CN116813358B - Forming process of silicon carbide plate and silicon carbide plate prepared by forming process - Google Patents
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 157
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 148
- 238000000034 method Methods 0.000 title claims abstract description 78
- 238000003466 welding Methods 0.000 claims abstract description 94
- 238000009792 diffusion process Methods 0.000 claims abstract description 77
- 238000010438 heat treatment Methods 0.000 claims abstract description 47
- 238000001816 cooling Methods 0.000 claims abstract description 35
- 238000000465 moulding Methods 0.000 claims abstract description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 9
- 238000010791 quenching Methods 0.000 claims description 7
- 230000000171 quenching effect Effects 0.000 claims description 7
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- 238000012545 processing Methods 0.000 abstract description 2
- 238000005245 sintering Methods 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 10
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- 238000005498 polishing Methods 0.000 description 8
- 238000004321 preservation Methods 0.000 description 8
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- 239000003153 chemical reaction reagent Substances 0.000 description 2
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Abstract
The invention relates to the technical field of silicon carbide material processing, in particular to a molding process of a silicon carbide plate and the silicon carbide plate prepared by the molding process, which comprises the following steps of; stacking at least two silicon carbide plastic blank plates in diffusion welding equipment, and sequentially performing pre-pressurizing, heating, boosting, depressurizing and cooling treatment under a vacuum condition; wherein the pre-pressurizing treatment comprises the step of raising the pressure to 0.5-1 MPa; the temperature raising treatment comprises the steps of raising the temperature to 2100-2300 ℃ and keeping the pressure to be 0.5-1 MPa; the pressure boosting treatment comprises the steps of raising the pressure to 10-13 MPa and keeping the temperature at 2100-2300 ℃; the pressure reduction and temperature reduction treatment comprises the steps of reducing the pressure to 6-8 MPa, completing integral diffusion welding, reducing the temperature to 1400-1500 ℃ and reducing the pressure to 0.5-1 MPa. The process flow is simplified, the welding difficulty and the process cost are greatly reduced, and the welding success rate of the silicon carbide plate is remarkably improved.
Description
Technical Field
The invention relates to the technical field of silicon carbide material processing, in particular to a forming process of a silicon carbide plate integrating vacuum sintering and diffusion welding and the silicon carbide plate manufactured by the forming process.
Background
Silicon carbide is a typical semiconductor material, has the characteristics of high temperature resistance, corrosion resistance, high strength, good heat conduction performance and the like, and has been widely applied to the fields of petrochemical industry, aerospace, ships, atomic energy, pharmaceutical chemical industry, heating ventilation equipment, machinery and the like.
In the prior art, the manufacturing process of silicon carbide products generally comprises the following steps: firstly, pressing silicon carbide powder into a biscuit plate, carrying out primary machining and high-temperature sintering on the biscuit plate to obtain a compact silicon carbide plate, and carrying out secondary machining and high-temperature diffusion welding on the silicon carbide plate to finally obtain a silicon carbide product. The process needs two times of furnace feeding and two times of machining, is complex in process, high in cost and high in welding difficulty, and the sintered silicon carbide plate is poor in toughness and easy to crack, and is easy to crack in the diffusion connection process (as shown in figure 1), so that the welding success rate is low, and only about 70%. Therefore, there is a need for optimizing and improving the silicon carbide manufacturing process to improve the process success rate and silicon carbide product performance.
Disclosure of Invention
In view of the above, the invention aims to solve the technical problems that the existing silicon carbide plate has complex manufacturing process, high welding difficulty and low success rate, thereby providing a silicon carbide plate forming process integrating vacuum sintering and diffusion welding.
In order to achieve the above purpose, the invention adopts the following technical scheme:
according to a first aspect of embodiments of the present invention, there is provided a process for forming a silicon carbide board, comprising the steps of;
Stacking at least two silicon carbide blanks in diffusion welding equipment, and sequentially performing pre-pressurizing, heating, boosting, depressurizing and cooling treatment under a vacuum condition; wherein,
The pre-pressurizing treatment comprises the step of increasing the pressure to 0.5-1 MPa;
the temperature raising treatment comprises the steps of raising the temperature to 2100-2300 ℃ and keeping the pressure to be 0.5-1 MPa;
The pressure boosting treatment comprises the steps of raising the pressure to 10-13 MPa and keeping the temperature at 2100-2300 ℃;
The pressure reduction and temperature reduction treatment comprises the steps of reducing the pressure to 6-8 MPa, reducing the pressure to 1400-1500 ℃ and reducing the pressure to 0.5-1 MPa.
In an embodiment of the present invention, the temperature increasing process includes: heating to 300-500 ℃ within 120-150 min, and preserving heat for 120-150 min; heating to 1200-1400 ℃ within 210-300 min, and preserving heat for 150-210 min; heating to 2100-2300 ℃ within 270-360 min, and preserving heat for 150-210 min.
In an embodiment of the present invention, the boosting process includes: boosting the pressure to 4-6 MPa, and maintaining the pressure for 120-150 min; boosting the pressure to 6-8 MPa, and maintaining the pressure for 90-120 min; boosting the pressure to 10-13 MPa and maintaining the pressure for 60-90 min.
In an embodiment of the present invention, the step-down and step-down cooling process includes: maintaining the temperature at 2100-2300 ℃ and reducing the pressure to 6-8 MPa, and maintaining the pressure for 60-90 min; then cooling to 1400-1500 ℃ within 200-300 min, and reducing the pressure to 0.5-1 MPa.
In an embodiment of the invention, the vacuum degree in the diffusion welding device is more than 10 -1 Pa.
In an embodiment of the present invention, the molding process further comprises, prior to stacking the silicon carbide green sheets in the diffusion welding apparatus, subjecting the silicon carbide green sheets to a surface treatment comprising mechanical polishing and alcohol wiping in sequence.
In the embodiment of the invention, an intermediate layer can be optionally placed between the silicon carbide blanks subjected to the surface treatment or not, and then the blanks are stacked in a diffusion welding device, and if the intermediate layer is placed, the intermediate layer is silicon carbide powder; the process of not placing the intermediate layer is simplified, and the prepared silicon carbide plate is stable.
In the embodiment of the invention, the forming process further comprises the step of cooling the prepared silicon carbide plate by adopting a vacuum gas quenching cooling or furnace cooling mode; wherein, the vacuum gas quenching cooling mode has fast cooling speed and high efficiency.
In a second aspect, the invention provides a silicon carbide plate prepared by the process for forming silicon carbide.
In a third aspect, the invention provides a microchannel heat exchanger comprising the silicon carbide plate.
Compared with the prior art, the technical scheme of the invention has the following advantages:
1. The invention provides a silicon carbide board forming process, which comprises the steps of stacking at least two silicon carbide boards in diffusion welding equipment, and sequentially performing pre-pressurizing, heating, pressurizing, depressurizing and cooling treatment; specifically, the pre-pressurizing of the silicon carbide blank plate to 0.5-1 MPa avoids the displacement of the blank plate in the vacuumizing process, the temperature is raised to 2100-2300 ℃ under the pressure, the heating treatment mainly has the effects that the silicon carbide blank plate is sintered at high temperature, the strength of the silicon carbide blank plate is low at first, only small pre-pressurizing can be applied, the silicon carbide blank plate is gradually sintered along with the temperature rise, and the corresponding strength is also increased along with the temperature rise; then preserving heat and boosting the pressure to 10-13 MPa, so that the plates can be subjected to diffusion welding, and the high-temperature sintering is slowly finished along with the extension of the heat preservation time, so that the plate reaches a complete sintering state; and finally, reducing the pressure to 6-8 MPa to finish integral diffusion welding, then reducing the temperature to 1400-1500 ℃ and reducing the pressure to 0.5-1 MPa so as to prevent the silicon carbide plates from breaking at a too high temperature reducing speed, thereby realizing good diffusion welding fusion between the silicon carbide plates. The invention optimizes the traditional twice machining and twice furnace charging silicon carbide plate manufacturing process into one-time machining and one-time furnace charging, simplifies the process flow, greatly reduces the welding difficulty and the process cost, and obviously improves the welding success rate of the silicon carbide plate.
2. The silicon carbide board forming process provided by the invention adopts a step heating mode, specifically, the temperature is raised to 300-500 ℃ within 120-150 min, and the temperature is kept for 120-150 min; heating to 1200-1400 ℃ within 210-300 min, and preserving heat for 150-210 min; heating to 2100-2300 ℃ within 270-360 min, and preserving heat for 150-210 min; after heating, the temperature is kept for a period of time, so that the overlarge temperature difference between the inside and the outside of the silicon carbide plate can be avoided, the discharge of volatile substances in the silicon carbide sintering process is facilitated, the vacuum degree is ensured, and the diffusion welding is facilitated, so that the bending strength, the fracture toughness and the compressive strength of the silicon carbide plate are improved.
3. The silicon carbide board molding process provided by the invention adopts a stepped pressure increasing mode, specifically, the pressure is increased to 4-6 MPa, and the pressure is maintained for 120-150 min; boosting the pressure to 6-8 MPa, and maintaining the pressure for 90-120 min; boosting to 10-13 MPa, and maintaining the pressure for 60-90 min; the method is favorable for carrying out diffusion welding, improves the welding success rate, and limits the pressure maintaining period when the pressure is increased once in the boosting process, so that the problems of low welding success rate and poor compressive strength of the manufactured product caused by too high boosting rate can be avoided. In addition, compared with constant-speed boosting, the step boosting mode has no difference in bending strength, fracture toughness and compressive strength, but is more beneficial to engineering of the process in the later period.
4. The molding process of the silicon carbide plate provided by the invention reduces the pressure to 6-8 MPa by adopting the temperature of 2100-2300 ℃ and maintains the pressure for 60-90 min; and then cooling to 1400-1500 ℃ within 200-300 min, and reducing the temperature to 0.5-1 MPa, so that the silicon carbide plates are prevented from being broken due to the excessively high cooling speed, and good diffusion welding fusion among the silicon carbide plates is realized.
5. According to the forming process of the silicon carbide board, the vacuum degree is controlled to be more than or equal to 10 -1 Pa, so that the silicon carbide can be prevented from being oxidized by heating in a vacuum state, and the welding effect is affected.
6. According to the molding process of the silicon carbide plate, the surface treatment is carried out on the silicon carbide blank plate, and the surface treatment sequentially comprises mechanical polishing and alcohol wiping so as to remove surface layers, greasy dirt and other impurities and avoid adverse effects on the welding effect.
7. The silicon carbide plate provided by the invention has high welding strength and toughness, the bearing pressure of the product with the same structure can be increased by 10-20%, the fracture phenomenon can not occur in the welding process, and the welding success rate is improved to 95%.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a sample graph of the fracture of a silicon carbide plate during diffusion welding.
Fig. 2 is a schematic diagram showing the temperature and pressure changes with time in the molding process of the silicon carbide board provided in examples 1 to 5 of the present invention.
FIG. 3 is the destructive testing result of the silicon carbide board prepared in example 1 of the present invention.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
The inventive concept of the present invention is as follows:
The prior art discovers that the welding difficulty is high, the sintered silicon carbide plate has poor toughness and is easy to crack, and the cracking phenomenon is easy to occur in the diffusion connection process; specifically, pre-pressurizing, heating, boosting, depressurizing and cooling are sequentially carried out; specifically, as shown in fig. 2, the pre-pressurizing of the silicon carbide blank plate to 0.5-1 MPa, the displacement of the blank plate in the vacuumizing process is avoided, the temperature is raised to 2100-2300 ℃ under the pressure, the heating treatment mainly has the effects of sintering the silicon carbide blank plate at high temperature, the strength of the silicon carbide blank plate is low at first, only small pre-pressurizing can be applied, the silicon carbide blank plate is gradually sintered along with the rise of the temperature, and the corresponding strength is also increased along with the rise of the temperature; then preserving heat and boosting the pressure to 10-13 MPa, so that the plates can be subjected to diffusion welding, and the high-temperature sintering is slowly finished along with the extension of the heat preservation time, so that the plate reaches a complete sintering state; and finally, reducing the pressure to 6-8 MPa, keeping the temperature at 2100-2300 ℃ in the process to finish integral diffusion welding, reducing the temperature to 1400-1500 ℃ and reducing the pressure to 0.5-1 MPa so as to prevent the silicon carbide plates from breaking at a too high temperature reducing speed, and thus, realizing good diffusion welding fusion among the silicon carbide plates. The invention optimizes the traditional twice machining and twice furnace charging silicon carbide plate manufacturing process into one-time machining and one-time furnace charging, simplifies the process flow, greatly reduces the welding difficulty and the process cost, and obviously improves the welding success rate of the silicon carbide plate.
Example 1
The molding process of the silicon carbide plate provided by the embodiment comprises the following steps:
(1) Mechanically polishing the silicon carbide blank and wiping and cleaning the silicon carbide blank with alcohol; 100 sets (2 per set) of silicon carbide blanks were stacked according to the configuration of the product to be formed and placed in a diffusion welding furnace. In order to prevent dislocation of the silicon carbide blanks caused by movement of the silicon carbide blanks in the vacuumizing process, the upper pressure head and the lower pressure head of the diffusion welding furnace are utilized to pre-press each group of the silicon carbide blanks to 0.75MPa, and then the diffusion welding furnace is vacuumized until the air pressure in the furnace is 10 -1 Pa.
(2) Sequentially heating, boosting, depressurizing and cooling in a diffusion welding furnace, wherein the vacuum degree is required to be ensured to be less than 10 -1 Pa in the heat preservation process;
The temperature raising treatment includes: firstly, raising the temperature in the diffusion welding furnace from the initial temperature to 400 ℃ within 130min, and preserving heat for 130min; then heating to 1300 ℃ within 230min, and preserving heat for 180min; finally, heating to 2200 ℃ within 290min, and preserving heat for 180min to finish the 95% sintering of the silicon carbide product;
The boosting process includes: the temperature in the furnace is 2200 ℃, the pressure is increased to 5MPa, and the pressure is maintained for 140min; then the pressure is increased to 7MPa, and the pressure is maintained for 110min, so that the sintering state is completely achieved; boosting to 12MPa, and maintaining the pressure for 70min;
The depressurization and cooling treatment comprises the following steps: maintaining the temperature at 2200 ℃ to reduce the pressure to 7MPa, maintaining the pressure for 80min, completing the integral diffusion welding fusion, reducing the temperature to 1450 ℃ in 250min, and reducing the pressure to 0.75MPa; and then the diffusion welding furnace is cooled to the temperature below 100 ℃ by adopting a vacuum gas quenching cooling mode, and the furnace is opened to obtain the silicon carbide plate.
The yield of the silicon carbide plate is 95 percent according to the measurement.
Example 2
The molding process of the silicon carbide plate provided by the embodiment comprises the following steps:
(1) Mechanically polishing the silicon carbide blank and wiping and cleaning the silicon carbide blank with alcohol; 100 sets (2 per set) of silicon carbide blanks were stacked according to the configuration of the product to be formed and placed in a diffusion welding furnace. In order to prevent dislocation of the silicon carbide blanks caused by movement of the silicon carbide blanks in the vacuumizing process, the upper pressure head and the lower pressure head of the diffusion welding furnace are utilized to pre-press each group of the silicon carbide blanks to 0.5MPa, and then the diffusion welding furnace is vacuumized until the air pressure in the furnace is 10 -1 Pa.
(2) Sequentially heating, boosting, depressurizing and cooling in a diffusion welding furnace, wherein the vacuum degree is required to be ensured to be less than 10 -1 Pa in the heat preservation process;
the temperature raising treatment includes: firstly, raising the temperature in the diffusion welding furnace from the initial temperature to 500 ℃ within 120min, and preserving heat for 120min; then heating to 1200 ℃ within 210min, and preserving heat for 210min; finally, heating to 2300 ℃ within 360min, and preserving heat for 150min to finish the 95% sintering of the silicon carbide product;
the boosting process includes: boosting the pressure to 4MPa at the temperature of 2300 ℃ in the furnace, and maintaining the pressure for 150min; then the pressure is increased to 6MPa, and the pressure is maintained for 120min, so that the sintering state is completely achieved; boosting to 13MPa, and maintaining the pressure for 60min;
The depressurization and cooling treatment comprises the following steps: maintaining the temperature at 2300 ℃ to reduce the pressure to 8MPa, maintaining the pressure for 90min, completing the whole diffusion welding fusion, reducing the temperature to 1400 ℃ in 200min, and reducing the pressure to 0.5MPa; and then the diffusion welding furnace is cooled to the temperature below 100 ℃ by adopting a vacuum gas quenching cooling mode, and the furnace is opened to obtain the silicon carbide plate.
The yield of the silicon carbide plate is 95 percent according to the measurement.
Example 3
The molding process of the silicon carbide plate provided by the embodiment comprises the following steps:
(1) Mechanically polishing the silicon carbide blank and wiping and cleaning the silicon carbide blank with alcohol; 100 sets (2 per set) of silicon carbide blanks were stacked according to the configuration of the product to be formed and placed in a diffusion welding furnace. In order to prevent dislocation of the silicon carbide blanks caused by movement of the silicon carbide blanks in the vacuumizing process, the upper pressure head and the lower pressure head of the diffusion welding furnace are utilized to pre-press each group of the silicon carbide blanks to 1MPa, and then the diffusion welding furnace is vacuumized until the air pressure in the furnace is 10 -1 Pa.
(2) Sequentially heating, boosting, depressurizing and cooling in a diffusion welding furnace, wherein the vacuum degree is required to be ensured to be less than 10 -1 Pa in the heat preservation process;
The temperature raising treatment includes: firstly, raising the temperature in the diffusion welding furnace from the initial temperature to 450 ℃ within 140min, and preserving heat for 125min; then heating to 1350 ℃ within 270min, and preserving heat for 200min; finally, heating to 2250 ℃ within 330min, and preserving heat for 200min to finish the 95% sintering of the silicon carbide product;
The boosting process includes: the pressure is increased to 6MPa at 2250deg.C, and the pressure is maintained for 120min; then the pressure is increased to 8MPa, and the pressure is maintained for 90 minutes, so that the sintering state is completely achieved; boosting to 10MPa, and maintaining the pressure for 90min;
the depressurization and cooling treatment comprises the following steps: maintaining the temperature at 2250deg.C, reducing the pressure to 6MPa, maintaining the pressure for 60min, completing the whole diffusion welding fusion, reducing the temperature to 1500 deg.C in 300min, and reducing the pressure to 1MPa; and then the diffusion welding furnace is cooled to a temperature below 100 ℃ by adopting a furnace cooling mode, and the furnace is opened to obtain the silicon carbide plate.
The yield of the silicon carbide plate is 96% through measurement.
Example 4
The molding process of the silicon carbide plate provided by the embodiment comprises the following steps:
(1) Mechanically polishing the silicon carbide blank and wiping and cleaning the silicon carbide blank with alcohol; 100 sets (2 per set) of silicon carbide blanks were stacked according to the configuration of the product to be formed and placed in a diffusion welding furnace. In order to prevent dislocation of the silicon carbide blanks caused by movement of the silicon carbide blanks in the vacuumizing process, the upper pressure head and the lower pressure head of the diffusion welding furnace are utilized to pre-press each group of the silicon carbide blanks to 0.6MPa, and then the diffusion welding furnace is vacuumized until the air pressure in the furnace is 10 -1 Pa.
(2) Sequentially heating, boosting, depressurizing and cooling in a diffusion welding furnace, wherein the vacuum degree is required to be ensured to be less than 10 -1 Pa in the heat preservation process;
the temperature raising treatment includes: firstly, raising the temperature in the diffusion welding furnace from the initial temperature to 300 ℃ within 150min, and preserving heat for 150min; then heating to 1400 ℃ within 300min, and preserving heat for 150min; finally, heating to 2100 ℃ within 270min, and preserving heat for 210min to finish the 95% sintering of the silicon carbide product;
The boosting process includes: the pressure is increased to 5MPa at 2100 ℃ in the furnace, and the pressure is maintained for 130min; then the pressure is increased to 8MPa, and the pressure is maintained for 100min, so that the sintering state is completely achieved; boosting to 11MPa, and maintaining the pressure for 80min;
The depressurization and cooling treatment comprises the following steps: maintaining the temperature at 2100 ℃ and reducing the pressure to 7MPa, maintaining the pressure for 70min, completing the whole diffusion welding fusion, then reducing the temperature to 1450 ℃ in 270min, and reducing the pressure to 0.6MPa; and then the diffusion welding furnace is cooled to a temperature below 100 ℃ by adopting a furnace cooling mode, and the furnace is opened to obtain the silicon carbide plate.
The yield of the silicon carbide plate is 98 percent according to the measurement.
Example 5
The molding process of the silicon carbide plate provided by the embodiment comprises the following steps:
(1) Mechanically polishing the silicon carbide blank and wiping and cleaning the silicon carbide blank with alcohol; and stacking at least two silicon carbide blanks according to the structure of the product to be formed, placing silicon carbide powder at the connecting interface of the silicon carbide blanks, and then placing the silicon carbide powder in a diffusion welding furnace. In order to prevent dislocation of the silicon carbide blanks caused by movement of the silicon carbide blanks in the vacuumizing process, the upper pressure head and the lower pressure head of the diffusion welding furnace are utilized to pre-press each group of the silicon carbide blanks to 0.75MPa, and then the diffusion welding furnace is vacuumized until the air pressure in the furnace is 10 -1 Pa.
(2) Sequentially heating, boosting, depressurizing and cooling in a diffusion welding furnace, wherein the vacuum degree is required to be ensured to be less than 10 -1 Pa in the heat preservation process;
The temperature raising treatment includes: firstly, raising the temperature in the diffusion welding furnace from the initial temperature to 400 ℃ within 130min, and preserving heat for 130min; then heating to 1300 ℃ within 230min, and preserving heat for 180min; finally, heating to 2200 ℃ within 290min, and preserving heat for 180min to finish the 95% sintering of the silicon carbide product;
The boosting process includes: boosting to 5MPa at 2200 ℃ in the furnace, and maintaining the pressure for 140min; then the pressure is increased to 7MPa, and the pressure is maintained for 110min, so that the sintering state is completely achieved; boosting to 12MPa, and maintaining the pressure for 70min;
The depressurization and cooling treatment comprises the following steps: maintaining the temperature at 2200 ℃ to reduce the pressure to 7MPa, maintaining the pressure for 80min, completing the integral diffusion welding fusion, reducing the temperature to 1450 ℃ in 250min, and reducing the pressure to 0.75MPa; and then the diffusion welding furnace is cooled to the temperature below 100 ℃ by adopting a vacuum gas quenching cooling mode, and the furnace is opened to obtain the silicon carbide plate.
The yield of the silicon carbide plate is 90 percent according to the measurement.
Comparative example 1
The molding process of the silicon carbide plate provided by the comparative example comprises the following steps:
(1) Mechanically polishing the silicon carbide blank and wiping and cleaning the silicon carbide blank with alcohol; 100 sets (2 per set) of silicon carbide blanks were stacked according to the configuration of the product to be formed and placed in a diffusion welding furnace. In order to prevent dislocation between the silicon carbide blanks caused by movement of the silicon carbide blanks in the vacuumizing process, the silicon carbide blanks are placed in a diffusion welding furnace, the silicon carbide blanks are pre-pressed to 0.75MPa by an upper pressure head and a lower pressure head of the diffusion welding furnace, and then the diffusion welding furnace is vacuumized until the air pressure in the furnace is 10 -1 Pa.
(2) The molding process is divided into two processes, namely a high-temperature sintering process adopts a conventional method, and a diffusion welding process refers to an embodiment 1 in the specification of a Chinese patent document CN113042879A, namely the specific steps are as follows:
4 sections of gradient heating is carried out in the diffusion welding furnace, and a heat preservation pressurizing section is further arranged between the 4 sections of gradient heating. Firstly, raising the temperature in a diffusion welding furnace from an initial temperature to 500 ℃ at a first heating rate, applying pressure of 5MPa to a silicon carbide part at 500 ℃, and preserving heat for 65min; then the temperature in the diffusion welding furnace is increased to 1100 ℃ at a second heating rate, the pressure of 12MPa is applied to the silicon carbide part at 1100 ℃, and the temperature is kept for 60 minutes; heating the temperature in the diffusion welding furnace to 1500 ℃ at a third heating rate, applying 18MPa pressure to the silicon carbide part at 1760 ℃, and preserving the temperature for 30min; and finally, heating the temperature in the diffusion welding furnace to 2280 ℃ at a fourth heating rate. The first heating rate and the second heating rate are 10 ℃/min, the third heating rate is 16 ℃/min, and the fourth heating rate is 12 ℃/min. And applying pressure of 20MPa to the silicon carbide part at the temperature of 2280 ℃ in the furnace, and keeping the constant temperature and the constant pressure for 50min.
The depressurization and cooling treatment comprises the following steps: maintaining the temperature at 2200 ℃ to reduce the pressure to 7MPa, maintaining the pressure for 80min, reducing the temperature to 1450 ℃ in 250min, and reducing the pressure to 0.75MPa; and then the diffusion welding furnace is cooled to the temperature below 100 ℃ by adopting a vacuum gas quenching cooling mode, and the furnace is opened to obtain the silicon carbide plate.
The yield of the silicon carbide plate is 72 percent according to the measurement.
Comparative example 2
The molding process of the silicon carbide plate provided in this comparative example is basically the same as the process steps of example 1 of the present invention, the only difference being that the temperature raising process is: the temperature was raised to 2200℃at a rate of 1.93℃per minute.
Experimental example
The silicon carbide plates prepared in the above examples and comparative examples were subjected to a compression test, a bending strength test according to GB/T6569, a fracture test according to GB/T38338, and a compression strength test according to GB/T4740, respectively, and the results are shown in Table 1.
Table 1 results of performance testing of silicon carbide products prepared in examples and comparative examples
The silicon carbide products prepared in examples 1 to 5 and comparative examples 1 to2 all pass the pressure test under 3MPa, and the pressure is maintained for 10min without leakage. The silicon carbide products prepared in examples 1 to 5 have bending strength of 450-465 MPa, fracture toughness of 3.8-4.0 MPa/m 1/2 and compressive strength of 3930-3950 MPa, and the bending strength, fracture toughness and compressive strength of comparative examples 1 to2 are all lower, because the bending strength, fracture toughness and compressive strength are larger in the heating process of comparative example 1, certain diffusion connection occurs at non-welding temperature (lower than 2280 ℃), so that the bending strength, fracture toughness and compressive strength are poor after diffusion welding, and the pressure is larger (20 MPa) at welding temperature (2280 ℃), the diffusion welding forging amount is large, and the deformation of welded parts is serious, so that the development of formal products is not facilitated; comparative example 2 increased in temperature at a constant rate, and the silicon carbide was sintered at different temperatures (e.g., 400 c and 1300 c) and the amount of material volatilized was different, and the vacuum degree at different temperatures was slightly high for a short time, which affected the progress of diffusion welding, resulting in poor flexural strength, fracture toughness and compressive strength after diffusion welding.
The silicon carbide product prepared in example 1 was subjected to destructive testing, and the result is shown in fig. 3, which shows that the silicon carbide product prepared by the molding process of the silicon carbide plate provided by the invention has no unwelded area, and has high welding success rate and high compressive strength.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (6)
1. The molding process of the silicon carbide board is characterized by comprising the following steps of;
Stacking at least two silicon carbide blanks in diffusion welding equipment, and sequentially performing pre-pressurizing, heating, boosting, depressurizing and cooling treatment under a vacuum condition; wherein,
The pre-pressurizing treatment comprises the step of increasing the pressure to 0.5-1 MPa;
the temperature raising treatment comprises the steps of raising the temperature to 2100-2300 ℃ and keeping the pressure to be 0.5-1 MPa;
The pressure boosting treatment comprises the steps of raising the pressure to 10-13 MPa and keeping the temperature at 2100-2300 ℃;
the pressure reduction and temperature reduction treatment comprises the steps of reducing the pressure to 6-8 MPa, then reducing the temperature to 1400-1500 ℃ and reducing the pressure to 0.5-1 MPa;
The temperature-increasing treatment includes: heating to 300-500 ℃ within 120-150 min, and preserving heat for 120-150 min; heating to 1200-1400 ℃ within 210-300 min, and preserving heat for 150-210 min; heating to 2100-2300 ℃ within 270-360 min, and preserving heat for 150-210 min;
The boosting process includes: boosting the pressure to 4-6 MPa, and maintaining the pressure for 120-150 min; boosting the pressure to 6-8 MPa, and maintaining the pressure for 90-120 min; boosting to 10-13 MPa, and maintaining the pressure for 60-90 min;
The depressurization and cooling treatment comprises the following steps: maintaining the temperature at 2100-2300 ℃ and reducing the pressure to 6-8 MPa, and maintaining the pressure for 60-90 min; then cooling to 1400-1500 ℃ within 200-300 min, and reducing the pressure to 0.5-1 MPa;
the vacuum degree in the diffusion welding equipment reaches more than 10 -1 Pa.
2. The process of claim 1, further comprising surface treating the silicon carbide blank prior to stacking the silicon carbide blank in the diffusion welding apparatus, the surface treatment comprising mechanical grinding and alcohol wiping in sequence.
3. A process for forming a silicon carbide board as claimed in claim 2, further comprising placing an intermediate layer between the surface treated silicon carbide boards, the intermediate layer being of silicon carbide powder, and then stacking the silicon carbide boards in a diffusion welding apparatus.
4. The process for forming a silicon carbide board according to claim 2, further comprising cooling the silicon carbide board by vacuum gas quenching or furnace cooling.
5. A silicon carbide board prepared by the shaping process of any one of claims 1 to 4.
6. A microchannel heat exchanger comprising the silicon carbide plate of claim 5.
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| CN100358667C (en) * | 2005-11-08 | 2008-01-02 | 西北工业大学 | Instantaneous Liquid Phase Diffusion Welding Method of Carbon/Silicon Carbide Composite Materials |
| CN100361935C (en) * | 2006-05-15 | 2008-01-16 | 西北工业大学 | Bonding method of carbon/carbon or carbon/silicon carbide composite material and heat-resistant alloy |
| CN102557706B (en) * | 2010-12-14 | 2015-03-11 | 鸿富锦精密工业（深圳）有限公司 | Composite part of tin bronze and silicon carbide ceramics and production method thereof |
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