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CN-121976187-A - Be used for SCO2Device and method for preparing environment laser cladding high-aluminum gradient coating

CN121976187ACN 121976187 ACN121976187 ACN 121976187ACN-121976187-A

Abstract

The invention relates to a preparation device and a preparation method for a laser cladding high-aluminum gradient coating in an SCO 2 environment, wherein the preparation device comprises a composite processing head assembly, a driving structure, a lifting workbench, an in-situ monitoring assembly and a central control system, the composite processing head assembly comprises a laser cladding head with a nozzle, an inner area induction coil and an outer area induction coil, the laser cladding head is used for depositing the gradient coating on the surface of a workpiece, the inner area induction coil and the outer area induction coil are arranged on the periphery of the laser cladding head, the gradient powder feeding assembly comprises a plurality of powder feeding pipes, the powder feeding pipes are respectively communicated with the laser cladding head, and the central control system is respectively and electrically connected with the laser cladding head, the gradient powder feeding assembly and the in-situ detection assembly. The device can obviously inhibit the formation of metallurgical defects such as air holes, unfused and the like by means of gradient preheating and gradient coating, so that the prepared gradient coating has excellent corrosion resistance, high surface hardness and good wear resistance in an SCO 2 environment.

Inventors

  • WU GUOLONG
  • ZHU JUNJIE
  • YAO JIANHUA

Assignees

  • 浙江工业大学

Dates

Publication Date
20260505
Application Date
20260310

Claims (10)

  1. 1. A preparation device for a laser cladding high-aluminum gradient coating in an SCO 2 environment is characterized by comprising a composite processing head assembly (1), a driving structure (2) for driving the composite processing head assembly (1), a liftable workbench (3) for placing a workpiece (17), an in-situ monitoring assembly and a central control system, wherein the composite processing head assembly (1) comprises a laser cladding head (11) with a nozzle (14), an inner area induction coil (15) and an outer area induction coil (16), the laser cladding head (11) is used for depositing a gradient coating on the surface of the workpiece (17), the inner area induction coil (15) and the outer area induction coil (16) are arranged on the periphery of the laser cladding head (11) to form radial temperature gradients on the surface of the workpiece (17), the gradient powder feeding assembly comprises a plurality of powder feeding pipes (13), the powder feeding pipes (13) are respectively communicated with the laser cladding head (11) and are respectively communicated with the laser cladding head (11) to be used for conveying different Al content gradients in a cladding process, and the central control system is respectively connected with the laser cladding head (11) and the in-situ monitoring assembly and the gradient powder feeding assembly is used for synchronously carrying the laser cladding process and the gradient control assembly.
  2. 2. The preparation device of the laser cladding high-aluminum gradient coating for the SCO 2 environment, which is disclosed in claim 1, is characterized in that a baffle (4) is arranged outside the composite processing head assembly (1).
  3. 3. The device for preparing the laser cladding high-aluminum gradient coating for the SCO 2 environment, which is characterized by further comprising an outer region driving assembly for driving and adjusting the angle of the outer region induction coil (16), wherein the outer region driving assembly comprises an outer region telescopic push rod (5), a pair of outer region bevel gears (6) and an outer region servo motor (7), the pair of outer region bevel gears (6) are arranged between the outer region servo motor (7) and the outer region telescopic push rod (5), and the outer region induction coil (16) is arranged at the end part of the outer region telescopic push rod (5).
  4. 4. The device for preparing the laser cladding high-aluminum gradient coating in the SCO 2 environment according to claim 3, further comprising an inner zone driving component for driving and adjusting the inner zone induction coil (15), wherein the inner zone driving component comprises an inner zone servo motor (8), an inner zone telescopic push rod (9) and a pair of inner zone bevel gears (10), the pair of inner zone bevel gears (10) are arranged between the inner zone servo motor (8) and the inner zone telescopic push rod (9), and the inner zone induction coil (15) is arranged at the end part of the inner zone telescopic push rod (9).
  5. 5. The device for preparing the laser cladding high-aluminum gradient coating for the SCO 2 environment according to claim 1, wherein the driving structure (2) is a five-axis robot.
  6. 6. The device for preparing the laser cladding high-aluminum gradient coating in the SCO 2 environment according to claim 1, wherein a plurality of powder feeding pipes (13) are distributed at equal intervals along the circumferential direction of the laser cladding head (11).
  7. 7. The preparation device for the laser cladding high-aluminum gradient coating in the SCO 2 environment is characterized in that at least three powder feeding pipes (13) are arranged, each powder feeding pipe (13) is connected with an independent powder bin, and the powder bins are used for filling Fe-20Cr-5Al powder, fe-20Cr-7Al powder and Fe-20Cr-9Al powder respectively, and yttrium element is added into the Fe-20Cr-5Al powder.
  8. 8. The apparatus of claim 1, wherein the in-situ monitoring assembly comprises a thermal imager (12), and a plurality of the thermal imagers (12) are respectively installed near the laser cladding head (11), the inner area induction coil (15) and the outer area induction coil (16) for real-time monitoring of coating and bath temperature and synchronous feedback of acquired information to the central control system.
  9. 9. The preparation device for the laser cladding high-aluminum gradient coating in the SCO 2 environment is characterized in that the frequency of the outer region induction coil (16) is 100kHz, the working temperature is 300 ℃ and the device is used for deep preheating of a substrate or a low-Al coating, the inner region induction coil (15) is subjected to focusing induction heating at high frequency 300kHz, the working temperature is 200 ℃, and the region to be clad is subjected to shallow heating.
  10. 10. A method for preparing a laser cladding high-aluminum gradient coating for an SCO 2 environment, which is provided with a laser cladding high-aluminum gradient coating preparation device for an SCO 2 environment according to any one of claims 1 to 9; the method is characterized by comprising the following steps of S1, polishing a surface to be processed of a workpiece (17), S2, carrying out gradient preheating on a substrate and a coating through a laser cladding head (11), an inner area induction coil (15) and an outer area induction coil (16), carrying out deep preheating on the substrate or a low Al coating by the outer area induction coil (16), carrying out shallow heating on the area to be clad by the inner area induction coil (15) to reduce the cooling rate of a molten pool, S3, synchronously carrying out laser cladding, opening a laser and rare gas protection, controlling a multichannel gradient powder feeding device by a central control system, dynamically adjusting powder feeding proportion of different gradient powders in the laser cladding process to realize uniform gradient transition from the substrate and the low Al content coating to the high Al coating, S4, wherein the laser power of the laser is 1500W, the scanning line speed is 10mm/min, the powder feeding rate is 10g/min, the thickness of a deposition layer is 0.5-0.8mm after single cladding, S5, the selected cladding material is Fe-Cr-Al gradient powder, the particle size of Fe-150 mu m, the Al gradient is 0.5-20 wt.% and the balance of Fe-20 wt.% and the Fe-20 wt.% is used as the transition powder, and the chemical grade of the Fe-20 wt.% is used as the transition powder, and the chemical grade is 20wt.% of the Fe-20 wt.% of the transition powder, the balance of Fe, fe-20Cr-9Al powder as an outermost protective layer, wherein the chemical components and mass fraction of the powder are 9wt.% Al,20wt.% Cr and the balance of Fe.

Description

Device and method for preparing laser cladding high-aluminum gradient coating in SCO 2 environment Technical Field The invention belongs to the technical field of laser cladding, is suitable for laser cladding of surface protection of critical components of a supercritical carbon dioxide nuclear power circulation system, and particularly relates to a device and a method for preparing a laser cladding high-aluminum gradient coating in an SCO 2 environment. Background Along with the acceleration of the 'double carbon' strategy in China, the carbon dioxide sealing and storing target exceeds 10 hundred million tons, and related equipment is exploded. In the fourth generation nuclear energy system, the supercritical carbon dioxide (SCO 2) Brayton cycle system is taken as a representative of the next generation advanced power cycle technology, and is regarded as an energy conversion scheme with great application potential because of the remarkable advantages of high working medium density, high heat efficiency, good system compactness and the like. The system can operate under the high temperature above 620 ℃ and the high pressure condition above 20MPa, compared with the traditional steam Rankine cycle, the heat efficiency can be improved by 30% -50%, and the equipment volume can be reduced by more than 80%. However, the extreme environment of high temperature and high pressure created by the SCO 2 cycle system when operating, presents a significant challenge to critical component materials. Under the working condition, the traditional stainless steel, nickel-based alloy and other materials face serious problems of uniform corrosion, oxidation corrosion and flow acceleration corrosion. Research shows that in the SCO 2 environment with the temperature of 600 ℃ per 25MPa, the annual corrosion depth of 316L stainless steel can reach hundreds of micrometers, so that key components (such as turbine blades, heat exchanger pipelines, valve sealing surfaces and the like) are rapidly failed, and the long-term safe and stable operation of the system is seriously restricted. Therefore, there is a need to develop surface protection techniques with excellent SCO 2 corrosion resistance to extend critical component service life and reduce annual losses. Among the surface engineering technologies, the laser cladding technology becomes an ideal choice for preparing high-performance anti-corrosion coating by virtue of the remarkable advantages of high energy density, small heat affected zone, good metallurgical bonding with a matrix and the like. According to the technology, the metal powder which is synchronously conveyed is melted through a high-energy laser beam, the material characteristics of different cladding materials are adapted by changing laser process parameters, and a compact cladding layer is formed on the surface of a base material layer by layer in a deposition mode, so that excellent corrosion resistance, abrasion resistance and high-temperature oxidation resistance are achieved. However, due to the inherent characteristics of the laser cladding technology, the molten pool generates a strong stirring effect and rapid cooling characteristic in the cladding process, and air hole defects are extremely easy to form. Secondly, because of the rapid heating and cooling processes, the defects of uneven shrinkage of a molten pool, easy crack generation and the like caused by larger temperature gradient exist. The presence of these internal defects becomes a preferential permeation path for corrosive media into the interior of the deposit, destroying the integrity of the deposit, and more severely reducing the oxidation and corrosion resistance of the component, with the risk of premature failure in the extreme environment of supercritical carbon dioxide. Substrate preheating is an important means of regulating the laser cladding thermal process. Related studies have shown that preheating the substrate/workpiece during deposition can reduce thermal stresses generated during deposition, ultimately reducing or eliminating spalling and cracking therefrom, and that the technique is widely used in a variety of applications such as joining, welding and laser fused deposition, and that the required laser power can be reduced by preheating the substrate and coating in advance to reduce the input of laser energy thereto. In addition, it has also been found that substrate temperature is a critical factor affecting coating dilution. In summary, single laser cladding has difficulty in solving the core problems of defects and residual stresses within the deposited layer. Therefore, a new manufacturing technology needs to be developed, a gradient preheating device matched with the gradient preheating device is designed aiming at the cladding gradient material, the gradient preheating and the gradient cladding can be integrated in space and time, the microstructure and the mechanical property of a deposition layer are actively optimized,