A method and device for synchronously preparing a ceramic-lined steel pipe and a high-entropy alloy / steel bimetallic product based on static SHS

Abstract

The application discloses a method and device for synchronously preparing a ceramic-lined steel pipe and a high-entropy alloy / steel bimetallic product based on static SHS technology, and belongs to the field of composite material manufacturing. The method comprises the following steps: vertically fixing a carbon steel pipe with an axial dovetail groove on the inner wall, arranging a hot melt plug at the bottom, and filling a specific proportion of thermite. After ignition, a static self-propagating reaction is initiated to generate a high-temperature layered melt. The reaction synchronously realizes the following: the upper-layer Al2O3-based ceramic melt forms a dense lining layer in the pipe; the lower-layer high-entropy alloy melt burns through the hot melt plug, is injected into a mold, and is metallurgically combined with a carbon steel plate which is obliquely placed in the mold to prepare a bimetallic composite plate. Through an integrated process, the application realizes 100% utilization of the by-product high-entropy alloy melt. The product has excellent performance: the porosity of the ceramic layer is less than or equal to 2%, and the interface strength is greater than or equal to 350 MPa. The process energy consumption can be reduced to about 620 kWh / t, the production cycle is shortened to about 3.5 hours, and the process has both environmental protection and economy.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite material manufacturing technology, specifically relating to a method and apparatus for simultaneously preparing ceramic-lined steel pipes and high-entropy alloy / steel bimetallic products based on static self-propagating high-temperature synthesis technology. Background Technology

[0002] When preparing ceramic linings inside steel pipes using the static self-propagating high-temperature synthesis method, byproduct ferroalloys accounting for 35%-50% of the total raw materials are generated. These byproducts exhibit large fluctuations in composition and substandard performance, and are often treated as waste, leading to resource waste and increased costs. High-entropy alloys possess excellent performance, but their mainstream preparation methods (such as vacuum melting) suffer from high energy consumption (>3800 kWh / t), easy elemental segregation, and long production cycles. Meanwhile, the existing manufacturing processes for bimetallic wear-resistant composite materials (such as liners), which are urgently needed in the market, (such as explosive bonding and hot rolling bonding) suffer from low interfacial bonding strength (often <250 MPa), high cost, and limited shape. Therefore, developing an integrated method and apparatus that can synergistically utilize SHS reaction products and simultaneously manufacture high-performance ceramic lining pipes and high-entropy alloy / steel bimetallic products has significant economic and technological value. Summary of the Invention

[0003] This invention aims to overcome the above-mentioned shortcomings and provide an innovative method and apparatus for the simultaneous preparation of ceramic-lined steel pipes and high-entropy alloy / steel bimetallic products based on static self-propagating high-temperature synthesis (SHS). A schematic diagram of the process system is shown below. Figure 1 , Figure 2 As shown. Specifically, it includes the following steps:

[0004] (1) Provide a carbon steel pipe with axial or spiral grooves on the inner wall, fix it vertically, and set a hot melt plug at the bottom of it;

[0005] (2) The steel pipe is filled with a thermite, the thermite comprising iron oxide, aluminum powder and alloy element powder;

[0006] (3) Ignite the thermite to initiate a static self-propagating reaction and generate a layered melt: the upper layer is an Al2O3-based ceramic melt and the lower layer is a Fe-X-based high-entropy alloy melt;

[0007] (4) The ceramic melt cools on the inner wall of the steel pipe to form a ceramic lining; at the same time, the high-entropy alloy melt melts through the hot melt plug and is injected into the casting and welding mold.

[0008] (5) The high-entropy alloy melt undergoes metallurgical bonding with the surface of a pre-placed carbon steel plate in the casting and welding mold to form a bimetallic composite product; optionally, the bimetallic composite product is subjected to heat treatment to optimize its performance.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0010] 1. High resource utilization rate, achieving green manufacturing:

[0011] The by-product ferroalloy (accounting for 35%-50% of the raw materials) generated during the traditional static SHS method for preparing ceramic-lined steel pipes is 100% converted in situ into a high-performance, high-entropy alloy with controllable composition. This completely solves the problem of by-product waste and achieves zero waste discharge and efficient resource recycling from the source.

[0012] 2. Significant breakthrough in overall product performance:

[0013] Excellent ceramic lining quality: The prepared Al2O3-based ceramic lining has high density and the porosity can be stably controlled at ≤2%, which is significantly lower than the level of ≥8% in the traditional SHS process, thus greatly improving wear resistance and corrosion resistance.

[0014] Strong bimetallic interface bonding: The high-entropy alloy melt and the carbon steel matrix achieve complete metallurgical bonding with an interface bonding strength of ≥350MPa, far exceeding the national standard (≥210MPa) requirement, ensuring the high reliability and long service life of the composite product under complex working conditions such as impact and wear.

[0015] High-entropy alloys exhibit superior performance: synthesized in situ through aluminothermic reaction, they possess uniform composition, effectively overcoming the elemental segregation problem inherent in traditional smelting methods. The resulting high-entropy alloys combine high hardness, high strength, and good toughness, exhibiting superior stability compared to traditional high-chromium cast iron materials under harsh environments such as impact wear and high-temperature wear.

[0016] 3. Production costs and energy consumption are significantly reduced, resulting in outstanding economic benefits:

[0017] Extremely low energy consumption: The process mainly relies on the chemical energy released by the reaction itself, and the overall energy consumption can be reduced to about 620 kWh / t, which is only about 16% of the energy consumption of traditional high-entropy alloy vacuum melting process (>3800 kWh / t).

[0018] High efficiency and short cycle: It realizes the integrated and simultaneous preparation of ceramic inner liner tube and bimetallic product, and the production cycle can be shortened to about 3.5 hours / piece, which is much more efficient than the traditional step-by-step preparation process (which usually takes tens of hours).

[0019] Significant cost advantages: While achieving high performance, the overall manufacturing cost is significantly reduced by eliminating the need for external high-energy-consuming smelting, avoiding waste disposal costs, and greatly improving production efficiency.

[0020] 4. Integrated process and equipment, highly adaptable:

[0021] The specialized equipment enables continuous operation of reaction, automatic melt separation, quantitative casting, and casting-welding, ensuring stable and controllable processes. By adjusting the molds and process parameters, it can be flexibly applied to the production of various bimetallic composite products such as crusher hammers, wear-resistant liners, and composite pipes, with a wide range of applications. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0023] Figure 1 This is a schematic diagram of a process system for the simultaneous preparation of ceramic-lined steel pipes and high-entropy alloy / steel bimetallic plates based on static SHS.

[0024] Figure 2 This is a schematic diagram of a process system for the simultaneous preparation of ceramic-lined steel tubes and high-entropy alloy / steel bimetallic tubes based on static SHS (Self-Synthetic Hybridization).

[0025] Explanation of component labels in the diagram:

[0026] 1-Vertical steel pipe: As a reaction vessel, its axial dovetail groove on the inner surface provides favorable conditions for the adhesion of the ceramic layer.

[0027] 2-Ceramic lining: Formed by cooling Al2O3-based ceramic melt generated by the aluminothermic reaction, it has good wear resistance and corrosion resistance.

[0028] 3-High-entropy alloy melt: It is generated by reaction below the thermite layer and then flows into the casting mold through the gating system.

[0029] 4-Thermite layer: Composed of various metal oxides and reducing agents, it undergoes an aluminothermic reaction upon ignition, providing high temperature and melt for the entire process.

[0030] 5-Hot melt pad: Placed above the pouring gate, it is burned through after the aluminothermic reaction is completed, and then the high-entropy alloy melt can flow into the casting mold cavity.

[0031] 6- Casting and welding mold: Its cavity is used to accommodate inclined carbon steel plates and accept high-entropy alloy melt to achieve casting and welding composite.

[0032] 7-Riser: Used for venting and feeding to prevent defects in castings.

[0033] 8- Inclined carbon steel plate ( Figure 1 ) or vertically placed carbon steel pipe ( Figure 2 As a casting and welding matrix, it undergoes metallurgical bonding with high-entropy alloy melt to form bimetallic composite steel plates or bimetallic composite steel pipes.

[0034] 9-Metallurgical bonding zone: The region formed by the interdiffusion and reaction between the high-entropy alloy melt and the carbon steel plate interface, ensuring high bonding strength between the bimetals.

[0035] 10- Quartz sand: As a molding material, it mainly serves the functions of heat preservation and air ventilation.

[0036] 11-Steel shell. Detailed Implementation

[0037] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Example 1: Ceramic-lined pipe co-production crusher hammerhead

[0039] Steel pipe pretreatment: 20# steel pipe with specifications of Φ200×1500mm is selected. The inner wall is machined to create a spiral groove with a depth of 1.2mm. Compared to ordinary axial grooves, this spiral groove further enhances the bonding force between the ceramic layer and the inner wall of the steel pipe. An Al-12Si alloy plug is installed at the bottom of the steel pipe. This alloy plug has a melting point of 577℃ and can effectively seal the bottom of the steel pipe in the early stages of the reaction, preventing material leakage.

[0040] Thermite formulation: Al2O3: 68.5wt%, as an iron source, providing iron for the reaction, and also participating in the thermite reaction to release a large amount of heat.

[0041] Al powder: accounting for 24.2 wt%, is the main reducing agent in the aluminothermic reaction. It reacts with Fe2O3 to generate high temperatures, promoting the formation of ceramics and alloys. Cr powder: accounting for 4.1 wt%, can improve the hardness, strength, and corrosion resistance of high-entropy alloys.

[0042] Ni powder: accounting for 2.0 wt%, helps to improve the toughness and high-temperature performance of high-entropy alloys.

[0043] MoO3: accounting for 1.2wt%, can enhance the high-temperature strength and wear resistance of high-entropy alloys.

[0044] Process parameters:

[0045] Reaction temperature: precisely controlled at 2470±50℃. This temperature range ensures that the aluminothermic reaction proceeds fully, while guaranteeing that the resulting ceramics and alloys have good properties.

[0046] Ceramic layer formation time: controlled within 8-12 minutes. Within this time, the Al2O3-based ceramic melt can fully settle and firmly bond with the inner wall of the steel pipe to form a dense ceramic lining.

[0047] The alloy melt pouring temperature is set at 1580℃. This temperature ensures that the high-entropy alloy melt has good fluidity, which is convenient for pouring and molding, while avoiding excessive burning of alloy elements and performance deterioration due to excessive temperature.

[0048] Example 2: Simultaneous preparation of ceramic-lined steel pipes and high-entropy alloy / steel bimetallic wear-resistant liners based on static self-propagating high-temperature synthesis (SHS).

[0049] Mold system: Employs a hydraulic tilting platform with an adjustable tilt angle between 12° and 18°. Precise control of the tilt angle optimizes the bonding process between the high-entropy alloy melt and the carbon steel plate, enhancing the bonding strength of the bimetallic interface.

[0050] Carbon steel plate surface treatment:

[0051] Sandblasting: The surface of the carbon steel plate is sandblasted to achieve a roughness of Ra = 12.5 μm. The rough surface increases the mechanical interlocking area with subsequent coatings and high-entropy alloy melts, thus improving adhesion.

[0052] NiCrBSi alloy layer spraying: An 80μm thick NiCrBSi alloy layer is sprayed onto the surface of the sandblasted carbon steel plate. This alloy layer has good wear resistance and oxidation resistance, and can also undergo a metallurgical reaction with the high-entropy alloy melt during the bimetallic composite process, further enhancing the interfacial bonding strength.

[0053] Interface enhancement technology: 0.3% TiH2 powder is added to the thermite. During the reaction, TiH2 decomposes to produce Ti atoms, which react with C atoms in the system to generate TiC particles in situ, with a particle size between 0.5-2 μm. These TiC particles are uniformly distributed at the bimetallic interface, playing a role in dispersion strengthening and significantly improving the strength and toughness of the bimetallic interface.

[0054] Heat treatment process:

[0055] Solution treatment: The prepared bimetallic wear-resistant liner is heated to 1080±10℃ and held at that temperature for 1.5h, then rapidly cooled by air cooling. Solution treatment allows the alloying elements to fully dissolve in the matrix, forming a uniform solid solution, thus improving the strength and toughness of the material.

[0056] 1. Cryogenic treatment: The solution-treated liner is placed in liquid nitrogen and held at -196℃ for 4 hours. Cryogenic treatment can promote the martensitic transformation of the matrix structure, refine the grains, and at the same time, further transform the residual austenite in the alloy into martensite, thereby improving the hardness and wear resistance of the material.

[0057] 2. Tempering treatment: Finally, the cryogenically treated lining is heated to 260±10℃, held at that temperature for 3 hours, and then air-cooled. Tempering treatment can eliminate residual stress inside the material, stabilize the microstructure, and improve the overall mechanical properties of the material.

[0058] Example 3: Co-production of high-entropy alloy wear-resistant hammerheads using ceramic-lined steel pipes

[0059] Raw material preparation

[0060] Steel pipe: Φ200×1500mm 20# seamless steel pipe, with a pre-installed fusible sealing plug at the bottom.

[0061] Thermite: Fe2O3 72wt%, Al powder 23wt%, Cr powder 3.5wt%, Ni powder 1.5wt% (particle size 80-12 mesh)

[0062] Mold: Water-cooled copper hammerhead mold (preheated to 300℃)

[0063] process

[0064] ① The steel pipe is vertically fixed to the foundation, and thermite is filled to 50mm from the pipe opening.

[0065] ② Ignition by top igniter (Mg+BaO2), reaction temperature reaches 2400℃

[0066] ③ Molten Al₂O₃ (density 3.9 g / cm³) 3 A 3.5mm ceramic layer was formed by sedimentation.

[0067] ④Fe-Cr-Ni alloy (density 7.2 g / cm³) 3 The melt-through of the bottom plug flowed into the mold.

[0068] ⑤ The castings undergo solution treatment at 1050℃ for 2 hours followed by cryogenic treatment with liquid nitrogen.

[0069] Product Performance

[0070] Improved component hardness and wear resistance

[0071] Ceramic liner HV1800 is 45 times larger than the base pipe.

[0072] High-entropy alloy hammerheads (HRC62) are 32 times more potent than high-manganese steel.

[0073] Example 4: Composite Wear-Resistant Liner Co-production System (with Composition Control)

[0074] Innovative Design

[0075] The bottom of the steel pipe is equipped with multi-stage alloying chambers (including Mo and W precast blocks).

[0076] The casting table is tilted at a 15° angle, and the surface of the carbon steel plate (50mm thick) is sandblasted and coated with nickel-based brazing filler metal.

[0077] Key parameters

[0078] 70% melt, 30% melt, aluminothermic reaction, Al2O3 + Fe melt, flow control, ceramic liner, alloying chamber, addition of 5% Mo + 3% W, poured onto carbon steel plate

[0079] Interface bonding strength: ≥350MPa (metallurgical bonding zone thickness 200μm)

[0080] Heat-affected zone control: Laser-assisted rapid cooling, hardness gradient <15%.

[0081] Example 5: Bimetallic Composite Manufacturing of Mine Crushed Walls

[0082] Mold System

[0083] Combined graphite mold: The lower part is a cone-shaped crushing wall cavity, and the upper part is equipped with a guide groove.

[0084] Carbon steel substrate (ZG270-500) preheated to 650±20℃

[0085] Technological Innovation

[0086] Thermite formulation: FeO 65% + Al 28% + V 4% + Co 3%

[0087] Melt separation after reaction:

[0088] Top layer: Al2O3-ZrO2 eutectic ceramic (thickness 4.2mm)

[0089] Bottom layer: FeCoCrNiV high-entropy alloy (yield strength 1250MPa)

[0090] The composite interface generates a TiC-reinforced phase (through in-situ reaction with the addition of 0.5% Ti powder) under the following heat treatment regime:

[0091] Step heating: 650℃×1h→880℃×2h→oil quenching

[0092] Cryogenic treatment: -196℃×4h → Tempering 250℃×4h

[0093] Example 6: Manufacturing of Corrosion-Resistant Bimetallic Pipes

[0094] Special design

[0095] Pre-fabricated spiral grooves on the inner wall of the steel pipe (1.5mm deep, 30mm pitch)

[0096] Alloy composition: Fe-25Cr-20Ni-3Cu-2Si (wt%)

[0097] Combination mechanism

[0098] Mechanical anchoring: The ceramic layer penetrates the groove to form a "barbed structure".

[0099] Metallurgical bonding: Performance comparison of (Fe,Cr)7C3 transition layer formed at the interface:

[0100] Media conditions, conventional 316L corrosion rate, product of this invention

[0101] 10% H₂SO₄ at 60℃: 8.2 mm / year, 0.15 mm / year

[0102] Example 7: Continuous Production System for Large Mill Liners

[0103] Production line configuration

[0104] Three-station rotary device: Automatic steel pipe loading → reaction station → casting station; Casting platform: 12m long hydraulic tilting table (angle adjustable from 0-25°).

[0105] Process optimization

[0106] Multi-tube synchronous reaction: simultaneous ignition of 3 Φ300×2000mm steel pipes

[0107] Alloy flow control: Electromagnetic throttle valve (response time < 0.5s)

[0108] Composite panel dimensions: 1200×800×60mm (40mm carbon steel + 20mm alloy layer)

[0109] Economic analysis

[0110]

[0111]

[0112] Core Innovation Points

[0113] Co-utilization of reaction products

[0114] Creatively separates aluminothermic reaction products automatically based on density difference:

[0115] ρAl₂O₃=3.97g / cm 3 ρ HEA =7.2-7.8 g / cm³ 3

[0116] Simultaneous molding of ceramic liner tubes and high-entropy alloy castings

[0117] Bimetallic Composite Key Technologies

[0118] Preheating temperature gradient control of carbon steel plate (550-750℃)

[0119] The activation energy Ea was controlled within the range of 120-150 kJ / mol.

[0120] In-situ synthesis of high-entropy alloys

[0121] Forced solid solution of refractory elements (W, Mo, V) is achieved through aluminothermic reduction reaction, overcoming the limitations of traditional smelting methods.

[0122] Technical Advantage Verification Data Table

[0123]

[0124] This patent has passed industrial-scale testing (a demonstration line with an annual output of 3,000 tons). After 18 months of application in Baosteel Group's coal mill, the bimetallic liner produced by this patent showed a wear of only 0.8 mm (compared to 12 mm for traditional high-manganese steel liners), verifying the reliability and economy of the technology.

[0125] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for synchronously preparing ceramic-lined steel pipes and high-entropy alloy / steel bimetallic products based on static SHS (Self-Harmonizing Hybridization and High-Entropy Mixing), characterized in that, Includes the following steps: (a) A thermite is filled into a vertically fixed carbon steel pipe (1), the inner surface of which is provided with axial or spiral grooves (11), and a hot melt plug (12) is provided at the bottom; (b) The thermite is ignited to initiate a self-propagating reaction, generating a layered melt: the upper layer has a density of 3.9-4.1 g / cm³. 3 Al2O3-based ceramic melt (2), the lower layer has a density of 7.2-7.8 g / cm³. 3 (c) The ceramic melt (2) is cooled and adheres to the inner wall of the steel pipe to form a ceramic lining. At the same time, the high-entropy alloy melt (3) melts through the hot melt plug (12) and is injected into the casting and welding mold (4); (d) The high-entropy alloy melt (3) is metallurgically bonded to the surface of the inclined carbon steel plate (5) in the mold (4) to form a bimetallic composite structure.

2. The method according to claim 1, characterized in that: The thermite contains the following components by mass percentage: 65-72% Fe source oxide, 23-28% Al powder, and 3-8% alloying element powder of at least two of Cr, Ni, Mo, and V, and its system satisfies the reaction formula 3Fe3O4+8Al→9Fe+4Al2O3+3270kJ as the main reaction.

3. The method according to claim 1, characterized in that: In step (d), the surface of the carbon steel plate (5) is sandblasted to a roughness Ra≥12.5μm and a NiCrBSi alloy transition layer (51) with a thickness of 50-100μm is pre-placed; the tilt angle of the carbon steel plate in the mold (4) is 12°-18°.

4. The method according to claim 1, characterized in that: Adding 0.3-0.5% of TiH2 powder by total mass to the thermite causes Ti atoms generated during the reaction to form TiC particles (52) with a particle size of 0.5-2 μm in situ with C atoms, which are dispersed at the bimetallic interface.

5. The method according to claim 1, characterized in that: The hot melt plug (12) is made of Al-12Si alloy with a melting point ≤577℃; the groove (11) has a depth of 1.2-1.5mm, and when it is a spiral groove, the pitch is 30-50mm.

6. The method according to claim 1, characterized in that: In step (c), a multi-stage alloying chamber (6) is set at the bottom of the steel pipe. Mo and W metal blocks are pre-placed in the chamber. When the high-entropy alloy melt flows through, the composition is controlled by melting, so that the total amount of refractory elements added in the melt is ≤8wt%.

7. An apparatus for implementing the method of any one of claims 1-6, comprising a vertical carbon steel pipe (1) with internal grooves (11) and a hot melt plug (12) at the bottom, and a casting and welding mold (4) having an inclined platform, wherein a carbon steel plate (5) is built into the mold, and the steel pipe and the mold are connected by an alloy melt flow channel (31); characterized in that: The mold (4) is connected to a hydraulic tilting mechanism (41), the tilting angle of which is adjustable from 0 to 25°; an electromagnetic throttle valve (32) is provided at the outlet of the flow channel (31), the response time of which is ≤0.5s.

8. The apparatus according to claim 7, characterized in that: The casting mold (4) is equipped with a combined graphite mold (42), which includes a lower conical crushing wall cavity (43) and an upper guide groove (44); the sidewall of the mold is integrated with a laser quenching module (45) with a power density ≥10 5 W / cm 2 .

9. A bimetallic composite article prepared by the method according to any one of claims 1-6, characterized in that: It includes a carbon steel substrate layer (I), a diffusion layer (II) and a high-entropy alloy layer (III). The diffusion layer (II) contains M7C3 type carbides and FeCr solid solution, with an interfacial bonding strength ≥350MPa and a metallurgical bonding zone thickness ≥200μm.

10. The bimetallic composite article according to claim 9, characterized in that: The high-entropy alloy layer (III) has a dual-phase structure of FCC and BCC, with a yield strength ≥1250MPa; its annual corrosion rate is ≤0.15mm in a 60℃, 10% H2SO4 solution environment.

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