A sintering fixture structure for high-density ceramic irregular parts
By combining the crucible lid, crucible body, and ceramic microspheres, the problems of uneven heat distribution and stress release during the sintering process of irregularly shaped ceramic parts are solved, achieving efficient uniform heat transfer and stress buffering, thereby improving sintering quality and yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUHAN HAILING HUIZHI NEW MATERIAL CO LTD
- Filing Date
- 2025-07-01
- Publication Date
- 2026-07-03
AI Technical Summary
During the high-temperature sintering process of ceramic materials, the forming of large-sized irregularly shaped blanks is subject to problems such as uneven heating and difficulty in releasing structural stress, which leads to deformation, cracking, etc. Traditional methods are costly and have poor adaptability.
The system employs a combination structure of crucible lid, crucible body, and ceramic microspheres. It utilizes the gravity self-flow characteristics of micron-sized ceramic microspheres to fill the shrinkage gaps of the green body in real time, providing both uniform heat transfer and stress buffering functions. The ceramic microspheres with various particle size distributions provide support and a uniform temperature field.
It achieves uniform heat transfer and stress buffering in ceramic blanks, reduces the risk of deformation and cracking, improves sintering quality and yield, and is low in cost and easy to promote.
Smart Images
Figure CN224455380U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of ceramic green body sintering equipment, specifically relating to a sintering fixture structure for high-density ceramic irregular parts. Background Technology
[0002] In the high-temperature sintering process of ceramic materials, the forming of large-sized irregularly shaped blanks (such as curved components, thin-walled parts, or porous structural parts) has always been a technical challenge in the industry. In traditional sintering processes, uneven heating of the blank can easily lead to local temperature gradients, causing thermal stress concentration. At the same time, the structural stress generated by sintering shrinkage (usually reaching 10%-20%) is difficult to release effectively, often causing problems such as blank deformation and cracking, resulting in a yield rate that is generally less than 60%. Especially for large and complex ceramic components (such as turbine blades and battery separators) required in aerospace, new energy and other fields, traditional coating methods (such as plaster mold protection) have drawbacks such as low heat transfer efficiency and difficulty in demolding, while complex tooling fixtures are expensive and have poor adaptability.
[0003] In existing technologies, while using rigid molds to constrain the green body can partially control deformation, the difference in thermal expansion coefficients between the mold and the green body can easily lead to extrusion damage. While isostatic pressing can improve uniformity, it is difficult to adapt to complex irregular structures. In recent years, although some studies have attempted to use particulate media as a buffer layer, problems such as high-temperature particle adhesion and insufficient fluidity leading to incomplete filling are common, making dynamic stress compensation impossible. Therefore, designing a sintering fixture structure that can both ensure heat transfer uniformity and adapt to green body shrinkage has become crucial to overcoming the bottleneck in the manufacturing of irregular ceramic components. Utility Model Content
[0004] The technical problem to be solved by this utility model is to provide a sintering fixture structure for high-density ceramic irregular parts. The structure is compact, easy to use, and low in cost. It can fill the shrinkage gap of the ceramic blank in real time during the sintering process, and has the dual functions of uniform heat transfer and stress buffering, effectively ensuring the firing quality.
[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows:
[0006] A high-density ceramic irregular part sintering fixture structure includes: a crucible cover 1 and a crucible body 2. The crucible cover 1 is placed on top of the crucible body 2. The irregular ceramic blank 3 to be sintered is placed inside the crucible body 2, and the inner cavity shape of the crucible body 2 is adapted to the outer contour of the irregular ceramic blank 3. A predetermined number of ceramic microspheres 4 are filled between the outer surface of the irregular ceramic blank 3 and the inner cavity wall of the crucible body 2. The ceramic microspheres 4 adopt a variety of particle size distributions.
[0007] Preferably, an infrared temperature measurement through hole 6 is provided at the center of the top of the crucible lid 1, and a thermocouple temperature measurement groove 7 is provided at the bottom of the crucible body 2.
[0008] Preferably, both the crucible lid 1 and the crucible body 2 are made of graphite, and the outer surface of the inner cavity wall of the crucible body 2 is provided with a pressure-resistant layer 5, which is made of ceramic composite material.
[0009] Preferably, the outer surface of the pressure-resistant layer 5 is in contact with the ceramic microspheres 4, and the roughness of the outer surface of the pressure-resistant layer 5 is less than the roughness threshold required for the ceramic microspheres 4 to roll.
[0010] Preferably, the outer surface of the pressure-resistant layer 5 has multiple guide grooves for guiding the rolling direction of the ceramic microspheres 4.
[0011] Preferably, the width of the reserved gap between the outer surface of the irregular ceramic blank 3 and the inner wall of the crucible body 2 is adapted to the theoretical shrinkage of the irregular ceramic blank 3 after sintering.
[0012] Preferably, the outer surface of the ceramic microspheres 4 is coated with a nano-boron nitride coating of a preset thickness, and the coating coverage is not less than a preset coverage threshold.
[0013] Preferably, the particle size distribution of the ceramic microspheres 4 includes: 30% to 40% ceramic microspheres with a diameter of 50 to 100 μm; 40% to 50% ceramic microspheres with a diameter of 100 to 200 μm; and 10% to 20% ceramic microspheres with a diameter of 200 to 300 μm.
[0014] Preferably, the acute angles, thin walls and pores on the outer surface of the irregular ceramic blank 3 are all covered with alumina fiber felt of a preset thickness of two, and the porosity of the fiber felt is not less than a preset porosity threshold.
[0015] Preferably, the inner cavity shape of the crucible body 2 and the initial outer contour of the irregular ceramic blank 3 have a degree of conformity not less than a preset degree of conformity threshold.
[0016] Preferably, the bottom of the crucible body 2 is provided with multiple honeycomb-shaped support columns arranged in an array, and the material of the support columns is the same as that of the crucible body 2.
[0017] Compared with the prior art, the present invention has the following main advantages:
[0018] 1. This utility model has a compact overall structure, is easy to use and has low cost due to the reasonable arrangement of crucible lid, crucible body, irregular ceramic blank and ceramic microspheres. It utilizes the gravity self-flow characteristics of micron-sized ceramic microspheres to fill the shrinkage gap of ceramic blank in real time during sintering, and has the dual functions of uniform heat transfer and stress buffering, effectively ensuring the firing quality. It has broad application prospects and is easy to promote.
[0019] 2. The inner cavity shape of the graphite crucible body of this utility model is similar to that of the irregularly shaped ceramic blank, which can better transfer heat to the ceramic blank, achieve isothermal heating, and make the blank shrink uniformly.
[0020] 3. The embedded ceramic microspheres of this utility model, through a combination of various particle size distributions, can provide support for the green body on the one hand, and can quickly fill the gaps under the action of gravity after the green body shrinks, continuing to provide a uniform temperature field for the green body, improving the sintering uniformity of the green body, and reducing the risk of deformation and cracking of the green body. Attached Figure Description
[0021] Figure 1 This is an overall schematic diagram of the sintering fixture structure for high-density ceramic irregular parts in this embodiment of the present invention.
[0022] In the figure: 1-Crucible lid; 2-Crucible body; 3-Irregularly shaped ceramic blank; 4-Ceramic microspheres; 5-Pressure-resistant layer; 6-Infrared temperature measurement through hole; 7-Thermocouple temperature measurement groove. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0024] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0026] In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0027] The features and performance of this application will be further described in detail below with reference to the embodiments.
[0028] Example 1: This example provides a sintering fixture structure for high-density ceramic irregular-shaped parts, such as... Figure 1 As shown, it mainly includes: crucible lid 1, crucible body 2, irregularly shaped ceramic blank to be sintered 3, and ceramic microspheres 4;
[0029] The crucible lid 1 is placed on top of the crucible body 2. The crucible body 2 contains a shaped ceramic blank 3 to be sintered, and the inner cavity shape of the crucible body 2 is adapted to the outer contour of the shaped ceramic blank 3. A predetermined number of ceramic microspheres 4 are filled between the outer surface of the shaped ceramic blank 3 and the inner cavity wall of the crucible body 2. The ceramic microspheres 4 have a variety of particle size distributions.
[0030] Furthermore, an infrared temperature measurement through hole 6 is provided at the center of the top of the crucible lid 1, and a thermocouple temperature measurement groove 7 is provided at the bottom of the crucible body 2.
[0031] Furthermore, both the crucible lid 1 and the crucible body 2 are made of graphite, and the outer surface of the inner cavity wall of the crucible body 2 is provided with a pressure-resistant layer 5, which is made of ceramic composite material.
[0032] Furthermore, the outer surface of the pressure-resistant layer 5 is in contact with the ceramic microspheres 4, and the roughness Ra of the outer surface of the pressure-resistant layer 5 is ≤3.2μm.
[0033] Furthermore, the outer surface of the pressure-resistant layer 5 has multiple guide grooves for guiding the rolling direction of the ceramic microspheres 4. The guide grooves have a depth of 0.1~0.3mm, a width of 0.5~1mm, and a spacing of 2~5mm.
[0034] Furthermore, the width of the reserved gap between the outer surface of the irregular ceramic blank 3 and the inner wall of the crucible body 2 is adapted to the theoretical shrinkage of the irregular ceramic blank 3 after sintering.
[0035] Furthermore, the outer surface of the ceramic microspheres 4 is coated with a nano-boron nitride coating with a thickness of 10~50nm, and the coating coverage is ≥90% to ensure that the ceramic microspheres will not melt or deform at high temperatures.
[0036] Furthermore, the ceramic microspheres 4 are made of at least one of aluminum nitride, zirconium oxide, or silicon carbide, and the particle size distribution of the ceramic microspheres 4 includes: 30% to 40% of ceramic microspheres with a diameter of 50 to 100 μm; 40% to 50% of ceramic microspheres with a diameter of 100 to 200 μm; and 10% to 20% of ceramic microspheres with a diameter of 200 to 300 μm.
[0037] Furthermore, the acute angles, thin walls and pores on the outer surface of the irregular ceramic blank 3 are all covered with alumina fiber felt with a thickness of 1~3mm, and the porosity of the fiber felt is ≥70%.
[0038] Furthermore, the inner cavity shape of the crucible body 2 and the initial outer contour of the irregular ceramic blank 3 have a degree of fit that is not less than a preset degree of fit threshold.
[0039] Furthermore, the bottom of the crucible body 2 is provided with multiple honeycomb-shaped support columns arranged in an array. The support columns are 5-20mm high and 1-3mm in diameter, and the material of the support columns is the same as that of the crucible body 2.
[0040] In practical use:
[0041] 1) Prepare a crucible body whose inner cavity shape matches the outer contour of the blank. The inner cavity of the crucible is manufactured by processing a mold according to the outer contour of the blank. A uniform gap of 5~15mm is reserved between the inner cavity of the crucible and the surface of the blank.
[0042] 2) Filling with ceramic microspheres: High-temperature resistant ceramic microspheres with a particle size of 50~300μm are mixed according to particle size classification and then filled into the gaps. The microspheres are then compacted by vibration to form a dense stacked layer.
[0043] 3) Sintering process control: Place the crucible containing the green body and ceramic microspheres in the sintering furnace and heat it to the ceramic sintering temperature (1200~1900℃). When the green body shrinks, the ceramic microspheres dynamically fill the gaps under the action of gravity, so as to achieve uniform heat transfer and stress buffering.
[0044] 4) Cooling stage: Under the protection of nitrogen or inert gas, the temperature is reduced to room temperature at a rate of 5-15℃ / min, and the ceramic microspheres continuously provide support to prevent deformation.
[0045] The process parameters for vibration compaction are as follows: vibration frequency 10-30 Hz, amplitude 0.5-2 mm, vibration time 3-10 minutes, and filling density reaching 85%-95% of the theoretical density.
[0046] Example 2: This example provides a sintering fixture structure for high-density ceramic irregular parts. The crucible body 2 is made of high-purity graphite with a thermal conductivity of 350 W / (m•K). Both the inner cavity of the crucible and the irregular ceramic blank to be sintered are hemispherical.
[0047] Furthermore, the infrared temperature measurement through hole 6 opened at the center of the top of the crucible lid 1 is used to draw a vacuum and fill it with protective gas before sintering, and at the same time, it is used to directly measure the temperature around the blank by passing an infrared temperature measurement probe through the opening after sintering.
[0048] Furthermore, the ceramic microspheres are used in a mixed manner according to their particle size: larger particles provide support, smaller particles fill gaps, and vibration compaction is used during filling to ensure an initial tight arrangement;
[0049] As the furnace temperature rises, the green body gradually shrinks (it shrinks by about 10%-20% during ceramic firing), and gaps appear between the green body and the crucible, which were originally tightly attached to it. At this time, the ceramic microspheres automatically flow downward under the action of gravity, continuously filling the newly generated gaps and always enveloping the green body. The microspheres adhere tightly to the surface of the green body, evenly transferring heat and avoiding local overheating or undercooling. At the same time, the microsphere layer disperses the internal stress generated when the green body shrinks through rolling and slight deformation, preventing cracking caused by stress concentration.
[0050] When the temperature drops, the microspheres can continue to provide support, preventing the billet from deforming due to uneven cooling.
[0051] Furthermore, all parts of this application that are not described in detail are the same as or implemented using existing technology.
[0052] In summary:
[0053] 1. This utility model has a compact overall structure, is easy to use and has low cost due to the reasonable arrangement of crucible lid, crucible body, irregular ceramic blank and ceramic microspheres. It utilizes the gravity self-flow characteristics of micron-sized ceramic microspheres to fill the shrinkage gap of ceramic blank in real time during sintering, and has the dual functions of uniform heat transfer and stress buffering, effectively ensuring the firing quality. It has broad application prospects and is easy to promote.
[0054] 2. The inner cavity shape of the graphite crucible body of this utility model is similar to that of the irregularly shaped ceramic blank, which can better transfer heat to the ceramic blank, achieve isothermal heating, and make the blank shrink uniformly.
[0055] 3. The embedded ceramic microspheres of this utility model, through a combination of various particle size distributions, can provide support for the green body on the one hand, and can quickly fill the gaps under the action of gravity after the green body shrinks, continuing to provide a uniform temperature field for the green body, improving the sintering uniformity of the green body, and reducing the risk of deformation and cracking of the green body.
[0056] The above embodiments are only used to illustrate the design concept and features of this utility model, and their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly. The protection scope of this utility model is not limited to the above embodiments. Therefore, all equivalent changes or modifications made based on the principles and design ideas disclosed in this utility model are within the protection scope of this utility model.
Claims
1. A high density ceramic shaped part sintering tooling structure, characterized by: The crucible includes a crucible lid (1) and a crucible body (2). The crucible lid (1) is placed on top of the crucible body (2). The crucible body (2) contains a shaped ceramic blank (3) to be sintered. The inner cavity shape of the crucible body (2) is adapted to the outer contour of the shaped ceramic blank (3). A predetermined number of ceramic microspheres (4) are filled in the reserved gap between the outer surface of the shaped ceramic blank (3) and the inner cavity wall of the crucible body (2). The ceramic microspheres (4) have a variety of particle size distributions. An infrared temperature measurement through hole (6) is opened at the center of the top of the crucible lid (1). A thermocouple temperature measurement groove (7) is provided at the bottom of the crucible body (2).
2. The sintering fixture structure for high-density ceramic irregular parts according to claim 1, characterized in that: The crucible lid (1) and the crucible body (2) are both made of graphite, and the outer surface of the inner cavity wall of the crucible body (2) is provided with a pressure-resistant layer (5), which is made of ceramic composite material.
3. The sintering fixture structure for high-density ceramic shaped parts according to claim 2, characterized in that: The outer surface of the pressure-resistant layer (5) is in contact with the ceramic microsphere (4), and the roughness of the outer surface of the pressure-resistant layer (5) is less than the roughness threshold required for the ceramic microsphere (4) to roll.
4. The sintering fixture of claim 3, wherein: The outer surface of the pressure-resistant layer (5) has multiple guide grooves for guiding the rolling direction of the ceramic microspheres (4).
5. The sintering fixture structure for high-density ceramic shaped parts according to claim 1, characterized in that: The width of the reserved gap between the outer surface of the irregular ceramic blank (3) and the inner wall of the crucible body (2) is adapted to the theoretical shrinkage of the irregular ceramic blank (3) after sintering.
6. The sintering fixture structure for high-density ceramic irregular parts according to claim 1, characterized in that: The outer surface of each ceramic microsphere (4) is coated with a nano boron nitride coating of a preset thickness of one, and the coating coverage is not less than a preset coverage threshold.
7. The sintering fixture of claim 1, wherein: The particle size distribution of the ceramic microspheres (4) includes: 30% to 40% of ceramic microspheres with a diameter of 50 to 100 μm; 40% to 50% of ceramic microspheres with a diameter of 100 to 200 μm; and 10% to 20% of ceramic microspheres with a diameter of 200 to 300 μm.
8. The sintering fixture of claim 1, wherein: The acute angles, thin walls and pores on the outer surface of the irregular ceramic blank (3) are all covered with alumina fiber felt of a preset thickness of two, and the porosity of the fiber felt is not less than the preset porosity threshold.
9. The sintering fixture of claim 1, wherein: The inner cavity shape of the crucible body (2) and the initial outer contour of the irregular ceramic blank (3) have a degree of conformity that is not less than a preset degree of conformity threshold.
10. The sintering fixture structure for high-density ceramic shaped parts according to claim 1, characterized in that: The bottom of the crucible body (2) is provided with multiple honeycomb-shaped support columns arranged in an array, and the material of the support columns is the same as that of the crucible body (2).