阅读说明：本技术 一种超细氧化锆磨球的制备方法 (Preparation method of superfine zirconia grinding ball ) 是由 李飞 于 2019-11-22 设计创作，主要内容包括：本发明提供了一种超细氧化锆磨球的制备方法：首先采用砂磨将纳米氧化锆粉末分散,然后在分散后的浆料中添加絮凝剂,使纳米氧化锆颗粒聚集形成疏松絮状的聚集体,从而抑制其在喷雾造粒过程中形成空心或异形结构,浆料经喷雾造粒制得多孔结构造粒粉末,造粒粉末经烧结、研磨后,可制成致密超细氧化锆磨球。本发明通过解决纳米粉末在喷雾造粒过程中形成空心或异形结构问题,使得氧化锆超细磨球能够采用工业中成熟的喷雾造粒工艺来制备,具有成本低、效率高、制品性能好等优点。(The invention provides a preparation method of a superfine zirconia grinding ball, which comprises the following steps: firstly, dispersing nano zirconia powder by using sand grinding, then adding a flocculating agent into the dispersed slurry to ensure that nano zirconia particles are aggregated to form loose flocculent aggregates, thereby inhibiting the nano zirconia particles from forming hollow or special-shaped structures in the spray granulation process, preparing porous structure granulated powder by spray granulation of the slurry, and sintering and grinding the granulated powder to prepare compact superfine zirconia grinding balls. The invention solves the problem that the nano powder forms a hollow or special-shaped structure in the spray granulation process, so that the zirconia superfine grinding ball can be prepared by adopting the mature spray granulation process in the industry, and has the advantages of low cost, high efficiency, good product performance and the like.)

1. The preparation method of the superfine zirconia grinding ball is characterized by comprising the following steps:

step one, uniformly mixing part of stable nano zirconia powder, deionized water and a dispersing agent to obtain slurry;

step two, adopting a sand mill to grind the slurry to the particle size within 200 nm;

step three, adding a flocculating agent into the ground slurry, and uniformly stirring at a low speed;

step four, adding the adhesive into the uniformly stirred slurry, and continuously stirring uniformly at a low speed;

step five, carrying out spray drying treatment on the slurry in the step four to obtain granules;

putting the granules in the fifth step into a sintering furnace for sintering treatment;

and step seven, polishing and screening the sintered zirconium oxide grinding ball blank to obtain finished zirconium oxide ceramic grinding balls with different grain diameters.

2. The method for preparing ultrafine zirconia grinding balls according to claim 1, wherein in the first step, the slurry has a solid content of 20-25%, the dispersant is polyacrylamide, and the amount of the dispersant is 0.8-1.0% by weight of the nano zirconia powder.

3. The method as claimed in claim 2, wherein the flocculating agent is anionic polyacrylamide with a molecular weight of 10000-12000, and the amount is 0.6-0.8% of the weight of the nano zirconia powder; the stirring speed was 30 rpm.

4. The method for preparing the superfine zirconia grinding ball according to claim 1, wherein the adhesive in the fourth step is acrylic resin, and the amount of the acrylic resin is 2% of the weight of the nano zirconia powder; the stirring speed was 30 rpm.

5. The method for preparing the ultrafine zirconia grinding ball according to claim 1, wherein in the step five, during spray granulation, the inlet temperature is (360-380) DEG C, the outlet temperature is (110-120) DEG C, and the rotation speed is (6000-12000) rpm.

6. The method for preparing the ultrafine zirconia grinding balls according to claim 1, wherein the sintering schedule in the sixth step is a temperature rise rate of not higher than 60 ℃/h, and the temperature is maintained at 400 ℃ for 2h and 1500 ℃ for 2 h.

7. The method for preparing an ultra-fine zirconia grinding ball according to claim 2, wherein the amount of the dispersant is 0.9% by weight of the nano zirconia powder.

8. The method for preparing the ultrafine zirconia grinding balls according to claim 3, wherein the amount of the flocculant is 0.7% by weight of the nano zirconia powder.

Technical Field

The invention belongs to the field of ceramic materials, and particularly relates to a preparation method of a superfine zirconia grinding ball.

Background

With the continuous development of industries such as paint, printing ink, nano fine ceramics and the like, the requirement on the fineness of the raw materials is higher and higher, and the requirement on the fineness of the raw materials of various products even reaches within 100 nm. In order to grind the above-mentioned ultrafine raw materials, it is necessary to prepare a high-performance grinding medium having a particle size of 0.3mm or less.

The zirconia ceramic has high density, high strength, high hardness, high fracture toughness and excellent wear resistance and chemical corrosion resistance, has the characteristics of high grinding efficiency, long service life, small pollution to products and the like when being used for grinding media, and is the grinding media with the most excellent performance at present.

The traditional zirconia grinding ball preparation methods mainly comprise a rolling ball method, an isostatic pressing forming method, a gel titration forming method, a sol-gel method, a stirring forming method and the like. Among them, the ball rolling method and isostatic pressing method, such as chinese patents 201010187597.7, 201811185831.5, 200710116340.0, etc., can only prepare grinding balls with diameter larger than 0.5 mm; the sol-gel method, such as Chinese patent 201611094181.4, needs expensive organic raw materials, and has high product cost and great pollution; although the gel titration forming method, such as chinese patents 201510629431.9, 200680006597.4, 201210371349.7, 201610174094.3, 201710057229.2, etc., can prepare grinding balls with a diameter of about 0.2mm, since only one grinding ball can be prepared by one titration, the production efficiency is low, and since the grinding balls with small particle size are light in weight, they are easy to deform during titration; the stirring molding method such as chinese patent 201710943691.2 requires high-speed stirring under high pressure, and has high equipment cost, high safety risk, and many defects of the grinding balls prepared under the high-speed stirring environment, and low product yield.

Spray granulation is a low-cost, high-efficiency process that can prepare spherical powder with a diameter of less than 0.3 mm. At present, the main problem of preparing superfine zirconia grinding balls by adopting a spray granulation method is that because superfine raw powder is required for preparing the superfine grinding balls, the powder is small in mass, and during spray granulation, particles migrate to the surface of liquid drops under the action of capillary force formed by water evaporation, and finally hollow or apple-shaped or onion-ring-shaped powder is formed, and the powder with the structure cannot form high-density spherical grinding balls after sintering.

In order to improve the powder structure after the nano zirconia is spray-granulated, chinese patent 201080059614.7 adopts a method of increasing the specific surface area of the second phase (alumina) powder to prevent the formation of hollow particles when preparing zirconia-alumina composite ceramic microspheres. However, due to the different settling properties of the powders with different specific surface areas in the slurry, the components in the slurry are difficult to be uniform, so that the grinding balls prepared by the method have larger difference in performance; chinese patent 201510869405.3 teaches the principle of the gel injection molding process, and adopts the gel slurry to carry out spray granulation to prepare zirconia grinding balls with the diameter of about 0.1mm, and the method has two main defects, namely, the gel monomer has certain toxicity, is not beneficial to the health of operators and can pollute the environment; in addition, the viscosity of the gel slurry is susceptible to fluctuations in ambient temperature and the like, resulting in unstable particle sizes of the particles produced. Researchers also adopt organic solvents such as alcohol and the like to spray and granulate the nano zirconia powder into solid spherical powder at extremely low inlet temperature, but because the organic solvents are used in the method, sealing treatment is needed in the stages of slurry preparation and spray granulation, so that equipment is expensive and the safety management cost is extremely high; some researchers have used a spray freeze-drying method to prepare porous solid nano-zirconia granulated powder, but the spray freeze-drying method needs to slowly remove water in the powder under low temperature and vacuum, so that the preparation cost of the powder is extremely high.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a method for preparing an ultrafine zirconia grinding ball, which solves the problem that water-based nano zirconia powder forms a hollow or irregular structure in the spray granulation process, so that the ultrafine high-density zirconia grinding ball can be prepared at low cost.

In order to achieve the purpose, the technical scheme of the invention is as follows: a preparation method of superfine zirconia grinding balls comprises the following steps:

step one, uniformly mixing part of stable nano zirconia powder, deionized water and a dispersing agent to obtain slurry;

step two, adopting a sand mill to grind the slurry to the particle size within 200 nm;

step three, adding a flocculating agent into the ground slurry, and uniformly stirring at a low speed;

step four, adding the adhesive into the uniformly stirred slurry, and continuously stirring uniformly at a low speed;

step five, carrying out spray drying treatment on the slurry in the step four to obtain granules;

putting the granules in the fifth step into a sintering furnace for sintering treatment;

and step seven, polishing and screening the sintered zirconium oxide grinding ball blank to obtain finished zirconium oxide ceramic grinding balls with different grain diameters.

As an improvement of the invention, in the step one, the solid content of the slurry is (20-25)%, the dispersant is polyacrylamide, and the dosage of the dispersant is (0.8-1.0)% of the weight of the nano zirconia powder; in the scheme, a flocculating agent is added, after the flocculating agent is dissociated in water, one end of a high molecular group of the flocculating agent is adsorbed on the surface of the nano particles, and the other end of the high molecular group is mutually wound to connect the nano particles in the slurry into loose and flocculent aggregates. During spray granulation, on one hand, nanoparticles are mutually held down through macromolecular groups, and on the other hand, loose flocculent aggregates are mutually rubbed to form obstacles, so that the nanoparticles are inhibited from migrating to the surface, and hollow powder is prevented from being formed.

As an improvement of the invention, in the third step, the flocculant is anionic polyacrylamide, the molecular weight is 10000-12000, and the dosage is 0.6-0.8 percent of the weight of the nano zirconia powder; the stirring speed was 30 rpm.

As an improvement of the invention, in the fourth step, the adhesive is acrylic resin, and the amount of the acrylic resin is 2% of the weight of the nano zirconia powder; the stirring speed was 30 rpm.

As an improvement of the invention, in the fifth step, during spray granulation, the inlet temperature is 360-380 ℃ and the outlet temperature is 110-120 ℃ and the rotation speed is 6000-12000 r/min.

As an improvement of the invention, the sintering schedule in the sixth step is that the heating rate is not higher than 60 ℃/h, and the temperature is kept for 2h at 400 ℃ and 2h at 1500 ℃.

In order to apply the spray drying granulation technology which is widely applied in industry to the preparation of the superfine zirconia grinding balls, the problem of hollow or special-shaped structures formed during the granulation of the nano powder needs to be solved. The core of the invention is that a small amount of polyacrylamide is added into nano zirconia slurry with relatively low solid content; polyacrylamide is a common flocculating agent in daily industry, after being dissociated in water, one end of a macromolecular group of the polyacrylamide is adsorbed on the surface of nano zirconia particles, and the other end of the macromolecular group is mutually wound, so that the nano zirconia particles in the slurry are connected into loose and flocculent aggregates. During spray granulation, on one hand, nano zirconia particles are mutually held through macromolecular groups, and on the other hand, loose flocculent aggregates are mutually rubbed to form obstacles, so that the nano zirconia particles are inhibited from migrating to the surface, and hollow or special-shaped structure powder is prevented from being formed; the prepared spherical powder is sintered at high temperature to obtain the compact zirconia grinding ball.

Compared with other processes for preparing superfine zirconia grinding balls at the present stage, the process adopts a mature spray drying granulation process, has the advantages of low investment and high efficiency, and the prepared grinding ball has high roundness and low breakage rate, and the diameter of the prepared grinding ball can be controlled to be (0.05-0.25) mm by controlling the rotating speed of spray drying. The anionic polyacrylamide used in the invention is a flocculant commonly used in daily industry, has low price and low dosage, does not obviously increase the cost, and is a method for preparing the superfine zirconia grinding ball with low cost.

Drawings

FIG. 1 is SEM pictures of the surface and cross-section of powder prepared by adding a flocculating agent into a superfine zirconia grinding ball of the present invention;

FIG. 2 is a SEM photograph of the surface and cross section of a sintered superfine zirconia grinding ball of the present invention;

FIG. 3 is an SEM photograph of the surface and cross-section of a powder prepared in the absence of a flocculant added to a comparative example.

Wherein: in fig. 1 to 3, the left side is a surface view and the right side is a sectional view.

Detailed Description

For the purpose of enhancing an understanding of the present invention, the present invention will be described in further detail below with reference to the accompanying drawings and examples.