Superfine zirconia nano composite powder and grinding preparation method thereof

Abstract

The invention belongs to the technical field of zirconium oxide refractory parts, and particularly relates to superfine zirconium oxide nano composite powder and a grinding preparation method thereof. The superfine premix is prepared by adopting a fluidized bed combined drying mixing and dry grinding process, and the uniform dispersion of nano powder is realized by controlling the flow rate of hot air and the parameters of grinding balls; designing a gradient structure of which the surface layer contains YOSiO to inhibit interface stress; and the surface protection is enhanced by combining molten salt dipping and filling of pores and plasma spraying of an AlO-YAG coating. The volume density of the prepared refractory part is larger than or equal to 5.85 g / cm < 2 >, the apparent porosity is smaller than or equal to 0.32%, the bending strength is larger than or equal to 550 MPa, and the 800 DEG C / 24 h glass liquid erosion depth is smaller than or equal to 0.18 mm. Through raw material treatment and integration, gradient component design and surface modification technologies, the comprehensive performance of the material is remarkably improved, and the material is suitable for high-temperature and high-erosion environments such as a glass kiln.

Description

Technical Field

[0001] The present invention belongs to the technical field of zirconia refractory products, and particularly relates to an ultrafine zirconia nano-composite powder and a grinding preparation method thereof. Background Art

[0002] Zirconia (ZrO2) refractory materials are widely used in high-temperature fields such as glass melting furnaces and steel continuous casting due to their high melting point (2715 °C), thermal shock resistance, and chemical erosion resistance. However, traditional zirconia materials have problems such as insufficient high-temperature volume stability and weak resistance to glass melt penetration during long-term service, mainly manifested as structural damage caused by the propagation of grain boundary cracks and the diffusion of erosion ions. Although existing modification methods can partially improve the performance by adding oxides or optimizing the sintering process, how to achieve the coordinated improvement of bulk density, apparent porosity, flexural strength, and anti-penetration performance remains a difficult problem in the industry.

[0003] In addition, in terms of raw material processing technology, in order to improve the mixing and grinding effects, methods such as step-by-step drying, mixing, and grinding can be used. However, due to the easy agglomeration characteristics of nano-powders, it is often necessary to improve the dispersibility through pretreatment means such as adding dispersants or silane coupling agents. This not only increases the production cost but also may affect the material purity due to the introduction of foreign components, which is not conducive to controlling the densification and mechanical property stability of the material. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention provides an ultrafine zirconia nano-composite powder and a grinding preparation method thereof.

[0005] The first aspect of the present invention is to provide a grinding preparation method for an ultrafine zirconia nano-composite powder.

[0006] The preparation of the ultrafine matrix layer powder premix includes the following steps: According to the formula of the matrix layer powder raw materials, zirconia, single crystal alumina, fused quartz powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed drying equipment for combined drying and mixing treatment, controlling the drying temperature at 115 - 125 °C and the hot air flow rate at 1.5 - 3 m / s until the moisture content of the material ≤ 0.2%; the material is transferred to a ball mill equipment for dry grinding treatment, using zirconia grinding balls with a diameter of 2 - 3 mm, controlling the ball-to-material ratio at 3 - 8:1, the rotation speed at 400 - 700 rpm, grinding for 3 - 5 hours, and passing through a 1200-mesh sieve to obtain the ultrafine matrix layer premix.

[0007] The preparation of the ultra-fine surface layer powder premix includes the following steps: According to the formula of the surface layer powder raw materials, zirconia, single crystal powdered alumina, fused quartz powder, boron compound, rare earth oxide, silicon carbide whisker, nano-alumina, nano-zirconia, and Y2O6Si2O7 are put into a fluidized bed drying equipment for combined drying and mixing treatment. Control the drying temperature at 115 - 125 °C and the hot air flow rate at 1.5 - 3 m / s until the moisture content of the material ≤ 0.2%; transfer the material to a ball milling equipment for dry milling treatment. Use zirconia grinding balls with a diameter of 2 - 3 mm, control the ball-to-material ratio at 3 - 8:1, the rotation speed at 400 - 700 rpm, grind for 3 - 5 hours, and pass through a 1200-mesh sieve to obtain the ultra-fine surface layer premix.

[0008] As a further optimized scheme for the grinding preparation method of the ultra-fine zirconia nano-composite powder, the raw materials of the ultra-fine matrix layer premix include the following components:

[0009]

[0010]

[0011] As a further optimized scheme for the grinding preparation method of the ultra-fine zirconia nano-composite powder, the raw material of the ultra-fine surface layer premix is the raw material of the ultra-fine matrix layer premix added with 5% by mass of nano-Y2O6Si2O7 powder.

[0012] The second aspect of the present invention is to provide an ultra-fine zirconia nano-composite powder, including the ultra-fine matrix layer powder premix and the ultra-fine surface layer premix prepared by the above preparation method.

[0013] On this basis, the present invention also provides a method for preparing a refractory piece using the above ultra-fine zirconia nano-composite powder. Thus, a highly densified zirconia refractory piece with excellent anti-permeation performance can be obtained, which has a high bulk density, a low apparent porosity, a high bending strength, and an excellent anti-glass liquid penetration performance. It mainly includes the following steps:

[0014] Mix raw materials

[0015] Add a magnesium dihydrogen phosphate solution with a concentration of 15 - 20% to the matrix layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 10 - 20% of the total mass of the raw materials. Use wet ball milling for 20 - 30 minutes to form a uniform slurry; dry and sieve to obtain the matrix layer mixture;

[0016] Add a magnesium dihydrogen phosphate solution with a concentration of 15 - 20% to the surface layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 10 - 20% of the total mass of the raw materials. Use wet ball milling for 20 - 30 minutes to form a uniform slurry; dry and sieve to obtain the surface layer mixture;

[0017] Load and mold the raw materials:

[0018] Fill the mold with the matrix layer mixture, with a thickness of 90 - 95% of the total thickness, and then fill it with the surface layer mixture, with a thickness of 5 - 10% of the total thickness; after filling, perform cold isostatic pressing for forming;

[0019] Sinter the formed green body:

[0020] Pre - sinter the formed green body to remove the binder, then perform gas pressure sintering under a protective atmosphere, and then perform hot isostatic pressing on the sintered green body to further eliminate internal defects and improve the material density;

[0021] Perform post - treatment on the sintered part:

[0022] Perform molten salt impregnation and plasma spraying on the sintered part to obtain a densified anti - permeable zirconia refractory part.

[0023] As a further optimization: during the raw material filling and forming process, the cold isostatic pressing forming pressure is 250 - 350 MPa, and the pressure holding time is 2 - 5 minutes.

[0024] As a further optimization: during the sintering process of the formed green body, pre - sinter the formed green body at 780 - 820 °C for 1 - 5 hours, with a heating rate of 2 - 4 °C / min to remove the binder; subsequently, perform gas pressure sintering at 1600 - 1700 °C for 1 - 3 hours, introduce nitrogen at 8 - 12 MPa, with a heating rate of 4 - 6 °C / min; then perform hot isostatic pressing on the sintered green body in an argon environment at 1400 - 1600 °C and 120 - 180 MPa for 0.8 - 1.5 hours, and control the cooling rate at ≤5 °C / min to further eliminate internal defects and improve the material density.

[0025] As a further optimization: the oxygen content in the atmosphere used for pre - sintering and gas pressure sintering is ≤10 ppm.

[0026] As a further optimization: during the post - treatment process of the sintered part, immerse the sintered part in molten borosilicate glass at 1200 - 1250 °C for 25 - 40 minutes to fill the surface pores; after impregnation, cool naturally and remove the residual glass phase on the surface.

[0027] As a further optimization: during the post - treatment process of the sintered part, after molten salt impregnation, deposit a 30 - 50 μm thick Al2O3 - YAG composite coating on the surface by plasma spraying.

[0028] Beneficial effects

[0029] Through the combination of fluidized bed combined drying, mixing and dry grinding processes, the present invention efficiently prepares a uniform and ultra-fine matrix layer and surface layer premix, significantly shortening the subsequent wet ball milling time, improving production efficiency and reducing costs, providing technical support for large-scale production. The gradient structure design enables the Y element content to gradually decrease from the surface to the matrix, effectively reducing the interfacial stress and inhibiting the ZrO2 phase transformation, and improving the mechanical properties of the material. The (Y, Ce)-O-Si-Al composite glass phase formed by rare earth oxides significantly blocks the diffusion path of erosion ions, and the anti-permeation performance is significantly improved. The post-treatment processes of molten salt impregnation and plasma spraying fill the surface pores and form an Al2O3-YAG composite coating, further enhancing the anti-permeation ability. In summary, by comprehensively optimizing the raw material formula and preparation process, the present invention can prepare a zirconia refractory with high bulk density, low apparent porosity, high bending strength and excellent anti-glass liquid permeation performance, having broad application prospects in high-temperature and high-permeation environments such as glass furnaces. Specific Embodiments

[0030] The following further clarifies the present invention through specific embodiments. These embodiments are exemplary, aiming to illustrate the problem and explain the present invention, and are not a kind of limitation.

[0031] (I) Raw Materials and Their Specifications

[0032] Table 1 Raw Materials and Specifications

[0033]

[0034]

[0035] (II) Basic Powder Raw Materials and Their Dosages

[0036]

[0037]

[0038] (III) Preparation Process Steps

[0039] 1. Premixing of Raw Materials

[0040] According to the formulation of the matrix layer powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. Turn on the rotary mixing device (rotation speed 1200 - 2000 rpm), and at the same time, introduce hot air at a temperature of 115 - 125 °C and a flow rate of 1.5 - 3 m / s to dry for 30 - 120 minutes, controlling the moisture content of the material ≤ 0.2%. Then transfer the material to a planetary ball mill for dry grinding. Use zirconia grinding balls (diameter 2 - 3 mm, ball-to-material ratio 3:1 - 8:1), and dry grind at a rotation speed of 400 - 700 rpm for 3 - 5 hours, and pass through a 1200-mesh sieve to obtain an ultra-fine and evenly mixed matrix layer premix.

[0041] The surface layer mixture is prepared by additionally adding 5% by mass of nano-Y2O6Si2O7 powder based on the matrix layer formulation. According to the formulation of the surface layer powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, nano-zirconia, and Y2O6Si2O7 are put into a fluidized bed dryer together. Turn on the rotary mixing device (rotation speed 1500 rpm), and at the same time, introduce hot air at a temperature of 115 - 125 °C and a flow rate of 1.5 - 3 m / s to dry for 30 - 120 minutes, controlling the moisture content of the material ≤ 0.2%. Then transfer the material to a planetary ball mill for dry grinding. Use zirconia grinding balls (diameter 2 - 3 mm, ball-to-material ratio 3:1 - 8:1), and dry grind at a rotation speed of 400 - 700 rpm for 3 - 5 hours, and pass through a 1200-mesh sieve to obtain an ultra-fine and evenly mixed surface layer premix.

[0042] 2. Mixing raw materials

[0043] Add a 15 - 20% magnesium dihydrogen phosphate solution to the matrix layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 10 - 20% of the total mass of the raw materials. Use wet ball milling for 20 - 30 minutes to form a uniform slurry. After drying the slurry at 80 °C for 12 hours, pass through a 100-mesh sieve to obtain the matrix layer mixture for standby.

[0044] Add a 15 - 20% magnesium dihydrogen phosphate solution to the surface layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 10 - 20% of the total mass of the raw materials. Use wet ball milling for 20 - 30 minutes to form a uniform slurry. After drying the slurry at 80 °C for 12 hours, pass through a 100-mesh sieve to obtain the surface layer mixture for standby.

[0045] 3. Molding

[0046] The forming process adopts the technologies of layered filling and cold isostatic pressing. First, the matrix layer mixture is filled into the mold, with a thickness of 90 - 95% of the total thickness. Subsequently, the surface layer mixture is filled, with a thickness of 5 - 10% of the total thickness. After the filling is completed, cold isostatic pressing is carried out at a pressure of 300 MPa for a holding time of 3 minutes to ensure the density and uniformity of the green body.

[0047] 4. Sintering

[0048] The sintering process includes three steps: pre-sintering, gas pressure sintering, and hot isostatic pressing. First, the formed green body is pre-sintered at 800 °C for 2 hours with a heating rate of 3 °C / min to remove the binder. Subsequently, gas pressure sintering is carried out at 1600 - 1700 °C for 2 hours with nitrogen at 10 MPa introduced and a heating rate of 5 °C / min. Finally, the sintered green body is subjected to hot isostatic pressing at 1500 °C in an argon atmosphere of 150 MPa for 1 hour, and the cooling rate is controlled at ≤5 °C / min to further eliminate internal defects and improve the material density. High-purity inert gases (nitrogen or argon) with an oxygen content of ≤10 ppm are used as the atmosphere for pre-sintering and gas pressure sintering.

[0049] 5. Post-treatment

[0050] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, the sintered part is immersed in molten borosilicate glass at 1200 - 1250 °C for 30 minutes to fill the surface pores. After impregnation, it is naturally cooled and the residual glass phase on the surface is removed. Subsequently, a 30 - 50 μm Al2O3 - YAG composite coating is deposited on the surface by plasma spraying, and the spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, spraying speed 200 mm / s. A densified anti-permeation zirconia refractory is obtained.

[0051] Example 1

[0052] Base powder raw materials and their dosages

[0053]

[0054] 1. Premixing of raw materials

[0055] According to the formula of the basic powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is started, and at the same time, hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced for drying for 60 minutes, and the moisture content of the material is controlled to be ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then sieved through a 1200-mesh sieve to obtain an ultra-fine and evenly mixed matrix layer premix.

[0056] The surface layer mixture is prepared by adding 5% by mass of nano-Y2O6Si2O7 powder additionally on the basis of the matrix layer formula. According to the ratio, the raw materials are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is started, and at the same time, hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced for drying for 60 minutes, and the moisture content of the material is controlled to be ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then sieved through a 1200-mesh sieve to obtain an ultra-fine and evenly mixed surface layer premix.

[0057] 2. Mixing raw materials

[0058] Magnesium dihydrogen phosphate solution with a concentration of 18% is added to the matrix layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 25 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is sieved through a 100-mesh sieve to obtain the matrix layer mixture for standby.

[0059] Magnesium dihydrogen phosphate solution with a concentration of 18% is added to the surface layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 30 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is sieved through a 100-mesh sieve to obtain the surface layer mixture for standby.

[0060] 3. Molding

[0061] The molding process adopts the technologies of layered filling and cold isostatic pressing. First, the matrix layer mixture is filled into the mold, with a thickness of 90% of the total thickness, and then the surface layer mixture is filled, with a thickness of 10% of the total thickness. After filling is completed, cold isostatic pressing is carried out at a pressure of 300 MPa and a holding pressure time of 3 minutes to ensure the density and uniformity of the green body.

[0062] 4. Sintering

[0063] The sintering process includes three steps: pre-sintering, gas-pressure sintering, and hot isostatic pressing. First, the formed green body is pre-sintered at 800 °C for 2 hours with a heating rate of 3 °C / min to remove the binder. Subsequently, it is gas-pressure sintered at 1600 °C for 2 hours while introducing nitrogen gas at 10 MPa with a heating rate of 5 °C / min. Finally, the sintered green body is subjected to hot isostatic pressing at 1500 °C under an argon atmosphere of 150 MPa for 1 hour, and the cooling rate is controlled at ≤5 °C / min to further eliminate internal defects and improve the material density. High-purity inert gas (nitrogen or argon) with an oxygen content of ≤10 ppm is used as the atmosphere for pre-sintering and gas-pressure sintering.

[0064] 5. Post-treatment

[0065] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, the sintered part is immersed in molten borosilicate glass at 1200 °C for 30 minutes to fill the surface pores. After impregnation, it is naturally cooled and the residual glass phase on the surface is removed. Subsequently, a 30-μm Al2O3-YAG composite coating is deposited on the surface using plasma spraying technology. The spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, and spraying speed 200 mm / s. A densified and anti-permeable zirconia refractory piece is obtained.

[0066] Example 2

[0067] Base powder raw materials and their dosages

[0068]

[0069]

[0070] 1. Premixing of raw materials

[0071] According to the formula of the base powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is started, and at the same time, hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced for drying for 60 minutes to control the moisture content of the material at ≤0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours. After passing through a 1200-mesh sieve, an ultra-fine and uniformly mixed matrix layer premix is obtained.

[0072] The surface layer premix is based on the matrix layer formula with an additional 5% by mass of nano Y2O6Si2O7 powder. According to the ratio, the raw materials are put into a fluidized bed dryer together, the rotary mixing device is started (rotation speed 1500 rpm), and at the same time, hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced for drying for 60 minutes, controlling the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then sieved through a 1200-mesh sieve to obtain an ultra-fine and uniformly mixed surface layer premix.

[0073] 2. Mixing raw materials

[0074] A 18% magnesium dihydrogen phosphate solution is added to the matrix layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 25 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is sieved through a 100-mesh sieve to obtain the matrix layer premix for standby.

[0075] A 18% magnesium dihydrogen phosphate solution is added to the surface layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 30 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is sieved through a 100-mesh sieve to obtain the surface layer premix for standby.

[0076] 3. Molding

[0077] The molding process uses the techniques of layered filling and cold isostatic pressing. First, the matrix layer premix is filled into the mold, with a thickness of 95% of the total thickness, and then the surface layer premix is filled, with a thickness of 5% of the total thickness. After filling is completed, cold isostatic pressing is carried out at a pressure of 300 MPa and a pressure holding time of 3 minutes to ensure the density and uniformity of the green body.

[0078] 4. Sintering

[0079] The sintering process includes three steps: pre-sintering, gas pressure sintering, and hot isostatic pressing. First, the formed green body is pre-sintered at 800 °C for 2 hours, with a heating rate of 3 °C / min to remove the binder. Subsequently, gas pressure sintering is carried out at 1700 °C for 2 hours, introducing nitrogen at 10 MPa, with a heating rate of 5 °C / min. Finally, the sintered green body is subjected to hot isostatic pressing treatment at 1500 °C and 150 MPa in an argon atmosphere for 1 hour, and the cooling rate is controlled ≤ 5 °C / min to further eliminate internal defects and improve the material density. The atmosphere for pre-sintering and gas pressure sintering uses high-purity inert gas (nitrogen or argon), with an oxygen content ≤ 10 ppm.

[0080] 5. Post-treatment

[0081] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, the sintered parts are immersed in molten borosilicate glass at 1250 °C for 30 minutes to fill the surface pores. After impregnation, they are cooled naturally and the residual glass phase on the surface is removed. Subsequently, a 50-μm Al2O3-YAG composite coating is deposited on the surface by plasma spraying, and the spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, spraying speed 200 mm / s. A densified and anti-permeable zirconia refractory is obtained.

[0082] Example 3

[0083] Base powder raw materials and their dosages

[0084]

[0085] 1. Premixing of raw materials

[0086] According to the formula of the base powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is started, and hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced simultaneously for drying for 60 minutes to control the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours. After passing through a 1200-mesh sieve, an ultra-fine and uniformly mixed matrix layer premix is obtained.

[0087] The surface layer premix is obtained by additionally adding 5% by mass of nano-Y2O6Si2O7 powder to the matrix layer formula. According to the ratio, the raw materials are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is started, and hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced simultaneously for drying for 60 minutes to control the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours. After passing through a 1200-mesh sieve, an ultra-fine and uniformly mixed surface layer premix is obtained.

[0088] 2. Mixing of raw materials

[0089] Magnesium dihydrogen phosphate solution with a concentration of 18% is added to the matrix layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 25 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is passed through a 100-mesh sieve to obtain the matrix layer mixture for standby.

[0090] Add a magnesium dihydrogen phosphate solution with a concentration of 18% to the surface layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Use wet ball milling for 30 minutes to form a uniform slurry. After drying the slurry at 80 °C for 12 hours, pass it through a 100-mesh sieve to obtain the surface layer mixture for standby.

[0091] 3. Molding

[0092] The molding process uses the techniques of layered filling and cold isostatic pressing. First, fill the matrix layer mixture into the mold, with a thickness of 90% of the total thickness. Subsequently, fill the surface layer mixture, with a thickness of 10% of the total thickness. After filling, use cold isostatic pressing with a pressure of 300 MPa and a holding time of 3 minutes to ensure the density and uniformity of the green body.

[0093] 4. Sintering

[0094] The sintering process includes three steps: pre-sintering, gas pressure sintering, and hot isostatic pressing. First, pre-sinter the formed green body at 800 °C for 2 hours with a heating rate of 3 °C / min to remove the binder. Subsequently, perform gas pressure sintering at 1650 °C for 2 hours, introduce nitrogen with a pressure of 10 MPa, and the heating rate is 5 °C / min. Finally, perform hot isostatic pressing on the sintered green body in an argon environment at 1500 °C and 150 MPa for 1 hour, and control the cooling rate to ≤5 °C / min to further eliminate internal defects and improve the material density. The atmosphere for pre-sintering and gas pressure sintering uses high-purity inert gas (nitrogen or argon) with an oxygen content of ≤10 ppm.

[0095] 5. Post-treatment

[0096] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, immerse the sintered part in molten borosilicate glass at 1250 °C for 30 minutes to fill the surface pores. After impregnation, cool naturally and remove the residual glass phase on the surface. Subsequently, use plasma spraying technology to deposit a 50-μm Al2O3-YAG composite coating on the surface. The spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, spraying speed 200 mm / s. A densified anti-permeation zirconia refractory piece is prepared.

[0097] Example 4

[0098] Base powder raw materials and their dosages

[0099]

[0100]

[0101] 1. Raw material premixing

[0102] According to the formula of the basic powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotary mixing device is turned on (rotation speed 1500 rpm), and at the same time, hot air at a temperature of 120°C and a flow rate of 2 m / s is introduced for drying for 60 minutes, controlling the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then sieved through a 1200-mesh sieve to obtain an ultra-fine and uniformly mixed matrix layer premix.

[0103] The surface layer mixture is prepared by adding 5% by mass of nano-Y2O6Si2O7 powder additionally on the basis of the matrix layer formula. According to the ratio, the raw materials are put into a fluidized bed dryer together. The rotary mixing device is turned on (rotation speed 1500 rpm), and at the same time, hot air at a temperature of 120°C and a flow rate of 2 m / s is introduced for drying for 60 minutes, controlling the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then sieved through a 1200-mesh sieve to obtain an ultra-fine and uniformly mixed surface layer premix.

[0104] 2. Mixing raw materials

[0105] Magnesium dihydrogen phosphate solution with a concentration of 18% is added to the matrix layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 25 minutes to form a uniform slurry. After the slurry is dried at 80°C for 12 hours, it is sieved through a 100-mesh sieve to obtain the matrix layer mixture for standby.

[0106] Magnesium dihydrogen phosphate solution with a concentration of 18% is added to the surface layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 30 minutes to form a uniform slurry. After the slurry is dried at 80°C for 12 hours, it is sieved through a 100-mesh sieve to obtain the surface layer mixture for standby.

[0107] 3. Molding

[0108] The molding process adopts the techniques of layered filling and cold isostatic pressing. First, the matrix layer mixture is filled into the mold, with a thickness of 95% of the total thickness. Subsequently, the surface layer mixture is filled in, with a thickness of 5% of the total thickness. After filling, cold isostatic pressing is carried out at a pressure of 300 MPa and a pressure holding time of 3 minutes to ensure the density and uniformity of the green body.

[0109] 4. Sintering

[0110] The sintering process includes three steps: pre-sintering, gas-pressure sintering, and hot isostatic pressing. First, the formed green body is pre-sintered at 800 °C for 2 hours with a heating rate of 3 °C / min to remove the binder. Subsequently, it is gas-pressure sintered at 1600 °C for 2 hours with nitrogen gas of 10 MPa introduced and a heating rate of 5 °C / min. Finally, the sintered green body is subjected to hot isostatic pressing treatment at 1500 °C and 150 MPa in an argon gas environment for 1 hour, and the cooling rate is controlled at ≤5 °C / min to further eliminate internal defects and improve the material density. High-purity inert gas (nitrogen or argon) is used as the atmosphere for pre-sintering and gas-pressure sintering, and the oxygen content is ≤10 ppm.

[0111] 5. Post-treatment

[0112] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, the sintered part is immersed in molten borosilicate glass at 1250 °C for 30 minutes to fill the surface pores. After impregnation, it is naturally cooled and the residual glass phase on the surface is removed. Subsequently, a 30-μm Al2O3-YAG composite coating is deposited on the surface by plasma spraying, and the spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, spraying speed 200 mm / s. A densified anti-permeation zirconia refractory piece is obtained.

[0113] Example 5

[0114] Base powder raw materials and their dosages

[0115]

[0116] 1. Premixing of raw materials

[0117] According to the formula of the base powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is turned on, and at the same time, hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced for drying for 60 minutes, and the moisture content of the material is controlled at ≤0.2%. Then the material is transferred to a planetary ball mill for dry grinding treatment. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then sieved through a 1200-mesh sieve to obtain an ultra-fine and uniformly mixed matrix layer premix.

[0118] The surface layer premix is prepared by adding 5% by mass of nano Y2O6Si2O7 powder to the matrix layer formulation. According to the ratio, the raw materials are put into a fluidized bed dryer together, the rotary mixing device (rotation speed 1500 rpm) is started, and at the same time, hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced for drying for 60 minutes to control the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then sieved through a 1200-mesh sieve to obtain ultrafine and uniformly mixed surface layer premix.

[0119] 2. Mixing raw materials

[0120] Magnesium dihydrogen phosphate solution with a concentration of 18% is added to the matrix layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 25 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is sieved through a 100-mesh sieve to obtain the matrix layer premix for standby.

[0121] Magnesium dihydrogen phosphate solution with a concentration of 18% is added to the surface layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 30 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is sieved through a 100-mesh sieve to obtain the surface layer premix for standby.

[0122] 3. Molding

[0123] The molding process adopts the technologies of layered filling and cold isostatic pressing. First, the matrix layer premix is filled into the mold, with a thickness of 95% of the total thickness, and then the surface layer premix is filled, with a thickness of 5% of the total thickness. After filling is completed, cold isostatic pressing is carried out at a pressure of 300 MPa and a holding pressure time of 3 minutes to ensure the density and uniformity of the green body.

[0124] 4. Sintering

[0125] The sintering process includes three steps: pre-sintering, gas pressure sintering and hot isostatic pressing. First, the formed green body is pre-sintered at 800 °C for 2 hours, and the heating rate is 3 °C / min to remove the binder. Subsequently, gas pressure sintering is carried out at 1700 °C for 2 hours, nitrogen with a pressure of 10 MPa is introduced, and the heating rate is 5 °C / min. Finally, the sintered green body is subjected to hot isostatic pressing treatment at 1500 °C and 150 MPa in an argon atmosphere for 1 hour, and the cooling rate is controlled at ≤ 5 °C / min to further eliminate internal defects and improve the material density. High-purity inert gas (nitrogen or argon) is used as the atmosphere for pre-sintering and gas pressure sintering, and the oxygen content ≤ 10 ppm.

[0126] 5. Post-treatment

[0127] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, the sintered parts are immersed in molten borosilicate glass at 1200 °C for 30 minutes to fill the surface pores. After impregnation, they are cooled naturally and the residual glass phase on the surface is removed. Subsequently, a 30-μm Al2O3-YAG composite coating is deposited on the surface by plasma spraying, with the spraying parameters as follows: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, and spraying speed 200 mm / s. A densified and anti-permeable zirconia refractory is obtained.

[0128] Example 6

[0129] Base powder raw materials and their dosages

[0130]

[0131]

[0132] 1. Premixing of raw materials

[0133] According to the formula of the base powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is turned on, and hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced simultaneously for drying for 60 minutes, controlling the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours. After passing through a 1200-mesh sieve, an ultra-fine and uniformly mixed matrix layer premix is obtained.

[0134] The surface layer mixture is obtained by adding 5% by mass of nano-Y2O6Si2O7 powder to the base of the matrix layer formula. According to the ratio, the raw materials are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is turned on, and hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced simultaneously for drying for 60 minutes, controlling the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours. After passing through a 1200-mesh sieve, an ultra-fine and uniformly mixed surface layer premix is obtained.

[0135] 2. Mixing of raw materials

[0136] Magnesium dihydrogen phosphate solution with a concentration of 18% is added to the matrix layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 25 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is passed through a 100-mesh sieve to obtain the matrix layer mixture for standby.

[0137] Add a magnesium dihydrogen phosphate solution with a concentration of 18% to the surface layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Use wet ball milling for 30 minutes to form a uniform slurry. After drying the slurry at 80 °C for 12 hours, sieve it through a 100-mesh sieve to obtain the surface layer mixture for standby.

[0138] 3. Molding

[0139] The molding process uses the technologies of layered filling and cold isostatic pressing. First, fill the matrix layer mixture into the mold with a thickness of 90% of the total thickness, and then fill the surface layer mixture with a thickness of 10% of the total thickness. After filling, perform cold isostatic pressing with a pressure of 300 MPa and a pressure holding time of 3 minutes to ensure the density and uniformity of the green body.

[0140] 4. Sintering

[0141] The sintering process includes three steps: pre-sintering, gas pressure sintering, and hot isostatic pressing. First, pre-sinter the molded green body at 800 °C for 2 hours with a heating rate of 3 °C / min to remove the binder. Subsequently, perform gas pressure sintering at 1650 °C for 2 hours, introduce nitrogen with a pressure of 10 MPa, and the heating rate is 5 °C / min. Finally, perform hot isostatic pressing on the sintered green body in an argon atmosphere at 1500 °C and 150 MPa for 1 hour, and control the cooling rate to ≤5 °C / min to further eliminate internal defects and improve the material density. The atmospheres for pre-sintering and gas pressure sintering use high-purity inert gases (nitrogen or argon) with an oxygen content ≤10 ppm.

[0142] 5. Post-treatment

[0143] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, immerse the sintered part in molten borosilicate glass at 1200 °C for 30 minutes to fill the surface pores. After impregnation, cool it naturally and remove the residual glass phase on the surface. Subsequently, use plasma spraying technology to deposit a 40-μm Al2O3-YAG composite coating on the surface. The spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, and spraying speed 200 mm / s. A densified anti-permeation zirconia refractory piece is prepared.

[0144] Comparative Example 1

[0145] Compared with Example 3, in Comparative Example 1, the matrix layer mixture and the surface layer mixture were not distinguished, but the same matrix layer mixture was used for one-piece molding.

[0146] Base powder raw materials and their dosages

[0147] Zirconia 1150 parts by mass;

[0148] 255 parts by mass of single-crystal powdered alumina;

[0149] 150 parts by mass of fused silica powder;

[0150] 75 parts by mass of boron compound;

[0151] 50 parts by mass of rare earth oxide;

[0152] 30 parts by mass of silicon carbide whiskers;

[0153] 80 parts by mass of nano-alumina;

[0154] 30 parts by mass of nano-zirconia.

[0155] 1. Premixing of raw materials

[0156] According to the formula of the basic powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotating mixing device (rotation speed 1500 rpm) is turned on, and at the same time, hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced for drying for 60 minutes to control the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then passed through a 1200-mesh sieve to obtain an ultra-fine and uniformly mixed matrix layer premix.

[0157] 2. Mixing raw materials

[0158] A 18% magnesium dihydrogen phosphate solution is added to the matrix layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Wet ball milling is carried out for 25 minutes to form a uniform slurry. After the slurry is dried at 80 °C for 12 hours, it is passed through a 100-mesh sieve to obtain the matrix layer mixture for standby.

[0159] 3. Molding

[0160] The matrix layer mixture is filled into the mold. After filling, cold isostatic pressing is carried out at a pressure of 300 MPa for a holding time of 3 minutes to ensure the density and uniformity of the green body.

[0161] 4. Sintering

[0162] The sintering process includes three steps: pre-sintering, gas-pressure sintering, and hot isostatic pressing. First, the formed green body is pre-sintered at 800 °C for 2 hours with a heating rate of 3 °C / min to remove the binder. Subsequently, gas-pressure sintering is carried out at 1650 °C for 2 hours with nitrogen at 10 MPa introduced, and the heating rate is 5 °C / min. Finally, the sintered green body is subjected to hot isostatic pressing in an argon environment at 1500 °C and 150 MPa for 1 hour, and the cooling rate is controlled at ≤5 °C / min to further eliminate internal defects and improve the material density. High-purity inert gas (nitrogen or argon) is used as the atmosphere for pre-sintering and gas-pressure sintering, and the oxygen content is ≤10 ppm.

[0163] 5. Post-treatment

[0164] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, the sintered part is immersed in molten borosilicate glass at 1250 °C for 30 minutes to fill the surface pores. After impregnation, it is cooled naturally and the residual glass phase on the surface is removed. Subsequently, a 50-μm Al2O3-YAG composite coating is deposited on the surface by plasma spraying, and the spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, spraying speed 200 mm / s. A densified and anti-permeable zirconia refractory is obtained.

[0165] Comparative Example 2

[0166] In Comparative Example 2 compared with Example 3, rare earth oxides were not added to the raw materials.

[0167] Base powder raw materials and their dosages

[0168]

[0169] 1. Premixing of raw materials

[0170] According to the formula of the base powder raw materials, zirconia, single-crystal powdered alumina, fused quartz powder, boron compound, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotating mixing device (rotation speed 1500 rpm) is started, and at the same time, hot air at a temperature of 120 °C and a flow rate of 2 m / s is introduced for drying for 60 minutes, controlling the moisture content of the material ≤0.2%. Then the material is transferred to a planetary ball mill for dry grinding treatment. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours, and then sieved through a 1200-mesh sieve to obtain an ultra-fine and uniformly mixed matrix layer premix.

[0171] The surface layer premix is based on the matrix layer formulation with an additional 5% by mass of nano - Y2O6Si2O7 powder. According to the ratio, the raw materials are put into a fluidized bed dryer together. Turn on the rotary mixing device (rotation speed 1500 rpm), and at the same time, pass hot air at a temperature of 120°C and a flow rate of 2 m / s for drying for 60 minutes, controlling the moisture content of the material ≤ 0.2%. Then transfer the material to a planetary ball mill for dry grinding. Use zirconia grinding balls (diameter 3 mm, ball - to - material ratio 5:1), and dry grind at a rotation speed of 500 rpm for 4 hours. Pass through a 1200 - mesh sieve to obtain an ultra - fine and uniformly mixed surface layer premix.

[0172] 2. Mixing raw materials

[0173] Add a 18% magnesium dihydrogen phosphate solution to the matrix layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Use wet ball milling for 25 minutes to form a uniform slurry. After drying the slurry at 80°C for 12 hours, pass through a 100 - mesh sieve to obtain the matrix layer premix for standby.

[0174] Add a 18% magnesium dihydrogen phosphate solution to the surface layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Use wet ball milling for 30 minutes to form a uniform slurry. After drying the slurry at 80°C for 12 hours, pass through a 100 - mesh sieve to obtain the surface layer premix for standby.

[0175] 3. Molding

[0176] The molding process uses the techniques of layered filling and cold isostatic pressing. First, fill the matrix layer premix into the mold, with a thickness of 90% of the total thickness. Subsequently, fill the surface layer premix, with a thickness of 10% of the total thickness. After filling, use cold isostatic pressing, with a pressure of 300 MPa and a pressure - holding time of 3 minutes to ensure the density and uniformity of the green body.

[0177] 4. Sintering

[0178] The sintering process includes three steps: pre - sintering, gas - pressure sintering, and hot isostatic pressing. First, pre - sinter the formed green body at 800°C for 2 hours, with a heating rate of 3°C / min to remove the binder. Subsequently, carry out gas - pressure sintering at 1650°C for 2 hours, introducing nitrogen at 10 MPa, with a heating rate of 5°C / min. Finally, perform hot isostatic pressing on the sintered green body in an argon environment at 1500°C and 150 MPa for 1 hour, controlling the cooling rate ≤ 5°C / min to further eliminate internal defects and improve the material density. The atmosphere for pre - sintering and gas - pressure sintering uses high - purity inert gas (nitrogen or argon), with an oxygen content ≤ 10 ppm.

[0179] 5. Post - treatment

[0180] The post-treatment includes two steps: molten salt impregnation and plasma spraying. First, the sintered parts are immersed in molten borosilicate glass at 1250 °C for 30 minutes to fill the surface pores. After impregnation, they are cooled naturally and the residual glass phase on the surface is removed. Subsequently, a 50-μm Al2O3-YAG composite coating is deposited on the surface by plasma spraying. The spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, and spraying speed 200 mm / s. A densified and anti-permeable zirconia refractory piece is obtained.

[0181] Comparative Example 3

[0182] Compared with Example 3, Comparative Example 3 omits the molten salt impregnation step in the post-treatment process.

[0183] Base powder raw materials and their dosages

[0184]

[0185] 1. Premixing of raw materials

[0186] According to the formula of the base powder raw materials, zirconia, single-crystal powdered alumina, fused silica powder, boron compound, rare earth oxide, silicon carbide whiskers, nano-alumina, and nano-zirconia are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is turned on, and hot air at a temperature of 120 °C and a flow rate of 2 m / s is passed through for 60 minutes to control the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours. After passing through a 1200-mesh sieve, an ultra-fine and uniformly mixed matrix layer premix is obtained.

[0187] The surface layer mixture is obtained by additionally adding 5% by mass of nano-Y2O6Si2O7 powder to the matrix layer formula. According to the ratio, the raw materials are put into a fluidized bed dryer together. The rotary mixing device (rotation speed 1500 rpm) is turned on, and hot air at a temperature of 120 °C and a flow rate of 2 m / s is passed through for 60 minutes to control the moisture content of the material ≤ 0.2%. Then the material is transferred to a planetary ball mill for dry grinding. Zirconia grinding balls (diameter 3 mm, ball-to-material ratio 5:1) are used, and dry grinding is carried out at a rotation speed of 500 rpm for 4 hours. After passing through a 1200-mesh sieve, an ultra-fine and uniformly mixed surface layer premix is obtained.

[0188] 2. Mixing of raw materials

[0189] Add a 18% magnesium dihydrogen phosphate solution to the matrix layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Use wet ball milling for 25 minutes to form a uniform slurry. After drying the slurry at 80 °C for 12 hours, sieve it through a 100-mesh sieve to obtain the matrix layer mixture for standby.

[0190] Add a 18% magnesium dihydrogen phosphate solution to the surface layer premix. The addition amount of the magnesium dihydrogen phosphate solution is 15% of the total mass of the raw materials. Use wet ball milling for 30 minutes to form a uniform slurry. After drying the slurry at 80 °C for 12 hours, sieve it through a 100-mesh sieve to obtain the surface layer mixture for standby.

[0191] 3. Molding

[0192] The molding process uses the techniques of layered filling and cold isostatic pressing. First, fill the matrix layer mixture into the mold, with a thickness of 90% of the total thickness. Subsequently, fill the surface layer mixture, with a thickness of 10% of the total thickness. After filling, perform cold isostatic pressing with a pressure of 300 MPa and a holding time of 3 minutes to ensure the density and uniformity of the green body.

[0193] 4. Sintering

[0194] The sintering process includes three steps: pre-sintering, gas pressure sintering, and hot isostatic pressing. First, pre-sinter the formed green body at 800 °C for 2 hours with a heating rate of 3 °C / min to remove the binder. Subsequently, perform gas pressure sintering at 1650 °C for 2 hours, introducing nitrogen at 10 MPa with a heating rate of 5 °C / min. Finally, perform hot isostatic pressing on the sintered green body in an argon environment at 1500 °C and 150 MPa for 1 hour, with the cooling rate controlled at ≤5 °C / min to further eliminate internal defects and improve the material density. The atmospheres for pre-sintering and gas pressure sintering use high-purity inert gases (nitrogen or argon) with an oxygen content ≤10 ppm.

[0195] 5. Post-treatment

[0196] The post-treatment is a plasma spraying step. Use plasma spraying technology to deposit a 50-μm Al2O3-YAG composite coating on the surface. The spraying parameters are: current 500 A, gas flow rate Ar / H2 = 45 / 15 SLPM, spraying distance 80 mm, spraying speed 200 mm / s. A densified anti-permeation zirconia refractory piece is prepared.

[0197] Table 2 Performance test results

[0198]

[0199]

[0200] Through the tests of the examples (Table 2), the zirconia refractory prepared by the present invention has excellent properties in terms of bulk density (≥5.85 g / cm 3 ), apparent porosity (≤0.32%), flexural strength (≥550 MPa), and glass melt penetration resistance (erosion depth ≤0.18 mm). Among them, Example 3 has outstanding performance, with a bulk density of 6.01 g / cm 3 , an apparent porosity of 0.25%, a flexural strength of 600 Mpa, and an erosion depth of 0.10 mm for glass melt penetration resistance. Combining with the test results of the comparative examples, it can be seen that the excellent comprehensive performance is due to the combined action of the gradient structure, grain boundary regulation, and surface defect repair.

[0201] Specifically, in the surface layer of the zirconia refractory prepared by the present invention, Y2O6Si2O7 and the matrix ZrO2 form a continuous Y-Si-O transition layer, making the Y element content show a gradient decreasing characteristic from the surface to the matrix. This gradient structure makes the coefficient of thermal expansion smoothly transition from about 5.8×10 -6 / °C on the surface layer to 10.5×10 -6 / °C in the matrix, significantly reducing the interfacial stress. This gradient structure effectively inhibits the phase transformation of ZrO2 into the monoclinic phase, endowing the material with excellent flexural strength and penetration resistance. Y 3 + / Ce 4 + exists in the form of a solid solution at the ZrO2 grain boundaries, forming a (Y,Ce)-O-Si-Al composite glass phase. This high-viscosity glass phase can effectively block the diffusion paths of erosion ions such as Ca 2 + / Na+, making the material show the minimum erosion depth in the glass melt erosion test. The erosion depth of Example 3 is 0.10 mm, which is 75% lower than that of Comparative Example 2 (0.40 mm) without rare earth addition. At the same time, rare earth doping also further increases the grain boundary binding energy, contributing to the improvement of flexural strength. During the post-treatment process of the material, through molten salt impregnation, the surface open porosity is significantly reduced, and the B2O3-SiO2 glass phase fills the defects with a size >1 μm through capillary action.

[0202] In addition, in the raw material treatment stage, by combining drying and mixing and then performing dry grinding, ultrafine and uniformly mixed matrix layer premix and surface layer premix can be efficiently obtained, which can significantly shorten the subsequent wet ball milling time. At the same time, it is also beneficial for batch preparation of premix, especially suitable for scenarios requiring large-scale production, significantly improving production efficiency and economic benefits. In addition, the obtained ultrafine powder can significantly improve the mixing effect, without the need for pretreatment by adding additional dispersants and modification methods such as silane coupling, simplifying the operation process while ensuring densification.

[0203] The above embodiments are exemplary, aiming to illustrate the technical concept and features of the present invention, so that those skilled in this field can understand the content of the present invention and implement it accordingly. However, it should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A grinding preparation method for ultrafine zirconia nano-composite powder, characterized in that: The preparation of the ultrafine matrix layer powder premix includes the following steps: According to the formula of the matrix layer powder raw materials, zirconia, single crystal alumina, fused quartz powder, boron compound, rare earth oxide, silicon carbide whisker, nano-alumina, and nano-zirconia are put into a fluidized bed drying equipment for combined drying and mixing treatment. Control the drying temperature at 115 - 125 °C and the hot air flow rate at 1.5 - 3 m / s until the moisture content of the material ≤ 0.2%; transfer the material to a ball milling equipment for dry milling treatment, use zirconia grinding balls with a diameter of 2 - 3 mm, control the ball-to-material ratio at 3 - 8:1, the rotation speed at 400 - 700 rpm, grind for 3 - 5 hours, and pass through a 1200-mesh sieve to obtain the ultrafine matrix layer premix; The preparation of the ultrafine surface layer powder premix includes the following steps: According to the formula of the surface layer powder raw materials, zirconia, single crystal powdered alumina, fused quartz powder, boron compound, rare earth oxide, silicon carbide whisker, nano-alumina, nano-zirconia, and Y2O6Si2O7 are put into a fluidized bed drying equipment for combined drying and mixing treatment. Control the drying temperature at 115 - 125 °C and the hot air flow rate at 1.5 - 3 m / s until the moisture content of the material ≤ 0.2%; transfer the material to a ball milling equipment for dry milling treatment, use zirconia grinding balls with a diameter of 2 - 3 mm, control the ball-to-material ratio at 3 - 8:1, the rotation speed at 400 - 700 rpm, grind for 3 - 5 hours, and pass through a 1200-mesh sieve to obtain the ultrafine surface layer premix.

2. The grinding preparation method of the ultrafine zirconia nanocomposite powder according to claim 1, characterized in that: The raw materials of the ultrafine matrix layer premix include the following components:

3. The grinding preparation method of the ultrafine zirconia nano-composite powder according to claim 2, characterized in that: The raw materials of the ultrafine surface layer premix are based on the raw materials of the ultrafine matrix layer premix and add 5% by mass of nano-Y2O6Si2O7 powder.

4. An ultrafine zirconia nano-composite powder, characterized in that: It includes the ultrafine matrix layer powder premix and the ultrafine surface layer premix prepared by the method according to any one of claims 1 - 3.

5. The method for preparing a refractory piece from the ultrafine zirconia nanocomposite powder according to claim 4, characterized in that: It includes the following steps: Mix raw materials: Add a 15 - 20% magnesium dihydrogen phosphate solution to the matrix layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 10 - 20% of the total mass of the raw materials. Use wet ball milling for 20 - 30 minutes to form a uniform slurry; dry and sieve to obtain the matrix layer mixture; Add a 15 - 20% magnesium dihydrogen phosphate solution to the surface layer premix, and the addition amount of the magnesium dihydrogen phosphate solution is 10 - 20% of the total mass of the raw materials. Use wet ball milling for 20 - 30 minutes to form a uniform slurry; dry and sieve to obtain the surface layer mixture; Load and mold the raw materials: Fill the matrix layer mixture into a mold with a thickness of 90 - 95% of the total thickness, and then fill the surface layer mixture with a thickness of 5 - 10% of the total thickness; after filling, perform cold isostatic pressing for molding; Sinter the molded blank: Pre-sinter the molded blank to remove the binder, then perform gas pressure sintering under a protective atmosphere, and then perform hot isostatic pressing on the sintered blank to further eliminate internal defects and improve the material density; Post-treat the sintered part: Perform molten salt impregnation and plasma spraying treatment on the sintered part to obtain a densified anti-permeation zirconia refractory part.

6. The method for preparing a refractory piece with the ultrafine zirconia nanocomposite powder according to claim 5, characterized in that: During the raw material loading and forming process, the cold isostatic pressing forming pressure is 250 - 350 MPa, and the pressure holding time is 2 - 5 minutes.

7. The method for preparing a refractory piece from the ultrafine zirconia nanocomposite powder according to claim 5, characterized in that: During the sintering process of the formed green body, the formed green body is pre-sintered at 780 - 820 °C for 1 - 5 hours with a heating rate of 2 - 4 °C / min to remove the binder; subsequently, it is gas pressure sintered at 1600 - 1700 °C for 1 - 3 hours with nitrogen of 8 - 12 MPa introduced and a heating rate of 4 - 6 °C / min; then the sintered green body is hot isostatically pressed at 1400 - 1600 °C under an argon atmosphere of 120 - 180 MPa for 0.8 - 1.5 hours, and the cooling rate is controlled at ≤5 °C / min to further eliminate internal defects and improve the material density.

8. The method for preparing a refractory piece with the ultrafine zirconia nanocomposite powder according to claim 5, wherein: The oxygen content in the atmosphere used for pre-sintering and gas pressure sintering is ≤10 ppm.

9. The method for preparing a refractory using the ultrafine zirconia nanocomposite powder according to claim 5, characterized in that: During the post-treatment process of the sintered part, the sintered part is immersed in molten borosilicate glass at 1200 - 1250 °C for 25 - 40 minutes to fill the surface pores; after impregnation, it is naturally cooled and the residual glass phase on the surface is removed.

10. The method for preparing a refractory piece from the ultrafine zirconia nanocomposite powder according to claim 5, characterized in that: During the post-treatment process of the sintered part, after molten salt impregnation, a 30 - 50 μm thick Al2O3 - YAG composite coating is deposited on the surface by plasma spraying.

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