A multilayer composite forming crucible for vacuum induction melting of superalloys

Abstract

This invention provides a multi-layered composite molding crucible for vacuum induction melting of high-temperature alloys. The multi-layered composite molding crucible has a layered structure, with a melting layer, a buffer layer, a transition layer, and a protective layer sequentially arranged from the inside out. The outer side of the melting layer is the buffer layer, the outer side of the buffer layer is the transition layer, and the outer side of the transition layer is the protective layer. The melting layer's main function is selected based on the type of alloy being melted; materials such as zirconium oxide, yttrium oxide, and calcium oxide can be chosen. Adding a buffer layer in front of the transition layer prevents further penetration of molten steel after the melting layer has been penetrated. The transition layer mainly functions to bond with the melting layer, ensuring that the melting layer is not damaged during use; different materials are selected depending on the materials used in the melting layer. The protective layer provides protection.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical crucible technology, specifically relating to a multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys. Background Technology

[0002] A crucible is a cup-shaped vessel used to heat solids at high temperatures. Although crucibles have historically been made of clay, they can be made of any material capable of withstanding high temperatures sufficient to melt or otherwise alter their contents. To improve crucible performance, a wide variety of models and specifications are now available on the market. CN104451184B discloses a composite crucible, specifically relating to a composite crucible for improving the energy utilization rate of electron beam melting technology. A composite crucible includes a crucible body with a hollow structure, the interior of which is a cavity for the flow of cooling liquid; the upper surface of the crucible body has a groove structure for holding materials; the crucible body is composed of a double-layer material, wherein the outer layer is graphite and the inner layer is copper. This invention improves the service life of the graphite layer by at least 30%. CN113073381B discloses a crucible with a silicon carbide / silicon composite ceramic layer. The crucible comprises a crucible made of carbon / carbon composite material and a silicon carbide / silicon composite ceramic layer attached to the inner and outer surfaces of the carbon / carbon composite crucible, or the crucible comprises a crucible made of carbon / carbon composite material and a silicon carbide / silicon composite ceramic layer attached to the inner surface of the carbon / carbon composite crucible. The silicon carbide / silicon composite ceramic layer is composed of silicon carbide and silicon interlocked and mixed. This invention achieves a product with excellent performance and long service life through optimized matching of the preparation process and crucible structure. However, crucibles composed of single substances and modifiers in the prior art have limited performance and various drawbacks, resulting in poor overall performance in the vacuum induction melting process. Summary of the Invention

[0003] The purpose of this invention is to provide a corrosion-resistant multi-layer composite molding crucible that exhibits resistance to ultra-high temperatures, erosion, and wetting inertness, as well as excellent thermal shock resistance when melting high-temperature alloys.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys, wherein the multi-layer composite molding crucible has a layered structure, and from the inside out are arranged a melting layer, a buffer layer, a transition layer and a protective layer, wherein the outer side of the melting layer is the buffer layer, the outer side of the buffer layer is the transition layer, and the outer side of the transition layer is the protective layer.

[0006] In a preferred embodiment, the thickness of the smelting layer is 0.5–1.5 cm. The material of the smelting layer is zirconium oxide, yttrium oxide, or calcium oxide; these materials have excellent resistance to ultra-high temperatures, erosion resistance, and wetting inertness, and serve as the innermost smelting layer.

[0007] In a preferred embodiment, the thickness of the transition layer is 1–3 cm. The material of the transition layer is a mullite-based material; the present invention uses the excellent thermal shock resistance of mullite to solve the problem of poor thermal shock resistance of the melting layer, preventing the crucible from cracking. The transition layer selected in the present invention can work synergistically with the melting layer to ensure that the melting layer is not damaged during use.

[0008] In a preferred embodiment, the thickness of the protective layer is 1–3 cm. The material of the protective layer is alumina, which has relatively excellent high-temperature resistance and is suitable as the outermost final protective layer, ensuring the integrity of the crucible during transportation and storage.

[0009] In a preferred embodiment, the thickness of the smelting layer is 1 cm, the thickness of the transition layer is 2 cm, and the thickness of the protective layer is 2 cm.

[0010] This invention combines the advantages of three refractory materials into a single crucible. By selecting appropriate materials, the three materials synergistically enhance each other, improving the crucible's resistance to high temperatures and shock. Simultaneously, a buffer layer is added in front of the transition layer to prevent further penetration of molten steel after the melting layer has been penetrated. Experiments revealed that the crucible's performance is optimal when the melting layer is 1 cm thick, the transition layer is 2 cm thick, and the protective layer is 2 cm thick. The inventors believe that at these thicknesses, the connection and compatibility between the melting layer, transition layer, and protective layer are better during hot pressing. Furthermore, the materials in each layer can work synergistically more simultaneously, resulting in improved resistance to ultra-high temperatures, erosion, wetting inertness, and thermal shock. If the thickness is too low, the individual materials cannot perform their respective functions; if the thickness is too high, the synergistic effect between them weakens.

[0011] In a preferred embodiment, the smelted layer is made of zirconium oxide with a particle size of 5 μm, a density of 5.89 g / mL at 25°C, and a melting point of 2700°C. It was purchased from Merck (230693).

[0012] In a preferred embodiment, the mullite-based material is used at a temperature of 1500°C and has a dried bulk density of 1.80 g / cm³. 3 Refractory resistance ≥1790℃. Purchased from Zhengzhou Jianxu Insulation and Refractory Materials Co., Ltd., LM15-1.8.

[0013] In a preferred embodiment, the alumina is ultra-dry alumina with the following particle size distribution: 2mm > 0.063mm, coefficient of variation ≥ 72%; < 0.063mm, coefficient of variation ≤ 28%; > 2mm, coefficient of variation ≤ 2%; bulk density 950-1100g / L; specific surface area 120-190m². 2 / g, purchased from Merck, 769290.

[0014] The inventors also discovered that the parameters of each material layer directly affect the performance of the crucible. The melting layer of this invention uses zirconium oxide, purchased from Merck 230693, which results in higher overall crucible performance. This type of zirconium oxide can improve the crucible's resistance to ultra-high temperatures, erosion, and wettability, and has better connectivity and compatibility with the buffer layer, providing a foundation for the hot pressing of the subsequent two layers. Furthermore, the intermediate layer of this invention uses mullite-based material purchased from Zhengzhou Jianxu Insulation and Refractory Materials Co., Ltd., LM15-1.8, which has excellent thermal shock resistance, preventing the crucible from cracking. The inventors speculate that this mullite-based material contains a binary solid solution compound composed of Al2O3 and SiO2, which can form more of the most stable 3Al2O3·2SiO2 compounds in the binary phase diagram. Ultra-dry alumina is used to prevent moisture from damaging the stable compounds in the mullite-based material. At the same time, the particle size distribution of the alumina used in this invention can better combine with the mullite-based material to form stable compounds and improve the performance of the crucible.

[0015] The present invention also provides a method for preparing the multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys, specifically including: preparing a melting layer by means of a mold; when the melting layer has not completely solidified, applying a fibrous material to the outer surface to form a buffer layer; then preparing a transition layer; applying a fibrous material when the surface is dried to an appropriate humidity; and then preparing a protective layer.

[0016] Furthermore, the method for preparing the multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys includes the following steps:

[0017] (1) Zirconia, yttrium oxide or calcium oxide are hot-pressed to form a molten layer;

[0018] (2) After coating the fibrous material onto the molten layer, add mullite-based material and hot press to form a transition layer;

[0019] (3) Apply aluminum oxide to the surface of the transition layer and sinter to solidify it to form a protective layer.

[0020] Compared with existing technologies, the advantages and beneficial effects of this invention are as follows: This invention provides a multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys, combining the advantages of three refractory materials into one crucible. The melting layer of the crucible in this invention is mainly selected according to the type of alloy being melted; zirconium oxide, yttrium oxide, calcium oxide, etc., can be selected. The transition layer mainly functions to bond with the melting layer, ensuring that the melting layer is not damaged during use; different materials are selected depending on the relevant materials of the melting layer. In this invention, when melting high-temperature alloys, zirconium oxide / yttrium oxide, with its excellent resistance to ultra-high temperatures, erosion, and wetting inertness, serves as the innermost melting layer; mullite, with its excellent thermal shock resistance, solves the problem of poor thermal shock resistance in the melting layer, preventing the crucible from cracking; alumina, with its relatively excellent high-temperature resistance, is suitable as the outermost final protective layer. The corrosion-resistant multi-layer composite molding crucible of this invention, when melting high-temperature alloys, possesses resistance to ultra-high temperatures, erosion, and wetting inertness, and excellent thermal shock resistance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a multi-layer composite molding crucible used for vacuum induction melting of high-temperature alloys;

[0022] Figure 2 This is a cross-sectional schematic diagram of a multi-layer composite molding crucible used for vacuum induction melting of high-temperature alloys.

[0023] Figure 3 This is a schematic cross-sectional view of a multi-layer composite molding crucible used for vacuum induction melting of high-temperature alloys.

[0024] In the diagram, 1 is the melting layer, 2 is the buffer layer, 3 is the transition layer, and 4 is the protective layer. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment provides a multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys. The multi-layer composite molding crucible includes a melting layer 1, a buffer layer 2, a transition layer 3, and a protective layer 4. The outer side of the melting layer 1 is the buffer layer 2, the outer side of the buffer layer 2 is the transition layer 3, and the outer side of the transition layer 3 is the protective layer 4. The material of the melting layer 1 is zirconium oxide; the material of the transition layer 3 is mullite-based material; and the material of the protective layer 4 is alumina.

[0028] The thickness of the smelting layer 1 is 1 cm. The thickness of the transition layer 3 is 2 cm. The thickness of the protective layer 4 is 2 cm.

[0029] The material of the smelted layer 1 is zirconium oxide, with a particle size of 5 μm, a density of 5.89 g / mL at 25°C, a boiling point of 5000°C, and a melting point of 2700°C. It was purchased from Merck 230693.

[0030] The mullite-based material has a service temperature of 1500℃ and a dry bulk density of 1.80 g / cm³. 3 Refractory resistance ≥1790℃. Purchased from Zhengzhou Jianxu Insulation and Refractory Materials Co., Ltd., LM15-1.8.

[0031] The alumina is an ultra-dry alumina with the following particle size distribution: 2mm > 0.063mm, coefficient of variation ≥ 72%; < 0.063mm, coefficient of variation ≤ 28%; > 2mm, coefficient of variation ≤ 2%; bulk density 950-1100g / L; specific surface area 120-190m². 2 / g, purchased from Merck, 769290.

[0032] The method for preparing the multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys includes the following steps:

[0033] (1) Zirconia is hot-pressed to form a molten layer 1;

[0034] (2) After coating the fibrous material on the melting layer, a buffer layer 2 is formed. Then, mullite-based material is added and hot-pressed to form a transition layer 3.

[0035] (3) Apply aluminum oxide to the surface of transition layer 3 and sinter to solidify it to form protective layer 4.

[0036] Example 2

[0037] This embodiment provides a multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys. The multi-layer composite molding crucible includes a melting layer 1, a buffer layer 2, a transition layer 3, and a protective layer 4. The outer side of the melting layer 1 is the buffer layer 2, the outer side of the buffer layer 2 is the transition layer 3, and the outer side of the transition layer 3 is the protective layer 4. The material of the melting layer 1 is zirconium oxide; the material of the transition layer 3 is mullite-based material; and the material of the protective layer 4 is alumina.

[0038] The thickness of the smelting layer 1 is 1 cm. The thickness of the transition layer 3 is 2 cm. The thickness of the protective layer 4 is 2 cm.

[0039] The material of the smelting layer 1 is yttrium oxide, purchased from Merck 234927.

[0040] The mullite-based material has a service temperature of 1500℃ and a dry bulk density of 1.80 g / cm³. 3 Refractory resistance ≥1790℃. Purchased from Zhengzhou Jianxu Insulation and Refractory Materials Co., Ltd., LM15-1.8.

[0041] The alumina is an ultra-dry alumina with the following particle size distribution: 2mm > 0.063mm, coefficient of variation ≥ 72%; < 0.063mm, coefficient of variation ≤ 28%; > 2mm, coefficient of variation ≤ 2%; bulk density 950-1100g / L; specific surface area 120-190m². 2 / g, purchased from Merck, 769290.

[0042] The method for preparing the multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys includes the following steps:

[0043] (1) Yttrium oxide is hot-pressed to form a molten layer 1;

[0044] (2) After coating the fibrous material on the melting layer 1, a buffer layer 2 is formed. Mullite-based material is added and hot-pressed to form a transition layer 3.

[0045] (3) Apply aluminum oxide to the surface of transition layer 3 and sinter to solidify it to form protective layer 4.

[0046] Example 3

[0047] This embodiment provides a multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys. The multi-layer composite molding crucible includes a melting layer 1, a buffer layer 2, a transition layer 3, and a protective layer 4. The outer side of the melting layer 1 is the buffer layer 2, the outer side of the buffer layer 2 is the transition layer 3, and the outer side of the transition layer 3 is the protective layer 4. The material of the melting layer 1 is zirconium oxide; the material of the transition layer 3 is mullite-based material; and the material of the protective layer 4 is alumina.

[0048] The thickness of the smelting layer 1 is 0.5 cm. The thickness of the transition layer 3 is 1 cm.

[0049] The protective layer 4 has a thickness of 1 cm.

[0050] The material of the smelted layer 1 is zirconium oxide, with a particle size of 5 μm, a density of 5.89 g / mL at 25°C, a boiling point of 5000°C, and a melting point of 2700°C. It was purchased from Merck 230693.

[0051] The mullite-based material has a service temperature of 1500℃ and a dry bulk density of 1.80 g / cm³. 3 Refractory resistance ≥1790℃. Purchased from Zhengzhou Jianxu Insulation and Refractory Materials Co., Ltd., LM15-1.8.

[0052] The alumina is an ultra-dry alumina with the following particle size distribution: 2mm > 0.063mm, coefficient of variation ≥ 72%; < 0.063mm, coefficient of variation ≤ 28%; > 2mm, coefficient of variation ≤ 2%; bulk density 950-1100g / L; specific surface area 120-190m². 2 / g, purchased from Merck, 769290.

[0053] The method for preparing the multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys includes the following steps:

[0054] (1) Zirconia is hot-pressed to form a molten layer 1;

[0055] (2) After coating the fibrous material on the melting layer 1, a buffer layer 2 is formed. Mullite-based material is added and hot-pressed to form a transition layer 3.

[0056] (3) Apply aluminum oxide to the surface of transition layer 3 and sinter to solidify it to form protective layer 4.

[0057] Performance testing

[0058] The performance parameters of the crucibles in Examples 1-3 and the conventional one-piece crucible were measured, and the results are shown in Table 1.

[0059] Table 1 Measurement Results

[0060]

[0061] Through the examples, it was found that the performance of the crucible prepared by the present invention is superior to that of the traditional one-piece crucible.

[0062] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys, characterized in that, The multi-layer composite molding crucible has a layered structure, with a melting layer, a buffer layer, a transition layer and a protective layer arranged sequentially from the inside to the outside. The outer side of the melting layer is the buffer layer, the outer side of the buffer layer is the transition layer, and the outer side of the transition layer is the protective layer. The transition layer is made of mullite-based material; the protective layer is made of alumina. The thickness of the smelting layer is 1 cm, the thickness of the transition layer is 2 cm, and the thickness of the protective layer is 2 cm; The material of the smelting layer is zirconium oxide with a particle size of 5 μm, a density of 5.89 g / mL at 25°C, and a melting point of 2700°C. The mullite-based material has a service temperature of 1500℃ and a dry bulk density of 1.80 g / cm³. 3 Refractory resistance ≥1790℃; The alumina is ultra-dry alumina with the following particle size distribution: 2mm > 0.063mm, coefficient of variation ≥ 72%; < 0.063mm, coefficient of variation ≤ 28%; > 2mm, coefficient of variation ≤ 2%; bulk density 950-1100g / L; specific surface area 120-190m². 2 / g.

2. The method for preparing the multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys as described in claim 1, characterized in that, include: A molten layer is prepared using a mold. Before the molten layer is completely solidified, a fibrous material is applied to the outer surface to form a buffer layer. Then, a transition layer is prepared. When the transition layer is dried to the appropriate humidity, a fibrous material is applied, and then a protective layer is prepared.

3. The method for preparing a multi-layer composite molding crucible for vacuum induction melting of high-temperature alloys according to claim 2, characterized in that, Includes the following steps: (1) Hot pressing zirconium oxide, yttrium oxide or calcium oxide into a molten layer; (2) After coating the fibrous material onto the smelting layer, add mullite-based material, hot press to form a transition layer; (3) Apply aluminum oxide to the surface of the transition layer and sinter to solidify it to form a protective layer.

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