A debinding system and debinding method for reaction sintered silicon carbide production

Abstract

The present invention relates to a debinding system and a debinding method for reactive sintered silicon carbide production. The debinding system of the present invention is a nitrogen circulation debinding system, comprising: a liquid nitrogen storage tank, a liquid nitrogen gasification device, a nitrogen heating device, a vacuum sintering furnace and a three-way electromagnetic control valve connected in sequence through pipelines, as well as a control unit, a gas recovery tank and a debinding structure, wherein the debinding structure is a pipeline structure arranged in the vacuum sintering furnace. The flow rate and temperature of the nitrogen are controlled by the control unit of the debinding system; a liquid nitrogen gasification device is provided to preheat the liquid nitrogen and nitrogen using the high-calorie debinding waste gas flowing out of the vacuum sintering furnace, thereby reducing the power consumption of the nitrogen heating device; and the waste gas is recovered and reused after treatment. The debinding system and the debinding method of the present invention improve the product qualification rate and the service life of the vacuum sintering furnace on the one hand, and reduce resource waste and environmental pollution and production costs on the other hand.

Description

Technical Field

[0001] The invention relates to the field of silicon carbide ceramic product production, and in particular to a debinding system and a debinding method for reaction-sintered silicon carbide production. Background Art

[0002] Reaction-bonded silicon carbide has high strength, high hardness, high wear resistance, corrosion resistance, good oxidation resistance, thermal shock resistance and other properties. The products are widely used in various industrial kilns, desulfurization equipment and other mechanical equipment as well as ceramics, machinery, metallurgy, new energy, electronics, chemical industry, steel industry and other fields. The reaction atmosphere of reaction-bonded silicon carbide technology usually uses inert gas, such as argon or hydrogen, to avoid oxidizing gas affecting product quality.

[0003] During the high-temperature sintering process of the silicon carbide blank in the vacuum furnace, the glue substances contained in the silicon carbide blank will be gasified to form glue vapor. If this kind of substance is not treated, it will affect the subsequent products, so a debinding device is needed to treat it. However, in actual use, the glue vapor generated during the sintering process is drained away, but there will still be a large amount of glue vapor inside the entire furnace body. When the temperature is lowered, it condenses into liquid and falls into the vacuum furnace, which in turn affects the sintering of silicon carbide. The debinding device plays a vital role in the sintering of silicon carbide materials in the vacuum furnace, which directly affects the qualified rate of sintered silicon carbide products and the service life of the insulation materials in the vacuum furnace.

[0004] The factors that affect the normal operation of the debinding device mainly include debinding speed, water cooling effect, sealing effect and other factors. When the glue vapor is discharged outward, the exhaust volume of the debinding equipment is required to be greater than the sum of the amount of glue vapor generated in the furnace and the amount of protective gas filled into the furnace, otherwise a positive pressure state will be formed in the vacuum furnace, affecting the normal operation of the vacuum furnace; at the same time, the reaction sintering temperature of the vacuum sintering furnace in the working state is 1680-1850℃, and the sintering time is 160-200min. After the reaction sintering is completed, the temperature in the furnace is extremely high. In actual production, debinding should be carried out at the beginning of the cooling process of the vacuum sintering furnace; therefore, the debinding process needs to control the temperature of the debinding gas, the gas flow of the debinding system or equipment, and the pressure in the vacuum sintering furnace. Based on the convenience of nitrogen preparation and low cost, nitrogen is generally used as the debinding gas in production. In current production, the debinding process is mainly manual operation, and the gas flow rate of the debinding process is difficult to control, which makes it difficult to clean the impurities in the vacuum sintering furnace, and the impurities accumulate on the surface of the sintered silicon carbide ceramic products, affecting the qualified rate of silicon carbide ceramic products. In addition, in current production, the gas discharged after debinding is generally not recovered and recycled, and will cause certain air pollution when discharged into the atmosphere. Therefore, the debinding equipment of the vacuum sintering furnace needs to be improved urgently. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a debinding system and a debinding method for the production of reactive sintered silicon carbide. The debinding system and the debinding method are nitrogen circulation debinding, and the flow rate and temperature of the nitrogen are controlled by the control unit of the debinding system; at the same time, a liquid nitrogen gasification device is provided to preheat the liquid nitrogen and nitrogen using the high-calorie debinding waste gas flowing out of the vacuum sintering furnace, thereby reducing the power consumption of the nitrogen heating device; the nitrogen heating device is provided with two heating chambers to better control the temperature of the nitrogen entering the vacuum sintering furnace, thereby reducing the problem of product damage caused by the nitrogen temperature being too low. In addition, the present invention not only reduces resource waste and environmental pollution, but also reduces production costs by recycling waste gas and reusing it after treatment. The debinding system and the debinding method of the present invention, on the one hand, improve the product qualification rate and the service life of the vacuum sintering furnace, and on the other hand, reduce resource waste and environmental pollution, thereby reducing production costs.

[0006] On the one hand, the present invention provides a binder removal system for reactive sintered silicon carbide production, wherein the binder removal system is a nitrogen circulation binder removal system, comprising: a liquid nitrogen storage tank, a liquid nitrogen gasification device, a nitrogen heating device, a vacuum sintering furnace and a three-way electromagnetic control valve connected in sequence through a pipeline, as well as a control unit, a gas recovery tank and a binder removal structure, wherein the binder removal structure is a pipeline structure arranged in the vacuum sintering furnace;

[0007] The outlet of the liquid nitrogen storage tank is communicated with the first inlet of the liquid nitrogen gasification device, the first outlet of the liquid nitrogen gasification device is communicated with the inlet of the nitrogen heating device, the three-way electromagnetic control valve is respectively communicated with the gas outlet of the vacuum sintering furnace, the second inlet of the liquid nitrogen gasification device and the inlet of the gas recovery tank through pipelines, and the second outlet of the liquid nitrogen gasification device is communicated with the inlet of the gas recovery tank;

[0008] The liquid nitrogen gasification device comprises a gasification pipeline and a heat exchange tube, wherein the heat exchange tube is spirally wound around the middle and rear part of the gasification pipeline; the first inlet and the first outlet are respectively the gas inlet and the gas outlet of the gasification pipeline, the second inlet and the second outlet are respectively the gas inlet and the gas outlet of the heat exchange tube, and the second inlet is located at the first outlet side; the inner diameter of the gasification pipeline is D, and the inner diameter of the heat exchange tube is d, D=kd, k=20~30.

[0009] The three-way electromagnetic control valve described in the present invention can adjust the flow of exhaust gas to the heat exchange tube and the gas recovery tank. A heat exchange tube pressure sensor electrically connected to the control unit is arranged at the gas inlet of the heat exchange tube, and the heat exchange tube pressure sensor monitors the gas pressure in the heat exchange tube, so that the gas pressure in the heat exchange tube is controlled within 90~100KPa.

[0010] Furthermore, in the debinding system of the present invention, when the debinding system is performing a debinding process, the internal pressure of the vacuum sintering furnace is 80-100 KPa, and the interior of the vacuum sintering furnace is in a negative pressure state.

[0011] Furthermore, in the binder removal system of the present invention, the binder removal system also includes a liquid nitrogen preparation device, the liquid nitrogen preparation device is arranged between the gas recovery tank and the liquid nitrogen storage tank, and the liquid nitrogen preparation device includes a waste gas treatment structure and a nitrogen liquefaction structure.

[0012] Further, in the debinding system of the present invention, the nitrogen heating device comprises a first heating chamber, a second heating chamber and a vacuum chamber which are connected in sequence, the first heating chamber and the second heating chamber are both insulating chambers, the first heating chamber comprises an A1 inlet, a B1 inlet and an A1 outlet, and the second heating chamber comprises an A2 inlet, an A2 outlet and a B2 outlet;

[0013] The gas inlet of the vacuum chamber is communicated with the B2 outlet, the gas outlet of the vacuum chamber is communicated with the B1 inlet, the A1 inlet is communicated with the inlet of the nitrogen heating device, the A1 outlet is communicated with the A2 inlet, the A2 outlet is communicated with the gas inlet of the vacuum sintering furnace, and a vacuum pump is provided between the gas outlet of the vacuum chamber and the B1 inlet;

[0014] The B1 inlet and the B2 outlet are both provided with control valves;

[0015] The first heating chamber and the second heating chamber are both provided with heaters electrically connected to the control unit and arranged along the longitudinal direction of the insulation chamber, and the heaters are also provided with temperature sensors;

[0016] The nitrogen inlets of the first heating chamber and the second heating chamber are both provided with an inlet pressure sensor, an inlet flow sensor and an inlet control valve electrically connected to the control unit of the debinding system;

[0017] The nitrogen outlets of the first heating chamber and the second heating chamber are both provided with outlet temperature sensors and outlet control valves electrically connected to the control unit of the debinding system.

[0018] Furthermore, in the debinding system of the present invention, the temperature range of the gas outlet of the first heating chamber is 20-45° C., and the indoor pressure of the first heating chamber is 80-100 KPa.

[0019] Furthermore, in the debinding system of the present invention, the gas temperature range of the gas outlet of the second heating chamber is 50-60° C., and the indoor pressure of the second heating chamber is 79-95 KPa.

[0020] Furthermore, in the debinding system of the present invention, the gas inlet of the vacuum sintering furnace is provided with a flow control valve and a pressure sensor, the gas inlet of the debinding structure is connected to the gas inlet of the vacuum sintering furnace, and the debinding structure includes a nitrogen injection pipe arranged on the furnace cover of the vacuum sintering furnace, and the nitrogen injection pipe is evenly provided with injection holes facing the inside of the vacuum sintering furnace.

[0021] Furthermore, in the debinding system of the present invention, the gas flow rate υ at the gas inlet of the vacuum sintering furnace is 90-110 L / min, and the pressure is 0.3-0.8 MPa.

[0022] On the other hand, the present invention provides a debinding method for the production of reaction-sintered silicon carbide, wherein the debinding method adopts the debinding system described above and specifically comprises the following steps:

[0023] Step 1): The dried silicon carbide product blank is loaded into a vacuum sintering furnace to complete the reaction sintering process and enter the debinding stage;

[0024] Step 2): Open the control valve and the three-way electromagnetic control valve between the liquid nitrogen storage tank, the liquid nitrogen gasification device, and the nitrogen heating device through the control unit of the debinding system, so that the liquid nitrogen in the liquid nitrogen storage tank flows into the liquid nitrogen gasification device and the nitrogen heating device in sequence;

[0025] At the same time, turning on the heater of the nitrogen heating device to heat the nitrogen, and adjusting the gas flow rate of each control valve and the heating temperature of the heater according to the preset parameters of the control unit;

[0026] The control valves at the B2 outlets are all in a closed state;

[0027] Step 3): When the gas temperature at the gas outlet of the second heating chamber reaches 50-60°C, open and adjust the flow control valve at the gas inlet of the vacuum sintering furnace to start debinding, and the debinding time is 10-24 hours;

[0028] The waste gas generated by the debinding enters the heat exchange tube for heat transfer and then enters the gas recovery tank, or the waste gas directly enters the gas recovery tank; the liquid nitrogen obtained after the waste gas in the gas recovery tank is processed by the nitrogen making equipment is recovered to the liquid nitrogen storage tank;

[0029] The gas flow rate of the gas inlet of the vacuum sintering furnace is υ=90~110 L / min, and the pressure is 0.3~0.8MPa; the internal pressure of the vacuum sintering furnace is 80~100KPa;

[0030] Step 4): After the debinding is completed, the control valve of the B2 outlet is opened, and then the outlet control valve of the liquid nitrogen storage tank, the flow control valve of the gas inlet of the vacuum sintering furnace and the heater are closed, and the nitrogen in the second heating chamber flows into the vacuum chamber for storage; after the temperature display of the gas outlet of the first heating chamber and the second heating chamber drops to room temperature, the control valve of the B2 outlet is closed.

[0031] Furthermore, in the debinding method of the present invention, in the step 2), the control valve of the B1 inlet is opened, the vacuum pump is turned on to pump the nitrogen in the vacuum chamber into the first heating chamber, and then the vacuum pump and the control valve of the B1 inlet are closed.

[0032] Compared with the prior art, the present invention has the following beneficial technical effects:

[0033] The debinding system and debinding method described in the present invention are nitrogen circulation debinding, and the flow rate and temperature of nitrogen are controlled by the control unit of the debinding system; at the same time, a liquid nitrogen gasification device is provided to preheat the liquid nitrogen and nitrogen using the high-calorie debinding waste gas flowing out of the vacuum sintering furnace, thereby reducing the power consumption of the nitrogen heating device; the nitrogen heating device is provided with two heating chambers, which can better control the temperature of the nitrogen entering the vacuum sintering furnace, thereby reducing the problem of product damage caused by the nitrogen temperature being too low. In addition, the present invention not only reduces resource waste and environmental pollution, but also reduces production costs by recycling waste gas and reusing it after treatment. The debinding system and debinding method of the present invention, on the one hand, improve the product qualification rate and the service life of the vacuum sintering furnace, and on the other hand, reduce resource waste and environmental pollution, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the binder removal system of the present invention;

[0035] Figure 2 It is a schematic diagram of the heat exchange tube and gasification pipeline structure of the present invention;

[0036] Figure 3 It is a structural schematic diagram of the nitrogen heating device of the present invention;

[0037] Wherein: 100, pipe sleeve, 101, gasification pipeline, 102, heat exchange pipe, 103, flow control valve A, 104, flow control valve B;

[0038] 200. First heating chamber, 201. Second heating chamber, 202. Vacuum chamber, 203. Vacuum pump, 204. Temperature sensor, 205. Temperature sensor, 206. Heater, 207. Inlet pressure sensor, 208. Inlet flow sensor. DETAILED DESCRIPTION

[0039] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described in detail with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. If no specific conditions are specified in the specific implementation method, it shall be carried out under normal conditions or conditions recommended by the manufacturer. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described exemplarily below do not represent all embodiments consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the attached claims. The terms used in the present disclosure are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. Specific implementation method 1

[0040] like Figure 1-3 As shown, a debinding system for reactive sintered silicon carbide production of the present invention is a nitrogen circulation debinding system, comprising: a liquid nitrogen storage tank, a liquid nitrogen gasification device, a nitrogen heating device, a vacuum sintering furnace and a three-way electromagnetic control valve, which are sequentially connected through pipelines, as well as a control unit, a gas recovery tank and a debinding structure, wherein the debinding structure is a pipeline structure arranged in the vacuum sintering furnace;

[0041] The outlet of the liquid nitrogen storage tank is communicated with the first inlet of the liquid nitrogen gasification device, the first outlet of the liquid nitrogen gasification device is communicated with the inlet of the nitrogen heating device, the three-way electromagnetic control valve is respectively communicated with the gas outlet of the vacuum sintering furnace, the second inlet of the liquid nitrogen gasification device and the inlet of the gas recovery tank through pipelines, and the second outlet of the liquid nitrogen gasification device is communicated with the inlet of the gas recovery tank;

[0042] The liquid nitrogen gasification device comprises a gasification pipeline 101 and a heat exchange tube 102, wherein the heat exchange tube 102 is spirally wound around the middle and rear part of the gasification pipeline 101; the first inlet and the first outlet are respectively the gas inlet and the gas outlet of the gasification pipeline 101, the second inlet and the second outlet are respectively the gas inlet and the gas outlet of the heat exchange tube 102, and the second inlet is located at the first outlet side; the inner diameter of the gasification pipeline 101 is D, and the inner diameter of the heat exchange tube 102 is d, where D=kd, and k=20-30.

[0043] In some embodiments, a pipe sleeve 100 is disposed outside the gasification pipe 101 and the heat exchange pipe 102 to protect the internal pipes.

[0044] In some embodiments, the three-way electromagnetic control valve can adjust the flow of exhaust gas to the heat exchange tube 102 and the gas recovery tank. A heat exchange tube pressure sensor electrically connected to the control unit is provided at the gas inlet of the heat exchange tube 102, and the heat exchange tube pressure sensor monitors the gas pressure in the heat exchange tube 102, so that the gas pressure in the heat exchange tube 102 is controlled within 90~95KPa.

[0045] In some embodiments, a flow control valve A 103 and a flow control valve B 104 are respectively provided at the gas inlet and outlet of the heat exchange tube 102 .

[0046] In some embodiments, when the debinding system is performing the debinding process, the interior of the vacuum sintering furnace is in a negative pressure state, and the specific pressure is 91~95KPa.

[0047] In some embodiments, the debinding system further comprises a liquid nitrogen preparation device, which is disposed between the gas recovery tank and the liquid nitrogen storage tank, and comprises a waste gas treatment structure and a nitrogen liquefaction structure.

[0048] In some embodiments, the nitrogen heating device comprises a first heating chamber 200, a second heating chamber 201 and a vacuum chamber 202 which are connected in sequence, the first heating chamber 200 and the second heating chamber 201 are both thermal insulation chambers, the first heating chamber 200 comprises an A1 inlet, a B1 inlet and an A1 outlet, and the second heating chamber 201 comprises an A2 inlet, an A2 outlet and a B2 outlet;

[0049] The gas inlet of the vacuum chamber 202 is connected to the B2 outlet, the gas outlet of the vacuum chamber 202 is connected to the B1 inlet, the A1 inlet is connected to the inlet of the nitrogen heating device, the A1 outlet is connected to the A2 inlet, the A2 outlet is connected to the gas inlet of the vacuum sintering furnace, and a vacuum pump 203 is provided between the gas outlet of the vacuum chamber 202 and the B1 inlet;

[0050] The above-mentioned B1 inlet and the above-mentioned B2 outlet are both provided with control valves;

[0051] The first heating chamber 200 and the second heating chamber 201 are both provided with a heater 206 electrically connected to the control unit and arranged along the longitudinal direction of the insulation chamber, and the heater 206 is also provided with a temperature sensor 205;

[0052] The nitrogen inlets of the first heating chamber 200 and the second heating chamber 201 are both provided with an inlet pressure sensor 207, an inlet flow sensor 208 and an inlet control valve electrically connected to the control unit of the debinding system;

[0053] The nitrogen outlets of the first heating chamber 200 and the second heating chamber 201 are both provided with an outlet temperature sensor 204 and an outlet control valve electrically connected to the control unit of the debinding system.

[0054] In some embodiments, the temperature range of the gas outlet of the first heating chamber 200 is 20-45° C., and the indoor pressure of the first heating chamber 200 is 85-98 KPa.

[0055] In some embodiments, the gas temperature at the gas outlet of the second heating chamber 201 is in the range of 50-60° C., and the indoor pressure of the second heating chamber 201 is in the range of 84-95 KPa.

[0056] In some embodiments, the gas inlet of the vacuum sintering furnace is provided with a flow control valve and a pressure sensor, the gas inlet of the debinding structure is connected to the gas inlet of the vacuum sintering furnace, the debinding structure includes a nitrogen injection pipe arranged on the furnace cover of the vacuum sintering furnace, and the nitrogen injection pipe is evenly provided with injection holes facing the inside of the vacuum sintering furnace.

[0057] In some embodiments, the gas flow rate υ at the gas inlet of the vacuum sintering furnace is 91-110 L / min, and the pressure is 0.4-0.8 MPa; the internal pressure of the vacuum sintering furnace is 85-100 KPa.

[0058] The present invention is further described in detail below with reference to specific embodiments. Embodiment 1:

[0059] The present invention provides a debinding method for the production of reaction-sintered silicon carbide, wherein the debinding method adopts the debinding system in the above-mentioned specific embodiment 1, and specifically comprises the following steps:

[0060] Step 1): The dried silicon carbide product blank is loaded into a vacuum sintering furnace to complete the reaction sintering process and enter the debinding stage;

[0061] Step 2): Open the control valves between the liquid nitrogen storage tank, the liquid nitrogen gasification device, and the nitrogen heating device and the three-way electromagnetic control valve through the control unit of the debinding system, so that the liquid nitrogen in the liquid nitrogen storage tank flows into the liquid nitrogen gasification device and the nitrogen heating device in sequence;

[0062] At the same time, the heater 206 of the nitrogen heating device is turned on to heat the nitrogen, and the gas flow rate of each control valve and the heating temperature of the heater 206 are adjusted according to the preset parameters of the control unit;

[0063] The control valves at the B2 outlet are all in the closed state;

[0064] Step 3): When the gas temperature at the gas outlet of the second heating chamber 201 reaches 50-60°C, open and adjust the flow control valve at the gas inlet of the vacuum sintering furnace to start debinding. The debinding time is 11-23 hours;

[0065] The waste gas generated by debinding enters the heat exchange tube 102 for heat transfer and then enters the gas recovery tank. The waste gas in the gas recovery tank is processed by the nitrogen making equipment to obtain liquid nitrogen which is recovered to the liquid nitrogen storage tank.

[0066] The gas flow rate of the gas inlet of the vacuum sintering furnace is υ=95~110 L / min, and the pressure is 0.5~0.8MPa; the internal pressure of the vacuum sintering furnace is 90~95KPa;

[0067] Step 4): After the debinding is completed, open the control valve of the B2 outlet, close the outlet control valve of the liquid nitrogen storage tank, the flow control valve of the gas inlet of the vacuum sintering furnace and the heater 206, and the nitrogen in the second heating chamber 201 flows into the vacuum chamber 202 for storage; after the temperature display of the gas outlet of the first heating chamber 200 and the second heating chamber 201 drops to room temperature, close the control valve of the B2 outlet. Embodiment 2:

[0068] The present invention provides a debinding method for the production of reaction-sintered silicon carbide, wherein the debinding method adopts the debinding system in the above-mentioned specific embodiment 1, and specifically comprises the following steps:

[0069] Step 1): The dried silicon carbide product blank is loaded into a vacuum sintering furnace to complete the reaction sintering process and enter the debinding stage;

[0070] Step 2): Open the control valves between the liquid nitrogen storage tank, the liquid nitrogen gasification device, and the nitrogen heating device and the three-way electromagnetic control valve through the control unit of the debinding system, so that the liquid nitrogen in the liquid nitrogen storage tank flows into the liquid nitrogen gasification device and the nitrogen heating device in sequence;

[0071] At the same time, the heater 206 of the nitrogen heating device is turned on to heat the nitrogen, and the gas flow rate of each control valve and the heating temperature of the heater 206 are adjusted according to the preset parameters of the control unit;

[0072] The control valves at the B2 outlet are all in the closed state;

[0073] Step 3): When the gas temperature at the gas outlet of the second heating chamber 201 reaches 50-60°C, open and adjust the flow control valve at the gas inlet of the vacuum sintering furnace to start debinding, and the debinding time is 12-20 hours;

[0074] The waste gas generated by debonding directly enters the gas recovery tank. The waste gas in the gas recovery tank is treated by the nitrogen making equipment to obtain liquid nitrogen which is recovered into the liquid nitrogen storage tank.

[0075] The gas flow rate of the gas inlet of the vacuum sintering furnace is υ=95~100 L / min, and the pressure is 0.4~0.7MPa; the internal pressure of the vacuum sintering furnace is 88~92KPa;

[0076] Step 4): After the debinding is completed, open the control valve of the B2 outlet, close the outlet control valve of the liquid nitrogen storage tank, the flow control valve of the gas inlet of the vacuum sintering furnace and the heater 206, and the nitrogen in the second heating chamber 201 flows into the vacuum chamber 202 for storage; after the temperature display of the gas outlet of the first heating chamber 200 and the second heating chamber 201 drops to room temperature, close the control valve of the B2 outlet. Embodiment 3:

[0077] The only difference between Example 3 and Example 1 is that in step 2), the control valve of the B1 inlet is opened, the vacuum pump 203 is turned on to pump the nitrogen in the vacuum chamber 202 into the first heating chamber 200, and then the vacuum pump 203 and the control valve of the B1 inlet are closed.

[0078] The present invention is described by the above-mentioned specific implementation methods and embodiments, and it should be understood by those skilled in the art that various changes and equivalent substitutions may be made to the present invention without departing from the scope of the present invention. The parts not described in detail in the present specification are known to those skilled in the art. In addition, various modifications may be made to the present invention for specific situations or specific circumstances without departing from the scope of the present invention. Therefore, the present invention is not limited to the disclosed specific embodiments, but should include all implementation methods falling within the scope of the claims of the present invention.

Claims

1. A debinding method for the production of reaction-sintered silicon carbide, characterized in that: The debinding method adopts a debinding system, and specifically comprises the following steps: Step 1): The dried silicon carbide product blank is loaded into a vacuum sintering furnace to complete the reaction sintering process and enter the debinding stage; Step 2): Open the control valve and the three-way electromagnetic control valve between the liquid nitrogen storage tank, the liquid nitrogen gasification device, and the nitrogen heating device through the control unit of the debinding system, so that the liquid nitrogen in the liquid nitrogen storage tank flows into the liquid nitrogen gasification device and the nitrogen heating device in sequence; At the same time, the heater of the nitrogen heating device is turned on to heat the nitrogen, and the gas flow rate of each control valve and the heating temperature of the heater are adjusted according to the preset parameters of the control unit; the nitrogen heating device comprises a first heating chamber, a second heating chamber and a vacuum chamber which are connected in sequence, the first heating chamber comprises an A1 inlet, a B1 inlet and an A1 outlet, and the second heating chamber comprises an A2 inlet, an A2 outlet and a B2 outlet; The control valves of the B2 outlet of the second heating chamber of the nitrogen heating device are all in a closed state; Step 3): When the gas temperature at the gas outlet of the second heating chamber reaches 50-60°C, open and adjust the flow control valve at the gas inlet of the vacuum sintering furnace to start debinding for 10-24 hours; The waste gas generated by debinding enters the heat exchange tube of the liquid nitrogen gasification device for heat transfer and then enters the gas recovery tank; the waste gas in the gas recovery tank is treated by the nitrogen making equipment to obtain liquid nitrogen which is recovered to the liquid nitrogen storage tank; The gas flow rate of the gas inlet of the vacuum sintering furnace is υ=90~110 L / min, and the pressure is 0.3~0.8MPa; the internal pressure of the vacuum sintering furnace is 80~100KPa; Step 4): After the debinding is completed, the control valve of the B2 outlet of the second heating chamber is opened, and then the outlet control valve of the liquid nitrogen storage tank, the flow control valve of the gas inlet of the vacuum sintering furnace and the heater are closed, and the nitrogen in the second heating chamber flows into the vacuum chamber of the nitrogen heating device for storage; after the temperature display of the gas outlet of the first heating chamber and the second heating chamber of the nitrogen heating device drops to room temperature, the control valve of the B2 outlet is closed.

2. The debinding method according to claim 1, characterized in that: In the step 2), the control valve of the B1 inlet of the first heating chamber is opened, the vacuum pump is turned on to pump the nitrogen in the vacuum chamber into the first heating chamber, and then the vacuum pump and the control valve of the B1 inlet are closed.

3. The debinding method according to claim 2, characterized in that: The debinding system is a nitrogen circulation debinding system, which includes: a liquid nitrogen storage tank, a liquid nitrogen gasification device, a nitrogen heating device, a vacuum sintering furnace and a three-way electromagnetic control valve, which are sequentially connected through pipelines, as well as a control unit, a gas recovery tank and a debinding structure, and the debinding structure is a pipeline structure arranged in the vacuum sintering furnace; The outlet of the liquid nitrogen storage tank is communicated with the first inlet of the liquid nitrogen gasification device, the first outlet of the liquid nitrogen gasification device is communicated with the inlet of the nitrogen heating device, the three-way electromagnetic control valve is respectively communicated with the gas outlet of the vacuum sintering furnace, the second inlet of the liquid nitrogen gasification device and the inlet of the gas recovery tank through pipelines, and the second outlet of the liquid nitrogen gasification device is communicated with the inlet of the gas recovery tank; The liquid nitrogen gasification device comprises a gasification pipeline and a heat exchange tube, wherein the heat exchange tube is spirally wound around the middle and rear part of the gasification pipeline; the first inlet and the first outlet are respectively the gas inlet and the gas outlet of the gasification pipeline, the second inlet and the second outlet are respectively the gas inlet and the gas outlet of the heat exchange tube, and the second inlet is located at the first outlet side; the inner diameter of the gasification pipeline is D, and the inner diameter of the heat exchange tube is d, D=kd, k=20-30; When the debinding system is performing the debinding process, the internal pressure of the vacuum sintering furnace is 80-100 KPa.

4. The debinding method according to claim 3, characterized in that: The debinding system further comprises a liquid nitrogen preparation device, which is arranged between the gas recovery tank and the liquid nitrogen storage tank, and comprises a waste gas treatment structure and a nitrogen liquefaction structure.

5. The debinding method according to claim 4, characterized in that: The first heating chamber and the second heating chamber are both thermal insulation chambers; The gas inlet of the vacuum chamber is communicated with the B2 outlet, the gas outlet of the vacuum chamber is communicated with the B1 inlet, the A1 inlet is communicated with the inlet of the nitrogen heating device, the A1 outlet is communicated with the A2 inlet, the A2 outlet is communicated with the gas inlet of the vacuum sintering furnace, and a vacuum pump is provided between the gas outlet of the vacuum chamber and the B1 inlet; The B1 inlet and the B2 outlet are both provided with control valves; The first heating chamber and the second heating chamber are both provided with heaters electrically connected to the control unit and arranged along the longitudinal direction of the insulation chamber, and the heaters are also provided with temperature sensors; The nitrogen inlets of the first heating chamber and the second heating chamber are both provided with an inlet pressure sensor, an inlet flow sensor and an inlet control valve electrically connected to the control unit of the debinding system; The nitrogen outlets of the first heating chamber and the second heating chamber are both provided with outlet temperature sensors and outlet control valves electrically connected to the control unit of the debinding system.

6. The debinding method according to claim 5, characterized in that: The temperature range of the gas outlet of the first heating chamber is 20-45° C., and the indoor pressure of the first heating chamber is 80-100 KPa.

7. The debinding method according to claim 6, characterized in that: The gas temperature range of the gas outlet of the second heating chamber is 50-60° C., and the indoor pressure of the second heating chamber is 79-95 KPa.

8. The debinding method according to claim 7, characterized in that: The gas inlet of the vacuum sintering furnace is provided with a flow control valve and a pressure sensor, the gas inlet of the debinding structure is connected to the gas inlet of the vacuum sintering furnace, the debinding structure includes a nitrogen injection pipe arranged on the furnace cover of the vacuum sintering furnace, and the nitrogen injection pipe is evenly provided with injection holes facing the inside of the vacuum sintering furnace.

9. The debinding method according to claim 8, characterized in that: The gas flow rate υ at the gas inlet of the vacuum sintering furnace is 90-110 L / min, and the pressure is 0.3-0.8 MPa.

Images