Method for preparing fine-grain ceramic through photo-thermal rapid sintering
Through the photothermal rapid sintering method, low-energy-consuming and efficient ceramic fine crystallization is achieved using the array of halogen tungsten lamp tubes and water circulation equipment, solving the problems of universality and energy consumption in traditional ceramic sintering methods, achieving the applicability of a variety of atmospheres and materials, and improving the density and grain uniformity of the ceramics.
Patent Information
- Application Number
- CN202510309514.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-17
- Publication Date
- 2025-07-18
AI Technical Summary
The existing ceramic sintering technology is difficult to achieve fine crystallization in a low energy consumption, high efficiency and controllable atmosphere, especially in an oxygen-rich environment, and the traditional methods are poor in universality and limited material selection.
The photothermal rapid sintering method is adopted, and the array of halogen tungsten lamps is used as the heating source to control the power of halogen tungsten lamps through program to achieve a cooling rate control of 20-400℃/s. Combined with water circulation equipment and a diverse sintering atmosphere, it is suitable for vacuum, inert and oxidation atmospheres, and supports sintering of various materials and shapes.
It achieves rapid densification and fine crystallization with low energy consumption, has a wide range of applicable scenarios, and has a variety of material types and shapes. It solves the universality and energy consumption problems in traditional methods, and improves the density and grain uniformity of ceramics.
Smart Images
Figure CN120329035A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of ceramic sintering, and particularly relates to a method for rapidly sintering fine-grained ceramics by photoinduced heating. Background Art
[0002] Advanced ceramic materials play a crucial role in the industrial field with a series of excellent properties, and are widely used in fields such as aerospace, electronic devices, semiconductors, etc. However, the popularization and application of ceramic materials still face many problems and challenges. How to achieve low-energy consumption and high-efficiency preparation of high-performance materials, how to achieve rapid densification of materials, and prepare ceramic blocks with uniform structure and fine grains are still the goals constantly pursued by ceramic materials scientists.
[0003] Traditional sintering methods have a slow heating rate, the green body needs to be in a high-temperature environment for a long time, with high energy consumption, and at the same time, it will cause grain growth, making it difficult to obtain high-performance dense fine-grained ceramics. In order to achieve efficient preparation of fine-grained ceramics, researchers have tried many rapid sintering methods, such as microwave sintering, spark plasma sintering, flash sintering, and ultra-fast and ultra-high temperature sintering technology, etc., in order to rapidly heat up, reduce the sintering driving force, and promote the formation of a dense fine-grained structure. However, whether it is flash sintering, spark plasma sintering (SPS), microwave sintering, or newly developed ultra-fast sintering, etc., it is difficult to simultaneously achieve controllable rapid heating and cooling (heating rate > 102 °C / s, cooling rate > 10 °C / s), low energy consumption, high efficiency, and batch preparation of high-performance fine-grained dense ceramics in an oxygen-rich environment. The spark plasma sintering method requires complex pressure-assisted equipment, and the sample shape is single, with high cost and difficult to scale up the preparation; microwave sintering depends on the characteristics of the material absorbing microwaves, with poor universality; the flash sintering method has problems such as relying on material selection, uneven heating, and single size, making it difficult to be actually applied. Professor Liangbing Hu of the University of Maryland developed a new ultra-fast and ultra-high temperature sintering technology UHS, which is a sintering process with high universality, but it can only be sintered in a high vacuum / protective atmosphere, and the heating rate is too fast to be controlled. Based on the investigation of existing ceramic preparation methods, as shown in Table 1, it can be seen that the existing sintering technologies are difficult to balance the characteristics of low carbon, high efficiency, batchability, and universality, and cannot solve the problems such as fine crystallization in the preparation process of ceramics in various atmospheres.
[0004] Table 1 Characteristics of Different Rapid Sintering Methods
[0005]
[0006] Among them, T max represents the maximum heating temperature, t represents the high-temperature sintering time, and V H represents the maximum heating rate.
[0007] Existing rapid heating technologies mainly use electric current to heat carbon materials to achieve rapid temperature rise. For example, in spark plasma sintering technology, an electric current is used to heat a carbon mold to achieve rapid temperature rise, and in ultra-rapid sintering, an electric current is used to heat carbon paper or carbon felt to achieve extremely rapid temperature rise. This method allows for a wide selection of materials to be prepared, but is limited by the weak oxidation resistance of carbon materials. Therefore, this method can only be sintered under an inert protective atmosphere. Flash sintering uses the Joule heat of an electric current to heat the sample. Limited by the narrow current path, the heating and sintering area is limited, and there are high requirements for the sample shape selection and conductivity. The microwave heating principle of microwave sintering results in its heating efficiency depending on the wave absorption characteristics of the material, with poor universality. Summary of the Invention
[0008] Based on the above-mentioned disadvantages and deficiencies in the prior art, one of the objectives of the present invention is to at least solve one or more of the above-mentioned problems existing in the prior art. In other words, one of the objectives of the present invention is to provide a method for preparing fine-grained ceramics by photo-thermal rapid sintering that meets one or more of the foregoing requirements.
[0009] To achieve the above-mentioned invention objectives, the present invention adopts the following technical solutions:
[0010] A method for preparing fine-grained ceramics by photo-thermal rapid sintering, comprising the following steps:
[0011] (1) Press the green body and perform debinding treatment to obtain a green compact;
[0012] (2) Place the green compact on the sample stage, push it into the heating chamber, and control the sintering atmosphere;
[0013] (3) Set the photo-thermal heating parameters, and use the halogen tungsten lamp tube array provided in the heating chamber as the heating source to heat and sinter the green compact in the sintering atmosphere.
[0014] As a preferred solution, the photo-thermal heating parameters include the heating rate, peak temperature, and its holding time. The heating rate is 20 - 400 °C / s, the peak temperature is 600 - 1300 °C, and the holding time is 200 - 1800 s.
[0015] As a preferred solution, the heating chamber is provided with a water circulation device, and the water circulation device is turned on in step (2).
[0016] As a preferred solution, the sample stage is made of silicon carbide, silicon nitride, or aluminum nitride.
[0017] As a preferred solution, the sintering atmosphere is vacuum, Ar, N2, air, oxygen, CO2, or N2 / Ar mixture gas.
[0018] As a preferred solution, the heating and sintering in step (3) is one-step heating or multi-step heating.
[0019] As a preferred embodiment, the green body is disc-shaped, strip-shaped or of special-shaped.
[0020] As a preferred embodiment, in the step (1), the ceramic green body powder and the binder are mechanically mixed and dried, and after drying, they are pressed into shape to obtain a ceramic green body;
[0021] The ceramic green body is placed in a muffle furnace for heating to remove the binder, obtaining a green body.
[0022] As a preferred embodiment, the ceramic green body powder is titanium dioxide, zinc oxide, vanadium oxide, cerium oxide, barium titanate, sodium potassium niobate or sodium bismuth titanate.
[0023] As a preferred embodiment, the heating tungsten wire of the halogen tungsten lamp array is encapsulated in a quartz tube.
[0024] Compared with the prior art, the beneficial effects of the present invention are:
[0025] The present invention uses the near-infrared halogen tungsten lamp array arranged in the heating chamber of the furnace body to achieve rapid heating, controls the power of the halogen tungsten lamp through a program, accurately regulates the heating and cooling rates, and promotes the formation of a fine crystal structure and densification of the ceramic; by adjusting the power of the near-infrared halogen tungsten lamp array, the heating and cooling rate regulation of 20-400 °C / s can be achieved; the characteristics are: low energy consumption; simple equipment and simple operation; applicable in vacuum, inert and oxidation atmospheres, with a wide range of applicable scenarios; diversity in the selection of material types and shapes, with great universality.
[0026] The method for preparing fine-grained ceramics by photo-thermally rapid sintering of the present invention is particularly suitable for solving some problems in the sintering process of piezoelectric materials. Common piezoelectric materials such as PbTiO3, (K or Na)NbO3 and Na 0.5 Bi 0.5 TiO3. Conventionally, a muffle furnace (conventional heating rate 5-10 °C / min) is used for long-term sintering in air, which is likely to cause certain volatilization losses of A-site elements Pb, K, Na, Bi, introducing a certain concentration of oxygen vacancy defects in the matrix, affecting the mass diffusion and grain boundary migration during sintering, and facilitating grain growth; at the same time, it is not conducive to the densification of the ceramic, significantly reducing the breakdown strength and other properties of the piezoelectric ceramic. With the rapid development of the electronics industry, piezoelectric devices also show a trend of miniaturization, thin-layerization and high integration. To improve performance and reduce the thickness of piezoelectric ceramics, it is required that the microstructure of piezoelectric ceramics presents a fine-grained characteristic to meet the actual application requirements. At the same time, under the impetus of the dual-carbon policy and the low-carbon economy, the traditional high-energy-consuming and high-emission production methods will gradually be restricted and replaced, and the preparation of lead-free piezoelectric ceramics has also developed from the traditional high-temperature electric furnace treatment process to a new low-energy-consuming sintering process. Description of the Drawings
[0027] Figure 1 is the framework diagram of preparing fine-grained ceramics by photo-induced rapid sintering in Embodiment 1 of the present invention;
[0028] Figure 2 is the SEM image (a) of titanium dioxide fine-grained ceramics prepared by existing muffle furnace sintering (1250 °C - 5 min) and the SEM image (b) of titanium dioxide fine-grained ceramics prepared by photo-induced rapid sintering (1250 °C - 5 min) in Embodiment 1 of the present invention;
[0029] Figure 3 is the temperature-time curve (a) of preparing titanium dioxide fine-grained ceramics by photo-induced rapid sintering in Embodiment 1 of the present invention and the curve of temperature rise rate changing with time (b). Detailed implementation manners
[0030] To more clearly illustrate the embodiments of the present invention, the specific implementation manners of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings, and other implementation manners can also be obtained.
[0031] Embodiment 1:
[0032] The method for preparing titanium dioxide fine-grained ceramics by photo-induced rapid sintering in this embodiment includes the following steps:
[0033] (1) Press the green body. Add PVA into deionized water to make a 10 wt% binder, mechanically mix high-purity nano-titanium dioxide powder with the binder and dry it. Take 0.5 g of the dried mixed powder and add it into a mold, and press it into shape under a pressure of 300 MPa. The size of the green body is φ6 × 0.5 mm 3 ;
[0034] (2) Debinding treatment. Put the pressed green body into a muffle furnace, heat it up to 600 °C at a heating rate of 2 °C / min, keep it warm for 2 hours, and then cool it down with the furnace;
[0035] (3) Arrange the green body on the sample stage, push it into the middle of the heating chamber, and turn on the water circulation device. The chamber uses an air atmosphere;
[0036] Among them, the sample stage is made of a material with excellent high temperature resistance and thermal shock resistance, which can be silicon carbide, silicon nitride, and aluminum nitride plate, and silicon nitride thin plate is the best;
[0037] In addition, the sintering atmosphere can also be determined as vacuum, Ar, N2, air, oxygen, CO2, or N2 / Ar mixed gas according to actual application requirements;
[0038] (4) Set the photo-induced heating furnace program, such as Figure 1As shown, an infrared tungsten halogen lamp array arranged in a heating chamber is used as a heating source to heat and sinter a green body sample. The heating rate is 100 °C / s, the peak sintering temperature is 1250 °C, the heating power is 13 KW, and the holding times are set to 0 s, 60 s, 180 s, and 300 s respectively, followed by furnace cooling to room temperature.
[0039] Among them, the sample can be taken out when the temperature is 200 °C or below, and the circulating water and power supply are turned off when the chamber temperature drops to room temperature.
[0040] Figure 2 Figure 7 is the surface scanning electron microscope morphology of the sample prepared in Example 1. It can be seen that the ceramic sample prepared by rapid sintering forms a dense microstructure, and no obvious pores are observed; moreover, the ceramic grain size distribution is relatively uniform, within the range of 0.5 - 2 μm. For a traditional commercial muffle furnace, with a heating rate of 5 °C / min and under the treatment conditions of the same sintering temperature of 1250 °C for 300 s, the grain size reaches 2 - 3 μm and is not dense. Thus, it can be seen that photoinduced rapid heating can greatly improve the efficiency compared with the commonly used muffle furnace, and achieve fine grains and densification of titanium dioxide ceramics.
[0041] As Figure 3 shown, the instantaneous maximum temperature rise rate of photoinduced heating is as high as nearly 400 °C / s, and the temperature control is stable, and the temperature fluctuation is small in the high-temperature section, and the operation is stable.
[0042] Table 1 shows the densification and D50 particle size values of muffle furnace sintering and photoinduced heating sintering in Example 1 at 1250 °C for different treatment times. It can be seen from the figure that before reaching the sintering temperature of 1250 °C, the titanium dioxide green body sintered slowly by the muffle furnace gradually densifies, and at the same time the particle size also gradually increases. After reaching the sintering temperature, due to the weak thermal driving force, the densification slows down and the particle size increases greatly; while for photoinduced rapid heating, after rapidly rising to the predetermined sintering temperature, the densification rapidly increases under the thermal driving force, and at the same time the particle size increases slowly. After being treated at 1250 °C for 300 s, a densification of 99% is achieved.
[0043] Table 1 Ceramic property parameters of different sintering methods
[0044]
[0045] The present invention uses photoinduced heating for sintering, that is, an infrared tungsten halogen lamp array is used as a heating source (the heating wire is sealed in the tungsten halogen lamp), and the power of the tungsten halogen lamp is precisely controlled through a program to accurately regulate the heating and cooling rates, so as to realize rapid sintering and densification of materials with infrared light in a relatively large chamber.
[0046] 1. The easily oxidized heating tungsten wire is sealed in a quartz tube, avoiding oxidation by the atmosphere and enabling diverse sintering atmospheres, which has significant advantages compared to spark plasma sintering and ultra-rapid sintering.
[0047] 2. The chamber has a large size, allowing the size of the green body to be sintered to be unrestricted. It can be a wafer or a complex structural part produced by 3D printing, etc., which has significant advantages compared to spark plasma sintering and flash sintering.
[0048] 3. The furnace temperature is rapidly increased by the action of infrared light, and the combination of heat convection and heat radiation is used to promote the densification of the material during sintering. It has higher universality and significant advantages compared to the selectivity of materials in flash sintering and microwave sintering.
[0049] 4. Utilizing the characteristics of rapid heating and cooling, denser fine-grained ceramics can be prepared by combining two-stage sintering, etc.
[0050] Given that there are numerous embodiments of the present invention, the raw materials and processes involved can be selected according to actual needs within a limited range. The experimental data of each embodiment is huge and not suitable for listing one by one here. However, the verification content and the final conclusions obtained in each embodiment are similar. Therefore, the verification content of each embodiment will not be described one by one here.
[0051] The above description only elaborates in detail on the preferred embodiments and principles of the present invention. For those of ordinary skill in the art, based on the idea provided by the present invention, there will be changes in the specific implementation manners, and these changes should also be regarded as the protection scope of the present invention.
Claims
1. A method for preparing fine-grained ceramics by photothermal rapid sintering, characterized in that, It includes the following steps: (1) Press the green body and perform debinding treatment to obtain a green compact; (2) Place the green compact on the sample stage, push it into the heating chamber, and control the sintering atmosphere; (3) Set the photo-induced heating parameters, use the tungsten halogen lamp array set in the heating chamber as the heating source, and carry out temperature-raising sintering on the green compact in the sintering atmosphere.
2. The method according to claim 1, wherein The photo-induced heating parameters include the heating rate, peak temperature and its holding time. The heating rate is 20 - 400 °C / s, the peak temperature is 600 - 1300 °C, and the holding time is 200 - 1800 s.
3. The method according to claim 1, characterized in that, The heating chamber is equipped with a water circulation device, and the water circulation device is turned on in step (2).
4. The method according to claim 1, wherein The sample stage is made of silicon carbide, silicon nitride or aluminum nitride.
5. The method according to claim 1, characterized in that, The sintering atmosphere is vacuum, Ar, N2, air, oxygen, CO2 or N2 / Ar mixture gas.
6. The method according to claim 1, wherein The temperature-raising sintering in step (3) is one-step temperature-raising or multi-step temperature-raising.
7. The method according to claim 1, wherein The green compact is in the shape of a disc, strip or special shape.
8. The method according to any one of claims 1-7, characterized in that, In step (1), the ceramic green body powder is mechanically mixed with a binder and dried, and after drying, it is pressed into shape to obtain a ceramic green body; The ceramic green body is placed in a muffle furnace for heating and debinding to obtain a green compact.
9. The method according to claim 8, characterized in that, The ceramic green body powder is titanium dioxide, zinc oxide, vanadium oxide, cerium oxide, barium titanate, sodium potassium niobate or sodium bismuth titanate.
10. The method according to any one of claims 1-7, characterized in that The heating tungsten wire of the tungsten halogen lamp array is encapsulated in a quartz tube.