RU2769683C1 - Method for producing zirconium dioxide powders with a spheroidal particle shape with a stabilizing component content of 20 to 60 wt. % - Google Patents

Abstract

FIELD: chemical industry.

SUBSTANCE: invention relates to the chemical industry and powder metallurgy and can be used in plasma spraying, slip casting, laser sintering. First, a general solution of hydrolysis-resistant inorganic zirconium salts and metal salts of group 3 of the Periodic table of chemical elements selected from scandium, yttrium, lanthanum or lanthanides is prepared in an aqueous solution in an amount that ensures the content of the latter up to 20% of the final mass of the composition in terms of oxides. The precipitating solution is prepared by dissolving alkali metal hydroxides or ammonia in water. Then the hydroxy compounds of zirconium and these metals are precipitated by dosing the prepared solutions into the reaction vessel while stirring and maintaining a constant pH from 5.0 to 6.5 inclusive due to the controlled introduction of the precipitating solution. The resulting precipitate is separated from the mother solution. Then the second part of the solution of these group 3 metal salts is introduced while maintaining a constant pH from 5.0 to 6.5 inclusive due to the controlled introduction of a precipitator solution until the content of these salts containing stabilizing components reaches from 20 to 60% of the final mass of the composition in terms of oxides. The resulting suspension is evaporated with stirring until a precipitate is formed, which is dried and fired.

EFFECT: resulting powder materials based on zirconium dioxide have a regular spheroidal particle shape with a narrow size distribution.

1 cl, 4 dwg, 5 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The invention relates to a technology for producing oxide powder materials, in particular to a technology for producing powder materials based on zirconium dioxide with a spheroidal particle shape containing stabilizing components from 20 to 60 mass percent, which can be used to produce ceramics, coatings, sorbents and catalysts, in including electrodes and electrolytes of high-temperature electrochemical devices.

BACKGROUND OF THE INVENTION

Zirconium dioxide is widely used in the creation of ceramics and coatings, sorbents and catalysts, electrodes and electrolytes of high-temperature electrochemical devices. The shape and size of particles are among the most important technological parameters of powder materials, which can be decisive when they are used in various fields of technology. Narrow fractionated powders with a regular shape close to spherical provide high flowability and bulk density of powder materials, low hydro- and aerodynamic resistance of particles. Powder materials based on zirconium dioxide with a content of stabilizing components from 20 to 60 mass percent make it possible to obtain protective coatings with improved heat-shielding properties and stability at high temperatures. Therefore, the task of forming narrowly fractionated powder materials based on zirconium dioxide with the correct shape of particles and an increased content of stabilizing components from 20 to 60 mass percent is very relevant.

A known method for producing ceramic monodisperse ZrO2 spheres with a size of 200 or more micrometers (X. Rui, Ch. Jiansong, Zh. Shijiao, H. Shaochang, Zh. Xingyu, L. Jianjun, D. Changsheng, M. Jingtao. Preparation of monodisperse ZrO2 ceramic microspheres (> 200 μm) by coaxial capillary microfluidic device assisted internal gelation process Ceram Int., Volume 45, (2019), pp. 19627-19634 https://doi.org/10.1016/j.ceramint.2019.06 .210) which includes preparing a precursor solution by mixing zirconium nitrate and yttrium hexahydrate nitrate, adding concentrated nitric acid to the precursor solution, preparing a solution of hexamethylenetetramine with a certain amount of urea, mixing solutions, forming sol droplets and dispersing them into oil at a temperature of 90 ° C with the formation of gel spheres, after which the gel spheres were washed with trichlorethylene and ammonia solution, subjected to hydrothermal treatment at 200°C, then washed with deionized water and methyl ether ohm of propylene glycol, drying and heat treatment were carried out. The advantages of the method are the production of monodisperse spherical particles of zirconium dioxide, the regulation of the particle size by changing the size of the droplets. The disadvantage of this method is the work with a large number of organic compounds heated to a high temperature, a large number of stages in the process of obtaining the final powder material. There is no information about the possibility of obtaining powder materials based on zirconium dioxide with an extended range of concentrations of stabilizing components.

A known method [Patent RU 2235686, prior. dated 04.01.2003, publ. 09/10/2004, IPC C01G 25/02, C25B 1/00, B01J 20/06] obtaining spherical powder materials based on zirconium hydroxide and oxide, which includes the dissolution of zirconium carbonate in hydrochloric acid until the Cl/Zr atomic ratio in solution is 0 ,8-1.8, electrolysis of a chloride solution at a temperature of 40-100 ° C to an atomic ratio of Cl / Zr equal to 0.2-0.5, introduction of a soluble compound of a metal of group III of the Periodic system of D.I. Mendeleev, dispersion of the sol into a gelling medium, separation of the formed gel spheres, their washing, drying and heat treatment. The advantage of the described method is the ability to use an aqueous solution of ammonia or alkali as a gelling medium, which is provided by obtaining a highly viscous zirconium sol at the stages of carbonate dissolution and solution electrolysis. Significant disadvantages of the method are the complexity and multi-stage process, the need to work with hydrochloric acid, which necessitates thorough washing of the obtained gel spheres from residual chlorine ions, the difficulty in obtaining powder materials with a narrow particle size distribution at the level of 10-60 microns. There is no information about the possibility of obtaining powder materials based on zirconium dioxide with a stabilizing component content of more than 20 mass percent.

An alternative approach for forming well-shaped zirconia particles is the electromelting of zirconia particles and a stabilizing component. A known method [Patent US 6893994, prior. dated 13.08.2002, publ. 19.02.2004, IPC C23C-004/10] the formation of chemically homogeneous particles of zirconium dioxide, which includes electrofusion of zirconium dioxide and a stabilizing component, cooling and heat treatment of the resulting powder material. The technical result is the formation of predominantly spherical hollow particles with a size of less than 200 microns. The advantage of the proposed method is the ability to obtain hollow particles, the ability to widely vary the content of the stabilizing component. Significant disadvantages of the method are the difficulty in obtaining powder materials with a narrow particle size distribution at the level of 10-60 μm and high energy costs for melting.

The closest way to obtain spheroidal particles based on zirconium dioxide is described in the patent [Patent RU 2714452, prior. dated 28.09.2019, publ. 02/17/2020, IPC B22F 9/24, C25B 1/20, C23C 4/11]. The method includes the preparation of aqueous solutions of salts of zirconium and metals of the 3rd group of PSCE, the preparation of a precipitant solution by dissolving alkali metal or ammonia hydroxides in water, the precipitation of hydroxo compounds of zirconium and selected metals by dosing the total solution into the reaction volume, in which mixing is carried out and a constant temperature is maintained. pH value due to the controlled introduction of the precipitant solution, separation of the precipitate, drying and heat treatment. The advantages of this method are the formation of spheroidal particles in an aqueous medium, a small number of stages in the process of obtaining powder material, the possibility of controlling the particle size by changing the duration of deposition. The disadvantage of this method is the impossibility of obtaining powder materials based on zirconium dioxide containing a stabilizing component from 20 to 60 mass percent.

Thus, the technical problem facing the authors of the present invention is to overcome the above described disadvantages, namely the expansion of the range of contents of stabilizing components while maintaining the correct particle shape and narrow particle size distribution using the precipitation method while maintaining a constant pH value.

DISCLOSURE OF THE INVENTION

The technical result achieved in the implementation of the invention is to expand the range of contents of the stabilizing components while maintaining the correct shape of the particles and a narrow particle size distribution. The claimed method for obtaining powder materials based on zirconium dioxide with a stabilizing component content of 20 to 60 mass percent includes the following steps:

- preparation of hydrolysis-resistant water-soluble salt of zirconium;

- preparation of hydrolysis-resistant water-soluble salts of metals of the 3rd group of the Periodic Table of Chemical Elements D.I. Mendeleev (PSCE D.I. Mendeleev), selected from among scandium, yttrium, lanthanum and lanthanides;

- mixing an aqueous solution of a zirconium salt and a part of an aqueous solution of metal salts of the 3rd group of PSCE D.I. Mendeleev with the formation of a common solution of metal salts;

- preparation of a precipitant solution by dissolving alkali metal hydroxides or ammonia in water;

- precipitation of hydrated zirconium oxide by simultaneous dosing of a total solution of metal salts and a solution of a precipitant by drop method into the reactor, where the reaction volume is constantly stirred and the pH value is maintained at the same level from the range of values from 5 to 6.5 inclusive due to the controlled introduction of the precipitant solution ;

- separation of the precipitate formed from the mother liquor, introduction of the solution of the second part of the salts of metals of the 3rd group of PSCE D.I. Mendeleev while maintaining the pH value of the suspension at the same level from the range of values from 5 to 6.5 inclusive due to the controlled introduction of the precipitant solution;

- evaporation of the resulting suspension, drying and heat treatment of the precipitate.

The authors of the invention proceeded from the fact that due to the difference in the pH values of the onset of precipitation of hydroxo compounds of zirconium and metals of the 3rd group of PSCE, with an increase in the content of salts of metals of the 3rd group of PSCE in the total solution going on precipitation, higher than 20% by weight of the final composition in terms of oxides, accumulation of cations of metals of the 3rd group of PSCE in the liquid part of the suspension, which in turn can lead to the formation of a solid phase of hydroxo compounds of metals of the 3rd group of PSCE at the site of introduction of the precipitant solution into the suspension. The formation of a separate solid phase of hydroxocompounds of Group 3 metals can lead to a decrease in the average particle size of the powder material, an increase in the size dispersion, and also to the phase inhomogeneity of the powder materials after firing. To prevent the described undesirable effects, the authors of the invention proposed to divide the amount of metal salts of the 3rd group of PSCE into two parts. The first part of metal salts of group 3 PSCE in an amount of 0 to 20% by weight of the final composition in terms of oxides is proposed to be introduced into the general solution for precipitation. The second part of metal salts of group 3 PSCE is proposed to be introduced into the already formed precipitate of hydrated zirconium dioxide. The authors of the invention found that adding a solution of salts of metals of the 3rd group of PSCE to a precipitate of hydrated zirconium oxide while maintaining a constant pH value in the range of values from 5.0 to 6.5 inclusive due to the controlled introduction of a precipitant solution with subsequent evaporation of the suspension makes it possible to achieve preservation of the average and dispersion of powder particles. Subsequent heat treatment leads to the formation of a composition with a homogeneous phase composition, while such an oxide powder material is characterized by a narrow particle size distribution and a particle shape close to spheroidal.

IMPLEMENTATION OF THE INVENTION

At the first stage of obtaining powder materials based on zirconium dioxide with spheroidal particles, a solution of zirconium salt in water is prepared. As the zirconium salt, hydrolysis-resistant, water-soluble salts of inorganic acids, especially zirconium nitrate, chloride or sulfate, can be used. The nature of the salt anion does not significantly affect the possibility of implementing the invention. In order to prepare a zirconium salt solution, the corresponding zirconium salt is dissolved in water. It is also possible to prepare a zirconium salt solution by dissolving zirconium compounds in an appropriate inorganic acid. According to the preferred method of implementing the invention, basic zirconium carbonate and nitric acid are used to prepare a zirconium salt solution.

At the second stage of obtaining powder materials based on zirconium dioxide, the first part of the solution of salts of metals of the 3rd group of PSCE D.I. is introduced into an aqueous solution of a zirconium salt. Mendeleev, selected from among scandium, yttrium, lanthanum and lanthanides until the content of the stabilizing component is from 0 to 20% by weight in terms of oxides with the formation of a common solution of metal salts. As salts of metals of the 3rd group of PSCE D.I. Mendeleev, water-soluble inorganic salts resistant to hydrolysis can be used, primarily nitrates, chlorides or sulfates of the corresponding metals selected from among scandium, yttrium, lanthanum and lanthanides. The nature of the salt anion does not significantly affect the possibility of implementing the invention. Additive of metal salts of group 3 PSCE D.I. Mendeleev can be performed both by dissolving metal salts of the 3rd group of PSCE D.I. Mendeleev in a solution of zirconium salt in water, and by introducing an aqueous solution of salts of metals of the 3rd group of PSCE D.I. Mendeleev in a solution of zirconium salt. With an increase in the amount of the addition of a compound of metals of the 3rd group of PSCE, D.I. Mendeleev above 20% by weight, incomplete coprecipitation of metals of the 3rd group of PSCE D.I. Mendeleev selected from the group of lanthanum, yttrium or lanthanides with hydrated zirconium dioxide, which can lead to a decrease in the average particle size of the powder material, an increase in the size dispersion, and also to phase inhomogeneity of the powder materials after firing.

At the third stage, a precipitating solution is prepared. An aqueous solution of alkali metal hydroxides or ammonia with a pH value of more than 7, including an aqueous solution of ammonia, sodium or potassium hydroxide, can be used as a precipitating solution. In a preferred embodiment of the invention, aqueous ammonia is used to precipitate the hydrated zirconium oxide.

At the fourth stage of obtaining a powder material based on zirconium dioxide with a spheroidal particle shape, an aqueous medium is introduced into the reaction volume. An aqueous medium is necessary for the distribution of reagents and reaction products in the reaction volume at the initial stage of precipitation, as well as to ensure stable operation of the pH meter and pH control. The amount of aqueous medium introduced into the reaction volume is not critical. In general, in order to reduce the volume of apparatuses, the minimum amount of an aqueous medium is introduced into the reaction volume, which is necessary to ensure pH control and distribution of reagents and reaction products due to mixing. Distilled water or aqueous solutions of inorganic salts can be used as an aqueous medium. In general, the type of cations and anions of salts does not significantly affect the implementation of the invention, however, the addition of salts with a buffer capacity, such as ammonia salts, leads to an increase in the inertia of the pH value of the reaction volume and facilitates maintaining a constant pH value in the reaction volume at the initial stage deposition.

At the fifth stage of obtaining a powder material based on zirconium dioxide with a spheroidal particle shape, hydrated zirconium oxide is precipitated by dosing a total solution of metal salts obtained in the second stage into the reaction volume in which stirring and a constant pH value from the range of values are maintained during the entire precipitation process from 5 to 6.5 units, inclusive, due to the controlled introduction of the precipitant solution obtained in the third stage. Hereinafter, a constant pH value during the entire precipitation process is understood to mean a value that does not differ from the selected one by more than 0.1 units, while in the first minutes of precipitation, the pH deviation from the set value may exceed 0.1 units. due to the low inertia of the reaction volume. The inertia of the reaction volume during the precipitation process depends on a large number of factors, primarily on the composition of the initial aqueous medium, on the type and concentration of the precipitant solution used, on the acidity and total concentration of salts in the total solution of metal salts, on the ratio of the reaction volume and the rates of introduction of the components . For this reason, the duration of establishing a constant pH value in the reaction volume varies to a large extent depending on the chosen conditions for organizing the precipitation process. In the general case, within the framework of the proposed synthesis method, the pH value during the precipitation process is considered constant if the period of establishing a constant pH value in the reaction volume does not exceed one tenth of the total duration of the precipitation process. A constant pH value during the precipitation process is ensured by controlled independent dosing of a total solution of metal salts having a pH value of less than 7, and a precipitant solution having a pH value of more than 7. Controlled independent dosing of solutions can be performed using peristaltic pumps, membrane pumps, pumps direct dosing, variable speed centrifugal pumps, and other methods. The pH of the reaction volume is monitored throughout the entire precipitation process using pH meters with ion-selective electrodes or other systems for detecting pH in solution.

At the sixth stage of obtaining a powder material based on zirconium dioxide with a spheroidal particle shape, the precipitate is separated from the mother liquor. Separation of the precipitate from the mother liquor is possible by filtration, centrifugation, decantation or any other method. According to the preferred method of implementing the invention, a filtration method is used to separate the precipitate from the mother liquor. Then, a solution of the second part of metal salts of the 3rd group of PSCE D.I. is added to the precipitate. Mendeleev, maintaining a constant pH value from the range of values from 5.0 to 6.5 inclusive due to the controlled introduction of a precipitant solution, until the content of oxides of these metals is from 20 to 60% of the final mass of the composition in terms of oxides. Next, the suspension is kept under stirring for an hour, and then evaporated until a precipitate forms. Evaporation of the precipitate can be carried out in various ways, including at atmospheric or reduced pressure. According to the preferred method of implementing the invention, the evaporation of the suspension is carried out using a rotary evaporator at reduced pressure and temperature.

After evaporation, the operations of drying and roasting the formed precipitate are carried out. Preferably, the drying of the precipitate is carried out at a temperature of from 30 to 120°C to constant weight, and the firing of the precipitate at a temperature of from 300 to 1300°C.

The possibility of implementing the invention is confirmed by examples.

Example 1

This example refers to a composition of 40% by weight zirconia and 60% gadolinium oxide.

In a beaker with stirring enter 550 ml of distilled water and 381 grams of zirconium carbonate (the content of zirconium oxide in zirconium carbonate is 42% by weight). To the resulting suspension add 178.2 ml of concentrated nitric acid (mass concentration of 71.6%). After complete dissolution of zirconium carbonate, 99.6 grams of gadolinium nitrate hexahydrate Gd(NO ₃ ) ₃ ⋅6H ₂ O are introduced into the solution until the content of gadolinium oxide reaches 10% by weight of the final weight of the composition. After complete dissolution of gadolinium nitrate, the volume of the solution is adjusted to 2000 ml using a volumetric flask. The resulting solution is kept under stirring for 2 hours before precipitation. In parallel with the preparation of a common solution of metal salts, a precipitating solution is prepared. To do this, 350 ml of concentrated ammonia solution (mass concentration 24%) and 438 ml of distilled water are introduced into the beaker.

To carry out the precipitation of hydrated zirconium oxide with spheroidal particles, 200 ml of distilled water is introduced into the reactor equipped with a stirrer and a pH sensor. Then, using peristaltic pumps, a controlled dosed introduction of a total solution of metal nitrates and an aqueous solution of ammonia into the reaction volume is carried out with stirring, and the pH value in the reaction volume is maintained constant at the level of 5.0 ± 0.1 units. by balancing the injection rates of both solutions.

After the precipitation is completed, the resulting suspension is separated from the mother liquor by filtration, the precipitate is transferred into a beaker, into which 1 l of distilled water is then added, stirred, 497.9 grams of gadolinium nitrate hexahydrate Gd(NO ₃ ) ₃ ⋅ 6H ₂ O is added in the form of an aqueous solution, at a constant pH of 5, maintained by the controlled introduction of the precipitant solution until the content of gadolinium oxide reaches 60% by weight of the final mass of the composition. After introducing the entire volume of the solution of gadolinium nitrate hexahydrate, the suspension is evaporated using a rotary evaporator. The heating of the suspension is carried out using a water bath with a water temperature of 80°C, while the pressure in the flask is at the level of 200 millibars.

After the separation of moisture is completed, the resulting precipitate is removed from the flask, placed in an oven and dried at a temperature of 100°C for 12 hours. After that, the precipitate is fired in a muffle furnace at a temperature of 1000°C for 2 hours.

After firing, the particle size distribution is measured using an Analisetta 22 nanotech laser diffractometer using a green and infrared laser. The shape of the particles is examined using optical microscopy. The phase composition is examined using an X-ray diffractometer. The particle size distribution is characterized by a set of different parameters, D[4,3] is the average volume diameter of the particles, the size dispersion is a parameter characterizing the spread of particle sizes of the powder material, determined by the ratio (D90-D10)/D50. The described particle size distribution parameters of the samples and other characteristics for all examples are shown in FIG. 1. The particle size distribution for the sample obtained according to example 1 is shown in figure 2, the optical photograph of the particles of the sample according to example 1 is shown in figure 3, the phase composition of the powder material is shown in figure 4.

Example 2

This example refers to a composition of 52% by weight zirconia and 48% yttrium oxide.

In a beaker with stirring enter 550 ml of distilled water and 433.3 grams of zirconium carbonate (the content of zirconium oxide in zirconium carbonate is 42% by weight). To the resulting suspension is added 202.4 ml of concentrated nitric acid. After complete dissolution of zirconium carbonate, 43.8 grams of yttrium nitrate Y(NO ₃ ) ₃ is introduced into the solution in the form of an aqueous solution to achieve a yttrium oxide content of 5% by weight of the final weight of the composition. After mixing the salt solutions, the volume of the total solution is adjusted to 2000 ml using a volumetric flask. The resulting solution is kept under stirring for 2 hours before precipitation. In parallel with the preparation of a common solution of metal salts, a solution of a precipitant is prepared. To do this, 350 ml of concentrated ammonia solution (mass concentration 24%) and 438 ml of distilled water are introduced into the beaker. Precipitation is carried out at a constant pH value of 5.0±0.1.

After the precipitation is completed, the resulting suspension is separated from the mother liquor by filtration, the precipitate is transferred to 1 l of distilled water, mixed, 365 grams of yttrium nitrate Y (NO ₃ ) ₃ are introduced in the form of an aqueous solution at a constant pH value of 5 maintained by controlled introduction of the solution - precipitant to achieve the content of yttrium oxide 48% by weight of the final weight of the composition. After introducing the entire volume of the yttrium nitrate solution, the suspension is evaporated in the same way as described in example 1.

The formed precipitate is dried and fired in the same way as described in example 1.

Example 3

This example refers to a composition of 60% by weight zirconia and 40% gadolinium oxide.

In a beaker with stirring enter 450 ml of distilled water and 381 grams of zirconium carbonate (the content of zirconium oxide in zirconium carbonate is 42% by weight). To the resulting suspension add 221.8 ml of concentrated hydrochloric acid (mass concentration of 36.2%). After complete dissolution of zirconium carbonate, 111.6 grams of gadolinium chloride hexahydrate GdCl ₃ ⋅6H ₂ O are introduced into the solution to achieve a gadolinium oxide content of 20% by weight of the final weight of the composition. After complete dissolution of gadolinium chloride hexahydrate, the volume of the solution is adjusted to 2000 ml using a volumetric flask. The resulting solution is kept under stirring for 2 hours before precipitation. In parallel with the preparation of a common solution of metal salts, a precipitant solution is prepared in the same way as described in example 1. Precipitation is carried out at a constant pH value of 6.5±0.1.

After the precipitation is completed, the resulting suspension is separated from the mother liquor by filtration, the precipitate is transferred into 1 l of distilled water, stirred, 109.6 grams of gadolinium chloride hexahydrate GdCl ₃ ⋅6H ₂ O are introduced in the form of an aqueous solution at a constant pH value of 6.5 maintained for through the controlled introduction of the solution-precipitant to achieve the content of gadolinium oxide 40% by weight of the final weight of the composition. After introducing the entire volume of the gadolinium chloride solution, the suspension is evaporated in the same way as described in example 1. The formed precipitate is dried and calcined in the same way as described in example 1.

Example 4

This example refers to a composition of 70% by weight zirconia and 30% ytterbium oxide.

In a beaker with stirring enter 550 ml of distilled water and 432.8 grams of zirconium carbonate (the content of zirconium oxide in zirconium carbonate is 42% by weight). To the resulting suspension add 202.3 ml of concentrated nitric acid (mass concentration of 71.6%). After complete dissolution of zirconium carbonate, 71.9 grams of ytterbium sulfate eight-water Yb ₂ (SO ₄ ) ₃ ⋅8H ₂ O are introduced into the solution to achieve a ytterbium oxide content of 7% by weight of the final mass of the composition. After complete dissolution of ytterbium sulfate, the volume of the solution is adjusted to 2000 ml using a volumetric flask. The resulting solution is kept under stirring for 2 hours before precipitation.

The precipitant solution is prepared as follows: 52.8 g of anhydrous sodium hydroxide and 400 ml of distilled water are introduced into a beaker. By stirring, complete dissolution of sodium hydroxide is achieved. After complete dissolution of sodium hydroxide, the volume of the solution is adjusted to 500 ml using a volumetric flask. Precipitation is carried out in the same way as described in example 1. After precipitation is completed, the resulting suspension is separated from the mother liquor by filtration, the precipitate is transferred to 1 l of distilled water, stirred, 237 grams of ytterbium sulfate octagonal Yb ₂ (SO ₄ ) ₃ ⋅8H ₂ are introduced O in the form of an aqueous solution at a constant pH of 5 maintained by the controlled introduction of the precipitant solution until the content of ytterbium oxide reaches 30% by weight of the final mass of the composition. After introducing the entire volume of the solution of ytterbium sulfate eight-water, the suspension is evaporated in the same way as described in example 1. The formed precipitate is subjected to drying and firing in the same way as described in example 1.

Example 5 (comparative)

This example refers to a composition of 40% by weight zirconia and 60% gadolinium oxide.

In a beaker with stirring enter 550 ml of distilled water and 381 grams of zirconium carbonate (the content of zirconium oxide in zirconium carbonate is 42% by weight). To the resulting suspension add 178.2 ml of concentrated nitric acid. After complete dissolution of zirconium carbonate, 597.5 grams of gadolinium nitrate hexahydrate Gd(NO ₃ ) ₃ ⋅6H ₂ O are introduced into the solution until the content of gadolinium oxide reaches 60% by weight of the final weight of the composition in terms of oxides. After complete dissolution of the salt, the volume of the solution is adjusted to 2000 ml using a volumetric flask. The resulting solution is kept under stirring for 2 hours before precipitation. Precipitation is also carried out as described in example 1. Next, the precipitant solution is slowly introduced into the suspension until a pH value of 9 is reached. The resulting suspension is separated from the mother liquor by filtration, then drying and firing are carried out as described in example 1.

Thus, from the above examples it follows that the deposition of hydrated zirconium oxide with the content of metals of the 3rd group of PSCE D.I. Mendeleev in a common solution in the range from 0 to 20% of the final mass of the composition (examples 1, 2, 3, 4) from solutions of various water-soluble inorganic salts (examples 1,3,4) at a constant pH value in the reaction volume from the range of values from 5 to 6.5 (examples 1, 3), when using an aqueous solution of ammonia and alkali metal hydroxides as a precipitant solution (examples 1, 2, 3, 4), when introducing into the suspension a solution of the second part of metal salts of group 3 PSCE D .AND. Mendeleev until the content of salts of these metals is from 20 to 60% of the final mass of the composition in terms of oxides and further evaporation (examples 1,2,3,4) leads to the formation of spheroidal particles, with a narrow particle size distribution and a homogeneous phase composition of the powder material, while precipitation with the content of metal salts of group 3 PSCE D.I. Mendeleev 60% of the final mass of the composition in the total solution, which is outside the stated range (example 5), at a pH value of 5 leads to the formation of particles with high dispersion and heterogeneity of the phase composition. The particles of samples obtained according to examples 1, 2, 3, 4 are characterized by a high average size, low size dispersion, phase homogeneity and spheroidal shape compared to sample 5. Thus, the proposed synthesis method ensures the achievement of the claimed technical result.

Claims (1)

A method for producing powder materials based on zirconium dioxide with a spheroidal particle shape, including the preparation of a general solution of hydrolysis-resistant inorganic salts of zirconium and metal salts of group 3 of the Periodic Table of chemical elements selected from scandium, yttrium, lanthanum and lanthanides in an aqueous solution, in an amount that provides the content of the latter is up to 20% of the final mass of the composition in terms of oxides, the preparation of a precipitant solution by dissolving alkali metal or ammonia hydroxides in water, the precipitation of hydroxo compounds of zirconium and selected metals by dosing the indicated solutions into the reaction volume, in which mixing is carried out and a constant value is maintained pH due to the controlled introduction of a precipitant solution, separation of the precipitate formed from the mother liquor, drying and roasting, characterized in that at the stage of preparation of the general solution, a part of the indicated metal salts of the 3rd group of the Periodic Table of the Chemical of their elements, during precipitation, a constant pH value is maintained in the range of values from 5.0 to 6.5 inclusive; 5.0 to 6.5 inclusive due to the controlled introduction of a precipitant solution until the content of the indicated salts is reached from 20 to 60% of the final composition weight in terms of oxides, the resulting suspension is evaporated with stirring until a precipitate is formed, which is sent for drying and firing.

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