A corundum sagger for high-purity alumina ceramics high-temperature sintering and its preparation method

Abstract

The present invention discloses a corundum sagger for high-temperature sintering of high-purity alumina ceramics and a preparation method thereof. The specific steps of the present invention are as follows: step S1, mixing sintered corundum particles and premixed fine powder in a certain mass ratio to obtain a premix; the premixed fine powder includes sintered corundum fine powder, fused zirconium corundum fine powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder and amorphous alumina fine powder; step S2, adding a certain mass of potato starch and ρ-alumina colloidal solution to the premix in sequence, and mixing them evenly to obtain a mixture; step S3, sealing the mixture to obtain a plastic material; step S4, demolding the plastic material after molding to obtain a green body; step S5, hot-pressing and sintering the green body to obtain a corundum sagger for high-purity alumina ceramics. The corundum sagger for high-temperature sintering of high-purity alumina ceramics prepared by the present invention has a high service temperature, good sintering performance, high strength, high load softening temperature and good thermal shock resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of saggers, and in particular to a corundum sagger for high-purity alumina ceramics high-temperature sintering and a preparation method thereof. Background Art

[0002] Alumina ceramics are ceramic materials with high-purity alumina as the main body. They are mainly used in thick film integrated circuits, electronic components or electronic ceramics. Their alumina content is as high as 99.9% or more, which belongs to the category of typical high-purity alumina ceramics. Zhang Hailin, Lin Tongzhi. Research on the manufacturing and performance of alumina ceramic products[J]. Science and Technology Information, 2017, 15(16): 128- 129 ).

[0003] At present, the sintering of alumina ceramics mainly adopts corundum sagger (which does not pollute the alumina ceramic products carried by it) and is fired under high temperature conditions, with a firing temperature of about 1700-1780℃. It can be seen that in high temperature service environment, the performance requirements of corundum sagger are more stringent ( Cai Xiaofeng. Kiln materials and technology for firing electronic ceramics[J]. Ceramic Science and Technology Art, 2002(02):44-47 ), which is specifically manifested in the following aspects:

[0004] (1) Strong high-temperature structural stability. Under high-temperature service environment (≥1700℃), the structural stability of the corundum sagger is the most important, and it must not soften, deform or crack. Therefore, the corundum sagger is required to have strong high-temperature resistance, high purity and low impurity content.

[0005] (2) Low component decomposition pressure. Oxide components will also decompose at high temperatures, which depends on the size of the decomposition pressure. The decomposition pressure of oxides increases with increasing temperature. The greater the decomposition pressure, the easier it is for the decomposition reaction to occur. Therefore, the inclusion of oxides with high decomposition pressures (such as Cr2O3, SiO2, etc.) in corundum saggers should be strictly avoided. Otherwise, the decomposition at high temperatures will lead to "pores" on the sagger surface, and the escape of gas components will easily cause the loaded alumina ceramics to crack, increasing the scrap rate of the ceramic material.

[0006] (3) High thermal shock stability. The development cost of corundum saggers is relatively high, and the ceramic products they carry are high-value and precise. Therefore, the corundum saggers are required to be recycled many times to improve economic benefits, which puts strict requirements on the thermal shock stability of the corundum saggers.

[0007] (4) Good sintering performance. As mentioned above, the service environment of corundum saggers is a high temperature condition, so the firing temperature of the saggers is also high. How to improve the sintering performance of corundum saggers without introducing impurities, reduce the sintering temperature of the saggers while saving energy and protecting the environment, which obviously has good social and economic benefits.

[0008] At present, there are few reports on high-purity corundum saggers, and they are still mainly made of Al2O3-SiO2-based corundum-mullite or mullite-corundum composite materials. The raw materials are mainly corundum, high-alumina bauxite or high-purity mullite, which are mixed evenly and then formed and fired at high temperature. However, the saggers made of Al2O3-SiO2 can show good high-temperature resistance under conditions below 1600℃, but when the temperature is higher than 1700℃, the sagger function fails and the service is terminated due to problems such as the evaporation of components (SiO2 is more easily decomposed and volatilized than Al2O3). Summary of the Invention

[0009] The purpose of the present invention is to address the above-mentioned shortcomings of the prior art and provide a corundum sagger for high-purity alumina ceramics for high-temperature sintering and a preparation method thereof. The corundum sagger for high-purity alumina ceramics for high-temperature sintering prepared by this method has a high service temperature, good sintering performance, high strength, high load softening temperature and good thermal shock resistance.

[0010] The present invention provides a method for preparing a corundum sagger for high-purity alumina ceramics for high-temperature sintering, comprising the following specific steps:

[0011] Step S1, mixing sintered corundum particles and premixed fine powder in a certain mass ratio to obtain a premix; the premixed fine powder includes sintered corundum fine powder, fused zirconium corundum fine powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder and amorphous alumina fine powder;

[0012] Step S2, adding a certain amount of potato starch and p-alumina colloidal solution to the premix in sequence, and mixing them uniformly to obtain a mixture;

[0013] Step S3, sealing the mixed material to obtain a plastic material;

[0014] Step S4, molding the plastic material and then demoulding it to obtain a green body;

[0015] Step S5, hot pressing and sintering the green body to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics;

[0016] The ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in potassium fluorozirconate solution.

[0017] Furthermore, in the premixed fine powder, the mass ratio of sintered corundum fine powder, fused zirconium corundum fine powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder and amorphous alumina fine powder is 100:(30-35):(6-8):(2.2-2.8):(15-25).

[0018] Furthermore, the mass ratio of the sintered corundum particles to the premixed fine powder is 100:(65-70).

[0019] Furthermore, the potato starch accounts for 1.2 to 1.6 wt% of the premix.

[0020] Furthermore, the ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in a potassium fluorozirconate solution with a concentration of 1.5-1.8 mol / L, and the mass ratio of ρ-alumina fine powder: potassium fluorozirconate solution is 1:(8-16); the ρ-alumina colloidal solution accounts for 3.3-3.6 wt% of the premix mass.

[0021] Furthermore, the specific operation of step S4 is: placing the plastic material in the mold, pressing and exhausting at 25-35 MPa, maintaining the pressure for 40-60 seconds, and then increasing the pressure to 75-85 MPa, maintaining the pressure for 30-40 seconds, and then increasing the pressure to 180-220 MPa, maintaining the pressure for 20-30 seconds, and demolding to obtain a green body.

[0022] Furthermore, the specific operation of step S5 is: placing the green body in a hot pressing sintering furnace, firing it at 1670-1680°C, the hot pressing sintering atmosphere is an air atmosphere, the pressure is 0.2-0.3 MPa, and then cooling it to room temperature after keeping it warm for 2-4 hours to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics.

[0023] Furthermore, the particle size of the sintered corundum fine powder is 25 to 30 μm; and / or,

[0024] The particle size of the fused zirconium corundum fine powder is 40 to 50 μm, and the ZrO2 content is 6 to 8 wt%; and / or,

[0025] The product grade of rare earth composite yttrium zirconium ceramic powder is YZ7.2QLA, see GB / T31968-2015; and / or,

[0026] The particle size of the cerium phosphate powder is 15 to 25 μm, and the CePO4 content is ≥ 98 wt%; and / or,

[0027] The amorphous alumina fine powder is amorphous, has a particle size of 5 to 8 μm, and an Al2O3 content of ≥99.5 wt%.

[0028] Furthermore, the particle size of the sintered corundum particles is 0.1-2.5 mm, wherein the mass ratio of [0.1-0.5 mm] particles, [1-1.5 mm] particles and [2-2.5 mm] particles is (15-20): (45-50): (25-30).

[0029] A corundum sagger for high-temperature sintering of high-purity alumina ceramics prepared by the above preparation method.

[0030] The beneficial effects of the present invention are:

[0031] (1) The present invention starts from the raw material system and selects high-purity alumina as the starting raw material to avoid the introduction of impurity components, thereby improving the purity of the corundum sagger and improving its high-temperature service performance.

[0032] (2) The present invention utilizes rare earth phosphate to form a good ceramic bond in the medium temperature range (600-1200°C), and combines Ce 4+ The alivalent substitution solid solution promotes Al 3+ The diffusion and migration of particles can improve the medium-temperature strength of the sagger, avoid structural cracking of the sagger during firing, and improve the yield of the sagger.

[0033] (3) The present invention utilizes the high temperature characteristics of rare earth composite oxides to form zirconium yttrium aluminum garnet solid solution in situ during the high temperature sintering process of corundum crucible, promotes the growth and development of alumina grains and the connection of crystal phases, and improves the load softening temperature and high temperature structural strength and stability of the crucible.

[0034] (4) The present invention utilizes the amorphous properties of amorphous alumina fine powder to reduce the activation energy of grain rearrangement during sintering, effectively reducing the sintering temperature of the corundum crucible and saving energy.

[0035] (5) The present invention improves the solid solubility of rare earth composite oxides by hot pressing and sintering, and at the same time utilizes the obstruction of the non-wetting solid solution interface layer to avoid adhesion and sintering between the corundum sagger and the supported high-purity alumina ceramic products, thereby preventing the corundum sagger from causing contamination to the supported ceramic products and improving the yield of the supported ceramics.

[0036] (6) The present invention utilizes the hydrolysis and ionization of ρ-Al2O3 to form [ZrF6] 2- and [-Al-OH-] 2+ The ion-coated long chain effectively improves the bonding performance between the matrix fine powder and the corundum aggregate. At the same time, no impurity components are introduced into the bonding system, and the bonding strength of the green body is guaranteed. The high-temperature escape of volatile components can offset the volume expansion caused by the growth and development of Al2O3 grains, thereby improving the high-temperature volume stability of the corundum sagger.

[0037] The corundum sagger for high-temperature sintering of high-purity alumina ceramics prepared by the present invention has the following test results: the yield is ≥98.2%; the service temperature is ≥1850°C; the relative density is 95.7-96.6%, the compressive strength is 182-191 MPa, the refractoriness under load is ≥1820°C, the reheating line change rate is 0.04-0.07%, and the residual flexural strength retention rate after three cycles of 1100°C air quenching is 91.3-92.4%.

[0038] Therefore, the corundum sagger for high-temperature sintering of high-purity alumina ceramics prepared by the present invention has high service temperature, good sintering performance, high strength, high load softening temperature and good thermal shock resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a photo of the appearance of the corundum sagger for high-temperature sintering of high-purity alumina ceramics prepared in Example 1;

[0040] Figure 2 This is a SEM photograph of the corundum sagger for high-temperature sintering of high-purity alumina ceramics prepared in Example 1. DETAILED DESCRIPTION

[0041] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0042] Example 1

[0043] Step 1: Prepare a premixed fine powder of sintered corundum powder, fused zirconium corundum powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder, and amorphous alumina powder in a mass ratio of 100:32:8:2.3:22, add the mixture to a roller mixer, and mix for 55 minutes to obtain a premixed fine powder.

[0044] Step 2: Sintered corundum particles and premixed fine powder were mixed in a roller mixer at a mass ratio of 100:66 and mixed for 28 minutes to obtain a premix;

[0045] Step 3: Add 1.4 wt% of potato starch and 3.5 wt% of p-alumina colloidal solution to the premix in sequence, and mix in a planetary mixer for 15 minutes to obtain a mixture;

[0046] Step 4: Seal the mixture at 22°C for 4 hours to obtain a plastic material;

[0047] Step 5: Place the plastic material in the mold, pressurize and exhaust at 33 MPa, hold the pressure for 45 seconds, then increase the pressure to 78 MPa, hold the pressure for 32 seconds, then increase the pressure to 195 MPa, hold the pressure for 26 seconds, and demould to obtain a green body.

[0048] Step 6: Place the green body in a hot pressing sintering furnace and sinter it at 1678°C in an air atmosphere with a pressure of 0.24 MPa. Keep warm for 3 hours and then cool to room temperature to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics.

[0049] The ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in a potassium fluorozirconate solution with a concentration of 1.5 mol / L, and the mass ratio of ρ-alumina fine powder to potassium fluorozirconate solution is 1:12.

[0050] The particle size of sintered corundum fine powder is 25 to 30 μm.

[0051] The particle size of the fused zirconium corundum fine powder is 40-50 μm, and the ZrO2 content is 6-8 wt%.

[0052] The product brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2QLA, refer to GB / T31968-2015.

[0053] The particle size of the cerium phosphate powder is 15-25 μm, and the CePO4 content is ≥98 wt%.

[0054] The amorphous alumina fine powder is amorphous, has a particle size of 5 to 8 μm, and an Al2O3 content of ≥99.5 wt%.

[0055] The particle size of the sintered corundum particles is 0.1-2.5 mm, wherein the mass ratio of [0.1-0.5 mm] particles, [1-1.5 mm] particles and [2-2.5 mm] particles is 16:48:27.

[0056] The high-purity alumina ceramic corundum sagger for high-temperature sintering prepared in this embodiment was tested to have a finished product rate of 98.4%, a service temperature of 1860°C, a relative density of 96.2%, a compressive strength of 187 MPa, a refractoriness temperature under load of 1820°C, a reheating line change rate of 0.07%, and a residual flexural strength retention rate of 91.7% after three cycles of 1100°C air quenching.

[0057] Figure 1 This is a photo of the appearance of the corundum sagger for high-temperature sintering of high-purity alumina ceramics prepared in this example. It can be seen that the sagger structure is complete, and the bottom, side walls, and especially the corner joints are flat, dense, and smooth.

[0058] Figure 2 This is an SEM photo of a corundum sagger used for high-temperature sintering of high-purity alumina ceramics. It can be seen that the internal structure of the sagger is dense, and the corundum particles and matrix fine powder form a good sintering bond, with no obvious low-melting phase.

[0059] Example 2

[0060] Step 1: Sintered corundum fine powder: fused zirconium corundum fine powder: rare earth composite yttrium zirconium ceramic powder: cerium phosphate powder: amorphous alumina fine powder in a mass ratio of 100:30:7:2.2:15 were added to a roller mixer and mixed for 85 minutes to obtain a premixed fine powder;

[0061] Step 2: Sintered corundum particles and premixed fine powder were mixed in a roller mixer at a mass ratio of 100:68 and mixed for 25 minutes to obtain a premix;

[0062] Step 3: Add 1.5 wt% of potato starch and 3.3 wt% of p-alumina colloidal solution to the premix in sequence, and mix in a planetary mixer for 12 minutes to obtain a mixture;

[0063] Step 4: Seal the mixture at 25°C for 6 hours to obtain a plastic material;

[0064] Step 5: Place the plastic material in the mold, pressurize and exhaust at 30 MPa, hold the pressure for 40 seconds, then increase the pressure to 80 MPa, hold the pressure for 30 seconds, then increase the pressure to 200 MPa, hold the pressure for 25 seconds, and demould to obtain a green body.

[0065] Step 6: Place the green body in a hot pressing sintering furnace and sinter it at 1680°C in an air atmosphere with a pressure of 0.2 MPa. Keep warm for 3 hours and then cool to room temperature to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics.

[0066] The ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in a potassium fluorozirconate solution with a concentration of 1.8 mol / L, and the mass ratio of the ρ-alumina fine powder to the potassium fluorozirconate solution is 1:10.

[0067] The particle size of sintered corundum fine powder is 25 to 30 μm.

[0068] The particle size of the fused zirconium corundum fine powder is 40-50 μm, and the ZrO2 content is 6-8 wt%.

[0069] The product brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2QLA, refer to GB / T31968-2015.

[0070] The particle size of the cerium phosphate powder is 15-25 μm, and the CePO4 content is ≥98 wt%.

[0071] The amorphous alumina fine powder is amorphous, has a particle size of 5 to 8 μm, and an Al2O3 content of ≥99.5 wt%.

[0072] The sintered corundum particles had a particle size of 0.1 to 2.5 mm, with a mass ratio of 0.1 to 0.5 mm particles, 1 to 1.5 mm particles, and 2 to 2.5 mm particles of 15:50:25. Testing of the high-purity alumina ceramic sagger for high-temperature sintering prepared in this example revealed a 98.5% yield, a service temperature of 1860°C, a relative density of 96.6%, a compressive strength of 190 MPa, a refractoriness under load of 1825°C, a reheat line change of 0.07%, and a 91.3% retention of residual flexural strength after three cycles of 1100°C air quenching.

[0073] Example 3

[0074] Step 1: Prepare a premixed fine powder of sintered corundum powder, fused zirconium corundum powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder, and amorphous alumina powder in a mass ratio of 100:35:6:2.4:25, add the mixture to a roller mixer, and mix for 60 minutes to obtain a premixed fine powder.

[0075] Step 2: Sintered corundum particles and premixed fine powder are mixed in a roller mixer at a mass ratio of 100:65 and mixed for 30 minutes to obtain a premix;

[0076] Step 3: Add 1.2 wt% of potato starch and 3.5 wt% of p-alumina colloidal solution to the premix in sequence, and mix in a planetary mixer for 15 minutes to obtain a mixture;

[0077] Step 4: Seal the mixture at 20°C for 4 hours to obtain a plastic material;

[0078] Step 5: Place the plastic material in the mold, pressurize and exhaust at 35 MPa, hold the pressure for 60 seconds, then increase the pressure to 75 MPa, hold the pressure for 40 seconds, then increase the pressure to 220 MPa, hold the pressure for 20 seconds, and demould to obtain a green body;

[0079] Step 6: Place the green body in a hot pressing sintering furnace and sinter it at 1670°C in an air atmosphere with a pressure of 0.3 MPa. Keep warm for 2 hours and then cool to room temperature to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics.

[0080] The ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in a potassium fluorozirconate solution with a concentration of 1.5 mol / L, and the mass ratio of ρ-alumina fine powder to potassium fluorozirconate solution is 1:8.

[0081] The particle size of sintered corundum fine powder is 25 to 30 μm.

[0082] The particle size of the fused zirconium corundum fine powder is 40-50 μm, and the ZrO2 content is 6-8 wt%.

[0083] The product brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2QLA, refer to GB / T31968-2015.

[0084] The particle size of the cerium phosphate powder is 15-25 μm, and the CePO4 content is ≥98 wt%.

[0085] The amorphous alumina fine powder is amorphous, has a particle size of 5 to 8 μm, and an Al2O3 content of ≥99.5 wt%.

[0086] The particle size of the sintered corundum particles is 0.1-2.5 mm, wherein the mass ratio of [0.1-0.5 mm] particles, [1-1.5 mm] particles and [2-2.5 mm] particles is 20:45:30.

[0087] The high-purity alumina ceramic corundum sagger for high-temperature sintering prepared in this embodiment was tested to have a finished product rate of 98.2%, a service temperature of 1855°C, a relative density of 96.3%, a compressive strength of 182 MPa, a refractoriness temperature under load of 1820°C, a reheating line change rate of 0.04%, and a residual flexural strength retention rate of 92.2% after three cycles of 1100°C air quenching.

[0088] Example 4

[0089] Step 1: Prepare a premixed fine powder of sintered corundum powder, fused zirconium corundum powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder, and amorphous alumina powder in a mass ratio of 100:33:8:2.8:20, add the mixture to a roller mixer, and mix for 50 minutes to obtain a premixed fine powder.

[0090] Step 2: Sintered corundum particles and premixed fine powder were mixed in a roller mixer at a mass ratio of 100:70 and mixed for 26 minutes to obtain a premix;

[0091] Step 3: Add 1.6 wt% of potato starch and 3.6 wt% of p-alumina colloidal solution to the premix in sequence, and mix in a planetary mixer for 10 minutes to obtain a mixture;

[0092] Step 4: Seal the mixture at 24°C for 5 hours to obtain a plastic material;

[0093] Step 5: Place the plastic material in the mold, pressurize and exhaust at 25 MPa, hold the pressure for 50 seconds, then increase the pressure to 85 MPa, hold the pressure for 35 seconds, then increase the pressure to 180 MPa, hold the pressure for 30 seconds, and demould to obtain a green body.

[0094] Step 6: Place the green body in a hot pressing sintering furnace and sinter it at 1675°C in an air atmosphere with a pressure of 0.25 MPa. Keep warm for 4 hours and then cool to room temperature to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics.

[0095] The ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in a potassium fluorozirconate solution with a concentration of 1.6 mol / L, and the mass ratio of ρ-alumina fine powder to potassium fluorozirconate solution is 1:16.

[0096] The particle size of sintered corundum fine powder is 25 to 30 μm.

[0097] The particle size of the fused zirconium corundum fine powder is 40-50 μm, and the ZrO2 content is 6-8 wt%.

[0098] The product brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2QLA, refer to GB / T31968-2015.

[0099] The particle size of the cerium phosphate powder is 15-25 μm, and the CePO4 content is ≥98 wt%.

[0100] The amorphous alumina fine powder is amorphous, has a particle size of 5 to 8 μm, and an Al2O3 content of ≥99.5 wt%.

[0101] The sintered corundum particles had a particle size of 0.1 to 2.5 mm, with a mass ratio of 0.1 to 0.5 mm particles, 1 to 1.5 mm particles, and 2 to 2.5 mm particles of 18:46:28. Testing of the high-purity alumina ceramic sagger for high-temperature sintering prepared in this example revealed a 98.9% yield, a service temperature of 1850°C, a relative density of 95.7%, a compressive strength of 191 MPa, a refractoriness under load of 1825°C, a reheat line change of 0.05%, and a 92.4% retention of residual flexural strength after three cycles of 1100°C air quenching.

[0102] Comparative Example 1

[0103] Step 1: Sintered corundum fine powder: fused zirconium corundum fine powder: rare earth composite yttrium zirconium ceramic powder: cerium phosphate powder: amorphous alumina fine powder in a mass ratio of 100:30:7:0.2:15 were added to a roller mixer and mixed for 85 minutes to obtain a premixed fine powder;

[0104] Step 2: Sintered corundum particles and premixed fine powder were mixed in a roller mixer at a mass ratio of 100:68 and mixed for 25 minutes to obtain a premix;

[0105] Step 3: Add 1.5 wt% of potato starch and 3.3 wt% of p-alumina colloidal solution to the premix in sequence, and mix in a planetary mixer for 12 minutes to obtain a mixture;

[0106] Step 4: Seal the mixture at 25°C for 6 hours to obtain a plastic material;

[0107] Step 5: Place the plastic material in the mold, pressurize and exhaust at 30 MPa, hold the pressure for 40 seconds, then increase the pressure to 80 MPa, hold the pressure for 30 seconds, then increase the pressure to 200 MPa, hold the pressure for 25 seconds, and demould to obtain a green body.

[0108] Step 6: Place the green body in a hot pressing sintering furnace and sinter it at 1680°C in an air atmosphere with a pressure of 0.2 MPa. Keep warm for 3 hours and then cool to room temperature to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics.

[0109] The ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in a potassium fluorozirconate solution with a concentration of 1.8 mol / L, and the mass ratio of the ρ-alumina fine powder to the potassium fluorozirconate solution is 1:10.

[0110] The particle size of sintered corundum fine powder is 25 to 30 μm.

[0111] The particle size of the fused zirconium corundum fine powder is 40-50 μm, and the ZrO2 content is 6-8 wt%.

[0112] The product brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2QLA, refer to GB / T31968-2015.

[0113] The particle size of the cerium phosphate powder is 15-25 μm, and the CePO4 content is ≥98 wt%.

[0114] The amorphous alumina fine powder is amorphous, has a particle size of 5 to 8 μm, and an Al2O3 content of ≥99.5 wt%.

[0115] The particle size of the sintered corundum particles is 0.1-2.5 mm, wherein the mass ratio of [0.1-0.5 mm] particles, [1-1.5 mm] particles and [2-2.5 mm] particles is 15:50:25.

[0116] The corundum sagger prepared in this comparative example was tested to have the following characteristics: a finished product rate of 91.2%, a service temperature of 1700°C, a relative density of 89.5%, a compressive strength of 110 MPa, a refractoriness under load of 1680°C, a reheating line change rate of 0.05%, and a residual flexural strength retention rate of 82.4% after three cycles of 1100°C air quenching.

[0117] It can be seen that the addition amount of cerium phosphate powder is significantly reduced, resulting in a decrease in the degree of solid solution during sintering, which in turn causes structural damage to the sagger, significantly reduces the strength and high-temperature service performance of the sagger, and also leads to a decrease in the yield of the sagger.

[0118] Comparative Example 2

[0119] Step 1: Prepare a premixed fine powder of sintered corundum powder, fused zirconium corundum powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder, and amorphous alumina powder in a mass ratio of 100:35:6:2.4:25, add the mixture to a roller mixer, and mix for 60 minutes to obtain a premixed fine powder.

[0120] Step 2: Sintered corundum particles and premixed fine powder are mixed in a roller mixer at a mass ratio of 100:65 and mixed for 30 minutes to obtain a premix;

[0121] Step 3: Add 1.2 wt% of potato starch and 3.5 wt% of p-alumina colloidal solution to the premix in sequence, and mix in a planetary mixer for 15 minutes to obtain a mixture;

[0122] Step 4: Seal the mixture at 20°C for 4 hours to obtain a plastic material;

[0123] Step 5: Place the plastic material in a mold, shape it at 220 MPa, and demould it to obtain a green body;

[0124] Step 6: Place the green body in a hot pressing sintering furnace and sinter it at 1670°C in an air atmosphere with a pressure of 0.3 MPa. Keep warm for 2 hours and then cool to room temperature to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics.

[0125] The ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in a potassium fluorozirconate solution with a concentration of 1.5 mol / L, and the mass ratio of ρ-alumina fine powder to potassium fluorozirconate solution is 1:8.

[0126] The particle size of sintered corundum fine powder is 25 to 30 μm.

[0127] The particle size of the fused zirconium corundum fine powder is 40-50 μm, and the ZrO2 content is 6-8 wt%.

[0128] The product brand of rare earth composite yttrium zirconium ceramic powder is YZ7.2QLA, refer to GB / T31968-2015.

[0129] The particle size of the cerium phosphate powder is 15-25 μm, and the CePO4 content is ≥98 wt%.

[0130] The amorphous alumina fine powder is amorphous, has a particle size of 5 to 8 μm, and an Al2O3 content of ≥99.5 wt%.

[0131] The particle size of the sintered corundum particles is 0.1-2.5 mm, wherein the mass ratio of [0.1-0.5 mm] particles, [1-1.5 mm] particles and [2-2.5 mm] particles is 20:45:30.

[0132] The corundum sagger prepared in this comparative example was tested: the finished product rate was 82.5%; the service temperature was 1650℃; the relative density was 85.3%, the compressive strength was 97MPa, the refractoriness temperature under load was 1610℃, the reheating line change rate was 0.02%, and the residual flexural strength retention rate after three cycles of 1100℃ air quenching was 91%.

[0133] It can be seen that direct high-pressure forming without pressure holding process conditions makes it difficult to eliminate the pores inside the corundum barren material due to the high hardness and high strength of the corundum itself, which significantly reduces the yield of the corundum sagger. At the same time, due to the residual pores, the sintering process is difficult to densify, which obviously damages the strength and high-temperature performance of the corundum sagger.

[0134] Any matters not mentioned above shall be subject to the existing technology.

[0135] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a corundum sagger for high-purity alumina ceramics high-temperature sintering, characterized in that: The specific steps are as follows: Step S1, mixing sintered corundum particles and premixed fine powder in a certain mass ratio to obtain a premix; the premixed fine powder includes sintered corundum fine powder, fused zirconium corundum fine powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder and amorphous alumina fine powder; Step S2, adding a certain amount of potato starch and p-alumina colloidal solution to the premix in sequence, and mixing them uniformly to obtain a mixture; Step S3, sealing the mixed material to obtain a plastic material; Step S4, molding the plastic material and then demoulding it to obtain a green body; Step S5, hot pressing and sintering the green body to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics; Wherein, the ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in potassium fluorozirconate solution; In the premixed fine powder, the mass ratio of sintered corundum fine powder, fused zirconium corundum fine powder, rare earth composite yttrium zirconium ceramic powder, cerium phosphate powder and amorphous alumina fine powder is 100: (30-35): (6-8): (2.2-2.8): (15-25); The ρ-alumina colloidal solution is obtained by dissolving ρ-alumina fine powder in a potassium fluorozirconate solution with a concentration of 1.5-1.8 mol / L, wherein the mass ratio of the ρ-alumina fine powder to the potassium fluorozirconate solution is 1:(8-16); the ρ-alumina colloidal solution accounts for 3.3-3.6 wt% of the premix; The specific operation of step S4 is as follows: placing the plastic material in the mold, degassing under a pressure of 25-35 MPa, maintaining the pressure for 40-60 seconds, then increasing the pressure to 75-85 MPa, maintaining the pressure for 30-40 seconds, then increasing the pressure to 180-220 MPa, maintaining the pressure for 20-30 seconds, and demolding to obtain a green body; The specific operation of step S5 is: placing the green body in a hot pressing sintering furnace, firing at 1670-1680°C, in an air atmosphere and a pressure of 0.2-0.3 MPa, keeping the temperature for 2-4 hours, and then cooling to room temperature to obtain a corundum sagger for high-temperature sintering of high-purity alumina ceramics; The amorphous alumina fine powder is amorphous, has a particle size of 5-8 μm, and an Al2O3 content of ≥99.5wt%.

2. The method for preparing a corundum sagger for high-purity alumina ceramics high-temperature sintering according to claim 1, characterized in that: The mass ratio of the sintered corundum particles to the premixed fine powder is 100:(65-70).

3. The method for preparing a corundum sagger for high-purity alumina ceramics high-temperature sintering according to claim 1, characterized in that: The potato starch accounts for 1.2-1.6 wt% of the premix.

4. The method for preparing a corundum sagger for high-purity alumina ceramics for high-temperature sintering according to any one of claims 1 to 3, characterized in that: The particle size of the sintered corundum fine powder is 25-30 μm; and / or, The particle size of the fused zirconium corundum fine powder is 40-50 μm, and the ZrO2 content is 6-8wt%; and / or, The product grade of rare earth composite yttrium zirconium ceramic powder is YZ7.2QLA, see GB / T31968-2015; and / or, The particle size of the cerium phosphate powder is 15-25 μm, and the CePO4 content is ≥98wt%.

5. The method for preparing a corundum sagger for high-purity alumina ceramics for high-temperature sintering according to any one of claims 1 to 3, characterized in that: The particle size of the sintered corundum particles is 0.1~2.5mm, wherein the mass ratio of [0.1~0.5mm] particles, [1~1.5mm] particles and [2~2.5mm] particles is (15~20):(45~50):(25~30).

6. A corundum sagger for high-temperature sintering of high-purity alumina ceramics prepared by the preparation method according to any one of claims 1 to 5.

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