CN1260134C - Method for preparing zirconium oxide micro powder - Google Patents

Abstract

The present invention relates to a method for preparing superfine zirconia powder, which is characterized in that a coprecipitation method is utilized to cause ammonia water and zirconium salt to react in a solution; the produced precipitate is washed and filtered, and is added to a zirconium oxychloride solution to cause the precipitate to generate peptization. The sol is used as a core for crystallization, and is heated to be further hydrolyzed to produce precipitate. The hydrolyzate is washed, calcined and ground, and superfine nanometer zirconia powder with uniform primary grains having controllable sizes is prepared. The present invention solves the problems that the crystallization nucleation and the growth process are uncontrollable and the primary grains are not uniform in the prior art. The prepared primary zirconia grains are uniform and have the advantages of controllable sizes, high quality, low preparation cost and high preparation efficiency.

Description

A method for preparing zirconia ultrafine powder

technical field

The invention relates to a method for preparing zirconia superfine powder. The powder prepared by the method has uniform particle distribution and compact structure, and is mainly used for preparing high-strength and high-density structural ceramics.

Background technique

Existing methods for preparing zirconia ultrafine powder include: uniform precipitation method, co-precipitation method, heating hydrolysis method, etc.

Uniform precipitation method: Mix zirconium oxychloride and urea solution evenly, heat it above 70°C, urea will decompose, and the decomposition reaction equation is as follows:

With the continuous decomposition of urea, the ammonia water produced will continuously increase the pH value of the solution. To a certain extent, the viscosity of the solution will suddenly increase, and precipitation will occur due to the uncontrollability of the growth process. The final precipitation is a kind of space. Grid-like gels are very difficult to filter and wash, making them difficult to use in large-scale production.

Co-precipitation method: first make a solution of zirconium salt in water to a certain concentration, called solution B; then dilute ammonia water to a certain concentration, called solution A. Using the forward drop method (that is, adding solution A to solution B) or the reverse drop method (adding solution B to solution A), the reaction is carried out to obtain a gel-like precipitate. The gel is washed and calcined to obtain ultrafine powder. The disadvantage of this method is that the particle size is uneven and the composition distribution is uneven. Especially in the reverse drop method, a large number of nuclei are formed in a short period of time, and the nucleation and growth are basically instantaneous and cross-over, and there is no way to completely separate the nucleation and growth. It can be inferred from this that the size of primary particles is also uneven, and the size control of primary particles and specific surface area can only be controlled by calcination temperature and time. Prolonging calcination time is economically uneconomical. In general, control Calcination temperature is the only means. The consequence is that the crystallization of the particles is not perfect, and there are holes inside the primary particles.

Hydrolysis method: Heating the zirconium oxychloride aqueous solution to a certain temperature to continuously volatilize hydrogen chloride. After the pH value rises to a certain level, the solution spontaneously nucleates to form a crystal core, and the prepared ultrafine powder is inconsistent in size. In addition, it is heated It takes a long time, usually takes 5-10 days, consumes a lot of energy, and the cost is high.

Contents of the invention

The object of the present invention is to provide a method for preparing zirconia ultrafine powder, the zirconia primary particles prepared by the method are controllable, uniform, high in quality, low in preparation cost and high in efficiency.

The object of the present invention is achieved like this: a kind of method for preparing zirconia superfine powder, is characterized in that: utilize the method for co-precipitation to make ammoniacal liquor and zirconium oxychloride react in solution, the precipitate that produces is after washing, filtering, Add it to the zirconium oxychloride solution to peptize the precipitate, use the sol as the crystallization core, add the zirconium oxychloride solution continuously and slowly, heat the solution to further hydrolyze to produce a precipitate, wash, calcinate, and grind the hydrolyzate to prepare a primary particle size Controllable and uniform nano-zirconia ultrafine powder.

The purpose of the present invention can also be achieved like this: the above-mentioned method for preparing zirconia ultrafine powder is characterized in that: operate according to the following steps successively:

i) Aqueous ammonia and zirconium oxychloride are prepared into homogeneous solutions A and B respectively, and solution B is added to solution A to make PH=7 to obtain precipitation of zirconium hydroxide;

ii) fully washing and filtering the precipitate, adding it to the zirconium oxychloride solution, and heating to boiling to make them fully react and peptize;

iii) separating the sol and the unpeptized precipitate by centrifugation to obtain a uniform zirconium hydroxide sol;

iv) Use the sol as the seed crystal of the hydrolysis reaction, heat to 80-105°C, continuously and slowly add zirconium oxychloride solution to supplement the zirconium ions consumed by hydrolysis, and finally obtain zirconium hydroxide precipitation with uniform particle size and controllable size things,

v) Washing, calcining, grinding, and spray drying the precipitate to obtain ultrafine nano zirconia powder.

Compared with the prior art, the present invention has the following advantages: the present invention combines the co-precipitation method and the heating hydrolysis method to learn from each other, thereby solving the problems of uncontrollable crystal nucleation and growth and uneven primary particle size. In the present invention, after adding foreign crystal cores, no spontaneous nucleation occurs, the number of crystal nuclei is constant, and the final particle size can be controlled by the length of hydrolysis time. Another advantage of this method is that it relies on the addition of foreign crystal nuclei instead of spontaneous nucleation, which saves the incubation time of spontaneous nucleation, shortens the time required for direct hydrolysis to 1/2 of the original, and greatly improves the efficiency.

Description of drawings

Accompanying drawing is the X-ray diffraction pattern of zirconia ultrafine powder of the present invention

Detailed ways

The present invention mainly aims at the shortcomings of the prior art, combines the co-precipitation method and the heating hydrolysis method, learns from each other, and proposes a method for preparing ultrafine zirconia powder with high quality and low cost. The basic process is to make ammonia water and zirconium salt react in the solution by co-precipitation method, and after the resulting precipitate is filtered and washed, zirconium oxychloride is added to peptize the precipitate, and the sol is used as the crystallization core, continuously and slowly Zirconium oxychloride solution is added, heated to further hydrolyze the solution to produce precipitation, and the hydrolyzate is washed, calcined, and ground to prepare uniform zirconia particles with a controllable primary particle size. The key steps are: 1) Precipitate the zirconium salt solution by adding ammonia water, wash and filter the precipitate; 2) Add the clean precipitate into the zirconium oxychloride solution, heat to make it peptized; 3) Centrifugal sedimentation, Remove the unpeptized precipitate to obtain a uniform sol; 4) continuously and slowly add a zirconium oxychloride solution, heat and hydrolyze the above solution, and prepare nano zirconium oxide particles of uniform size.

According to current research, doping yttrium oxide and other oxides in zirconia can obtain zirconia with a stable tetragonal phase structure, which can improve the material strength and fracture toughness of zirconia, so yttrium oxide solution can be added to zirconia solution to produce Prepare high-performance nano-zirconia ultrafine powder by forming a mixed solution.

Example 1

Follow the steps below in order:

i) Prepare zirconium oxychloride into solution B with a concentration of 1.0M, dilute 14M ammonia water into solution A of 1.0M, and add solution A to solution B under constant stirring conditions to produce precipitation of zirconium hydroxide. Stop at PH=7.0, aging for 12 hours;

ii) Wash the precipitate fully with deionized water until no white precipitate can be detected with silver nitrate, and obtain precipitate C; dissolve zirconium oxychloride in deionized water to obtain solution D; add precipitate C to solution D, add water When the concentration of zirconium ions reaches 1.0M, heat to boiling under stirring conditions until all the precipitates are peptized;

iii) Centrifugal sedimentation to separate the unpeptized precipitate: put the sol into a closed container and settle for 1 hour on a centrifuge with a separation factor of 3600 to obtain Sol E;

iv) Heat sol E to boiling, continuously and slowly add solution B, keep the amount added equal to the amount of hydrolysis, stop adding after reaching the expected primary particle size, and keep boiling until the hydrolysis of zirconium ions in the solution is completed; during the heating process In the medium, the water evaporates continuously, and water needs to be replenished frequently to keep the volume of the solution constant;

v) The hydrolyzed product is washed with deionized water, filtered, and calcined at 800° C. for 5 hours to obtain granular zirconia. Grind the granular zirconia with water to a particle size of 0.2-0.3 μm with a ball mill, and spray dry to obtain a finished product.

Example 2

Follow the steps below in order:

i) Prepare zirconium oxychloride and yttrium chloride mixed solution and prepare ammonia solution according to the following ratio: 322 grams of zirconium oxychloride and 43 grams of yttrium chloride solution that can be converted to 6.4 grams of yttrium oxide are mixed and prepared into a concentration of 1.0M For solution B, dilute 14M ammonia water into 1.0M solution A, add solution A to solution B under constant stirring conditions, and produce zirconium hydroxide precipitation, stop when pH=7.0, and age for 12 hours;

ii) Wash the precipitate fully with deionized water until no white precipitate can be detected with silver nitrate, and obtain precipitate C; dissolve 966 grams of zirconium oxychloride in deionized water to obtain solution D; add precipitate C to solution D , add water until the concentration of zirconium ions reaches 1.0M, and heat to boiling under stirring conditions until all the precipitates are peptized;

iii) Centrifugal sedimentation to separate the unpeptized precipitate: put the sol into a closed container and settle for 1 hour on a centrifuge with a separation factor of 3600 to obtain Sol E;

iv) Heat sol E to boiling, continuously and slowly add solution B, keep the amount added equal to the amount of hydrolysis, stop adding after reaching the expected primary particle size, and keep boiling until the hydrolysis of zirconium ions in the solution is completed; during the heating process In the medium, the water evaporates continuously, and water needs to be replenished frequently to keep the volume of the solution constant;

v) The hydrolyzed product is washed with deionized water, filtered, and calcined at 800°C for 5 hours to obtain granular zirconia, which is ground with water in a ball mill until the particle size reaches 0.2-0.3 μm, and spray-dried to obtain a finished product;

After calcination, the XRD of the zirconia particles is shown in the attached figure, all of which are composed of tetragonal phases; the spray-dried powder is cold isostatically pressed at 200Mpa, sintered at 1500°C for 2 hours, and the detected density is 6.07.

Claims (4)

1. A method for preparing zirconia ultrafine powder, characterized in that: utilize the method of co-precipitation to make ammonia and zirconium oxychloride react in solution, and the precipitate produced is added in the zirconium oxychloride solution after washing and filtering Peptize the precipitate, use the sol as the crystallization core, continuously and slowly add zirconium oxychloride solution, heat to further hydrolyze the solution to produce precipitation, wash, calcinate, and grind the hydrolyzate to prepare a uniform particle size of nano Zirconia ultrafine powder. 2. the method for preparing zirconia ultrafine powder according to claim 1, is characterized in that: operate according to the following steps successively: i) Aqueous ammonia and zirconium oxychloride are prepared into homogeneous solutions A and B respectively, and solution B is added to solution A to make PH=7 to obtain precipitation of zirconium hydroxide; ii) fully washing and filtering the precipitate, adding it to the zirconium oxychloride solution, and heating to boiling to make them fully react and peptize; iii) separating the sol and the unpeptized precipitate by centrifugation to obtain a uniform zirconium hydroxide sol; iv) Use the sol as the seed crystal of the hydrolysis reaction, heat to 80-105°C, continuously and slowly add zirconium oxychloride solution to supplement the zirconium ions consumed by hydrolysis, and finally obtain zirconium hydroxide precipitation with uniform particle size and controllable size things, v) Washing, calcining, grinding, and spray drying the precipitate to obtain ultrafine nano zirconia powder. 3. the method for preparing zirconia ultrafine powder according to claim 1, is characterized in that: follow the following steps successively: i) Prepare zirconium oxychloride into solution B with a concentration of 1.0M, dilute 14M ammonia water into solution A of 1.0M, and add solution A to solution B under constant stirring conditions to produce precipitation of zirconium hydroxide. Stop at PH=7.0, aging for 12 hours; ii) Wash the precipitate fully with deionized water until no white precipitate can be detected with silver nitrate, and obtain precipitate C; dissolve zirconium oxychloride in deionized water to obtain solution D; add precipitate C to solution D, add water When the concentration of zirconium ions reaches 1.0M, heat to boiling under stirring conditions until all the precipitates are peptized; iii) Centrifugal sedimentation to separate the unpeptized precipitate: put the sol into a closed container and settle for 1 hour on a centrifuge with a separation factor of 3600 to obtain Sol E; iv) Heat sol E to boiling, continuously and slowly add solution B, keep the amount added equal to the amount of hydrolysis, stop adding after reaching the expected primary particle size, and keep boiling until the hydrolysis of zirconium ions in the solution is completed; during the heating process In the medium, the water evaporates continuously, and water needs to be replenished frequently to keep the volume of the solution constant; v) The hydrolyzed product is washed with deionized water, filtered, and calcined at 800° C. for 5 hours to obtain granular zirconia. Grind the granular zirconia with water to a particle size of 0.2-0.3 μm with a ball mill, and spray dry to obtain a finished product. 4. the method for preparing zirconia ultrafine powder according to claim 1, is characterized in that: operate according to the following steps successively: i) Prepare zirconium oxychloride and yttrium chloride mixed solution and prepare ammonia solution according to the following ratio: 322 grams of zirconium oxychloride and 43 grams of yttrium chloride solution that can be converted to 6.4 grams of yttrium oxide are mixed and prepared into a concentration of 1.0M For solution B, dilute 14M ammonia water into 1.0M solution A, add solution A to solution B under constant stirring conditions, and produce zirconium hydroxide precipitation, stop when pH=7.0, and age for 12 hours; ii) Wash the precipitate fully with deionized water until no white precipitate can be detected with silver nitrate, and obtain precipitate C; dissolve 966 grams of zirconium oxychloride in deionized water to obtain solution D; add precipitate C to solution D , add water until the concentration of zirconium ions reaches 1.0M, and heat to boiling under stirring conditions until all the precipitates are peptized; iii) Centrifugal sedimentation to separate the unpeptized precipitate: put the sol into a closed container and settle for 1 hour on a centrifuge with a separation factor of 3600 to obtain Sol E; iv) Heat sol E to boiling, continuously and slowly add solution B, keep the amount added equal to the amount of hydrolysis, stop adding after reaching the expected primary particle size, and keep boiling until the hydrolysis of zirconium ions in the solution is completed; during the heating process In the medium, the water evaporates continuously, and water needs to be replenished frequently to keep the volume of the solution constant; v) The hydrolyzed product is washed with deionized water, filtered, and calcined at 800°C for 5 hours to obtain granular zirconia, which is ground with water in a ball mill until the particle size reaches 0.2-0.3 μm, and spray-dried to obtain a finished product; After calcination, the zirconia particles are all composed of tetragonal phase; the spray-dried powder is cold isostatic pressed at 200Mpa, sintered at 1500°C for 2 hours, and the detected density is 6.07.