Cold isostatic pressing pulse sintering method and cold isostatic pressing pulse sintering device

Abstract

The invention provides a cold isostatic pressing pulse sintering method and a cold isostatic pressing pulse sintering device. The cold isostatic pressing pulse sintering method comprises the steps that a to-be-sintered sample is placed between two heating elements and makes contact with the heating elements, and a sealed sintering unit is obtained after packaging and vacuumizing; and the sintering unit is placed in a cold isostatic pressing environment, and pulse voltage is applied to a heating element in the sintering unit, so that in-situ sintering is conducted on the to-be-sintered sample under the fixed pressure intensity and the vacuum environment through generated joule heat.

Description

Technical Field

[0001] The present disclosure relates to the technical field of material sintering, in particular to the technical field of hot pressing sintering, and more specifically to a cold isostatic pressing pulse sintering method and a cold isostatic pressing pulse sintering device. Background Art

[0002] The sintering process is a key manufacturing technology that heats powder materials to bond their particles and achieve material densification. It is widely used in ceramics, metals, composite materials and other fields. In order to promote effective bonding between powder particles to be sintered and sufficient densification of the material, it is usually necessary to carry out the sintering at a higher ambient temperature, which relies on the surface atoms to obtain sufficient diffusion energy to cross the interface between particles. However, this sintering method that relies on high temperature often leads to long sintering times and difficulty in achieving ideal density for materials with high sintering temperatures or slow atomic diffusion rates, thus limiting the performance and application of the material. To address this problem, ultrafast high-temperature sintering technology has emerged. This technology can achieve rapid local heating, and its heating rate can reach 10 3 ~10 4 ℃ / min, can quickly reach and exceed the sintering temperature of the material, thereby significantly accelerating the solid phase reaction and achieving rapid sintering of the material. However, ultrafast high temperature sintering technology is mainly applicable to atmospheric pressure sintering environment, and has certain restrictions on the types of materials, especially transparent ceramics and other materials that have extremely high requirements for sintering conditions.

[0003] On the other hand, hot pressing sintering technology effectively reduces the sintering temperature by applying axial pressure during the sintering process, usually by 50~200 ℃. However, hot pressing sintering technology also has its limitations, such as complex equipment, high cost, and difficulty in accurately controlling the sintering temperature. In addition, hot pressing sintering requires a large amount of power input during the sintering process, resulting in high energy consumption and low efficiency.

[0004] Therefore, there is still an urgent need to develop a new high-pressure sintering method that is simple in device and easy to operate, which can achieve precise control of the sintering temperature while reducing production costs. Summary of the invention

[0005] In view of this, the main purpose of the present disclosure is to provide a cold isostatic pressing pulse sintering method and a cold isostatic pressing pulse sintering device, in order to at least partially solve at least one of the above-mentioned technical problems.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] In one aspect of the present disclosure, a cold isostatic pressing pulse sintering method is provided, comprising:

[0008] The sample to be sintered is placed between two heating elements and in contact with the heating elements, and a sealed sintering unit is obtained after packaging and vacuuming;

[0009] The sintering unit is placed in a cold isostatic pressing environment, and a pulse voltage is applied to a heating element in the sintering unit to utilize the generated Joule heat to perform in-situ sintering of the sample to be sintered under a fixed pressure and vacuum environment.

[0010] In another aspect of the present disclosure, a cold isostatic pressing pulse sintering device is provided for performing the above method, the device comprising:

[0011] A cold isostatic pressing module, a sintering unit located inside the cold isostatic pressing module, and a power supply module for providing a pulse voltage to the sintering unit;

[0012] Among them, the cold isostatic pressing module includes:

[0013] A cold isostatic pressing chamber, loaded with a heat transfer liquid and a sintering unit located in the heat transfer liquid;

[0014] The pressure head is engaged with the cold isostatic pressing cavity and is used to provide isostatic pressing and is electrically connected to the power supply module and the heating element in the sintering unit through wires;

[0015] An insulating ring is placed on the pressure head to isolate the pressure head from direct contact with the cold isostatic pressing chamber;

[0016] The sintering unit comprises: a sample to be sintered, and heating elements, an insulating layer and a sealing layer are sequentially arranged on both sides of the sample to be sintered as a core.

[0017] According to an embodiment of the present disclosure, a cold isostatic pressing pulse sintering method is provided. The sample to be sintered is contacted with a heating element and vacuum-encapsulated. In a cold isostatic pressing environment, a pulse voltage is applied to the heating element, and the Joule heat generated by the heating element is directly applied to the sample to be sintered. Due to the instantaneous high heat effect of the pulse voltage, the sintering process can be completed in a relatively short time, while effectively maintaining the density and mechanical properties of the material to be sintered, thereby achieving in-situ sintering. In addition, the cold isostatic pressing pulse sintering method in the present disclosure can achieve an efficient sintering process at a relatively low energy consumption, and has superior economy and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural diagram of the cold isostatic pressing pulse sintering device disclosed in the present invention;

[0019] Figure 2 The Li prepared by sintering in Example 1 of the present disclosure 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron micrographs of the materials;

[0020] Figure 3 The Li prepared by sintering in Example 1 and Comparative Examples 1-2 of the present disclosure 6.5 Ln3Z 1.5 Ta 0.5 O 12 Comparison of scanning electron microscope images of the materials;

[0021] Figure 4 The Li prepared by sintering in Example 1 and Comparative Examples 1-2 of the present disclosure 6.5 Ln3Z 1.5 Ta 0.5 O 12 X-ray diffraction pattern of the material;

[0022] Figure 5 This is a scanning electron microscope image of the pure copper metal material prepared by sintering in Example 2 of the present disclosure;

[0023] Figure 6 This is a scanning electron microscope image of the sintered Cu-W-ZrO2 composite material of Example 3 of the present disclosure. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments.

[0025] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this disclosure.

[0026] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0027] As a key manufacturing technology for achieving inter-particle bonding and densification of powder materials by heating, the sintering process plays an important role in many fields such as ceramics, metals, and composite materials. However, existing sintering technologies face many challenges such as sintering temperature, time, and cost. Although ultrafast high-temperature sintering technology can achieve rapid heating and sintering, it is only applicable to normal pressure environments, and the material application range is limited, which makes it difficult to meet the preparation needs of high-demand materials such as transparent ceramics. Although hot pressing sintering technology can apply pressure during the sintering process to reduce the sintering temperature and increase the density of the material, thereby forming a more dense material in a shorter time. However, the hot pressing sintering device is very complex, and the manufacturing and maintenance costs are high, and it is not popular. At the same time, the sintering temperature of hot pressing sintering is difficult to control, and it is necessary to continuously input more than 2000 W of power during the sintering process, which consumes huge energy and has extremely low efficiency.

[0028] In the process of realizing the concept of the present disclosure, it was found that the isostatic pressing environment achieves pressure conditions similar to hot pressing sintering, and the use of high thermal conductivity liquid can achieve high-pressure rapid heat dissipation. In addition, a Joule heating device is constructed by a simple substrate, the material to be sintered is placed in the core Joule heating area, and an insulating layer is added for vacuumization and packaging. The packaged sintering unit is connected to the cold isostatic pressing device, and high-efficiency pulse-type cold isostatic pressing sintering can be achieved by applying a pulse voltage. By utilizing the instantaneous high heat effect of the pulse voltage, in-situ sintering is completed in a short time, effectively maintaining the density and mechanical properties of the material. By precisely controlling the pulse parameters (such as voltage, time, and power, etc.), accurate control of the total heat generation and sintering temperature is achieved, thereby ensuring the stability and consistency of the material sintering process. In addition, this method can achieve efficient sintering at low energy consumption, has significant economic and environmental advantages, and provides new solutions for sintering technology in the fields of ceramics, metals, composite materials, etc.

[0029] According to an embodiment of one aspect of the present disclosure, a cold isostatic pressing pulse sintering method is proposed, comprising:

[0030] The sample to be sintered is placed between two heating elements and in contact with the heating elements, and a sealed sintering unit is obtained after packaging and vacuuming;

[0031] The sintering unit is placed in a cold isostatic pressing environment, and a pulse voltage is applied to a heating element in the sintering unit to utilize the generated Joule heat to perform in-situ sintering of the sample to be sintered under a fixed pressure and vacuum environment.

[0032] According to an embodiment of the present disclosure, a cold isostatic pressing pulse sintering method is provided, in which a sample to be sintered is first brought into close contact with a heating element to ensure that heat can be directly and efficiently transferred to the sample. The contacted sample and heating element are then vacuum packaged to ensure a sealed sintering environment. The packaged sample is placed in a cold isostatic pressing environment to provide a stable pressure for sintering, and a pulse voltage is applied to the heating element, and the Joule heat generated is directly applied to the sample to be sintered. Since the pulse voltage has an instantaneous high heat effect, the sample can be quickly heated to the sintering temperature, thereby completing the sintering process in a relatively short time. At the same time, due to the existence of cold isostatic pressing, the density and mechanical properties of the material to be sintered are effectively maintained, and in-situ sintering is achieved.

[0033] According to the embodiments of the present disclosure, the heating element is selected from conductive heat-generating materials, including any one of carbon paper, nickel-chromium alloy, and manganese-copper alloy. The above materials have excellent electrical conductivity, good thermal stability, and a high melting point to ensure that they can effectively transmit current and generate stable Joule heat during high-temperature sintering, and are not prone to decomposition or reaction. In addition, these materials also have good mechanical strength, can withstand the pressure in the cold isostatic pressing environment, maintain stable shape, and are easy to process into various shapes and sizes, so as to be in close contact with the sample to be sintered.

[0034] According to the embodiments of the present disclosure, during specific implementation, the shape of the heating element can be selected to have a structure that is wide at both ends and narrow in the middle, and the heating element substrate is cut into a specific shape using a laser. Because the resistance is inversely proportional to the cross-sectional area of ​​the heating element, the resistance of the wide parts at both ends is smaller, while the resistance of the narrow part in the middle is larger. When current passes through the heating element, due to the large resistance of the middle part, according to Joule's law, the middle part will generate more heat, so that the heat generated by the heating element is more concentrated in the middle, thereby improving the thermal efficiency and ensuring the uniformity and effectiveness of the heating of the sample during the sintering process.

[0035] According to the embodiments of the present disclosure, in specific implementation, the thickness of the heating element can be 0.01 mm to 99 mm, for example, 0.01 mm, 0.05 mm, 0.1 mm, 0.5 mm, 1 mm, 10 mm, 30 mm, 50 mm, 70 mm, 99 mm, etc., preferably 0.05 mm to 0.9 mm. Thinner heating elements can heat up quickly and reach the required sintering temperature more quickly, thereby shortening the heating time of the sintering process. At the same time, thin heating elements are more sensitive to temperature changes, which is conducive to achieving more precise temperature control and ensuring the stability and consistency of the sintering process.

[0036] According to an embodiment of the present disclosure, applying voltage to a heating element in a sintering unit includes: intermittently applying a pulse voltage. The pulse voltage is 0.01-1000 V, for example, it can be 0.01 V, 0.1 V, 1 V, 100 V, 300 V, 500 V, 700 V, 1000 V, etc. The pulse current is 0.01-1000 A, for example, it can be 0.01 A, 0.1 A, 1 A, 100 A, 300 A, 500A, 700 A, 1000 A, etc. The time for applying the pulse voltage is 0.01-60 s, for example, it can be 0.01 s, 0.05 s, 0.1 s, 0.5 s, 1 s, 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, etc. The intermittent time is 0.01-1200 s, for example, it can be 0.01 s, 0.05 s, 0.1 s, 0.5 s, 1 s, 100 s, 500 s, 700 s, 1000 s, 1200 s, etc. By controlling the pulse parameters, the total heat generation, sintering temperature and sintering time can be effectively controlled, thereby achieving precise control of the sintering process of different materials.

[0037] According to the embodiments of the present disclosure, the pressure of the cold isostatic pressing environment is 0.01~800 MPa, for example, it can be 0.01MPa, 0.1MPa, 1MPa, 100MPa, 300MPa, 500MPa, 800MPa, etc. The upper limit of the pressure applied during the sintering process can reach 800MPa, which can meet the requirements of different materials for sintering pressure and can effectively promote the densification and sintering of materials. The temperature of Joule heat is 100℃~3000℃, for example, it can be 100℃, 300℃, 500℃, 800℃, 1000℃, 1500℃, 2000℃, 2500℃, 3000℃, etc., which can cover the sintering temperature requirements of most materials and ensure that the material can reach the ideal sintering state. The core Joule heat source temperature can reach up to 3000℃, which can meet the demand for high-temperature sintering while ensuring the rapid and efficient sintering process.

[0038] According to an embodiment of the present disclosure, the sample to be sintered includes any one of an inorganic material, a metal material, and a composite material of an inorganic material and a metal material, wherein the inorganic material includes ceramics, glass, etc. The sample to be sintered also includes an organic material or a composite material of any two or more of an organic material, an inorganic material, and a metal material, such as a polymer material. The sintering method of the present disclosure can be applied to the sintering requirements of different materials.

[0039] According to an embodiment of the present disclosure, the sample to be sintered is placed between two heating elements and in contact with the heating elements. Depending on the material type of the sample to be sintered, different placement methods are used to contact with the heating elements.

[0040] Specifically, when the sample to be sintered is an inorganic material, the sample to be sintered is in direct contact with the heating element. When a pulse voltage is applied to the heating element, the generated Joule heat can be directly conducted to the sample to be sintered, so that the heat utilization rate is as high as more than 70%, effectively improving the sintering efficiency.

[0041] When the sample to be sintered is a metal material or a composite material, in order to prevent the metal material and the composite material containing metal from being short-circuited when powered on in the heating element, an insulating layer is provided between the sample to be sintered and the heating element so that the sample to be sintered and the heating element are in indirect contact. The insulating layer material can be selected from insulating materials, such as zirconium dioxide (ZrO2).

[0042] According to an embodiment of the present disclosure, the sintering unit is further provided with: an insulating layer and a sealing layer.

[0043] The insulating layer is located on both sides of the heating element away from the sample to be sintered, and is used to isolate the Joule heat generated by the heating element, ensure that the heat can be concentrated on the sample to be sintered, and prevent local high temperature from damaging the sealing layer. The material of the insulating layer is selected from a low thermal conductivity material with a thermal conductivity lower than 0.12W / (m·K). The material of the insulating layer can be, for example, zirconium dioxide fiber, aluminum oxide fiber, silicon dioxide fiber, etc. The thickness of the insulating layer is 0.01~99 mm, for example, 0.01 mm, 0.1 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 90 mm, 99 mm, etc., preferably 0.1~5 mm.

[0044] The sealing layer is located on both sides of the insulating layer away from the heating element, and is used to encapsulate the insulating layer, the heating element and the sample to be sintered to form a sealed sintering unit. The sealing layer separates the inside of the sintering unit from the outside (such as high thermal conductivity silicone oil), so that the prepared device is in a sealed state. The material of the sealing layer is selected from thermoplastic polymers, such as simple polymer materials such as polypropylene, polyethylene, polyester, etc.

[0045] In a specific implementation, the material to be sintered can be placed between two heating elements, and wires can be arranged at both ends of the heating elements. After placing the insulating layer, the packaging layer can be vacuum-packaged with hot melt adhesive to obtain a sintered unit. The insulating layer can isolate local high temperature to protect the packaging layer.

[0046] According to the embodiments of the present disclosure, in a specific implementation, for example, an oxide-type solid lithium-ion electrolyte sheet can be used as a sample to be sintered and solid-phase sintered. Specifically, cold isostatic pulse sintering of the oxide-type solid lithium-ion electrolyte sheet includes the following steps:

[0047] The raw materials for preparing the oxide-type solid lithium-ion electrolyte are ball-milled for 2 hours using a high-energy ball mill to obtain a precursor of the oxide-type solid lithium-ion electrolyte. The precursor is poured into a mold and pressed to obtain a green material;

[0048] The oxide-type solid lithium-ion electrolyte green material (sample to be sintered) is placed between two heating elements and in contact with the heating elements, and a sealed sintering unit is obtained after packaging and vacuuming;

[0049] The sintering unit is placed in a cold isostatic press, and a pulse voltage is applied to the heating element in the sintering unit to utilize the generated Joule heat to perform in-situ sintering of the sintered sample under a fixed pressure and vacuum environment. The pulse voltage is a fixed voltage, the pulse voltage is 0.01~999 V, the current is 0.01~999 A, the power is 0.01~5000 W, the current is maintained for 0.01~15 s, the interval is 0.01~600 s, and the cold isostatic press is placed with high thermal conductivity silicone oil.

[0050] According to another aspect of the present disclosure, a cold isostatic pressing pulse sintering device is provided for executing the above method. Figure 1 This is a structural diagram of the cold isostatic pressing pulse sintering device disclosed in the present invention.

[0051] like Figure 1 As shown, the cold isostatic pressing pulse sintering device includes: a cold isostatic pressing module, a sintering unit, and a power supply module for providing a pulse voltage to the sintering unit, wherein the sintering unit is located inside the cold isostatic pressing module.

[0052] The cold isostatic pressing module includes: a cold isostatic pressing chamber, a pressing head, and an insulating ring.

[0053] Specifically, a cold isostatic pressing cavity is loaded with a heat-conducting liquid and a sintering unit is located in the heat-conducting liquid; a pressure head is embedded in the cold isostatic pressing cavity and is used to provide isostatic pressing while being electrically connected to a power supply module and a heating element in the sintering unit through wires; an insulating ring is sleeved on the pressure head and is used to isolate the pressure head from direct contact with the cold isostatic pressing cavity; wherein the sintering unit includes: a sample to be sintered, and heating elements, an insulating layer and a sealing layer are sequentially arranged on both sides with the sample to be sintered as the core.

[0054] According to the embodiments of the present disclosure, the power supply module provides a stable pulse voltage to the cold isostatic pressing module, which stimulates the heating element in the cold isostatic pressing module to generate heat, ensuring that the heating element can heat up quickly and evenly. At the same time, the pressure head of the cold isostatic pressing module provides a uniform and controllable isostatic pressure for the cold isostatic pressing cavity, ensuring the stability and uniformity of the sample during the sintering process. Under the dual effects of heat and pressure, the pulse parameters are adjusted to achieve efficient and controllable sintering of the sample to be sintered.

[0055] According to an embodiment of the present disclosure, specifically, the sintering unit includes: a heating element, a heat insulation layer, and a sealing layer.

[0056] The heating element is used to generate Joule heat to sinter the sample to be sintered under the action of the pulse device. The heating element is electrically connected to the pressure head and the pulse module through wires. The sample to be sintered is placed between the two heating elements and is in direct or indirect contact with the two heating elements.

[0057] The heat-insulating layers are respectively arranged on both sides of the two heating elements away from the sample to be sintered, and are used to isolate the Joule heat generated by the heating elements, ensuring that the heat can be concentrated on the sample to be sintered, while preventing local high temperature from causing damage to the sealing layer.

[0058] The sealing layers are respectively arranged on both sides of the two heat-insulating layers away from the heating elements, and are used to encapsulate the insulation layers, the heating elements and the samples to be sintered to form a sealed sintering unit.

[0059] According to the embodiment of the present disclosure, the inside of the pressure head also includes an electrode for connecting the power supply module and the heating element in the sintering unit, and the insulating ring is located at the periphery of the engagement position between the pressure head and the cold isostatic pressing cavity. The electrical contact between the pressure head and the cold isostatic pressing cavity is effectively isolated, current leakage and short circuit are prevented, and the safe operation of the device is ensured.

[0060] According to an embodiment of the present disclosure, one side of the power supply module is electrically connected to the electrode in the pressure head through a conductor such as a silver wire or a copper wire, ensuring that the current can be transmitted from the power supply module to the pressure head part, and the other side of the power supply module is electrically connected to the heating element in the sintering unit through a conductor such as a silver wire or a copper wire, ensuring that the current can be transmitted from the power supply module to the heating element to generate Joule heat, and at the same time, the electrode is electrically connected to the heating element in the sintering unit to ensure the current transmission between the pressure head and the heating element to form a complete electrical circuit. When powered on, a complete electrical circuit is formed inside the cold isostatic pressing pulse sintering device, ensuring that the pulse voltage and the pressurization process can be carried out synchronously, and the device can simultaneously apply a pulse electric field and isostatic pressure to the sample to be tested, thereby achieving efficient and uniform sintering of the sample. Thereby increasing the sintering rate, and improving the density and mechanical properties of the sintered sample.

[0061] According to an embodiment of the present disclosure, specifically, a wire led out from one side of the power supply module penetrates from the side of the press head away from the sintering unit, and is connected to an electrode inside the press head; a wire is led out from the other side of the power supply module, penetrates from the side of the cold isostatic pressing cavity away from the press head, and is connected to one side of a heating element in the cold isostatic pressing cavity; a wire is connected to the other side of the heating element, penetrates from the side of the press head close to the sintering unit, and is connected to an electrode inside the press head, so as to form a complete current loop.

[0062] In order to make the purpose, technical scheme and advantages of the present disclosure clearer, the present disclosure is further described in detail below in conjunction with specific examples and drawings. Specific techniques or conditions not specified in the examples are all conventional methods, which can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. It should be noted that the methods provided in the present disclosure are all conventional methods unless otherwise specified, and the reactants and reagents can be obtained from public commercial channels unless otherwise specified.

[0063] Embodiment 1:

[0064] In this embodiment 1, the ceramic oxide material is sintered according to the following steps:

[0065] According to Li 6.5 LqCy 1.5 Ta 0.5 O 12 The stoichiometric ratio of Li2CO3, La2O3, ZrO2 and Ta2O5 was weighed. The purity of the above reagents was analytically pure, and the amount of Li2CO3 added was 10% excess by mass. The weighed powder was transferred to a high-energy ball mill, and an appropriate amount of anhydrous ethanol was added as a ball milling medium. The mixed powder was ball milled for 8 to 12 hours to obtain a mixed powder. The mixed powder was dried in an oven to obtain Li 6.5 LqCy 1.5 Ta 0.5 O 12 Precursor powder. Weigh 0.1-1 g of the precursor powder and pour it into a mold with an inner diameter of 15 mm. Apply a small pressure and keep it for 1-5 min to obtain a disc-shaped green material with a thickness of 0.8-5 mm.

[0066] The green material is placed between two heating elements and in contact with the heating elements, and a sealed sintering unit is obtained after packaging and vacuuming. The sintering unit is placed in a cold isostatic pressing environment, and a pulse voltage is applied to the heating element in the sintering unit, wherein the pulse voltage is set to 1~30 V, the pulse current is 1~30 A, and the power is 100~900 W. The pulse is applied 1~30 times, with an interval of 20~40 s each time, so as to utilize the generated Joule heat to in-situ sinter the green material under a fixed pressure and vacuum environment to obtain the sintered Li 6.5 LqCy 1.5 Ta 0.5 O 12 Material.

[0067] Comparative Example 1

[0068] In this comparative example 1, the ceramic oxide material is sintered using conventional sintering technology:

[0069] Li 6.5 LqCy1.5 Ta 0.5 O 12 The precursor powder was placed in a cold isostatic press and maintained at 1-200 MPa for 5-10 min to obtain a compacted disc-shaped green material. The temperature was raised to 1200 °C in a muffle furnace at 5 °C / min and sintered for 6 h, followed by natural cooling and annealing.

[0070] Comparative Example 2

[0071] This comparative example 2 uses ultrafast high temperature sintering technology to sinter the ceramic oxide material:

[0072] Li 6.5 LqCy 1.5 Ta 0.5 O 12 The precursor powder is placed in a cold isostatic press and maintained at 1-200 MPa for 5-10 minutes to obtain a compacted disc-shaped green material.

[0073] The disc-shaped green material was sintered by ultrafast high temperature sintering technology at 1000~1200℃ for 5~15s to obtain the sintered Li 6.5 LqCy 1.5 Ta 0.5 O 12 Material.

[0074] The Li prepared by sintering in Example 1 and Comparative Examples 1-2 was observed by scanning electron microscopy. 6.5 LqCy 1.5 Ta 0.5 O 12 Materials for analysis.

[0075] Figure 2 The Li prepared by sintering in Example 1 of the present disclosure 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron microscope image of the material, a is the pulse number of 2 Li 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron microscope image of the material; b is the Li when the pulse number is 5 times 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron microscope image of the material; c is the Li when the pulse number is 9 times 6.5 LqCy 1.5 Ta 0.5 O 12Scanning electron microscope image of the material; d is the Li when the pulse number is 13 times 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron microscope image of the material, e is the relationship between the sintering number and sintering temperature during the sintering process.

[0076] like Figure 2 As shown in Figure 2, with the increase of pulse number, Li 6.5 LqCy 1.5 Ta 0.5 O 12 The density of the material gradually increases. It can be observed that the sintering process of cold isostatic pulse sintering is simple, effective and temperature controllable.

[0077] Figure 3 The Li prepared by sintering in Example 1 and Comparative Examples 1-2 of the present disclosure 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron microscope comparison of materials, a is the Li prepared by sintering in Comparative Example 1 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron microscope image of the material; b is the Li prepared by sintering in Comparative Example 2 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron microscope image of the material; c is the Li prepared by sintering in Example 1 6.5 LqCy 1.5 Ta 0.5 O 12 Scanning electron micrograph of the material.

[0078] like Figure 3 As shown, it can be observed that the material sintered by cold isostatic pressing pulse sintering method has higher density and smaller grain size.

[0079] The Li prepared by sintering in Example 1 and Comparative Examples 1-2 was analyzed by X-ray diffraction. 6.5 LqCy 1.5 Ta 0.5 O 12 The material was subjected to phase structure analysis.

[0080] Figure 4 The Li prepared by sintering in Example 1 and Comparative Examples 1-2 of the present disclosure 6.5 LqCy 1.5 Ta 0.5 O 12 X-ray diffraction pattern of the material.

[0081] like Figure 4 As shown, the Li prepared by sintering in Comparative Example 2 6.5 LqCy 1.5 Ta 0.5 O 12 The material shows a diffraction peak with good crystallinity, which is similar to the cubic phase of Li5La3Ta2O 12 The standard cards correspond one to one, showing a pure cubic garnet phase. Example 1 shows some amorphous characteristics, and the diffraction peaks of the uncrystallized phase are consistent with those of the cubic phase Li5La3Ta2O 12 The standard cards correspond one by one, showing that it is still a cubic garnet phase. This is because the density of the material is higher after cold isostatic pressing pulse sintering, the pores are smaller and more uniform, and Li 6.5 LqCy 1.5 Ta 0.5 O 12 This is caused by partial melting of the grain boundaries of the material.

[0082] Example 2

[0083] In this embodiment 2, the metal material is sintered according to the following steps:

[0084] Weigh 0.1~1g of copper (Cu) metal powder and pour it into a mold with an inner diameter of 8 mm. Apply a small pressure and keep it for 1~5 minutes to obtain a disc-shaped green material with a thickness of 0.8~2 mm.

[0085] The green material and the insulating layer are placed between two heating elements, in indirect contact with the heating elements, and a sealed sintering unit is obtained after packaging and vacuuming; the sintering unit is placed in a cold isostatic pressing environment, and a pulse voltage is applied to the heating element in the sintering unit, with the pulse voltage set to 1~30 V, the pulse current to 1~30 A, and the power to 100~900 W. The pulse is applied 1~30 times, with an interval of 20~40 s each time, so as to utilize the generated Joule heat to in-situ sinter the green material under a fixed pressure and vacuum environment to obtain a sintered pure copper metal material.

[0086] Figure 5 This is a scanning electron microscope image of the pure copper metal material prepared by sintering in Example 2 of the present disclosure.

[0087] like Figure 5 As shown, it can be observed that the pure copper metal particles after sintering are tightly combined, showing an excellent sintering effect on metal materials.

[0088] Example 3

[0089] In this embodiment 3, the metal-ceramic composite material is sintered according to the following steps:

[0090] Copper (Cu) metal powder and tungsten (W) metal powder were weighed and added into a high-energy ball mill, and an appropriate amount of anhydrous ethanol was added as a ball milling medium. The ball milling was performed for 12 hours to obtain a mixed powder. The mixed powder was dried in an oven to obtain a Cu-W precursor powder.

[0091] Weigh 0.1~1 g of Cu-W precursor powder and pour it into a mold with an inner diameter of 8 mm. Apply a small pressure and keep it for 1~5 min to obtain a disc-shaped green material with a thickness of 0.8~2 mm.

[0092] The green material and ZrO2 fiber are arranged between two heating elements, in indirect contact with the heating elements, and a sealed sintered unit is obtained after packaging and vacuuming;

[0093] The sintering unit is placed in a cold isostatic pressing environment, and a pulse voltage is applied to the heating element in the sintering unit, with the voltage set to 1-30 V, the current to 1-30 A, and the power to 100-900 W. The pulse is applied 20-60 times, with an interval of 15-60 seconds each time, so as to utilize the generated Joule heat to in-situ sinter the green material under a fixed pressure and vacuum environment to obtain a sintered Cu-W-ZrO2 composite material.

[0094] Figure 6 This is a scanning electron microscope image of the sintered Cu-W-ZrO2 composite material of Example 3 of the present disclosure.

[0095] like Figure 6 As shown, it can be observed that Cu-W-ZrO2 are fused with each other and sintered densely, showing an excellent sintering effect on the composite material.

[0096] The present disclosure utilizes a heating element in contact with the material to be sintered, and uses high heat capacity materials such as alumina and zirconia as an insulating layer, and obtains a sintering unit after vacuum packaging. The sintering unit is electrically connected to a cold isostatic pressing module to form a loop, and pulse power is applied to achieve in-situ Joule heat generation sintering. The present disclosure changes the working mode of traditional hot pressing sintering, and achieves low-cost, low-power in-situ high-pressure sintering, while the total heat generation and sintering temperature are controllable. The present disclosure can achieve rapid cold isostatic pressing pulse sintering of a variety of materials such as ceramics, metals, and glass, and can be widely used in material screening and sintering.

[0097] The present disclosure also provides a cold isostatic pressing pulse sintering device, which can achieve temperature-controlled cold isostatic pressing sintering at room temperature with low power consumption. The effect of hot pressing sintering is successfully achieved by cold isostatic pressing. The device is highly operable and the process is relatively simple. In addition, the present disclosure also provides a new type of Joule heat generating device, which uses laser cutting to cut the heating element into a structure that is wide at both ends and gradually narrows toward the middle. Joule heat can be generated by connecting a power supply, and combined with the cold isostatic pressing environment, precise control of the material sintering process can be achieved.

[0098] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A cold isostatic pressing pulse sintering method, characterized in that: The cold isostatic pressing pulse sintering method comprises: The sample to be sintered is placed between two heating elements and in contact with the heating elements, and a sealed sintering unit is obtained after packaging and vacuuming; The sintering unit is placed in a cold isostatic pressing environment, and a pulse voltage is applied to the heating element in the sintering unit to utilize the generated Joule heat to perform in-situ sintering on the sample to be sintered under a fixed pressure and vacuum environment.

2. The cold isostatic pulse sintering method according to claim 1, characterized in that: The heating element is selected from conductive heat-generating materials, including any one of carbon paper, nickel-chromium alloy, and manganese-copper alloy.

3. The cold isostatic pulse sintering method according to claim 1, characterized in that: The applying voltage to the heating element in the sintering unit includes: intermittently applying a pulse voltage; Wherein, the pulse voltage is 0.01~1000 V, and the pulse current is 0.01~1000 A; The pulse voltage is applied for a time period of 0.01 to 60 s, and the intermittent time period is 0.01 to 1200 s.

4. The cold isostatic pulse sintering method according to claim 1, characterized in that: The pressure of the cold isostatic pressing environment is 0.01-800 MPa; The temperature of the Joule heat is 100°C to 3000°C.

5. The cold isostatic pulse sintering method according to claim 1, characterized in that: The sample to be sintered includes any one of an inorganic material, a metal material, and a composite material of an inorganic material and a metal material; The sample to be sintered is placed between two heating elements and in contact with the heating elements, comprising: In the case where the sample to be sintered is an inorganic material, the sample to be sintered is in direct contact with the heating element; In the case that the sample to be sintered is a metal material or a composite material, an insulating layer is provided between the sample to be sintered and the heating element so that the sample to be sintered is in indirect contact with the heating element.

6. The cold isostatic pulse sintering method according to claim 1, characterized in that: The sintering unit is also provided with: An insulating layer, located on both sides of the heating element away from the sample to be sintered, and used to isolate the Joule heat generated by the heating element; The sealing layer is located on both sides of the insulating layer away from the heating element and is used to encapsulate the insulating layer, the heating element and the sample to be sintered to form the sealed sintering unit.

7. The cold isostatic pulse sintering method according to claim 6, characterized in that: The material of the insulating layer is selected from materials having a thermal conductivity lower than 0.12 W / (m·K); The thickness of the insulating layer is 0.01~99 mm; The material of the sealing layer is selected from thermoplastic polymers.

8. A cold isostatic pressing pulse sintering device, used to perform the method according to any one of claims 1 to 7, characterized in that: The cold isostatic pressing pulse sintering device comprises: A cold isostatic pressing module, a sintering unit located inside the cold isostatic pressing module, and a power supply module for providing a pulse voltage to the sintering unit; Wherein, the cold isostatic pressing module comprises: A cold isostatic pressing cavity, loaded with a heat-conducting liquid and a sintering unit located in the heat-conducting liquid; A pressure head, engaged with the cold isostatic pressing cavity, used to provide isostatic pressing and electrically connected to the power supply module and the heating element in the sintering unit through wires; An insulating ring, which is sleeved on the pressure head and is used to isolate the pressure head from direct contact with the cold isostatic pressing chamber; The sintering unit comprises: a sample to be sintered, and heating elements, an insulating layer and a sealing layer are sequentially arranged on both sides of the sample to be sintered as a core.

9. The cold isostatic pulse sintering device according to claim 8, characterized in that: The interior of the pressure head also includes electrodes for connecting the power supply module and the heating element in the sintering unit; The insulating ring is located at the engaging position between the pressure head and the cold isostatic pressing cavity.

10. The cold isostatic pressing pulse sintering device according to claim 8, characterized in that: One side of the power supply module is electrically connected to the electrode in the pressure head, and the other side of the power supply module is electrically connected to the heating element in the sintering unit, and the electrode is electrically connected to the heating element in the sintering unit.

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