阅读说明：本技术 一种湿法改性纳米氧化锆粉体方法 (Method for modifying nano zirconium oxide powder by wet method ) 是由 王敬轩 侯永改 侯超 李文凤 王延铭 冯鑫 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种湿法改性纳米氧化锆粉体方法,属于功能陶瓷领域。改性后的氧化锆烧结后粉体流失量要远低于原始氧化锆陶瓷,陶瓷均匀致密,而且没有大尺寸的孔隙,且改性氧化锆陶瓷的力学性能以及致密度都有优于原始氧化锆陶瓷,达到了提高烧结性能的目的。凝胶注模作为一种新颖的成型方法,为制备大尺寸及复杂形状的陶瓷制品提供了有效的技术途径。(The invention discloses a method for modifying nano zirconia powder by a wet method, belonging to the field of functional ceramics. The loss of the sintered powder of the modified zirconia is far lower than that of the original zirconia ceramic, the ceramic is uniform and compact, large-size pores do not exist, the mechanical property and the compactness of the modified zirconia ceramic are superior to those of the original zirconia ceramic, and the purpose of improving the sintering property is achieved. Gel casting is used as a novel forming method, and provides an effective technical approach for preparing ceramic products with large sizes and complex shapes.)

1. A method for modifying nano zirconia powder by a wet method comprises the following process principles: the method comprises the steps of adding zirconium oxide and absolute ethyl alcohol into water serving as a solvent, sequentially adding silane coupling agents with different contents, stirring, grinding, and comparing the effects of the silane coupling agents with different addition amounts through molding and sintering, so that the modified zirconium oxide ceramic is uniform and compact in structure, and the porosity, density and mechanical properties of the modified zirconium oxide ceramic are superior to those of the original zirconium oxide ceramic.

2. The modification method according to claim 1, characterized in that: zirconium oxide (3Y-ZrO) partially stabilized with yttrium oxide is used₂) (ii) a Particle diameter D in powder₅₀=0.15 μm, yttria content 5.25 wt%.

3. The modification method according to claim 1, characterized in that: the water, the zirconia powder and the absolute ethyl alcohol are premixed liquid.

4. The modification method according to claim 1, characterized in that: the silane coupling agent is KH 550.

5. The modification method according to claim 1, characterized in that: the addition amount of KH550 is 0.1% to 1.0%.

6. The modification method according to claim 1, characterized in that: the initiator is Ammonium Persulfate (APS).

7. The modification method according to claim 1, characterized in that: the catalyst is Tetramethylethylenediamine (TEMED).

8. The modification method according to claim 1, characterized in that: the dispersant is 1.2.4 tricarboxylic acid.

9. The modification method according to claim 1, characterized in that: the method comprises the following steps of: modification of powder: adding zirconium oxide and absolute ethyl alcohol into water serving as a solvent to prepare a premixed solution, then sequentially adding silane coupling agents with different contents, stirring, and pouring the uniformly stirred slurry into a mortar for grinding; molding and drying: adding an initiator and a catalyst into the prepared premixed solution, stirring, then adjusting the pH, adding a dispersing agent, adding the modified zirconia powder with different contents for three times for ball milling, pouring the prepared slurry into a mould, putting the mould into a drying oven for curing, and putting the green blank into an electric heating air blowing drying oven for curing in the drying process; thirdly, sintering: after the green body is dried, setting a sintering curve according to a TG-DTA curve, removing gel of the green body, namely removing organic matters, performing differential thermal analysis on the dried gel, and slowly heating at the decomposition stage of the organic matters; the final sintering temperature was 1520 ℃ and held for 120 min.

10. The method of claim 9, wherein: when KH550 is added in an amount of 0.7%, the porosity content is only 0.17% at the lowest, and the density reaches 6.07g/cm³And when the content of the modified zirconia ceramic is 0.6%, the mechanical property of the modified zirconia ceramic is optimal.

Technical Field

The invention belongs to the field of inorganic non-metallic materials and functional ceramics, and relates to a method for modifying a nano zirconia powder by a wet method.

Background

The gel injection molding process combines polymer chemistry and the traditional ceramic process skillfully, and a method of polymerizing organic monomers into high molecules is applied in the ceramic molding process, so that a greater opportunity is provided for molding a high-density, high-strength and near-size blank which can be directly machined into a ceramic part with complicated shape. The gel casting process includes the first preparation of ceramic slurry with low viscosity and high solid content, and the subsequent inducing the polymerization of organic monomer in the slurry to solidify the slurry in-situ. After the operations of drying, binder removal and sintering are carried out on the blank, a part which does not contain impurity residues and has a complex shape can be obtained, and the current forming technology is advanced. The gel casting process that was first developed was a non-aqueous based gel forming process, followed by the successful development of a more environmentally friendly aqueous based gel forming process that is more environmentally friendly than the non-aqueous based gel forming process.

Surface modification is a process of chemically, physically, mechanically, or the like processing the surface of a powder to change the physical and chemical properties of the surface of the processed powder, thereby improving the dispersibility of the powder in a medium. The surface modification of the powder has a plurality of functions, mainly including improving or changing the dispersibility of the powder particles, and the powder particles are not easy to agglomerate after changing the dispersibility of the powder particles. Meanwhile, the surface modification can also improve the surface activity of the powder example and enable the surface of the powder to generate new functions, physical, chemical and mechanical properties. And improving the compatibility of the powder particles with other substances and the durability of the powder. The modification can be realized by coating a covering layer with different chemical compositions on the surface of the powder, improving the compatibility of the particles and other substances, enabling the powder to have biocompatibility, improving the thermal stability, mechanical stability and chemical stability of the powder, improving the optical, magnetic, electric, catalytic, hydrophilic, hydrophobic and sintering characteristics of the powder, prolonging the service life and improving the corrosion resistance.

The problems faced in wet-process modification of nano zirconia powder are as follows:

the stable zirconia material has unique physical and chemical properties, has excellent characteristics of high melting point, strong hardness and the like, also has acidity, alkalinity, oxidizability and reducibility, is a P-type semiconductor and is easy to generate holes. The invention mainly aims at the influence of silane coupling agent KH550 on the surface performance of zirconia powder and researches on a gel casting process. The influence of the volume percentage content, the reaction temperature and the reaction time of the silane coupling agent KH550 on the surface modification effect of the zirconium oxide is researched.

Disclosure of Invention

The purpose of the invention is as follows: the research takes untreated zirconia powder as a raw material, uses a silane coupling agent KH550 to perform surface modification treatment on the untreated zirconia powder, improves the forming and sintering properties of the powder by improving the agglomeration and surface properties of the powder, and obtains zirconia ceramics with denser sintered body and higher bending strength through a gel injection molding process.

The technical scheme is as follows: in order to solve the problems, the following technical scheme is adopted for realizing the following steps:

A. the water, the absolute ethyl alcohol and the zirconia are stirred to prepare a premixed solution, and the premixed solution is put into an ultrasonic cleaner for 30 minutes. Sequentially adding different contents of silane coupling agent KH550 (0.1-1.0% of the mass of zirconia), and stirring the prepared solution in a stirrer for two hours. And pouring the uniformly stirred slurry into a mortar, putting the mortar into a drying oven, drying for 6 hours, and grinding.

B. Adding zirconia powder (with the volume content of 44-50%) into the prepared premixed liquid, ball-milling for 4.5 hours to prepare slurry, adding a defoaming agent, an initiator and a catalyst, stirring, injecting the mixture into a mold, and placing the mold in a vacuum drying oven for curing at 70 ℃.

C. Adding the prepared slurry into a ball mill, performing ball milling for 5 hours (the ball-to-material ratio is 1: 2) to prepare zirconia slurry, sequentially adding defoamer n-octanol accounting for 0.1% of the mass of the slurry, initiator ammonium persulfate accounting for 0.5% of the mass of the slurry and catalyst tetramethyl ethylene diamine accounting for 0.3% of the volume of the slurry into the ball-milled slurry, adding the next reagent into the ball-milled slurry after stirring for 2 minutes, pouring the prepared slurry into a mold, placing the mold into a drying box, curing at 70 ℃, and recording the curing time. The drying process needs to be carried out by putting the green bodies into an electrothermal blowing drying oven, and the drying curve is set as follows: drying at 25 deg.C for 72h, heating to 40 deg.C for 48h, heating to 60 deg.C for 12h, heating to 80 deg.C for 6h, and heating to 100 deg.C for 4 h.

D. After the green body is dried, setting a sintering curve according to a TG-DTA curve, removing gel of the green body, namely removing organic matters, performing differential thermal analysis on the dried gel, and slowly heating up in the decomposition stage of the organic matters to finally obtain the sintering curve as follows: 60min, heating from 25 deg.C to 150 deg.C, 80min to 300 deg.C, 240min to 400 deg.C, 200min to 800 deg.C, maintaining at 800 deg.C for 90min, 200min to 1200 deg.C, maintaining at 1200 deg.C for 30min, 150min to 1520 deg.C, and maintaining at 1520 deg.C for 120 min.

In the above method, the zirconia powder content is preferably 50%.

In the above method, the silane coupling agent is preferably KH 550.

In the above process, the catalyst is preferably tetramethylethylenediamine.

In the above method, preferably, the initiator is ammonium persulfate.

In the above method, the dispersant is preferably 1,2, 4-tricarboxylic acid.

Has the advantages that:

1. the original zirconia ceramics have a plurality of serious defects, the modified zirconia ceramics have uniform and compact structure, and the porosity, density and mechanical property of the modified zirconia ceramics are superior to those of the original zirconia ceramics.

Compared with the original zirconia sintered body, the phase composition of the modified sintered body and the powder loss before and after sintering are compared, and the powder loss before and after sintering of the modified powder is far lower than the sintering loss rate of the original zirconia powder.

Drawings

FIG. 1 is an SEM image before modification.

FIG. 2 is a modified SEM image.

Detailed Description

The method comprises the following specific implementation steps:

150 ml of water, 150 ml of absolute ethyl alcohol and 150 ml of zirconium oxide were weighed and stirred to prepare a premixed solution, which was put into an ultrasonic cleaner for 30 minutes. Different contents of a silane coupling agent KH550 (0.1 to 1.0% by mass of zirconia) and KH550 and KH560 (0.1 to 0.5% by mass of zirconia) were sequentially added, and the prepared solution was stirred in a stirrer for two hours. And pouring the uniformly stirred slurry into a mortar, putting the mortar into a drying oven, drying for 6 hours, and grinding.

20 ml of distilled water, 3g of methacrylamide, 0.2g of methylene bisacrylamide (cross-linking agent) and 0.56g of polyvinylpyrrolidone (polyethylene mass) are weighed, mixed and stirred for 15min, the pH of the stirred solution is adjusted to 10-11 by using ammonia water, then 1.2.4 tricarboxylic acid (dispersing agent) with 0.2% of powder is added, and finally 117g (50 g, 50g and 17 g) of modified zirconium oxide powder is weighed and added in three times.

Adding the prepared slurry into a ball mill, performing ball milling for 5 hours (the ball-to-material ratio is 1: 2) to prepare zirconia slurry, sequentially adding defoamer n-octanol accounting for 0.1% of the mass of the slurry, initiator ammonium persulfate accounting for 0.5% of the mass of the slurry and catalyst tetramethyl ethylene diamine accounting for 0.3% of the volume of the slurry into the ball-milled slurry, adding the next reagent into the ball-milled slurry after stirring for 2 minutes, pouring the prepared slurry into a mold, placing the mold into a drying box, curing at 70 ℃, and recording the curing time. The drying process needs to be carried out by putting the green bodies into an electrothermal blowing drying oven, and the drying curve is set as follows: drying at 25 deg.C for 72h, heating to 40 deg.C for 48h, heating to 60 deg.C for 12h, heating to 80 deg.C for 6h, and heating to 100 deg.C for 4 h. Green sintering curve: after the green body is dried, setting a sintering curve according to a TG-DTA curve, removing gel of the green body, namely removing organic matters, performing differential thermal analysis on the dried gel, and slowly raising the temperature in the decomposition stage of the organic matters to finally obtain the sintering curve as follows: 60min, heating from 25 deg.C to 150 deg.C, 80min to 300 deg.C, 240min to 400 deg.C, 200min to 800 deg.C, maintaining at 800 deg.C for 90min, 200min to 1200 deg.C, maintaining at 1200 deg.C for 30min, 150min to 1520 deg.C, and maintaining at 1520 deg.C for 120 min.

SEM analysis and X-ray diffraction analysis are carried out on the prepared zirconia green body and the zirconia ceramic, the powder loss of the sintered modified zirconia is far lower than that of the original zirconia ceramic, the ceramic is uniform and compact, no large-size pores exist, the mechanical property and the compactness of the modified zirconia ceramic are better than those of the original zirconia ceramic, the lowest porosity content is only 0.17 percent when the KH550 is added in an amount of 0.7 percent, and the density reaches up to 06.07g/cm³And when the content of the modified zirconia ceramic is 0.6%, the mechanical property of the modified zirconia ceramic is optimal. The purpose of improving the sintering performance is achieved. Compared with the original powder, the powder molding after KH550 modification is obviously improved. By comparing fig. 1 and fig. 2, the green body obtained by sintering the ceramic with the modified powder is uniform and compact, and has no large-size pores, and compared with the original zirconia powder, the green body obtained by sintering the original zirconia powder has a loose structure, and larger pores can be seen. Therefore, the performance of the modified zirconia powder is obviously optimized after sintering and forming.