A nanometer-scale yttrium-stabilized zirconium powder and its preparation method

Abstract

The present invention belongs to the field of nanopowder materials technology, specifically relating to a nanoscale yttrium-stabilized zirconium powder and its preparation method. The preparation method comprises the following steps: uniformly mixing zirconium oxychloride with yttrium oxide, aluminum oxide, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide, followed by a single high-temperature calcination to obtain a precursor powder; then subjecting the precursor powder to a primary grinding, impurity removal, and spray drying. After drying, the precursor powder is subjected to a secondary high-temperature calcination. The resulting secondary calcined powder is then subjected to a secondary grinding and impurity removal, followed by the addition of additives, uniform mixing, and spray granulation to obtain the nanoscale yttrium-stabilized zirconium powder. The nanoscale yttrium-stabilized zirconium powder of the present invention has: ZrO2+HfO2≥90%, Y2O3=2.50-9.91%, and T+C phase ≥96%. The nanoscale yttrium-stabilized zirconium powder provided by the present invention has high stability, high activity, and high toughness. The present invention also provides a preparation method with low production costs and a stable production process.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano powder materials, and in particular relates to a nano-scale yttrium-stabilized zirconium powder and a preparation method thereof. Background Art

[0002] Yttrium-stabilized zirconia (YSZ) powder has excellent physical and chemical properties such as high-temperature stability, high hardness, high wear resistance, high thermal conductivity, and high oxygen ion conductivity. It has important applications as a high-tech material in engineering ceramics, steel smelting, chemical corrosion protection equipment, photocatalysts, gas sensors, solid electrolyte materials, and biomedicine.

[0003] Currently, there are two main methods for preparing yttrium-stabilized zirconium powder: liquid phase co-precipitation and mechanical mixing. However, both methods have significant drawbacks, which restrict further improvement of material performance and large-scale application. The liquid-phase co-precipitation method has several drawbacks: a complex process with low yields, requiring multiple precipitation steps and repeated washing, which inevitably results in material loss and high production costs. Particle uniformity and stability are poor, and the reaction easily generates colloidal particles with a wide particle size distribution, making subsequent drying, calcination, and hot pressing difficult, severely impacting product uniformity and batch stability. Impurity control is difficult, limiting purity. The co-precipitation process easily introduces other ionic impurities that are difficult to completely remove, resulting in low product purity and impaired performance in harsh environments such as high temperature and high pressure. Environmental pressures and powder defects are also present. Ammonia is often used as a precipitant, releasing ammonia gas that pollutes the environment during calcination. The resulting powder is prone to hard agglomeration. High yttrium dosage leads to insufficient phase stability. Even with a high tetragonal + cubic phase (T+C phase) content (typically requiring >5% Y2O3), the final powder still has a T+C phase ratio of only approximately 75%, a crystal particle size of approximately 30-34 nm, an average flexural strength of 700-850 MPa, and a sintering shrinkage of as high as 25-30%, resulting in poor overall product stability.

[0004] Mechanical mixing method (high-energy ball milling): high energy consumption and high cost, relying on high-power ball milling equipment for long-term mechanical impact grinding, huge electricity consumption, pushing up production costs; powder performance controllability is poor, grinding process parameters (such as particle size and morphology) are difficult to accurately control, powder particle size distribution is wide, batch repeatability and performance stability are difficult to guarantee; equipment wear is serious, ball mills wear severely at high speeds, equipment life is short, maintenance is frequent, and operating costs are further increased.

[0005] Therefore, existing mainstream preparation technologies generally have problems such as lengthy process flow, high energy consumption, high cost, poor product purity and uniformity, poor batch stability, difficult particle size control, and environmental pollution risks.

[0006] CN110330333A discloses a method for preparing nano-scale yttrium-stabilized zirconia composite powder. The method adopts a sol-gel method combined with a hydrothermal reaction to prepare yttrium-stabilized zirconium. Agglomeration is easy to occur during the gelation process, and the particle size distribution is wide, which cannot be accurately controlled. Ammonium inorganic salts are added during the hydrothermal reaction, and ammonia is released during the drying process to pollute the environment, posing an environmental risk. In addition, the reactor used in the reaction is a special reactor, which has high construction and maintenance costs.

[0007] CN108546118A discloses a yttria-stabilized zirconia powder, a preparation method thereof, and a ceramic. A large amount of ethanol is used in the preparation process, which is easily volatile during the subsequent drying process and requires explosion-proof equipment, thereby increasing costs. Physical mixing of yttrium salt solution and ZrO2 particles makes it difficult to achieve uniform doping at the atomic level. Yttrium ions may only adhere to the surface of the particles, and local yttrium-rich or yttrium-poor areas are likely to appear after calcination, resulting in uneven crystal phases. The product particle size distribution range is relatively wide, and pores or cracks are easily generated during the firing process of the ceramic preparation. Summary of the Invention

[0008] The technical problem addressed by the present invention is to overcome the aforementioned deficiencies of the prior art by providing a nanoscale yttrium-stabilized zirconium powder with high stability, activity, strength, toughness, and oxidation resistance (the product's stability and high-strength properties are evident from its yttrium oxide content, T+C phase ratio, and flexural strength). The present invention also provides a method for preparing the nanoscale yttrium-stabilized zirconium powder, which offers low production costs and a stable production process.

[0009] The nano-sized yttrium-stabilized zirconium powder described in this invention has the following specifications: ZrO₂+HfO₂ ≥ 90%, Y₂O₃ 2.50-9.91%, and T+C phase ≥ 96%. The average grain size is 18-25 nm, and the average flexural strength is 890-998 MPa. The powder exhibits uniform particle size, compact sintering, and excellent performance.

[0010] The preparation method of the nano-scale yttrium-stabilized zirconium powder adopts a preparation process combining solid-phase mixing calcination with wet treatment, including: uniformly mixing zirconium oxychloride with yttrium oxide, aluminum oxide, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide, and subjecting the mixture to a high-temperature calcination to obtain a precursor powder; grinding the precursor powder once, removing impurities, spray drying, and subjecting the precursor powder to a second high-temperature calcination after drying; grinding and removing impurities from the obtained second calcined powder, adding additives, mixing uniformly, and spray granulating to obtain nano-scale yttrium-stabilized zirconium powder.

[0011] The addition amounts of yttrium oxide, aluminum oxide, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide are 0.95-3.96% (mass of yttrium oxide × 100% / (mass of yttrium oxide + mass of zirconium oxychloride)), 0.019-0.032% (mass of aluminum oxide × 100% / (mass of aluminum oxide + mass of zirconium oxychloride)), 0.005-0.015% (mass of copper oxide × 100% / (mass of copper oxide + mass of zirconium oxychloride)), and 0.00 5~0.015% (mass of magnesium oxide × 100% / (mass of magnesium oxide + mass of zirconium oxychloride)), 0.001~0.010% (mass of cerium oxide × 100% / (mass of cerium oxide + mass of zirconium oxychloride)), 0.001~0.010% (mass of calcium oxide × 100% / (mass of calcium oxide + mass of zirconium oxychloride)), 0.001~0.010% (mass of lanthanum oxide × 100% / (mass of lanthanum oxide + mass of zirconium oxychloride)).

[0012] The temperature of the first high-temperature calcination is 1000~1350℃, and the calcination time is 4~12h.

[0013] The precursor powder is ground once by ball milling, stirring milling, and sand milling to a particle size of D50 = 0.3~0.7μm.

[0014] The precursor powder is ground once, and the slurry high-strength magnetic pipeline iron remover is used for impurity removal, and the impurity removal time is 8 to 14 hours.

[0015] The precursor powder is ground once, impurities are removed, and spray dried. The spray drying adopts a spray drying tower. The inlet temperature of the spray drying tower is controlled at 230~260℃, and the outlet temperature is controlled at 120~150℃.

[0016] The secondary high-temperature calcination temperature is 1100~1300℃, and the calcination time is 8~12h.

[0017] The secondary grinding is carried out by sand grinding to a particle size of D50 = 0.2~0.4μm.

[0018] After secondary grinding and impurity removal, additives are added. The additives are a mixture of polyvinyl alcohol (PVA), polyethylene glycol, glycerol, and ammonium polyacrylate. After uniform mixing, spray granulation is performed. Spray granulation uses the same parameters as spray drying after primary grinding. Impurities are removed using a three-dimensional ultrasonic vibrating screen. In terms of mass percentage, the amount of polyvinyl alcohol added is 0.4-1.5% of the powder after impurity removal, the amount of polyethylene glycol added is 0.2-0.8% of the powder after impurity removal, the amount of glycerol added is 0.1-0.5% of the powder after impurity removal, and the amount of ammonium polyacrylate added is 0.1-0.5% of the powder after impurity removal.

[0019] Specifically, the method for preparing nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0020] (1) Mix zirconium oxychloride with a stabilizer, wherein the amount of yttrium oxide added as the stabilizer is 0.95-3.96%; the amount of aluminum oxide added is 0.019-0.032%; the amount of copper oxide added is 0.005-0.015%; the amount of magnesium oxide added is 0.005-0.015%; the amount of cerium oxide added is 0.001-0.010%; the amount of calcium oxide added is 0.001-0.010%; and the amount of lanthanum oxide added is 0.001-0.010%, and mix them evenly in a mixer.

[0021] (2) The mixed materials are calcined at a high temperature of 1000-1350°C for 4-12 hours to obtain a precursor powder.

[0022] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 is 0.3~0.7μm.

[0023] (4) The ground precursor powder is removed from the powder by a high-strength magnetic pipeline slurry remover. The removal time is 8 to 14 hours.

[0024] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation. The inlet temperature of the spray drying tower is controlled at 230~260℃, and the outlet temperature is controlled at 120~150℃.

[0025] (6) The powder obtained by the spray granulation is subjected to a secondary high-temperature calcination at a temperature of 1100-1300°C and a calcination time of 8-12 hours.

[0026] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 to 0.2~0.4μm.

[0027] (8) Add additives (0.4-1.5% polyvinyl alcohol (PVA), 0.2-0.8% polyethylene glycol, 0.1-0.5% propylene glycol, and 0.1-0.5% ammonium polyacrylate) to the powder after secondary grinding and impurity removal, mix well, and then spray granulate. The inlet temperature of the spray drying tower is controlled at 230-260°C, and the outlet temperature is controlled at 120-150°C to obtain nano-scale yttrium-stabilized zirconium powder.

[0028] The present invention uniformly mixes zirconium oxychloride with stabilizers yttrium oxide, aluminum oxide, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide in advance, and then melts the zirconium oxychloride at high temperature to convert the monoclinic zirconium oxide into tetragonal zirconium oxide. The conversion rate is high and the product activity is high. At the same time, after secondary calcination and grinding in the later stage, the content of the tetragonal phase can be further increased. At the same time, the product particle size is uniform during the grinding process, no other impurities are introduced during the entire process, the product purity is high, and the production equipment requirements are not high. The equipment loss rate during the production process is low, and the production cost is low. The present invention can obtain stable zirconium with a high T+C phase under the condition of adding a small amount of yttrium oxide, meeting the index requirements of stable zirconium powder.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The yttrium-stabilized zirconium powder prepared by the method of the present invention has ZrO2+HfO2≥90%, Y2O3=2.5~9.91%, T+C phase≥96%, an average crystal particle size of 18~25nm, an average bending strength of the powder of 890~998MPa, a sintering shrinkage of 12~20%, uniform powder particle size, high green strength, dense sintering, and good performance. The produced stabilized zirconium oxide has more advantages in sensors, functional ceramics, structural ceramics, solid electrolyte supplementary materials, etc.

[0031] (2) The method for preparing nano-scale yttrium-stabilized zirconium powder of the present invention has low requirements for production equipment, low equipment loss rate, and low production cost.

[0032] (3) The method for preparing nano-scale yttrium-stabilized zirconium powder of the present invention is simple to operate and is easy to mass-produce yttrium-stabilized zirconium powder, thereby reducing production costs, reducing the introduction of impurities during the production process, and improving the purity and reliability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The figure is a schematic diagram of the process flow for preparing the nano-scale yttrium-stabilized zirconium powder of the present invention.

[0034] Figure 2 This is the morphology of the nano-scale yttrium-stabilized zirconium powder prepared in Example 1.

[0035] Figure 3 This is the particle size distribution diagram of the nano-scale yttrium-stabilized zirconium powder prepared in Example 1. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to specific embodiments.

[0037] The raw materials and additives used in the following examples and comparative examples are all commercially available products. The zirconium oxychloride used in the following examples is prepared by reacting zircon sand with alkali, generally expressed as Zr(Hf)O2%, in which the Hf content accounts for 0.7%. Therefore, when using it as a raw material to prepare nano-scale yttrium-stabilized zirconium powder, it contains a small amount of Hf element. Figure 1 :Process flow chart; Figure 2 : Powder morphology; Figure 3 : Particle size distribution diagram.

[0038] Example 1

[0039] The method for preparing the nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0040] (1) 10t of zirconium oxychloride was mixed with a stabilizer, wherein the amount of yttrium oxide added was 412.33kg; the amount of aluminum oxide added was 1.90kg; the amount of copper oxide added was 0.50kg; the amount of magnesium oxide added was 0.50kg; the amount of cerium oxide added was 0.10kg; the amount of calcium oxide added was 0.10kg; and the amount of lanthanum oxide added was 0.10kg, and the mixture was mixed evenly in a mixer.

[0041] (2) The mixed materials are calcined at a high temperature of 1350°C for 12 hours to obtain a precursor powder.

[0042] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 = 0.3 μm.

[0043] (4) The ground precursor powder is removed from the powder by a slurry high-strength magnetic pipeline remover. The removal time is 8 hours.

[0044] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation, and the inlet temperature of the spray drying tower is controlled at 260°C and the outlet temperature is controlled at 150°C.

[0045] (6) The powder obtained by the spray granulation is subjected to a second high-temperature calcination at a temperature of 1250°C and a calcination time of 12 hours.

[0046] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 = 0.2 μm.

[0047] (8) The powder after secondary grinding was cleaned with a three-dimensional ultrasonic vibration screen, and then additives (0.6% polyvinyl alcohol (PVA), 0.4% polyethylene glycol, 0.3% propylene glycol, 0.3% ammonium polyacrylate, the percentages of which are the percentages of the mass of each additive to the mass of the powder after cleansing) were added and mixed well, and then spray granulation was performed. The inlet temperature of the spray drying tower was controlled at 260°C, and the outlet temperature was controlled at 150°C, thus obtaining a highly active yttrium-stabilized zirconium powder. The morphology thereof is shown in the figure below. Figure 2 As shown. Figure 3 It can be seen that the particle size of the prepared powder is uniform.

[0048] Example 2

[0049] The method for preparing the nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0050] (1) 10t of zirconium oxychloride was mixed with a stabilizer, wherein the amount of yttrium oxide added was 319.92kg; the amount of aluminum oxide added was 2.10kg; the amount of copper oxide added was 0.60kg; the amount of magnesium oxide added was 0.60kg; the amount of cerium oxide added was 0.20kg; the amount of calcium oxide added was 0.80kg; and the amount of lanthanum oxide added was 0.20kg, and the mixture was mixed evenly in a mixer.

[0051] (2) The mixed materials are calcined at a high temperature of 1300°C for 10 hours to obtain a precursor powder.

[0052] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 = 0.4 μm.

[0053] (4) The ground precursor powder is removed from the powder by a slurry high-strength magnetic pipeline iron remover, and the removal time is 10 hours.

[0054] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation, and the inlet temperature of the spray drying tower is controlled at 250°C and the outlet temperature is controlled at 140°C.

[0055] (6) The powder obtained by the spray granulation is subjected to a second high-temperature calcination at a temperature of 1200°C and a calcination time of 10 h.

[0056] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 = 0.3 μm.

[0057] (8) The powder after secondary grinding is cleaned with a three-dimensional ultrasonic vibrating screen, and then additives (0.4% polyvinyl alcohol (PVA), 0.8% polyethylene glycol, 0.5% propylene glycol, 0.1% ammonium polyacrylate, the percentages being the mass of each additive relative to the mass of the powder after cleansing) are added and mixed, and then spray granulation is performed. The inlet temperature of the spray drying tower is controlled at 250°C, and the outlet temperature is controlled at 140°C, thereby obtaining a highly active yttrium-stabilized zirconium powder.

[0058] Example 3

[0059] The method for preparing the nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0060] (1) 10t of zirconium oxychloride was mixed with a stabilizer, wherein the amount of yttrium oxide added was 270.10kg; the amount of aluminum oxide added was 2.30kg; the amount of copper oxide added was 0.80kg; the amount of magnesium oxide added was 0.80kg; the amount of cerium oxide added was 0.40kg; the amount of calcium oxide added was 1.00kg; and the amount of lanthanum oxide added was 0.40kg, and the mixture was mixed evenly in a mixer.

[0061] (2) The mixed materials are calcined at a high temperature of 1000°C for 4 hours to obtain a precursor powder.

[0062] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 = 0.5 μm.

[0063] (4) The ground precursor powder is removed from the powder by a slurry high-strength magnetic pipeline remover. The removal time is 12 hours.

[0064] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation, and the inlet temperature of the spray drying tower is controlled at 260°C and the outlet temperature is controlled at 120°C.

[0065] (6) The powder obtained by the spray granulation was subjected to a secondary high-temperature calcination at a temperature of 1300°C and a calcination time of 11 h.

[0066] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 = 0.4 μm.

[0067] (8) The powder after secondary grinding is cleaned with a three-dimensional ultrasonic vibrating screen, and then additives (1.5% polyvinyl alcohol (PVA), 0.2% polyethylene glycol, 0.1% propylene glycol, 0.5% ammonium polyacrylate, the percentages being the mass of each additive relative to the mass of the powder after cleansing) are added and mixed, and then spray granulation is performed. The inlet temperature of the spray drying tower is controlled at 260°C, and the outlet temperature is controlled at 120°C, thereby obtaining a highly active yttrium-stabilized zirconium powder.

[0068] Example 4

[0069] The method for preparing the nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0070] (1) 10t of zirconium oxychloride was mixed with a stabilizer, wherein the amount of yttrium oxide added was 230.18kg; the amount of aluminum oxide added was 2.50kg; the amount of copper oxide added was 1.00kg; the amount of magnesium oxide added was 1.00kg; the amount of cerium oxide added was 0.60kg; the amount of calcium oxide added was 0.20kg; and the amount of lanthanum oxide added was 0.60kg, and the mixture was mixed evenly in a mixer.

[0071] (2) The mixed materials are calcined at a high temperature of 1100°C for 8 hours to obtain a precursor powder.

[0072] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 = 0.6 μm.

[0073] (4) The ground precursor powder is removed from the powder by a slurry high-strength magnetic pipeline remover. The removal time is 14 hours.

[0074] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation, and the inlet temperature of the spray drying tower is controlled at 240°C and the outlet temperature is controlled at 150°C.

[0075] (6) The powder obtained by the spray granulation is subjected to a second high-temperature calcination at a temperature of 1150°C and a calcination time of 12 h.

[0076] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 = 0.4 μm.

[0077] (8) The powder after secondary grinding was cleaned with a three-dimensional ultrasonic vibrating screen, and then additives (1.0% polyvinyl alcohol (PVA), 0.6% polyethylene glycol, 0.2% propylene glycol, 0.2% ammonium polyacrylate, the percentages being the mass of each additive relative to the mass of the powder after cleansing) were added and mixed, and then spray granulation was performed. The inlet temperature of the spray drying tower was controlled at 240°C, and the outlet temperature was controlled at 150°C, thereby obtaining a highly active yttrium-stabilized zirconium powder.

[0078] Example 5

[0079] The method for preparing the nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0080] (1) 10t of zirconium oxychloride was mixed with a stabilizer, wherein the amount of yttrium oxide added was 189.53kg; the amount of aluminum oxide added was 2.70kg; the amount of copper oxide added was 1.20kg; the amount of magnesium oxide added was 1.20kg; the amount of cerium oxide added was 0.70kg; the amount of calcium oxide added was 0.40kg; and the amount of lanthanum oxide added was 0.70kg, and the mixture was mixed evenly in a mixer.

[0081] (2) The mixed materials are calcined at a high temperature of 1150°C for 10 hours to obtain a precursor powder.

[0082] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 = 0.7 μm.

[0083] (4) The ground precursor powder is removed from the powder by a slurry high-strength magnetic pipeline remover. The removal time is 8 hours.

[0084] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation, and the inlet temperature of the spray drying tower is controlled at 230°C and the outlet temperature is controlled at 140°C.

[0085] (6) The powder obtained by the spray granulation is subjected to a second high-temperature calcination at a temperature of 1200°C and a calcination time of 9 hours.

[0086] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 to 0.3 μm.

[0087] (8) The powder after secondary grinding was removed by a three-dimensional ultrasonic vibrating screen, and then additives (0.6% polyvinyl alcohol (PVA), 0.4% polyethylene glycol, 0.3% propylene glycol, and 0.3% ammonium polyacrylate) were added and mixed, and then spray granulation was performed. The inlet temperature of the spray drying tower was controlled at 230°C, and the outlet temperature was controlled at 140°C, thereby obtaining a highly active yttrium-stabilized zirconium powder.

[0088] Example 6

[0089] The method for preparing the nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0090] (1) 10t of zirconium oxychloride was mixed with a stabilizer, wherein the amount of yttrium oxide added was 150.22kg; the amount of aluminum oxide added was 2.90kg; the amount of copper oxide added was 1.30kg; the amount of magnesium oxide added was 1.50kg; the amount of cerium oxide added was 0.90kg; the amount of calcium oxide added was 0.60kg; and the amount of lanthanum oxide added was 0.90kg, and the mixture was mixed evenly in a mixer.

[0091] (2) The mixed materials are calcined at a high temperature of 1200°C for 12 hours to obtain a precursor powder.

[0092] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 = 0.6 μm.

[0093] (4) The ground precursor powder is removed from the powder by a slurry high-strength magnetic pipeline remover. The removal time is 12 hours.

[0094] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation, and the inlet temperature of the spray drying tower is controlled at 250°C and the outlet temperature is controlled at 130°C.

[0095] (6) The powder obtained by the spray granulation was subjected to a secondary high-temperature calcination at a temperature of 1150°C and a calcination time of 11 hours.

[0096] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 = 0.3 μm.

[0097] (8) The powder after secondary grinding is removed by a three-dimensional ultrasonic vibrating screen, and then additives (0.6% polyvinyl alcohol (PVA), 0.4% polyethylene glycol, 0.3% propylene glycol, 0.3% ammonium polyacrylate, the percentages of which are the percentages of the mass of each additive to the mass of the powder after impurities are removed) are added and mixed, and then spray granulation is performed. The inlet temperature of the spray drying tower is controlled at 250°C, and the outlet temperature is controlled at 130°C, thereby obtaining a high-activity yttrium-stabilized zirconium powder.

[0098] Example 7

[0099] The method for preparing the nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0100] (1) 10t of zirconium oxychloride was mixed with a stabilizer, wherein the amount of yttrium oxide added was 110.20kg; the amount of aluminum oxide added was 3.00kg; the amount of copper oxide added was 1.40kg; the amount of magnesium oxide added was 1.30kg; the amount of cerium oxide added was 1.00kg; the amount of calcium oxide added was 0.70kg; and the amount of lanthanum oxide added was 1.00kg, and the mixture was mixed evenly in a mixer.

[0101] (2) The mixed materials are calcined at a high temperature of 1250°C for 6 hours to obtain a precursor powder.

[0102] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 = 0.4 μm.

[0103] (4) The ground precursor powder is removed from the powder by a slurry high-strength magnetic pipeline remover. The removal time is 14 hours.

[0104] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation, and the inlet temperature of the spray drying tower is controlled at 240°C and the outlet temperature is controlled at 120°C.

[0105] (6) The powder obtained by the spray granulation is subjected to a second high-temperature calcination at a temperature of 1100°C and a calcination time of 10 h.

[0106] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 = 0.2 μm.

[0107] (8) The powder after secondary grinding is cleaned with a three-dimensional ultrasonic vibrating screen, and then additives (0.6% polyvinyl alcohol (PVA), 0.4% polyethylene glycol, 0.3% propylene glycol, 0.3% ammonium polyacrylate, the percentages of which are the percentages of the mass of each additive to the mass of the powder after cleansing) are added and mixed, and then spray granulation is performed. The inlet temperature of the spray drying tower is controlled at 240°C, and the outlet temperature is controlled at 120°C, thereby obtaining high-activity yttrium-stabilized zirconium powder.

[0108] Example 8

[0109] The method for preparing the nano-scale yttrium-stabilized zirconium powder comprises the following steps:

[0110] (1) 10t of zirconium oxychloride was mixed with a stabilizer, wherein the amount of yttrium oxide added was 95.91kg; the amount of aluminum oxide added was 3.20kg; the amount of copper oxide added was 1.50kg; the amount of magnesium oxide added was 1.40kg; the amount of cerium oxide added was 0.80kg; the amount of calcium oxide added was 0.90kg; and the amount of lanthanum oxide added was 0.80kg, and the mixture was mixed evenly in a mixer.

[0111] (2) The mixed materials are calcined at a high temperature of 1000°C for 10 hours to obtain a precursor powder.

[0112] (3) The precursor powder is subjected to ball milling, stirring milling, and sand milling (one-time grinding) to ensure that the precursor powder particle size D50 = 0.3 μm.

[0113] (4) The ground precursor powder is removed from the powder by a slurry high-strength magnetic pipeline iron remover, and the removal time is 10 hours.

[0114] (5) The precursor powder after impurity removal is subjected to high-temperature spray granulation, and the inlet temperature of the spray drying tower is controlled at 230°C and the outlet temperature is controlled at 150°C.

[0115] (6) The powder obtained by the spray granulation is subjected to a second high-temperature calcination at a temperature of 1250°C and a calcination time of 8 hours.

[0116] (7) The secondary calcined powder is sand-milled (secondary grinding) to control the particle size D50 = 0.2 μm.

[0117] (8) The powder after secondary grinding was cleaned with a three-dimensional ultrasonic vibrating screen, and then additives (0.6% polyvinyl alcohol (PVA), 0.4% polyethylene glycol, 0.3% propylene glycol, 0.3% ammonium polyacrylate, the percentages being the mass of each additive relative to the mass of the powder after cleansing) were added and mixed, and then spray granulation was performed. The inlet temperature of the spray drying tower was controlled at 230°C, and the outlet temperature was controlled at 150°C, thereby obtaining a highly active yttrium-stabilized zirconium powder.

[0118] Comparative Example 1

[0119] Preparation of an unstabilized zirconium oxide powder: The difference between this comparative example and Example 1 is that yttrium oxide is not added in step (1), the amount of zirconium oxychloride is increased accordingly to maintain the total material amount, and the other preparation processes are the same to obtain an unstabilized zirconium oxide powder.

[0120] The zirconium oxide powder produced by this method will crack during the green body preparation process.

[0121] Comparative Example 2

[0122] This comparative example is the same as steps (1) to (5) in Example 1. After the first spray granulation is completed, secondary grinding and impurity removal are directly carried out, and the same additives as in Example 1 are added to carry out spray granulation again.

[0123] Comparative Example 3

[0124] This comparative example is the same as steps (1) to (6) in Example 1, except that the secondary grinding particle size is controlled to D50 = 0.5 μm and impurities are removed, and the same additives as in Example 1 are added for spray granulation again.

[0125] The test indicators of the powders prepared in the above examples and comparative examples are shown in Table 1. The powders were dry pressed and then isostatically pressed at a pressure of 150 MPa for 2 minutes to obtain green compacts. The strength of the green compacts is shown in Table 1. The green compacts were sintered at 1430°C for 2 hours to obtain sintered bodies. The test results of the sintered bodies are shown in Table 1.

[0126] The average crystal grain size was determined using X-ray diffraction at a starting angle of 25°, an ending angle of 32.5°, a scanning speed of 1° / min, a copper target, a current of 30 mA, and a voltage of 50 kV. Individual components were determined using fluorescence X-ray diffraction. T+C phase was determined using X-ray diffraction at a starting angle of 26°, an ending angle of 38°, a scanning speed of 4° / min, a copper target, a tube current of 30 mA, and a tube voltage of 50 kV. The finished product density and shrinkage were measured and calculated using a two-dimensional high-speed dimensional analyzer and a solid specific gravity meter. The average flexural strength of the sintered body was determined and calculated using a press, sintering furnace, grinder, cutter, surface cutter, and strength meter.

[0127] Table 1 Test results

[0128]

[0129] It can be seen from the above that the nano-scale yttrium-stabilized zirconium powder prepared by the method of the present invention has uniform particles and high purity, and the sintered body prepared by using the same has good product stability and good mechanical properties.

Claims

1. A method for preparing nano-scale yttrium-stabilized zirconium powder, characterized in that: The preparation process comprises the following steps: uniformly mixing zirconium oxychloride with yttrium oxide, aluminum oxide, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide, and subjecting the mixture to a primary high-temperature calcination at 1000-1350°C to obtain a precursor powder; subjecting the precursor powder to a primary grinding process to a particle size D50 of 0.3-0.7 μm, removing impurities, and spray drying; and subjecting the dried precursor powder to a secondary high-temperature calcination process at 1100-1300°C to secondary grinding and impurity removal of the obtained secondary calcined powder to a particle size D50 of 0.2-0.4 μm; and then adding an additive, uniformly mixing the mixture, and spray granulating the mixture to obtain a nano-scale yttrium-stabilized zirconium powder. The additive is a mixture of polyvinyl alcohol, polyethylene glycol, glycerol, and ammonium polyacrylate. The powder has the following indicators: ZrO2+HfO2≥90%, Y2O3=2.50~9.91%, and T+C phase≥96%.

2. The method for preparing nano-scale yttrium-stabilized zirconium powder according to claim 1, wherein: The added amounts of yttrium oxide, aluminum oxide, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide are 0.95-3.96%, 0.019-0.032%, 0.005-0.015%, 0.005-0.015%, 0.001-0.010%, 0.001-0.010%, and 0.001-0.010%, respectively, where the percentage is the percentage of the mass of each oxide to the sum of its own mass and the mass of zirconium oxychloride.

3. The method for preparing nano-scale yttrium-stabilized zirconium powder according to claim 1, wherein: The high-temperature calcination time is 4 to 12 hours.

4. The method for preparing nano-scale yttrium-stabilized zirconium powder according to claim 3, characterized in that: The precursor powder is ground once by ball milling, stirred milling and sand milling.

5. The method for preparing nano-scale yttrium-stabilized zirconium powder according to claim 4, characterized in that: The precursor powder is ground once, and the slurry high-strength magnetic pipeline iron remover is used for impurity removal, and the impurity removal time is 8 to 14 hours.

6. The method for preparing nano-scale yttrium-stabilized zirconium powder according to claim 5, characterized in that: The precursor powder is ground once, impurities are removed, and spray dried. The spray drying adopts a spray drying tower. The inlet temperature of the spray drying tower is controlled at 230~260℃, and the outlet temperature is controlled at 120~150℃.

7. The method for preparing nano-scale yttrium-stabilized zirconium powder according to claim 1, characterized in that: The secondary high-temperature calcination time is 8~12h.

8. The method for preparing nano-scale yttrium-stabilized zirconium powder according to claim 7, characterized in that: The secondary grinding is done by sand grinding.

9. The method for preparing nano-scale yttrium-stabilized zirconium powder according to claim 8, characterized in that: Secondary grinding and impurity removal are carried out using a three-dimensional ultrasonic vibrating screen.

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