Nanoscale yttrium-stabilized zirconium powder and preparation method thereof

Abstract

The invention belongs to the technical field of nano powder materials, and particularly relates to nanoscale yttrium-stabilized zirconium powder and a preparation method thereof. The preparation method of the nanoscale yttrium-stabilized zirconium powder 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 carrying out primary high-temperature calcination to obtain precursor powder; and performing primary grinding, impurity removal and spray drying on the precursor powder, performing secondary high-temperature calcination after drying to obtain secondary calcined powder, performing secondary grinding and impurity removal on the secondary calcined powder, adding an additive, uniformly mixing, and performing spray granulation to obtain the nanoscale yttrium-stabilized zirconium powder. According to the nanoscale yttrium-stabilized zirconium powder, ZrO2 + HfO2 is larger than or equal to 90%, Y2O3 is 2.50-9.91%, and T + C phase is larger than or equal to 96%. The nanoscale yttrium-stabilized zirconium powder provided by the invention is high in stability, high in activity and high in toughness. The invention also provides the preparation method, the production cost is low, and the production process is stable.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano-powder materials, and particularly relates to a nano-sized yttrium-stabilized zirconia 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, and has important applications as a high-tech material in the fields of engineering ceramics, iron and steel smelting, chemical corrosion prevention equipment, photocatalysts, gas sensors, solid electrolyte materials, and biomedicine.

[0003] Currently, there are mainly two methods for preparing yttrium-stabilized zirconia powder: the liquid-phase co-precipitation method and the mechanical mixing method. However, both of these methods have significant defects, which restrict the further improvement of material properties and large-scale applications. Defects of the liquid-phase co-precipitation method: The process is complex and the yield is low. It requires multiple steps of precipitation and repeated washing. Inevitably, material loss occurs during the process, resulting in high production costs; the particle uniformity and stability are poor. The reaction is prone to generate colloidal particles, and the particle size distribution is wide, making subsequent drying, calcination, and hot pressing difficult, seriously affecting the uniformity and batch stability of the product; it is difficult to control impurities and the purity is limited. Other ionic impurities are easily introduced during the co-precipitation process and are difficult to completely remove, resulting in low product purity and weakening its service performance in harsh environments such as high temperature and high pressure; environmental protection pressure and powder defects. Ammonia water is commonly used as a precipitant, and ammonia gas is released during calcination, polluting the environment; the obtained powder is prone to hard agglomeration; the yttrium dosage is high while the phase stability is insufficient. To obtain a higher content of tetragonal + cubic phase (T + C phase) (usually > 5% Y2O3), the T + C phase ratio of the final powder is still only about 75%, the crystallite size is about 30 - 34 nm, the average flexural strength is 700 - 850 MPa, and the sintering shrinkage rate is as high as 25 - 30%. The comprehensive stability of the product is poor.

[0004] Mechanical mixing method (high-energy ball milling method): High energy consumption and high cost. It relies on high-power ball milling equipment for long-term mechanical impact grinding, consuming a large amount of electric energy and driving up production costs; the controllability of powder properties is poor. The parameters during the grinding process (such as particle size and morphology) are difficult to accurately control, the powder particle size distribution is wide, and the batch repeatability and performance stability are difficult to guarantee; the equipment loss is serious. The ball mill wears severely during high-speed operation, the equipment life is short, and maintenance is frequent, further increasing the operating cost.

[0005] Therefore, the existing mainstream preparation technologies generally have problems such as long 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-sized yttrium-stabilized zirconia composite powder. The method combines sol-gel and hydrothermal reactions to prepare yttrium-stabilized zirconia. Agglomeration easily occurs during the gel process, resulting in a wide particle size distribution and inaccurate control. Ammonium inorganic salts are added during the hydrothermal reaction, and ammonia is released during the drying process, polluting the environment and posing an environmental protection risk. In addition, the reaction kettle used in this reaction is a special reaction kettle, with high manufacturing and maintenance costs.

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

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned defects existing in the prior art, and provide a nano-sized yttrium-stabilized zirconia powder with high stability, high activity, high strength and high toughness, and having antioxidant properties (the stability and high strength performance of the product can be seen from the yttrium oxide content, the proportion of T+C phase and the flexural strength). The present invention also provides a preparation method for the nano-sized yttrium-stabilized zirconia powder, with low production costs and stable production processes.

[0009] The nano-sized yttrium-stabilized zirconia powder described in the present invention has the following indicators: ZrO2+HfO2≥90%, Y2O3 = 2.50~9.91%, T+C phase≥96%. The average grain size is 18~25nm, the average flexural strength of the powder is 890~998MPa, the particle size of the powder is uniform, sintering is dense, and the powder properties are good.

[0010] The preparation method of the nano-sized yttrium-stabilized zirconia powder adopts a preparation process combining solid-phase mixing calcination and wet processing, including: uniformly mixing zirconium oxychloride with yttrium oxide, aluminum oxide, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide, and performing a first high-temperature calcination to obtain a precursor powder; performing a first grinding on the precursor powder, removing impurities, spray drying, performing a second high-temperature calcination on the dried powder to obtain a second calcined powder, performing a second grinding and removing impurities, adding additives, mixing uniformly, and spray granulating to obtain the nano-sized yttrium-stabilized zirconia 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)), 0.005 - 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)), and 0.001 - 0.010% (mass of lanthanum oxide × 100% / (mass of lanthanum oxide + mass of zirconium oxychloride)), respectively.

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

[0013] The precursor powder is ground for the first time by means of ball milling, stirred milling, or sand milling until the particle size D50 = 0.3 - 0.7 μm.

[0014] The precursor powder is ground for the first time, and the impurity removal is carried out by a high-strength magnetic pipeline iron remover for slurry, and the impurity removal time is 8 - 14 h.

[0015] The precursor powder is ground for the first time, then impurity removal and spray drying are carried out. Spray drying is carried out using a spray drying tower. The inlet temperature of the spray drying tower is controlled at 230 - 260 °C, and the outlet temperature is controlled at 120 - 150 °C.

[0016] The temperature of the second high-temperature calcination is 1100 - 1300 °C, and the calcination time is 8 - 12 h.

[0017] The second grinding is carried out by sand milling until the particle size is D50 = 0.2 - 0.4 μm.

[0018] After the second grinding and impurity removal, additives are added. The additives are a mixture of polyvinyl alcohol PVA, polyethylene glycol, glycerol, and ammonium polyacrylate. After mixing evenly, spray granulation is carried out. The parameters of spray granulation are the same as those of the spray drying after the first grinding. Impurity removal is carried out using a three-dimensional ultrasonic vibrating screen. Among them, according to the mass percentage, the addition amount of polyvinyl alcohol is 0.4 - 1.5% of the powder after impurity removal, the addition amount of polyethylene glycol is 0.2 - 0.8% of the powder after impurity removal, the addition amount of glycerol is 0.1 - 0.5% of the powder after impurity removal, and the addition amount of ammonium polyacrylate is 0.1 - 0.5% of the powder after impurity removal.

[0019] Specifically, the method for preparing the nanoscale yttrium-stabilized zirconia powder includes the following steps: (1) Mix zirconium oxychloride with stabilizers. The addition amount of yttrium oxide as the stabilizer is 0.95 - 3.96%; the addition amount of alumina is 0.019 - 0.032%; the addition amount of copper oxide is 0.005 - 0.015%; the addition amount of magnesium oxide is 0.005 - 0.015%; the addition amount of cerium oxide is 0.001 - 0.010%; the addition amount of calcium oxide is 0.001 - 0.010%; the addition amount of lanthanum oxide is 0.001 - 0.010%. Mix them evenly with a mixer.

[0020] (2) Calcinate the above - mixed materials at a high temperature. The calcination temperature is 1000 - 1350 °C and the calcination time is 4 - 12 h to obtain precursor powder.

[0021] (3) Grind, stir - grind, and sand - grind (primary grinding) the above precursor powder to ensure that the particle size D50 of the precursor powder is 0.3 - 0.7 μm.

[0022] (4) Remove impurities from the ground precursor powder. The impurity - removing device used is a high - strength magnetic pipeline iron remover for slurry, and the impurity - removing time is 8 - 14 h.

[0023] (5) Perform high - temperature spray granulation on the impurity - removed precursor powder. Control the inlet temperature of the spray - drying tower at 230 - 260 °C and the outlet temperature at 120 - 150 °C.

[0024] (6) Perform secondary high - temperature calcination on the powder obtained by the above spray granulation. The secondary calcination temperature is 1100 - 1300 °C and the calcination time is 8 - 12 h.

[0025] (7) Sand - grind (secondary grinding) the above secondary - calcined powder to control the particle size D50 at 0.2 - 0.4 μm.

[0026] (8) Add additives (0.4 - 1.5% polyvinyl alcohol PVA, 0.2 - 0.8% polyethylene glycol, 0.1 - 0.5% glycerol, 0.1 - 0.5% ammonium polyacrylate) to the powder after the above secondary grinding and impurity removal, mix them evenly, and then perform spray granulation. Control the inlet temperature of the spray - drying tower at 230 - 260 °C and the outlet temperature at 120 - 150 °C to obtain nano - sized yttrium - stabilized zirconium powder.

[0027] In the present invention, zirconium oxychloride is uniformly mixed with stabilizers such as yttrium oxide, alumina, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide in advance, and then through high-temperature melting, monoclinic zirconia is transformed into tetragonal zirconia, with a high conversion rate and high product activity. At the same time, through secondary calcination and grinding in the later stage, the content of the tetragonal phase can be further increased. Meanwhile, during the grinding process, the product has uniform particle size, no other impurities are introduced in the whole technological process, the product has high purity, the requirements for production equipment are not high, the equipment loss rate is low during the production process, and the production cost is low. The present invention can obtain high-T+C-phase stabilized zircon by adding a small amount of yttrium oxide, meeting the index requirements of stabilized zircon powder.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The yttrium-stabilized zircon powder prepared by the method of the present invention has ZrO2+HfO2≥90%, Y2O3=2.5~9.91%, T+C phase≥96%, the average crystal particle size is 18~25nm, the average flexural strength of the powder is 890~998MPa, the sintering shrinkage rate is 12~20%, the powder has uniform particle size, high green strength, dense sintering, good performance, and the produced stabilized zirconia has more advantages in aspects such as sensors, functional ceramics, structural ceramics, and solid electrolyte supplementary materials.

[0029] (2) The preparation method of the nanoscale yttrium-stabilized zircon powder of the present invention has low requirements for production equipment, low equipment loss rate, and low production cost.

[0030] (3) The preparation method of the nanoscale yttrium-stabilized zircon powder of the present invention is simple to operate, is easy to produce yttrium-stabilized zircon powder on a large scale, reduces the production cost, reduces the introduction of impurities during the production process, and improves the purity and reliability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic process flow diagram for the preparation of the nanoscale yttrium-stabilized zircon powder of the present invention.

[0032] Figure 2 It is a morphology diagram of the nanoscale yttrium-stabilized zircon powder prepared in Example 1.

[0033] Figure 3 It is a particle size distribution diagram of the nanoscale yttrium-stabilized zircon powder prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention will be further described below in conjunction with specific embodiments.

[0035] The raw materials and auxiliaries 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%, and the Hf content is 0.7%. Therefore, when using it as a raw material to prepare nano-sized yttrium-stabilized zirconium powder, it contains a small amount of Hf element. As Figure 1 : Process flow chart; Figure 2 : Powder morphology diagram; Figure 3 : Particle size distribution diagram.

[0036] Example 1 The preparation method of the nano-sized yttrium-stabilized zirconium powder includes the following steps: (1) Mix 10 t of zirconium oxychloride with stabilizers. The addition amount of yttrium oxide as the stabilizer is 412.33 kg; the addition amount of alumina is 1.90 kg; the addition amount of copper oxide is 0.50 kg; the addition amount of magnesium oxide is 0.50 kg; the addition amount of cerium oxide is 0.10 kg; the addition amount of calcium oxide is 0.10 kg; the addition amount of lanthanum oxide is 0.10 kg, and mix evenly through a mixer.

[0037] (2) Calcinate the above-mentioned uniformly mixed materials at a high temperature. The calcination temperature is 1350 °C and the calcination time is 12 h to obtain a precursor powder.

[0038] (3) Grind, stir and sand the above-mentioned precursor powder (primary grinding) to ensure that the particle size D50 of the precursor powder is 0.3 μm.

[0039] (4) Remove impurities from the ground precursor powder. The impurity removal device used is a slurry high-intensity magnetic pipe iron remover, and the impurity removal time is 8 h.

[0040] (5) Perform high-temperature spray granulation on the impurity-removed precursor powder. The inlet temperature of the spray drying tower is controlled at 260 °C, and the outlet temperature is controlled at 150 °C.

[0041] (6) Perform secondary high-temperature calcination on the powder obtained by the above spray granulation. The secondary calcination temperature is 1250 °C and the calcination time is 12 h.

[0042] (7) Sand the above-mentioned secondarily calcined powder (secondary grinding) to control the particle size D50 = 0.2 μm.

[0043] (8) Use a three-dimensional ultrasonic vibrating sieve to remove impurities from the powder after the above secondary grinding, then add additives (0.6% polyvinyl alcohol PVA, 0.4% polyethylene glycol, 0.3% glycerol, 0.3% ammonium polyacrylate, and the percentages are all the mass percentages of each additive in the powder after impurity removal), mix evenly and then perform spray granulation. The inlet temperature of the spray drying tower is controlled at 260 °C, and the outlet temperature is controlled at 150 °C to obtain a highly active yttrium-stabilized zirconium powder, and its morphology diagram is asFigure 2 As shown in Figure 3 It can be seen that the particle size of the prepared powder is uniform.

[0044] Example 2 The method for preparing the nanoscale yttrium-stabilized zirconia powder described above includes the following steps: (1) Mix 10 t of zirconium oxychloride with stabilizers. The added amount of yttrium oxide as the stabilizer is 319.92 kg; the added amount of alumina is 2.10 kg; the added amount of copper oxide is 0.60 kg; the added amount of magnesium oxide is 0.60 kg; the added amount of cerium oxide is 0.20 kg; the added amount of calcium oxide is 0.80 kg; the added amount of lanthanum oxide is 0.20 kg, and mix evenly through a mixer.

[0045] (2) Calcinate the above-mentioned uniformly mixed materials at a high temperature. The calcination temperature is 1300 °C and the calcination time is 10 h to obtain a precursor powder.

[0046] (3) Grind, stir and sand the above-mentioned precursor powder (primary grinding) to ensure that the particle size D50 of the precursor powder is 0.4 μm.

[0047] (4) Remove impurities from the ground precursor powder. The impurity removal device used is a high-strength magnetic pipeline iron remover for slurry, and the impurity removal time is 10 h.

[0048] (5) Subject the impurity-removed precursor powder to high-temperature spray granulation. The inlet temperature of the spray drying tower is controlled at 250 °C and the outlet temperature is controlled at 140 °C.

[0049] (6) Subject the powder obtained by the above spray granulation to secondary high-temperature calcination. The secondary calcination temperature is 1200 °C and the calcination time is 10 h.

[0050] (7) Sand the above-mentioned secondary calcined powder (secondary grinding) to control the particle size D50 = 0.3 μm.

[0051] (8) Use a three-dimensional ultrasonic vibrating sieve to remove impurities from the powder after the above secondary grinding, then add additives (0.4% polyvinyl alcohol PVA, 0.8% polyethylene glycol, 0.5% glycerol, 0.1% ammonium polyacrylate, and the percentages are all the mass percentages of each additive in the powder after impurity removal), mix evenly and then perform spray granulation. The inlet temperature of the spray drying tower is controlled at 250 °C and the outlet temperature is controlled at 140 °C to obtain a highly active yttrium-stabilized zirconia powder.

[0052] Example 3 The method for preparing the nanoscale yttrium-stabilized zirconia powder described above includes the following steps: (1) Mix 10 t of zirconium oxychloride with stabilizers. The addition amount of yttrium oxide as the stabilizer is 270.10 kg; the addition amount of alumina is 2.30 kg; the addition amount of copper oxide is 0.80 kg; the addition amount of magnesium oxide is 0.80 kg; the addition amount of cerium oxide is 0.40 kg; the addition amount of calcium oxide is 1.00 kg; the addition amount of lanthanum oxide is 0.40 kg, and mix evenly through a mixer.

[0053] (2) Calcinate the above-mentioned evenly mixed material at a high temperature. The calcination temperature is 1000 °C and the calcination time is 4 h to obtain a precursor powder.

[0054] (3) Grind, stir-grind, and sand-grind (primary grinding) the above-mentioned precursor powder to ensure that the particle size D50 of the precursor powder is 0.5 μm.

[0055] (4) Remove impurities from the ground precursor powder. The impurity removal device used is a high-strength magnetic pipeline iron remover for slurry, and the impurity removal time is 12 h.

[0056] (5) Perform high-temperature spray granulation on the precursor powder after impurity removal. Control the inlet temperature of the spray drying tower at 260 °C and the outlet temperature at 120 °C.

[0057] (6) Perform secondary high-temperature calcination on the powder obtained by the above spray granulation. The secondary calcination temperature is 1300 °C and the calcination time is 11 h.

[0058] (7) Sand-grind (secondary grinding) the powder after the above secondary calcination to control the particle size D50 = 0.4 μm.

[0059] (8) Use a three-dimensional ultrasonic vibrating sieve to remove impurities from the powder after the above secondary grinding, then add additives (1.5% polyvinyl alcohol PVA, 0.2% polyethylene glycol, 0.1% glycerol, 0.5% ammonium polyacrylate, and the percentages are all the mass percentages of each additive in the powder after impurity removal), mix evenly and then perform spray granulation. Control the inlet temperature of the spray drying tower at 260 °C and the outlet temperature at 120 °C to obtain a highly active yttrium-stabilized zirconia powder.

[0060] Example 4 The method for preparing the nanoscale yttrium-stabilized zirconia powder described above includes the following steps: (1) Mix 10 t of zirconium oxychloride with stabilizers. The addition amount of yttrium oxide as the stabilizer is 230.18 kg; the addition amount of alumina is 2.50 kg; the addition amount of copper oxide is 1.00 kg; the addition amount of magnesium oxide is 1.00 kg; the addition amount of cerium oxide is 0.60 kg; the addition amount of calcium oxide is 0.20 kg; the addition amount of lanthanum oxide is 0.60 kg, and mix evenly through a mixer.

[0061] (2) Calcinate the above-mentioned uniformly mixed materials at a high temperature. The calcination temperature is 1100 °C and the calcination time is 8 h to obtain the precursor powder.

[0062] (3) Grind, stir and sand the above-mentioned precursor powder (primary grinding) to ensure that the particle size D50 of the precursor powder is 0.6 μm.

[0063] (4) Remove impurities from the ground precursor powder. The impurity removal device used is a high-strength magnetic pipeline iron remover for slurry, and the impurity removal time is 14 h.

[0064] (5) Perform high-temperature spray granulation on the precursor powder after impurity removal. Control the inlet temperature of the spray drying tower at 240 °C and the outlet temperature at 150 °C.

[0065] (6) Perform secondary high-temperature calcination on the powder obtained by the above spray granulation. The secondary calcination temperature is 1150 °C and the calcination time is 12 h.

[0066] (7) Sand the above-mentioned powder after secondary calcination (secondary grinding) to control the particle size D50 = 0.4 μm.

[0067] (8) Remove impurities from the powder after the above secondary grinding using a three-dimensional ultrasonic vibrating screen, then add additives (1.0% polyvinyl alcohol PVA, 0.6% polyethylene glycol, 0.2% glycerol, 0.2% ammonium polyacrylate, and the percentages are all the mass percentages of each additive in the powder after impurity removal), mix evenly and then perform spray granulation. Control the inlet temperature of the spray drying tower at 240 °C and the outlet temperature at 150 °C to obtain the high-activity yttrium-stabilized zirconia powder.

[0068] Example 5 The preparation method of the nano-level yttrium-stabilized zirconia powder described above includes the following steps: (1) Mix 10 t of zirconium oxychloride with stabilizers. The addition amount of the stabilizer yttrium oxide is 189.53 kg; the addition amount of alumina is 2.70 kg; the addition amount of copper oxide is 1.20 kg; the addition amount of magnesium oxide is 1.20 kg; the addition amount of cerium oxide is 0.70 kg; the addition amount of calcium oxide is 0.40 kg; the addition amount of lanthanum oxide is 0.70 kg, and mix evenly through a mixer.

[0069] (2) Calcinate the above-mentioned uniformly mixed materials at a high temperature. The calcination temperature is 1150 °C and the calcination time is 10 h to obtain the precursor powder.

[0070] (3) Grind, stir and sand the above-mentioned precursor powder (primary grinding) to ensure that the particle size D50 of the precursor powder is 0.7 μm.

[0071] (4) The ground precursor powder is purified. The purification device used is a high-strength magnetic pipe iron remover for slurry, and the purification time is 8 h.

[0072] (5) The purified precursor powder is subjected to high-temperature spray granulation. The inlet temperature of the spray drying tower is controlled at 230 °C, and the outlet temperature is controlled at 140 °C.

[0073] (6) The powder obtained from the above spray granulation is subjected to secondary high-temperature calcination. The secondary calcination temperature is 1200 °C, and the calcination time is 9 h.

[0074] (7) The above secondary calcined powder is sanded (second grinding), and the particle size D50 is controlled at 0.3 μm.

[0075] (8) The powder after the above secondary grinding is purified by using a three-dimensional ultrasonic vibrating screen, and then additives (0.6% polyvinyl alcohol PVA, 0.4% polyethylene glycol, 0.3% glycerol, 0.3% ammonium polyacrylate) are added and mixed evenly, followed by spray granulation. The inlet temperature of the spray drying tower is controlled at 230 °C, and the outlet temperature is controlled at 140 °C, thus obtaining a high-activity yttrium-stabilized zirconia powder.

[0076] Example 6 The preparation method of the nano-scale yttrium-stabilized zirconia powder described above includes the following steps: (1) 10 t of zirconium oxychloride is mixed with stabilizers. The added amount of the stabilizer yttrium oxide is 150.22 kg; the added amount of alumina is 2.90 kg; the added amount of copper oxide is 1.30 kg; the added amount of magnesium oxide is 1.50 kg; the added amount of cerium oxide is 0.90 kg; the added amount of calcium oxide is 0.60 kg; the added amount of lanthanum oxide is 0.90 kg, and they are mixed evenly by a mixer.

[0077] (2) The above uniformly mixed materials are subjected to high-temperature calcination. The calcination temperature is 1200 °C, and the calcination time is 12 h to obtain a precursor powder.

[0078] (3) The above precursor powder is ball milled, stirred milled, and sanded (first grinding) to ensure that the particle size D50 of the precursor powder is 0.6 μm.

[0079] (4) The ground precursor powder is purified. The purification device used is a high-strength magnetic pipe iron remover for slurry, and the purification time is 12 h.

[0080] (5) The purified precursor powder is subjected to high-temperature spray granulation. The inlet temperature of the spray drying tower is controlled at 250 °C, and the outlet temperature is controlled at 130 °C.

[0081] (6) The powder obtained from the above spray granulation is subjected to secondary high-temperature calcination. The secondary calcination temperature is 1150 °C, and the calcination time is 11 h.

[0082] (7) Grind the above-mentioned secondary calcined powder (secondary grinding), and control the particle size D50 = 0.3 μm.

[0083] (8) Remove impurities from the above-mentioned powder after secondary grinding by using a three-dimensional ultrasonic vibrating screen, and then add additives (0.6% polyvinyl alcohol PVA, 0.4% polyethylene glycol, 0.3% glycerol, 0.3% ammonium polyacrylate, and the percentages are all the mass percentages of each additive in the powder after impurity removal). After mixing evenly, perform spray granulation. Control the inlet temperature of the spray drying tower at 250 °C and the outlet temperature at 130 °C to obtain high-activity yttrium-stabilized zirconia powder.

[0084] Example 7 The preparation method of the nano-scale yttrium-stabilized zirconia powder described above includes the following steps: (1) Mix 10 t of zirconium oxychloride with stabilizers. The addition amount of the stabilizer yttrium oxide is 110.20 kg; the addition amount of alumina is 3.00 kg; the addition amount of copper oxide is 1.40 kg; the addition amount of magnesium oxide is 1.30 kg; the addition amount of cerium oxide is 1.00 kg; the addition amount of calcium oxide is 0.70 kg; the addition amount of lanthanum oxide is 1.00 kg, and mix evenly through a mixer.

[0085] (2) Calcine the above-mentioned evenly mixed material at a high temperature. The calcination temperature is 1250 °C and the calcination time is 6 h to obtain a precursor powder.

[0086] (3) Grind, stir and sand the above-mentioned precursor powder (primary grinding) to ensure that the particle size D50 of the precursor powder is 0.4 μm.

[0087] (4) Remove impurities from the ground precursor powder. The impurity removal device used is a slurry high-strength magnetic pipe iron remover, and the impurity removal time is 14 h.

[0088] (5) Perform high-temperature spray granulation on the precursor powder after impurity removal. Control the inlet temperature of the spray drying tower at 240 °C and the outlet temperature at 120 °C.

[0089] (6) Perform secondary high-temperature calcination on the powder obtained by the above spray granulation. The secondary calcination temperature is 1100 °C and the calcination time is 10 h.

[0090] (7) Grind the above-mentioned secondary calcined powder (secondary grinding) to control the particle size D50 = 0.2 μm.

[0091] (8) The powder after the above-mentioned secondary grinding is purified using a three-dimensional ultrasonic vibrating sieve, and then additives (0.6% polyvinyl alcohol PVA, 0.4% polyethylene glycol, 0.3% glycerol, 0.3% ammonium polyacrylate, and the percentages are all the mass percentages of each additive in the powder after purification) are added and mixed evenly, followed by spray granulation. The inlet temperature of the spray drying tower is controlled at 240 °C, and the outlet temperature is controlled at 120 °C, thus obtaining a highly active yttrium-stabilized zirconia powder.

[0092] Example 8 The preparation method of the nanoscale yttrium-stabilized zirconia powder described above includes the following steps: (1) Mix 10 t of zirconium oxychloride with stabilizers. The addition amount of yttrium oxide as the stabilizer is 95.91 kg; the addition amount of alumina is 3.20 kg; the addition amount of copper oxide is 1.50 kg; the addition amount of magnesium oxide is 1.40 kg; the addition amount of cerium oxide is 0.80 kg; the addition amount of calcium oxide is 0.90 kg; the addition amount of lanthanum oxide is 0.80 kg, and mix evenly through a mixer.

[0093] (2) Calcinate the above-mentioned uniformly mixed material at a high temperature. The calcination temperature is 1000 °C, and the calcination time is 10 h to obtain a precursor powder.

[0094] (3) Grind, stir, and sand the above-mentioned precursor powder (primary grinding) to ensure that the particle size D50 of the precursor powder is 0.3 μm.

[0095] (4) Purify the ground precursor powder. The purification device used is a high-strength magnetic pipe iron remover for slurry, and the purification time is 10 h.

[0096] (5) Perform high-temperature spray granulation on the purified precursor powder. The inlet temperature of the spray drying tower is controlled at 230 °C, and the outlet temperature is controlled at 150 °C.

[0097] (6) Perform secondary high-temperature calcination on the powder obtained by the above-mentioned spray granulation. The secondary calcination temperature is 1250 °C, and the calcination time is 8 h.

[0098] (7) Grind the above-mentioned secondary calcined powder (secondary grinding) to control the particle size D50 = 0.2 μm.

[0099] (8) The powder after the above-mentioned secondary grinding is purified using a three-dimensional ultrasonic vibrating sieve, and then additives (0.6% polyvinyl alcohol PVA, 0.4% polyethylene glycol, 0.3% glycerol, 0.3% ammonium polyacrylate, and the percentages are all the mass percentages of each additive in the powder after purification) are added and mixed evenly, followed by spray granulation. The inlet temperature of the spray drying tower is controlled at 230 °C, and the outlet temperature is controlled at 150 °C, thus obtaining a highly active yttrium-stabilized zirconia powder.

[0100] Comparative Example 1 Preparation of an unstabilized zirconia powder: The difference between this comparative example and Example 1 is only that: in step (1), yttrium oxide was not added, and the amount of zirconium oxychloride was increased accordingly to maintain the total amount of materials, and other preparation processes were the same, obtaining an unstabilized zirconia powder.

[0101] Cracks occurred in the zirconia powder produced by this method during the preparation of the green body.

[0102] Comparative Example 2 Steps (1) to (5) in this comparative example are the same as those in Example 1. After the first spray granulation is completed, directly perform secondary grinding and impurity removal, and add the same additives as in Example 1 for re-spray granulation.

[0103] Comparative Example 3 Steps (1) to (6) in this comparative example are the same as those in Example 1. The particle size of the secondary grinding is controlled at D50 = 0.5 μm and impurity removal is performed, and the same additives as in Example 1 are added for re-spray granulation.

[0104] The detection indexes of the powders prepared in the above examples and comparative examples are shown in Table 1. The powder is formed by dry pressing and then isostatically pressed. The isostatic pressing pressure is 150 MPa and the time is 2 min to obtain a green body. The strength of the green body is shown in Table 1. The green body is sintered at 1430 °C for 2 h to obtain a sintered body. The detection results of the sintered body are shown in Table 1.

[0105] Among them, the average crystal grain size is measured by X-ray diffraction method, the starting angle is 25°, the ending angle is 32.5°, the scanning speed is 1° / min, the target is copper, the current is 30 mA, and the voltage is 50 kV. The determination of each component is measured by X-ray fluorescence method. The T+C phase is measured by X-ray diffraction method, and the measurement conditions are: starting angle 26°, ending angle 38°, scanning speed 4° / min, target copper, tube current 30 mA, and tube voltage 50 kV. Among them, the finished product density and shrinkage rate are measured and calculated by a 2D high-speed dimension measuring instrument and a pycnometer. The average flexural strength of the sintered body is measured and calculated by a press, a sintering furnace, a grinding machine, a cutting machine, a chamfering machine, and a strength meter.

[0106] Table 1 Detection Results

[0107] It can be seen from the above that the nano-sized yttrium-stabilized zirconia powder prepared by the method of the present invention has uniform particles and high purity, and the sintered body prepared by using it has good product stability and good mechanical properties.

Claims

1. A method for preparing nanoscale yttrium-stabilized zirconia powder, characterized in that: It includes the following preparation process: uniformly mix zirconium oxychloride with yttrium oxide, aluminum oxide, copper oxide, magnesium oxide, cerium oxide, calcium oxide, and lanthanum oxide, and obtain a precursor powder through a first high-temperature calcination; conduct a first grinding on the precursor powder, remove impurities, and spray drying. After drying, conduct a second high-temperature calcination to obtain a second calcined powder, conduct a second grinding until the particle size is D50 = 0.2 - 0.4 μm, remove impurities, then add additives, mix uniformly, and spray granulate to obtain a nanoscale yttrium-stabilized zirconia powder.

2. The preparation method of the nanoscale yttrium-stabilized zirconia powder according to claim 1, characterized in that: The addition 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%, 0.001 - 0.010% respectively. The % is the percentage of the mass of each oxide in the sum of its own mass and the mass of zirconium oxychloride.

3. The preparation method of the nano-sized yttrium-stabilized zirconia powder according to claim 1, characterized in that: The temperature of the first high-temperature calcination is 1000 - 1350 °C, and the calcination time is 4 - 12 h.

4. The preparation method of the nanoscale yttrium-stabilized zirconia powder according to claim 3, characterized in that: Conduct a first grinding on the precursor powder by means of ball milling, stirred milling, or sand milling until the particle size D50 = 0.3 - 0.7 μm.

5. The preparation method of the nanoscale yttrium-stabilized zirconia powder according to claim 4, characterized in that: Conduct a first grinding on the precursor powder, and the impurity removal is carried out by a high-strength magnetic pipeline iron remover for slurries, and the impurity removal time is 8 - 14 h.

6. The preparation method of the nanoscale yttrium-stabilized zirconia powder according to claim 5, characterized in that: Conduct a first grinding on the precursor powder, remove impurities, and spray drying. The spray drying is carried out using a spray drying tower. The inlet temperature of the spray drying tower is controlled at 230 - 260 °C, and the outlet temperature is controlled at 120 - 150 °C.

7. The preparation method of the nano-level yttrium-stabilized zirconia powder according to claim 1, wherein: The temperature of the second high-temperature calcination is 1100 - 1300 °C, and the calcination time is 8 - 12 h.

8. The preparation method of the nano-sized yttrium-stabilized zirconia powder according to claim 1, characterized in that: The second grinding is carried out by means of sand milling.

9. The preparation method of the nanoscale yttrium-stabilized zirconia powder according to claim 8, wherein: After the second grinding and impurity removal, add additives. The additives are a mixture of polyvinyl alcohol, polyethylene glycol, glycerol, and ammonium polyacrylate. After mixing uniformly, spray granulate; the impurity removal is carried out using a three-dimensional ultrasonic vibrating screen.

10. A nano-scale yttrium-stabilized zirconia powder, characterized in that: It is prepared by the preparation method of the nanoscale yttrium-stabilized zirconia powder described in any one of claims 1 - 9, and has the following indicators: ZrO2 + HfO2 ≥ 90%, Y2O3 = 2.50 - 9.91%, T + C phase ≥ 96%.

Images