Purification pyrolysis device and purification pyrolysis method
By employing a pyrolysis device and a heat self-balancing design, the problems of cumbersome and costly purification processes in traditional silicon-nitrogen-hydrogen powders have been solved, enabling rapid purification and low-cost preparation of high-purity amorphous silicon nitride.
Patent Information
- Application Number
- CN202511374884.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-24
- Publication Date
- 2026-01-02
AI Technical Summary
Traditional silicon-nitrogen-hydrogen powder purification processes are cumbersome and consume large amounts of liquid ammonia, resulting in high preparation costs.
A purification pyrolysis device, including a heat trap, a transition trap, and a cold trap, is used. Heating is achieved through a heating jacket and cooling is achieved through a cooling jacket. A heat self-balancing method is designed to decompose and purify silicon nitrogen hydrogen powder and ammonium chloride powder. The self-reducing properties of ammonia and hydrogen chloride are used to inhibit the oxidation of intermediate products and reduce the formation of by-products.
Rapid purification of high-purity amorphous silicon nitride was achieved, with high batch stability and reduced preparation costs.
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Figure CN121244092A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of silicon-nitrogen-hydrogen powder purification technology, and in particular to a purification pyrolysis apparatus and purification pyrolysis method. Background Technology
[0002] Crystalline nitride powders can be obtained by crystallizing amorphous nitride powders. The purity, stability, and production process of amorphous nitrides determine the high purity and low cost of crystalline nitride powders. The pyrolysis of silicon-nitrogen-hydrogen (SiN-H) powders to prepare amorphous nitrides possesses the intrinsic characteristics of high purity and stability. SiN-H powders contain ammonium chloride impurities. Traditional purification of SiN-H powders is achieved through ammonia washing, requiring a large amount of liquid ammonia to dissolve the ammonium chloride powder, thereby filtering out the SiN-H powder. The filtered SiN-H powder then needs further drying to obtain the SiN-H powder suitable for pyrolysis to prepare amorphous silicon nitride. Therefore, the above process is cumbersome and consumes a large amount of liquid ammonia, making the preparation cost of SiN-H powders too high. Summary of the Invention
[0003] This disclosure provides a purification pyrolysis apparatus and a purification pyrolysis method to at least solve one of the technical problems existing in the prior art.
[0004] In a first aspect, this application provides a purification pyrolysis apparatus, comprising:
[0005] A heat trap includes a heat trap body and a heating jacket. The heat trap body has a first chamber inside and is provided with an air inlet, a feed inlet and a first air outlet that communicate with the first chamber. The heating jacket is fitted over the outside of the heat trap body and is used to heat the heat trap body.
[0006] The transition trap has a through second chamber inside, and the first end of the second chamber is sealed and connected to the first air outlet.
[0007] A cold trap includes a cold trap body and a cooling jacket. The cold trap body has a third chamber inside, which is sealed and connected to the second end of the second chamber. The cooling jacket is fitted over the outside of the cold trap body and is used to cool the cold trap body.
[0008] In one possible embodiment, it further includes: a first temperature-measuring blind tube, which is sealed to the heat trap body, and a first end of the first temperature-measuring blind tube extends into the first chamber and a second end protrudes from the first chamber;
[0009] The second temperature measuring blind tube is sealed to the transition trap, and the first end of the second temperature measuring blind tube extends into the second chamber and the second end protrudes from the second chamber;
[0010] The third temperature measuring blind tube is sealed to the cold trap body, and the first end of the third temperature measuring blind tube extends into the third chamber and the second end protrudes from the third chamber;
[0011] Multiple thermocouples are provided and are respectively inserted into the first temperature measuring blind tube, the second temperature measuring blind tube, and the third temperature measuring blind tube.
[0012] In one embodiment, the first end of the second temperature-measuring blind tube and the first end of the third temperature-measuring blind tube are on the same plane.
[0013] In one possible implementation, the length of the first temperature-measuring blind tube extending into the first chamber is 0.5 to 0.75Hh, based on the height Hh of the heat trap body.
[0014] Based on the height Hc of the cold trap body, the length of the third temperature measuring blind tube extending into the third chamber is 0.1 to 0.3Hc.
[0015] In one possible embodiment, it further includes: a second air outlet, the first end of which is in sealed communication with the third chamber;
[0016] The discharge port has a first end that is sealed and connected to the third chamber.
[0017] In one embodiment, the heating jacket is heated by direct current, and the cooling jacket is cooled by a water bath.
[0018] Secondly, this application provides a purification pyrolysis method, using a purification pyrolysis apparatus described in one embodiment above, for purifying and pyrolyzing a mixed powder containing ammonium chloride powder and silicon nitrogen-hydrogen powder; the method includes:
[0019] The first chamber, second chamber, and third chamber are evacuated to 10°C through the air inlet. -5 ~10 -2 Pa, introduce 4N~7N high-purity nitrogen gas, then evacuate to 10. -5 ~10 -2 Pa, after repeating the operation multiple times, a protective atmosphere is introduced;
[0020] A mixture of ammonium chloride powder and silicon nitrogen-hydrogen powder is fed into the first chamber through the feed inlet;
[0021] The heating jacket is heated to 450-650°C at a rate of 20-25°C / min and held for 0-120 min, and then heated to 850-1080°C at a rate of 20-25°C / min and held for at least 180 min.
[0022] The cooling jacket is set to room temperature so that the ammonium chloride powder and silicon nitrogen hydrogen powder in the mixed powder decompose in the first chamber, thereby obtaining amorphous silicon nitride in the first chamber and ammonium chloride powder in the third chamber.
[0023] In one embodiment, the protective atmosphere is one of ammonia, nitrogen, argon, an argon-ammonia mixture, a nitrogen-hydrogen mixture, or an argon-hydrogen mixture.
[0024] In one embodiment, the volume percentage of ammonium chloride powder in the mixed powder is 20-90%, and the volume percentage of silicon nitrogen-hydrogen powder is 10-80%.
[0025] The ammonium chloride powder has a particle size of 10–100 nanometers, and the silicon nitrogen-hydrogen powder has a particle size of 5–150 nanometers.
[0026] Compared with the prior art, the advantages of this application are as follows: This application provides a purification pyrolysis apparatus, including a hot trap, a transition trap, and a cold trap. The hot trap has a heating jacket, which can heat the hot trap body. The cold trap body is cooled by a cooling jacket. Using the purification pyrolysis apparatus of this application, mixed powders containing silicon-nitrogen-hydrogen powder and ammonium chloride powder can be purified and depyrolyzed. High-purity amorphous silicon nitride is obtained in the first chamber of the hot trap, and high-purity ammonium chloride is obtained in the third chamber of the cold trap.
[0027] This application describes a purification pyrolysis apparatus capable of rapidly purifying and pyrolyzing mixed powders containing silicon-nitrogen-hydrogen powder and ammonium chloride powder. Employing a heat self-balancing design, the ammonium chloride powder in the heat trap decomposes into ammonia and hydrogen chloride. The ammonia and hydrogen chloride then enter the cold trap through the first outlet and transition trap, subsequently synthesizing ammonium chloride within the cold trap body, thus completing the rapid purification of the silicon-nitrogen-hydrogen powder. Furthermore, the silicon-nitrogen-hydrogen powder in the heat trap is further pyrolyzed into ammonia and amorphous silicon nitride. The ammonia-rich environment, with its self-reducing properties, inhibits the oxidation or disproportionation of intermediate products during the pyrolysis process of the silicon-nitrogen-hydrogen powder, reducing the formation of byproducts and ultimately purifying the powder to obtain amorphous silicon nitride. By controlling the entire system to a slightly positive pressure state through heat self-balancing, this apparatus achieves high purity, high batch stability, and low production cost for the rapid purification and pyrolysis of silicon-nitrogen-hydrogen powder to obtain amorphous silicon nitride powder.
[0028] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description
[0029] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:
[0030] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.
[0031] Figure 1 A schematic diagram of the purification pyrolysis apparatus according to an embodiment of the present disclosure is shown;
[0032] Figure 2 An electron micrograph of amorphous silicon nitride powder obtained according to an embodiment of this disclosure is shown.
[0033] Reference numerals: 1-Heat trap, 2-First sealing gasket, 3-First temperature measuring blind tube, 4-Inlet, 5-Second temperature measuring blind tube, 6-Air inlet, 7-Third temperature measuring blind tube, 8-Second air outlet, 9-Outlet, 10-Transition trap, 11-Cold trap, 12-Second sealing gasket, 13-Heating jacket, 14-Cooling jacket, 15-First chamber, 16-First air outlet, 17-Second chamber, 18-Third chamber, 19-Heat trap body, 20-Cold trap body. Detailed Implementation
[0034] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.
[0035] Firstly, such as Figure 1 As shown, this application provides a purification pyrolysis apparatus, comprising:
[0036] The heat trap 1 includes a heat trap body 19 and a heating sleeve 13. The heat trap body 19 has a first chamber 15 inside. The heat trap body is provided with an air inlet 6, a feed inlet 4 and a first air outlet 16 that are connected to the first chamber 15. The heating sleeve 13 is sleeved on the outside of the heat trap body 19 and is used to heat the heat trap body 19.
[0037] The transition trap 10 has a through second chamber 17 inside, and the first end of the second chamber 17 is sealed and connected to the first air outlet 16.
[0038] The cold trap 11 includes a cold trap body 20 and a cooling sleeve 14. The cold trap body 20 has a third chamber 18 inside, which is sealed and connected to the second end of the second chamber 17. The cooling sleeve 14 is sleeved on the outside of the cold trap body 20 for cooling the cold trap body 20.
[0039] For example, such as Figure 1 As shown, the centerline of the heat trap body 19 is perpendicular to the centerline of the transition trap 10, the centerline of the transition trap 10 is perpendicular to the centerline of the cold trap body 20, and the centerline of the heat trap body 19 is parallel to the centerline of the cold trap body 20.
[0040] For example, the material of the heat trap body 19 includes, but is not limited to, stainless steel, Hasbro alloy, and quartz glass.
[0041] For example, the heat trap body 19 has a cylindrical structure, with a diameter Dh of 80-160 mm and a height Hh of 140-250 mm; the thickness of the heat trap body 19 is 5-15 mm.
[0042] The heating jacket 13 uses DC electric heating, and the temperature setting range of the heating jacket 13 is 200 to 1100℃, and the heating rate setting range is 10 to 30℃ / min.
[0043] For example, the inner diameter of the feed inlet 4 is 25-38 mm; the diameter of the air inlet 6 is 4-8 mm and the length is 300-800 mm.
[0044] For example, the material of the transition trap 10 includes, but is not limited to, stainless steel, Hasbro alloy, and quartz glass.
[0045] The transition trap 10 has a cylindrical structure with a diameter Dm of 60–120 mm and a height Hm of 100–220 mm.
[0046] For example, the cold trap body 20 may be made of materials including but not limited to stainless steel, Hastelloy, and quartz glass. The cold trap body 20 has a cylindrical structure and a wall thickness of 5–15 mm. The diameter Dc of the cold trap body 20 is 40–120 mm, and the height Hc is 280–750 mm.
[0047] Cooling jacket 14 is cooled by water bath.
[0048] For example, such as Figure 1 As shown, the connection position between the transition trap 10 and the first air outlet 16 of the heat trap body 19 is located near the top of the heat trap body 19.
[0049] This application provides a purification pyrolysis apparatus, including a heat trap 1, a transition trap 10, and a cold trap 11. The heat trap 1 has a heating jacket 13, which can heat its body 19. The cold trap body 20 of the cold trap 11 is cooled by a cooling jacket 14. Using this purification pyrolysis apparatus, a mixed powder containing silicon nitrogen hydrogen powder and ammonium chloride powder can be purified and depyrolyzed. High-purity amorphous silicon nitride is obtained in the first chamber 15 of the heat trap 1, and high-purity ammonium chloride is obtained in the third chamber 18 of the cold trap 11.
[0050] This application discloses a purification pyrolysis apparatus capable of rapidly purifying and pyrolyzing mixed powders containing silicon-nitrogen-hydrogen powder and ammonium chloride powder. Employing a heat self-balancing design, the ammonium chloride powder in heat trap 1 decomposes into ammonia and hydrogen chloride. The ammonia and hydrogen chloride then enter the cold trap 11 through the first outlet 16 and transition trap 10, subsequently synthesizing ammonium chloride within the cold trap body 20, thus completing the rapid purification of the silicon-nitrogen-hydrogen powder. Furthermore, the silicon-nitrogen-hydrogen powder in heat trap 1 is further pyrolyzed into ammonia and amorphous silicon nitride. The ammonia-rich environment, with its self-reducing properties, inhibits the oxidation or disproportionation of intermediate products during the pyrolysis process of the silicon-nitrogen-hydrogen powder, reducing the formation of byproducts and ultimately purifying amorphous silicon nitride. By controlling the entire system to a slightly positive pressure state through heat self-balancing, the apparatus described in this application achieves high purity, high batch stability, and low production cost for the rapid purification and pyrolysis of silicon-nitrogen-hydrogen powder to obtain amorphous silicon nitride powder.
[0051] In one embodiment, the purification pyrolysis apparatus of this application further includes: a first temperature measuring blind tube 3, which is sealed to the heat trap body 19, with a first end of the first temperature measuring blind tube 3 extending into the first chamber 15 and a second end protruding from the first chamber 15;
[0052] The second temperature measuring blind tube 5 is sealed to the transition trap 10. The first end of the second temperature measuring blind tube 5 extends into the second chamber 17 and the second end protrudes from the second chamber 17.
[0053] The third temperature measuring blind tube 7 is sealed to the cold trap body 20. The first end of the third temperature measuring blind tube 7 extends into the third chamber 18 and the second end protrudes from the third chamber 18.
[0054] Multiple thermocouples are provided and are respectively inserted into the first temperature measuring blind tube 3, the second temperature measuring blind tube 5, and the third temperature measuring blind tube 7.
[0055] For example, a thermocouple is inserted into the first temperature-sensing blind tube 3 to test the temperature inside the first chamber 15 of the heat trap 1. Exemplarily, the diameter of the first temperature-sensing blind tube 3 is 3 to 6 mm.
[0056] A thermocouple is inserted into the second temperature-sensing blind tube 5 to test the temperature inside the second chamber 17 of the transition trap 1. For example, the diameter of the second temperature-sensing blind tube 5 is 3–6 mm.
[0057] A thermocouple is inserted into the third temperature-measuring blind tube 7 to test the temperature inside the third chamber 18 of the cold trap 11. The diameter of the third temperature-measuring blind tube 7 is 3-6 mm.
[0058] For example, thermocouples include, but are not limited to, type K, type N, type S and type R.
[0059] For example, the heat trap body 19 also has a first top cover that is sealed to its first chamber 15. Exemplarily, the first top cover and the first chamber 15 can be sealed using a first sealing gasket 2. After the reactants in the first chamber 15 of the heat trap 1 have decomposed, the first top cover can be opened to remove the product from the first chamber 15. Exemplarily, the material of the sealing gasket 2 includes, but is not limited to, metal-wound graphite or pure graphite. Alternatively, the first top cover can be left unopened, and the amorphous silicon nitride product in the first chamber 15 can be discharged through the feed port 4 after the reaction is complete.
[0060] The first temperature measuring blind tube 3, the feed inlet 4, and the air inlet 6 are located on the top of the heat trap body 19. For example, the first temperature measuring blind tube 3, the feed inlet 4, and the air inlet 6 may be located on the first upper cover.
[0061] For example, the cold trap body 20 also has a second top cover that is sealed to its third chamber 18. Exemplarily, the second top cover and the third chamber 18 can be sealed together using a second sealing gasket 12. The second sealing gasket 12 includes, but is not limited to, polytetrafluoroethylene and high-temperature silicone rubber.
[0062] In one embodiment, the first ends of the second temperature-sensing blind tube 5 and the third temperature-sensing blind tube 7 are on the same plane. Placing the first ends of the second and third temperature-sensing blind tubes 5 and 7 on the same plane ensures accurate temperature measurement of the transition trap 10 and the cold trap 11 at the same location, thereby facilitating temperature control of the heat trap 1. Figure 1 As shown, the second temperature measuring blind tube 5 is generally located in the middle of the transition trap 10.
[0063] For example, taking the height Hh of the heat trap body 19 as a reference, the length of the first temperature measuring blind tube 3 extending into the first chamber 15 is 0.5 to 0.75 Hh;
[0064] Based on the height Hc of the cold trap body 20, the length of the third temperature measuring blind tube 7 extending into the third chamber 18 is 0.1 to 0.3Hc.
[0065] By setting the first end of the first temperature-measuring blind tube 3 at a distance of 0.5 to 0.75 Hh from the top of the heat trap body 19, the temperature inside the first chamber 15 can be measured more accurately, making it convenient to precisely control the temperature of the first chamber 15.
[0066] In one embodiment, the purification pyrolysis apparatus of this application further includes:
[0067] The second air outlet 8, the first end of the second air outlet 8 is sealed and connected to the third chamber 18;
[0068] The discharge port 9 has its first end sealed and connected to the third chamber 18.
[0069] A second air outlet 8 is provided at the top of the cold trap body 20, and the second air outlet 8 is sealed and connected to the third chamber 18. The second air outlet 8 is used to discharge excess ammonia gas in the third chamber.
[0070] A discharge port 9 is provided at the top of the cold trap body 20. The discharge port 9 is sealed and connected to the third chamber 18 to discharge the ammonium chloride product synthesized in the third chamber of the cold trap.
[0071] For example, the second air outlet 8 is connected to a check valve, the working pressure of which is 0.005–0.5 MPa. The check valve is made of materials including, but not limited to, stainless steel and Hastelloy alloy.
[0072] For example, the second air outlet 8, the discharge outlet 9, and the third temperature measuring blind tube 7 can be located on the top of the cold trap body. Exemplarily, the second air outlet 8, the discharge outlet 9, and the third temperature measuring blind tube 7 can be located on the second upper cover.
[0073] For example, the inner diameter of the discharge port 9 is 25–38 mm. The diameter of the second air outlet 8 is 4–8 mm and the length is 80–300 mm.
[0074] Secondly, this application provides a purification pyrolysis method, using the aforementioned purification pyrolysis apparatus to purify and pyrolyze a mixed powder containing ammonium chloride powder and silicon nitrogen-hydrogen powder; the purification pyrolysis method includes:
[0075] Step 1), evacuate the first chamber 15 of the heat trap 1, the second chamber 17 of the transition trap 10, and the third chamber 18 of the cold trap 11 to 10 through the air inlet 6. -5 ~10 -2 Pa, introduce 4N~7N high-purity nitrogen gas, then evacuate to 10. -5 ~10 -2 Pa;
[0076] Step 2), after repeating step 1) 3 to 5 times, introduce a protective atmosphere to achieve a slight negative pressure;
[0077] Step 3): A mixture of ammonium chloride powder and silicon nitrogen-hydrogen powder is fed into the first chamber 15 through the feed inlet 4;
[0078] Step 4): Heat the heating jacket 13 to 450-650°C at 20-25°C / min, hold for 0-120 min, and then heat to 850-1080°C at 20-25°C / min and hold for at least 180 min.
[0079] The cooling jacket 14 is set to room temperature so that the ammonium chloride powder and silicon nitrogen hydrogen powder in the mixed powder decompose in the first chamber 15, thereby obtaining amorphous silicon nitride in the first chamber 15 and ammonium chloride powder in the third chamber 18.
[0080] In this application, 4N to 7N high-purity nitrogen gas represents 99.99% to 99.99999% high-purity nitrogen gas. "Slight negative pressure" refers to a state in which the pressure in a system or space is slightly lower than the external atmospheric pressure (normal pressure), and the pressure difference is usually very small (generally in the range of -10Pa to -1000Pa).
[0081] In this application, a mixed powder containing ammonium chloride powder and silicon nitrogen hydrogen powder is loaded into the first chamber. When the heating jacket starts to heat the heat trap body to about 337.8°C, the impurity ammonium chloride powder first begins to decompose to produce ammonia and hydrogen chloride. As the temperature further rises to about 600°C, the decomposition of ammonium chloride powder is completed. At this time, silicon nitrogen hydrogen powder begins to decompose in small amounts until it is heated to 850-1080°C. The thermal decomposition of silicon nitrogen hydrogen powder is completed to obtain amorphous silicon nitride. During this period, the ammonia gas generated by the thermal decomposition of silicon nitrogen hydrogen powder makes the first chamber 15 have a self-reducing ammonia-rich environment that inhibits the oxidation or disproportionation of intermediate products in the pyrolysis process of silicon nitrogen hydrogen powder, reduces the formation of by-products, and thus purifies and obtains amorphous silicon nitride.
[0082] This application utilizes the aforementioned purification pyrolysis apparatus to purify and pyrolyze silicon-nitrogen-hydrogen powder containing ammonium chloride powder impurities. The purification of the silicon-nitrogen-hydrogen powder includes ammonium chloride removal and byproduct removal. The silicon-nitrogen-hydrogen powder pyrolysis is a thermal decomposition reaction that occurs between the pyrolysis start temperature and the pyrolysis termination temperature. The byproduct removal and purification utilizes ammonia gas, including but not limited to that generated during the pyrolysis of the silicon-nitrogen-hydrogen powder.
[0083] In this purification pyrolysis method, the reversible phase transition characteristic of ammonium chloride powder (sublimation-condensation) is utilized to achieve physical separation within a single sealed container. The endothermic process of sublimation is provided by an external heat source (such as a heating jacket), while the exothermic process of condensation releases energy that is directly recovered within the sealed device, compensating for the endothermic demand of subsequent silicon-nitrogen-hydrogen powder pyrolysis. Compared to traditional separation methods (such as ammonia washing filtration and carrier gas purging), this application, through the design of a phase transition path and a heat self-balancing design method, achieves self-circulation and efficient utilization of energy within the reaction system, significantly reducing the total energy consumption of the purification process.
[0084] In the purification pyrolysis of the above-mentioned mixed powder using the purification pyrolysis apparatus of this application, after the ammonium chloride in the closed device with the first chamber heat trap body sublimates, the remaining space is filled with its decomposition products (ammonia, hydrogen chloride) and the ammonia released by the subsequent thermal decomposition of silicon-nitrogen-hydrogen powder. The ammonia-rich atmosphere has self-reducing properties, which can effectively inhibit the oxidation or disproportionation of intermediate products (such as SiH2, SiH) in the pyrolysis process of silicon-nitrogen-hydrogen powder, which is beneficial to the direct formation of silicon-nitrogen bonds and may promote the formation of amorphous silicon nitride, reducing the formation of by-products (such as silicon dioxide) and significantly improving the purity of amorphous silicon nitride powder.
[0085] This application completes the two steps of ammonium chloride powder separation and silicon nitrogen hydrogen powder pyrolysis in the same closed device (heat trap body) under continuous heating conditions. The sublimated ammonium chloride gas is condensed and recovered within the system, avoiding the escape of harmful gases such as ammonia and hydrogen chloride from open systems or carrier gas systems. At the same time, it shortens the process flow, reduces equipment requirements, and solves the gas emission pollution problems commonly found in processes containing ammonium salts and ammonia.
[0086] The purification pyrolysis device of this application utilizes a heat self-balancing design method based on establishing and maintaining a specific temperature gradient within a closed device (the heat trap is used for sublimation and pyrolysis, and the cold trap is used for condensation). It precisely controls the positions of the heat source and cold source, and creates and utilizes thermodynamic non-equilibrium conditions (temperature gradient) within a limited space to drive the directional transport and separation of substances, thereby achieving efficient purification of silicon, nitrogen, and hydrogen powders.
[0087] For example, the protective atmosphere is one of 100% ammonia protective gas, 100% nitrogen protective gas, 100% argon protective gas, argon-ammonia mixture, nitrogen-hydrogen mixture, or argon-hydrogen mixture.
[0088] For example, in the mixed powder, the volume percentage of ammonium chloride powder is 20-90%, and the volume percentage of silicon nitrogen hydrogen powder is 10-80%.
[0089] The particle size of ammonium chloride powder is 10–100 nanometers, and the particle size of silicon nitrogen hydrogen powder is 5–150 nanometers.
[0090] The pyrolysis start temperature of silicon-nitrogen-hydrogen powder is 450–650 degrees Celsius, and the pyrolysis termination temperature is 850–1080 degrees Celsius.
[0091] The present application will be further described in detail below with reference to specific embodiments:
[0092] Example 1
[0093] A purification pyrolysis apparatus, comprising:
[0094] The heat trap 1 includes a heat trap body 19 and a heating sleeve 13. The heat trap body 19 has a first chamber 15 inside. The heat trap body 19 is provided with an air inlet 6, a feed inlet 4 and a first air outlet 16 that are connected to the first chamber 15. The heating sleeve 13 is sleeved on the outside of the heat trap body 19 and is used to heat the heat trap body 19.
[0095] The transition trap 10 has a through second chamber 17 inside, and the first end of the second chamber 17 is sealed and connected to the first air outlet 16.
[0096] The cold trap 11 includes a cold trap body 20 and a cooling sleeve 14. The cold trap body 20 has a third chamber 18 inside, which is sealed and connected to the second end of the second chamber 17. The cooling sleeve 14 is sleeved on the outside of the cold trap body 20 for cooling the cold trap body 20.
[0097] The heat trap body 19 is made of stainless steel and has a cylindrical shape. The diameter Dh of the heat trap body 19 is 120mm, the height Hh is 240mm, and the thickness of the heat trap body 19 is 8mm.
[0098] The transition trap 10 has a cylindrical shape, with a diameter Dm of 120 mm and a height Hm of 200 mm. The transition trap 10 is made of stainless steel. The axis of the transition trap 10 is perpendicular to the axis of the heat trap body 19.
[0099] The cold trap body 20 has a cylindrical shape. The diameter Dc of the cold trap body 20 is 110mm, the height Hc is 500mm, the thickness of the cold trap body 20 is 6mm, and the material of the cold trap body is stainless steel.
[0100] The heat trap 1 also includes a first temperature measuring blind tube 3, which is sealed to the heat trap body 19. The first end of the first temperature measuring blind tube 3 extends into the first chamber 15 and the second end protrudes from the first chamber 15. The diameter of the first temperature measuring blind tube 3 is 6 mm and the length extending into the first chamber 15 is 180 mm (0.75 Hh).
[0101] The second temperature measuring blind tube 5 is sealed to the transition trap 10, and the first end of the second temperature measuring blind tube 5 extends into the second chamber 17 and the second end protrudes from the second chamber 17.
[0102] The third temperature measuring blind tube 7 is sealed to the cold trap body 20, and the first end of the third temperature measuring blind tube 7 extends into the third chamber 18, while the second end protrudes from the third chamber 18. The length of the third temperature measuring blind tube 7 extending into the third chamber 18 is 50 mm (0.1 Hc).
[0103] Thermocouples are inserted into the first temperature measuring blind tube 3, the second temperature measuring blind tube 5, and the third temperature measuring blind tube 7, respectively.
[0104] A purification pyrolysis method, using the aforementioned purification pyrolysis apparatus, is used to purify and pyrolyze a mixed powder containing ammonium chloride powder and silicon nitrogen-hydrogen powder; the purification pyrolysis method includes:
[0105] Step 1), evacuate the first chamber 15 of the heat trap 1, the second chamber 17 of the transition trap 10, and the third chamber of the cold trap 11 to a vacuum level of 10 through the air inlet 6. -4 Pa, introduce 6N high-purity nitrogen gas, then evacuate to 10. -4 Pa;
[0106] Step 2), after repeating step 1) 5 times, introduce a protective atmosphere, which is 100% nitrogen protective gas, to achieve a slight negative pressure;
[0107] Step 3): A mixed powder containing ammonium chloride powder and silicon nitrogen hydrogen powder is fed into the first chamber 15 through the feed port 4. The volume of the mixed powder is 1000 ml. In the mixed powder, the volume percentage of ammonium chloride powder is 80% and the volume percentage of silicon nitrogen hydrogen powder is 20%. The particle size of the ammonium chloride powder is 30-60 nanometers and the particle size of the silicon nitrogen hydrogen powder is 50-80 nanometers.
[0108] Step 4): Heat the heating jacket 13 to 600℃ at 20℃ / min, hold for 0min, and then continue to heat to 980℃ at 20℃ / min and hold for 180min.
[0109] Cooling jacket 14 is water-cooled at room temperature; so that ammonium chloride powder and silicon nitrogen hydrogen powder in the mixed powder are decomposed in the first chamber 15, thereby obtaining amorphous silicon nitride in the first chamber 15 and ammonium chloride powder in the third chamber 18;
[0110] Step 5) After the heat trap body 19 is kept warm, cool it down to 100°C and take out the amorphous silicon nitride powder.
[0111] Electron micrograph of the amorphous silicon nitride powder prepared in Example 1 is shown below. Figure 2 As shown, from Figure 2 It can be seen that amorphous silicon nitride powder exhibits a spherical or near-spherical structure, with some differences in particle size.
[0112] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.
[0113] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.
[0114] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.
Claims
1. A purified pyrolysis apparatus, characterized by: It comprises: a hot trap (1) comprising a hot trap body (19) with a first chamber (15) inside, and a heating jacket (13) outside the hot trap body (19) for heating the hot trap body (19); a transition trap (10) with a second chamber (17) inside, the first end of the second chamber (17) being in sealed communication with the first outlet (16) of the hot trap (1); a cold trap (11) comprising a cold trap body (20) with a third chamber (18) inside, the third chamber (18) being in sealed communication with the second end of the second chamber (17), and a cooling jacket (14) outside the cold trap body (20) for cooling the cold trap body (20).
2. A purification pyrolysis apparatus as claimed in claim 1, characterized in that: It further comprises: a first temperature measuring blind pipe (3) in sealed connection with the hot trap body (19), the first end of the first temperature measuring blind pipe (3) extending into the first chamber (15) and the second end of the first temperature measuring blind pipe (3) being exposed to the first chamber (15); a second temperature measuring blind pipe (5) in sealed connection with the transition trap (10), the first end of the second temperature measuring blind pipe (5) extending into the second chamber (17) and the second end of the second temperature measuring blind pipe (5) being exposed to the second chamber (17); a third temperature measuring blind pipe (7) in sealed connection with the cold trap body (20), the first end of the third temperature measuring blind pipe (7) extending into the third chamber (18) and the second end of the third temperature measuring blind pipe (7) being exposed to the third chamber (18); a plurality of thermocouples are provided, respectively inserted into the first temperature measuring blind pipe (3), the second temperature measuring blind pipe (5) and the third temperature measuring blind pipe (7).
3. A purification pyrolysis apparatus as claimed in claim 2, characterized in that: The first end of the second temperature measuring blind pipe (5) and the first end of the third temperature measuring blind pipe (7) are in the same plane.
4. A purification pyrolysis apparatus as claimed in claim 2, wherein: The length of the first temperature measuring blind pipe (3) extending into the first chamber (15) is 0.5-0.75Hh, with the height of the hot trap body (19) being Hh; The length of the third temperature measuring blind pipe (7) extending into the third chamber (18) is 0.1-0.3Hc, with the height of the cold trap body (20) being Hc.
5. A purification pyrolysis apparatus as claimed in claim 1, wherein: It further comprises: a second outlet (8) in sealed communication with the third chamber (18); a discharge outlet (9) in sealed communication with the third chamber (18).
6. A purification pyrolysis apparatus as claimed in claim 1, wherein: The heating jacket (13) is heated by direct current, and the cooling jacket (14) is cooled by water bath.
7. A method for purifying pyrolysis, using the purifying pyrolysis device according to any one of claims 1-6 to purify and pyrolyze mixed powders containing ammonium chloride powders and silazane powders; the method comprises: The first chamber (15), the second chamber (17) and the third chamber (18) are vacuumed through the air inlet (6) to 10 -5 ~ 10 -2 Pa, 4N~7N high-purity nitrogen is introduced, and vacuum is extracted to 10 -5 ~ 10 -2 Pa, after repeating the operation for multiple times, a protective atmosphere is introduced; loading mixed powders containing ammonium chloride powders and silazane powders into the first chamber (15) through the feeding port (4). The heating jacket (13) is heated to 450-650℃ at a rate of 20-25℃ / min, kept for 0-120min, then heated to 850-1080℃ at a rate of 20-25℃ / min, kept for at least 180min; The cooling jacket (14) is kept at room temperature, so that the ammonium chloride powder and the silicon-nitrogen-hydrogen powder in the mixed powder are decomposed in the first chamber (15), thereby obtaining amorphous silicon nitride in the first chamber (15) and ammonium chloride powder in the third chamber (18).
8. The method of claim 7, wherein: The protective atmosphere is one of ammonia, nitrogen, argon, argon-ammonia mixed gas, nitrogen-hydrogen mixed gas, and argon-hydrogen mixed gas.
9. The method of claim 7, wherein: In the mixed powder, the volume percentage of the ammonium chloride powder is 20-90%, and the volume percentage of the silicon-nitrogen-hydrogen powder is 10-80%. The particle size of the ammonium chloride powder is 10-100nm, and the particle size of the silicon-nitrogen-hydrogen powder is 5-150nm.