A sintered graphite boat set for powder metallurgy

Abstract

The utility model relates to the technical field of hard alloy production, concretely is a sintered graphite boat set for powder metallurgy, mainly includes a plurality of groups of upper and lower stacked boat bodies, and is provided with rectangular graphite baffle between two adjacent groups of boat bodies, and the end of rectangular graphite baffle is provided with exhaust gap, the boat body is composed of bottom plate and a plurality of small cylinders, the flat plate material tray is placed in the upper of boat set, the product is supported through small cylinder, reduces the contact area, when high -temperature sintering, the friction resistance that product shrinkage received is reduced greatly, fundamentally avoids the oval deformation, the gap between small cylinder forms " horizontal air flow channel", and the atmosphere on the upper surface of product forms convection, avoids the liquid phase shrinkage of lower surface because of carbon potential too high and appears too early dense, part of hydrogen in the furnace flows to the lower surface of product through the small cylinder gap of single boat, balances the carbon potential of upper and lower surfaces, another part is discharged outside the furnace through the exhaust gap, avoids the atmosphere stagnation, and the flat plate material tray blocks the air flow direct impact top product.

Description

Technical Field

[0001] This utility model relates to the field of cemented carbide production technology, specifically to a sintered graphite boat and dish assembly for powder metallurgy. Background Technology

[0002] Hard alloy products require high-temperature sintering during production to impart specific shapes, sizes, microstructures, and physical and mechanical properties. Currently, graphite boats used for hard alloy sintering are mainly divided into round and square types. Round boats consist of a round base plate and sidewalls, with limited atmosphere flow achieved only through the gap between the base plate and sidewalls. Square boats consist of a square base plate and sidewalls, with a dedicated atmosphere flow channel only created in the upper part of the sidewalls. Both types of graphite boats share common defects, leading to significant problems during sintering, especially for hard alloy discs with a height of less than 5mm. The main defects are uneven atmosphere distribution and significant differences in product performance, as the atmosphere can only pass through the limited channels at the edge of the boat. The flow of carbon is difficult to penetrate to the center of the boat, resulting in significant differences in the carbon atmosphere environment between products near and far from the flow channel. This ultimately leads to substantial differences in the hardness, density, and other physical and mechanical properties of the sintered products, resulting in poor product quality stability. Simultaneously, the products are prone to deformation; cemented carbide discs with a height of less than 5mm are easily deformed into elliptical shapes during sintering. The first core reason is the inconsistent carbon atmosphere contacting the upper and lower surfaces of the product, with differences in carbon potential causing different shrinkage rates. The second core reason is that the upper surface of the existing graphite boat is a complete plane, fully contacting the lower surface of the cemented carbide disc, with a contact area of ​​100%. During high-temperature sintering and shrinkage, the frictional resistance experienced by the cemented carbide blank in all directions is extremely uneven, further exacerbating deformation. Utility Model Content

[0003] The purpose of this invention is to provide a sintered graphite boat assembly for powder metallurgy to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution: A sintered graphite boat assembly for powder metallurgy, comprising: The vessel body is provided in multiple sets, and the multiple sets of the vessel bodies are stacked one on top of the other. Multiple sets of rectangular graphite baffles are provided between two adjacent sets of the vessel bodies, and an exhaust gap is provided between the ends of two adjacent sets of rectangular graphite baffles. The vessel body consists of a base plate and multiple sets of small cylinders spaced apart on the base plate, and the upper surface of the small cylinders is an alloy sintered surface. A flat tray is placed above the boat-shaped container assembly.

[0005] Preferably, the vessel body is integrally molded from high-purity graphite material.

[0006] Preferably, the base plate is rectangular or circular to support the small cylinder.

[0007] Preferably, the small cylinder has a diameter of 4mm, and the center-to-center distance between two adjacent sets of small cylinders is 10mm; The height of the small cylinder is half that of the boat-shaped vessel.

[0008] Preferably, the rectangular graphite baffles are provided in four sets, which are respectively distributed around the upper surface of the base plate.

[0009] Preferably, the height of the rectangular graphite strip is 9mm higher than that of the sintered cemented carbide disc.

[0010] Preferably, the exhaust gap spacing is 5mm.

[0011] Preferably, the flat tray is made of the same material and size as the base plate.

[0012] Compared with the prior art, the beneficial effects of this utility model are: By supporting the product with the upper surface of the small cylinder, the contact area can be reduced to 40%-45% of the traditional solution. During high-temperature sintering, the frictional resistance to product shrinkage is greatly reduced, and the resistance in all directions is uniform, fundamentally avoiding elliptical deformation. The gaps between the small cylinders form a "transverse airflow channel". The sintering atmosphere in the furnace can penetrate to the lower surface of the product through this channel and form convection with the atmosphere on the upper surface of the product. This effectively improves the carbon atmosphere difference between the upper and lower surfaces of the product and prevents the lower surface from becoming too dense due to excessive carbon potential. Hydrogen gas enters the boat-and-vessel assembly from the furnace chamber. Part of it flows to the lower surface of the product through the small cylindrical gaps between individual boats to balance the carbon potential of the upper and lower surfaces. The other part flows from the bottom to the top of the boat-and-vessel assembly through the 5mm gaps between the rectangular graphite baffles in the interlayer, and is finally discharged outside the furnace to avoid local atmosphere stagnation. As the furnace temperature rises, the cemented carbide discs slowly shrink. Due to the "low resistance and uniform resistance" characteristics brought about by the small cylindrical support, the shrinkage rate of the products is consistent in all directions. At the same time, the flat plate tray prevents the airflow from directly impacting the top products, ensuring that all products are in a consistent atmosphere. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the boat-and-vessel assembly structure of this utility model; Figure 2 This is a side view of the boat-and-vessel assembly structure of this utility model; Figure 3 This is a schematic cross-sectional view of the boat-and-dish assembly structure at point AA of this utility model; Figure 4 This is a schematic diagram of the structure of the vessel body of this utility model.

[0014] In the diagram: 1. Base plate; 2. Rectangular graphite baffle; 3. Flat material tray; 4. Exhaust gap; 5. Small cylinder. Detailed Implementation

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0016] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0017] like Figures 1-4 As shown, this application provides a sintered graphite boat assembly for powder metallurgy, comprising:

[0018] Multiple sets of boat-shaped vessels are stacked one on top of each other. The vessels are made of high-purity graphite material and are integrally molded to ensure high temperature resistance. They are suitable for the sintering temperature of hard alloys of 1300-1600℃ and have good chemical stability and are free from impurities.

[0019] Specifically, such as Figure 4 As shown, the vessel body consists of a base plate 1 and multiple sets of small cylinders 5 spaced apart on the base plate 1. The base plate 1 is rectangular or circular and is used to support the small cylinders 5.

[0020] Specifically, such as Figure 4 As shown, the small cylinder 5 has a diameter of 4mm. This diameter ensures both support stability and minimizes the contact area. The center-to-center distance between two adjacent sets of small cylinders 5 is 10mm, ensuring that there is sufficient gap between the small cylinders 5 for gas flow, and at the same time, the products can be arranged reasonably to increase the amount of sintering per batch. The height of the small cylinder 5 is half that of the boat-shaped vessel body, so as to avoid the small cylinder 5 being too high, which would cause the product's center of gravity to be unstable, or too low, which would affect the gas flow space. The upper surface of the small cylinder 5 is an alloy sintered surface.

[0021] Specifically, such as Figures 1-3 As shown, four sets of rectangular graphite baffles 2 are provided between two adjacent sets of the boat-shaped vessels, respectively distributed around the upper surface of the base plate 1 to ensure stacking stability.

[0022] Specifically, such as Figures 1-3 As shown, the height of the rectangular graphite baffle 2 is the height of the sintered hard alloy disc + 9mm, with the standard being "able to surround the edge of the vessel and the product, without obstructing the gas flow path".

[0023] Specifically, such as Figures 1-3 As shown, an exhaust gap 4 is provided between the ends of two adjacent sets of rectangular graphite baffles 2. The exhaust gap 4 is spaced 5mm apart, serving as an interlayer gas exhaust channel to avoid gas stagnation and resulting in uneven local atmosphere.

[0024] Specifically, such as Figures 1-3 As shown, a flat material tray 3 is provided above the boat-shaped tray assembly. It is made of the same material and has the same size as the bottom plate 1. It is used to block the airflow in the furnace from directly impacting the top layer of products and reduce the carbon potential difference between the top products and the edge products.

[0025] Working principle: Individual boat-shaped vessels are stacked sequentially. Rectangular graphite baffles 2 are placed at the four corners of the upper and lower boat-shaped vessels, ensuring that there is an exhaust gap 4 between the ends of adjacent sets of rectangular graphite baffles 2. A flat material tray 3 is placed on top of the uppermost boat-shaped vessel. Hard alloy discs with a height of less than 5mm are placed one by one on the surface of the small cylinders 5 on each individual boat-shaped vessel, ensuring that the product is centered. The assembled boat-shaped vessel group is sent into the sintering furnace, and the sintering program is started. As the furnace temperature rises, the hard alloy discs slowly shrink. After sintering is completed, the furnace temperature drops to room temperature. The boat-shaped vessel group is removed, the flat material tray 3 and the rectangular graphite baffles 2 are removed, and the sintered hard alloy discs are taken out.

[0026] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary; within the framework of this invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of this invention as described above, which are not provided in the details for the sake of brevity.

[0027] This utility model is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A sintered graphite boat / dish assembly for powder metallurgy, characterized in that, include: The vessel body is provided in multiple sets, and the multiple sets of the vessel bodies are stacked on top of each other. Multiple sets of rectangular graphite baffles (2) are provided between adjacent sets of the vessel bodies, and an exhaust gap (4) is provided between the ends of adjacent sets of rectangular graphite baffles (2). The vessel body is composed of a base plate (1) and multiple sets of small cylinders (5) spaced apart on the base plate (1), and the upper surface of the small cylinders (5) is an alloy sintered surface; A flat tray (3) is placed above the boat-shaped container assembly.

2. The sintered graphite boat assembly for powder metallurgy according to claim 1, characterized in that, The vessel body is made of high-purity graphite material in one piece.

3. The sintered graphite boat-dish assembly for powder metallurgy according to claim 1, characterized in that, The base plate (1) is set to be rectangular or circular to support the small cylinder (5).

4. The sintered graphite boat assembly for powder metallurgy according to claim 3, characterized in that, The small cylinder (5) has a diameter of 4 mm, and the center-to-center distance between two adjacent sets of small cylinders (5) is 10 mm. The height of the small cylinder (5) is half that of the boat-shaped vessel.

5. A sintered graphite boat-dish assembly for powder metallurgy according to claim 1, characterized in that, The rectangular graphite baffles (2) are provided in four groups, which are distributed around the upper surface of the base plate (1).

6. A sintered graphite boat-dish assembly for powder metallurgy according to claim 5, characterized in that, The height of the rectangular graphite strip (2) is 9 mm higher than that of the sintered hard alloy disc.

7. A sintered graphite boat assembly for powder metallurgy according to claim 6, characterized in that, The exhaust gap (4) has a spacing of 5 mm.

8. A sintered graphite boat assembly for powder metallurgy according to claim 7, characterized in that, The size and material of the flat plate tray (3) are the same as those of the base plate (1).

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