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CN-121974393-A - High-performance nearly spherical zirconia feed powder and preparation method thereof

CN121974393ACN 121974393 ACN121974393 ACN 121974393ACN-121974393-A

Abstract

The invention belongs to the technical field of advanced ceramic material preparation, and particularly discloses high-performance near-spherical zirconia feed powder and a preparation method thereof, wherein the method comprises the following steps of (1) preparing composite precursor liquid; the method comprises the steps of (1) carrying out graded controllable thermal conversion, (2) carrying out post-treatment, namely carrying out thermal treatment on the product obtained in the step (2) in an oxidizing atmosphere at 500-700 ℃ for 0.5-3 hours to obtain the zirconia powder. The invention prepares the powder with special structure of 'outer dense inner hole'. The smooth and compact surface gives the powder excellent fluidity, the internally uniform nano closed pores not only moderately reduce the particle density and further facilitate the flow, but also can partially absorb the binder during the preparation of the feed, and play the roles of buffering and optimizing the distribution of the binder, thereby allowing higher powder loading amount under the same viscosity or obtaining lower viscosity and better rheological property under the same loading amount.

Inventors

  • SUN JINGHUI
  • FU ZHIHONG

Assignees

  • 金业新材料科技(昆山)有限公司

Dates

Publication Date
20260505
Application Date
20260115

Claims (9)

  1. 1. The preparation method of the high-performance near-spherical zirconia feed powder is characterized by comprising the following steps of: (1) Preparing a composite precursor liquid, namely dissolving a zirconium source and a stabilizer source in water to obtain a solution A, dissolving a polymer network agent and a pore-forming agent in water to obtain a solution B, mixing the solution A and the solution B, and regulating the pH value to 1.5-3.5 to obtain a stable and uniform composite precursor liquid; (2) Atomizing the precursor liquid obtained in the step (1) into liquid drops, firstly, entering a first reaction zone with the temperature of 250-400 ℃ to stay for 1-6 seconds to gel the liquid drops and form an internal organic-inorganic network, then, directly introducing the obtained solid microspheres into a second reaction zone with the temperature of 750-1050 ℃ to stay for 3-20 seconds to burn and decompose the internal network, forming nano closed pores in the interior of the particles, and simultaneously, densifying and crystallizing the surface; (3) And (3) post-treatment, namely heat-treating the product obtained in the step (2) for 0.5-3 hours at 500-700 ℃ in an oxidizing atmosphere to obtain the zirconia powder.
  2. 2. The preparation method of claim 1, wherein in the step (1), the polymer network agent is at least one selected from polyvinylpyrrolidone, polyvinyl alcohol and polyethylene glycol with a molecular weight of 2000-10000, the pore-forming agent is at least one selected from citric acid, tartaric acid and polyacrylic acid, and the mass ratio of the polymer network agent to the pore-forming agent is 1:1-1:4.
  3. 3. The method according to claim 1, wherein in the step (1), the total metal ion concentration in the solution A is 0.3-1.2 mol/L, and the stabilizer is a compound of yttrium, cerium or magnesium, and the addition amount is such that the content of the stabilizer oxide in the final powder is 2-5 mol%.
  4. 4. The process of claim 1, wherein in step (2), the first reaction zone is at a temperature of 300 to 380℃and a residence time of 2 to 5 seconds, and the second reaction zone is at a temperature of 850 to 1000℃and a residence time of 5 to 15 seconds.
  5. 5. A high-performance nearly spherical zirconia feed powder prepared by the method according to any one of claims 1-4 is characterized in that powder particles are nearly spherical, sphericity is more than or equal to 0.90, D50 is 10-50 mu m, particle size distribution span is less than 1.2, closed holes with the size of 30-250nm are uniformly distributed in single particles, and the surfaces of the particles are compact and smooth shells formed by zirconia nanocrystals.
  6. 6. The zirconia feed powder according to claim 5, wherein the powder has a Hall flow time of 30s/50g or less, a tap density of 52% or more of its theoretical density and a BET specific surface area of 2 to 10m 2 /g.
  7. 7. The zirconia feed powder of claim 5, wherein the main crystal phase of the powder is metastable tetragonal zirconia t-ZrO 2 , the content of monoclinic phase m-ZrO 2 is less than or equal to 5wt%, and the tetragonal phase content retention rate is more than or equal to 95% after heat treatment at 550 ℃ for 2 hours.
  8. 8. A feed for ceramic injection molding, characterized by comprising the high-performance near-spherical zirconia feed powder as claimed in any one of claims 5 to 7 and an organic binder, wherein the volume loading of the powder in the feed is not less than 58%.
  9. 9. The feed for ceramic injection molding according to claim 8, wherein the viscosity of the feed is not more than 120 Pa-s when the powder loading is 60 vol%, the test temperature is 160 ℃ and the shear rate is 1000s -1 .

Description

High-performance nearly spherical zirconia feed powder and preparation method thereof Technical Field The invention belongs to the technical field of advanced ceramic material preparation, and particularly relates to high-performance near-spherical zirconia feed powder and a preparation method thereof. Background Zirconia ceramics are widely used in precision bearings, dental restorations, electronic devices, and the like because of their excellent mechanical properties, chemical stability, and biocompatibility. The powder injection molding technology is a key technology for preparing zirconia ceramic parts with complex shapes and high precision, and the core of the technology is feeding, and the performance of the feeding directly depends on the characteristics of raw material powder. The ideal ceramic powder for injection molding should have high sphericity, narrow particle size distribution, high tap density, excellent flowability, and good sintering activity and phase stability. At present, commercial zirconia feed powder is mainly prepared by spray granulation or one-step pyrolysis process, and has the following general problems: 1. The traditional spray granulation powder has rough and porous surface, is formed by loosely accumulating nanometer or submicron primary particles, has large inter-particle friction force and poor fluidity, and causes uneven feeding and injection defects. 2. In order to improve the production efficiency and the dimensional accuracy, it is necessary to increase the powder loading amount in the feed. However, increasing the loading of the conventional solid spherical powder drastically increases the feed viscosity and deteriorates the workability. 3. To obtain high sintering activity, the powder is often metastable tetragonal phase, but the nanoscale active surface is prone to absorb water vapor to induce transformation to monoclinic phase, resulting in deterioration of feeding or green body properties. 4. Although spherical particles can be directly obtained by high-temperature spray pyrolysis by a one-step method, the process window is narrow, the internal structure of the particles is difficult to precisely control, hollow, broken or excessively sintered particles are easy to generate, and the batch stability is poor. Therefore, the zirconia feeding powder which can systematically solve the contradiction, has unique structure and excellent performance and the preparation method thereof are developed, and have important significance for promoting the development of high-end ceramic injection molding technology. Disclosure of Invention The invention aims to provide high-performance near-spherical zirconia feed powder and a preparation method thereof. According to the invention, a specific composite precursor is designed, and a hierarchical controllable thermal conversion process is adopted, so that the near-spherical zirconia powder with a compact and smooth surface and an internal nano closed-pore structure is prepared. The powder and the feed prepared by the powder are obviously superior to the powder obtained by the traditional spray granulation and the conventional one-step pyrolysis method in terms of fluidity, loading capacity, phase stability, rheological property and final sintered body quality. The invention effectively solves the technical contradiction existing in the ceramic injection molding field for a long time, and has wide industrial application prospect. The invention provides a preparation method of high-performance near-spherical zirconia feed powder, which comprises the following steps: (1) Preparing a composite precursor liquid, namely dissolving a zirconium source and a stabilizer source in water to obtain a solution A, dissolving a polymer network agent and a pore-forming agent in water to obtain a solution B, slowly adding the solution B into the solution A under continuous stirring, and regulating the pH value of the mixed solution to 1.5-3.5 by using dilute ammonia water or organic amine after uniformly mixing to obtain a stable, uniform and composite precursor liquid with certain viscosity; (2) Atomizing the precursor liquid obtained in the step (1) into liquid drops, firstly, entering a first reaction zone with the temperature of 250-400 ℃ to stay for 1-6 seconds, enabling the liquid drops to gel and form an internal organic-inorganic network, under the condition, rapidly dehydrating the liquid drops, enabling the precursor to undergo preliminary hydrolytic condensation, and simultaneously enabling a polymer network agent to interact with a pore-forming agent to form a penetrating organic-inorganic hybrid gel network in the liquid drops, so as to realize conversion and pre-curing of the liquid drops to solid microspheres; And then directly introducing the obtained solid microspheres into a second reaction zone with the temperature of 750-1050 ℃ to stay for 3-20 seconds, so that an internal network is combusted and decomposed to form nano closed po