Multi-size detachable combined graphite mold suitable for plasma sintering

Abstract

The utility model relates to a multi-size detachable combined graphite mold suitable for plasma sintering, belongs to the field of design and manufacture of plasma sintering graphite molds, and aims to solve the problem that the combination of molds can be adjusted according to the size of a required sample so as to meet the required size requirement, and has the technical key points that a middle mold sleeve comprises a plurality of middle mold sleeves with different diameters; the middle die sleeves are cylindrical, the upper surfaces of the protrusions of the lower base support the bottoms of the middle die sleeves, the middle die sleeves of different diameters are coaxially nested and arranged on the upper surface of the base, and the pressing heads of different diameters can be matched with the middle die sleeves of different diameters. The outer die sleeve is cylindrical, the outer die sleeve is coaxially nested and arrayed outside the bulge and the middle die sleeve supported on the upper surface of the bulge, and the upper surface of the lower base supports the bottom of a cylinder of the outer die sleeve, so that the graphite die is detachable, each component can be independently replaced, and the combination of the die can be adjusted at any time according to the size of a sample; and further, the required size requirement is met.

Description

Technical Field

[0001] This utility model relates to the field of design and manufacturing of graphite molds for plasma sintering in powder metallurgy and ceramic production, specifically to a multi-size detachable combined graphite mold suitable for plasma sintering. Background Technology

[0002] Plasma sintering (SPS) is an advanced rapid sintering technology developed in Japan in the 1990s, aiming to overcome the limitations of traditional sintering methods (such as hot pressing and pressureless sintering). Traditional methods rely on high temperatures and long holding times, which easily lead to coarsening of material grains, high energy consumption, and difficulty in preparing high-performance nanomaterials. SPS uses pulsed direct current to directly act on powder particles, generating a plasma discharge effect in a mold. Combined with pressure and Joule heating, it achieves rapid densification (from a few minutes to tens of minutes). Its core principle is to activate the powder surface through an electric field to accelerate diffusion and atomic migration, thereby obtaining highly dense materials at lower temperatures. In the preparation process, dry powder is filled into a graphite mold, and then pulsed direct current is applied from a uniaxial direction while pressure is applied, so that molding and sintering are completed simultaneously. Plasma sintering time is short (traditional methods take several hours, while SPS only takes a few minutes), which can inhibit grain growth and is suitable for preparing nanocrystalline and amorphous materials. Plasma activation can reduce the sintering temperature (100-300℃ lower than traditional methods), saving energy and avoiding high-temperature decomposition of materials. This technology produces products with a density exceeding 99%, significantly improving mechanical and electrical properties, and is particularly suitable for ceramics and metal-based composite materials. Furthermore, plasma sintering technology can sinter traditionally difficult-to-process materials (such as high-melting-point metals and ultra-hard ceramics) and achieve precise fabrication of gradient materials and multilayer structures. Simultaneously, independent control of temperature, pressure, and current facilitates optimization of the microstructure and reduces the formation of impurity phases.

[0003] The main disadvantages of plasma sintering technology lie in the fact that the powder is directly loaded into the graphite mold and pressure and current are directly applied. Therefore, the raw material is prone to sticking to the inner wall of the graphite mold during the sintering process. At the same time, the mold may react with certain materials (such as active metals) at high temperatures, and the graphite mold is easily worn and needs to be replaced frequently. In addition, during the sintering process, there is a possibility that the temperature and pressure settings may be too high, causing some samples to melt, which may cause the pressure head to get stuck in the mold sleeve. Utility Model Content

[0004] This utility model aims to provide a multi-size detachable modular graphite mold, which allows for adjustment of the mold assembly according to the required sample size to achieve the desired dimensions, and is easy to replace. According to some embodiments of this application, a multi-size detachable modular graphite mold suitable for plasma sintering is described, including...

[0005] First electrode;

[0006] The upper base has a first electrode on its upper surface and several cylindrical grooves of different diameters formed on its lower part. The cylindrical grooves of different diameters are concentric stepped cylindrical grooves with gradually increasing diameters.

[0007] The pressure head includes several pressure heads of different diameters. The pressure head is cylindrical, and the pressure heads of different diameters can be matched with cylindrical grooves of different diameters.

[0008] Second electrode;

[0009] The lower base has a second electrode on its lower surface and a protrusion formed in the center of its upper surface that is higher than the upper surface.

[0010] The intermediate mold sleeve includes several intermediate mold sleeves of different diameters. The intermediate mold sleeve is cylindrical. The raised upper surface of the lower base supports the bottom of the intermediate mold sleeve. The intermediate mold sleeves of different diameters are coaxially nested and arranged on the upper surface of the base. The pressure head of different diameters can cooperate with the intermediate mold sleeves of different diameters.

[0011] The outer mold sleeve is cylindrical and is coaxially nested outside the protrusion and the middle mold sleeve supported on the upper surface of the protrusion. The upper surface of the lower base supports the bottom of the outer mold sleeve cylinder.

[0012] The gasket includes several gaskets of different diameters. The gaskets are in the shape of circular pieces. The gaskets of different diameters can be adapted to intermediate mold sleeves of different diameters. The gaskets are set at the bottom of the intermediate mold sleeves, and the raised upper surface of the lower base supports the bottom surface of the gaskets.

[0013] The upper base, pressure head, lower base, middle mold sleeve, outer mold sleeve, and gasket are all made of graphite.

[0014] According to some embodiments of this application, a multi-size detachable combined graphite mold suitable for plasma sintering is described, wherein the protrusion has a first height along the axial direction, the intermediate mold sleeve has a second height along the axial direction, and the outer mold sleeve has a third height along the axial direction, and the sum of the first height and the second height is less than the third height.

[0015] According to some embodiments of this application, a multi-size detachable combined graphite mold suitable for plasma sintering is described, wherein, among any two adjacent intermediate molds of different diameters, the inner wall of the outer intermediate mold abuts against the outer wall of the inner intermediate mold, and the outer wall of the outermost intermediate mold abuts against the inner wall of the outer mold.

[0016] According to some embodiments of this application, a multi-size detachable combined graphite mold suitable for plasma sintering is described, wherein the upper base includes a base and a protrusion disposed below the base, the protrusion being formed into a plurality of cylindrical grooves of different diameters.

[0017] According to some embodiments of this application, a multi-size detachable modular graphite mold suitable for plasma sintering is described, wherein the lower base includes a base and a protrusion disposed above the base.

[0018] According to some embodiments of this application, the multi-size detachable combined graphite mold suitable for plasma sintering has a clearance fit between the pressure head and the cylindrical groove, and a clearance fit between the pressure head and the intermediate mold sleeve.

[0019] According to some embodiments of this application, a multi-size detachable combined graphite mold suitable for plasma sintering is described, wherein the pressure head includes a first pressure head, a second pressure head, and a third pressure head;

[0020] The concentric stepped cylindrical groove includes a first cylindrical groove, a second cylindrical groove, and a third cylindrical groove;

[0021] The intermediate mold includes a first intermediate mold, a second intermediate mold, and a third intermediate mold;

[0022] Among them, the opening diameter of the outer mold sleeve matches the outer diameter of the third intermediate mold sleeve, the opening diameter of the third mold sleeve matches the outer diameter of the second intermediate mold sleeve, and the opening diameter of the second mold sleeve matches the outer diameter of the first intermediate mold sleeve.

[0023] The opening diameter of the third mold sleeve matches the diameter of the third pressure head, the opening diameter of the second mold sleeve matches the diameter of the second pressure head, and the opening diameter of the first mold sleeve matches the diameter of the first pressure head.

[0024] The opening diameter of the third cylindrical groove matches the diameter of the third pressure head, the opening diameter of the second cylindrical groove matches the diameter of the second pressure head, and the opening diameter of the first cylindrical groove matches the diameter of the first pressure head.

[0025] According to some embodiments of this application, a multi-size detachable combined graphite mold suitable for plasma sintering is described, wherein the gasket includes a first gasket, a second gasket, and a third gasket.

[0026] The first gasket is adapted to the diameter of the first intermediate mold sleeve and can be disposed at the bottom of the first intermediate mold sleeve; the second gasket is adapted to the diameter of the second intermediate mold sleeve and can be disposed at the bottom of the second intermediate mold sleeve; the third gasket is adapted to the diameter of the third intermediate mold sleeve and can be disposed at the bottom of the third intermediate mold sleeve.

[0027] According to some embodiments of this application, a multi-size detachable modular graphite mold suitable for plasma sintering is described, wherein the thickness of the gasket is 10 mm.

[0028] According to some embodiments of this application, a multi-size detachable combined graphite mold suitable for plasma sintering is described, in which a first electrode covers the upper surface of the upper base and a second motor covers the lower surface of the lower base.

[0029] Beneficial effects:

[0030] This invention proposes a multi-size detachable modular graphite mold. The upper base has cylindrical grooves of different diameters to accommodate pressure heads of varying diameters. The lower base has multiple nested mold sleeves of different diameters. By selectively combining these mold sleeves, hollow slots of different diameters can be obtained. These hollow slots hold the sample powder to be sintered, such as ceramic powder. By assembling the cylindrical grooves, pressure heads, mold sleeves, and gaskets of different sizes, the pressure head fits into the hollow slot, allowing the lower surface of the pressure head, the inner wall of the mold sleeve, and the upper surface of the gasket to contact the sample powder. Conductivity is achieved through electrodes and corresponding graphite components, enabling micro-discharge of pulsed current across the particle gaps, thus sintering the sample. This modular design allows for the production of sintered samples of different diameters. Furthermore, the modular component arrangement makes it easier to replace the mold sleeves and other components.

[0031] Therefore, the multi-size detachable combined graphite mold proposed in this utility model can adjust the combination of molds at any time according to the required sample size, so as to achieve the required size requirements, and is easy to replace.

[0032] Therefore, the multi-size detachable combined graphite mold proposed in this utility model, with its openable and closable mold sleeve, can effectively prevent the pressure head from getting stuck in the mold.

[0033] Therefore, the multi-size detachable combined graphite mold proposed in this utility model has a simple mold structure, is easy to install and disassemble, has low demolding difficulty after powder metallurgy, and each component can be replaced individually, which can effectively improve the mold utilization rate, reduce production costs, and achieve good implementation results. Attached Figure Description

[0034] Figure 1 This is a cross-sectional view of a multi-size detachable modular graphite mold suitable for plasma sintering in the embodiment.

[0035] Figure 2 This is a schematic diagram of the intermediate pressure head and the maximum pressure head of the multi-size detachable combined graphite mold suitable for plasma sintering in the embodiment.

[0036] Figure 3 This is a top view of the lower base of a multi-size detachable modular graphite mold suitable for plasma sintering in the embodiment.

[0037] Marked in the image:

[0038] 1. Upper base; 2. Minimum pressure head; 3. Maximum mold sleeve; 4. Maximum intermediate mold sleeve; 5. Intermediate size intermediate mold sleeve; 6. Minimum mold sleeve; 7. Minimum gasket; 8. Lower base; 9. Intermediate pressure head; 10. Maximum pressure head; 11. Intermediate gasket; 12. Maximum gasket. Detailed Implementation

[0039] The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the design method of a multi-size detachable combined graphite mold suitable for plasma sintering (SPS). Addressing the issues of mold wear and jamming in SPS technology, this invention aims to provide a multi-size detachable combined graphite mold that allows for easy adjustment of the mold assembly according to the required sample size, thereby achieving the desired dimensions. Simultaneously, the openable mold sleeve effectively prevents the pressure head from jamming within the mold. The mold structure is simple, easy to install and disassemble, and simplifies demolding after powder metallurgy. Individual components can be replaced, effectively improving mold utilization, reducing production costs, and demonstrating good implementation results.

[0040] This utility model relates to a multi-size detachable composite graphite mold suitable for plasma sintering. The graphite mold includes a first electrode, an upper base 1, a pressure head, a second electrode, a lower base 8, an intermediate mold sleeve, and an outer mold sleeve. The upper base 1 has a first electrode on its upper surface, and its lower part is formed with several cylindrical grooves of different diameters, which are concentric stepped cylindrical grooves with gradually increasing diameters. The pressure head includes several cylindrical pressure heads of different diameters, each capable of engaging with a different diameter cylindrical groove. The lower base 8 has a second electrode on its lower surface, and a raised section above the upper surface is formed at the center of its upper surface. The intermediate mold sleeve includes several cylindrical intermediate mold sleeves of different diameters. The raised upper surface of the lower base 8 supports the bottom of the intermediate mold sleeves. The intermediate mold sleeves of different diameters are coaxially nested and arranged on the upper surface of the base, and the pressure heads of different diameters can engage with the intermediate mold sleeves of different diameters. The outer mold sleeve is cylindrical and coaxially nested outside the protrusion and the intermediate mold sleeve supported on the upper surface of the protrusion. The upper surface of the lower base 8 supports the bottom of the outer mold sleeve. The gaskets include several gaskets of different diameters, which are circular. Gaskets of different diameters can be fitted to intermediate mold sleeves of different diameters. The gaskets are located at the bottom of the intermediate mold sleeves, and the upper surface of the protrusion of the lower base 8 supports the bottom surface of the gaskets. The upper base 1, pressure head, lower base 8, intermediate mold sleeve, outer mold sleeve, and gaskets are all made of graphite.

[0041] In one example, the pressure head includes a first pressure head, a second pressure head, and a third pressure head. The concentric stepped cylindrical groove includes a first cylindrical groove, a second cylindrical groove, and a third cylindrical groove. The intermediate mold sleeve includes a first intermediate mold sleeve, a second intermediate mold sleeve, and a third intermediate mold sleeve. The gasket includes a first gasket, a second gasket, and a third gasket.

[0042] The outer mold sleeve has an opening diameter that matches the outer diameter of the third intermediate mold sleeve, the third mold sleeve has an opening diameter that matches the outer diameter of the second intermediate mold sleeve, and the second mold sleeve has an opening diameter that matches the outer diameter of the first intermediate mold sleeve. The third mold sleeve has an opening diameter that matches the diameter of the third pressure head, the second mold sleeve has an opening diameter that matches the diameter of the second pressure head, and the first mold sleeve has an opening diameter that matches the diameter of the first pressure head. The third cylindrical groove has an opening diameter that matches the diameter of the third pressure head, the second cylindrical groove has an opening diameter that matches the diameter of the second pressure head, and the first cylindrical groove has an opening diameter that matches the diameter of the first pressure head. A first gasket is adapted to the diameter of the first intermediate mold sleeve and can be disposed at the bottom of the first intermediate mold sleeve. A second gasket is adapted to the diameter of the second intermediate mold sleeve and can be disposed at the bottom of the second intermediate mold sleeve. A third gasket is adapted to the diameter of the third intermediate mold sleeve and can be disposed at the bottom of the third intermediate mold sleeve.

[0043] In this embodiment, a multi-size detachable combined graphite mold suitable for plasma sintering is used. The first pressure head is the smallest pressure head 2, the second pressure head is the intermediate pressure head 9, the third pressure head is the largest pressure head 10, the outer mold sleeve is the largest mold sleeve 3, the third intermediate mold sleeve is the largest intermediate mold sleeve 4, the second intermediate mold sleeve is the intermediate size intermediate mold sleeve 5, the first intermediate mold sleeve is the smallest mold sleeve 6, the first gasket is the smallest gasket 7, the second gasket is the intermediate gasket 11, and the third gasket is the largest gasket 12.

[0044] The largest mold sleeve 3 is a cylindrical ring. The largest intermediate mold sleeve 4, the intermediate size intermediate mold sleeve 5, and the smallest mold sleeve 6 are all axial cylindrical rings or cylindrical rings assembled from two semi-cylindrical rings. The smallest pressure head 2, the intermediate pressure head 9, and the largest pressure head 10 are all cylindrical. The smallest gasket 7, the intermediate gasket 11, and the largest gasket 12 are all cylindrical. Due to their very small thickness, they can also be called circular pieces.

[0045] The upper base 1 consists of a base 1a, a protrusion 1b, and a cylindrical groove. The cylindrical groove includes a minimum groove 1c, a middle groove 1d, and a maximum groove 1e. The diameter of the base 1a is defined as... The thickness is d1. The height of protrusion 1b is d3, and the outer diameter is... The depths of grooves 1c, 1d, and 1e are 3d², 2d², and d², respectively, and their inner diameters are... , , And d3 = 3d2.

[0046] The lower base 8 consists of a base 8a and a protrusion 8b. The diameter of the base 8a is , and its thickness is defined as d8. The diameter of the protrusion 8b is , and its height is defined as d7.

[0047] The diameter of the minimum indenter 2 is , and its length is defined as d9. The diameter of the intermediate indenter 9 is , and its length is defined as d10 = d9 - d2. The diameter of the maximum indenter 10 is , and its length is defined as d11 = d9 - 2d2.

[0048] The outer diameter of the maximum die sleeve 3 is equal to the diameters of the bases 1a and 8a of the upper and lower bases, which is , and the inner diameter is equal to the diameters of the protrusions 1b and 8b of the upper and lower bases, which is , and its height is defined as d4.

[0049] The outer diameter of the maximum intermediate die sleeve 4 is , and the inner diameter is . The outer diameter of the intermediate-sized intermediate die sleeve 5 is , and the inner diameter is . The outer diameter of the minimum die sleeve 6 is , and the inner diameter is . The heights of the three are equal and defined as d5.

[0050] The diameters of the minimum spacer 7, the intermediate spacer 11, and the maximum spacer 12 are , , respectively, and their thicknesses are equal and defined as d6.

[0051] In the preferred solution, the surface roughness of each component is less than or equal to 5 μm. d5 + d7 < d4 < d9 + d6, d6 < d3 < d5 < d9, and the sizes of each component can be taken according to actual needs under the condition of satisfying the size relationship. In one example, among them, , , , , , , , , , , , , , , , .

[0052] This invention relates to a multi-size detachable combined graphite mold suitable for plasma sintering. The dimensions of each component can be selected according to actual needs while meeting size requirements, offering high flexibility and wide applicability. In practical use, the dimensions of the pressure head, mold sleeve, and gaskets must correspond precisely, especially the diameters.

[0053] Spark plasma sintering (SPS) is an advanced sintering method that achieves rapid densification of materials through direct heating with pulsed current and plasma activation. The basic principle is that a pulsed direct current passes directly through a conductive mold (such as graphite) and the sample, utilizing Joule heating (…). High temperatures are generated, and the sample area becomes the main heat source due to contact resistance and its own resistance (heat concentration effect).

[0054] If the sample is conductive (e.g., metal), the current heats the sample directly. If the sample is insulating (e.g., ceramic), heating relies on conduction through the mold. Pulsed current generates micro-discharges in the interparticle gaps, forming localized plasmas that break down the surface oxide layer and promote atomic diffusion. Axial mechanical pressure (typically 10-100 MPa) works synergistically with high temperature to eliminate porosity and accelerate sintering.

[0055] The present invention is a detachable, modular graphite mold. The upper base has cylindrical grooves of different diameters to accommodate pressure heads of different diameters. The lower base has multiple nested mold sleeves of different diameters. By selectively combining these mold sleeves, hollow slots of different diameters can be obtained. These hollow slots are used to hold the sample powder to be sintered, such as ceramic powder. By assembling the cylindrical grooves, pressure heads, mold sleeves, and gaskets of different sizes, the pressure head fits into the hollow slot, allowing the lower surface of the pressure head, the inner wall of the mold sleeve, and the upper surface of the gasket to contact the sample powder. Through the electrodes and corresponding graphite components, electrical conductivity is achieved, generating micro-discharges of pulsed current between the particles, sintering the sample. This assembly structure can be used to obtain sintered samples of different diameters.

[0056] Example 1: Preparation of diameter sintered samples, With the same inner diameter as the minimum mold sleeve, the maximum mold sleeve 3, the maximum intermediate mold sleeve 4, the intermediate size intermediate mold sleeve 5, and the minimum mold sleeve 6 are layered and fitted together. The minimum gasket 7 is placed in the minimum mold sleeve 6 and installed at its bottom, so that the lower surface of the minimum gasket contacts the upper surface of the protrusion of the lower base 8. The sample powder is then placed in the minimum mold sleeve 6.

[0057] Select the smallest pressure head 2 and install it in the first cylindrical groove of the upper base 1. The diameter of the first cylindrical groove is also... The upper base 2 is inserted into the hollow groove of the minimum mold sleeve 6 of the lower base 8 through the minimum pressure head 2. The assembled mold is placed on the hydraulic press. The upper base plate of the hydraulic press is a fixed plate, and the lower base plate of the hydraulic press is a movable plate, i.e., an upward push plate. When the hydraulic press is started, the lower base plate of the hydraulic press contacts the second electrode of the lower base 8 of the mold. The mold is mounted on the lower base plate of the hydraulic press. The lower base plate of the hydraulic press rises until the first electrode on the upper surface of the upper base 2 of the mold contacts the upper base plate of the hydraulic press, and the lower base plate continues to rise, so that the upper base plate and the lower base plate apply pressure to the lower base 8 and the upper base 2 from top to bottom, so that the lower surface of the pressure head, the inner wall of the mold sleeve, the upper surface of the gasket and the sample powder are in full contact.

[0058] When current is applied to the first and second electrodes, since all components of the mold are made of graphite, which is conductive, if the sample is conductive (e.g., metal), the current directly heats the sample. If the sample is insulating (e.g., ceramic), heating relies on conduction through the mold. The pulsed current generates micro-discharges between particles, forming localized plasma that breaks down the surface oxide layer and promotes atomic diffusion. Axial mechanical pressure (typically 10-100 MPa) works synergistically with high temperature to eliminate porosity and accelerate sintering, thus enabling its application in… Plasma sintering of the sample.

[0059] Example 2: Preparation of diameter sintered samples, With the same inner diameter as the intermediate mold sleeve, the maximum mold sleeve 3, the maximum intermediate mold sleeve 4, and the intermediate mold sleeve 5 are layered and fitted together. The intermediate gasket 11 is placed in the intermediate mold sleeve 5 and installed at its bottom, so that the lower surface of the intermediate gasket 11 contacts the raised upper surface of the lower base 8. The sample powder is placed in the intermediate mold sleeve 5.

[0060] Select the intermediate pressure head 9 and install it in the second cylindrical groove of the upper base 1. The diameter of the second cylindrical groove is also... The upper base 2 is inserted into the hollow groove of the intermediate mold sleeve 5, which is oriented towards the middle dimension of the lower base 8, through the intermediate pressure head 9. The assembled mold is then placed on a hydraulic press. The upper base plate of the hydraulic press is a fixed plate, and the lower base plate is a movable plate, i.e., an upward push plate. When the hydraulic press is started, the lower base plate of the hydraulic press contacts the second electrode of the lower base 8 of the mold. The mold is mounted on the lower base plate of the hydraulic press. The lower base plate of the hydraulic press rises until the first electrode on the upper surface of the upper base 2 of the mold contacts the upper base plate of the hydraulic press, and the lower base plate continues to rise. This allows the upper and lower base plates to apply pressure to the lower base 8 and the upper base 2, ensuring that the lower surface of the pressure head, the inner wall of the mold sleeve, the upper surface of the gasket, and the sample powder make full contact.

[0061] When current is applied to the first and second electrodes, since all components of the mold are made of graphite, which is conductive, if the sample is conductive (e.g., metal), the current directly heats the sample. If the sample is insulating (e.g., ceramic), heating relies on conduction through the mold. The pulsed current generates micro-discharges between particles, forming localized plasma that breaks down the surface oxide layer and promotes atomic diffusion. Axial mechanical pressure (typically 10-100 MPa) works synergistically with high temperature to eliminate porosity and accelerate sintering, thus enabling its application in… Plasma sintering of the sample.

[0062] Example 3: Preparation of diameter The sample, With the same inner diameter as the largest intermediate mold sleeve 4, the largest mold sleeve 3 and the largest intermediate mold sleeve 4 are fitted together in layers. The largest gasket 12 is placed in the largest intermediate mold sleeve 4 and installed at its bottom, so that the lower surface of the largest gasket 12 contacts the upper surface of the protrusion of the lower base 8. The sample powder is placed in the largest intermediate mold sleeve 4. The largest pressure head 10 is selected and installed in the third cylindrical groove of the upper base 1. The diameter of the third cylindrical groove is also... The upper base 2 is inserted into the hollow groove of the largest intermediate mold sleeve 4 of the lower base 8 through the maximum pressure head 10. The assembled mold is placed on a hydraulic press. The upper base plate of the hydraulic press is a fixed plate, and the lower base plate of the hydraulic press is a movable plate, i.e., an upward push plate. When the hydraulic press is started, the lower base plate of the hydraulic press contacts the second electrode of the lower base 8 of the mold. The mold is mounted on the lower base plate of the hydraulic press. The lower base plate of the hydraulic press rises until the first electrode on the upper surface of the upper base 2 of the mold contacts the upper base plate of the hydraulic press, and the lower base plate continues to rise, so that the upper and lower base plates apply pressure to the lower base 8 and the upper base 2, so that the lower surface of the pressure head, the inner wall of the mold sleeve, the upper surface of the gasket and the sample powder are in full contact. The first and second electrodes are energized. Since all parts of the mold are made of graphite, which is conductive, if the sample is conductive (such as metal), the current directly passes through the sample for heating. If the sample is insulating (such as ceramic), the heating depends on the conduction of the mold. The pulsed current generates micro-discharge in the interparticle gaps, forming local plasma, breaking the surface oxide layer and promoting atomic diffusion. Axial mechanical pressure (typically 10-100 MPa) works synergistically with high temperature to eliminate porosity and accelerate sintering, thus enabling its application in [various applications]. Plasma sintering of the sample.

[0063] Example 4: This example describes the disassembly of a multi-sized detachable composite graphite mold suitable for plasma sintering. Since most molds are fixed using a hole-shaft fit, the pressure head can be pulled out first from the hollow groove of the mold sleeve, then from the circular groove, and finally the intermediate mold sleeve can be removed. Based on the above dimensional descriptions, it can be understood that the mold sleeve and other components are also fixed using a hole-shaft fit. If removal is difficult, the base can be laid down to help separate the mold sleeve, base, etc.

[0064] Compared with the prior art, the main advantages of this invention are that the mold combination can be adjusted at any time according to the required sample size to achieve the required dimensions; at the same time, the openable and closable mold sleeve can effectively prevent the pressure head from getting stuck in the mold. The mold structure is simple, easy to install and disassemble, and easy to demold after powder metallurgy. Each component can be replaced individually, which can effectively improve the mold utilization rate and reduce production costs.

[0065] As described above, this utility model relates to a multi-size detachable combined graphite mold suitable for plasma sintering. The mold includes upper and lower bases, three pressure heads of different sizes, three gaskets of different sizes, and a set of layered mold sleeves of different sizes, wherein the base size is fixed. The graphite mold designed by this method is detachable, and each component can be replaced individually. Furthermore, the mold combination can be adjusted at any time according to the size of the sample to achieve the required dimensions. Simultaneously, the openable and closable mold sleeves effectively prevent the pressure heads from getting stuck in the mold. The advantages of this utility model patent are that it achieves plasma sintering of samples of multiple sizes through the combination of different layered mold sleeves. Its structure is simple, installation and disassembly are convenient, demolding after powder metallurgy is easy, and the individual replacement of each component effectively improves mold utilization, reduces production costs, and achieves good implementation results.

[0066] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0067] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0068] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0069] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0070] In this invention, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one" refers to one or more; "at least one of A and B," similar to "A and / or B," describes the relationship between related objects, indicating that three relationships can exist. For example, at least one of A and B can represent: A alone, A and B simultaneously, or B alone.

[0071] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A multi-size detachable modular graphite mold suitable for plasma sintering, characterized in that, include First electrode; The upper base has a first electrode on its upper surface and several cylindrical grooves of different diameters formed on its lower part. The cylindrical grooves of different diameters are concentric stepped cylindrical grooves with gradually increasing diameters. The pressure head includes several pressure heads of different diameters. The pressure head is cylindrical, and the pressure heads of different diameters can be matched with cylindrical grooves of different diameters. Second electrode; The lower base has a second electrode on its lower surface and a protrusion formed in the center of its upper surface that is higher than the upper surface. The intermediate mold sleeve includes several intermediate mold sleeves of different diameters. The intermediate mold sleeve is cylindrical. The raised upper surface of the lower base supports the bottom of the intermediate mold sleeve. The intermediate mold sleeves of different diameters are coaxially nested and arranged on the upper surface of the base. The pressure head of different diameters can cooperate with the intermediate mold sleeves of different diameters. The outer mold sleeve is cylindrical and is coaxially nested outside the protrusion and the middle mold sleeve supported on the upper surface of the protrusion. The upper surface of the lower base supports the bottom of the outer mold sleeve cylinder. The gasket includes several gaskets of different diameters. The gaskets are in the shape of circular pieces. The gaskets of different diameters can be adapted to intermediate mold sleeves of different diameters. The gaskets are set at the bottom of the intermediate mold sleeves, and the raised upper surface of the lower base supports the bottom surface of the gaskets. The upper base, pressure head, lower base, middle mold sleeve, outer mold sleeve, and gasket are all made of graphite.

2. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, The protrusion has a first height along the axial direction, the intermediate mold sleeve has a second height along the axial direction, and the outer mold sleeve has a third height along the axial direction. The sum of the first height and the second height is less than the third height.

3. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, in, For any two adjacent intermediate molds of different diameters, the inner wall of the outermost intermediate mold abuts against the outer wall of the innermost intermediate mold, and the outer wall of the outermost intermediate mold abuts against the inner wall of the outermost mold.

4. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, The upper base includes a base and a protrusion located below the base, the protrusion being formed into several cylindrical grooves of different diameters.

5. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, The lower base includes a base and a protrusion disposed on the base.

6. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, The fit between the pressure head and the cylindrical groove is a clearance fit, and the fit between the pressure head and the intermediate mold sleeve is a clearance fit.

7. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, The pressure head includes a first pressure head, a second pressure head, and a third pressure head; The concentric stepped cylindrical groove includes a first cylindrical groove, a second cylindrical groove, and a third cylindrical groove; The intermediate mold includes a first intermediate mold, a second intermediate mold, and a third intermediate mold; Among them, the opening diameter of the outer mold sleeve matches the outer diameter of the third intermediate mold sleeve, the opening diameter of the third mold sleeve matches the outer diameter of the second intermediate mold sleeve, and the opening diameter of the second mold sleeve matches the outer diameter of the first intermediate mold sleeve. The opening diameter of the third mold sleeve matches the diameter of the third pressure head, the opening diameter of the second mold sleeve matches the diameter of the second pressure head, and the opening diameter of the first mold sleeve matches the diameter of the first pressure head. The opening diameter of the third cylindrical groove matches the diameter of the third pressure head, the opening diameter of the second cylindrical groove matches the diameter of the second pressure head, and the opening diameter of the first cylindrical groove matches the diameter of the first pressure head.

8. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, in, Gaskets, including a first gasket, a second gasket, and a third gasket; The first gasket is adapted to the diameter of the first intermediate mold sleeve and can be disposed at the bottom of the first intermediate mold sleeve; the second gasket is adapted to the diameter of the second intermediate mold sleeve and can be disposed at the bottom of the second intermediate mold sleeve; the third gasket is adapted to the diameter of the third intermediate mold sleeve and can be disposed at the bottom of the third intermediate mold sleeve.

9. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, in, The thickness of the gasket is 10mm.

10. The multi-size detachable combined graphite mold suitable for plasma sintering according to claim 1, characterized in that, The first electrode covers the upper surface of the upper base, and the second motor covers the lower surface of the lower base.

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