Yttrium oxide powder filling and sealing method

Abstract

The invention discloses a yttrium oxide powder filling and sealing method. The yttrium oxide powder filling and sealing method comprises the following steps that S101, a vibration platform is used for vibrating a rubber mold to remove residual stress; s102, the yttrium oxide powder is divided into 5-10 batches to be loaded into a rubber mold, after each batch of yttrium oxide powder is loaded, a vibration platform is started to vibrate, and the surface of the yttrium oxide powder is stricken; the operation is repeated until the yttrium oxide powder reaches the target height; s103, a sealing adhesive tape is used for winding the joint of the sealing cover and the rubber mold for at least three circles; s104, a PE film inner bag is adopted to wrap the rubber mold, and vacuumizing and sealing are conducted; then a PE film outer bag is used for secondary wrapping, vacuumizing and sealing are conducted, and the sealing position is coated with polyurethane waterproof paint; s105, the yttrium oxide powder in the rubber mold is pressed into a green body part through cold isostatic pressing treatment; the problems that powder filling is not uniform, sealing reliability is poor and a mold is prone to local deformation in a traditional preparation process of the large-size cake-shaped yttrium oxide green body can be solved.

Description

Technical Field

[0001] This invention relates to the field of yttrium oxide ceramics preparation, specifically to a method for filling and sealing yttrium oxide powder. Background Technology

[0002] Yttrium oxide ceramics occupy an important position in aerospace, semiconductor, and nuclear industries due to their excellent high-temperature stability, corrosion resistance, and optical properties. Cold isostatic pressing (CIP) technology, which enables uniform pressurization, is considered a key process for pressing powder into green bodies. However, for the preparation of large-sized (diameter ≥700mm) disc-shaped green bodies, traditional processes suffer from the following problems: First, traditional manual filling methods often result in uneven powder density distribution due to operational variations, directly affecting the quality of yttrium oxide green bodies; second, rubber molds are prone to sealing failure under high pressure, potentially leading to water leakage, which can contaminate the powder or damage equipment; third, large-sized molds are at risk of localized deformation under high pressure, which can cause powder leakage and even cracking of the green body, hindering the stable preparation of high-quality, large-sized yttrium oxide ceramic green bodies. Summary of the Invention

[0003] To overcome the above-mentioned shortcomings, the present invention aims to provide a method for filling and sealing yttrium oxide powder.

[0004] To achieve the above objectives, the technical solution adopted by the present invention includes the following steps: S101, Fix the disc rubber mold to the vibration platform, and use the vibration platform to vibrate the rubber mold to remove residual stress; S102, Yttrium oxide powder is divided into 5 to 10 batches and sequentially loaded into the rubber mold. After each batch of Yttrium oxide powder is loaded, the vibration platform is started to vibrate for 1 to 10 minutes to initially compact the Yttrium oxide powder. The surface of the Yttrium oxide powder is then smoothed along the inner edge of the rubber mold with a scraper. The above loading and vibration operation is repeated until the Yttrium oxide powder reaches the target height in the rubber mold. S103, cover the top opening of the rubber mold with a rubber sealing cap, and wrap the sealing tape around the connection between the sealing cap and the rubber mold at least three times; S104, the rubber mold with the sealing cap is wrapped in a PE film inner bag, vacuumed and sealed; then wrapped again in a PE film outer bag, vacuumed and sealed, and polyurethane waterproof coating is applied to the sealed area, which is then cured at room temperature to form a waterproof layer. S105, the sealed rubber mold is immersed in the water tank of a cold isostatic press, and the yttrium oxide powder in the rubber mold is pressed into a green part by cold isostatic pressing.

[0005] This application has the following beneficial effects: (1) First, the rubber mold is vibrated to remove its residual stress, and the powder density uniformity is improved by loading it into the rubber mold in batches and vibrating it to compact it (radial density deviation ≤2%), which effectively avoids the problem of cracking of the green body during the preparation process.

[0006] (2) By sealing the rubber mold and the sealing cap with sealing tape, and by sealing the rubber mold with PE inner bag and PE outer bag respectively, the rubber mold is made to leak zero water when the pressure is above 130MPa.

[0007] (3) It is suitable for the efficient preparation of large-sized yttrium oxide green blanks with a diameter of 500-1500 mm. In the preferred embodiment of the above-mentioned yttrium oxide powder filling and sealing method, in S101, the vibration frequency of the vibration platform is 50-100Hz, the amplitude is 0.5-1mm, and the duration is 5-10 minutes.

[0008] In the preferred embodiment of the above-mentioned yttrium oxide powder filling and sealing method, in S102, the target height of the yttrium oxide powder that is repeatedly vibrated and compacted in the rubber mold is at least 1 mm lower than the eaves of the rubber mold.

[0009] In the preferred embodiment of the above-mentioned yttrium oxide powder filling and sealing method, the thickness of the inner PE film bag is 0.1 mm and the pore size is no greater than 10 μm; the thickness of the outer PE film bag is 0.12 mm and the pore size is no greater than 10 μm.

[0010] In the preferred embodiment of the above-mentioned yttrium oxide powder filling and sealing method, the thickness of the polyurethane waterproof coating layer is 0.4-0.6 mm, and the curing time is not less than 30 minutes.

[0011] In the preferred embodiment of the above-mentioned method for filling and sealing yttrium oxide powder, in S105, the sealed rubber mold and sealing cap are immersed in the water tank of a cold isostatic press. The cold isostatic press presses the pressure to 100-200 MPa at a rate of 10-15 MPa / min and holds the pressure for 10-20 minutes, thereby forming the yttrium oxide powder in the rubber mold into a green part.

[0012] In the preferred embodiment of the above-mentioned yttrium oxide powder filling and sealing method, the inner surface of the rubber mold and the outer surface of the sealing cap are both coated with zinc stearate release agent. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the rubber mold and the sealing cap; Figure 2 A schematic diagram showing a rubber mold placed on a vibration platform; Figure 3 A schematic diagram showing a rubber mold placed inside a cold isostatic press; In the diagram: 1. Rubber mold; 2. Sealing cap; 21. Protrusion; 3. Vibrating platform; 4. Cold isostatic press. Detailed Implementation

[0014] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0015] It should be noted that in the description of this invention, terms such as "upper," "lower," "left," "right," "front," and "rear," which indicate direction or positional relationships, are based on the direction or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0016] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly, for example, referring to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0017] Example 1: like Figures 1 to 3 As shown, the yttrium oxide powder filling and sealing method of the present invention is applicable to the preparation of yttrium oxide green parts in large-size molds, and includes the following steps: (1) Selection and processing of molds The mold is a disc-shaped rubber mold 1 with an opening at the top. The diameter of the rubber mold 1 is not less than 500mm. The ratio of the height to the diameter of the rubber mold 1 is 1:1 to 1:5. The inner surface of the rubber mold 1 is coated with a release agent so that the yttrium oxide green part formed inside can be effectively demolded. The release agent can be zinc stearate.

[0018] The sealing cap 2 of the rubber mold 1 adopts a T-shaped cross-section structure. The protrusion 21 at the bottom of the sealing cap 2 can extend into the inner cavity of the rubber mold 1 through the top opening. The depth of the protrusion 21 of the sealing cap 2 into the inner cavity of the rubber mold 1 is at least 1 mm.

[0019] The mold (including rubber mold 1 and sealing cover 2) is fixed on the vibration platform 3. The vibration frequency of the vibration platform 3 is set to 50-100Hz and the amplitude is 0.5-1mm. The vibration lasts for 5-10 minutes. The vibration can remove the residual stress in the rubber mold 1, prompt the rubber mold 1 to make fine adjustments, reduce the deformation of the rubber mold 1 caused by stress, and improve the molding quality of the yttrium oxide green part.

[0020] (2) Filling operation Yttrium oxide powder with a particle size of 0.1-10μm is selected; 0.1-10μm yttrium oxide powder has extremely high specific surface area and surface energy, and is easy to agglomerate. After static pressing, the green parts obtained have higher density and uniform distribution.

[0021] Yttrium oxide powder is divided into five batches and loaded into rubber mold 1. After each batch of yttrium oxide powder is loaded, the vibration platform 3 is started and vibrated for 10 minutes to allow the loaded yttrium oxide powder to be initially compacted. Then, a scraper is used to smooth the surface of the compacted yttrium oxide powder along the inner edge of rubber mold 1 to ensure the flatness of the batch of yttrium oxide powder. The flatness error of each layer of compacted yttrium oxide powder is ±0.2mm. The density of the yttrium oxide powder after repeated filling into rubber mold 1 and initial compaction is 40%-50%. The target height of the initially compacted yttrium oxide powder is at least 1mm lower than the eaves of rubber mold 1 to fit the T-shaped sealing cap 2. After the sealing cap 2 is placed inside rubber mold 1, there is only a very small gap between rubber mold 1, sealing cap 2, and yttrium oxide powder.

[0022] (3) Mold sealing treatment The sealing materials used are sealing tape, PE inner film bag, and PE outer film bag; the width of the sealing tape is 20-30mm, the thickness of the PE inner film bag is 0.1mm, the pore size of the PE inner film bag is no greater than 10μm, and the thickness of the PE outer film bag is 0.12mm, with a pore size no greater than 10μm.

[0023] During the sealing process, the T-shaped rubber sealing cap 2 is placed over the opening of the rubber mold 1, and at least three turns of sealing tape are wrapped around the connection between the sealing cap 2 and the rubber mold 1. After the sealing tape is wrapped, the mold (including the rubber mold 1 and the sealing cap 2) is placed into the inner PE film bag. The inner PE film bag is sealed and vacuumed using a vacuum packaging machine. Then, an outer PE film bag is placed over it, and the outer PE film bag is sealed and vacuumed using a vacuum packaging machine. Finally, a polyurethane waterproof coating with a thickness of at least 0.4 mm is sprayed onto the sealed opening of the outer PE film bag and cured at room temperature for at least 30 minutes. By sequentially using the inner and outer PE film bags to seal the rubber mold 1 in multiple layers, the pressure transmission medium (such as water or oil) in the cold isostatic pressing equipment can be effectively prevented from seeping into the rubber mold 1 and contaminating the powder. At the same time, it can facilitate the subsequent demolding of the yttrium oxide preform and the cleaning of the mold.

[0024] (4) Cold isostatic pressing The sealed rubber mold 1 and sealing cap 2 are immersed in the water tank of the cold isostatic press 4. The cold isostatic press 4 presses the pressure to 100 MPa at a rate of 10 MPa / min and holds the pressure for 10 minutes, so that the yttrium oxide powder in the rubber mold 1 is formed into a green part.

[0025] Example 2: In this embodiment, a method for filling and sealing yttrium oxide powder includes the following steps: S101, Fix the disc rubber mold 1 to the vibration platform 3, and use the vibration platform 3 to vibrate the rubber mold 1 to remove residual stress; S102, Yttrium oxide powder is divided into six batches and loaded into rubber mold 1 in sequence. After each batch of Yttrium oxide powder is loaded, the vibration platform 3 is started to vibrate for 8 minutes to make the Yttrium oxide powder initially compacted. The surface of the Yttrium oxide powder is then scraped smooth along the inner edge of the rubber mold 1 with a scraper. The above loading and vibration operation is repeated until the height of the Yttrium oxide powder in the rubber mold 1 is at least 1 mm lower than the eaves of the rubber mold 1. S103, cover the top opening of the rubber mold 1 with the rubber sealing cap 2, and wrap the sealing tape at least three times at the connection between the sealing cap 2 and the rubber mold 1; S104, the rubber mold 1 with the sealing cap 2 is wrapped in a PE film inner bag, vacuumed and sealed; then a PE film outer bag is used for a second wrapping, vacuumed and sealed, and polyurethane waterproof coating is applied to the sealed area, which is then cured at room temperature to form a waterproof layer. S105, the sealed rubber mold 1 is immersed in the water tank of the cold isostatic press 4. The cold isostatic press 4 presses the pressure to 120 MPa at a rate of 11 MPa / min and holds the pressure for 12 minutes, so that the yttrium oxide powder in the rubber mold 1 is formed into a green part.

[0026] Example 3: In this embodiment, a method for filling and sealing yttrium oxide powder includes the following steps: S101, Fix the disc rubber mold 1 to the vibration platform 3, and use the vibration platform 3 to vibrate the rubber mold 1 to remove residual stress; S102, Yttrium oxide powder is divided into seven batches and loaded into rubber mold 1 in sequence. After each batch of Yttrium oxide powder is loaded, the vibration platform 3 is started to vibrate for 6 minutes to make the Yttrium oxide powder initially compacted. The surface of the Yttrium oxide powder is then scraped along the inner edge of the rubber mold 1 with a scraper. The above loading and vibration operation is repeated until the height of the Yttrium oxide powder in the rubber mold 1 is at least 1 mm lower than the eaves of the rubber mold 1. S103, cover the top opening of the rubber mold 1 with the rubber sealing cap 2, and wrap the sealing tape at least three times at the connection between the sealing cap 2 and the rubber mold 1; S104, the rubber mold 1 with the sealing cap 2 is wrapped in a PE film inner bag, vacuumed and sealed; then a PE film outer bag is used for a second wrapping, vacuumed and sealed, and polyurethane waterproof coating is applied to the sealed area, which is then cured at room temperature to form a waterproof layer. S105, the sealed rubber mold 1 is immersed in the water tank of the cold isostatic press 4. The cold isostatic press 4 presses the pressure to 140 MPa at a rate of 12 MPa / min and holds the pressure for 14 minutes, so that the yttrium oxide powder in the rubber mold 1 is formed into a green part.

[0027] Example 4: In this embodiment, a method for filling and sealing yttrium oxide powder includes the following steps: S101, Fix the disc rubber mold 1 to the vibration platform 3, and use the vibration platform 3 to vibrate the rubber mold 1 to remove residual stress; S102, Yttrium oxide powder is divided into eight batches and loaded into rubber mold 1 in sequence. After each batch of Yttrium oxide powder is loaded, the vibration platform 3 is started to vibrate for 4 minutes to make the Yttrium oxide powder initially compacted. The surface of the Yttrium oxide powder is then scraped along the inner edge of the rubber mold 1 with a scraper. The above loading and vibration operation is repeated until the height of the Yttrium oxide powder in the rubber mold 1 is at least 1 mm lower than the eaves of the rubber mold 1. S103, cover the top opening of the rubber mold 1 with the rubber sealing cap 2, and wrap the sealing tape at least three times at the connection between the sealing cap 2 and the rubber mold 1; S104, the rubber mold 1 with the sealing cap 2 is wrapped in a PE film inner bag, vacuumed and sealed; then a PE film outer bag is used for a second wrapping, vacuumed and sealed, and polyurethane waterproof coating is applied to the sealed area, which is then cured at room temperature to form a waterproof layer. S105, the sealed rubber mold 1 is immersed in the water tank of the cold isostatic press 4. The cold isostatic press 4 presses the material to 160 MPa at a rate of 13 MPa / min and holds the pressure for 16 minutes, so that the yttrium oxide powder in the rubber mold 1 is formed into a green part.

[0028] Example 5: In this embodiment, a method for filling and sealing yttrium oxide powder includes the following steps: S101, Fix the disc rubber mold 1 to the vibration platform 3, and use the vibration platform 3 to vibrate the rubber mold 1 to remove residual stress; S102, Yttrium oxide powder is divided into nine batches and loaded into rubber mold 1 in sequence. After each batch of Yttrium oxide powder is loaded, the vibration platform 3 is started to vibrate for 2 minutes to make the Yttrium oxide powder initially compacted. The surface of the Yttrium oxide powder is then scraped smooth along the inner edge of the rubber mold 1 with a scraper. The above loading and vibration operation is repeated until the height of the Yttrium oxide powder in the rubber mold 1 is at least 1 mm lower than the eaves of the rubber mold 1. S103, cover the top opening of the rubber mold 1 with the rubber sealing cap 2, and wrap the sealing tape at least three times at the connection between the sealing cap 2 and the rubber mold 1; S104, the rubber mold 1 with the sealing cap 2 is wrapped in a PE film inner bag, vacuumed and sealed; then a PE film outer bag is used for a second wrapping, vacuumed and sealed, and polyurethane waterproof coating is applied to the sealed area, which is then cured at room temperature to form a waterproof layer. S105, the sealed rubber mold 1 is immersed in the water tank of the cold isostatic press 4. The cold isostatic press 4 presses the pressure to 180 MPa at a rate of 14 MPa / min and holds the pressure for 18 minutes, so that the yttrium oxide powder in the rubber mold 1 is formed into a green part.

[0029] Example 6: In this embodiment, a method for filling and sealing yttrium oxide powder includes the following steps: S101, Fix the disc rubber mold 1 to the vibration platform 3, and use the vibration platform 3 to vibrate the rubber mold 1 to remove residual stress; S102, Yttrium oxide powder is divided into ten batches and loaded into rubber mold 1 in sequence. After each batch of Yttrium oxide powder is loaded, the vibration platform 3 is started to vibrate for 1 minute to make the Yttrium oxide powder initially compacted. The surface of the Yttrium oxide powder is then scraped along the inner edge of the rubber mold 1 with a scraper. The above loading and vibration operation is repeated until the height of the Yttrium oxide powder in the rubber mold 1 is at least 1 mm lower than the eaves of the rubber mold 1. S103, cover the top opening of the rubber mold 1 with the rubber sealing cap 2, and wrap the sealing tape at least three times at the connection between the sealing cap 2 and the rubber mold 1; S104, the rubber mold 1 with the sealing cap 2 is wrapped in a PE film inner bag, vacuumed and sealed; then a PE film outer bag is used for a second wrapping, vacuumed and sealed, and polyurethane waterproof coating is applied to the sealed area, which is then cured at room temperature to form a waterproof layer. S105, the sealed rubber mold 1 is immersed in the water tank of the cold isostatic press 4. The cold isostatic press 4 presses the pressure to 200 MPa at a rate of 15 MPa / min and holds the pressure for 20 minutes, so that the yttrium oxide powder in the rubber mold 1 is formed into a green part.

[0030] The large-sized yttrium oxide green blanks with diameters of 500-1500 mm prepared in the above embodiments have a green density of up to 62% of the theoretical value and a standard deviation of radial bending strength of <5%.

[0031] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for filling and sealing yttrium oxide powder, characterized in that, Includes the following steps: S101, Fix the disc rubber mold to the vibration platform, and use the vibration platform to vibrate the rubber mold to remove residual stress; S102, Yttrium oxide powder is divided into 5 to 10 batches and sequentially loaded into the rubber mold. After each batch of Yttrium oxide powder is loaded, the vibration platform is started to vibrate for 1 to 10 minutes to initially compact the Yttrium oxide powder. The surface of the Yttrium oxide powder is then smoothed along the inner edge of the rubber mold with a scraper. The above loading and vibration operation is repeated until the Yttrium oxide powder reaches the target height in the rubber mold. S103, cover the top opening of the rubber mold with a rubber sealing cap, and wrap the sealing tape around the connection between the sealing cap and the rubber mold at least three times; S104, the rubber mold with the sealing cap is wrapped in a PE film inner bag, vacuumed and sealed; then wrapped again in a PE film outer bag, vacuumed and sealed, and polyurethane waterproof coating is applied to the sealed area, which is then cured at room temperature to form a waterproof layer. S105, the sealed rubber mold is immersed in the water tank of a cold isostatic press, and the yttrium oxide powder in the rubber mold is pressed into a green part by cold isostatic pressing.

2. The method for filling and sealing yttrium oxide powder according to claim 1, characterized in that: In S101, the vibration platform operates at a vibration frequency of 50-100Hz, an amplitude of 0.5-1mm, and a duration of 5-10 minutes.

3. The method for filling and sealing yttrium oxide powder according to claim 1, characterized in that: In S102, the target height of the yttrium oxide powder, which is repeatedly vibrated and compacted within the rubber mold, is at least 1 mm below the eaves of the rubber mold.

4. The method for filling and sealing yttrium oxide powder according to claim 1, characterized in that: The inner PE film bag has a thickness of 0.1 mm and a pore size of no more than 10 μm; the outer PE film bag has a thickness of 0.12 mm and a pore size of no more than 10 μm.

5. The method for filling and sealing yttrium oxide powder according to claim 1, characterized in that: The thickness of the polyurethane waterproof coating layer is 0.4-0.6 mm, and the curing time is not less than 30 minutes.

6. The method for filling and sealing yttrium oxide powder according to claim 1, characterized in that: In S105, the sealed rubber mold and sealing cap are immersed in the water tank of a cold isostatic press. The cold isostatic press presses pressure to 100-200 MPa at a rate of 10-15 MPa / min and holds the pressure for 10-20 minutes, thereby forming the yttrium oxide powder in the rubber mold into a green part.

7. The method for filling and sealing yttrium oxide powder according to claim 1, characterized in that: The inner surface of the rubber mold and the outer surface of the sealing cap are both coated with zinc stearate release agent.

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