Sintering device for improving material temperature uniformity and application and design method thereof

Abstract

The invention belongs to the technical field related to alloy manufacturing, and discloses a sintering device for improving material temperature uniformity and application and a design method thereof, the sintering device comprises a reaction furnace body and a temperature regulation and control unit, and the reaction furnace body comprises a reaction cavity and a furnace door; the temperature regulation and control unit comprises heating structures, the heating structures are arranged on the left side and the right side in the reaction cavity correspondingly, the heating structure on any side is arranged in the front-back direction, and the heating structure on any side is sequentially divided into a front heating section, a middle heating section and a rear heating section from front to back; the arrangement density of the heating structures in the middle heating section is smaller than the arrangement density of the heating structures in the front heating section and the arrangement density of the heating structures in the rear heating section. By adjusting the setting density of the heating structure in the reaction cavity in different areas, the materials in the reaction cavity are heated in a centralized manner, the temperature uniformity of the materials during heating and sintering is improved, and structural defects caused by non-uniform heating are effectively prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field related to alloy manufacturing, and more specifically, relates to a sintering device for improving the temperature uniformity of materials, an application thereof and a design method thereof. Background Art

[0002] High-entropy alloy (HEA) is a new type of alloy material with excellent properties. It is composed of five or more element phases, among which there is no main element. Since the formation of its grid structure comes from the most "disordered" pattern of atoms of each element, the entropy (△S mix ) increases significantly, presenting a lower Gibbs free energy, and is easier to form a stable mixture. Compared with traditional metal bodies, high-entropy alloy blocks have stronger hardness, better wear resistance, corrosion resistance and temperature resistance, and meet the stringent application requirements of high-speed or ultra-high-speed aircraft structural components in the aerospace industry.

[0003] At present, the preparation technologies of high entropy alloy bodies mainly include vacuum melting, mechanical alloying, laser cladding and powder metallurgy. Due to the complex internal composition of high entropy alloy bodies, it is difficult to ensure the uniformity of the block by using methods such as laser cladding, which is very easy to cause structural defects, and requires the addition of chemical agents for pre-treatment, which is costly. Powder metallurgy is a method of using high entropy alloy powder as raw material, pressing and sintering, and finally obtaining a finished product. Through this method, the density of the sintered material is extremely high, and the mechanical properties of the material are good, which is conducive to overcoming the problem of poor uniformity of raw material elements, but the temperature uniformity during sintering can easily affect the quality of the obtained material.

[0004] As a universal heating equipment, muffle furnace is widely used in the hot processing industry due to its low price and convenient operation. However, there are too many alloy inclusions in the high entropy alloy, and the overall temperature uniformity requirement is too high when the material is heated. The existing ordinary muffle furnace and other heating equipment have poor temperature uniformity when sintering the material, and cannot meet the sintering effect. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a sintering device for improving the temperature uniformity of materials, its application and design method, which are used to solve the problem that the temperature uniformity of materials is poor when existing ordinary muffle furnaces and other heating equipment are used to sinter and heat materials, resulting in failure to meet the expected sintering effect.

[0006] To achieve the above object, according to a first aspect of the present invention, there is provided a sintering device for improving the temperature uniformity of materials, comprising a reaction furnace body and a temperature control unit, wherein: the reaction furnace body comprises a reaction chamber and a furnace door, the front side of the reaction chamber is provided with an opening, and the furnace door can be opened and closed and connected to the front side opening of the reaction chamber;

[0007] The temperature control unit includes a heating structure, and the heating structures are respectively provided on the left and right sides of the interior of the reaction chamber, the heating structures on either side are arranged along the front-to-back direction, and the heating structures on either side are divided into a front heating section, a middle heating section and a rear heating section from front to back, and the arrangement density of the heating structures in the middle heating section is respectively less than the arrangement density in the front heating section and the rear heating section.

[0008] According to the sintering device for improving the uniformity of material temperature provided by the present invention, the heating structure on either side includes heating tubes, the heating tubes are distributed in a serpentine shape along the front-to-back direction, and the tube spacing of the heating tubes in the middle heating section is respectively greater than the tube spacing in the front heating section and the rear heating section;

[0009] And / or, the heating structures on the left and right sides are symmetrically arranged, and the front heating section and the rear heating section of the heating structure on either side are symmetrical about the middle heating section.

[0010] According to the sintering device for improving the temperature uniformity of materials provided by the present invention, the reaction furnace body also includes a bottom base, which is arranged inside the reaction chamber and corresponds to the middle of the heating structure in the front-to-back direction, and is used to support and place the sintering material.

[0011] According to the sintering device for improving the temperature uniformity of materials provided by the present invention, the bottom base is configured as a liftable structure, and the lifting range of the bottom base is 0-120 mm.

[0012] According to the sintering device for improving the uniformity of material temperature provided by the present invention, an air inlet is provided at the bottom of the rear side of the reaction chamber, an air outlet is provided at the middle part of the top of the reaction chamber, and a handle is installed on the furnace door;

[0013] The furnace door is connected to a power switch, and the power switch is used to cut off the power of the reaction furnace body when the furnace door is opened, and to turn on the power of the reaction furnace body when the furnace door is closed.

[0014] According to the sintering device for improving the temperature uniformity of materials provided by the present invention, the temperature control unit also includes a temperature monitoring structure, which is inserted into the interior of the reaction chamber and is used to monitor the temperature field inside the reaction chamber and to cut off the power supply of the reaction furnace body when it is monitored that the temperature field inside the reaction chamber exceeds preset requirements.

[0015] According to the sintering device for improving the temperature uniformity of materials provided by the present invention, the heating tube is a graphite heating tube; the diameter of the heating tube is 2.5-3.5 mm, the distance between the tubes of the heating tube in the front heating section and the rear heating section is 15-16 mm, the distance between the tubes of the heating tube in the middle heating section is 40-42 mm; the middle heating section accounts for 50-55% of the length of the heating tube in the front-to-back direction.

[0016] According to a second aspect of the present invention, there is provided an application of a sintering device for improving the temperature uniformity of a material as described in any one of the above items, wherein the sintering device is used for sintering to prepare a high entropy alloy.

[0017] According to a third aspect of the present invention, a design method for a sintering device for improving material temperature uniformity is provided, which is used to design a sintering device for improving material temperature uniformity as described in any one of the above, and the design method comprises:

[0018] According to the temperature uniformity of the material during the sintering reaction in the reaction chamber, the specific setting parameters of the heating structure are optimized to achieve the best temperature uniformity of the material during the sintering reaction in the reaction chamber;

[0019] The temperature uniformity of the material during the sintering reaction in the reaction chamber is specifically evaluated by the material temperature variability coefficient.

[0020] According to the design method of the sintering device for improving the uniformity of material temperature provided by the present invention, the material temperature variability coefficient ε is specifically:

[0021]

[0022] Among them, σ represents the temperature standard deviation of the temperature points on the material, Indicates the average temperature of the temperature points on the material, N indicates the number of temperature points on the material, T i It represents the temperature of the i-th temperature point on the material. The smaller ε is, the higher the temperature uniformity of the material is.

[0023] In general, compared with the prior art, the above technical solutions conceived by the present invention provide a sintering device for improving the uniformity of material temperature, its application and its design method:

[0024] 1. By adjusting the density of the heating structures on both sides of the reaction chamber in different areas, the heating structures are arranged sparsely in the middle section along the front-to-back direction and densely in the front section and the rear section, so that the materials in the reaction chamber can be heated centrally, which is beneficial to improve the temperature uniformity of the materials during heating and sintering, and effectively prevent the structural defects caused by uneven heating, so as to obtain sintered parts such as high-entropy alloy blocks with better performance;

[0025] 2. By using the bottom base, the material placement height can be freely adjusted. Combined with the distribution position of the heating tube inside the reaction chamber, it is beneficial to heat the material from all directions at the same time, making the material heating temperature field more uniform;

[0026] 3. By setting the air inlet and outlet on the reaction chamber, the inert gas atmosphere inside the furnace is ensured, which effectively prevents the oxidation of high entropy alloy metal powder during sintering and ensures the quality of the block;

[0027] 4. By setting the overheating protection, breaking protection and door opening power-off function, the stability of device operation is improved and the safety of staff is protected. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a front view of a sintering device for improving the uniformity of material temperature provided by the present invention;

[0029] Figure 2 It is a side view of a sintering device for improving the uniformity of material temperature provided by the present invention;

[0030] Figure 3 It is a schematic diagram of the arrangement of the heating tube provided by the present invention;

[0031] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0032] 1-heating tube, 2-air outlet, 3-temperature monitoring structure, 4-reaction chamber, 5-material, 6-bottom base, 7-furnace door, 8-handle, 9-furnace plug, 10-air inlet. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] See also Figure 1 and Figure 2, this embodiment 1 provides a sintering device for improving the temperature uniformity of materials, the sintering device includes a reaction furnace body and a temperature control unit, wherein: the reaction furnace body includes a reaction chamber 4 and a furnace door 7, the front side of the reaction chamber 4 is provided with an opening, and the furnace door 7 can be opened and closed and connected to the front opening of the reaction chamber 4;

[0035] The temperature control unit includes a heating structure, and the heating structures are respectively provided on the left and right sides of the interior of the reaction chamber 4. The heating structures on either side are arranged along the front-to-back direction, and the heating structures on either side are divided into a front heating section, a middle heating section and a rear heating section from front to back. The arrangement density of the heating structures in the middle heating section is less than the arrangement density in the front heating section and the rear heating section.

[0036] The heating structure is installed on the inner wall of the reaction chamber 4, and the heating structures are respectively provided on the left and right sides of the reaction chamber 4; the heating structure can be installed and fixed on the reaction chamber 4 by means of structures such as clamps and brackets, and slots can also be provided on the upper and lower walls of the reaction chamber 4, and the top and bottom of the heating structure are fixed by the slots to achieve fixed installation of the heating structure, and grooves can also be provided on the left and right walls of the reaction chamber 4, and the heating structure is fixed by partially embedding the grooves, and the specific fixed installation structure of the heating structure is not limited.

[0037] This embodiment has been found through research that most traditional sintering equipment is heated by equidistant parallel heat pipes, but this can only heat the material basically, and cannot guarantee the overall uniformity of the resulting processed workpiece and the subsequent yield rate. In the experiment, it can be found through measurement that the temperature difference of the sintered material is above 10°C, which is contrary to the requirements of sintering high entropy alloys and other parts (the temperature difference should be stable within 5°C), so the overall uniformity of the resulting processed workpiece and the subsequent yield rate cannot be guaranteed. It is further proposed to adjust and optimize the setting density of the heating structure in different areas to improve the temperature uniformity of the material 5 during heating. This embodiment specifically proposes to set the heating structure relatively sparsely in the middle section along the front-to-back direction, that is, the setting density is relatively small, and to set it relatively densely in the front section and the rear section, that is, the density is relatively high. By adjusting the setting density of the heating structure, the heating power in the middle section is less than the heating power of the front section and the rear section, so that the temperature field distribution inside the reaction chamber 4 during heating can be adjusted, thereby achieving the adjustment of the material temperature uniformity.

[0038] Experimental verification shows that after adjusting the setting density of the heating structure in different regions in the front-to-back direction, this embodiment can effectively improve the temperature uniformity of the material 5 during the sintering heating process, thereby facilitating the realization of the expected sintering effect and improving the performance of the sintered material.

[0039] Furthermore, the heating structures on the left and right sides are symmetrically arranged, and the front heating section and the rear heating section of the heating structure on either side are symmetrical about the middle heating section. The heating structures on the left and right sides of the reaction chamber 4 can be symmetrical with each other, that is, the heating structures on both sides can be set to the same structure and the setting positions on the reaction chamber 4 are consistent; in addition, the heating structures on either side are set to a symmetrical structure at the same time, the front heating section and the rear heating section can be symmetrical about the middle heating section, that is, the front heating section and the rear heating section can be symmetrically arranged on both sides of the middle heating section, and the middle heating section can also be set to a symmetrical structure, which is conducive to improving the uniformity of material temperature.

[0040] In some specific embodiments, reference Figure 2 and Figure 3 The heating structure on either side includes a heating tube 1, which is distributed in a serpentine shape along the front-rear direction, and the tube spacing of the heating tube 1 in the middle heating section is greater than the tube spacing in the front heating section and the rear heating section. The setting density of the heating structure can be adjusted by adjusting the tube spacing, and the structure is simple and easy to adjust.

[0041] Furthermore, this embodiment takes into account that when the existing material heating equipment is sintering the material 5, the material 5 is directly placed at the bottom of the reaction chamber 4, and it is impossible to achieve uniform heating of the bottom area of ​​the material 5. In this way, it is likely to form an alloy body with segregation, non-uniform structure and high residual stress, thereby affecting the performance of materials such as the high entropy alloy block after sintering. It is further proposed that the reaction furnace body also includes a bottom base 6, which is arranged inside the reaction chamber 4 and corresponds to the middle of the heating structure in the front-to-back direction. The bottom base 6 is used to support and place the sintered material 5. The bottom base 6 is arranged at the bottom of the reaction chamber 4, corresponds to the middle part of the heating structure in the front-to-back direction, and is arranged in the middle part of the reaction chamber 4 in the left-right direction.

[0042] In some specific embodiments, the bottom base 6 is set to a liftable structure, and the lifting range of the bottom base 6 is 0-120mm. The height of the bottom base 6 can be freely adjusted up and down at a spacing of 0-120mm, and is used to place the material 5 to be sintered to prevent uneven heating of the material 5. The bottom base 6 can be adjusted up and down to control the placement height of the material 5 to ensure that the bottom of the material 5 is heated, thereby ensuring that the temperature uniformity of the material 5 is the highest. Furthermore, the radius of the bottom base 6 can be set to 90-100mm, which can meet the sintering requirements of most high entropy alloy materials.

[0043] In some specific embodiments, the bottom of the rear side of the reaction chamber 4 is provided with an air inlet 10, and the middle part of the top of the reaction chamber 4 is provided with an air outlet 2; during the entire sintering process, inert gas continuously enters from the air inlet 10, and flows out from the air outlet 2 after the reaction is completed, so as to ensure the inert atmosphere inside the entire reaction chamber 4 to prevent oxidation of the high entropy alloy metal. The reaction inert gas is argon or one or more of other gases required for sintering high entropy alloys.

[0044] The furnace door 7 is provided with a handle 8; the furnace door 7 is connected with a power switch, and the power switch is used to cut off the power supply of the reaction furnace body when the furnace door 7 is opened, and to turn on the power supply of the reaction furnace body when the furnace door 7 is closed. The furnace door 7 is provided with a switch handle 8, which is provided with a door opening power-off function to protect the circuit.

[0045] Furthermore, the temperature control unit also includes a temperature monitoring structure 3, which is inserted into the interior of the reaction chamber 4 and is used to monitor the temperature field inside the reaction chamber 4 and to cut off the power supply of the reaction furnace body when it is monitored that the temperature field inside the reaction chamber 4 exceeds the preset requirements.

[0046] In this embodiment, the temperature control unit is provided with overheating and disconnection protection. When the temperature distribution field detected by the temperature monitoring structure 3 does not meet the preset requirements, for example, when the temperature in the cavity is detected to be higher than the preset temperature threshold, the power supply of the furnace body is automatically disconnected to achieve safety protection. The temperature monitoring structure 3 can set the upper limit temperature in the cavity according to the sintering temperature. When the temperature is too high, the circuit is automatically cut off to ensure the safety of the equipment.

[0047] In some specific embodiments, the heating tube 1 is a graphite heating tube 1, the specific heat capacity and thermal conductivity increase and decrease non-uniformly with the temperature, and the heating effect is excellent; the diameter of the heating tube 1 is 2.5-3.5 mm, the distance between the tubes of the heating tube 1 in the front heating section and the rear heating section is 15-16 mm, and the distance between the tubes of the heating tube 1 in the middle heating section is 40-42 mm; the middle heating section accounts for 50-55% of the length of the heating tube 1 in the front and rear directions, such as Figure 3 The specific configuration parameters of the heating structure can achieve better material temperature uniformity.

[0048] The second embodiment provides an application of a sintering device for improving the temperature uniformity of a material as described in any one of the above, wherein the sintering device is used for sintering and preparing a high entropy alloy. The above sintering device is suitable for sintering and preparing a high entropy alloy, and can achieve good temperature uniformity of the material 5, thereby ensuring the sintering effect and the performance of the alloy product.

[0049] When the sintering device is used to sinter and prepare a high entropy alloy, the preparation of the high entropy alloy also includes the following steps: before sintering any high entropy alloy powder, the furnace body must be evacuated to a vacuum state, and then filled with argon or one or more other gases required for sintering the high entropy alloy at an appropriate rate, and this process is repeated three times. Thereafter, argon or one or more other gases required for sintering the high entropy alloy are introduced at a flow rate of 100 ml / min for 30 minutes to balance the internal pressure of the furnace body with the outside.

[0050] The third embodiment provides a design method for a sintering device for improving the uniformity of material temperature. The design method is used to design any of the above-mentioned sintering devices for improving the uniformity of material temperature. The design method includes:

[0051] According to the temperature uniformity of the material 5 during the sintering reaction in the reaction chamber 4, the specific setting parameters of the heating structure are optimized and designed so that the temperature uniformity of the material during the sintering reaction in the reaction chamber 4 is optimal;

[0052] The temperature uniformity of the material during the sintering reaction in the reaction chamber 4 is specifically evaluated by the material temperature variability coefficient.

[0053] This embodiment proposes to optimize the specific setting parameters of the heating structure directly according to the temperature uniformity coefficient of the material during the sintering reaction, such as the setting form of the heating structure such as the heating tube 1, and the distribution number of the heating structure in the front heating section, the middle heating section and the rear heating section respectively, and the length proportion of the middle heating section in the front-to-back direction of the entire heating structure, so that the material temperature uniformity is better when the material is actually sintering under the specific setting of the heating structure finally determined, so that the designed sintering device can effectively improve the temperature uniformity of the material during sintering, thereby ensuring the sintering effect and improving the performance of the sintered parts.

[0054] It is proposed to evaluate the temperature uniformity of the reaction materials by the material temperature variability coefficient during the sintering reaction. This coefficient is intuitive, can directly reflect the temperature uniformity of the materials, and is easy to calculate and obtain, so that the design method can effectively improve the temperature uniformity of the materials and is easy to carry out.

[0055] Furthermore, the material temperature variability coefficient ε is specifically:

[0056]

[0057] Among them, σ represents the temperature standard deviation of the temperature points on the material, Indicates the average temperature of the temperature points on the material, N indicates the number of temperature points on the material, T iIt represents the temperature of the i-th temperature point on the material. The calculated ε can directly measure the uniformity of the temperature field of the heated material 5. The smaller ε is, the higher the temperature uniformity of the material is.

[0058] Furthermore, the temperature points are selected by the following method, that is, the setting of the temperature points on the material in the design method is specifically as follows: the material is divided into m parts from top to bottom, so that the material is divided into m+1 sections, and n temperature points are arranged on each section, so that N=(m+1)×n; the temperature points on each section can be evenly and symmetrically arranged on the section.

[0059] For example, in some specific embodiments, the entire material is equally divided into 5 parts in the Z-axis direction, and then a total of 6 material sections are intercepted. Temperature observation points are taken at a certain distance from each section, so 1 / 6N material temperature monitoring points are selected on a single section, totaling N temperature detection points. In this way, the temperature data of all points are exported for calculation.

[0060] Furthermore, the design of the sintering device can be carried out by means of actual sintering experiments, sintering simulation or optimization algorithms. In some specific embodiments, an actual sintering experiment can be carried out, by designing different groups of experiments, the setting parameters of the heating structure in different groups of experiments are different, and the actual sintering experiments are carried out under each group of designed heating structure setting parameters, and the actual material temperature variability coefficient under the heating structure setting parameters of the group of designs is obtained; the temperature uniformity of the material under each group of designed heating structure setting parameters is evaluated according to the actual material temperature variability coefficient, and the heating structure setting parameters corresponding to the experiment with the smallest actual material temperature variability coefficient are selected as the final setting parameters. When designing a sintering device through an actual sintering experiment, a material sample can be selected for an actual sintering experiment, wherein the material sample is cross-sectioned and arranged with temperature points according to the above-mentioned temperature point setting method, and a temperature detection element can be set at each temperature point, so that the material temperature variability coefficient can be calculated through the detection results of the temperature detection element.

[0061] In other specific embodiments, sintering simulation can be performed in simulation software, by designing different groups of simulations, the setting parameters of the heating structure in different groups of simulations are different, sintering experiment simulation is performed under each group of designed heating structure setting parameters, and the simulated material temperature variability coefficient under the heating structure setting parameters of the group of designs is obtained; the temperature uniformity of the material under each group of designed heating structure setting parameters is evaluated according to the simulated material temperature variability coefficient, and the heating structure setting parameters corresponding to the simulation with the smallest actual material temperature variability coefficient are selected as the final setting parameters. When designing a sintering device through sintering simulation, the set material sample is arranged with temperature points according to the above-mentioned temperature point setting method, and the temperature data of each temperature point on the material sample can be directly obtained according to the temperature field generated during the simulation process to calculate the material temperature variability coefficient.

[0062] When designing the sintering device by means of actual sintering experiments or sintering simulation, the size parameters of the material sample can be selected according to the specific size of the reaction chamber 4. It has been found that the size of the area with higher temperature uniformity corresponding to the temperature field in the chamber of the reaction chamber 4 of different sizes is different when heated. The area with higher temperature uniformity corresponding to the actual reaction chamber 4 when heated can be simulated, and then the size parameters of the material sample are designed according to the area, so that the size of the material sample is as close to the size of the area as possible. When the material samples are all in the area, the larger size is selected as much as possible, so that the designed heating structure is suitable for the material sample of the larger size, and it is also suitable for the material sample size smaller than the larger size, which is conducive to improving the applicability of materials of different sizes. The size parameters of the material sample can also be set according to the specific application of the material. For example, when sintering to prepare high entropy alloys, the size of the high entropy alloy in the specific application is usually within 22mm in height and 100mm in radius, so the size of the high entropy alloy material sample can be set to 22mm in height and 100mm in radius, so that the designed sintering device is suitable for the size required in most practical applications.

[0063] In other embodiments, the sintering device can also be designed by an optimization algorithm. For example, the setting parameters of the sintering device can be optimized by the response surface method. The response surface method needs to obtain a data set, wherein each data in the data set is specifically a specific setting parameter of the heating structure and a corresponding material temperature variability coefficient. The data set includes multiple data, and the specific setting parameters of the heating structure are different in different data. The target response value in the response surface method is the material temperature variability coefficient, and the variable is the setting parameter of the heating structure. Then, based on the data set, the variable parameters that can obtain the optimal target response value can be optimized by the response surface method. The data in the data set can be obtained by actual sintering experiments or sintering simulations, and the material sample size required for acquisition can be selected according to the above-mentioned material sample size determination method.

[0064] Furthermore, to facilitate the design, the setting parameters of the heating structure in this embodiment, such as the setting form, and the distribution quantity of the heating structure in the front heating section, the middle heating section and the rear heating section, can be determined and selected according to the setting parameters of the commonly used heating structures of the sintering heating device. For example, when the heating structure is a heating tube 1, the tube diameter of the heating tube 1 and the tube spacing in different heating sections can be designed and determined first, so that the unknown variable is only the length proportion of the middle heating section in the heating structure along the front-to-back direction of the entire heating structure, and then the length proportion of the middle heating section can be optimized, which can simplify and accelerate the design process.

[0065] Further, when a bottom base 6 is provided in the sintering device and the bottom base 6 is set as a liftable structure, the design method further includes: optimizing the setting height of the bottom base 6 according to the temperature uniformity of the material when the material is sintered in the reaction chamber 4, so that the temperature uniformity of the material when the material is sintered in the reaction chamber 4 is optimal. It is found through research that the setting height of the material in the reaction chamber 4, that is, the height of the bottom base 6, also has a great influence on the temperature uniformity of the material, so the setting height of the bottom base 6 is also optimized as a design variable. That is, when the parameter design is performed through actual sintering experiments, sintering simulations or optimization algorithms, the parameter variables include not only the setting parameters of the heating structure but also the setting height of the bottom base 6. The setting parameters of the heating structure and the setting height of the bottom base 6 can be optimized and designed simultaneously. Take the parameter design by means of actual sintering experiments as an example: set at least one variable in the setting parameters of the heating structure and the height of the bottom base 6 in different groups of experiments, and finally select the setting parameters of the heating structure and the height of the bottom base 6 in the optimal experiment as the final parameters.

[0066] Taking the optimization design based on response surface methodology as an example, the sintering device with a bottom base 6 is optimized and designed: the adjustment of the height of the bottom base 6 and the configuration of the heating tube 1, that is, the length ratio of the middle heating section in the heating structure along the front-to-back direction in the entire heating structure are analyzed by response surface methodology, where the target response value is the final temperature uniformity of the material, that is, the material temperature variability coefficient. First, a data set is established, and each data in the data set is specifically the configuration of the heating tube 1, the height of the bottom base 6, and the corresponding material temperature variability coefficient; through the sample points, that is, the data set, a model is established by using methods such as multivariate regression analysis, and the variables in this example: A-the height of the bottom base 6 and B-the configuration of the heating tube 1 are fitted with the target response value, and the variance sources are: A, B, AB, A 2 , B 2 , analyze it, and draw a response surface plot. The response surface plot is helpful to visualize the impact of the variables in this example on the target response value and locate the most favorable setting of the two items.

[0067] The optimal setting parameters of the sintering device obtained by the design method are: when the heating structure is set as a heating tube, the diameter of the heating tube 1 is 2.5-3.5mm, the distance between the tubes of the heating tube 1 in the front heating section and the rear heating section is 15-16mm, and the distance between the tubes of the heating tube 1 in the middle heating section is 40-42mm; the middle heating section accounts for 50-55% of the length of the heating tube 1 in the front and rear directions. The height of the bottom base is 20-40mm.

[0068] The purpose of this embodiment is to provide a device for sintering high-uniformity high-entropy alloys based on a muffle furnace, wherein the overall temperature uniformity of the high-entropy alloy material is synergistically improved by optimizing the distribution of the furnace heating tube 1, improving the heating material placement structure, and real-time monitoring of the temperature change in the furnace, which helps to solve the problems of uneven heating and inability to control in real time in existing sintering furnaces. The device for sintering high-uniformity high-entropy alloys based on a muffle furnace of this embodiment is described below through specific examples:

[0069] A device for sintering a high-uniformity high-entropy alloy based on a muffle furnace, the device comprising a reaction furnace body and a temperature control unit, wherein: the reaction furnace body comprises a reaction chamber 4, a furnace door 7, a handle 8, a furnace plug 9, an air inlet 10, an air outlet 2, materials and a bottom base 6, the handle 8 is arranged on the right side of the furnace door 7, the bottom base 6 is used as a reaction table of the material, and is arranged in the middle of the reaction chamber 4, and can be adjusted up and down according to the size of the sintered material, the air inlet 10 is arranged at the back of the reaction chamber 4, and an air outlet 2 is opened at the middle position above, and gas enters from the air inlet 10 and is ejected from the air outlet 2;

[0070] The temperature control unit includes a heating tube 1 and a temperature monitoring structure 3. The heating tube 1 is symmetrically placed on both sides of the reaction chamber 4. The heating tube 1 is arranged at non-equidistant intervals and is set to a special structure that is narrower on the left and right and wider in the middle, so that the temperature of the intermediate material heating area is more uniform. The temperature monitoring structure 3 may include a thermocouple and a controller. Thermocouples may be respectively set at the upper and lower ends of the reaction chamber 4. During heating, the heating tube 1 is turned on to heat the material placed on the bottom base 6 to realize the heating process. When in use, the entrance needs to be blocked with a furnace plug 9 to improve the heating efficiency inside the reaction chamber 4 and extend the service life of the furnace body. The furnace plug 9 can be a graphite block, which is sealed at the entrance of the reaction chamber 4 inside the furnace door 7 when the furnace door 7 is closed.

[0071] In this embodiment, the pipe diameter of the heating tube 1 is 3mm, the front and rear sides are relatively tight, the distance between the tubes is 15.5mm, the middle part is relatively loose, the distance between the tubes is 41mm, and in order to ensure the smoothness of the internal flow, each pipe corner is 3mm rounded. In this embodiment, the heating tube 1 adopts a graphite tube, which exhibits excellent specific heat capacity and thermal conductivity at high temperature, and has a good heating effect. The bottom base 6 adopts a graphite bracket, which can withstand the high temperature environment in the furnace body, and the low thermal conductivity does not affect the heat absorption of the material. The thermocouple adopts a B-type double platinum thermocouple, which can keenly capture temperature changes at high temperatures; if gas is required, the gas enters through the air inlet 10 and is discharged through the air outlet 2; the interior of the reaction chamber 4 is coated with an alumina coating to improve the heating efficiency of the heating tube 1, reduce energy loss during heating, and extend the service life of the furnace body.

[0072] The temperature monitoring structure 3 is used to monitor the temperature change in the furnace in real time, and the controller is used to receive the temperature information obtained by the thermocouple. Once the temperature is too high, the disconnection protection is activated, that is, the on and off of the furnace power switch is controlled. During the sintering process, the block formed by pressing the metal powder is placed on the bottom base 6, and the special heating tube 1 is heated at a specific heating rate to improve the uniformity of the temperature field of the workpiece as a whole and ensure that it is heated evenly. During the whole process, the inert gas continues to enter from the air inlet 10 and flows out from the air outlet 2 to ensure the inert atmosphere inside the furnace body. After sintering is completed, the pressure is unloaded to form a high-entropy alloy with superior performance. Through this embodiment, the problem of uneven sintering of the alloy body in the prior art is solved, and the prepared alloy has higher uniformity and shows good hardness characteristics and tensile strength.

[0073] The specific steps of sintering the high entropy alloy are as follows: first, the metal powder is pressed to prepare a CoCrFeNi metal powder block with a height of 22 mm and a radius of 100 mm. Under the argon component, the prepared raw material is transferred to the bottom base 6 of the reaction chamber 4, and the furnace door 7 is ensured to be closed. Start heating from room temperature (taking 25°C as an example), heat to 100°C at a heating rate of 5°C / min and keep warm for 30 minutes, then continue to heat to 250°C at the same heating rate and keep warm for 60 minutes, then heat to 450°C at the same heating rate and keep warm for 60 minutes, and finally heat to 1200°C at the same heating rate as above, keep warm for 12 hours and then cool naturally. In particular, ventilation should be continued throughout the heating and cooling process to ensure the argon atmosphere in the furnace. Since the whole process adopts the heating method of intermittent heating and insulation, the internal density of the high entropy alloy is good, and there will be no surface warping or internal defects of the block due to rapid heating, and the mechanical properties are excellent.

[0074] In particular, taking into account the size of the raw material, after adjusting the height of the bottom base 6 to 30 mm, the average temperature curve is calculated to be the highest at this time, and the material temperature uniformity is improved by 6%. In particular, unlike the traditional parallel spacing heating tubes 1, under the same conditions, the non-uniform arrangement of the heating tubes 1 in the furnace body improves the material temperature uniformity by nearly 30%. In particular, the present embodiment considers the improvement of the temperature uniformity of the maximum practical material size (radius of 100 mm) of the furnace body, so when the radius of the sintered material is less than 100 mm, the effect is more significant.

[0075] In this embodiment, the distance between the heating tubes 1 on both sides of the reaction furnace cavity is adjusted so that the central material is evenly heated, which can significantly improve the temperature uniformity of the material over a large area; the bottom base 6 can be adjusted in height according to the size of the material to ensure uniform heat absorption at the bottom of the material. The above synergistic effect ensures that the overall temperature field of the material has a good degree of uniformity.

[0076] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A sintering device for improving the uniformity of material temperature, characterized in that: It includes a reaction furnace body and a temperature control unit, wherein: the reaction furnace body includes a reaction chamber and a furnace door, the front side of the reaction chamber is provided with an opening, and the furnace door can be opened and closed and connected to the front opening of the reaction chamber; The temperature control unit includes a heating structure, and the heating structures are respectively provided on the left and right sides of the interior of the reaction chamber, the heating structures on either side are arranged along the front-to-back direction, and the heating structures on either side are divided into a front heating section, a middle heating section and a rear heating section from front to back, and the arrangement density of the heating structures in the middle heating section is respectively less than the arrangement density in the front heating section and the rear heating section.

2. The sintering device for improving the uniformity of material temperature according to claim 1, characterized in that: The heating structure on either side includes heating tubes, the heating tubes are distributed in a serpentine shape along the front-rear direction, and the tube spacing of the heating tubes in the middle heating section is greater than the tube spacing in the front heating section and the rear heating section; And / or, the heating structures on the left and right sides are symmetrically arranged, and the front heating section and the rear heating section of the heating structure on either side are symmetrical about the middle heating section.

3. The sintering device for improving the uniformity of material temperature according to claim 1, characterized in that: The reaction furnace body further comprises a bottom base, which is arranged inside the reaction chamber and corresponding to the middle of the heating structure in the front-to-back direction, and is used for supporting and placing sintering materials.

4. The sintering device for improving the uniformity of material temperature as claimed in claim 3, characterized in that: The bottom base is configured as a liftable structure, and the lifting range of the bottom base is 0-120 mm.

5. The sintering device for improving the uniformity of material temperature according to any one of claims 1 to 4, characterized in that: An air inlet is provided at the bottom of the rear side of the reaction chamber, an air outlet is provided at the middle part of the top of the reaction chamber, and a handle is installed on the furnace door; The furnace door is connected to a power switch, and the power switch is used to cut off the power of the reaction furnace body when the furnace door is opened, and to turn on the power of the reaction furnace body when the furnace door is closed.

6. The sintering device for improving the uniformity of material temperature according to any one of claims 1 to 4, characterized in that: The temperature control unit also includes a temperature monitoring structure, which is inserted into the interior of the reaction chamber and is used to monitor the temperature field inside the reaction chamber and to cut off the power supply of the reaction furnace body when it is monitored that the temperature field inside the reaction chamber exceeds a preset requirement.

7. The sintering device for improving the uniformity of material temperature as claimed in claim 2, characterized in that: The heating tube is a graphite heating tube; the diameter of the heating tube is 2.5-3.5 mm, the distance between the tubes in the front heating section and the rear heating section is 15-16 mm, and the distance between the tubes in the middle heating section is 40-42 mm; the middle heating section accounts for 50-55% of the length of the heating tube in the front-to-back direction.

8. Application of the sintering device for improving the uniformity of material temperature according to any one of claims 1 to 7, characterized in that: The sintering device is used for preparing high entropy alloy by sintering.

9. A design method for a sintering device for improving the uniformity of material temperature, characterized in that: For designing a sintering device for improving the uniformity of material temperature according to any one of claims 1 to 7, the design method comprises: According to the temperature uniformity of the material during the sintering reaction in the reaction chamber, the specific setting parameters of the heating structure are optimized to achieve the best temperature uniformity of the material during the sintering reaction in the reaction chamber; The temperature uniformity of the material during the sintering reaction in the reaction chamber is specifically evaluated by the material temperature variability coefficient.

10. The design method of a sintering device for improving the uniformity of material temperature as claimed in claim 9, characterized in that: The material temperature variability coefficient ε is specifically: Among them, σ represents the temperature standard deviation of the temperature points on the material, It represents the average temperature of the temperature points on the material, N represents the number of temperature points on the material, T i It represents the temperature of the i-th temperature point on the material. The smaller ε is, the higher the temperature uniformity of the material is.

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