Laser additive remanufacturing process for repairing compressor components

Abstract

The application belongs to the technical field of metal material plating, and particularly relates to a laser additive remanufacturing process for repairing compressor accessories. The process comprises the following steps: surface treatment of nano silicon carbide, installation of a titanium target and a nickel target in a magnetron sputtering system for gradient deposition, annealing and sieving after deposition to obtain Ti / Ni gradient composite silicon carbide, grinding of nickel-based high-temperature alloy, gadolinium oxide and hexagonal boron nitride in a grinding medium, mixing of the Ti / Ni gradient composite silicon carbide after grinding, drying to obtain composite ceramic reinforced high-temperature alloy powder, laser additive remanufacturing of the repair area of the compressor accessory to obtain the repaired compressor accessory. The nickel and titanium are gradiently combined on the surface of the silicon carbide, and then the composite ceramic reinforced high-temperature alloy powder is prepared, so that the problems of poor interface fusion performance, easy loss of molten pool and easy precipitation of brittle phase in the existing laser additive repair are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material plating, and in particular relates to a laser additive remanufacturing process for repairing compressor accessories. Background Art

[0002] Turbine compressors (e.g., centrifugal and axial flow) and screw compressors are essential equipment in the energy and chemical industries. Their impellers, rotors, journals, and sealing surfaces are subject to long-term operation in high-temperature, high-pressure, and high-speed environments. This can lead to failures such as cavitation, particle erosion wear, alternating stress accumulation, and eccentric wear. In severe cases, these failures can cause surge and damage the compressor. Particle erosion and cavitation can cause regional honeycomb-like pits on the component surface, often located on complex curved surfaces, requiring precise filling to restore the flow path profile. Alternating stress accumulation can cause fatigue cracks in stress concentration areas, requiring stress relief. Eccentric wear can lead to subtle errors in roundness and cylindricity, requiring high repair precision. Traditional repair methods, such as arc cladding / submerged arc welding, thermal spraying, brush plating, and even complete replacement, all suffer from limited application scenarios, low repair accuracy, insufficient performance after repair, additional thermal damage, and long repair times and costs.

[0003] Laser additive manufacturing is gaining increasing attention due to its high repair accuracy and adaptability to complex curved surfaces; its small heat-affected zone, which avoids damage to the substrate; its wide range of material choices for the repair layer, which generally outperforms the substrate after repair; its adaptability to a variety of failure modes and wide repair coverage; and its high material utilization, simple repair process, and significant economic benefits. The quality of laser additive repair depends primarily on the synergy of four key dimensions: material compatibility, process stability, stress control, and performance regulation. Materials are a key component of this, so researchers are hoping to develop a new alloy material with good interface fusion during laser cladding, a molten pool that is less prone to instability (keyhole collapse and Marangoni convection), a brittle phase that is less likely to precipitate, and low residual stress and interlayer defects after laser cladding.

[0004] Chinese patent CN105671410A discloses a ceramic alloy powder, which is composed of alloy powder and a ceramic hard phase. The alloy powder is composed of the following components in percentage by weight: 5-8% calcium fluoride, 8-12% boron, 3-5% lanthanum oxide, and 15-25% silicon nitride; the ceramic hard phase is a mixture of tungsten carbide and titanium carbide.

[0005] In this patent, boron has a strong affinity with oxygen and is prone to forming boron oxides. Lanthanum oxide is also added to the patent, and the two compete for oxygen, resulting in the formation of a La-BO transition phase (such as LaBO3) rather than a pure deoxidation product. The La-BO transition phase is often more brittle, and microcracks are easily formed and expanded under alternating stress.

[0006] Chinese patent CN103350224A discloses a nickel-based cermet alloy powder, which, by weight, comprises 10-11% tungsten carbide, 0.2-0.4% carbon, 4-6% calcium fluoride, 2-4% silicon nitride, 3-5% boron, 0.6-1.0% vanadium, 11-14% molybdenum, 1.0-1.4% silicon, 15-18% chromium, and the balance nickel. The preferred composition of the nickel-based cermet alloy powder specifically for crankshaft laser cladding is 10% tungsten carbide, 0.3% carbon, 5% calcium fluoride, 3% silicon nitride, 4% boron, 0.8% vanadium, 13% molybdenum, 1.2% silicon, 16% chromium, and the balance nickel.

[0007] In this patent, the thermal expansion coefficients of silicon nitride, tungsten carbide ceramic phases and nickel metal matrix are quite different. During the rapid heating and cooling process of laser additive manufacturing, thermal stress accumulation is easily formed at the interface between the ceramic phase and the nickel metal matrix, and long-term use will affect the bonding strength of the cladding layer. Summary of the Invention

[0008] The purpose of the present invention is to provide a laser additive remanufacturing process for repairing compressor accessories, so as to solve the problems of poor interface fusion performance, easy instability of the molten pool and easy precipitation of brittle phases during existing laser additive repair.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] The laser additive remanufacturing process for repairing compressor parts according to the present invention comprises the following steps:

[0011] S1, treating the surface of nano-silicon carbide for standby use;

[0012] S2. Installing nano-silicon carbide, a titanium target, and a nickel target in a magnetron sputtering system to perform gradient deposition on nano-silicon carbide; after the deposition is completed, annealing and screening are performed to obtain Ti / Ni gradient composite silicon carbide;

[0013] S3, nickel-based high-temperature alloy, gadolinium oxide and hexagonal boron nitride are ground in a grinding medium, and after grinding, mixed with Ti / Ni gradient composite silicon carbide, and dried to obtain composite ceramic reinforced high-temperature alloy powder;

[0014] S4. Clean the compressor parts, detect defects in the compressor parts, determine the area to be repaired, model the area to be repaired, and generate a repair model; according to the repair model, use composite ceramic reinforced high-temperature alloy powder for laser additive remanufacturing to obtain the repaired compressor parts.

[0015] in:

[0016] In the S1, the particle size of the nano-silicon carbide is 50-100 nm. During the surface treatment, the nano-silicon carbide is first placed in a 10-15 wt% hydrogen fluoride aqueous solution and stirred and washed for 5-10 minutes; then placed in a 35-45 wt% ethanol aqueous solution and stirred and washed for 20-30 minutes. After centrifugation, the nano-silicon carbide is dried at 85-95°C to constant weight to complete the surface treatment operation.

[0017] In the above-mentioned S2, the magnetron sputtering system includes a vacuum chamber, which includes a fluidized bed sputtering chamber; the installation process is to symmetrically install a titanium target and a nickel target on both sides of the fluidized bed sputtering chamber; the titanium target has a purity of 99.9wt% and a diameter of 40-50mm; the nickel target has a purity of 99.9wt% and a diameter of 40-50mm; nano-silicon carbide is placed in the sample area at the center of the fluidized bed sputtering chamber, so that the target surface of the titanium target and the nickel target is 10-15cm away from the sample area; the vacuum chamber is evacuated to a basic vacuum, and the basic vacuum is ≤5×10 -4 MPa; argon gas was introduced into the fluidized bed sputtering chamber at a flow rate of 8~10sccm.

[0018] In the above-mentioned S2, the gradient deposition comprises the following steps:

[0019] (1) First, the first sputtering is performed, with only the titanium target turned on, where the sputtering power of the titanium target is 190~210W;

[0020] (2) Then, a second sputtering is performed. In the first 1 / 3 of the second sputtering, the sputtering power of the titanium target is uniformly reduced from 190~210W to 90~110W, and the sputtering power of the nickel target is uniformly increased from 0W to 50~70W; in the middle 1 / 3 of the second sputtering, the sputtering power of the titanium target is uniformly reduced from 90~110W to 50~70W, and the sputtering power of the nickel target is uniformly increased from 50~70W to 110~130W; in the last 1 / 3 of the second sputtering, the sputtering power of the titanium target is uniformly reduced from 50~70W to 0W, and the sputtering power of the nickel target is uniformly increased from 110~130W to 220~240W;

[0021] (3) Finally, the third sputtering is performed, with only the nickel target turned on, where the sputtering power of the nickel target is 240~260W, to complete the gradient deposition operation.

[0022] The working pressure of the first sputtering is 0.3~0.5Pa, and the first sputtering time is 9~12min; the working pressure of the second sputtering is 0.3~0.5Pa, and the second sputtering time is 15~18min; the working pressure of the third sputtering is 0.3~0.5Pa, and the third sputtering time is 12~16min.

[0023] In the above-mentioned S2, nitrogen is introduced during annealing, the nitrogen pressure is 0.15-0.25 MPa, the annealing temperature is 400-480° C., and the annealing holding time is 1-2 h.

[0024] In the above-mentioned S3, a planetary ball mill is used for grinding, and the planetary ball mill includes a ball milling jar and grinding balls; the grinding medium is anhydrous ethanol; and the nickel-based high-temperature alloy is GH4169 nickel-based high-temperature alloy.

[0025] The ratio of the total mass of the grinding balls to the total mass of the nickel-based high-temperature alloy, gadolinium oxide, and hexagonal boron nitride is 10-15:1; the volume of the grinding medium accounts for 25-35% of the volume of the ball mill; the grinding includes a first grinding and a second grinding, the first grinding speed is 150-200 rpm, the first grinding time is 40-50 minutes; the second grinding speed is 320-360 rpm, the second grinding time is 15-25 minutes, and the drying temperature is 75-85°C.

[0026] In the S3, when mixed, the mass ratio of Ti / Ni gradient composite silicon carbide, nickel-based high-temperature alloy, gadolinium oxide and hexagonal boron nitride is 100:(700~800):(4.5~6):(15~18).

[0027] In the above-mentioned S4, during cleaning, ultrasonic cleaning is first performed at 40 kHz for 15 minutes, and then polished with 240-mesh sandpaper.

[0028] In the S4 described above, during laser additive manufacturing, a fiber laser and a coaxial powder feeding system are used. When the defect depth is <1 mm, the laser power of the fiber laser is 290~300 W. When the defect depth is ≥1 mm, the laser power of the fiber laser is 450~470 W, and the scanning speed is 10.5~11.5 mm / s; the powder feeding amount of the coaxial powder feeding system is 11.5~13.5 g / min; and the protective gas is high-purity argon with an inlet flow rate of 15~25 L / min.

[0029] Gadolinium oxide is abbreviated as Gd2O3, hexagonal boron nitride is abbreviated as h-BN, and nano-silicon carbide is abbreviated as SiC.

[0030] In S2, annealing further eliminates internal stress accumulated during sputtering due to the difference in thermal expansion coefficients between the coating and SiC. It also promotes diffusion reactions at the Ti-SiC interface, further strengthening the bonding strength and inhibiting the excessive formation of brittle phases in the Ni-Ti layer. Anhydrous ethanol is added as a grinding medium to prevent powder splashing and excessive heating.

[0031] Marangoni convection occurs when uneven temperature distribution within the melt pool triggers surface tension gradients, causing spattering or spheroidization. Keyhole collapse occurs when the depth-to-width ratio of the melt pool is too large, leading to an imbalance between steam recoil pressure and surface tension, causing the keyhole to collapse and form pores.

[0032] The beneficial effects of the present invention are as follows:

[0033] The present invention uses h-BN nanosheets, which have excellent lubricity, high thermal conductivity, thermal stability, adsorption and a layered elastic structure; the present invention performs gradient coating on nano-silicon carbide to prepare nano-Ti / Ni gradient composite silicon carbide, which is divided into an outer layer, a transition layer, an inner layer and nano-SiC. During laser cladding, the outer layer has a high Ni content and excellent compatibility with the GH4169 nickel-based alloy, effectively improving surface bonding while reducing interfacial tension. The low interfacial tension allows the h-BN nanosheets to be evenly distributed between the nano-Ti / Ni gradient composite silicon carbide and the GH4169 nickel-based superalloy powder. Leveraging the high thermal conductivity of the h-BN nanosheets, they can rapidly release accumulated thermal energy, inhibit keyhole collapse and Marangoni convection, and prevent melt pool instability. The transition layer exhibits a relatively linear Ni:Ti gradient, which avoids interfacial stress concentration caused by sudden changes in the thermal expansion coefficients between SiC, the GH4169 nickel-based alloy, and the metal substrate, resulting in low residual stress and defects after cladding. The inner layer has a high Ti content, and the SiC reacts with the inner Ti layer at high temperatures to form a TiC / Ti5Si3 nanoceramic phase. This nanoceramic phase has high hardness, which can form a pinning effect, inhibit crack propagation, and prevent the precipitation of brittle phases.

[0034] Due to its excellent lubricity, h-BN nanosheets can act as a lubricant during cladding, reducing inter-particle friction and promoting the uniform dispersion of Ti / Ni gradient composite silicon carbide, GH4169 nickel-based high-temperature alloy powder, and Gd2O3 in the molten pool, thus avoiding poor fusion caused by agglomeration. At the same time, during the cooling and shrinkage period of laser cladding, the layered elastic structure of h-BN nanosheets is utilized to release residual stress through plastic deformation and interlayer slip, thereby reducing the generation of cracks and interlayer defects.

[0035] Gd2O3 acts as a strong deoxidizer, and its Gd preferentially combines with free oxygen to form Gd-O clusters, reducing the oxygen vacancy concentration and avoiding grain boundary embrittlement caused by vacancy aggregation; at the same time, it reduces the gas content in the molten pool and avoids splashing or collapse of the molten pool caused by bubble disturbance; h-BN nanosheets have strong adsorption properties and can serve as heterogeneous nucleation sites to refine grains; and the Gd formed by the decomposition of Gd2O3 is adsorbed on the h-BN nanosheets. The two work together to reduce the grain boundary energy through pinning-adsorption, thereby inhibiting the precipitation of brittle phases along the grain boundaries.

[0036] The GH4169 nickel-based high-temperature alloy powder with the highest content can provide a high-toughness base as a repair substrate. At the same time, it is easier to form cellular substructures and twins during rapid cooling. The cellular substructure presets high-density dislocations, providing sites for the subsequent pinning of the TiC / Ti5Si3 nanoceramic phase of nano-SiC. DETAILED DESCRIPTION

[0037] The present invention will be specifically described and illustrated below with reference to the embodiments.

[0038] The raw materials and equipment used in the following examples and comparative examples are all commercially available products. Some of the raw material manufacturers are as follows: GH4169 nickel-based high-temperature alloy powder, micron-grade, was provided by AVIC Mate Powder Metallurgy Technology (Beijing) Co., Ltd.; nano-SiC was provided by Shanghai Yaotian New Materials Technology Co., Ltd.; Gd2O3 powder, micron-grade, was provided by Xi'an Fangke New Materials Technology Co., Ltd.; h-BN nanosheets were provided by Xi'an Qiyue Biological.

[0039] Example 1

[0040] 1. Preparation of composite ceramic reinforced high temperature alloy powder

[0041] Weigh 7350 g of GH4169 nickel-based high-temperature alloy powder, 50 g of Gd2O3 powder and 165 g of h-BN nanosheets for later use.

[0042] Nano-SiC with a particle size of 75 nm was added to a 13.5 wt% hydrogen fluoride aqueous solution and stirred for 8 minutes; then placed in a 40 wt% ethanol aqueous solution and stirred for 25 minutes, centrifuged and dried at 90°C to constant weight.

[0043] A magnetron sputtering system was selected, which included a vacuum chamber, which included a fluidized bed sputtering chamber. A titanium target and a nickel target were symmetrically installed on both sides of the fluidized bed sputtering chamber. The titanium target had a purity of 99.9 wt% and a diameter of 45 mm. The nickel target had a purity of 99.9 wt% and a diameter of 45 mm. Nano-SiC was placed in the sample area at the center of the fluidized bed sputtering chamber, with the target surfaces of the titanium target and the nickel target 12 cm away from the sample area. The molecular pump was started and the vacuum chamber was evacuated to a basic vacuum (i.e., ≤5×10 -4 MPa); turn on the bottom airflow device and introduce argon into the fluidized bed sputtering chamber at a flow rate of 9 sccm.

[0044] First, the first sputtering was carried out, with only the titanium target turned on, where the sputtering power of the titanium target was 200W, the working pressure was 0.4Pa, and the sputtering time was 10min. Then a second sputtering was carried out, where the working pressure was 0.4Pa and the sputtering time was 16min. In the first 1 / 3 of the second sputtering time, the sputtering power of the titanium target was uniformly reduced from 200W to 100W, and the sputtering power of the nickel target was uniformly increased from 0W to 60W; in the middle 1 / 3 of the time, the sputtering power of the titanium target was uniformly reduced from 100W to 60W, and the sputtering power of the nickel target was uniformly increased from 60W to 120W; in the last 1 / 3 of the time, the sputtering power of the titanium target was uniformly reduced from 60W to 0W, and the sputtering power of the nickel target was uniformly increased from 120W to 230W. Finally, the third sputtering was performed, with only the nickel target turned on, where the sputtering power of the nickel target was 250 W, the working pressure was 0.4 Pa, and the sputtering time was 15 minutes to complete the gradient deposition.

[0045] The gradient deposited nano-SiC was transferred to a tube furnace, nitrogen was introduced, and the temperature was raised to 430° C. in a nitrogen atmosphere of 0.2 MPa for annealing. The temperature was kept for 1.5 hours and the furnace was cooled. After sieving, Ti / Ni gradient composite silicon carbide was obtained.

[0046] A planetary ball mill was selected, which was equipped with a ball mill and grinding balls. The diameters of the grinding balls were 5 mm and 10 mm, and the number ratio of the two was 1:1. The grinding balls and the weighed GH4169 nickel-based high-temperature alloy powder, Gd2O3 powder and h-BN nanosheets were added to the ball mill at a ball-to-material ratio (i.e., the ratio of the total mass of the grinding balls to the total mass of the material) of 12:1. Anhydrous ethanol was then added, with the volume of anhydrous ethanol accounting for 30% of the volume of the ball mill. The ball mill was sealed and the speed was set to 180 rpm for the first grinding, and the grinding time was 45 minutes; then the speed was increased to 340 rpm for the second grinding, and the grinding time was 20 minutes; finally, all the materials were taken out and mixed with 1000 g of Ti / Ni gradient composite silicon carbide, and dried at 82°C to constant weight to obtain composite ceramic reinforced high-temperature alloy powder.

[0047] 2. Laser additive manufacturing process

[0048] The impeller was disassembled from the compressor rotor assembly, and the surface dust was blown off with high-pressure air. The impeller was ultrasonically cleaned at 40kHz for 15 minutes. The impeller was polished with 240-grit aluminum oxide sandpaper to remove the surface oxide layer.

[0049] Industrial CT scanning was used to obtain the three-dimensional data of the entire impeller, focusing on identifying the location, depth, and distribution range of the pits. Penetrant testing (PT) was combined to confirm the pit boundaries and mark the target areas for repair. A total of 9 areas were selected, each 15 cm thick. 2, marked as areas 1 to 9. Fix the impeller on the workbench and position it through the positioning reference holes.

[0050] The area to be repaired (areas 1-9) was modeled using three-dimensional reverse engineering software (Geomagic) to generate a repair model, which was then entered into additive path planning software (Materialise Magics). A fiber laser and a coaxial powder feeding system were used, with the fiber laser power set to 293 W (for defect depths <1 mm) or 462 W (for defect depths ≥1 mm). The scanning speed was 11 mm / s, and the powder feeding rate of the coaxial powder feeding system was 12.5 g / min. High-purity argon was used as the protective gas at a flow rate of 20 L / min. Laser additive repair was performed, and the composite ceramic-reinforced high-temperature alloy powder obtained in Example 1 was used to repair area 1. Finally, surface shaping was performed to obtain a repaired compressor component.

[0051] Example 2

[0052] 1. Preparation of composite ceramic reinforced high temperature alloy powder

[0053] Weigh 8000 g of GH4169 nickel-based high-temperature alloy powder, 60 g of Gd2O3 powder and 180 g of h-BN nanosheets for later use.

[0054] Nano-SiC with a particle size of 50 nm was added to a 10 wt% hydrogen fluoride aqueous solution and stirred for 10 minutes; then placed in a 45 wt% ethanol aqueous solution and stirred for 20 minutes, centrifuged and dried at 85°C to constant weight.

[0055] A magnetron sputtering system was selected, which included a vacuum chamber, which included a fluidized bed sputtering chamber. A titanium target and a nickel target were symmetrically installed on both sides of the fluidized bed sputtering chamber. The titanium target had a purity of 99.9 wt% and a diameter of 50 mm. The nickel target had a purity of 99.9 wt% and a diameter of 50 mm. Nano-SiC was placed in the sample area at the center of the fluidized bed sputtering chamber, with the target surfaces of the titanium target and the nickel target 15 cm away from the sample area. The molecular pump was started and the vacuum chamber was evacuated to a basic vacuum (i.e., ≤5×10 -4 MPa); turn on the bottom airflow device and introduce argon into the fluidized bed sputtering chamber at a flow rate of 10 sccm.

[0056] First, the first sputtering was carried out, with only the titanium target turned on, where the sputtering power of the titanium target was 190W, the working pressure was 0.3Pa, and the first sputtering time was 12min. Then the second sputtering was carried out, with the working pressure being 0.3Pa and the sputtering time being 18min. In the first 1 / 3 of the second sputtering time, the sputtering power of the titanium target was uniformly reduced from 190W to 90W, and the sputtering power of the nickel target was uniformly increased from 0W to 50W; in the middle 1 / 3 of the time, the sputtering power of the titanium target was uniformly reduced from 90W to 50W, and the sputtering power of the nickel target was uniformly increased from 50W to 110W; in the last 1 / 3 of the time, the sputtering power of the titanium target was uniformly reduced from 50W to 0W, and the sputtering power of the nickel target was uniformly increased from 110W to 220W. Finally, the third sputtering was performed, with only the nickel target turned on. The sputtering power of the nickel target was 240 W, the working pressure was 0.3 Pa, and the third sputtering time was 16 minutes to complete the gradient deposition.

[0057] The gradient deposited nano-SiC was transferred to a tube furnace, nitrogen was introduced, and the temperature was raised to 480°C in a nitrogen atmosphere of 0.15 MPa for annealing, kept warm for 2 hours, and cooled with the furnace; after sieving, Ti / Ni gradient composite silicon carbide was obtained.

[0058] A planetary ball mill was selected, which was equipped with a ball mill and grinding balls. The diameters of the grinding balls were 5 mm and 10 mm, and the number ratio of the two was 1:1. The grinding balls and the weighed GH4169 nickel-based high-temperature alloy powder, Gd2O3 powder and h-BN nanosheets were added to the ball mill at a ball-to-material ratio (i.e., the ratio of the total mass of the grinding balls to the total mass of the material) of 15:1. Anhydrous ethanol was continued to be added, and the volume of anhydrous ethanol accounted for 25% of the volume of the ball mill. The ball mill was sealed and the speed was set to 150 rpm for the first grinding, and the grinding time was 50 minutes; then the speed was increased to 320 rpm for the second grinding, and the grinding time was 25 minutes; finally, all the materials were taken out and mixed with 1000 g of Ti / Ni gradient composite silicon carbide, and dried at 85°C to constant weight to obtain composite ceramic reinforced high-temperature alloy powder.

[0059] 2. Laser additive manufacturing process

[0060] With the help of the repair model in Example 1 and the marked areas 1 to 9, a fiber laser and a coaxial powder feeding system were used, and the laser power of the fiber laser was set to 300 W (for defect depth <1 mm) or 470 W (for defect depth ≥1 mm); the scanning speed was 11.5 mm / s; the powder feeding amount of the coaxial powder feeding system was 13.5 g / min; high-purity argon was used as the protective gas with an inlet flow rate of 25 L / min. Laser additive repair was performed, and the composite ceramic reinforced high-temperature alloy powder obtained in Example 2 was used to repair area 2. Finally, surface shaping was performed to obtain the repaired compressor parts.

[0061] Example 3

[0062] 1. Preparation of composite ceramic reinforced high temperature alloy powder

[0063] Weigh 7000 g of GH4169 nickel-based high-temperature alloy powder, 45 g of Gd2O3 powder and 150 g of h-BN nanosheets for later use.

[0064] Nano-SiC with a particle size of 100 nm was added to a 15 wt% hydrogen fluoride aqueous solution and stirred for 5 minutes; then placed in a 35 wt% ethanol aqueous solution and stirred for 30 minutes, centrifuged and dried at 95°C to constant weight.

[0065] A magnetron sputtering system was selected, which included a vacuum chamber, which included a fluidized bed sputtering chamber. A titanium target and a nickel target were symmetrically installed on both sides of the fluidized bed sputtering chamber. The titanium target had a purity of 99.9 wt% and a diameter of 40 mm. The nickel target had a purity of 99.9 wt% and a diameter of 40 mm. Nano-SiC was placed in the sample area at the center of the fluidized bed sputtering chamber, with the target surfaces of the titanium target and the nickel target 10 cm away from the sample area. The molecular pump was started and the vacuum chamber was evacuated to a basic vacuum (i.e., ≤5×10 -4 MPa); turn on the bottom airflow device and introduce argon into the fluidized bed sputtering chamber at a flow rate of 8 sccm.

[0066] First, the first sputtering was carried out, with only the titanium target turned on, where the sputtering power of the titanium target was 210W, the working pressure was 0.5Pa, and the first sputtering time was 9 minutes. Then the second sputtering was carried out, with the working pressure being 0.5Pa and the sputtering time being 15 minutes. In the first 1 / 3 of the second sputtering time, the sputtering power of the titanium target was uniformly reduced from 210W to 110W, and the sputtering power of the nickel target was uniformly increased from 0W to 70W; in the middle 1 / 3 of the time, the sputtering power of the titanium target was uniformly reduced from 110W to 70W, and the sputtering power of the nickel target was uniformly increased from 70W to 130W; in the last 1 / 3 of the time, the sputtering power of the titanium target was uniformly reduced from 70W to 0W, and the sputtering power of the nickel target was uniformly increased from 130W to 240W. Finally, the third sputtering was performed, with only the nickel target turned on. The sputtering power of the nickel target was 260 W, the working pressure was 0.5 Pa, and the third sputtering time was 12 minutes to complete the gradient deposition.

[0067] The gradient deposited nano-SiC was transferred to a tube furnace, nitrogen was introduced, and the temperature was raised to 400° C. in a nitrogen atmosphere of 0.25 MPa for annealing. The temperature was kept for 1 hour and the furnace was cooled. After sieving, Ti / Ni gradient composite silicon carbide was obtained.

[0068] A planetary ball mill was selected, which was equipped with a ball mill and grinding balls. The diameters of the grinding balls were 5 mm and 10 mm, and the number ratio of the two was 1:1. The grinding balls and the weighed GH4169 nickel-based high-temperature alloy powder, Gd2O3 powder and h-BN nanosheets were added to the ball mill at a ball-to-material ratio (i.e., the ratio of the total mass of the grinding balls to the total mass of the material) of 10:1. Anhydrous ethanol was then added, with the volume of anhydrous ethanol accounting for 35% of the volume of the ball mill. The ball mill was sealed and the speed was set to 200 rpm for the first grinding, and the grinding time was 40 minutes; then the speed was increased to 360 rpm for the second grinding, and the grinding time was 15 minutes; finally, all the materials were taken out and mixed with 1000 g of Ti / Ni gradient composite silicon carbide, and dried at 75°C to constant weight to obtain composite ceramic reinforced high-temperature alloy powder.

[0069] 2. Laser additive manufacturing process

[0070] With the help of the repair model in Example 1 and the marked areas 1 to 9, a fiber laser and a coaxial powder feeding system were used, and the laser power of the fiber laser was set to 290 W (for defect depth <1 mm) or 450 W (for defect depth ≥1 mm); the scanning speed was 10.5 mm / s; the powder feeding amount of the coaxial powder feeding system was 11.5 g / min; high-purity argon was used as the protective gas with an inlet flow rate of 15 L / min. Laser additive repair was performed, and the composite ceramic reinforced high-temperature alloy powder obtained in Example 3 was used to repair area 3. Finally, surface shaping was performed to obtain the repaired compressor parts.

[0071] Comparative Example 1

[0072] Only the first sputtering was performed, and the remaining steps and raw materials used were the same as those in Example 1. The high-temperature alloy powder obtained in Comparative Example 1 was used to repair area 4.

[0073] Comparative Example 2

[0074] Only the third sputtering was performed, and the remaining steps and raw materials used were the same as those in Example 1. The high-temperature alloy powder obtained in Comparative Example 2 was used to repair area 5.

[0075] Comparative Example 3

[0076] No gradient deposition operation was performed, and the remaining steps and raw materials used were the same as those in Example 1. The high-temperature alloy powder obtained in Comparative Example 3 was used to repair area 6.

[0077] Comparative Example 4

[0078] Without adding h-BN nanosheets, the remaining steps and raw materials used were the same as those in Example 1, and the high-temperature alloy powder obtained in Comparative Example 4 was used to repair area 7.

[0079] Comparative Example 5

[0080] Without adding Gd2O3 powder, the remaining steps and raw materials used were the same as those in Example 1. The high-temperature alloy powder obtained in Comparative Example 5 was used to repair area 8.

[0081] Comparative Example 6

[0082] Gd2O3 powder was replaced with CaO. The remaining steps and raw materials were the same as those in Example 1. The high-temperature alloy powder obtained in Comparative Example 6 was used to repair area 9.

[0083] Implementation Effect

[0084] Fix performance test

[0085] 1. Use a universal testing machine to test the shear strength of the interface between the cladding layer and the substrate in areas 1 to 9 at a loading rate of 0.5 mm / min until fracture. Obtain the fracture cross section. If the shear strength is ≥550 MPa, the interface bonding strength is qualified.

[0086] 2. Observe the fracture cross-sections of areas 1-9 using a metallographic microscope at a magnification of 200x. Select five fields of view and manually count the pores using a grid method to calculate the percentage of pore area. If the porosity is ≤1%, it indicates that there is no significant keyhole collapse or splashing (Marangoni convection) in the molten pool. Continue to observe the fracture location, end roughness, and the presence of secondary cracks. Finely grind the fracture cross-section with 1000-grit sandpaper to expose the junction of the cladding layer and the substrate. Increase the magnification of the metallographic microscope to 500x and observe the junction of the cladding layer and the substrate for continuous cracks, lack of fusion lines, or obvious pores.

[0087] The specific cladding layer performance test data are shown in Table 1.

[0088]

[0089] As shown in Table 1, the shear strength of the impeller blades in regions 1 to 3 all meet the requirement of ≥550 MPa, which means that the interfacial bonding between the substrate and the cladding repair layer is good and stress concentration is not easy to occur. The porosity in regions 1 to 3 is all ≤1%, indicating that there is no obvious keyhole collapse or splashing (also known as Marangoni convection) in the molten pool, which meets the test requirements.

[0090] In addition, after observing the fracture cross-section, the fracture locations of regions 1 to 3 (Examples 1 to 3) are mostly in the cladding layer or the substrate, indicating that there are no weak areas caused by residual stress concentration in the cladding layer and the interface between the cladding layer and the substrate, proving that the residual stress is low; while the fracture locations of regions 4 to 9 are mostly at the interface between the cladding layer and the substrate, indicating the presence of stress concentration.

[0091] The fracture surfaces of regions 1-3 are rough and uneven, covered with tiny pits containing tearing edges. They are dark gray overall and lack a metallic luster. This indicates that under low residual stress, shear forces in regions 1-3 are primarily transmitted through plastic deformation, causing the material to fracture through microporous aggregation, consuming high energy and exhibiting good toughness. In contrast, the fracture surfaces of regions 4-9 are flat and smooth, exhibiting crystalline facets with a metallic luster. Radial striations can be seen extending from the stress concentration point. This indicates that under the influence of high residual stress and internal defects in regions 4-9, the material fractures suddenly without significant plastic deformation, consuming less energy and exhibiting high brittleness.

[0092] There are no secondary cracks (i.e., many small cracks parallel to or at a certain angle to the main fracture surface) near the main fracture surface in regions 1 to 3, indicating that the residual stress is small; while secondary cracks exist in regions 4 to 9, indicating that the residual stress is large.

[0093] When observing the junction between the cladding layer and the substrate, there are no continuous cracks, unfused lines or obvious pores (i.e., the diameter of a single pore is ≤ 0.2 mm, 10 mm) at the junction of areas 1 to 3. 2 The number of internal pores is ≤3), and the transition zone is gradual without a clear linear boundary, indicating that the interface fusion is good.

Claims

1. A laser additive manufacturing process for repairing compressor parts, characterized in that: The following steps are involved: S1, treating the surface of nano-silicon carbide for standby use; S2, installing nano-silicon carbide, a titanium target, and a nickel target in a magnetron sputtering system to perform gradient deposition on nano-silicon carbide; After deposition, Ti / Ni gradient composite silicon carbide is obtained through annealing and sieving; S3, nickel-based high-temperature alloy, gadolinium oxide and hexagonal boron nitride are ground in a grinding medium, and after grinding, mixed with Ti / Ni gradient composite silicon carbide, and dried to obtain composite ceramic reinforced high-temperature alloy powder; S4. Clean the compressor parts, detect defects in the compressor parts, determine the area to be repaired, model the area to be repaired, and generate a repair model; According to the repair model, composite ceramic reinforced high-temperature alloy powder is used for laser additive manufacturing to obtain the repaired compressor parts; Gradient deposition in S2 includes the following steps: (1) First, the first sputtering is performed, with only the titanium target turned on, where the sputtering power of the titanium target is 190~210W; (2) Then, a second sputtering is performed. In the first 1 / 3 of the second sputtering, the sputtering power of the titanium target is uniformly reduced from 190~210W to 90~110W, and the sputtering power of the nickel target is uniformly increased from 0W to 50~70W; in the middle 1 / 3 of the second sputtering, the sputtering power of the titanium target is uniformly reduced from 90~110W to 50~70W, and the sputtering power of the nickel target is uniformly increased from 50~70W to 110~130W; in the last 1 / 3 of the second sputtering, the sputtering power of the titanium target is uniformly reduced from 50~70W to 0W, and the sputtering power of the nickel target is uniformly increased from 110~130W to 220~240W; (3) Finally, the third sputtering is performed, with only the nickel target turned on, where the sputtering power of the nickel target is 240~260W, to complete the gradient deposition operation.

2. The laser additive remanufacturing process for repairing compressor parts according to claim 1, characterized in that: In S1, the particle size of nano-silicon carbide is 50~100nm. During the surface treatment, the nano-silicon carbide is first placed in a 10~15wt% hydrogen fluoride aqueous solution and stirred and washed for 5~10min; then placed in a 35~45wt% ethanol aqueous solution and stirred and washed for 20~30min. After centrifugal separation, it is dried at 85~95°C to constant weight to complete the surface treatment operation.

3. The laser additive manufacturing process for repairing compressor parts according to claim 1, characterized in that: In S2, the magnetron sputtering system includes a vacuum chamber, which includes a fluidized bed sputtering chamber. The installation process is to symmetrically install titanium targets and nickel targets on both sides of the fluidized bed sputtering chamber. Nano-silicon carbide is placed in the sample area at the center of the fluidized bed sputtering chamber, so that the target surface of the titanium target and the nickel target is 10-15 cm away from the sample area. The vacuum chamber is evacuated to a basic vacuum of ≤5×10 -4 MPa; argon gas was introduced into the fluidized bed sputtering chamber at a flow rate of 8~10sccm.

4. The laser additive remanufacturing process for repairing compressor parts according to claim 1, characterized in that: The working pressure of the first sputtering is 0.3~0.5Pa, and the first sputtering time is 9~12min; the working pressure of the second sputtering is 0.3~0.5Pa, and the second sputtering time is 15~18min; the working pressure of the third sputtering is 0.3~0.5Pa, and the third sputtering time is 12~16min.

5. The laser additive remanufacturing process for repairing compressor parts according to claim 1, characterized in that: In S2, nitrogen is introduced during annealing, the nitrogen pressure is 0.15~0.25MPa, the annealing temperature is 400~480℃, and the annealing holding time is 1~2h.

6. The laser additive remanufacturing process for repairing compressor parts according to claim 1, characterized in that: In S3, a planetary ball mill is used for grinding, and the planetary ball mill includes a ball milling jar and grinding balls; the grinding medium is anhydrous ethanol; and the nickel-based high-temperature alloy is GH4169 nickel-based high-temperature alloy.

7. The laser additive manufacturing process for repairing compressor parts according to claim 6, characterized in that: The ratio of the total mass of the grinding balls to the total mass of the nickel-based high-temperature alloy, gadolinium oxide, and hexagonal boron nitride is 10-15:1; The volume of the grinding medium accounts for 25~35% of the volume of the ball mill; the grinding includes the first grinding and the second grinding, the first grinding speed is 150~200rpm, the first grinding time is 40~50min; the second grinding speed is 320~360rpm, the second grinding time is 15~25min, and the drying temperature is 75~85℃.

8. The laser additive remanufacturing process for repairing compressor parts according to claim 1, characterized in that: In S3, when mixed, the mass ratio of Ti / Ni gradient composite silicon carbide, nickel-based high-temperature alloy, gadolinium oxide and hexagonal boron nitride is 100:(700~800):(4.5~6):(15~18).

9. The laser additive remanufacturing process for repairing compressor parts according to claim 1, characterized in that: In S4, fiber laser and coaxial powder feeding system are used for laser additive remanufacturing. When the defect depth is less than 1mm, the laser power of the fiber laser is 290~300W. When the defect depth is ≥1mm, the laser power of the fiber laser is 450~470W, and the scanning speed is 10.5~11.5mm / s. The powder feeding amount of the coaxial powder feeding system is 11.5~13.5g / min. The protective gas is high-purity argon, and the inlet flow rate is 15~25L / min.

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