Graphite boat device for sintering hard alloy large plate and assembly structure

Abstract

The utility model discloses a graphite boat device for sintering a hard alloy large plate and an assembly structure. The graphite boat device comprises a graphite boat body, a supporting block, a supporting ball and a bonding solid, the graphite boat body further comprises side wall exhaust holes, supporting block clamping grooves, an annular arc groove and upper and lower end stacking clamping grooves. The supporting balls are placed on the periphery of the supporting block, and a pressed blank is placed on the same plane formed by the top ends of the supporting balls and the top end of the supporting block. When the pressed blank is sintered and shrunk, the supporting ball can be driven to roll freely, and the shrinkage resistance on the periphery of the pressed blank is almost zero; the supporting block in the middle plays a role in supporting and stabilizing the pressed blank and prevents the pressed blank from sliding; a communicating space is formed among the supporting balls, the supporting blocks and the side wall exhaust holes, so that the uniformity and the stability of the carbon atmosphere around the pressed blank are ensured; the periphery of the pressed blank is mainly subjected to heat transfer and heating in a heat radiation heat transfer mode, and it is guaranteed that the pressed blank is evenly heated. Therefore, the sintering deformation of the hard alloy large plate can be effectively reduced.

Description

Technical Field

[0001] This utility model relates to the field of cemented carbide product sintering technology, and more specifically, to a graphite boat device and assembly structure for sintering large cemented carbide plates. Background Technology

[0002] In the manufacturing process of cemented carbide products: after the compact is pressed, it is usually placed in a graphite boat. The surface in contact with the compact is coated with a paint to prevent the compact from reacting with the graphite boat surface and "sticking" during sintering (the cemented carbide compact cannot directly contact the graphite plate). It is then placed in a sintering furnace and sintered at high temperature into a dense, high-strength alloy. However, on the one hand, unlike other powder metallurgy materials (such as SiC and Si3N4-based ceramic composites) which are relatively insensitive to carbon atmospheres, cemented carbide is very sensitive to carbon atmospheres during sintering; on the other hand, cemented carbide has a high density (generally higher than 14 g / cm³). 3 This results in a higher weight of the compact, and in the contact area with the boat, the shrinkage resistance experienced by the compact during sintering is greater than that of other powder metallurgy materials (such as SiC, Si3N4, TiCN, TiN, etc. ceramic matrix composites). The density of these composites is generally 3 g / cm³, depending on the density and content of other additives. 3 ~8g / cm 3 The temperature is much higher; therefore, based on the characteristics of cemented carbide materials mentioned above, the following four aspects can easily lead to deformation of the cemented carbide compact during the sintering shrinkage process:

[0003] (1) The carbon atmosphere concentration around the compact is inconsistent, which leads to the time difference and different liquid phase potential energy during sintering, resulting in agglomeration and uneven shrinkage, thus causing deformation. As the contact area between the bottom of the compact and the graphite boat increases, sintering deformation is more likely to occur. This is because as the contact area between the bottom of the compact and the graphite boat increases, not only will the carbon atmosphere in the contact area and the non-contact area be inconsistent, but also the insufficient air flow in the contact area will cause the carbon atmosphere concentration in the center and the edge of the contact area to be inconsistent, thus aggravating sintering deformation.

[0004] (2) The resistance experienced by different parts during the shrinkage of the compact during sintering is not consistent. For example, the shrinkage resistance experienced by the area where the compact is in contact with the graphite boat must be greater than that of the area where it is not in contact. The path of the compact shrinking from the periphery to the center gradually decreases, so the energy required to resist the shrinkage resistance from the periphery to the center gradually decreases. In order to balance the difference in the energy required to resist the shrinkage resistance from the periphery to the center, the compact is prone to warping deformation around the periphery.

[0005] (3) Uneven heating of the compact leads to uneven shrinkage. For example, the bottom of the compact is in contact with the graphite boat, which is mainly for heat conduction, while the top of the compact is not in contact with the graphite boat, which is mainly for heat radiation. It is difficult for the heat conduction efficiency of the two to be consistent, which will lead to uneven heating of the compact.

[0006] (4) The weight of the compact itself, especially large compacts, will cause the friction between the bottom of the compact and the graphite boat to increase exponentially during high-temperature sintering shrinkage, which will seriously hinder the bottom shrinkage.

[0007] As the weight of the compact increases or the contact area between the compact and the boat increases, the sintering deformation of the compact will increase significantly, both in magnitude and probability. To address the sintering deformation problem of large cemented carbide plates, existing technologies have proposed several solutions, such as:

[0008] To ensure a uniform atmosphere distribution within the graphite boat, patents CN102002606B and CN203639532U incorporate several through-holes at the bottom of the graphite boat. This guarantees atmosphere uniformity within the boat and effectively mitigates sintering deformation in large cemented carbide plates. However, shrinkage resistance still exists in the area where the compact contacts the graphite boat, and the carbon atmosphere in the contact area cannot be guaranteed to be consistent with that in the non-contact area. Furthermore, consistent heat conduction and heating between the contact and non-contact areas cannot be guaranteed.

[0009] To reduce the shrinkage resistance in the contact area between the compact and the graphite boat during sintering, patent CN206561116U changed the contact area between the graphite boat and the compact from surface contact to multi-point contact, significantly reducing shrinkage resistance. Furthermore, the gaps between the point contacts also improved the uniformity of the carbon atmosphere at the bottom of the compact, effectively alleviating compact deformation. Patent CN207563735U, in addition to changing the contact between the compact and the graphite boat from surface contact to multi-point contact to improve contact resistance, further added several through holes at the bottom of the graphite boat to improve the uniformity of the carbon atmosphere at the bottom of the compact. However, in these technical solutions, contact shrinkage resistance still exists between the compact and the graphite boat; and the problem of consistent heat transfer between the contact and non-contact areas remains unresolved.

[0010] In summary, ensuring uniform carbon atmosphere and heating around the compact during sintering, and reducing shrinkage resistance between the compact and the boat / dish contact area, thereby enabling uniform sintering shrinkage in all areas of the compact and effectively alleviating sintering deformation, remains a problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0011] In view of this, the purpose of this utility model is to provide a graphite boat device and assembly structure for sintering large plates of cemented carbide. To achieve the above objective, this utility model provides the following technical solution:

[0012] The graphite boat apparatus and assembly structure for sintering large cemented carbide plates include: a graphite boat body, a support ball, a bonding solid, a support block, and a cemented carbide plate blank. The graphite boat body further includes: a lower end stacking and positioning groove, an upper end stacking and positioning groove, a side wall vent, a support block positioning groove, and an annular arc groove.

[0013] In one embodiment, the diameter or side length of the cemented carbide plate blank is at least greater than 60 mm, and the ratio of diameter or side length to thickness (height) is at least greater than 5.

[0014] In one embodiment, the graphite boat body can be of any shape, preferably circular or square.

[0015] Furthermore, the upper surface of the graphite boat body is generally flat, which facilitates the coating treatment of its upper surface, the assembly and placement of the support ball and the cemented carbide plate blank, and the removal of the cemented carbide plate sintered body after sintering.

[0016] In one embodiment, the annular arc groove is disposed on the upper surface plane of the graphite boat body, surrounding the graphite boat body. The opening width (groove width) of the annular arc groove is at least the diameter of the support ball + 0.5 mm. Since the size of the sintered hard alloy plate will decrease after sintering, and the bonding solid will completely volatilize or decompose, some of the support balls will be completely free. Therefore, this design aims to prevent the completely free support balls from rolling off when the previous layer of the graphite boat body is removed. The arc shape is used to reduce corner stress and prevent the graphite boat from cracking. The depth cannot be too deep, otherwise it will reduce the strength of the graphite boat body; the depth also cannot be too shallow, otherwise it will not effectively prevent the support balls from rolling off.

[0017] Furthermore, the depth of the annular arc groove is preferably 3mm to 5mm. For example, it can be 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, or 5mm, but is not limited to the listed values; other unlisted values ​​within the range are also applicable. The purpose of setting this groove depth is to ensure that the annular arc groove effectively restricts the supporting ball.

[0018] Furthermore, the outermost edge of the annular arc groove is 3mm to 5mm away from the edge of the upper surface of the graphite boat body. For example, it can be 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, or 5mm, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The purpose of this distance setting is to minimize the use of available space within the graphite boat body.

[0019] Furthermore, each corner of the annular arc groove (such as the 90° corner when the graphite boat body is square) also transitions with an arc shape. This aims to reduce corner stress and lower the risk of cracking in the graphite boat.

[0020] In one embodiment, the supporting sphere and the supporting block are made of a material that does not sinter and bond with the cemented carbide blank during sintering, or are coated with a material that does not sinter and bond with the blank during sintering. The material itself has low thermal conductivity and does not deform below 1600°C. Preferably, it is a high-purity graphite material (with a coating layer), silicon carbide-based ceramic material, zirconia-based ceramic material, or yttrium oxide-based ceramic material with low thermal conductivity. The requirement for low thermal conductivity aims to reduce the efficiency of heat conduction from the graphite boat body to the cemented carbide blank, ensuring that both the upper and lower parts of the cemented carbide blank undergo heat radiation, thereby ensuring the uniformity of heating of the cemented carbide blank. The requirement that the supporting sphere and the supporting block do not deform below 1600°C aims to minimize the sintering deformation of the cemented carbide blank if they do not deform during sintering.

[0021] Furthermore, if the support ball and the support block are made of high-purity graphite material with low thermal conductivity, the surface is treated with a non-stick coating layer before use. The coating contains silicon carbide ceramic material, zirconium oxide ceramic material, or yttrium oxide ceramic material with low thermal conductivity to prevent the hard alloy sintered body from reacting with it during the sintering process.

[0022] In one embodiment, on the upper surface of the graphite boat body, taking a region of the bottom size of the cemented carbide plate blank as a reference, a set of support block positioning grooves are arranged in an array symmetrically along the center of the bottom surface of the cemented carbide plate blank in the middle of this region.

[0023] Furthermore, the side length or diameter of the support block slot is preferably 5mm to 15mm. For example, it can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, or 15mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Furthermore, the depth of the support block slot is preferably 2mm to 3mm. For example, it can be 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, or 3mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Furthermore, the edge spacing between two adjacent support block slots is preferably 2mm to 8mm. For example, it can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, or 8mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] The support block slots are used to assemble the support blocks, and their spacing should be appropriate. If the spacing is too small, on the one hand, the space between the support blocks will obviously decrease, further affecting airflow; on the other hand, the number of support blocks will also increase, which is detrimental to assembly efficiency. If the spacing is too large, on the one hand, it will also affect airflow between the support blocks; on the other hand, the number of support points for the cemented carbide plate blank will decrease, and due to the gravity of the cemented carbide plate blank, the shrinkage resistance of the support points will easily increase, leading to increased sintering deformation.

[0027] Furthermore, the area of ​​the largest region enclosed by the line connecting the center points of the outermost support block slots is 20% to 50% of the bottom surface area of ​​the cemented carbide plate blank. For example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. The purpose of this arrangement is twofold: firstly, to ensure that the support block provides good stability to the cemented carbide sheet compact, preventing the sheet from sliding and preventing multiple compacts from colliding and cracking when placed in a single graphite boat, thus facilitating material transfer; secondly, during the sintering shrinkage process, the path of the cemented carbide sheet compact shrinking from the periphery to the center gradually decreases, thus reducing the energy required to resist the shrinkage resistance from the periphery to the center. As the energy required for the compact to resist the shrinkage resistance from the periphery to the center gradually decreases, the deformation of the compact from the periphery to the center also gradually decreases. Therefore, a portion of the compact in the center can be relatively fixed to ensure the first aspect of preventing the compact from sliding. The smaller the area of ​​the enclosed maximum region, the larger the supporting area of ​​the surrounding support spheres, which helps to improve the sintering deformation of the cemented carbide sheet blank. However, the support stability of the support block on the cemented carbide sheet blank is weakened, and the number of support spheres increases, reducing the assembly and disassembly efficiency of the graphite boat structure. Conversely, the larger the area of ​​the enclosed maximum region, the smaller the supporting area of ​​the surrounding support spheres, which is not conducive to improving the sintering deformation of the cemented carbide sheet blank. However, the support stability of the support block on the cemented carbide sheet blank is enhanced, and the number of support spheres decreases, which helps to improve the assembly and disassembly efficiency of the graphite boat structure.

[0028] In one embodiment, in other areas of the bottom dimension region of the aforementioned cemented carbide sheet blank, or around the support block slot, a group of support balls are placed in an array symmetrically along the center of the bottom surface of the cemented carbide sheet blank. All support balls are bonded and fixed with the adhesive solid to prevent the support balls from rolling.

[0029] Furthermore, the diameter of the support ball is preferably 5mm to 15mm. For example, it can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, or 15mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Furthermore, the edge spacing between two adjacent support balls is preferably 2mm to 8mm. For example, it can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, or 8mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Similar to the support block positioning groove, the spacing of the support balls should be appropriate. If the spacing is too small, on the one hand, the space between the support balls will obviously decrease, further affecting the airflow; on the other hand, the number of support balls will also increase, which is detrimental to assembly efficiency. If the spacing is too large, on the one hand, it will also affect the airflow between the support balls; on the other hand, the support points of the support balls on the cemented carbide plate blank will decrease. Due to the gravity of the cemented carbide plate blank, when the sintering shrinkage causes the support balls to roll, grooves are easily formed on the surface of the cemented carbide plate sintered body.

[0032] Furthermore, the bonding solid is a soft, viscous solid material at 20°C to 80°C; the bonding solid contains no oxygen or metallic elements; under pressure degreasing or vacuum heating conditions, below 400°C, the bonding solid can completely volatilize or decompose. The purpose of this arrangement is that, before sintering at 20°C to 80°C, the bonding solid is soft and viscous, which helps it deform and can adhere to the support ball, preventing it from rolling; while under pressure degreasing or vacuum heating conditions, below 400°C, it can completely volatilize or decompose, thus releasing its constraint on the support ball during high-temperature sintering. This allows the support ball to roll freely, greatly reducing the shrinkage resistance between the hard alloy plate blank and the support ball during sintering shrinkage, making the shrinkage resistance between them almost zero. The binder solid is selected from oxygen-free materials to prevent the oxygen-containing gases released during volatilization or decomposition from oxidizing the carbon in the compact, which would have the following adverse effects: (1) It would reduce the carbon content in the alloy, producing a decarburized phase and reducing performance; (2) Since the binder solid is placed at the bottom of the cemented carbide plate compact, if it volatilizes or decomposes and produces oxygen-containing gases, it would first react with the carbon components at the bottom of the compact, thus reducing the carbon content at the bottom of the compact, resulting in uneven carbon content between the top and bottom of the compact, and consequently causing sintering deformation of the compact. The binder solid is selected from metal-free materials because generally volatile metal elements (such as sodium, potassium, lithium, magnesium, or calcium) can easily enter the pores of the cemented carbide plate compact when they volatilize, causing contamination of the sintered body or affecting the growth of tungsten carbide grains, and the volatilized metal elements may even contaminate the sintering furnace cavity.

[0033] Further, the binder solid is preferably one or more mixtures of hydrocarbon compounds, the melting point of which is preferably 30°C to 90°C. For example, it can be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, or 90°C, but is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0034] In one embodiment, the shape and size of the lower end of the support block are the same as the shape and size of the support block slot, and it is assembled in the support block slot.

[0035] Furthermore, the lower end of the support block and the support block locking groove are in a clearance fit with a tolerance of 0.1mm to 0.2mm. If the clearance is too small, the assembly between the support block and the support block locking groove becomes more difficult, which is not conducive to assembly. More importantly, it prevents the support block from cracking due to excessive thermal expansion. If the clearance is too large, the assembly between the support block and the support block locking groove becomes unstable, which can easily cause the hard alloy plate blank to move.

[0036] Furthermore, the top of the support block is spherical.

[0037] Furthermore, the spherical crown-shaped top of the support block and the top of the support ball are in the same plane.

[0038] Furthermore, the edge spacing between two adjacent support balls and the support block is 2mm to 8mm. For example, it can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, or 8mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] It should be noted that the purpose of designing the support block slot and the support block is as follows: (1) to reduce the processing difficulty of the graphite boat body; (2) to remove the support block, so that the upper surface of the graphite boat body remains flat and can also be used to support other products; (3) as mentioned above, to facilitate the treatment of the upper surface of the graphite boat body (such as coating layer treatment); (4) to facilitate the replacement of the material of the support block.

[0040] In one embodiment, the cemented carbide plate blank is placed on the same plane formed by the top of the support ball and the crown-shaped top of the support block, forming an assembly structure.

[0041] In one embodiment, multiple sets of the above-described assembly structure can be repeatedly arranged in other areas on the upper surface of a graphite boat body, thereby enabling the placement of one or more of the cemented carbide plate blanks in a graphite boat body.

[0042] In one embodiment, a plurality of the sidewall vents are disposed below the bottom surface of the cemented carbide plate blank.

[0043] Furthermore, the central axes of all the sidewall vents are in the same horizontal plane, penetrate the sidewall of the graphite boat body, and are symmetrically and evenly distributed.

[0044] Furthermore, the diameter of the sidewall vent is preferably 2mm to 4mm. For example, it can be 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, or 4mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Furthermore, the plane formed by the central axis of the side wall vent holes bisects the support ball vertically.

[0046] Furthermore, when the graphite boat body is circular, the axial direction of the side wall vent hole points towards the center of the graphite boat body.

[0047] Furthermore, when the graphite boat body is square, the axial direction of the side wall vent is perpendicular to the side wall of the graphite boat body.

[0048] Furthermore, the number of sidewall vents is set as follows: when the side length of the largest area in the graphite boat body that can hold one or more of the cemented carbide sheet blanks is less than or equal to 100 mm or the diameter is less than or equal to 125 mm, the number of sidewall vents is 4 to 8; subsequently, based on the side length of the largest area in the graphite boat body that can hold one or more of the cemented carbide sheet blanks being 100 mm or the diameter being 125 mm, for every increase in the side length of the largest area in the graphite boat body that can hold one or more of the cemented carbide sheet blanks being greater than 50 mm or for every increase in the diameter being greater than 65 mm by n times (n is zero or a positive integer), the number of sidewall vents is increased by 4n based on the number of 8. The purpose of setting the number of side wall vents is as follows: Research has shown that when the number is small, it is not conducive to the exhaust and flow of atmosphere, and it is easy to create a "dead zone" around the inside of the graphite boat body, which further leads to inconsistent atmosphere concentration in the internal space; when the number is large, the efficiency of atmosphere exhaust and flow increases, which is easy to cause instability of the atmosphere in the internal space of the graphite boat body, which also leads to inconsistent atmosphere concentration in the internal space.

[0049] This utility model also provides a stacking structure, which is formed by stacking several graphite boat bodies and their internal assembly structures together through the lower stacking slot of the upper layer of graphite boat body and the upper stacking slot of the lower layer of graphite boat body.

[0050] Based on the above, compared with the prior art, the graphite boat device and assembly structure for sintering large cemented carbide plates provided by this utility model, during the shrinkage of the pressed blank during sintering, causes the support ball to roll freely on the plane of the graphite boat. Therefore, the shrinkage resistance experienced by the area around the pressed blank in contact with the support ball during sintering shrinkage is almost zero. The support block provides support and stability to the pressed blank, preventing it from sliding and preventing multiple pressed blanks from colliding and cracking when placed in one graphite boat, thus facilitating material transfer. The gaps between the support ball, support block, and side wall vents create sufficient space, ensuring not only sufficient atmosphere flow but also atmosphere stability, thereby ensuring the uniformity of the carbon atmosphere around the pressed blank. Simultaneously, the use of support balls and support blocks with low thermal conductivity ensures that the pressed blank is heated by thermal radiation, thus ensuring uniform heating. Therefore, it can effectively reduce the sintering deformation of large cemented carbide plates. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0052] Figure 1 A schematic diagram of the graphite boat-shaped dish device and its assembly structure provided in Embodiment 1 of this utility model;

[0053] Figure 2 for Figure 1 Top view;

[0054] Figure 3 A schematic diagram of the graphite boat-shaped dish device and its assembly structure provided in Embodiment 2 of this utility model;

[0055] Figure 4 for Figure 3 Top view;

[0056] Figure 5 A schematic diagram showing the deformation measurement of a large sheet blank after sintering and densification.

[0057] exist Figures 1-5 middle,

[0058] 100 is the graphite boat body; 110 is the lower stacking and positioning groove; 120 is the upper stacking and positioning groove; 130 is the side wall vent; 140 is the support block positioning groove; 150 is the annular arc groove; 155 is the rounded transition at the corner of the arc groove; 200 is the support ball; 300 is the bonding solid; 400 is the support block; 500 is the cemented carbide large plate blank; 510 is the sintered and dense cemented carbide large plate blank; 600 is the grade 0 marble testing platform. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The technical features designed in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the protection scope of this utility model.

[0060] In the description of this utility model, it should be noted that all terms used in this utility model (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model pertains, and should not be construed as limiting this utility model; it should be further understood that the terms used in this utility model should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this utility model.

[0061] Example 1

[0062] Please refer to Figure 1 and Figure 2 . Figure 1 A schematic diagram of the graphite boat-shaped vessel device and its assembly structure provided by this utility model; Figure 2 for Figure 1 Top view.

[0063] The graphite boat body (100) of this embodiment is circular, with an upper stacking slot (110) and a lower stacking slot (120) respectively provided on its upper and lower sides, allowing the graphite boat body (100) to be stacked in multiple layers in the height direction. The cemented carbide large plate blank (500) of this embodiment is circular, with a diameter of 108 mm and a thickness (height) of 20 mm.

[0064] Specifically, Figure 1 The illustrated embodiment provides a 3-layer stack.

[0065] The materials of the support ball (200) and the support block (400) can be high-purity graphite material with low thermal conductivity (with coating layer), silicon carbide-based ceramic material, zirconia-based ceramic material, or yttrium oxide-based ceramic material.

[0066] Specifically, if the support ball (200) and support block (400) are selected as high-purity graphite materials, they need to be coated with a non-stick coating before use. The coating contains silicon carbide ceramic material with low thermal conductivity, or zirconium oxide ceramic material, or yttrium oxide ceramic material to prevent the hard alloy plate blank (500) from reacting with it during the sintering process.

[0067] The top of the support block (400) is set as a spherical crown shape with a diameter of 8mm; the shape and size of the lower end of the support block (400) are the same as those of the support block slot (140), and its lower end is fitted into the support block slot (140).

[0068] Specifically, the clearance between the lower end of the support block (400) and the support block slot (140) is 0.1mm~0.2mm.

[0069] Specifically, the support block slot (140) is cylindrical in shape and has a diameter of 8mm.

[0070] Specifically, the depth of the support block slot (140) is 2.5 mm.

[0071] Specifically, the edge spacing between the two nearest adjacent support block slots (140) is 4.5 mm.

[0072] Specifically, the diameter of the support ball (200) is 8 mm, the edge spacing between the two nearest adjacent support balls is 4.5 mm, and they are arranged in an array symmetrically on the upper surface of the graphite boat body (100) along the center of the hard alloy plate blank (500), and are bonded and fixed with adhesive solid (300).

[0073] Specifically, the binder solid (300) is paraffin wax with a melting point of 46°C.

[0074] Specifically, the top of the spherical crown of the support block (400) and the top of the support ball (200) are in the same plane, that is, the total height of the support block (400) is 10.5mm.

[0075] Specifically, the edge spacing between the two nearest adjacent support balls (200) and the support block (400) is 4.5 mm.

[0076] Specifically, the support block slots (140) are arranged symmetrically in an array along the center of the bottom surface of the cemented carbide plate blank (500). Figure 1 Example 21); Connect the center points of all the outermost support block slots (140) with a line. The shape after connecting the lines is nearly circular. The area of ​​the largest area enclosed is about 20% of the bottom area of ​​the hard alloy plate blank (500).

[0077] Specifically, the opening width of the annular arc groove (150) is 8.5 mm, the depth is 4 mm, and the outermost edge is 3 mm away from the edge of the upper plane of the graphite boat body (100).

[0078] Specifically, several side wall vents (130) are provided below the bottom surface of the cemented carbide plate blank (500).

[0079] Specifically, the central axes of all the side wall vents (130) are in the same horizontal plane, pointing axially towards the center of the graphite boat body (100), penetrating the side wall of the graphite boat body (100), and are symmetrically and evenly distributed, totaling 6.

[0080] Specifically, the diameter of the side wall vent (130) is 3 mm.

[0081] Specifically, the distance between the central axis of the side wall vent (130) and the lower surface plane of the cemented carbide plate blank (500) is 4 mm.

[0082] In this embodiment, a large hard alloy plate blank (500) is placed on the upper surface of the graphite boat body (100).

[0083] Example 2

[0084] Please refer to Figure 3 and Figure 4 . Figure 3 A schematic diagram of the graphite boat-shaped vessel device and its assembly structure provided by this utility model; Figure 4 for Figure 3 Top view.

[0085] The graphite boat body (100) in this embodiment is square.

[0086] Specifically, the cemented carbide plate blank (500) in this embodiment is a square plate with a side length of 108mm and a thickness (height) of 20mm.

[0087] Specifically, in this embodiment, a set of support block slots (140) is set to 25, and the center line of the outermost support block slots (140) is a square, and the maximum area enclosed is about 20% of the bottom area of ​​the cemented carbide plate blank (500).

[0088] Specifically, the central axis of all the side wall exhaust holes (130) is in the same horizontal plane, and its axis is perpendicular to the side wall. They penetrate the side wall of the graphite boat body (100) and are symmetrically and evenly distributed, with 4 holes on each side and a total of 16 holes.

[0089] In this embodiment, four large hard alloy plate blanks (500) are placed on the upper surface of the graphite boat body (100).

[0090] The other settings are the same as in Example 1.

[0091] Example 3

[0092] The graphite boat device and assembly structure provided in this embodiment are the same as in Embodiment 1, except that the number of support block slots (140) and corresponding support blocks (400) is increased so that the area of ​​the largest region enclosed by the line connecting the center points of all the outermost support block slots (140) is about 50% of the bottom area of ​​the hard alloy plate blank (500).

[0093] Comparative Example 1

[0094] This comparative example provides a graphite boat device and assembly structure, in which all the support block slots (140) in Example 1 are removed, and all support blocks (400) are also removed. All the original support blocks (400) in Example 1 are replaced with support balls (200), that is, the area occupied by all support block slots (140) is 0% of the bottom surface area of ​​the cemented carbide large plate blank (500). Other settings are the same as in Example 1.

[0095] Comparative Example 2

[0096] The graphite boat device and assembly structure provided in this embodiment are the same as in Embodiment 1 except that the number of support block slots (140) and corresponding support blocks (400) is reduced, and the area of ​​the largest area enclosed by the line connecting the center points of all the outermost support block slots (140) is about 10% of the bottom area of ​​the hard alloy large plate blank (500), and the number of support balls (200) is increased.

[0097] Comparative Example 3

[0098] This comparative example provides a graphite boat device and assembly structure, in which all the support balls (200) in Example 1 are replaced with support blocks (400). Correspondingly, support block slots (140) are also formed on the upper surface of the replaced support blocks (400) corresponding to the graphite boat body (100). That is, the area of ​​the largest region enclosed by the center line connecting all the outermost support block slots (140) is close to 100% of the bottom surface area of ​​the cemented carbide large plate blank (500). Of course, since this comparative example eliminates the freely rolling support balls (200), the annular arc groove (150) can also be eliminated. Other settings are the same as in Example 1. The technical solution of this comparative example 1 is similar to the technical solution disclosed in patent CN206561116U.

[0099] Comparative Example 4

[0100] This comparative example provides a graphite boat-shaped vessel device and assembly structure, in which the side wall vent (130) in Example 1 is omitted. All other configurations are the same as in Example 1.

[0101] Comparative Example 5

[0102] This comparative example provides a graphite boat-shaped vessel device and assembly structure, in which the number of side wall vents (130) in Example 2 is set to 24. Other settings are the same as in Example 2.

[0103] Each embodiment and comparative example sintered 1000 corresponding cemented carbide plates, and the deformation and quantity of the cemented carbide plates were measured and statistically analyzed. The deformation measurement method was as follows: the sintered cemented carbide plate was placed flat on a plane without a "seesaw" phenomenon (generally, if this occurs, the cemented carbide plate can be turned upside down), maintaining stability. The vertical distance H1 between the highest point of the cemented carbide plate and the horizontal plane, and the average thickness H2 of the cemented carbide plate were measured (at least 5 different locations were measured, and the arithmetic mean was calculated). The deformation of the plate was then calculated as (H1 – H2) / 2. A schematic diagram of the test is shown below. Figure 5 As shown. It is obvious that if H1=H2, it indicates that the large plate has not been deformed. Table 1 lists the implementation effects of the embodiments and comparative examples of this utility model (statistics on the number and proportion of cemented carbide large plates with different deformation amounts).

[0104] As can be seen from the table, the deformation of the large plates in Examples 1 and 2 was almost entirely controlled below 0.05 mm.

[0105] Compared with Example 1, Example 3 shows that the deformation of the large plate is slightly increased due to the increased area of ​​the support block slot. However, the deformation of 96.4% of the large plates is still controlled below 0.05mm, and only the number of large plates with deformation between 0.05mm and 0.1mm has increased slightly.

[0106] Comparative Example 1, due to the elimination of the support block structure, should theoretically exhibit less deformation compared to Example 1. However, the results show that the deformation of the large plate was actually exacerbated, even exceeding that of Example 3. This is because during the sintering process, the central region of the large plate, lacking any stabilization measures, rolled freely with the support balls, causing the large plate to slide and contact the inner edge of the graphite boat body. This altered the surrounding spatial environment of the large plate, resulting in an uneven carbon atmosphere and uneven heat transfer, further intensifying the deformation. A more unfavorable effect of this comparative example is that, on the one hand, the increased number of support balls significantly reduced the efficiency of the boat loading process, doubling the loading time; on the other hand, when removing the upper graphite boat body, the large plate slipped, making removal extremely inconvenient and dangerous. Naturally, based on these unfavorable results, it is difficult to implement a scheme that simultaneously places multiple large cemented carbide plates within a single graphite boat body.

[0107] Table 1. Implementation effects of the embodiments and comparative examples of this utility model (number and proportion of large plates with different deformation amounts)

[0108] In Comparative Example 2, the supporting block occupies a smaller area, approximately 10% of the bottom surface area of ​​the large plate blank. Although it provides some stability to the large plate blank compared to Comparative Example 1, the smaller supporting area still allows for free sliding and displacement of the large plate blank. Therefore, the deformation of the large plate blank remains relatively severe; and the risks of low loading efficiency and easy slippage during unloading of the large plate blank, as seen in Comparative Example 1, persist.

[0109] In Comparative Example 3, the removal of the supporting ball structure led to a sharp increase in the deformation of the large plates, with nearly 80% of the plates having a deformation greater than 0.1 mm, and a small number of large plates having a deformation greater than 0.3 mm.

[0110] Compared with Example 1, Comparative Example 4 eliminated the side wall vent, which resulted in poor airflow inside the graphite boat, and consequently increased the deformation of the large plate. The proportion of the plates with deformation greater than 0.1 mm exceeded 12%.

[0111] Compared with Example 2, Comparative Example 5 increased the number of side wall vents, which led to unstable airflow inside the graphite boat and a greater increase in the deformation of the large plate. The proportion of the plates with deformation greater than 0.1 mm exceeded 4%.

[0112] The graphite boat apparatus and assembly structure for sintering large cemented carbide plates provided by this utility model have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A graphite boat apparatus and assembly structure for sintering large cemented carbide plates, characterized in that, include: The graphite boat body (100), support ball (200), bonding solid (300), support block (400), and hard alloy plate blank (500) are included; the graphite boat body (100) further includes: lower end stacking slot (110), upper end stacking slot (120), side wall vent (130), support block slot (140), and annular arc groove (150); The lower end of the support block (400) is fitted into the support block slot (140); The support balls (200) are arranged in an array symmetrically around the support block slot (140), and the support balls (200) are bonded and fixed to the upper surface plane of the graphite boat body (100) with the adhesive solid (300). The bonding solid (300) is a soft and sticky solid material at 20°C to 80°C; the bonding solid (300) does not contain oxygen or metal elements; under pressure degreasing or vacuum heating conditions, at a temperature below 400°C, the bonding solid (300) can completely volatilize or decompose. The supporting ball (200) and the supporting block (400) are made of the same material. The material itself or the surface is coated with a material that does not sinter and bond with the hard alloy blank during the sintering process. The material itself does not deform at temperatures below 1600°C, and the material itself or together with the coating is a material with low thermal conductivity. A cemented carbide plate blank (500) is placed on the same plane formed by the top of a set of support blocks (400) and the top of a set of support balls (200) placed around the support blocks (400) respectively, forming an assembly structure; One or more of the assembly structures may be provided on the upper surface of a graphite boat body (100), so that one or more of the hard alloy large plate blanks (500) can be placed in a graphite boat body (100) at the same time. The diameter or side length of the cemented carbide plate blank (500) must be at least 60 mm, and the ratio of diameter or side length to thickness (height) must be at least 5.

2. The graphite boat apparatus and assembly structure for sintering large cemented carbide plates according to claim 1, characterized in that, The support balls (200) are arranged in an array symmetrically along the center of the bottom surface of the cemented carbide plate blank (500); The diameter of the support ball (200) is 5mm to 15mm; the edge spacing between two adjacent support balls (200) is 2mm to 8mm.

3. The graphite boat apparatus and assembly structure for sintering large cemented carbide plates according to claim 1, characterized in that, The support block slots (140) are arranged in an array symmetrically along the center of the bottom surface of the cemented carbide plate blank (500); The opening side length or diameter of the support block slot (140) is 5mm~15mm, the depth is 2mm~3mm, and the edge distance between two adjacent support block slots (140) is 2mm~8mm. The area of ​​the largest region enclosed by connecting the center points of all the outermost support block slots (140) is 20% to 50% of the bottom area of ​​the cemented carbide plate blank (500).

4. The graphite boat apparatus and assembly structure for sintering large cemented carbide plates according to claim 1, characterized in that, The lower end of the support block (400) has the same shape and size as the support block slot (140) and is assembled in the support block slot (140); The lower end of the support block (400) and the support block slot (140) are in clearance fit with a tolerance of 0.1mm to 0.2mm.

5. The graphite boat apparatus and assembly structure for sintering large cemented carbide plates according to claim 1, characterized in that, The top of the support block (400) is spherical; The crown-shaped top of the support block (400) and the top of the support ball (200) are in the same plane; The edge spacing between two adjacent support blocks (400) and the support ball (200) is 2mm to 8mm.

6. The graphite boat apparatus and assembly structure for sintering large cemented carbide plates according to claim 1, characterized in that, The annular arc groove (150) is disposed on the peripheral edge area of ​​the upper surface plane of the graphite boat body (100) and surrounds the graphite boat body (100) for one circumference; The opening width (groove width) of the annular arc groove (150) is at least the diameter of the support ball (200) + 0.5 mm, the depth is 3 mm to 5 mm, and its outermost edge is 3 mm to 5 mm away from the edge of the upper plane of the graphite boat body (100). The annular arc groove (150) is transitioned by arcs (155) at each corner. When the graphite boat body (100) is square, the annular arc groove (150) is transitioned by arcs (155) at the 90° corner.

7. The graphite boat apparatus and assembly structure for sintering large cemented carbide plates according to claim 1, characterized in that, The binder solid (300) is one or more mixtures of hydrocarbon compounds; The melting point of the hydrocarbon compound is 30°C to 90°C.

8. The graphite boat apparatus and assembly structure for sintering large cemented carbide plates according to claim 1, characterized in that, The support ball (200) and the support block (400) are made of the same material, namely, high-purity graphite, silicon carbide-based ceramic, zirconium oxide-based ceramic, or yttrium oxide-based ceramic. When the support ball (200) and the support block (400) are made of high-purity graphite, their surfaces need to be treated with a non-stick coating layer before use. The coating contains silicon carbide ceramic material with low thermal conductivity, or zirconium oxide ceramic material, or yttrium oxide ceramic material to prevent the hard alloy sintered body from reacting with it during the sintering process.

9. The graphite boat apparatus and assembly structure for sintering large cemented carbide plates according to claim 1, characterized in that, The side wall vents (130) are located below the bottom surface of the cemented carbide plate blank (500). The central axes of all the side wall vents (130) are in the same horizontal plane, penetrate the side wall of the graphite boat body (100), and are symmetrically and evenly distributed. The diameter of the side wall vent (130) is 2mm~4mm; The plane formed by the central axis of the side wall vent (130) bisects the support ball (200) vertically. When the graphite boat body (100) is circular, the axial direction of the side wall vent (130) points to the center of the graphite boat body (100). When the graphite boat body (100) is square, the axial direction of the side wall vent (130) is perpendicular to the side wall of the graphite boat body (100). The number of side wall vents (130) is set as follows: when the side length of the largest area in the graphite boat body (100) where one or more of the cemented carbide plate blanks (500) can be placed is less than or equal to 100 mm or the diameter is less than or equal to 125 mm, the number of side wall vents (130) is 4 to 8; subsequently, based on the side length of the largest area in the graphite boat body (100) where one or more of the cemented carbide plate blanks (500) can be placed being 100 mm or the diameter being 125 mm, when the side length of the largest area in the graphite boat body (100) where one or more of the cemented carbide plate blanks (500) can be placed being increased by a factor of n (n is zero or a positive integer) for every increase of more than 50 mm or more than 65 mm, the number of side wall vents (130) is increased by 4n based on the number of 8.

10. A stacked structure, characterized in that: The graphite boat body (100) and its internal assembly structure are assembled together by stacking and positioning them in a vertical manner through the stacking slot (110) at the lower end of the graphite boat body (100) of the upper layer and the stacking slot (120) at the upper end of the graphite boat body (100) of the lower layer.

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