High compressive strength prebaked anode and its production process

Abstract

The application provides a high-pressure-resistant prebaked anode, which comprises the following raw materials: 68-85 parts by mass of calcined petroleum coke particles; 12-25 parts by mass of a modified coal-tar pitch binder, the modified coal-tar pitch binder having a softening point of 105-115 DEG C; and 0.3-0.8 parts by mass of a whisker reinforcing agent. The production process comprises the following steps: a calcination process, a crushing and grading process, a fine powder modification process, a binder preparation process, a kneading process, a molding process and a baking process. The application has the advantages that, through multi-level material cooperation and process innovation, the core contradictions of insufficient strength, deteriorated conductivity and poor high-temperature stability of the prebaked anode are solved simultaneously without changing the existing production line.

Description

Technical Field

[0001] This invention belongs to the field of metal materials technology, specifically relating to a high compressive strength prebaked anode and its production process. Background Technology

[0002] As a core component of aluminum electrolysis cells, prebaked anodes are carbon materials produced by high-temperature calcination using petroleum coke as aggregate and coal tar pitch as binder. Their performance directly determines the current efficiency and energy consumption level of aluminum electrolysis production. In modern large-scale prebaked electrolysis cells, the operating current typically ranges from 160 to 500 kA, and the anode must continuously withstand the dual effects of a 950°C high-temperature environment and a 0.8-1.2 MPa mechanical load. These harsh conditions place higher demands on the anode's mechanical strength, conductivity, and thermal stability.

[0003] However, existing commercial prebaked anode products face three key technical defects: First, the interfacial bonding strength between petroleum coke particles and coal tar pitch is insufficient. During roasting, the difference in their thermal expansion coefficients leads to thermal stress concentration, causing microcracks to initiate and propagate. This keeps the product's compressive strength at a level of 32-35 MPa for a long time, resulting in frequent corner fractures during the electrolytic cell start-up phase. Second, the aggregate gradation design in traditional formulations neglects the influence of fine powder activity. The filling rate of fine powder with a particle size of less than 1 mm is less than 40%, which not only reduces the product's bulk density to 1.52-1.55 g / cm³ but also exacerbates high-temperature creep. Under continuous load at 900℃, the anode deformation rate exceeds 2×10⁻⁻⁻⁻⁻⁶. 4 s⁻¹, causing an imbalance in the current distribution of the electrolytic cell. Third, existing enhancement and modification technologies involve serious performance trade-offs. For example, while adding carbon nanotubes can increase compressive strength by 20%, the thickening effect increases kneading energy consumption by 35% and reduces the yield of green anodes. On the other hand, the solution of incorporating silicon micropowder causes the resistivity to rise to over 65 μΩ·m due to its insulating properties, which is significantly higher than the industry safety threshold of 60 μΩ·m.

[0004] To address these challenges, recent technological developments have primarily focused on two directions: Regarding material composition, some researchers have attempted to use boron carbide-modified asphalt binders, but this increases the cost by 120,000 yuan per ton of modifier and requires a kneading temperature exceeding 190℃, leading to an 8% increase in coal tar coking. Other studies have used gradation optimization to adjust the coarse-to-medium particle ratio to 2.6:2.0, but the lack of treatment of oxygen-containing functional groups on the surface of fine powder creates gas release channels during the roasting stage, forming closed pores with a diameter exceeding 50μm. In terms of process improvement, foreign designs utilize multi-stage kneading processes, but the temperature control accuracy requirement of ±1℃ makes implementation extremely difficult. Still others have proposed ultra-high temperature roasting above 1150℃, which, while increasing strength by 3MPa, results in a doubling of energy consumption. These technical solutions have failed to overcome the triple technical bottlenecks of weak interfacial bonding, mutual incompatibility between strength and conductivity, and high process costs, forcing electrolytic aluminum companies to incur additional annual anode replacement and power consumption expenses in the tens of millions of yuan range. Therefore, a high-compressive-strength prebaked anode and its production process are needed. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, a high compressive strength prebaked anode and its production process are provided.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A high compressive strength prebaked anode, the prebaked anode comprising the following raw materials:

[0008] 68-85 parts by weight of calcined petroleum coke granules;

[0009] 12-25 parts by weight of modified coal tar pitch binder, the softening point of the modified coal tar pitch binder is 105-115℃;

[0010] Whisker reinforcement 0.3-0.8 parts by weight.

[0011] The calcined petroleum coke particles comprise coarse particles with a diameter of 4-8 mm, medium particles with a diameter of 1-4 mm, and fine powder with a diameter of less than 1 mm. The mass ratio of the coarse particles, medium particles, and fine powder is (3.5-4.5):(2.8-3.5):(2.5-3.2).

[0012] The modified coal tar pitch binder is prepared through the following steps:

[0013] a) Place coal tar pitch with a softening point of 82-86℃ in a reactor and heat it to 160-170℃ at a rate of 3-5℃ / min in a nitrogen atmosphere.

[0014] b) Add 5-8% by weight of nano-silicon carbide powder, with an average particle size of 50 nm.

[0015] c) Maintain stirring at 800-1200 rpm for 40-60 minutes;

[0016] d) Cool to room temperature to form a solid binder, which is the modified coal tar pitch binder.

[0017] The nano-silicon carbide powder was pretreated as follows: the nano-silicon carbide powder was immersed in a 15% hydrofluoric acid solution for 2 hours; then washed with deionized water until the pH of the filtrate was 6.5-7.5; and then vacuum dried at 120°C for 2 hours.

[0018] The fine powder of the calcined petroleum coke is modified by plasma. The modification process includes the following steps: placing the fine powder in the cavity of a radio frequency plasma device and introducing argon gas to stabilize the gas pressure at 0.5-0.8 Pa; applying 30 kW radio frequency power for 15-30 minutes to obtain modified fine powder. The surface oxygen content of the modified fine powder obtained after plasma modification is reduced to 5-7 wt%.

[0019] The whisker reinforcement includes aluminum borate whiskers and potassium titanate whiskers, wherein the mass ratio of aluminum borate whiskers to potassium titanate whiskers is 1:0.6-1.2.

[0020] The aluminum borate whiskers have a diameter of 0.5-1 μm and an aspect ratio of 30-50; the potassium titanate whiskers have a diameter of 0.2-0.5 μm and an aspect ratio of 40-60.

[0021] A process for producing high compressive strength prebaked anodes, the process comprising the following steps:

[0022] (1) Calcination process: Petroleum coke is loaded into a pot furnace and calcined at 1250-1350℃ for 28-32 hours to obtain calcined petroleum coke;

[0023] (2) Crushing and grading: The calcined petroleum coke is processed by a crusher and screened to obtain coarse particles of 4-8mm, medium particles of 1-4mm and fine powder of less than 1mm;

[0024] (3) Fine powder modification: The fine powder obtained in step (2) is subjected to plasma modification to obtain modified fine powder;

[0025] (4) Preparation of binder: Preparation of modified coal tar pitch binder;

[0026] (5) Mixing: Put the coarse particles, medium particles, modified fine powder obtained in step (3), binder and whisker reinforcing agent obtained in step (4) into a kneader and knead at 160-175℃ for 25-40 minutes.

[0027] (6) Molding: The mixed material is put into the mold and vibrated to form a green anode under a pressure of 30-45MPa;

[0028] (7) Calcination: Place the green anode in a ring-type calcining furnace and heat it to 1100-1200℃ at 15-20℃ / hour, and hold it for 24-36 hours.

[0029] Step (5) Kneading is done in stages: first add coarse and medium particles and knead for 8-12 minutes; then add zinc stearate equivalent to 0.1-0.3% of the total raw material mass as a lubricant; finally add modified fine powder, binder and whisker reinforcement and knead for 17-28 minutes.

[0030] In step (7), when the temperature is in the range of 350-550℃, the heating rate is controlled to be 2-3℃ / minute. When the calcination is finished, inert gas is used for rapid cooling, and the cooling rate is not less than 50℃ / minute.

[0031] In step (6), the vibration molding frequency is 40-50Hz and the amplitude is 0.8-1.2mm.

[0032] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0033] 1. The prebaked anode technology proposed in this application enhances overall performance through multiple synergistic mechanisms. Regarding the binder system, a coal tar pitch binder modified with nano-silicon carbide is used, allowing nanoparticles to embed into the pitch molecular chains in a high-temperature molten state, forming a three-dimensional reinforcing network. This structure significantly strengthens the rigidity of the binder phase itself. More importantly, during subsequent roasting, the modified binder can more fully wet the surface of petroleum coke particles, effectively suppressing the initiation of microcracks caused by differences in thermal expansion coefficients by enhancing interfacial chemical bonding.

[0034] 2. For the fine powder component in the aggregate system, a plasma surface activation treatment is specifically introduced. This process selectively removes low-activity oxygen-containing groups on the surface of the fine powder through high-energy argon ion bombardment, while simultaneously generating a large number of dangling bonds. These activated sites interact strongly with the liquid binder during the kneading stage, transforming areas of fine powder that are prone to defects in traditional processes into high-strength bonding points, significantly enhancing the functional contribution of the fine powder in the system.

[0035] 3. The compound design of whisker reinforcements resolves the performance contradictions of traditional single reinforcement materials. Aluminum borate whiskers, with their high modulus, provide skeletal support, while potassium titanate whiskers maintain the conductive network through their unique ionic conductivity channels. When used synergistically in a specific ratio, they form an interpenetrating reinforcement structure within the matrix, which both withstands mechanical stress and ensures electron transport efficiency, avoiding the resistivity degradation problem caused by the introduction of reinforcements.

[0036] 4. The innovative segmented mixing process in the production process significantly optimizes the dispersion effect. Initially, only coarse and medium-sized particles are dry-mixed to eliminate pores between large particles before the binder and fine powder are introduced. This sequential design ensures that the fine powder fully fills the gaps in the skeletal structure. A specially added trace amount of lubricant is introduced in the later stages of mixing to precisely reduce the system viscosity, preventing whisker breakage due to excessive friction and maintaining the integrity of the reinforcing phase.

[0037] 5. The gradient temperature control strategy during the roasting stage of this application is crucial to product performance. A decreasing heating rate is implemented within the critical temperature range for asphalt decomposition to ensure the orderly release of volatiles and eliminate internal porosity defects. The rapid cooling process, by quickly freezing the microstructure, locks in the ideal bonding state between whiskers and aggregates, resulting in a more balanced distribution of internal stress in the material. Detailed Implementation

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The sources of various raw materials in this application are briefly described as follows:

[0040] 1. Petroleum coke

[0041] Purchaser: Liaoyang Petrochemical Branch of China National Petroleum Corporation. Specifications: Meets YS / T 587-2020 Class I standard, sulfur content ≤1.8%, volatile matter ≤0.5%.

[0042] 2. Coal tar pitch

[0043] Purchaser: Shanxi Hongte Coal Chemical Co., Ltd. Model: HT-MZ86, Softening point 82-86℃, Toluene insoluble content 26-30%

[0044] 3. Nano-silicon carbide powder

[0045] Purchaser: Anhui Yishitong Materials Technology Co., Ltd. Model: EShine-SC50, Average particle size 50±5nm, Purity >99.9%, CAS No. 409-21-2

[0046] 4. Hydrofluoric acid

[0047] Purchaser: Do-Fluoride Chemicals Co., Ltd.

[0048] Model: PEDF-40, 40% stock solution, CAS No. 7664-39-3 (must be diluted to 15%)

[0049] 5. Argon (high purity)

[0050] Purchaser: Hangzhou Hangyang Co., Ltd.

[0051] Model: GY-ArG5, purity ≥99.999%, conforms to GB / T 4842-2017

[0052] 6. Aluminum borate whiskers

[0053] Purchaser: Jiangsu Huachi Functional Materials Co., Ltd.

[0054] Model: HC-ABW80, Diameter 0.5-1μm, Aspect Ratio 35-50, CAS No. 12041-78-2

[0055] 7. Potassium titanate whiskers

[0056] Purchaser: Shandong Jingxin Electronic Materials Co., Ltd.

[0057] Model: JX-TKW120, Diameter 0.2-0.5μm, Aspect Ratio 45-60, CAS No. 12056-50-3

[0058] 8. Zinc stearate

[0059] Purchaser: Nanjing Chemical Reagent Co., Ltd.

[0060] Model: C70053, Zinc content 10-11%, CAS No. 557-05-1

[0061] A high compressive strength prebaked anode, the prebaked anode comprising the following raw materials:

[0062] 68-85 parts by weight of calcined petroleum coke granules;

[0063] 12-25 parts by weight of modified coal tar pitch binder, the softening point of the modified coal tar pitch binder is 105-115℃;

[0064] Whisker reinforcement 0.3-0.8 parts by weight.

[0065] The calcined petroleum coke particles comprise coarse particles with a diameter of 4-8 mm, medium particles with a diameter of 1-4 mm, and fine powder with a diameter of less than 1 mm. The mass ratio of the coarse particles, medium particles, and fine powder is (3.5-4.5):(2.8-3.5):(2.5-3.2).

[0066] The modified coal tar pitch binder is prepared through the following steps:

[0067] a) Place coal tar pitch with a softening point of 82-86℃ in a reactor and heat it to 160-170℃ at a rate of 3-5℃ / min in a nitrogen atmosphere.

[0068] b) Add 5-8% by weight of nano-silicon carbide powder, with an average particle size of 50 nm.

[0069] c) Maintain stirring at 800-1200 rpm for 40-60 minutes;

[0070] d) Cool to room temperature to form a solid binder, which is the modified coal tar pitch binder.

[0071] The nano-silicon carbide powder was pretreated as follows: the nano-silicon carbide powder was immersed in a 15% hydrofluoric acid solution for 2 hours; then washed with deionized water until the pH of the filtrate was 6.5-7.5; and then vacuum dried at 120°C for 2 hours.

[0072] The fine powder of the calcined petroleum coke is modified by plasma. The modification process includes the following steps: placing the fine powder in the cavity of a radio frequency plasma device and introducing argon gas to stabilize the gas pressure at 0.5-0.8 Pa; applying 30 kW radio frequency power for 15-30 minutes to obtain modified fine powder. The surface oxygen content of the modified fine powder obtained after plasma modification is reduced to 5-7 wt%.

[0073] The whisker reinforcement includes aluminum borate whiskers and potassium titanate whiskers, wherein the mass ratio of aluminum borate whiskers to potassium titanate whiskers is 1:0.6-1.2.

[0074] The aluminum borate whiskers have a diameter of 0.5-1 μm and an aspect ratio of 30-50; the potassium titanate whiskers have a diameter of 0.2-0.5 μm and an aspect ratio of 40-60.

[0075] A process for producing high compressive strength prebaked anodes, the process comprising the following steps:

[0076] (1) Calcination process: Petroleum coke is loaded into a pot furnace and calcined at 1250-1350℃ for 28-32 hours to obtain calcined petroleum coke;

[0077] (2) Crushing and grading: The calcined petroleum coke is processed by a crusher and screened to obtain coarse particles of 4-8mm, medium particles of 1-4mm and fine powder of less than 1mm;

[0078] (3) Fine powder modification: The fine powder obtained in step (2) is subjected to plasma modification to obtain modified fine powder;

[0079] (4) Preparation of binder: Preparation of modified coal tar pitch binder;

[0080] (5) Mixing: Put the coarse particles, medium particles, modified fine powder obtained in step (3), binder and whisker reinforcing agent obtained in step (4) into a kneader and knead at 160-175℃ for 25-40 minutes.

[0081] (6) Molding: The mixed material is put into the mold and vibrated to form a green anode under a pressure of 30-45MPa;

[0082] (7) Calcination: Place the green anode in a ring-type calcining furnace and heat it to 1100-1200℃ at 15-20℃ / hour, and hold it for 24-36 hours.

[0083] Step (5) Kneading is done in stages: first add coarse and medium particles and knead for 8-12 minutes; then add zinc stearate equivalent to 0.1-0.3% of the total raw material mass as a lubricant; finally add modified fine powder, binder and whisker reinforcement and knead for 17-28 minutes.

[0084] In step (7), when the temperature is in the range of 350-550℃, the heating rate is controlled to be 2-3℃ / minute. When the calcination is finished, inert gas is used for rapid cooling, and the cooling rate is not less than 50℃ / minute.

[0085] In step (6), the vibration molding frequency is 40-50Hz and the amplitude is 0.8-1.2mm.

[0086] The innovation of this application lies in its pioneering use of a three-tiered synergistic mechanism—confined enhancement with nano-silicon carbide, plasma selective etching to activate aggregates, and bi-whisker composite stress / current conduction—to simultaneously resolve the core contradictions that have long existed in the prebaked anode field: weak interfacial bonding, mutual exclusion of strength / conductivity, and poor process adaptability. Specifically, it employs hydrofluoric acid-activated nano-silicon carbide to construct a spatially confined structure in coal tar pitch, increasing the binder softening point by 30% and strengthening interfacial bonding through Si-OC covalent bonds; selectively removing oxygen-containing groups from the surface of fine powder using high-energy argon plasma bombardment, increasing the aggregate surface energy by 50% and achieving molecular-level wetting; innovatively designed aluminum borate / potassium titanate whisker interpenetrating networks, decoupling and synergizing the high-modulus framework with ion-conducting channels, breaking through the 38MPa compressive strength threshold while ensuring a conductivity of ≤53μΩ·m; and combined with segmented kneading kinetic control and precise regulation of calcination phase transformation, reducing the high-temperature creep rate by 44% while maintaining compatibility with existing production lines, ultimately achieving a dual breakthrough in material performance and industrial production.

[0087] The technical solutions of the present invention are further illustrated below through examples and comparative examples, but the scope of protection of the present invention is not limited thereto.

[0088] Example 1

[0089] The process for preparing high compressive strength prebaked anodes is as follows: First, 78 parts by weight of petroleum coke are loaded into a pot furnace and calcined at 1300℃ for 30 hours to obtain calcined petroleum coke. The calcined petroleum coke is crushed and sieved to obtain coarse particles of 4-8 mm, medium particles of 1-4 mm, and fine powder <1 mm, with a mass ratio of 4.5:2.8:2.5. The fine powder is placed in a radio frequency plasma device, and argon gas is introduced to a pressure of 0.6 Pa. It is treated with 30 kW power for 22 minutes to obtain modified fine powder with a surface oxygen content of 6 wt%.

[0090] Preparation of modified coal tar pitch binder: Take coal tar pitch with a softening point of 82℃, heat it to 160℃ at 3℃ / min, add nano silicon carbide powder equivalent to 8% of the mass of coal tar pitch (pre-impregnated with 15% hydrofluoric acid for 2 hours, washed with deionized water to pH 6.5, and vacuum dried at 120℃), stir at 800rpm for 60 minutes, and cool to obtain binder with a softening point of 115℃.

[0091] Mixing process: First, put the coarse and medium particles into a kneader and dry mix for 12 minutes; add 0.1% zinc stearate lubricant to the total raw materials; then add modified fine powder, 25 parts of binder, and 0.8 parts of whisker reinforcing agent (aluminum borate whiskers and potassium titanate whiskers are compounded at a ratio of 1:0.6, aluminum borate diameter 1μm / Aspect ratio 30, potassium titanate diameter 0.5μm / Aspect ratio 40), and knead at 175℃ for 17 minutes. Vibration molding parameters: 45MPa pressure, 40Hz frequency, 1.2mm amplitude. During calcination, the temperature is increased at 20℃ / h, the speed is controlled at 2℃ / min before reaching 550℃, and the temperature is held at 1200℃ for 24 hours. At the end, the temperature is rapidly cooled with argon gas (rate 50℃ / min).

[0092] Example 2

[0093] In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows:

[0094] 68 parts of petroleum coke were calcined at 1250℃ for 32 hours. The particle size distribution after crushing was 3.5:3.5:3.2. The fine powder was treated at 0.5 Pa pressure and 30 kW for 30 minutes, and the surface oxygen content was 7 wt%.

[0095] Binder preparation: Coal tar with a softening point of 86℃ was heated to 170℃ at 5℃ / min, and 5% pretreated nano silicon carbide (washing water pH 7.5) was added. The mixture was stirred at 1200 rpm for 40 minutes to obtain 12 parts of binder with a softening point of 105℃.

[0096] Mixing: Mix coarse and medium particles for 10 minutes; add 0.2% zinc stearate; add 0.55 parts of modified fine powder, binder, and whisker reinforcing agent (whisker ratio 1:0.9, aluminum borate diameter 0.7μm / Aspect ratio 40, potassium titanate diameter 0.3μm / Aspect ratio 50), and mix at 168℃ for 22 minutes. Molding pressure 38MPa, frequency 45Hz, amplitude 1.0mm. Calcination temperature rise 18℃ / h, controlled at 2.5℃ / min before reaching 450℃, held at 1150℃ for 30 hours, quenching rate 55℃ / min.

[0097] Example 3

[0098] In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows:

[0099] 85 parts of petroleum coke were calcined at 1350℃ for 28 hours. The particle size distribution was 4.0:3.0:2.8. The fine powder was treated at 0.8 Pa and 30 kW for 15 minutes, with a surface oxygen content of 5 wt%.

[0100] Binder: Coal tar pitch with a softening point of 84℃ was heated to 165℃ at 4℃ / min, 6.5% nano silicon carbide (pH 7.0) was added, and the mixture was stirred at 1000 rpm for 50 minutes to obtain 19 parts of binder with a softening point of 110℃.

[0101] Mixing: First, mix coarse and medium particles for 8 minutes; add 0.3% zinc stearate; then add 0.3 parts of modified fine powder, binder, and whisker reinforcing agent (aluminum borate to potassium titanate whisker ratio 1:1.2, aluminum borate diameter 0.5μm / Aspect ratio 50, potassium titanate diameter 0.2μm / Aspect ratio 60), and mix at 160℃ for 28 minutes. Molding pressure 30MPa, frequency 50Hz, amplitude 0.8mm. Calcination temperature rise 15℃ / h, controlled at 3℃ / min before reaching 350℃, held at 1100℃ for 36 hours, quenching rate 60℃ / min.

[0102] Comparative Example 1

[0103] In this comparative example, the similarities with Example 1 will not be repeated, and the differences are as follows:

[0104] The binder was replaced with unmodified coal tar pitch (softening point 86℃).

[0105] Comparative Example 2

[0106] In this comparative example, the similarities with Example 2 will not be repeated, and the differences are as follows:

[0107] The fine powder was not subjected to plasma treatment (surface oxygen content 12wt%).

[0108] Comparative Example 3

[0109] In this comparative example, the similarities with Example 3 will not be repeated, and the differences are as follows:

[0110] The whisker reinforcement uses only aluminum borate whiskers (0.8 parts).

[0111] Comparative Example 4

[0112] In this comparative example, the similarities with Example 1 will not be repeated, and the differences are as follows:

[0113] The mixture was not divided into sections; all ingredients were added at once and mixed for 40 minutes.

[0114] Comparative Example 5

[0115] In this comparative example, the similarities with Example 1 will not be repeated, and the differences are as follows:

[0116] During roasting, the temperature should be increased at a rate of 5℃ / min within the range of 350-550℃.

[0117] Performance Test Results and Analysis

[0118] Performance tests were conducted on the prebaked anodes of the comparative examples and the control examples, respectively. The compressive strength was tested according to GB / T 1431, the resistivity was measured according to GB / T 24525, and the high-temperature creep rate (900℃ / 0.8MPa) was measured according to GB / T 30067. The test results are shown in Table 1.

[0119] As shown in Table 1, Example 1, using the highest binder addition of 25 parts and a very large particle size distribution, achieved a maximum strength of 41.5 MPa. This is attributed to three mechanisms: nano-silicon carbide modification increased the interfacial shear strength between the binder phase and aggregate by approximately 40%; plasma-treated fine powder increased the aggregate interstitial filling rate from the conventional 40% to 53%; and whisker composites formed a cross-scale reinforcing network in the matrix. Compared to Comparative Example 1's 33.1 MPa, this demonstrates that the unmodified binder caused microcrack propagation due to weak interfacial bonding. The compressive strength data validates the synergistic effect of the technical solutions.

[0120] Although Example 2 used the minimum binder dosage of 12 parts, the 1:1.2 mixture of aluminum borate / potassium titanate whiskers formed an ion-electron dual pathway, maintaining excellent conductivity of 52.7 μΩ·m. In contrast, Comparative Example 2, due to the thickened oxygen layer (12 wt%) on the surface of the untreated fine powder, experienced a sharp increase in resistance to 59.8 μΩ·m, which hindered electron migration, thus verifying the repair effect of plasma activation on conductive channels.

[0121] Table 1 Analysis of Test Results

[0122] Compressive strength (MPa) 41.5 38.2 40.1 33.1 35.7 36.8 37.3 36.0 Resistivity (μΩ·m) 50.3 52.7 51.0 54.2 59.8 57.4 53.1 56.3 <![CDATA[Creep rate (×10⁻ 5 s⁻¹)]]> 1.8 2.1 1.9 3.9 3.2 2.8 2.5 3.4

[0123] Example 3 showed a creep rate of 1.9 × 10⁻⁻⁻⁶ at 900 °C and 0.8 MPa. 5 s⁻¹, compared to 3.4 × 10⁻ in Comparative Example 5 5 The s⁻¹ was reduced by 44%, which is attributed to two key processes: the controlled-rate heating during the calcination stage (350-550℃) reduced the peak volatile release by 28%, and the rapid cooling process reduced the internal residual stress from the conventional 14MPa to 6MPa. Although the single-whisker system of Comparative Example 3 achieved a compressive strength of 36.8MPa, due to the lack of stress dispersion effect from potassium titanate whiskers, the creep rate data reflected a breakthrough in thermal stability, and the high-temperature creep was still higher than that of the composite system.

[0124] Comparative Example 4, which used a single-stage kneading process, maintained a compressive strength of 37.3 MPa, but exhibited 3.2% corner cracking during vibration molding. In contrast, Example 1, which employed segmented kneading, first constructed a coarse-particle skeleton and then introduced fine powder as filler, increasing the green body density by 0.12 g / cm³ and achieving a molding pass rate exceeding 99.5%. This demonstrates that the impact of the kneading process cannot be underestimated.

[0125] Test results show that, while maintaining a resistivity ≤53μΩ·m, the embodiment achieves a compressive strength exceeding 38MPa and a high-temperature creep rate below 2.1×10⁻⁻⁻⁶. 5 s⁻¹ simultaneously solves three major problems in the background technology: weak interface integration, mutual performance exclusion, and poor process adaptability.

[0126] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high compressive strength prebaked anode, characterized in that, The prebaked anode comprises the following raw materials: 68-85 parts by weight of calcined petroleum coke granules; 12-25 parts by weight of modified coal tar pitch binder, the softening point of the modified coal tar pitch binder is 105-115℃; 0.3-0.8 parts by weight of whisker reinforcing agent, wherein the whisker reinforcing agent includes aluminum borate whiskers and potassium titanate whiskers; The calcined petroleum coke fine powder undergoes plasma modification, which includes the following steps: placing the fine powder in the cavity of a radio frequency plasma device, introducing argon gas to stabilize the gas pressure at 0.5-0.8 Pa; applying 30 kW radio frequency power for 15-30 minutes to obtain modified fine powder, wherein the surface oxygen content of the modified fine powder obtained after plasma modification is reduced to 5-7 wt%. The modified coal tar pitch binder is prepared through the following steps: a) Place coal tar pitch with a softening point of 82-86℃ in a reactor and heat it to 160-170℃ at a rate of 3-5℃ / min in a nitrogen atmosphere. b) Add 5-8% by weight of nano-silicon carbide powder, with an average particle size of 50 nm. c) Maintain stirring at 800-1200 rpm for 40-60 minutes; d) Cool to room temperature to form a solid binder, which is the modified coal tar pitch binder; The above-mentioned prebaked anode production process includes the following steps: (1) Calcination process: Petroleum coke is loaded into a pot furnace and calcined at 1250-1350℃ for 28-32 hours to obtain calcined petroleum coke; (2) Crushing and grading: The calcined petroleum coke is processed by a crusher and screened to obtain coarse particles of 4-8mm, medium particles of 1-4mm and fine powder of less than 1mm; (3) Fine powder modification: The fine powder obtained in step (2) is subjected to plasma modification to obtain modified fine powder; (4) Preparation of binder: Preparation of modified coal tar pitch binder; (5) Mixing: Put the coarse particles and medium particles obtained in step (2), the modified fine powder obtained in step (3), the binder and whisker reinforcing agent obtained in step (4) into a kneader and knead at 160-175℃ for 25-40 minutes. The kneading is carried out in stages: first add the coarse particles and medium particles and knead for 8-12 minutes; then add zinc stearate equivalent to 0.1-0.3% of the total raw material mass as a lubricant; finally add the modified fine powder, binder and whisker reinforcing agent and knead for 17-28 minutes. (6) Molding: The mixed material is put into the mold and vibrated to form a green anode under a pressure of 30-45MPa; (7) Calcination: Place the green anode in a ring-type calcining furnace and heat it to 1100-1200℃ at 15-20℃ / hour, and hold it for 24-36 hours. When the temperature is in the range of 350-550℃, control the heating rate to be 2-3℃ / minute.

2. The high compressive strength prebaked anode according to claim 1, characterized in that, The calcined petroleum coke particles comprise coarse particles with a diameter of 4-8 mm, medium particles with a diameter of 1-4 mm, and fine powder with a diameter of less than 1 mm. The mass ratio of the coarse particles, medium particles, and fine powder is (3.5-4.5):(2.8-3.5):(2.5-3.2).

3. The high compressive strength prebaked anode according to claim 2, characterized in that, The nano-silicon carbide powder was pretreated as follows: the nano-silicon carbide powder was immersed in a 15% hydrofluoric acid solution for 2 hours; then washed with deionized water until the pH of the filtrate was 6.5-7.5; and then vacuum dried at 120°C for 2 hours.

4. The high compressive strength prebaked anode according to claim 1, characterized in that, The mass ratio of aluminum borate whiskers to potassium titanate whiskers is 1:0.6-1.2; The aluminum borate whiskers have a diameter of 0.5-1 μm and an aspect ratio of 30-50; the potassium titanate whiskers have a diameter of 0.2-0.5 μm and an aspect ratio of 40-60.

5. The high compressive strength prebaked anode according to claim 1, characterized in that, In step (7), at the end of the roasting, inert gas is used for rapid cooling at a rate of not less than 50°C / minute.

6. The high compressive strength prebaked anode according to claim 1, characterized in that, In step (6), the vibration molding frequency is 40-50Hz and the amplitude is 0.8-1.2mm.