Zirconia/titanium oxide/cerium oxide doped rare earth tantalum/niobate RETa/NbO4 ceramic powder and preparation method thereof

Abstract

The present disclosure relates to the technical field of ceramic powder preparation, and discloses a zirconia/titania/cerium oxide doped rare earth tantalum/niobate RETa/NbO.sub.4 ceramic powder and a preparation method thereof. A general chemical formula of the ceramic powder is RE.sub.1-x(Ta/Nb).sub.1-x(Zr/Ce/Ti).sub.2xO.sub.4, 0<x<1, the crystal structure of the ceramic powder is orthorhombic, the lattice space group of the ceramic powder is C222.sub.1, the particle size of the ceramic powder ranges from 10 to 70 μm, and particles of the ceramic powder are spherical. During preparation, the raw materials are ball-milled before a high temperature solid phase reaction, then mixed with a solvent and an organic binder to obtain a slurry C, then centrifuged and atomized to obtain dry pellets, and finally sintered to obtain a zirconia/titanium oxide/cerium oxide doped rare earth tantalum/niobate RETa/NbO.sub.4 ceramic powder, which satisfies the requirements of APS technology for ceramic powders.

Claims

1. A ceramic powder comprising: a rare earth tantalate (RETaO.sub.4) or a rare earth niobate (RENbO.sub.4) doped with a dopant selected from one of zirconia, titanium oxide and cerium oxide; wherein, a general chemical formula of the ceramic powder is RE.sub.1-x(Ta or Nb).sub.1-x(Zr or Ce or Ti).sub.2xO.sub.4, wherein 0<x<1; the ceramic powder has an orthorhombic crystal structure, a lattice space group of C222.sub.1, and a particle size of from 10 to 70 and particles of the ceramic powder are spherical.

2. The ceramic powder according to claim 1, wherein RE represents one or more selected from Sc, Y, La, Nd, Sm, Eu, Gd, Dy, Er, Yb, and Lu.

3. A method for preparing the ceramic powder according to claim 1 comprising: operation (1): weighing a RE.sub.2O.sub.3 powder, a Ta.sub.2O.sub.5 powder or a Nb.sub.2O.sub.5 powder, and a dopant selected from one of ZrO.sub.2 powder, CeO.sub.2 powder and TiO.sub.2 powder with the molar ratio of RE:(Ta or Nb):(Zr or Ce or Ti) equal to (1-x):(1-x):2x, and adding the powders to a solvent to form a mixed solution, ball milling the mixed solution with a ball mill, and drying the mixed solution to obtain a dry powder A, with a ball milling time of 10 hours or more, and a ball milling speed of 300 rpm or more; operation (2): performing a high-temperature solid-phase reaction with the powder A obtained in operation (1) to obtain a powder B with a composition of RE.sub.1-x(Ta or Nb).sub.1-x(Zr or Ce or Ti).sub.2xO.sub.4, with a reaction temperature of from 1500 to 1800° C., and a reaction time of from 6 to 20 hours; operation (3): mixing the powder B obtained in operation (2) with a solvent and an organic binder to obtain a slurry C, and drying the slurry C by centrifuging and atomizing the slurry C at a temperature of 400-800° C. to obtain dry pellets D, wherein the mass percentage of the powder B in the slurry C ranges from 10% to 40%, the mass percentage of the organic binder in the slurry C ranges from 0.1% to 3%, the rest of the slurry C is solvent, and the speed of the centrifuging ranges from 8000 to 9000 rpm; and operation (4): sintering the pellets D obtained in operation (3) at a temperature of 800-1300° C. with a sintering time of from 7 to 9 h to obtain the ceramic powder.

4. The method according to claim 3, wherein adopting a rotary evaporator for the drying in operation (1), with a drying temperature of from 40 to 60° C., and a rotary evaporation time of from 2 to 4 hours.

5. The method according to claim 4, wherein the powder A obtained in the operation (1), the powder B obtained in operation (2), and the ceramic powder obtained in operation (4) are all sieved with a 200-500 mesh sieve.

6. The method according to claim 5, wherein in operation (3), the temperature for centrifuging and atomizing the slurry C is 600° C., and the speed of the centrifuging is 8500 rpm.

7. The method according to claim 6, wherein the RE.sub.2O.sub.3 powder, the Ta.sub.2O.sub.5 powder and the Nb.sub.2O.sub.5 powder in operation (1) are pre-dried before weighing, with a pre-drying temperature of from 400 to 700° C., and a drying time of from 5 to 8 hours.

8. The method according to claim 7, wherein the purity of the RE.sub.2O.sub.3 powder, the Ta.sub.2O.sub.5 powder and the Nb.sub.2O.sub.5 powder in operation (1) is not less than 99.9%.

9. The method according to claim 8, wherein in operation (3), the mass percentage of the powder B in the slurry C is 25%, and the mass percentage of the organic binder in the slurry C is 2%.

10. The method according to claim 9, wherein in operation (4), the sintering temperature is 1200° C., and the sintering time is 8 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an XRD diagram of zirconia doped rare earth tantalate (Sc.sub.0.8Ta.sub.0.8Zr.sub.0.4O.sub.4) prepared in Example 5 according to the present disclosure.

(2) FIG. 2 shows an SEM diagram of zirconia doped rare earth tantalate (Sc.sub.0.8Ta.sub.0.8Zr.sub.0.4O.sub.4) prepared in Example 5 according to the present disclosure.

DETAILED DESCRIPTION

(3) Some embodiments of the present disclosure will be described in further detail below.

(4) The present disclosure provides a zirconia/titanium oxide/cerium oxide doped rare earth tantalate/niobate RETa/NbO.sub.4 ceramic powder. A general chemical formula of the ceramic powder is RE.sub.1-x(Ta/Nb).sub.1-x(Zr/Ce/Ti).sub.2xO.sub.4, 0<x<1, with RE representing one or more of Sc, Y, La, Nd, Sm, Eu, Gd, Dy, Er, Yb, and Lu. The crystal structure of the ceramic powder is orthorhombic, the lattice space group of the ceramic powder is C222.sub.1, the particle size of the ceramic powder ranges from 10 to 70 μm, and particles of the ceramic powder are spherical.

(5) The applicant has conducted a large number of experiments on the zirconia/titanium oxide/cerium oxide doped rare earth tantalate/niobate RETa/NbO.sub.4 ceramic powder and the preparation method thereof of the present disclosure during the research process, and now 12 sets of experiments are used for illustration. Parameters of the zirconia/titanium oxide/cerium oxide doped rare earth tantalate/niobate RETa/NbO.sub.4 ceramic powder and the preparation method thereof in Examples 1-12 are shown in Table 1 and Table 2. Table 1 shows the specific parameters of Examples 1-6, and Table 2 shows the specific parameters of Examples 7-12.

(6) TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 x 0.2 0.2 0.2 0.4 0.4 0.4 Dopant (g) ZrO.sub.2 5.58 8.92 CeO.sub.2 5.84 20.77 TiO.sub.2 2.71 7.23 Rare earth Sc.sub.2O.sub.3 6.24 oxide (g) Y.sub.2O.sub.3 10.59 La.sub.2O.sub.3 11.50 11.50 Nd.sub.2O.sub.3 9.63 Sm.sub.2O.sub.3 15.79 Eu.sub.2O.sub.3 11.50 11.50 Gd.sub.2O.sub.3 Dy.sub.2O.sub.3 9.63 Er.sub.2O.sub.3 Yb.sub.2O.sub.3 Lu.sub.2O.sub.3 10.59 Ta.sub.2O.sub.5 (g) 20 12 12 10 14 10 Nb.sub.2O.sub.5 (g) Pre-drying Temperature 600 500 400 650 550 700 Time (h) 8 6 7 7 6 8 Ball Time (h) 10 10 10 10 11 11 milling Speed (r/min) 300 350 380 350 400 300 Rotary Temperature 60 40 50 50 40 60 evaporation Time (h) 2 2 3 4 3 3 Sieving Mesh 300 200 200 300 300 300 High-temperature Reaction temperature (° C.) 1700 1500 1600 1550 1650 1750 solid-phase Reaction time (h) 10 6 15 18 20 20 reaction Slurry C Powder B 10% 10% 20% 20% 20% 20% (mass percent) Organic Polyvinyl 0.1%  0.1%   1% adhesive alcohol Gum arabic 1.5%  1.5%  1.5%  Solvent Deionized 78.5%   78.5%   78.5%   water Ethanol 89.9 89.9 79% Drying by Temperature 600 400 500 550 650 700 centrifuging speed (r/min) 8500 8000 9000 8500 8000 9000 and atomizing Sintering Temperature 1200 800 900 1000 1100 1150 Time (h) 8 7 8 9 7 9

(7) TABLE-US-00002 TABLE 2 Example 7 8 9 10 11 12 x 0.6 0.6 0.6 0.8 0.8 0.8 Dopant (g) ZrO.sub.2 16.69 25.96 CeO.sub.2 38.85 20.72 TiO.sub.2 9.01 14.42 Rare earth Sc.sub.2O.sub.3 oxide (g) Y.sub.2O.sub.3 5.05 La.sub.2O.sub.3 Nd.sub.2O.sub.3 9.62 Sm.sub.2O.sub.3 Eu.sub.2O.sub.3 Gd.sub.2O.sub.3 8.58 Dy.sub.2O.sub.3 14.03 8.66 Er.sub.2O.sub.3 7.34 5.05 Yb.sub.2O.sub.3 9.62 8.66 Lu.sub.2O.sub.3 8.58 7.34 5.05 Ta.sub.2O.sub.5 (g) Nb.sub.2O.sub.5 (g) 3.5 4 3 1.5 1 1.1 Pre-drying Temperature 450 500 600 700 500 550 Time (h) 8 6 6 8 8 8 Ball Time (h) 11 11 12 12 12 12 milling Speed (r/min) 350 300 400 450 400 350 Rotary Temperature 50 40 60 50 40 60 evaporation Time (h) 3 4 2 4 2 4 Sieving Mesh 400 400 400 500 500 500 High-temperature Reaction 1800 1750 1600 1650 1700 1800 solid-phase temperature(° C.) reaction Reaction time (h) 6 15 6 15 20 10 Slurry C Powder B 30% 30% 30% 40% 40% 40% (mass percent) Organic Polyvinyl  2%  2% 2.5%  adhesive alcohol Gum 2.5%   3%  3% arabic Solvent Deionized 57.5%   57% 57% water Ethanol 68% 68% 67.5%   Drying by Temperature 750 700 800 600 500 800 centrifuging Speed (r/min) 8500 8000 8000 8500 8000 9000 and atomizing Sintering Temperature 1200 1050 1000 1100 900 1300 Time (h) 9 8 8 7 8 9

(8) Taking Example 1 as an example, the method for preparing the zirconia/titanium oxide/cerium oxide doped rare earth tantalate/niobate RETa/NbO.sub.4 ceramic powder of the present disclosure is described below.

(9) The method for preparing the zirconia (ZrO.sub.2) doped rare earth tantalate (RETaO.sub.4) ceramic powder (Sc.sub.0.8Ta.sub.0.8Zr.sub.0.4O.sub.4) includes the following operations:

(10) Operation (1):

(11) The zirconia (ZrO.sub.2) powder, the rare earth oxide powder Sc.sub.2O.sub.3, and the tantalate pentoxide (Ta.sub.2O.sub.5) powder were pre-dried. The pre-drying temperature was 600° C. and the pre-drying time was 8 hours. 5.58 g of zirconium oxide (ZrO.sub.2) powder, 6.24 g of rare earth oxide powder Sc.sub.2O.sub.3, and 20 g of tantalate oxide (Ta.sub.2O.sub.5) powder were weighed and added into the ethanol solvent to obtain a mixed solution, such that the molar ratio Sc:Ta:Zr in the mixed solution was 2:2:1. The mixed solution was ball milled with a ball mill for 10 hours, and the speed of the ball mill was 300 r/min.

(12) The slurry obtained after ball milling was dried using a rotary evaporator (model: N-1200B), the drying temperature was 60° C., and the drying time was 2 hours. The dried powder was sieved through a 300-mesh sieve to obtain powder A.

(13) Operation (2):

(14) A high-temperature solid-phase reaction was performed on the powder A obtained in operation (1) to prepare powder B with a composition of ZrO.sub.2 doped with ScTaO.sub.4, the reaction temperature was 1700° C., and the reaction time was 10 h. A 300-mesh sieve was adopted to sieve the powder B.

(15) Operation (3):

(16) The powder B sieved in operation (2) was mixed with a deionized water solvent and an organic binder to obtain slurry C, where the mass percentage of powder B in slurry C was 25%, and the mass percentage of the organic binder in the slurry C was 2%, the rest of the slurry C was solvent. The organic adhesive may be polyvinyl alcohol or gum arabic, and in this embodiment, polyvinyl alcohol was adopted. Then, the slurry C was dried by centrifuging and atomizing, the temperature during drying was 600° C., the centrifugal speed was 8500 r/min, and dried pellets D were obtained.

(17) Operation (4):

(18) The pellets D obtained in operation (3) were sintered at a temperature of 1200° C. for 8 hours, and then the sintered pellets D were sieved with a 300-mesh sieve to obtain zirconia (ZrO.sub.2) with a particle size of 10 to 70 nm and a doped ScTaO.sub.4 ceramic powder (Sc.sub.0.8Ta.sub.0.8Zr.sub.0.4O.sub.4) comprising spherical particles.

(19) Examples 2-6 only differ from Example 1 in the parameters and the final products.

(20) XRD characterization and SEM characterization were performed in Examples 1-12. Taking Example 1 as an example, the characterization of the obtained zirconia doped rare earth tantalate ceramic powder (Sc.sub.0.8Ta.sub.0.8Zr.sub.0.4O.sub.4) is described:

(21) 1 XRD characterization:

(22) The X-ray diffraction pattern is shown in FIG. 1. It can be seen from FIG. that the zirconia doped rare earth tantalate ceramic powder (Sc.sub.0.8Ta.sub.0.8Zr.sub.0.4O.sub.4) obtained in Example 1 is orthorhombic with no impurity phase, and the lattice space group of the ceramic powder is C222.sub.1. The zirconia/titanium oxide/cerium oxide doped rare earth tantalate/niobate RETa/NbO.sub.4 ceramic powders obtained in Examples 2-12 are also orthorhombic with no impurity phases, and the lattice space group of the ceramic powders is C222.sub.1.

(23) SEM characterization:

(24) The SEM spectrum of the zirconia doped rare earth tantalate ceramic powder (Sc.sub.0.8Ta.sub.0.8Zr.sub.0.4O.sub.4) prepared in Example 1 is shown in FIG. 2. It can be seen from FIG. 2 that the particle sizes of the powder range from 10 to 70 μm, and the particles are spherical. The particle sizes of the zirconia/titanium oxide/cerium oxide doped rare earth tantalate/niobate RETa/NbO.sub.4 ceramic powders obtained in Examples 2-12 range from 10 to 70 μm, and the particles are spherical.

(25) Three groups of comparative examples are listed and compared with the ceramic powders obtained in Examples 1-12:

(26) Comparative Example 1: different from Example 1 in that the drying here is not performed by centrifuging and atomizing, the drying temperature is 800° C., the drying time is 1.5 h, the final powder has a particle size of 180 μm-220 μm, and the particles have an irregular shape.

(27) Comparative Example 2: different from Example 1 in that the ball milling time here is 7 hours, and the average particle size of the finally obtained powder is greater than 200 μm.

(28) Comparative Example 3: different from Example 1 in that after sintering, the sieving process is not performed, and the finally obtained powder contains lumps with a particle size greater than 220 μm.

(29) In summary, the zirconia/titanium oxide/cerium oxide doped rare earth tantalate/niobate RETa/NbO.sub.4 ceramic powders prepared in examples 1-12 have a particle size of 10-70 μm and the particles are spherical, which conforms to the requirements of APS technology for powders, and ceramic powders that meet the requirements of APS technology are not obtained in Comparative Examples 1-3.

(30) While particular elements, embodiments, and applications of the present invention have been shown and described, it is understood that the invention is not limited thereto because modifications may be made by those skilled in the art, particularly in light of the foregoing teaching. It is therefore contemplated by the appended claims to cover such modifications and incorporate those features which come within the spirit and scope of the invention.

(31) For those skilled in the art, several modifications and improvements can be made without departing from the principle of the technical solution of the present disclosure. These should also be regarded as the protection scope of the present disclosure, and these will not affect the effect of the implementation and unity of the present disclosure.