Negative pressure spray deposition equipment and process for negative pressure auxiliary control gas-solid two-phase flow driving liquid phase rapid solidification process

Abstract

The invention belongs to the field of preparation of high-proportion alloy and metal ceramic composite materials, and particularly relates to negative-pressure spray deposition equipment and process for controlling a gas-solid two-phase flow to drive a liquid phase to rapidly solidify in a negative-pressure-assisted manner. The equipment comprises a smelting cabin, a tundish cabin, a deposition cabin, an injection mechanism and a two-stage vacuum system, through cooperative work of the smelting cabin, the tundish cabin, the deposition cabin, the injection mechanism, the two-stage vacuum system and all parts, high-vacuum smelting and negative-pressure environment injection are achieved, and the gas-solid two-phase flow driven negative-pressure injection deposition process is completed. According to the technology, under the vacuum environment, through driving of gas-solid two-phase flow, spray deposition forming of metal and a composite material of the metal can be achieved, and metal-based ceramic phase strengthening, high-alloy uniform solid solution, fine grain strengthening and solidification defect reduction can be achieved in the rapid solidification process; therefore, the mechanical property, the corrosion resistance and the high temperature resistance of the material are remarkably improved, and the material requirements in the fields of aerospace, automobile manufacturing, energy and the like are met.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of high-proportion alloys and metal-ceramic composite materials, and particularly relates to a negative pressure spray deposition device and process for negative pressure-assisted control of a gas-solid two-phase flow-driven liquid phase rapid solidification process. Background Art

[0002] High-quality special alloys include alloys for special application scenarios such as ultra-high-strength steel, special stainless steel, bearing steel, protective steel, high-strength and high-conductivity copper alloy, wear-resistant copper alloy, etc. As my country's manufacturing industry develops towards high-end, the application end of special structural-functional materials requires the matrix to have higher strength, higher toughness, higher wear resistance and even higher thermal conductivity / electrical conductivity. However, due to the limitations of traditional material preparation methods, its component system design, strengthening and toughening methods, and electromagnetic property control are all greatly restricted. It is necessary to achieve performance improvement and function expansion through innovative upgrades in the forming process. Its development trend is high-alloy materials and composite materials.

[0003] Powder metallurgy can achieve uniform composites of metals and ceramics through mechanical alloying, but it also has problems such as low efficiency, large fluctuations in batch performance, and low yield rate. It is urgent to develop efficient and low-cost metal-based composite material preparation processes. Under the existing process conditions, the inability to add a large amount of hard phase during the smelting process and the formation of segregation flow during the solidification process directly restrict the development of a variety of metal composite alloy materials. Rapid solidification technology and experimental equipment are needed to develop a new generation of special materials. Summary of the invention

[0004] The purpose of the present invention is to provide a negative pressure spray deposition equipment and process for negative pressure assisted control of gas-solid two-phase flow to drive the rapid solidification process of the liquid phase, to achieve efficient preparation of high-proportion alloy and ceramic phase composite materials based on the smelting method, and to solve common problems such as spray deposition pore defects, difficulty in adding second phase particles, excessive spray gas volume, and high cost of preparing metal composite materials.

[0005] The technical solution of the present invention is:

[0006] A negative pressure spray deposition device for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process, the device comprises a smelting chamber, a tundish chamber, a deposition chamber, a spray mechanism, and a two-stage vacuum system, and the specific structure is as follows:

[0007] The smelting chamber, the tundish chamber, and the sedimentation chamber are connected in sequence, and the two ends of the tundish chamber are respectively vertically connected to the smelting chamber and the sedimentation chamber, the smelting chamber is vertically upward relative to the tundish chamber, and the sedimentation chamber is vertically downward relative to the tundish chamber; one end of the tundish chamber extends into the smelting chamber, and a gate valve communicating with the inner cavity of the smelting chamber is arranged on the top of the end of the tundish chamber extending into the smelting chamber, a steel ladle is arranged in the smelting chamber, a tundish chamber sealing door is arranged at the top opening of the tundish chamber, the tundish is placed in the tundish chamber through the tundish chamber sealing door, and the inclination direction of the steel ladle corresponds to that of the tundish;

[0008] The bottom opening at one end of the tundish corresponds to the bottom opening of the tundish chamber, a pouring ingot is provided at the bottom opening of the tundish chamber, the center hole of the pouring ingot is a water inlet vertically connected to the tundish and the bottom opening of the tundish chamber, a rotating disk and a lifting device thereof are provided at the lower part of the inner cavity of the sedimentation chamber, the rotating disk and the lifting device thereof are composed of a rotating disk and a lifting device, the output end of the lifting device is connected to the rotating disk through a vertical center axis, the injection mechanism is horizontally arranged at the upper part of the sedimentation chamber, the center hole of the injector of the injection mechanism is above the water inlet, and the nozzle on the injector is below the rotating disk;

[0009] The two-stage vacuum system is provided with a first-stage vacuum pump group and a second-stage vacuum pump group. The first-stage vacuum pump group is connected to the inner cavity of the smelting chamber through a pipeline, and the lower side of the deposition chamber is connected to the second-stage vacuum pump group through a pipeline.

[0010] The negative pressure assisted control of the gas-solid two-phase flow driven liquid phase rapid solidification process of the negative pressure jet deposition equipment, the jet mechanism is provided with an air compressor, a powder particle feeding mechanism, a particle loader, a gas-solid two-phase flow interface, a cyclone filter component, an ejector, a nozzle, and a drive motor, one side of the ejector is provided with a drive motor, the drive motor is connected to the ejector through an output shaft, and the ejector is independently controlled to swing by the drive motor; the other side of the ejector is provided with an air compressor, a powder particle feeding mechanism, a particle loader, a gas-solid two-phase flow interface, and a cyclone filter component, the outlet of the air compressor is connected to the inner cavity of the powder particle feeding mechanism, the gas-solid two-phase flow interface, and the cyclone filter component in sequence, the cyclone filter component is connected to the inner cavity of the ejector through a pipeline, the powder particle feeding mechanism is provided with a particle loader, and the particle loader is connected to the inner cavity of the powder particle feeding mechanism; the ejector is an annular structure, and the nozzle is located between the outer side of the center hole of the ejector and the inner wall of the annular structure.

[0011] The negative pressure spray deposition equipment for negative pressure assisted control of gas-solid two-phase flow to drive the rapid solidification process of the liquid phase has an annular structure slit or a porous structure evenly distributed along the circumference at the upper part of the nozzle, the annular structure slit or the porous structure of the nozzle is connected to the inner cavity of the injector, the lower end of the nozzle is an outward-expanding trumpet mouth, the lower plane of the nozzle is flush with the lower plane of the injector, and the gas-solid two-phase flow enters the inner cavity of the injector and is output from the annular structure slit or the porous structure of the nozzle.

[0012] The negative pressure jet deposition equipment for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process has a first control valve provided on the pipeline connecting the first-stage vacuum pump group with the inner cavity of the smelting chamber, and a second control valve, a solid phase particle cyclone separator and a third control valve provided in sequence on the pipeline connecting the deposition chamber with the second-stage vacuum pump group.

[0013] A negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process comprises the following steps:

[0014] (1) The superheat of the base alloy liquid is controlled to be 40-120°C higher than the melting point, and the ladle is used for bottom argon blowing to remove slag and degassing. After the smelting is completed, large inclusions near the positive and negative tilting of the ladle are captured by the adsorption layer, and sampling and composition fine-tuning are completed, and pouring is ready;

[0015] (2) Open the sealed door of the tundish cabin on the top of the tundish cabin, put the tundish preheated to above 1200°C into the tundish cabin, connect the bottom opening of the tundish with the water inlet of the pouring ingot, and then close the sealed door of the tundish cabin. The second-stage vacuum pump group starts to evacuate the air until the pressure is below 5000Pa. At this time, the protective gas is filled in the smelting cabin to 0.01-0.03MPa and then the filling is stopped;

[0016] (3) The gate valve of the smelting chamber is opened, and the three chambers of the smelting chamber, the tundish chamber, and the deposition chamber are connected. The ambient pressure is maintained at ≤5000Pa by the second-stage vacuum pump group. The ladle is tilted for pouring. After the liquid level reaches the set height, it remains stable. The flow rate of the alloy liquid flowing through the water inlet of the pouring ingot is stable.

[0017] (4) The nozzle is located in the middle of the ejector, the center lines are aligned, and the nozzle uses a porous structure or a slit to inject gas and solid phases;

[0018] (5) The ejector is designed with one or two powder particle feeding mechanisms, which uniformly feed the particles into the high-speed airflow, thereby accurately loading the second phase particles into the alloy; after the particles are preheated to a temperature ≥ 600°C, they enter the powder particle feeding mechanism through the particle loader, and the powder feeding rate of the second phase particles with a particle size of 20 to 3000 nm is 100 to 1250 g / min;

[0019] (6) The gas-solid two-phase flow fully disperses the alloy liquid flowing out of the water outlet of the pouring ingot into uniform droplets. The horizontal rotating disk at the top of the rotating disk and its lifting device is controlled to be 200-450 mm away from the lower end of the ejector, the ingot diameter is 200-850 mm, the rotating speed of the rotating disk is 40-200 r / min, the descending speed of the rotating disk is 50-200 mm / min, the surface molten pool depth is controlled to be 1-3 mm, and the second-stage vacuum pump group 18 controls the negative pressure of the solidification environment to be ≤5000 Pa;

[0020] (7) Short process energy-saving process for forging after hot charging furnace equalization: After the deposition ingot is sprayed, the top temperature is controlled to be ≤(T s -100℃), bottom temperature control≤(T s -200℃), take out the deposited ingot and send it into a forging holding furnace for equalizing the temperature for 1 to 3 hours, and then forge it into a square billet or a round billet for subsequent processing and heat treatment.

[0021] The negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process, in step (1), the base alloy smelted in the ladle is various high element addition alloys suitable for induction or resistance heating, the base alloy includes: medium-high carbon steel, high alloy steel, medium manganese steel, high manganese steel, high nitrogen stainless steel, nickel-tin-copper alloy, manganese-nickel-copper alloy or high temperature alloy; the second phase particles are various functional particles, including silicon carbide, boron carbide, silicon dioxide, boron nitride, aluminum oxide, corundum, graphene, carbon nanotubes or graphite particles, the mass fraction of the second phase particles is 1-8%, and the particle size is controlled to be below 20μm.

[0022] In the negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification, in step (3), the number of nozzles configured is 1 to 3 according to the diameter range of the spray deposition ingot, and the diameter of each nozzle is The flow rate of each water nozzle is 10-80kg / min, the outlet flow rate of each water nozzle is controlled at 1-2m / min, the position of the water nozzle is opposite to different positions of the radius of the deposited ingot, and different flow rates are controlled by sizing the water nozzle size; when there are two water nozzles, the aperture area ratio of the water nozzle is controlled at 1:0.7-0.9; when there are three water nozzles, the aperture area ratio of the water nozzle is controlled at 1:0.7-0.9:0.6-0.85.

[0023] The negative pressure spray deposition process of negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process, in step (4), when a porous structure is used to spray gas-solid two-phase, the number of holes opened on the nozzle of the injector is 10 to 20, and the aperture is 4 to 8 mm; or, when a slit method is used to spray gas-solid two-phase, an annular slit is designed on the nozzle of the injector, and the slit width is controlled to be 2 to 4 mm; the injector as a whole swings -40° to +40° relative to the horizontal direction, and the scanning frequency is 0 to 10 Hz; the gas injection pressure is 0.2 to 0.7 MPa, and the injection volume of the injector 22 is 5 to 40 m 3 / min, particle loading amount 0~2500g / min.

[0024] In the negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process, in step (5), the second phase particles need to be surface modified before being added to the powder particle feeding mechanism, and the surface modification method includes low-temperature ball milling, acid washing or evaporation method with matrix metal powder; when the second phase particles and the matrix metal powder are low-temperature ball milled, the second phase particles are ball milled and mixed with the matrix metal powder in liquid nitrogen, the mass fraction of the second phase particles is more than 95%, and the grinding ball material is super S280 stainless steel; wherein the second phase particle diameter is less than 20μm, the particle diameter of the matrix metal powder used for modification is 0.5-30μm, and the ball milling time is more than 24 hours.

[0025] The negative pressure spray deposition process of negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process, in step (6), the liquid phase is driven by gas-solid two-phase flow, and the gas phase and solid phase are used as cooling medium, and the ratio of gas-solid consumption of solidification latent heat is 1:1.5-3; after the spraying is completed, the number of pores counted on the solidified end surface of the deposited ingot is ≤5 / 10mm 2 , and the pore diameter is ≤2μm, and all the pores are pressed together after forging.

[0026] The design concept of the present invention:

[0027] The present invention combines innovative practices with an advanced material preparation method of gas-solid two-phase flow and vacuum jet deposition technology. The process can realize the jet deposition forming of metals and their composite materials under vacuum environment by driving gas-solid two-phase flow. This rapid solidification process can realize metal-based ceramic phase strengthening, uniform solid solution of high alloys, fine grain strengthening and reduction of solidification defects, thereby significantly improving the mechanical properties, corrosion resistance and high temperature resistance of the material, which is of great significance for the demand for high-performance materials in the fields of aerospace, automobile manufacturing, energy, etc. The gas-solid two-phase flow driven metal vacuum jet deposition process has high process flexibility. Parameters such as gas pressure, solid phase particle type and content, and deposition temperature can be adjusted as needed to prepare materials with different properties and uses. This flexibility provides more possibilities for material design and preparation. At the same time, since the deposition process under vacuum environment reduces the oxidation and contamination of the material, the subsequent processing cost is reduced. The process introduces solid phase medium particles on the basis of gas atomization to form a gas-solid two-phase mixed flow. This new atomization mechanism significantly improves the atomization efficiency, refines the particle size of the atomized powder, and improves the uniform distribution of the reinforcement phase in the matrix alloy. This innovative forming process provides new ideas and methods for the preparation of high-performance composite materials.

[0028] Advantages and beneficial effects of the present invention:

[0029] 1. The present invention realizes spray deposition in a negative pressure environment of ≤5000Pa (≤0.05bar) through structural design such as vacuum chamber, and the second phase particles act as cooling medium to improve the heat absorption capacity of the mixed medium, reduce the airflow input and flow rate, and quickly discharge the bubbles in the micro-molten pool under negative pressure, and most of the solidification shrinkage holes and looseness are eliminated. The remaining part is also a negative pressure vacuum bubble, which is convenient for forging or extrusion pressing. A large number of spray deposition studies [Document 1] have mentioned that there are a large number of hole-type defects in the micro-positive pressure spraying process, and this problem exists regardless of whether it is nitrogen or argon spraying. Moreover, at present, only the second phase particles of the aluminum-based composite material spray deposition ingot also have pore defects around them [Documents 2, 3]. This is due to the poor wettability of the particles and the gas phase, which causes the retention of the gas phase. The negative pressure solidification process can fundamentally solve this problem.

[0030] (Document 1Opportunitiesand challenges ofspray forming high-alloyed steels[J].Materials ScienceandEngineeringA477(2008)69-79.

[0031] Document 2Microstructureandmechanicalproperties of spray deposition Al / SiCp composite after hot extrusion[J]. Journal ofMaterials Engineering andPerformance,2011,20(9):1697-1702.

[0032] Document 3Spray processing of 2014-Al+SiCp composites and their property evaluation[J].Materials Science andEngineeringA, 2005,(412):19-26.

[0033] 2. The loading method and composite method of the second phase particles of the present invention can realize the injection molding of composite materials of high melting point metals. The second phase particles are not only the kinetic energy carrier of the dispersed liquid phase, but also the cooling medium of the alloy liquid phase, and also the strengthening or functional structure of the metal matrix composite material. For example, in the injection thermal neutron shielding steel 304B8 material, the submicron B 4C particles are both coolants and neutron shielding functional metals. In the spray deposition process of medium manganese steel + SiC particle reinforced ultra-high strength and wear-resistant steel, SiC is both a strengthening phase and a functional particle that improves thermal conductivity. At present, there are no patents or literature reports on the introduction of second-phase functional particles into copper, steel and nickel-based high-temperature alloys through gas-solid two-phase flow driving. The typical technology is the technology of adding SiC particles to the aluminum matrix through gas-solid two-phase flow injection in aluminum alloys, as reported in literature 2, 3, 4 and 5. This type of technology is generally deposited under normal pressure, and the main problem is the agglomeration of SiC particles and the presence of pores around them.

[0034] The present invention solves the porosity problem through three innovative process measures: ① The second phase particles are subjected to low temperature ball milling with the base metal powder, so that a layer of metal particles is attached around the second phase particles, thereby reducing the surface energy of the alloy liquid to achieve surface modification; ② It constructs a negative pressure jet solidification environment, reasonably designs the mixing and exhaust directions, improves the linearity of the particles and airflow movement, can efficiently disperse and cool the alloy liquid, greatly stabilize the solidified micro-molten pool, and promote the rapid discharge of gas; ③ The second phase particles are preheated to reduce the energy difference between the two after the particles impact the liquid phase. The above three points have not been reported in patents or literature, and are original.

[0035] Reference 4 Study on the microstructure and properties of spray-deposited ultra-high strength aluminum matrix composites[J]. Hot Working Technology, 2024, 53(4): 111-114.

[0036] Reference 5 Research progress of spray-formed particle reinforced metal matrix composites[J]. Functional Materials, 2015, 1(46): 01-06.

[0037] 3. The present invention realizes the low-cost and high-efficiency preparation of composite materials of high-alloy matrix and second phase particles such as steel, copper and nickel. Compared with the powder metallurgy mechanical alloying process disclosed in patents CN102690977A and CN110863153A, the efficiency of oxide loading and dispersion is greatly improved and the cost is reduced.

[0038] 4. The temperature of the ingot formed by the present invention is relatively high. The ingot can be directly forged or pierced and rolled after high-temperature sampling and uniformization, which can eliminate the slow cooling and heating steps and significantly reduce the heat emission of forming.

[0039] 5. Analysis and comparison of the innovation of this invention and other spray deposition related patents:

[0040] ① Patent CN 115740451 A discloses a large-diameter metal ingot spray forming equipment and method, which is mainly aimed at large-scale ingot spraying, and its characteristics include inclined nozzle arrangement, cam-type nozzle motion control, "petal-type" nozzle motion trajectory, etc. The difference between the present invention and this patent is not only the negative pressure solidification, second-phase particle driven cooling and composite material billet making process, but also obvious differences: the nozzle of the present invention is an annular structure slit or a porous structure evenly distributed along the circumference, and the nozzle annular structure slit or porous structure is connected to the inner cavity of the ejector (the nozzle of patent CN 115740451 A is tilted instead of adjusting the temperature and flow); the present invention adjusts the injection molten pool temperature by the size of the sizing nozzle, and each nozzle motion trajectory is independently controlled; the present invention adopts 2-3mm small molten pool control, cooperates with the negative pressure environment, and reduces the generation of defects, which is essentially different from the control idea of ​​patent CN 115740451 A.

[0041] ② Patent CN 101967595 A discloses a method for preparing a spray-deposited nanoparticle-reinforced zinc-based composite material, in which solid phase particles are added through a second set of devices, and the second phase particles are directly sprayed on the surface of the solidified molten pool without participating in the dispersed liquid phase. The gas-solid two-phase flow of the present invention is mixed and then sprayed out by the ejector, and the solid phase is the main part of the dispersed liquid phase and absorbs the latent heat of solidification, which is essentially different.

[0042] ③ Patent CN 114101609 B discloses a process for spray rolling aluminum alloy strips, the core idea of ​​which is to quickly obtain a semi-solid structure by dispersing the liquid phase through the gas phase, and directly forming the strip material. The present invention mainly prepares round ingots, which are rolled into strips after forging. The process ideas of the two are completely different.

[0043] ④ Patents CN 104878301 B and CN 117626110 A respectively disclose a method for spray forming high-speed steel and roll steel blanks. Since there are many literatures on spray forming processes, this patent only claims the composition and organizational morphology of high-speed steel and roll steel in combination with the spray process. The present invention is significantly different from patents CN 104878301B and CN117626110A in core methods, process effects and key innovations such as gas-solid two-phase flow driven liquid phase dispersion, negative pressure solidification exhaust gas and the use of the second phase composite function;

[0044] ⑤ Patent CN 100479951C discloses a mechanical swinging atomization liquid guiding system suitable for preparing large-sized jet deposition ingots. Similar patents include CN1209217C, both of which use two-stage atomization drive. That is, the double-layer atomizer design fully disperses the liquid phase through the double-layer gas to achieve the effect of refining the alloy liquid. The difference between the present invention and patents CN 100479951C and CN1209217C is that the present invention adopts gas-solid two-phase flow dispersion and a single-layer ejector structure, and the solid phase participates in controlling solidification, which is more concise and efficient than patents CN 100479951C and CN1209217C. This is the essential difference.

[0045] ⑥ Patents CN 105345004 B and CN 109487129 B are both designed for high-proportion aluminum alloy spray deposition processes. The spray problem, spray angle, rotation speed and descent speed of the rotating disk and its lifting device are designed mainly for the characteristics of aluminum alloys for patent protection, and the air pressure in the spray cabin is maintained at around 1.1 bar. The present invention mainly sprays high-alloy materials with high-temperature substrates such as copper, iron, and nickel. Its solidification phase change latent heat, solid-liquid two-phase temperature range and processing temperature are essentially different from patents CN 105345004 B and CN 109487129 B. Moreover, the present invention uses gas-solid two-phase flow to drive the liquid phase, and solidifies under negative pressure, which is the core difference.

[0046] ⑦ Patents CN 114799187 B and CN 107803510 B are solutions for gas atomization powder making technology. The vacuum gas atomization described in these two patents refers to vacuum smelting to prepare alloy liquid. During the gas atomization process, the pressure in the cabin is slightly positive, which is essentially different from the ≤5000Pa negative pressure environment solidification of the present invention.

[0047] ⑧ According to the reports in Documents 6, 7, and 8, Professor Chen Zhenhua of Hunan University and other scholars proposed a process for preparing stainless steel powder by gas-solid two-phase drive, in which the solid phase particles are water-soluble particles such as sodium chloride, and the main function is to dissipate the kinetic energy phase. After the solid phase particles impact the liquid flow, the sodium chloride particles are removed by washing. In the present invention, the second phase particles are not only the kinetic energy phase, but also the coolant, nucleating agent and functional structure after solidification. A variety of processing methods are used to stably disperse the second phase particles in the matrix to form a metal-based composite material, which plays a composite function of wear resistance, hardness improvement, stiffness improvement, thermal conductivity / magnetic conductivity, shielding, etc., which is essentially different from the control ideas of Documents 6 to 8.

[0048] Reference 6 Preparation of fine stainless steel powder by gas-solid two-phase flow atomization method [J]. The Chinese Journal of Nonferrous Metals, 2005, (04): 584-589.

[0049] Reference 7 Research on the solid atomization principle and process of liquid metal and alloy [D]. Hunan University, 2005.

[0050] Reference 8. Research on the principle of solid atomization process of liquid metals and alloys. Hunan Province, Hunan University, 2005-01-01. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the gas-solid two-phase flow driven negative pressure spray deposition equipment of the present invention.

[0052] Figure 2 It is a schematic diagram of the combined structure of the tundish, the deposition chamber and the injection mechanism of the present invention.

[0053] In the figure, 1 is a first-stage vacuum pump group; 2 is a first control valve; 3 is a smelting chamber; 4 is a ladle; 5 is a tundish; 6 is a gate valve; 7 is a tundish chamber sealing door; 8 is a tundish chamber; 9 is a water inlet; 10 is a pouring ingot; 11 is an injection mechanism; 12 is a deposition chamber; 13 is a deposition ingot; 14 is a rotating disk and its lifting device; 15 is a second control valve; 16 is a solid-phase particle cyclone separator; 17 is a third control valve; 18 is a second-stage vacuum pump group; 19 is a driving motor; 20 is a nozzle; 21 is a CCD camera; 22 is an ejector; 23 is a slit; 24 is a powder particle feeding mechanism; 25 is a particle loader; 26 is a cyclone filter component; 27 is an air compressor; 28 is a gas-solid two-phase flow interface; 29 is a rotating disk; 30 is a lifting device; 31 is a center hole. DETAILED DESCRIPTION

[0054] In the specific implementation process, the present invention drives the liquid phase to solidify rapidly in a negative pressure environment through gas-solid two-phase flow, thereby obtaining a metal-based composite material with no segregation, no pore defects, fine grains, and dispersed and strengthened second-phase particles. Its key process innovations include: (1) gas-solid two-phase flow drives the liquid phase, and the solid phase is used as a cooling medium and solidification material to reduce the amount of gas phase; (2) a vacuum pump group and a three-chamber design are used to achieve negative pressure solidification and reduce defects; (3) the three-chamber structure ensures high vacuum melting and negative pressure solidification; (4) the second phase particles are fine and uniformly dispersed, and the matrix strength, toughness, macro-hardness and wear resistance are improved at the same time; (5) the deposited ingot can be hot-loaded and hot-delivered, and can be used as a forging billet or hot-rolled billet, or it can be directly perforated and rolled into a pipe, which is an energy-saving and emission-reduction process.

[0055] like Figure 1-Figure 2 As shown, the present invention proposes a negative pressure spray deposition device for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process, which mainly includes a smelting chamber 3, a tundish chamber 8, a deposition chamber 12, a spray mechanism 11, and a two-stage vacuum system. The specific structure is as follows:

[0056] The smelting chamber 3, the tundish chamber 8, and the deposition chamber 12 are connected in sequence, and the two ends of the tundish chamber 8 are respectively vertically connected to the smelting chamber 3 and the deposition chamber 12, the smelting chamber 3 is vertically upward relative to the tundish chamber 8, and the deposition chamber 12 is vertically downward relative to the tundish chamber 8; one end of the tundish chamber 8 extends into the smelting chamber 3, and a gate valve 6 communicating with the inner cavity of the smelting chamber 3 is arranged on the top of the end of the tundish chamber 8 extending into the smelting chamber 3, a ladle 4 is arranged in the smelting chamber 3, a tundish chamber sealing door 7 is arranged at the top opening of the tundish chamber 8, and the tundish 5 is placed in the tundish chamber 8 through the tundish chamber sealing door 7, and after the gate valve 6 is opened, the ladle 4 can be tilted at a certain angle to correspond to the tundish 5, and the alloy liquid in the ladle 4 can be poured into the tundish 5.

[0057] The bottom opening at one end of the tundish 5 corresponds to the bottom opening of the tundish chamber 8. A pouring ingot 10 is provided at the bottom opening of the tundish chamber 8. The center hole of the pouring ingot 10 is a water inlet 9 vertically connected to the bottom openings of the tundish 5 and the tundish chamber 8. A rotating disk and its lifting device 14 are provided at the lower part of the inner cavity of the deposition chamber 12. The rotating disk and its lifting device 14 are composed of a rotating disk 29 and a lifting device 30. The output end of the lifting device 30 is connected to the rotating disk 29 through a vertical center axis. The injection mechanism 11 is horizontally penetrated through the upper part of the deposition chamber 12, and the center hole of the injector 22 of the injection mechanism 11 corresponds to the water inlet 9 above, and the nozzle 20 on the injector 22 corresponds to the rotating disk 29 below. The gas-solid two-phase flow of the nozzle 20 fully disperses the alloy liquid flowing out of the water inlet 9 of the pouring ingot 10 into uniform droplets, which converge at the top of the rotating disk 29 and solidify into a deposited ingot 13. A CCD camera 21 is provided outside a transparent window on one side of the deposition chamber 12. The CCD camera 21 corresponds to the alloy droplets and the molten pool formed on the top of the rotating disk 29 and is used to observe and detect the injection process and the molten pool solidification process.

[0058] The two-stage vacuum system is provided with a first-stage vacuum pump group 1 and a second-stage vacuum pump group 18. The first-stage vacuum pump group 1 is connected to the inner cavity of the smelting chamber 3 through a pipeline (a first control valve 2 is provided on the pipeline); the lower side of the deposition chamber 12 is connected to the second-stage vacuum pump group 18 through a pipeline, and a second control valve 15, a solid-phase particle cyclone separator 16 and a third control valve 17 are provided on the pipeline in sequence.

[0059] The injection mechanism 11 is provided with an air compressor 27, a powder particle feeding mechanism 24, a particle loader 25, a gas-solid two-phase flow interface 28, a cyclone filter component 26, an injector 22, a nozzle 20, and a drive motor 19. A drive motor 19 is provided on one side of the injector 22, and the drive motor 19 is connected to the injector 22 through an output shaft. The injector 22 can be independently controlled to swing by the drive motor 19 (such as a servo motor); an air compressor 27, a powder particle feeding mechanism 24, a particle loader 25, a gas-solid two-phase flow interface 28, and a cyclone filter component 26 are provided on the other side of the injector 22. The outlet of the air compressor 27 is connected to the inner cavity of the powder particle feeding mechanism 24, the gas-solid two-phase flow interface 28, and the cyclone filter component 26 in sequence. The cyclone filter component 26 is connected to the inner cavity of the injector 22 through a pipeline. A particle loader 25 is provided on the powder particle feeding mechanism 24, and the particle loader 25 is connected to the inner cavity of the powder particle feeding mechanism 24. The ejector 22 is an annular structure, and the nozzle 20 is located between the outer side of the center hole 31 of the ejector 22 and the inner wall of the annular structure. The upper part of the nozzle 20 is an annular structure slit 23 or a porous structure evenly distributed along the circumference. The annular structure slit 23 or the porous structure of the nozzle 20 is connected to the inner cavity of the ejector 22. The lower end of the nozzle 20 is an outwardly flared bell mouth, and the lower plane of the nozzle 20 is flush with the lower plane of the ejector 22. After the gas-solid two-phase flow enters the inner cavity of the ejector 22, it is output from the annular structure slit 23 or the porous structure of the nozzle 20.

[0060] In addition, as required, a nozzle corresponding to the alloy liquid outlet of the pouring ingot 10 can be vertically arranged in the center hole 31 of the injector 22. The number of nozzles to be configured is 1 to 3 according to the diameter range of the spray-deposited ingot. The diameter of each nozzle is The flow rate of each nozzle is 10-80 kg / min, the outlet flow rate of each nozzle is controlled at 1-2 m / min, the nozzle position is opposite to the different positions of the deposited ingot radius, and the different flow rates are controlled by the sizing nozzle size. When there are two nozzles, the aperture area ratio of the nozzle is controlled at 1:0.7-0.9; when there are three nozzles, the aperture area ratio of the nozzle is controlled at 1:0.7-0.9:0.6-0.85.

[0061] The gas-solid two-phase flow driven negative pressure jet deposition equipment realizes vacuum melting and rapid solidification forming of high-proportion alloy composite ingots through a multi-chamber structure design. Its main functions include: ① The melting chamber 3 has a vacuum induction melting function, and the two-stage vacuum system ensures that it maintains a high vacuum state during the melting process to degas, add materials and remove inclusions; ② The tundish 5 connects the melting chamber 3 and the injection mechanism 11. After the tundish 5 is preheated to temperature outside the chamber, it is placed in the tundish chamber 8 and corresponds to the melting chamber 3 and the injection mechanism 11 after vacuuming; ③ The injection mechanism 11 integrates an air compressor 27, a powder particle feeding mechanism 24, a particle loader 25, a gas-solid two-phase flow interface 28, a cyclone filter component 26, an ejector 22, a nozzle 20, and a drive motor 19. The injection mechanism 11 realizes the uniform dispersion of solid phase particles under high pressure and loads gas; ④ The two-stage vacuum system is: the first-stage vacuum pump group 1 configured for the melting chamber 3, the working vacuum pressure ≤5×10 -2 Pa; the second-stage vacuum pump group 18 configured for the deposition chamber 12 during the spray deposition process is used to maintain the environmental pressure ≤ 5000 Pa under the injection gas input condition. Thus, through the three chambers of the smelting chamber 3, the tundish chamber 8, and the deposition chamber 12 and the two-stage vacuum system, each component works together to achieve high vacuum smelting and negative pressure environment spraying, and efficiently complete the gas-solid two-phase flow driven negative pressure spray deposition process.

[0062] like Figure 1-Figure 2 As shown, the present invention proposes a negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow to drive liquid phase rapid solidification process, which is carried out in the following steps:

[0063] (1) The base alloys smelted in ladle are mainly various alloys with high element additions suitable for induction or resistance heating, such as medium-high carbon steel, high alloy steel, medium manganese steel, high manganese steel, high nitrogen stainless steel, nickel-tin-copper alloy, manganese-nickel-copper alloy, high-temperature alloy, etc.; while the second phase particles include functional particles such as silicon carbide, boron carbide, silicon dioxide, boron nitride, alumina, corundum, graphene, carbon nanotubes, and graphite particles.

[0064] (2) The superheat of the alloy liquid is controlled to be 40-120°C higher than the melting point, and the ladle is used for bottom argon blowing to remove slag and degassing. After the smelting is completed, large inclusions near the positive and negative tilting of the ladle are captured by the adsorption layer, and sampling and composition fine-tuning are completed, and preparation for pouring is made.

[0065] (3) Open the tundish cabin sealing door 7 on the top of the tundish cabin 8, load the tundish 5 preheated to above 1200°C into the tundish cabin 8, connect the bottom opening of the tundish 5 with the water inlet 9 of the pouring ingot 10, and then close the tundish cabin sealing door 7. The first-stage vacuum pump group 1 starts to evacuate the air until the pressure is ≤5×10 -2 Pa, at this time, the smelting chamber 3 is filled with protective gas to 0.01-0.03MPa and then the inflation is stopped.

[0066] (4) The gate valve 6 of the smelting chamber 3 is opened, and the three chambers of the smelting chamber 3, the tundish chamber 8, and the deposition chamber 12 are connected. The two ends of the tundish chamber 8 are vertically connected to the smelting chamber 3 and the deposition chamber 12 respectively. The smelting chamber 3 and the tundish chamber 8 are vertically upward, and the deposition chamber 12 and the tundish chamber 8 are vertically downward. The second-stage vacuum pump group 18 maintains the ambient pressure ≤ 5000Pa. The ladle 4 is tilted for pouring. After the alloy liquid flows through the slag retaining mechanism of the tundish, the inclusions are fully adsorbed. After the liquid level reaches the set height, it remains stable, and the alloy liquid flows through the water nozzle 9 of the pouring ingot 10 with a stable flow rate. According to the diameter range of the jet deposition ingot, the number of water nozzles 9 is 1 to 3, and the diameter of each water nozzle 9 is The flow rate of each nozzle 9 is 10-80 kg / min, and the outlet flow rate of each nozzle 9 is controlled at 1-2 m / min. The nozzle 9 is located at different positions of the radius of the deposited ingot 13, and different flow rates are controlled by the sizing nozzle size. When there are two nozzles, the aperture area ratio of the nozzles is controlled to be 1:0.7-0.9; when there are three nozzles, the aperture area ratio of the nozzles is controlled to be 1:0.7-0.9:0.6-0.85.

[0067] (5) The nozzle 20 is located in the middle of the injector 22, the center lines are aligned, and the lower plane of the nozzle 20 is parallel to the lower plane of the injector 22. When a porous structure is used to inject gas-solid two-phases, the number of holes opened on the nozzle 20 of the injector 22 is 10 to 20, and the aperture is 4 to 8 mm. Alternatively, when a slit method is used to inject gas-solid two-phases, an annular slit 23 is designed on the nozzle 20 of the injector 22, and the slit width is controlled to be 2 to 4 mm. The injector 22 as a whole can swing -40° to +40° relative to the horizontal direction (the forward swing angle is positive, and the backward swing angle is negative), the scanning frequency is 0 to 10 Hz, and the injector movement is independently controlled by the drive motor 19 (such as: servo motor); the gas injection pressure is 0.2 to 0.7 MPa, and the injection volume of the injector 22 is 5 to 40m 3 / min, particle loading amount 0~2500g / min.

[0068] (6) The ejector 22 is designed with one or two powder particle feeding mechanisms 24, which accurately and evenly feed the particles into the high-speed airflow, thereby accurately loading the second phase particles into the alloy. After the particles are preheated to a temperature ≥ 600°C, they enter the powder particle feeding mechanism 24 through the particle loader 25, and the second phase particles with a particle size of 20 to 3000 nm are fed at a rate of 100 to 1250 g / min. Particle preheating can reduce the solid-liquid interface energy and improve wettability.

[0069] Before the second phase particles are added to the powder particle feeding mechanism 24, the surface modification is required. The surface modification methods include low temperature ball milling with the base metal powder, acid washing, evaporation and the like.

[0070] The second phase particles are ball-milled and mixed with base metal powder (such as 304 stainless steel, Cu, Fe or Al) in liquid nitrogen, the mass fraction of the second phase particles is more than 95%, and the grinding ball material is super S280 stainless steel. Among them, the second phase particle diameter is less than 20 μm (preferably 0.02-20 μm, more preferably 200-1500 nm), the base metal powder used for modification has a particle diameter of 0.5-30 μm (preferably 20-30 μm), and the ball milling time is more than 24 hours. The second phase particles and the base metal powder are subjected to low-temperature ball milling treatment to promote the adhesion of the base metal powder on the surface of the second phase particles and promote the full wetting of the second phase particles and the steel liquid.

[0071] (7) The gas-solid two-phase flow fully disperses the alloy liquid flowing out of the water nozzle 9 of the pouring ingot 10 into uniform droplets. The horizontal rotating disk 29 on the top of the rotating disk and its lifting device 14 is controlled to be 200-450 mm away from the lower end of the ejector 22, the ingot diameter is 200-850 mm, the rotating speed of the rotating disk 29 is 40-200 r / min, the descending speed of the rotating disk 29 is 50-200 mm / min, the surface molten pool depth is controlled to be 1-3 mm, and the second-stage vacuum pump group 18 controls the negative pressure of the solidification environment to be ≤5000 Pa.

[0072] The liquid phase is driven by gas-solid two-phase flow, and both the gas phase and the solid phase can be used as cooling media. The ratio of gas-solid consumption of solidification latent heat is 1:1.5~3. After the injection is completed, the number of pores counted on the solidified end surface of the deposited ingot is ≤5 / 10mm 2 , and the pore diameter is ≤2μm, and all the pores are pressed together after forging.

[0073] (8) Short process energy-saving process for forging after hot charging furnace equalization: After the deposition ingot is sprayed, the top temperature is controlled to be ≤(T s -100℃), bottom temperature control≤(T s -200℃), take out the deposited ingot and send it into a forging holding furnace for 1-3h to equalize the temperature, and then forge it into a square billet or round billet for subsequent processing and heat treatment. Among them, Ts is the softening temperature.

[0074] The mass fraction of the second phase particles in the forging blank is 1-8%, the particle size is controlled below 20 μm (preferably 0.02-20 μm, more preferably 200-1500 nm), and it is evenly distributed on the matrix alloy without grain boundary segregation. The wear life of the reinforced particles is increased by more than 30%, the macroscopic hardness is increased by more than 20%, and the yield strength, tensile strength and impact energy are reduced by ≤1% compared with the non-second phase reinforced matrix.

[0075] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention.

[0076] Example 1

[0077] In this embodiment, a negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process includes the following steps:

[0078] (1) The ladle smelting metal is medium manganese steel (mass fraction): Mn 7%, C 0.35%, Si 1%, V 0.4%, Cr 1%, Ni 0.5%, Mo 0.8%, S 18ppm, P 0.007%, Fe balance. The second phase particles are SiC, the addition amount is 1.5wt%, and the particle size is 200-800nm.

[0079] (2) The superheat of the alloy liquid is controlled to be higher than the melting point of 80°C, and the ladle is used for bottom argon blowing to remove slag and degassing. After the smelting is completed, large inclusions near the positive and negative tilting of the ladle are captured by the adsorption layer, and sampling and composition fine-tuning are completed, and preparation for pouring is made.

[0080] (3) The tundish compartment is opened, and the tundish preheated to 1210°C is placed in the tundish compartment. The bottom opening of the tundish is connected to the water inlet position of the pouring ingot. Then the sealing door of the tundish compartment is closed, and the first-stage vacuum pump group starts to evacuate the air to a pressure of 3×10 -2 Pa, at this time, the smelting chamber is filled with argon and then the filling is stopped after the pressure reaches 0.01MPa.

[0081] (4) The gate valve of the smelting chamber is opened, and the three chambers of the smelting chamber, the tundish chamber, and the deposition chamber are connected. The second vacuum pump group maintains the ambient pressure at 4000Pa, and the ladle is tilted for pouring. The liquid level reaches the set height of 300mm. According to the diameter of the spray deposition ingot of 420mm, two nozzles are configured with a diameter of and Flow rate is 50kg / min and 33kg / min, and the outlet flow rate is controlled at 1.1m / min.

[0082] (5) The nozzle is located in the middle of the injector, the center line is aligned, the lower plane of the nozzle is parallel to the lower plane of the injector, the number of injector openings is 16, and the hole diameter is 5mm. The injector as a whole can swing -20 to +30° relative to the horizontal direction, and the scanning frequency is 3Hz; the gas injection pressure is 0.4MPa, and the injector injection volume is 25m 3 / min, particle loading 720g / min.

[0083] (6) Before the second phase particles are added to the powder particle feeding mechanism, they need to be surface modified by ball milling 95% by mass SiC and 5% by mass medium manganese steel metal powder in liquid nitrogen for 30 h.

[0084] (7) The gas-solid two-phase flow fully disperses the alloy liquid flowing out of the pouring ingot into uniform droplets. The horizontal rotating disk on the top of the rotating disk and its lifting device is controlled to be 400 mm away from the lower end of the ejector. The ingot diameter is 420 mm. The rotating disk rotates at a speed of 80 r / min and descends at a speed of 70 mm / min. The surface molten pool depth is controlled to be 2 mm. The second vacuum pump group controls the negative pressure of the solidification environment to be 3000 Pa.

[0085] (8) After the ingot is sprayed, the top temperature is controlled below 1400°C and the bottom temperature is controlled below 1280°C. After the deposited ingot is taken out, it is sent to a forging holding furnace for 2 hours to even the temperature, and then forged into a square billet for rolling.

[0086] (9) The mass fraction of the second phase particles in the forging billet is 1.5%, the particle size is 200-800nm, and it is evenly distributed on the matrix alloy without grain boundary segregation. The wear life of the reinforced particles is increased by more than 30%, the macro hardness is increased by more than 20%, and the yield strength, tensile strength and impact energy are reduced by 1% compared with the non-second phase reinforced matrix.

[0087] Example 2

[0088] In this embodiment, a negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process includes the following steps:

[0089] (1) The ladle molten metal is 304 stainless steel (mass fraction): Mn 1.8%, C 0.06%, Si 0.4%, Cr20%, Ni 10%, S13ppm, P 0.006%, Fe balance. The second phase particles are B 4 C, the addition amount is 5wt%, and the particle size is 200-1000nm.

[0090] (2) The superheat of the alloy liquid is controlled to be higher than the melting point by 50°C, and the ladle is used for bottom blowing argon to remove slag and degassing. After the smelting is completed, large inclusions near the positive and negative tilting of the ladle are captured by the adsorption layer, and sampling and composition fine-tuning are completed, and preparation for pouring is made.

[0091] (3) The tundish compartment is opened, and the tundish preheated to 1200°C is placed in the tundish compartment. The bottom opening of the tundish is connected to the water inlet position of the pouring ingot. Then the sealing door of the tundish compartment is closed, and the first-stage vacuum pump group starts to evacuate the air to a pressure of 2×10 -2 Pa, at this time, the smelting chamber is filled with argon gas to 0.011MPa and then the inflation is stopped.

[0092] (4) The gate valve of the smelting chamber is opened, and the three chambers of the smelting chamber, the tundish chamber, and the deposition chamber are connected. The second vacuum pump group maintains the ambient pressure at 4000Pa, and the ladle is tilted for pouring. The liquid level reaches the set height of 280mm. According to the diameter of the spray deposition ingot of 450mm, two nozzles are configured with a diameter of and Flow rate is 50kg / min and 38kg / min, and the outlet flow rate is controlled at 1.2m / min.

[0093] (5) The nozzle is located in the middle of the ejector, the center line is aligned, the lower plane of the nozzle is parallel to the lower plane of the ejector, and the ejector slit width is 3mm. The ejector as a whole can swing -20 to +30° relative to the horizontal direction, and the scanning frequency is 4Hz; the gas injection pressure is 0.25MPa, and the ejection volume of the ejector is 22m 3 / min, particle loading 2400g / min.

[0094] (6) Before the second phase particles are added to the powder particle feeding mechanism, they need to be surface modified by adding 95% B 4 C and 304 stainless steel metal powder with a mass fraction of 5% and a particle size of 10-20 μm were ball-milled in liquid nitrogen for 30 h.

[0095] (7) The gas-solid two-phase flow fully disperses the alloy liquid flowing out of the pouring ingot into uniform droplets. The horizontal rotating disk at the top of the rotating disk and its lifting device is controlled to be 350 mm away from the lower end of the ejector. The ingot diameter is 440 mm. The rotating disk rotates at a speed of 50 r / min and descends at a speed of 72 mm / min. The surface molten pool depth is controlled to be 2 mm. The second vacuum pump group controls the negative pressure of the solidification environment to be 2000 Pa.

[0096] (8) After the ingot is sprayed, the top temperature is controlled below 1380°C and the bottom temperature is controlled below 1250°C. After the deposited ingot is taken out, it is sent to a forging holding furnace for 2 hours of equalization, and then forged into a square billet and rolled to 5 mm.

[0097] (9) The mass fraction of the second phase particles in the forging billet is 5%, the particle size is 200-1000nm, and it is evenly distributed on the matrix alloy without grain boundary segregation. The macroscopic hardness is increased by more than 20%, and the yield strength, tensile strength and impact energy are reduced by 1% compared with the non-second phase strengthened matrix.

[0098] Example 3

[0099] In this embodiment, a negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process includes the following steps:

[0100] (1) The ladle smelting alloy is bulletproof steel (mass fraction): Mn 0.5%, C 0.45%, Si 0.3%, Cr1%, Ni1.5%, Mo 0.3%, V 0.1%, S15ppm, P 0.004%, Fe balance. The second phase particles are SiC, the addition amount is 2wt%, and the particle size is 2-8μm.

[0101] (2) The superheat of the alloy liquid is controlled to be higher than the melting point of 80°C, and the ladle is used for bottom argon blowing to remove slag and degassing. After the smelting is completed, large inclusions near the positive and negative tilting of the ladle are captured by the adsorption layer, and sampling and composition fine-tuning are completed, and preparation for pouring is made.

[0102] (3) The tundish compartment is opened, and the tundish preheated to 1230℃ is placed in the tundish compartment. The bottom opening of the tundish is connected to the water inlet position of the pouring ingot. Then the sealing door of the tundish compartment is closed, and the first-stage vacuum pump group starts to evacuate the air to a pressure of 10 -2 Pa, at this time, the smelting chamber is filled with argon and then the inflation is stopped after the pressure reaches 0.016MPa.

[0103] (4) The gate valve of the smelting chamber is opened, and the three chambers of the smelting chamber, the tundish chamber, and the deposition chamber are connected. The second vacuum pump group maintains the ambient pressure at 3000Pa, and the ladle is tilted for pouring. The liquid level reaches the set height of 260mm. According to the diameter of the spray deposition ingot of 550mm, three nozzles are configured with a diameter of and The flow rates are 50kg / min, 38kg / min and 33kg / min, and the outlet flow rate is controlled at 1.1m / min.

[0104] (5) The nozzle is located in the middle of the injector, the center line is aligned, the lower plane of the nozzle is parallel to the lower plane of the injector, the number of holes in the injector is 18, and the hole diameter is 4mm. The injector as a whole can swing -20 to +30° relative to the horizontal direction, and the scanning frequency is 3Hz; the gas injection pressure is 0.45MPa, and the injection volume of the injector is 35m 3 / min, particle loading 820g / min.

[0105] (6) Before the second phase particles are added to the powder particle feeding mechanism, they need to be surface modified by liquid nitrogen ball milling 95% SiC and 5% bulletproof steel metal powder for 50 h;

[0106] (7) The gas-solid two-phase flow fully disperses the alloy liquid flowing out of the pouring ingot into uniform droplets. The horizontal rotating disk on the top of the rotating disk and its lifting device is controlled to be 350 mm away from the lower end of the ejector. The ingot diameter is 550 mm. The rotating disk rotates at a speed of 50 r / min and descends at a speed of 60 mm / min. The surface molten pool depth is controlled to be 2 mm. The second vacuum pump group controls the negative pressure of the solidification environment to be 3000 Pa.

[0107] (8) After the ingot is sprayed, the top temperature is controlled below 1400°C and the bottom temperature is controlled below 1280°C. After the deposited ingot is taken out, it is sent to a forging holding furnace for 2 hours of equalization, and then forged into a square billet and rolled to specifications of 2.5 mm and 12 mm.

[0108] (9) The mass fraction of the second phase particles in the forging billet is 2%, the particle size is 2000-8000nm, and it is evenly distributed on the matrix alloy without grain boundary segregation. The wear life of the reinforced particles is increased by more than 30%, the macro hardness is increased by 30%, and the yield strength, tensile strength and impact energy are reduced by 1% compared with the non-second phase reinforced matrix.

[0109] Example 4

[0110] In this embodiment, a negative pressure spray deposition process for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process includes the following steps:

[0111] (1) The ladle smelting alloy is a nickel-tin-copper alloy (mass fraction): Ni 15%, Sn 7%, and Cu balance. The second phase particles are SiC with an addition amount of 3wt% and a particle size of 200-800nm.

[0112] (2) The superheat of the alloy liquid is controlled to be higher than the melting point of 80°C, and the ladle is used for bottom argon blowing to remove slag and degassing. After the smelting is completed, large inclusions near the positive and negative tilting of the ladle are captured by the adsorption layer, and sampling and composition fine-tuning are completed, and preparation for pouring is made.

[0113] (3) The tundish compartment is opened, and the tundish preheated to 1100°C is placed in the tundish compartment. The bottom opening of the tundish is connected to the water inlet position of the pouring ingot. Then the sealing door of the tundish compartment is closed, and the first-stage vacuum pump group starts to evacuate the air to a pressure of 5×10 -2 Pa, at this time, the smelting chamber is filled with argon and then the filling is stopped after the pressure reaches 0.02MPa.

[0114] (4) The gate valve of the smelting chamber is opened, and the three chambers of the smelting chamber, the tundish chamber, and the deposition chamber are connected. The second vacuum pump group maintains the ambient pressure at 3000Pa, and the ladle is tilted for pouring. The liquid level reaches the set height of 200mm. According to the diameter of the spray deposition ingot of 420mm, two nozzles are configured with a diameter of and Flow rate is 50kg / min and 33kg / min, and the outlet flow rate is controlled at 1.1m / min.

[0115] (5) The nozzle is located in the middle of the injector, the center line is aligned, the lower plane of the nozzle is parallel to the lower plane of the injector, the number of holes in the injector is 20, and the hole diameter is 6mm. The injector as a whole can swing -20 to +30° relative to the horizontal direction, and the scanning frequency is 3Hz; the gas injection pressure is 0.4MPa, and the injection volume of the injector is 25m3 / min, particle loading 720g / min.

[0116] (6) Before the second phase particles are added to the powder particle feeding mechanism, they need to be surface modified by ball milling 95% by mass SiC and 5% by mass Ni-Sn-Cu metal powders in liquid nitrogen for 30 h.

[0117] (7) The gas-solid two-phase flow fully disperses the alloy liquid flowing out of the pouring ingot into uniform droplets. The horizontal rotating disk on the top of the rotating disk and its lifting device is controlled to be 300 mm away from the lower end of the ejector. The ingot diameter is 420 mm. The rotating disk rotates at a speed of 60 r / min and descends at a speed of 72 mm / min. The surface molten pool depth is controlled to be 3 mm. The second vacuum pump group controls the negative pressure of the solidification environment to be 3000 Pa.

[0118] (8) After the ingot is sprayed, the top temperature is controlled below 980°C and the bottom temperature is controlled below 880°C. After the deposited ingot is taken out, it is sent to a forging holding furnace for 2 hours of equalization, and then directly pierced and rolled into a tube.

[0119] (9) The mass fraction of the second phase particles in the forging billet is 3%, the particle size is 200-800nm, and it is evenly distributed on the matrix alloy without grain boundary segregation. The wear life of the reinforced particles is increased by more than 30%, the macro hardness is increased by more than 20%, and the yield strength, tensile strength and impact energy are reduced by 1% compared with the non-second phase reinforced matrix.

[0120] The implementation results show that the present invention is a comprehensive application process for rapid solidification by dispersing alloy liquid through gas-solid two-phase flow jet, and has great application value in the development of neutron shielding steel, ceramic-steel composite reinforced armor steel, super wear-resistant steel, high-strength and super-hard copper alloy, and oxide dispersion strengthened alloy.

Claims

1. A negative pressure spray deposition device for negative pressure assisted control of gas-solid two-phase flow to drive liquid phase rapid solidification process, characterized in that: The equipment includes a smelting chamber, a tundish chamber, a deposition chamber, an injection mechanism, and a two-stage vacuum system. The specific structure is as follows: The smelting chamber, the tundish chamber, and the sedimentation chamber are connected in sequence, and the two ends of the tundish chamber are respectively vertically connected to the smelting chamber and the sedimentation chamber, the smelting chamber is vertically upward relative to the tundish chamber, and the sedimentation chamber is vertically downward relative to the tundish chamber; one end of the tundish chamber extends into the smelting chamber, and a gate valve communicating with the inner cavity of the smelting chamber is arranged on the top of the end of the tundish chamber extending into the smelting chamber, a steel ladle is arranged in the smelting chamber, a tundish chamber sealing door is arranged at the top opening of the tundish chamber, the tundish is placed in the tundish chamber through the tundish chamber sealing door, and the inclination direction of the steel ladle corresponds to that of the tundish; The bottom opening at one end of the tundish corresponds to the bottom opening of the tundish chamber, a pouring ingot is provided at the bottom opening of the tundish chamber, the center hole of the pouring ingot is a water inlet vertically connected to the tundish and the bottom opening of the tundish chamber, a rotating disk and a lifting device thereof are provided at the lower part of the inner cavity of the sedimentation chamber, the rotating disk and the lifting device thereof are composed of a rotating disk and a lifting device, the output end of the lifting device is connected to the rotating disk through a vertical center axis, the injection mechanism is horizontally arranged at the upper part of the sedimentation chamber, and the upper part of the center hole of the injector of the injection mechanism corresponds to the water inlet, and the lower part of the nozzle on the injector corresponds to the rotating disk; The two-stage vacuum system is provided with a first-stage vacuum pump group and a second-stage vacuum pump group. The first-stage vacuum pump group is connected to the inner cavity of the smelting chamber through a pipeline, and the lower side of the deposition chamber is connected to the second-stage vacuum pump group through a pipeline.

2. The negative pressure spray deposition device for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process according to claim 1, characterized in that: The injection mechanism is provided with an air compressor, a powder particle feeding mechanism, a particle loader, a gas-solid two-phase flow interface, a cyclone filter component, an injector, a nozzle, and a drive motor. A drive motor is provided on one side of the injector, and the drive motor is connected to the injector through an output shaft, and the injector is independently controlled to swing by the drive motor; an air compressor, a powder particle feeding mechanism, a particle loader, a gas-solid two-phase flow interface, and a cyclone filter component are provided on the other side of the injector, and the outlet of the air compressor is connected to the inner cavity of the powder particle feeding mechanism, the gas-solid two-phase flow interface, and the cyclone filter component in sequence, and the cyclone filter component is connected to the inner cavity of the injector through a pipeline, and a particle loader is provided on the powder particle feeding mechanism, and the particle loader is connected to the inner cavity of the powder particle feeding mechanism; the injector is an annular structure, and the nozzle is located between the outer side of the center hole of the injector and the inner wall of the annular structure.

3. The negative pressure spray deposition device for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process according to claim 2, characterized in that: The upper part of the nozzle is an annular slit or a porous structure evenly distributed along the circumference. The annular slit or porous structure of the nozzle is connected to the inner cavity of the ejector. The lower end of the nozzle is an outward-expanding bell mouth. The lower plane of the nozzle is flush with the lower plane of the ejector. After the gas-solid two-phase flow enters the inner cavity of the ejector, it is output from the annular slit or porous structure of the nozzle.

4. The negative pressure spray deposition device for negative pressure assisted control of gas-solid two-phase flow driving liquid phase rapid solidification process according to claim 1, characterized in that: A first control valve is provided on the pipeline connecting the first-stage vacuum pump group with the inner cavity of the smelting chamber, and a second control valve, a solid phase particle cyclone separator and a third control valve are provided in sequence on the pipeline connecting the deposition chamber with the second-stage vacuum pump group.

5. A negative pressure spray deposition process using the negative pressure-assisted control of the gas-solid two-phase flow to drive the rapid solidification of the liquid phase according to any one of claims 1 to 4, characterized in that: The steps include: (1) The superheat of the base alloy liquid is controlled to be 40-120°C higher than the melting point, and the ladle is used for bottom argon blowing to remove slag and degassing. After the smelting is completed, large inclusions near the positive and negative tilting of the ladle are captured by the adsorption layer, and sampling and composition fine-tuning are completed, and pouring is ready; (2) Open the sealed door of the tundish cabin on the top of the tundish cabin, put the tundish preheated to above 1200°C into the tundish cabin, connect the bottom opening of the tundish with the water inlet of the pouring ingot, and then close the sealed door of the tundish cabin. The second-stage vacuum pump group starts to evacuate the air until the pressure is below 5000Pa. At this time, the protective gas is filled in the smelting cabin to 0.01-0.03MPa and then the filling is stopped; (3) The gate valve of the smelting chamber is opened, and the three chambers of the smelting chamber, the tundish chamber, and the deposition chamber are connected. The ambient pressure is maintained at ≤5000Pa by the second-stage vacuum pump group. The ladle is tilted for pouring. After the liquid level reaches the set height, it remains stable. The flow rate of the alloy liquid flowing through the water inlet of the pouring ingot is stable. (4) The nozzle is located in the middle of the ejector, the center lines are aligned, and the nozzle uses a porous structure or a slit to inject gas and solid phases; (5) The ejector is designed with one or two powder particle feeding mechanisms, which uniformly feed the particles into the high-speed airflow, thereby accurately loading the second phase particles into the alloy; after the particles are preheated to a temperature ≥ 600°C, they enter the powder particle feeding mechanism through the particle loader, and the powder feeding rate of the second phase particles with a particle size of 20 to 3000 nm is 100 to 1250 g / min; (6) The gas-solid two-phase flow fully disperses the alloy liquid flowing out of the water outlet of the pouring ingot into uniform droplets. The horizontal rotating disk at the top of the rotating disk and its lifting device is controlled to be 200-450 mm away from the lower end of the ejector, the ingot diameter is 200-850 mm, the rotating speed of the rotating disk is 40-200 r / min, the descending speed of the rotating disk is 50-200 mm / min, the surface molten pool depth is controlled to be 1-3 mm, and the second-stage vacuum pump group 18 controls the negative pressure of the solidification environment to be ≤5000 Pa; (7) Short process energy-saving process for forging after hot charging furnace equalization: After the deposition ingot is sprayed, the top temperature is controlled to be ≤(T s -100℃), bottom temperature control≤(T s -200℃), take out the deposited ingot and send it into a forging holding furnace for equalizing the temperature for 1 to 3 hours, and then forge it into a square billet or a round billet for subsequent processing and heat treatment.

6. The negative pressure spray deposition process for driving the rapid solidification of liquid phase by negative pressure assisted control of gas-solid two-phase flow according to claim 5, characterized in that: In step (1), the base alloy smelted in the ladle is various high-element addition alloys suitable for induction or resistance heating, and the base alloy includes: medium-high carbon steel, high-alloy steel, medium manganese steel, high manganese steel, high nitrogen stainless steel, nickel-tin-copper alloy, manganese-nickel-copper alloy or high-temperature alloy; the second phase particles are various functional particles, including silicon carbide, boron carbide, silicon dioxide, boron nitride, aluminum oxide, corundum, graphene, carbon nanotubes or graphite particles, the mass fraction of the second phase particles is 1-8%, and the particle size is controlled to be below 20 μm.

7. The negative pressure spray deposition process for driving the rapid solidification of liquid phase by negative pressure assisted control of gas-solid two-phase flow according to claim 5, characterized in that: In step (3), according to the diameter range of the spray deposition ingot, the number of nozzles is 1 to 3, and the diameter of each nozzle is The flow rate of each water nozzle is 10-80kg / min, the outlet flow rate of each water nozzle is controlled at 1-2m / min, the position of the water nozzle is opposite to different positions of the radius of the deposited ingot, and different flow rates are controlled by sizing the water nozzle size; when there are two water nozzles, the aperture area ratio of the water nozzle is controlled at 1:0.7-0.9; when there are three water nozzles, the aperture area ratio of the water nozzle is controlled at 1:0.7-0.9:0.6-0.

85.

8. The negative pressure spray deposition process for driving the rapid solidification of liquid phase by negative pressure assisted control of gas-solid two-phase flow according to claim 5, characterized in that: In step (4), when a porous structure is used to spray gas-solid two-phase, the number of holes on the nozzle of the injector is 10 to 20, and the aperture is 4 to 8 mm; or, when a slit is used to spray gas-solid two-phase, an annular slit is designed on the nozzle of the injector, and the slit width is controlled to be 2 to 4 mm; the injector as a whole swings -40° to +40° relative to the horizontal direction, and the scanning frequency is 0 to 10 Hz; the gas injection pressure is 0.2 to 0.7 MPa, and the injection volume of the injector 22 is 5 to 40 m 3 / min, particle loading amount 0~2500g / min.

9. The negative pressure spray deposition process for driving the rapid solidification of liquid phase by negative pressure assisted control of gas-solid two-phase flow according to claim 5, characterized in that: In step (5), the second phase particles need to be surface modified before being added to the powder particle feeding mechanism, and the surface modification method includes low-temperature ball milling with the base metal powder, pickling or evaporation method; when the second phase particles and the base metal powder are subjected to low-temperature ball milling, the second phase particles are ball-milled and mixed with the base metal powder in liquid nitrogen, the mass fraction of the second phase particles is more than 95%, and the grinding ball material is super S280 stainless steel; wherein the second phase particle diameter is less than 20 μm, the base metal powder particle diameter used for modification is 0.5 to 30 μm, and the ball milling time is more than 24 hours.

10. The negative pressure spray deposition process for driving liquid phase rapid solidification by negative pressure assisted control of gas-solid two-phase flow according to claim 5, characterized in that: In step (6), a gas-solid two-phase flow is used to drive the liquid phase, and the gas phase and the solid phase are used as cooling media, and the ratio of gas-solid consumption of solidification latent heat is 1:1.5-3; after the injection is completed, the number of pores counted on the solidified end surface of the deposited ingot is ≤5 / 10mm 2 , and the pore diameter is ≤2μm, and all the pores are pressed together after forging.

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