High-resistance, high-thermal-shock-resistant ceramic material for nuclear waste treatment and method for producing the same

Abstract

The application belongs to the technical field of ceramic materials for nuclear waste treatment, and discloses a high-resistance and strong thermal shock ceramic material for nuclear waste treatment and a preparation method thereof. An aluminum-chromium eutectic body and chromium oxide powder are added into a binder and deionized water, and a granulating method is used to prepare aluminum-chromium eutectic body granules with a large number of small closed pores. Then, the aluminum-chromium eutectic body granules are blended with raw materials such as fused electric chromium oxide, zirconium oxide, alpha-aluminum oxide, rho-aluminum oxide, and silicon dioxide superfine powder, and are formed into a high-temperature composite ceramic material with high resistance, low thermal conductivity and strong thermal shock through volume static pressure forming or casting forming, and the high-temperature composite ceramic material is prepared after high-temperature sintering. The high-temperature composite ceramic material is applied to a nuclear waste high-level liquid waste glass solidification electric heating ceramic furnace working lining, and effectively prolongs the service life of the working lining.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic materials for nuclear waste treatment, and particularly relates to a high-resistance and strong thermal shock ceramic material for nuclear waste treatment and a preparation method thereof. BACKGROUND

[0002] Nuclear energy is a kind of efficient energy with high energy density. In the development and application of nuclear technology, the treatment of nuclear waste left by nuclear energy is a thorny problem with great difficulty, heavy pollution and easy leakage, which has become an important problem restricting the development of nuclear energy. High-level waste contains radioactive nuclides such as neptunium, plutonium, americium, technetium, iodine, strontium and cesium. Its main characteristics are high radiation level, long half-life period, high nuclide toxicity and heat generation, etc. The specific activity of high-level waste and liquid waste reaches 3.7*109 Bq / L. The half-life of neptunium-237 and plutonium-239 is more than 100,000 years, and they cannot be degraded or eliminated by ordinary physical, chemical or biological methods. They can only rely on their own radioactive decay to gradually reduce their harm. How to store and treat these waste liquids is very important for the safe application of nuclear energy.

[0003] Glass solidification technology is the only high-level waste liquid treatment technology that has been industrialized and applied. Glass solidification technology is to mix high-level waste liquid and glass raw materials for melting and dissolution, and to form a glass body after cooling. The glass body has low leaching rate and high strength. The radioactive nuclides are contained in the stable glass substrate. Most of the radioactive elements are solidified in the crystal lattice. The waste without radioactivity and a small amount of elements not solidified in the crystal lattice are solidified in the outer glass substrate. It can effectively contain radioactive substances and form a stable form, realize the conversion of waste liquid into solid, and greatly improve the safety of storage, meeting the requirements of long-term stable storage of high-level waste liquid.

[0004] The electric heating ceramic furnace is the core engineering equipment of high-level liquid glass solidification engineering technology. In order to meet the needs of nuclear waste high-level liquid glass solidification, the refractory material, electrode material and kiln structure design in the electric heating ceramic furnace need to have high efficiency, long service life and long-term stable operation. In particular, the manufacture of the refractory material lining has been a technical barrier to the localization of glass solidification technology, which seriously restricts the progress of nuclear waste treatment technology in China. The electric heating ceramic furnace has a harsh working environment, which is impacted and eroded by nuclides and high temperature. The service life of the electric heating melting furnace working lining used for nuclear waste glass solidification treatment is extremely short, which affects the normal operation of the whole furnace body. Therefore, it is of great significance to develop a high-performance ceramic material with high resistance, strong thermal shock and low thermal conductivity for nuclear waste high-level liquid glass solidification electric heating ceramic furnace working lining, which can promote the safety and sustainable development of China's nuclear energy industry. SUMMARY

[0005] The present application provides a high-resistance and strong thermal shock ceramic material for nuclear waste treatment and a preparation method thereof, and solves the problems of short service life of the working lining of the electric heating melting furnace for nuclear waste glass solidification treatment.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows: a high-resistance and strong thermal shock ceramic material for nuclear waste treatment, the raw material includes the following components in parts by weight: 68-70 parts of aluminum-chromium eutectic granulated material, 5-6 parts of electrically fused chromium oxide, 4 parts of zirconium oxide micro powder, 3-9 parts of alpha-aluminum oxide, 8 parts of rho-aluminum oxide, 2-4 parts of ultra-fine silicon dioxide powder, 6-12 parts of aluminum sol, 0-4 parts of calcium hexaluminate micro powder, 0-10 parts of pure calcium aluminate cement, and 0-0.2% of additional composite water reducing agent based on the total weight of the raw material.

[0007] The alpha-aluminum oxide has a particle size of 5 mu m and accounts for 2-6 parts, and a particle size of 1 mu m and accounts for 1-3 parts.

[0008] The zirconium oxide micro powder has a particle size of less than 1 mu m.

[0009] The rho-aluminum oxide has a content of greater than or equal to 92% and a particle size of less than or equal to 1 mu m.

[0010] The aluminum sol has an alumina solid solution content of 40%, an organic silicon resin content of 20%, and a deionized water content of 40%.

[0011] The composite water reducing agent is a mixture of sodium tripolyphosphate and SM high-efficiency water reducing agent in a mass ratio of 1:1.

[0012] The raw material components of the aluminum-chromium eutectic granulated material include 60 parts of aluminum-chromium eutectic and 40 parts of chromium oxide micro powder, and 31% of deionized water, 3% of isopropyl alcohol, and 1% of polyvinyl acetal are additionally added based on the total weight of the raw material.

[0013] The content of the aluminum-chromium eutectic in the aluminum-chromium eutectic is 80%, and the content of the chromium oxide is 20%. The chromium oxide micro powder has a particle size of 325 mesh.

[0014] The polyvinyl acetal has a solid content of greater than or equal to 65%.

[0015] The polyvinyl acetal has a solid content of greater than or equal to 65%.

[0016] ​​The aluminum-chromium eutectic granules are prepared by a spray granulation method, including the following steps: (1) adding aluminum-chromium eutectic, chromium oxide powder and deionized water into a ball mill, and grinding for 36 hours; (2) after the slurry is finely ground, adding isopropyl alcohol and polyvinyl acetal into the slurry under forced stirring to obtain a mixed slurry, and the viscosity of the mixed slurry is controlled at 400 Pa·s; (3) adding the mixed slurry into a centrifugal spray granulator for spray granulation, and high-speed centrifugal rotation spray disc is used for atomization spraying to form 80-100 μm small droplet spheres, which are instantaneously dried at 300-350 ℃ hot air; (4) the dried granules are blown to a separator by hot air for gas separation and screening to form spherical granule aggregates with micro-closed pores; (5) the spherical granule aggregates are calcined at 2100 ℃ in a high-temperature shaft kiln to form sintered aluminum-chromium co-solvent granules with a content of 60%, a content of 40%, and a granule aggregate particle size of 20-180 mesh; and (6) finely grinding the fine granule aggregate particles screened out from the granule aggregate to obtain granule fine powder, and the granule fine powder has a particle size of 850-1000 mesh.

[0017] A method for preparing high-resistance and strong thermal shock ceramic materials for nuclear waste treatment by volume method and static pressure forming, including the following steps: (1) preparing aluminum sol as a binder by mixing aluminum oxide and deionized water, and then adding organic silicone resin and fully stirring; (2) mixing aluminum-chromium eutectic granules, fused chromium oxide powder, zirconium oxide powder, α-aluminum oxide powder and ρ-aluminum oxide in a certain proportion, and then adding silica ultrafine powder and calcium hexaluminate powder under forced stirring, and adding the prepared aluminum sol as a binder to form a mixed blank; (3) using isostatic pressing method to press the prepared ceramic material mixed blank into a block-shaped ceramic body, and the forming pressure is 150-200 Mpa and the static pressure is 60-160 s; (4) placing the ceramic body into a drying oven and drying at a temperature of 100-150 ℃ for 24 hours, and then placing the dried ceramic body into a high-temperature tunnel kiln for firing, and the temperature is raised to 500 ℃ at a speed of 0.5-2 ℃ / min, and then the temperature is raised to 1650 ℃ at a speed of 2-5 ℃ / min, and the firing is performed for 6 hours to obtain aluminum-chromium-zirconium composite ceramic products.

[0018] The method for preparing high-resistance and strong thermal shock ceramic material for nuclear waste treatment by casting method comprises the following steps: (1) mixing aluminum-chromium eutectic granulated material, fused chromium oxide powder, zirconium oxide powder, alpha-aluminum oxide powder and rho-aluminum oxide according to a proportion, wherein the mass ratio of the aluminum-chromium eutectic granulated material aggregate and fine powder is 17:8; forced stirring, then dispersing and adding silica ultrafine powder, adding pure calcium aluminate cement and 0.1% of sodium tripolyphosphate and 0.1% of SM high-efficiency water reducing agent, and putting into a strong sand mixer for pre-mixing for 10-15 min; (2) adding 5-10% of deionized water into the mixed material, continuing to stir for 5-10 min, preparing a slurry, and pouring the prepared slurry into a mold by vibration molding, and performing high-frequency vibration and vacuum treatment; (3) curing at 110-120 DEG C for 12-24 h, and demolding; (4) putting the demolded body into a drying furnace, drying at 450 DEG C for 24-48 h, and taking out after the furnace temperature drops to below 50 DEG C; (5) putting the dried body into a sintering furnace, heating to 500 DEG C at a heating rate of 0.5-2 DEG C / min, keeping for 2-5 h, then heating to 1650 DEG C at a rate of 2-5 DEG C / min, and sintering for 6 h, to obtain aluminum-chromium-zirconium composite ceramic products.

[0019] The prepared ceramic material mainly contains the following chemical components: , , , .

[0020] The alpha-aluminum oxide and the fused chromium oxide powder are sintered at high temperature to form an aluminum-chromium solid solution, and then the aluminum-chromium eutectic granulated material is added to form a large number of aluminum-chromium eutectic crystal phases; the added zirconium oxide is dispersed around the aluminum-chromium eutectic body, and the zirconium oxide crystals are like rivets to pin around the aluminum-chromium eutectic body, playing a role of fixing and protecting, forming an overall structure, so as to improve the overall thermal shock resistance and corrosion resistance of the composite ceramic material; the added silica ultrafine powder below 1 micron forms a liquid phase during the high-temperature sintering process, and forms a viscous liquid phase from 900 DEG C to 1650 DEG C during the whole sintering process, which promotes sintering and promotes the growth of crystals including aluminum-chromium eutectic body and zirconium oxide solid solution; the added calcium hexaluminate also improves the thermal shock stability of the ceramic material.

[0021] The working process of the centrifugal spray granulator is that air enters the hot air distributor at the top of the drying chamber of the granulator after passing through a filter and a heating device, the hot air of the hot air distributor enters the drying chamber uniformly and rotates spirally, while the mixed slurry is sent to the centrifugal spray disc at the top of the drying chamber, the mixed slurry is sprayed into extremely small mist droplets, so that the surface area of the mixed slurry in contact with the hot air is greatly increased, and the moisture is rapidly evaporated to dry the product in a very short time. When the spray granulation method is used to prepare the aluminum-chromium eutectic granules, a preparation process contrary to the conventional ceramic spray granulation method is adopted, that is, the vacuum defoaming process in the preparation of the slurry is removed, and the air pressure during the spray granulation is adjusted, so as to increase the small bubbles in the slurry, and a large number of small closed pores are formed in the granule particle spheres under the condition of ensuring the uniformity of the slurry, so as to reduce the thermal conductivity of the ceramic material and increase the high resistivity under high temperature.

[0022] In addition, in the production process of the ceramic material, the aluminum-chromium eutectic is added in the form of spherical granules, the spherical granules have better dispersibility and fluidity, greatly improve the toughness of the ceramic and reduce the sintering temperature, and change the performance of the ceramic material.

[0023] The present application configures aluminum sol as a binder, and deionized water reacts with aluminum oxide to form a boehmite gel, so as to increase the plasticity and viscosity of the binder.

[0024] The aluminum-chromium-zirconium composite ceramic material prepared by the present application can be used as the working lining of the electric heating ceramic furnace for glass solidification treatment of nuclear waste and nuclear waste water, and has the following advantages: (1) can resist the radiation and radiation heating accelerated damage of the furnace body caused by high radioactivity and strong toxicity nuclides containing cesium 137, strontium 90 and plutonium 239; can also completely resist the corrosion and damage of other metals under high temperature; (2) can resist the corrosion of molten borosilicate glass, and especially will not produce a low melting phase of sodium aluminosilicate with the borosilicate glass; (3) has high resistivity, which can ensure that the furnace body operates well in the molten state using electricity as the heating body; (4) has low thermal conductivity and strong thermal shock resistance, and the thermal shock stability can resist the cycle working condition from high temperature to less than 200 DEG C; (5) has a long service life for treating high radioactivity nuclides, and the service life of the furnace lining is greater than or equal to five years. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The crystal phase diagram of the aluminum-chromium-zirconium composite ceramic material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0026] In order for those skilled in the art to better understand the technical solutions of the present application and implement them, the present application will be further described below in conjunction with specific examples and drawings, but the examples are not limiting to the present application.

[0027] It should be noted that the experimental methods described in the following examples are conventional methods unless otherwise specified. The reagents and materials used are commercially available unless otherwise specified.

[0028] Aluminum-chromium eutectic The content of Al2O3 is 80%, The content of Al2O3 is 20%; the particle size of zirconia micropowder is ≤1 μm; the particle size of fused chromium oxide is 325 mesh; the content of Al2O3 in ρ-alumina is ≥92%, and the particle size is ≤1 μm; the particle size of chromium oxide micropowder is 325 mesh; and the solid content of polyvinyl acetal is ≥65%.

[0029] Example 1

[0030] A high-resistance and strong thermal shock ceramic material for nuclear waste treatment, the raw materials include the following components by weight fraction: 70 parts of aluminum-chromium eutectic granulated material, 6 parts of fused chromium oxide, 4 parts of zirconia micropowder, 9 parts of α-alumina, 8 parts of ρ-alumina, 4 parts of ultra-fine silica powder, 12 parts of aluminum sol, and 4 parts of calcium hexaluminate micropowder.

[0031] Among them, the particle size of 5 μm in α-alumina accounts for 6 parts, and the particle size of 1 μm accounts for 3 parts.

[0032] The solid solution amount of alumina in the aluminum sol is 40%, the silicone resin is 20%, and the deionized water is 40%.

[0033] Among them, the raw material components of the aluminum-chromium eutectic granulated material include: 60 parts of aluminum-chromium eutectic, 40 parts of chromium oxide micropowder, 31% of deionized water, 3% of isopropyl alcohol, and 1% of polyvinyl formal based on the total weight of the raw materials.

[0034] The aluminum-chromium eutectic granulated material is prepared by spray granulation method, including the following steps: (1) adding aluminum-chromium eutectic and chromium oxide micropowder into a ball mill according to the proportion, then adding deionized water, and co-milling with slurry, ceramic ball milling for 36 h; (2) after the slurry is finely ground, isopropyl alcohol and polyvinyl formal are added under forced stirring to obtain a mixed slurry, and the viscosity of the mixed slurry is controlled at 400 Pa·s; (3) the mixed slurry is added into a centrifugal spray granulator for spray granulation, high-speed centrifugal rotation spray disc for atomization spraying, forming 80-100 μm small droplet spheres, and instant drying at 350°C hot air; (4) the dried particles are blown into a separator with hot air, for gas separation and screening, forming spherical granulated material aggregate with a large number of micro-closed pores; (5) the spherical granulated material aggregate is calcined at 2100°C in a high-temperature shaft kiln to form The content of Al2O3 is 60%, The sintered aluminum-chromium co-solvent granulated material contains 40% of the granulated material, and the granulated material aggregate particle size is 20-180 mesh; (6) the fine aggregate particles are finely ground after the granulated material aggregate is screened, and the granulated material fine powder has a particle size of 850-1000 mesh.

[0035] The method for preparing high-resistance and strong thermal shock ceramic material for nuclear waste treatment by using volume method static pressure forming comprises the following steps: (1) preparing aluminum sol as a binder, uniformly mixing alumina and deionized water, and then adding organic silicone resin and fully stirring and mixing; (2) mixing aluminum-chromium co-solvent granulated material, fused chromium oxide powder, zirconia micro powder, alpha-alumina micro powder and rho-alumina according to a proportion, wherein the mass ratio of aggregate to fine powder in the aluminum-chromium co-solvent granulated material is 3:2, forcibly stirring, adding silica ultrafine powder and calcium hexaluminate micro powder, and then adding the prepared aluminum sol as a binder and mixing uniformly to form a mixed blank; (3) using isostatic pressing forming method to press the prepared ceramic material mixed blank into a block-shaped ceramic blank body, the forming pressure is 200 MPa, and the static pressure is 160 s; (4) placing the ceramic blank body into a drying furnace, drying at a temperature of 150 DEG C for 24 h, and then placing the dried ceramic blank body in a high-temperature tunnel kiln for firing, heating to 500 DEG C at a heating rate of 2 DEG C / min, keeping the temperature for 5 h, and then heating to 1650 DEG C at a rate of 5 DEG C / min, and firing for 6 h to obtain aluminum-chromium-zirconium composite ceramic products.

[0036] Example 2:

[0037] A high-resistance and strong thermal shock ceramic material for nuclear waste treatment, the raw material includes the following components by weight fraction: aluminum-chromium co-solvent granulated material 68 parts, fused chromium oxide 5 parts, zirconia micro powder 4 parts, alpha-alumina 9 parts, rho-alumina 8 parts, silica ultrafine powder 4 parts, aluminum sol 6 parts, and calcium hexaluminate micro powder 4 parts.

[0038] Among them, the particle size of 5 μm in alpha-alumina accounts for 6 parts, and the particle size of 1 μm accounts for 3 parts.

[0039] The aluminum sol contains 40% of alumina solid solution, 20% of organic silicone resin, and 40% of deionized water.

[0040] Among them, the raw material components of the aluminum-chromium co-solvent granulated material include aluminum-chromium co-solvent 60 parts and chromium oxide micro powder 40 parts by weight fraction, and 31% of deionized water, 3% of isopropyl alcohol and 1% of polyvinyl butyral in the total weight of the raw material.

[0041] The aluminum-chromium eutectic granules are prepared by a spray granulation method, including the following steps: (1) adding aluminum-chromium eutectic, chromium oxide powder into a ball mill according to a proportion, then adding deionized water, and grinding with slurry for 36 hours; (2) after the slurry is finely ground, isopropyl alcohol and polyvinyl butyral are added under forced stirring to obtain mixed slurry, and the viscosity of the mixed slurry is controlled at 400 Pa·s; (3) the mixed slurry is added into a centrifugal spray granulator for spray granulation, a high-speed centrifugal rotating spray disc is used for atomization spraying to form 80-100 μm small droplet spheres, and the spheres are instantaneously dried by hot air at 30℃; (4) the dried granules are blown to a separator by hot air, and the granules are separated and screened to form spherical granule aggregates with micro-closed pores; (5) the spherical granule aggregates are calcined at 2100℃ in a high-temperature shaft kiln to form sintered aluminum-chromium eutectic granules with a content of 60%, a content of 40%, and a particle size of 20-180 meshes; and (6) the fine granule aggregates screened from the granule aggregates are finely ground to obtain granule fine powder with a particle size of 850-1000 meshes.

[0042] A method for preparing high-resistance and strong thermal shock ceramic material for nuclear waste treatment by volume method and static pressure forming, including the following steps: (1) preparing aluminum sol as a binder by mixing aluminum oxide with deionized water, then adding silicone resin, and fully stirring and mixing; (2) mixing aluminum-chromium eutectic granules, fused chromium oxide powder, zirconia powder, α-alumina powder and ρ-alumina according to a proportion, wherein the mass ratio of aggregates to fine powder in the aluminum-chromium eutectic granules is 3:2, and the mixture is forcedly stirred, and then ultrafine silica powder and calcium hexaluminate powder are added, and the aluminum sol prepared in step (1) is added as a binder, and the mixture is uniformly mixed to form a mixed blank; (3) the mixed blank of the ceramic material prepared in step (2) is pressed into a block-shaped ceramic blank by isostatic pressing, and the forming pressure is 150 MPa, and the static pressure is 60 s; (4) the ceramic blank is placed in a drying oven and dried at 100℃ for 24 hours, and then the dried ceramic blank is placed in a high-temperature tunnel kiln for firing, the temperature is raised to 500℃ at a rate of 2℃ / min, and then the temperature is raised to 1650℃ at a rate of 2℃ / min, and the firing is performed for 6 hours to obtain an aluminum-chromium-zirconium composite ceramic product.

[0043] Example 3

[0044] A high-resistance and strong thermal shock ceramic material for nuclear waste treatment, wherein the raw materials include the following components by weight: 68 parts of aluminum-chromium eutectic granules, 5 parts of fused chromium oxide, 4 parts of zirconia powder, 3 parts of α-alumina, 8 parts of ρ-alumina, 2 parts of ultrafine silica powder, 10 parts of pure calcium aluminate cement, and 0.2% of a composite water reducing agent based on the total weight of the raw materials.

[0045] The alpha-aluminum oxide contains 2 parts of 5-micron particles and 1 part of 1-micron particles.

[0046] The composite water reducing agent is a mixture of sodium tripolyphosphate and SM high-efficiency water reducing agent in a mass ratio of 1:1.

[0047] The original material components of the aluminum-chromium eutectic granules include, by weight fraction, aluminum-chromium eutectic 60 parts, chromium oxide powder 40 parts, and 31% deionized water, 3% isopropanol, and 1% polyvinyl formal based on the total weight of the original material.

[0048] The aluminum-chromium eutectic granules are prepared by a spray granulation method, including the following steps: (1) adding aluminum-chromium eutectic and chromium oxide powder in proportion to a ball mill, then adding deionized water, and co-milling with slurry, ceramic ball milling for 36 hours; (2) after fine grinding of the slurry, adding isopropanol and polyvinyl formal under forced stirring to obtain a mixed slurry, and controlling the viscosity of the mixed slurry at 400 Pa·s; (3) adding the mixed slurry to a centrifugal spray granulator for spray granulation, high-speed centrifugal rotation of the spray disc for atomization and spraying, forming 80-100-micron small droplet spheres, and instant drying at 300°C hot air; (4) the dried particles are blown to a separator with hot air, for gas separation and screening, forming spherical granulated aggregate with micro-closed pores; (5) the spherical granulated aggregate is calcined at 2100°C in a high-temperature shaft kiln to form sintered aluminum-chromium eutectic granules with a content of 60%, sintered aluminum-chromium eutectic granules with a content of 40%, and the granulated aggregate particle size is 20-180 mesh; (6) fine grinding of the fine aggregate particles screened from the granulated aggregate to obtain granulated aggregate fines, and the granulated aggregate fines have a particle size of 850-1000 mesh.

[0049] The application discloses a method for preparing high-resistance and strong thermal shock ceramic material for nuclear waste treatment by casting, which comprises the following steps: (1) mixing aluminum-chromium eutectic granulated material, fused chromium oxide powder, zirconium oxide powder, alpha-alumina powder and rho-alumina according to a certain proportion, wherein the mass ratio of the aluminum-chromium eutectic granulated material aggregate and fine powder is 17:8; forced stirring, and then dispersively adding silica ultrafine powder and pure calcium aluminate cement, adding 0.1% of sodium tripolyphosphate and 0.1% of SM high-efficiency water reducing agent in the total weight of the original material, and putting into a strong sand mixer for premixing for 10 minutes; (2) adding 5% of deionized water into the mixed material, continuing to stir for 5 minutes, preparing a slurry, and pouring the slurry into a mold by vibration molding, and performing high-frequency vibration and vacuum treatment; (3) curing at 110 DEG C for 12 hours and demolding; (4) putting the demolded body into a drying furnace, drying at 450 DEG C for 24 hours, and taking out the body after the furnace temperature drops to below 50 DEG C; and (5) putting the dried body into a sintering furnace, heating to 500 DEG C at a heating rate of 1 DEG C / min, keeping the temperature for 2 hours, then heating to 1650 DEG C at a rate of 2 DEG C / min, and sintering for 6 hours to obtain aluminum-chromium-zirconium composite ceramic products.

[0050] Example 4

[0051] A high-resistance and strong thermal shock ceramic material for nuclear waste treatment, wherein the original material comprises the following components in parts by weight: 70 parts of aluminum-chromium eutectic granulated material, 6 parts of fused chromium oxide, 4 parts of zirconium oxide powder, 3 parts of alpha-alumina, 8 parts of rho-alumina, 4 parts of silica ultrafine powder, 10 parts of pure calcium aluminate cement, and 0.2% of composite water reducing agent in the total weight of the original material.

[0052] The alpha-alumina has 2 parts of 5-micron particle size and 1 part of 1-micron particle size.

[0053] The composite water reducing agent is a mixture of sodium tripolyphosphate and SM high-efficiency water reducing agent at a mass ratio of 1:1.

[0054] The original material components of the aluminum-chromium eutectic granulated material comprise 60 parts of aluminum-chromium eutectic material and 40 parts of chromium oxide powder, and 31% of deionized water, 3% of isopropyl alcohol and 1% of polyvinyl formal are additionally added in the total weight of the original material.

[0055] The aluminum-chromium eutectic granules are prepared by a spray granulation method, including the following steps: (1) adding aluminum-chromium eutectic, chromium oxide powder, deionized water into a ball mill, and grinding for 36 hours; (2) after the slurry is finely ground, adding isopropyl alcohol and polyvinyl butyral into the slurry under forced stirring to obtain a mixed slurry, and the viscosity of the mixed slurry is controlled at 400 Pa·s; (3) adding the mixed slurry into a centrifugal spray granulator for spray granulation, and high-speed centrifugal rotation spray disc is used for atomization spraying to form 80-100 μm small droplet spheres, which are instantaneously dried by hot air at 350 ℃; (4) the dried granules are blown to a separator by hot air, and the granules are separated and screened to form spherical granule aggregates with micro-closed pores; (5) the spherical granule aggregates are calcined in a high-temperature shaft kiln at 2100 ℃ to form sintered aluminum-chromium eutectic granules with a content of 60%, a content of 40%, and the granule aggregate particle size is 20-180 mesh; (6) the fine granule aggregate particles are finely ground to obtain granule fine powder, and the granule fine powder particle size is 850-1000 mesh.

[0056] A method for preparing high-resistance and strong thermal shock ceramic materials for nuclear waste treatment by casting, including the following steps: (1) mixing aluminum-chromium eutectic granules, fused chromium oxide powder, zirconia powder, α-alumina powder and ρ-alumina in a certain proportion, wherein the mass ratio of aluminum-chromium eutectic granule aggregate and fine powder is 17:8; forced stirring, and then adding silica ultrafine powder and pure calcium aluminate cement, adding 0.1% of sodium tripolyphosphate and 0.1% of SM high-efficiency water reducing agent based on the total weight of the original material, and placing in a strong sand mixer for 15 minutes; (2) adding 10% deionized water to the mixed material, and continuing to stir for 10 minutes to prepare a slurry; (3) using vibration molding, the prepared slurry is poured into a mold for high-frequency vibration and vacuum treatment; (4) curing at 120 ℃ for 24 hours, and demolding; (5) placing the demolded body into a drying oven, drying at 450 ℃ for 48 hours, and taking out after the furnace temperature drops to below 50 ℃; (6) placing the dried body into a sintering furnace, heating to 500 ℃ at a rate of 2 ℃ / min, maintaining for 5 hours, then heating to 1650 ℃ at a rate of 5 ℃ / min, and sintering for 6 hours to obtain aluminum-chromium-zirconium composite ceramic products.

[0057] The main chemical components of the aluminum-chromium-zirconium composite ceramic materials prepared in Examples 1-4 are shown in the following table:

[0058]

[0059] The main performance indicators of the aluminum-chromium-zirconium composite ceramic materials prepared in Examples 1-4 are shown in the following table:

[0060]

[0061] The test data in the table above show that the main performance indicators of the prepared aluminum-chromium-zirconium composite ceramic material are: porosity 10-15%; bulk density 3.0-3.6 g / cm³. 3 Elastic modulus: 146-151 GPa; Thermal conductivity at 1000℃: 2.58-2.61 W / (m·K); High-temperature resistivity: at 900℃ Around 950℃ Around 1000℃ Around 1050℃ It has a thermal shock resistance of 9-12 cycles (1100℃ water cooling); the erosion rate of the expanded glass composite is <10mm / year; and the load-bearing temperature is around 1720℃.

[0062] Depend on Figure 1 As can be seen, the black part marked 1 in the figure is the aluminum-chromium eutectic crystal, and the white part marked 2 is the zirconium oxide crystal. Zirconia crystals are distributed around the aluminum-chromium eutectic crystal. The zirconium oxide crystal phase is dispersed around the aluminum-chromium eutectic, like rivets, forming a stable overall structure.

[0063] The aluminum-chromium-zirconium composite ceramic materials prepared in Examples 1-4 exhibit excellent high-temperature performance, high resistivity, low thermal conductivity, and strong thermal shock resistance. They are used as working linings for electrically heated ceramic furnaces in the vitrification treatment of nuclear waste and nuclear wastewater. These linings can resist radiation from highly radioactive and toxic nuclides such as cesium-137, strontium-90, and plutonium-239, as well as furnace body damage accelerated by irradiation heating. They also completely resist corrosion and damage from other metals at high temperatures. Furthermore, they resist the corrosion of molten borosilicate glass, and in particular, do not form a low-melting phase of sodium aluminosilicate with borosilicate glass. They possess high resistivity, ensuring good furnace operation in the molten state when electricity is used as the heating element. They also exhibit low thermal conductivity and strong thermal shock resistance, with thermal shock stability capable of withstanding cyclic operation from high temperatures to below 200°C. Finally, they have a long service life, with a furnace lining service life ≥ five years.

[0064] The specific embodiments of the present invention have been described in detail above with reference to the examples, but the scope of protection of the present invention should not be limited thereto. The present invention is not limited to the above embodiments, and any changes made within the scope of protection of the claims of the present invention are within the scope of protection of the present invention.

Claims

1. A high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment, characterized in that, The raw materials, by weight, include the following components: 68-70 parts of aluminum-chromium eutectic granules, 5-6 parts of fused chromium oxide, 4 parts of zirconia micro powder, 3-9 parts of α-alumina, 8 parts of ρ-alumina, 2-4 parts of ultrafine silica powder, 6-12 parts of alumina sol, 0-4 parts of calcium hexaaluminate micro powder, 0-10 parts of pure calcium aluminate cement, and an added composite water-reducing agent accounting for 0-0.2% of the total weight of the raw materials. Among them, α-alumina particles with a diameter of 5 μm account for 2-6 parts, and particles with a diameter of 1 μm account for 1-3 parts; The raw material composition of the aluminum-chromium eutectic granulation material includes, by weight, 60 parts of aluminum-chromium eutectic, 40 parts of chromium oxide micro powder, plus 31% of deionized water, 3% of isopropanol and 1% of polyvinyl acetal, accounting for 31% of the total weight of the raw material. The aluminum-chromium eutectic granules are prepared by spray granulation, including the following steps: (1) Aluminum-chromium eutectic and chromium oxide micro powder are added to a ball mill in proportion, and then deionized water is added. The mixture is co-milled with slurry and ceramic ball milled for 36 hours; (2) After the slurry is finely ground, isopropanol and polyvinyl acetal are added while forcibly stirred to obtain a mixed slurry. The viscosity of the mixed slurry is controlled at 400 Pa·s; (3) The mixed slurry is added to a centrifugal spray granulator for spray granulation. The high-speed centrifugal rotating spray disc is used for atomization spraying to form small droplet spheres of 80-100 μm. At the same time, the spheres are instantaneously dried with hot air at 300-350℃; (4) The dried granules are blown to a separator with hot air for gas separation and sieving to form spherical granulated aggregate with micro-closed pores; (5) The spherical granulated aggregate is calcined in a high-temperature vertical kiln at 2100℃ to form Content 60%, Sintered aluminum-chromium eutectic granules with a content of 40% have an aggregate particle size of 20-180 mesh; (6) Fine aggregate particles separated from the aggregate are finely ground to obtain fine powder of granules with a particle size of 850-1000 mesh. The main chemical components of the prepared ceramic material are as follows: , , , .

2. The high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment according to claim 1, characterized in that: Zirconia micro powder has a particle size ≤1μm; fused chromium oxide has a particle size of 325 mesh.

3. The high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment according to claim 1, characterized in that: p-alumina Content ≥92%, particle size ≤1μm.

4. The high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment according to claim 1, characterized in that: The aluminum sol contains 40% alumina solid solution, 20% organosilicon resin, and 40% deionized water.

5. The high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment according to claim 1, characterized in that: The composite water-reducing agent is a mixture of sodium tripolyphosphate and SM high-efficiency water-reducing agent in a 1:1 mass ratio.

6. The high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment according to claim 1, characterized in that: In aluminum-chromium eutectic The content is 80%. The content is 20%; the particle size of chromium oxide micro powder is 325 mesh; the solid content of polyvinyl acetal is ≥65%.

7. A method for preparing a high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment according to claim 1, characterized in that, High-resistivity, high-thermal-shock ceramic materials for nuclear waste treatment are prepared by volumetric static pressing or casting.

8. The method for preparing high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment according to claim 7, characterized in that, A method for preparing high-resistivity, high-thermal-shock ceramic materials for nuclear waste treatment by volumetric static pressing includes the following steps: (1) preparing aluminum sol as a binder, first mixing alumina with deionized water evenly, then adding silicone resin, and stirring thoroughly to mix evenly; (2) mixing aluminum-chromium eutectic granules, fused chromium oxide powder, zirconium oxide micro powder, α-alumina micro powder, and ρ-alumina in proportion, wherein the mass ratio of aggregate to fine powder in the aluminum-chromium eutectic granules is 3:2, forcibly stirring, dispersing and adding silica ultrafine powder and calcium hexaaluminate micro powder, then adding the prepared aluminum sol as a binder, and mixing evenly. (3) Using isostatic pressing, the prepared ceramic material mixed blank is pressed into a block ceramic blank with a molding pressure of 150-200 MPa and static pressure of 60-160 s; (4) The ceramic blank is placed in a drying furnace and dried at 100-150℃ for 24 hours. Then the dried ceramic blank is placed in a high-temperature tunnel kiln for firing. The temperature is raised to 500℃ at a rate of 0.5-2℃ / min and held for 2-5 hours. Then the temperature is raised to 1650℃ at a rate of 2-5℃ / min and fired for 6 hours to obtain aluminum chromium zirconium composite ceramic products.

9. The method for preparing high-resistivity, high-thermal-shock ceramic material for nuclear waste treatment according to claim 7, characterized in that, The method for preparing high-resistance, high-thermal-shock ceramic materials for nuclear waste treatment by casting includes the following steps: (1) Aluminum-chromium eutectic granules, fused chromium oxide powder, zirconia micro powder, α-alumina micro powder, and ρ-alumina are mixed in proportion, wherein the mass ratio of aggregate to fine powder in the aluminum-chromium eutectic granules is 17:8; forced stirring is performed, and silica ultrafine powder is added in a dispersed manner, along with pure calcium aluminate cement, sodium tripolyphosphate (0.1%), and SM high-efficiency water-reducing agent (0.1%). The mixture is then placed in a high-power sand mixer and premixed for 10-15 minutes. The mixed material is then set aside. (2) 5-10% deionized water is added to the mixed material, and stirring is continued for 5 minutes. -10min, the raw material is made into a slurry, and the slurry is poured into the mold by vibration molding, and high frequency vibration and vacuum treatment are performed; (3) it is cured at 110-120℃ for 12-24h and demolded; (4) the demolded blank is placed in a drying furnace and dried at 450℃ for 24-48h. After the furnace temperature drops to below 50℃, it is taken out of the furnace; (5) the dried blank is placed in a sintering furnace and heated to 500℃ at a heating rate of 0.5-2℃ / min. It is held for 2-5h and then heated to 1650℃ at a rate of 2-5℃ / min. It is fired for 6 hours to obtain aluminum chromium zirconium composite ceramic products.

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