Method for producing ceramic powder

Abstract

Disclosed in the present invention is a method for producing a ceramic powder, the method comprising: a composite precursor solution preparing step of preparing a composite precursor solution by mixing at least two types of metal salts and a solvent; a precursor powder preparing step of preparing a precursor powder by rapidly drying the composite precursor solution; and a ceramic powder preparing step of preparing a ceramic powder by heat-treating the precursor powder.

Description

Method for manufacturing ceramic powder

[0001] The present invention relates to a method for manufacturing ceramic powder, which manufactures ceramic powder using an amorphous precursor powder obtained by rapid drying of a metal salt containing a metal element.

[0002] Multi-element ceramic powders can generally be manufactured by a ball-mill process, a co-precipitation process, a sol-gel process, or a pyrolysis process. The ball-mill process has poor powder composition uniformity, and morphology control may not be easy. In addition, the co-precipitation process may not be easy to control morphology. In addition, the sol-gel process has poor powder composition uniformity, morphology control may not be easy, and productivity (scalability) may not be high. In addition, the pyrolysis process has high powder composition uniformity and morphology control is easy, but productivity may be low. Therefore, a method for manufacturing the multi-element ceramic powder requires a powder that has good powder composition uniformity, easy particle shape control, and high productivity.

[0003] The purpose of the present invention is to provide a method for manufacturing ceramic powder having high composition uniformity, easy particle shape control, and high mass productivity.

[0004] The method for manufacturing a ceramic powder of the present invention is characterized by including a step of manufacturing a composite precursor solution by mixing at least two types of metal salts and a solvent to manufacture a composite precursor solution, a step of manufacturing a precursor powder by rapidly drying the composite precursor solution to manufacture a precursor powder, and a step of manufacturing a ceramic powder by heat-treating the precursor powder.

[0005] Additionally, the solvent may be water or a polar organic solvent.

[0006] Additionally, the metal salt can be mixed in the solvent at a solubility of 1 mol / kg.

[0007] In addition, the precursor powder manufacturing step can be performed by rapidly drying the composite precursor solution by spraying a drying gas or heating it after forming it into a thin film or mist of a predetermined thickness.

[0008] Additionally, the precursor powder manufacturing step can be performed so that the precursor thin film is completely dried within the drying time.

[0009] Additionally, the drying time may be within 10 seconds.

[0010] Additionally, the precursor powder manufacturing step may be performed by spraying a drying gas using an air knife, an air gun, or a hot air dryer.

[0011] Additionally, the drying gas may be air, nitrogen gas or argon gas.

[0012] Additionally, the above dry gas can be heated to a temperature of 20 to 300°C and sprayed.

[0013] Additionally, the ceramic powder manufacturing step may heat treat the precursor powder at a heat treatment temperature of 500 to 2,000°C.

[0014] Additionally, the ceramic powder manufacturing step may heat treat the precursor powder for a heat treatment time of 10 minutes to 5 hours.

[0015] In addition, the ceramic powder manufacturing step can produce a ceramic fine powder having a particle size of 1 mm or less by heat-treating the precursor powder for a heat treatment time of 10 to 30 minutes.

[0016] The method for manufacturing a ceramic powder of the present invention rapidly evaporates and dries a composite precursor solution containing at least two types of metal salts and at least one type of solvent to prevent crystallization and phase separation, thereby making the precursor powder amorphous, thereby ensuring uniformity of the composition of the ceramic powder at the atomic level.

[0017] In addition, the method for manufacturing ceramic powder of the present invention prevents an increase in the particle size of the precursor powder by rapidly evaporating the composite precursor solution, and synthesizes the precursor powder into a powder having a particle size of several tens of nm or more by heat-treating it for a short period of time, so that the particle size of the ceramic powder is small and the particle shape can be easily controlled.

[0018] In addition, the method for manufacturing ceramic powder of the present invention can increase productivity by manufacturing ceramic powder through rapid evaporation and low-temperature, short-time heat treatment of a composite precursor solution.

[0019] Figure 1 is a process diagram of a method for manufacturing ceramic powder according to one embodiment of the present invention.

[0020] FIG. 2 is a TEM photograph of a precursor powder according to one embodiment of the precursor powder manufacturing step of FIG. 1.

[0021] Figure 3 is a TEM electron diffraction pattern of the precursor powder of Figure 2.

[0022] Figure 4 is an XRD graph of the precursor powder of Figure 2.

[0023] Figure 5 is a Dot Map (Energy Dispersive Spectroscopy EDS) photograph of the element distribution of the precursor powder of Figure 2.

[0024] Figure 6 is an XPS graph showing the elements present in the precursor powder of Figure 2.

[0025] Fig. 7 is an XRD graph of a ceramic powder according to the ceramic powder manufacturing step of Fig. 1.

[0026] Fig. 8 is a graph showing the crystal structure of ceramic powder according to the heat treatment temperature in the ceramic powder manufacturing method of Fig. 1.

[0027] Figure 9 is a TEM photograph of the spinel LiCoO2 of Figure 8.

[0028] Fig. 10 is an SEM photograph of the layered LiCoO2 of Fig. 8.

[0029] Fig. 11 is an XRD graph of a precursor powder of another example by the precursor powder manufacturing step of Fig. 1.

[0030] Hereinafter, a method for manufacturing ceramic powder according to one embodiment of the present invention will be described in detail.

[0031]

[0032] First, a method for manufacturing ceramic powder according to one embodiment of the present invention will be described.

[0033] Figure 1 is a process diagram of a method for manufacturing ceramic powder according to one embodiment of the present invention.

[0034] A method for manufacturing a ceramic powder according to one embodiment of the present invention may include a step of manufacturing a composite precursor solution (S10), a step of manufacturing a precursor powder (S20), and a step of manufacturing a ceramic powder (S30), as shown in FIG. 1.

[0035] The above ceramic powder manufacturing method can be applied to manufacturing ceramic powder using various metal salts. The above ceramic powder manufacturing method can be applied to manufacturing ceramic powder using a composite precursor solution in which at least two kinds of metal salts and a solvent are mixed. Therefore, the ceramic powder manufacturing method according to an embodiment of the present invention can be suitable for manufacturing a binary ceramic powder including at least two kinds of metal elements, a ceramic powder including a ternary or more elements. In addition, the ceramic powder manufacturing method can be suitable for manufacturing a ceramic powder such as an oxide. For example, the ceramic powder manufacturing method can be applied to manufacturing a binary ceramic powder such as LiCoO2, SrVO3 or CaVO3. In addition, the ceramic powder manufacturing method can be applied to manufacturing a LiNi x Mn y Co1 -x-y O2 (NMC cathode material), LiNi0 . 5Mn1 . 5O4, Li7La3Zr2O 12 , Mgx V1 . 5Ti0 . 75 It can be applied to manufacture ternary oxide powders such as O4.

[0036] In addition, the method for manufacturing ceramic powder can be applied to manufacturing ceramic powder such as fluoride, chloride, sulfide or nitride. The method for manufacturing ceramic powder can manufacture ceramic powder such as sulfide or nitride containing multiple elements. The method for manufacturing ceramic powder can manufacture through crystallization through anion exchange of the precursor produced by rapidly drying a complex precursor solution and subsequent heat treatment. For example, the method for manufacturing ceramic powder can manufacture ceramic powder such as fluoride such as LiFeF3 or LiFeOF, chloride such as Li6PS5Cl, sulfide or nitride such as Li3PS4, Li3SbS4 or Li4SnS4. The method for manufacturing ceramic powder can be utilized when manufacturing ceramic powder such as nitride containing two or more metal elements that could not be realized due to the high temperature synthesis process of 1500 °C or higher.

[0037] The above method for manufacturing ceramic powder manufactures ceramic powder by rapidly drying a complex precursor solution in which a metal salt is dispersed in an ionic state in a solvent, so that the composition uniformity of the ceramic powder can be secured to an atomic level.

[0038] The above ceramic powder manufacturing method can easily control the crystal phase of the ceramic powder by controlling its particle size, morphology, composition uniformity, and heat treatment temperature. In particular, it can mass-produce nanoparticle ceramic powder through short heat treatment times. Furthermore, the ceramic powder can be utilized for the production of high-density sintered bodies, as it allows for rapid particle size growth and minimizes porosity.

[0039]

[0040] The above composite precursor solution preparation step (S10) is a step of preparing a composite precursor solution by mixing at least two types of metal salts and a solvent. The metal salt may be a variety of metal salts containing a metal element of the ceramic powder to be prepared. For example, the metal element may be an element such as lithium (Li), copper (Cu), chromium (Cr), aluminum (Al), zinc (Zn), cobalt (Co), nickel (Ni), manganese (Mn), zirconium (Zr), titanium (Ti), lanthanum (La), strontium (Sr), or vanadium (V). In addition, the metal salt may include a nitrate, carbonate, chloride, acetate, citrate, or phosphate containing the metal element, and may be a compound such as a hydrate thereof.

[0041] The solvent may be water or an organic solvent. The organic solvent may be a polar organic D-substituted solvent. The organic solvent may be any one solvent selected from acetone, dimethyl sulfoxide (DMSO), acetone, dimethyl carbonate (DMC), methanol, tetrahydrofuran (THF), and anhydrous ethanol (EtOH), or a mixture thereof. The solvent may preferably be water, alcohol, or acetone, which are relatively easy to rapidly dry.

[0042] The above composite precursor solution can be prepared by appropriately mixing a metal salt and a solvent. The composite precursor solution can be mixed with the metal salt in a ratio identical to the composition ratio of the metal elements of the ceramic powder to be prepared. In addition, the composite precursor solution can be mixed with the metal salt in the solvent in a ratio of 1 mol / kg to solubility. Here, the solubility can be a ratio at which the metal salt is maximally dissolved in the solvent. The composite precursor solution can efficiently achieve amorphization due to rapid drying of the solvent when the concentration of the metal salt increases. The composite precursor solution can secure uniformity at the atomic level due to the amorphization.

[0043] The above composite precursor solution may further include a component, such as a dispersant, that improves the dispersibility of the metal salt. The composite precursor solution preparation step (S10) may enable the metal salts to be uniformly mixed through a separate dispersion process.

[0044] In addition, the composite precursor solution may further include a polar polymer. The polar polymer suppresses crystallization of the precursor powder during the drying process of the composite precursor solution, thereby allowing the precursor powder to maintain an amorphous state. The polar polymer may be a polar polymer resin such as polyethylene oxide (PEO), polymethylmethacrylate (PMMA), polycaprolactone (PCL), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyimide (PI), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), or polystyrene sulfonate.

[0045]

[0046] The precursor powder manufacturing step (S20) is a step of rapidly drying a composite precursor solution to manufacture a precursor powder. The precursor powder manufacturing step (S20) can rapidly dry the composite precursor solution by various methods. The precursor powder manufacturing step (S20) can preferably first form the composite precursor solution into a precursor thin film with a predetermined thickness and then rapidly dry it by spraying a drying gas. That is, the precursor powder manufacturing step (S20) can spray a drying gas onto the upper surface of the precursor thin film to evaporate the solvent of the composite precursor solution. The drying gas can be air or an inert gas such as nitrogen gas or argon gas. In addition, the precursor powder manufacturing step (S20) can spray the composite precursor solution into the air in the form of a mist and spray a drying gas at a temperature in the range of 20°C to 300°C to evaporate the solvent of the composite precursor solution.

[0047] The precursor powder manufacturing step (S20) can completely dry the precursor thin film within a drying time. Here, the complete drying may mean that the solvent content in the precursor thin film is dried to 99% or more. The drying time may be within 10 seconds. In addition, the drying time may be 0.1 to 10 seconds. In addition, the drying time may be preferably 0.1 to 1 second. In addition, the drying time may be more preferably within 1 second. Therefore, the precursor powder manufacturing step (S20) may be performed under a condition where the solvent in the precursor thin film evaporates within the drying time.

[0048] The above composite precursor solution can be coated on a flat substrate as a precursor thin film having a predetermined thickness that can satisfy a drying time. The above composite precursor solution can be coated on the flat substrate using a spray method, a roll coating method using a gravure coater, a slot die coater, a blade coater or a reverse coater, or an inkjet method. The flat substrate can be a rigid substrate such as a glass substrate. In addition, the flat substrate can be a flexible substrate such as a resin film. The flat substrate can be heated to a predetermined substrate temperature. The substrate temperature can be 20 to 300°C. In addition, the above composite precursor solution can be used by being heated to a predetermined solution temperature. The solution temperature can be 20 to 300°C. Therefore, the precursor thin film can be dried more quickly.

[0049]

[0050] The precursor powder manufacturing step (S20) may be performed by spraying a drying gas onto the upper surface of a precursor thin film using an air knife, an air gun, or a hot air dryer. Here, the precursor thin film may be a thin film formed by a composite precursor solution. The drying gas may be sprayed so that the precursor thin film is dried within a complete drying time. The drying gas may be sprayed at a wind speed of 0.5 to 30 m / s. In addition, the drying gas may be sprayed while being heated to a temperature of 20 to 300°C. Preferably, the drying gas may be sprayed while being heated to a temperature of 50 to 150°C. The air knife may receive the drying gas in a compressed state and spray it through a spray nozzle of a predetermined length. The air knife may spray the drying gas over an area of ​​a predetermined width and length. The air knife may spray the drying gas over an area of ​​a length greater than the width of the precursor thin film. The precursor powder manufacturing step (S20) may be performed such that the continuously formed precursor thin film is moved downwards by the air knife while the air knife sprays a dry gas onto the upper surface of the precursor thin film. Accordingly, the precursor powder manufacturing step (S20) may be performed as a continuous process to manufacture the precursor powder.

[0051] The precursor powder manufacturing step (S20) may be performed by spraying a dry gas as a precursor mist using an air knife, an air gun, or a hot air dryer. Here, the precursor mist may be formed by spraying a composite precursor solution. The dry gas may be sprayed so that the precursor mist is dried within a complete drying time to produce a precursor powder. The dry gas may be sprayed at a wind speed of 0.1 to 30 m / s. In addition, the dry gas may be sprayed after being heated to a temperature of 20 to 300°C. Preferably, the dry gas may be sprayed after being heated to a temperature of 50 to 200°C. The air knife, air gun, or hot air dryer may receive the dry gas in a compressed state and spray it through a spray nozzle of a predetermined length. The air knife may spray the dry gas over an area of ​​a predetermined width and length. The air knife may spray the dry gas over an area larger than the cross-sectional area of ​​the volume of the space occupied by the precursor mist. The precursor powder manufacturing step (S20) may be performed such that the continuously formed precursor mist is rapidly dried by spraying the drying gas to form the precursor powder. Therefore, the precursor powder manufacturing step (S20) may be performed as a continuous process to manufacture the precursor powder.

[0052] The precursor powder manufacturing step (S20) can form a precursor powder by rapidly drying a composite precursor solution. Since the precursor powder manufacturing step (S20) rapidly dries the composite precursor solution, the liquid-like properties that enable translational motion of atoms can be rapidly eliminated. The precursor powder can be formed into an amorphous ceramic precursor in a solid state in a manner similar to a glass phase transition as the liquid-like composite precursor solution is rapidly dried. Since the precursor powder manufacturing step (S20) rapidly dries and does not provide time required for nucleation and crystallization, an amorphous precursor powder with uniformity at the atomic level can be manufactured. The precursor powder can have uniformity at the atomic level while becoming amorphous.

[0053]

[0054] The above ceramic powder manufacturing step (S30) is a step of manufacturing ceramic powder by heat-treating precursor powder. The precursor powder can be formed in powder form by separating the precursor thin film from the substrate. In this case, the ceramic powder manufacturing step (S30) can heat-treat the precursor powder in a powder state. In addition, the ceramic powder manufacturing step (S30) can perform heat treatment while the precursor thin film is coated on the upper surface of the flat substrate.

[0055] The ceramic powder manufacturing step (S30) may heat-treat the precursor powder under conditions of a predetermined heat treatment temperature and heat treatment time. The ceramic powder manufacturing step (S30) may be performed in a sealed process chamber. The heat treatment temperature and heat treatment time may vary depending on the type of precursor powder. The heat treatment temperature may be 500 to 2,000°C. The heat treatment temperature may be determined depending on the crystal phase of the ceramic powder to be manufactured. If the heat treatment temperature is too low, the heat treatment of the precursor powder may not be sufficient, and thus the crystal structure of the target ceramic powder may not be obtained. If the heat treatment temperature is too high, the particle size of the ceramic powder may increase, which may cause problems in composition management. If the ceramic powder has an allotrope, the allotrope produced may be determined depending on the heat treatment temperature. For example, if the ceramic powder is LiCoO2, spinel LiCoO2 can be formed when the heat treatment temperature is 600°C or lower, and layered LiCoO2 can be formed when the heat treatment temperature is 700°C. In the above ceramic powder manufacturing step (S30), if the heat treatment time is kept short, the particle size growth of the ceramic powder can be suppressed, so that a ceramic fine powder having a pure crystal structure and a particle size of 1 mm or less can be synthesized.

[0056] The above ceramic powder manufacturing step (S30) may be performed in air or an oxidizing atmosphere. Therefore, the ceramic powder manufacturing step (S30) may be performed while supplying a gas such as air or oxygen to the process chamber. The heat treatment time may be 10 minutes to 5 hours. The heat treatment time is more preferably 10 minutes to 30 minutes. The heat treatment time may be the time required to achieve purity of the crystal structure and composition resulting from the heat treatment. The ceramic powder may be formed as a crystalline powder. The ceramic powder may be formed as a powder having uniformity at the atomic level. Therefore, the ceramic powder manufacturing step (S30) may generate a ceramic fine powder having a particle size of 1 mm or less by heat-treating the precursor powder for a heat treatment time of 10 minutes to 30 minutes.

[0057]

[0058] The following describes a method for manufacturing ceramic powder of the present invention through specific examples.

[0059] FIG. 2 is a TEM photograph of a precursor powder according to an embodiment of the precursor powder manufacturing step of FIG. 1. FIG. 3 is a TEM electron diffraction pattern of the precursor powder according to FIG. 1. FIG. 4 is an XRD graph of the precursor powder according to FIG. 2. FIG. 5 is an element distribution Dot Map (Energy Dispersive Spectroscopy EDS) photograph of the precursor powder according to FIG. 2. FIG. 6 is an XPS graph showing elements present in the precursor powder according to FIG. 2. FIG. 7 is an XRD graph of a ceramic powder according to the ceramic powder manufacturing step of FIG. 1. FIG. 8 is a graph showing the crystal structure of a ceramic powder according to a heat treatment temperature in the method for manufacturing a ceramic powder according to FIG. 1. FIG. 9 is a TEM photograph of spinel LiCoO2 according to FIG. 8. FIG. 10 is an SEM photograph of layered LiCoO2 according to FIG. 8. FIG. 11 is an XRD graph of a precursor powder according to another embodiment of the precursor powder manufacturing step of FIG. 1.

[0060] First, an example of a binary ceramic powder is described.

[0061] In the example of the above ceramic powder manufacturing method, LiNO3 and Co(NO3)2 were used as the metal salts, and water was used as the solvent. The composite precursor solution was manufactured by mixing LiNO3 and Co(NO3)2 with the solvent at 12.0 mol / kg each. That is, LiNO3 and Co(NO3)2 were mixed at the same 12.0 mol / kg each.

[0062] A composite precursor solution was coated on the surface of a silicon wafer to a thickness of 30 μm to form a precursor thin film. The surface of the precursor thin film was rapidly dried by spraying air at 20°C to form a precursor powder. The drying time was set to approximately 1 second. The precursor powder was heat-treated at 430°C for 2 hours to produce a ceramic powder. In addition, the composite precursor solution was rapidly dried by spraying it in air heated to 200°C to form a precursor powder.

[0063] The precursor powders manufactured by the above two methods were heat-treated at 540°C for 10 minutes to manufacture spinel LiCoO2, and layered LiCoO2 was heat-treated at 700°C for 10 minutes to manufacture a phase-pure ceramic powder. In addition, regardless of which method is adopted, precursor thin film formation or spray drying, the result of forming a pure ceramic powder is the same.

[0064] As shown in FIGS. 2, 3, and 4, it can be confirmed that the precursor powder manufactured from the composite precursor solution is amorphous. Furthermore, as shown in FIG. 5, it can be confirmed that Co, N, and O are uniformly distributed at the atomic level in the precursor powder. Furthermore, as shown in FIG. 6, it can be confirmed that all of the introduced metal elements are detected in the precursor powder without loss.

[0065] As shown in Fig. 7, it can be confirmed that the ceramic powder is formed into a powder having crystallinity by heat treatment of the precursor powder. In addition, as shown in Fig. 8, it can be confirmed that spinel LiCoO2 and layered LiCoO2 are formed depending on the heat treatment temperature of the precursor powder. As shown in Fig. 8, the ceramic manufacturing method of the present invention can be confirmed to have the advantage of short-time heat treatment (calcination) compared to other existing synthesis methods. In addition, as shown in Figs. 9 and 10, it can be confirmed that the ceramic powder is manufactured into a fine powder having a particle size of 100 nm to 1 mm.

[0066]

[0067] Next, an example of a ternary ceramic powder is described.

[0068] In another embodiment of the above ceramic powder manufacturing method, the metal salts used were LiNO3, Zr(NO3)4, and La(NO3)3, and the solvent used was water. The composite precursor solution was manufactured by mixing LiNO3, Zr(NO3)4, and La(NO3)3 with the solvent in a molar ratio of 7:3:2, so that the total amount was 12.0 mol / kg.

[0069] The precursor powder was formed by rapidly drying the composite precursor solution by spraying it into air heated to 200°C. At this time, the drying time was set to approximately 1 second.

[0070] As shown in Fig. 11, it can be confirmed that the precursor powder formed from the composite precursor solution is amorphous, indicating that an amorphous precursor can be manufactured from three or more metal elements using a rapid drying process.

[0071]

[0072] The above description is only one embodiment for carrying out a method for manufacturing ceramic powder according to one embodiment of the present invention, and the present invention is not limited to the above-described embodiment, and it will be understood that the technical spirit of the present invention exists to the extent that anyone having ordinary skill in the art to which the present invention pertains can make various modifications without departing from the gist of the present invention as claimed in the claims below.

Claims

1. A step of preparing a composite precursor solution by mixing at least two types of metal salts and a solvent, A precursor powder manufacturing step for manufacturing a precursor powder by rapidly drying a composite precursor solution, and A method for manufacturing ceramic powder, characterized in that it comprises a ceramic powder manufacturing step of manufacturing ceramic powder by heat-treating the precursor powder.

2. In paragraph 1, A method for manufacturing ceramic powder, characterized in that the solvent is water or a polar organic solvent.

3. In paragraph 1, A method for manufacturing ceramic powder, characterized in that the metal salt is mixed in the solvent at a solubility of 1 mol / kg.

4. In paragraph 1, A method for manufacturing ceramic powder, characterized in that the precursor powder manufacturing step comprises forming the composite precursor solution into a thin film or mist of a predetermined thickness and then rapidly drying it by spraying a drying gas or heating.

5. In paragraph 1, A method for manufacturing ceramic powder, characterized in that the precursor powder manufacturing step is performed so as to completely dry the precursor thin film within the drying time.

6. In paragraph 5, A method for manufacturing ceramic powder, characterized in that the drying time is within 10 seconds.

7. In paragraph 5, A method for manufacturing ceramic powder, characterized in that the precursor powder manufacturing step is performed by spraying a drying gas using an air knife, an air gun, or a hot air dryer.

8. In paragraph 5, A method for manufacturing ceramic powder, characterized in that the above drying gas is air, nitrogen gas or argon gas.

9. In paragraph 5, A method for manufacturing ceramic powder, characterized in that the above dry gas is heated to a temperature of 20 to 300°C and sprayed.

10. In paragraph 1, A method for manufacturing ceramic powder, characterized in that the above ceramic powder manufacturing step heat-treats the precursor powder at a heat treatment temperature of 500 to 2,000°C.

11. In paragraph 1, A method for manufacturing ceramic powder, characterized in that the above ceramic powder manufacturing step heat-treats the precursor powder for a heat treatment time of 10 minutes to 5 hours.

12. In paragraph 1, A method for manufacturing ceramic powder, characterized in that the above ceramic powder manufacturing step heat-treats the precursor powder for a heat treatment time of 10 to 30 minutes to produce a ceramic fine powder having a particle size of 1 mm or less.

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