] For example, crucible powder can be produced by crushing or pulverizing waste crucibles, and ceramic particles for crucibles can be produced from the crucible powder and inorganic materials. Even when crucible powder obtained from waste crucibles is used, the reactivity of the crucible is reduced due to the formation of a core-shell structure, thereby producing a crucible with improved lifespan characteristics.

[0064] The first shell portion (150) has a lower silicon content than the ceramic core portion (110). The silicon content may change rapidly based on the boundary between the ceramic core portion (110) and the first shell portion (150).

[0065] As the silicon content of the first shell (150) is low, the reactivity of the crucible with lithium salts generated during the cathode material sintering process can be reduced, and thus the life characteristics of the crucible can be improved.

[0066] If the silicon content of the first shell portion (150) is higher than that of the ceramic core portion (110), the side reaction with the lithium salt may increase, accelerating the volume expansion of the crucible, and accordingly, the life characteristics of the crucible may rapidly deteriorate.

[0067] According to exemplary embodiments, the first shell portion (150) may further include aluminum or magnesium.

[0068] For example, the first shell portion (150) may further include a metal element. For example, the metal element may include sodium (Na), potassium (K), calcium (Ca), zirconium (Zr), iron (Fe), zinc (Zn), lithium (Li), titanium (Ti), etc.

[0069] According to exemplary embodiments, the content of aluminum included in the first shell portion (150) may be greater than the content of aluminum included in the ceramic core portion (110).

[0070] As the aluminum content of the first shell (150) increases, the chemical resistance of the crucible can be improved.

[0071] According to exemplary embodiments, the content of silicon among the total metal atoms included in the first shell portion (150) may be 5% or less. The lower limit of the silicon content included in the first shell portion (150) is not particularly limited, but may be, for example, 0.001% or more, or 0.005% or more. Within the above range, side reactions with lithium salts on the surface of the crucible may be reduced, thereby improving the lifespan of the crucible.

[0072] According to exemplary embodiments, the content of aluminum among the total metal atoms included in the first shell portion (150) may be 60% or more. In some embodiments, the content of aluminum among the total metal atoms included in the first shell portion (150) may be 60% or more and 90% or less, or 60% or more and 80% or less.

[0073] According to exemplary embodiments, the content of magnesium among the total metal atoms included in the first shell portion (150) may be 20% or more. In some embodiments, the content of magnesium among the total metal atoms included in the first shell portion (150) may be 20% to 40%, or 20% to 30% or less.

[0074] In the above content range, the strength of the crucible increases, and the durability of the crucible can be improved.

[0075] According to some embodiments, silicon, aluminum or magnesium may be included in the first shell portion (150) in the form of an oxide.

[0076] For example, aluminum may be included in spinel having a crystal structure, and the spinel may be included in the first shell portion (150). Alternatively, aluminum may be included in alumina in the form of an oxide, and the alumina may be included in the first shell portion (150).

[0077] For example, the first shell (150) may include silica, alumina, magnesia, etc.

[0078] According to exemplary embodiments, the first shell portion (150) may include spinel.

[0079] The above spinel may include MgO and Al2O3. Spinel is a crystal including the above binary oxide, and for example, spinel may be expressed as MgO·Al2O3.

[0080] According to exemplary embodiments, the first shell portion (150) including spinel can coat the surface of the crucible or the ceramic particles for the crucible. Accordingly, contact between silicon and lithium salt contained in the ceramic core portion can be prevented, thereby suppressing side reactions and improving the lifespan characteristics of the crucible.

[0081] According to exemplary embodiments, the first shell portion (150) may further include alumina or magnesia.

[0082] According to exemplary embodiments, the thickness of the first shell portion (150) may be 0.1 μm to 200 μm. In some embodiments, the thickness of the first shell portion (150) may be 1 μm to 150 μm, 5 μm to 100 μm, or 10 μm to 100 μm.

[0083] The above thickness may be a value measured in a vertical direction from the surface toward the center of the ceramic particle (100) for the crucible. In addition, the above thickness may represent the thinnest thickness of the first shell portion (150).

[0084] Within the above thickness range, even if cracks, fractures, etc. occur in the crucible, the chemical resistance of the crucible can be maintained, and accordingly, volume expansion of the crucible can be suppressed.

[0085] Referring to FIG. 1b, the ceramic particle (200) for manufacturing a crucible includes a ceramic core portion (110a) and a first shell portion (150a), and includes a second shell portion (120) disposed between the ceramic core portion (110a) and the first shell portion (150a).

[0086] For example, the ceramic core portion (110a) and the second shell portion (120) of the ceramic particle (200) for manufacturing a crucible may have a boundary formed by a binder. However, the boundary is not limited to the boundary formed by the binder, and the ceramic core portion (110a) and the second shell portion (120) may be divided by a point where the silicon content is distinguished.

[0087] According to exemplary embodiments, the ceramic core portion (110a) and the second shell portion (120) can be uniformly mixed with each other. For example, the binder may be removed during the sintering process for manufacturing the crucible, so that the ceramic core portion (110a) and the second shell portion (120) can be uniformly mixed with each other. The ceramic core portion (110) of the ceramic particle (100) for the crucible can be formed by uniformly mixing the ceramic core portion (110a) and the second shell portion (120) of the ceramic particle (200) for manufacturing the crucible.

[0088] For example, the ceramic core portion (110a) and the second shell portion (120) can be uniformly mixed with each other to form the ceramic core portion (110) of the ceramic particles (100) for the crucible described above.

[0089] According to exemplary embodiments, the ceramic core portion (110a) and the second shell portion (120) may include silicon.

[0090] According to exemplary embodiments, the silicon content of the second shell portion (120) may be lower than the silicon content of the ceramic core portion (110a).

[0091] According to exemplary embodiments, the silicon content of the first shell portion (150a) may be lower than the silicon content of the second shell portion (120).

[0092] By the above silicon content, a crucible having a core-shell structure and a controlled silicon content of the ceramic core portion (110) and the first shell portion (150) can be manufactured.

[0093] According to exemplary embodiments, the ceramic core portion (110a), the first shell portion (150a), and the second shell portion (120) may further include aluminum.

[0094] According to exemplary embodiments, the content of aluminum atoms included in the second shell portion (120) of the ceramic particle (200) for manufacturing a crucible may be higher than the content of aluminum atoms included in the ceramic core portion (110a).

[0095] According to exemplary embodiments, the content of aluminum atoms included in the first shell portion (150a) of the ceramic particle (200) for manufacturing a crucible may be higher than the content of aluminum atoms included in the second shell portion (120).

[0096] By the above aluminum content, a core-shell structure of the ceramic particles (100) for the crucible can be formed, and thus the chemical resistance of the crucible can be improved.

[0097] According to exemplary embodiments, the content of silicon atoms among the total metal atoms included in the ceramic core portion (110a) of the ceramic particle (200) for manufacturing a crucible may be 30% to 40%, and the content of silicon atoms among the total metal atoms included in the second shell portion (120) may be 20% to 30%.

[0098] According to exemplary embodiments, the content of silicon atoms among the total metal atoms included in the first shell portion (150a) of the ceramic particles (200) for manufacturing a crucible may be less than 20%. In some embodiments, the content of silicon atoms among the total metal atoms included in the first shell portion (150a) of the ceramic particles (200) for manufacturing a crucible may be 10% or less. The lower limit of the silicon atoms included in the first shell portion (150a) is not particularly limited, but may be, for example, 0.001% or more, or 0.005% or more.

[0099] According to exemplary embodiments, the content of aluminum atoms among the total metal atoms included in the ceramic core portion (110a) may be 40% to 50%, and the content of aluminum atoms among the total metal atoms included in the second shell portion (120) may be 50% to 70%.

[0100] According to exemplary embodiments, the content of aluminum atoms among the total metal atoms included in the first shell portion (150a) may be 60% or more. In some embodiments, the content of aluminum among the total metal atoms included in the first shell portion (150a) may be 60% to 90%, or 60% to 80%.

[0101] Within the above range, the content of each metal included in the ceramic core portion (110) and the first shell portion (150) of the above-described crucible ceramic particle (100) can be implemented.

[0102] According to exemplary embodiments, the ceramic core portion (110a), the second shell portion (120), and the first shell portion (150a) may each include silicon, aluminum, or magnesium in the form of an oxide.

[0103] For example, the ceramic core portion (110a) may include cordierite including MgO, Al2O3, and SiO2. For example, the second shell portion (120) may include mullite including Al2O3 and SiO2. For example, the first shell portion (150a) may include spinel including MgO and Al2O3.

[0104] According to exemplary embodiments, the ceramic core portion (110a) may include cordierite.

[0105] According to exemplary embodiments, the ceramic core portion (110a) may include an inorganic material obtained from a waste crucible.

[0106] According to exemplary embodiments, the second shell portion (120) may include at least one selected from the group consisting of mullite, alumina, or clay.

[0107] According to exemplary embodiments, the first shell portion (150a) may include spinel.

[0108] According to exemplary embodiments, the average particle diameter of the ceramic particles (200) for manufacturing a crucible may be from 1 mm to 10 mm. In some embodiments, the average particle diameter of the ceramic particles (200) for manufacturing a crucible may be from 1.5 mm to 8 mm or from 2 mm to 8 mm.

[0109] According to exemplary embodiments, the average particle diameter of the ceramic particles (200) for manufacturing a crucible may have a uni-modal distribution.

[0110] The above unimodal distribution can represent a distribution with one mode.

[0111] Since the average particle diameter of the ceramic particles (200) for manufacturing the crucible has a unimodal distribution, the ceramic core portion (110) and the first shell portion (150) of the ceramic particles (100) for the crucible can be distinguished, and the first shell portion (150) can suppress side reactions, thereby improving the life characteristics of the crucible.

[0112] The unimodal distribution described above allows the ceramic particles (100) for the crucible to be uniformly distributed within the crucible, thereby suppressing the penetration of lithium salts even when cracks or breaks occur in the crucible. Accordingly, the life characteristics of the crucible can be improved.

[0113] According to exemplary embodiments, the thickness of the first shell portion (150a) of the ceramic particle (200) for manufacturing a crucible may be 0.01 μm to 300 μm. In some embodiments, the thickness of the first shell portion (150a) of the ceramic particle (200) for manufacturing a crucible may be 0.1 μm to 250 μm, or 1 μm to 200 μm.

[0114] Figure 2 is a schematic diagram showing a method for manufacturing a crucible.

[0115] Referring to Fig. 2, a ceramic core is manufactured by mixing inorganic materials (e.g., S10 process).

[0116] For example, the inorganic material may include spinel, cordierite, mullite, kaolinite, silica, silicon carbide, talc, forsterite, corundum, alumina, petalite, spodumene, zircon, clay, or combinations thereof.

[0117] In exemplary embodiments, the inorganic material may include two or more selected from the group consisting of cordierite, alumina, mullite, clay, zirconia, ceria, silica, yttria, magnesia, talc, olivine, corundum, petalite, spodumene, kaolinite, zircon, yttria-magnesia, and yttria-alumina.

[0118] The above inorganic materials may include three or more types, four or more types, etc. For example, cordierite, alumina, mullite, and clay may be included together. The above inorganic materials may include two or more types in consideration of sinterability, crucible strength, corrosion resistance, etc.

[0119] According to exemplary embodiments, the inorganic material may include cordierite.

[0120] The content of each inorganic material used in the manufacture of the above ceramic core part can be determined by considering the content of spinel included to manufacture ceramic particles for manufacturing a crucible, which will be described later, after the manufacture of the ceramic core part.

[0121] For example, a ceramic core part may be manufactured from inorganic materials including cordierite, mullite, alumina, etc., and the content of each inorganic material may be determined based on the total weight of the weight of the ceramic core part and the weight of spinel (hereinafter referred to as “total weight of the inorganic mixture”).

[0122] According to exemplary embodiments, the content of the cordierite may be 20 wt% to 40 wt% of the total weight of the inorganic mixture.

[0123] In some embodiments, the content of cordierite may be from 22 wt% to 38 wt%, from 24 wt% to 36 wt%, from 26 wt% to 35 wt%, or from 28 wt% to 35 wt% of the total weight of the inorganic mixture.

[0124] According to exemplary embodiments, the inorganic material may include at least one selected from the group consisting of mullite, alumina, clay, and ceramic fibers.

[0125] According to exemplary embodiments, the inorganic material comprises mullite, and the content of the mullite may be from 4 wt% to 10 wt% of the total weight of the inorganic mixture.

[0126] According to exemplary embodiments, the inorganic material comprises alumina, and the content of the alumina may be from 4 wt% to 10 wt% of the total weight of the inorganic mixture.

[0127] According to exemplary embodiments, the inorganic material comprises clay, and the content of the clay may be from 10 wt% to 25 wt% of the total weight of the inorganic mixture.

[0128] According to exemplary embodiments, the inorganic material comprises ceramic fibers, and the content of the ceramic fibers may be from 1 wt% to 5 wt% of the total weight of the inorganic mixture.

[0129] In some embodiments, the ceramic fibers may include zirconia fibers or glass fibers. For example, the ceramic fibers may also act as a binder between inorganic components.

[0130] According to exemplary embodiments, the inorganic material may further include one or more selected from the group consisting of sodium oxide (Na2O), potassium oxide (K2O), calcium oxide (CaO), titanium oxide (TiO2), iron oxide (Fe2O3), and graphite (C).

[0131] The method of mixing the above-mentioned inorganic materials is not limited. For example, mixing can be performed using a known mixer. For example, the mixer may include a high-speed mixer, a Nauta mixer, a ribbon blender, a kneader, an intensive mixer, a universal mixer, a dissolver, a static mixer, a Henschel mixer, a Redige mixer, an internal mixer, a Banbury mixer, etc.

[0132] Referring to Fig. 2, the ceramic core, binder, solvent, and spinel are mixed to produce ceramic particles for crucible manufacturing (e.g., S20 process). The produced ceramic particles for crucible manufacturing are the same as the ceramic particles for crucible manufacturing (200) described above.

[0133] According to exemplary embodiments, ceramic particles for crucible manufacturing can be manufactured by mixing a ceramic core, a binder, a solvent, and a spinel and using a coating device or a mixer.

[0134] The above coating equipment can perform dry coating using known equipment. For example, the coating equipment can include a ball mill, a mechanofusion mixer, a spherical coating mixer, a paste mixer, a planetary mixer, a high-speed mixer, a shaker mill, a blade mill, etc.

[0135] The above mixer can use the known mixer described above.

[0136] According to exemplary embodiments, the content of the spinel may be from 20 wt% to 60 wt% of the total weight of the inorganic mixture.

[0137] In some embodiments, the content of the spinel may be from 20 wt% to 41 wt%, from 22 wt% to 40 wt%, or from 25 wt% to 39 wt% of the total weight of the inorganic mixture.

[0138] When spinel in the above content range is included, spinel can be evenly coated on the ceramic core portion, and thus a core-shell structure can be formed, thereby improving the life characteristics of the crucible.

[0139] For example, the binder may include polysaccharides such as starch, glycogen, cellulose, chitin, hyaluronic acid, agarose, carboxymethyl cellulose, methylcellulose, ethylcellulose, hydroxypropyl cellulose, dextrin, maltodextrin, and derivatives thereof; polymers such as polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, polyethylene, and polyurethane; tetrafluoroethylene, fluororubber, derivatives thereof, copolymers thereof, and the like.

[0140] According to exemplary embodiments, the binder may comprise carboxymethyl cellulose, dextrin or maltodextrin.

[0141] For example, a solvent capable of dissolving the binder may be used.

[0142] For example, the solvent may include water.

[0143] The binder content and solvent content may be determined based on the total weight of the inorganic mixture. For example, the total weight of the inorganic mixture may be set as 100 parts by weight (hereinafter referred to as "100 parts by weight of the inorganic mixture"), and the binder content and solvent content may be determined based on the 100 parts by weight.

[0144] According to exemplary embodiments, the binder may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the inorganic mixture. In some embodiments, the binder may be included in an amount of 0.3 to 4 parts by weight or 0.5 to 3 parts by weight based on 100 parts by weight of the inorganic mixture.

[0145] According to exemplary embodiments, the solvent may be included in an amount of 5 to 20 parts by weight based on 100 parts by weight of the inorganic mixture. In some embodiments, the binder may be included in an amount of 7 to 15 parts by weight or 8 to 12 parts by weight based on 100 parts by weight of the total inorganic mixture.

[0146] In the above range, ceramic particles for manufacturing a crucible having a core-shell structure can be manufactured by dry coating of spinel.

[0147] Referring to Fig. 2, a crucible can be manufactured by compression molding ceramic particles for manufacturing a crucible (e.g., S30 process).

[0148] In exemplary embodiments, the compression molding of the ceramic particles for crucible manufacturing may include the steps of pressing the ceramic particles for crucible manufacturing, drying the pressed ceramic particles for crucible manufacturing, and sintering the dried ceramic particles for crucible manufacturing.

[0149] For example, ceramic particles for crucible manufacturing can be loaded into a press equipped with a crucible-shaped mold, pressurized to manufacture into a certain shape, and the compressed ceramic particles for crucible manufacturing can be dried and sintered through a heating furnace to manufacture into a crucible shape.

[0150] The heating furnace used for the above drying and sintering may be a known heating furnace, such as a roller herarth kiln, a rotary kiln, a box kiln, a tunnel kiln, an elevator kiln, etc.

[0151] In exemplary embodiments, the ceramic particles for manufacturing the crucible have a density of 300 kgf / cm 2 Up to 2000 kgf / cm 2 can be pressurized. Specifically, the ceramic particles for manufacturing the crucible are 700 kgf / cm 2 Up to 1300 kgf / cm 2 can be pressurized.

[0152] In exemplary embodiments, the ceramic particles for manufacturing the pressurized crucible may be dried at 75° C. to 150° C. Specifically, the ceramic particles for manufacturing the pressurized crucible may be dried at 80° C. to 120° C.

[0153] In exemplary embodiments, the ceramic particles for manufacturing a pressurized crucible can be dried for 1 to 4 hours within the above temperature range. Specifically, the ceramic particles for manufacturing a pressurized crucible can be dried for 1 to 3 hours within the above temperature range.

[0154] In exemplary embodiments, the dried ceramic particles for making a crucible can be sintered at 1100° C. to 1500° C. Specifically, the dried ceramic particles for making a crucible can be sintered at 1200° C. to 1400° C.

[0155] The above sintering can be performed at a heating rate in the range of 1 to 30°C / min.

[0156] In exemplary embodiments, the dried ceramic particles for crucible manufacturing can be sintered at the above temperature range for 1 to 5 hours. Specifically, the dried ceramic particles for crucible manufacturing can be sintered at the above temperature range for 2 to 4 hours.

[0157] Hereinafter, the present invention will be described in detail through examples and experimental examples. The following examples and experimental examples are merely illustrative examples for describing the present invention in detail, and the content of the present invention is not limited to the following examples and experimental examples.

[0158]

[0159] Example

[0160] (1) Manufacturing of ceramic particles for crucible manufacturing

[0161] The core was manufactured using cordierite, mullite, alumina, clay, and ceramic fiber as inorganic materials and carboxymethyl cellulose as a binder.

[0162] Water containing a binder was added to the core portion, and spinel was dry-coated using a Henschel mixer to produce ceramic particles for crucible manufacturing.

[0163] The contents of each inorganic material, binder and water used in the manufacture of the ceramic particles for manufacturing the above crucible are shown in Table 1 below.

[0164] Ingredient content (parts by weight)Example 1Example 2Example 3Example 4Cordierite33.330.227.725.6Spinel29.836.141.546.0Mullite6.66.05.55.1Alumina6.66.05.55.1Clay19.818.216.615.2Ceramic fiber3.93.53.23.0Water + CMC12.012.012.012.0

[0165] (2) Manufacturing of crucible A crucible was manufactured using ceramic particles for manufacturing a crucible manufactured according to the above examples.

[0166] Specifically, the ceramic particles for manufacturing the above crucible are loaded into a press and 1000 kgf / cm 2 A preliminary crucible was manufactured by applying pressure to shape it into a crucible shape and drying it at 120°C for 2 hours. The preliminary crucible was sintered while maintaining it at 1350°C for 3 hours to manufacture a crucible.

[0167]

[0168] Comparative example

[0169] (1) Manufacturing of ceramic particles for crucible manufacturing

[0170] Ceramic particles for manufacturing a crucible were manufactured by the same method as in the above examples, except that only mixing was performed without performing dry coating, including the above inorganic materials, binder and water.

[0171] The contents of each inorganic material, binder and water used in the manufacture of the ceramic particles for manufacturing the above crucible are shown in Table 2 below.

[0172] Content (weight parts)Component Comparison Example 1 Comparison Example 2 Cordierite 25.6 46.0 Spinel 46.0 Mullite 5.1 30.7 Alumina 5.1 5.3 Clay 15.2 15.0 Ceramic fiber 3.0 3.0 Water + CMC 12.0 12.0

[0173] (2) Manufacturing of crucible Using the ceramic particles for manufacturing a crucible manufactured according to the comparative example above, a crucible was manufactured by the same process as the above example.

[0174]

[0175] Experimental example

[0176] (1) Appearance evaluation

[0177] The appearance of the ceramic particles for crucible manufacturing manufactured according to the above examples and comparative examples was analyzed. The analysis results are shown in Figs. 3a and 3b.

[0178] As shown in FIGS. 3a and 3b, the ceramic particles for manufacturing a crucible according to Example 1 had a white coating film formed, but the ceramic particles for manufacturing a crucible according to Comparative Example 1 did not have a coating film formed.

[0179] (2) SEM analysis

[0180] The cross-sectional images of the ceramic particles for manufacturing crucibles according to the above examples and comparative examples and the crucibles manufactured using the ceramic particles for manufacturing crucibles were analyzed using a scanning electron microscope (SEM).

[0181] A cross-section of a crucible manufactured using ceramic particles for manufacturing a crucible according to an embodiment is shown in Fig. 4, and the results of SEM analysis of the red-marked portion of the cross-section divided into 25 cuts are shown in Fig. 5.

[0182] In Fig. 5, the yellow part represents a part containing a large amount of cordierite containing silica, and the blue part represents a part containing a large amount of spinel not containing silica.

[0183] As shown in Fig. 5, the outer surface of the crucible contained a large number of blue parts, and the inside of the crucible contained a large number of yellow parts, confirming that the surface of the crucible contained a large number of silica.

[0184] The analysis results of the ceramic particles for manufacturing a crucible according to an example are shown in Fig. 6a, and the analysis results of the ceramic particles for manufacturing a crucible according to a comparative example are shown in Fig. 6b. In addition, the analysis results of the crucible according to an example are shown in Fig. 7a, and the analysis results of the crucible according to a comparative example are shown in Fig. 7b.

[0185] As shown in FIGS. 6a and 6b, the ceramic particles for manufacturing a crucible according to the example formed a core-shell structure, but the boundary of the core-shell was not confirmed in the ceramic particles for manufacturing a crucible according to the comparative example.

[0186] As shown in FIGS. 7a and 7b, in the case of the crucible according to the example, a boundary was confirmed, confirming the formation of a core-shell structure. In the case of the crucible manufactured using ceramic particles according to the comparative example, a core-shell boundary was not confirmed.

[0187] (3) EDS analysis

[0188] The amount of elements was analyzed through EDS (Energy-dispersive X-ray spectroscopy) analysis from SEM images of ceramic particles for crucible manufacturing manufactured according to the above examples and comparative examples. In addition, the amount of elements was analyzed through EDS analysis from SEM images of crucibles manufactured according to the above examples and comparative examples.

[0189] The analysis results of the ceramic particles for manufacturing a crucible according to an example are shown in FIGS. 8a and 9a, and the analysis results of the ceramic particles for manufacturing a crucible according to a comparative example are shown in FIGS. 8b and 9b. In addition, the analysis results of the crucible according to an example are shown in FIGS. 10a and 11a, and the analysis results of the crucible according to a comparative example are shown in FIGS. 10b and 11b.

[0190] As shown in Figs. 8a and 9a, the ceramic particles for crucible manufacturing according to the examples exhibited a directionality of change in the contents of aluminum (Al), silicon (Si), and magnesium (Mg). Specifically, the contents of aluminum and magnesium increased from the inside to the outside, while the content of silicon decreased. In addition, it was confirmed that the contents of aluminum, magnesium, and silicon changed rapidly around the boundary, forming a core-shell structure.

[0191] As shown in FIGS. 8b and 9b, the ceramic particles for manufacturing a crucible according to the comparative example did not show a directionality of change in the content of aluminum, silicon, and magnesium, and there was no part where the content changed abruptly based on a certain boundary.

[0192] As shown in FIGS. 10a and 11a, in the case of the crucible according to the embodiment, the contents of aluminum, silicon, and magnesium change rapidly with respect to a certain boundary, and it was confirmed that the crucible contained ceramic particles with a core-shell structure.

[0193] As shown in Figures 10b and 11b, in the case of the crucible according to the comparative example, no rapid changes in the contents of aluminum, silicon, and magnesium were observed.

[0194] (4) Evaluation of the characteristics of the crucible

[0195] Porosity evaluation

[0196] The porosity of the crucibles according to the above examples and comparative examples was analyzed. The porosity was measured according to the Archimedes method, and the measurement results are shown in Table 3 below.

[0197] Strength analysis

[0198] The three-point bending strength of the crucibles according to the above examples and comparative examples was measured. The three-point bending strength was measured according to ASTM C 1161, and the measurement results are shown in Table 3 below.

[0199] Separation porosity (%) 3-point bending strength (N / mm 2 ) Example 132.85.6 Example 232.65.8 Example 333.74.0 Example 434.42.6 Comparative Example 128.56.2 Comparative Example 227.25.7

[0200] As shown in Table 3 above, in the examples using ceramic particles for manufacturing crucibles manufactured through dry coating, a certain porosity and strength were maintained. In the cases of Examples 3, 4, and Comparative Example 1, in which the spinel content exceeded 41 wt% of the total weight of the inorganic mixture, the strength of the crucibles was reduced.

[0201] Life Characteristics Assessment

[0202] The life characteristics of the crucibles according to the above examples and comparative examples were evaluated. Specifically, the crucibles were used to sinter cathode materials containing lithium composite oxides, and the thickness expansion rate according to the sintering cycles was compared. The life characteristics evaluation was an accelerated experiment conducted under harsh conditions, and the analysis results are shown in Fig. 12.

[0203] As shown in Fig. 12, in the case of a crucible according to Example 1 or Example 2 manufactured from ceramic particles for manufacturing a crucible having a core-shell structure and having a spinel content of 41 wt% or less of the total weight of the inorganic mixture, the thickness expansion rate of the crucible according to the firing cycle was reduced.

[0204] In the case of a crucible manufactured using ceramic particles for manufacturing a crucible according to a comparative example, the thickness expansion rate of the crucible increased with the number of firing cycles.

[0205] In the case of the crucible according to Example 3 or Example 4 manufactured from an inorganic material having a relatively high spinel content, the thickness expansion rate increased with the number of firing cycles.

Claims

1. A ceramic core containing silicon; and A ceramic particle for a crucible, comprising a first shell portion located on the surface of the ceramic core portion and having a lower silicon content than the ceramic core portion.

2. A ceramic particle for a crucible according to claim 1, wherein the ceramic core portion and the first shell portion further comprise aluminum.

3. A ceramic particle for a crucible, wherein the aluminum content contained in the first shell portion is greater than the aluminum content contained in the ceramic core portion in claim 2.

4. In claim 1, the ceramic core part comprises cordierite, a ceramic particle for a crucible.

5. A ceramic particle for a crucible, wherein the first shell part comprises spinel in claim 1.

6. A ceramic particle for a crucible, wherein, in claim 2, the content of silicon among all metal atoms included in the ceramic core portion is 40% to 60%, and the content of silicon among all metal atoms included in the first shell portion is 5% or less.

7. A ceramic particle for a crucible, wherein, in claim 2, the content of aluminum among all metal atoms included in the ceramic core portion is 20% to 50%, and the content of aluminum among all metal atoms included in the first shell portion is 60% or more.

8. In claim 2, the ceramic core part and the first shell part further contain magnesium, and the content of magnesium among the total metal atoms contained in the ceramic core part is 5% to 20%, and the content of magnesium among the total metal atoms contained in the first shell part is 20% or more, a ceramic particle for a crucible.

9. A step of manufacturing a ceramic core by mixing an inorganic material including cordierite; A step of manufacturing ceramic particles for manufacturing a crucible by mixing the above ceramic core, binder and spinel; and A method for manufacturing a crucible, comprising the step of compression molding the ceramic particles for manufacturing the crucible.

10. A method for manufacturing a crucible according to claim 9, wherein the inorganic material further comprises at least one selected from the group consisting of alumina, mullite, kaolinite, clay, and ceramic fiber.

11. A method for manufacturing a crucible, wherein in the step of manufacturing the ceramic particles for manufacturing the crucible, the spinel is coated on the ceramic core portion.

12. A crucible comprising ceramic particles for a crucible according to claim 1.

13. Ceramic core containing silicon; A second shell portion located on the surface of the ceramic core portion and having a lower silicon content than the ceramic core portion; and Ceramic particles for manufacturing a crucible, comprising a first shell portion located on the surface of the second shell portion and having a lower silicon content than the second shell portion.

14. A ceramic particle for manufacturing a crucible according to claim 13, wherein the ceramic core portion and the second shell portion further include aluminum atoms, and the content of aluminum atoms included in the second shell portion is higher than the content of aluminum atoms included in the ceramic core portion.

15. A ceramic particle for manufacturing a crucible according to claim 13, wherein the first shell portion and the second shell portion further include aluminum atoms, and the content of aluminum atoms included in the first shell portion is higher than the content of aluminum atoms included in the second shell portion.

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