阅读说明：本技术 一种微纳双尺度氧化钇坩埚及制备方法 (Micro-nano double-scale yttrium oxide crucible and preparation method thereof ) 是由 樊江磊 梁柳博 王霄 魏泽新 李莹 吴深 王艳 周向葵 刘建秀 于 2021-06-24 设计创作，主要内容包括：本发明公开一种微/纳双尺度氧化钇坩埚,外层由微米级氧化钇制成,内层由纳米级氧化钇构成,且内层纳米级氧化钇与外层微米级氧化钇紧密结合。纳米级氧化钇内层,在烧结过程中通过自粘结作用形成致密的氧化钇壳,在TiAl合金的熔炼与精密铸造过程中,抵抗合金熔体的侵蚀,防止合金受到污染；微米级氧化钇外层,烧结后具有一定的孔隙率,可提高坩埚的强度,在TiAl合金的熔炼与精密铸造过程中,提高了坩埚的抗热震性能,可满足合金熔炼时的高过热度需求；微/纳双尺度氧化钇坩埚内外层结合紧密,所述氧化钇坩埚纯度高达99.99%,避免熔炼与精密铸造过程中杂质元素对TiAl合金造成污染。(The invention discloses a micro/nano double-scale yttrium oxide crucible, wherein the outer layer is made of micron-scale yttrium oxide, the inner layer is made of nano-scale yttrium oxide, and the inner layer of nano-scale yttrium oxide is tightly combined with the outer layer of micron-scale yttrium oxide. The nano-scale yttrium oxide inner layer forms a compact yttrium oxide shell through self-bonding in the sintering process, resists the corrosion of alloy melt in the smelting and precision casting processes of TiAl alloy and prevents the alloy from being polluted; the micron-scale yttrium oxide outer layer has certain porosity after sintering, can improve the strength of the crucible, improves the thermal shock resistance of the crucible in the process of smelting and precise casting of TiAl alloy, and can meet the requirement of high superheat degree during alloy smelting; the inner layer and the outer layer of the micro/nano double-scale yttrium oxide crucible are tightly combined, the purity of the yttrium oxide crucible is as high as 99.99 percent, and the TiAl alloy is prevented from being polluted by impurity elements in the smelting and precision casting processes.)

1. A micro/nano double-scale yttrium oxide crucible is characterized in that: the crucible is prepared from micron-level yttrium oxide powder and nanometer-level yttrium oxide powder.

2. The micro/nano dual scale yttria crucible of claim 1, wherein: the crucible comprises an inner layer and an outer layer, wherein the outer layer is made of micron-scale yttrium oxide, the inner layer is made of nanometer-scale yttrium oxide, and the nanometer-scale yttrium oxide of the inner layer is tightly combined with the micron-scale yttrium oxide of the outer layer.

3. The micro/nano dual scale yttria crucible of claim 1, wherein: the yttrium oxide content of the crucible is not less than 99.99%.

4. A method of making a micro/nano dual scale yttria crucible according to any of claims 1-3, wherein: comprises the following steps of (a) carrying out,

(1) preparation of micron-scale yttrium oxide slurry

Taking micron-grade yttrium oxide powder, a ceramic additive, deionized water and a defoaming agent, putting the raw materials into a ball mill, and wet-mixing for 1-10h, wherein the solid phase content of the micron-grade yttrium oxide is 15-60%, the content of the ceramic additive is 0.05-2.0%, and the content of the defoaming agent is 0.05-1.0%;

(2) preparation of nano-scale yttrium oxide slurry

Putting the raw materials into a ball mill for wet mixing for 1-10h by taking nano-scale yttrium oxide powder, a ceramic additive, deionized water and a defoaming agent, wherein the solid phase content of the nano-scale yttrium oxide is 15-60%, the content of the ceramic additive is 0.05-2.0% and the content of the defoaming agent is 0.05-1.0%;

(3) making a grouting model by using water and gypsum in a mass ratio of 5:7, and drying;

(4) pouring the micron-scale yttrium oxide slurry prepared in the step (1) into a grouting model, standing for 30s-2min, and then pouring out the residual slurry to obtain an outer-layer micron-scale yttrium oxide crucible blank;

(5) pouring the nano-scale yttrium oxide slurry prepared in the step (2) into the micron-scale yttrium oxide blank prepared in the previous step, standing for 30s-2min, and pouring out the residual slurry to obtain a micro/nano double-scale yttrium oxide crucible blank;

(6) putting the micro/nano double-scale yttrium oxide crucible blank obtained in the step (5) into a drying oven to be dried for 72-240h at the temperature of 20-60 ℃;

(7) and (4) putting the micro/nano double-scale yttrium oxide crucible blank dried in the step (6) into a muffle furnace for sintering, wherein the sintering temperature is 1550-1850 ℃, and the sintering time is 5-20h, so as to obtain the micro/nano double-scale yttrium oxide crucible.

5. The method of making a micro/nano dual scale yttria crucible of claim 4, wherein: the granularity of the micron-level yttrium oxide powder is 3-150 mu m, and the granularity of the nanometer-level yttrium oxide powder is 5-400 nm.

6. The method of making a micro/nano dual scale yttria crucible of claim 4, wherein: the ceramic additive is any one of sodium hexametaphosphate, lithium citrate and sodium carboxymethyl cellulose.

7. The method of making a micro/nano dual scale yttria crucible of claim 4, wherein: the defoaming agent is any one of polypropylene glycol or n-butanol.

8. The method of making a micro/nano dual scale yttria crucible of claim 4, wherein: the grinding balls are zirconia grinding balls, wherein the mass ratio of the raw materials to the grinding balls is 1:1.5-1: 2.0.

9. The method of making a micro/nano dual scale yttria crucible of claim 4, wherein: the grinding balls comprise grinding balls with different particle sizes.

10. The method of making a micro/nano dual scale yttria crucible of claim 4, wherein: the rotating speed of the ball mill is 37-250 r/min.

Technical Field

The invention belongs to the technical field of ceramic crucibles, and particularly relates to a micro/nano dual-scale yttrium oxide crucible for TiAl alloy high-temperature smelting and precision casting and a preparation method thereof.

Background

The TiAl alloy shows huge application prospect in the fields of aerospace and engines at present, the TiAl alloy material is taken as a key research object in all countries of the world, but the molten TiAl alloy is extremely active in chemical property, has interface reaction with common crucible materials in different degrees and has complex mechanism, such as scouring and corrosion of the molten alloy on the inner surface of a shell, interaction between alloy elements under high temperature, diffusion and chemical reaction between materials and the like. These factors affect each other and interact with each other to form a pollution layer on the surface of the casting, which causes adverse effect on the internal quality of the casting and seriously limits the smelting and precise casting of TiAl alloy. Therefore, the problem to be solved is to find a crucible material with stable thermodynamic and chemical properties.

Aiming at the smelting and the precise casting of TiAl alloy, the currently used crucibles mainly comprise graphite crucibles, high-melting-point metal crucibles, oxide crucibles and zirconate crucibles. The oxide crucible has the characteristics of clean, bright and fine surface, no toxicity, no harm, stable chemical property, acid, alkali and salt resistance, strong atmospheric moisture corrosion resistance, good thermal stability, high temperature resistance, low thermal conductivity, low possibility of explosion due to rapid heat and cold accumulation and the like. Compared with other types of crucible materials, the crucible material has wide oxide sources and low price, and is suitable for casting TiAl alloy. Therefore, in recent years, the research on melting and precision casting of TiAl alloy crucibles has been focused mainly on oxide crucibles.

At present, the oxide crucibles used more frequently comprise CaO crucible and Al crucible₂O₃Crucible and ZrO₂Crucible, Y₂O₃Crucibles, and the like. The CaO crucible is easy to react with moisture in the air, and the manufacturing process of the crucible has certain difficulty; al (Al)₂O₃After the TiAl alloy is smelted in the crucible, the pollution layer is thicker and reaches 200 mu m; ZrO (ZrO)₂After the TiAl alloy is smelted in the crucible, the thickness of the pollution layer is 50-150 μm. According to standard free energy of oxide, Y₂O₃The highest stability in the interfacial reaction with the high-temperature molten alloy, and thus, Y₂O₃Is the preferable material of the crucible for TiAl alloy smelting and precision casting.

Because the preparation difficulty of the high-purity yttrium oxide crucible is high, the existing yttrium oxide crucible usually uses Y₂O₃As the crucible inner layer material. The yttrium oxide surface layer and the crucible body are usually made of SiO₂As a binder, Ti element and SiO element can react with each other in the smelting process of TiAl alloy₂Chemical reaction is generated, the reaction directly causes the yttrium oxide particles in the crucible to fall off from the crucible wall and enter the alloy melt, and as the smelting time is increased, Ti and SiO react₂The reaction is continuously carried out, a large amount of yttrium oxide particles are dissociated in the melt, severe pollution is caused to the TiAl alloy, and the quality of the alloy is reduced. Therefore, when an alloy is melted using an yttria crucible, the degree of superheat of the alloy melt is limited. However, the low superheat degree causes the TiAl alloy melt to have high viscosity and poor fluidity, so that the casting performance of the TiAl alloy melt is poor, and a casting with a complex shape and good quality is not easy to obtain. Therefore, in order to obtain good-quality TiAl alloy products, the alloy melt needs to have higher superheat degree during the smelting and precision casting of the TiAl alloy. However, with the rise of the melting temperature, the chemical reaction degree between the TiAl alloy melt and the crucible adhesive and the erosion and scouring action of the alloy melt on the crucible material are intensified, so that the crucible damage is accelerated, the quality of the alloy melt is deteriorated, and the requirements of TiAl melting and precision casting are difficult to meet. Therefore, it is highly desirable to develop an yttria crucible that satisfies the requirement of high superheat degree in the melting of TiAl alloys without causing the inner layer material to fall off.

Disclosure of Invention

The invention provides a micro/nano dual-scale yttrium oxide crucible and a manufacturing method thereof, aiming at solving the problems of TiAl alloy smelting and precision casting in the prior art.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a micron/nano double-scale yttrium oxide crucible is prepared from micron-scale yttrium oxide powder and nano-scale yttrium oxide powder.

The crucible comprises an inner layer and an outer layer, wherein the outer layer is made of micron-scale yttrium oxide, the inner layer is made of nanometer-scale yttrium oxide, the nanometer-scale yttrium oxide of the inner layer and the micron-scale yttrium oxide of the outer layer are tightly combined, and the structural schematic diagram is shown in figure 1.

The yttrium oxide content of the crucible is not less than 99.99%.

A preparation method of a micro/nano double-scale yttrium oxide crucible comprises the following steps:

(1) preparation of micron-scale yttrium oxide slurry

Taking micron-grade yttrium oxide powder, a ceramic additive, deionized water and a defoaming agent, putting the raw materials into a ball mill, and wet-mixing for 1-10h, wherein the solid phase content of the micron-grade yttrium oxide is 15-60%, the content of the ceramic additive is 0.05-2.0%, and the content of the defoaming agent is 0.05-1.0%;

(2) preparation of nano-scale yttrium oxide slurry

Taking nano-scale yttrium oxide powder, a ceramic additive, deionized water and a defoaming agent, putting the raw materials into a ball mill, wet-mixing for 1-10h, and eliminating powder agglomeration, wherein the nano-scale yttrium oxide solid phase content is 15% -60%, the ceramic additive content is 0.05% -2.0%, and the defoaming agent content is 0.05% -1.0%;

(3) making a grouting model by using water and gypsum in a mass ratio of 5:7, and drying the grouting model, wherein the grouting gypsum model is shown in figure 2;

(4) pouring the micron-scale yttrium oxide slurry prepared in the step (1) into a grouting model, standing for 30s-2min, and then pouring out the residual slurry to obtain an outer-layer micron-scale yttrium oxide crucible blank;

(5) pouring the nano-scale yttrium oxide slurry prepared in the step (2) into the micron-scale yttrium oxide blank prepared in the previous step, standing for 30s-2min, and pouring out the residual slurry to obtain a micro/nano double-scale yttrium oxide crucible blank;

(6) putting the micro/nano double-scale yttrium oxide crucible blank obtained in the step (5) into a drying oven to be dried for 72-240h at the temperature of 20-60 ℃;

(7) and (3) putting the micro/nano double-scale yttrium oxide crucible blank dried in the step (6) into a muffle furnace for sintering at 1550-1850 ℃ for 5-20h to obtain the micro/nano double-scale yttrium oxide crucible, wherein a material object diagram of the sintered micro/nano double-scale yttrium oxide crucible is shown in figure 3.

The granularity of the micron-level yttrium oxide powder is 3-150 mu m, and the granularity of the nanometer-level yttrium oxide powder is 5-400 nm.

The ceramic additive is any one of sodium hexametaphosphate, lithium citrate and sodium carboxymethyl cellulose.

The defoaming agent is one of polypropylene glycol or n-butyl alcohol.

The grinding balls are zirconia grinding balls, wherein the mass ratio of the raw materials to the grinding balls is 1:1.5-1: 2.0.

The grinding balls comprise grinding balls with different particle sizes.

The rotating speed of the ball mill is 37-250 r/min.

The invention has the beneficial effects that:

1. the nano-scale yttrium oxide inner layer forms a compact yttrium oxide shell through self-bonding in the sintering process, resists the corrosion of alloy melt in the smelting and precision casting processes of TiAl alloy, and prevents the alloy from being polluted.

2. The micron-level yttrium oxide outer layer has certain porosity after sintering, can improve the strength of the crucible, improves the thermal shock resistance of the crucible in the process of smelting and precision casting of TiAl alloy, and can meet the requirement of high superheat degree during alloy smelting.

3. The inner and outer layers of the micro/nano dual-scale yttrium oxide crucible are tightly combined (as shown in figure 4), and the advantages of a nano structure and a micro structure are achieved.

4. The yttrium oxide crucible has high purity reaching 99.99 percent, and avoids the pollution of impurity elements to TiAl alloy in the smelting and precision casting processes.

Drawings

FIG. 1 is a view showing the structure of a micro/nano dual-scale yttria crucible of the present invention.

Figure 2 is a schematic view of a slip cast plaster model.

FIG. 3 is a pictorial view of a micro/nano dual-scale yttria crucible made in accordance with the present invention.

FIG. 4 is a microstructure diagram of the interface between the inner and outer layers of the sintered micro/nano dual-scale yttria-based shell.

FIG. 5 shows the microstructure of the surface of a Ti-48Al alloy ingot inductively smelted by using a micron/nano double-scale yttrium oxide crucible prepared by the invention, and the surface of the ingot is free from yttrium oxide pollution.

FIG. 6 is a microstructure of the surface of a Ti-45Al-7Nb alloy ingot inductively melted by using a micro/nano dual-scale yttrium oxide crucible prepared by the invention, and the surface of the ingot is free from yttrium oxide pollution.

FIG. 7 shows the microstructure of the surface of a Ti-47Al-2Nb alloy ingot inductively melted by using a micron/nano dual-scale yttrium oxide crucible prepared by the invention, and the surface of the ingot is free from yttrium oxide pollution.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort belong to the protection scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.

A micro/nano double-scale yttrium oxide crucible is prepared from micron-scale yttrium oxide powder and nano-scale yttrium oxide powder.

As shown in fig. 1, a micro/nano dual-scale yttria crucible is composed of an outer layer of micron-scale yttria and an inner layer of nano-scale yttria, and the inner layer of nano-scale yttria and the outer layer of micron-scale yttria are tightly combined together, as shown in fig. 4. The nano-scale yttrium oxide of the inner layer has smaller crystal grain and pore size, and can improve the melt erosion resistance of the yttrium oxide crucible; the micron-scale yttrium oxide on the outer layer has larger grain size and pore size, so that the thermal shock resistance of the yttrium oxide crucible can be improved; the two characteristics are combined to manufacture the micro/nano dual-scale yttrium oxide crucible with good erosion resistance and thermal shock resistance.

The micro/nano double-scale yttrium oxide crucible is high in purity, the content of yttrium oxide is not less than 99.99%, other components added into the yttrium oxide crucible do not have ash residue after the crucible is sintered, and the purity of the crucible is guaranteed. The yttrium oxide crucible has high purity, and the chemical reaction of the alloy melt and other elements can be avoided in the process of smelting and precision casting of the TiAl alloy, so that the alloy is prevented from being polluted, and the TiAl alloy with good quality can be obtained.

A preparation method of a micro/nano double-scale yttrium oxide crucible comprises the following steps:

(1) preparation of micron-scale yttrium oxide slurry

Taking micron-grade yttrium oxide powder, a ceramic additive, deionized water and a defoaming agent, and putting the raw materials into a ball mill for wet mixing for 1-10h, wherein the solid phase content of the micron-grade yttrium oxide is 15-60%, the content of the ceramic additive is 0.05-2.0%, and the content of the defoaming agent is 0.05-1.0%.

(2) Preparation of nano-scale yttrium oxide slurry

The preparation method comprises the following steps of taking nanoscale yttrium oxide powder, a ceramic additive, deionized water and a defoaming agent, putting the raw materials into a ball mill, and carrying out wet mixing for 1-10 hours to eliminate powder agglomeration, wherein the solid phase content of the nanoscale yttrium oxide is 15-60%, the content of the ceramic additive is 0.05-2.0%, and the content of the defoaming agent is 0.05-1.0%.

The sequence of the step (1) and the step (2) is not certain, and can be exchanged, and the influence of the micron-scale yttrium oxide slurry or the nanometer-scale yttrium oxide slurry on the micron/nanometer double-scale yttrium oxide crucible is not great.

The solid content of the slurry is controlled in a proper range, so that the completion of the later grouting is ensured, the solid content is too high, the viscosity of the slurry is increased, and the fluidity and the stability are poor; the solid content is too low, the strength of the crucible blank obtained after slip casting is not enough, and the subsequent demoulding and sintering are not favorable.

The granularity of the micron-level yttrium oxide powder is 3-150 mu m, and the granularity of the nanometer-level yttrium oxide powder is 5-400 nm.

In the preparation process of the slurry, the grinding balls are zirconium oxide grinding balls, wherein the mass ratio of the raw materials to the grinding balls is 1:1.5-1:2.0, the grinding balls are mixed by three different particle sizes of large, medium and small, and the mass ratio is as follows: big ball: a middle ball: the small balls are =1:1:1, the rotating speed of the ball mill is set to be 37-250r/min, so that the impact and grinding effects of the grinding balls are fully exerted, and yttrium oxide powder is uniformly distributed in the slurry.

Deionized water is selected for preparation of the slurry to eliminate adverse effects of electrolytes present in the water on the properties of the slurry.

The ceramic additive is any one of sodium hexametaphosphate, lithium citrate and sodium carboxymethyl cellulose, the surface performance of the yttrium oxide powder is effectively improved by adding the ceramic additive, the viscosity of the slurry is reduced, and the stable slurry with good rheological property, uniform dispersion and high solid content is obtained, so that the aims of improving the grinding effect, reducing the water consumption and reducing the power consumption are fulfilled.

The defoaming agent is any one of polypropylene glycol and n-butyl alcohol, part of air can be mixed into the slurry in the ball milling process, and meanwhile, after the ceramic additive is added, undesirable bubbles can be generated in the ceramic slurry, so that small holes or pits are generated in the crucible blank. Therefore, a proper amount of defoaming agent is added into the slurry to eliminate the surface activity of the slurry and avoid the generation of bubbles.

The ceramic additive and the defoaming agent do not generate ash or generate little ash after the yttria crucible is sintered at high temperature, and almost have no influence on the purity of the yttria crucible.

(3) Making a grouting model by using water and gypsum in a mass ratio of 5:7, weighing the water and the gypsum powder according to the proportion, pouring the gypsum powder into the water, uniformly stirring, and preparing the grouting model, wherein the grouting gypsum model is shown in figure 2. The proportion of the gypsum cannot be too high, otherwise, the slurry absorption rate of the grouting model is too high, the blank is not easy to form, and the prepared grouting model is placed in a drying box for 100-200h for drying treatment.

(4) Pouring the micron-scale yttrium oxide slurry prepared in the step (1) into a dried grouting model, wherein the internal shape of the grouting model is the required crucible blank, removing water in the slurry by utilizing the capillary water absorption effect of a gypsum model so as to solidify, standing for 30s-2min to obtain a micron-scale yttrium oxide crucible blank body with a certain thickness, and pouring out the redundant slurry.

(5) And (3) pouring the nano yttrium oxide slurry prepared in the step (2) into the micron yttrium oxide blank prepared in the step (4), at the moment, placing the micron yttrium oxide in the gypsum model, continuously utilizing the capillary water absorption effect of the gypsum model to remove water in the nano yttrium oxide slurry, standing for 30s-2min to prepare a nano yttrium oxide crucible blank with a certain thickness, and then pouring out the redundant slurry. And simultaneously obtaining a micro/nano double-scale yttrium oxide crucible blank, and demolding to wait for the next operation.

(6) And (4) putting the micro/nano double-scale yttrium oxide crucible blank obtained in the step (5) into a drying oven for drying, wherein the drying temperature is as low as possible, and the drying time is as long as possible, so that the elimination of the bonding water in the blank is ensured. If the temperature is too high and the drying time is too fast, the evaporation speed of the residual moisture in the micro/nano yttrium oxide crucible blank is too fast, and the blank is cracked. Finally setting the drying temperature to be 20-60 ℃ and the drying time to be 72-240h to ensure the full drying of the embryo body.

(7) And (4) putting the micro/nano double-scale yttrium oxide crucible blank dried in the step (6) into a high-temperature muffle furnace for sintering, wherein the sintering temperature and the sintering time have important influence on the finally prepared micro/nano double-scale yttrium oxide crucible. The sintering temperature and the sintering time have certain mutual restriction characteristics and can compensate each other to a certain extent. The sintering temperature and the sintering time can be adjusted mutually so as to achieve the aims of mature primary crystal grain development, obvious crystal boundary, no excessive secondary crystal grain growth, uniform shrinkage, few pores, compact porcelain body and low energy consumption. Aiming at the characteristics of high melting point and high vitrification temperature of the yttrium oxide material, the optimal sintering temperature is set to 1550-1850 ℃, and the sintering time is 5-20h, so that the micro/nano dual-scale yttrium oxide crucible is obtained, and the micro/nano dual-scale yttrium oxide crucible material object is shown in figure 3.

The nano-scale yttrium oxide inner layer forms a compact yttrium oxide shell through self-bonding in the sintering process, resists the corrosion of alloy melt in the smelting and precision casting processes of TiAl alloy, and prevents the alloy from being polluted.

The micron-level yttrium oxide outer layer has certain porosity after sintering, can improve the strength of the crucible, improves the thermal shock resistance of the crucible in the process of smelting and precision casting of TiAl alloy, and can meet the requirement of high superheat degree during alloy smelting.

The finally prepared micron/nano double-scale yttrium oxide crucible has high purity reaching 99.99 percent, and effectively avoids the pollution of impurity elements to TiAl alloy in the smelting and precision casting processes.

Example 1:

1. weighing 45g of micron-sized yttrium oxide and 0.15g of lithium citrate, weighing 0.15ml of polypropylene glycol defoamer, adding the polypropylene glycol defoamer into 300ml of deionized water to obtain a mixture, and putting the mixture into a planetary ball mill for ball milling for 1h to obtain micron-sized yttrium oxide slurry, wherein the rotating speed of the ball mill is 37r/min, and the ball milling medium is zirconia balls.

2. Weighing 45g of nano-scale yttrium oxide and 0.15g of lithium citrate, weighing 0.15ml of polypropylene glycol defoamer, adding the polypropylene glycol defoamer into 300ml of deionized water to obtain a mixture, and putting the mixture into a planetary ball mill for ball milling for 1h to obtain nano-scale yttrium oxide slurry, wherein the rotating speed of the ball mill is 27r/min, and the ball milling medium is zirconia balls.

3. Weighing 210g of gypsum powder, pouring into 150ml of water, uniformly stirring to prepare the required crucible gypsum model, and putting the gypsum model into a drying oven to dry for 100 hours.

4. And pouring the prepared micron-scale yttrium oxide slurry into a gypsum model, standing for 30s, and discharging residual slurry to obtain a micron-scale yttrium oxide crucible blank.

5. And pouring the prepared nano-scale yttrium oxide slurry into the micron-scale yttrium oxide blank prepared in the last step, and standing for 30 s. And then discharging the residual slurry to obtain the micro/nano double-scale yttrium oxide crucible blank.

6. And (3) putting the micro/nano double-scale yttrium oxide crucible blank into a drying box, setting the drying temperature to be 20 ℃, and drying for 72 hours.

7. And (3) putting the dried micro/nano double-scale yttrium oxide crucible blank into a high-temperature muffle furnace for sintering, setting the temperature at 1550 ℃, and the sintering time at 5h, and then cooling to room temperature along with the furnace to obtain a micro/nano double-scale yttrium oxide crucible finished product.

Loading Ti-45Al (at,%) alloy in the prepared yttrium oxide crucible, placing in a vacuum induction melting furnace, vacuumizing to 4 × 10-3Pa, introducing high-purity argon for gas washing, and finally introducing argon to 0.5 × 10⁵And (4) performing induction melting after Pa, wherein the melting temperature is about 1650 ℃. Keeping for 3min after the alloy is completely melted, then turning off the power supply, taking out after the alloy is cooled, wherein the alloy ingot and the yttrium oxide shell are not adhered, the alloy surface is smooth, obvious columnar crystals can be seen by naked eyes, and the TiAl alloy lamellar structure can be directly seen by placing the alloy ingot into a scanning electron microscope for observation. Meanwhile, no inclusion of Y element was found, as shown in fig. 5. When the TiAl alloy is smelted, the smelting temperature is too high, a small amount of Al element volatilizes to form air holes on the surface of the alloy, after the smelting is finished, the alloy is cooled, the volume of the unexhausted gas is shrunk after the gas is cooled on the inner wall of the crucible, and air bubbles are formed on the surface of the alloy. Therefore, the use of the micro/nano dual-scale yttrium oxide crucible is very suitable for the smelting of TiAl alloy.

Example 2:

1. weighing 45g of micron-scale yttrium oxide and 0.45g of sodium carboxymethylcellulose, weighing 0.45ml of polypropylene glycol defoaming agent, adding the polypropylene glycol defoaming agent into 100ml of deionized water to obtain a mixture, and putting the mixture into a planetary ball mill for ball milling for 5 hours to obtain micron-scale yttrium oxide slurry, wherein the rotating speed of the ball mill is 100r/min, and the ball milling medium is zirconia balls.

2. Weighing 45g of nano-scale yttrium oxide and 0.45g of sodium carboxymethylcellulose, weighing 0.45ml of polypropylene glycol defoaming agent, adding the polypropylene glycol defoaming agent into 100ml of deionized water to obtain a mixture, and putting the mixture into a planetary ball mill for ball milling for 5 hours to obtain nano-scale yttrium oxide slurry, wherein the rotating speed of the ball mill is 100r/min, and the ball milling medium is zirconia balls.

3. Weighing 210g of gypsum powder, pouring into 150ml of water, uniformly stirring to prepare the required gypsum model, and putting the gypsum model into a drying oven to dry for 150 hours.

4. And pouring the micron-scale yttrium oxide slurry into the dried gypsum model, standing for 1min, and discharging the residual slurry to obtain a micron-scale yttrium oxide crucible blank.

5. And pouring the nano-scale yttrium oxide slurry into the micron-scale yttrium oxide blank body, standing for 1min, and discharging the residual slurry to obtain the micro/nano dual-scale yttrium oxide crucible blank body.

6. And (3) putting the micro/nano double-scale yttrium oxide crucible blank into a drying box, setting the drying temperature to be 40 ℃, and drying for 120 h.

7. And (3) putting the dried micro/nano double-scale yttrium oxide crucible blank into a high-temperature muffle furnace for sintering, setting the temperature at 1700 ℃, setting the sintering time to 10h, and then cooling to room temperature along with the furnace to obtain a finished product of the micro/nano double-scale yttrium oxide crucible.

The Ti-45Al-7Nb (at percent) alloy is loaded in a prepared yttrium oxide crucible and then placed in a vacuum induction melting furnace, the vacuum is pumped to 4 multiplied by 10 < -3 > Pa, then high-purity argon gas is introduced for washing, finally the induction melting is carried out after the argon gas is filled to 0.5 multiplied by 105Pa, and the melting temperature is about 1800 ℃. Keeping for 3min after the alloy is completely melted, then turning off the power supply, taking out after the alloy is cooled, wherein the alloy ingot and the yttrium oxide shell are not adhered, the alloy surface is smooth, obvious columnar crystals can be seen by naked eyes, the TiAl alloy lamellar structure can be directly seen by placing the alloy ingot into a scanning electron microscope for observation, and meanwhile, no Y element is mixed, as shown in figure 6. Therefore, the use of the micro/nano dual-scale yttrium oxide crucible is very suitable for the smelting of TiAl alloy.

Example 3:

1. weighing 60g of micron-grade yttrium oxide and 2.0g of sodium hexametaphosphate, weighing 1ml of n-butanol defoaming agent, adding into 100ml of deionized water to obtain a mixture, and putting the mixture into a planetary ball mill for ball milling for 10 hours to obtain micron-grade yttrium oxide slurry, wherein the rotating speed of the ball mill is 150r/min, and the ball milling medium is zirconia balls.

2. Weighing 60g of nano-grade yttrium oxide and 2.0g of sodium hexametaphosphate, weighing 1ml of n-butanol defoaming agent, adding into 100ml of deionized water to obtain a mixture, and putting the mixture into a planetary ball mill for ball milling for 5 hours to obtain nano-grade yttrium oxide slurry, wherein the rotating speed of the ball mill is 250r/min, and the ball milling medium is zirconia balls.

3. Weighing 210g of gypsum powder, pouring into 150ml of water, uniformly stirring to prepare the required crucible gypsum model, and putting the gypsum model into a drying oven to dry for 200 hours.

4. And pouring the micron-scale yttrium oxide slurry into a gypsum model, standing for 2min, and discharging residual slurry to obtain a micron-scale yttrium oxide crucible blank.

5. And pouring the nano-scale yttrium oxide slurry into a micron-scale yttrium oxide blank, standing for 2min, and discharging the residual slurry to obtain the micro/nano dual-scale yttrium oxide crucible blank.

6. And (3) putting the micro/nano double-scale yttrium oxide crucible blank into a drying box, setting the drying temperature to be 60 ℃, and drying for 240 hours.

7. And (3) putting the dried micro/nano double-scale yttrium oxide crucible blank into a high-temperature muffle furnace for sintering, setting the temperature at 1850 ℃, and the sintering time to be 20h, and then cooling to room temperature along with the furnace to obtain a finished product of the micro/nano double-scale yttrium oxide crucible.

Loading Ti-47Al-2Nb (at percent) alloy in a prepared yttrium oxide crucible, placing the yttrium oxide crucible in a vacuum induction melting furnace, vacuumizing to 4 x 10 < -3 > Pa, introducing high-purity argon for gas washing, finally filling argon to 0.5 x 105Pa, and then carrying out induction melting at the melting temperature of 1780 ℃. Keeping for 3min after the alloy is completely melted, then turning off the power supply, taking out after the alloy is cooled, wherein the alloy ingot and the yttrium oxide shell are not adhered, the surface of the alloy is smooth, and obvious columnar crystals can be seen by naked eyes; the TiAl alloy lamellar structure can be directly seen by observing the alloy cast ingot in a scanning electron microscope. Meanwhile, no inclusion of Y element was found, as shown in fig. 7. Therefore, the micro/nano dual-scale yttrium oxide crucible is very suitable for smelting TiAl alloy.

The above specific embodiments are only convenient for further detailed description of the technical scheme of the invention, but the invention is not limited to the embodiments.