Production equipment and method of silicon nitride and silicon carbide combined product

Abstract

The invention discloses silicon nitride and silicon carbide combined product production equipment which comprises a support, a furnace body is arranged on the support, a silicon molybdenum rod electric heating element is arranged at the top of the furnace body, and the furnace body comprises a middle bidirectional furnace body and two rotary furnace bodies arranged at the two ends of the bidirectional furnace body. A partition plate is arranged in the middle of the two-way furnace body to divide an inner cavity of the two-way furnace body into a first furnace cavity channel and a second furnace cavity channel, an air supply mechanism is arranged in each rotary furnace body, a first air inlet pipe communicated with the first furnace cavity channel is arranged on the side wall of one end of the two-way furnace body, and a second air inlet pipe communicated with the second furnace cavity channel is arranged on the side wall of the other end of the two-way furnace body. An exhaust pipe is arranged at the top of the bidirectional furnace body, feeding pipes are arranged at the bottoms of the first furnace cavity channel and the second furnace cavity channel, and gate valves are arranged on the feeding pipes. The invention further discloses a production method of the silicon nitride and silicon carbide combined product, and the silicon nitride and silicon carbide combined product is prepared through charging sealing, low-temperature nitriding, medium-temperature reaction, high-temperature sintering and cooling discharging in sequence. The system is small in heat loss, low in energy consumption, good in energy-saving effect and high in automation degree.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing silicon nitride bonded silicon carbide products, and particularly to a production device and method for silicon nitride bonded silicon carbide products. Background Art

[0002] Silicon nitride bonded silicon carbide composite refractory material is a new material, which is widely used in various industries such as iron and steel, non-ferrous metals, chemical building materials, etc., and has many advantages such as energy saving, environmental protection, high temperature resistance, corrosion resistance, etc. Its physical properties are mainly as follows: (1) Silicon nitride bonded silicon carbide products have a hard texture, and the Mohs hardness is about 9, belonging to hard materials among non-metallic materials, second only to diamond. (2) Silicon nitride bonded silicon carbide products have high high-temperature strength. At a high temperature of 1200 - 1400 °C, they almost maintain the same strength and hardness as at room temperature for the same period of time. Depending on the use atmosphere, the maximum safe use temperature can reach 1650 - 1750 °C. (3) The thermal expansion coefficient is small, the thermal conductivity is high compared with products such as silicon carbide, it is not easy to generate thermal stress, has good thermal shock stability, and a long service life. It has strong high-temperature creep resistance, corrosion resistance, resistance to extremely cold and hot, oxidation resistance, and is easy to be made into products with high dimensional accuracy and meeting requirements.

[0003] During the sintering process of silicon nitride bonded silicon carbide products, the temperature of the kiln is 0 - 1450 °C. When the kiln temperature reaches above 750 °C, the sealed top cover and sealed door cover of the kiln need to be closed to make the inside of the kiln a closed space. Then, nitrogen with a purity of 99.999% is continuously introduced, and the flow rate is generally 20 - 100 cubic meters per hour (the amount of nitrogen depends on the size and loading capacity of the kiln). The initial function is to displace the air inside the kiln to keep a high-purity nitrogen atmosphere inside the kiln. As the temperature inside the kiln rises, a chemical reaction occurs between the metallic silicon in the product and nitrogen to form silicon nitride bonded silicon carbide finished products. During this period, a large amount of heat will be released, causing the pressure inside the kiln to rise. To ensure the safety of the kiln and the products, the kiln generally has 3 - 6 exhaust ports, equipped with automatic regulating valves, which automatically adjust the opening degree according to the pressure inside the kiln to keep the pressure inside the kiln within a specified range, and the waste gas is directly discharged into the atmosphere through the exhaust valve pipeline.

[0004] Currently, during the sintering process of silicon nitride bonded silicon carbide products, frequent opening of the furnace door during the feeding and discharging process of the sintering furnace causes a large amount of heat loss, high energy consumption, long heating-up time, and manual assistance is required during the process of taking and placing silicon nitride bonded silicon carbide products, resulting in high manual labor intensity. Summary of the Invention

[0005] The present invention provides a production device and method for silicon nitride bonded silicon carbide products, which solves the problems of large heat loss, high energy consumption, long heating-up time, and high manual labor intensity for taking and placing sintered products caused by frequent opening of the furnace door during the feeding and discharging process of traditional silicon nitride bonded silicon carbide product sintering furnaces.

[0006] The present invention provides a production device for silicon nitride bonded silicon carbide products, including a bracket, on which a furnace body is arranged. A silicon molybdenum rod electric heating element is arranged at the top of the furnace body. The furnace body includes a two-way furnace body in the middle and two rotary furnace bodies arranged at both ends of the two-way furnace body. A partition is arranged in the middle of the two-way furnace body to divide the inner cavity of the two-way furnace body into a first furnace cavity channel and a second furnace cavity channel. A air supply mechanism is arranged in each rotary furnace body. A first air inlet pipe communicated with the first furnace cavity channel is arranged on the side wall at one end of the two-way furnace body, and a second air inlet pipe communicated with the second furnace cavity channel is arranged on the side wall at the other end of the two-way furnace body. An exhaust pipe is arranged on the top side wall of the two-way furnace body. Feed inlets are arranged at the bottoms of the first furnace cavity channel and the second furnace cavity channel. Each feed inlet is connected with a feed pipe, and a gate valve is arranged on each feed pipe.

[0007] In the above technical solution, an installation plate fixedly connected with the bracket 1 is arranged below the feed pipe. A plurality of bearing supports are arranged on the installation plate. A lead screw shaft is arranged on each bearing support. A first motor for driving the lead screw shaft to rotate is arranged at the bottom of the installation plate. A nut seat is arranged on each lead screw shaft. A lifting plate is arranged on each nut seat. Two parallel first guide rails are arranged on the lifting plate. Two sliders are arranged on the two first guide rails. A sealing plate is arranged on the two sliders. A fixed block is arranged on the sealing plate. A tray is arranged on the fixed block.

[0008] In the above technical solution, each air supply mechanism includes a second motor, a motor seat, a first pulley, a second pulley, a transmission belt, a pivot shaft and blades. The motor seat is arranged on the top of the rotary furnace body. The second motor is arranged on the motor seat. A first pulley is arranged on the output shaft of the second motor. A second pulley is arranged on one side of the first pulley. The second pulley and the first pulley are connected by a transmission belt in a belt drive manner. A vertical pivot shaft is arranged in the rotary furnace body. A plurality of blades are arranged on the side wall of the pivot shaft along the circumferential direction. The upper and lower ends of the pivot shaft are respectively rotatably connected with the top wall and the bottom wall of the rotary furnace body. The upper end of the pivot shaft is connected with the second pulley.

[0009] In the above technical solution, a guide block is arranged on the side surface of the lifting plate. A guide hole is arranged on the guide block. Two guide shafts fixedly connected with the installation plate are arranged in the guide hole.

[0010] In the above technical solution, two discharge plates are arranged on both sides of the installation plate. Two second guide rails are arranged on each discharge plate.

[0011] In the above technical solution, an annular boss is arranged on the upper surface of the sealing plate, and an annular groove is arranged on the lower end surface of the feed pipe. The annular boss and the annular groove are in vertical socket fit.

[0012] In the above technical solution, a cooling hood is arranged above the unloading plate, an air supply pipe is arranged on the side wall of the cooling hood, two hydraulic cylinders are arranged on both sides of the cooling hood, and the fixed end of each hydraulic cylinder is fixedly connected to the unloading plate, and the telescopic end is fixedly connected to the mounting seat arranged on the side wall of the cooling hood.

[0013] The present invention also provides a method for producing a silicon nitride-bonded silicon carbide product, comprising the following steps: S1. Loading and sealing: stack the pressed silicon nitride combined with silicon carbide products on a pallet, move the lifting plate to the bottom of the feed port by a forklift, open the gate valve of the feed pipe by the controller, drive the first motor to drive the screw shaft to rotate clockwise, so that the nut seat lifts the lifting plate, and the products enter the cavity of the bidirectional furnace through the feed pipe, and stop after the sealing plate seals the feed pipe; S2, low temperature nitriding: the controller starts the silicon molybdenum rod electric heating element to heat the furnace body to 900-1000℃, the heating rate is 6-10℃ / min, 99.999% nitrogen is introduced, and the gas is circulated through the air supply mechanism; S3, medium temperature reaction: continue heating to 1300-1400℃, heating rate 4-5℃ / min, maintain nitrogen pressure 0.1-1MPa, circulate gas until temperature is balanced; S4, high temperature sintering: heating to 1700-1800℃, keeping warm for 1-4 hours, forming liquid phase through sintering aid to promote densification, and circulating gas until the temperature is balanced; S5. Cooling and unloading: The controller drives the first motor to reverse the screw shaft to lower the lifting plate, and the product is moved out of the furnace through the feed pipe. After closing the gate valve, the hydraulic cylinder drives the cooling hood to cover the product, and nitrogen is pumped in to cool it down to below 800°C at a rate of 4-6°C / min. After monitoring by the temperature detector, the cooling hood is removed to obtain the silicon nitride combined with silicon carbide finished product.

[0014] In step (2), the heating rate is 8°C / min, and nitrogen is introduced through the first air inlet pipe and the second air inlet pipe; in step (3), the nitrogen pressure is 0.5 MPa, and the heating rate is 4.5°C / min; in step (4), the sintering aid is a Y2O3-Al2O3 system, and the insulation time is 2 hours; in step (5), the cooling hood is connected to the nitrogen tank through the air supply pipe (40), and the cooling rate is achieved by adjusting the nitrogen flow rate by the controller.

[0015] It can be seen from the above technical solutions that the present invention provides a production device and method for silicon nitride combined with silicon carbide products. Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention prepares silicon nitride-bonded silicon carbide products through charging and sealing, low-temperature nitriding, medium-temperature reaction, high-temperature sintering, and cooling and discharging in sequence, improves the performance indexes of silicon nitride-bonded silicon carbide composite refractory materials, basically realizes automated production, improves the manufacturing level of silicon nitride-bonded silicon carbide composite refractory materials, and reduces various errors caused by subjective human factors. 2. The present invention charges and discharges materials by opening a feed port at the bottom of the furnace body, which can effectively prevent a large amount of hot gas in the furnace body from overflowing during the process of accessing materials. At the same time, by installing a gate valve on the feed pipe of the feed port, the loss of hot gas in the furnace body can be prevented. Compared with the existing sintering furnace, there is no need to cool down the inside of the furnace body, increasing the utilization rate of heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the implementation cases will be briefly introduced below. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0017] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is a top view schematic diagram of the overall structure of the present invention; Figure 3 is an attached Figure 2 A-A line cross-sectional schematic diagram of the present invention; Figure 4 is an attached Figure 3 partial enlarged structure schematic diagram at position Ⅰ of the present invention; Figure 5 is a three-dimensional structure schematic diagram of the present invention; Figure 6 is an attached Figure 3 partial enlarged structure schematic diagram at position Ⅱ of the present invention; Figure 7 is a partial structure schematic diagram of the present invention; Figure 8 is a partial structure cross-sectional schematic diagram of the present invention; Figure 9 is an attached Figure 8 partial enlarged structure schematic diagram at position Ⅲ of the present invention.

[0018] In the figure: 1 - support; 10 - first motor; 11 - mounting plate; 12 - lead screw shaft; 13 - nut seat; 14 - lifting plate; 15 - first guide rail; 16 - slider; 17 - sealing plate; 18 - fixing block; 19 - tray; 111 - discharging plate; 112 - second guide rail; 141 - guide shaft; 171 - annular boss; 2 - Furnace body; 20 - Partition board; 21 - Two-way furnace body; 22 - Rotary furnace body; 23 - First intake pipe; 24 - Second intake pipe; 25 - Exhaust pipe; 26 - Feed inlet; 27 - Feed pipe; 28 - Gate valve; 271 - Annular groove; 3 - Air supply mechanism; 31 - Second motor; 32 - Motor base; 33 - First pulley; 34 - Second pulley; 35 - Transmission belt; 36 - Pivot shaft; 37 - Blade; 361 - First bushing; 362 - Second bushing; 4 - Cooling cover; 40 - Gas supply pipe; 41 - Hydraulic cylinder; 42 - Mounting seat. Detailed implementation manners

[0019] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0020] Embodiment 1: See Figures 1-9A silicon nitride combined with silicon carbide product production equipment includes a bracket 1, the bracket 1 is a three-dimensional steel frame structure, a furnace body 2 is fixedly arranged on the bracket 1, a silicon-molybdenum rod electric heating element is arranged on the top of the furnace body 2, the silicon-molybdenum rod electric heating element is an existing commercially available product, specifically a U-shaped silicon-molybdenum rod element, the U-shaped silicon-molybdenum rod element is electrically connected to the temperature control module of the controller, and after power is turned on, Joule heat is generated by relying on the resistance characteristics of MoSi (the working temperature can reach 1800°C), the furnace body 2 includes a bidirectional furnace body 21 in the middle and two rotary furnace bodies 22 arranged at both ends of the bidirectional furnace body 21, and the bidirectional A partition 20 is arranged in the middle of the furnace body 21 to divide the inner cavity of the two-way furnace body 21 into a first furnace cavity channel and a second furnace cavity channel. An air supply mechanism 3 is arranged in each rotary furnace body 22. The air supply mechanism 3 can drive the gas in the furnace body 2 to flow along the furnace cavity channel of the two-way furnace body 21, so that the temperature of each part inside the furnace body 2 is kept consistent. A first air inlet pipe 23 connected to the first furnace cavity channel is arranged on one end side wall of the two-way furnace body 21, and a second air inlet pipe 24 connected to the second furnace cavity channel is arranged on the other end side wall. The first air inlet pipe 23 and the second air inlet pipe 24 are used to Nitrogen is introduced into the inner cavity of the furnace body 2, an exhaust pipe 25 is arranged on the top side wall of the two-way furnace body 21, and the exhaust pipe 25 is used to balance the air pressure inside the furnace body 2. Feed ports 26 are arranged at the bottom of the first furnace cavity channel and the second furnace cavity channel, and each feed port 26 is connected to a feed pipe 27. A gate valve 28 is arranged on each feed pipe 27, and the gate valve 28 includes a gate plate, a screw, a screw nut seat, and a servo motor. The servo motor is fixed at the bottom of the furnace body 2, and the output shaft of the servo motor is connected to the screw through a coupling. The screw is rotatably installed at the bottom of the gate plate through the screw seat, and the screw nut seat is installed at the screw seat. The servo motor drives its output shaft to rotate forward and reversely to control the gate plate to pass through the guide hole on the side wall of the feed pipe 27 horizontally to extend into the feed pipe 27 to block the feed pipe 27, or to open the passage of the feed pipe 27. By opening a feed port 26 at the bottom of the furnace body 2, a large amount of hot air in the furnace body 2 can be effectively prevented from overflowing during the material storage and retrieval process. At the same time, by installing a gate valve 28 on the feed pipe 27 at the feed port 26, the heat loss in the furnace body 2 can be prevented. Compared with the existing sintering furnace, there is no need to cool down the inside of the furnace body 2, which increases the heat utilization rate.

[0021] For further information, see Figure 3 , 4, 5, 6, an installation plate 11 fixedly connected to the bracket 1 is arranged below the feed pipe 27. A plurality of bearing supports are fixedly arranged on the installation plate 11. A lead screw shaft 12 is rotatably arranged on each bearing support. A first motor 10 for driving the lead screw shaft 12 to rotate is arranged at the bottom of the installation plate 11. The output shaft of the first motor 10 is coaxially and fixedly connected to the lead screw shaft 12. A nut seat 13 that can be in screw pair cooperation with the lead screw shaft 12 is arranged on each lead screw shaft 12. A horizontal lifting plate 14 is fixedly arranged on each nut seat 13. Two parallel first guide rails 15 are fixedly arranged on the lifting plate 14. Two sliders 16 are slidably arranged on the two first guide rails 15. The sliders 16 and the guide rails have a locking structure. A horizontal sealing plate 17 is fixedly arranged on the two sliders 16. A fixing block 18 is fixedly arranged on the sealing plate 17. A tray 19 is fixedly arranged on the fixing block 18 by screws. By driving the lead screw shaft 12 to rotate through the first motor 10, the lifting plate 14, the sealing plate 17, the fixing block 18 and the tray 19 on the nut seat 13 are driven to move up and down vertically.

[0022] Further, refer to Figure 7 , 89. Each air supply mechanism 3 includes a second motor 31, a motor seat 32, a first pulley 33, a second pulley 34, a transmission belt 35, a pivot shaft 36, and a blade 37. The pivot shaft 36 and the blade 37 are made of high-temperature resistant materials. The motor seat 32 is fixedly arranged on the top of the rotary furnace body 22. The second motor 31 is fixedly arranged on the motor seat 32. The first pulley 33 is coaxially fixedly arranged on the output shaft of the second motor 31. The second pulley 34 is arranged on one side of the first pulley 33. The second pulley 34 and the first pulley 33 is connected by a transmission belt 35, a vertical pivot shaft 36 is set in the rotary furnace body 22, a first bearing mounting seat is fixedly set on the top of the rotary furnace body 22, and a second bearing mounting seat is set on the bottom, a first shaft sleeve 361 is rotatably set in the first bearing mounting seat, the upper end of the pivot shaft 36 passes through the top side wall of the rotary furnace body 22 and is sleeved inside the first shaft sleeve 361, and is radially fastened by the top screw in the threaded top screw hole set on the side wall of the first shaft sleeve 361, a second shaft sleeve 362 is rotatably set in the second bearing mounting seat, and the pivot shaft The lower end of the pivot shaft 36 passes through the bottom side wall of the rotary furnace body 22 and is sleeved inside the second shaft sleeve 362, and is fastened radially by the top screw in the threaded top screw hole set on the side wall of the second shaft sleeve 362. A plurality of blades 37 connected to the pivot shaft 36 are fixedly arranged on the side wall of the pivot shaft 36 in the circumferential direction. The upper and lower ends of the pivot shaft 36 are rotatably connected to the top wall and the bottom wall of the rotary furnace body 22 respectively. The upper end of the pivot shaft 36 is connected to the second pulley 34 through the first shaft sleeve 361, and the second pulley 34 is coaxially fixed to the outer wall of the first shaft sleeve 361. The output shaft of the second motor 31 drives the first pulley 33 to rotate, the first pulley 33 drives the second pulley 34 to rotate through the transmission belt 35, the rotation of the second pulley 34 drives the pivot shaft 36 to rotate, the rotation of the pivot shaft 36 drives the blade 37 to rotate, so that the high-temperature gas inside the furnace body 2 flows along its inner cavity, so that the temperature of each part inside the furnace body 2 is kept consistent, so that the silicon nitride combined with silicon carbide product can be sintered at a constant and controllable temperature, the sintering effect is good, and the hardness distribution inside the silicon nitride combined with silicon carbide product is uniform.

[0023] Preferably, see Figure 3 A guide block is fixedly arranged on the side of the lifting plate 14, a guide hole is arranged on the guide block, and two guide shafts 141 fixedly connected to the mounting plate 11 are arranged in the guide hole. The lifting plate 14 can be moved vertically along the guide block through the guide shafts 141, so that the silicon nitride combined with silicon carbide products on the tray 19 can smoothly enter and exit the furnace body 2.

[0024] Preferably, see Figure 1, two discharge plates 111 are fixedly arranged on both sides of the mounting plate 11, and two second guide rails 112 are fixedly arranged on each discharge plate 111. When the pallet 19 needs to be taken out, the lifting plate 14 descends to the lowest position. At this time, the two first guide rails 15 and the corresponding two second guide rails 112 are at the same height on the horizontal plane. The two sliders 16 arranged on the two first guide rails 15 can slide and support the pallet 19 along the two second guide rails 112 and transfer it outside the furnace body 2.

[0025] Preferably, refer to Figure 4 , an annular boss 171 is arranged on the upper surface of the sealing plate 17, and an annular groove 271 is arranged on the lower end surface of the feed pipe 27. The annular boss 171 and the annular groove 271 are in vertical socket fit. During the rising process of the sealing plate 17, the annular boss 171 is inserted into the annular groove 271. After the charging and discharging are completed, the lower end of the feed pipe 27 can be timely sealed by the sealing plate 17 to prevent the hot gas in the furnace body 2 from overflowing, increasing the utilization rate of the heat in the furnace.

[0026] Preferably, refer to Figure 1 , a cooling cover 4 is arranged above the discharge plate 111. An air supply pipe 40 is arranged on the side wall of the cooling cover 4. Two hydraulic cylinders 41 are arranged on both sides of the cooling cover 4. The fixed end of each hydraulic cylinder 41 is fixedly connected to the discharge plate 111, and the telescopic end is fixedly connected to the mounting seat 42 arranged on the side wall of the cooling cover 4. When the silicon nitride bonded silicon carbide product on the pallet 19 is slid and supported along the two second guide rails 112 by the two sliders 16 and transferred to the lower part of the cooling cover 4 outside the furnace body 2, the discharge plate 111 is driven by the two hydraulic cylinders 41 to move downward and completely cover the outside of the silicon nitride bonded silicon carbide product on the pallet 19. The cold air in the nitrogen tank is pumped into the air supply pipe 40 by a pump and introduced into the cooling cover 4 to cool the silicon nitride bonded silicon carbide product in the cooling cover 4. The temperature of the silicon nitride bonded silicon carbide product in the cooling cover 4 is detected by a temperature detector inside the cooling cover 4. After the temperature drops to an appropriate temperature, the cooling cover 4 can be lifted by the two hydraulic cylinders 41 and the nitrogen supply can be stopped.

[0027] In this embodiment, the molybdenum disilicide rod assembly includes a cold end and a hot end. The cold end vertically passes through the top side wall of the furnace body 2 and is electrically connected to an external power supply circuit; the hot end extends into the furnace body 2 and is installed in a suspended structure, reducing heat loss, increasing the heating speed, and saving energy. A heat insulation layer is installed on the inner wall of the furnace body 2. The heat insulation layer uses domestic ceramic fiber board, which has a better heat insulation effect and good heat insulation performance.

[0028] A production method of a silicon nitride bonded silicon carbide product of the present invention includes the following steps: S1. Neatly stack the pressure-molded silicon nitride bonded silicon carbide products on the tray 19. Then, use a forklift to push the lifting plate 14 under the feeding port 26. Control the opening of the gate valve 28 on the feeding pipe 27 through the controller. Then, control the first motor 10 through the controller to drive the lead screw shaft 12 to rotate clockwise, driving the nut seat 13 to rise, so that the nut seat 13 drives the lifting plate 14 to rise. The silicon nitride bonded silicon carbide products on the tray 19 enter the inner cavity of the double-sided furnace body 21 from the feeding pipe 27. Stop rising when the upper surface of the sealing plate 17 fits the lower end surface of the feeding pipe 27 to seal the lower end of the feeding pipe 27; S2. Control the silicon molybdenum rod heating element to heat the inner cavity of the furnace body 2 through the controller, so that the temperature in the furnace body 2 is first raised to 900 - 1000 °C, and the heating rate is controlled at 6 - 10 °C / min to avoid thermal stress cracking. At the same time, introduce 99.999% nitrogen (N) into the inner cavity of the furnace body 2 through the first air inlet pipe 23 and the second air inlet pipe 24, so that the oxygen inside the furnace body 2 is discharged from the exhaust pipe 25. Then, use the air supply mechanism 3 to circulate the gas inside the inner cavity of the furnace body 2, and stop when the temperatures at all places are balanced; S3. Control the silicon molybdenum rod heating element to continue heating and raising the temperature of the inner cavity of the furnace body 2 to 1300 - 1400 °C through the controller, so that the silicon in the silicon nitride bonded silicon carbide products reacts with nitrogen to form silicon nitride and form a bonding phase. At the same time, supplement the nitrogen pressure to 0.1 - 1 MPa, and control the heating to be slow heating (4 - 5 °C / min) to ensure sufficient reaction (3Si + 2N2 → Si3N4). The silicon powder melts: the melting point of silicon is about 1414 °C, but fine powder may soften at a lower temperature. Then, use the air supply mechanism 3 to circulate the gas inside the inner cavity of the furnace body 2, and stop when the temperatures at all places are balanced; S4. Control the silicon molybdenum rod heating element to continue heating the inner cavity of the furnace body 2 through the controller, so that the temperature in the furnace body 2 is raised to 1700 - 1800 °C, promoting the diffusion and bonding of SiN - SiC particles, forming a liquid phase of the sintering aid, and accelerating densification (such as the Y2O3 - A2O3 system). Holding time: 1 - 4 hours. Then, use the air supply mechanism 3 to circulate the gas inside the inner cavity of the furnace body 2, and stop when the temperatures at all places are balanced; S5. Control the first motor 10 through the controller to drive the lead screw shaft 12 to rotate counterclockwise, drive the nut seat 13 to descend, drive the lifting plate 14 to descend through each nut seat 13, so that the silicon nitride bonded silicon carbide product on the tray 19 is removed from the inner cavity of the double-sided furnace body 21 through the feed pipe 27. When the tray 19 is removed from the feed pipe 27, control the gate valve 28 through the controller to close the feed pipe 27, then drive the discharge plate 111 to move downward through two hydraulic cylinders 41 and completely cover the outside of the silicon nitride bonded silicon carbide product on the tray 19. Pump the cold air in the nitrogen gas tank into the gas supply pipe 40 through the pump and introduce it into the cooling cover 4 to cool the silicon nitride bonded silicon carbide product in the cooling cover 4. Detect the temperature of the silicon nitride bonded silicon carbide product through the temperature detector in the cooling cover 4. Continuously supply nitrogen until the temperature is below 800 °C, and the cooling rate is 4 - 6 °C / min. Lift the cooling cover 4 through two hydraulic cylinders 41 and stop supplying nitrogen.

[0029] The silicon nitride bonded silicon carbide composite refractory material produced by the present invention through the above steps: the bulk density ≥ 2.67 g / cm 3 ; the apparent porosity ≤ 13%; the cold crushing strength at room temperature ≥ 160 MPa; the cold bending strength at room temperature ≥ 44 MPa; the hot bending strength (1000 °C) ≥ 46 MPa). The present invention mainly provides an enhanced preparation process technology for silicon nitride bonded silicon carbide composite refractory materials. By applying the present invention, the relevant performance indicators of silicon nitride bonded silicon carbide composite refractory materials can be improved; each process flow in the manufacturing process is basically automated, which can reduce the labor intensity of workers and greatly improve the manufacturing level of silicon nitride bonded silicon carbide composite refractory materials.

[0030] After considering the specification and practicing the invention disclosed herein, those skilled in the art will readily conceive of other embodiments of the present invention. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include the common general knowledge or conventional technical means in the technical field not disclosed in the present invention. The specification and examples are only regarded as exemplary, and the true scope of the present invention is pointed out by the claims.

[0031] It should be understood that the present invention is not limited to the precise structures already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The above-described embodiments of the present invention do not constitute a limitation to the protection scope of the present invention.

Claims

1. A production device for silicon nitride bonded silicon carbide products, comprising a bracket (1), characterized in that: A furnace body (2) is arranged on the bracket (1). A silicon molybdenum rod electric heating element is arranged on the top of the furnace body (2). The furnace body (2) includes a two-way furnace body (21) in the middle and two rotary furnace bodies (22) arranged at both ends of the two-way furnace body (21). A partition plate (20) is arranged in the middle of the two-way furnace body (21) to divide the inner cavity of the two-way furnace body (21) into a first furnace cavity channel and a second furnace cavity channel. A blowing mechanism (3) is arranged in each rotary furnace body (22). A first air inlet pipe (23) communicated with the first furnace cavity channel is arranged on the side wall of one end of the two-way furnace body (21), and a second air inlet pipe (24) communicated with the second furnace cavity channel is arranged on the side wall of the other end. An exhaust pipe (25) is arranged on the top side wall of the two-way furnace body (21). Feed inlets (26) are arranged at the bottoms of the first furnace cavity channel and the second furnace cavity channel. Each feed inlet (26) is connected to a feed pipe (27), and a gate valve (28) is arranged on each feed pipe (27).

2. The production equipment of silicon nitride bonded silicon carbide products according to claim 1, characterized in that, An installation plate (11) fixedly connected to the bracket (1) is arranged below the feed pipe (27). A plurality of bearing supports are arranged on the installation plate (11). A lead screw shaft (12) is arranged on each bearing support. A first motor (10) for driving the lead screw shaft (12) to rotate is arranged at the bottom of the installation plate (11). A nut seat (13) is arranged on each lead screw shaft (12). A lifting plate (14) is arranged on each nut seat (13). Two parallel first guide rails (15) are arranged on the lifting plate (14). Two sliders (16) are arranged on the two first guide rails (15). A sealing plate (17) is arranged on the two sliders (16). A fixing block (18) is arranged on the sealing plate (17). A tray (19) is arranged on the fixing block (18).

3. The production equipment for silicon nitride bonded silicon carbide products according to claim 1, characterized in that, Each blowing mechanism (3) includes a second motor (31), a motor seat (32), a first pulley (33), a second pulley (34), a transmission belt (35), a pivot shaft (36), and blades (37). The motor seat (32) is arranged on the top of the rotary furnace body (22). The second motor (31) is arranged on the motor seat (32). A first pulley (33) is arranged on the output shaft of the second motor (31). A second pulley (34) is arranged on one side of the first pulley (33). The second pulley (34) is connected to the first pulley (33) by belt transmission through the transmission belt (35). A vertically arranged pivot shaft (36) is arranged in the rotary furnace body (22). A plurality of blades (37) are arranged on the side wall of the pivot shaft (36) along the circumferential direction. The upper and lower ends of the pivot shaft (36) are respectively rotatably connected to the top wall and the bottom wall of the rotary furnace body (22). The upper end of the pivot shaft (36) is connected to the second pulley (34).

4. A production device for silicon nitride-bonded silicon carbide products according to claim 2, characterized in that, Guide blocks are arranged on the side surface of the lifting plate (14). Guide holes are arranged on the guide blocks. Two guide shafts (141) fixedly connected to the installation plate (11) are arranged in the guide holes.

5. The production equipment of silicon nitride bonded silicon carbide products according to claim 4, characterized in that, Two discharge plates (111) are arranged on both sides of the mounting plate (11), and two second guide rails (112) are arranged on each discharge plate (111).

6. The production equipment of silicon nitride bonded silicon carbide products according to claim 2, characterized in that, An annular boss (171) is arranged on the upper surface of the sealing plate (17), an annular groove (271) is arranged on the lower end surface of the feed pipe (27), and the annular boss (171) and the annular groove (271) are in vertical socket fit.

7. The production equipment of silicon nitride bonded silicon carbide products according to claim 5, characterized in that, A cooling cover (4) is arranged above the discharge plate (111), an air supply pipe (40) is arranged on the side wall of the cooling cover (4), two hydraulic cylinders (41) are arranged on both sides of the cooling cover (4), and the fixed end of each hydraulic cylinder (41) is fixedly connected to the discharge plate (111), and the telescopic end is fixedly connected to a mounting seat (42) arranged on the side wall of the cooling cover (4).

8. A production method of silicon nitride bonded silicon carbide products, characterized in that, It includes the following steps: S1. Loading and Sealing: Stack the silicon nitride bonded silicon carbide products formed by pressing on the tray (19), move the lifting plate (14) to below the feed inlet (26) by a forklift, the controller opens the gate valve (28) of the feed pipe (27), drives the first motor (10) to drive the lead screw shaft (12) to rotate clockwise, so that the nut seat (13) lifts the lifting plate (14), and the products enter the inner cavity of the double-sided furnace body (21) through the feed pipe (27), and stop after the sealing plate (17) seals the feed pipe (27). S2. Low-temperature Nitriding: The controller starts the silicon molybdenum rod electric heating element to heat the furnace body (2) to 900 - 1000 °C, with a heating rate of 6 - 10 °C / min, introduce 99.999% nitrogen, and circulate the gas through the air supply mechanism (3). S3. Medium-temperature Reaction: Continue to heat to 1300 - 1400 °C, with a heating rate of 4 - 5 °C / min, maintain the nitrogen pressure at 0.1 - 1 MPa, and circulate the gas until the temperature is balanced. S4. High-temperature Sintering: Heat to 1700 - 1800 °C, hold for 1 - 4 hours, form a liquid phase through the sintering aid to promote densification, and circulate the gas until the temperature is balanced. S5. Cooling and Discharging: The controller drives the first motor (10) to reverse the lead screw shaft (12) to lower the lifting plate (14), the products are removed from the furnace body through the feed pipe (27), after closing the gate valve (28), the hydraulic cylinder (41) drives the cooling cover (4) to cover the products, pump in nitrogen to cool down to below 800 °C, at a rate of 4 - 6 °C / min, and after being monitored by the temperature detector, the cooling cover is removed to obtain the silicon nitride bonded silicon carbide finished product.

9. The production method of silicon nitride bonded silicon carbide products according to claim 8, characterized in that, In the step (2), the heating rate is 8 °C / min, and nitrogen is introduced through the first inlet pipe (23) and the second inlet pipe (24); in the step (3), the nitrogen pressure is 0.5 MPa, and the heating rate is 4.5 °C / min; in the step (4), the sintering aid is the Y2O3 - Al2O3 system, and the holding time is 2 hours; in the step (5), the cooling cover (4) is connected to a nitrogen tank through the air supply pipe (40), and the cooling rate is adjusted by the controller to control the nitrogen flow rate.

Images