Anti-erosion composite ceramic for the discharge port of the bottom of a high-level nuclear species glass solidification furnace

Abstract

The application belongs to the technical field of ceramic materials for nuclear waste treatment, and discloses a kind of anti-erosion composite ceramics for high-level nuclide glass solidification furnace bottom discharge port, which is prepared by adding nano-sized zirconia and binder to chromium oxide, and then preparing a chromium-zirconium sintered body with high density and ultra-low porosity by spray granulation method, and then introducing aluminum titanate ceramic powder, clay, sodium-based bentonite and aluminum sol binder, and then forming by volume method, and then preparing titanium-aluminum-chromium-zirconium composite ceramics with ultra-low porosity and high elastic modulus by high-temperature sintering, which has excellent resistance to thermal shock and erosion, and is applied to the lining of high-level nuclide glass solidification furnace bottom discharge port, effectively prolonging the service life of high-level nuclide glass solidification furnace discharge port.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic materials for nuclear waste treatment furnaces, and particularly relates to a kind of anti-erosion composite ceramics for high-level nuclide glass solidification furnace bottom discharge port. BACKGROUND

[0002] Nuclear waste has the characteristics of high concentration of radioactive elements, high heat release rate and strong corrosion, and glass solidification technology is currently the only high-level waste liquid treatment technology that can be industrialized. High-level waste liquid and glass raw materials are mixed and melted, and after cooling, a glass body is formed. The glass body has low leaching rate and high strength, and high-level radioactive nuclides are contained in stable glass matrix. It can effectively contain radioactive substances and form a stable form, convert waste liquid into solid, thereby greatly improving the safety of storage and meeting the long-term stable storage requirements of high-level waste liquid.

[0003] The glass solidification heating furnace is the core equipment of the high-level liquid glass solidification technology. The discharge mode of the glass solidification heating furnace is bottom discharge. The discharge port is subjected to long-term high-low temperature fatigue during service, and the repeated melting-solidification process of the glass solidification material in the discharge port also repeatedly applies external force to the discharge port, which easily causes the refractory material at the discharge port to be eroded and damaged, which inevitably affects the entire nuclear waste high-level waste liquid glass solidification process. In view of the harsh service environment of the discharge port, it is urgent to develop a composite ceramic for the discharge port of the nuclear waste high-level waste liquid glass solidification electric heating ceramic furnace to improve its performance and service life. SUMMARY

[0004] The application provides an anti-erosion composite ceramic for the discharge port of a high-level nuclide glass solidization furnace bottom, which is prepared by a spray granulation method to obtain a high-density, ultra-low porosity chromium-zirconium sintered body, and then aluminum titanate ceramic powder, clay, sodium-based bentonite and aluminum sol are introduced and combined to form a titanium-aluminum-chromium-zirconium composite ceramic with ultra-low porosity and high elastic modulus after hydraulic forming and high-temperature sintering. It is applied to the lining of the discharge port of the high-level nuclide glass solidification furnace bottom, and has the advantages of high heat shock resistance and erosion resistance, which effectively prolongs the service life of the discharge port of the high-level nuclide glass solidification furnace.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows: an anti-erosion composite ceramic for the discharge port of a high-level nuclide glass solidification furnace bottom, the raw materials include the following components in parts by weight: chromium-zirconium sintered granulated material 85-90 parts, aluminum titanate ceramic powder 4-5 parts, clay 1 part, sodium-based bentonite 0.5 part, and aluminum sol 3 parts.

[0006] Among them, the solid content of aluminum oxide in the aluminum sol is 40%, the organic silicon resin is 20%, and the deionized water is 40%.

[0007] The raw material components of the chromium-zirconium sintering granulating material include: 90 parts of chromium oxide, 10 parts of nano-zirconium oxide powder, 31% of deionized water, 3% of isopropyl alcohol and 1% of polyvinyl acetal based on the total weight of the raw material.

[0008] The particle size of the chromium oxide is 325 mesh.

[0009] The solid content of the polyvinyl acetal is greater than or equal to 65%.

[0010] The chromium-zirconium sintering granulating material is prepared by a spray granulation method, including the following steps: (1) adding chromium oxide and nano-zirconium oxide powder into a ball mill according to a proportion, then adding deionized water, and ball milling for 36 hours with ceramic balls; (2) after the slurry is finely ground, isopropyl alcohol and polyvinyl acetal are added under forced stirring to obtain a mixed slurry, and the viscosity of the mixed slurry is controlled at 400 Pa·s; (3) after vacuum degassing, the mixed slurry is added into a centrifugal spray granulator for spray granulation, high-speed centrifugal rotation of a spray disc is used for atomization and injection to form small droplet spheres with a diameter of 80-100 μm, and instant drying is performed at 300-350 ℃ hot air; (4) the dried particles are blown to a separator with hot air for gas separation and screening to obtain spherical granulating material; and (5) the spherical granulating material is sintered at 2250-2350 ℃ in a high-temperature shaft kiln to form chromium-zirconium sintering granulating material with high density and ultra-low porosity.

[0011] The method for preparing the anti-erosion composite ceramic for the discharge port of the high-level nuclear glass solidification furnace bottom by volume method and static pressure forming includes the following steps: (1) preparing aluminum sol as a binder by uniformly mixing aluminum oxide and deionized water, and then adding silicone resin and fully stirring and mixing; (2) mixing chromium-zirconium sintering granulating material, aluminum titanate ceramic powder, clay and sodium-based bentonite according to a proportion, then forced stirring, adding the prepared aluminum sol as a binder, and mixing uniformly to form a mixed blank; (3) using a 4000t hydraulic press isostatic pressing forming method, the prepared mixed blank is pressed into a block-shaped ceramic blank, the forming pressure is 150-200 MPa, and the static pressure is 60-160 s; (4) placing the ceramic blank into a drying furnace and drying at a temperature of 100-150 ℃ for 24 hours, and then placing the dried ceramic blank in a high-temperature tunnel kiln for sintering, with a heating rate of 0.5-2 ℃ / min, heating to 500 ℃, keeping for 2-5 hours, then heating to 1750-1800 ℃ at a rate of 2-5 ℃ / min, and sintering for 6 hours to obtain titanium-aluminum-chromium-zirconium composite ceramic.

[0012] The present application produces high-density, ultra-low-porosity chromium zirconium sintered granules by a spray granulation method, then introduces aluminum titanate ceramic powder, clay, sodium-based bentonite and aluminum sol, and prepares titanium-aluminum-chromium-zirconium composite ceramic material with ultra-low porosity and high elastic modulus through volume method hydraulic forming and high-temperature sintering, thereby improving the overall thermal shock resistance, erosion resistance and corrosion resistance of the ceramic material.

[0013] The working process of the centrifugal spray granulator is that air enters the hot air distributor at the top of the granulator drying chamber 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 device, the mixed slurry is sprayed into extremely small mist droplets, 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 chromium zirconium sintered granules are prepared by the spray granulation method used in the present application, a vacuum defoaming process is adopted during the preparation of the slurry, which aims to reduce the small bubbles in the slurry, ensure the uniformity of the slurry, and form high-density, ultra-low-porosity granule spherical bodies, which are then sintered at high temperature to form chromium zirconium sintered granules.

[0014] In addition, during the production of the ceramic material, the chromium zirconium sintered granules are added in the form of spherical granules, which have better dispersibility and fluidity, greatly improve the toughness of the composite ceramic and reduce the sintering temperature, and change the performance of the ceramic material.

[0015] The titanium-aluminum-chromium-zirconium composite ceramic material prepared by the present application has ultra-low porosity and high elastic modulus, can resist the radiation of high-radioactivity, strong-toxicity nuclear elements such as cesium 137, strontium 90 and plutonium 239, and the damage of the accelerated discharge port of the furnace body caused by radiation and heat; can resist the erosion of molten borosilicate glass, especially will not produce low-melting sodium aluminosilicate phase with borosilicate glass; the strong thermal shock resistance and stability can resist the long-term high and low temperature fatigue of the discharge port during service, and the repeated melting-solidification process of the glass solidification material in the discharge port also repeatedly applies external force to the discharge port, and resists erosion and damage; when applied to the lining of the glass solidification furnace bottom discharge port of high-radioactivity nuclear elements, it has a long service life. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The crystal phase diagram of the titanium-aluminum-chromium-zirconium composite ceramic prepared in Example 1 of the present application;

[0017] In the figure: mark 1 is , mark 2 is , and mark 3 is glass body. DETAILED DESCRIPTION

[0018] In order to make the skilled in the art better understand the technical solutions of the present application can be implemented, the following specific embodiments and the present application is further described with reference to the drawings, but the examples are not as a limitation of the present application.

[0019] It should be noted that the experimental methods described in the following examples, if not specifically described, are conventional methods; the reagents and materials used, if not specifically described, can be purchased on the market.

[0020] The particle size of chromium oxide is 325 mesh; the solid content of polyvinyl acetal is ≥65%; the solid content of alumina in the aluminum sol is 40%, the silicone resin is 20%, and the deionized water is 40%.

[0021] Example 1:

[0022] A kind of high-nuclide glass solidification furnace bottom discharge port for anti-erosion composite ceramic, raw material includes the following components by weight fraction: chromium zirconium sintered granulating material 88 parts, aluminum titanate ceramic powder 4.5 parts, clay 1 part, sodium bentonite 0.5 part, aluminum sol 3 parts.

[0023] The raw material components of chromium zirconium sintered granulating material include: chromium oxide 90 parts, nano zirconia powder 10 parts, plus 31% deionized water, 3% isopropanol and 1% polyvinyl acetal of the total weight of the raw material.

[0024] Chromium zirconium sintered granulating material is prepared by spray granulation method, including the following steps: (1) chromium oxide, nano zirconia powder are added to the ball mill in proportion, then deionized water is added, and ceramic balls are milled for 36h; (2) after the slurry is finely ground, isopropanol and polyvinyl acetal are added under forced stirring to obtain a mixed slurry, and the viscosity of the mixed slurry is controlled at 400Pa·s; (3) after vacuum degassing, the mixed slurry is added to a centrifugal spray granulator for spray granulation, high-speed centrifugal rotation spray disc for atomization injection, forming 80-100μm small droplet spheres, and instant drying at 350℃ hot air; (4) the dried particles are blown to the separator with hot air, and gas separation and screening are carried out to obtain spherical granulating material; (5) the spherical granulating material is sintered at 2300℃ in a high-temperature shaft kiln to form chromium zirconium sintered granulating material with high density and ultra-low porosity.

[0025] The method for preparing the anti-erosion composite ceramic for the discharge port of the high-level waste glass solidification furnace bottom by using the volume method static compaction molding comprises the following steps: (1) preparing aluminum sol as a binder, first mixing alumina with deionized water uniformly, and then adding silicone resin and fully stirring and mixing uniformly; (2) mixing chromium-zirconium sintered granulated material, aluminum titanate ceramic powder, clay and sodium-based bentonite according to a proportion, then forcibly stirring, adding the prepared aluminum sol as a binder and mixing uniformly to form a mixed blank; (3) using a 4000t hydraulic press isostatic compaction molding method, the prepared mixed blank is pressed into a block-shaped ceramic blank body, the molding pressure is 200MPa, and the isostatic pressure is 160s; (4) the ceramic blank body is placed in a drying furnace and dried at a temperature of 120℃ for 24h, and then the dried ceramic blank body is placed in a high-temperature tunnel kiln for sintering, the temperature is raised to 500℃ at a speed of 1℃ / min, the temperature is kept for 3h, and then the temperature is raised to 1800℃ at a speed of 3℃ / min, and sintering is performed for 6h to obtain titanium-aluminum-chromium-zirconium composite ceramic.

[0026] Example 2:

[0027] The anti-erosion composite ceramic for the discharge port of the high-level waste glass solidification furnace bottom comprises the following components in terms of weight fractions: chromium-zirconium sintered granulated material 85 parts, aluminum titanate ceramic powder 4 parts, clay 1 part, sodium-based bentonite 0.5 part and aluminum sol 3 parts.

[0028] The raw material components of the chromium-zirconium sintered granulated material comprise, in terms of weight fractions: chromium oxide 90 parts, nano-sized zirconium oxide powder 10 parts, and deionized water accounting for 31% of the total weight of the raw material, 3% isopropyl alcohol and 1% polyvinyl acetal.

[0029] The chromium-zirconium sintered granulated material is prepared by using a spray granulation method, comprising the following steps: (1) adding chromium oxide and nano-sized zirconium oxide powder into a ball mill according to a proportion, then adding deionized water, and ball milling the slurry for 36h; (2) after the slurry is finely ground, isopropyl alcohol and polyvinyl acetal are added under forced stirring to obtain mixed slurry, and the viscosity of the mixed slurry is controlled at 400Pa·s; (3) after vacuum degassing, 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 small droplet spheres of 80-100μm, and the spheres are instantaneously dried by hot air at 300℃; (4) the dried particles are blown to a separator by hot air for gas separation and screening to obtain spherical granulated material; and (5) the spherical granulated material is sintered at 2250℃ in a high-temperature shaft kiln to form chromium-zirconium sintered granulated material with high density and ultra-low porosity.

[0030] The method for preparing the anti-erosion composite ceramic for the high-level nuclear waste glass solidification furnace bottom discharge port by using the volume method static compaction molding comprises the following steps: (1) preparing aluminum sol as a binder, first mixing alumina with deionized water uniformly, and then adding silicone resin and fully stirring and mixing uniformly; (2) mixing chromium-zirconium sintered granulated material, aluminum titanate ceramic powder, clay and sodium-based bentonite according to a proportion, then forcibly stirring, adding the prepared aluminum sol as a binder and mixing uniformly to form a mixed blank; (3) using a 4000t hydraulic press isostatic compaction molding method, the prepared mixed blank is pressed into a block-shaped ceramic blank body, the molding pressure is 150MPa, and the isostatic pressure is 60s; (4) the ceramic blank body is placed in a drying furnace and dried at a temperature of 100℃ for 24h, and then the dried ceramic blank body is placed in a high-temperature tunnel kiln for sintering, the temperature is raised to 500℃ at a speed of 0.5℃ / min, the temperature is kept for 2h, and then the temperature is raised to 1750℃ at a speed of 2℃ / min, and sintering is performed for 6h to obtain titanium-aluminum-chromium-zirconium composite ceramic.

[0031] Example 3:

[0032] The anti-erosion composite ceramic for the high-level nuclear waste glass solidification furnace bottom discharge port comprises the following components in terms of weight fractions: chromium-zirconium sintered granulated material 90 parts, aluminum titanate ceramic powder 5 parts, clay 1 part, sodium-based bentonite 0.5 part and aluminum sol 3 parts.

[0033] The raw material components of the chromium-zirconium sintered granulated material comprise, in terms of weight fractions: chromium oxide 90 parts, nano-sized zirconium oxide powder 10 parts, and deionized water accounting for 31% of the total weight of the raw material, 3% isopropyl alcohol and 1% polyvinyl acetal.

[0034] The chromium-zirconium sintered granulated material is prepared by using a spray granulation method, comprising the following steps: (1) adding chromium oxide and nano-sized zirconium oxide powder into a ball mill according to a proportion, then adding deionized water, and ball milling the slurry for 36h; (2) after the slurry is finely ground, isopropyl alcohol and polyvinyl acetal are added under forced stirring to obtain mixed slurry, and the viscosity of the mixed slurry is controlled at 400Pa·s; (3) after vacuum degassing, 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 small droplet spheres of 80-100μm, and the spheres are instantaneously dried by hot air at 320℃; (4) the dried particles are blown to a separator by hot air for gas separation and screening to obtain spherical granulated material; and (5) the spherical granulated material is sintered at 2350℃ in a high-temperature shaft kiln to form chromium-zirconium sintered granulated material with high density and ultra-low porosity.

[0035] The method for preparing the anti-erosion composite ceramic for the discharge port of the high-level nuclear waste glass solidification furnace bottom by using the 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 silicone resin and fully stirring and mixing uniformly; (2) mixing chromium-zirconium sintered granules, aluminum titanate ceramic powder, clay and sodium-based bentonite according to a proportion, then forcibly stirring, adding the prepared aluminum sol as a binder and mixing uniformly to form a mixed blank; (3) using a 4000t hydraulic press isostatic pressing forming method, pressing the prepared mixed blank into a block-shaped ceramic blank body, the forming pressure is 180MPa and the static pressure is 100s; (4) placing the ceramic blank body into a drying furnace, drying at a temperature of 150℃ for 24h, and then placing the dried ceramic blank body into a high-temperature tunnel kiln for firing, the temperature is raised to 500℃ at a speed of 2℃ / min, the temperature is kept for 5h, and then the temperature is raised to 1780℃ at a speed of 5℃ / min, and the firing is performed for 6h to obtain the titanium-aluminum-chromium-zirconium composite ceramic.

[0036] The main chemical components of the titanium-aluminum-chromium-zirconium composite ceramic prepared in examples 1-3 are shown in the following table:

[0037]

[0038] The main performance indicators of the titanium-aluminum-chromium-zirconium composite ceramic prepared in examples 1-3 are shown in the following table:

[0039]

[0040] From the test data in the above table, it can be known that the main chemical component contents of the prepared titanium-aluminum-chromium-zirconium composite ceramic are: 3-4% of alumina, 84-86% of chromium oxide, 8% of zirconium oxide, 2% of titanium oxide and 1.5% of silicon dioxide and others.

[0041] The main performance indicators of the prepared titanium-aluminum-chromium-zirconium composite ceramic are: bulk density ; elastic modulus 220-280GPa; thermal conductivity coefficient at 1000℃ 3.0-3.1W / (m·K); thermal expansion coefficient at 1000℃ ; thermal shock resistance 10 times (DIN standard, water cooling).

[0042] It can be known from the above that, at a high-temperature sintering temperature, a solid phase equilibrium relationship is formed, in which Figure 1 , is a skeleton and glass phase is a binder, that is, a composite titanium-aluminum-chromium-zirconium ceramic system composed of chromium sesquioxide , zirconium dioxide and aluminum-titanium-silicon ternary oxide glass .

[0043] ​The titanium-aluminum-chromium-zirconium composite ceramic material prepared by this invention has ultra-low porosity and high elastic modulus, which can resist the damage to the furnace outlet accelerated by radiation and irradiation heating of highly radioactive and toxic nuclides such as cesium-137, strontium-90, and plutonium-239. Its strong thermal shock resistance can resist the fatigue of the outlet under high and low temperature conditions during long-term service. In addition, the repeated melting and solidification process of the glass curing material in the outlet will also repeatedly apply external forces to the outlet, resisting erosion damage. When applied to the inner lining of the outlet of the furnace bottom of a high-radioactive nuclide glass curing furnace, it has a long service life.

[0044] 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. An erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace, characterized in that, The raw materials include the following components by weight: 85-90 parts of chromium zirconium sintered granules, 4-5 parts of aluminum titanate ceramic powder, 1 part of clay, 0.5 parts of sodium-based bentonite, and 3 parts of aluminum sol. The raw material composition of the chromium zirconium sintered granulation material includes, by weight, 90 parts of chromium oxide, 10 parts of nano-sized zirconium oxide 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. Chromium-zirconium sintered granules were prepared by spray granulation, including the following steps: (1) Chromium oxide and nano-sized zirconium oxide powder were added to a ball mill in proportion, and then deionized water was added. The slurry was ball-milled for 36 hours. (2) After the slurry was finely ground, isopropanol and polyvinyl acetal were added while forcibly stirred to obtain a mixed slurry. The viscosity of the mixed slurry was controlled at 400 Pa·s. (3) After vacuum degassing, the mixed slurry was added to a centrifugal spray granulator for spray granulation. The high-speed centrifugal rotating spray disc was used for atomization spraying to form small droplet spheres of 80-100 μm. At the same time, the spheres were instantly dried with hot air at 300-350℃. (4) The dried granules were blown to a separator with hot air for gas separation and sieving to obtain spherical granules. (5) The spherical granules were sintered in a high-temperature vertical kiln at 2250-2350℃ to form chromium-zirconium sintered granules with high density and ultra-low porosity. The main chemical components of the erosion-resistant composite ceramic prepared by volumetric static pressing are: alumina 3-4%, chromium oxide 84-86%, zirconium oxide 8%, titanium oxide 2%, silicon dioxide and others 1.5%.

2. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that: The particle size of chromium oxide is 325 mesh.

3. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that: The solid content of polyvinyl acetal is ≥65%.

4. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that: The aluminum sol contains 40% alumina solid solution, 20% organosilicon resin, and 40% deionized water.

5. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that, The preparation of erosion-resistant composite ceramics for the bottom outlet of a high-radioactive glass curing furnace by volumetric static pressing includes the following steps: (1) Prepare aluminum sol as a binder, first mix alumina and deionized water evenly, then add silicone resin and stir thoroughly; (2) Mix chromium zirconium sintered granules, aluminum titanate ceramic powder, clay, and sodium bentonite in proportion, force stir, then add the prepared aluminum sol as a binder and mix evenly to form a mixed blank; (3) Press the prepared mixed blank into a block ceramic blank using a 4000t hydraulic press isostatic pressing method; (4) Place the ceramic blank in a drying furnace and dry it at 100-150℃ for 24h, then place the dried ceramic blank in a high-temperature tunnel kiln for firing to obtain erosion-resistant composite ceramics.

6. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 5, characterized in that: In step (3), the hydraulic forming pressure of the ceramic blank is 150-200MPa, and the static pressure is 60-160s.

7. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 5, characterized in that, In step (4), the temperature is increased to 500℃ at a rate of 0.5-2℃ / min, and held for 2-5 hours. Then the temperature is increased to 1750-1800℃ at a rate of 2-5℃ / min and fired for 6 hours.

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