Preparation method of novel heat-insulation corrosion-resistant potassium titanate whisker

Abstract

The invention discloses a preparation method of a novel heat-insulating corrosion-resistant potassium titanate whisker, and relates to the technical field of preparation of potassium titanate whiskers, the preparation method comprises the following steps: S1, mixing choline chloride and urea according to a molar ratio of 1: 2, and stirring at 80 DEG C to prepare a deep eutectic solvent DES; s2, sequentially adding a titanium source, an alkali source KOH and polyvinylpyrrolidone PVP into the deep eutectic solvent DES, and carrying out ultrasonic dispersion for 10-30 minutes to form a uniform precursor mixed solution; and S3, injecting the precursor mixed solution into a microwave hydrothermal reaction kettle provided with temperature control partitions, and heating according to the following pulse microwave program. Through design of deep eutectic solvent coordination and partitioned pulse microwave heating, rapid, uniform and directional growth of the whiskers with high length-diameter ratio is realized, the problems of slow growth and non-uniform size distribution in traditional soaking are solved, the reaction period is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of potassium titanate whiskers, in particular to a method for preparing novel heat-insulating and corrosion-resistant potassium titanate whiskers. Background Art

[0002] Potassium titanate whiskers are widely used in composite thermal insulation materials, corrosion-resistant coatings, and high-temperature structural ceramics due to their high aspect ratio, excellent mechanical strength, and thermal stability. However, existing preparation processes, which often rely on traditional alkali fusion or conventional hydrothermal methods, suffer from slow growth, high energy consumption, easy agglomeration of whiskers, uneven size distribution, numerous surface defects, and limited improvement in corrosion resistance.

[0003] Patent CN106048727B discloses a method for preparing potassium hexatitanate whiskers in one step by combustion. The above patent realizes a one-step direct synthesis with a simple method, low raw material price, short synthesis time and high efficiency.

[0004] The above patent improves the shortcomings of the multi-step method by adding fuel and combustion aid to provide the prerequisites for the reaction, and directly synthesizes through a one-step method. The method is simple, the raw materials are cheap, the synthesis time is short, and the efficiency is high, laying the foundation for the development of fields such as building materials and the automotive industry. However, the traditional homogenization preparation method has technical problems such as slow growth and uneven size distribution.

[0005] To this end, the present application proposes a method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker that can achieve rapid, uniform, and directional growth of high aspect ratio whiskers. Summary of the Invention

[0006] The purpose of the present invention is to provide a novel method for preparing heat-insulating and corrosion-resistant potassium titanate whiskers to solve the technical problems of slow uniform growth and uneven size distribution proposed in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker, the preparation method comprising the following steps: Step S1, mixing choline chloride and urea in a molar ratio of 1:2, and stirring at 80° C. to prepare a deep eutectic solvent DES; Step S2: adding a titanium source, an alkali source KOH, and polyvinylpyrrolidone (PVP) to the obtained deep eutectic solvent DES in sequence, and performing ultrasonic dispersion for 10-30 minutes to form a uniform precursor mixture; Step S3: inject the precursor mixture into a microwave hydrothermal reactor with temperature control zones and heat it according to the following pulse microwave program: Heat at 180°C for 10 minutes - cool to 100-200°C and heat again for 20 minutes; Each stage adopts microwave pulse control with a cycle of 5 min heating at 800 W and 2 min rest; Step S4: After the reaction is completed, the pressure is released, and the obtained product is washed alternately with deionized water and anhydrous ethanol three times, and finally vacuum-dried at 100° C. for 12 hours to obtain potassium titanate whiskers with a high aspect ratio.

[0008] Preferably, in step S2, a rare earth metal salt having a mass fraction of 0.5-2.0 wt% is added, wherein the rare earth metal salt is selected from one of lanthanum nitrate La(NO3)3, cerium nitrate Ce(NO3)3 and corresponding soluble complexes, so that La 3+ or La 3+ Doping into titanate crystals can induce lattice distortion and form defect-stabilized regions, thereby enhancing the structural stability and dissolution resistance of the whiskers in acidic and alkaline environments.

[0009] Preferably, the pH value of the initial mixed solution is controlled to be 12.5-13.5 during the reaction process, and is adjusted by precisely adding NaOH or HNO3 to promote the directional growth of whiskers along the

[001] crystal direction and suppress the dendrite structure.

[0010] Preferably, the microwave hydrothermal reactor is a pipeline continuous flow system, which is equipped with three temperature control areas: a preheating zone, a microwave pulse reaction zone and a cooling zone. The temperature of each section is controlled by a PLC intelligent temperature control system. The precursor liquid flows continuously at a flow rate of 1-5 mL / min to ensure the consistency of product crystallinity and size distribution.

[0011] Preferably, the amount of polyvinylpyrrolidone (PVP) is 1.0-1.5 wt % of the total mass of the titanium source, which plays a dual role of surface coating and growth regulation, preventing whisker agglomeration and dendrite deformity formation.

[0012] Preferably, the deep eutectic solvent DES is recovered by thermal desorption at 95° C. + vacuum concentration after the reaction is completed. The recovered choline chloride is mixed with urea and can be reused ≥5 times. After each recovery, the solvent purity is maintained above 95%, and the whisker quality does not significantly decrease.

[0013] Preferably, the microscopic size of the potassium titanate whiskers is controlled to be 0.2-0.5 μm in diameter, 10-30 μm in length, with an aspect ratio greater than 40, and has a high crystallinity single crystal structure. The XRD spectrum shows pure phase potassium titanate K2Ti6O 13 Or K2Ti4O9, TEM observation shows no obvious crystal defects.

[0014] Preferably, after drying, the potassium titanate whiskers can be further immersed in an ethanol solution containing 1 wt% of γ-methacryloxypropyltrimethoxysilane at room temperature for 30 minutes, and then heat-treated at 120°C for 2 hours to form a surface hydrophobic organic silicon protective film, thereby improving the interface bonding strength and dispersibility between the potassium titanate whiskers and the organic polymer composite material.

[0015] Preferably, the thermal conductivity of the material used to prepare the potassium titanate whiskers is ≤1.8W·m -1 ·K -1 , and in 1 mol·L -1 After immersion in HCL or NaOH solution for 24 hours, the mass loss rate does not exceed 2wt%, showing excellent thermal insulation and acid and alkali corrosion resistance.

[0016] Preferably, the preparation method is suitable for industrial continuous production with an annual output of not less than 10 kg, and the specific surface area of the product is 10-15 m 2 / g, with high whisker distribution density and low agglomeration rate, it is suitable for high-end application scenarios of high-performance composite thermal insulation coatings and structural ceramic toughening fillers.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention achieves rapid and uniform directional growth of high aspect ratio whiskers by designing deep eutectic solvent coordination and zoned pulse microwave heating, solving the problems of slow growth and uneven size distribution in traditional uniform heating, shortening the reaction cycle and improving production efficiency. 2. The present invention improves the whisker's resistance to acid and alkali dissolution by designing a directional doping with rare earth particles to induce lattice distortion, thereby solving the problems of whisker surface defects and poor corrosion resistance, reducing the immersion loss rate, and improving single-phase crystallinity; 3. The present invention adopts a three-stage continuous flow microwave hydrothermal reactor to achieve dimensional consistency and batch stability during production, solve the problem of agglomeration and fluctuation caused by uneven heating in batch reactions, and improve continuous output rate; 4. The present invention enhances the hydrophobicity of the whiskers and the composite interface bonding strength by designing the functionalization of the silicone surface, solves the problems of poor interface adhesion between the whiskers and the organic matrix and unstable dispersion, improves the dispersion stability of the whiskers, and reduces thermal conductivity. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0019] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like, which indicate positions or locations, are based on these positions and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood in a broad sense. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a mechanical connection or an electrical connection; it may refer to a direct connection or an indirect connection through an intermediate medium; it may refer to internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0021] An embodiment of the present invention provides a method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker, the method comprising the following steps: Step S1, mixing choline chloride and urea in a molar ratio of 1:2, and stirring at 80° C. to prepare a deep eutectic solvent DES; Step S2: adding a titanium source, an alkali source KOH, and polyvinylpyrrolidone (PVP) to the obtained deep eutectic solvent DES in sequence, and performing ultrasonic dispersion for 10-30 minutes to form a uniform precursor mixture; Step S3: inject the precursor mixture into a microwave hydrothermal reactor with temperature control zones and heat it according to the following pulse microwave program: Heat at 180°C for 10 minutes - cool to 100-200°C and heat again for 20 minutes; Each stage adopts microwave pulse control with a cycle of 5 min heating at 800 W and 2 min rest; Step S4: releasing the pressure after the reaction is completed, washing the obtained product three times with deionized water and anhydrous ethanol alternately, and finally drying it in vacuum at 100° C. for 12 hours to obtain potassium titanate whiskers with a high aspect ratio; Further, raw materials: choline chloride ChCl, analytical grade, 50.0g; urea Urea, analytical grade, 60.0g; tetrabutoxytitanium Ti(OBu)4, industrial grade, 10.0g; potassium hydroxide KOH, anhydrous, 8.0g, polyvinylpyrrolidone PVP, M w ≈10 000, 1.2 g; appropriate amounts of deionized water and anhydrous ethanol; Step S1: Preparation of deep eutectic solvent DES: In a reaction vessel equipped with mechanical stirring and temperature control, 50.0 g of ChCl and 60.0 g of urea were weighed, respectively. The mixture was heated to 80°C and stirred at 300 rpm for 1 h until the system was completely clear and transparent. The heating was turned off, and the mixture was continued to stir at 200 rpm and cooled to room temperature to obtain a uniform DES (approximately 110 mL). Step S2: Prepare a precursor mixture: Slowly add 410.0 g of Ti(OBu) dropwise to degassed (vacuumed for 10 min) DES while stirring at 400 rpm. Add 8.0 g of KOH and continue stirring for 5 min. Weigh 1.2 g of PVP and add it in three portions, ensuring uniform stirring after each addition. Place the resulting mixture in an ultrasonic cleaner (40 kHz, 200 W) for 20 min, controlling the temperature to <40°C, to produce a transparent and uniform precursor mixture (approximately 120 mL). Step S3: Pulsed microwave hydrothermal synthesis: The precursor mixture was injected into a microwave hydrothermal reactor with a PTFE liner (volume 150 mL), ensuring that the liquid level was below 2 / 3 of the liner. The reactor was placed in a microwave synthesizer (specifications: 2.45 GHz, maximum power 1000 W, with PLC zone temperature control). The pulse microwave program was set as follows: first stage: heating to 180°C, holding for 10 min (alternating cycle of 5 min microwave at 800 W → 2 min stop), natural cooling to 100°C, lasting about 8 min; second stage: heating again to 200°C, holding for 20 min (also using a 5 min / 2 min pulse mode). The entire reaction process took a total of approximately 45 min, and the maximum internal pressure was approximately 2.5 MPa. Step S4: separation, washing, and drying: After the reaction is completed, wait for the system to naturally depressurize to normal pressure, slowly open the lid to take out the reaction slurry, centrifuge at 5000 rpm for 5 min, discard the supernatant, and wash alternately with deionized water (50 mL) and anhydrous ethanol (50 mL) for a total of 3 rounds, each round of ultrasonic-assisted dispersion for 5 min and centrifugation (5000 rpm × 5 min), transfer the wet powder to a vacuum drying oven, and dry it at 100°C and <10 kPa for 12 h to obtain a white loose powder.

[0022] An embodiment of the present invention provides a method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker, wherein in step S2, a rare earth metal salt having a mass fraction of 0.5-2.0 wt% is added, and the rare earth metal salt is selected from one of lanthanum nitrate La(NO3)3, cerium nitrate Ce(NO3)3 and a corresponding soluble complex, so that La 3+ or La 3+ Doping into titanate crystals to induce lattice distortion and form defect-stable regions, thereby enhancing the structural stability and dissolution resistance of the whiskers in acidic and alkaline environments; During the reaction, the pH value of the initial mixed solution is controlled to be 12.5-13.5, and is adjusted by precisely adding NaOH or HNO3 to promote the directional growth of whiskers along the

[001] crystal direction and inhibit the dendrite structure; Furthermore, the raw materials and proportions are as follows: rare earth dopant: lanthanum nitrate hexahydrate La(NO3)3·6H2O: mass 0.12 g, or can be replaced by cerium nitrate hexahydrate Ce(NO3)3·6H2O, the amount is the same as above; pH adjustment reagent: 1 mol / L sodium hydroxide solution and 1 mol / L hydrochloric acid solution; Weigh and dissolve: Place La(NO3)3·6H2O in a small beaker, add about 5mL of deionized water, and stir gently to dissolve it completely to obtain La 3+ The rare earth salt solution was slowly added dropwise to the degassed DES while stirring at 400 rpm to allow La 3+ Dispersed evenly in the DES phase; Add other precursors: According to the order of S2 in Example 1, add in sequence: Ti(OBu) 410.0 g, KOH 8.0 g, PVP 1.2 g (add in three times), stirring for 3-5 minutes after each addition; Initial pH measurement and adjustment: Take 5 mL of the mixed solution in a clean small beaker and measure the initial pH with a calibrated precision pH meter. If the pH is less than 12.5, use a pipette to add 1 mol / L NaOH to the sample solution in batches, stir after each drop and re-measure until the pH reaches the range of 12.5-13.5. If the pH is greater than 13.5, use 1 mol / L HNO3 to accurately add dropwise to the required range. After completing the pH adjustment, inject the adjusted sample solution back into the main reaction mixture in a ratio (about 1:23) and stir evenly. Ultrasonic dispersion: Place the entire precursor mixture into an ultrasonic cleaning machine, control the temperature to <40°C, and process for 20 minutes to make the solution clear and transparent without precipitation; Subsequent microwave reaction: follow steps S3-S4 in Example 1: pulsed microwave hydrothermal synthesis ➡ washing ➡ drying, and finally obtain rare earth doped and pH-optimized potassium titanate whiskers; By introducing 0.5-2.0 wt% of La3+ or Ce3+ in step S2 of Example 1 and precisely controlling the pH of the precursor solution at 12.5-13.5, lattice distortion can be effectively induced, a stable defect region can be formed, the solubility resistance in acidic and alkaline environments can be improved, the chemical environment of the solution can be optimized, the orderly growth of whiskers along the

[001] direction can be promoted, and dendrites can be significantly inhibited.

[0023] An embodiment provided by the present invention provides a method for preparing novel heat-insulating and corrosion-resistant potassium titanate whiskers. The microwave hydrothermal reactor is a pipeline-type continuous flow system having three temperature-controlled zones: a preheating zone, a microwave pulse reaction zone, and a cooling zone. The temperature of each zone is controlled by a PLC intelligent temperature control system. The precursor solution flows continuously at a flow rate of 1-5 mL / min to ensure the consistency of the product crystallinity and size distribution. The amount of polyvinylpyrrolidone (PVP) is 1.0-1.5 wt% of the total mass of the titanium source, which plays a dual role of surface coating and growth regulation, preventing whisker agglomeration and dendrite deformity. Further, equipment and system parameters are as follows: Pipeline continuous flow reactor: Reaction tube material: 316L stainless steel lined with PTFE, inner diameter 6mm, total length 3m; Segmented layout: Preheating zone: 0.6m long, set temperature 120°C; Microwave pulse reaction zone: 1.5m long, two-stage temperature control sections set at 180°C and 200°C; Cooling zone: 0.9m long, set temperature 100°C; Microwave head configuration: Four microwave feeders installed around the outside of the reaction zone, each with a maximum output of 250W; PLC intelligent temperature control: equipped with thermocouples and PID control, temperature accuracy of ±1°C, real-time recording and feedback to the main control; Delivery system: Cross-flow peristaltic pump: Model BT100-2J, with 0.8mm tubing, adjustable flow rate 1.0-5.0mL / min; Solution displacement valve and backpressure valve: maintain the pressure in the pipeline at 2.0-2.7MPa to ensure stable liquid flow. Weigh 1.2 g of PVP and dissolve it in 20 mL of deionized water. Magnetic stirring was performed at room temperature for 15 min to obtain a 6 wt% PVP aqueous solution. Before ultrasonic dispersion in step S2, the above PVP solution was added to the DES / Ti solution system in three equal amounts. Stir for 3-5 min after each addition. After the addition was completed, ultrasonic treatment was performed for 20 min to ensure that the PVP evenly coated the surface of the precursor particles to form a stable core-shell structure. The precursor mixture containing PVP was transported to the preheating zone through a peristaltic pump at a flow rate of 3.0 mL / min. The fluid in the tube stayed at 120°C for about 40 seconds to achieve initial temperature rise and homogenization of the solution; the first section (180°C): after the fluid entered the first microwave zone, the PLC controlled the microwave to circulate with 5 minutes of power on and 2 minutes of intermittent power, which was equivalent to 10 minutes of power on; the second section (200°C): the fluid naturally transitioned to the second section and again carried out a 5 minutes of power on and 2 minutes of intermittent power off cycle, which was equivalent to 20 minutes of power on; PLC feedback: the temperature was sampled every 10 seconds, and the microwave power was automatically adjusted to maintain the set temperature; the product flowed into the cooling zone and maintained at 100°C for 60 seconds to prevent rapid cooling and cracking. After cooling, it flowed out of the pipeline, was reduced to normal pressure by the back pressure valve, and was collected in a 500 mL receiving bottle.

[0024] An embodiment provided by the present invention is a method for preparing novel heat-insulating and corrosion-resistant potassium titanate whiskers. The deep eutectic solvent DES is recovered by thermal desorption at 95°C and vacuum concentration after the reaction. The recovered choline chloride is mixed with urea and can be reused ≥5 times. After each recovery, the solvent purity is maintained above 95%, and the whisker quality does not significantly decrease. The micro-size of the potassium titanate whisker is controlled to be 0.2-0.5 μm in diameter, 10-30 μm in length, with an aspect ratio greater than 40, and has a high crystallinity single crystal structure. The XRD spectrum shows pure phase potassium titanate K2Ti6O 13 or K2Ti4O9, no obvious crystal defects were observed by TEM; After drying, the potassium titanate whiskers can be further immersed in an ethanol solution containing 1 wt% of γ-methacryloxypropyltrimethoxysilane at room temperature for 30 minutes, and then heat-treated at 120° C. for 2 hours to form a surface hydrophobic organic silicon protective film, thereby improving the interfacial bonding strength and dispersibility of the potassium titanate whiskers and the organic polymer composite material; Furthermore, before the reaction was completed and the whiskers were collected, the remaining liquid in the reactor was transferred to a high-temperature resistant glass evaporator through a corrosion-resistant valve. The collected liquid was heated to 95°C in an oil bath with a reflux device and maintained for 2 hours to evaporate most of the water and residual ethanol, while promoting the precipitation of volatile organic impurities in the DES. Subsequently, the pretreated solution was transferred to a rotary evaporator, the vacuum was adjusted to <10 kPa, and the water bath temperature was maintained at 95°C. The remaining water was evaporated until the solvent volume was reduced to approximately 20% of the initial volume. After cooling, the distillation residue was collected to obtain an enriched mixture of ChCl and Urea. The recovered DES sample was taken and determined by nuclear magnetic resonance and ion chromatography to ensure that the ChCl and Urea contents remained above 95% of the original DES and the impurity content was less than 5%. If the purity dropped slightly (<2%), the corresponding amount of ChCl and Urea was supplemented at the original 1:2 molar ratio to restore the original volume to the initial specifications. The above recovery-compensation operation was repeated 5 times, and the DES after each recovery was used to prepare the precursor solution and prepare whiskers. Preparation of silicone protective film on the surface of silane coupling agent: Weigh 0.10 g of γ-methacryloxypropyltrimethoxysilane and 10 mL of anhydrous ethanol, stir ultrasonically for 5 minutes to prepare a uniform solution, place the vacuum-dried whiskers in a three-necked flask, add the above-mentioned silane solution, and soak them under magnetic stirring at room temperature for 30 minutes to allow the silane molecules to self-assemble on the whisker surface; after the soaking, filter out the mixture and gently shake off the excess solution, place the wet whiskers in an oven, dry and cure at 120°C for 2 hours, so that the γ-methacryloxypropyltrimethoxysilane undergoes condensation to form a dense silicone protective layer; contact angle test: the whiskers before and after modification were pressed into a sheet, and the water contact angle was measured to increase from the original 20°±2° to 110°±3°, indicating that the surface has been successfully hydrophobized; FTIR spectrum test: at 1100 cm -1 The Si-0-Si stretching peak appears at 1720 cm -1 The C=O stretching peak appears at the position of the modified whiskers, proving the existence of the silane layer. Composite dispersion: The whiskers before and after modification were added to the epoxy resin respectively and left to stand for 24 hours. It was observed that the modified sample had almost no sedimentation and was dispersed stably.

[0025] An embodiment of the present invention provides a method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker, wherein the thermal conductivity of the material used to prepare the potassium titanate whisker is ≤1.8W·m -1 ·K -1 , and in 1 mol·L -1 The mass loss rate after immersion in HCL or NaOH solution for 24 hours does not exceed 2wt%, showing excellent thermal insulation and acid and alkali corrosion resistance; The preparation method is suitable for industrial continuous production with an annual output of not less than 10 kilograms, and the specific surface area of the product is 10-15m 2 / g, with high whisker distribution density and low agglomeration rate, it is suitable for high-end application scenarios such as high-performance composite thermal insulation coatings and structural ceramic toughening fillers; Further, performance testing and industrial continuous production verification: Thermal conductivity test: Vacuum-dried potassium titanate whisker powder was loaded onto a polytetrafluoroethylene pellet at a 20 wt% loading rate. The pellet had a diameter of 25 mm, a thickness of 2 mm, and a total mass of approximately 0.5 g. The pellet was then placed in a thermostat for 24 hours to allow the sample to reach moisture equilibrium. Test conditions included: instrument: HotDisk TPS 2500S; probe: 10 mm diameter flat probe; applied power: 100 mW; test environment: room temperature, relative humidity: 50%. The probe was sandwiched between two identical sample pellets, and three sets of repeated tests were performed. The measured thermal conductivities were 1.62, 1.68, and 1.65 W·m, respectively. -1 ·K -1 , average value 1.65W·m -1 ·K -1 , meeting ≤1.8W·m-1 ·K -1 requirements; Acid and alkali corrosion resistance: Accurately weigh 0.2000 g of dry whisker powder and mark it as “preliminary weight”. Place the whiskers of “preliminary weight” in a 100 mL flask and add 100 mL of 1.0 mol·L -1 The whiskers were immersed in HCl solution and NaOH solution in a constant temperature oscillating box at 25°C and 150 rpm for 24 hours. After immersion, the whiskers were recovered by centrifugation (5000 rpm × 5 min), rinsed with deionized water three times and ethanol once, and vacuum dried (100°C, 12 hours). The "after weight" was weighed, and the mass loss rate = (before weight - after weight) / before weight × 100%. The loss rates of the HCl group were 1.7%, 1.6%, and 1.8%, respectively, with an average of 1.7%. The loss rates of the NaOH group were 1.5%, 1.6%, and 1.7%, respectively, with an average of 1.6%. All of them were ≤2.0wt%, meeting the requirements. Specific surface area determination (mercury porosimetry): About 1.0 g of dry whisker powder was dried in vacuum at 120°C for 2 h and placed in the sample cell of a mercury intrusion porosimeter. The instrument was AutoPore IV 9510, with a pressure range of 0.1-400 MPa and a surface tension of liquid mercury of 0.484 N·m. -1 , contact angle: 130°; calculated by inversion of the cumulative pore volume curve, the specific surface area is 11.8m 2 / g, multiple measurements have resulted in a range of 10.5-13.2m 2 / g, uniform and stable; Industrial continuous production verification: Equipment: Pipeline continuous flow microwave hydrothermal system, flow rate: 3.0 mL / min, operation time: 24 hours continuously, cumulative precursor solution usage: 4.32 L; a total of 40.0 g of whiskers were recovered. Based on the theoretical mass of Ti(OBu)4 (10 g Ti(OBu)4 ➡ 9.2 g whiskers), an annual production of ≥ 10 kg is easily achievable, requiring only approximately 600 hours of continuous operation of a single machine. Samples were taken at 2 hours, 12 hours, and 24 hours, and the following measurements were made: Thermal conductivity deviation <3%, mass loss rate deviation <0.2wt%, specific surface area deviation <0.5m 2 / g; The obtained whiskers were added as 15wt% filler into epoxy matrix to prepare composite thermal insulation coating. After curing at 140℃, thermal conductivity and corrosion resistance tests were conducted. The results showed that the thermal conductivity of the coating was reduced by more than 20%. -1 There was no obvious peeling or swelling of the coating substrate in the HCl or NaOH environment.

[0026] Working Principle: Choline chloride and urea in the deep eutectic solvent DES form a highly polar grid structure, which can coordinate with titanium sources such as tetrabutoxytitanium, while carrying KOH, PVP and rare earth particles. Under the action of ultrasound, each component is fully dispersed and evenly coordinated in the solution, laying the foundation for the subsequent uniform formation of crystal nuclei. In a zoned temperature-controlled pipeline reactor, the precursor solution sequentially passes through a 180°C microwave pulse segment for 10 minutes and a 120°C microwave pulse segment for 20 minutes. The preferential excitation of the Ti-O bond by the microwave field combined with precise temperature control enables the rapid directional growth of the crystal nucleus along the

[001] crystal direction. At the same time, rare earth doping induces lattice distortion, suppressing dendrites and agglomeration. The fluid is cooled in a 100°C cooling zone and then discharged from the autoclave. Residual DES and organic matter are removed by centrifugal washing, and high aspect ratio whiskers are obtained by vacuum drying. Subsequently, the whiskers are impregnated with a γ-silane coupling agent and thermally cured to form a stable hydrophobic organic protective layer on the surface, which imparts excellent dispersibility and composite interface bonding properties.

[0027] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker, characterized by: The preparation method comprises the following steps: Step S1, mixing choline chloride and urea in a molar ratio of 1:2, and stirring at 80° C. to prepare a deep eutectic solvent DES; Step S2: adding a titanium source, an alkali source KOH, and polyvinylpyrrolidone (PVP) to the obtained deep eutectic solvent DES in sequence, and performing ultrasonic dispersion for 10-30 minutes to form a uniform precursor mixture; Step S3: inject the precursor mixture into a microwave hydrothermal reactor with temperature control zones and heat it according to the following pulse microwave program: Heat at 180°C for 10 minutes - cool to 100-200°C and heat again for 20 minutes; Each stage adopts microwave pulse control with a cycle of 5 min heating at 800 W and 2 min rest; Step S4: After the reaction is completed, the pressure is released, and the obtained product is washed alternately with deionized water and anhydrous ethanol three times, and finally vacuum-dried at 100° C. for 12 hours to obtain potassium titanate whiskers with a high aspect ratio.

2. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, wherein: In the step S2, a rare earth metal salt with a mass fraction of 0.5-2.0 wt% is added, and the rare earth metal salt is selected from one of lanthanum nitrate La(NO3)3, cerium nitrate Ce(NO3)3 and corresponding soluble complexes, so that La 3+ or La 3+ Doping into titanate crystals can induce lattice distortion and form defect-stabilized regions, thereby enhancing the structural stability and dissolution resistance of the whiskers in acidic and alkaline environments.

3. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, characterized in that: During the reaction, the pH value of the initial mixed solution is controlled to be 12.5-13.5 and is adjusted by precisely adding NaOH or HNO3 to promote the directional growth of whiskers along the [001] crystal direction and inhibit the dendrite structure.

4. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, characterized in that: The microwave hydrothermal reactor is a pipeline-type continuous flow system with three temperature-controlled areas: a preheating zone, a microwave pulse reaction zone, and a cooling zone. The temperature of each zone is controlled by a PLC intelligent temperature control system. The precursor solution flows continuously at a flow rate of 1-5 mL / min to ensure the consistency of the product crystallinity and size distribution.

5. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, characterized in that: The amount of polyvinyl pyrrolidone (PVP) used is 1.0-1.5 wt % of the total mass of the titanium source, which plays a dual role of surface coating and growth regulation, preventing whisker agglomeration and dendrite deformity.

6. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, characterized in that: The deep eutectic solvent DES is recovered by thermal desorption at 95° C. and vacuum concentration after the reaction. The recovered choline chloride is mixed with urea and can be reused for ≥5 times. The solvent purity is maintained above 95% after each recovery, and the whisker quality does not significantly decrease.

7. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, characterized in that: The micro-size of the potassium titanate whisker is controlled to be 0.2-0.5 μm in diameter, 10-30 μm in length, with an aspect ratio greater than 40, and has a high crystallinity single crystal structure. The XRD spectrum shows pure phase potassium titanate K2Ti6O 13 Or K2Ti4O9, TEM observation shows no obvious crystal defects.

8. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, characterized in that: After drying, the potassium titanate whiskers can be further immersed in an ethanol solution containing 1 wt% of γ-methacryloxypropyltrimethoxysilane at room temperature for 30 minutes, and then heat-treated at 120°C for 2 hours to form a surface hydrophobic silicone protective film, thereby improving the interfacial bonding strength and dispersibility of the potassium titanate whiskers and the organic polymer composite material.

9. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, characterized in that: The thermal conductivity of the material used to prepare the potassium titanate whiskers is ≤1.8W·m -1 ·K -1 , and in 1 mol·L -1 After immersion in HCL or NaOH solution for 24 hours, the mass loss rate does not exceed 2wt%, showing excellent thermal insulation and acid and alkali corrosion resistance.

10. The method for preparing a novel heat-insulating and corrosion-resistant potassium titanate whisker according to claim 1, characterized in that: The preparation method is suitable for industrial continuous production with an annual output of not less than 10 kilograms, and the specific surface area of the product is 10-15m 2 / g, with high whisker distribution density and low agglomeration rate, it is suitable for high-end application scenarios of high-performance composite thermal insulation coatings and structural ceramic toughening fillers.