CN110818408A - Preparation method of ceramic and ceramic - Google Patents
Preparation method of ceramic and ceramic Download PDFInfo
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- CN110818408A CN110818408A CN201810901375.3A CN201810901375A CN110818408A CN 110818408 A CN110818408 A CN 110818408A CN 201810901375 A CN201810901375 A CN 201810901375A CN 110818408 A CN110818408 A CN 110818408A
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Abstract
The invention relates to the technical field of ceramic preparation, in particular to a preparation method of ceramic and the ceramic. The sintering aid can be uniformly dispersed on the surface of the ceramic blank, so that the sintering shrinkage and the densification degree of the ceramic can be effectively improved. A method of making a ceramic, comprising: dispersing or dissolving a sintering aid or a sintering aid precursor in a solvent to form a dispersion liquid or a solution; dipping the formed ceramic body by using dispersion liquid or solution to ensure that metal ions or metal oxides in the dispersion liquid or solution are uniformly distributed on the surface of the ceramic body; and drying and sintering the ceramic blank after the dipping treatment to obtain the ceramic. The embodiment of the invention is used for preparing the ceramic.
Description
Technical Field
The invention relates to the technical field of ceramic preparation, in particular to a preparation method of ceramic and the ceramic.
Background
The preparation of ceramic articles generally comprises: the method comprises a series of working procedures of ceramic powder preparation, blank forming, drying, sintering, post-treatment and the like. In the preparation process of the functional ceramic, the sintering of the ceramic has great influence on the strength, consistency, durability, porosity and the like of the ceramic product. Therefore, the improvement of the sintering shrinkage rate and the densification degree in the ceramic sintering process is an important link for improving the quality of functional ceramic products.
In general, the sintering shrinkage of ceramics is related to the type of material, the powder particle size of the material, the distribution of the particle sizes of the material, and the like. In the actual experimental production process, once the material type and the powder particles of the material are determined, the powder is difficult to be continuously improved and optimized through the traditional process. If the sintering shrinkage and porosity of the sintered ceramic are found to be not up to the standard after the experiment, a new batch of material powder needs to be purchased again, so that the research and development cost and the production cost are greatly increased, and the research and development period is delayed.
The addition of sintering aids to the material powder is an effective way to increase the densification of the ceramic, and it is common practice to add to the original powder oxides that aid sintering, such as lithium oxide, potassium oxide, sodium oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, and the like. However, the particle size of the sintering aid is generally in the order of micrometers, and there is a great difficulty in uniformly dispersing the sintering aid on the surface of the ceramic powder.
Disclosure of Invention
The main objective of the present invention is to provide a method for preparing a ceramic and a ceramic, which can uniformly disperse a sintering aid on the surface of a ceramic blank, thereby effectively increasing the sintering shrinkage and densification degree of the ceramic.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, an embodiment of the present invention provides a method for preparing a ceramic, including:
dispersing or dissolving a sintering aid or a sintering aid precursor in a solvent to form a dispersion liquid or a solution;
dipping the formed and sintered ceramic blank by the dispersion liquid or the solution to ensure that metal ions or metal oxides in the dispersion liquid or the solution are uniformly distributed on the surface of the ceramic blank; and drying and sintering the ceramic blank after the dipping treatment to obtain the ceramic.
Optionally, the number of times of the dipping treatment and the drying of the ceramic body after the dipping treatment is 1 to 10.
Optionally, the time for one immersion treatment is 1-20 min.
Optionally, the solvent is a reducing solvent; or, a reducing agent for reducing the metal ions or the metal oxides into metal nanoparticles and dispersing the metal nanoparticles in the solution or the dispersion liquid is further added to the solvent.
Optionally, before sintering the ceramic green body, the preparation method further includes:
and (3) dipping the dried ceramic blank body by using a reducing solvent or an aqueous solution of a reducing agent to reduce metal ions or metal oxides distributed on the surface of the ceramic blank body into metal nano particles for drying again.
Optionally, the reducing agent is sodium citrate, an amine compound, an aldehyde compound, an alcohol compound, an amide compound, potassium tartrate or ascorbic acid.
Optionally, the molar concentration of the reducing agent in the solvent or the aqueous solution is 0.1 to 0.2 times of the molar concentration of the metal ions in the sintering aid or the sintering aid precursor.
Optionally, the reducing solvent is ethylene glycol or DMF.
Optionally, the temperature is raised to 1300 ℃ at a heating rate of 0.5-10 ℃/min, and the temperature is maintained at 1300 ℃ of 600-.
Optionally, the molar concentration of the metal ions in the sintering aid or the sintering aid precursor in the solution or the dispersion liquid is 1-5 mol/L.
Optionally, the particle size of the metal oxide is less than or equal to 500 nm.
In another aspect, embodiments of the present invention provide a ceramic prepared by the method for preparing a ceramic described above.
Optionally, the sintering shrinkage of the ceramic is 10-20%.
Optionally, the density of the ceramic is 80% or more of the theoretical density.
The embodiment of the invention provides a preparation method of ceramic and ceramic, wherein ceramic powder and a sintering aid or a sintering aid precursor are uniformly dispersed or dissolved in a solvent to form a dispersion liquid, in one case, when the sintering aid such as a metal oxide is dispersed in the solvent, the sintering aid can be uniformly dispersed on the surface of the ceramic powder under the mass transfer action of the solvent, so that the sintering shrinkage and the densification degree of the ceramic can be effectively improved in the ceramic sintering process. In another case, when the sintering aid precursor, such as metal nitrate, is dissolved in the solvent, the metal ions in the metal nitrate can be uniformly coated on the surface of the ceramic powder particles under the mass transfer effect of the solvent, so that the sintering shrinkage and the densification degree of the ceramic can be effectively improved in the ceramic sintering process.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a method for preparing a ceramic according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In one aspect, embodiments of the present invention provide a method for preparing a ceramic, referring to fig. 1, including:
step 1) dispersing or dissolving a sintering aid or a sintering aid precursor in a solvent to form a dispersion liquid or a solution;
step 2) dipping the formed and sintered ceramic blank by using the dispersion liquid or the solution to ensure that metal ions or metal oxides in the dispersion liquid or the solution are uniformly distributed on the surface of the ceramic blank; and drying and sintering the ceramic blank after the dipping treatment to obtain the ceramic.
Wherein, the ceramic green body can be obtained by molding oxide powder (such as alumina, zirconia, barium titanate, magnesium aluminate, etc.), nitride powder (such as silicon nitride, etc.), carbide powder (such as silicon carbide, etc.), etc.; the sintering aid is usually an oxide, for example, lithium oxide, potassium oxide, sodium oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, or the like. The sintering aid is usually an oxide, for example, lithium oxide, potassium oxide, sodium oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, or the like. In actual practice, the metal nitrate is generally mixed with the ceramic powder in the form of a metal nitrate, and the metal nitrate is decomposed to a metal oxide by heating during sintering, and therefore, these metal nitrates are generally referred to as sintering aid precursors.
The embodiment of the invention provides a preparation method of ceramic, which is characterized in that a sintering aid or a sintering aid precursor is uniformly dispersed or dissolved in a solvent to form a dispersion liquid or a solution, and a ceramic blank body is immersed in the dispersion liquid or the solution. In another case, when the sintering aid precursor, such as metal nitrate, is dissolved in the solvent, the metal ions in the metal nitrate can form a liquid film to be uniformly dispersed on the surface of the ceramic blank under the mass transfer effect of the solvent, so that the sintering shrinkage and the densification degree of the ceramic can be effectively improved in the ceramic sintering process.
The solvent may be an organic solvent or water. Preferably, the solvent is ethanol or water.
After the dipping treatment is finished, the ceramic blank body after the dipping treatment is dried, the solvent is volatilized and removed, and metal ions are uniformly attached to the particle surfaces of the ceramic blank body after metal oxides in the solvent.
In order to fill the metal oxide or metal ion between the particles of the ceramic green body as much as possible, in a preferred embodiment of the present invention, the number of times of the dipping treatment and the drying of the ceramic green body after the dipping treatment is 1 to 10 times.
Wherein, the time of one dipping treatment can be 1-20 min.
In another embodiment of the present invention, the temperature is raised to 600-1300 ℃ at a heating rate of 0.5-10 ℃/min, and the temperature is maintained at 600-1300 ℃ for 1-10h to sinter the ceramic green body. For example, the temperature can be raised to 600 ℃ at the heating rate of 0.5 ℃/min, and the temperature is kept at 600 ℃ for 10 h; or heating to 1300 ℃ at the heating rate of 5 ℃/min, and keeping the temperature at 1300 ℃ for 1 h; the temperature can also be raised to 1000 ℃ at the heating rate of 10 ℃/min, and the temperature is kept at 1000 ℃ for 8 h.
In one possible implementation of the invention, the solvent is a reducing solvent. The reducing solvent is a solvent with reducibility, such as alcohols, aldehydes, and the like, so that metal ions in the ceramic powder can generate weak reduction reaction with the reducing solvent to generate metal nanoparticles, which is beneficial to further dispersion of the metal particles, and in the subsequent sintering process, along with the rise of temperature, the melting point of the metal nanoparticles is lower, which is beneficial to forming multi-eutectic mixture between the sintering aid and the ceramic powder, and the liquid phase is generated at lower temperature (such as 800 ℃) to promote particle rearrangement and mass transfer processes, so as to promote the combination of the ceramic powder, thereby being beneficial to the increase of the densification degree of the ceramic in the sintering process, along with the continuous rise of temperature, the metal oxide in the liquid phase continuously volatilizes, a combination area between the ceramic powder is reserved, and the combination area promotes the growth of the ceramic grains at certain temperature (such as 1200 ℃), thereby effectively improving the sintering shrinkage of the ceramic.
In another possible implementation manner of the present invention, a reducing agent for reducing metal ions or metal oxides into metal nanoparticles and dispersing the metal nanoparticles in the solvent is further added to the solvent. The reducing agent itself has reducing properties, and can be oxidized to a high-valence substance by losing electrons or deviating electrons in the oxidation-reduction process. Therefore, the metal ions or the metal oxides are reduced into the metal nano particles, so that the metal particles are favorably dispersed, and in the subsequent sintering process, along with the rise of the temperature, the melting point of the metal nano particles is lower, the sintering aid and the ceramic powder form a multi-eutectic, a liquid phase is generated at a lower temperature (such as 800 ℃) to promote particle rearrangement and mass transfer processes, so that the combination of the ceramic powder is promoted, the increase of the densification degree of the ceramic in the sintering process is facilitated, along with the continuous rise of the temperature, the metal oxides in the liquid phase are continuously volatilized, a combination area between the ceramic powders is reserved, and the combination area promotes the growth of ceramic grains at a certain temperature (such as 1200 ℃) so as to effectively promote the sintering shrinkage rate of the ceramic.
In another possible implementation manner of the present invention, before sintering the ceramic green body, the preparation method further includes: and (3) dipping the dried ceramic blank body by using a reducing solvent or an aqueous solution of a reducing agent to reduce metal ions or metal oxides distributed on the surface of the ceramic blank body into metal nano particles for drying again. The reducing agent itself has reducing properties, and can be oxidized to a high-valence substance by losing electrons or deviating electrons in the oxidation-reduction process. The reducing solvent is a solvent having reducing property, so that metal ions are reduced into metal nanoparticles, further dispersion of the metal particles is facilitated, along with temperature rise in a subsequent sintering process, the melting point of the metal nanoparticles is low, a multi-eutectic mixture is formed between a sintering aid and ceramic powder, a liquid phase is generated at a low temperature (such as 800 ℃) to promote particle rearrangement and mass transfer processes, and combination of the ceramic powder is promoted, so that the densification degree of ceramic in the sintering process is promoted, along with continuous temperature rise, a metal oxide in the liquid phase is continuously volatilized, a combination area between the ceramic powder is reserved, and the combination area promotes growth of ceramic grains at a certain temperature (such as 1200 ℃) so as to effectively promote sintering shrinkage of the ceramic.
The kind of the reducing agent is not limited as long as the reducing agent can reduce metal ions into metal nanoparticles. The reducing agent may be, for example, a weakly reducing substance such as sodium citrate, an amine compound, an aldehyde compound, an alcohol compound, an amide compound, potassium tartrate, or ascorbic acid.
Wherein, sodium citrate is the most common organic reducing agent, sodium citrate can also be used as a stabilizing agent, and the whole reaction raw material is easy to obtain and easy to operate. Amine compounds such as amino acid, polymer, etc. can be used as reducing agent and stabilizer, and aldehyde compounds such as glucose are polyhydroxy aldehyde which can undergo redox reaction with metal salt. Alcohol compounds such as ethanol, ethylene glycol and hydroxyl-containing alcohol compounds or phenolic compounds can also be used as reducing agents, which themselves are reduced to aldehydes or ketones, alcohol compounds generally being used as both solvents and reducing agents. Amide compounds such as N, N-Dimethylformamide (DMF) can be used as a reducing agent to reduce metal ions. Potassium tartrate is also a relatively common reducing agent. The ascorbic acid is enol-type hexonic acid lactone, and the excessive ascorbic acid can also prevent the oxidation of the metal nanoparticles. These organic substances are all capable of reducing metal ions to metal nanoparticles and dispersing the metal nanoparticles in water.
In the case where the reducing agent is defined, in order to prevent agglomeration due to too fast reaction rate when the metal ions are reduced to metal nanoparticles, which is disadvantageous for uniform dispersion of the metal particles on the surface of the ceramic powder, it is preferable that the molar concentration of the reducing agent in the solvent or aqueous solution is 0.1 to 0.2 times the molar concentration of the metal ions in the sintering aid or sintering aid precursor.
In a preferred embodiment of the present invention, the reducing solvent is ethylene glycol or DMF. The metal ions can be reduced into metal nano particles by using the ethylene glycol as a solvent and a reducing agent, and the metal nano particles can be prevented from agglomerating.
The concentrations of the sintering aid and the metal ions in the sintering aid precursor are not limited, and the sintering aid precursor can play a role in sintering assistance and can improve the sintering shrinkage and densification degree of the ceramic.
In one embodiment of the present invention, the molar concentration of the metal ions in the sintering aid or the sintering aid precursor in the solution or dispersion is 1-5 mol/L. Because the porosity of the ceramic body is limited, the concentration of the metal ions is too low to meet the attachment and dispersion among the particles of the ceramic body, and in the above concentration range, the metal ions can be covered and dispersed on the surface of the ceramic body as much as possible.
Illustratively, the molar concentration of the metal ion in the sintering aid or sintering aid precursor in the solution or dispersion may be 1mol/L, 2mol/L, 3mol/L, 4mol/L, or 5 mol/L.
Further, in order to ensure that the metal oxide can diffuse into between the particles of the ceramic green body, it is preferable that the particle diameter of the metal oxide is 500nm or less.
In another aspect, embodiments of the present invention provide a ceramic prepared by the method for preparing a ceramic described above.
Optionally, the sintering shrinkage of the ceramic is 10-20%.
Optionally, the density of the ceramic is 80% or more of the theoretical density.
Hereinafter, the technical effects of the present invention will be described in detail by the following schemes.
Scheme 1
The ground 3g of zirconia powder was dry-pressed in a powder tabletting machine with a circular powder tank having an inner diameter of 25mm, the tabletting pressure was set at 10MPa and the tabletting time was 5 minutes.
Taking a formed zirconium oxide wafer with the diameter of 25mm, heating the formed zirconium oxide wafer to 1200 ℃ at the heating rate of 2 ℃ per minute, and keeping the temperature at 1200 ℃ for 4 hours for drying and sintering.
Measurement of ZrO after sintering of the samples2The average diameter of the disk of (1) was about 23.8mm, and the mass and volume of the disk were measured to obtain a sample having a density of ZrO267% of the theoretical density.
24.2g of copper nitrate trihydrate is placed in a beaker, 50ml of deionized water is added and the mixture is stirred evenly until the copper nitrate is completely dissolved in the water.
Soaking a zirconium oxide wafer with the diameter of 23.8mm sintered at 1200 ℃ in a copper nitrate solution for 5 minutes, taking out the zirconium oxide wafer, and drying for 2 hours at 120 ℃.
And heating the impregnated zirconia wafer to 1200 ℃ at the heating rate of 2 ℃ per minute, and keeping the temperature at 1200 ℃ for 4 hours for drying and sintering.
After sintering of the sampleAmount ZrO2The average diameter of the disk of (1) was about 21.3mm, and the mass and volume of the disk were measured to obtain a sample having a density of ZrO281% of the theoretical density.
Scheme 2
The ground 3g of alumina powder was dry-pressed in a powder tabletting machine with a circular powder tank having an inner diameter of 25mm, the tabletting pressure was set at 10MPa and the tabletting time was 5 minutes.
Taking a formed aluminum oxide wafer with the diameter of 25mm, heating to 800 ℃ at the heating rate of 0.5 ℃ per minute, and preserving the temperature at 800 ℃ for 10 hours for sintering.
The mean diameter of the discs of alumina was measured after sintering of the sample and was about 23.8mm, and the mass and volume of the discs were measured to give a sample density of 67% of the theoretical density of alumina.
24.2g of copper nitrate trihydrate is placed in a beaker, 100ml of deionized water is added, and the mixture is stirred uniformly until the copper nitrate is completely dissolved in the water.
And (2) soaking the sintered aluminum oxide wafer with the diameter of 23.8mm in a copper nitrate solution for 5 minutes, adding 12.4g of ethylene glycol into the beaker, then placing the beaker in an ultrasonic cleaning machine, performing ultrasonic dispersion on the beaker under the condition of 80KHz for 10 minutes, taking out a zirconium oxide wafer sample, and drying the zirconium oxide wafer sample at the temperature of 120 ℃ for 2 hours.
And heating the impregnated aluminum oxide wafer to 800 ℃ at the heating rate of 0.5 ℃ per minute, and preserving the temperature at 800 ℃ for 10 hours for sintering.
The mean diameter of the discs of alumina was measured after sintering of the sample and was about 21.1mm, and the mass and volume of the discs were measured to give a sample density of 82% of the theoretical density of alumina.
Scheme 3
The ground 3g of zirconia powder was dry-pressed in a powder tabletting machine with a circular powder tank having an inner diameter of 25mm, the tabletting pressure was set at 10MPa and the tabletting time was 5 minutes.
Taking ZrO with the diameter of 25mm after molding2The wafer is heated to 1300 ℃ at a heating rate of 10 ℃ per minute and at 13 DEG CAnd preserving the heat at 00 ℃ for 1 hour for sintering.
Measurement of ZrO after sintering of the samples2The average diameter of the disk of (1) was about 23.8mm, and the mass and volume of the disk were measured to obtain a sample having a density of ZrO267% of the theoretical density.
24.2g of copper nitrate trihydrate is placed in a beaker, 20ml of deionized water is added, and the mixture is stirred uniformly until the copper nitrate is completely dissolved in the water.
Soaking a zirconium oxide wafer with the diameter of 23.8mm sintered at 1200 ℃ in a copper nitrate solution for 5 minutes, adding 12.4g of ethylene glycol into a beaker, then placing the beaker in an ultrasonic cleaning machine, performing ultrasonic dispersion on the beaker under the condition of 80KHz for 10 minutes, taking out a sample of the zirconium oxide wafer, and drying the sample for 2 hours at 120 ℃.
And heating the impregnated zirconia wafer to 1300 ℃ at the heating rate of 10 ℃ per minute, and preserving the heat at 1300 ℃ for 1 hour for sintering.
Measurement of ZrO after sintering of the samples2The average diameter of the disk of (1) was about 21.1mm, and the mass and volume of the disk were measured to obtain a sample having a density of ZrO282.5% of the theoretical density.
Scheme 4
The ground 3g of zirconia powder was dry-pressed in a powder tabletting machine with a circular powder tank having an inner diameter of 25mm, the tabletting pressure was set at 10MPa, and the tabletting time was 5 minutes.
Taking ZrO with the diameter of 25mm after molding2The wafer is heated to 1200 ℃ at a heating rate of 5 ℃ per minute, and is sintered at 1200 ℃ for 8 hours.
Measurement of ZrO after sintering of the samples2The average diameter of the disk of (1) was about 23.8mm, and the mass and volume of the disk were measured to obtain a sample having a density of ZrO267% of the theoretical density.
24.2g of copper nitrate trihydrate is placed in a beaker, 40ml of deionized water is added, and the mixture is stirred uniformly until the copper nitrate is completely dissolved in the water.
Soaking a zirconium oxide wafer with the diameter of 23.8mm sintered at 1200 ℃ in a copper nitrate solution for 5 minutes, taking out the zirconium oxide wafer, and drying for 2 hours at 120 ℃.
Adding 100ml of sodium citrate aqueous solution into a beaker, soaking the dried zirconium oxide wafer sample in the sodium citrate aqueous solution for 1 minute, and drying the soaked sample for 1 hour at the temperature of 120 ℃.
And heating the impregnated zirconia wafer to 1200 ℃ at a heating rate of 5 ℃ per minute, and keeping the temperature at 1200 ℃ for 8 hours for sintering.
Measurement of ZrO after sintering of the samples2The average diameter of the disk of (1) was about 21.2mm, and the mass and volume of the disk were measured to obtain a sample having a density of ZrO281.5% of the theoretical density.
Scheme 5
The ground 3g of zirconia powder was dry-pressed in a powder tabletting machine with a circular powder tank having an inner diameter of 25mm, the tabletting pressure was set at 10MPa, and the tabletting time was 5 minutes.
Taking ZrO with the diameter of 25mm after molding2The wafer is heated to 1200 ℃ at a heating rate of 2 ℃ per minute and is sintered at 1200 ℃ for 4 hours.
Measurement of ZrO after sintering of the samples2The average diameter of the disk of (1) was about 23.8mm, and the mass and volume of the disk were measured to obtain a sample having a density of ZrO267% of the theoretical density.
Taking 15.9g of copper oxide with the diameter of 100nm into a beaker, adding 200ml of absolute ethyl alcohol, uniformly stirring, putting a zirconium oxide wafer with the diameter of 23.8mm sintered at 1200 ℃ into copper oxide dispersion liquid, then putting the beaker into an ultrasonic cleaning machine, performing ultrasonic dispersion for 10 minutes under the condition of 80KHz, taking out a zirconium oxide wafer sample, and drying for 2 hours under the condition of 120 ℃.
And heating the impregnated zirconia wafer to 1200 ℃ at the heating rate of 2 ℃ per minute, and keeping the temperature at 1200 ℃ for 4 hours for sintering.
Measurement of ZrO after sintering of the samples2The average diameter of the disk of (1) was about 21.5mm, and the mass and volume of the disk were measured to obtain a sample having a density of ZrO280% of the theoretical density.
In summary, by uniformly dispersing or dissolving the sintering aid or the sintering aid precursor in the solvent to form a dispersion or solution, and immersing the ceramic green body in the dispersion or solution, in one case, when the sintering aid such as the metal oxide is dispersed in the solvent, the sintering aid can be uniformly dispersed on the surface of the ceramic green body under the mass transfer effect of the solvent, so that the sintering shrinkage and the densification degree of the ceramic can be effectively improved during the sintering process of the ceramic. In another case, when the sintering aid precursor, such as metal nitrate, is dissolved in the solvent, the metal ions in the metal nitrate can form a liquid film to be uniformly dispersed on the surface of the ceramic blank under the mass transfer effect of the solvent, so that the sintering shrinkage and the densification degree of the ceramic can be effectively improved in the ceramic sintering process. Meanwhile, a reducing agent is added into a solvent, or before the ceramic blank is sintered, the dried ceramic blank is impregnated by a water solution of the reducing solvent or the reducing agent, so that metal ions or metal oxides distributed on the surface of the ceramic blank are reduced into metal nano particles, further dispersion of the metal particles is facilitated, in the subsequent sintering process, along with the rise of temperature, the melting point of the metal nano particles is lower, the sintering auxiliary agent and the ceramic powder form a multi-eutectic mixture, a liquid phase is generated at a lower temperature (such as 800 ℃) to promote particle rearrangement and mass transfer processes, the combination of the ceramic powder is promoted, the increase of the densification degree of the ceramic in the sintering process is facilitated, along with the continuous rise of temperature, the liquid-phase metal oxides are continuously volatilized, and a combination area between the ceramic powders is reserved, the combination area promotes the growth of ceramic grains at a certain temperature (such as 1200 ℃), so that the sintering shrinkage of the ceramic can be effectively improved.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (14)
1. A method of making a ceramic, comprising:
dispersing or dissolving a sintering aid or a sintering aid precursor in a solvent to form a dispersion liquid or a solution;
dipping the formed and sintered ceramic blank by the dispersion liquid or the solution to ensure that metal ions or metal oxides in the dispersion liquid or the solution are uniformly distributed on the surface of the ceramic blank; and drying and sintering the ceramic blank after the dipping treatment to obtain the ceramic.
2. The method for producing a ceramic according to claim 1,
the times of the dipping treatment and the drying of the ceramic body after the dipping treatment are 1 to 10 times.
3. The method for producing a ceramic according to claim 2,
the time of one-time dipping treatment is 1-20 min.
4. The method for producing a ceramic according to claim 1,
the solvent is a reducing solvent; alternatively, the first and second electrodes may be,
the solvent is further added with a reducing agent for reducing the metal ions or metal oxides into metal nanoparticles and dispersing the metal nanoparticles in the solution or dispersion liquid.
5. The method for producing a ceramic according to claim 1,
before sintering the ceramic green body, the preparation method further comprises the following steps:
and (3) dipping the dried ceramic blank body by using a reducing solvent or an aqueous solution of a reducing agent to reduce metal ions or metal oxides distributed on the surface of the ceramic blank body into metal nano particles for drying again.
6. The method for producing a ceramic according to claim 4 or 5,
the reducing agent is sodium citrate, amine compounds, aldehyde compounds, alcohol compounds, amide compounds, potassium tartrate or ascorbic acid.
7. The method for producing a ceramic according to claim 4 or 5,
the molar concentration of the reducing agent in the solvent or the water solution is 0.1-0.2 times of the molar concentration of the metal ions in the sintering aid or the sintering aid precursor.
8. The method for producing a ceramic according to claim 4 or 5,
the reducing solvent is ethylene glycol or DMF.
9. The method for producing a ceramic according to claim 1,
heating to 600-1300 ℃ at the heating rate of 0.5-10 ℃/min, and preserving the heat at 600-1300 ℃ for 1-10h to sinter the ceramic blank.
10. The method for producing a ceramic according to claim 1,
the molar concentration of the metal ions in the sintering aid or the sintering aid precursor in the solution or the dispersion liquid is 1-5 mol/L.
11. The method for producing a ceramic according to claim 1,
the particle size of the metal oxide is less than or equal to 500 nm.
12. A ceramic obtained by a method for producing a ceramic according to any one of claims 1 to 11.
13. The ceramic of claim 12,
the sintering shrinkage of the ceramic is 10-20%.
14. The ceramic of claim 12,
the density of the ceramic is more than 80% of the theoretical density.
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| CN113045319A (en) * | 2021-02-07 | 2021-06-29 | 广东省科学院新材料研究所 | Sintering aid modified nano ceramic powder and preparation method thereof |
| CN114133247A (en) * | 2021-12-24 | 2022-03-04 | 武汉理工大学 | Modified SiC-based heat storage ceramic for solar thermal power generation and preparation method thereof |
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| CN111454064A (en) * | 2020-05-15 | 2020-07-28 | 昆山卡德姆新材料科技有限公司 | Composite ceramic filter and preparation method thereof |
| CN111732434A (en) * | 2020-07-07 | 2020-10-02 | 韶关学院 | Ceramic preparation method using in-situ generated oxide as sintering aid |
| CN113045319A (en) * | 2021-02-07 | 2021-06-29 | 广东省科学院新材料研究所 | Sintering aid modified nano ceramic powder and preparation method thereof |
| CN114133247A (en) * | 2021-12-24 | 2022-03-04 | 武汉理工大学 | Modified SiC-based heat storage ceramic for solar thermal power generation and preparation method thereof |
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