High-temperature sintering-resistant ceramic powder for thermal spraying and preparation method thereof

Abstract

The application discloses a kind of high-temperature sintering-resistant ceramic powder for thermal spraying and a preparation method thereof, and relates to the field of ceramic materials.The application adopts the way of solid phase reaction, secondary ball milling, secondary granulation and high-temperature agglomeration treatment to prepare the powder, and mainly controls the time of secondary ball milling and the solid content of slurry during the preparation process, and adjusts the agglomeration degree and morphology of the ceramic powder by adjusting the procedures of secondary granulation, heat treatment and high-temperature agglomeration treatment temperature.The powder prepared by the application can maintain high porosity and specific surface area before and after high-temperature sintering, and can be added to APS ceramic material as a pore-forming agent or sintering-resistant agent, so as to alleviate the performance degradation problem of APS ceramic material caused by sintering during high-temperature service, and prolong the service life of the material.The preparation method of the application is simple, and the requirements for equipment and operation are not high, so that the porous ceramic powder for thermal spraying with sintering-resistant performance can be prepared in large quantities at low cost.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, specifically to a high-temperature anti-sintering ceramic powder for thermal spraying and its preparation method. Background Technology

[0002] Ceramic materials possess excellent high-temperature stability, high fracture toughness, and high ionic conductivity, and are widely used in high-temperature structural ceramics, thermal barrier coatings, solid oxide fuel cells, and other fields. The performance of ceramic materials is closely related to their microstructure characteristics, which typically depend on the preparation process and the properties of the raw materials.

[0003] Air Plasma spraying (APS), a widely used industrial thermal spraying technology, is a typical method for preparing high-temperature ceramic materials. Benefiting from the interlayer porosity formed during the preparation process, APS ceramic materials typically possess excellent thermal insulation properties and strain tolerance, enabling them to resist thermal erosion and complex stress damage under high-temperature environments. However, under long-term high-temperature service conditions, APS ceramics face a severe sintering degradation problem. During sintering, multiple bridging points form between the APS lamellar structures, causing the interlayer porosity to disappear and the ceramic material to gradually densify. In this process, the excellent thermal and mechanical properties of APS ceramic materials gradually deteriorate, thus threatening the service life of the ceramic material.

[0004] Powder structure design is a major technical means to alleviate the sintering problem of APS ceramic materials, and it is of great significance for improving their performance and extending their service life under high temperature service environment.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] To address the sintering degradation problem of existing APS ceramic materials, this invention provides a high-temperature anti-sintering ceramic powder for thermal spraying and its preparation method. This invention aims to improve the anti-sintering performance and service life of APS ceramic materials through powder structure design, thereby improving their overall thermal and mechanical properties in application scenarios. It solves the problem of internal pore structure healing caused by high-temperature sintering during service in ceramic materials prepared using thermal spraying technology, which leads to material densification, reduced strain tolerance, and accelerated spalling failure.

[0007] The technical solution adopted by this invention to solve the technical problem is as follows:

[0008] This invention provides a high-temperature anti-sintering ceramic powder for thermal spraying. The powder has a tetragonal crystal structure with a median diameter (D50) of 48-55 μm. After sintering at 1400℃ in an atmospheric atmosphere for 100 hours, the powder has a porosity of 18%-28% and a specific surface area of ​​2.55 m². 2 / g~3.12m 2 / g.

[0009] This invention provides a method for preparing high-temperature anti-sintering ceramic powder for thermal spraying, comprising the following steps:

[0010] Step S1: Mix oxide ceramic powder raw material and rare earth oxide stabilizer at a stoichiometric ratio of 0.8~0.96:0.04~0.2, and use deionized water as solvent to prepare slurry. The solid content of the obtained slurry is 40%~50%.

[0011] Step S2: Add a dispersant to the obtained slurry, with a dispersant content of 1 wt% to 3 wt%.

[0012] Step S3: Add ball milling media to ball mill the slurry, and test the particle size of the ball-milled slurry;

[0013] Step S4: Add a binder to the fully ball-milled slurry for agglomeration treatment, and inject it into the granulation equipment for spray granulation;

[0014] Step S5: Heat-treat the granulated powder to remove excess binder;

[0015] Step S6: Heat-treat the granulated powder after removing excess binder to form a phase;

[0016] Step S7: Perform secondary ball milling and secondary granulation on the phase-formed powder;

[0017] Step S8: The powder after secondary granulation is heat-treated to remove excess binder and then subjected to high-temperature agglomeration treatment to obtain high-temperature anti-sintering ceramic powder for thermal spraying.

[0018] In a preferred embodiment, in step S1, the oxide ceramic powder raw material is selected from one or more of zirconium oxide, gadolinium zirconate, lanthanum zirconate, and lanthanum cerate; the rare earth oxide stabilizer is selected from one or more of yttrium oxide, ytterbium oxide, cerium dioxide, lanthanum oxide, gadolinium trioxide, scandium trioxide, aluminum trioxide, and titanium dioxide.

[0019] In a preferred embodiment, in step S2, the dispersant is selected from one of triammonium citrate, ammonium polyacrylate, and sodium polyacrylate.

[0020] In a preferred embodiment, in step S4, the adhesive is selected from gum arabic, polyvinyl alcohol, and acrylic acid.

[0021] In a preferred embodiment, in step S3, the milling medium is zirconia grinding beads, the milling method is planetary ball milling, the ball-to-material mass ratio is 1~3:1, three types of grinding beads are used for milling, the mass ratio of the three types of grinding beads is 7.5~9:2~3:1, the diameter ratio of the three types of grinding beads is 1:1.5~3:3.5~5, the milling speed is set to 60~90 rpm / min, the milling time is 20~24 hours, and the median diameter D50 of the milled slurry is 0.7μm~1μm.

[0022] In a preferred embodiment, in step S4, the granulation temperature is 110~135℃, the heating rate is 2~4.5℃ / min, the atomizing nozzle rotation speed is 70~100 rpm / min, and the motor frequency is 30~45 Hz.

[0023] In a preferred embodiment, in step S5, the heat treatment temperature is 550~700℃, the time is 1~3 hours, and the heating rate is 1~2℃ / min.

[0024] In a preferred embodiment, in step S6, the temperature for heat treatment to form the phase is 1400~1500℃, the heating rate is 8~10℃ / min, and the holding time is 18~24 hours.

[0025] In a preferred embodiment, in step S7, the medium for the secondary ball milling is zirconia grinding beads, the ball milling method is closed sand milling, the ball-to-material mass ratio is 0.5~1:1, two types of grinding beads are used for grinding, the mass ratio of the two types of grinding beads is 4.5~6:2~3, the diameter ratio of the two types of grinding beads is 7.5~9:3~5, the ball milling speed is set to 30~50 rpm / min, the ball milling time is 5~10 hours, and the median diameter D50 of the slurry after ball milling is 1μm~3μm; the temperature of the secondary granulation is 95~120℃, the heating rate is 2~5℃ / min, the atomizing nozzle speed is 40~60 rpm / min, and the motor frequency is 20~28 Hz.

[0026] In a preferred embodiment, in step S8, the high-temperature agglomeration treatment is carried out in an atmospheric environment. First, the temperature is raised to 1150-1250°C at a heating rate of 2-4°C / min and held for 3-5 hours, and then raised to 1400-1450°C at a heating rate of 5-7°C / min and held for 0.5-2 hours.

[0027] The beneficial effects of this invention are as follows:

[0028] The present invention provides a high-temperature anti-sintering ceramic powder for thermal spraying, which has excellent high-temperature sintering resistance. Under long-term high-temperature service environment, the powder can maintain a high porosity and specific surface area. It can be added to APS ceramic materials as a pore-forming agent or anti-sintering agent, thereby alleviating the performance degradation problem caused by sintering during the high-temperature service of APS ceramic materials and extending the service life of the materials.

[0029] This invention provides a method for preparing high-temperature anti-sintering ceramic powder for thermal spraying. The powder is prepared by combining solid-phase reaction, secondary ball milling and secondary granulation. The agglomeration degree and morphology of the anti-sintering powder are mainly controlled by two ball milling, two granulation and two heat treatment temperature control processes. The preparation process is simple, low cost and does not have high requirements for equipment and operation, which is conducive to large-scale industrial application. Attached Figure Description

[0030] Figure 1 The images show the microstructure of the powder prepared in Example 1 of this invention (a) and the powder after heat treatment at 1400℃ for 100 hours (b).

[0031] Figure 2 The images show the microstructure of the powder prepared in Example 2 of this invention (a) and the powder after heat treatment at 1400℃ for 100 hours (b).

[0032] Figure 3 The images show the microstructure of the powder prepared in Example 3 of this invention (a) and the powder after heat treatment at 1400℃ for 100 hours (b).

[0033] Figure 4 The images show the microstructure of the powder prepared in Comparative Example 1 of this invention (a) and the powder after heat treatment at 1400℃ for 100 hours (b).

[0034] Figure 5 The XRD patterns are those of the ceramic powders prepared in Examples 1-3 of this invention. Detailed Implementation

[0035] In a first aspect, the present invention provides a high-temperature anti-sintering ceramic powder for thermal spraying.

[0036] This invention provides a high-temperature anti-sintering ceramic powder for thermal spraying, which has a tetragonal crystal structure with a median diameter (D50) of 48-55 μm and exhibits excellent high-temperature phase structure stability. After sintering at 1400℃ in an atmospheric atmosphere for 100 hours, the powder porosity remains at 18%-28%, and the specific surface area remains at 2.55 m². 2 / g~3.12m 2 / g.

[0037] Secondly, the present invention provides a method for preparing high-temperature anti-sintering ceramic powder for thermal spraying.

[0038] The present invention provides a method for preparing high-temperature anti-sintering ceramic powder for thermal spraying, which specifically includes the following steps:

[0039] Step S1: Mix oxide ceramic powder raw material and rare earth oxide stabilizer at a stoichiometric ratio of 0.8~0.96:0.04~0.2, and use deionized water as solvent to prepare slurry. The solid content of the obtained slurry is 40%~50%.

[0040] Preferably, the oxide ceramic powder raw material is selected from one or more of zirconium oxide, gadolinium zirconate, lanthanum zirconate, and lanthanum cerate.

[0041] Preferably, the rare earth oxide stabilizer is selected from one or more of yttrium oxide (Y₂O₃), ytterbium oxide (Yb₂O₃), cerium dioxide (CeO₂), lanthanum oxide (La₂O₃), gadolinium oxide (Gd₂O₃), scandium oxide (Sc₂O₃), aluminum oxide (Al₂O₃), and titanium dioxide (TiO₂). One or more of Y₂O₃, Yb₂O₃, CeO₂, La₂O₃, Gd₂O₃, Sc₂O₃, Al₂O₃, and TiO₂ are added to the ceramic powder lattice as rare earth oxide stabilizers to form a solid solution.

[0042] Step S2: Add a dispersant to the obtained slurry, with a dispersant content of 1 wt% to 3 wt%.

[0043] Preferably, the dispersant is selected from one of triammonium citrate, ammonium polyacrylate, and sodium polyacrylate.

[0044] Step S3: Add ball milling media to ball mill the slurry, and then test the particle size of the ball-milled slurry.

[0045] Preferably, the milling media is zirconia grinding beads, the milling method is planetary ball milling, the ball-to-material mass ratio is 1~3:1, three types of grinding beads are used for milling, the mass ratio of the three types of grinding beads is 7.5~9:2~3:1, the diameter ratio of the three types of grinding beads is 1:1.5~3:3.5~5, the milling speed is set to 60~90 rpm / min, the milling time is 20~24 hours, and the median diameter D50 of the milled slurry is 0.7μm~1μm.

[0046] Step S4: Add a binder to the fully ball-milled slurry for agglomeration treatment, and inject it into the granulation equipment for spray granulation;

[0047] Preferably, the granulation temperature is 110~135℃, the heating rate is 2~4.5℃ / min, the atomizing nozzle speed is 70~100rpm / min, and the motor frequency is 30~45 Hz.

[0048] Step S5: Heat-treat the granulated powder to remove excess binder.

[0049] Preferably, the heat treatment temperature is 550~700℃, the time is 1~3 hours, and the heating rate is 1~2℃ / min.

[0050] Step S6: Heat-treat the granulated powder after removing excess binder to form a phase.

[0051] Preferably, the heat treatment phase formation temperature is 1400~1500℃, the heating rate is 8~10℃ / min, and the holding time is 18~24 hours.

[0052] Step S7: Perform secondary ball milling and secondary granulation on the phase-formed powder;

[0053] Preferably, the media used in the secondary ball milling is zirconia grinding beads, the ball milling method is closed sand milling, the ball-to-material mass ratio is 0.5~1:1, two types of grinding beads are used for grinding, the mass ratio of the two types of grinding beads is 4.5~6:2~3, the diameter ratio of the two types of grinding beads is 7.5~9:3~5, the ball milling speed is set to 30~50 rpm / min, the ball milling time is 5~10 hours, and the median diameter D50 of the slurry after ball milling is 1μm~3μm.

[0054] Preferably, the temperature of the secondary granulation is 95~120℃, the heating rate is 2~5℃ / min, the atomizing nozzle rotation speed is 40~60 rpm / min, and the motor frequency is 20~28 Hz.

[0055] Step S8: The powder after secondary granulation is heat-treated to remove excess binder and then subjected to high-temperature agglomeration treatment to obtain high-temperature anti-sintering ceramic powder for thermal spraying.

[0056] Preferably, the high-temperature agglomeration treatment is carried out in an atmospheric atmosphere, with a phased heating and phased holding process. First, the temperature is raised to 1150-1250℃ at a heating rate of 2-4℃ / min and held for 3-5 hours, and then raised to 1400-1450℃ at a heating rate of 5-7℃ / min and held for 0.5-2 hours.

[0057] The present invention will now be described in detail with reference to specific embodiments, thereby providing a clearer description of the application objectives, technical solutions, and advantages of the present invention. The described embodiments are some, but not all, implementations of the present invention. It should be understood that the embodiments described herein are for illustrative purposes only and should not be construed as limiting the scope of protection of the present invention.

[0058] Example 1: Preparation of High-Temperature Anti-Sintering Ceramic Powder for Thermal Spraying

[0059] This embodiment discloses a method for preparing high-temperature anti-sintering ceramic powder for thermal spraying, the specific operation process of which is as follows:

[0060] (1) Weigh zirconium oxide and yttrium oxide powders according to a stoichiometric ratio of 0.92:0.08 and dissolve them in deionized water to prepare a slurry. Here, yttrium oxide is used as a rare earth oxide stabilizer to be doped into the zirconium oxide lattice to form a solid solution. The solid content of the slurry is controlled at 45% by controlling the amount of deionized water added.

[0061] (2) Add the slurry prepared in step (1) into the ball mill jar, and add 2 wt% triammonium citrate as a dispersant to the slurry before ball milling.

[0062] (3) High-purity zirconia grinding beads were added to the ball milling jar as the ball milling medium. The ball milling method was planetary ball milling. During the ball milling process, the mass ratio of slurry to grinding beads was 1:1. Three types of grinding beads with diameters of 1 mm, 3 mm and 5 mm were used for grinding. The mass ratio of these three types of grinding beads was 9:3:1. The ball milling speed was set to 86 rpm / min and the ball milling time was 20 hours. The particle size of the ball-milled slurry was tested by a laser particle size analyzer. The median diameter D50 of the slurry was 0.85 μm.

[0063] (4) Add 0.05wt% gum arabic 1 hour before the ball milling process is completed for agglomeration treatment, and inject the treated slurry into a high-speed centrifugal spray granulator for spray granulation. The granulation temperature is 135℃, the heating rate is 2℃ / min, the atomizing nozzle speed is 80 rpm / min, and the motor frequency is 34 Hz.

[0064] (5) The granulated powder obtained in step (4) is subjected to heat treatment at 700℃ for 2 hours to remove excess binder. The heating rate is 2℃ / min.

[0065] (6) The granulated powder after debinding in step (5) is subjected to heat treatment to form a phase at a temperature of 1400℃, a heating rate of 10℃ / min, and a holding time of 20 hours.

[0066] (7) The phase-forming powder obtained in step (6) is subjected to secondary ball milling and secondary granulation. The medium for secondary ball milling is zirconia grinding beads. The ball milling method is closed sand milling. The ball-to-material mass ratio is 1:1. Two types of grinding beads with diameters of 9 mm and 5 mm are used for grinding. The mass ratio of these two types of grinding beads is 5:3. The ball milling speed is set to 40 rpm / min and the ball milling time is 5 hours. The particle size of the slurry after ball milling is tested by a laser particle size analyzer. The median diameter D50 of the slurry is 3 μm. The slurry after secondary ball milling is subjected to secondary granulation. The temperature of secondary granulation is 120℃, the heating rate is 5℃ / min, the atomizing nozzle speed is 60 rpm / min, and the motor frequency is 28 Hz.

[0067] (8) First, the powder after secondary granulation in step (7) is heat-treated at 700℃ for 2 hours to remove excess binder; then, high-temperature agglomeration treatment is carried out: under atmospheric conditions, the temperature is first raised to 1200℃ at a heating rate of 2℃ / min and held for 3 hours, and then raised to 1400℃ at a heating rate of 5℃ / min and held for 1 hour to obtain high-temperature anti-sintering ceramic powder for thermal spraying. The particle size is tested by a laser particle size analyzer, and the median diameter D50 is 55μm.

[0068] Example 2: Preparation of High-Temperature Anti-Sintering Ceramic Powder for Thermal Spraying

[0069] This embodiment discloses a method for preparing high-temperature anti-sintering ceramic powder for thermal spraying, the specific operation process of which is as follows:

[0070] (1) Weigh zirconium oxide and cerium oxide powders according to a stoichiometric ratio of 0.84:0.16 and dissolve them in deionized water to prepare a slurry. Here, cerium oxide is used as a rare earth oxide stabilizer to be doped into the zirconium oxide lattice to form a solid solution. The solid content of the slurry is controlled at 40% by controlling the amount of deionized water added.

[0071] (2) Add the slurry prepared in step (1) into the ball mill jar, and add 2 wt% of ammonium polyacrylate as a dispersant to the slurry before ball milling.

[0072] (3) High-purity zirconia grinding beads were added to the ball milling jar as the ball milling medium. The ball milling method was planetary ball milling. During the ball milling process, the mass ratio of slurry to grinding beads was 1:1. Three types of grinding beads with diameters of 1 mm, 3 mm and 5 mm were used for grinding. The mass ratio of these three types of grinding beads was 9:3:1. The ball milling speed was set to 90 rpm / min and the ball milling time was 24 hours. The particle size of the ball milled slurry was tested by a laser particle size analyzer. The median diameter D50 of the slurry was 0.75 μm.

[0073] (4) Add 0.05 wt% gum arabic 1 hour before the ball milling process is completed for agglomeration treatment, and inject the treated slurry into a high-speed centrifugal spray granulator for spray granulation. The granulation temperature is 135℃, the heating rate is 2℃ / min, the atomizing nozzle speed is 80 rpm / min, and the motor frequency is 34 Hz.

[0074] (5) The granulated powder obtained in step (4) is subjected to heat treatment at 700℃ for 2 hours to remove excess binder. The heating rate is 2℃ / min.

[0075] (6) The granulated powder after debinding in step (5) is subjected to heat treatment to form a phase at a temperature of 1400℃, a heating rate of 10℃ / min, and a holding time of 20 hours.

[0076] (7) The phase-forming powder obtained in step (6) is subjected to secondary ball milling and secondary granulation. The media for secondary ball milling is zirconia grinding beads. The ball milling method is closed sand milling. The ball-to-material mass ratio is 1:1. Two types of grinding beads with diameters of 9 mm and 5 mm are used for grinding. The mass ratio of these two types of grinding beads is 5:3. The ball milling speed is set to 40 rpm / min and the ball milling time is 7 hours. The particle size of the slurry after ball milling is tested by a laser particle size analyzer. The median diameter D50 of the slurry is 2.5 μm. The slurry after secondary ball milling is subjected to secondary granulation. The temperature of secondary granulation is 120℃, the heating rate is 5℃ / min, the atomizing nozzle speed is 60 rpm / min, and the motor frequency is 28 Hz.

[0077] (8) First, the powder after secondary granulation in step (7) is heat-treated at 700℃ for 2 hours to remove excess binder; then, high-temperature agglomeration treatment is carried out: under atmospheric conditions, the temperature is first raised to 1200℃ at a heating rate of 2℃ / min and held for 4 hours, and then raised to 1400℃ at a heating rate of 5℃ / min and held for 0.5 hours to obtain high-temperature anti-sintering ceramic powder for thermal spraying. The particle size is tested by a laser particle size analyzer, and the median diameter D50 is 48μm.

[0078] Example 3: Preparation of High-Temperature Anti-Sintering Ceramic Powder for Thermal Spraying

[0079] This embodiment discloses a method for preparing high-temperature anti-sintering ceramic powder for thermal spraying, the specific operation process of which is as follows:

[0080] (1) Weigh zirconium oxide, cerium oxide and gadolinium oxide powders according to the stoichiometric ratio of 0.80:0.16:0.04 and dissolve them in deionized water to prepare slurry. Here, cerium oxide and gadolinium oxide are used as rare earth oxide stabilizers to be doped into the zirconium oxide lattice to form a solid solution. The solid content of the slurry is controlled at 50% by controlling the amount of deionized water added.

[0081] (2) Add the slurry prepared in step (1) into a ball mill jar, and add sodium polyacrylate with a content of 2 wt% as a dispersant to the slurry before ball milling.

[0082] (3) High-purity zirconia grinding beads were added to the ball milling jar as the ball milling medium. The ball milling method was planetary ball milling. During the ball milling process, the mass ratio of slurry to grinding beads was 1:1. Three types of grinding beads with diameters of 1 mm, 3 mm and 5 mm were used for grinding. The mass ratio of these three types of grinding beads was 9:3:1. The ball milling speed was set to 70 rpm / min and the ball milling time was 24 hours. The particle size of the ball-milled slurry was tested by a laser particle size analyzer. The median diameter D50 of the slurry was 1 μm.

[0083] (4) Add 0.05wt% gum arabic 1 hour before the ball milling process is completed for agglomeration treatment, and inject the treated slurry into a high-speed centrifugal spray granulator for spray granulation. The granulation temperature is 135℃, the heating rate is 2℃ / min, the atomizing nozzle speed is 80 rpm / min, and the motor frequency is 34 Hz.

[0084] (5) The granulated powder obtained in step (4) is subjected to heat treatment at 700℃ for 2 hours to remove excess binder. The heating rate is 2℃ / min.

[0085] (6) The granulated powder after debinding in step (5) is subjected to heat treatment to form a phase at a temperature of 1400℃, a heating rate of 10℃ / min, and a holding time of 20 hours.

[0086] (7) The phase-forming powder obtained in step (6) is subjected to secondary ball milling and secondary granulation. The medium for secondary ball milling is zirconia grinding beads. The ball milling method is closed sand milling. The ball-to-material mass ratio is 1:1. Two types of grinding beads with diameters of 9 mm and 5 mm are used for grinding. The mass ratio of these two types of grinding beads is 5:3. The ball milling speed is set to 40 rpm / min and the ball milling time is 10 hours. The particle size of the slurry after ball milling is tested by a laser particle size analyzer. The median diameter D50 of the slurry is 2 μm. The slurry after secondary ball milling is subjected to secondary granulation. The temperature of secondary granulation is 120℃, the heating rate is 5℃ / min, the atomizing nozzle speed is 60 rpm / min, and the motor frequency is 28 Hz.

[0087] (8) First, the powder after secondary granulation in step (7) is heat-treated at 700℃ for 2 hours to remove excess binder; then, high-temperature agglomeration treatment is carried out: under atmospheric conditions, the temperature is first raised to 1200℃ at a heating rate of 2℃ / min and held for 5 hours, and then raised to 1400℃ at a heating rate of 5℃ / min and held for 1.5 hours to obtain high-temperature anti-sintering ceramic powder for thermal spraying. The particle size is tested by a laser particle size analyzer, and the median diameter D50 is 50μm.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 1 is that the powder preparation adopts conventional solid-phase synthesis technology, that is, the preparation process only involves one slurry ball milling, spray granulation and sintering phase formation, omitting steps (7) and (8). In addition, the slurry solid content in Comparative Example 1 is 60%, the ball-to-powder mass ratio in the ball milling process is 4:1, and the ball milling time is extended to 48 hours. The median diameter D50 of the ball-milled slurry was measured to be 0.1 μm.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Example 2 is that in step (7), the ball-to-material mass ratio during the secondary ball milling process is 2:1, the diameter of the grinding beads is 1 mm, the ball milling time is 24 hours, and the median diameter D50 of the slurry after the secondary ball milling is measured to be 0.5 μm. In addition, the atomizing nozzle speed is 120 rpm / min during the secondary granulation process, and step (8) is omitted.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 3 is that: in step (7), the secondary ball milling time is 15 hours, and the median diameter D50 of the slurry after secondary ball milling is measured to be 0.8 μm; in step (8), during the high-temperature agglomeration process, the temperature is directly raised to 1400℃ at a heating rate of 5℃ / min and kept at that temperature for 5 hours.

[0094] Anti-sintering performance, particle size characterization, and phase composition characterization were performed on Examples 1-3 and Comparative Examples 1-3, respectively. The morphology, porosity, and specific surface area of ​​each powder before and after sintering at 1400℃ in an atmospheric atmosphere for 100 hours were analyzed. For porosity testing, the internal pore content of the powder was determined using an image method. The powder cross-section was polished using a standard metallographic method, and the pore content in the powder was measured using image analysis software. The particle size of each powder and slurry was measured using a laser particle size analyzer.

[0095] As shown in Table 1, the median diameter (D50) of the ceramic powders prepared in Examples 1-3 of this invention is 48-55 μm, and the porosity in the prepared state remains at 25-31%. After sintering at 1400℃ for 100 hours, the porosity of the powders still remains above 21%, and the specific surface area of ​​the powders changes little before and after sintering, with the specific surface area of ​​all powders remaining at 2.2 m². 2 / g or more. Conversely, after sintering at 1400℃ for 100 hours, the porosity of the ceramic powder prepared in Comparative Example 1 decreased significantly from 15% in the prepared state to 4%, and the corresponding specific surface area of ​​the powder increased from 1.65 m² / g. 2 / g decreased to 0.96m 2 / g. The porosity and specific surface area of ​​the ceramic powders prepared in Comparative Examples 2 and 3 were significantly reduced before and after the sintering test.

[0096] Table 1 Characterization of anti-sintering properties of powder

[0097]

[0098] also, Figures 1-3 The images show the ceramic powders prepared in Examples 1-3 in their preparative state and after sintering at 1400℃ for 100 hours. Figure 4The ceramic powder prepared in Comparative Example 1 is shown in its preparative state and its microstructure after sintering at 1400℃ for 100 hours. Figure 5 The phase composition of the ceramic powders prepared in Examples 1-3 is shown above. The characterization results indicate that the ceramic powders prepared in Examples 1-3 all exhibit a tetragonal zirconia crystal structure. After attempted high-temperature sintering, the microstructure of the ceramic powders prepared in Examples 1-3 showed little change, maintaining a loose and porous internal structure. In contrast, the ceramic powder provided in Comparative Example 1 showed that its internal pore structure essentially disappeared after sintering at 1400℃ for 100 hours, indicating poor high-temperature sintering resistance. In conclusion, the ceramic powder material prepared using the method provided by this invention possesses excellent high-temperature sintering resistance.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing high-temperature anti-sintering ceramic powder for thermal spraying, characterized in that, Includes the following steps: Step S1: Mix oxide ceramic powder raw material and rare earth oxide stabilizer at a stoichiometric ratio of 0.8~0.96:0.04~0.2, and use deionized water as solvent to prepare slurry. The solid content of the obtained slurry is 40%~50%. Step S2: Add a dispersant to the obtained slurry, with a dispersant content of 1wt%~3wt%; Step S3: Add ball milling media to ball mill the slurry, and test the particle size of the ball-milled slurry; Step S4: Add a binder to the fully ball-milled slurry for agglomeration treatment, and inject it into the granulation equipment for spray granulation; Step S5: Heat-treat the granulated powder to remove excess binder; Step S6: Heat-treat the granulated powder after removing excess binder to form a phase; Step S7: Perform secondary ball milling and secondary granulation on the phase-formed powder; Step S8: The powder after secondary granulation is heat-treated to remove excess binder and then subjected to high-temperature agglomeration treatment to obtain high-temperature anti-sintering ceramic powder for thermal spraying; In step S2, the dispersant is selected from one of triammonium citrate, ammonium polyacrylate, and sodium polyacrylate. In step S3, the milling medium is zirconia grinding beads, the milling method is planetary ball milling, the ball-to-material mass ratio is 1~3:1, three types of grinding beads are used for milling, the mass ratio of the three types of grinding beads is 7.5~9:2~3:1, the diameter ratio of the three types of grinding beads is 1:1.5~3:3.5~5, the milling speed is set to 60~90 rpm / min, the milling time is 20~24 hours, and the median diameter D50 of the milled slurry is 0.7μm~1μm. In step S4, the granulation temperature is 110~135℃, the heating rate is 2~4.5℃ / min, the atomizing nozzle speed is 70~100rpm / min, and the motor frequency is 30~45Hz. In step S5, the heat treatment temperature is 550~700℃, the time is 1~3 hours, and the heating rate is 1~2℃ / min. In step S6, the temperature for heat treatment to form the phase is 1400~1500℃, the heating rate is 8~10℃ / min, and the holding time is 18~24 hours. In step S7, the medium for the secondary ball milling is zirconia grinding beads, the ball milling method is closed sand milling, the ball-to-material mass ratio is 0.5~1:1, two types of grinding beads are used for grinding, the mass ratio of the two types of grinding beads is 4.5~6:2~3, the diameter ratio of the two types of grinding beads is 7.5~9:3~5, the ball milling speed is set to 30~50 rpm / min, the ball milling time is 5~10 hours, and the median diameter D50 of the ball-milled slurry is 1μm~3μm; the temperature of the secondary granulation is 95~120℃, the heating rate is 2~5℃ / min, the atomizing nozzle speed is 40~60 rpm / min, and the motor frequency is 20~28Hz; In step S8, the high-temperature agglomeration treatment is carried out in an atmospheric environment. First, the temperature is raised to 1150-1250℃ at a heating rate of 2-4℃ / min and held for 3-5 hours. Then, the temperature is raised to 1400-1450℃ at a heating rate of 5-7℃ / min and held for 0.5-2 hours.

2. The method for preparing high-temperature anti-sintering ceramic powder for thermal spraying according to claim 1, characterized in that, In step S1, the oxide ceramic powder raw material is selected from one or more of zirconium oxide, gadolinium zirconate, lanthanum zirconate, and lanthanum cerate; the rare earth oxide stabilizer is selected from one or more of yttrium oxide, ytterbium oxide, cerium dioxide, lanthanum oxide, gadolinium trioxide, scandium trioxide, aluminum trioxide, and titanium dioxide.

3. The high-temperature anti-sintering ceramic powder for thermal spraying prepared by the preparation method according to claim 1 or 2, characterized in that, The powder has a tetragonal crystal structure with a median diameter (D50) of 48–55 μm. After sintering at 1400 °C for 100 hours in an atmospheric atmosphere, the powder porosity is 18%–28%, and the specific surface area is 2.55 m². 2 / g~3.12m 2 / g.

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