A spinel-based crucible for melting nickel-based superalloys and a method for manufacturing the same

Abstract

This invention relates to a spinel-based crucible for melting nickel-based superalloys and its preparation method. The technical solution is as follows: Fine spinel powder, alumina powder, magnesium lignosulfonate, and deionized water are mixed and spray-dried to obtain mixed fine powder A. Fine spinel powder, aluminum nitride powder, and boric acid are used as mixed powders, with anhydrous ethanol added, ball-milled, and dried to obtain mixed fine powder B. Spinel particles with a particle size of 5–3 mm, 3–1 mm, and ≤1 mm are added to a mixing mill, with anhydrous ethanol added, and mixed and milled. Then, hydrateable alumina, yttrium oxide powder, mixed fine powder A, and mixed fine powder B are added sequentially, mixed and milled, cold isostatically pressed, dried, and heat-treated at 1650–1750℃ under nitrogen conditions to obtain the spinel-based crucible for melting nickel-based superalloys. The products manufactured by this invention have good thermal shock stability, excellent high-temperature mechanical properties, and excellent resistance to erosion and penetration by nickel-based high-temperature alloy melts.

Description

Technical Field

[0001] This invention belongs to the technical field of spinel-based crucibles. Specifically, it relates to a spinel-based crucible for melting nickel-based high-temperature alloys and its preparation method. Background Technology

[0002] Nickel-based superalloys possess excellent comprehensive properties, including low density, high strength, corrosion resistance, and good high-temperature stability, making them widely used in aerospace, construction, and medical fields. Crucibles, as essential melting containers for superalloys, have performance that is a key factor affecting their quality. Magnesium-aluminum spinel, with its high melting point, excellent high-temperature mechanical properties, and stable chemical properties, is an important material for crucibles used in the melting of nickel-based superalloys.

[0003] Currently, the research and development of spinel-based crucibles for high-temperature alloy melting has attracted widespread attention from those skilled in the art.

[0004] The patented technology "An aluminum-magnesium-based ceramic crucible for high-temperature alloy melting and its preparation method (CN202311773401.6)" produces crucible materials with stable chemical properties that do not react with high-temperature alloys or release harmful substances during use. However, the excessive density of the crucible material results in insufficient thermal shock stability.

[0005] The patented technology "A method for preparing a periclase-magnesium aluminum spinel ceramic crucible for magnesium alloy melting (CN201410077381.3)" states that although the periclase-magnesium aluminum spinel ceramic crucible prepared by this technology has good high-temperature resistance and thermal shock stability, its ability to resist the erosion and penetration of alloy melt is still insufficient.

[0006] The patented technology "An isostatic pressing corundum spinel crucible and its preparation method (CN201210440801.0)" states that although the corundum spinel crucible prepared by this technology has high bulk density, low porosity and good thermal shock stability, its high-temperature mechanical properties are low. Summary of the Invention

[0007] The present invention aims to overcome the defects of the existing technology and provides a method for preparing a spinel-based crucible for melting nickel-based superalloys. The spinel-based crucible prepared by this method has good thermal shock stability, excellent high-temperature mechanical properties, and excellent resistance to erosion and penetration by nickel-based superalloy melts.

[0008] To achieve the above objectives, the specific steps of the technical solution adopted by the present invention are as follows:

[0009] Step 1: Mix 30-50 wt% spinel fine powder, 5-15 wt% alumina micro powder, 10-30 wt% magnesium lignosulfonate and 20-40 wt% deionized water to obtain a mixed slurry; place the mixed slurry in a spray dryer and spray dry to obtain mixed fine powder A.

[0010] The sum of Al2O3 and MgO content in the spinel fine powder is greater than 99.1 wt%; the particle size of the spinel fine powder is less than 0.020 mm.

[0011] The alumina micro powder has an Al2O3 content >99.5wt% and a particle size <5μm.

[0012] Step 2: Using 70-80 wt% spinel fine powder, 17-27 wt% aluminum nitride powder and 1-3 wt% boric acid as mixed powder, and adding 1-3 wt% anhydrous ethanol to the mixed powder, ball milling for 6-8 hours, and drying at 80-110℃ for 8-12 hours, mixed fine powder B is obtained.

[0013] The spinel powder mentioned in step two is the same as the spinel powder mentioned in step one.

[0014] Step 3: Prepare the following ingredients: 10-20 wt% spinel particles with a particle size of 5-3 mm, 25-35 wt% spinel particles with a particle size of 3-1 mm, 10-20 wt% spinel particles with a particle size ≤1 mm, 2-6 wt% hydrateable alumina, 0.5-1.5 wt% yttrium oxide powder, 15-20 wt% of the aforementioned mixed fine powder A, and 15-20 wt% of the aforementioned mixed fine powder B; first, mix the spinel particles with a particle size of 5-3 mm, the spinel particles with a particle size of 3-1 mm, and the spinel particles with a particle size ≤1 mm. The particles are added to a mixing mill, along with 3-5 wt% anhydrous ethanol, and mixed for 5-10 minutes. Then, the hydrateable alumina, yttrium oxide powder, mixed fine powder A, and mixed fine powder B are added sequentially and mixed for 8-15 minutes to obtain a mixture. The mixture is then cold isostatically pressed to obtain a spinel-based crucible blank. The spinel-based crucible blank is then dried at 80-110°C for 8-12 hours, and then heat-treated at 1650-1750°C under a nitrogen atmosphere for 2-4 hours to obtain a spinel-based crucible for melting nickel-based high-temperature alloys.

[0015] The cold isostatic pressing process involves placing the mixture in a mold, sealing it, and transferring it to the pressure chamber of an isostatic press. The pressure is increased sequentially at a rate of 0.1–3.0 MPa / s to 20–50 MPa, then at a rate of 0.2–5.0 MPa / s to 60–80 MPa, then at a rate of 0.2–10.0 MPa / s to 90–110 MPa, and finally at a rate of 0.5–1.0 MPa / s to 120–140 MPa. The pressure is then increased again at a rate of 0.5–8 MPa / s. The pressure is increased to 150–200 MPa and held for 1–5 minutes. Then, the pressure is decreased sequentially at a rate of 0.2–5 MPa / s to 120–140 MPa, 0.2–6 MPa / s to 90–110 MPa, 0.1–8 MPa / s to 60–80 MPa, 0.1–5 MPa / s to 30–50 MPa, and 0.1–5 MPa / s to 2 MPa. Finally, the pressure is unloaded to atmospheric pressure.

[0016] The C of magnesium lignosulfonate 81 H 92 O 28 The content is 50.0-60.0 wt%; the particle size of magnesium lignosulfonate is <0.088 mm.

[0017] The peristaltic pump in the spray dryer has a rotation speed of 40-60 r / min, the atomizer of the spray dryer has a pneumatic rotation speed of 20000-25000 r / min, and the temperature of the spray dryer is 180-220℃.

[0018] The aluminum nitride powder has an AlN content >99.5 wt% and a particle size <5 μm.

[0019] The H3BO3 content of the boric acid is >99.5 wt%.

[0020] The ball mill has a rotational speed of 60-80 r / min, a ball-to-material ratio of 3.0-4.0:1, and the grinding balls are agate balls.

[0021] The sum of the Al2O3+MgO contents of the spinel particles is greater than 99.1 wt%.

[0022] The chemical composition of the hydrateable alumina is as follows: Al2O3 content > 88.2 wt%, Na2O+K2O content < 0.42 wt%, IL < 10.17 wt%; the particle size of the hydrateable alumina is < 0.074 mm.

[0023] The yttrium oxide powder has a Y2O3 content > 99.0 wt% and a particle size < 5 μm.

[0024] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0025] (1) This invention uses spinel particles and fine powder, alumina, aluminum nitride, yttrium oxide powder, and magnesium lignosulfonate as main raw materials. Through an effective combination of processes such as premixing, cold isostatic pressing, and nitrogen atmosphere sintering, the spinel-based crucible for melting nickel-based high-temperature alloys (hereinafter referred to as the spinel-based crucible) has fine spinel and yttrium aluminum garnet grains (fine grains) generated in situ between the spinel particles. While optimizing the pore structure, size, and distribution in the spinel-based crucible material, it avoids the adverse effects of the volume effect caused by the in-situ generation of spinel and other phases on the thermal shock stability of the crucible, thus solving the problem of poor thermal shock stability of traditional spinel-based crucibles. Therefore, the spinel-based crucible prepared by this invention has good thermal shock stability.

[0026] (2) This invention generates uniformly distributed spinel and yttrium aluminum garnet fine grains in situ, which are then used as the bonding phase between particles in the spinel-based crucible. This improves the bonding strength between particles, and the small-sized, multi-grain-bound fine-grained structure also suppresses the propagation of microcracks inside the spinel-based crucible material caused by external stress under high-temperature conditions. Therefore, the spinel-based crucible prepared by this invention has excellent high-temperature mechanical properties.

[0027] (3) The aluminum nitride powder used in this invention has the characteristic of being difficult to wet by nickel-based superalloy melts. At the same time, the fine grains of spinel and yttrium aluminum garnet with good chemical stability strengthen the interparticle bonding and pore filling in the spinel-based crucible material, which can effectively reduce the penetration and reaction of nickel-based superalloy melts. Therefore, the spinel-based crucible prepared by this invention has excellent resistance to erosion and penetration by nickel-based superalloy melts.

[0028] The spinel-based crucible prepared in this invention was tested and found to have a bulk density of 3.24–3.38 g / cm³. 3 Apparent porosity ≤17.3%; room temperature flexural strength 36.5~40.3MPa; room temperature compressive strength 145.2~160.8MPa; high temperature flexural strength 21.0~33.7MPa (1400℃, carbonized); thermal shock resistance 12~19 cycles (1100℃, water-cooled); no obvious corrosion or penetration was observed in the molten nickel-based superalloy resistance test.

[0029] The testing standards for the performance indicators involved in this invention are as follows: bulk density is measured according to GB / T 2999-2016; room temperature flexural strength is measured according to GB / T 3001-2017; room temperature compressive strength is measured according to GB / T 5072-2008; high temperature flexural strength is measured according to GB / T 3002-2017; thermal shock stability is measured according to GB / T 30873-2014; and coefficient of thermal expansion is measured according to GB / T 7320-2018.

[0030] Therefore, the spinel-based crucible for melting nickel-based superalloys prepared by this invention has the characteristics of good thermal shock stability, excellent high-temperature mechanical properties, and excellent resistance to erosion and penetration by nickel-based superalloy melts. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but this is not intended to limit the scope of protection thereof.

[0032] A spinel-based crucible for melting nickel-based superalloys and its preparation method. The preparation method described in this specific embodiment is as follows:

[0033] Step 1: Mix 30-50 wt% spinel fine powder, 5-15 wt% alumina micro powder, 10-30 wt% magnesium lignosulfonate and 20-40 wt% deionized water to obtain a mixed slurry; place the mixed slurry in a spray dryer and spray dry to obtain mixed fine powder A.

[0034] Step 2: Using 70-80 wt% spinel fine powder, 17-27 wt% aluminum nitride powder and 1-3 wt% boric acid as mixed powder, and adding 1-3 wt% anhydrous ethanol to the mixed powder, ball milling for 6-8 hours, and drying at 80-110℃ for 8-12 hours, mixed fine powder B is obtained.

[0035] The spinel powder mentioned in step two is the same as the spinel powder mentioned in step one.

[0036] Step 3: Prepare the following ingredients: 10-20 wt% spinel particles with a particle size of 5-3 mm, 25-35 wt% spinel particles with a particle size of 3-1 mm, 10-20 wt% spinel particles with a particle size ≤1 mm, 2-6 wt% hydrateable alumina, 0.5-1.5 wt% yttrium oxide powder, 15-20 wt% of the aforementioned mixed fine powder A, and 15-20 wt% of the aforementioned mixed fine powder B; first, mix the spinel particles with a particle size of 5-3 mm, the spinel particles with a particle size of 3-1 mm, and the spinel particles with a particle size ≤1 mm. The particles are added to a mixing mill, along with 3-5 wt% anhydrous ethanol, and mixed for 5-10 minutes. Then, the hydrateable alumina, yttrium oxide powder, mixed fine powder A, and mixed fine powder B are added sequentially and mixed for 8-15 minutes to obtain a mixture. The mixture is then cold isostatically pressed to obtain a spinel-based crucible blank. The spinel-based crucible blank is then dried at 80-110°C for 8-12 hours, and then heat-treated at 1650-1750°C under a nitrogen atmosphere for 2-4 hours to obtain a spinel-based crucible for melting nickel-based high-temperature alloys.

[0037] The cold isostatic pressing process involves placing the mixture in a mold, sealing it, and transferring it to the pressure chamber of an isostatic press. The pressure is increased sequentially at a rate of 0.1–3.0 MPa / s to 20–50 MPa, then at a rate of 0.2–5.0 MPa / s to 60–80 MPa, then at a rate of 0.2–10.0 MPa / s to 90–110 MPa, and finally at a rate of 0.5–1.0 MPa / s to 120–140 MPa. The pressure is then increased again at a rate of 0.5–8 MPa / s. The pressure is increased to 150–200 MPa and held for 1–5 minutes. Then, the pressure is decreased sequentially at a rate of 0.2–5 MPa / s to 120–140 MPa, 0.2–6 MPa / s to 90–110 MPa, 0.1–8 MPa / s to 60–80 MPa, 0.1–5 MPa / s to 30–50 MPa, and 0.1–5 MPa / s to 2 MPa. Finally, the pressure is unloaded to atmospheric pressure.

[0038] The C of magnesium lignosulfonate 81 H 92 O 28 The content is 50.0–60.0 wt%.

[0039] The peristaltic pump in the spray dryer has a rotation speed of 40-60 r / min, the atomizer of the spray dryer has a pneumatic rotation speed of 20000-25000 r / min, and the temperature of the spray dryer is 180-220℃.

[0040] The ball mill has a rotational speed of 60-80 r / min, a ball-to-material ratio of 3.0-4.0:1, and the grinding balls are agate balls.

[0041] In this specific implementation:

[0042] The particle size of the magnesium lignosulfonate is <0.088 mm.

[0043] The sum of Al2O3 and MgO content in the spinel fine powder is greater than 99.1 wt%; the particle size of the spinel fine powder is less than 0.020 mm.

[0044] The alumina micro powder has an Al2O3 content >99.5wt% and a particle size <5μm.

[0045] The aluminum nitride powder has an AlN content >99.5 wt% and a particle size <5 μm.

[0046] The H3BO3 content of the boric acid is >99.5 wt%.

[0047] The sum of the Al2O3+MgO contents of the spinel particles is greater than 99.1 wt%.

[0048] The chemical composition of the hydrateable alumina is as follows: Al2O3 content > 88.2 wt%, Na2O+K2O content < 0.42 wt%, IL < 10.17 wt%; the particle size of the hydrateable alumina is < 0.074 mm.

[0049] The details will not be repeated in the examples.

[0050] Example 1

[0051] A spinel-based crucible for melting nickel-based superalloys and its preparation method. The preparation method described in this embodiment is as follows:

[0052] Step 1: Mix 30wt% spinel fine powder, 8wt% alumina micro powder, 30wt% magnesium lignosulfonate and 32wt% deionized water to obtain a mixed slurry; place the mixed slurry in a spray dryer and spray dry to obtain mixed fine powder A.

[0053] Step 2: Using 70 wt% spinel fine powder, 27 wt% aluminum nitride powder and 3 wt% boric acid as mixed powder, and adding 1 wt% anhydrous ethanol to the mixed powder, ball milling for 6 hours, and drying at 80°C for 8 hours, mixed fine powder B is obtained.

[0054] The spinel powder mentioned in step two is the same as the spinel powder mentioned in step one.

[0055] Step 3: Prepare the following ingredients: 20 wt% spinel particles with a particle size of 5-3 mm, 25 wt% spinel particles with a particle size of 3-1 mm, 10 wt% spinel particles with a particle size ≤1 mm, 4.2 wt% hydrateable alumina, 0.8 wt% yttrium oxide powder, 20 wt% of the aforementioned mixed fine powder A, and 20 wt% of the aforementioned mixed fine powder B; first, mix the spinel particles with a particle size of 5-3 mm, the spinel particles with a particle size of 3-1 mm, and the spinel particles with a particle size ≤1 mm. Stone particles are added to a mixing mill, along with 3 wt% anhydrous ethanol, and mixed for 5 minutes. Then, the hydrateable alumina, yttrium oxide powder, mixed fine powder A, and mixed fine powder B are added sequentially and mixed for 8 minutes to obtain a mixture. The mixture is then cold isostatically pressed to obtain a spinel-based crucible blank. The spinel-based crucible blank is then dried at 80°C for 8 hours, and then heat-treated at 1650°C under a nitrogen atmosphere for 2 hours to obtain a spinel-based crucible for melting nickel-based high-temperature alloys.

[0056] The cold isostatic pressing process involves placing the mixture in a mold, sealing it, and transferring it to the pressure chamber of an isostatic press. The pressure is increased sequentially at a rate of 0.1 MPa / s to 20 MPa, then at 0.2 MPa / s to 60 MPa, then at 0.2 MPa / s to 90 MPa, and finally at 0.5 MPa / s to 120 MPa. The pressure is then increased to 150 MPa at 0.5 MPa / s and held for 1 minute. The pressure is then decreased sequentially at a rate of 0.2 MPa / s to 120 MPa, then at 0.2 MPa / s to 90 MPa, then at 0.1 MPa / s to 60 MPa, then at 0.1 MPa / s to 30 MPa, and finally at 0.1 MPa / s to 2 MPa. Finally, the pressure is released to atmospheric pressure.

[0057] The C of magnesium lignosulfonate 81 H 92 O 28 The content is 50.0 wt%.

[0058] The peristaltic pump in the spray dryer has a rotation speed of 40 r / min, the atomizer of the spray dryer has a pneumatic rotation speed of 20000 r / min, and the temperature of the spray dryer is 180℃.

[0059] The ball mill has a rotation speed of 60 r / min, a ball-to-material ratio of 3.0:1, and uses agate balls.

[0060] The spinel-based crucible for melting nickel-based superalloys prepared in this embodiment was tested and found to have a bulk density of 3.38 g / cm³. 3The apparent porosity is 16.7%; the room temperature flexural strength is 40.3 MPa; the room temperature compressive strength is 160.8 MPa; the high temperature flexural strength is 33.7 MPa (1400℃, carbonized); the thermal shock resistance is 12 cycles (1100℃, water-cooled); no obvious corrosion or penetration was observed in the molten nickel-based superalloy resistance test.

[0061] Example 2

[0062] A spinel-based crucible for melting nickel-based superalloys and its preparation method. The preparation method described in this embodiment is as follows:

[0063] Step 1: Mix 35wt% spinel fine powder, 5wt% alumina micro powder, 20wt% magnesium lignosulfonate and 40wt% deionized water to obtain a mixed slurry; place the mixed slurry in a spray dryer and spray dry to obtain mixed fine powder A.

[0064] Step 2: Using 75wt% spinel fine powder, 23wt% aluminum nitride powder and 2wt% boric acid as mixed powder, and adding 3wt% anhydrous ethanol to the mixed powder, ball milling for 6.5h, and drying at 90℃ for 9h, mixed fine powder B is obtained.

[0065] The spinel powder mentioned in step two is the same as the spinel powder mentioned in step one.

[0066] Step 3: Prepare the following ingredients: 10 wt% spinel particles with a particle size of 5-3 mm, 35 wt% spinel particles with a particle size of 3-1 mm, 13 wt% spinel particles with a particle size ≤1 mm, 6 wt% hydrateable alumina, 1 wt% yttrium oxide powder, 17 wt% of the aforementioned mixed fine powder A, and 18 wt% of the aforementioned mixed fine powder B; first, mix the spinel particles with a particle size of 5-3 mm, the spinel particles with a particle size of 3-1 mm, and the spinel particles with a particle size ≤1 mm. Add the mixture to a mixing mill, add 4 wt% anhydrous ethanol, mix for 7 min, then add the hydrated alumina, yttrium oxide powder, mixed fine powder A and mixed fine powder B in sequence, mix for 11 min to obtain a mixture; cold isostatically press the mixture to obtain a spinel-based crucible blank, then dry the spinel-based crucible blank at 90℃ for 9 h, and then heat treat it at 1675℃ and nitrogen atmosphere for 3 h to obtain a spinel-based crucible for melting nickel-based high-temperature alloys.

[0067] The cold isostatic pressing process involves placing the mixture in a mold, sealing it, and transferring it to the pressure chamber of an isostatic press. The pressure is increased sequentially at a rate of 1 MPa / s to 30 MPa, then to 65 MPa, then to 100 MPa, and finally to 125 MPa at a rate of 0.6 MPa / s. The pressure is then increased to 160 MPa at a rate of 1 MPa / s and held for 2 minutes. The pressure is then decreased sequentially at a rate of 1 MPa / s to 125 MPa, then to 95 MPa, then to 65 MPa, then to 35 MPa, and finally to 2 MPa. Finally, the pressure is released to atmospheric pressure.

[0068] The C of magnesium lignosulfonate 81 H 92 O 28 The content is 53.0 wt%.

[0069] The peristaltic pump in the spray dryer has a rotation speed of 50 r / min, the atomizer of the spray dryer has a pneumatic rotation speed of 21000 r / min, and the temperature of the spray dryer is 200℃.

[0070] The ball mill has a rotational speed of 65 r / min, a ball-to-material ratio of 3.2:1, and uses agate balls.

[0071] The spinel-based crucible for melting nickel-based superalloys prepared in this embodiment was tested and found to have a bulk density of 3.32 g / cm³. 3 The apparent porosity is 16.9%; the room temperature flexural strength is 39.1 MPa; the room temperature compressive strength is 151.5 MPa; the high temperature flexural strength is 28.8 MPa (1400℃, carbonized); the thermal shock resistance is 15 cycles (1100℃, water-cooled); no obvious corrosion or penetration was observed in the molten nickel-based superalloy resistance test.

[0072] Example 3

[0073] A spinel-based crucible for melting nickel-based superalloys and its preparation method. The preparation method described in this embodiment is as follows:

[0074] Step 1: Mix 45wt% spinel fine powder, 10wt% alumina micro powder, 25wt% magnesium lignosulfonate and 20wt% deionized water to obtain a mixed slurry; place the mixed slurry in a spray dryer and spray dry to obtain mixed fine powder A.

[0075] Step 2: Using 80 wt% spinel fine powder, 19 wt% aluminum nitride powder and 1 wt% boric acid as mixed powder, and adding 2 wt% anhydrous ethanol to the mixed powder, ball milling for 7 hours, and drying at 100°C for 10 hours, mixed fine powder B is obtained.

[0076] The spinel powder mentioned in step two is the same as the spinel powder mentioned in step one.

[0077] Step 3: Prepare the following ingredients: 15 wt% spinel particles with a particle size of 5-3 mm, 27 wt% spinel particles with a particle size of 3-1 mm, 20 wt% spinel particles with a particle size ≤1 mm, 4.5 wt% hydrateable alumina, 0.5 wt% yttrium oxide powder, 16 wt% of the aforementioned mixed fine powder A, and 17 wt% of the aforementioned mixed fine powder B; first, mix the spinel particles with a particle size of 5-3 mm, the spinel particles with a particle size of 3-1 mm, and the spinel particles with a particle size ≤1 mm. The particles are added to a mixing mill, along with 4 wt% anhydrous ethanol, and mixed for 8 minutes. Then, the hydrated alumina, yttrium oxide powder, mixed fine powder A, and mixed fine powder B are added sequentially and mixed for 13 minutes to obtain a mixture. The mixture is then cold isostatically pressed to obtain a spinel-based crucible blank. The spinel-based crucible blank is then dried at 100°C for 10 hours, and then heat-treated at 1700°C under a nitrogen atmosphere for 3 hours to obtain a spinel-based crucible for melting nickel-based high-temperature alloys.

[0078] The cold isostatic pressing process involves placing the mixture in a mold, sealing it, and transferring it to the pressure chamber of an isostatic press. The pressure is increased sequentially at a rate of 2 MPa / s to 40 MPa, then at 3 MPa / s to 70 MPa, then at 5 MPa / s to 105 MPa, and finally at 0.8 MPa / s to 130 MPa. The pressure is then increased to 180 MPa at 5 MPa / s and held for 3 minutes. The pressure is then decreased sequentially at a rate of 3 MPa / s to 130 MPa, then at 4 MPa / s to 100 MPa, then at 5 MPa / s to 75 MPa, then at 3 MPa / s to 45 MPa, and finally at 3 MPa / s to 2 MPa. Finally, the pressure is released to atmospheric pressure.

[0079] The C of magnesium lignosulfonate 81 H 92 O 28 The content is 56.0 wt%.

[0080] The peristaltic pump in the spray dryer has a rotation speed of 55 r / min, the atomizer of the spray dryer has a pneumatic rotation speed of 23000 r / min, and the temperature of the spray dryer is 210℃.

[0081] The ball mill has a rotation speed of 70 r / min, a ball-to-material ratio of 3.6:1, and the grinding balls are agate balls.

[0082] The spinel-based crucible for melting nickel-based superalloys prepared in this embodiment was tested and found to have a bulk density of 3.28 g / cm³.3 The apparent porosity is 17.1%; the room temperature flexural strength is 38.4 MPa; the room temperature compressive strength is 148.6 MPa; the high temperature flexural strength is 25.1 MPa (1400℃, carbonized); the thermal shock resistance is 19 cycles (1100℃, water-cooled); no obvious corrosion or penetration was observed in the molten nickel-based superalloy resistance test.

[0083] Example 4

[0084] A spinel-based crucible for melting nickel-based superalloys and its preparation method. The preparation method described in this embodiment is as follows:

[0085] Step 1: Mix 50 wt% spinel fine powder, 15 wt% alumina micro powder, 10 wt% magnesium lignosulfonate and 25 wt% deionized water to obtain a mixed slurry; place the mixed slurry in a spray dryer and spray dry to obtain mixed fine powder A.

[0086] Step 2: Using 80wt% spinel fine powder, 17wt% aluminum nitride powder and 3wt% boric acid as mixed powder, and adding 1.5wt% anhydrous ethanol to the mixed powder, ball milling for 8 hours, and drying at 110℃ for 12 hours, mixed fine powder B is obtained.

[0087] The spinel powder mentioned in step two is the same as the spinel powder mentioned in step one.

[0088] Step 3: Prepare the following ingredients: 18 wt% spinel particles with a particle size of 5-3 mm, 32 wt% spinel particles with a particle size of 3-1 mm, 16.5 wt% spinel particles with a particle size ≤1 mm, 2 wt% hydrateable alumina, 1.5 wt% yttrium oxide powder, 15 wt% of the aforementioned mixed fine powder A, and 15 wt% of the aforementioned mixed fine powder B; first, mix the spinel particles with a particle size of 5-3 mm, the spinel particles with a particle size of 3-1 mm, and the spinel particles with a particle size ≤1 mm. The particles are added to a mixing mill, along with 5 wt% anhydrous ethanol, and mixed for 10 min. Then, the hydrateable alumina, yttrium oxide powder, mixed fine powder A, and mixed fine powder B are added sequentially and mixed for 15 min to obtain a mixture. The mixture is then cold isostatically pressed to obtain a spinel-based crucible blank. The spinel-based crucible blank is then dried at 110°C for 12 h, and then heat-treated at 1750°C under a nitrogen atmosphere for 4 h to obtain a spinel-based crucible for melting nickel-based high-temperature alloys.

[0089] The cold isostatic pressing process involves placing the mixture in a mold, sealing it, and transferring it to the pressure chamber of an isostatic press. The pressure is increased sequentially at a rate of 3.0 MPa / s to 50 MPa, then at 5.0 MPa / s to 80 MPa, then at 10.0 MPa / s to 110 MPa, and finally at 1.0 MPa / s to 140 MPa. The pressure is then increased to 200 MPa at 8 MPa / s and held for 5 minutes. The pressure is then decreased sequentially at a rate of 5 MPa / s to 140 MPa, then at 6 MPa / s to 110 MPa, then at 8 MPa / s to 80 MPa, then at 5 MPa / s to 50 MPa, and finally at 5 MPa / s to 2 MPa. Finally, the pressure is released to atmospheric pressure.

[0090] The C of magnesium lignosulfonate 81 H 92 O 28 The content is 60.0 wt%.

[0091] The peristaltic pump in the spray dryer has a rotation speed of 60 r / min, the atomizer of the spray dryer has a pneumatic rotation speed of 25000 r / min, and the temperature of the spray dryer is 220℃.

[0092] The ball mill has a rotation speed of 80 r / min, a ball-to-material ratio of 4.0:1, and the grinding balls are agate balls.

[0093] The spinel-based crucible for melting nickel-based superalloys prepared in this embodiment was tested and found to have a bulk density of 3.24 g / cm³. 3 The apparent porosity is 17.3%; the room temperature flexural strength is 36.5 MPa; the room temperature compressive strength is 145.2 MPa; the high temperature flexural strength is 21.0 MPa (1400℃, carbonized); the thermal shock resistance is 17 cycles (1100℃, water-cooled); no obvious corrosion or penetration was observed in the molten nickel-based superalloy resistance test.

[0094] This specific implementation method has the following advantages compared with the prior art:

[0095] (1) This specific embodiment uses spinel particles and fine powder, alumina, aluminum nitride, yttrium oxide powder, and magnesium lignosulfonate as main raw materials. Through an effective combination of processes such as premixing, cold isostatic pressing, and nitrogen atmosphere sintering, the prepared spinel-based crucible for melting nickel-based high-temperature alloys (hereinafter referred to as the spinel-based crucible) has fine spinel and yttrium aluminum garnet grains (fine grains) generated in situ between the spinel particles. While optimizing the pore structure, size, and distribution in the spinel-based crucible material, it avoids the adverse effects of the volume effect caused by the in-situ generation of spinel and other phases on the thermal shock stability of the crucible, thus solving the problem of poor thermal shock stability of traditional spinel-based crucibles. Therefore, the spinel-based crucible prepared in this specific embodiment has good thermal shock stability.

[0096] (2) In this specific embodiment, uniformly distributed spinel and yttrium aluminum garnet fine grains are generated in situ and used as the bonding phase between particles in the spinel-based crucible. This improves the bonding strength between particles, and the small-sized, multi-grain-bound fine-grained structure also suppresses the propagation of microcracks inside the spinel-based crucible material caused by external stress under high-temperature conditions. Therefore, the spinel-based crucible prepared in this specific embodiment has excellent high-temperature mechanical properties.

[0097] (3) The aluminum nitride powder used in this specific embodiment has the characteristic of being difficult to wet by nickel-based superalloy melts. At the same time, the fine grains of spinel and yttrium aluminum garnet with good chemical stability strengthen the interparticle bonding and pore filling in the spinel-based crucible material, which can effectively reduce the penetration and reaction of nickel-based superalloy melts. Therefore, the spinel-based crucible prepared in this specific embodiment has excellent resistance to erosion and penetration by nickel-based superalloy melts.

[0098] The spinel-based crucible prepared in this specific embodiment was tested and found to have a bulk density of 3.24–3.38 g / cm³. 3 Apparent porosity ≤17.3%; room temperature flexural strength 36.5~40.3MPa; room temperature compressive strength 145.2~160.8MPa; high temperature flexural strength 21.0~33.7MPa (1400℃, carbonized); thermal shock resistance 12~19 cycles (1100℃, water-cooled); no obvious corrosion or penetration was observed in the molten nickel-based superalloy resistance test.

[0099] The test standards for the performance indicators involved in this specific embodiment are as follows: bulk density is measured according to GB / T 2999-2016; room temperature flexural strength is measured according to GB / T 3001-2017; room temperature compressive strength is measured according to GB / T 5072-2008; high temperature flexural strength is measured according to GB / T 3002-2017; thermal shock stability is measured according to GB / T 30873-2014; and coefficient of thermal expansion is measured according to GB / T 7320-2018.

[0100] Therefore, the spinel-based crucible for melting nickel-based superalloys prepared in this specific embodiment has the characteristics of good thermal shock stability, excellent high-temperature mechanical properties, and excellent resistance to erosion and penetration by nickel-based superalloy melts.

Claims

1. A method for preparing a spinel-based crucible for melting nickel-based superalloys, characterized in that... The preparation steps are as follows: Step 1: Mix 30-50 wt% spinel fine powder, 5-15 wt% alumina micro powder, and 10-30 wt% lignin sulfonic acid. Magnesium is mixed with 20-40 wt% deionized water to obtain a mixed slurry; the mixed slurry is placed in a spray dryer and spray dried to obtain mixed fine powder A; The sum of Al2O3+MgO content in the spinel fine powder is >99.1wt%; the particle size of the spinel fine powder is <0.020mm. The alumina micro powder has an Al2O3 content >99.5wt% and a particle size <5μm. Step 2: Using 70-80 wt% spinel fine powder, 17-27 wt% aluminum nitride powder and 1-3 wt% boric acid as mixed powder, and adding 1-3 wt% anhydrous ethanol to the mixed powder, ball milling for 6-8 hours, and drying at 80-110℃ for 8-12 hours, mixed fine powder B is obtained. The spinel powder mentioned in step two is the same as the spinel powder mentioned in step one; Step 3: Prepare the following ingredients: 10-20 wt% spinel particles with a particle size of 5-3 mm, 25-35 wt% spinel particles with a particle size of 3-1 mm, 10-20 wt% spinel particles with a particle size ≤1 mm, 2-6 wt% hydrateable alumina, 0.5-1.5 wt% yttrium oxide powder, 15-20 wt% of the aforementioned mixed fine powder A, and 15-20 wt% of the aforementioned mixed fine powder B. First, add the spinel particles with a particle size of 5-3 mm, the spinel particles with a particle size of 3-1 mm, and the spinel particles with a particle size ≤1 mm to a mixer, add 3-5 wt% anhydrous ethanol, and mix for 5-10 minutes. Then, add the hydrateable alumina, the yttrium oxide powder, the mixed fine powder A, and the mixed fine powder B in sequence, and mix for 8-15 minutes to obtain a mixture. The mixture is cold isostatically pressed to obtain a spinel-based crucible blank, which is then dried at 80-110℃ for 8-12 hours and then heat-treated at 1650-1750℃ under a nitrogen atmosphere for 2-4 hours to obtain a spinel-based crucible for melting nickel-based high-temperature alloys. The sum of the Al2O3+MgO content of the spinel particles is >99.1 wt%; The cold isostatic pressing process involves placing the mixture in a mold, sealing it, and transferring it to the pressure chamber of an isostatic press; first, the pressure is increased sequentially to 20-50 MPa at a rate of 0.1-3.0 MPa / s, and then at a rate of 0.2-5.0 MPa / s. The pressure is increased to 60-80 MPa at a rate of 0.2-10.0 MPa / s, then increased to 90-110 MPa at a rate of 0.5-1.0 MPa / s, and finally increased to 120-140 MPa at a rate of 0.5-8 MPa / s. The pressure is then increased to 150-200 MPa at a rate of 0.5-8 MPa / s and held for 1-5 minutes. The pressure is then decreased sequentially to 120-140 MPa at a rate of 0.2-5 MPa / s, then to 90-110 MPa at a rate of 0.2-6 MPa / s, then to 60-80 MPa at a rate of 0.1-8 MPa / s, then to 30-50 MPa at a rate of 0.1-5 MPa / s, and finally to 2 MPa at a rate of 0.1-5 MPa / s. The pressure is then finally released to atmospheric pressure.

2. The method for preparing the spinel-based crucible for melting nickel-based high-temperature alloys according to claim 1, characterized in that... The C of magnesium lignosulfonate 81 H 92 O 28 The content is 50.0~60.0wt%; the particle size of magnesium lignosulfonate is <0.088mm.

3. The method for preparing the spinel-based crucible for melting nickel-based high-temperature alloys according to claim 1, characterized in that... The peristaltic pump in the spray dryer has a rotation speed of 40~60 r / min, the atomizer of the spray dryer has a pneumatic rotation speed of 20000~25000 r / min, and the temperature of the spray dryer is 180~220℃.

4. The method for preparing the spinel-based crucible for melting nickel-based superalloys according to claim 1, characterized in that... The aluminum nitride powder has an AlN content >99.5wt% and a particle size <5μm.

5. The method for preparing the spinel-based crucible for melting nickel-based high-temperature alloys according to claim 1, characterized in that... The boric acid (H3BO3) content is >99.5 wt%.

6. The method for preparing the spinel-based crucible for melting nickel-based superalloys according to claim 1, characterized in that... The ball mill has a rotational speed of 60-80 r / min, a ball-to-material ratio of 3.0-4.0:1, and the grinding balls are agate balls.

7. The method for preparing the spinel-based crucible for melting nickel-based high-temperature alloys according to claim 1, characterized in that... The chemical composition of the hydrateable alumina is as follows: Al2O3 content > 88.2 wt%, Na2O+K2O content < 0.42 wt%, IL < 10.17 wt%; the particle size of the hydrateable alumina is < 0.074 mm.

8. The method for preparing the spinel-based crucible for melting nickel-based high-temperature alloys according to claim 1, characterized in that... The yttrium oxide powder has a Y2O3 content >99.0 wt% and a particle size <5 μm.

9. A spinel-based crucible for melting nickel-based superalloys, characterized in that... The spinel-based crucible for melting nickel-based superalloys is prepared by the method described in any one of claims 1 to 8.