Cold-sintered zirconia ceramic and preparation method thereof

Abstract

The invention provides cold-sintered zirconia ceramic and a preparation method thereof. According to the preparation method of the cold-sintered zirconia ceramic, the cold-sintered zirconia ceramic is prepared on the basis of a biomimetic mineralization principle, and an amorphous ZrO2 precursor is introduced into ZrO2 powder and can be subjected to a controllable crystallization reaction at a low temperature, so that a superfine ZrO2 nanophase is formed in a grain boundary region; an acid environment generated in situ in a precursor generation process is utilized to excite the surface of ZrO2 crystal grains to generate unbalanced dissolution, and directional precipitation and structural healing of a crystal boundary region are realized under the action of high pressure; the relative density of the cold-sintered body is greater than or equal to 85% by accurately regulating and controlling the additive amount and sintering parameters of the precursor; and after annealing treatment, a three-dimensional interlocking nano-structure network is constructed at the grain boundary, and the average grain size of the final sample is controlled to be below 250 nm.

Description

Technical Field

[0001] The invention relates to the technical field of advanced ceramic material preparation, and in particular to a cold-sintered zirconia ceramic and a preparation method thereof. Background Art

[0002] The optimization of sintering process of zirconia ceramics is a long-standing technical problem in this field. 2 Due to the inherent low thermal conductivity (<2 W / m·K) and high sintering activation energy (typical value ≥500 kJ / mol) of the material, the traditional solid phase sintering process requires ultra-high temperature (>1450℃) and ultra-long sintering cycle (>48h) to achieve densification. Under such extreme sintering conditions, the following unfavorable phase changes will occur inside the material: 1) ZrO 2 Abnormal grain growth beyond critical size; 2) High temperature metastable phase to monoclinic m-ZrO 2 The irreversible transformation of the material leads to the degradation of the material performance. In the prior art, the sintering activity of the powder is improved by refining the grains. For example, the prior art discloses a hydrothermal method for preparing ultrafine ZrO 2 The technical solution for powders is to increase the specific surface area of ​​the powder (>30 m 2 / g) to improve the sintering activity and reduce the sintering temperature to 1250°C. However, this process has the disadvantages of complex powder preparation process (high pressure reactor equipment is required) and high cost (precursor utilization rate <70%).

[0003] Based on the defects in the current preparation of zirconia ceramics, it is necessary to improve it. Summary of the invention

[0004] The object of the present invention is to provide a cold-sintered zirconia ceramic and a preparation method thereof in view of the problems and shortcomings of the prior art.

[0005] The present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a cold-sintered zirconia ceramic, comprising the following steps:

[0007] adding a soluble zirconium salt into water to obtain a soluble zirconium salt solution;

[0008] adding a stabilizer to a soluble zirconium salt solution to obtain a first mixed solution;

[0009] Adding a precipitant to the first mixed solution and stirring to obtain a precursor;

[0010] Add Y to the precursor 2 O 3 Stable ZrO 2 The powder and the binder are dispersed to obtain a slurry;

[0011] The slurry is subjected to spray granulation to obtain granulated powder;

[0012] The granulated powder is placed in a cold sintering device and maintained at a pressure of 300-800 MPa for 10-60 minutes, and then heated to 180-450°C at a heating rate of 5-20°C / min and maintained for 30-180 minutes to obtain a cold sintered body;

[0013] The cold-sintered body is dried and then annealed to obtain a cold-sintered zirconia ceramic.

[0014] Preferably, the stabilizer includes at least one of a soluble yttrium salt, a soluble calcium salt, and a soluble magnesium salt.

[0015] Preferably, the soluble yttrium salt includes at least one of yttrium nitrate, yttrium chloride and yttrium sulfate;

[0016] The soluble calcium salt includes at least one of calcium chloride and calcium nitrate;

[0017] The soluble magnesium salt includes at least one of magnesium chloride, magnesium sulfate and magnesium nitrate.

[0018] Preferably, the soluble zirconium salt includes at least one of zirconium oxychloride and zirconium nitrate;

[0019] The precipitant includes oxalic acid or phosphoric acid, and the concentration of the precipitant is 0.8-1.0M.

[0020] Preferably, the binder includes polypropylene alcohol aqueous solution and acrylic emulsion;

[0021] The mass ratio of the polyacrylic alcohol aqueous solution to the acrylic emulsion is 1:1;

[0022] The concentration of the polyacryl alcohol aqueous solution is 10 wt %.

[0023] Preferably, in the step of adding a stabilizer to the soluble zirconium salt solution, the amount of the stabilizer added is 3 to 10 mol% of the zirconium salt based on the molar amount of the zirconium salt in the soluble zirconium salt solution; the concentration of the soluble zirconium salt solution is 1 to 2 M;

[0024] In the step of adding a precipitant to the first mixed solution, the volume ratio of the precipitant to the soluble zirconium salt solution is (220-700):250;

[0025] Add Y to the precursor 2 O 3 Stable ZrO 2 In the step of powder and binder, Y 2 O 3 Stable ZrO 2The mass of the powder is 25~45% of the mass of the precursor;

[0026] The mass of the binder added is Y 2 O 3 Stable ZrO 2 10~15% of the mass of the powder.

[0027] Preferably, the Y 2 O 3 Stable ZrO 2 Powder Y 2 O 3 The doping amount is 0.5~3mol%.

[0028] Preferably, the cold sintered body is dried at 150-200° C. for 10-15 hours.

[0029] Preferably, after the cold sintered body is dried, the temperature is increased to 700-1100° C. at a heating rate of 5-10° C. / min and annealed for 1-3 h.

[0030] In a second aspect, the present invention further provides a cold-sintered zirconia ceramic prepared by the preparation method.

[0031] The cold-sintered zirconia ceramic and the preparation method thereof of the present invention have the following beneficial effects compared with the prior art:

[0032] 1. The preparation method of cold-sintered zirconia ceramics of the present invention is based on the principle of bionic mineralization to prepare cold-sintered zirconia ceramics. The core of this scheme lies in: (1) the in-situ crystallization mechanism of the precursor. 2 Amorphous ZrO is introduced into the powder 2 Precursor, which can undergo a controlled crystallization reaction at low temperature (<400℃), thereby forming ultrafine ZrO 2 Nanophase (grain size <30 nm); acid-induced dissolution-precipitation mechanism. (2) Using the acidic environment generated in situ during the precursor generation process to stimulate ZrO 2 Non-equilibrium dissolution occurs on the surface of the grains, and directional precipitation and structural healing are achieved in the grain boundary region under high pressure; (3) Grain boundary nano-strengthening effect. By precisely controlling the amount of precursor added and the firing parameters, the relative density of the cold sintered body is ≥85%. After annealing, a three-dimensional interlocking nanostructure network is constructed at the grain boundary, and the average grain size of the final sample is controlled below 250 nm;

[0033] 2. The preparation method of the cold-sintered zirconia ceramics of the present invention can significantly reduce the sintering temperature; the cold-sintered zirconia ceramics prepared by the present invention have a relative density of 91-95%, a Vickers hardness of 10.8-13.5 Gpa, and an average grain size of 173.28-233.77 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 This is a schematic diagram of the preparation of cold-sintered zirconia ceramics based on the bionic mineralization principle of the present invention;

[0036] Figure 2 Based on the bionic mineralization principle of the present invention, ZrO 2 Schematic diagram of the gradual growth of grains at the grain boundary, causing the grain boundary to heal;

[0037] Figure 3 is a cross-sectional scanning electron microscope image of the cold-sintered zirconia ceramic prepared in Example 1;

[0038] Figure 4 The principle of preparing the cold-sintered zirconia ceramic in Example 1 based on the bionic mineralization principle of the present invention is further described;

[0039] Figure 5 is a cross-sectional scanning electron microscope image of the cold-sintered zirconia ceramic in Example 2 of the present invention;

[0040] Figure 6 is a cross-sectional scanning electron microscope image of the cold-sintered zirconia ceramic in Example 3 of the present invention;

[0041] Figure 7 This is a scanning electron microscope image of the cross section of the cold-sintered zirconia ceramic in Example 4 of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be understood that the directions or positions indicated by “upper” and the like are based on the directions or positions shown in the accompanying drawings, or are the directions or positions in which the product of the invention is usually placed when in use, or are directions or positions commonly understood by those skilled in the art. These directions or positions are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0044] The order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0045] The present invention provides a method for preparing a cold-sintered zirconia ceramic, comprising the following steps:

[0046] S1. adding a soluble zirconium salt into water to obtain a soluble zirconium salt solution;

[0047] S2, adding a stabilizer to the soluble zirconium salt solution to obtain a first mixed solution;

[0048] S3, adding a precipitant to the first mixed solution, stirring, to obtain a precursor;

[0049] S4. Add Y to the precursor 2 O 3 Stable ZrO 2 The powder and the binder are dispersed to obtain a slurry;

[0050] S5, spray granulating the slurry to obtain granulated powder;

[0051] S6, placing the granulated powder in a cold sintering device and maintaining the pressure at 300-800 MPa for 10-60 min, then heating to 180-450°C at a heating rate of 5-20°C / min, and maintaining the temperature for 30-180 min to obtain a cold sintered body;

[0052] S7, drying the cold sintered body and then annealing it to obtain a cold sintered zirconia ceramic.

[0053] According to current prior art reports, when preparing zirconia ceramics, the sintering temperature is reduced to 1250°C. However, in the actual process, due to the slow heating rate and high sintering temperature (even if it is reduced to 1250°C), the zirconia sintering cycle is too long, resulting in grain growth and performance degradation. The present invention cold-sinters the granulated powder. The benefits of cold sintering are: on the one hand, after cold sintering, the sample obtains a higher initial density. Therefore, during the subsequent annealing treatment, the heating rate is fast, the annealing temperature is low, and the holding time is short, which greatly shortens the entire sintering cycle. On the other hand, more importantly, the cold sintering temperature is low, and the grain size will not grow significantly, which is beneficial to the material performance.

[0054] In some embodiments, the stabilizer includes at least one of a soluble yttrium salt, a soluble calcium salt, and a soluble magnesium salt.

[0055] In some embodiments, the soluble yttrium salt includes at least one of yttrium nitrate, yttrium chloride, and yttrium sulfate;

[0056] In some embodiments, the soluble calcium salt includes at least one of calcium chloride and calcium nitrate;

[0057] In some embodiments, the soluble magnesium salt includes at least one of magnesium chloride, magnesium sulfate, and magnesium nitrate.

[0058] In some embodiments, the soluble zirconium salt includes at least one of zirconium oxychloride and zirconium nitrate;

[0059] In some embodiments, the precipitant includes oxalic acid or phosphoric acid, the precipitant is in the form of an aqueous solution, and the concentration of the precipitant is 0.8-1.0M.

[0060] In some embodiments, the binder includes an aqueous solution of polyacrylic alcohol and an acrylic emulsion;

[0061] The concentration of the polypropylene alcohol (ie, polypropylene glycol) aqueous solution is 10 wt%.

[0062] In some embodiments, the mass ratio of the polyacrylic alcohol aqueous solution to the acrylic emulsion is 1:1.

[0063] In some embodiments, in the step of adding a stabilizer to the soluble zirconium salt solution, the amount of the stabilizer added is 3 to 10 mol% of the zirconium salt based on the molar amount of the zirconium salt in the soluble zirconium salt solution; the concentration of the soluble zirconium salt solution is 1 to 2 M;

[0064] In the step of adding a precipitant to the first mixed solution, the volume ratio of the precipitant to the soluble zirconium salt solution is (220-700):250; Y is added to the precursor. 2 O3 Stable ZrO 2 In the step of powder and binder, Y 2 O 3 Stable ZrO 2 The mass of the powder is 25~45% of the mass of the precursor;

[0065] The mass of the binder added is Y 2 O 3 Stable ZrO 2 10~15% of the mass of the powder.

[0066] In some embodiments, when oxalic acid is used as a precipitant, the precursor is a hydrate of zirconium oxalate, calcium oxalate, or magnesium oxalate; when phosphoric acid is used as a precipitant, the precursor is a hydrate of zirconium phosphate, calcium phosphate, or magnesium phosphate.

[0067] In some embodiments, Y 2 O 3 Stable ZrO 2 Y in powder (3YSZ powder) 2 O 3 The doping amount is 0.5~3mol%.

[0068] In some embodiments, the cold sintered body is dried at 150-200° C. for 10-15 h.

[0069] In some embodiments, after the cold sintered body is dried, the temperature is increased to 700-1100° C. at a heating rate of 5-10° C. / min and annealed for 1-3 hours.

[0070] The method for preparing cold-sintered zirconia ceramics of the present invention is based on the principle of bionic mineralization to prepare cold-sintered zirconia ceramics. The core of this solution is:

[0071] (1) Precursor in-situ crystallization mechanism. 2 Amorphous ZrO is introduced into the powder 2 Precursor, which can undergo a controlled crystallization reaction at low temperature (<450℃), thereby forming ultrafine ZrO 2 nanophase (grain size <30 nm);

[0072] (2) Acid-induced dissolution-precipitation mechanism. The acidic environment generated in situ during the precursor generation process is used to stimulate the ZrO 2 Non-equilibrium dissolution occurs on the grain surface, and directional precipitation and structural healing are achieved in the grain boundary region under high pressure;

[0073] (3) Grain boundary nano-strengthening effect. By precisely controlling the amount of precursor added and the firing parameters, the relative density of the cold sintered body is ≥85%. After annealing, a three-dimensional interlocking nanostructure network is constructed at the grain boundary, and the average grain size of the final sample is controlled below 250 nm.

[0074] For further reference, Figure 1 As shown, it shows that the present invention prepares cold-sintered zirconia ceramics based on the bionic mineralization principle; specifically, ZrO 2 Powder (i.e. Y mentioned above) 2 O 3 Stable ZrO 2 The powder is mixed with the precursor and then spray granulated, and then enters the cold pressing and sintering stage; at this time, the granulated powder is pressed into shape in the mold and gradually heated under external pressure. The changes in the microstructure of this process are as follows: Figure 1~2 shown.

[0075] (1) The precursor is filled in ZrO 2 Between grains (grain boundaries);

[0076] (2) When the temperature rises, the precursor loses its crystal water, thus forming amorphous ZrO 2 (fine grain);

[0077] (3) Further increasing the temperature, the acidic environment generated in situ stimulates the amorphous ZrO 2 Non-equilibrium dissolution occurs on the (fine-grained) surface, and directional precipitation is achieved in the grain boundary region under high pressure;

[0078] (4) As the temperature continues to rise, the grains gradually grow at the grain boundaries, causing the grain boundaries to "heal" and the density of the material to gradually increase.

[0079] Specifically, under the condition of applied pressure, as the cold sintering temperature continues to increase, ZrO 2 The following reaction occurs between grains (grain boundaries): the precursor is heated to remove (crystallize) water → forming amorphous ZrO 2 (fine crystal) → acid-activated ZrO 2 Non-equilibrium dissolution occurs on the surface of fine grains → directional precipitation is achieved in the grain boundary area under high pressure → the grain boundary is "healed", the blank is initially densified and finally annealed, the density of the material can reach more than 90% of the theoretical density.

[0080] Based on the same inventive concept, the present invention also provides a cold-sintered zirconia ceramic, which is prepared by the above-mentioned preparation method.

[0081] The cold sintered zirconia ceramics and the preparation method thereof of the present application are further described below with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0082] In the following embodiments, Y 2 O 3 Stable ZrO 2 Y in powder (3YSZ powder) 2 O 3 The doping amount is 3 mol%, and 3YSZ powder is provided by Guangdong Oriental Zirconium Industry.

[0083] The acrylic emulsion in the following examples is Dow TX-100 acrylic emulsion, Dow Chemical.

[0084] Example 1

[0085] This embodiment provides a method for preparing a cold-sintered zirconia ceramic, comprising the following steps:

[0086] S1. Add zirconium oxychloride to water to obtain 250 mL of a 1 mol / L soluble zirconium salt solution;

[0087] S2. Add 1 mol / L yttrium nitrate solution (aqueous solution) to the soluble zirconium salt solution in S1 to obtain a first mixed solution; based on the molar amount of zirconium salt in the soluble zirconium salt solution, the amount of yttrium nitrate added as a stabilizer is 3 mol% of the zirconium salt (zirconium oxychloride);

[0088] S3, adding 700 mL of 0.8 mol / L oxalic acid solution as a precipitant to the first mixed solution to completely precipitate the metal ions in the first mixed solution, and continuously stirring to make the precipitation completely uniform, to obtain a precursor;

[0089] S4. Add Y to the precursor 2 O 3 Stable ZrO 2 powder, and a binder, and ball-milling dispersion to obtain a slurry; the binder includes a polypropylene alcohol aqueous solution and an acrylic emulsion, and the mass ratio of the polypropylene alcohol aqueous solution to the acrylic emulsion is 1:1; Y 2 O 3 Stable ZrO 2 Y in powder (3YSZ powder) 2 O 3 The doping amount is 3 mol%; the added Y 2 O 3 Stable ZrO 2The mass of the powder is 25wt% of the mass of the precursor; the mass of the added binder is Y 2 O 3 Stable ZrO 2 10wt% of the mass of the powder;

[0090] S5, spray granulating the slurry to obtain granulated powder;

[0091] S6, placing the granulated powder in a cold sintering device at 300 MPa for 30 minutes, then heating to 180° C. at a heating rate of 10° C. / min, and keeping the temperature for 180 minutes to obtain a cold sintered body;

[0092] S7. Dry the cold sintered body at 200° C. for 12 h, then heat it to 1100° C. at a heating rate of 5° C. / min, anneal it for 1 h, and cool it naturally to obtain a cold sintered zirconia ceramic.

[0093] Example 2

[0094] This embodiment provides a method for preparing a cold-sintered zirconia ceramic, comprising the following steps:

[0095] S1. Add zirconium oxychloride to water to obtain 250 mL of a 1 mol / L soluble zirconium salt solution;

[0096] S2. Add 1 mol / L yttrium nitrate solution (aqueous solution) to the soluble zirconium salt solution in S1 to obtain a first mixed solution; based on the molar amount of zirconium salt in the soluble zirconium salt solution, the amount of yttrium nitrate added as a stabilizer is 6 mol% of the zirconium salt (zirconium oxychloride);

[0097] S3, adding 220 mL of a 1 mol / L phosphoric acid solution as a precipitant to the first mixed solution to completely precipitate the metal ions in the first mixed solution, and continuously stirring to make the precipitation completely uniform, to obtain a precursor;

[0098] S4. Add Y to the precursor 2 O 3 Stable ZrO 2 powder, and a binder, and ball-milling dispersion to obtain a slurry; the binder includes a polypropylene alcohol aqueous solution and an acrylic emulsion, and the mass ratio of the polypropylene alcohol aqueous solution to the acrylic emulsion is 1:1; Y 2 O 3 Stable ZrO 2 Y in powder (3YSZ powder) 2 O 3 The doping amount is 3 mol%; the added Y 2 O 3 Stable ZrO 2 The mass of the powder is 30wt% of the mass of the precursor; the mass of the added binder is Y2 O 3 Stable ZrO 2 10wt% of the mass of the powder;

[0099] S5, spray granulating the slurry to obtain granulated powder;

[0100] S6, placing the granulated powder in a cold sintering device at 400 MPa for 30 minutes, then heating to 300° C. at a heating rate of 10° C. / min, and keeping the temperature for 120 minutes to obtain a cold sintered body;

[0101] S7. Dry the cold sintered body at 200° C. for 12 h, then heat it to 900° C. at a heating rate of 5° C. / min, anneal it for 3 h, and cool it naturally to obtain a cold sintered zirconia ceramic.

[0102] Example 3

[0103] This embodiment provides a method for preparing a cold-sintered zirconia ceramic, comprising the following steps:

[0104] S1. Add zirconium nitrate to water to obtain 250 mL of a 1 mol / L soluble zirconium salt solution;

[0105] S2. Add 1 mol / L calcium chloride solution (aqueous solution) to the soluble zirconium salt solution in S1 to obtain a first mixed solution; based on the molar amount of zirconium salt in the soluble zirconium salt solution, the amount of calcium chloride added as a stabilizer is 10 mol% of the zirconium salt (zirconium nitrate);

[0106] S3, adding 400 mL of 1 mol / L phosphoric acid solution as a precipitant to the first mixed solution to completely precipitate the metal ions in the first mixed solution, and continuously stirring to make the precipitation completely uniform, to obtain a precursor;

[0107] S4. Add Y to the precursor 2 O 3 Stable ZrO 2 powder, and a binder, and ball-milling dispersion to obtain a slurry; the binder includes a polypropylene alcohol aqueous solution and an acrylic emulsion, and the mass ratio of the polypropylene alcohol aqueous solution to the acrylic emulsion is 1:1; Y 2 O 3 Stable ZrO 2 Y in powder (3YSZ powder) 2 O 3 The doping amount is 3 mol%; the added Y 2 O 3 Stable ZrO 2 The mass of the powder is 45wt% of the mass of the precursor; the mass of the added binder is Y 2 O 3 Stable ZrO2 10wt% of the mass of the powder;

[0108] S5, spray granulating the slurry to obtain granulated powder;

[0109] S6, placing the granulated powder in a cold sintering device and maintaining the pressure at 800 MPa for 10 minutes, then heating to 450°C at a heating rate of 10°C / min, and maintaining the temperature for 120 minutes to obtain a cold sintered body;

[0110] S7. Dry the cold sintered body at 200° C. for 12 h, then heat it to 700° C. at a heating rate of 10° C. / min, anneal it for 3 h, and cool it naturally to obtain a cold sintered zirconia ceramic.

[0111] Example 4

[0112] This embodiment provides a method for preparing a cold-sintered zirconia ceramic, comprising the following steps:

[0113] S1. Add zirconium nitrate to water to obtain 250 mL of a 1 mol / L soluble zirconium salt solution;

[0114] S2. Add 1 mol / L magnesium nitrate solution (aqueous solution) to the soluble zirconium salt solution in S1 to obtain a first mixed solution; based on the molar amount of zirconium salt in the soluble zirconium salt solution, the amount of magnesium nitrate added as a stabilizer is 5 mol% of the zirconium salt (zirconium nitrate);

[0115] S3, adding 680 mL of 0.8 mol / L oxalic acid solution as a precipitant to the first mixed solution to completely precipitate the metal ions in the first mixed solution, and continuously stirring to make the precipitation completely uniform, to obtain a precursor;

[0116] S4. Add Y to the precursor 2 O 3 Stable ZrO 2 powder, and a binder, and ball-milling dispersion to obtain a slurry; the binder includes a polypropylene alcohol aqueous solution and an acrylic emulsion, and the mass ratio of the polypropylene alcohol aqueous solution to the acrylic emulsion is 1:1; Y 2 O 3 Stable ZrO 2 Y in powder (3YSZ powder) 2 O 3 The doping amount is 3 mol%; the added Y 2 O 3 Stable ZrO 2 The mass of the powder is 40wt% of the mass of the precursor; the mass of the added binder is Y 2 O 3 Stable ZrO 2 10wt% of the mass of the powder;

[0117] S5, spray granulating the slurry to obtain granulated powder;

[0118] S6, placing the granulated powder in a cold sintering device at 800 MPa for 60 minutes, then heating to 450°C at a heating rate of 10°C / min, and keeping the temperature for 30 minutes to obtain a cold sintered body;

[0119] S7. Dry the cold sintered body at 200° C. for 12 h, then heat it to 1000° C. at a heating rate of 5° C. / min, anneal it for 1 h, and cool it naturally to obtain a cold sintered zirconia ceramic.

[0120] Performance Testing

[0121] The relative density, Vickers hardness, and grain size of the cold-sintered zirconia ceramics prepared in Examples 1 to 4 are shown in Table 1 below. Relative density = measured density / theoretical density (6.08 g / cm 3 ) calculated; Vickers hardness (Hv): using indentation technology to make pyramid-shaped marks on the polished ceramic surface, Hv = 0.0018544 (P / d 2 ), where P = applied force, d = diagonal length of the indentation pyramid; grain size: read from SEM images.

[0122] Table 1 - Properties of cold sintered zirconia ceramics prepared in Examples 1 to 4

[0123] Example Relative density Vickers hardness Average grain size Example 1 92% 11.7Gpa 180.07nm Example 2 95% 13.5Gpa 173.28nm Example 3 91% 10.8Gpa 233.77nm Example 4 92% 12.6Gpa 215.96nm

[0124] Figure 3 This is a cross-sectional scanning electron microscope image of the cold-sintered zirconia ceramic prepared in Example 1 (the upper left corner is the particle size distribution statistics).

[0125] from Figure 3 It can be seen that the average grain size of the cold-sintered zirconia ceramic prepared in Example 1 is 180.07 nm.

[0126] Figure 4 The principle of preparing the cold-sintered zirconia ceramics in Example 1 based on the bionic mineralization principle of the present invention is further explained.

[0127] from Figure 4 It can be seen that the grain boundaries between the large zirconium oxide grains in Example 1 are filled with fine zirconium oxide grains. These fine grains come from the amorphous ZrO formed by dehydration of the precursor. 2 Non-equilibrium dissolution occurs on the surface and directional precipitation is formed in the grain boundary area under high pressure. This process gradually "heals" the grain boundary.

[0128] Figure 5This is a cross-sectional scanning electron microscope image of the cold-sintered zirconia ceramic in Example 2 of the present invention (the upper left corner is the particle size distribution statistics).

[0129] from Figure 5 It can be seen that the average grain size of the cold-sintered zirconia ceramic prepared in Example 2 is 173.28 nm.

[0130] Figure 6 This is a cross-sectional scanning electron microscope image of the cold-sintered zirconia ceramic in Example 3 of the present invention (the upper left corner is the particle size distribution statistics).

[0131] from Figure 6 It can be seen that the average grain size of the cold-sintered zirconia ceramic prepared in Example 3 is 233.77 nm.

[0132] Figure 7 This is a cross-sectional scanning electron microscope image of the cold-sintered zirconia ceramic in Example 4 of the present invention (the upper left corner is the particle size distribution statistics).

[0133] from Figure 7 It can be seen that the average grain size of the cold-sintered zirconia ceramic prepared in Example 3 is 215.96 nm.

[0134] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing cold-sintered zirconia ceramics, characterized in that: The following steps are involved: adding a soluble zirconium salt into water to obtain a soluble zirconium salt solution; adding a stabilizer to a soluble zirconium salt solution to obtain a first mixed solution; Adding a precipitant to the first mixed solution and stirring to obtain a precursor; Adding Y2O3-stabilized ZrO2 powder and a binder to the precursor, dispersing the mixture, and obtaining a slurry; The slurry is subjected to spray granulation to obtain granulated powder; The granulated powder is placed in a cold sintering device and maintained at a pressure of 300-800 MPa for 10-60 minutes, and then heated to 180-450°C at a heating rate of 5-20°C / min and maintained for 30-180 minutes to obtain a cold sintered body; The cold-sintered body is dried and then annealed to obtain a cold-sintered zirconia ceramic.

2. The method for preparing the cold-sintered zirconia ceramic according to claim 1, characterized in that: The stabilizer includes at least one of a soluble yttrium salt, a soluble calcium salt, and a soluble magnesium salt.

3. The method for preparing the cold-sintered zirconia ceramic according to claim 2, characterized in that: The soluble yttrium salt includes at least one of yttrium nitrate, yttrium chloride and yttrium sulfate; The soluble calcium salt includes at least one of calcium chloride and calcium nitrate; The soluble magnesium salt includes at least one of magnesium chloride, magnesium sulfate and magnesium nitrate.

4. The method for preparing the cold-sintered zirconia ceramic according to claim 1, characterized in that: The soluble zirconium salt includes at least one of zirconium oxychloride and zirconium nitrate; The precipitant includes oxalic acid or phosphoric acid, and the concentration of the precipitant is 0.8-1.0M.

5. The method for preparing the cold-sintered zirconia ceramic according to claim 1, characterized in that: The binder includes polypropylene alcohol aqueous solution and acrylic acid emulsion; The mass ratio of the polyacrylic alcohol aqueous solution to the acrylic emulsion is 1:1; The concentration of the polyacryl alcohol aqueous solution is 10 wt %.

6. The method for preparing the cold-sintered zirconia ceramic according to claim 1, characterized in that: In the step of adding a stabilizer to the soluble zirconium salt solution, the amount of the stabilizer added is 3 to 10 mol% of the zirconium salt based on the molar amount of the zirconium salt in the soluble zirconium salt solution; the concentration of the soluble zirconium salt solution is 1 to 2 M; In the step of adding a precipitant to the first mixed solution, the volume ratio of the precipitant to the soluble zirconium salt solution is (220-700):250; in the step of adding Y2O3-stabilized ZrO2 powder and a binder to the precursor, the mass of the added Y2O3-stabilized ZrO2 powder is 25-45% of the mass of the precursor; The mass of the added binder is 10~15% of the mass of the Y2O3 stabilized ZrO2 powder.

7. The method for preparing the cold-sintered zirconia ceramic according to claim 1, characterized in that: The Y2O3 doping amount in the Y2O3-stabilized ZrO2 powder is 0.5-3 mol%.

8. The method for preparing cold-sintered zirconia ceramics according to claim 1, characterized in that: Dry the cold sintered body at 150-200°C for 10-15h.

9. The method for preparing cold-sintered zirconia ceramics according to claim 1, characterized in that: After the cold sintered body is dried, the temperature is increased to 700-1100°C at a heating rate of 5-10°C / min and annealed for 1-3h.

10. A cold-sintered zirconia ceramic, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 9.

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