A method for preparing a ceramic tube shell green body and a ceramic tube shell green body prepared by the method

Abstract

This invention discloses a method for preparing a ceramic tube shell green body and the prepared ceramic tube shell green body, relating to the field of ceramic tube shell processing. The method includes: S1 stacking green ceramic sheets sequentially to form a green ceramic sheet stack, and placing a release film at the bottom to form a green ceramic assembly; the required cavity is located within the coverage area of ​​the release film; S2 stacking one or more green ceramic assemblies on one set of green ceramic sheet stacks, and pressing them together to form a multi-layer green ceramic assembly; S3 using laser etching to etch layer by layer from top to bottom. Each time a layer of green ceramic assembly is etched, the green body above the release film of that layer is peeled off, thus completing the cavity opening. The bottommost green ceramic sheet stack does not participate in the etching. After all cavities are opened, a ceramic tube shell green body is formed. The ceramic tube shell prepared by this invention has extremely small cavity deformation, high airtightness, and good reliability; the cavity sidewalls are smooth, resulting in a high appearance qualification rate; the process is simplified, and production efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of ceramic tube shell processing technology, specifically to a method for preparing ceramic tube shell green bodies and the prepared ceramic tube shell green bodies. Background Technology

[0002] Ceramic housings have a wide range of applications in optical communication, providing electrical connections and mechanical support and protection for optical communication devices. Optical communication ceramic housings typically require cavities in the end sidewalls for welding optical window supports. However, the fabrication technology for multilayer ceramic housings is currently quite complex.

[0003] Chinese patent document CN115741937A discloses a method for manufacturing a ceramic tube shell for optical communication. The technical solution decomposes each cavity and bottom of the ceramic tube shell. First, the inner cavity or side cavity is opened in the green ceramic sheet, and then they are combined to form three independent stacked groups and isostatically pressed separately. Then, the three independent stacked groups are combined in sequence and isostatically pressed again.

[0004] 1. This technical solution involves at least four layers and isostatic pressing. The number of cavity openings is based on the number of green ceramic tile layers that make up the inner and side cavities. Therefore, the manufacturing process is complex and inefficient.

[0005] 2. The technical solution first creates a cavity in a single layer of green ceramic tile and then assembles it. Due to the influence of the alignment accuracy of the lamination process, the sidewall of the cavity inevitably exhibits obvious "misalignment".

[0006] 3. Since this technical solution involves assembling the cavity before isostatic pressing, the isostatic pressure is often controlled below 30MPa in order to minimize the deformation of the cavity caused by the isostatic pressure. However, a lower isostatic pressure often leads to insufficient density of the ceramic, increasing the leakage rate of the tube shell's airtightness. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a ceramic tube shell green body and its preparation method, thereby solving problems such as large cavity deformation, poor airtightness, interlayer misalignment of cavity sidewalls, rough surface, and complex forming process steps and low production efficiency of ceramic tube shells.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing a ceramic tube shell green body includes the following steps:

[0010] S1. Green ceramic sheets are stacked sequentially to form a green ceramic sheet stack, and a release film is placed at the bottom of the stack to form a green ceramic assembly. The release film, with the release agent coated on the release surface facing upward, is attached to the bottom surface of the green ceramic sheet stack. In the horizontal direction, the shape, size and position of the release film are consistent with the shape, size and position of the cavity to be opened, or the cavity to be opened is located within the coverage area of ​​the release film.

[0011] S2 stacks one or more of the green ceramic assemblies on a set of green ceramic sheet stacks. When there are ≥2 green ceramic assemblies, the size of the release film of the lower green ceramic assembly is smaller than the size of the release film of the upper green ceramic assembly, and is located within the coverage area of ​​the release film of the upper green ceramic assembly. Then, they are stacked to form a multi-layer green ceramic assembly.

[0012] S3 uses laser etching to etch the multi-layer green ceramic assembly layer by layer from top to bottom. The etching path is the side shape of the cavity to be opened. Each time a layer of green ceramic assembly is etched, the green blank above the release film of that layer is peeled off, thus completing the opening of the cavity for that layer. The bottom layer of green ceramic sheet stack does not participate in the etching. After all cavities are opened, a ceramic tube shell green blank is formed.

[0013] Preferably, the upper layer of the bottom layer of raw ceramic tile stack has multiple cavities, but all of them must be opened within the range of the upper layer of raw ceramic tile stack.

[0014] Preferably, the release film material in S1 is PET or thermosensitive plastic, and the thickness of the release film is 20~100um. PET release film has good rigidity and strength, and the opposite sides of the release surface of thermosensitive plastic release film are adhesive, which can improve the adhesion between the green ceramic assemblies. If the thickness of the release film is greater than 100um, it will cause delamination and non-sealing between the green ceramic assemblies. However, the release film should have a certain thickness, which is conducive to the tolerance of laser etching depth. The thicker the release film, the greater the tolerance of laser etching depth. If the thickness of the release film is less than 20um, it is not conducive to subsequent laser etching cavity opening and damage to the structure of the lower green ceramic assembly.

[0015] Preferably, the stacking method described in S2 includes uniaxial hot pressing and non-directional isostatic pressing. The stacking conditions are: vacuum covering, pressure 5~60MPa, temperature 50~90℃; uniaxial hot pressing, that is, heating the green ceramic assembly to the glass transition point temperature under vacuum and applying pressure from top to bottom; non-directional isostatic pressing, that is, isostatically pressing the green ceramic assembly at the glass transition point temperature; the above stacking conditions can ensure that the green ceramic assemblies are fused together and maintain good airtightness.

[0016] Preferably, the lamination conditions in S2 are: vacuum covering, pressure 40~60MPa, and temperature 60~80℃. The higher the lamination pressure, the higher the density of the ceramic green body, which is beneficial to the airtightness and reliability of the final product. However, the maximum capacity of the industry's temperature isostatic pressing equipment is 40~60MPa. The commonly used adhesive for green bodies is PVB (polyvinyl butyral), whose glass softening point temperature is 60~80℃. Within this temperature range, the bonding effect between the lamination layers is good.

[0017] Preferably, in S3, the laser etching depth is: the etching of each cavity layer is from the upper surface to 1 / 3 to 2 / 3 of the thickness of the release film layer; when the laser etching depth is too shallow, it will be difficult to release the green ceramic above; when the laser etching depth is too deep, it will damage the cavity structure of the next layer of green ceramic assembly.

[0018] Preferably, the laser etching parameters in S3 are: laser frequency of 30-50kHz, etching rate of 150-250mm / s, and power of 80%-90% of the maximum power of 40W. If the laser frequency is higher than 50kHz, it is easy to melt or overheat. If it is lower than 30kHz, although the heat-affected zone is reduced, the etching efficiency is low and it may not even be able to penetrate the required etching thickness. If the etching rate is lower than 150mm / s, the etching efficiency is affected. If the etching rate is higher than 250mm / s, the smoothness of the cavity edge will be poor, and problems such as burrs and gaps will occur. If the power is lower than 80%, the etching efficiency will be low. If the power is higher than 90%, the green blank is prone to scorching and blackening.

[0019] The ceramic tube shell green body prepared by the above-mentioned method includes one or more green ceramic assemblies and a bottom layer of green ceramic sheet stacks. The green ceramic assemblies include the green ceramic sheet stacks and a release film. The release film is embedded at the bottom of the green ceramic sheet stacks with its release surface facing upward, and its bottom surface is flush with the bottom surface of the green ceramic sheet stacks. The green ceramic sheet stacks include ≥1 green ceramic sheet, and each layer of green ceramic sheet, the green ceramic assemblies, and the green ceramic assemblies and the green ceramic sheet stacks are attached and fixedly connected to form a whole.

[0020] The bottommost layer of green ceramic tiles does not have cavities, while all green ceramic assemblies have cavities. The cavities in each green ceramic assembly are located within the coverage area of ​​the release film of that layer in the horizontal direction.

[0021] When there are ≥2 green ceramic assemblies, the horizontal dimension of the cavity in the lower green ceramic assembly is smaller than that in the upper green ceramic assembly, and the cavity is located within the range of the cavity in the upper green ceramic assembly. The cavities of each layer extend from top to bottom to the upper surface of the release film of that layer and are interconnected.

[0022] The release film of each green ceramic assembly adheres to the upper surface of the green ceramic sheet stack below it. The outer edge of each release film is in contact with the green ceramic sheet stack of that layer, and its inner edge is flush with the side of the cavity of the lower green ceramic sheet stack.

[0023] Preferably, the release film has at least one release surface; having two release surfaces results in better peeling performance, lower peeling force, and less deformation and damage to the ceramic when peeling off green ceramic.

[0024] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0025] 1. The ceramic tube shell prepared by the present invention has a very small cavity deformation and few cavity misalignments, thus improving the product qualification rate.

[0026] 2. The ceramic tube shell prepared by the ceramic tube shell green body of the present invention has high air tightness, good ceramic density, and good reliability;

[0027] 3. The ceramic tube shell cavity obtained by preparing the ceramic tube shell green body according to the present invention has a smooth sidewall and a high appearance qualification rate;

[0028] 4. The production steps of the ceramic tube shell obtained by the preparation of the ceramic tube shell green body of the present invention are greatly reduced, the process is simplified, and the production efficiency is greatly improved. Attached Figure Description

[0029] Figure 1 Schematic diagram of the cross-sectional structure of a single unit of green ceramic assembly;

[0030] Figure 2 Release membrane cross-sectional view;

[0031] Figure 3 Schematic diagram of the cross-sectional structure of a single-unit multi-layer green ceramic assembly;

[0032] Figure 4 Schematic diagram of laser etching path for a single unit multilayer green ceramic assembly;

[0033] Figure 5 Schematic diagram of the cross-sectional structure of a single unit ceramic tube shell green body;

[0034] Figure 6 Top view of a multi-unit ceramic tube shell green body;

[0035] Figure 7 Schematic diagram of the cross-sectional structure of a single-unit multi-cavity ceramic tube shell green body;

[0036] Figure 8 Example 1: Deformation of the ceramic tube shell cavity;

[0037] Figure 9 Example 2: Deformation of the ceramic tube shell cavity;

[0038] Figure 10 Example 3: Deformation of the ceramic tube shell cavity;

[0039] Figure 11 Example 4: Deformation of the ceramic tube shell cavity;

[0040] Figure 12 Example 5: Deformation of the ceramic tube shell cavity;

[0041] Figure 13 Comparative Example 1: Deformation of the ceramic tube shell cavity;

[0042] Figure labeling: 1. Green ceramic sheet stack, 2. Release film, 2-1. Release surface, 3. Green ceramic assembly, 4. Multilayer green ceramic assembly; 5. Laser etching path. Detailed Implementation

[0043] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0044] This invention provides the following technical solution:

[0045] like Figures 1-6 A method for preparing a ceramic tube shell green body includes the following steps:

[0046] S1. Green ceramic sheets are stacked sequentially to form a green ceramic sheet stack 1, and a release film 2 is placed at the bottom of it to form a green ceramic assembly 3; the release surface 2-1 of the release film 2, which is coated with release agent, is attached to the bottom surface of the green ceramic sheet stack 1 with the release surface facing upward; in the horizontal direction, the shape, size and position of the release film 2 are consistent with the shape, size and position of the cavity to be opened, or the cavity to be opened is located within the coverage area of ​​the release film 2.

[0047] S2 stacks one or more of the green ceramic assemblies 3 on a set of green ceramic sheet stacks 1. When there are ≥ 2 green ceramic assemblies 3, the size of the release film 2 of the lower green ceramic assembly 3 is smaller than the size of the release film 2 of the upper green ceramic assembly 3, and is located within the coverage area of ​​the release film 2 of the upper green ceramic assembly 3. This is to ensure that the cavity of the lower green ceramic assembly 3 is opened within the cavity area of ​​the upper layer, and then the layers are stacked to form a multi-layer green ceramic assembly 4.

[0048] S3 uses laser etching to etch the multi-layer green ceramic assembly 4 layer by layer from top to bottom. The laser etching route 5 is the side shape of the cavity to be opened. Each time a layer of green ceramic assembly 3 is etched, the green blank above the release film 2 of that layer is peeled off, thus completing the opening of the cavity of that layer. The bottom layer of green ceramic sheet stack 1 does not participate in the etching. After all cavities are opened, a ceramic tube shell green blank is formed.

[0049] Preferred, such as Figure 7 The bottom layer of raw ceramic tile stack 1 has multiple cavities in the upper layer of raw ceramic assembly 3, but all of them must be opened within the range of the cavity opened in the upper layer of raw ceramic assembly 3.

[0050] Preferably, the release film 2 in S1 is made of PET or thermosensitive plastic, and its thickness is 20~100µm. PET release film has good rigidity and strength, while the opposite sides of the release surface of thermosensitive plastic release film are adhesive, which can improve the adhesion between the green ceramic assemblies. If the release film thickness is greater than 100µm, it will cause delamination and lack of sealing between the green ceramic assemblies. However, the release film should have a certain thickness to facilitate the tolerance of laser etching depth. The thicker the release film, the greater the tolerance of laser etching depth. If the release film thickness is less than 20µm, it is not conducive to subsequent laser etching cavity opening and damage to the structure of the underlying green ceramic assembly.

[0051] Preferably, the stacking method described in S2 includes uniaxial hot pressing and non-directional isostatic pressing. The stacking conditions are: vacuum encapsulation, pressure 5~60MPa, and temperature 50~90℃. Uniaxial hot pressing involves heating the green ceramic assembly to its glass transition point temperature under vacuum and applying pressure from above and below. Non-directional isostatic pressing involves isostatically pressing the green ceramic assembly at its glass transition point temperature. The above stacking conditions can ensure that the green ceramic assemblies are fused together and maintain good airtightness.

[0052] Preferably, the lamination conditions in S2 are: vacuum covering, pressure 40~60MPa, and temperature 60~80℃. The higher the lamination pressure, the higher the density of the ceramic green body, which is beneficial to the airtightness and reliability of the final product. However, the maximum capacity of the industry's temperature isostatic pressing equipment is 40~60MPa. The commonly used adhesive for green bodies is PVB (polyvinyl butyral), whose glass softening point temperature is 60~80℃. Within this temperature range, the bonding effect between lamination layers is good.

[0053] Preferably, the laser etching depth in S3 is: the etching of each cavity layer is from the upper surface to 1 / 3 to 2 / 3 of the thickness of the release film 2; when the laser etching depth is too shallow, it will be difficult to release the green ceramic above; when the laser etching depth is too deep, it will damage the cavity structure of the next layer of green ceramic assembly.

[0054] Preferably, the laser etching parameters in S3 are: laser frequency of 30-50kHz, etching rate of 150-250mm / s, and power of 80%-90% of the maximum power of 40W. If the laser frequency is higher than 50kHz, it is easy to melt or overheat. If it is lower than 30kHz, although the heat-affected zone is reduced, the etching efficiency is low and it may not even be able to penetrate the required etching thickness. If the etching rate is lower than 150mm / s, the etching efficiency is affected. If the etching rate is higher than 250mm / s, the smoothness of the cavity edge will be poor, and problems such as burrs and gaps will occur. If the power is lower than 80%, the etching efficiency will be low. If the power is higher than 90%, the green blank is prone to scorching and blackening.

[0055] like Figure 5 The ceramic tube shell green body prepared by the method of preparation of the ceramic tube shell green body includes one or more green ceramic assemblies 3 and a bottom layer of green ceramic sheet stacks 1. The green ceramic assemblies 3 include green ceramic sheet stacks 1 and release film 2. The release surface 2-1 of the release film 2 is inlaid at the bottom of the green ceramic sheet stacks 1 with its bottom surface flush with the bottom surface of the green ceramic sheet stacks 1. The green ceramic sheet stacks 1 include ≥1 green ceramic sheet. Each layer of green ceramic sheet, the green ceramic assemblies 3, and the green ceramic assemblies 3 and the green ceramic sheet stacks 1 are attached and fixedly connected to form an integral whole.

[0056] The bottommost layer of green ceramic sheet stack 1 does not have cavities, while all green ceramic assemblies 3 have cavities. The cavities in each layer of green ceramic assemblies 3 are located within the coverage area of ​​the release film 2 of that layer in the horizontal direction.

[0057] When the green porcelain assembly 3 ≥ 2, the cavity of the lower green porcelain assembly 3 is smaller in the horizontal direction than the cavity of the upper green porcelain assembly 3, and the cavity is opened within the range of the cavity of the upper green porcelain assembly 3. The cavity of each layer extends from top to bottom to the upper surface of the release film 2 of that layer and is connected to each other. That is, except for the cavity of the uppermost green porcelain assembly 3, the cavities of other layers need to be opened again on the basis (within the range) of the cavity of the layer above.

[0058] The release film 2 of each layer of green ceramic assembly 3 is adhered to the upper surface of the green ceramic sheet stack 1 below it. The outer edge of each release film 2 is in contact with the green ceramic sheet stack 1 of that layer, and its inner edge is flush with the side of the cavity of the lower green ceramic sheet stack 1.

[0059] Preferably, the release film 2 has at least one release surface 2-1. Having two release surfaces facilitates the smooth peeling of the green blank etched away by the laser on the release surface, and also facilitates the peeling of the release film from the ceramic tube shell green blank.

[0060] Principle: Green ceramic sheets are stacked sequentially to form a green ceramic sheet stack 1, and a release film 2 is placed at the bottom to form a green ceramic assembly 3. Green ceramic assemblies 3 with larger release films are then placed on top, and so on, from largest to smallest, multiple layers of green ceramic assemblies 3 are stacked on top of the green ceramic sheet stack 1 in a single, direct stacking process. The green ceramic sheets soften and wrap around the release film, forming a multi-layered green ceramic assembly 4. Laser etching is then used to etch layer by layer along the edges of the release film, peeling off the green body layer by layer. The bottom layer of green ceramic sheet stack 1 is not etched, thus obtaining the ceramic tube shell green body. This method avoids multiple stacking processes and misalignment problems caused by stacking after assembly. Because the stacking is done before laser etching, deformation of the cavity is also avoided. Furthermore, adjusting the laser parameters solves the problem of surface roughness in the cavity. Optimizing the stacking parameters improves the density of the ceramic, significantly reducing defects such as porosity in the finished ceramic after subsequent high-temperature sintering, thus improving overall airtightness.

[0061] Example 1

[0062] A method for preparing a ceramic tube shell green body includes the following steps:

[0063] S1 Four 100-micron-thick green ceramic sheets are stacked sequentially to form a green ceramic sheet stack 1, and a release film 2 is placed at the bottom to form a green ceramic assembly 3. The size of the release film 2 is smaller than that of the green ceramic sheet stack 1. The release surface 2-1 of the release film 2, which is coated with release agent, is attached to the bottom surface of the green ceramic sheet stack 1 with the release agent facing upward. In the horizontal direction, the shape, size and position of the release film 2 are consistent with the shape, size and position of the cavity to be opened. The release film 2 is rectangular, that is, the cavity to be opened is rectangular. The release film 2 is arranged in multiple rows and columns on the green ceramic sheet stack 1 according to a certain size. The size is determined according to the structural requirements of the ceramic tube shell so that it can be subsequently hot-cut into multiple ceramic tube shell green units.

[0064] S2 stacks three green ceramic assemblies 3 on a set of green ceramic sheet stacks 1. The size of the release film 2 of the lower green ceramic assembly 3 is smaller than that of the release film 2 of the upper green ceramic assembly 3, and the center point of the release film 2 is consistent, and the shape and the setting direction of the release film 2 on the green ceramic assembly 3 are consistent. Then, they are stacked to form a multi-layer green ceramic assembly 4.

[0065] S3 uses laser etching to etch the multi-layer green ceramic assembly 4 layer by layer from top to bottom. The laser etching route 5 is the side shape of the cavity to be opened. Each time a layer of green ceramic assembly 3 is etched, the green blank above the release film 2 of that layer is peeled off, thus completing the opening of the cavity of that layer. The bottom layer of green ceramic sheet stack 1 does not participate in the etching. After all cavities are opened, a ceramic tube shell green blank is formed.

[0066] S4 performs hot cutting, glue removal, and sintering on the above-mentioned ceramic tube shell green body to obtain the ceramic tube shell.

[0067] In S1, the release film 2 is made of heat-sensitive plastic and has a thickness of 100 μm.

[0068] The stacking method described in S2 is non-directional warm isostatic pressing, and the stacking conditions are: vacuum covering, pressure 40MPa, temperature 80℃, and holding time 10 minutes.

[0069] Laser etching depth in S3: The etching of each cavity layer extends from the upper surface to 2 / 3 of the thickness of the release film 2.

[0070] The laser etching parameters in S3 are: laser frequency of 40kHz, etching rate of 250mm / s, and power of 90% of the maximum power of 40W.

[0071] The ceramic tube shell green body prepared by the method described above consists of three green ceramic assemblies 3 and a bottom layer of green ceramic sheet stacks 1. Each green ceramic assembly 3 consists of one green ceramic sheet stack 1 and one release film 2. The release surface 2-1 of the release film 2 is embedded at the bottom of the green ceramic sheet stack 1 with its bottom surface flush with the bottom surface of the green ceramic sheet stack 1. The green ceramic sheet stack 1 is composed of four green ceramic sheets with a thickness of 100 micrometers stacked together. Each layer of green ceramic sheet, each green ceramic assembly 3, and each green ceramic assembly 3 and the green ceramic sheet stack 1 are attached and fixedly connected to form a whole.

[0072] The bottommost green ceramic tile stack 1 does not have cavities, while all green ceramic assemblies 3 have cavities. The shape, size, and position of the cavities in the green ceramic assemblies 3 on the horizontal plane are consistent with the shape, size, and position of the release film 2 of that layer.

[0073] The size of the cavity in the lower green porcelain assembly 3 is smaller than that in the upper green porcelain assembly 3, and the center point of all cavities is in the same position. The shape of all cavities and their orientation on the green porcelain assembly 3 are the same. The cavities of each layer extend from top to bottom to the upper surface of the release film 2 of that layer and are interconnected. That is, except for the cavity of the uppermost green porcelain assembly 3, the cavities of other layers are opened on the basis of the cavity of the upper layer.

[0074] The release film 2 of the green ceramic assembly 3 is adhered to the step surface between the green ceramic sheet stack 1 and the lower green ceramic sheet stack 1. The outer edge of each release film 2 is in contact with the green ceramic sheet stack 1 of that layer, and its inner edge is flush with the side of the cavity of the lower green ceramic sheet stack 1.

[0075] The release film 2 has only one release surface 2-1.

[0076] Example 2

[0077] The difference from Example 1 is:

[0078] The green ceramic tile stack 1 is formed by stacking two green ceramic tiles with a thickness of 200 micrometers in sequence;

[0079] In S1, the release film 2 is made of PET and has a thickness of 20 μm. PET release film has good rigidity and strength.

[0080] The lamination method described in S2 is non-directional warm isostatic pressing. The lamination conditions are: vacuum covering, pressure of 5 MPa, temperature of 90°C, and holding time of 10 minutes. After lamination, the green ceramic sheet softens and wraps around the release film, ultimately forming a single piece.

[0081] Laser etching depth in S3: The etching of the cavity extends from the upper surface to 1 / 3 of the thickness of the release film 2.

[0082] The laser etching parameters in S3 are: laser frequency of 30kHz, etching rate of 150mm / s, and power of 80% of the maximum power of 40W.

[0083] Example 3

[0084] The difference from Example 1 is:

[0085] The green ceramic tile stack 1 is composed of five green ceramic tiles with a thickness of 80 micrometers stacked together;

[0086] The release film 2 described in S1 is made of heat-sensitive plastic and has a thickness of 50 μm.

[0087] The stacking method described in S2 is vacuum uniaxial hot pressing, and the stacking conditions are: vacuum covering, pressure 50MPa, temperature 60℃, and holding time 10 minutes.

[0088] Laser etching depth in S3: The etching of each cavity layer extends from the upper surface to half the thickness of the release film 2.

[0089] The laser etching parameters in S3 are: laser frequency of 50kHz, etching rate of 200mm / s, and power of 85% of the maximum power of 40W.

[0090] Example 4

[0091] The difference from Example 1 is:

[0092] Preparation method: The raw ceramic sheet stack 1 is composed of 10 raw ceramic sheets with a thickness of 50 micrometers stacked together;

[0093] The release film 2 described in S1 is made of PET and has a thickness of 100µm.

[0094] The stacking method described in S2 is vacuum uniaxial hot pressing, and the stacking conditions are: vacuum covering, pressure 60MPa, temperature 50℃, and holding time 10 minutes.

[0095] Laser etching depth in S3: The etching of each cavity layer extends from the upper surface to half the thickness of the release film 2.

[0096] The laser etching parameters in S3 are: laser frequency of 40kHz, etching rate of 150mm / s, and power of 83% of the maximum power of 40W.

[0097] Example 5

[0098] like Figure 7 The difference from Example 4 is:

[0099] The bottom layer of raw ceramic tile stack 1 has two cavities in the upper layer of raw ceramic assembly 3, and both cavities are opened within the range of the cavities opened in the upper layer of raw ceramic assembly 3.

[0100] The release film 2 of the upper layer of green ceramic assembly 3 above the bottom layer of green ceramic tile stack 1, in the horizontal direction, the cavity to be opened is located within the coverage area of ​​the release film 2, the size of the release film 2 is larger than the size of the two cavities, and the release film 2 has a release surface on one side.

[0101] Comparative Example 1

[0102] Twenty 100-micrometer-thick green ceramic sheets are divided into four equal parts and stacked separately. The first part of the green ceramic sheets has a first inner cavity and is stacked to form a first stacked group. The second part of the green ceramic sheets has a second inner cavity and is stacked to form a second stacked group. The third part of the green ceramic sheets has a third inner cavity and is stacked to form a third stacked group. The fourth part of the green ceramic sheets is the bottom of the ceramic tube shell and is stacked directly without a cavity to form a fourth stacked group. The second inner cavity is smaller than the first inner cavity, and the third inner cavity is smaller than the second inner cavity. The center point, shape, and orientation of the first, second, and third inner cavities are consistent.

[0103] The first, second, third, and fourth stacked layers are subjected to isostatic pressing (WHP) at 80°C and 5 MPa for 10 minutes to form a first green body, a second green body, a third green body, and a fourth green body, respectively. The third green body is placed on the fourth green body, the second green body is stacked on the third green body, and the first green body is stacked on the second green body to form a fifth green body. The fifth green body is subjected to WHP at 80°C and 5 MPa for 10 minutes to form a multilayer ceramic tube shell green body.

[0104] The multi-layer ceramic tube shell green body is hot-cut to form a single green body unit, the green body unit is debonded, and then sintered to obtain a multi-layer ceramic tube shell.

[0105] Results Comparison

[0106] The ceramic tube shells prepared in Examples 1-5 and Comparative Example 1 were tested, and the data are as follows:

[0107]

[0108] In summary, compared with the prior art (Comparative Example 1), the cavity misalignment and cavity deformation problems of Examples 1-5 are significantly improved; the ceramic density is increased, the airtightness is also significantly improved, and the yield is significantly increased compared with Comparative Example 1.

[0109] It should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0110] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a ceramic tube shell green body, characterized in that, Includes the following steps: S1. Green ceramic pieces are stacked sequentially to form a green ceramic piece stack (1), and a release film (2) is placed at the bottom of it to form a green ceramic assembly (3); the release surface (2-1) of the release film (2) is attached to the bottom surface of the green ceramic piece stack (1) with the release surface (2-1) facing upward; in the horizontal direction, the shape, size and position of the release film (2) are consistent with the shape, size and position of the cavity to be opened, or the cavity to be opened is located within the coverage area of ​​the release film (2) for opening the cavity; S2 stacks one or more of the green ceramic assemblies (3) on a set of green ceramic sheet stacks (1). When there are ≥2 green ceramic assemblies (3), the size of the release film (2) of the lower green ceramic assembly (3) is smaller than the size of the release film (2) of the upper green ceramic assembly (3) and is located within the coverage area of ​​the release film (2) of the upper green ceramic assembly (3). Then, the layers are stacked to form a multilayer green ceramic assembly (4). S3 uses laser etching to etch the multi-layer green ceramic assembly (4) layer by layer from top to bottom. The etching route is the side shape of the cavity to be opened. Each time a layer of green ceramic assembly (3) is etched, the green blank above the release film (2) of that layer is peeled off, thus completing the opening of the cavity of that layer. The bottom layer of green ceramic sheet stack (1) does not participate in the etching. After all cavities are opened, a ceramic tube shell green blank is formed.

2. The method for preparing ceramic tube shell green body according to claim 1, characterized in that, The bottom layer of raw ceramic tile stack (1) has multiple cavities in the upper layer of raw ceramic assembly (3), but all of them must be opened within the range of the cavity opened in the upper layer of raw ceramic assembly (3).

3. The method for preparing ceramic tube shell green body according to claim 1, characterized in that, The release film (2) described in S1 is made of PET or heat-sensitive plastic, and the thickness of the release film (2) is 20~100um.

4. The method for preparing a ceramic tube shell green body according to claim 1, characterized in that, The stacking methods described in S2 include uniaxial hot pressing and non-directional isostatic pressing. The stacking conditions are: vacuum covering, pressure 5~60MPa, and temperature 50~90℃.

5. The method for preparing a ceramic tube shell green body according to claim 4, characterized in that, The stacking conditions in S2 are: vacuum covering, pressure 40~60MPa, and temperature 60~80℃.

6. The method for preparing a ceramic tube shell green body according to claim 1, characterized in that, Laser etching depth in S3: The etching of each cavity layer is from the upper surface to 1 / 3 to 2 / 3 of the thickness of the release film (2).

7. The method for preparing a ceramic tube shell green body according to claim 1, characterized in that, The laser etching parameters in S3 are: laser frequency of 30-50kHz, etching rate of 150-250mm / s, and power of 80%-90% of the maximum power of 40W.

8. The ceramic tube shell green body prepared by the method for preparing ceramic tube shell green bodies according to any one of claims 1-7, characterized in that, It includes one or more raw ceramic assemblies (3) and a bottom layer of raw ceramic sheet stacks (1). The raw ceramic assemblies (3) include the raw ceramic sheet stacks (1) and a release film (2). The release surface (2-1) of the release film (2) is inlaid at the bottom of the raw ceramic sheet stacks (1) with its bottom surface flush with the bottom surface of the raw ceramic sheet stacks (1). The raw ceramic sheet stacks (1) include ≥1 raw ceramic sheet. Each layer of raw ceramic sheet, the raw ceramic assemblies (3), and the raw ceramic assemblies (3) and the raw ceramic sheet stacks (1) are attached and fixedly connected to form a whole. The bottommost layer of green ceramic sheet stack (1) does not have cavities, while all green ceramic assemblies (3) have cavities. The cavities of each green ceramic assembly (3) are located within the coverage area of ​​the release film (2) of that layer in the horizontal direction. When the number of green ceramic assemblies (3) is greater than or equal to 2, the size of the cavity in the lower green ceramic assemblies (3) in the horizontal direction is smaller than the size of the cavity in the upper green ceramic assemblies (3), and the cavity is located within the range of the cavity in the upper green ceramic assemblies (3). The cavities of each layer penetrate from top to bottom to the upper surface of the release film (2) of that layer and are connected to each other. The release film (2) of each layer of green ceramic assembly (3) is adhered to the upper surface of the green ceramic sheet stack (1) below it. The outer side of each release film (2) is in contact with the green ceramic sheet stack (1) of the same layer, and its inner side is flush with the side of the cavity of the lower green ceramic sheet stack (1).

9. The ceramic tube shell green body according to claim 8, characterized in that, The release film (2) has at least one release surface (2-1).

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