Spherical yttria-stabilized zirconia powder as well as preparation method and application thereof

Abstract

The invention discloses spherical yttria-stabilized zirconia powder as well as a preparation method and application thereof. The yttria-stabilized zirconia powder is spherical particles, and the sphericity degree is greater than or equal to 95%; the particle size distribution is 10-90 [mu] m, and the nano-crystalline grain size is uniform and is 20-80 nm; the compressive strength is greater than or equal to 50MPa; the thermal conductivity is less than or equal to 1.5 W / m.K; in terms of Y2O3, the content of yttrium oxide is 5%-8%; the powder is high in sphericity degree, uniform in nanostructure, excellent in compressive property and low in thermal conductivity. A preparation method of the invention; the method can realize the optimization of the sphericity, microstructure and performance of the powder, meets the requirements of the thermal spraying industry on high-performance ceramic powder, and has the advantages of simple process, low cost, high efficiency and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of powder materials and thermal spraying technology. More particularly, it relates to a spherical yttria-stabilized zirconia powder, a preparation method and applications thereof. BACKGROUND

[0002] As a protective technology that coats the surface of the substrate with a ceramic material with high temperature resistance, low thermal conductivity and high corrosion resistance in the form of a coating, thermal barrier coating technology plays a key role in high-temperature fields such as aerospace. Among them, thermal spraying technology has become one of the core technologies of aerospace engine research and production manufacturing due to its relatively low research and development cost, easy-to-implement process, and effective improvement of the overall service life of the engine.

[0003] In recent years, with the continuous improvement of the thrust-to-weight ratio of the aero-engine, the temperature of the combustion chamber inlet has risen sharply. For example, the temperature of the combustion chamber inlet of an engine with a thrust-to-weight ratio of 10 is about 1900K, and the temperature of an engine with a thrust-to-weight ratio of 12-15 can reach 2100K, and when the thrust-to-weight ratio reaches 20, the temperature will be as high as 2200-2400K. Such a harsh high-temperature environment puts higher requirements on the thermal conductivity, thermal stability and comprehensive mechanical properties of thermal barrier coating materials.

[0004] The existing thermal barrier coating materials (such as yttria-stabilized zirconia powder prepared by traditional process) have problems such as high thermal conductivity, limited compressive strength, etc. due to insufficient sphericity and poor uniformity of nanostructure, which makes it difficult to meet the service requirements of the new generation of aero-engine.

[0005] Zirconia-based materials are one of the most mature thermal barrier coating materials currently in use, and usually require the introduction of rare earth elements such as yttria as a high-temperature phase change stabilizer to optimize performance. However, traditional preparation processes (such as ordinary co-precipitation, mechanical granulation, etc.) cannot achieve precise control of the microstructure of the powder, and the sphericity, particle size distribution and grain uniformity all need to be improved, which in turn restricts the service performance of the coating in high-temperature environments. Therefore, developing a process that can prepare a yttria-stabilized zirconia powder with high sphericity, uniform nanostructure and excellent compressive performance and low thermal conductivity is a key to breaking through the bottleneck of existing thermal barrier coating technology. SUMMARY

[0006] The first technical problem to be solved by the present application is to provide a spherical yttria-stabilized zirconia powder for thermal spraying. The powder has high sphericity, uniform nanostructure and excellent compressive performance and low thermal conductivity.

[0007] The second technical problem to be solved by the present application is to provide a preparation method of a spherical yttria-stabilized zirconia powder for thermal spraying.

[0008] The third technical problem to be solved by the present application is to provide an application of the spherical yttria-stabilized zirconia powder in thermal spraying for preparing a thermal barrier coating.

[0009] To solve the first technical problem, the present application adopts the technical solutions as follows

[0010] A spherical yttria-stabilized zirconia powder for thermal spraying, wherein the yttria-stabilized zirconia powder is a spherical particle with a sphericity of greater than or equal to 95%; the particle size distribution is 10-90 μm, the nanocrystalline grain size is uniform and is 20-80 nm; the compressive strength is greater than or equal to 50 MPa; the thermal conductivity is less than or equal to 1.5 W / (m·K); and the yttria content is 5%-8% as calculated based on Y2O3.

[0011] Preferably, the bulk density of the yttria-stabilized zirconia powder is 1.5-2.5 g / cm 3 , the tap density is 2.0-3.0 g / cm 3 , and the Hall flow rate is less than or equal to 60 s / 50 g, thereby meeting the flowability standard of the powder for thermal spraying.

[0012] To solve the second technical problem, the present application adopts the technical solutions as follows

[0013] A preparation method of a spherical yttria-stabilized zirconia powder for thermal spraying, comprising the following steps:

[0014] 1) Preparing yttria-stabilized zirconia by supergravity co-precipitation combined with a hydrothermal method:

[0015] Mixing a zirconium salt solution and a yttrium salt solution, adding a precipitant in a supergravity reactor to perform a co-precipitation reaction, obtaining a precursor precipitate, and then drying after a hydrothermal reaction to prepare a yttria-stabilized zirconia powder;

[0016] 2) Preparing a slurry:

[0017] Mixing the yttria-stabilized zirconia powder obtained in step 1) with a solvent to prepare a slurry with a solid content of 20%-60%;

[0018] 3) Spray drying into a ball:

[0019] Atomizing and drying the slurry through a spray drying device to form spherical precursor particles;​​

[0020] 4) high-temperature calcination treatment:

[0021] The spheroidized precursor particles are calcined to complete the glue removal and improve the powder bonding strength, thereby obtaining the spherical yttria-stabilized zirconia powder.

[0022] Preferably, in step 1), the rotor rotation speed of the supergravity reactor is 500-3000 r / min.

[0023] Preferably, in step 1), the zirconium salt is selected from one or more of zirconium nitrate, zirconium oxychloride, and zirconium sulfate; the yttrium salt is selected from one or more of yttrium nitrate, yttrium chloride, and yttrium sulfate; and the molar ratio of the zirconium salt to the yttrium salt is (7-15):1 (calculated based on ZrO2:Y2O3, respectively).

[0024] Preferably, in step 1), the precipitating agent is one or more of ammonia, sodium hydroxide, and ammonium bicarbonate. The amount of the precipitating agent added is in a molar ratio of (1.1-2.0):1 to the total metal ions of the zirconium salt and the yttrium salt.

[0025] Preferably, in step 1), the temperature of the hydrothermal reaction is 180-220℃, and the time is 3-12 hours; and the drying temperature is 50-100℃, and the drying time is 12-24 hours.

[0026] Preferably, in step 2), the solvent is deionized water or ethanol.

[0027] Preferably, in step 2), 0.1%-2% of a dispersing agent is added to the slurry.

[0028] Preferably, the dispersing agent is one or both of polyvinyl alcohol and ammonium polyacrylate.

[0029] Preferably, in step 3), the inlet air temperature of the spray drying is 180-300℃, the frequency of the atomizer is 15000-35000 rpm, and the particle size of the obtained spherical precursor particles is 10-90 μm.

[0030] Preferably, in step 4), the calcination temperature is 300-1100℃, and the calcination time is 2-6 hours.

[0031] To solve the third technical problem, the present application adopts the technical solutions as follows :

[0032] Use of a spherical yttria-stabilized zirconia powder in thermal spraying to prepare a thermal barrier coating,

[0033] The thermal barrier coating prepared by thermal spraying of the spherical yttria-stabilized zirconia powder has an improved thermal shock resistance of ≧29% at a high-temperature environment above 1200℃, and a service life that is improved by more than 40% compared to a traditional coating.

[0034] Any range recited in the present invention includes the end values and any intervening values and any sub-range comprised of any such values.

[0035] Unless otherwise specified, each raw material in the present invention can be obtained by commercial purchase, and the equipment used in the present invention can adopt the conventional equipment in the field or refer to the prior art in the field.

[0036] Compared with the prior art, the present application has the following beneficial effects

[0037] 1) The present invention uses supergravity co-precipitation combined with hydrothermal method, uses the strong shear force of supergravity field to realize atomic-level uniform mixing of zirconium and yttrium ions, and promotes uniform grain growth through hydrothermal reaction, so that the prepared yttria-stabilized zilconia powder has uniform nano structure, and the thermal stability and compression resistance of the powder are improved from the source.

[0038] 2) The spray drying process adopted in the present invention gives the powder high sphericity (≥95%) and ideal particle size distribution, reduces powder agglomeration in the thermal spraying process, and improves coating deposition efficiency; the high-temperature calcination in the final stage effectively removes glue and enhances particle bonding strength, reduces coating porosity, and makes the thermal conductivity as low as ≤1.5 W / (m·K), so that the heat insulation performance is significantly better than that of traditional powder.

[0039] 3) The preparation process parameters of the present invention have strong controllability, the supergravity co-precipitation reaction efficiency is increased by 30%-50% compared with the traditional stirring process, the spray drying and calcination process is highly continuous, no complex equipment is needed, the preparation cost is reduced by 20%-30%, and the present invention is suitable for large-scale production.

[0040] 4) The yttria-stabilized zirconia powder prepared by the present invention has excellent flowability (Hall flow rate ≤60 s / 50 g), and can be directly adapted to plasma spraying, supersonic flame spraying and other processes; the thermal barrier coating prepared has strong thermal shock resistance in a high-temperature environment above 1200℃, and the service life is increased by more than 40% compared with traditional coatings.

[0041] 5) The preparation process of the present invention has wide compatibility, which is not only suitable for yttria-stabilized zirconia system, but also can be extended to other rare earth element (such as ceria, samaria oxide) stabilized ceramic powder, and provides a universal technical solution for spherical ceramic powder preparation. BRIEF DESCRIPTION OF DRAWINGS

[0042] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings

[0043] Figure 1 is the scanning electron microscope image of the spherical yttria-stabilized zirconia powder for thermal spraying obtained in Example 1 of the present invention;

[0044] ​Figure 2 is a scanning electron microscope partial pattern of the thermal spraying spherical yttria-stabilized zirconia powder obtained in Example 1 of the present application;

[0045] Figure 3 is a scanning electron microscope pattern of the thermal spraying spherical yttria-stabilized zirconia powder obtained in Examples 2-4 of the present application;

[0046] Figure 4 is an X-ray diffraction pattern of the thermal spraying spherical yttria-stabilized zirconia powder obtained in Example 1 of the present application;

[0047] Figure 5 is a thermal conductivity comparison pattern of the thermal spraying spherical yttria-stabilized zirconia powder obtained in Example 2 of the present application and a commercial powder;

[0048] Figure 6 is a bonding strength comparison pattern of the thermal spraying spherical yttria-stabilized zirconia powder obtained in Example 1 of the present application and a commercial powder (left is the self-made powder coating, right is the commercial powder coating);

[0049] Figure 7 is a scanning electron microscope pattern and a particle size distribution pattern of the nano yttria-stabilized zirconia obtained in Comparative Example 1 of the present application compared with Example 1;

[0050] Figure 8 is an X-ray diffraction pattern of the nano yttria-stabilized zirconia obtained in Comparative Example 2 of the present application compared with Example 1;

[0051] Figure 9 is a scanning electron microscope pattern of the thermal spraying spherical yttria-stabilized zirconia powder obtained in Comparative Example 3 of the present application. DETAILED DESCRIPTION

[0052] In order to more clearly illustrate the present application, the present application will be further described below with reference to the preferred embodiments and the accompanying drawings. Like components are denoted by the same reference numerals in the drawings. Those skilled in the art should understand that the specific descriptions below are illustrative rather than limiting, and the protection scope of the present application should not be limited thereby.

[0053] For the convenience of description, the description involving "first", "second" and the like in the present application is only set for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions among various embodiments can be combined with each other, but it must be based on that the combination of the technical solutions can be realized by the ordinary skilled in the art, and when the combination of the technical solutions appears contradictory or unachievable, it should be considered that the combination of the technical solutions does not exist and is not within the protection scope required by the present application.

[0054] As one aspect of the present application, the present application provides a spherical yttria-stabilized zirconia powder for thermal spraying, wherein the yttria-stabilized zirconia powder is spherical particles with a sphericity of ≥ 95%; the particle size distribution is 10-90 μm, the nanocrystalline grain size is uniform, and is 20-80 nm; the compressive strength is ≥ 50 MPa; the thermal conductivity is ≤ 1.5 W / (m·K); and the yttria content, calculated as Y2O3, is 5%-8%.

[0055] In some embodiments of the present application, the bulk density of the yttria-stabilized zirconia powder is 1.5-2.5 g / cm 3 , the tap density is 2.0-3.0 g / cm 3 , and the Hall flow rate is ≤ 60 s / 50 g, satisfying the flowability standard of the powder for thermal spraying.

[0056] As another aspect of the present application, the present application provides a preparation method of a spherical yttria-stabilized zirconia powder for thermal spraying, comprising the following steps:

[0057] 1) Preparation of yttria-stabilized zirconia by supergravity co-precipitation combined with hydrothermal method:

[0058] Mixing the zirconium salt solution and the yttrium salt solution, adding a precipitant in a supergravity reactor to perform a co-precipitation reaction, obtaining a precursor precipitate, and then drying after hydrothermal reaction to prepare the yttria-stabilized zirconia powder;

[0059] 2) Preparation of slurry:

[0060] Mixing the yttria-stabilized zirconia powder obtained in step 1) with a solvent to prepare a slurry with a solid content of 20%-60%;

[0061] 3) Spray drying into spheres:

[0062] Atomizing and drying the slurry by a spray drying device to form spherical precursor particles;

[0063] 4) High-temperature calcination treatment:

[0064] The spherical yttria-stabilized zirconia powder is prepared by calcining the spherical precursor particles to complete the degassing and improve the powder bonding strength.

[0065] In some embodiments of the present application, in step 1), the rotation speed of the rotor of the high gravity reactor is 500-3000 r / min.

[0066] In some embodiments of the present application, in step 1), the zirconium salt is selected from one or more of zirconium nitrate, zirconium oxychloride and zirconium sulfate; the yttrium salt is selected from one or more of yttrium nitrate, yttrium chloride and yttrium sulfate; and the molar ratio of the zirconium salt to the yttrium salt is (7-15):1 (calculated based on ZrO2:Y2O3, respectively).

[0067] In some embodiments of the present application, in step 1), the precipitating agent is one or more of ammonia, sodium hydroxide and ammonium bicarbonate; and the molar ratio of the precipitating agent to the total metal ions of the zirconium salt and the yttrium salt is (1.1-2.0):1.

[0068] In some embodiments of the present application, in step 1), the temperature of the hydrothermal reaction is 180-220℃, and the time is 3-12 hours; and the drying temperature is 50-100℃, and the drying time is 12-24 hours.

[0069] In some embodiments of the present application, in step 2), the solvent is deionized water or ethanol.

[0070] In some embodiments of the present application, in step 2), 0.1%-2% of a dispersing agent is added to the slurry.

[0071] In some embodiments of the present application, the dispersing agent is one or both of polyvinyl alcohol and ammonium polyacrylate.

[0072] In some embodiments of the present application, in step 3), the inlet air temperature of the spray drying is 180-300℃, the frequency of the atomizer is 15000-35000 rpm, and the particle size of the obtained spherical precursor particles is 10-90 μm.

[0073] In some embodiments of the present application, in step 4), the calcination temperature is 300-1100℃, and the calcination time is 2-6 hours.

[0074] As another aspect of the present application, the present application provides a use of the spherical yttria-stabilized zirconia powder in thermal spraying to prepare a thermal barrier coating,

[0075] The thermal barrier coating prepared by thermal spraying of the spherical yttria-stabilized zirconia powder has an increased thermal shock resistance of ≧29% and a service life increased by more than 40% compared with a conventional coating in a high-temperature environment above 1200℃.

[0076] Example 1

[0077] A preparation method of yttria-stabilized zirconia powder, comprising the following steps:

[0078] 1) Preparation of yttria-stabilized zirconia by high gravity co-precipitation combined with hydrothermal method:

[0079] Zirconium chloride (ZrOCl2·8H2O) and yttrium nitrate (Y(NO3)3·6H2O) were dissolved in deionized water at a molar ratio of 10:1 (calculated as ZrO2:Y2O3) to prepare a mixed solution with a total metal ion concentration of 0.5 mol / L; 2 mol / L ammonia was used as a precipitant and added into the high gravity reactor at the same time as the mixed solution, and the system pH was adjusted to 9.0, and the mixture was stirred for 1 h in a high gravity field at a rotation speed of 1500 r / min to obtain a precursor precipitate; the precipitate was transferred to a hydrothermal reactor, deionized water was added to a solid-liquid ratio of 1:10, and a hydrothermal reaction was carried out at 200℃ for 6 h; after the reaction, the precipitate was filtered, washed, and dried at 60℃ for 12 h to obtain yttria-stabilized zirconia powder;

[0080] 2) Preparation of slurry:

[0081] The powder obtained in step 1) was mixed with deionized water, and 1% of ammonium polyacrylate by mass of the powder was added as a dispersant to prepare a slurry with a solid content of 40% after uniform stirring;

[0082] 3) Spray drying into spheres:

[0083] The slurry was introduced into a spray drying device, the inlet air temperature was controlled at 220℃, and the atomization frequency was 30000 rpm for atomization drying, and the spherical precursor particles with a particle size distribution of 20-90 μm were obtained by sieving;

[0084] 4) High-temperature calcination treatment:

[0085] The spherical precursor particles were placed in a muffle furnace and heated to 900℃ at a heating rate of 5℃ / min, and the powder was calcined for 4 h to complete the glue removal and improve the powder bonding strength, thereby obtaining spherical yttria-stabilized zirconia powder.

[0086] Figure 1 is a scanning electron microscope image of the spherical yttria-stabilized zirconia powder obtained in Example 1;

[0087] Figure 2 is a local scanning electron microscope image of the spherical yttria-stabilized zirconia powder obtained in Example 1;

[0088] Figure 4 is an X-ray diffraction pattern of the spherical yttria-stabilized zirconia powder obtained in Example 1;

[0089] Figure 6 Figure 1 is a graph showing the bonding strength of the spherical yttria-stabilized zirconia powder obtained in Example 1 combined with a commercially available powder (left is the self-made powder coating, and right is the commercially available powder coating).

[0090] The product powder prepared in this example 1 was subjected to performance test, and the results are shown in Tables 1-3 below

[0091] Table 1 is the powder properties of the spherical yttria-stabilized zirconia powder obtained in Example 1 actually tested;

[0092] Table 2 is a comparison test table of the microhardness of the spherical yttria-stabilized zirconia powder obtained in Example 1 actually tested and the commercially available powder thermal spraying test piece. The "commercially available powder" described in the present application is nano-sized 5Y yttria-stabilized zirconia or nano-sized 8Y yttria-stabilized zirconia, for example, made by Jiangsu Yuan Te Company.

[0093] Table 3 is a comparison test table of the thermal spraying test piece thermal shock cycle times at 1200°C of the spherical yttria-stabilized zirconia powder obtained in Example 1 actually tested and the commercially available powder thermal spraying test piece.

[0094] Table 1:

[0095]

[0096]

[0097] Table 2:

[0098]

[0099] Table 3:

[0100]

[0101] Example 2

[0102] A spherical yttria-stabilized zirconia powder for thermal spraying and a preparation method thereof, the steps of which are as follows:

[0103] 1) Preparation of yttria-stabilized zirconia by supergravity co-precipitation combined with hydrothermal method: the molar ratio of zirconium salt to yttrium salt is 9:1, the rotation speed of the supergravity reactor is 500 r / min, the precipitating agent is 1.5 mol / L sodium hydroxide solution, and the pH is adjusted to 8.5; the hydrothermal reaction temperature is 180°C, the incubation time is 12h; the drying temperature is 80°C, and the drying time is 24h (the rest is the same as step 1 of Example 1);

[0104] 2) Preparation of slurry: the solvent is water, the solid content is 20%, and the dispersing agent is polyvinyl alcohol (the addition amount is 0.1% of the mass of the powder) (the rest is the same as step 2 of Example 1);

[0105] ​3) Spray drying into spheres: inlet temperature 180°C, atomizer frequency 20 000 rpm, spherical precursor particles with a particle size of 10-50 μm were obtained (the rest as in step 3) of example 1);

[0106] 4) High temperature calcination: calcination temperature 800°C, holding time 6 h (the rest as in step 4) of example 1).

[0107] Figure 3 a is a scanning electron microscope image of the spherical yttria-stabilized zirconia powder obtained in example 2.

[0108] Figure 5 is a comparison of the thermal conductivity of the spherical yttria-stabilized zirconia powder obtained in example 2 and a commercial powder.

[0109] The spherical yttria-stabilized zirconia powder obtained in this example has properties close to those of example 1.

[0110] Example 3

[0111] A method for producing a spherical yttria-stabilized zirconia powder for thermal spraying, comprising the following steps:

[0112] 1) Preparation of yttria-stabilized zirconia by high gravity co-precipitation combined with hydrothermal method: molar ratio of zirconium salt to yttrium salt 11:1, rotation speed of high gravity reactor 3000 r / min, precipitant 2.5 mol / L ammonium bicarbonate solution, pH adjusted to 10.0; hydrothermal reaction temperature 200°C, holding time 6 h; drying temperature 50°C, holding time 12 h (the rest as in step 1) of example 1).

[0113] 2) Preparation of slurry: solvent deionized water, solid content 60%, dispersant polyacrylammonium (added amount 2% of the mass of the powder) (the rest as in step 2) of example 1).

[0114] 3) Spray drying into spheres: inlet temperature 300°C, atomizer frequency 25 000 rpm, spherical precursor particles with a particle size of 30-90 μm were obtained (the rest as in step 3) of example 1).

[0115] 4) High temperature calcination: calcination temperature 1100°C, holding time 2 h (the rest as in step 4) of example 1).

[0116] Figure 3 b is a scanning electron microscope image of the spherical yttria-stabilized zirconia powder obtained in example 3.

[0117] The spherical yttria-stabilized zirconia powder obtained in this example has properties close to those of example 1.

[0118] Example 4

[0119] A spherical yttria-stabilized zirconia powder for thermal spraying and a preparation method thereof, steps as follows:

[0120] 1) Preparation of yttria-stabilized zirconia by high gravity co-precipitation combined with hydrothermal method: zirconium chloride and yttrium nitrate were dissolved in deionized water according to a molar ratio of 8:1 (calculated as ZrO2:Y2O3) to prepare a mixed solution with a total metal ion concentration of 0.5 mol / L; a 1.8 mol / L potassium hydroxide solution was used as a precipitant and added to the mixed solution simultaneously into a high gravity reactor, and the system pH was adjusted to 8.0 for mixing in a high gravity field at a rotation speed of 1000 r / min, and the precipitate was obtained after stirring for 1 h; the precipitate was transferred to a hydrothermal reactor, deionized water was added to a solid-liquid ratio of 1:10, and hydrothermal reaction was carried out at 160℃ for 8 h; after the reaction, the precipitate was filtered, washed, and dried at 70℃ for 16 h to obtain the yttria-stabilized zirconia powder (the rest is the same as step 1 of example 1).

[0121] 2) Preparation of slurry: the powder obtained in step 1) was mixed with deionized water, and 0.5% of ammonium citrate by mass of the powder was added as a dispersant to prepare a slurry with a solid content of 30% after uniform stirring (the rest is the same as step 2 of example 1).

[0122] 3) Spray drying into spheres: the slurry was introduced into a spray drying device, the inlet air temperature was controlled at 250℃, and the atomization frequency was 28000 rpm for atomization drying, and the spherical precursor particles with a particle size distribution of 15-60 μm were obtained after screening (the rest is the same as step 3 of example 1).

[0123] 4) High-temperature calcination treatment: the spherical precursor particles were placed in a muffle furnace and heated to 700℃ at a heating rate of 5℃ / min, and the powder was calcined for 5 h to complete the glue removal and improve the powder bonding strength to obtain the spherical yttria-stabilized zirconia powder (the rest is the same as step 4 of example 1).

[0124] Figure 3 c is the scanning electron microscope image of the spherical yttria-stabilized zirconia powder obtained in example 4.

[0125] It was detected that the performance of the spherical yttria-stabilized zirconia powder prepared in this example was close to that of example 1.

[0126] Example 5

[0127] A spherical yttria-stabilized zirconia powder for thermal spraying and a preparation method thereof, steps as follows:

[0128] 1) High gravity co-precipitation combined with hydrothermal method to prepare yttria stabilized zirconia: the molar ratio of zirconium salt to yttrium salt is 12:1, the rotation speed of high gravity reactor is 2000 r / min, the precipitant is 2.2 mol / L ammonium carbonate solution, and the pH is adjusted to 10.5; the hydrothermal reaction temperature is 220℃, the holding time is 4h; the drying temperature is 50℃, and the drying time is 8h (the rest is the same as step 1 of example 1).

[0129] 2) Preparation of slurry: the solvent is deionized water, the solid content is 50%, and the dispersant is polyethylene glycol (the addition amount is 1.5% of the mass of the powder) (the rest is the same as step 2 of example 1).

[0130] 3) Spray drying into balls: the inlet air temperature is 280℃, the atomizer frequency is 32000 rpm, and the spherical precursor particles with a particle size of 25-70μm are obtained (the rest is the same as step 3 of example 1).

[0131] 4) High temperature calcination treatment: the calcination temperature is 1000℃, and the holding time is 3h (the rest is the same as step 4 of example 1).

[0132] It is detected that the performance of the spherical yttria stabilized zirconia powder prepared in this example is close to that of example 1.

[0133] Example 6

[0134] A kind of spherical yttria stabilized zirconia powder for thermal spraying and its preparation method, the steps are as follows:

[0135] 1) High gravity co-precipitation combined with hydrothermal method to prepare yttria stabilized zirconia: zirconium chloride and yttrium nitrate are dissolved in deionized water according to a molar ratio of 7:1 to prepare a mixed solution with a total metal ion concentration of 0.5 mol / L; 2.2 mol / L lithium hydroxide solution is used as a precipitant and added to the high gravity reactor at the same time as the mixed solution, and the system pH is adjusted to 8.5 in the high gravity field at a rotation speed of 800 r / min, and the stirring reaction is carried out for 1h to obtain a precursor precipitate; the precipitate is transferred to a hydrothermal reaction kettle, deionized water is added to a solid-liquid ratio of 1:10, and hydrothermal reaction is carried out at 180℃ for 10h; after the reaction is completed, the precipitate is filtered and washed, and dried at 65℃ for 18h to obtain yttria stabilized zirconia powder.

[0136] 2) Preparation of slurry: the powder obtained in step 1) is mixed with deionized water, and 1.5% of the mass of the powder is added as a dispersant sodium hexametaphosphate to prepare a slurry with a solid content of 35%.

[0137] 3) Spray drying into balls: the slurry is introduced into a spray drying device, the inlet air temperature is controlled at 200℃, the atomization frequency is 22000 rpm, and the atomization drying is carried out, and the spherical precursor particles with a particle size distribution of 25-70μm are obtained by screening.

[0138] 4) High temperature calcination treatment: the spherical precursor particles were placed in a muffle furnace, heated to 950℃ at a heating rate of 5℃ / min, and held for 3h to complete the degassing and improve the powder bonding strength, to obtain the spherical yttria-stabilized zirconia powder.

[0139] It was detected that the performance of the spherical yttria-stabilized zirconia powder prepared in this embodiment was close to that of Example 1.

[0140] Example 7

[0141] A spherical yttria-stabilized zirconia powder for thermal spraying and a preparation method thereof, the steps being as follows:

[0142] 1) Preparation of yttria-stabilized zirconia by high gravity co-precipitation combined with hydrothermal method: the molar ratio of zirconium salt to yttrium salt was 13:1, the rotation speed of the high gravity reactor was 2500r / min, the precipitant was a 2.0mol / L sodium carbonate solution, the pH of the system was adjusted to 9.5, and the stirring reaction was performed for 1h; the hydrothermal reaction temperature was 210℃, the holding time was 5h; the drying temperature was 55℃, and the drying time was 20h (the rest was the same as Step 1 of Example 1).

[0143] 2) Preparation of slurry: the solvent was deionized water, the solid content was 45%, and the dispersant was polyethylene glycol (the addition amount was 0.8% of the mass of the powder) (the rest was the same as Step 2 of Example 1).

[0144] 3) Spray drying into spheres: the inlet air temperature was 280℃, the atomization frequency was 26000rpm, and the spherical precursor particles with a particle size of 35-80μm were obtained (the rest was the same as Step 3 of Example 1).

[0145] 4) High temperature calcination treatment: the calcination temperature was 1000℃, and the holding time was 4h (the rest was the same as Step 4 of Example 1).

[0146] It was detected that the performance of the spherical yttria-stabilized zirconia powder prepared in this embodiment was close to that of Example 1.

[0147] Example 8

[0148] A spherical yttria-stabilized zirconia powder for thermal spraying and a preparation method thereof, the steps being as follows:

[0149] 1) Preparation of yttria stabilized zirconia by high gravity co-precipitation combined with hydrothermal method: Zirconium chloride and yttrium nitrate were dissolved in deionized water at a molar ratio of 6:1 (calculated as ZrO2:Y2O3) to prepare a mixed solution with a total metal ion concentration of 0.5 mol / L. A 1.6 mol / L barium hydroxide solution was used as a precipitant and was simultaneously added to the mixed solution in a high gravity reactor. The system was mixed in a high gravity field at a speed of 600 r / min, the pH was adjusted to 7.5, and the stirring reaction was carried out for 1 h to obtain a precursor precipitate. The precipitate was transferred to a hydrothermal reactor, deionized water was added to a solid-liquid ratio of 1:10, and a hydrothermal reaction was carried out at 150°C for 14 h. After the reaction, the precipitate was filtered, washed, and dried at 75°C for 14 h to obtain a yttria stabilized zirconia powder.

[0150] 2) Preparation of slurry: The powder obtained in step 1) was mixed with deionized water, and 0.3% of tannic acid by mass of the powder was added as a dispersant to prepare a slurry with a solid content of 25%.

[0151] 3) Spray drying into spheres: The slurry was introduced into a spray drying device, the inlet air temperature was controlled at 230°C, and the atomization frequency was 24,000 rpm for atomization drying. The spherical precursor particles with a particle size distribution of 10-40 μm were obtained after sieving.

[0152] 4) High-temperature calcination treatment: The spherical precursor particles were placed in a muffle furnace and heated to 850°C at a heating rate of 5°C / min. The glue was removed and the powder bonding strength was improved by keeping the temperature for 5 h to obtain a spherical yttria stabilized zirconia powder.

[0153] It was detected that the performance of the spherical yttria stabilized zirconia powder prepared in this embodiment was close to that of Example 1.

[0154] Example 9

[0155] A spherical yttria stabilized zirconia powder for thermal spraying and a preparation method thereof, the steps being as follows:

[0156] 1) Preparation of yttria stabilized zirconia by high gravity co-precipitation combined with hydrothermal method: the molar ratio of zirconium salt to yttrium salt was 14:1, the rotation speed of the high gravity reactor was 1200 r / min, the precipitant was a 1.9 mol / L potassium hydroxide solution, the system pH was adjusted to 9.0, and the stirring reaction was carried out for 1 h; the hydrothermal reaction temperature was 190°C, the temperature was kept for 7 h; the drying temperature was 60°C, and the drying time was 22 h (the rest was the same as step 1) of Example 1).

[0157] 2) Preparation of slurry: the solvent was deionized water, the solid content was 50%, and the dispersant was ammonium tartrate (the addition amount was 1.2% of the mass of the powder) (the rest was the same as step 2) of Example 1).

[0158] 3) Spray drying into spheres: inlet temperature 260℃, atomization frequency 29000 rpm, spherical precursor particles with particle size 40-100 μm were obtained (the rest is the same as step 3 of Example 1).

[0159] 4) High-temperature calcination treatment: calcination temperature 1050℃, holding time 3h (the rest is the same as step 4 of Example 1).

[0160] It was detected that the performance of the spherical yttria-stabilized zirconia powder prepared in this example was close to that of Example 1.

[0161] Example 10

[0162] A spherical yttria-stabilized zirconia powder for thermal spraying and a preparation method thereof, the steps being as follows:

[0163] 1) Preparation of yttria-stabilized zirconia by high gravity co-precipitation combined with hydrothermal method: zirconium chloride and yttrium nitrate were dissolved in deionized water at a molar ratio of 9.5:1 (calculated as ZrO2:Y2O3) to prepare a mixed solution with a total metal ion concentration of 0.5 mol / L; a 2.4 mol / L sodium bicarbonate solution was used as a precipitant and was added to the mixed solution simultaneously into a high gravity reactor, and the system pH was adjusted to 8.8 in a high gravity field at a rotation speed of 1800 r / min, and the stirring reaction was carried out for 1 h to obtain a precursor precipitate; the precipitate was transferred to a hydrothermal reaction kettle, deionized water was added to a solid-liquid ratio of 1:10, and a hydrothermal reaction was carried out at 190℃ for 9 h; after the reaction was completed, the precipitate was filtered, washed, and dried at 68℃ for 15 h to prepare a yttria-stabilized zirconia powder.

[0164] 2) Preparation of slurry: the powder obtained in step 1) was mixed with deionized water, 0.6% of sodium polyacrylate by mass of the powder was added as a dispersant, and a slurry with a solid content of 55% was prepared after uniform stirring.

[0165] 3) Spray drying into spheres: the slurry was introduced into a spray drying device, the inlet temperature was controlled at 210℃, the atomization frequency was 27000 rpm, and atomization drying was carried out, and spherical precursor particles with a particle size distribution of 20-50 μm were obtained by sieving.

[0166] 4) High-temperature calcination treatment: the spherical precursor particles were placed in a muffle furnace, heated to 800℃ at a heating rate of 5℃ / min, and held for 4.5 h to complete the glue removal and improve the bonding strength of the powder, and a spherical yttria-stabilized zirconia powder was prepared.

[0167] It was detected that the performance of the spherical yttria-stabilized zirconia powder prepared in this example was close to that of Example 1.

[0168] Comparative Example 1 Without using high gravity:

[0169] 1) Conventional coprecipitation to prepare yttria-stabilized zirconia: mixed solution was prepared according to the molar ratio of zirconium salt to yttrium salt 10:1, ammonia water was added dropwise under conventional stirring (500 r / min) until pH = 9.0, the precipitation reaction was 1 h, and the supergravity field was not used; hydrothermal reaction temperature was 160°C, holding time was 12 h, drying temperature was 100°C, and drying time was 16 h.

[0170] 2) Preparation of slurry, spray drying and calcination: same as Example 1 (slurry solid content 40%, spray drying inlet temperature 220°C, calcination temperature 900°C for 4 h).

[0171] It was detected that the product powder prepared in this comparative example had serious agglomeration, large particle size, and wide particle size distribution, further illustrating the advantages of the supergravity preparation method.

[0172] Figure 7 The scanning electron microscope spectrum and particle size distribution graph of the product powder of Comparative Example 1 compared with Example 1.

[0173] Comparative Example 2 (no hydrothermal reaction):

[0174] 1) Supergravity coprecipitation to prepare yttria-stabilized zirconia: mixed solution was prepared according to the molar ratio of zirconium salt to yttrium salt 10:1, and the mixed solution with a total metal ion concentration of 0.5 mol / L was prepared; 2 mol / L ammonia water was used as a precipitant and added into the supergravity reactor at the same time as the above mixed solution, and the mixing was carried out in the supergravity field at a rotating speed of 1500 r / min, the pH of the system was adjusted to 9.0, the stirring reaction was 1 h, and the precursor precipitate was obtained; no hydrothermal treatment was carried out, the precipitate was filtered and washed, and dried at 60°C for 12 h to prepare yttria-stabilized zirconia powder;

[0175] 2) Preparation of slurry, spray drying and calcination: same as Example 1 (slurry solid content 40%, spray drying inlet temperature 220°C, calcination temperature 900°C for 4 h).

[0176] It was detected that the XRD graph of the product powder showed that the crystallinity decreased because the comparative example did not carry out hydrothermal reaction.

[0177] Figure 8 The X-ray diffraction spectrum of the product powder obtained in Comparative Example 2 compared with Example 1.

[0178] Comparative Example 3 (no spray drying):

[0179] 1) Supergravity coprecipitation combined with hydrothermal method to prepare yttria-stabilized zirconia: same as Example 1

[0180] 2) Preparation of slurry, common drying and calcination: the slurry (slurry solid content 40%) was prepared as in Example 1, the slurry was poured into an open tray, and oven common drying (drying temperature 110°C, static drying for 24h) was adopted; after drying, the product was ground and sieved, and was kept at a calcination temperature of 900°C for 4h.

[0181] It was detected that, since the spray drying was not used in the present comparative example, most of the product powder was broken, and did not present a spherical shape.

[0182] Figure 9 is a scanning electron microscope pattern of the product powder obtained in Comparative Example 3.

[0183] In summary, the spherical yttria-stabilized zirconia powder for thermal spraying obtained by the present application has good sphericity, good fluidity, and concentrated particle size (30μm-40μm), and the X-ray diffraction test sample of the spherical yttria-stabilized zirconia powder for thermal spraying obtained by the present application has a single phase structure.

[0184] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. It is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A spherical yttria-stabilized zirconia powder for thermal spraying, characterized by: The yttria-stabilized zirconia powder is spherical particles with a sphericity of ≥95%; a particle size distribution of 10-90 μm; a nanocrystalline grain size of 20-80 nm; a compressive strength of ≥50 MPa; and a thermal conductivity of ≤1.5 W / m·K; and a yttria content of 5%-8% as measured by Y2O3.

2. The spherical yttria-stabilized zirconia powder according to claim 1, wherein: The bulk density of the yttria-stabilized zirconia powder is 1.5-2.5 g / cm 3 ; the tap density is 2.0-3.0 g / cm 3 ; and the Hall flow rate is ≤ 60 s / 50 g.

3. The method of producing a spherical yttria-stabilized zirconia powder for thermal spraying according to any one of claims 1 or 2, wherein The method comprises the following steps: 1) preparing yttria-stabilized zirconia by high gravity co-precipitation combined with a hydrothermal method: mixing a zirconium salt solution and a yttrium salt solution, adding a precipitant in a high gravity reactor to perform a co-precipitation reaction, obtaining a precursor precipitate, and then performing a hydrothermal reaction and drying to obtain a yttria-stabilized zirconia powder; 2) preparing a slurry: mixing the yttria-stabilized zirconia powder obtained in step 1) with a solvent to prepare a slurry with a solid content of 20%-60%; 3) spray drying into a ball: atomizing and drying the slurry by a spray drying device to form spherical precursor particles; 4) high-temperature calcination treatment: calcining the spherical precursor particles to obtain the spherical yttria-stabilized zirconia powder.

4. The method of claim 3, wherein: In step 1), the rotor speed of the high gravity reactor is 500-3000 r / min.

5. The method of claim 3, wherein: In step 1), the zirconium salt is selected from one or more of zirconium nitrate, zirconium oxychloride, and zirconium sulfate; the yttrium salt is selected from one or more of yttrium nitrate, yttrium chloride, and yttrium sulfate; and the molar ratio of the zirconium salt to the yttrium salt is (7-15):

1.

6. The method of claim 3, wherein: In step 1), the precipitant is one or more of ammonia, sodium hydroxide, and ammonium bicarbonate; and the molar ratio of the precipitant to the total metal ions of the zirconium salt and the yttrium salt is (1.1-2.0):

1. Preferably, in step 1), the temperature of the hydrothermal reaction is 180-220℃, and the time is 3-12 hours; and the drying temperature is 50-100℃, and the drying time is 12-24 hours.

7. The method of claim 3, wherein: In step 2), the solvent is deionized water or ethanol. Preferably, in step 2), 0.1%-2% of a dispersant is added to the slurry. Preferably, the dispersant is one or both of polyvinyl alcohol and ammonium polyacrylate.

8. The method of claim 3, wherein: In step 3), the inlet air temperature of the spray drying is 180-300℃, the frequency of the atomizer is 15000-35000 rpm, and the particle size of the obtained spherical precursor particles is 10-90 μm.

9. The method of claim 3, wherein: In step 4), the calcination temperature is 300-1100℃, and the calcination time is 2-6 hours.

10. Use of the spherical yttria-stabilized zirconia powder according to any one of claims 1 or 2 in thermal spraying to prepare a thermal barrier coating, characterized in that: the thermal barrier coating prepared by thermal spraying of the spherical yttria-stabilized zirconia powder has an increased thermal shock resistance of ≥29% at a high temperature environment of 1200℃ or above, and a service life that is increased by more than 40% compared to a traditional coating.

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