Online acoustic emission detection test device for damage of aluminum electrolysis cathode carbon block and use method of online acoustic emission detection test device

Abstract

The invention relates to the technical field of aluminum electrolysis cathode carbon block detection, and particularly discloses an online acoustic emission detection test device and method for damage of an aluminum electrolysis cathode carbon block. The device comprises a closed tubular electric furnace, an electrolytic compression device penetrating through an alundum tube in the closed tubular electric furnace, and fastening devices which are symmetrically arranged, the electrolytic compression device is integrated with an acoustic emission device, an upper stainless steel column, an upper graphite pressure head, an isostatic pressing graphite crucible, a lower graphite pressure head and a lower stainless steel column from top to bottom, and is connected with an acoustic emission sensor and a cathode test piece through a waveguide rod. According to the invention, acoustic emission signals in the cathode carbon block damage process can be collected in real time in a high-temperature electrolysis and mechanical loading coupling environment, and online dynamic monitoring of the damage behavior of the cathode carbon block is realized. The method is easy and convenient to operate and reasonable in structure, can truly simulate industrial aluminum electrolysis conditions, remarkably improves the accuracy and reliability of cathode carbon block rupture mechanism research, and has important application value for prolonging the service life of an electrolytic cell and preventing production accidents.

Description

Technical Field

[0001] This invention relates to the field of aluminum electrolysis cathode carbon block detection technology, specifically to an online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage and its usage method. Background Technology

[0002] In the aluminum electrolysis production process, the damage to the cathode carbon block has a crucial impact on production efficiency, product quality, and production costs. Traditional detection methods struggle to monitor the damage to the cathode carbon block in real time and accurately under complex conditions such as high temperature and strong corrosion. Acoustic emission technology, as an effective non-destructive testing method, can capture elastic wave signals generated when internal defects in materials propagate. However, current devices for detecting damage to aluminum electrolysis cathode carbon blocks have many shortcomings, such as unreasonable structural design leading to limited detection accuracy, inability to meet stable detection requirements under high-temperature environments, and complex operation. Therefore, a new type of testing device is urgently needed to solve these problems. Summary of the Invention

[0003] The purpose of this invention is to provide an online acoustic emission testing device and its method for detecting the damage of aluminum electrolysis cathode carbon blocks, so as to realize the real-time and accurate detection of the damage of aluminum electrolysis cathode carbon blocks under high temperature electrochemical environment. This invention solves the technical problem that traditional detection methods cannot monitor carbon block damage under complex working conditions online by integrating acoustic emission dynamic non-destructive testing technology, mechanical loading system and micro aluminum electrolysis device.

[0004] To address the aforementioned technical problems, this invention first provides an online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage, comprising: A closed-tube electric furnace with a corundum tube in the center, and the temperature is controlled by a temperature controller via a thermocouple inside the furnace. An electrolytic compression device, extending through the corundum tube of a closed tubular electric furnace, comprises, from top to bottom: An acoustic emission device is used to emit sound waves. The acoustic emission device is electrically connected to an acoustic emission signal amplifier and an acoustic emission detector. The upper stainless steel column has a stainless steel through hole in the center and a power cathode connection hole on the upper side, which is connected to the cathode of the power supply. The upper graphite pressure head is a stepped cylinder with an upper limit ring on the outside to limit the upper graphite pressure head to the center of the corundum tube, and an upper graphite through hole in the center. An isostatic graphite crucible is used to support a graphitized cathode specimen, which has threaded holes. The lower graphite indenter is a stepped cylinder made of isostatic high-purity graphite, and is fitted with a lower limit ring on the outside to limit the lower graphite indenter to the center of the corundum tube. The lower stainless steel column has a power anode connection hole on its lower side, which is connected to the anode of the power supply. The electrolytic compression device also includes a waveguide rod, which passes through the stainless steel through hole of the upper stainless steel column and the upper graphite through hole of the upper graphite pressure head. The upper end is threadedly connected to the acoustic emission device, and the lower end is threadedly connected to the test piece thread hole of the graphitized cathode test piece. The fastening devices are provided at the upper and lower ends of the closed tube electric furnace, and the two fastening devices are arranged symmetrically. They are used to fix the electrolytic compression device inside the corundum tube of the closed tube electric furnace and to isolate the inside of the closed tube electric furnace from the outside air.

[0005] As some embodiments of the present invention, a universal testing machine is also included for fixing a closed tubular electric furnace; the universal testing machine includes an insulating rubber gasket, a supporting and fixed test platform, an insulating connector, an upper pressure head, and a lower pressure head; the upper pressure head is fixedly provided at the upper end of the universal testing machine, and the insulating rubber gasket is provided below the upper pressure head, the insulating rubber gasket abutting against the acoustic emission device of the electrolytic compression device; the lower pressure head is fixedly provided at the lower end of the universal testing machine, the insulating connector is connected to the lower pressure head, the supporting and fixed test platform is connected to the insulating connector, and the upper part of the supporting and fixed test platform abuts against the lower stainless steel column.

[0006] As some embodiments of the present invention, the acoustic emission device includes a frame, a rubber plug, a spring, an acoustic emission sensor, a sensor clamp, and a clamp base. The frame is cylindrical with a placement hole at the center of the bottom. The sensor clamp is placed in the placement hole and consists of a side wall and a clamp base threaded to the lower side of the side wall. The acoustic emission sensor is placed inside the sensor clamp. The rubber plug is inserted into the upper end of the sensor clamp. The upper end of the spring abuts against the inner top surface of the rubber plug, and the lower end of the spring fixes the acoustic emission sensor against the clamp base. The lower end of the clamp base has a clamp threaded hole, and the upper end of the waveguide rod is threaded to the clamp threaded hole. A slot extends from one side of the placement hole for placing the sensor clamp into the placement hole.

[0007] As some embodiments of the present invention, the fastening device includes a base, a water-cooling ring, a vent ring, a threaded fastening bolt, an O-ring, a fastening screw, and a fastening ring. The base has a central hole and is fixedly mounted on a closed-tube electric furnace using the fastening screw. A water-cooling ring is fixedly mounted on the side of the base away from the closed-tube electric furnace using the fastening screw. Two water passages are provided on the outer side of the water-cooling ring, both of which communicate with an annular liquid channel within the water-cooling ring. A corundum tube passes through the base and extends into the inner annular hole of the water-cooling ring, and is secured by an O-ring between the base and the inner ring of the water-cooling ring. The O-ring achieves a sealed assembly among the three components; the water-cooling ring and the side away from the closed tube furnace are sealed to the venting ring through the O-ring seal. The outer ring of the water-cooling ring and the venting ring is fixedly connected by a fastening ring at the contact point. The outer side of the venting ring is provided with a vent hole that communicates with the inside of the venting ring. The side of the venting ring away from the closed tube furnace is threadedly connected to a threaded fastening bolt. The upper or lower stainless steel column passes through the venting ring and the threaded fastening bolt, and under the action of the O-ring seal clamped between the inner ring of the venting ring and the threaded fastening bolt, the sealed assembly among the three components is achieved.

[0008] As a preferred embodiment of the present invention, the sensor fixture sidewall is also provided with wire grooves and heat dissipation grooves.

[0009] As a preferred embodiment of the present invention, three heat dissipation holes are drilled on the side of the frame to protect the acoustic emission sensor.

[0010] As a preferred embodiment of the present invention, the bottom of the frame has a frame limiting groove that matches the upper stainless steel column, which facilitates fixed connection.

[0011] As a preferred embodiment of the present invention, the acoustic emission device employs a high-temperature sensor.

[0012] As a preferred embodiment of the present invention, an upper ring vent hole is opened around the upper limit ring, and a lower ring vent hole is opened around the lower limit ring; the arrangement of the upper ring vent hole and the lower ring vent hole is conducive to the air circulation inside the corundum tube.

[0013] As some embodiments of the present invention, a corundum sheet is also placed at the bottom of the isostatic graphite crucible for insulation, and the upper end of the corundum sheet is in contact with the bottom of the graphitized cathode specimen; a graphite crucible limiting groove matching the upper end of the lower graphite pressure head is opened at the lower end of the isostatic graphite crucible.

[0014] As a preferred embodiment of some embodiments of the present invention, the lower end of the lower graphite pressure head is provided with a lower graphite limiting groove that matches the lower stainless steel column.

[0015] As a preferred embodiment of the present invention, in order to make the fixed connection more stable, a V-groove is provided on the inner side of the fastening ring, and an inclined surface is provided at the contact point between the water cooling ring and the venting ring to cooperate with the V-groove to compress the O-ring between the water cooling ring and the venting ring, thereby enhancing the sealing effect while strengthening the stability of the fixed connection.

[0016] As a preferred embodiment of the present invention, in order to facilitate assembly, fastening handles are symmetrically provided on the outer side of the threaded fastener.

[0017] As a preferred embodiment of the present invention, the upper end of the insulating connector is provided with a protrusion, and the lower end is machined with an insulating connection limiting groove that matches the pressing head.

[0018] As a preferred embodiment of the present invention, the upper end of the support and fixing test platform is provided with an upper limit groove that matches the lower stainless steel column, and the lower end of the support and fixing test platform is provided with a lower limit groove that matches the protrusion of the insulating connector.

[0019] As a preferred embodiment of the present invention, mounting handles are welded to both sides of the support and fixing test platform to facilitate device installation.

[0020] The vent is used to introduce protective gas into the corundum tube to maintain the inert environment inside the closed tube furnace. The water-cooling ring protects the O-ring seal from high-temperature failure.

[0021] Since O-rings and fastening screws are common standard mechanical parts, their specific use and selection are common knowledge for those skilled in the art. Therefore, they are uniformly numbered in this embodiment. However, this does not mean that the O-rings and fastening screws used are the same model. The specific model used is selected according to the implementation requirements.

[0022] The corundum tube serves as the main body of the furnace, resistant to high-temperature corrosion, and forms a closed electrolysis space inside. The temperature control system monitors the furnace temperature in real time via thermocouples, with a temperature range of room temperature to 1200℃.

[0023] As a preferred embodiment of the present invention, the power supply has an operating voltage of 0-30V and an operating current of 0-10A, and has a constant current and constant voltage control mode.

[0024] As a preferred embodiment of the present invention, the diameter of the upper stainless steel through hole is 10 mm, and the depth of the power cathode connection hole is 15 mm.

[0025] As a preferred embodiment of the present invention, the upper graphite indenter is made of isostatic high-purity graphite, and the diameter of the upper graphite through hole is 8mm.

[0026] As a preferred embodiment of the present invention, the graphitized cathode specimen has a specification of φ30mm*60mm, and the specimen threaded hole is an M6 internal threaded hole with a depth of 25mm.

[0027] As a preferred embodiment of the present invention, the power supply anode connection hole is 15mm deep.

[0028] As a preferred embodiment of the present invention, the waveguide rod is made of 304 stainless steel with a diameter of 6mm, and has an M6 standard thread with a length of 10mm machined at its upper end and an M6 standard thread with a length of 25mm machined at its lower end.

[0029] As a preferred embodiment of some embodiments of the present invention, the frame is a cylindrical steel column with a placement hole diameter of 30mm and a depth of 100mm.

[0030] As a preferred embodiment of some embodiments of the present invention, the clamp threaded hole is an M6 internal threaded hole with a depth of 10mm.

[0031] As a preferred embodiment of the present invention, the depth of the upper limit groove of the test platform, the lower limit groove of the test platform, the insulating connection limit groove, the frame limit groove, the graphite crucible limit groove and the lower graphite limit groove are all 3mm.

[0032] As a preferred embodiment of the present invention, the acoustic emission device can withstand an operating temperature of up to 200°C.

[0033] As a preferred embodiment of some embodiments of the present invention, the acoustic emission detector is a PCI-II type acoustic emission detector.

[0034] As a preferred embodiment of the present invention, the corundum sheet has a diameter of 55mm and a thickness of 5mm, and is made of 99% ceramic alumina.

[0035] As a preferred embodiment of the present invention, the insulating connector is made of polytetrafluoroethylene.

[0036] This invention also discloses a method for online acoustic emission detection of aluminum electrolysis cathode carbon block damage using the above-mentioned aluminum electrolysis cathode carbon block damage test device, the steps of which are as follows: S1. Specimen preparation: The cathode carbon block is processed into a cylindrical standard specimen according to the test standard. A threaded hole is machined at the center of the top of the specimen to obtain a graphitized cathode specimen. S2. Electrolyte preparation: The electrolyte is made by mixing the following components evenly in parts by weight: 95 parts electrolyte for aluminum electrolysis plants, 5 parts cryolite, 10 parts lithium fluoride, and 10 parts aluminum oxide. S3. Equipment assembly: First, install the closed tube furnace into the universal testing machine, install the lower fastening device, the lower graphite indenter and the lower stainless steel column, then install the graphitized cathode specimen at the lower end of the waveguide rod and place it in the isostatic graphite crucible, then install the upper graphite indenter, the upper stainless steel column and the acoustic emission device in sequence, and finally install the upper fastening device. S4. Parameter Adjustment: Conduct a lead-breaking test outside the enclosed tubular electric furnace. By observing the lead-breaking signal parameters, initially set the acoustic emission acquisition parameters PDT, HDT, and HLT. Set the preamplifier amplification factor, acoustic emission threshold, sampling rate, and sampling length. Based on the attenuation of the acoustic emission signal and taking into account the influence of environmental noise, set the signal gain. Set the frequency range of the digital filter. S5. Room temperature pre-experiment: A room temperature pre-experiment is conducted using a test graphitized cathode specimen, and acoustic emission signals are collected to check whether the test is proceeding normally and whether the acoustic emission signal collection is normal; at the same time, the airtightness of the closed tube furnace is tested. S6. Add electrolyte. First, place a corundum sheet at the bottom of the isostatic graphite crucible, then place the graphitized cathode specimen. Next, pour the well-mixed electrolyte evenly around the graphitized cathode specimen through a funnel. Then, use crucible tongs to clamp the inner wall of the isostatic graphite crucible and carefully and steadily place it into the corundum tube, so that the bottom of the isostatic graphite crucible and the lower graphite pressure head are fixed through the limiting groove of the graphite crucible. S7. Lead breakage test: Before the test equipment is heated, the lead breakage test is performed again to check whether the acoustic emission device signal acquisition is normal. After that, the tube furnace is sealed and heated. During this period, nitrogen is introduced and the airtightness of the device is checked at all times. Cold water is introduced to protect the O-ring seal from heat dissipation. S8. Electrolysis Test: After the temperature rises to the test temperature, continue to keep it at that temperature. After the holding period, connect a constant current power supply. Connect the negative terminal of the power supply to the cathode connection hole of the upper stainless steel column and the positive terminal to the anode connection hole of the lower stainless steel column to form a miniature aluminum electrolysis system. In this system, the graphitized cathode specimen acts as the cathode and the isostatic graphite crucible acts as the anode. Then, the electrolysis test is carried out. After the corresponding electrolysis time is reached, the power supply is cut off and a uniaxial loading test is carried out. The acoustic emission signal generated by the graphitized cathode specimen during the loading process is collected simultaneously during the experiment. S9. Post-experiment treatment: After the carbon block is damaged, immediately stop the acquisition of acoustic emission signals and stop the heat preservation of the closed tube furnace. Let it cool down naturally, and then close the nitrogen valve after it has cooled down.

[0037] Compared with the prior art, the beneficial effects of this invention are as follows: it introduces aluminum electrolysis environment and acoustic emission detection into the mechanical testing of cathode carbon blocks, which is simple to operate and can more realistically simulate the service conditions of cathode carbon blocks in the aluminum electrolysis environment. It is used to detect the evolution law of their mechanical characteristics and acoustic emission characteristic parameters in the aluminum electrolysis environment, providing technical parameters and theoretical basis for the cathode health detection of aluminum electrolysis cells, helping to extend the service life of cathode carbon blocks and aluminum electrolysis cells, and reduce electrolysis cell damage accidents. It is especially suitable for promotion and application in carbon product-related enterprises and research institutions.

[0038] 1. Realistic simulation of the coupling effect of electrolysis environment and mechanical load: This invention is the first to organically combine acoustic emission dynamic detection technology, high-temperature electrolysis system and mechanical loading system, which can highly reproduce the actual working conditions of aluminum electrolysis (high temperature, corrosive electrolyte, current loading) in the laboratory, realize real-time and online monitoring of the damage behavior of cathode carbon block under complex service conditions, and significantly improve the authenticity and reliability of detection.

[0039] 2. High-Temperature Adaptability and Structural Optimization: The device employs a corundum tube furnace, a high-temperature acoustic emission sensor, a water-cooled sealing structure, and graphite components to ensure stable operation in high-temperature (up to 1200℃) and highly corrosive environments. The waveguide rod conduction design effectively mitigates signal attenuation, and combined with heat dissipation and ventilation structures, extends equipment lifespan and improves signal quality.

[0040] 3. Convenient operation and high integration: The device features a modular design and a clear assembly process. It is equipped with a universal testing machine to achieve integrated operation of mechanical loading and electrochemical experiments. It can calibrate acoustic emission parameters in real time through lead breakage testing, and supports pre-experiments and multiple repeated experiments, which significantly improves experimental efficiency and data consistency.

[0041] 4. Comprehensive data and in-depth analysis: It can simultaneously collect multiple acoustic emission parameters (event count, ring count, S value, RA-AF, etc.) and mechanical response data, revealing the influence of electrolysis time on carbon block strength, crack propagation mechanism and fracture mode, providing rich and accurate experimental evidence for the study of cathode carbon block damage evolution mechanism.

[0042] 5. Possesses significant promotional and application value: This invention is not only applicable to basic research on cathode material damage behavior by scientific research institutions, but also provides key technical means for aluminum electrolysis production enterprises to assess cathode health status and predict lifespan, which has important engineering application value for reducing electrolytic cell operation accidents and improving production efficiency. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a three-dimensional structural diagram of the testing apparatus according to an embodiment of the present invention; Figure 2 This is a cross-sectional structural schematic diagram of the electrolytic compression device, the closed tube furnace, the fastening device, and the graphitized cathode specimen according to an embodiment of the present invention. Figure 3 for Figure 2Enlarged view of a portion of point A in the middle; Figure 4 for Figure 2 Enlarged view of a portion of point B in the middle; Figure 5 for Figure 2 Enlarged view of a portion of point C in the middle; Figure 6 This is a three-dimensional structural diagram of the upper fastening device according to an embodiment of the present invention; Figure 7 This is a three-dimensional structural diagram of the lower fastening device according to an embodiment of the present invention; Figure 8 This is a three-dimensional structural diagram of the electrolytic compression device according to an embodiment of the present invention; Figure 9 for Figure 8 Enlarged view of a portion of point D; Figure 10 Stress-strain curves and peak compressive strength curves under different electrolysis durations; Figure 11 Acoustic emission strain-stress-ringing count-cumulative ringing count under different electrolysis durations; Figure 12 The number of acoustic emission events under different electrolysis durations; Figure 13 Characteristics of acoustic emission S-values ​​of graphitized cathode carbon blocks under different electrolysis durations; Figure 14 RA-AF core density diagram of graphitized carbon blocks under different electrolysis times; Figure 15 The percentage of shear cracks under different electrolysis durations.

[0045] The labels in the attached diagram are as follows: 1. Universal testing machine; 11. Insulating rubber gasket; 12. Support and fixing test platform; 121. Upper limit groove of the test platform; 122. Lower limit groove of the test platform; 123. Installation handle; 13. Insulating connector; 131. Protrusion; 132. Insulating connection limiting groove; 14. Upper pressure head; 15. Lower pressure head; 2. Electrolytic compression device; 21. Acoustic emission device; 211. Frame; 2111. Placement hole; 2112. Groove; 2113. Heat dissipation hole; 2114. Frame limiting groove; 212. Rubber plug; 213. Spring; 214. Acoustic emission sensor; 215. Sensor fixture; 2151. Wire groove; 2152. Heat dissipation groove; 216. Fixture base; 2161. Fixture threaded hole; 22. Upper stainless steel column; 221. Power supply cathode connection hole; 22 2. Upper stainless steel through hole; 23. Waveguide rod; 24. Upper graphite pressure head; 241. Upper limit ring; 2411. Upper ring vent hole; 242. Upper graphite through hole; 25. Isostatic graphite crucible; 251. Corundum sheet; 252. Graphite crucible limiting groove; 26. Lower graphite pressure head; 261. Lower limit ring; 2611. Lower ring vent hole; 262. Lower graphite limiting groove; 27. Lower stainless steel Column; 271, Power supply anode connection hole; 3, Closed tube furnace; 31, Corundum tube; 4, Fastening device; 41, Base; 42, Water cooling ring; 421, Water passage hole; 43, Vent ring; 431, Vent hole; 44, Threaded fastener; 441, Fastening handle; 45, O-ring seal; 46, Fastening screw; 47, Fastening ring; 5, Graphitized cathode specimen; 51, Specimen threaded hole. Detailed Implementation

[0046] To make the technical means, creative features, objectives and effects of this invention easier to understand, the technical solutions in the specific embodiments of this invention are described clearly and completely below to further illustrate this invention. Obviously, the specific embodiments described are only a part of the embodiments of this invention, and not all of them.

[0047] Example 1: This embodiment discloses an online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage, such as... Figures 1-9 As shown, it includes: The closed tubular electric furnace 3 has a corundum tube 31 in the center, and the temperature is controlled by a temperature controller via a thermocouple inside the furnace. Universal testing machine 1 is used to fix the closed tube electric furnace 3. In this embodiment, universal testing machine 1 adopts the material mechanics testing machine CMT5504, Shenzhen Xin Sansi Group Co., Ltd. The electrolytic compression device 2, which runs through the corundum tube 31 of the closed tubular electric furnace 3, includes, from top to bottom: Acoustic emission device 21 is used to emit sound waves. Acoustic emission device 21 is electrically connected to an acoustic emission signal amplifier (not shown in the accompanying drawings of this embodiment) and an acoustic emission detector (not shown in the accompanying drawings of this embodiment). The upper stainless steel column 22 has a 10mm diameter upper stainless steel through hole 222 in the center and a 15mm deep power cathode connection hole 221 on the upper side. The power cathode connection hole 221 is connected to the cathode of the power supply (not shown in the attached figure of this embodiment). The upper graphite pressure head 24 is a stepped cylinder made of isostatic high-purity graphite. An upper limit ring 241 is fitted on the outside to limit the upper graphite pressure head 24 to the center of the corundum tube 31. An upper graphite through hole 242 with a diameter of 8mm is opened in the center. An isostatic graphite crucible 25 is used to support a graphitized cathode specimen 5. The graphitized cathode specimen 5 has a specification of φ30mm*60mm and a specimen threaded hole 51 is opened on it. The specimen threaded hole 51 is an M6 internal threaded hole with a depth of 25mm. The lower graphite pressure head 26 is a stepped cylinder made of isostatic high-purity graphite, and a lower limiting ring 261 is fitted on the outside to limit the lower graphite pressure head 26 to the center of the corundum tube 31. The lower stainless steel column 27 has a 15mm deep power anode connection hole 271 on its lower side, which is connected to the anode of the power supply (not shown in the attached drawings of this embodiment). The electrolytic compression device 2 also includes a waveguide rod 23, which is made of 304 stainless steel and has a diameter of 6mm. The upper end of the waveguide rod is machined with an M6 standard thread with a length of 10mm, and the lower end is machined with an M6 standard thread with a length of 25mm. The waveguide rod 23 passes through the stainless steel through hole 222 of the upper stainless steel column 22 and the upper graphite through hole 242 of the upper graphite pressure head 24. The upper end is threadedly connected to the acoustic emission device 21, and the lower end is threadedly connected to the test specimen threaded hole 51 of the graphitized cathode test specimen 5. Fastening devices 4 are provided at the upper and lower ends of the closed tube electric furnace 3. The two sets of fastening devices 4 are arranged symmetrically to fix the electrolytic compression device 2 inside the corundum tube 31 of the closed tube electric furnace 3, and to isolate the inside of the closed tube electric furnace 3 from the outside air.

[0048] The universal testing machine 1 also includes an insulating rubber pad 11, a support and fixed test platform 12, an insulating connector 13, an upper pressure head 14, and a lower pressure head 15. The upper pressure head 14 is fixedly installed at the upper end of the universal testing machine 1, and the insulating rubber pad 11 is installed below the upper pressure head 14. The insulating rubber pad 11 abuts against the acoustic emission device 21 of the electrolytic compression device 2. The lower pressure head 15 is fixedly installed at the lower end of the universal testing machine 1. The insulating connector 13 is connected to the lower pressure head 15, and the support and fixed test platform 12 is connected to the insulating connector 13. The upper part of the support and fixed test platform 12 abuts against the lower stainless steel column 27.

[0049] To facilitate the fixed connection of the device, in this embodiment, the insulating connector 13 is made of polytetrafluoroethylene, and has a protrusion 131 at the upper end and a 3mm deep insulating connection limiting groove 132 at the lower end that matches the lower pressure head 15; the upper end of the support and fixing test platform 12 has a 3mm deep upper limit groove 121 that matches the lower stainless steel column 27, and the lower end of the support and fixing test platform 12 has a 3mm deep lower limit groove 122 that matches the protrusion 131 of the insulating connector 13; installation handles 123 are also welded on both sides of the support and fixing test platform 12 to facilitate the installation of the device.

[0050] The acoustic emission device 21 includes a frame 211, a rubber plug 212, a spring 213, an acoustic emission sensor 214, a sensor clamp 215, and a clamp base 216. The frame 211 is a cylindrical steel column with a placement hole 2111 of 30mm diameter and 100mm depth drilled at the center of its bottom. The sensor clamp 215 is disposed in the placement hole 2111 and consists of a side wall and a clamp base 216 threadedly connected to the lower side of the side wall. The acoustic emission sensor 214 is disposed in the sensor clamp 215. The rubber plug 212... 12 is inserted into the upper end of the sensor clamp 215, the upper end of the spring 213 abuts against the inner top surface of the rubber plug 212, and the lower end of the spring 213 abuts the acoustic emission sensor 214 against the clamp base 216 to achieve fixation; the lower end of the clamp base 216 has a clamp threaded hole 2161, which is an M6 internal threaded hole with a depth of 10mm. The upper end of the waveguide rod 23 is threadedly connected to the clamp threaded hole 2161, and the placement hole 2111 extends to one side to form a slot 2112 for placing the sensor clamp 215 into the placement hole 2111.

[0051] Due to the special nature of its operation, the acoustic emission device 21 needs to use a high-temperature sensor. In this embodiment, an acoustic emission device 21 that can withstand a maximum operating temperature of 200°C is used.

[0052] The sensor fixture 215 also has a wire groove 2151 and a heat dissipation groove 2152 on its side wall.

[0053] The frame 211 has three heat dissipation holes 2113 drilled on its side to protect the acoustic emission sensor 214.

[0054] The bottom of the frame 211 has a 3mm deep frame limiting groove 2114 that matches the upper stainless steel column 22, which facilitates fixed connection.

[0055] The upper limit ring 241 has upper ring vent holes 2411 around its perimeter, and the lower limit ring 261 has lower ring vent holes 2611 around its perimeter. The upper ring vent holes 2411 and lower ring vent holes 2611 are designed to facilitate air circulation within the corundum tube 31.

[0056] A corundum sheet 251 is also placed at the bottom of the isostatic graphite crucible 25 for insulation. The upper end of the corundum sheet 251 is in contact with the bottom of the graphitized cathode specimen 5. A 3mm deep graphite crucible limiting groove 252 matching the upper end of the lower graphite pressure head 26 is opened at the lower end of the isostatic graphite crucible 25.

[0057] The corundum sheet 251 has a diameter of 55mm and a thickness of 5mm, and is made of 99% ceramic alumina.

[0058] The lower graphite pressure head 26 has a 3mm deep lower graphite limiting groove 262 at its lower end, which matches the lower stainless steel column 27.

[0059] Fastening device 4 includes a base 41, a water-cooling ring 42, a vent ring 43, a threaded fastener 44, an O-ring 45, a fastening screw 46, and a fastening ring 47. The base 41 has a central hole and is fixedly mounted on the closed-tube electric furnace 3 by the fastening screw 46. The water-cooling ring 42 is fixedly mounted on the side of the base 41 away from the closed-tube electric furnace 3 by the fastening screw 46. Two water holes 421 are provided on the outer side of the water-cooling ring 42, both of which communicate with an annular liquid channel inside the water-cooling ring 42. A corundum tube 31 passes through the base 41 and extends into the inner annular hole of the water-cooling ring 42, and the O-ring 45, which clamps between the base 41 and the inner annular hole of the water-cooling ring 42, achieves a sealed assembly. The side of the water-cooling ring 42 away from the closed-tube electric furnace 3 is sealed to the vent ring 43 by the O-ring 45. The water-cooling ring 42 and the venting ring 43 are connected by a fastening ring 47 on the outer ring of the contact point. To make the connection more stable, a V-groove is opened on the inner side of the fastening ring 47. The water-cooling ring 42 and the venting ring 43 have a bevel that cooperates with the V-groove to compress the O-ring 45 between the water-cooling ring 42 and the venting ring 43, thereby enhancing the stability of the connection and the sealing effect. The outer side of the venting ring 43 has a vent hole 431 that communicates with the inside of the venting ring 43. The side of the venting ring 43 away from the closed tube electric furnace 3 is threadedly connected to a threaded fastening bolt 44. The upper stainless steel column 22 or the lower stainless steel column 27 passes through the venting ring 43 and the threaded fastening bolt 44, and under the action of the O-ring 45 clamped between the inner ring of the venting ring 43 and the threaded fastening bolt 44, the three are sealed together.

[0060] Vent 431 is used to introduce protective gas into the corundum tube 31. Water cooling ring 42 protects O-ring 45.

[0061] For better assembly, fastening handles 441 are symmetrically provided on the outer side of the threaded fastener 44.

[0062] Since the O-ring 45 and fastening screw 46 are common standard mechanical parts, their specific use and selection are common knowledge for those skilled in the art. Therefore, they are uniformly numbered in this embodiment. However, this does not mean that the O-ring 45 and fastening screw 46 used are the same model. The specific model used is selected according to the implementation requirements. For example, in this embodiment, three different sizes of O-ring 45 are used for sealing in the three sealing locations of the fastening device 4, and different lengths of fastening screw 46 are also used in the two locations.

[0063] Example 2: This example discloses the method of using the online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage described in Example 1, as follows: S1. Specimen Preparation: In this embodiment, the graphitized cathode carbon block currently used in the aluminum electrolysis industry was selected, which was sourced from Wanji Holding Group Graphite Products Co., Ltd. The cathode carbon block was processed according to the test standards to form a standard cylindrical specimen with dimensions of Φ30mm×60mm. A 25mm deep M6 thread was machined at the center of the top, resulting in a graphitized cathode specimen 5 with a threaded hole 51.

[0064] S2. Preparation of electrolyte: The electrolyte used in this embodiment is made by mixing the following components evenly: 95 grams of electrolyte for aluminum electrolysis plants, 5 grams of cryolite, 10 grams of lithium fluoride, and 10 grams of aluminum oxide.

[0065] S3. Equipment Assembly: According to the structure in Example 1, first install the closed tube furnace 3 into the universal testing machine 1, then install the lower fastening device 4, the lower graphite indenter 26, and the lower stainless steel column 27. Then install the graphitized cathode specimen 5 onto the waveguide rod 23 and place it in the isostatic graphite crucible 25. Next, install the upper graphite indenter 24, the upper stainless steel column 22, and the acoustic emission device 21 in sequence. Finally, install the upper fastening device 4.

[0066] S4. Parameter Adjustment: A lead-breaking test was first conducted outside the enclosed tubular electric furnace 3. By observing the lead-breaking signal parameters, the acoustic emission acquisition parameters were determined to be 50μs for PDT, 120μs for HDT, and 200μs for HLT. The preamplifier gain was set to 40dB, and the acoustic emission threshold was also set to 40dB. The sampling rate was set to 1MSPS, and the sampling length was set to 2k. Through multiple lead-breaking tests at different locations on the graphitized cathode specimen 5 and the waveguide rod 23, it was found that the acoustic emission signal attenuated by approximately 8dB to 10dB after transmission through the waveguide rod. Considering the influence of environmental noise, an 8dB signal gain was ultimately set in the acquisition settings to reduce the impact of signal attenuation by the waveguide rod.

[0067] S5. Preliminary Experiment at Room Temperature: A preliminary experiment was conducted first. Analysis showed that the elastic wave signal generated by the breakage of the carbon block mainly concentrated in the frequency range of 100kHz to 300kHz. To more accurately collect the acoustic emission signal generated by the breakage of the carbon block, we set the frequency range of the digital filter to 0 to 400kHz. In this way, noise signals with frequencies higher than 400kHz can be effectively filtered out, ensuring the accuracy and reliability of the experimental data.

[0068] Considering the complexity of the experimental setup and the high-temperature environment, each test requires disassembly and reassembly. To improve reliability, a pre-test using a graphitized cathode specimen 5 at room temperature is conducted before each experiment. After installation, a uniaxial loading test with a loading rate of 0.1 mm / min is performed, while simultaneously acquiring acoustic emission signals to check for proper test execution and signal acquisition. While checking the acoustic emission and testing equipment, the airtightness of the sealed tubular furnace 3 is tested. The nitrogen valve is opened, and nitrogen is introduced at a rate of 0.15 L / min. The outlet of the gas pipe is inserted into a beaker containing soapy water, and bubble formation is observed to verify the airtightness of the experimental setup. After confirming everything is normal, the graphitized cathode specimen 5 used for the formal test is then installed.

[0069] S6. Add electrolyte. First, place a 5mm thick 99% ceramic alumina corundum sheet 251 at the bottom of the isostatic graphite crucible 25 to provide insulation. Then, manually position the graphitized cathode specimen 5, making it as centered as possible. Next, pour the well-mixed electrolyte evenly around the graphitized cathode specimen 5 through a funnel. Then, use crucible tongs to clamp the inner wall of the isostatic graphite crucible 25 and carefully and steadily place it into the corundum tube 31, so that the bottom of the isostatic graphite crucible 25 and the lower graphite pressure head 26 are fastened and fixed through the graphite crucible limiting groove 252.

[0070] S7. Lead Breakage Test: Before heating the test equipment, a lead breakage test is performed again to check if the signal acquisition of the acoustic emission device 21 is normal. After confirming that there are no problems, the closed tube furnace 3 heats up at a rate of 4.5℃ / min, while nitrogen gas is introduced at a rate of 0.15L / min. The airtightness of the device is checked at all times to reduce the impact of oxidation on the test and protect the test equipment. At the same time, cold water is introduced to dissipate heat and protect the O-ring seal 45.

[0071] S8. Electrolysis Test: After the temperature reaches the test temperature of 950℃, the test is continued at this temperature for 2 hours. After the holding period, a 10A constant current power supply is connected. The negative terminal of the power supply is connected to the cathode connection hole 221 of the upper stainless steel column 22, and the positive terminal is connected to the anode connection hole 271 of the lower stainless steel column 27, thus forming a miniature aluminum electrolysis system. In this system, the graphitized cathode specimen 5 acts as the cathode, and the isostatic graphite crucible 25 acts as the anode. The electrolysis current density is approximately 0.23A / cm³. 2 ~0.35A / cm 2 Electrolysis tests were then conducted. After the required electrolysis time was reached, the power was cut off, and a uniaxial loading test was performed. Simultaneously, acoustic emission signals generated by the graphitized cathode specimen 5 during the loading process were collected.

[0072] S9. Post-experiment processing: After the carbon block is damaged, immediately stop the acquisition of acoustic emission signals and stop the heat preservation of the closed tube furnace 3, allowing it to cool down naturally. When the temperature drops to around 250℃, at which point the graphite and oxygen will hardly react, the nitrogen valve can be turned off.

[0073] from Figure 10 , 11 As shown in 12, the aluminum electrolysis environment affects the number of acoustic emission events and the ringing count of cathode carbon block breakage. As the electrolysis time increases, the number of acoustic emission events gradually decreases, and the ringing count also decreases accordingly.

[0074] from Figure 13 It can be seen that the evolution law of acoustic emission S value of cathode carbon block under load and failure is similar under different electrolysis durations. Specifically, the S value is low and fluctuates slightly during the compaction stage, rises rapidly during the elastic stage, and remains at a medium-high level with slight fluctuations during the stable crack propagation stage and the unstable crack propagation stage. When the carbon block fails and becomes unstable, the S value rises rapidly.

[0075] from Figure 14 , 15 It can be seen that the proportion of shear cracks gradually decreases during the fracture process of graphitized cathode carbon blocks.

[0076] The main technical features, basic principles, and related advantages of the present invention have been described above. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the concept or basic characteristics of the invention. Therefore, the above-described embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

[0077] Furthermore, it should be understood that although this specification describes various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage, characterized in that, Including: A closed tube electric furnace (3) is provided with a corundum tube (31) in the center, and the temperature is controlled by a temperature controller through a thermocouple inside the furnace; The electrolytic compression device (2) extends through the corundum tube (31) of the closed tubular electric furnace (3) and comprises, from top to bottom: Acoustic emission device (21) is used to emit sound waves. Acoustic emission device (21) is electrically connected to acoustic emission signal amplifier and acoustic emission detector. The upper stainless steel column (22) has an upper stainless steel through hole (222) in the center and a power cathode connection hole (221) on the upper side, which is connected to the cathode of the power supply. The upper graphite pressure head (24) is a stepped cylinder with an upper limit ring (241) on the outside for limiting the upper graphite pressure head (24) to the center of the corundum tube (31), and an upper graphite through hole (242) is opened in the center. An isostatic graphite crucible (25) is used to support a graphitized cathode specimen (5), and the graphitized cathode specimen (5) has a specimen thread hole (51). The lower graphite pressure head (26) is a stepped cylinder made of isostatic high-purity graphite. A lower limiting ring (261) is fitted on the outside to limit the lower graphite pressure head (26) to the center of the corundum tube (31). The lower stainless steel column (27) has a power anode connection hole (271) on its lower side, which is connected to the anode of the power supply. The electrolytic compression device (2) also includes a waveguide rod (23), which passes through the stainless steel through hole (222) of the upper stainless steel column (22) and the upper graphite through hole (242) of the upper graphite pressure head (24). The upper end is threadedly connected to the acoustic emission device (21), and the lower end is threadedly connected to the test specimen thread hole (51) of the graphitized cathode test specimen (5). Fastening devices (4) are provided at the upper and lower ends of the closed tube electric furnace (3). The two fastening devices (4) are arranged symmetrically to fix the electrolytic compression device (2) inside the corundum tube (31) of the closed tube electric furnace (3) and to isolate the inside of the closed tube electric furnace (3) from the outside air.

2. The online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage according to claim 1, characterized in that, It also includes a universal testing machine (1) for fixing a closed tube electric furnace (3); the universal testing machine (1) includes an insulating rubber pad (11), a support and fixing test platform (12), an insulating connector (13), an upper pressure head (14) and a lower pressure head (15); the upper end of the universal testing machine (1) is fixedly provided with an upper pressure head (14), and the upper pressure head (14) is provided with an insulating rubber pad (11) below the upper pressure head (14), and the insulating rubber pad (11) abuts against the acoustic emission device (21) of the electrolytic compression device (2); the lower end of the universal testing machine (1) is fixedly provided with a lower pressure head (15), the lower pressure head (15) is connected to an insulating connector (13), the insulating connector (13) is connected to a support and fixing test platform (12), and the upper part of the support and fixing test platform (12) abuts against the lower stainless steel column (27).

3. The online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage according to claim 2, characterized in that, The acoustic emission device (21) includes a frame (211), a rubber plug (212), a spring (213), an acoustic emission sensor (214), a sensor clamp (215), and a clamp base (216). The frame (211) is cylindrical, with a placement hole (2111) drilled at the center of the bottom. The sensor clamp (215) is located inside the placement hole (2111). The sensor clamp (215) consists of a side wall and a clamp base (216) threadedly connected to the lower side of the side wall. The acoustic emission sensor (214) is located inside the sensor clamp (215). A rubber plug (212) is inserted into the upper end of the sensor clamp (215), and the upper end of the spring (213) abuts against the inner top surface of the rubber plug (212). The lower end of the spring (213) abuts the acoustic emission sensor (214) against the clamp base (216) to achieve fixation. The lower end of the clamp base (216) has a clamp threaded hole (2161). The upper end of the waveguide rod (23) is threadedly connected to the clamp threaded hole (2161). The placement hole (2111) extends to one side to form a slot (2112) for placing the sensor clamp (215) into the placement hole (2111).

4. The online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage according to claim 3, characterized in that, The fastening device (4) includes a base (41), a water-cooling ring (42), a venting ring (43), a threaded fastener (44), an O-ring (45), a fastening screw (46), and a fastening ring (47). The base (41) has a round hole in the middle and is fixedly installed on the closed tube furnace (3) by the fastening screw (46). The water-cooling ring (42) is fixedly installed on the side of the base (41) away from the closed tube furnace (3) by the fastening screw (46). The water-cooling ring (42) has two water holes (421) on the outside. Both water holes (421) are connected to the annular liquid channel opened in the water-cooling ring (42). The corundum tube (31) passes through the base (41) and extends into the inner ring hole of the water-cooling ring (42), and is clamped between the base (41) and the inner ring of the water-cooling ring (42) by the O-ring. The O-ring (45) achieves the sealing assembly between the three components; the water cooling ring (42) and the side away from the closed tube electric furnace (3) are sealed and connected to the ventilation ring (43) through the O-ring (45); the outer ring of the water cooling ring (42) and the ventilation ring (43) is fixedly connected by the fastening ring (47) at the contact point; the ventilation ring (43) is provided with a ventilation hole (431) communicating with the inside of the ventilation ring (43); the side of the ventilation ring (43) away from the closed tube electric furnace (3) is threadedly connected to the threaded fastening bolt (44); the upper stainless steel column (22) or the lower stainless steel column (27) passes through the ventilation ring (43) and the threaded fastening bolt (44), and under the action of the O-ring (45) clamped between the inner ring of the ventilation ring (43) and the threaded fastening bolt (44), the sealing assembly between the three components is achieved.

5. The online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage according to claim 4, characterized in that, The sensor fixture (215) also has wire grooves (2151) and heat dissipation grooves (2152) on its side wall; The frame (211) has three heat dissipation holes (2113) drilled on its side to protect the acoustic emission sensor (214); The bottom of the frame (211) has a frame limiting groove (2114) that matches the upper stainless steel column (22); The acoustic emission device (21) uses a high-temperature sensor.

6. The online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage according to claim 5, characterized in that, The upper limit ring (241) has an upper ring vent hole (2411) around its perimeter, and the lower limit ring (261) has a lower ring vent hole (2611) around its perimeter. A corundum sheet (251) is also placed at the bottom of the isostatic graphite crucible (25) for insulation. The upper end of the corundum sheet (251) is in contact with the bottom of the graphitized cathode specimen (5). A graphite crucible limiting groove (252) matching the upper end of the lower graphite pressure head (26) is opened at the lower end of the isostatic graphite crucible (25). The lower graphite pressure head (26) has a lower graphite limiting groove (262) that matches the lower stainless steel column (27) at its lower end.

7. The online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage according to claim 6, characterized in that, The inner side of the fastening ring (47) has a V-groove, and the contact point between the water cooling ring (42) and the venting ring (43) has an inclined surface that cooperates with the V-groove to compress the O-ring (45) between the water cooling ring (42) and the venting ring (43); the outer side of the threaded fastening bolt (44) is symmetrically provided with fastening handles (441).

8. The online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage according to claim 7, characterized in that, The upper end of the insulating connector (13) is provided with a protrusion (131), and the lower end is machined with an insulating connection limiting groove (132) that matches the lower pressure head (15); the upper end of the support and fixed test platform (12) is provided with an upper limit groove (121) that matches the lower stainless steel column (27), and the lower end of the support and fixed test platform (12) is provided with a lower limit groove (122) that matches the protrusion (131) of the insulating connector (13); the two sides of the support and fixed test platform (12) are also welded with installation handles (123).

9. The online acoustic emission detection test device for aluminum electrolysis cathode carbon block damage according to claim 8, characterized in that, The diameter of the upper stainless steel through hole (222) is 10mm, and the depth of the power cathode connection hole (221) is 15mm; The upper graphite indenter (24) is made of isostatic high-purity graphite, and the diameter of the upper graphite through hole (242) is 8mm. The graphitized cathode specimen (5) has a specification of φ30mm*60mm, and the specimen threaded hole (51) is an M6 internal threaded hole with a depth of 25mm; The power supply anode connection hole (271) is 15mm deep; The waveguide rod (23) is made of 304 stainless steel with a diameter of 6mm. Its upper end is machined with an M6 standard thread with a length of 10mm, and its lower end is machined with an M6 standard thread with a length of 25mm. The frame (211) is a cylindrical steel column, and the placement hole (2111) is 30mm in diameter and 100mm deep; The fixture threaded hole (2161) is an M6 internal threaded hole with a depth of 10mm; The depth of the upper limit groove (121), lower limit groove (122), insulation connection limit groove (132), frame limit groove (2114), graphite crucible limit groove (252) and lower graphite limit groove (262) of the test platform is 3mm. The acoustic emission device (21) can withstand a maximum operating temperature of 200℃; The corundum sheet (251) has a diameter of 55mm and a thickness of 5mm, and is made of 99% ceramic alumina; The insulating connector (13) is made of polytetrafluoroethylene.

10. A method for using the online acoustic emission detection test apparatus for aluminum electrolysis cathode carbon block damage as described in claim 9, characterized in that, The steps are as follows: S1. Specimen preparation: The cathode carbon block is processed into a cylindrical standard specimen according to the test standard. A specimen thread hole (51) is machined at the center of the top to obtain a graphitized cathode specimen (5). S2. Electrolyte preparation: The electrolyte is made by mixing the following components evenly in parts by weight: 95 parts electrolyte for aluminum electrolysis plants, 5 parts cryolite, 10 parts lithium fluoride, and 10 parts aluminum oxide. S3. Equipment assembly: First, install the closed tube electric furnace (3) into the universal testing machine (1), install the lower fastening device (4), the lower graphite indenter (26), and the lower stainless steel column (27), then install the graphitized cathode specimen (5) at the lower end of the waveguide rod (23) and place it in the isostatic graphite crucible (25), then install the upper graphite indenter (24), the upper stainless steel column (22), and the acoustic emission device (21) in sequence, and finally install the upper fastening device (4). S4. Parameter Adjustment: Conduct a lead breakage test outside the closed tube furnace (3). Preliminarily set the acoustic emission acquisition parameters PDT, HDT and HLT by observing the lead breakage signal parameters. Set the preamplifier amplification factor, acoustic emission threshold value, sampling rate and sampling length. Based on the attenuation of the acoustic emission signal and taking into account the influence of environmental noise, set the signal gain. Set the frequency range of the digital filter. S5. Room temperature pre-experiment: A test graphitized cathode specimen (5) is used to conduct a room temperature pre-experiment. Acoustic emission signals are collected at the same time to check whether the test is carried out normally and whether the acoustic emission signal collection is normal. At the same time, the airtightness of the closed tube furnace (3) is checked. S6. Add electrolyte. First, place a corundum sheet (251) at the bottom of the isostatic graphite crucible (25), then place the graphitized cathode specimen (5), and then pour the mixed electrolyte evenly into the surrounding area of ​​the graphitized cathode specimen (5) through a funnel. Then, use crucible tongs to clamp the inner wall of the isostatic graphite crucible (25) and carefully and steadily place it into the corundum tube (31). Let the bottom of the isostatic graphite crucible (25) and the lower graphite pressure head (26) be fastened and fixed through the graphite crucible limiting groove (252). S7. Lead breakage test: Before the test equipment is heated, the lead breakage test is performed again to check whether the signal acquisition of the acoustic emission device (21) is normal. After that, the tube furnace (3) is closed and heated. During this period, nitrogen is introduced and the airtightness of the device is checked at all times. Cold water is introduced to protect the O-ring seal (45) from heat dissipation. S8. Electrolysis test: After the temperature rises to the test temperature, continue to keep it warm. After the heat preservation stage, connect the constant current power supply. The negative terminal of the power supply is connected to the power cathode connection hole (221) of the upper stainless steel column (22), and the positive terminal is connected to the power anode connection hole (271) of the lower stainless steel column (27). This constitutes a micro aluminum electrolysis system. In this system, the graphitized cathode specimen (5) acts as the cathode, and the isostatic graphite crucible (25) acts as the anode. Then, the electrolysis test is carried out. After the corresponding electrolysis time is reached, the power supply is cut off and a uniaxial loading test is carried out. The acoustic emission signal generated by the graphitized cathode specimen (5) during the loading process is collected simultaneously during the experiment. S9. Post-experiment treatment: After the carbon block is broken, immediately stop the acquisition of acoustic emission signals and stop the heat preservation of the closed tube furnace (3) to allow it to cool down naturally. After cooling down, close the nitrogen valve.

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