A graphite boat suitable for square tube carbonization furnace

Abstract

The utility model discloses a graphite boat dish suitable for square tube carbonization furnace belongs to metal powder preparation field, including boat dish body, is equipped with the gas hole of a plurality of on the side wall of boat dish. Through the gas hole of being equipped with on the side wall of boat dish, can make the internal and external protection gas of boat dish form convection channel, produce weak gas circulation between the inside and outside of boat dish, make oxygen and volatile gas and timely discharge. The gas hole is equivalent to micro - exhaust path, avoided the partial oxygen concentration too high problem that the inside of boat dish led to because of gas stagnation. Through the structure realizes the stabilization and purification of atmosphere in carbonization process, effectively slow down the speed of boat dish surface oxidation, prolong the life of boat dish. Meanwhile can reduce the composition deviation of material because of oxidation, guarantee the granularity and carbon content consistency of carbid product.

Description

Technical Field

[0001] This utility model belongs to the field of metal powder preparation, specifically a graphite boat suitable for square tube carbonization furnace. Background Technology

[0002] The fully automatic square tube carbonization furnace is a highly automated, temperature-controlled, high-productivity, and low-energy-consumption carbonization equipment. It is primarily used for the high-temperature carbonization of cemented carbide tungsten powder in the non-ferrous metals industry. The long-term operating temperature can reach 2000℃, and it is suitable for the production of coarse, medium, and fine-particle carbides. During production, the material is loaded into a graphite boat. By controlling certain process parameters, the graphite boat moves from the furnace head to the furnace tail, completing the carbonization process.

[0003] In the carbonization process, materials are typically loaded into graphite boats and slowly driven into the furnace by a transmission mechanism. Under multi-temperature zone control, the heating, holding, and cooling processes are completed, enabling the continuous carbonization reaction. To prevent oxidation from contact with air during carbonization, high-purity nitrogen or argon is generally used for protection within the furnace. However, in actual production, due to insufficient material pretreatment, high oxygen content in the feeding environment, and inadequate sealing of the protective gas, the materials entering the furnace may still contain a certain amount of oxygen or water vapor.

[0004] When the oxygen content of the material is too high, oxygen is very likely to react with the graphite boat under the high-temperature carbonization atmosphere. This will not only damage the surface structure of the boat, reducing its strength and service life, but also lead to a decrease in the stability of the furnace atmosphere, affecting the carbonization rate and carbon content control accuracy of the material.

[0005] Patent CN116140632A discloses a multi-layer boat and a method for preparing refractory metal powder using a multi-layer boat. The method involves laying raw material powder on the bottom of each single-layer boat in a multi-layer boat to form a raw material powder layer of a predetermined thickness. The multi-layer boat with the raw material powder is then placed in a reduction device, where the raw material powder is reduced to metal powder. Each single-layer boat has gas channels on its bottom and sidewalls, which facilitates the uniform dispersion of reducing gas into the interior of the single-layer boat, improving the uniformity of the reduction process. This device is primarily used for the diffusion of reducing gas into the boat, but it does not prevent the boat from oxidizing. Utility Model Content

[0006] The purpose of this invention is to provide a graphite boat suitable for a square tube carbonization furnace, so as to solve the problems mentioned in the prior art.

[0007] A graphite boat dish suitable for a square tube carbonization furnace is provided, comprising: The vessel body has several air holes on its side walls.

[0008] Furthermore, the number of pores is 4-12.

[0009] Furthermore, the diameter of the pores is 6mm-15mm.

[0010] Furthermore, the plurality of pores are respectively distributed on two opposite sidewalls of the vessel body.

[0011] Furthermore, the number of pores on the two opposite sidewalls of the vessel body is the same.

[0012] Furthermore, a base is provided at the bottom of the vessel body, and the thickness of the base is 25mm-40mm.

[0013] Furthermore, the bottom of the base is recessed inward to form two mutually perpendicular guide grooves.

[0014] Furthermore, the two ends of the guide rail groove are respectively formed with flared structures extending towards the ends.

[0015] Furthermore, the clearance between the guide rail groove and the guide rail inside the furnace is 5mm-10mm.

[0016] Furthermore, the corners of the vessel body are rounded.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows: By creating vents in the sidewalls of the crucible, a convection channel is formed between the inside of the crucible and the external protective gas, generating a weak gas circulation between the inside and outside of the crucible, allowing oxygen and volatile gases to be discharged in a timely manner. The vents act as miniature exhaust paths, preventing the problem of excessively high local oxygen concentrations caused by gas stagnation inside the crucible. This structure stabilizes and purifies the atmosphere during the carbonization process, effectively slowing down the oxidation rate of the crucible surface and extending its lifespan. Simultaneously, it reduces compositional deviations caused by material oxidation, ensuring consistency in particle size and carbon content of the carbonized product. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the external structure of a graphite boat suitable for a square tube carbonization furnace; Figure 2 This is a schematic diagram of the internal structure of a graphite boat suitable for a square tube carbonization furnace.

[0020] In the diagram: 1. Boat body; 11. Air vent; 2. Base; 21. Guide rail groove. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0022] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0023] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0024] Please see Figures 1-2 As shown in the embodiment of this utility model, a graphite boat suitable for a square tube carbonization furnace includes a boat body 1, and a plurality of air holes 11 are provided on the side wall of the boat body 1.

[0025] During pre-firing or drying, residual moisture, organic matter, and adsorbed gases inside the boat body 1 will escape. The pores 11 provide a direct discharge channel for these volatiles and adsorbed oxygen, shortening degassing time and reducing the residual oxygen content in the material layer. When the boat body 1 is pushed from the furnace head into the furnace chamber under inert gas protection flow, the external protective gas generates a dynamic pressure difference on the boat body along the flow direction within the furnace. The pores 11 allow the protective gas to enter the interior of the boat body 1 and expel residual air, water vapor, and low-boiling-point impurities. As the temperature rises, the material releases more volatiles, and the desorption rate of adsorbed water and oxygen increases. Simultaneously, the graphite surface becomes more sensitive to oxygen at high temperatures. The pores 11 promote internal and external convection and diffusion, rapidly removing degassed and oxygen, and reducing local oxygen partial pressure.

[0026] In summary, the pores 11 establish a controllable gas exchange channel between the interior of the boat body 1 and the protective gas in the furnace throughout the carbonization process, thereby reducing the oxygen partial pressure inside the boat, venting the volatilized / reacted gases, stabilizing the atmosphere and temperature field, and ultimately reducing boat oxidation, improving carbonization quality and boat life.

[0027] The number of pores 11 can be designed from 4 to 12 depending on the oxygen content of the material. Their function is to achieve a balance between the ventilation performance and structural strength of the graphite boat. If the number of pores 11 is too small, gas exchange within the furnace will be insufficient, making it difficult for oxygen to escape in time, which can easily lead to oxidation of the boat at high temperatures. Conversely, too many pores 11 will weaken the load-bearing capacity of the graphite wall and increase the risk of thermal stress concentration. By controlling the number of pores 11 to between 4 and 12, it is possible to ensure smooth gas flow during carbonization, reduce the oxygen content of the material, and maintain the overall strength and service life of the graphite boat, thus achieving a balance between stability and durability in the high-temperature carbonization process.

[0028] The diameter of pore 11 is 6mm-15mm. The larger the pore diameter, the greater the single-pore ventilation capacity, thus more effectively removing residual oxygen and reaction gas inside the boat. However, increasing the pore diameter also significantly increases the material removal and stress concentration on the wall section. Therefore, in engineering, a trade-off must be made between pore diameter, number of pores, wall thickness, and pore arrangement: small pores are used for low-oxygen materials, while large pores are required for high-oxygen materials or strong degassing.

[0029] In one embodiment, an air inlet short cylinder is provided at the top opening or center of the boat body 1, and several air holes 11 are provided on the side wall of the boat body 1. During use, inert gas is continuously introduced into the boat from the top opening of the boat body 1 or through the air inlet short cylinder, and residual oxygen and reactant gases are then discharged from the boat through the side wall air holes 11 to maintain a low-oxygen carbonization atmosphere inside the boat. This embodiment effectively reduces the oxygen partial pressure inside the boat by forming a top-down and side-exhaust airflow field through top air intake and side wall exhaust, inhibiting the oxidation of the graphite boat and improving the uniformity of the carbides and the automation reliability of the equipment.

[0030] In one embodiment, multiple pores 11 are distributed on two opposite sidewalls of the boat body 1. During the operation of the fully automatic square tube carbonization furnace, protective gas enters through the pores 11 on one side of the boat body 1 and exits through the pores 11 on the other side, forming a transverse airflow channel running from one side to the other. Because the pores 11 are symmetrically and uniformly distributed along their length, this transverse flow exists uniformly throughout the entire length of the boat, making the pressure distribution inside and outside the boat more balanced. As the airflow passes through the boat, it continuously carries and dilutes the oxygen, water vapor, and reaction byproduct gases generated during heating inside the boat, thereby achieving continuous replacement and purification, maintaining the inertia and stability of the carbonization environment.

[0031] Furthermore, the number of pores 11 on the two opposite sidewalls of the boat body 1 is the same. Having the same number of pores on both sides can ensure that the boat is heated and stressed evenly, avoid the reduction in wall thickness caused by too many pores on one side, improve the structural symmetry and stability, ensure that the boat maintains geometric stability during continuous transfer in the furnace and under high-temperature conditions, and reduce deformation and stress damage.

[0032] During the operation of the fully automatic square tube carbonization furnace, the graphite boat is continuously moved along the guide rail inside the furnace by a boat-pushing device. The base 2 of the boat body 1 directly bears the weight of the boat itself, the weight of the loaded material, and the pushing force applied by the boat-pushing device. If the thickness of the base 2 is insufficient or its design strength is inadequate, high temperature, long-term friction, and load will cause local wear, cracks, or even perforation of the base 2, thereby affecting the structural stability of the boat and the continuous operation of the carbonization furnace.

[0033] By designing the base 2 to be 25mm-40mm thick, the bearing cross-sectional area of ​​the base 2 is increased, resulting in a more uniform stress distribution under load and reducing local stress concentration. At the same time, the thickened base 2 can improve the wear resistance of the base 2, making it less prone to perforation or deformation under high temperature, friction and thrust. The structural reinforcement of the base 2 also enhances the overall stability of the boat, ensuring precise alignment during multi-round carbonization production, guaranteeing uniform contact between materials and atmosphere, and making the carbonization process stable and reliable.

[0034] During the operation of the fully automatic square tube carbonization furnace, the boat body 1 needs to be automatically moved along the furnace guide rail by the boat pushing device. The guide rail groove 21 on the base 2 precisely matches the furnace guide rail, which can realize the positioning and force distribution of the boat, so that the boat remains stable during the pushing, moving and unloading process, and prevents uneven carbonization process or boat jamming caused by lateral or longitudinal tilting. The bottom of the base 2 is recessed inward to form two mutually perpendicular guide rail grooves 21. The cross-shaped guide rail groove 21 design includes two mutually perpendicular grooves in the longitudinal and transverse directions, which can simultaneously accommodate the boat pushing action in multiple directions, making it convenient for multiple boats to be arranged or staggered at the same time, improving the flexibility and automation adaptability of the transmission system.

[0035] In one specific embodiment, the cross-shaped guide groove 21 of the base 2 of the boat body 1 is automatically aligned with the guide rail inside the carbonization furnace, with a fitting gap of 5mm-10mm. The boat, filled with material, is pushed into the charging machine via an automatic traveling device. The boat, filled with material, is pushed from the furnace head into the square tube carbonization furnace. A specific temperature and pushing speed are set according to process requirements. The coarser the tungsten carbide powder produced, the higher the carbonization temperature and the slower the pushing speed, resulting in a longer carbonization time. The furnace is equipped with boat guide rails. After carbonization, the graphite boat moves out of the furnace along the rails and enters the automatic unloading device. After unloading, the empty graphite boat re-enters the charging machine for the next round of carbonization, thus achieving the automation requirements.

[0036] It should be noted that the thickness of the base 2 includes the depth of the guide rail groove 21.

[0037] Both ends of the guide rail groove 21 form flared structures extending towards the ends. The graphite boat needs to be automatically moved along the guide rail inside the furnace by the boat pushing device. If both ends of the guide rail groove 21 are ordinary straight grooves, the boat may not be fully aligned with the guide rail when it is pushed into or moved out of the guide rail, or there may be edge collisions or a sudden increase in friction, which may cause the boat to jam and affect continuous carbonization production.

[0038] By setting a flared structure at the end of the guide rail groove 21, the groove gradually widens, forming a gradual guiding zone. When the boat enters or exits the furnace guide rail, the flared guide can automatically guide the base 2 to align with the guide rail, reducing contact collision surfaces and frictional resistance, allowing the boat to enter or exit the guide rail smoothly and steadily. This design can also tolerate a certain amount of installation or pushing error, reducing the dependence of operation on precision and improving the reliability and automation stability of the boat pushing system.

[0039] The fit clearance between the guide rail groove 21 and the guide rail inside the furnace is 5mm-10mm. An appropriate clearance ensures sufficient guidance for the boat's longitudinal or lateral movement, preventing excessive friction or jamming due to tightness, and also preventing the boat from wobbling on the guide rail and affecting stability due to excessive width. The reasonable width ensures uniform force distribution on the boat during pushing, reducing localized stress concentration and wear on the base 2, while also preventing jamming due to thermal expansion in the high-temperature carbonization environment.

[0040] During carbonization, the boat is placed in a high-temperature inert atmosphere, but residual oxygen in the material or trace amounts of air in the furnace can still cause localized oxidation. If the corner of the boat body is an acute angle, the material thickness at the acute angle is relatively thin, and it is easy to form a dead zone for airflow. The protective gas flows slowly or stagnates at this point, and oxygen easily accumulates locally, making this area an oxidation-sensitive point. At high temperatures, these stress concentrations and gas stagnation areas will accelerate the oxidation of graphite materials, causing localized corrosion, cracks, or even edge chipping, reducing the service life of the boat.

[0041] Therefore, rounded corners are provided at the corners of the boat body 1, with a radius R of 3mm-10mm. The rounded corners allow for smooth airflow along the corners, enabling the protective gas to more evenly cover the boat surface, preventing oxygen stagnation and thus reducing the risk of localized oxidation. The rounded corners also disperse thermal and mechanical stresses at the corners, preventing the formation of cracks or micropores, which are often entry points for oxidation reactions. The rounded corner structure improves material thickness and structural continuity, making it difficult for oxidizing gases to accumulate locally, thus enhancing the boat's overall oxidation resistance and the stability of the carbonization process.

[0042] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A graphite boat suitable for a square tube carbonization furnace, characterized in that, include: The vessel body (1) has several air holes (11) on its side wall.

2. The graphite boat-shaped vessel suitable for a square tube carbonization furnace according to claim 1, characterized in that, The number of pores (11) is 4-12.

3. A graphite boat suitable for a square tube carbonization furnace according to claim 1, characterized in that, The diameter of the pore (11) is 6mm-15mm.

4. A graphite boat suitable for a square tube carbonization furnace according to claim 1, characterized in that, The multiple pores (11) are respectively distributed on two opposite sidewalls of the boat body (1).

5. A graphite boat suitable for a square tube carbonization furnace according to claim 4, characterized in that, The number of pores (11) on the two opposite sidewalls of the vessel body (1) is the same.

6. A graphite boat suitable for a square tube carbonization furnace according to claim 1, characterized in that, The bottom of the vessel body (1) is provided with a base (2), and the thickness of the base (2) is 25mm-40mm.

7. A graphite boat suitable for a square tube carbonization furnace according to claim 6, characterized in that, The bottom of the base (2) is recessed inward to form two mutually perpendicular guide grooves (21).

8. A graphite boat-shaped vessel suitable for a square tube carbonization furnace according to claim 7, characterized in that, The guide rail groove (21) has flared structures extending towards the ends at both ends.

9. A graphite boat-shaped vessel suitable for a square tube carbonization furnace according to claim 7, characterized in that, The clearance between the guide rail groove (21) and the guide rail inside the furnace is 5mm-10mm.

10. A graphite boat-shaped vessel suitable for a square tube carbonization furnace according to claim 1, characterized in that, The corners of the vessel body (1) are rounded.

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