Method and device for promoting densification of sintered product through terahertz wave pretreatment

Abstract

The invention discloses a method for promoting densification of a sintered product through terahertz wave pretreatment, sintering is high-temperature sintering, and before high-temperature sintering, materials (raw material powder, raw material particles or prefabricated parts) used for high-temperature sintering are pretreated through terahertz waves, densification of the high-temperature sintered product is promoted, and the strength of the high-temperature sintered product is improved. The invention further discloses a sintered product pretreated through the terahertz waves and a device for promoting densification of the sintered product through pretreatment through the terahertz waves. The terahertz technology is applied to the field of material processing with high-temperature sintering as a main approach; high-temperature sintered materials are pretreated through non-contact and high-energy-efficiency terahertz waves, product densification can be promoted, and product strength can be improved. The method can be widely applied to high-temperature sintering processes in the fields of ceramics, metals, composite materials and the like, and has remarkable energy-saving and consumption-reducing effects and economic benefits besides promoting product densification, improving product strength and the like.

Description

Technical Field

[0001] The present invention relates to the field of material processing with high temperature sintering as the main approach, and in particular to a method and device for promoting the densification of sintered products by using terahertz wave pretreatment. Background Art

[0002] High temperature sintering is one of the important processes in material preparation and is widely used in the fields of ceramics, metals, composite materials, etc. Traditional high temperature sintering methods often have problems such as high energy consumption, long cycle, and insufficient material densification. In particular, insufficient material densification affects the strength of the product and affects the performance of the final product.

[0003] Terahertz (THz) waves refer to electromagnetic waves with a frequency range of 0.1-10 THz (wavelength of 30-3000 μm). The band of terahertz (THz) waves can cover the characteristic spectra of semiconductors, plasmas, organisms, and biomacromolecules. Using this frequency band can deepen and expand human understanding of some basic scientific issues in physics, chemistry, astronomy, informatics, and life sciences.

[0004] At present, many research institutions in China have carried out relevant research in the field of terahertz. However, most of the international and domestic research focuses on terahertz imaging technology and terahertz spectroscopy technology, and widely applies transmission imaging, spectral measurement and other functions to short-range radar, satellite communication, remote sensing, homeland security and counter-terrorism, highly confidential data communication and transmission, meteorological monitoring, security inspection, quality inspection, biomedical diagnosis and other fields. At present, there is no existing technology related to the use of terahertz wave pretreatment to promote the densification of sintered products. Summary of the invention

[0005] The first technical problem to be solved by the present invention is to provide a method for promoting the densification of sintered products, so that the densification of sintered products can be promoted through a special pretreatment method, the strength of the sintered products can be improved, and the performance of the sintered products can be improved.

[0006] The second technical problem to be solved by the present invention is to provide a sintered product, densify it, improve the strength of the sintered product, and further improve the performance of the sintered product.

[0007] The third technical problem to be solved by the present invention is to provide a special device used in the above method.

[0008] In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a method for promoting the densification of sintered products by using terahertz wave pretreatment, wherein the sintering is high-temperature sintering. Before the high-temperature sintering, the material used for high-temperature sintering is pretreated by using terahertz waves to promote the densification of the high-temperature sintered products and improve the strength of the high-temperature sintered products; the material used for high-temperature sintering is raw material powder, raw material particles or prefabricated parts.

[0010] As a further improvement of the present invention, the high temperature sintered product is a high temperature sintered product in the field of ceramics, metals or composite materials.

[0011] Furthermore, in the pretreatment, the material for high temperature sintering is treated with terahertz waves having a frequency of 0.1-10 THz and simultaneously subjected to a heating treatment.

[0012] Furthermore, when the material is raw material powder or raw material particles, the treatment temperature is 40-100°C and the treatment time is 1-3h; when the material is a preform, the treatment temperature is 120-200°C and the treatment time is 2-4h.

[0013] Furthermore, the high-temperature sintered product is a refractory skateboard; the pretreatment method is to pretreat the skateboard wet embryo preform or raw material powder with terahertz waves, dry it after pretreatment and then sinter it at high temperature; or dry the skateboard wet embryo preform, pretreat it with terahertz waves and then sinter it at high temperature.

[0014] Furthermore, the drying is drying at 200° C., and the high-temperature sintering is calcining at 730° C.

[0015] Furthermore, the high-temperature sintered product is a ceramic tile; the pretreatment method is to pretreat part or all of the raw material powder of the ceramic tile with terahertz waves and then perform high-temperature sintering, which can promote product densification, improve product strength and reduce product thickness at the same time.

[0016] Furthermore, the part of raw material powder is raw material powder with a mass percentage of 3-10%.

[0017] In a second aspect, the present invention provides a sintered product pretreated by terahertz waves, which is processed by the above-mentioned method of promoting densification of sintered products by terahertz wave pretreatment.

[0018] In a third aspect, the present invention provides a device for promoting the densification of sintered products by using terahertz wave pretreatment, wherein the device is a pretreatment device used in the method for promoting the densification of sintered products by using terahertz wave pretreatment; the pretreatment device comprises:

[0019] Device body;

[0020] A terahertz energy chamber disposed in the main body of the device;

[0021] A terahertz wave generator connected to the terahertz energy chamber to provide an energy source for the terahertz energy chamber;

[0022] It also includes an operation control system for controlling the temperature inside the terahertz energy cabin and the action time of the entire device.

[0023] By adopting the above technical solution, the present invention has at least the following beneficial effects:

[0024] (1) The present invention applies terahertz technology to the field of material processing with high-temperature sintering as the main method; by pretreating high-temperature sintered materials (raw material powders or prefabricated parts) through non-contact, high-efficiency terahertz waves, the densification of products can be promoted and the strength of products can be improved.

[0025] (2) The present invention uses a special device to generate terahertz waves of a specific frequency, and performs terahertz wave pretreatment for different lengths of time on different materials. In particular, temperature treatment is performed simultaneously with terahertz wave pretreatment, which can change the microstructure and improve the thermal conductivity, thereby significantly improving the densification during the sintering process and enhancing the mechanical properties of the final product. In addition, the sintering time and temperature can be reduced.

[0026] (3) This method can be widely used in high-temperature sintering processes in the fields of ceramics, metals, composite materials, etc. In addition to promoting the densification of sintered products and improving product strength and other properties, it also has significant energy-saving and consumption-reducing effects and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0028] Figure 1 It is a schematic flow chart of a method for promoting the densification of sintered products by using terahertz wave pretreatment in one embodiment of the present invention.

[0029] Figure 2 It is a schematic diagram of the structure of the device for promoting the densification of sintered products by using terahertz wave pretreatment in Example 1 of the present invention;

[0030] Figure 3 A structural diagram of the test product in Example 2 of the present invention. DETAILED DESCRIPTION

[0031] The present invention breaks through the application field of traditional terahertz technology. The traditional application field is mainly based on terahertz imaging technology and terahertz spectroscopy technology, and applies functions such as transmission imaging and spectrum measurement. The present invention mainly applies terahertz technology to the field of material processing with high-temperature sintering as the main method; Figure 1 As shown, before high-temperature sintering, the high-temperature sintering material (raw material powder, raw material particles or preforms) is pretreated by non-contact, high-efficiency terahertz waves, which can promote product densification and improve product strength. High-temperature sintering in the present invention refers to high-temperature sintering at a temperature of more than 300°C.

[0032] Densification of sintered products is a process of forming a dense whole of powder or granular materials through high temperature treatment. During the sintering process, diffusion, fusion and chemical reaction occur between particles to form new substances or change the microstructure. The densification effect depends on the process parameters such as sintering temperature, time, pressure, and the physical and chemical properties of the material.

[0033] The traditional sintering densification path mainly includes improving the chemical composition of the powder, increasing the green body density, increasing the sintering temperature, and extending the sintering time. The existing technology does not use terahertz technology to promote the densification of sintered products.

[0034] The mechanism of promoting sintering densification by terahertz wave pretreatment in the present invention mainly includes:

[0035] 1. Improve the surface properties of materials

[0036] Terahertz waves can act on the surface of powders, change their surface activity, increase surface active points, and increase the activation energy of the powder surface, thereby improving the sintering activity of the powders.

[0037] 2. Enhance material diffusion energy

[0038] Terahertz waves have strong penetrating power and can excite atoms or molecules in materials to achieve synchronous resonance, thereby enhancing the diffusion capacity of materials and possibly changing the sintering kinetics of powders, thereby promoting the diffusion and transmission effects of materials during the sintering process.

[0039] 3. Optimize the microstructure of materials

[0040] Terahertz waves can optimize the microstructure of materials through molecular synchronous resonance, improve the physical and chemical properties of materials, and make it easier to form a uniform and dense body during the sintering process.

[0041] 4. Improved thermal conductivity of materials

[0042] Terahertz waves have high-frequency vibration and energy transfer characteristics. Therefore, through the interaction between high-frequency electromagnetic waves and materials, efficient energy transfer is achieved, the energy value and activity of the molecules in the material itself are enhanced, and the thermal and electrical conductivity of the material is improved.

[0043] Using temperature treatment at the same time as terahertz wave treatment can stimulate the activity of the material itself, and the two work best together.

[0044] High temperature sintering is the main way to process products in the fields of ceramics, metals or composite materials. The working principles of using terahertz waves for pretreatment, promoting product densification and improving product strength in specific application fields of high temperature sintering are basically similar. The following examples will illustrate:

[0045] Embodiment 1: Device for promoting densification of sintered products by terahertz wave pretreatment

[0046] This embodiment provides a special pretreatment device, which mainly uses terahertz waves to pretreat materials used for high-temperature sintering, promotes product densification, and improves product strength; Figure 2 The pretreatment device includes: a device body 1; a terahertz energy chamber 2 arranged in the device body 1; a terahertz wave generator 3 connected to the terahertz energy chamber 2 to provide an energy source for the terahertz energy chamber 2; and also includes an operation control system for controlling the temperature inside the terahertz energy chamber and the action time of the entire device.

[0047] The pretreatment device in this embodiment is a whole, including an independent terahertz energy chamber 2 and a terahertz wave generator 3. The independent energy chamber can act as a waveguide, and can generate stable terahertz waves of specific frequency and intensity generated by the terahertz wave generator 3, and accurately guide the material to be processed (raw material powder, raw material particles or prefabricated parts) within a certain space. At the same time, it is also equipped with an operating control system for the temperature in the chamber and an operating control system for the action time of the terahertz wave generator, which can control the temperature and action time, and perform pretreatment at different temperatures and durations according to different materials, so as to change the microstructure of the material, improve its thermal conductivity, improve the density of the product, and improve the mechanical properties such as product strength.

[0048] The size and specifications of the above-mentioned pretreatment device can be determined according to the application and production capacity requirements.

[0049] In actual preprocessing, you can follow the steps below:

[0050] Open the terahertz energy chamber 2, place the material to be pretreated (raw material powder, raw material granules or prefabricated parts) in the center of the chamber, and close the door of the terahertz energy chamber 2. Select different temperatures on the control panel of the device body according to the different pretreatment materials, turn on the device, and set a certain time to shut down, so as to control the temperature in the terahertz energy chamber and the action time of the terahertz wave generator through the operation control system. The temperature and time settings are shown in Table 1:

[0051] Table 1 Temperature and duration settings for different materials

[0052]

[0053] As can be seen from Table 1 above, for raw material powder, the temperature can be 40°C, 50°C, 60°C, 80°C, 100°C, etc., and the duration can be 1h, 1.5h, 2h, 2.5h, 3h, etc. For preforms, the temperature can be 120°C, 150°C, 180°C, 200°C, etc., and the duration can be 2 to 4h, such as 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0054] During the pretreatment process, terahertz waves induce molecular synchronous resonance in the materials inside the cabin, thereby changing its microstructure, enhancing its thermal conductivity, improving product density, and improving product strength and other mechanical properties.

[0055] Example 2 Refractory Slide Plate Test

[0056] 1. Test product

[0057] Refractory skateboards (skateboard bricks), such as Figure 3 shown.

[0058] 2. Test methods

[0059] A skateboard brick was selected, starting from blank making (skateboard wet blank preform), through drying at 200 degrees and firing at 730 degrees, and the strength changes of the bricks before and after terahertz wave pretreatment were studied. The pretreatment temperature here was 180°C and the treatment time was 2h.

[0060] Table 2 Unenhanced treatment (without terahertz wave pretreatment)

[0061] Sample No. Skateboard original condition Program Content 1 After drying at 200℃ out of kiln Perform normal temperature index test 2 After drying at 200℃ out of kiln After firing in a medium temperature kiln, the indexes are tested 3 Wet blank forming Perform normal temperature index test 4 Wet blank forming After drying in the drying kiln, do the normal temperature index test 2 Wet blank forming After drying and firing, do index test

[0062] Table 3 Strengthening treatment (after terahertz wave pretreatment)

[0063]

[0064] Referring to Tables 2 and 3 above, the test process is as follows:

[0065] (1) The workshop pressed Ruifeng 350 skateboard bricks, material b8-1 / SFB-3, brick batch number: 38LC48, clay batch number 38LC14, black material 1.8 kg, white material 4.68 kg.

[0066] (2) Take 6 wet blanks and 6 blanks taken out of kiln No. 6 after drying at 200 degrees. Perform terahertz wave pretreatment and strengthening test on 4 of each type. The remaining 4 blanks are reserved for comparison and testing.

[0067] (3) After the sample bricks are pre-treated by terahertz waves, the subsequent process is carried out. The slides No. 4, 8, and 9 are placed on the No. 110 vertical and horizontal slide car and put into the kiln for drying at 200 degrees, and then taken out of the kiln; the bricks No. 2, 6 (two pieces), and 9 are placed on the medium-temperature kiln car and fired at 730 degrees; after firing is completed, the bricks are cut and sampled for testing.

[0068] 3. Test results

[0069] The test results are shown in Table 4 below:

[0070] Table 4 Test results

[0071]

[0072]

[0073] From the above Table 4, we can see that:

[0074] (1) Scheme A: The skateboard sample was dried at 200°C and then pretreated with terahertz waves, and the strength did not change much.

[0075] (2) Solution B: The skateboard sample was dried at 200 degrees and then pre-treated with terahertz waves, and then fired at 730 degrees. The strength was improved by about 5-10%.

[0076] (3) Scheme C: The strength of the wet skateboard sample does not change whether it is pretreated by terahertz wave or not.

[0077] (4) Scheme D: The wet skateboard sample is pretreated with terahertz waves and then dried at 200 degrees, which increases the strength by about 10%.

[0078] (5) Scheme E: The wet skateboard sample was pretreated with terahertz waves, dried at 200 degrees, and then fired at 730 degrees. The strength was increased by 15-17%, and the pretreatment effect was obvious.

[0079] 4. Test conclusion

[0080] From the above results, it can be seen that terahertz wave pretreatment has little effect on improving the strength of low-temperature treated skateboards. Terahertz wave pretreatment has a significant effect on improving the strength of skateboards after high-temperature firing, with an increase of 15-17%; among them, pretreatment of wet embryos before drying has a more obvious strength improvement than pretreatment after drying.

[0081] It should be noted that the above embodiments are described by taking the prefabricated parts as an example. In actual use, the raw material powder may also be pretreated to promote sintering densification.

[0082] Example 3 Tile Test

[0083] 1. Test product

[0084] 800mm×800mm floor tiles

[0085] 2. Test methods

[0086] Part of the raw materials for tiles (5%) are pretreated with terahertz waves at a temperature of 100°C for 2 hours, and then the thickness of the bricks is reduced to 8mm (usually the thickness of 800mm×800mm floor tiles is not less than 10.5mm, otherwise its breaking strength and other indicators cannot meet the national standard requirements), and then high-temperature sintering is carried out using the same process.

[0087] 3. Test results

[0088] The 800mm×800mm×8mm ceramic tiles pretreated with terahertz waves have indicators such as destructive strength that are equivalent to or better than those of the 10.5mm thick ceramic tiles produced by Zhongsheng Ceramics.

[0089] At the same time, a comparison product is provided. After technological innovation, Dongpeng Ceramics has reduced the thickness of 800mm×800mm tiles to 9mm, but many indicators are far from the aforementioned 8mm tiles.

[0090] Table 5 Comparison of main index data of three types of tiles

[0091]

[0092] 4. Test conclusion

[0093] Terahertz wave pretreatment technology has significantly improved the destructive strength of tiles and other properties. At the same time, it can directly reduce the thickness of 800mmX800mm tiles to 8mm. This can not only save more than 20% of raw materials, reduce some calcination energy consumption, but also save transportation costs. It has considerable economic benefits and great environmental significance.

[0094] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Those skilled in the art may make some simple modifications, equivalent changes or modifications using the technical contents disclosed above, which all fall within the protection scope of the present invention.

Claims

1. A method for promoting the densification of sintered products by terahertz wave pretreatment, characterized in that: The sintering is high-temperature sintering. Before the high-temperature sintering, the material used for the high-temperature sintering is pretreated by using terahertz waves to promote the densification of the high-temperature sintered product and improve the strength of the high-temperature sintered product. The material used for high temperature sintering is raw material powder, raw material particles or prefabricated parts.

2. The method for promoting densification of sintered products by terahertz wave pretreatment according to claim 1, characterized in that: The high temperature sintered product is a high temperature sintered product in the field of ceramics, metals or composite materials.

3. The method for promoting densification of sintered products by terahertz wave pretreatment according to claim 1, characterized in that: In the pretreatment, the material for high temperature sintering is treated with terahertz waves having a frequency of 0.1-10 THz and simultaneously subjected to a heating treatment.

4. The method for promoting densification of sintered products by terahertz wave pretreatment according to claim 3, characterized in that: When the material is raw material powder or raw material granules, the treatment temperature is 40-100°C and the treatment time is 1-3h; when the material is a prefabricated part, the treatment temperature is 120-200°C and the treatment time is 2-4h.

5. The method for promoting densification of sintered products by terahertz wave pretreatment according to any one of claims 1 to 4, characterized in that: The high temperature sintered product is a refractory material slide plate; The pretreatment method comprises: subjecting the skateboard wet embryo preform or raw material powder to terahertz wave pretreatment, drying and then high-temperature sintering after the pretreatment; or subjecting the skateboard wet embryo preform to terahertz wave pretreatment after drying and then high-temperature sintering.

6. The method for promoting densification of sintered products by using terahertz wave pretreatment according to claim 5, characterized in that: The drying is performed at 200° C., and the high temperature sintering is performed at 730° C.

7. The method for promoting densification of sintered products by terahertz wave pretreatment according to any one of claims 1 to 4, characterized in that: The high temperature sintered product is a ceramic tile; The pretreatment method is to pretreat part or all of the raw material powder of the ceramic tile with terahertz waves and then perform high-temperature sintering, which can promote product densification, improve product strength and reduce product thickness at the same time.

8. The method for promoting densification of sintered products by terahertz wave pretreatment according to claim 7, characterized in that: The part of raw material powder is raw material powder with a mass percentage of 3-10%.

9. A sintered product pretreated by terahertz waves, characterized in that: The sintered product is processed by the method of promoting the densification of the sintered product by terahertz wave pretreatment as described in any one of claims 1 to 8.

10. A device for promoting densification of sintered products by terahertz wave pretreatment, characterized in that: The device is a pretreatment device used in the method for promoting densification of sintered products by terahertz wave pretreatment as described in any one of claims 1 to 8; The pre-processing device comprises: Device body; A terahertz energy chamber disposed in the main body of the device; A terahertz wave generator connected to the terahertz energy chamber to provide an energy source for the terahertz energy chamber; It also includes an operation control system for controlling the temperature inside the terahertz energy cabin and the action time of the entire device.

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