Modified zirconium boride ceramic, preparation method and application of modified zirconium boride ceramic in electrolytic aluminum

Abstract

The invention provides modified zirconium boride ceramic, a preparation method and application of the modified zirconium boride ceramic in electrolytic aluminum, and belongs to the technical field of ceramic. The preparation method comprises the following steps: preparing zirconium dioxide sol, preparing a reinforcing phase, coating and sintering. The step of preparing the zirconium dioxide sol comprises the following steps: adding a rare earth solution into a zirconium source solution, controlling the adding rate of the rare earth solution to be 1.5-2.0 g / min, stirring while adding, stirring at 42-45 DEG C for 30-35 min, stirring at 60-63 DEG C for 40-50 min, adjusting the pH to 3.2-3.5, adding polyethylene glycol 2000 after aging, and stirring for 50-60 min to obtain the zirconium dioxide sol; the prepared modified zirconium boride ceramic is high in strength, excellent in high-temperature oxidation resistance and thermal shock resistance and good in corrosion resistance, and the stability of the electrolysis process can be effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramics, and particularly relates to a modified zirconium boride ceramic, a preparation method and application thereof in electrolytic aluminum. BACKGROUND

[0002] Electrolytic aluminum is obtained by electrolysis, and is an important part of modern metallurgical industry; modern electrolytic aluminum industry usually adopts the cryolite-alumina molten electrolysis method, molten cryolite is the solvent, alumina is the solute, carbon is the anode, and aluminum liquid is the cathode; after strong direct current is introduced, electrochemical reaction is carried out at the two poles of the electrolytic cell at high temperature. However, in the traditional electrolysis process, the carbon anode is continuously oxidized and consumed during electrolysis, generating a large amount of waste gas such as carbon dioxide, which does not meet the low-carbon environmental protection requirements; and the electrolysis efficiency of the carbon anode is low, the energy consumption is high, the production stability is affected, the service life is short, and the application in electrolytic aluminum is limited.

[0003] Zirconium boride ceramic is a typical superhigh-temperature ceramic material, which has a high melting point of 3245℃, low resistivity, good electrical conductivity, and can still maintain good electrical conductivity at high temperature, meeting the electronic transmission demand in the electrolysis process; zirconium boride has good chemical inertness, and in the cryolite-alumina molten salt system, its corrosion resistance is significantly better than that of traditional carbon materials and metal alloys, which can effectively prolong the service life of the electrolytic cell and improve the electrolysis stability.

[0004] Therefore, zirconium boride ceramic is considered as one of the ideal inert anode materials, and it has important research significance to use zirconium boride ceramic in electrolytic aluminum.

[0005] However, the existing zirconium boride ceramic has the following problems in the application of electrolytic aluminum: First, the thermal shock resistance of zirconium boride ceramic is poor, and the matching degree of its thermal expansion coefficient with other parts of the electrolytic cell is low; when the temperature fluctuates during electrolysis, the ceramic is easily cracked, affecting the electrolysis process. Second, the oxidation resistance of zirconium boride ceramic is insufficient, which leads to rapid oxidation failure in a high-temperature oxidation environment, and the strength and other physical properties decrease sharply; when used in electrolytic aluminum, the wettability with molten aluminum is poor, resulting in uneven current distribution.

[0006] Therefore, it is necessary to provide a modified zirconium boride ceramic to improve the strength of zirconium boride ceramic, enhance its structural stability under various complex working conditions, improve its corrosion resistance and thermal shock resistance in the electrolytic aluminum environment, reduce the energy consumption in the electrolytic aluminum production process, improve the production efficiency, and reduce the electrode replacement frequency, so as to meet the severe requirements in the field of electrolytic aluminum.

[0007] The modification of zirconium boride ceramics in the prior art usually adopts the method of adding second phase particles, such as silicon carbide particles, to improve the strength of the ceramics; however, the interface bonding force between these particles and the zirconium boride matrix is limited, and the particles are prone to become crack sources under stress, which cannot effectively improve the overall strength of the ceramics, and even reduces the toughness of the ceramics; in the application of electrolytic aluminum, although some modification methods can improve the corrosion resistance of the ceramics to a certain extent, the modified layer will still gradually fail under the long-term action of high-temperature strong electrolyte environment, which cannot meet the demand of the electrolytic aluminum industry for low-cost and high-performance electrode materials. SUMMARY

[0008] In order to solve the technical problems existing in the prior art, the present application provides a modified zirconium boride ceramic and a preparation method, which has good strength and toughness, excellent thermal shock resistance and high-temperature oxidation resistance, good electrical conductivity, strong corrosion resistance, and can be stably applied in electrolytic aluminum for a long time.

[0009] In view of the above technical problems, the present application adopts the following technical solutions: A preparation method of a modified zirconium boride ceramic, comprising the steps of preparing a zirconium dioxide sol, preparing a reinforcing phase, coating and sintering, and the specific operation is as follows: 1. Preparation of zirconium dioxide sol Gadolinium nitrate and neodymium nitrate are added to the ethanol solution, and after uniform stirring at 30-34℃, a rare earth solution is obtained; zirconium oxychloride is added to the ethanol solution, and uniform stirring is carried out at a temperature of 60-62℃ to obtain a zirconium source solution; The mass concentration of the ethanol solution is 60-66%; In the rare earth solution, the mass ratio of the ethanol solution, gadolinium nitrate and neodymium nitrate is 200:6.5-7.0:3.0-3.5; In the zirconium source solution, the mass ratio of zirconium oxychloride and ethanol solution is 65-70:500; The rare earth solution is added to the zirconium source solution, the addition rate of the rare earth solution is controlled to be 1.5-2.0 g / min, stirring is carried out at the same time, the stirring speed is controlled to be 110-120 rpm, the temperature is controlled to be 30-34℃, after stirring is completed, the temperature is increased to 42-45℃ at a rate of 1.5-2.0℃ / min, and the temperature is maintained for 30-35 min, the temperature is increased to 60-63℃ at a rate of 1.0-1.5℃ / min, and the temperature is maintained for 40-50 min, nitric acid solution is added to adjust the pH to 3.2-3.5, aging is carried out at 60-63℃ for 2.0-2.5h, then polyethylene glycol 2000 is added, and the temperature is maintained for 50-60 min, after washing and drying, a zirconium dioxide sol is obtained; The mass ratio of the zirconium source solution, the rare earth solution and polyethylene glycol 2000 is 570:100-120:3.0-3.5; The mass concentration of the nitric acid solution is 20-25%.

[0010] 2. The preparation of the reinforcing phase The TiB2 and AlN powders are put into the pretreatment liquid for impregnation pretreatment, the pretreatment time is 1.0-1.5h, the pretreatment temperature is 45-50℃, after the pretreatment, put into the modified liquid, increase the temperature to 60-65℃ at the rate of 1.0-1.5℃ / min, keep stirring for 3.0-4.0h, after the end of the stirring, filter, wash and dry to obtain the modified mixed powder; disperse the modified mixed powder in tetrahydrofuran, after uniform dispersion, add the trimesoyl chloride solution, control the adding rate to be 1.0-1.5g / min, after the completion of the adding, keep stirring at 0-4℃ for 2.0-2.5h, after the end of the stirring, naturally restore to room temperature, continue stirring for 4.0-4.5h, centrifugal wash and dry to obtain the reinforcing phase; The particle size of the TiB2 is 120-150nm; The particle size of the AlN powder is 90-100nm; The mass ratio of the TiB2 powder, AlN powder, pretreatment liquid, modified liquid is 10-15:7-10:130-140:120-125; The mass ratio of the modified mixed powder, tetrahydrofuran, trimesoyl chloride solution is 10:80-85:50-55; The pretreatment liquid is a mixture of deionized water, dodecyl dimethyl betaine and polyvinyl alcohol, the mass ratio of the deionized water, dodecyl dimethyl betaine and polyvinyl alcohol is 100:1.5-2.0:0.5-0.8; The modified liquid is a mixture of deionized water and γ-aminopropyl triethoxysilane, the mass ratio of the deionized water and γ-aminopropyl triethoxysilane is 100:2.0-3.0; The trimesoyl chloride solution is a mixture of trimesoyl chloride and tetrahydrofuran, the mass ratio of trimesoyl chloride and tetrahydrofuran is 0.4-0.5:50.

[0011] 3. Coating Put the reinforcing phase into the zirconium dioxide sol for ultrasonic dispersion, the ultrasonic time is 30-35min, the ultrasonic power is 120-130W, the ultrasonic frequency is 30-36kHz, after the ultrasonic, increase the temperature to 72-76℃, keep stirring for 2.0-2.5h, after drying, increase the temperature to 350-360℃ at the rate of 2.0-3.0℃ / min under argon atmosphere, keep for 30-40min, then increase the temperature to 600-620℃ at the rate of 1.5-2.0℃ / min, keep for 2.0-2.2h, naturally cool to room temperature to obtain the zirconium oxide coated reinforcing phase; The mass ratio of the reinforcing phase, zirconium dioxide sol is 15-18:90-100.

[0012] 4. Sintering The zirconium boride, zirconia coated reinforcing phase, LaB6 and Y2O3 are mixed and then subjected to ball milling treatment, the ball milling time is 30-35 min, the ball milling speed is 210-220 rpm, and the ball milling ratio is 3-5:1, after the ball milling, the mixture is subjected to sintering after molding, the sintering is performed at 1200-1250 DEG C for 1.0-1.2 h, and the sintering is performed at 1810-1830 DEG C for 2.0-2.3 h, and then the sintering product is cooled to room temperature in the furnace, thereby obtaining the modified zirconium boride ceramic. The mass ratio of the zirconium boride, zirconia coated reinforcing phase, LaB6 and Y2O3 is 85-90:6-10:3-5:2-3.

[0013] A modified zirconium boride ceramic is prepared by the above method.

[0014] The modified zirconium boride ceramic prepared by the above method is used in electrolytic aluminum, which effectively promotes the electrolytic stability and improves the electrolytic efficiency.

[0015] The modified zirconium boride ceramic is prepared by using TiB2 and AlN powders as reinforcing phases to modify the zirconium boride ceramic, using zirconium oxychloride precursor to prepare zirconium dioxide sol, and doping rare earth metal ions which can be doped in the zirconium dioxide lattice, combining with polyethylene glycol to enhance the stability, inhibit the abnormal growth of the crystal grains, improve the electrical conductivity, and prevent the agglomeration of the nanoparticles; TiB2 and AlN are used as reinforcing phases, which are first subjected to surface active agent treatment and silane coupling agent treatment to further enhance the surface dispersion performance, and then the amino active sites are introduced on the surface of the powders, and then the trimesoyl chloride is used as a bridge to combine TiB2 and AlN, and to combine with the zirconium dioxide sol in the coating process, so as to realize the chemical bonding and coating of the zirconia particles on the surface of the TiB2 and AlN powders, better improve the strength and toughness of the product, relieve the mismatching problem of the thermal expansion coefficient, combine with LaB6 and Y2O3 components to realize the modification of the zirconium boride ceramic, improve the electrical conductivity, oxidation resistance and thermal shock resistance of the ceramic, enhance the corrosion resistance, improve the electrolytic efficiency, ensure the stability of the electrolysis process, and make the ceramic have high application value in electrolytic aluminum.

[0016] Compared with the prior art, the present application has the following advantages: 1. The modified zirconium boride ceramic has a bending strength of 476.7-488.5 MPa, a fracture toughness of 12.4-13.2 MPa·m 1 / 2 , and an electrical conductivity of 6.5-7.2 x 10 5S / m; 2. The modified zirconium boride ceramic of the present application has a corrosion rate of 7.3-7.7 mm / a; 3. The modified zirconium boride ceramic of the present application has a bending strength of 447.1-464.6 MPa and a fracture toughness of 11.8-12.7 MPa·m after being heated to 1300℃ at a rate of 10℃ / min and then kept for 120 h. 1 / 2 ; 4. The modified zirconium boride ceramic of the present application has a bending strength of 441.9-457.2 MPa and a fracture toughness of 11.6-12.4 MPa·m after being heated to 1200℃ at a rate of 50℃ / min in air, kept for 1.0 h, then immersed in 20℃ deionized water for 1.0 h, and the above operation is one treatment cycle, and the above operation is continuously performed for 20 treatment cycles. 1 / 2 . DETAILED DESCRIPTION

[0017] In order to more clearly understand the technical features, objectives and effects of the present application, the specific embodiments of the present application will now be described.

[0018] Example 1 1. Preparation of zirconium dioxide sol 7.0 g of gadolinium nitrate and 3.5 g of neodymium nitrate were added to 200 g of ethanol solution, and after being stirred uniformly at 34℃, a rare earth solution was obtained; 70 g of zirconium oxychloride was added to 500 g of ethanol solution, and the temperature was increased to 62℃ and stirred uniformly, obtaining a zirconium source solution; The mass concentration of the ethanol solution is 660%; 120 g of the rare earth solution was added to 570 g of the zirconium source solution, the addition rate of the rare earth solution was controlled at 2.0 g / min, and stirring was performed at the same time, the stirring speed was controlled at 120 rpm, and the temperature was controlled at 34℃, after stirring was completed, the temperature was increased to 45℃ at a rate of 1.5℃ / min, and the temperature was kept for 35 min, the temperature was increased to 63℃ at a rate of 1.5℃ / min, and the temperature was kept for 50 min, 25 wt% nitric acid solution was added to adjust the pH to 3.5, and then the temperature was kept for 2.0 h at 63℃, then 3.5 g of polyethylene glycol 2000 was added, and the temperature was kept for 60 min, and after washing and drying, a zirconium dioxide sol was obtained.

[0019] 2. Preparation of reinforcing phase Put 15g TiB2 and 10g AlN powder into 140g pretreatment liquid for impregnation pretreatment, the pretreatment time is 1.5h, the pretreatment temperature is 50℃, after the pretreatment, put into 120g modified liquid, increase the temperature to 65℃ at the rate of 1.5℃ / min, keep stirring for 4.0h, after the end of the heat preservation and stirring, filter, wash and dry to obtain modified mixed powder; disperse 10g modified mixed powder in 85g tetrahydrofuran, after uniform dispersion, add 55g trimesoyl chloride solution, control the adding rate to be 1.5g / min, after the addition is completed, keep stirring at 4℃ for 2.5h, after the end of stirring, restore to room temperature naturally, continue stirring for 4.5h, centrifugal wash and dry to obtain the reinforcing phase; The particle size of the TiB2 is 150nm; The particle size of the AlN powder is 100nm; The pretreatment liquid is a mixture of deionized water, dodecyl dimethyl betaine and polyvinyl alcohol, and the mass ratio of the deionized water, dodecyl dimethyl betaine and polyvinyl alcohol is 100:2.0:0.8; The modified liquid is a mixture of deionized water and γ-aminopropyl triethoxysilane, and the mass ratio of the deionized water and γ-aminopropyl triethoxysilane is 100:3.0; The trimesoyl chloride solution is a mixture of trimesoyl chloride and tetrahydrofuran, and the mass ratio of trimesoyl chloride and tetrahydrofuran is 0.5:50.

[0020] 3. Coating Put 18g reinforcing phase into 100g zirconia sol for ultrasonic dispersion, the ultrasonic time is 35min, the ultrasonic power is 130W, the ultrasonic frequency is 36kHz, after the ultrasonic is completed, increase the temperature to 76℃, keep stirring for 2.5h, after drying, increase the temperature to 360℃ at the rate of 3.0℃ / min under argon atmosphere, keep for 40min, then increase the temperature to 620℃ at the rate of 2.0℃ / min, keep for 2.0h, and then naturally cool to room temperature to obtain the zirconia coated reinforcing phase.

[0021] 4. Sintering Mix 90g zirconium boride, 10g zirconia coated reinforcing phase, 5g LaB6 and 3g Y2O3, and then perform ball milling treatment, the ball milling time is 35min, the ball milling rotation speed is 220rpm, and the ball to material ratio is 5:1, after the ball milling is completed, perform molding and then sintering, keep sintering at 1250℃ for 1.0h, and keep sintering at 1830℃ for 2.3h, and then cool to room temperature in the furnace to obtain modified zirconium boride ceramic.

[0022] Example 2 1. Preparation of zirconia sol Add 6.8g of gadolinium nitrate and 3.3g of neodymium nitrate to 200g of ethanol solution, stir evenly at 32℃ to obtain rare earth solution; add 67g of zirconium oxychloride to 500g of ethanol solution, raise the temperature to 62℃ and stir evenly to obtain zirconium source solution; The ethanol solution has a mass concentration of 62%. 110g of rare earth solution was added to 570g of zirconium source solution at a rate of 1.8g / min. The mixture was stirred at 120rpm and 32℃. After stirring, the temperature was increased to 43℃ at a rate of 1.5℃ / min and stirred for 35min. The temperature was then increased to 62℃ at a rate of 1.2℃ / min and stirred for 45min. The pH was adjusted to 3.3 by adding 22wt% nitric acid solution. The mixture was aged at 62℃ for 2.5h. Then, 3.3g of polyethylene glycol 2000 was added and stirred for 55min. After washing and drying, zirconium dioxide sol was obtained.

[0023] 2. Preparation of reinforcing phase 12g of TiB2 and 8g of AlN powder were impregnated in 135g of pretreatment solution for 1.2h at 45℃. After pretreatment, the powder was added to 125g of modification solution, and the temperature was increased to 62℃ at a rate of 1.2℃ / min. The mixture was kept warm and stirred for 3.5h. After stirring, the powder was filtered, washed, and dried to obtain the modified mixed powder. 10g of the modified mixed powder was dispersed in 82g of tetrahydrofuran. After uniform dispersion, 52g of trimesoyl chloride solution was added at a rate of 1.2g / min. After addition, the mixture was kept warm and stirred at 2℃ for 2.3h. After stirring, the mixture was allowed to return to room temperature and stirred for another 4.2h. After centrifugation, washing, and drying, the reinforcing phase was obtained. The TiB2 has a particle size of 130 nm; The particle size of the AlN powder is 100 nm; The pretreatment solution is a mixture of deionized water, dodecyl dimethyl betaine, and polyvinyl alcohol, wherein the mass ratio of deionized water, dodecyl dimethyl betaine, and polyvinyl alcohol is 100:1.7:0.6. The modified solution is a mixture of deionized water and γ-aminopropyltriethoxysilane, wherein the mass ratio of deionized water to γ-aminopropyltriethoxysilane is 100:2.5. The pyromellitic chloride solution is a mixture of pyromellitic chloride and tetrahydrofuran, with a mass ratio of pyromellitic chloride to tetrahydrofuran of 0.5:50.

[0024] 3. Covering Put 17 g of reinforcing phase into 100 g of zirconium dioxide sol for ultrasonic dispersion, the ultrasonic time is 30 min, the ultrasonic power is 125 W, the ultrasonic frequency is 32 kHz, after ultrasonic, the temperature is raised to 74℃, and the temperature is kept for 2.3 h, after drying, the temperature is raised to 360℃ at a rate of 2.5℃ / min under argon atmosphere, the temperature is kept for 35 min, then the temperature is raised to 610℃ at a rate of 2.0℃ / min, the temperature is kept for 2.2 h, and then the temperature is naturally cooled to room temperature, to obtain the zirconia coated reinforcing phase.

[0025] 4. Sintering After mixing 88 g of zirconium boride, 7 g of zirconia coated reinforcing phase, 4 g of LaB6, and 3 g of Y2O3, ball milling is performed, the ball milling time is 32 min, the ball milling speed is 220 rpm, the ball to material ratio is 4:1, after ball milling, after molding, sintering is performed, the temperature is kept for 1.2 h at 1230℃, the temperature is kept for 2.2 h at 1820℃, and the furnace is cooled to room temperature, to obtain the modified zirconium boride ceramic.

[0026] Example 3 1. Preparation of zirconium dioxide sol 6.5 g of gadolinium nitrate and 3.0 g of neodymium nitrate are added to 200 g of ethanol solution, and after stirring uniformly at 30℃, a rare earth solution is obtained; 65 g of zirconium oxychloride is added to 500 g of ethanol solution, and after stirring uniformly at a temperature of 60℃, a zirconium source solution is obtained; The mass concentration of the ethanol solution is 60%; 100 g of rare earth solution is added to 570 g of zirconium source solution, the addition rate of the rare earth solution is controlled to be 1.5 g / min, stirring is performed at the same time, the stirring speed is controlled to be 110 rpm, and the temperature is controlled to be 30℃, after stirring, the temperature is raised to 42℃ at a rate of 2.0℃ / min, the temperature is kept for 30 min, the temperature is raised to 60℃ at a rate of 1.0℃ / min, the temperature is kept for 40 min, 20 wt% nitric acid solution is added to adjust the pH to 3.2, aging is performed at 60℃ for 2.5 h, then 3.0 g of polyethylene glycol 2000 is added, and the temperature is kept for 50 min, after washing and drying, the zirconium dioxide sol is obtained.

[0027] 2. Preparation of reinforcing phase 10 g of TiB2and 7 g of AlN powder were put into 130 g of pretreatment liquid for impregnation pretreatment, the pretreatment time was 1.0 h, the pretreatment temperature was 50℃, after the pretreatment, it was put into 120 g of modification liquid, the temperature was increased to 60℃ at a rate of 1.0℃ / min, and it was kept stirring for 3.0 h, after the stirring, it was filtered, washed and dried to obtain modified mixed powder; 10 g of modified mixed powder was dispersed in 80 g of tetrahydrofuran, after uniform dispersion, 50 g of trimesoyl chloride solution was added, the adding rate was controlled at 1.0 g / min, after the addition was completed, it was kept stirring at 0℃ for 2.0 h, after the stirring, it was naturally restored to room temperature, and it was continuously stirred for 4.0 h, and then it was centrifuged, washed and dried to obtain the reinforcing phase; The particle size of the TiB2was 120 nm; The particle size of the AlN powder was 90 nm; The pretreatment liquid was a mixture of deionized water, dodecyl dimethyl betaine and polyvinyl alcohol, and the mass ratio of the deionized water, dodecyl dimethyl betaine and polyvinyl alcohol was 100:1.5:0.5; The modification liquid was a mixture of deionized water and γ-aminopropyl triethoxysilane, and the mass ratio of the deionized water and γ-aminopropyl triethoxysilane was 100:2.0; The trimesoyl chloride solution was a mixture of trimesoyl chloride and tetrahydrofuran, and the mass ratio of trimesoyl chloride and tetrahydrofuran was 0.4:50.

[0028] 3. Coating 15 g of the reinforcing phase was put into 90 g of zirconium dioxide sol for ultrasonic dispersion, the ultrasonic time was 30 min, the ultrasonic power was 120 W, the ultrasonic frequency was 30 kHz, after the ultrasonic, the temperature was increased to 72℃, and it was kept stirring for 2.0 h, after drying, the temperature was increased to 350℃ at a rate of 2.0℃ / min under argon atmosphere, it was kept for 30 min, then the temperature was increased to 600℃ at a rate of 1.5℃ / min, it was kept for 2.2 h, and it was naturally cooled to room temperature to obtain the zirconium oxide coated reinforcing phase.

[0029] 4. Sintering 85 g of zirconium boride, 6 g of the zirconium oxide coated reinforcing phase, 3 g of LaB6and 2 g of Y2O3were mixed and then ball milled, the ball milling time was 30 min, the ball milling rotation speed was 210 rpm, the ball to material ratio was 3:1, after the ball milling, it was shaped and then sintered, it was sintered at 1200℃ for 1.2 h and at 1810℃ for 2.0 h, and it was cooled to room temperature in the furnace to obtain modified zirconium boride ceramic.

[0030] Comparative Example 1 On the basis of Example 2, the changes were that, 1. The preparation step of zirconia sol is omitted; in the coating step, the zirconia sol is equivalent to the zirconia mixed solution, which is a mixture of zirconia and deionized water with a mass ratio of 10:90; 2. In the preparation of the reinforcing phase step, the operation step of "dispersing 10 g of modified mixed powder in 82 g of tetrahydrofuran, uniformly dispersing, then adding 52 g of trimesoyl chloride solution at a rate of 1.2 g / min, after completion of addition, 2℃ temperature holding stirring for 2.3h, after stirring, naturally restore to room temperature, continue stirring for 4.2h, centrifugal washing and drying to obtain the reinforcing phase" is omitted, and the modified mixed powder prepared is the reinforcing phase; The rest of the operations are exactly the same.

[0031] Comparative Example 2 Based on Example 2, the changes are: 1. In the preparation of zirconia sol step, the rare earth liquid component is omitted, and the rare earth liquid is replaced by zirconium source solution; 2. In the sintering step, LaB6 is replaced by zirconium boride; The rest of the operations are exactly the same.

[0032] Performance detection The modified boron zirconium ceramics prepared in Examples 1-3 and Comparative Examples 1-2 are subjected to performance detection, and the test results are as follows:

[0033] Among them, the corrosion rate is that the modified boron zirconium ceramics prepared in Examples 1-3 and Comparative Examples 1-2 are subjected to electrolysis test in a molten salt system at 1000℃, the molten salt system is NaF·AlF3+CaF2+Al2O3, the molar ratio of NaF·AlF3 is 2.0, the mass concentration of CaF2 is 5.0%, the mass concentration of Al2O3 is 5.0%, the anode current density is 1.0A / cm 2 , the electrolysis time is 48h, and the annual corrosion rate is calculated by testing the corrosion amount of 48h; The high temperature oxidation resistance performance is that the modified boron zirconium ceramics prepared in Examples 1-3 and Comparative Examples 1-2 are placed in air, the temperature is increased to 1300℃ at a rate of 10℃ / min, and the temperature is kept for 120h, and the bending strength and fracture toughness are tested again; The thermal shock resistance is that the modified boron zirconium ceramics prepared in Examples 1-3 and Comparative Examples 1-2 are placed in air environment, the temperature is increased to 1200℃ at a rate of 50℃ / min, and the temperature is kept for 1.0h, then immersed in 20℃ deionized water for 1.0h, the above operation is one treatment cycle, and after 20 treatment cycles, the bending strength and fracture toughness are tested again.

[0034] According to the results of the above table, it can be known that, in the comparative example 1, zirconium dioxide is directly added, the combination with the zirconium boride matrix is poor, the dispersion performance is not good, there are a large number of gaps in the particle combination interface, stress concentration is easy to occur when stress, the overall performance is reduced, the electron transmission resistance is increased, thus leading to poor conductive performance, poor strength and stability; in the comparative example 2, the rare earth component is omitted in the preparation of zirconium dioxide sol, thus leading to the crystal type transformation of zirconium dioxide, cracks are easy to occur in the material, the overall strength is not good, the LaB6 component is omitted, thus reducing the conductive performance, increasing the interface defects, and reducing the overall stability performance.

[0035] Unless otherwise specified, the percentages used in the present application are mass percentages.

[0036] It should be finally pointed out that: the above only describes the preferred embodiments of the present application, and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced equivalently. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing modified zirconium boride ceramic, characterized in that, This includes the steps of preparing zirconium dioxide sol, preparing the reinforcing phase, coating, and sintering; The steps for preparing zirconium dioxide sol are as follows: adding rare earth solution to zirconium source solution, controlling the addition rate of rare earth solution to 1.5-2.0 g / min, stirring while adding, stirring at 42-45℃ for 30-35 min, stirring at 60-63℃ for 40-50 min, adding nitric acid solution to adjust pH to 3.2-3.5, aging, adding polyethylene glycol 2000, stirring for 50-60 min, to obtain zirconium dioxide sol; The rare earth solution is a mixture of ethanol solution, gadolinium nitrate and neodymium nitrate; The step of preparing the reinforcing phase is as follows: TiB2 and AlN powders are sequentially added to the pretreatment solution and the modification solution and stirred to obtain a modified mixed powder; the modified mixed powder is dispersed in tetrahydrofuran, a trimesoyl chloride solution is added, and the mixture is kept at 0-4℃ and stirred for 2.0-2.5h, and then stirred at room temperature for 4.0-4.5h to obtain the reinforcing phase.

2. The method for preparing modified zirconium boride ceramic according to claim 1, characterized in that, In the step of preparing zirconium dioxide sol, the mass ratio of the zirconium source solution, rare earth solution, and polyethylene glycol 2000 is 570:100-120:3.0-3.

5. The mass concentration of the nitric acid solution is 20-25%.

3. The method for preparing modified zirconium boride ceramic according to claim 1, characterized in that, In the rare earth solution, the mass ratio of the ethanol solution, gadolinium nitrate, and neodymium nitrate is 200:6.5-7.0:3.0-3.5; The zirconium source solution is prepared by adding zirconium oxychloride to an ethanol solution and stirring until homogeneous at a temperature of 60-62°C; the mass ratio of zirconium oxychloride to ethanol solution is 65-70:

500.

4. The method for preparing modified zirconium boride ceramic according to claim 1, characterized in that, In the step of preparing the reinforcing phase, the mass ratio of the modified mixed powder, tetrahydrofuran, and trimesoyl chloride solution is 10:80-85:50-55; The pyromellitic chloride solution is a mixture of pyromellitic chloride and tetrahydrofuran, with a mass ratio of pyromellitic chloride to tetrahydrofuran of 0.4-0.5:

50.

5. The method for preparing modified zirconium boride ceramic according to claim 1, characterized in that, The step of preparing the reinforcing phase includes: immersing TiB2 and AlN powders in a pretreatment solution for 1.0-1.5 h for 15-50 °C; after pretreatment, immersing them in a modification solution and raising the temperature to 60-65 °C at a rate of 1.0-1.5 °C / min; maintaining the temperature and stirring for 3.0-4.0 h; and after maintaining the temperature and stirring, filtering, washing, and drying to obtain the modified mixed powder. The TiB2 has a particle size of 120-150 nm; The particle size of the AlN powder is 90-100 nm; The mass ratio of TiB2 powder, AlN powder, pretreatment solution, and modification solution is 10-15:7-10:130-140:120-125.

6. The method for preparing modified zirconium boride ceramic according to claim 5, characterized in that, The pretreatment solution is a mixture of deionized water, dodecyl dimethyl betaine, and polyvinyl alcohol, wherein the mass ratio of deionized water, dodecyl dimethyl betaine, and polyvinyl alcohol is 100:1.5-2.0:0.5-0.

8. The modified solution is a mixture of deionized water and γ-aminopropyltriethoxysilane, wherein the mass ratio of deionized water to γ-aminopropyltriethoxysilane is 100:2.0-3.

0.

7. The method for preparing modified zirconium boride ceramic according to claim 1, characterized in that, The coating step involves placing the reinforcing phase into a zirconium dioxide sol for ultrasonic dispersion. The ultrasonic time is 30-35 min, the ultrasonic power is 120-130 W, and the ultrasonic frequency is 30-36 kHz. After ultrasonication, the temperature is raised to 72-76℃ and stirred for 2.0-2.5 h. After drying, the temperature is raised to 350-360℃ at a rate of 2.0-3.0℃ / min under an argon atmosphere and held for 30-40 min. Then, the temperature is raised to 600-620℃ at a rate of 1.5-2.0℃ / min and held for 2.0-2.2 h. After natural cooling to room temperature, the zirconium dioxide-coated reinforcing phase is obtained. The mass ratio of the reinforcing phase to the zirconium dioxide sol is 15-18:90-100.

8. The method for preparing modified zirconium boride ceramic according to claim 1, characterized in that, The sintering step is as follows: zirconium boride, zirconium oxide-coated reinforcing phase, LaB6, and Y2O3 are mixed and then ball-milled for 30-35 minutes at a speed of 210-220 rpm and a ball-to-material ratio of 3-5:

1. After ball milling, the mixture is shaped and then sintered at 1200-1250℃ for 1.0-1.2 hours and at 1810-1830℃ for 2.0-2.3 hours. The mixture is then cooled to room temperature in the furnace to obtain modified zirconium boride ceramic. The mass ratio of the zirconium boride, zirconium oxide-coated reinforcing phase, LaB6, and Y2O3 is 85-90:6-10:3-5:2-3.

9. A modified zirconium boride ceramic, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of a modified zirconium boride ceramic in electrolytic aluminum, characterized in that, The modified zirconium boride ceramic is prepared by the preparation method according to any one of claims 1-8.

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