Preparation method of large-size yttrium oxide ceramic

Abstract

The invention discloses a preparation method of large-size yttrium oxide ceramic, and belongs to the technical field of preparation of advanced functional ceramic. The invention mainly solves the problem that the hydrolysis of the yttrium oxide powder affects the preparation of the high-quality yttrium oxide ceramic. The preparation method comprises the following steps: 1, preparing ceramic slurry; 2, forming a yttrium oxide ceramic biscuit; and 3, sintering. According to the method, starting from the essence of the yttrium oxide hydrolysis reaction, the hydrolysis content control method of the yttrium oxide nano-powder is created for the first time on the premise of not sacrificing the sintering activity of the yttrium oxide nano-powder by virtue of the wetting characteristic of the nano-powder and the reversible hydrolysis reaction of yttrium oxide hydrolysis; the problems of slurry system unbalance, viscosity increase, poor slurry uniformity and the like caused by yttrium oxide nano-powder hydrolysis are solved, and finally the high-performance yttrium oxide ceramic part is prepared.

Description

Technical Field

[0001] The invention relates to the field of advanced functional ceramics, and in particular to a method for preparing large-size yttrium oxide ceramics. Background Art

[0002] Yttria ceramics are a special functional ceramic product made from high-purity yttria powder. They belong to the cubic crystal system and have excellent heat resistance, corrosion resistance, wear resistance, electromagnetic shielding and plasma resistance. They are known as the "scavenger" of microelectronics manufacturing.

[0003] At present, yttrium oxide ceramics are mostly prepared by powder dry pressing technology. The preparation process first granulates the yttrium oxide powder, and then prepares it into the target product through molding preforming and isostatic pressing. The reason for this phenomenon is that the yttrium oxide powder is active in nature. In humid or other water-containing conditions, yttrium oxide reacts with water and then hydrolyzes, affecting the batch stability of the entire preparation process. In order to achieve the wet molding preparation of complex-shaped yttrium oxide parts, the Shanghai Institute of Silicates first performs anti-hydrolysis treatment on the yttrium oxide powder before it is officially used, that is, citric acid and polyurethane prepolymer are added to the yttrium oxide slurry using ethanol as a solvent for modification to obtain a polymer network-coated yttrium oxide powder. However, although this method can achieve the preparation of high-solid content slurry, citric acid and polyurethane prepolymers may react to generate citric acid polyester polyols, and the polyol polymer cannot be completely decomposed in a low-temperature environment. Therefore, it is impossible to further prepare high-quality ceramic parts. Summary of the invention

[0004] The purpose of the present invention is to provide a new process for preparing high-quality yttrium oxide ceramics.

[0005] To achieve the above object, the technical solution adopted by the present invention is carried out according to the following steps:

[0006] 1. Preparation of yttrium oxide ceramic slurry

[0007] 1.1. Boil the deionized water and keep it boiling for 5 to 8 minutes to ensure that the gas dissolved in the deionized water is completely removed. Through natural cooling, control the temperature of the gas-free deionized water at 5℃ to 15℃;

[0008] 1.2. Add high-purity yttrium chloride powder to the deionized water prepared in step 1.1, and heat and stir to obtain a saturated aqueous solution of yttrium chloride at a temperature of 45 to 55°C;

[0009] 1.3. Boil the saturated aqueous solution of yttrium trichloride obtained in step 1.2, then add nano yttrium oxide powder with a primary crystal size of 30 to 80 nm, and keep the ratio of nano yttrium oxide powder to deionized water at 0.3:1 to 0.45:1 to obtain a composite yttrium slurry;

[0010] 1.4. Dry and sieve the composite yttrium slurry obtained in step 1.3 to obtain composite yttrium powder, and calcine the obtained powder in air at a calcination temperature of 750 to 850° C. for 6 to 8 hours to obtain high-purity yttrium oxide powder;

[0011] 1.5. Wash the high-purity yttrium oxide powder obtained in step 1.4, centrifuge and filter, and then dry, bake and sieve to obtain yttrium oxide powder that can be used for water-based grouting molding;

[0012] 1.6. The yttrium oxide powder prepared in step 1.5 is prepared into a ceramic slurry with a volume solid content of 40 vol.% to 45 vol.%, wherein deionized water is used as a solvent, the dispersant is one of ammonium citrate, polyacrylic acid, and CE64, PVA is added as a binder, polyethylene glycol is added as a plasticizer, and the mixture is ball-milled for 6 to 8 hours;

[0013] 2. Yttria Ceramic Green Billet Forming

[0014] The slurry prepared in step 1 is subjected to exhaust treatment, and then injected into a gypsum mold, and demolded after the sample is dried to obtain an yttrium oxide ceramic blank, and the obtained ceramic blank is dried;

[0015] 3. Sintering

[0016] 3.1. Degreasing and debinding the green blank prepared in step 2, the degreasing temperature is 600-800°C, and the degreasing heating rate is 0.5-2.0°C / min;

[0017] 3.2, pre-sintering the ceramic body prepared in step 3.1 in air, with the air pre-sintering temperature being 1000-1200°C and the pre-sintering time being 2h-4h;

[0018] 3.3. The green body prepared in step 3.2 is vacuum sintered at a sintering temperature of 1580-1650° C. for 10-15 h, and then annealed at a annealing temperature of 1100-1250° C. for 10-20 h.

[0019] The stirring while heating in step 1.2 is performed by unidirectional low-speed stirring at a stirring speed of 10 to 30 r / min;

[0020] The nano yttrium oxide powder added in step 1.2 of step 1 is dispersed using a high-speed disperser, the dispersing rotary cutting speed is 4000-6000 r / min, the stirring time is 6-8 hours, and carbon dioxide gas needs to be continuously introduced during the dispersion process;

[0021] In step 1.5, the centrifugal speed is 2000-2500 r / min, and the centrifugal time is 3-5 min.

[0022] The amount of the dispersant added in 1.6 of step one is 0.5wt.% to 2.0wt.% of the mass of the yttrium oxide powder, the amount of the PVA added is 1wt.% to 3wt.% of the mass of the yttrium oxide powder, and the amount of the polyethylene glycol added is 0.3wt.% to 0.8wt.% of the mass of the yttrium oxide powder.

[0023] In step 2, the plaster mold is dried in advance in a blast drying oven at a drying temperature of 50 to 60° C. for a drying time of 6 to 10 hours.

[0024] The drying temperature of the ceramic blank in step 2 is 50-60° C. and the drying time is 24 hours.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The anti-hydration treatment of the present invention is achieved without reducing the sintering activity of yttrium oxide powder. The entire anti-hydration treatment includes three stages. First, yttrium trichloride is ionized in water to form yttrium ions and chloride ions. Excessive yttrium ions inhibit the hydrolysis of cubic yttrium oxide and are adsorbed on the surface of yttrium oxide powder in the drying stage to form a yttrium chloride hydration layer; secondly, during air calcination, the yttrium chloride hydration layer is thermally decomposed at high temperature to produce unstable yttrium oxide (orthorhombic system) powder; during the water washing process, orthorhombic yttrium oxide will preferentially hydrolyze into yttrium hydroxide, while the initially added yttrium oxide (belonging to the cubic system) will not be hydrolyzed under the action of yttrium hydroxide, so that the powder has a sintering activity.

[0027] 2. The solid content of the yttrium oxide slurry for grouting molding prepared by the present invention is significantly higher than the reported theoretical volume solid content of 37 vol.% for water-based yttrium oxide slurry in the literature. The slurry has good fluidity and no agglomeration phenomenon, and is suitable for grouting molding.

[0028] 3. The present invention adopts water-based wet molding, and the preparation process is energy-saving, environmentally friendly, green and efficient. The preparation process does not require the use of high-pressure equipment such as cold isostatic pressing and hot isostatic pressing. The density of the prepared product exceeds 4.97g / cm 3 , which is much higher than the density of yttrium oxide structural parts used in microelectronics, which is 4.92g / cm 3 The application technical indicators are in line with the development needs of the microelectronics industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 (a) is a physical picture of the solid cylinder prepared in Example 1, Figure 1 (b) is a physical picture of the yttrium oxide square sheet prepared in Example 2, Figure 1 (c) is a physical picture of the yttrium oxide semicircular ring prepared in Example 3.

[0030] Figure 2 SEM image of the sample of Example 2 after pre-sintering at 1200°C.

[0031] Figure 3 Cross-sectional SEM image of the sample prepared in Example 3. DETAILED DESCRIPTION

[0032] Example 1: The method for preparing high-quality yttrium oxide ceramics in this embodiment is carried out according to the following steps:

[0033] 1. Preparation of yttrium oxide ceramic slurry

[0034] 1.1. Boil the deionized water in a glass beaker and keep it boiling for 5 minutes to ensure that the gas dissolved in the deionized water is completely removed. Cool the deionized water by natural environment to control the temperature of the gas-free deionized water at 10°C.

[0035] 1.2. Add high-purity yttrium chloride powder to the deionized water prepared in step 1.1, and stir while heating. The stirring method is forward low-speed stirring at a stirring speed of 15 r / min. At a temperature of 45° C., a saturated aqueous solution of yttrium chloride is obtained;

[0036] 1.3. Boil the saturated aqueous solution of yttrium trichloride obtained in step 1.2, add nano yttrium oxide powder with a primary crystal size of 30nm to 80nm, and use a high-speed disperser to disperse the composite yttrium slurry with the nano yttrium oxide powder. The dispersing rotary cutting speed is 6000r / min, the stirring time is 8h, and the ratio of nano yttrium oxide powder to deionized water is maintained at 0.45:1. Carbon dioxide gas is continuously introduced during the dispersion process to obtain a composite yttrium slurry;

[0037] 1.4. Dry and sieve the composite yttrium slurry obtained in step 1.3 to obtain composite yttrium powder, and calcine the obtained powder in air at a calcination temperature of 800° C. for 6 hours to obtain high-purity yttrium oxide powder;

[0038] 1.5. The high-purity yttrium oxide powder obtained in step 1.4 is washed with deionized water, washed with a centrifuge and then centrifuged at a speed of 2500 r / min for 3 min, and then dried, baked and sieved to obtain yttrium oxide powder that can be used for water-based grouting molding;

[0039] 1.6. The yttrium oxide powder prepared in step 1.5 is configured into a ceramic slurry with a volume solid content of 40 vol.%, wherein deionized water is used as a solvent, 1.0 wt.% of ammonium citrate by weight of the yttrium oxide powder is added as a dispersant, 2.0 wt.% of PVA powder by weight of the yttrium oxide powder is added as a binder, and 0.8 wt.% of polyethylene glycol by weight of the yttrium oxide powder is added as a plasticizer, and the materials are mixed by a drum ball mill for 8 hours;

[0040] 2. Yttrium Oxide Billet Forming

[0041] The slurry prepared in step 1 was degassed and then injected into a gypsum mold. The mold was pre-dried in an oven at 60°C for 6 hours. After the sample was dried, it was demolded to obtain a yttrium oxide ceramic blank. The blank was then dried in a blast drying oven at a drying temperature of 55°C for 24 hours.

[0042] 3. Sintering

[0043] 3.1. Degreasing and debinding the green blank prepared in step 2, the degreasing temperature is 800°C, and the degreasing heating rate is 1.0°C / min;

[0044] 3.2, pre-sintering the ceramic body prepared in step 3.1 in air, with the air pre-sintering temperature being 1200°C and the pre-sintering time being 2h;

[0045] 3.3. The green body prepared in step 3.2 is vacuum sintered at a sintering temperature of 1600°C for 10 hours, and then annealed at a annealing temperature of 1100°C for 20 hours to obtain a corrosion-resistant yttrium oxide ceramic structural component for semiconductors. Figure 1 (a) shown.

[0046] Example 2: The method for preparing high-quality yttrium oxide ceramics in this embodiment is carried out according to the following steps:

[0047] 1. Preparation of yttrium oxide ceramic slurry

[0048] 1.1. Boil the deionized water in a glass beaker and keep it boiling for 8 minutes to ensure that the gas dissolved in the deionized water is completely removed. Cool the deionized water by natural environment to control the temperature of the gas-free deionized water at 15°C.

[0049] 1.2. Add high-purity yttrium chloride powder to the deionized water prepared in step 1.1, and stir while heating. The stirring method is forward low-speed stirring at a stirring speed of 30 r / min. At a temperature of 55° C., a saturated aqueous solution of yttrium chloride is obtained;

[0050] 1.3. Boil the saturated aqueous solution of yttrium trichloride obtained in step 1.2, add nano yttrium oxide powder with a primary crystal size of 30nm to 80nm, and use a high-speed disperser to disperse the composite yttrium slurry with the nano yttrium oxide powder. The dispersing rotary cutting speed is 5000r / min, the stirring time is 6h, and the ratio of nano yttrium oxide powder to deionized water is maintained at 0.45:1. Carbon dioxide gas is continuously introduced during the dispersion process to obtain a composite yttrium slurry;

[0051] 1.4. Dry and sieve the composite yttrium slurry obtained in step 1.3 to obtain composite yttrium powder, and calcine the obtained powder in air at a calcination temperature of 850° C. for 6 hours to obtain high-purity yttrium oxide powder;

[0052] 1.5. The high-purity yttrium oxide powder obtained in step 1.4 is washed with deionized water, washed with a centrifuge and then centrifuged at a speed of 2000 r / min for 5 min, and then dried, baked and sieved to obtain yttrium oxide powder that can be used for water-based grouting molding;

[0053] 1.6. The yttrium oxide powder prepared in step 1.5 is configured into a ceramic slurry with a volume solid content of 45 vol.%, wherein deionized water is used as a solvent, 1.0 wt.% of CE64 by weight of the yttrium oxide powder is added as a dispersant, 1.0 wt.% of PVA powder by weight of the yttrium oxide powder is added as a binder, and 0.5 wt.% of polyethylene glycol by weight of the yttrium oxide powder is added as a plasticizer, and the materials are mixed by a drum ball mill for 6 hours;

[0054] 2. Yttrium Oxide Billet Forming

[0055] The slurry prepared in step 1 is subjected to exhaust treatment, and then injected into a gypsum mold, the mold is pre-dried in an oven at 55°C for 6 hours, and the sample is demoulded after drying to obtain a yttrium oxide ceramic blank, and then the blank is dried in a blast drying oven at a drying temperature of 55°C for 24 hours;

[0056] 3. Sintering

[0057] 3.1. Degreasing and debinding the green blank prepared in step 2, the degreasing temperature is 600°C, and the degreasing heating rate is 2.0°C / min;

[0058] 3.2, air pre-sintering the ceramic body prepared in step 3.1, the air pre-sintering temperature is 1200°C, and the pre-sintering time is 4h;

[0059] 3.3. The green body prepared in step 3.2 is vacuum sintered at a sintering temperature of 1650°C for 15 hours, and then annealed at a annealing temperature of 1200°C for 20 hours to obtain a corrosion-resistant yttrium oxide ceramic structural component for semiconductors. Figure 1 (b) as shown.

[0060] Figure 2 The SEM image of the ceramic body prepared in Example 2 after pre-sintering in air at 1200° C. shows that no organic matter remains in the sample and a sintering neck has been formed.

[0061] Example 3: The method for preparing high-quality yttrium oxide ceramics in this embodiment is carried out according to the following steps:

[0062] 1. Preparation of yttrium oxide ceramic slurry

[0063] 1.1. Boil the deionized water in a glass beaker and keep it boiling for 5 minutes to ensure that the gas dissolved in the deionized water is completely removed. Cool the deionized water by natural environment to control the temperature of the gas-free deionized water at 5°C.

[0064] 1.2. Add high-purity yttrium chloride powder to the deionized water prepared in step 1.1, and stir while heating. The stirring method is forward low-speed stirring at a stirring speed of 15 r / min. At a temperature of 45° C., a saturated aqueous solution of yttrium chloride is obtained;

[0065] 1.3. Boil the saturated aqueous solution of yttrium trichloride obtained in step 1.2, add nano yttrium oxide powder with a primary crystal size of 30nm to 80nm, and use a high-speed disperser to disperse the composite yttrium slurry with the nano yttrium oxide powder. The dispersing rotary cutting speed is 4000r / min, the stirring time is 8h, and the ratio of nano yttrium oxide powder to deionized water is maintained at 0.45:1. Carbon dioxide gas is continuously introduced during the dispersion process to obtain a composite yttrium slurry;

[0066] 1.4. Dry and sieve the composite yttrium slurry obtained in step 1.3 to obtain composite yttrium powder, and calcine the obtained powder in air at a calcination temperature of 750° C. for 8 h to obtain high-purity yttrium oxide powder;

[0067] 1.5. The high-purity yttrium oxide powder obtained in step 1.4 is washed with deionized water, washed with a centrifuge and then centrifuged at a speed of 2500 r / min for 3 min, and then dried, baked and sieved to obtain yttrium oxide powder that can be used for water-based grouting molding;

[0068] 1.6. The yttrium oxide powder prepared in step 1.5 is configured into a ceramic slurry with a volume solid content of 45 vol.%, wherein deionized water is used as a solvent, 1.5 wt.% of CE64 by weight of the yttrium oxide powder is added as a dispersant, 3.0 wt.% of PVA powder by weight of the yttrium oxide powder is added as a binder, and 0.8 wt.% of polyethylene glycol by weight of the yttrium oxide powder is added as a plasticizer, and the materials are mixed by a drum ball mill for 8 hours;

[0069] 2. Yttrium Oxide Billet Forming

[0070] The slurry prepared in step 1 was degassed and then injected into a gypsum mold. The mold was pre-dried in an oven at 60°C for 6 hours. After the sample was dried, it was demolded to obtain a yttrium oxide ceramic blank. The blank was then dried in a blast drying oven at a drying temperature of 55°C for 24 hours.

[0071] 3. Sintering

[0072] 3.1. Degreasing and debinding the green blank prepared in step 2 at a degreasing temperature of 800°C and a degreasing heating rate of 1.5°C / min;

[0073] 3.2, pre-sintering the ceramic body prepared in step 3.1 in air, with the air pre-sintering temperature being 1100°C and the pre-sintering time being 2h;

[0074] 3.3. The green body prepared in step 3.2 is vacuum sintered at a sintering temperature of 1650°C for 15 hours, and then annealed at a annealing temperature of 1200°C for 10 hours to obtain a corrosion-resistant yttrium oxide ceramic structural component for semiconductors. Figure 1 (c) as shown.

[0075] Figure 3 The cross-sectional SEM of the sample prepared in Example 3 shows that the sample is broken without delamination or cracking, and only a small amount of intracrystalline pores exist, thus ensuring the high density of the sample.

[0076] The density of the yttrium oxide ceramic samples prepared in Example 1, Example 2 and Example 3 was tested by Archimedes method, and the purity of the yttrium oxide ceramic samples prepared in Example 1, Example 2 and Example 3 was tested by inductively coupled plasma mass spectrometry. The results are shown in Table 1:

[0077] Table 1 Test data

[0078] serial number Example 1 Example 2 Example 3 <![CDATA[Density (g / cm 3 )]]> 4.99 4.98 4.98 purity(%) 99.99 99.99 99.99

Claims

1. A method for preparing large-size yttrium oxide ceramics, characterized in that it comprises the following steps:

1. Preparation of yttrium oxide ceramic slurry 1.

1. Boil the deionized water and keep it boiling for 5 to 8 minutes to ensure that the gas dissolved in the deionized water is completely removed. Through natural cooling, control the temperature of the gas-free deionized water at 5 to 15°C; 1.

2. Add high-purity yttrium chloride powder to the deionized water prepared in step 1.1, and heat and stir to obtain a saturated aqueous solution of yttrium chloride at a temperature of 45 to 55°C; 1.

3. Boil the saturated aqueous solution of yttrium trichloride obtained in step 1.2, and then add nano yttrium oxide powder with a primary crystal size of 30 to 80 nm to obtain a composite yttrium slurry; 1.

4. Dry and sieve the composite yttrium slurry obtained in step 1.3 to obtain composite yttrium powder, and calcine the obtained powder in air at a calcination temperature of 750 to 850° C. for 6 to 8 hours to obtain high-purity yttrium oxide powder; 1.

5. Wash the high-purity yttrium oxide powder obtained in step 1.4, filter it by centrifugation, and then dry, bake, and sieve it to obtain yttrium oxide powder that can be used for water-based grouting molding; 1.

6. The yttrium oxide powder prepared in step 1.5 is prepared into a ceramic slurry with a volume solid content of 40 vol.% to 45 vol.%, wherein deionized water is added as a solvent, ammonium citrate, polyacrylic acid, and CE64 are added as a dispersant, PVA is added as a binder, and polyethylene glycol is added as a plasticizer, and the mixture is ball-milled for 6 to 8 hours; 2. Yttria Ceramic Green Billet Forming The slurry prepared in step 1 is subjected to exhaust treatment, and then injected into a gypsum mold, and demolded after the sample is dried to obtain an yttrium oxide ceramic blank, and the obtained ceramic blank is dried; 3. Sintering 3.

1. Degreasing and debinding the green blank prepared in step 2, the degreasing temperature is 600-800°C, and the degreasing heating rate is 0.5-2.0°C / min; 3.2, pre-sintering the ceramic body prepared in step 3.1 in air, the air pre-sintering temperature is 1000-1200°C, and the pre-sintering time is 2-4h; 3.

3. The green body prepared in step 3.2 is vacuum sintered at a sintering temperature of 1580-1650° C. for 10-15 h, and then annealed at a annealing temperature of 1100-1250° C. for 10-20 h.

2. A method for preparing a large-size yttrium oxide ceramic according to claim 1, characterized in that: The stirring while heating described in 1.2 of step 1 is performed in a unidirectional low-speed stirring manner with a stirring speed of 10 to 30 r / min.

3. A method for preparing a large-size yttrium oxide ceramic according to claim 1, characterized in that: The nano yttrium oxide powder added in step 1.2 is dispersed using a high-speed disperser, the dispersing rotary cutting speed is 4000-6000 r / min, the stirring time is 6-8 h, and carbon dioxide gas needs to be continuously introduced during the dispersion process.

4. A method for preparing a large-size yttrium oxide ceramic according to claim 1, characterized in that: In step 1.3 of the composite yttrium slurry, the ratio of nano yttrium oxide powder to deionized water is 0.3:1 to 0.45:

1.

5. A method for preparing a large-size yttrium oxide ceramic according to claim 1, characterized in that: In step 1.5, the centrifugal speed is 2000-2500 r / min, and the centrifugal time is 3-5 min.

6. A method for preparing a large-size yttria ceramic according to claim 1, characterized in that The amount of the dispersant added in 1.6 of step one is 0.5wt.% to 2.0wt.% of the mass of the yttrium oxide powder, the amount of the PVA added is 1wt.% to 3wt.% of the mass of the yttrium oxide powder, and the amount of the polyethylene glycol added is 0.3wt.% to 0.8wt.% of the mass of the yttrium oxide powder.

7. A method for preparing large-size yttrium oxide ceramics according to claim 1, characterized in that: In step 2, the plaster mold is pre-dried at a temperature of 50 to 60° C. for 6 to 10 hours.

8. A method for preparing large-size yttria ceramics according to claim 1, characterized in that: In step 2, the ceramic blank is dried at a temperature of 50-60° C. and for a drying time of 24 hours.

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