Method and system for toughening a spherical mullite reinforced porcelain insulator

Abstract

The application belongs to the technical field of ceramic material preparation, and relates to a method and system for improving the toughness of a spherical mullite reinforced porcelain insulator, which comprises the following steps: obtaining a precursor green body with a three-dimensional sacrificial conductive network embedded inside; forming a preliminary three-dimensional interlocking mullite framework; fusing into a multi-modal process characteristic signal; generating a process stage switching instruction; obtaining a template-removed body; continuously monitoring the multi-modal process characteristic signal until a template removal completion signal is generated when it is confirmed that the three-dimensional sacrificial conductive network has been basically removed; and heating the template-removed body to a final ceramization temperature for densification sintering according to the template removal completion signal, so as to obtain a final product of the porcelain insulator containing a three-dimensional interlocking mullite reinforced network inside. The application solves the problem of lacking real-time monitoring and accurate control means for the behavior of the reinforced phase in the sintering process.

Description

Technical Field

[0001] This invention belongs to the technical field of ceramic material preparation, and relates to a method and system for enhancing the toughness of ceramic insulators with spherical mullite. Background Technology

[0002] As a critical support and insulation component in power systems, the mechanical reliability of porcelain insulators directly affects the safe and stable operation of the entire power grid. Currently, improving the fracture toughness of porcelain insulators to resist brittle fracture caused by mechanical stress, thermal shock, or unexpected external forces is a core challenge facing the industry. The inherent brittleness of traditional porcelain materials makes them highly susceptible to catastrophic rapid propagation after the appearance of microcracks. Therefore, effectively inhibiting crack initiation and propagation, extending product lifespan, and improving safety during service have become key focuses of material research and development and manufacturing process improvement.

[0003] A commonly adopted solution in the industry is to introduce a second-phase reinforcement into the ceramic matrix, such as adding silicon carbide whiskers, alumina lamellars, or other high-strength, high-modulus particles. The basic idea behind this method is to deflect or pin cracks by dispersing the reinforcing particles within the matrix, thereby consuming the energy required for crack propagation and achieving toughening. This method is relatively simple; composite ceramic insulators can be prepared by physically blending the reinforcing phase with the base ceramic raw materials and then performing traditional molding and sintering processes.

[0004] Based on the above problems, this traditional dispersion reinforcement method has obvious drawbacks. The entire preparation process of ceramic materials is based on experience and lacks real-time monitoring and precise control of the behavior of the reinforcing phase during sintering, resulting in poor product performance consistency and difficulty in fundamentally guaranteeing reliability. Summary of the Invention

[0005] In a first aspect, the present invention provides a method for enhancing the toughness of porcelain insulators with spherical mullite, employing the following technical solution:

[0006] A method for enhancing the toughness of porcelain insulators with spherical mullite includes the following steps:

[0007] S1. The slurry of pre-dispersed conductive nanomaterials and insulating ceramic raw materials is mixed, shaped and dried to obtain a precursor green body with a three-dimensional sacrificial conductive network embedded inside.

[0008] S2. The precursor green body is placed in a sintering environment with multiple sets of electrodes, heated to the initial generation temperature range of mullite crystals, and a dynamically time-space alternating external electric field is applied. Micro-region electric fields are generated inside the precursor green body along the three-dimensional sacrificial conductive network, forming a preliminary three-dimensional interlocking mullite framework.

[0009] S3. The electrical characteristic parameters reflecting the connectivity state of the three-dimensional sacrificial conductive network and the physical signals reflecting the initial growth dynamics of the three-dimensional interlocked mullite skeleton are time-aligned and fused into a multimodal process characteristic signal.

[0010] S4. Based on the multimodal process characteristic signals, the mullite skeleton forming inflection point is identified. When the combined event mode of the initial three-dimensional interlocking mullite skeleton growth slows down and the three-dimensional sacrificial conductive network structure is complete appears, a process stage switching instruction is generated.

[0011] S5. In response to the process stage switching command, stop applying the dynamically alternating external electric field and adjust the sintering environment to an oxidizing atmosphere. The precursor green body undergoes oxidation removal treatment of the sacrificial conductive network to obtain a green body with the template removed.

[0012] S6. Continuously monitor the characteristic signals of the multimodal process until it is confirmed that the three-dimensional sacrificial conductive network has been basically removed, and then generate a template removal completion signal.

[0013] S7. Based on the template removal completion signal, heat the template-removed blank to the final vitrification temperature for densification sintering to obtain a finished porcelain insulator containing a three-dimensional interlocked mullite reinforcement network.

[0014] A further aspect of the present invention involves obtaining a precursor green body with a three-dimensional sacrificial conductive network embedded internally, comprising the following steps:

[0015] Select conductive nanomaterials with high aspect ratio for liquid phase pre-dispersion treatment;

[0016] High aspect ratio conductive nanomaterials that have undergone pre-dispersion treatment are mixed with a slurry of insulating ceramic raw materials. By adjusting the pH and viscosity of the slurry of insulating ceramic raw materials, the high aspect ratio conductive nanomaterials are encouraged to self-assemble into physically connected pathways during the drying process, forming a three-dimensional sacrificial conductive network.

[0017] A further aspect of the present invention involves forming a preliminary three-dimensional interlocking mullite framework, comprising the following steps:

[0018] By periodically switching the activation state and electric field polarity of different electrode groups, mullite crystals are guided to undergo directional nucleation and bridging growth along the path of a three-dimensional sacrificial conductive network in three-dimensional space.

[0019] Micro-field electric fields are generated inside the precursor green body along a three-dimensional sacrificial conductive network, forming a preliminary three-dimensional interlocking mullite framework;

[0020] While applying an external electric field, an inert or weakly reducing gas is introduced into the sintering environment.

[0021] A further aspect of the present invention involves fusing the signals into a multimodal process characteristic signal, comprising the following steps:

[0022] An impedance spectrum data stream reflecting the connectivity state of a three-dimensional sacrificial conductive network was established by measuring the global AC impedance spectrum characteristics of the precursor green body.

[0023] Capture the micro-stress waves generated inside the precursor green body due to the formation and overlapping of mullite crystals, and establish an acoustic emission data stream that reflects the growth dynamics of the initial three-dimensional interlocked mullite skeleton.

[0024] The impedance spectrum data stream and the acoustic emission data stream are time-aligned and fused into a multimodal process characteristic signal.

[0025] A further aspect of the present invention generates a process stage switching instruction, comprising the following steps:

[0026] Calculate the rate of change of acoustic emission event rate or cumulative energy over time in the acoustic emission data stream;

[0027] Extract key characteristic frequencies and corresponding amplitudes related to the three-dimensional sacrificial conductive network structure from the impedance spectrum data stream;

[0028] When the rate of change of acoustic emission event rate or cumulative energy decreases to below a preset slowing threshold, and the key characteristic frequency and corresponding amplitude remain stable within a preset time window, it is determined that a combined event pattern has been identified.

[0029] Determine the inflection point of the mullite skeleton forming process and generate process stage switching instructions.

[0030] A further aspect of this invention identifies the mullite skeleton forming inflection point based on multimodal process characteristic signals, comprising the following steps:

[0031] The cumulative energy or event rate growth rate of the acoustic emission signal in the dual-modal process characteristic signal was monitored to begin to slow down and tend to stabilize.

[0032] When the key characteristic frequencies and amplitudes of the AC impedance spectrum remain stable within the same time window, it is determined that the inflection point of mullite framework formation has been reached.

[0033] A further aspect of the present invention involves performing an oxidation removal process on the precursor green body to remove the sacrificial conductive network, comprising the following steps:

[0034] The gas in the sintering environment is switched from an inert or weakly reducing gas to an oxidizing gas;

[0035] The sintering temperature is maintained or increased to a preset oxidation temperature that allows the three-dimensional sacrificial conductive network material to be completely oxidized into gaseous products and escape, thereby removing the three-dimensional sacrificial conductive network from the gaps in the initial three-dimensional interlocked mullite skeleton.

[0036] A further aspect of the present invention involves generating a template removal completion signal, comprising the following steps:

[0037] The template for extracting and characterizing multimodal process features has been removed to remove the overall resistance of the billet and to separate the specific frequency signal intensity related to the oxidation reaction.

[0038] When the overall resistance increases exponentially and exceeds the preset high impedance threshold, and the intensity of the specific frequency signal related to the oxidation reaction falls back to the background noise level, a template removal completion signal is generated.

[0039] A further aspect of the present invention involves heating the blank (with the template removed) to the final vitrification temperature for densification sintering, comprising the following steps:

[0040] The template removes the ceramic matrix material from the green body and performs liquid phase sintering to fill the micropores left by the removal of the three-dimensional sacrificial conductive network, and forms an interface bond with the preliminary three-dimensional interlocked mullite skeleton, solidifying into a three-dimensional interlocked mullite reinforced network.

[0041] After heat preservation and controlled cooling, the finished porcelain insulator is obtained.

[0042] Secondly, the present invention provides a system for enhancing the toughness of porcelain insulators with spherical mullite, employing the following technical solution:

[0043] A system for enhancing the toughness of porcelain insulators with spherical mullite includes the following modules:

[0044] The precursor green body preparation module is used to mix, shape, and dry the slurry of pre-dispersed conductive nanomaterials and insulating ceramic raw materials to obtain a precursor green body with a three-dimensional sacrificial conductive network embedded inside.

[0045] In the electric field-induced growth module, the precursor green body is placed in a sintering environment with multiple sets of electrodes, heated to the initial generation temperature range of mullite crystals, and a dynamically space-time alternating external electric field is applied. Micro-region electric fields are generated inside the precursor green body along a three-dimensional sacrificial conductive network, forming a preliminary three-dimensional interlocking mullite framework.

[0046] The dual-mode signal acquisition module is used to time-align electrical characteristic parameters reflecting the connectivity state of the three-dimensional sacrificial conductive network with physical signals reflecting the initial growth dynamics of the three-dimensional interlocked mullite skeleton, and fuse them into a multi-mode process characteristic signal.

[0047] The forming inflection point identification module identifies the forming inflection point of the mullite skeleton based on the multimodal process characteristic signals. When the combined event mode of the initial three-dimensional interlocking mullite skeleton growth slows down and the three-dimensional sacrificial conductive network structure is complete appears, a process stage switching instruction is generated.

[0048] The sacrificial network oxidation removal module responds to the process stage switching command, stops applying the dynamically changing external electric field and adjusts the sintering environment to an oxidizing atmosphere. The precursor green body undergoes oxidation removal treatment of the sacrificial conductive network to obtain a green body with the template removed.

[0049] The template removal confirmation module continuously monitors the multimodal process characteristic signals until it confirms that the three-dimensional sacrificial conductive network has been basically removed, and then generates a template removal completion signal.

[0050] In the final densification sintering module, based on the template removal completion signal, the template-removed blank is heated to the final vitrification temperature for densification sintering to obtain a finished porcelain insulator containing a three-dimensional interlocked mullite reinforcement network.

[0051] In summary, the present invention has the following beneficial technical effects:

[0052] 1. By pre-constructing a sacrificial conductive network as a template within the ceramic green body and guiding the in-situ directional growth of the reinforcing phase mullite crystals along this template using an external electric field, a three-dimensional interlocking continuous reinforcing skeleton can be constructed. This bottom-up, actively designed microstructure, compared to traditional randomly dispersed particle reinforcement, forms a more effective stress transfer and energy absorption network. It can significantly suppress crack propagation through multiple mechanisms such as crack bridging and pull-out, fundamentally improving the fracture toughness and mechanical reliability of ceramic insulators.

[0053] 2. A real-time online monitoring and feedback control mechanism based on dual-modal process characteristic signals transforms the traditional "black box" sintering process based on a fixed time-temperature program into an intelligent, closed-loop control process based on the real-time evolution of the material's internal state. By simultaneously monitoring electrical signals reflecting the integrity of the conductive network and acoustic signals reflecting the dynamics of crystal growth, the key time inflection point of mullite framework formation can be captured, triggering subsequent process switching accordingly. This improves process accuracy and repeatability, ensuring the stability and superior performance of the final product.

[0054] 3. Ensuring complete removal of the sacrificial template and high purity of the final product. After the reinforcing skeleton is formed, the conductive network serving as the template is completely converted into gaseous products and released through atmosphere switching and a specialized oxidation removal step. Online monitoring signals confirm complete removal. This design avoids introducing any impurity phases that could affect the insulation performance of the final insulator, ensuring that the product possesses excellent mechanical properties while its inherent high resistivity and excellent dielectric properties remain unaffected, achieving a synergistic improvement in both mechanical and electrical properties. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings are used to provide a further understanding of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 A flowchart illustrating an embodiment of this application is disclosed.

[0057] Figure 2 Structural schematic diagrams of embodiments of this application are disclosed. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] The following is in conjunction with the appendix Figures 1-2 A preferred description of the present invention is provided below.

[0060] See attached document Figure 1 This invention proposes a method for enhancing the toughness of porcelain insulators with spherical mullite, comprising the following steps:

[0061] S1. The slurry of pre-dispersed conductive nanomaterials and insulating ceramic raw materials is mixed, shaped and dried to obtain a precursor green body with a three-dimensional sacrificial conductive network embedded inside.

[0062] S2. The precursor green body is placed in a sintering environment with multiple sets of electrodes, heated to the initial generation temperature range of mullite crystals, and a dynamically time-space alternating external electric field is applied. Micro-region electric fields are generated inside the precursor green body along the three-dimensional sacrificial conductive network, forming a preliminary three-dimensional interlocking mullite framework.

[0063] S3. The electrical characteristic parameters reflecting the connectivity state of the three-dimensional sacrificial conductive network and the physical signals reflecting the initial growth dynamics of the three-dimensional interlocked mullite skeleton are time-aligned and fused into a multimodal process characteristic signal.

[0064] S4. Based on the multimodal process characteristic signals, the mullite skeleton forming inflection point is identified. When the combined event mode of the initial three-dimensional interlocking mullite skeleton growth slows down and the three-dimensional sacrificial conductive network structure is complete appears, a process stage switching instruction is generated.

[0065] S5. In response to the process stage switching command, stop applying the dynamically alternating external electric field and adjust the sintering environment to an oxidizing atmosphere. The precursor green body undergoes oxidation removal treatment of the sacrificial conductive network to obtain a green body with the template removed.

[0066] S6. Continuously monitor the characteristic signals of the multimodal process until it is confirmed that the three-dimensional sacrificial conductive network has been basically removed, and then generate a template removal completion signal.

[0067] S7. Based on the template removal completion signal, heat the template-removed blank to the final vitrification temperature for densification sintering to obtain a finished porcelain insulator containing a three-dimensional interlocked mullite reinforcement network.

[0068] In one embodiment of the present invention, step S1 includes the following steps:

[0069] At least one conductive nanomaterial is pre-dispersed in the liquid phase to break its original agglomerated state; the pre-dispersed conductive nanomaterial is mixed with the slurry of insulating ceramic raw material, and by adjusting the pH and viscosity of the slurry, the conductive nanomaterial is encouraged to self-assemble into physically connected pathways during the drying and molding process; after molding and drying, a precursor green body with an internally embedded three-dimensional sacrificial conductive network is obtained.

[0070] Specifically, conductive nanomaterials with high aspect ratios are selected. High aspect ratio conductive nanomaterials refer to nanoscale conductive materials whose geometric length is greater than their diameter and which construct conductive pathways. The selection of conductive nanomaterials is based on the formation of continuous conductive pathways through overlapping within a ceramic matrix, typically with an aspect ratio greater than 100. The ceramic matrix refers to the densified ceramic material that forms the main body of the insulator after the conductive network has been removed and final sintered.

[0071] In a preferred embodiment, the conductive nanomaterial is a carbon-based nanomaterial. The carbon-based nanomaterial undergoes a liquid-phase pre-dispersion treatment. Carbon-based nanomaterials are a specific category of materials designated for use as conductive nanomaterials, primarily composed of carbon elements and possessing excellent conductivity, such as carbon nanotubes or graphene. A specific amount of carbon-based nanomaterial is added to the liquid medium, and energy is applied through mechanical stirring or ultrasonic oscillation. The purpose of applying energy is to break the initial agglomeration of the carbon-based nanomaterial, causing it to suspend uniformly as single or small-sized bundles.

[0072] The pre-dispersed conductive nanomaterials are mixed with a slurry of insulating ceramic raw materials. This slurry is a fluid suspension formed by mixing insulating ceramic raw material powder with a liquid medium and a small amount of additives; its function is to serve as a carrier for material mixing and molding. During the mixing process, the pH of the slurry is adjusted by adding acidic or alkaline regulators, and the viscosity is adjusted by using thickeners or thinners. The purpose of these adjustments is to create a chemical-physical environment conducive to the spontaneous arrangement and interconnection of the conductive nanomaterials during subsequent drying, relying on capillary forces and interparticle interactions to form physical pathways.

[0073] The uniformly mixed slurry is formed into a predetermined shape through slip casting, dry pressing, or tape casting. It is then dried under controlled temperature and humidity conditions to slowly remove moisture from the insulating ceramic raw material slurry. After the forming and drying steps are completed, a precursor green body with a uniformly embedded three-dimensional sacrificial conductive network is obtained. The three-dimensional sacrificial conductive network refers to a three-dimensional conductive pathway system formed by interconnected conductive nanomaterials with high aspect ratios throughout the entire green body volume. At this point, the conductive nanomaterials inside the precursor green body constitute a continuous conductive path running through the entire structure. The precursor green body refers to the unsintered green body obtained after forming and drying before the final high-temperature sintering and densification of the ceramic product. The interior of the precursor green body contains insulating ceramic raw material particles and a network composed of conductive nanomaterials.

[0074] Among them, the three-dimensional sacrificial conductive network is a temporary network structure that serves as a growth template in the early stage of ceramic matrix sintering and is removed in subsequent processes.

[0075] For example, a precursor green body containing a sacrificial conductive network was prepared. Multi-walled carbon nanotubes were selected as the carbon-based nanomaterial. The diameter of the multi-walled carbon nanotubes was 10 nm-20 nm, and the length was 10 μm-30 μm, which meets the characteristics of conductive nanomaterials with a high aspect ratio. 1 g of multi-walled carbon nanotubes were placed in 100 mL of anhydrous ethanol and treated in an ultrasonic cleaner with a power of 300 W for 1 h to complete the pre-dispersion treatment.

[0076] 100g of alumina powder with an average particle size of 1μm was used as the raw material for insulating ceramics. It was mixed with 50mL of deionized water and 0.5g of ammonium polyacrylate dispersant to prepare a slurry for the insulating ceramics raw material. A pre-dispersed carbon nanotube ethanol suspension was slowly added to the slurry. The pH of the slurry was adjusted to 9.5 with ammonia water, and hydroxyethyl cellulose was added to control the viscosity of the slurry at 500mPa·s. The mixed slurry was poured into a cylindrical mold and dried at 60℃ and 70% relative humidity for 24 hours to obtain a precursor green body with a uniform three-dimensional sacrificial conductive network inside.

[0077] In one embodiment of the present invention, step S2 includes the following steps:

[0078] The precursor green body is placed in a sintering environment with multiple sets of electrodes and heated to the initial generation temperature range of mullite crystals. A dynamically space-time alternating external electric field is applied, and a micro-region electric field distributed along the sacrificial conductive network is generated inside the precursor green body. The dynamically space-time alternating external electric field is achieved by periodically switching the activation state and electric field polarity of different electrode sets, guiding the mullite crystals to grow in a directional manner along the path of the sacrificial conductive network in three-dimensional space for nucleation and bridging.

[0079] While applying an electric field, an inert or weakly reducing gas is introduced into the sintering environment to protect the three-dimensional sacrificial conductive network from oxidation within this temperature range. Through the guiding effect of the micro-field, the generated mullite crystals attach and interconnect along the sacrificial conductive network to form a preliminary three-dimensional interlocking mullite framework.

[0080] Specifically, the prepared precursor green body undergoes electric field-induced growth treatment. First, the precursor green body is transferred into a sintering environment equipped with multiple sets of electrodes. This environment is a sintering furnace capable of precisely controlling temperature and atmosphere. Electric field-induced growth is a special sintering technique that utilizes an external electric field to influence the nucleation and growth direction of mullite crystals within the material. A sintering environment with multiple sets of electrodes refers to a sintering furnace with at least two sets of electrodes installed inside, whose on / off state and polarity can be independently controlled, allowing electric fields to be applied to the sample within the furnace from different spatial directions. The temperature of the sintering environment is then programmed to rise to the initial mullite crystal formation temperature range. This initial mullite crystal formation temperature range refers to the temperature range within which a specific ceramic raw material system begins to form the mullite phase. For example, using differential thermal analysis experiments on the kaolinite-alumina system, the temperature range is typically between 980 and 1200 °C.

[0081] When the initial growth temperature range of mullite crystals is reached, a dynamically space-time alternating external electric field is applied through an external control system. This dynamically space-time alternating external electric field refers to an electric field that dynamically changes with time in its position and direction of application. By continuously changing the electric field distribution, the growth path of the mullite crystals is comprehensively guided in three-dimensional space. The dynamically space-time alternating external electric field periodically activates different electrode groups and switches the polarity of the electric field applied to the electrode groups. For example, it alternately energizes electrode pairs in different directions according to a preset sequence and changes the positive and negative poles during energization.

[0082] Because of the presence of a three-dimensional sacrificial conductive network within the precursor green body, an external electric field generates concentrated high electric field strength on the surface and tip regions of the conductive network, thus generating micro-fields along the paths of the conductive network within the precursor green body. A micro-field refers to a localized high-intensity electric field region formed around the conductive network due to the disturbance and focusing effect of the three-dimensional sacrificial conductive network on the external electric field. Throughout the electric field-induced growth process, an inert or weakly reducing gas is continuously introduced into the sintering environment to form a protective atmosphere. Inert or weakly reducing gases are chemically stable at high temperatures and will not undergo oxidation reactions with the carbon-based conductive network, such as argon, nitrogen, or a nitrogen-hydrogen mixture.

[0083] In the presence of inert or weakly reducing gases, to prevent the carbon-based three-dimensional sacrificial conductive network from oxidizing and disappearing at high temperatures, the components in the insulating ceramic raw material preferentially undergo chemical reactions on the surface of the sacrificial conductive network, where the electric field strength is highest. This directional nucleation forms mullite crystals, which then bridge and grow along the network path. The resulting mullite crystals adhere to and tightly interconnect along the sacrificial conductive network, forming a preliminary three-dimensional interlocking mullite framework. This preliminary three-dimensional interlocking mullite framework refers to the continuous network structure formed during the electric field-induced stage, where newly generated mullite crystals overlap along the sacrificial conductive network. While the three-dimensional interlocking mullite framework is initially formed, the ceramic matrix is ​​not yet densified.

[0084] For example, an alumina-based precursor green body containing a carbon nanotube network is placed in a sintering environment with multiple electrode sets containing three pairs of tungsten electrodes evenly distributed along its circumference. The sintering environment is heated to 1150°C at a rate of 10°C / min, which falls within the initial formation temperature range of mullite crystals. Upon reaching this temperature, a dynamically alternating external electric field is applied. A voltage of 100V is sequentially applied to the three pairs of electrodes via a controller, energizing each pair for 30 seconds before switching to the next pair, while simultaneously reversing the electric field polarity every 15 seconds. Throughout the process, argon gas at a flow rate of 1L / min is introduced into the sintering environment as an inert or weakly reducing gas. After 60 minutes of electric field-induced growth treatment, without damaging the precursor green body, a preliminary three-dimensional interlocking mullite framework formed by the interlocking of mullite whiskers is generated within the interior along the carbon nanotube network.

[0085] In one embodiment of the present invention, step S3 includes the following steps:

[0086] Low-voltage detection signals are applied to both ends of the precursor green body to monitor at least one electrical characteristic parameter reflecting the connectivity state of the sacrificial conductive network in real time, and a first data stream is established; at least one physical signal reflecting the growth dynamics of the enhanced skeleton is monitored simultaneously to establish a second data stream; the first data stream and the second data stream are time-aligned and fused into a multimodal process characteristic signal that can synchronously characterize the integrity of the internal conductive pathway and the growth state of the enhanced skeleton.

[0087] In a preferred embodiment, the electrical characteristic parameter is an AC impedance spectrum, and the first data stream is an impedance spectrum data stream. In the same preferred embodiment, the physical signal is an acoustic emission signal, and the second data stream is an acoustic emission data stream. The multimodal process characteristic signal in this case is the dual-modal process characteristic signal.

[0088] Specifically, throughout the entire period of electric field-induced growth, two key physical quantities of the precursor green body are monitored synchronously and continuously: the first is the global AC impedance spectroscopy (GAS) characteristic, which reflects the conductivity and energy storage capacity of the entire precursor green body at different AC frequencies. It is typically a multidimensional array containing frequency, resistance, and capacitance values, or the real and imaginary parts of the impedance. A separate measurement circuit switches the growth electrode to the measurement electrode, and a low-voltage detection signal is applied to both ends of the precursor green body. This low-voltage detection signal serves as a weak excitation signal for measurement, set to be much smaller than the electric field strength inducing mullite crystal growth to avoid interference with the growth process; it is typically set below 1V.

[0089] Impedance analyzers are used to measure the current flowing through the precursor green blank and the phase difference between the voltage and the current. The measurement is performed over a wide frequency range to obtain the resistance and capacitance responses of the precursor green blank at different frequencies. In order to fully capture and distinguish the various physical and chemical processes that occur inside the precursor green blank at different time scales, the wide frequency range is usually set from a high frequency of 1MHz to a low frequency of 0.01Hz, spanning a frequency range of 5 to 8 orders of magnitude.

[0090] This measurement process is repeated at set time intervals, recording the complete spectral data measured at each time point in chronological order, thus establishing an impedance spectrum data stream reflecting the connectivity of the sacrificial conductive network. The impedance spectrum data stream is a time-series dataset, and each element is a complete global AC impedance spectrum characteristic data.

[0091] The second physical quantity is internal acoustic emission activity, which refers to the physical phenomenon of energy being released in the form of elastic waves when microscopic changes occur inside the material. High-sensitivity acoustic sensors are arranged outside the sintering environment via high-temperature resistant acoustic waveguides. These acoustic sensors are transducers that convert acoustic vibrations into electrical signals. They are used to capture and convert the micro-stress waves generated inside the green body of the precursor due to the release of minute stresses caused by lattice rearrangement and microstructural evolution as mullite crystals are generated, grow, and overlap under the influence of a micro-field electric field. These micro-stress waves are high-frequency elastic waves generated when localized stress inside the material is rapidly released.

[0092] The electrical signal output from the acoustic sensor is amplified and filtered to establish an acoustic emission data stream reflecting the dynamics of mullite crystal growth. This acoustic emission data stream is a time-series dataset containing parameters such as the occurrence rate, amplitude, duration, and energy of acoustic emission events. The acquired impedance spectroscopy data stream and the acoustic emission data stream are time-aligned through a central processing system to ensure that each data point in both streams corresponds to the same moment. These two time-synchronized data streams are then fused into a composite dataset, which is a dual-modal process characteristic signal capable of synchronously characterizing the integrity of the internal conductive pathways and the growth state of the mullite crystal. This dual-modal process characteristic signal integrates signals from two different physical sources—electrical and acoustic signals—in the time dimension to provide a comprehensive description of the material's internal state.

[0093] For example, in a sintering environment of 1150°C, online monitoring is started simultaneously. A low-voltage detection signal with an amplitude of 0.5V is applied through the measurement leads connected to both ends of the precursor green body. An impedance analyzer is used to perform scanning measurements in a wide frequency range of 1Hz to 1MHz. The complete global AC impedance spectrum characteristics are recorded every 1 minute to form an impedance spectrum data stream.

[0094] A piezoelectric acoustic sensor coupled to a quartz observation window outside the sintering environment continuously captures microscopic stress waves in the frequency range of 100kHz to 300kHz generated during the formation and overlapping of mullite crystals. After amplification and processing, the acoustic emission event count is recorded every minute, forming an acoustic emission data stream. The data acquisition system aligns these two data streams in time. The data points recorded in the 10th minute contain the complete impedance spectrum measured at that moment and the total number of acoustic emission events accumulated from the 9th to the 10th minute, fusing them into a dual-modal process characteristic signal.

[0095] In one embodiment of the present invention, step S4 includes the following steps:

[0096] The inflection point of mullite framework formation is identified based on the characteristic signals of the dual-modal process. Real-time analysis of these signals identifies and determines specific combined event patterns. These combined event patterns characterize the growth of the mullite framework reaching a preset integrity level before overgrowth begins. The preset integrity level refers to the connectivity and density standards that the mullite framework needs to achieve according to product performance requirements, indirectly characterized by the cumulative amount of acoustic emission signals. Overgrowth refers to the continued disordered growth of mullite crystals after reaching the ideal framework morphology, leading to grain coarsening or increased internal stress.

[0097] Within the same time window, the key characteristic frequencies and amplitudes of the AC impedance spectrum remain stable, indicating that the three-dimensional sacrificial conductive network maintains good structural integrity and conductive connectivity. When this combined event mode is identified, the system determines that the mullite skeleton forming inflection point has been reached and generates a process stage switching instruction.

[0098] Specifically, the analysis system receives the dual-modal process characteristic signals from the previous stage and processes the acoustic emission data stream and impedance spectrum data stream contained therein in parallel to find and determine specific combined event modes. The combined event mode refers to the composite condition that defines the inflection point of mullite framework formation. It is a logical "AND" operation that requires the acoustic and electrical signals to simultaneously meet their respective easing criteria, indicating that the large-scale crystal growth and bonding stage is nearing its end.

[0099] For acoustic emission data streams, the rate of change of the cumulative energy or event rate of the acoustic emission signal over time is calculated, i.e., its first derivative. The cumulative energy refers to the total energy obtained by summing the energy values ​​of all acoustic emission events over a period of time, reflecting the overall scale of crystal growth. The event rate refers to the number of acoustic emission events occurring per unit time, reflecting the instantaneous rate of crystal growth. Continuously monitoring this rate of change and determining whether it begins to decrease significantly and tends towards a stable value close to zero indicates that the large-scale crystal growth and bonding phase is nearing its end.

[0100] For the impedance spectrum data stream, key characteristic frequencies and corresponding amplitudes are extracted from the AC impedance spectrum at each time point. Key characteristic frequencies typically refer to specific frequency points in the impedance spectrum related to the conductive network structure, such as the frequency at which the impedance phase angle reaches its peak and begins to change abruptly. Amplitude refers to the impedance or admittance value measured at the key characteristic frequency. The values ​​of these parameters are compared over several consecutive time windows, which are continuous time periods used to analyze signal stability. Determining whether stability is maintained—that is, whether the fluctuation range is within a preset stability tolerance—indicates that the three-dimensional sacrificial conductive network, serving as the growth template, maintains good structural integrity and conductive connectivity at this stage.

[0101] When the conditions for stable acoustic emission activity and stable impedance spectrum characteristics are simultaneously met within the same time window, the combined event mode is identified. The current time point is marked as the inflection point for mullite framework forming, and a process stage switching command is generated as the output signal, satisfying the following conditions:

[0102] Condition one: ;

[0103] Condition two: and ;

[0104] in, This represents the cumulative energy or event rate of the acoustic emission signal at time t; t represents time, in seconds (s). represent The first derivative with respect to time, i.e., the rate of increase of acoustic emission activity; It is the threshold for judging the growth rate of acoustic emission activity. The basis for setting it is to determine the value to which the growth rate usually decreases when the skeleton growth tends to be completed by statistical analysis of 200 sintering experiments under different process parameters. For example, it is set to 5% of the initial peak growth rate.

[0105] The key characteristic frequency of the AC impedance spectrum measured at time t is expressed in Hz. Δt represents the amplitude of the key characteristic frequency at time t, in Ω. Δt represents the time window used to determine stability, in seconds, and is set based on the typical time scale of process changes, usually between 2 and 5 measurement cycles.

[0106] and These are the stability tolerances for key characteristic frequencies and amplitudes, set based on the noise level of the measurement system itself and the normal process fluctuation range, ensuring that signal stability reflects actual state changes rather than measurement errors. When both conditions are simultaneously met at time t, the mullite framework formation inflection point is determined. The mullite framework formation inflection point is a critical time point in the process, marking that the three-dimensional interlocking mullite framework formed under electric field induction has reached the preset integrity, and the sacrificial conductive network serving as the template has not yet begun to significantly degrade due to high temperature or atmospheric effects. Process stage switching commands are digital or analog signals generated by the analysis system, switching from one process stage to the next, such as switching from electric field-induced growth to oxidation removal.

[0107] For example, a threshold for the rate of increase of acoustic emission event rate is set. Set a time window for judging stability based on the rate of change over 10 events / min. For 3 minutes, the stability tolerance of key characteristic frequencies For 100Hz, amplitude stability tolerance The Ω value is 50. When the electric field-induced growth treatment reached 45 minutes, system analysis showed that the rate of increase of acoustic emission event rate decreased from a peak of 200 events / min to 8 events / min, satisfying condition one.

[0108] Within the time window from 42 to 45 minutes, the key characteristic frequency of the AC impedance spectrum was measured to be stable at around 10.1 kHz with fluctuations less than 50 Hz, and the corresponding amplitude was stable at 5.2 kΩ with fluctuations less than 20 Ω, satisfying condition two. Since both conditions are simultaneously met in this combined event mode, this moment is determined to be the inflection point for mullite framework formation. A high-level digital signal is generated as a process stage switching command and sent to the control unit of the sintering furnace.

[0109] In one embodiment of the present invention, step S5 includes the following steps:

[0110] In response to the process stage switching command, the sacrificial conductive network is oxidized and removed. After receiving the process stage switching command, the external electric field is stopped and the atmosphere of the sintering environment is adjusted, and the original inert or weak reducing gas is switched to an oxidizing gas.

[0111] Under an oxidizing atmosphere, the sintering temperature is maintained or slightly increased to a temperature at which the sacrificial conductive network material is completely oxidized into gaseous products and escapes; through this oxidation process, the three-dimensional sacrificial conductive network, which serves as a growth template, is effectively removed from the gaps in the mullite skeleton; a template-removed blank is obtained, which contains a three-dimensional interlocked mullite skeleton but is not yet fully dense.

[0112] Specifically, in response to the process stage switching command generated by the mullite framework forming inflection point recognition, the sintering control system first performs an oxidation removal process on the sacrificial conductive network. This oxidation removal process is a critical step; its function is to selectively remove the conductive network, which serves as a temporary template, through a chemical reaction, creating conditions for subsequent densification sintering and the achievement of final properties. Upon receiving the process stage switching command, the sintering control system cuts off the power supply to multiple sets of electrodes, thereby ceasing the application of the external electric field.

[0113] Adjusting the sintering atmosphere involves closing the valve supplying inert or weakly reducing gases to the sintering furnace and opening another valve to introduce an oxidizing gas. Oxidizing gases are those that provide oxygen at high temperatures, promoting oxidation reactions in other substances; examples include air, pure oxygen, or a mixture of oxygen and nitrogen. Under an oxidizing atmosphere, the system maintains the sintering temperature at its current value or slightly increases it to the preset oxidation temperature. The sintering temperature, set within the furnace during the sintering process, is a key parameter for controlling the rate of physicochemical changes within the material.

[0114] The preset oxidation temperature is based on ensuring a rapid and complete chemical reaction between the sacrificial conductive network material and the oxidizing gas, converting it into gaseous products that escape from the green body, without causing premature densification of the ceramic matrix. Gaseous products refer to the gaseous substances generated after the oxidation reaction of the sacrificial conductive network material; for example, when using carbon-based materials, the gaseous products are carbon monoxide or carbon dioxide. Through this oxidation process, the three-dimensional sacrificial conductive network, which serves as a template for mullite crystal growth, is effectively removed from the microscopic gaps in the formed mullite framework. The oxidation process refers to the chemical reaction between the sacrificial conductive network material and the oxidizing gas, transforming it into oxides.

[0115] After the processing steps are completed, the resulting green body has had its template removed. It contains a pure three-dimensional interlocking mullite framework, but the overall structure is not yet fully dense, and pores remain due to template removal. A pure three-dimensional interlocking mullite framework refers to a mullite network structure that no longer has sacrificial conductive network material attached after template removal. The template-removed green body specifically refers to the intermediate product state after the sacrificial conductive network removal step has been completed, but before final densification sintering. The template-removed green body is a porous solid containing a mullite framework network.

[0116] For example, the generated process stage switching command disconnects the 100V voltage applied to the three pairs of tungsten electrodes in the sintering control system and stops applying the external electric field. The system shuts off the argon supply at 1L / min and starts the air compressor, introducing dry air into the sintering environment as an oxidizing gas. The system increases the sintering temperature from 1150℃ to 1250℃ at a rate of 5℃ / min and holds it at this temperature, which is higher than the temperature at which carbon nanotubes are completely oxidized to CO2 gas products in air. This oxidizing atmosphere and temperature is maintained for 120 minutes. Through this oxidation process, the three-dimensional sacrificial conductive network serving as the growth template is essentially removed. After processing, a green body with the template removed is obtained, containing a pure three-dimensional interlocked mullite framework. The green body now exhibits a porous state due to the removal of carbon nanotubes.

[0117] In one embodiment of the present invention, step S6 includes the following steps:

[0118] Once it is confirmed that the template has been removed and the conductive network of the preform has been largely removed, during the oxidation removal process, the characteristic signals of the dual-mode process are continuously monitored until it is confirmed that the sacrificial conductive network has been largely removed; the overall resistance of the AC impedance spectrum undergoes an exponential jump, changing from the initial semi-conductive or conductive state to a high-impedance state that matches the insulating ceramic matrix; the intensity of the specific frequency signal related to the oxidation reaction in the acoustic emission signal falls back to the background noise level; when both conditions are met simultaneously, a template removal completion signal is generated.

[0119] Specifically, the AC impedance spectroscopy data stream is continuously analyzed to extract and track the overall resistance value, representing the overall conductivity of the green body. The overall resistance value refers to a macroscopic electrical parameter characterizing the integrity of the conductive path throughout the green body; its function is to directly reflect the existence of a conductive network. The system compares this value with a preset high impedance threshold. An exponential jump in the measured overall resistance value, characterized by multiple jumps in magnitude, signifies a rapid change in value. The first condition is met when the initial resistance, at the kiloohm level in the semi-conductive or conductive state, rapidly increases and exceeds the gigaohm level, representing the characteristics of the insulating ceramic matrix. A high impedance state refers to a material exhibiting extremely high resistance, approaching the electrical characteristics of an ideal insulator.

[0120] Simultaneously, the acoustic emission data stream is analyzed, and a digital filter separates the specific frequency signal intensity related to the oxidation reaction. This specific frequency signal intensity refers to the signal energy or amplitude within a specific frequency band in the total acoustic emission signal spectrum. This frequency band corresponds to the sound wave frequencies generated by gas escape or microstructure rupture during the oxidation reaction, serving as an indicator of whether the oxidation reaction is still ongoing. This signal intensity is compared with a pre-calibrated or real-time measured background noise level. The second condition is met when the signal intensity at the specific frequency weakens due to the end of the oxidation reaction and eventually falls to a level indistinguishable from the background noise level. The background noise level refers to the average level of stable noise output generated by the measurement system itself and the environment in the absence of a target signal source.

[0121] When both of the above conditions are met simultaneously, it is confirmed that the sacrificial conductive network has been effectively removed from the preform. The system generates a template removal completion signal, which is a clear instruction signal generated by the control system. Its function is to mark the end of the oxidation removal process and the beginning of the next process stage, and it must meet the following conditions:

[0122] Condition one, ;

[0123] Condition two, ;

[0124] in, This represents the overall resistance value of the AC impedance spectrum measured at time t. It is typically selected as the impedance modulus at a low frequency point, such as 1 Hz, and is measured in Ω. t represents time, measured in seconds (s). This is the threshold for determining a high impedance state, measured in Ω. It is based on the intrinsic resistivity of the final insulating ceramic material at the sintering temperature, and is typically set to be greater than 1. 10 9 Ω.

[0125] The value represents the intensity of a specific frequency signal associated with the oxidation reaction in the acoustic emission signal at time t, expressed in dB. It is the background noise level measured by the acoustic sensing system. The unit is the same as the signal strength. The setting is based on the background noise value obtained by calibrating the system when no response occurs.

[0126] For example, the control system continuously monitors the characteristic signals of the dual-modal process. At the start of processing, the overall resistance of the preform with the template removed is measured to be 5.2 kΩ, while the intensity of a specific frequency signal related to the oxidation reaction is 500 μV. The set high-impedance threshold is 1 GΩ, and the background noise level is 5 μV. After holding at 1250°C for 105 min, the system detects that the overall resistance jumps exponentially from several MΩ to 1.5 GΩ in a short period of time, exceeding the preset threshold. At the same time, the intensity of the specific frequency signal related to the oxidation reaction in the acoustic emission signal also decreases to 4.8 μV, which is no longer distinguishable from the background noise level. With both conditions met simultaneously, it is confirmed that the sacrificial conductive network has been substantially removed, and a high-level template removal completion signal is generated and sent to the sintering program controller.

[0127] In one embodiment of the present invention, step S7 includes the following steps:

[0128] Based on the template removal completion signal, final densification sintering is performed. After confirming that the sacrificial conductive network has been largely removed, the sintering temperature is further increased to the final vitrification temperature for high-temperature sintering of the template-removed green body. The high-temperature process causes the ceramic matrix material to melt and fill the micropores left by template removal, tightly bonding with the internal three-dimensional interlocking mullite framework. Final densification sintering refers to the final stage of sintering where high-temperature treatment causes the porous green body to shrink, pores to be eliminated, and the density to approach the theoretical value.

[0129] After heat preservation and controlled cooling, a porcelain insulator product containing a complete three-dimensional interlocking mullite reinforcement network is obtained. This network structure endows the insulator with fracture toughness that surpasses that of traditional dispersed reinforcement through crack bridging and pull-out mechanisms.

[0130] Specifically, upon receiving the signal indicating template removal is complete, the sintering control program enters the final sintering stage, instructing the heating system to continue raising the sintering temperature, increasing the furnace temperature from the oxidation removal treatment temperature to the preset final vitrification temperature. The final vitrification temperature is the sintering temperature required for the ceramic green body to achieve its maximum densification. It is set based on the chemical composition and phase diagram of the ceramic matrix material. For example, for 95% alumina ceramic, the final vitrification temperature is typically set between 1600℃ and 1700℃. At this high temperature, the ceramic matrix material in the green body where the template has been removed undergoes liquid-phase sintering. The ceramic matrix material refers to the ceramic phase that constitutes the insulator surrounding the mullite network, generated from the initial insulating ceramic raw materials through a high-temperature reaction. Some low-melting-point components melt to form a liquid phase. This liquid phase, under the action of capillary force, fills the micropores left by the removal of the sacrificial conductive network, fully wetting the surface of the formed pure three-dimensional interlocking mullite framework, reacting with it, and forming a strong interfacial bond.

[0131] Micropores refer to the interconnected tiny channels and voids left in the green body after the template has been removed due to the oxidation and removal of the sacrificial conductive network. The three-dimensional interlocking mullite reinforcement network refers to the continuous framework structure composed of mullite crystals in the final product, which serves to strengthen and toughen it. It is the final form of the framework formed during the electric field-induced growth stage after final sintering and solidification. During the holding stage, the temperature is maintained at the final vitrification temperature for a period of time to ensure that the green body is fully densified and porosity is completely eliminated. Holding refers to maintaining a constant temperature for a period of time after reaching the final vitrification temperature to ensure the sintering reaction proceeds fully.

[0132] After the heat preservation process, the system executes a controlled cooling program to gradually reduce the furnace temperature to room temperature. This is to prevent thermal stress caused by rapid temperature changes, which could lead to cracking of the finished product. Controlled cooling refers to lowering the product temperature according to a preset cooling curve. Its function is to prevent thermal shock and reduce residual stress. After this complete high-temperature treatment process, a porcelain insulator with a dense matrix and an internally complete and continuous three-dimensional interlocked mullite reinforcement network is finally obtained. The internal network structure significantly improves the fracture toughness of the insulator through crack bridging and pull-out mechanisms, making its performance superior to traditional dispersed reinforced ceramics.

[0133] Among these, dense matrix describes the final product's state attribute, indicating extremely low porosity in the ceramic matrix, typically with a relative density greater than 99%. The finished porcelain insulator is the final product, possessing excellent electrical insulation and mechanical properties. Crack bridging refers to the phenomenon where, during crack propagation, the internal reinforcing fiber network holds the crack in place, preventing it from expanding further. Pull-out mechanism refers to the partial pulling of reinforcing fibers from the matrix before fracture, increasing the material's fracture energy through frictional energy dissipation. Fracture toughness is a key mechanical property indicator measuring a material's resistance to crack propagation.

[0134] For example, the sintering control system executes the final densification sintering process, increasing the sintering temperature from 1250°C to 1650°C at a rate of 5°C / min. This is the final vitrification temperature of the alumina-based ceramic matrix material. Holding at this temperature for 2 hours allows the ceramic matrix material to fully melt and fill all micropores, tightly bonding with the internal three-dimensional interlocking mullite framework to form a three-dimensional interlocking mullite reinforcement network.

[0135] After the insulation process is completed, a controlled cooling program is initiated, slowly lowering the temperature to room temperature at a rate of 3℃ / min. This results in a fully dense porcelain insulator with a dense ceramic matrix and a uniformly distributed, complete three-dimensional interlocking mullite reinforcement network. Mechanical property testing shows that the fracture toughness of the finished porcelain insulator reaches 8.5. This is significantly higher than the 4.0 of the same material without network enhancement. This demonstrates the significant toughening effect of crack bridging and pull-out mechanisms.

[0136] See appendix Figure 2 The present invention also proposes a system for enhancing the toughness of porcelain insulators with spherical mullite, comprising the following modules:

[0137] The precursor green body preparation module is used to mix, shape, and dry the slurry of pre-dispersed conductive nanomaterials and insulating ceramic raw materials to obtain a precursor green body with a three-dimensional sacrificial conductive network embedded inside.

[0138] In the electric field-induced growth module, the precursor green body is placed in a sintering environment with multiple sets of electrodes, heated to the initial generation temperature range of mullite crystals, and a dynamically space-time alternating external electric field is applied. Micro-region electric fields are generated inside the precursor green body along a three-dimensional sacrificial conductive network, forming a preliminary three-dimensional interlocking mullite framework.

[0139] The dual-mode signal acquisition module is used to time-align electrical characteristic parameters reflecting the connectivity state of the three-dimensional sacrificial conductive network with physical signals reflecting the initial growth dynamics of the three-dimensional interlocked mullite skeleton, and fuse them into a multi-mode process characteristic signal.

[0140] The forming inflection point identification module identifies the forming inflection point of the mullite skeleton based on the multimodal process characteristic signals. When the combined event mode of the initial three-dimensional interlocking mullite skeleton growth slows down and the three-dimensional sacrificial conductive network structure is complete appears, a process stage switching instruction is generated.

[0141] The sacrificial network oxidation removal module responds to the process stage switching command, stops applying the dynamically changing external electric field and adjusts the sintering environment to an oxidizing atmosphere. The precursor green body undergoes oxidation removal treatment of the sacrificial conductive network to obtain a green body with the template removed.

[0142] The template removal confirmation module continuously monitors the multimodal process characteristic signals until it confirms that the three-dimensional sacrificial conductive network has been basically removed, and then generates a template removal completion signal.

[0143] In the final densification sintering module, based on the template removal completion signal, the template-removed blank is heated to the final vitrification temperature for densification sintering to obtain a finished porcelain insulator containing a three-dimensional interlocked mullite reinforcement network.

[0144] It should be noted that the formulas described above, through the principle of dimensional consistency and mathematical standardization methods (such as normalization, dimensionless parameter conversion, or unit system unification), can translate physical quantities with different properties into unitless standard values ​​or superimposed parameters of the same dimension. This eliminates the interference of different dimensions on the computational logic, allowing the formulas to retain the original data distribution characteristics while possessing mathematical rationality and adaptability to objective laws. The descriptions are merely exemplary embodiments of the present invention and should not be construed as limiting the scope of the invention.

[0145] Each of the modules can be implemented in whole or in part through software, hardware, or a combination thereof. It supports hardware embedded in or independent of the processor in the computer device, and also supports software stored in the memory of the computer device, so that the processor can call and execute the operations corresponding to each of the above modules.

[0146] It should be noted that the human information (including but not limited to human device information and personal information) and data (including but not limited to data used for analysis, data stored and data displayed) involved in this invention are all information and data authorized by the human body or fully authorized by all parties. The collection, use and processing of related data require relevant legal standards.

[0147] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for enhancing the toughness of porcelain insulators with spherical mullite, characterized in that, Includes the following steps: S1. The slurry of pre-dispersed conductive nanomaterials and insulating ceramic raw materials is mixed, shaped and dried to obtain a precursor green body with a three-dimensional sacrificial conductive network embedded inside. Select conductive nanomaterials with high aspect ratio for liquid phase pre-dispersion treatment; High aspect ratio conductive nanomaterials that have undergone pre-dispersion treatment are mixed with slurry of insulating ceramic raw materials. By adjusting the pH and viscosity of the slurry of insulating ceramic raw materials, the high aspect ratio conductive nanomaterials are encouraged to self-assemble into physically connected pathways during the drying process, forming a three-dimensional sacrificial conductive network. S2. The precursor green body is placed in a sintering environment with multiple sets of electrodes, heated to the initial generation temperature range of mullite crystals, and a dynamically time-space alternating external electric field is applied. Micro-region electric fields are generated inside the precursor green body along the three-dimensional sacrificial conductive network, forming a preliminary three-dimensional interlocking mullite framework. By periodically switching the activation state and electric field polarity of different electrode groups, mullite crystals are guided to undergo directional nucleation and bridging growth along the path of a three-dimensional sacrificial conductive network in three-dimensional space. Micro-field electric fields are generated inside the precursor green body along a three-dimensional sacrificial conductive network, forming a preliminary three-dimensional interlocking mullite framework; While applying an external electric field, an inert or weakly reducing gas is introduced into the sintering environment; S3. The electrical characteristic parameters reflecting the connectivity state of the three-dimensional sacrificial conductive network and the physical signals reflecting the initial growth dynamics of the three-dimensional interlocked mullite skeleton are time-aligned and fused into a multimodal process characteristic signal. S4. Based on the multimodal process characteristic signals, the mullite skeleton forming inflection point is identified. When the combined event mode of the initial three-dimensional interlocking mullite skeleton growth slows down and the three-dimensional sacrificial conductive network structure is complete appears, a process stage switching instruction is generated. S5. In response to the process stage switching command, stop applying the dynamically alternating external electric field and adjust the sintering environment to an oxidizing atmosphere. The precursor green body undergoes oxidation removal treatment of the sacrificial conductive network to obtain a green body with the template removed. S6. Continuously monitor the characteristic signals of the multimodal process until it is confirmed that the three-dimensional sacrificial conductive network has been basically removed, and then generate a template removal completion signal. S7. Based on the template removal completion signal, heat the template-removed blank to the final vitrification temperature for densification sintering to obtain a finished porcelain insulator containing a three-dimensional interlocked mullite reinforcement network.

2. The method for enhancing the toughness of porcelain insulators with spherical mullite according to claim 1, characterized in that, The process of fusing signals into a multimodal process characteristic signal includes the following steps: An impedance spectrum data stream reflecting the connectivity state of a three-dimensional sacrificial conductive network was established by measuring the global AC impedance spectrum characteristics of the precursor green body. Capture the micro-stress waves generated inside the precursor green body due to the formation and overlapping of mullite crystals, and establish an acoustic emission data stream that reflects the growth dynamics of the initial three-dimensional interlocked mullite skeleton. The impedance spectrum data stream and the acoustic emission data stream are time-aligned and fused into a multimodal process characteristic signal.

3. The method for enhancing the toughness of porcelain insulators with spherical mullite according to claim 1, characterized in that, Generating process stage switching instructions includes the following steps: Calculate the rate of change of acoustic emission event rate or cumulative energy over time in the acoustic emission data stream; Extract key characteristic frequencies and corresponding amplitudes related to the three-dimensional sacrificial conductive network structure from the impedance spectrum data stream; When the rate of change of acoustic emission event rate or cumulative energy decreases to below a preset slowing threshold, and the key characteristic frequency and corresponding amplitude remain stable within a preset time window, it is determined that a combined event pattern has been identified. Determine the inflection point of the mullite skeleton forming process and generate process stage switching instructions.

4. The method for enhancing the toughness of porcelain insulators with spherical mullite according to claim 1, characterized in that, Identifying the mullite skeleton forming inflection point based on multimodal process characteristic signals includes the following steps: The cumulative energy or event rate growth rate of the acoustic emission signal in the dual-modal process characteristic signal was monitored to begin to slow down and tend to stabilize. When the key characteristic frequencies and amplitudes of the AC impedance spectrum remain stable within the same time window, it is determined that the inflection point of mullite framework formation has been reached.

5. The method for enhancing the toughness of porcelain insulators with spherical mullite according to claim 1, characterized in that, The precursor green body undergoes an oxidative removal process to remove the sacrificial conductive network, including the following steps: The gas in the sintering environment is switched from an inert or weakly reducing gas to an oxidizing gas; The sintering temperature is maintained or increased to a preset oxidation temperature that allows the three-dimensional sacrificial conductive network material to be completely oxidized into gaseous products and escape, thereby removing the three-dimensional sacrificial conductive network from the gaps in the initial three-dimensional interlocked mullite skeleton.

6. The method for enhancing the toughness of porcelain insulators with spherical mullite according to claim 1, characterized in that, The template removal process is complete, including the following steps: The template for extracting and characterizing multimodal process features has been removed to remove the overall resistance of the billet and to separate the specific frequency signal intensity related to the oxidation reaction. When the overall resistance increases exponentially and exceeds the preset high impedance threshold, and the intensity of the specific frequency signal related to the oxidation reaction falls back to the background noise level, a template removal completion signal is generated.

7. The method for enhancing the toughness of porcelain insulators with spherical mullite according to claim 1, characterized in that, The blank, with the template removed, is heated to the final vitrification temperature for densification sintering, including the following steps: The template removes the ceramic matrix material from the green body and performs liquid phase sintering to fill the micropores left by the removal of the three-dimensional sacrificial conductive network, and forms an interface bond with the preliminary three-dimensional interlocked mullite skeleton, solidifying into a three-dimensional interlocked mullite reinforced network. After heat preservation and controlled cooling, the finished porcelain insulator is obtained.

8. A system for enhancing the toughness of porcelain insulators with spherical mullite, characterized in that, Includes the following modules: The precursor green body preparation module is used to mix, shape, and dry pre-dispersed conductive nanomaterials with slurry of insulating ceramic raw materials to obtain a precursor green body with a three-dimensional sacrificial conductive network embedded inside. Conductive nanomaterials with high aspect ratio are selected and subjected to liquid-phase pre-dispersion treatment. The pre-dispersed high aspect ratio conductive nanomaterials are mixed with slurry of insulating ceramic raw materials. By adjusting the pH and viscosity of the slurry of insulating ceramic raw materials, the high aspect ratio conductive nanomaterials are encouraged to self-assemble into physically connected pathways during the drying process to form a three-dimensional sacrificial conductive network. The electric field-induced growth module places the precursor green body in a sintering environment equipped with multiple sets of electrodes. It is heated to the initial growth temperature range of mullite crystals and a dynamically alternating external electric field is applied. Micro-fields of electric fields are generated within the precursor green body along a three-dimensional sacrificial conductive network, forming a preliminary three-dimensional interlocked mullite framework. By periodically switching the activation state and electric field polarity of different electrode sets, the mullite crystals are guided to undergo directional nucleation and bridging growth along the path of the three-dimensional sacrificial conductive network in three-dimensional space. Simultaneously with the application of the external electric field, inert or weakly reducing gases are introduced into the sintering environment. The dual-mode signal acquisition module is used to time-align electrical characteristic parameters reflecting the connectivity state of the three-dimensional sacrificial conductive network with physical signals reflecting the initial growth dynamics of the three-dimensional interlocked mullite skeleton, and fuse them into a multi-mode process characteristic signal. The forming inflection point identification module identifies the forming inflection point of the mullite skeleton based on the multimodal process characteristic signals. When the combined event mode of the initial three-dimensional interlocking mullite skeleton growth slows down and the three-dimensional sacrificial conductive network structure is complete appears, a process stage switching instruction is generated. The sacrificial network oxidation removal module responds to the process stage switching command, stops applying the dynamically changing external electric field and adjusts the sintering environment to an oxidizing atmosphere. The precursor green body undergoes oxidation removal treatment of the sacrificial conductive network to obtain a green body with the template removed. The template removal confirmation module continuously monitors the multimodal process characteristic signals until it confirms that the three-dimensional sacrificial conductive network has been basically removed, and then generates a template removal completion signal. In the final densification sintering module, based on the template removal completion signal, the template-removed blank is heated to the final vitrification temperature for densification sintering to obtain a finished porcelain insulator containing a three-dimensional interlocked mullite reinforcement network.

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