KR102005862B1 - Method for preparing ysz nano sol using solvothermal synthesis - Google Patents

Abstract

 (A) preparing a mixed solution by stirring a zirconium acetate solution (ZAS) and a yttrium acetate solution (YAS) at the same concentration with a solvent; (b) adjusting the pH by adding a basic substance to the solution; and (c) heat-treating the solution obtained in the step (b) at a temperature of 120 to 150 ° C to form a yttria-stabilized zirconia , YSZ) nano-sol. The present invention relates to a method for preparing a YSZ nano-sol using a solvent thermo-synthetic method, and more particularly, to a method for producing a uniform high-purity YSZ nano- And the YSZ nano powder prepared according to the present invention can be used for various purposes as a ceramic material requiring high hardness, chemical stability and conductivity.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for preparing a YSZ nano sol using a solvent thermo-synthesis method,

The present invention relates to a method for preparing oxide nanoparticles using a solvent thermo-synthetic method.

Zirconia has a monoclinic crystal structure at room temperature and atmospheric pressure, tetragonal crystal at a temperature of 1150 ° C or higher, cubic crystal structure at a temperature of 2370 ° C or higher Since pure zirconia causes volume change at the time of phase transition as described above, there is a problem that it is difficult to use it as a heat resistant material or a structural material.

Therefore, a metal oxide such as calcium oxide (CaO), magnesium oxide (MgO), yttrium oxide (Y ₂ O ₃ ), or cerium oxide (CeO ₂ ) is added to pure zirconia to maintain tetragonal or cubic structure even at room temperature Zirconia has been stabilized to stabilize crystal structure changes, and it is used as structural materials.

Among them, yttria-stabilized zirconia (YSZ), which is added as a stabilizer to zirconia, is stable at room temperature and high temperature, and has excellent hardness and conductivity, and is used in various fields such as refractories, solid oxide fuel cells useful.

Currently known methods of producing YSZ powders can be divided into solid phase method and liquid phase method.

According to the solid phase method, a raw material powder can be obtained by dry mixing at a desired ratio, followed by solid-phase reaction through high-temperature firing, but it is difficult to obtain fine and uniform powder, and the solid phase method has a disadvantage that impurities are likely to be introduced at the time of synthesis .

On the other hand, the liquid phase method can obtain finer and more uniform powder than the solid phase method.

As a method of synthesizing YSZ powder by such a liquid phase method, a coprecipitation method, an alkoxide method, a hydrothermal synthesis method, and the like are known.

In the co-precipitation process, first, a certain amount of zirconia salt and stabilizer salt are weighed and dissolved in water to prepare a mixed aqueous solution. Then, an alkaline solution such as NH 4 OH is precipitated in a hydroxide state as a precipitant, Followed by drying and calcination to produce YSZ powder. In such coprecipitation method, a salt form such as yttria chloride or yttria nitride is used as the yttria component. These yttria salts in the form of chloride or nitride are high in price, and in particular, in the course of raw material weighing, , It has been difficult to reproducibly synthesize yttria-added YSZ powder having an aimed exact molar fraction (mol%).

On the other hand, the hydrothermal synthesis method using water as a solvent belongs to the solvothermal synthesis method has an advantage of a liquid phase method in which a crystalline and anhydrous ceramics powder can be produced by a single process. The greatest difference between hydrothermal synthesis and solid phase or other liquid phase processes is that a hot calcination process is not required. This means that not only the calcination process but also the subsequent crushing process that is indispensable to follow the calcination process is not required. Therefore, it is possible to suppress the inflow of impurities and the generation of defects which may be caused by the pulverization. Another advantage of the hydrothermal synthesis method is that the selection of the raw materials to be reacted and the reaction conditions are so wide that not only cheap raw materials can be used but also the physical and chemical properties of the powders can be easily controlled, . In addition, a high purity powder can be obtained in a large amount from a raw material which is simple and low in purity and low in production process.

Accordingly, the present inventors propose a novel method for producing YSZ nanoparticles based on a solvent thermo-synthetic method.

Korean Patent Publication No. 10-2002-0088143 (published on November 27, 2002). Korean Patent Laid-Open No. 10-2003-0065004 (Publication date: 2003.08.06.) Korean Registered Patent No. 10-0692642 (Registered Date: Mar. 2, 2007)

SUMMARY OF THE INVENTION The present invention provides a method for producing a high purity YSZ nano sol using an economical and simple process based on a solvent thermal synthesis method.

(A) preparing a mixed solution by stirring a zirconium acetate solution (ZAS) and a yttrium acetate solution (YAS) at the same concentration with a solvent; (b) adjusting the pH by adding a basic substance to the solution; and (c) heat-treating the solution obtained in the step (b) at a temperature of 120 to 150 ° C to form a yttria-stabilized zirconia , YSZ) nano-sol by a solvent thermo-synthesis method.

The concentration of ZAS and YAS in step (a) is 20% (w / w) and 3% (w / w), respectively, and the weight ratio of ZAS and YAS is 90: 95: 5. The present invention also provides a method for preparing YSZ nanosol using the solvent thermo-synthetic method.

Further, the present invention proposes a process for preparing YSZ nano sol using a solvent thermo-synthetic method, wherein the solvent is a mixed solvent of water and ethanol (EtOH).

In addition, the mixed solvent includes water and ethanol in a volume ratio of 50:50 to 75:25. The present invention also provides a method for preparing a YSZ nano sol using the solvent thermo-synthetic method.

Also, the present invention proposes a process for preparing YSZ nano sol using the solvent thermo-synthetic method, wherein the basic substance is ammonium hydroxide (NH ₄ OH).

Also, the present invention provides a process for preparing a YSZ nano sol using a solvent thermo-synthetic method, wherein the solvent thermal reaction is carried out for 8 to 12 hours.

The present invention also proposes YSZ nano sol prepared by the above production method in another aspect of the invention.

According to the present invention, it is possible to produce a homogeneous and fine high-purity YSZ nanopowder through solvent thermal synthesis at a significantly lower reaction temperature than the conventional hydrothermal synthesis. The YSZ nanopowder prepared according to the present invention has high hardness and chemical stability And as a ceramic material requiring conductivity.

1 is a process flow diagram of a method for producing a YSZ nano sol using a solvent thermal synthesis method according to the present invention.
2 (a) to 2 (d) are X-ray diffraction (XRD) results of the YSZ nano sol prepared in Examples 1 to 4 of the present application.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Embodiments in accordance with the concepts of the present invention can make various changes and have various forms, so that specific embodiments are illustrated in the drawings and described in detail in this specification or application. It should be understood, however, that the embodiments according to the concepts of the present invention are not intended to be limited to any particular mode of disclosure, but rather all variations, equivalents, and alternatives falling within the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises ", or" having ", or the like, specify that there is a stated feature, number, step, operation, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Hereinafter, the present invention will be described in detail.

The present invention relates to a novel method for producing a high purity YSZ nano sol using a more economical and simple process than the conventional synthesis method.

1, a method for preparing a YSZ nanosol using a solvent thermosynthetic method according to the present invention comprises the steps of (a) mixing a zirconium acetate solution (ZAS) and a yttrium acetate solution , YAS) with a solvent to prepare a mixed solution; (b) adjusting the pH by adding a basic substance to the solution; and (c) heat-treating the solution obtained in the step (b) at a temperature of 120 to 150 ° C to form a yttria-stabilized zirconia , YSZ) nano-sol.

In this case, the content ratio of ZAS and YAS in the step (a) can be appropriately adjusted according to the molar ratio (ZrO ₂ : Y ₂ O ₃ ) of zirconia and yttria in the finally prepared YSZ nano sol, for example, 20% w / w) ZAS and 3% (w / w) YAS in a weight ratio of 90:10 to 95: 5.

Preferably, the solvent is a mixed solvent of water and ethanol (EtOH) so that the thermal reaction of the solvent can be performed at a low temperature of 120 to 150 ° C. Further, the mixed solvent is used in an amount of 50:50 to 75:25 More preferably, water and ethanol are contained in a volume ratio.

Meanwhile, the kind of the basic substance to be added to adjust the pH of the mixed solution to 9 to 10 in the step (b) is not particularly limited, and may be, for example, ammonium hydroxide (NH ₄ OH).

In the step (c), it is preferable to carry out a solvent thermal reaction at a reaction temperature of 120 to 150 ° C, which is significantly lower than that of the conventional hydrothermal synthesis method, for 8 to 12 hours to synthesize YSZ nano sol.

When the reaction temperature of the solvent heat reaction in this step is less than 120 ° C, the hydrothermal reaction is difficult to occur. When the temperature exceeds 150 ° C, the hydrothermal reaction rate is rapidly increased due to excessive heat, have.

When the reaction time of the solvent thermal reaction is less than 8 hours, sufficient reaction does not occur and particles are difficult to form. When the reaction time exceeds 12 hours, the particle size becomes excessively large and the stability of the particles deteriorates Lt; / RTI >

The method for producing YSZ nano sol using the solvent thermo-synthetic method according to the present invention can produce a homogeneous and fine high purity YSZ nano powder through a solvent thermal synthesis method at a significantly lower reaction temperature than the conventional hydrothermal synthesis method, The YSZ nano powder prepared according to the invention can be used for various applications as a ceramic material requiring high hardness, chemical stability and conductivity.

Hereinafter, the present invention will be described in more detail with reference to examples.

The embodiments according to the present disclosure can be modified in various other forms, and the scope of the present specification is not construed as being limited to the embodiments described below. Embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the art.

<Examples>

A 20% (w / w) zirconium acetate solution (ZAS) containing zirconium acetate (C ₈ H ₁₂ O ₈ Zr) as a zirconia precursor is mixed with yttrium acetate (C ₆ H ₉ O ₆ Y ) Was stirred with a mixed solvent containing water and ethanol according to the volume ratio described in Table 1 below to give ZA and YA in an amount of 12.74% (w / w) w) was prepared.

Ammonium hydroxide (NH ₄ OH, 16%) was then added to the mixed solution and the pH of the solution was adjusted to 9 or 10 by stirring.

Next, the mixed solution was transferred into a Teflon container, placed in a high-temperature reaction container, and reacted at 120 ° C or 150 ° C for 12 hours as shown in Table 1 below to obtain a YSZ nano sol.

The crystallinity of the YSZ nano sol prepared according to Examples 1 to 4 was confirmed by measuring X-ray diffraction (MiniFlex II, RIGAKU) in two ranges of 20-80 °. The specific surface area of the YSZ nanoparticles was measured using a specific surface area analyzer (BET, Autosorb-iQ, Quantachrome Instrement).

2 (a) to 2 (d) are XRD measurement results of the YSZ nano sol prepared in Examples 1 to 4, respectively. Referring to FIG. 2, it was confirmed that YSZ nano sol of Example 3 produced by solvent thermo-synthesis at 150 ° C using a solvent containing water and ethanol in a volume ratio of 75:25 exhibits the highest crystallinity.

Referring to Table 1, it was confirmed that the YSZ nano sol of Example 4 produced by solvent thermo-synthesis at 150 ° C. using a solvent containing water and ethanol in a volume ratio of 50:50 exhibits the largest specific surface area .

Claims (7)

(a) preparing a mixed solution by stirring a zirconium acetate solution (ZAS) and a yttrium acetate solution (YAS) at the same concentration with a solvent;
(b) adjusting the pH by adding a basic substance to the mixed solution; and
(c) forming a yttria-stabilized zirconia (YSZ) nano-sol by reacting the solution obtained in step (b) with a solvent at a temperature of 120 to 150 ° C,
In step (a), the concentrations of ZAS and YAS are 20% (w / w) and 3% (w / w)
Wherein the weight ratio of ZAS and YAS is from 90:10 to 95: 5. delete The method according to claim 1,
Wherein the solvent is a mixed solvent of water and ethanol (EtOH). The method of claim 3,
Wherein the mixed solvent comprises water and ethanol in a volume ratio of 50:50 to 75:25. The method according to claim 1,
Wherein the basic substance is ammonium hydroxide (NH ₄ OH). The method according to claim 1,
Wherein the solvent thermal reaction is performed for 8 to 12 hours. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt; delete

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