Preparation method of high-entropy stability crucible for melting titanium and titanium alloy

Abstract

The application belongs to the field of refractory materials, and relates to a preparation method of a high-entropy stability crucible for titanium and titanium alloy smelting. The high-entropy stability crucible is prepared by using a barium zirconate-calcium zirconate-yttrium oxide composite doped material as a main raw material, mixing and stirring granules and fine powder of the composite doped material, yttrium oxide powder and an organic binder in a high-speed mixer, putting the mixture into a closed trough after screening, and then putting the mixture into a mold for hydraulic forming into the crucible; or directly drying and screening the mixture after uniform mixing and stirring, and then putting the mixture into a mold for isostatic pressing to form the crucible; and finally drying and firing the mixture to obtain the crucible product. The high-entropy stability effect of the barium zirconate-calcium zirconate-yttrium oxide composite doped materials is fully utilized, the interface reaction of the material is effectively inhibited, the yttrium oxide powder is added to play the roles of sintering aid, purification, strengthening of the material grain boundary and regulation of the material grain boundary structure and performance, and the problems of slag dropping, inclusion pollution and poor corrosion resistance of the crucible in the titanium and titanium alloy smelting process are improved.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials and mainly relates to a method for preparing a high-entropy stability crucible for melting titanium and titanium alloys. Background Technology

[0002] Titanium and titanium alloys are a class of alloys composed of titanium (Ti) as the matrix and other elements. They possess characteristics such as low density, high specific strength, excellent corrosion resistance, and good heat resistance, playing an irreplaceable role in aerospace, marine engineering, chemical, and medical fields. Traditional titanium and titanium alloy smelting methods (such as vacuum arc melting) are no longer able to meet the rapidly developing needs of large-scale applications due to high energy consumption and long processes. Crucible vacuum induction melting technology has high superheat and strong electromagnetic stirring, and can obtain ingots with uniform composition without multiple remeltings. It is considered an effective way to solve the problems of high energy consumption and low material yield. However, liquid titanium can react with almost all known refractory materials, easily leading to alloy contamination. The core of using the crucible method to melt titanium and titanium alloys is to solve the "extremely reactive" characteristic of titanium in the high-temperature liquid state, which traditional refractory crucibles cannot handle.

[0003] Barium zirconate (chemical formula BaZrO3) has a melting point exceeding 2600℃. Its unique cubic perovskite crystal structure remains stable at high temperatures, exhibits a low coefficient of thermal expansion, and possesses excellent mechanical strength, chemical stability, and ionic conductivity. It exhibits excellent chemical inertness to highly reactive metal melts (such as titanium alloys and TiAl alloys) and oxide melts, making it an ideal choice for manufacturing crucibles for melting these materials.

[0004] Calcium zirconate (chemical formula CaZrO3) has a perovskite structure, an extremely high melting point (2250-2550℃), a low coefficient of thermal expansion, and excellent chemical stability. It is the best-performing compound in the CaO-ZrO2 binary system. It exhibits excellent corrosion resistance to titanium alloy melts (such as Ti-6Al-4V and TiNi), making it an ideal crucible material for vacuum induction melting and allowing for control of impurities such as oxygen and zirconium in the product.

[0005] Yttrium oxide (Y2O3) belongs to the body-centered cubic crystal system and has a melting point as high as 2410℃. It has excellent thermal stability and can maintain structural stability for a long time under extreme high temperatures as a typical high-temperature refractory material. It also has extremely strong chemical stability, especially non-wetting of titanium and titanium alloy melts, and excellent corrosion resistance. It is one of the best crucible materials when melting highly reactive metals (such as titanium alloys).

[0006] High entropy materials (HEMs) represent a disruptive paradigm shift in materials science. They break away from the traditional design framework of materials based on one or two main elements, instead creating entirely new materials with superior properties by mixing five or more main elements and utilizing their unique "high entropy effect." "Entropy" can be understood as the degree of disorder in a system. "High entropy" means that the arrangement of atoms in the crystal lattice is extremely disordered and random. The extremely high mixing entropy inside the material can effectively reduce the Gibbs free energy of the system, thereby stabilizing the original multi-element single-phase solid solution structure that is difficult to coexist. High entropy materials have four major effects: (1) Thermodynamic high entropy effect: High mixing entropy is conducive to the formation of simple solid solutions. (2) Kinetic hysteresis diffusion effect: Slow atomic diffusion is conducive to obtaining nanostructures and endowing the material with excellent high-temperature stability. (3) Lattice distortion effect: Differences in atomic size lead to severe lattice distortion, which is an important source of its high strength and high hardness. (4) Performance "cocktail" effect: By adjusting the types and proportions of elements, the performance can be customized as needed, like mixing a cocktail. High-entropy materials utilize the high-entropy effect to stabilize multi-principal-element solid solutions, achieving a combination of superior performances that are difficult for traditional materials to match through four core effects. Calcium-barium-zirconium oxide composite-doped high-entropy materials typically refer to high-entropy materials formed by introducing multiple elements onto the basis of calcium zirconate (CaZrO3) or barium zirconate (BaZrO3).

[0007] To meet the rapidly growing demand for large-scale applications of titanium and titanium alloys, and to effectively improve the service life of crucible-type vacuum induction melting technology while saving energy and reducing costs, providing a composite doped material and crucible product with good high-temperature stability, strong corrosion resistance, and safety and reliability is one of the key approaches. The excellent properties of barium zirconate, calcium zirconate, and yttrium oxide make the preparation of such composite doped materials possible. Through the high-entropy stability design of the barium zirconate-calcium zirconate-yttrium oxide-zirconia system, a very promising direction is provided for the development of a new generation of high-entropy stability crucibles for titanium and titanium alloy melting. Summary of the Invention

[0008] The purpose of this invention is to propose a method for preparing a high-entropy stability crucible for melting titanium and titanium alloys. By introducing a composite doping material formed by multiple elements, the aim is to obtain crucible products with better comprehensive performance than those with single components, thereby effectively improving the service life of crucibles for melting titanium and titanium alloys.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a high-entropy stability crucible for smelting titanium and titanium alloys is disclosed. The high-entropy stability crucible uses composite doped materials as the main raw material. The particles and fine powder of the composite doped materials, yttrium oxide micro powder, and organic binder are mixed and stirred evenly in a high-speed mixer, sieved, and then placed in a sealed material tank for 12-24 hours. The crucible is then hydraulically formed into a mold. Alternatively, the evenly mixed raw materials can be directly dried, sieved, and then isostatically pressed into a mold to form a crucible. After drying at 100-180℃ and firing at 1650-1750℃, the crucible product is obtained.

[0010] The composite doped material refers to a barium zirconate-calcium zirconate-yttrium oxide material, which is prepared by high-temperature sintering. Its molar percentage composition is: barium zirconate 20-40%, calcium zirconate 10-20%, and yttrium oxide 40-70%.

[0011] The composite doped material particles refer to particles with particle sizes ranging from greater than 0.15 mm to less than or equal to 0.45 mm, greater than 0.074 mm to less than or equal to 0.15 mm, and greater than 0.05 mm to less than or equal to 0.074 mm, which respectively constitute 15% to 20%, 40% to 50%, and 10% to 15% of the total mass of the solid raw materials in the crucible product.

[0012] The particle size range of the composite doped material fine powder is less than or equal to 43µm, and the addition amount is 20% to 25% of the total solid raw material of the crucible product.

[0013] The yttrium oxide micro powder has a purity of Y2O3 ≥ 99.5%, a particle size range of median diameter D50 ≤ 5µm, and is added at a rate of 0.5% ~ 1.5% of the total mass of the solid raw materials in the crucible product (added externally).

[0014] The binder is one or a mixture of two of the following: phenolic resin, aqueous resin, and dextrin.

[0015] The amount of binder added is 4.0% to 7.0% (added externally) of the total mass of the solid raw materials of the crucible product.

[0016] This invention proposes a method for preparing a high-entropy stable crucible for titanium and titanium alloy smelting. By utilizing the slow diffusion of the "high-entropy effect" of the barium zirconate-calcium zirconate-yttrium oxide composite doping material, interfacial reactions can be effectively suppressed. At the same time, the addition of yttrium oxide micro powder plays a role in assisting sintering, purifying and strengthening grain boundaries, and regulating grain boundary structure and properties. This results in a crucible product with superior comprehensive performance compared to single-component crucibles, which can greatly improve problems such as crucible slag shedding, inclusion contamination, and poor corrosion resistance during the titanium and titanium alloy smelting process.

[0017] The table below compares the performance (core properties and main challenges) of different types of crucibles in the melting of titanium and titanium alloys: Detailed Implementation

[0018] The present invention is described in detail with reference to specific embodiments: Example 1:

[0019] The crucible raw material composition is as follows: Barium zirconate-calcium zirconate-yttrium oxide composite doped material is used as the main raw material, with the following molar percentages: barium zirconate 20%, calcium zirconate 10%, yttrium oxide 70%; particles with a size greater than 0.15 mm and less than or equal to 0.45 mm, particles with a size greater than 0.074 mm and less than or equal to 0.15 mm, and particles with a size greater than 0.05 mm and less than or equal to 0.074 mm. The composite doped material particles with a particle size of mm account for 15%, 45%, and 15% of the total solid raw material by mass, respectively; the fine powder of the composite doped material with a particle size of less than or equal to 43µm accounts for 25% of the total solid raw material by mass; the yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 0.5% of the total solid raw material by mass (added externally); an aqueous resin solution is used as a binder, and the binder accounts for 7.0% of the total solid raw material by mass (added externally); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 12 hours, then placed in a mold and hydraulically formed into a crucible; after drying at 120℃, they are fired at 1650℃ to obtain a high-entropy stable crucible for titanium and titanium alloy smelting. Example 2:

[0020] The crucible raw material composition is as follows: Barium zirconate-calcium zirconate-yttrium oxide composite doped material is used as the main raw material, with the following molar percentages: barium zirconate 20%, calcium zirconate 10%, and yttrium oxide 70%. The mass percentages of the composite doped material particles with a particle size greater than 0.15 mm and less than or equal to 0.45 mm, a particle size greater than 0.074 mm and less than or equal to 0.15 mm, and a particle size greater than 0.05 mm and less than or equal to 0.074 mm are 20%, 50%, and 10% of the total solid raw material, respectively. The composite doped material fine powder with a particle size of less than or equal to 43µm accounts for 20% of the total solid raw material by mass; yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 1.5% of the total solid raw material by mass (added); phenolic resin solution is used as a binder, and the binder accounts for 4.0% of the total solid raw material by mass (added); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 24 hours. After drying and sieving, they are placed in a mold and isostatically pressed into a crucible; after drying at 180℃, they are fired at 1750℃ to obtain a high entropy stability crucible for titanium and titanium alloy smelting. Example 3:

[0021] The crucible raw material composition is as follows: Barium zirconate-calcium zirconate-yttrium oxide composite doped material is used as the main raw material, with the following molar percentages: barium zirconate 20%, calcium zirconate 10%, yttrium oxide 70%; particles with a size greater than 0.15 mm and less than or equal to 0.45 mm, particles with a size greater than 0.074 mm and less than or equal to 0.15 mm, and particles with a size greater than 0.05 mm and less than or equal to 0.074 mm. The composite doped material particles with a particle size of mm account for 18%, 50%, and 10% of the total solid raw material by mass, respectively; the fine powder of the composite doped material with a particle size of less than or equal to 43µm accounts for 22% of the total solid raw material by mass; the yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 1.0% of the total solid raw material by mass (added externally); the binder, consisting of an aqueous resin solution and dextrin, accounts for 6.5% of the total solid raw material by mass (added externally); after mixing and sieving the above raw materials, they are placed in a sealed trough and left to stand for 24 hours, then placed in a mold and hydraulically formed into a crucible; after drying at 120℃, they are fired at 1700℃ to obtain a high-entropy stable crucible for smelting titanium and titanium alloys. Example 4:

[0022] The crucible raw material composition is as follows: Barium zirconate-calcium zirconate-yttrium oxide composite doped material is used as the main raw material, with the following molar percentages: barium zirconate 20%, calcium zirconate 10%, and yttrium oxide 70%. The mass percentages of the total solid raw material are as follows: particles larger than 0.15 mm and smaller than or equal to 0.45 mm, particles larger than 0.074 mm and smaller than or equal to 0.15 mm, and composite doped material particles larger than 0.05 mm and smaller than or equal to 0.074 mm, respectively. The mass percentage of the total solid raw material is 25% for fine composite doped material powder with a particle size of ≤43 µm. The mass percentage of the total solid raw material is 0.5% for yttrium oxide micropowder with a purity of Y₂O₃ ≥99.5% and a median diameter D₅₀ ≤5 µm. (Additional); using phenolic resin solution as a binder, the binder accounts for 5% of the total solid raw materials by mass (additional); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 12 hours, dried and sieved, and then placed in a mold for isostatic pressing to form a crucible; after drying at 170℃, it is fired at 1680℃ to obtain a high entropy stability crucible for titanium and titanium alloy smelting. Example 5:

[0023] The crucible raw material composition is as follows: Barium zirconate-calcium zirconate-yttrium oxide composite doped material is used as the main raw material, with the following molar percentages: barium zirconate 20%, calcium zirconate 10%, yttrium oxide 70%; particles with a size greater than 0.15 mm and less than or equal to 0.45 mm, particles with a size greater than 0.074 mm and less than or equal to 0.15 mm, and particles with a size greater than 0.05 mm and less than or equal to 0.074 mm. The composite doped material particles with a particle size of mm account for 15%, 49%, and 13% of the total solid raw material by mass, respectively; the fine powder of the composite doped material with a particle size of less than or equal to 43µm accounts for 23% of the total solid raw material by mass; the yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 1.3% of the total solid raw material by mass (added externally); an aqueous resin solution is used as a binder, and the binder accounts for 7.0% of the total solid raw material by mass (added externally); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 24 hours, then placed in a mold and hydraulically formed into a crucible; after drying at 100℃, they are fired at a high temperature of 1720℃ to obtain a high entropy stability crucible for titanium and titanium alloy smelting. Example 6:

[0024] The crucible raw material composition is as follows: The main raw material is a barium zirconate-calcium zirconate-yttrium oxide composite doped material, with the following molar percentages: barium zirconate 20%, calcium zirconate 10%, yttrium oxide 70%; particles with a size greater than 0.15 mm and less than or equal to 0.45 mm, particles with a size greater than 0.074 mm and less than or equal to 0.15 mm, and particles with a size greater than 0.05 mm and less than or equal to 0.074 mm. The composite doped material particles with a particle size of mm account for 20%, 45%, and 10% of the total solid raw material by mass, respectively; the fine powder of the composite doped material with a particle size of less than or equal to 43µm accounts for 25% of the total solid raw material by mass; the yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 0.8% of the total solid raw material by mass (added); an aqueous resin solution is used as a binder, and the binder accounts for 4.5% of the total solid raw material by mass (added); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 24 hours, dried and sieved, and then placed in a mold for isostatic pressing to form a crucible; after drying at 170℃, it is fired at a high temperature of 1700℃ to obtain a high entropy stability crucible for titanium and titanium alloy smelting. Example 7:

[0025] The crucible raw material composition is as follows: The main raw material is a barium zirconate-calcium zirconate-yttrium oxide composite doped material, with the following molar percentages: barium zirconate 40%, calcium zirconate 10%, yttrium oxide 50%; particles with a size greater than 0.15 mm and less than or equal to 0.45 mm, particles with a size greater than 0.074 mm and less than or equal to 0.15 mm, and particles with a size greater than 0.05 mm and less than or equal to 0.074 mm. The composite doped material particles with a particle size of mm account for 15%, 50%, and 10% of the total solid raw material by mass, respectively; the fine powder of the composite doped material with a particle size of less than or equal to 43µm accounts for 25% of the total solid raw material by mass; the yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 0.5% of the total solid raw material by mass (added externally); an aqueous resin solution is used as a binder, and the binder accounts for 6.8% of the total solid raw material by mass (added externally); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 24 hours, then placed in a mold and hydraulically formed into a crucible; after drying at 120℃, they are fired at 1680℃ to obtain a high-entropy stability crucible for titanium and titanium alloy smelting. Example 8:

[0026] The crucible raw material composition is as follows: The main raw material is a barium zirconate-calcium zirconate-yttrium oxide composite doped material, with the following molar percentages: barium zirconate 40%, calcium zirconate 10%, yttrium oxide 50%; particles with a size greater than 0.15 mm and less than or equal to 0.45 mm, particles with a size greater than 0.074 mm and less than or equal to 0.15 mm, and particles with a size greater than 0.05 mm and less than or equal to 0.074 mm. The composite doped material particles with a particle size of mm account for 20%, 45%, and 10% of the total solid raw material by mass, respectively; the fine powder of the composite doped material with a particle size of less than or equal to 43µm accounts for 25% of the total solid raw material by mass; the yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 0.6% of the total solid raw material by mass (added); an aqueous resin solution is used as a binder, and the binder accounts for 4.2% of the total solid raw material by mass (added); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 24 hours, dried and sieved, and then placed in a mold for isostatic pressing to form a crucible; after drying at 170℃, it is fired at a high temperature of 1720℃ to obtain a high entropy stability crucible for titanium and titanium alloy smelting. Example 9:

[0027] The crucible raw material composition is as follows: The main raw material is a barium zirconate-calcium zirconate-yttrium oxide composite doped material, with the following molar percentages: barium zirconate 30%, calcium zirconate 10%, yttrium oxide 60%; particles with a size greater than 0.15 mm and less than or equal to 0.45 mm, particles with a size greater than 0.074 mm and less than or equal to 0.15 mm, and particles with a size greater than 0.05 mm and less than or equal to 0.074 mm. The composite doped material particles with a particle size of mm account for 15%, 52%, and 10% of the total solid raw material by mass, respectively; the fine powder of the composite doped material with a particle size of less than or equal to 43µm accounts for 23% of the total solid raw material by mass; the yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 1.0% of the total solid raw material by mass (added externally); an aqueous resin solution is used as a binder, and the binder accounts for 7.0% of the total solid raw material by mass (added externally); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 24 hours, then placed in a mold and hydraulically formed into a crucible; after drying at 1200℃ and firing at 1730℃, a high entropy stability crucible for titanium and titanium alloy smelting is obtained.

[0028] Example 10: The crucible raw material composition is as follows: The main raw material is a barium zirconate-calcium zirconate-yttrium oxide composite doped material, with the following molar percentages: barium zirconate 30%, calcium zirconate 10%, yttrium oxide 60%; particles with a size greater than 0.15 mm and less than or equal to 0.45 mm, particles with a size greater than 0.074 mm and less than or equal to 0.15 mm, and particles with a size greater than 0.05 mm and less than or equal to 0.074 mm. The composite doped material particles with a particle size of mm account for 18%, 48%, and 10% of the total solid raw materials by mass, respectively; the fine powder of the composite doped material with a particle size of less than or equal to 43µm accounts for 24% of the total solid raw materials by mass; the yttrium oxide micro powder with a purity of Y2O3 ≥ 99.5% and a particle size range of median diameter D50 ≤ 5µm accounts for 0.5% of the total solid raw materials by mass (added); an aqueous resin solution is used as a binder, and the binder accounts for 4.5% of the total solid raw materials by mass (added); after the above raw materials are mixed and sieved, they are placed in a sealed material tank and left to stand for 24 hours, dried and sieved, and then placed in a mold for isostatic pressing to form a crucible; after drying at 170℃, it is fired at a high temperature of 1750℃ to obtain a high entropy stability crucible for titanium and titanium alloy smelting.

Claims

1. A method for preparing a high-entropy stable crucible for melting titanium and titanium alloys, characterized in that: High-entropy stability crucibles are made primarily from composite doped materials. The composite doped material particles and fine powder, yttrium oxide micro-powder, and organic binder are mixed and stirred evenly in a high-speed mixer. After sieving, the mixture is placed in a sealed trough and left to stand for 12–24 hours. It is then placed in a mold and hydraulically formed into a crucible. Alternatively, the evenly mixed raw materials can be directly dried, sieved, and then isostatically pressed into a crucible. After drying at 100–180℃ and firing at 1650–1750℃, the crucible product is obtained.

2. The method for preparing a high-entropy stable crucible for melting titanium and titanium alloys according to claim 1, characterized in that: The composite doped material refers to a barium zirconate-calcium zirconate-yttrium oxide material, which is prepared by high-temperature sintering or high-temperature electrofusion. Its molar percentage composition is: barium zirconate 20-40%, calcium zirconate 10-20%, and yttrium oxide 40-70%.

3. The method for preparing a high-entropy stable crucible for melting titanium and titanium alloys according to claim 1, characterized in that: The composite doped material particles refer to particles with particle sizes ranging from greater than 0.15 mm to less than or equal to 0.45 mm, greater than 0.074 mm to less than or equal to 0.15 mm, and greater than 0.05 mm to less than or equal to 0.074 mm, which respectively constitute 15% to 20%, 40% to 50%, and 10% to 15% of the total mass of the solid raw materials in the crucible product.

4. The method for preparing a high-entropy stable crucible for melting titanium and titanium alloys according to claim 1, characterized in that: The particle size range of the composite doped material fine powder is less than or equal to 43µm, and the addition amount is 20% to 25% of the total solid raw material of the crucible product.

5. The method for preparing a high-entropy stable crucible for melting titanium and titanium alloys according to claim 1, characterized in that: The yttrium oxide micro powder has a purity of Y2O3 ≥ 99.5%, a particle size range of median diameter D50 ≤ 5µm, and is added at a rate of 0.5% ~ 1.5% of the total mass of the solid raw materials in the crucible product (added externally).

6. The method for preparing a high-entropy stable crucible for melting titanium and titanium alloys according to claim 1, characterized in that: The binder is one or a mixture of two of the following: phenolic resin, aqueous resin, and dextrin.

7. The method for preparing a high-entropy stable crucible for melting titanium and titanium alloys according to claim 1, characterized in that: The amount of binder added is 4.0% to 7.0% (added externally) of the total mass of the solid raw materials of the crucible product.

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