Heating chamber structure for small hot isostatic pressing equipment and temperature control method thereof

Abstract

This invention belongs to the field of hot isostatic pressing (HIP) technology, and particularly relates to a heating chamber structure and its temperature control method for a small-scale HIP equipment. The heating chamber structure includes a heating element assembly, a heat insulation assembly, and a temperature measuring element. The heating element assembly includes a coaxially arranged cylindrical sidewall heating element and a disc-shaped lower end cap heating element sealed at its bottom. The sidewall heating element adopts an axially segmented partitioned structure, divided into 2 to 4 independent heating zones along the height direction. Each heating zone is equipped with an independent heating element and a temperature measuring element, and a temperature measuring element is located at the center of the lower end cap heating element. The heat insulation assembly adopts a gradient composite heat insulation structure consisting of a high-temperature reflective layer, a gradient composite heat insulation layer, and a low-temperature sealing layer, arranged sequentially from the inside out. This invention can optimize the temperature uniformity of the thermal field in small-scale HIP equipment and expand the effective loading space, ensuring that the temperature difference throughout the heating chamber is controlled within ±5℃ and increasing the effective loading space ratio to 65-75%.

Description

Technical Field

[0001] This invention belongs to the field of hot isostatic pressing technology, and particularly relates to a heating chamber structure and temperature control method of a small hot isostatic pressing equipment. Background Technology

[0002] Hot isostatic pressing (HIP) is a special processing technique that utilizes the synergistic effect of high temperature and isotropic high pressure to achieve material densification. The process involves placing the product to be processed inside a completely sealed pressure-resistant container, and simultaneously introducing high-pressure gas to uniformly heat the entire system. This subjects the product to equal pressure loads and temperature fields in three-dimensional space, thereby completing the sintering and densification of the internal particles. This technology is a key supporting technology for the preparation of high-performance materials and the research and development of new functional materials in fields such as aerospace, defense, and new energy. It mainly includes two core applications: First, near-net-shape powder metallurgy, in which metal, ceramic or composite powders are loaded into a prefabricated sleeve (the sleeve acts as a mold constraint, and commonly used materials include low-carbon steel, nickel, molybdenum, glass, etc.), and high-purity nitrogen or argon is used as the pressure transmission medium to achieve sintering and integral forming of the powder through a single high-temperature and high-pressure treatment; Second, defect repair and performance improvement of castings, in which heat densification post-treatment is performed on precision castings such as aluminum alloys, titanium alloys, and high-temperature alloys to completely eliminate metallurgical defects such as shrinkage porosity, gas pores, and microcracks inside the castings, significantly improve the density of the material, and ultimately greatly improve the comprehensive mechanical properties of the castings, such as strength, toughness, and fatigue life.

[0003] The uniformity of the thermal field temperature and the effective loading space of hot isostatic pressing (HIP) equipment are crucial technical parameters in its manufacturing. Regarding thermal field temperature uniformity, the temperature difference along the height direction is particularly significant. Uneven temperature directly leads to internal stress in the product, ranging from residual stress to cracks and even scrapping. As for the effective loading space, current mainstream small HIP equipment typically uses a method of lowering the heating elements to cover the entire workpiece area to address the height-direction temperature uniformity issue. While this alleviates the temperature difference along the height direction to some extent, it significantly increases the overall height of the equipment components, reduces the effective loading space, and substantially increases the overall equipment cost.

[0004] On the other hand, the thickness of the thermal insulation components is also a crucial factor affecting the uniformity of the thermal field temperature and the effective loading space of the equipment. To maintain thermal stability and mitigate temperature fluctuations, thermal insulation components are used to construct a high-temperature thermal barrier, ensuring the uniformity of the thermal field temperature throughout the entire process cycle. Currently, the thickness of the thermal insulation components in mainstream small-scale hot isostatic pressing (HIP) equipment is generally too thick, which further compresses the effective loading space in the radial direction. The poor thermal field temperature uniformity and small effective loading space caused by the heating chamber structure of current mainstream small-scale HIP equipment limit its development and application.

[0005] There is currently no effective solution to the problems of poor temperature uniformity and small effective loading space in small hot isostatic pressing equipment. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of the prior art by proposing a heating chamber structure and its temperature control method for small hot isostatic pressing equipment, in order to solve the technical problems of poor uniformity of thermal field temperature, small effective loading space, low process stability and unsatisfactory cost control in the prior art.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows: A heating chamber structure for a small hot isostatic pressing equipment includes a heating element assembly, a heat insulation assembly, and a temperature sensing element; The heating element assembly includes a sidewall heating element and a lower end cap heating element; The sidewall heating element has a cylindrical structure and is coaxially sleeved on the inner side of the heat insulation component in an axial segmented partitioning manner; the sidewall heating element is divided into 2 to 4 independent heating zones along the height direction, and each heating zone is equipped with an independent heating element to achieve precise control of the temperature in the height direction of the heating cavity.

[0008] The lower end cover heating element has a disc-shaped structure and is sealed to the bottom of the side wall heating element to form a cylindrical heating cavity; The temperature sensing element includes a sidewall temperature sensing element disposed in each of the heating zones and a lower end cover temperature sensing element fixedly disposed in the central area of ​​the lower end cover heating body. It is used to detect the temperature at the lower end of the heating cavity in real time, and in conjunction with the zoned temperature control of the sidewall heating body, eliminate the cold end effect at the upper and lower ends of the heating cavity. The sidewall temperature sensing element and the lower end cover temperature sensing element are electrically connected to the temperature control system to form a closed-loop temperature control system. The thermal insulation component adopts a gradient composite thermal insulation structure, which includes a high-temperature reflective layer, a gradient composite thermal insulation layer and a low-temperature sealing layer from the inside to the outside. The heating chamber structure ensures that the effective loading space of the heating chamber accounts for 65-75% of its total internal volume, and the temperature difference throughout the heating chamber is controlled within ±5℃.

[0009] Furthermore, the height of each heating zone is 100-200mm, and a heat insulation gap of 10-20mm is provided between adjacent heating zones to reduce thermal interference between adjacent zones.

[0010] Furthermore, the heating element assembly adopts a spiral or grid structure and is uniformly fixed to the inner wall of the heating zone; the material of the heating element in the heating element assembly is selected according to the highest working temperature of the heating cavity: when the working temperature is ≤1400℃, a molybdenum-lanthanum alloy or a tungsten-rhenium alloy is used; when the working temperature is >1400℃, graphite or C / C composite material is used.

[0011] Furthermore, the high-temperature reflective layer is composed of 2 to 5 layers of molybdenum foil or graphite foil, each layer having a thickness of 0.05 to 0.1 mm, with an air gap of 2 to 3 mm between the layers, used to reflect the infrared radiation heat generated by the heating element and the non-metallic layer inside the heat insulation component.

[0012] Furthermore, the gradient composite insulation layer is composed of 2 to 5 layers of carbon fiber felt or graphite felt, each layer being 5 to 8 mm thick, with staggered splicing between layers to reduce heat conduction paths; the total thickness of the gradient composite insulation layer is 30 to 50 mm, which is 30 to 40% thinner than traditional single-material insulation components under the same thermal resistance conditions.

[0013] Furthermore, the low-temperature sealing layer is made of alumina fiber felt or aluminum silicate fiber felt with a thickness of 10-20 mm, which is used to isolate heat loss in the low-temperature section and ensure the airtightness of the heating chamber.

[0014] Furthermore, the sidewall temperature measuring element disposed in each of the heating zones is located at the axial middle position of the zone, and the lateral distance between it and the corresponding sidewall heating body is 10-15mm; the sidewall temperature measuring element is an armored thermocouple or a tungsten-rhenium thermocouple.

[0015] Furthermore, the effective loading space of the heating chamber has an inner diameter of 0.1–0.3 m and a height of 0.2–1 m. With the heating chamber structure of this invention, the proportion of the effective loading space to the total internal volume of the heating chamber is increased to 65–75%, the temperature difference across the entire heating chamber can be controlled within ±5℃, the operating temperature range is 400–2000℃, and the operating pressure range is 50–200 MPa.

[0016] The present invention also provides a temperature control method for the heating chamber structure of a small hot isostatic pressing equipment, comprising the following steps: S1: Place the workpiece to be processed inside the heating chamber, evacuate and pressurize the medium, and control the side wall heating element and the lower end cover heating element to rise according to the preset process curve. S2: The temperature signal of each heating zone is collected in real time by the side wall temperature measuring element set at the middle position of the axial direction of each heating zone, and the temperature signal of the bottom of the heating cavity is collected in real time by the lower end cover temperature measuring element set in the center area of ​​the lower end cover heating body. S3: The temperature control system receives all temperature signals from the temperature sensing elements and compares and analyzes them with the preset process curve; S4: When the measured temperature of any heating zone is higher than the preset value corresponding to that heating zone, the temperature control system reduces the output power of the heating element of that heating zone; when the measured temperature of any heating zone is lower than the preset value corresponding to that heating zone, the temperature control system increases the output power of the heating element of that heating zone. S5: When the actual measured temperature at the center of the lower end cover is lower than the preset bottom target temperature, the temperature control system will increase the output power of the lower end cover heating element to eliminate the cold end effect at the bottom of the heating cavity. S6: Cool down according to the preset cooling curve. After the pressure inside the furnace drops to normal pressure, take out the workpiece.

[0017] Furthermore, the heating rate in step S1 is 5–10 °C / min; the cooling rate in step S6 is 2–5 °C / min.

[0018] This invention addresses the specific scenario of small-scale hot isostatic pressing (HIP) equipment by proposing a design that combines axial partitioned heating with radial gradient insulation to solve the problems of poor temperature uniformity and limited effective loading space in the heating chamber. The axial heating element employs independent temperature control in segmented sections along the sidewalls, combined with radiative heating from the center of the lower end cover. By dividing the vertical direction into multiple independent heating zones and configuring independent temperature acquisition points, the heat output of each zone is actively adjusted to eliminate the cold-end effect, achieving temperature uniformity in the vertical direction without sacrificing axial loading space. The radial direction is designed with a gradient composite insulation structure, consisting of a high-temperature reflective layer, a gradient composite insulation layer, and a low-temperature sealing layer from the inside out. Through the combined effects of reflection, blocking, and sealing, the total thickness of the insulation layer can be significantly reduced while maintaining the same thermal resistance, thereby freeing up loading space in the radial direction.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The structure of axial segmented and zoned heating of the side wall combined with radiation heat supplementation of the lower end cover can achieve temperature uniformity control in the height direction of the heating chamber without the need for the sinking heating components. The temperature difference in the whole area is ≤±5℃, which effectively avoids residual stress and cracks caused by uneven temperature of the workpiece. At the same time, it avoids the increase in overall equipment height and reduction in loading space caused by the sinking of the heating components.

[0020] (2) The gradient composite insulation structure is used to replace the traditional single material insulation components. Under the premise of ensuring the same insulation effect and thermal field stability, the total thickness of the insulation layer is reduced by 30-40%, which significantly expands the radial loading space of the heating cavity, increases the proportion of effective loading space by 25-35%, and reduces the overall manufacturing cost of the equipment.

[0021] (3) A closed-loop zone temperature control system is adopted. Combined with the arrangement of temperature measuring elements in the middle of each heating zone and the center of the lower end cover, the real-time monitoring and precise adjustment of the temperature of the entire heating cavity are realized, which improves the process stability and product consistency. Attached Figure Description

[0022] The following figures are intended only to illustrate and explain the present invention and do not limit the scope of the invention. Wherein: Figure 1 This is a schematic cross-sectional view of the heating chamber structure of the present invention used in a small hot isostatic pressing equipment; Figure 2 This is a cross-sectional schematic diagram of the heating element assembly of the present invention; Figure 3 This is a schematic diagram of the layered structure of the gradient composite thermal insulation component of the present invention; In the diagram: 1. Effective loading space; 2. Heating element assembly; 201. Side wall heating element; 202. Lower end cover heating element; 3. Heat insulation assembly; 301. High temperature reflective layer; 302. Heat insulation core layer; 303. Low temperature sealing layer; 4. Temperature measuring element. Detailed Implementation

[0023] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

[0024] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] As shown in Figures 1, 2, and 3, the present invention provides a heating chamber structure for a small hot isostatic pressing equipment. The heating chamber structure includes an effective loading space 1, a heating body assembly 2, a heat insulation assembly 3, and temperature measuring elements 4, with multiple temperature measuring elements 4 respectively disposed at corresponding positions of the heating body assembly 2.

[0027] In this invention, the heating element assembly 2 adopts a structure of axial segmented and zoned heating on the side wall combined with heat supplementation by the lower end cover, and the heat insulation assembly 3 adopts a gradient composite heat insulation structure. It can achieve uniform temperature control of the entire heating cavity without the need for settling heating components, while significantly reducing the thickness of the heat insulation layer and effectively expanding the effective loading space of the heating cavity. This fundamentally solves the technical problems of poor thermal uniformity and small loading space in existing small hot isostatic pressing equipment.

[0028] In an optional embodiment of the invention, such as Figure 1 As shown, the effective loading space 1 is a cylindrical structure with an open top and a sealed bottom. The inner diameter of the effective loading space 1 is 0.1 to 0.3 m and the height is 0.2 to 1 m. There is an installation gap of 5 to 20 mm between the effective loading space 1 and the heat insulation component 3, which facilitates the overall disassembly, maintenance and component replacement of the heating chamber structure.

[0029] Furthermore, such as Figure 1 , Figure 2 As shown, the heating element assembly 2 includes a side wall heating element 201 and a lower end cover heating element 202. The side wall heating element 201 has a cylindrical structure and is coaxially sleeved inside the heat insulation assembly 3. The lower end cover heating element 202 has a disc-shaped structure and is correspondingly sealed to the bottom of the side wall heating element 201. The side wall heating element 201 and the lower end cover heating element 202 together enclose a cylindrical effective loading space, which is used to place the workpiece to be processed and the sealing sleeve.

[0030] Specifically, the sidewall heating element 201 adopts an axial segmented partition structure, which is divided into 2 to 4 independent heating partitions along the height direction. The height of each heating partition is 100 to 200 mm. A heat insulation gap of 10 to 20 mm is set between adjacent heating partitions. The heat insulation gap is filled with high-purity argon gas, which can effectively block heat conduction and heat radiation interference between adjacent heating partitions and ensure the independence and accuracy of temperature control of each heating partition.

[0031] In an optional embodiment of the invention, each heating zone is configured independently, and the heating element adopts a spiral or grid structure and is uniformly fixed to the inner wall of the heat insulation component by silicon nitride ceramic or CC composite material connectors.

[0032] Furthermore, the material of the heating element is selected differently according to the maximum operating temperature of the heating chamber: when the maximum operating temperature of the heating chamber is ≤1400℃, the heating element 2 is made of molybdenum-lanthanum alloy or tungsten-rhenium alloy, which has high high-temperature strength, good creep resistance, and a service life of more than 5000 hours; when the maximum operating temperature of the heating chamber is >1400℃, the heating element 2 is made of graphite or C / C composite material, which has excellent high-temperature resistance and can work stably for a long time in high-temperature environments above 2000℃.

[0033] In an optional embodiment of the invention, such as Figure 2 As shown, the outer diameter of the lower end cover heating element 202 is matched with the inner diameter of the side wall heating element 201. A temperature sensing element 4 is embedded in the center of the lower end cover heating element 202 to detect the temperature at the lower end of the heating cavity in real time. With the zoned temperature control of the side wall heating element 201, the cold end effect at the upper and lower ends of the heating cavity can be effectively eliminated, ensuring the temperature uniformity in the height direction of the heating cavity.

[0034] In an optional embodiment of the present invention, as shown in Figures 1 and 3, the heat insulation component 3 adopts a gradient composite heat insulation structure, which includes a high-temperature reflective layer 301, a gradient composite heat insulation layer 302 and a low-temperature sealing layer 303 from the inside to the outside. The high-temperature reflective layer 301 is tightly attached to the outer wall of the heating element component 2, the low-temperature sealing layer 303 is fixed to the outer wall of the heat insulation component 3 by a high-temperature resistant adhesive, and the gradient composite heat insulation layer 302 is filled between the high-temperature reflective layer 301 and the low-temperature sealing layer 303.

[0035] Specifically, the total thickness of the gradient composite insulation layer 302 is 30-50mm. Compared with traditional single-material alumina fiber or graphite felt insulation components, the thickness is reduced by 30%-40% under the same thermal resistance conditions, which can significantly expand the radial loading space of the heating cavity.

[0036] Furthermore, the high-temperature reflective layer 301 is determined according to the operating temperature of the heating cavity: when the operating temperature is ≤1400℃, the high-temperature reflective layer 301 consists of 2 to 5 layers of molybdenum foil; when the operating temperature is >1400℃, the high-temperature reflective layer 301 consists of 2 to 5 layers of graphite foil. The thickness of each molybdenum foil or graphite foil layer is 0.05 to 0.1 mm, and an air gap of 2 to 3 mm is set between the layers, which can reflect more than 90% of infrared radiation heat, greatly reducing radiative heat loss and improving thermal field stability.

[0037] The gradient composite insulation layer 302 is composed of 2 to 5 layers of carbon fiber felt or graphite felt stacked with metal inverted cups. The thickness of each layer of carbon fiber felt or graphite felt is 5 to 8 mm. The layers are spliced ​​in a staggered manner, which can effectively block the heat conduction path and reduce heat conduction loss. The inverted cups are evenly distributed between each layer of insulation felt, which can further reflect infrared radiation heat and form multiple heat insulation barriers.

[0038] The low-temperature sealing layer 303 is made of alumina fiber felt or aluminum silicate fiber felt stacked with stainless steel inverted cups, with a thickness of 10-20mm. It is used to isolate the heat loss of the low-temperature section of the heating chamber, while ensuring the airtightness of the heating chamber and preventing leakage of the pressurized medium from affecting the normal operation of the hot isostatic pressing process.

[0039] In an optional embodiment of the present invention, as shown in Figures 1 and 2, the temperature sensing element 4 is an armored thermocouple or a tungsten-rhenium thermocouple. The temperature sensing element 4 of each heating zone is located at the middle position of the axial direction of the zone, and the distance between the temperature sensing element 4 and the heating element of the corresponding heating zone is 10-15mm. This can accurately detect the actual working temperature of the heating zone and avoid interference of the temperature of the heating element itself on the temperature measurement result.

[0040] In this invention, the small hot isostatic pressing equipment with the above-mentioned heating chamber structure increases the proportion of the effective loading space of the heating chamber to the total internal volume of the heating chamber to 65-75%, which is 25-35% higher than that of traditional small hot isostatic pressing equipment; the temperature difference throughout the heating chamber can be controlled within ±5℃, which can meet the hot isostatic pressing process requirements of various high-performance materials such as powder metallurgy forming and casting densification treatment; the working temperature range of the heating chamber is 400-2000℃, and the working pressure range is 50-200MPa.

[0041] The temperature sensing element 4 of this invention includes a sidewall temperature sensing element disposed in each of the heating zones and a lower end cover temperature sensing element fixedly disposed in the central region of the lower end cover heating body 202; the sidewall temperature sensing element and the lower end cover temperature sensing element are electrically connected to the temperature control system to form a closed-loop temperature control system. The working process of the heating chamber structure of this invention for small hot isostatic pressing equipment is as follows: First, the workpiece to be processed is placed in a metal or ceramic sheath and vacuum-sealed, then placed on a rack inside the heating chamber. The furnace door of the hot isostatic pressing equipment is closed, and the furnace chamber is evacuated to 1×10⁻⁶. -3 Below Pa; then high-purity argon gas is introduced into the effective loading space 1 as a pressurizing medium, and the side wall heating element 201 and the lower end cover heating element 202 are controlled to heat up at a rate of 5 to 10 °C / min according to the preset process curve; During the heating and heat preservation process, each temperature measuring element 4 collects the temperature signal at the corresponding position in real time and transmits it to the temperature control system. The temperature control system adjusts the output power of each heating element component 2 in real time according to the temperature feedback. When the temperature of a certain heating zone is higher than the set value, the output power of the heating element in that zone is reduced. When the temperature is lower than the set value, the output power of the heating element in that zone is increased to ensure that the temperature of the entire heating cavity is uniform and stable. Once the furnace temperature and pressure reach the preset process values, maintain the temperature and pressure for 1 to 10 hours to complete the hot isostatic pressing sintering or densification treatment of the workpiece. Finally, cool down at a rate of 2 to 5℃ / min according to the preset cooling curve. After the furnace temperature drops below 200℃ and the pressure drops to atmospheric pressure, open the furnace door and take out the workpiece.

[0042] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes will be obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A heating chamber structure for a small hot isostatic pressing equipment, comprising a heating element assembly (2), a heat insulation assembly (3), and a temperature sensing element (4), characterized in that, The heating element assembly (2) includes a side wall heating element (201) and a lower end cover heating element (202); The sidewall heating element (201) has a cylindrical structure and is coaxially sleeved on the inner side of the heat insulation component (3) in an axial segmented partitioning manner; the sidewall heating element (201) is divided into 2 to 4 independent heating zones along the height direction, and each heating zone is equipped with an independent heating element; The lower end cover heating element (202) has a disc-shaped structure and covers the bottom of the side wall heating element (201) to form a cylindrical heating cavity; The temperature measuring element (4) includes a side wall temperature measuring element disposed in each of the heating zones and a lower end cover temperature measuring element fixedly disposed in the central area of ​​the lower end cover heating body (202); the side wall temperature measuring element and the lower end cover temperature measuring element are electrically connected to the temperature control system to form a closed-loop temperature control system; The heat insulation component (3) adopts a gradient composite heat insulation structure, which includes a high-temperature reflective layer (301), a gradient composite heat insulation layer (302) and a low-temperature sealing layer (303) from the inside to the outside. The heating chamber structure ensures that the effective loading space of the heating chamber accounts for 65-75% of its total internal volume, and the temperature difference throughout the heating chamber is controlled within ±5℃.

2. The heating chamber structure for a small hot isostatic pressing equipment according to claim 1, characterized in that, The height of each heating zone is 100-200mm, and a heat insulation gap of 10-20mm is provided between adjacent heating zones.

3. The heating chamber structure for a small hot isostatic pressing equipment according to claim 2, characterized in that, The material of the heating element in the heating element assembly (2) is selected according to the highest working temperature of the heating chamber: when the working temperature is ≤1400℃, a molybdenum-lanthanum alloy or a tungsten-rhenium alloy is used; when the working temperature is >1400℃, graphite or C / C composite material is used.

4. The heating chamber structure for a small hot isostatic pressing equipment according to claim 3, characterized in that, The high-temperature reflective layer (301) is composed of 2 to 5 layers of molybdenum foil or graphite foil, each layer having a thickness of 0.05 to 0.1 mm, with an air gap of 2 to 3 mm between the layers.

5. The heating chamber structure for a small hot isostatic pressing equipment according to claim 1, characterized in that, The gradient composite insulation layer is composed of 2 to 5 layers of carbon fiber felt or graphite felt, each layer being 5 to 8 mm thick, and the layers are spliced ​​together in a staggered manner.

6. The heating chamber structure for a small hot isostatic pressing equipment according to claim 5, characterized in that, The low-temperature sealing layer (303) is made of alumina fiber felt or aluminum silicate fiber felt with a thickness of 10-20 mm.

7. The heating chamber structure for a small hot isostatic pressing equipment according to claim 6, characterized in that, The sidewall temperature measuring element disposed in each of the heating zones is located at the axial middle position of the zone and the lateral distance from the corresponding sidewall heating element (201) is 10-15mm; the sidewall temperature measuring element is a sheathed thermocouple or a tungsten-rhenium thermocouple.

8. The heating chamber structure for a small hot isostatic pressing apparatus according to any one of claims 1 to 7, characterized in that, The effective loading space of the heating chamber has an inner diameter of 0.1–0.3 m and a height of 0.2–1 m.

9. A temperature control method for a heating chamber structure for a small hot isostatic pressing equipment based on any one of claims 1 to 8, characterized in that, Includes the following steps: S1: Place the workpiece to be processed inside the heating chamber, evacuate and pressurize the medium, and control the side wall heating element (201) and the lower end cover heating element (202) to heat up according to the preset process curve; S2: The temperature signal of each heating zone is collected in real time by the side wall temperature measuring element set at the middle position of the axial direction of each heating zone, and the temperature signal of the bottom of the heating cavity is collected in real time by the lower end cover temperature measuring element set in the central area of ​​the lower end cover heating body (202). S3: The temperature control system receives all temperature signals from the temperature sensing element (4) and compares and analyzes them with the preset process curve; S4: When the measured temperature of any heating zone is higher than the preset value corresponding to that heating zone, the temperature control system reduces the output power of the heating element of that heating zone; when the measured temperature of any heating zone is lower than the preset value corresponding to that heating zone, the temperature control system increases the output power of the heating element of that heating zone. S5: When the actual measured temperature at the center of the lower end cover is lower than the preset bottom target temperature, the temperature control system increases the output power of the lower end cover heating element (202) to eliminate the cold end effect at the lower end of the heating cavity. S6: Cool down according to the preset cooling curve. After the pressure inside the furnace drops to normal pressure, take out the workpiece.

10. The temperature control method for the heating chamber structure of a small hot isostatic pressing equipment according to claim 9, characterized in that, The heating rate in step S1 is 5–10 °C / min; the cooling rate in step S6 is 2–5 °C / min.

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