A long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade and a preparation method thereof

Abstract

The present invention discloses a long-lasting anti-corrosion multilayer coating on the surface of a turbine blade and a preparation method thereof, specifically comprising: preparing powder particles for spraying, preparing an anti-erosion coating and a composite anti-cavitation coating by HVOF, and alternately spraying to obtain the long-lasting anti-corrosion multilayer coating; the multilayer coating is composed of an anti-erosion coating and an anti-cavitation coating alternately sprayed on a blade substrate, and the anti-cavitation coating and the anti-erosion coating are alternately exposed and have appropriate layer thicknesses to specifically resist cavitation damage in non-flood seasons and erosion damage in flood seasons, reduce the overall abrasion rate of the coating, and extend the service life of the blade. At the same time, the service life of the blade is regulated by changing the number of layers of the anti-erosion coating and the anti-cavitation coating, which is also helpful to predict the overhaul cycle of the turbine and reduce the exploration workload. It has important application prospects in the field of surface protection of hydraulic machinery.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic machinery surface protection, and particularly relates to a long-lasting corrosion-resistant multi-layer coating on the surface of a turbine blade and a preparation method thereof. Background Art

[0002] The Yellow River is famous for its high sediment load. From 1919 to 2020, its average sediment load reached 1.11 billion tons, with an average sediment content of 30.5 kg / m 3 , with the highest sand content in the world. Due to soil erosion, the Yangtze River Basin also has a relatively serious sand content in the water, and its sand content is also among the highest in the world. At the same time, the annual distribution of sediment in the Yellow River and the Yangtze River is uneven, with periodic changes of high and low water levels, and the amount of water and sediment is mainly concentrated in the flood season. For example, the average annual sediment content at the upper end of the Yellow River where the Qingtongxia Hydropower Station is located is 9.83kg / m 3 , the maximum sand content is 431.35kg / m 3 , the amount of sand is mainly concentrated in July and August every year. When the turbines of hydropower stations operate in the Yellow River or the Yangtze River for a long time, their flow-through components (such as blades) are very prone to severe corrosion. These mainly include sediment erosion and cavitation erosion, which will damage the metal surface of the turbine blades, shorten the service life of the blades, reduce the efficiency of the turbine, generate vibration and noise, and affect the safety and stability of operation. At present, there are two main ways to solve the abrasion problem of turbine blades: the first is to use supersonic flame spraying (HOVF), laser cladding and other technologies to prepare a hard inorganic coating on the blade surface. The second is to use coating, pouring and other technologies to prepare an organic coating on the blade surface, such as composite resin mortar and polyurethane. However, the organic coating has low hardness, weak bonding strength with the substrate, poor erosion resistance, short service life, and it is difficult to provide long-term protection for the blades. While inorganic coatings offer excellent properties such as high strength, wear resistance, and high bonding strength, they typically struggle to provide both cavitation and erosion resistance. For example, WC coatings and Fe-based amorphous coatings (SAM2X5) offer excellent protection against sediment erosion but poor cavitation protection. Stainless steel-based coatings (such as ZG04Cr16Ni5Mo) offer the opposite. Consequently, conventional inorganic coatings cannot significantly extend the service life of turbine blades.

[0003] Designing suitable protective coatings to improve turbine blade erosion (erosion-cavitation) resistance and extend blade service life is a current research hotspot. The design of anti-erosion coatings must consider the actual water quality environment. Generally speaking, for hydropower stations located in the middle and upper reaches of the Yangtze and Yellow River basins, the actual sediment load during the flood season (approximately 3,672 hours annually, from June to October) accounts for over 95% of the annual sediment transport volume. Therefore, the flood season is the primary period for sediment erosion on turbine blades. During the non-flood season (approximately 5,088 hours), sediment erosion is negligible, with cavitation being the primary cause. Alternating layers of anti-erosion and anti-cavitation materials are combined to create a lamellar, anti-erosion inorganic multilayer coating of appropriate thickness, tailored to the peak annual occurrence periods of sediment erosion and cavitation. This coating provides targeted protection against erosion damage during the flood season and cavitation damage during the non-flood season. This has practical implications for reducing the overall wear rate, extending the service life of turbine blades, and predicting turbine overhaul intervals.

[0004] Zhang Lei et al. (Zhang Lei, Zhang Kai, Huo Jiaxiang et al. Effect of spraying distance on the microstructure and anti-sediment erosion performance of nano-WC-10Co4Cr coatings sprayed by internal hole HVOF [J]. Rare Metals & Cemented Carbide, 2023, 51(05):36-43.) used internal hole oxygen-propane high velocity flame spraying technology to prepare nano-WC-10Co4Cr coatings on the surface of ZG0Cr13Ni5Mo stainless steel substrates. The coatings had excellent strength and anti-sediment erosion performance that was 7 to 8 times that of the substrate. However, the coatings had relatively poor toughness and needed to improve their cavitation resistance. Under the alternating effects of sediment erosion and cavitation, it was difficult to significantly extend the service life of the blades.

[0005] The Chinese patent "A Highly Erosion-Cavitation-Corrosion-Resistant Coating" (Application Number: 202211041989.1, Application Publication Number: CN 115386871 A, Publication Date: November 25, 2022) uses laser cladding technology to form a coating with high erosion-cavitation-corrosion resistance from Fe90, Ti powder, and Cr3C2. This coating can increase the service life of flow-through components in hydraulic machinery. However, the coating has poor hardness, and the coating substrate will still suffer severe wear under sediment erosion. At the same time, the hard reinforcing phase particles are easily detached as the coating substrate wears, exacerbating coating damage, making it difficult to ensure long-term protective effects.

[0006] The Chinese patent "A High-Entropy Alloy / Ceramic Composite Anti-Cavitation and Anti-Abrasion Coating and Its Preparation Method" (Application Number: 202211451667.4, Application Publication Number: CN 115772639 A, Publication Date: March 10, 2023) describes a high-entropy alloy / ceramic composite anti-cavitation and anti-abrasion coating prepared by atmospheric supersonic spraying. The coating's cavitation resistance is 4 to 8 times that of the substrate, and its erosion resistance is 12 to 14.5 times that of the substrate, effectively addressing the cavitation and erosion problems of turbine flow components. However, this coating exhibits a trade-off between cavitation and erosion resistance, making it difficult to flexibly adjust its erosion resistance for flood and non-flood seasons, and also making it difficult to predict turbine overhaul cycles. Furthermore, the coating's relatively weak cavitation resistance hinders the extension of turbine blade service life.

[0007] The Chinese patent "Modified Polyurethane Coating and Preparation Method for Turbine Flow Components" (Application Number: 202310084418.4, Application Publication Number: CN 116239946A, Publication Date: June 9, 2023) discloses a modified polyurethane coating for turbine flow components. The coating is composed of diisocyanate, polyether polyol, chain extender, propylene glycol methyl ether acetate, hydroxyl-terminated polysiloxane, and cage-type polysilsesquioxane-modified nano-ceramic particles. It can improve the cavitation and abrasion resistance of turbine flow components. However, due to the poor scratch and erosion resistance of polyurethane polymer coatings and the weak adhesion between the coating and the substrate, it is easy to fall off and fail during service, making it difficult to ensure the protective effect of the coating. Summary of the Invention

[0008] The purpose of the present invention is to provide a long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade and a preparation method thereof, so as to solve the problem that existing turbine blades are difficult to resist the alternating damage of flood season erosion and non-flood season cavitation erosion and have a short service life.

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

[0010] A method for preparing a long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade is specifically implemented by the following steps:

[0011] Step 1: Prepare powder particles for spraying:

[0012] The SAM2X5 amorphous alloy powder was dried in an oven to obtain alloy powder for spraying; ZG04Cr16Ni5Mo stainless steel powder and WC ceramic powder were ball-milled and mixed in proportion, and then dried to obtain stainless steel / ceramic powder;

[0013] Step 2: HVOF preparation of erosion-resistant coating:

[0014] The alloy powder obtained in step 1 is loaded into the HVOF equipment, and the supersonic flame spraying parameters are adjusted to spray the anti-erosion coating on the pretreated blade surface;

[0015] Step 3, HVOF composite anti-cavitation coating:

[0016] The blade containing the anti-erosion coating obtained in step 2 is placed in an HVOF device loaded with stainless steel / ceramic powder, and a composite anti-cavitation coating is sprayed by supersonic flame to obtain an inorganic double-layer anti-erosion coating;

[0017] Step 4: Alternate spraying to prepare a corrosion-resistant multilayer coating:

[0018] According to the operations of step 2 and step 3, the anti-erosion coating and the anti-cavitation coating are sprayed alternately layer by layer on the inorganic double-layer anti-corrosion coating to obtain a long-lasting anti-corrosion multi-layer coating.

[0019] Furthermore, the SAM2X5 amorphous alloy powder in step 1 is Fe2O3 without organic binder and with a particle size of 25 to 35 μm. 49.7 Cr 17.7 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 Iron-based amorphous alloy powder; the mass percentages of ZG04Cr16Ni5Mo stainless steel powder and WC ceramic powder are 75% to 76% and 24% to 25% respectively, and the total is 100%. The ZG04Cr16Ni5Mo stainless steel powder is composed of the following powders by mass fraction: C powder: 0.053% to 0.065%, Cr powder: 15.17% to 15.93%, Ni powder: 4.82% to 5.91%, Mo powder: 0.87% to 1.03%, Mn powder: 0.45% to 0.88%, Si powder: 0.35% to 0.529%, Cu powder: 0.03% to 0.04%, and P powder: 0.005% to 0.016%. , S powder: 0.002~0.005%, Fe powder: 75.595~78.25%, the sum of the above components is 100%, the particle size of ZG04Cr16Ni5Mo stainless steel powder is 5~50μm; the particle size of WC ceramic powder is 5~25μm, the ball mill speed is 200~300r / min, the ball milling time is 1~2h, the ball-to-material mass ratio is 2:1, the drying temperature of SAM2X5 amorphous alloy powder in the oven is 100~120℃, the drying time is 2~4h, the drying temperature of ZG04Cr16Ni5Mo stainless steel powder and WC ceramic powder after ball milling is 100~120℃, and the drying time is 2~4h.

[0020] Furthermore, in step 2, the HVOF equipment uses kerosene as fuel, and the kerosene flow rate is 20.8 to 29.7 L / h; oxygen is used as the combustion-supporting gas, and the oxygen flow rate is 830 to 940 L / min; nitrogen is used as the powder feeding gas, and the nitrogen flow rate is 11.5 to 14.0 L / min; the powder feeding rate is 48 to 60 g / min, the spraying distance is 350 to 380 mm, and the spray gun scanning speed is 375 to 500 mm / s.

[0021] Furthermore, the pretreatment of the blade in step 2 includes surface decontamination and degreasing and sandblasting roughening treatment.

[0022] Furthermore, in step 3, the HVOF equipment uses kerosene as fuel, the kerosene flow rate is 40.0-42.5 L / min, oxygen as the combustion-supporting gas, the oxygen flow rate is 237-252 L / min, and nitrogen as the powder feeding gas, the nitrogen flow rate is 348-370 L / min; the powder feeding rate is 39.5-42.0 g / min, the spraying distance is 250-260 mm, and the spray gun scanning speed is 250-260 mm / s.

[0023] Furthermore, in step 4, the anti-erosion coating and the anti-cavitation coating are alternately sprayed 6 to 9 times.

[0024] Furthermore, the thickness of each layer of the anti-erosion coating is 0.5 to 1 mm, and the thickness of each layer of the anti-cavitation coating is 0.3 to 0.6 mm.

[0025] The long-lasting corrosion-resistant multilayer coating prepared by the above-mentioned method for preparing a long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade is composed of an anti-erosion coating and an anti-cavitation coating alternately sprayed on the blade substrate from the inside to the outside, wherein the anti-erosion coating and the anti-cavitation coating each have 7 to 10 layers.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] A method for preparing a long-lasting anti-corrosion multilayer coating on the surface of a turbine blade comprises spraying a long-lasting anti-corrosion multilayer coating with high bonding strength, lamellar shape and appropriate layer thickness on the surface of the turbine blade. The high-toughness anti-cavitation coating on the outermost side of the coating can specifically resist cavitation erosion during the non-flood season. When the flood season comes, the anti-cavitation coating is removed by sediment erosion, exposing the high-strength and wear-resistant anti-erosion coating on the inner side, which can effectively protect against erosion damage. The remaining anti-erosion coating will be consumed by the cavitation in the next round of non-flood season, and the anti-cavitation coating will be exposed again to resist cavitation damage. The alternatingly exposed anti-cavitation coating and anti-erosion coating with appropriate layer thickness can specifically resist cavitation damage in the non-flood season and erosion damage in the flood season, thereby reducing the overall abrasion rate of the coating, providing effective protection for the turbine blades, and extending the service life of the blades. At the same time, the combination of an anti-cavitation coating and an anti-erosion coating can cope with one year of abrasion damage. Therefore, by changing the number of layers of the anti-erosion coating and the anti-cavitation coating, the service life of the turbine blades can be flexibly controlled, which is also helpful to predict the overhaul cycle of the turbine and reduce the exploration workload. In addition, the production cost of the present invention is low, the preparation process is reliable, the main elements of the blade substrate, the anti-cavitation coating and the anti-erosion coating are similar, the interface is tightly and firmly bonded, and the coating performance is stable. The long-lasting corrosion-resistant multi-layer coating prepared by the present invention solves the problem that the existing turbine blades are difficult to resist the alternating damage of flood season erosion and non-flood season cavitation and have a short service life, and has broad application prospects in the field of surface protection of hydraulic machinery. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade prepared by the present invention.

[0029] In the figure, 1 is a turbine blade substrate, 2 is an anti-erosion coating, and 3 is an anti-cavitation coating. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] A method for preparing a long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade is specifically implemented by the following steps:

[0032] Step 1: Prepare powder particles for spraying:

[0033] The SAM2X5 amorphous alloy powder is dried in an oven at 100-120°C for 2-4 hours to obtain alloy powder for spraying; the ZG04Cr16Ni5Mo stainless steel powder and the WC ceramic powder are mixed by ball milling in proportion at a speed of 200-300 r / min with a ball-to-material mass ratio of 2:1 for 1-2 hours, and dried at 100-120°C for 2-4 hours to obtain the stainless steel / ceramic powder.

[0034] In step 1, the SAM2X5 alloy powder is Fe2O3 alloy powder without organic binder and with a particle size of 25 to 35 μm. 49.7 Cr 17.7 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 Iron-based amorphous alloy powder. The mass percentages of ZG04Cr16Ni5Mo stainless steel powder and WC ceramic powder are 75%-76% and 24%-25%, respectively, totaling 100%. The stainless steel powder is composed of the following powder compositions by mass: C powder: 0.053-0.065%, Cr powder: 15.17-15.93%, Ni powder: 4.82-5.91%, Mo powder: 0.87-1.03%, Mn powder: 0.45-0.88%, Si powder: 0.35-0.529%, Cu powder: 0.03-0.04%, P powder: 0.005-0.016%, S powder: 0.002-0.005%, and Fe powder: 75.595-78.25%, totaling 100%. The stainless steel powder particle size is 5-50μm, and the WC ceramic powder particle size is 5-25μm.

[0035] Step 2: HVOF preparation of erosion-resistant coating:

[0036] The SAM2X5 alloy powder obtained in step 1 is loaded into the HVOF equipment, the supersonic flame spraying parameters are adjusted, and the anti-erosion coating is sprayed on the blade surface that has been pre-treated by decontamination, degreasing and sandblasting.

[0037] In step 2, the HVOF equipment uses kerosene as fuel, with a kerosene flow rate of 20.8 to 29.7 L / h; oxygen as the combustion-supporting gas, with an oxygen flow rate of 830 to 940 L / min; nitrogen as the powder feeding gas, with a nitrogen flow rate of 11.5 to 14.0 L / min; the powder feeding rate is 48 to 60 g / min, the spraying distance is 350 to 380 mm, and the spray gun scanning speed is 375 to 500 mm / s.

[0038] Step 3, HVOF composite anti-cavitation coating:

[0039] The blade containing the anti-erosion coating obtained in step 2 is placed in an HVOF device loaded with stainless steel / ceramic powder, and a composite anti-cavitation coating is sprayed by supersonic flame to obtain an inorganic double-layer anti-erosion coating.

[0040] In step 3, the HVOF equipment uses kerosene as fuel, and the kerosene flow rate is 40.0~42.5L / min; oxygen is used as the combustion-supporting gas, and the oxygen flow rate is 237~252L / min; nitrogen is used as the powder feeding gas, and the nitrogen flow rate is 348~370L / min; the powder feeding rate is 39.5~42.0g / min, the spraying distance is 250~260mm, and the spray gun scanning speed is 250~260mm / s.

[0041] Step 4: Alternate spraying to prepare a corrosion-resistant multilayer coating:

[0042] According to the operations of step 2 and step 3, the anti-erosion coating and the anti-cavitation coating with appropriate thickness are sprayed alternately layer by layer 6 to 9 times on the double-layer anti-corrosion coating to obtain a long-lasting anti-corrosion multilayer coating.

[0043] In step 4, the coating is composed of an anti-erosion coating 2 and an anti-cavitation coating 3 sprayed alternately on the turbine blade substrate 1 from the inside to the outside, such as Figure 1 As shown, the anti-erosion coating and the anti-cavitation coating each have 7 to 10 layers. The thickness of each anti-erosion coating layer is 0.5 to 1 mm, and the thickness of each anti-cavitation coating layer is 0.3 to 0.6 mm.

[0044] The present invention provides a long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade and a preparation method thereof. By ball milling, mixing and drying, spray powder particles with uniform dispersion and good fluidity are prepared, thereby achieving the purpose of improving the powder feeding effect and enhancing the supersonic flame spraying effect. By controlling the component content and particle size of the spray powder particles and optimizing the HVOF process parameters, a defect-free, high-toughness anti-cavitation coating and a uniform, dense, high-strength and wear-resistant anti-erosion coating are obtained. The interfaces between the two are tightly and firmly bonded, and can respectively resist cavitation damage in non-flooding seasons and erosion damage in flooding seasons, thereby extending the service life of the blades. By changing the number of times the anti-erosion coating and the anti-cavitation coating are alternately sprayed, corrosion-resistant multilayer coatings with different numbers of layers are obtained, which can not only prevent the alternating damage of erosion in flooding seasons and cavitation damage in non-flooding seasons, regulate the service life of the turbine blades, but also help predict the overhaul cycle of the turbine and reduce the exploration workload.

[0045] The present invention provides a method for preparing a long-lasting anti-corrosion multilayer coating on the surface of a turbine blade. A long-lasting anti-corrosion multilayer coating with high bonding strength, lamellar shape and appropriate layer thickness is sprayed on the surface of the turbine blade. The high-toughness anti-cavitation coating on the outermost side of the coating can specifically resist cavitation erosion during the non-flood season. When the flood season comes, the anti-cavitation coating is removed by sediment erosion, exposing the high-strength and wear-resistant anti-erosion coating on the inner side, which can achieve effective protection against erosion damage. The remaining anti-erosion coating will be consumed by the cavitation action of the next round of non-flood season, and the anti-cavitation coating will be exposed again to resist cavitation damage. The alternatingly exposed anti-cavitation coating and the anti-erosion coating with appropriate layer thickness can specifically resist cavitation damage during the non-flood season and erosion damage during the flood season, thereby reducing the overall abrasion rate of the coating, providing effective protection for the turbine blades, and extending the service life of the blades. At the same time, the combination of an anti-cavitation coating and an anti-erosion coating can cope with one year of abrasion damage. Therefore, by changing the number of layers of the anti-erosion coating and the anti-cavitation coating, the service life of the turbine blades can be flexibly controlled, which is also helpful to predict the overhaul cycle of the turbine and reduce the exploration workload. In addition, the production cost of the present invention is low, the preparation process is reliable, the main elements of the blade substrate, the anti-cavitation coating and the anti-erosion coating are similar, the interface is tightly and firmly bonded, and the coating performance is stable. The long-lasting corrosion-resistant multi-layer coating prepared by the present invention solves the problem that the existing turbine blades are difficult to resist the alternating damage of flood season erosion and non-flood season cavitation erosion, and have a short service life. It has broad application prospects in the field of abrasion protection of hydraulic machinery.

[0046] Example 1

[0047] 2.5 kg of SAM2X5 amorphous alloy powder with a particle size of 25-35 μm was dried in an oven at 100 ° C for 4 h to obtain alloy powder for spraying; 0.00106 kg of C powder, 0.3034 kg of Cr powder, 0.0964 kg of Ni powder, 0.0174 kg of Mo powder, 0.009 kg of Mn powder, 0.007 kg of Si powder, 0.0006 kg of Cu powder, 0.0001 kg of P powder, 0.00004 kg of S powder and 1.565 kg of Fe powder (particle size 5-50 μm) and 0.6667 kg of WC ceramic powder (particle size 5-25 μm) were ball milled at a speed of 300 r / min with a ball-to-material mass ratio of 2:1 for 1 h, and then dried at 120 ° C for 2 h to obtain stainless steel / ceramic powder.

[0048] The alloy powder was loaded into the HVOF equipment, and the kerosene flow rate was adjusted to 20.8 L / h, the oxygen flow rate was 940 L / min, the nitrogen flow rate was 11.5 L / min, the powder feeding rate was 60 g / min, the spraying distance was 350 mm, and the spray gun scanning speed was 375 mm / s. A 0.5 mm thick anti-erosion coating was sprayed on the blade surface that had been pre-treated by decontamination, degreasing and sandblasting.

[0049] The blade containing the anti-erosion coating was placed in an HVOF device loaded with stainless steel / ceramic powder, and the kerosene flow rate was adjusted to 40.0L / min, the oxygen flow rate was 237L / min, the nitrogen flow rate was 348L / min, the powder feeding rate was 39.5g / min, the spraying distance was 250mm, and the spray gun scanning speed was 250mm / s. The supersonic flame sprayed composite 0.3mm thick anti-cavitation coating was obtained to obtain an inorganic double-layer anti-erosion coating.

[0050] According to the above spraying operation, the anti-erosion coating and the anti-cavitation coating with different thicknesses are sprayed alternately on the double-layer anti-corrosion coating layer by layer for 9 times to obtain a long-lasting anti-corrosion multi-layer coating.

[0051] Example 2

[0052] 2 kg of SAM2X5 amorphous alloy powder with a particle size of 25-35 μm was dried in an oven at 120 ° C for 2 h to obtain alloy powder for spraying; 0.0013 kg of C powder, 0.3186 kg of Cr powder, 0.1182 kg of Ni powder, 0.0206 kg of Mo powder, 0.0176 kg of Mn powder, 0.01058 kg of Si powder, 0.0008 kg of Cu powder, 0.00032 kg of P powder, 0.0001 kg of S powder and 1.5119 kg of Fe (particle size 5-50 μm) and 0.6667 kg of WC ceramic powder (particle size 5-25 μm) were ball milled at a speed of 300 r / min with a ball-to-material mass ratio of 2:1 for 1 h, and dried at 120 ° C for 2 h to obtain stainless steel / ceramic powder.

[0053] The alloy powder was loaded into the HVOF equipment, and the kerosene flow rate was adjusted to 29.7 L / h, the oxygen flow rate was 830 L / min, the nitrogen flow rate was 14.0 L / min, the powder feeding rate was 48 g / min, the spraying distance was 380 mm, and the spray gun scanning speed was 500 mm / s. A 0.8 mm thick anti-erosion coating was sprayed on the blade surface that had been pre-treated by decontamination, degreasing and sandblasting.

[0054] The blade containing the anti-erosion coating was placed in an HVOF device loaded with stainless steel / ceramic powder, and the kerosene flow rate was adjusted to 41L / min, the oxygen flow rate was 240L / min, the nitrogen flow rate was 352L / min, the powder feeding rate was 41.0g / min, the spraying distance was 250mm, and the spray gun scanning speed was 250mm / s. The supersonic flame sprayed composite 0.4mm thick anti-cavitation coating was obtained to obtain an inorganic double-layer anti-erosion coating.

[0055] According to the above spraying operation, the anti-erosion coating and the anti-cavitation coating with different thicknesses are sprayed alternately layer by layer 6 times on the double-layer anti-corrosion coating to obtain a long-lasting anti-corrosion multi-layer coating.

[0056] Example 3

[0057] 2 kg of SAM2X5 amorphous alloy powder with a particle size of 25-35 μm was dried in an oven at 110 ° C for 3 h to obtain alloy powder for spraying; 0.0011 kg of C powder, 0.3064 kg of Cr powder, 0.0964 kg of Ni powder, 0.0174 kg of Mo powder, 0.0176 kg of Mn powder, 0.007 kg of Si powder, 0.0008 kg of Cu powder, 0.0001 kg of P powder, 0.00004 kg of S powder and 1.55316 kg of Fe powder (particle size 5-50 μm) and 0.6316 kg of WC ceramic powder (particle size 5-25 μm) were ball milled at a speed of 300 r / min with a ball-to-material mass ratio of 2:1 for 2 h, and dried at 110 ° C for 3 h to obtain stainless steel / ceramic powder.

[0058] The alloy powder was loaded into the HVOF equipment, and the kerosene flow rate was adjusted to 22.8 L / h, the oxygen flow rate was 873 L / min, the nitrogen flow rate was 12.0 L / min, the powder feeding rate was 50 g / min, the spraying distance was 380 mm, and the spray gun scanning speed was 400 mm / s. A 1 mm thick anti-erosion coating was sprayed on the blade surface that had been pre-treated by decontamination, degreasing and sandblasting roughening.

[0059] The blade containing the anti-erosion coating was placed in an HVOF device loaded with stainless steel / ceramic powder, and the kerosene flow rate was adjusted to 40.5L / min, the oxygen flow rate was 240L / min, the nitrogen flow rate was 352L / min, the powder feeding rate was 40.0g / min, the spraying distance was 250mm, and the spray gun scanning speed was 250mm / s. The supersonic flame sprayed composite 0.6mm thick anti-cavitation coating was obtained to obtain an inorganic double-layer anti-erosion coating.

[0060] According to the above spraying operation, the anti-erosion coating and the anti-cavitation coating with different thicknesses are sprayed alternately layer by layer 7 times on the double-layer anti-corrosion coating to obtain a long-lasting anti-corrosion multilayer coating.

[0061] Example 4

[0062] 2 kg of SAM2X5 amorphous alloy powder with a particle size of 25-35 μm was dried in an oven at 100 ° C for 4 h to obtain alloy powder for spraying; 0.00106 kg of C powder, 0.3186 kg of Cr powder, 0.1082 kg of Ni powder, 0.02 kg of Mo powder, 0.009 kg of Mn powder, 0.0074 kg of Si powder, 0.0006 kg of Cu powder, 0.00032 kg of P powder, 0.00004 kg of S powder and 1.53478 kg of Fe powder (particle size 5-50 μm) and 0.6490 kg of WC ceramic powder (particle size 5-25 μm) were ball milled at a speed of 200 r / min with a ball-to-material mass ratio of 2:1 for 2 h, and then dried at 110 ° C for 2 h to obtain stainless steel / ceramic powder.

[0063] The alloy powder was loaded into the HVOF equipment, and the kerosene flow rate was adjusted to 23 L / h, the oxygen flow rate was 880 L / min, the nitrogen flow rate was 12.0 L / min, the powder feeding rate was 60 g / min, the spraying distance was 360 mm, and the spray gun scanning speed was 380 mm / s. A 0.9 mm thick anti-erosion coating was sprayed on the blade surface that had been pre-treated by decontamination, degreasing and sandblasting.

[0064] The blade containing the anti-erosion coating was placed in an HVOF device loaded with stainless steel / ceramic powder, and the kerosene flow rate was adjusted to 41L / min, the oxygen flow rate was 243L / min, the nitrogen flow rate was 356L / min, the powder feeding rate was 40.5g / min, the spraying distance was 255mm, and the spray gun scanning speed was 255mm / s. The supersonic flame sprayed composite 0.5mm thick anti-cavitation coating was obtained to obtain an inorganic double-layer anti-erosion coating.

[0065] According to the above spraying operation, the anti-erosion coating and the anti-cavitation coating with different thicknesses are sprayed alternately 8 times on the double-layer anti-corrosion coating to obtain a long-lasting anti-corrosion multilayer coating.

[0066] Example 5

[0067] 2.5 kg of SAM2X5 amorphous alloy powder with a particle size of 25-35 μm was dried in an oven at 120 ° C for 3 h to obtain alloy powder for spraying; 0.0011 kg of C powder, 0.3064 kg of Cr powder, 0.0964 kg of Ni powder, 0.0174 kg of Mo powder, 0.0176 kg of Mn powder, 0.007 kg of Si powder, 0.0008 kg of Cu powder, 0.0001 kg of P powder, 0.00004 kg of S powder and 1.55316 kg of Fe powder (particle size 5-50 μm) and 0.6490 kg of WC ceramic powder (particle size 5-25 μm) were ball milled at a speed of 200 r / min with a ball-to-material mass ratio of 2:1 for 1 h, and dried at 100 ° C for 4 h to obtain stainless steel / ceramic powder.

[0068] The alloy powder was loaded into the HVOF equipment, and the kerosene flow rate was adjusted to 24.6 L / h, the oxygen flow rate was 920 L / min, the nitrogen flow rate was 13.0 L / min, the powder feeding rate was 55 g / min, the spraying distance was 370 mm, and the spray gun scanning speed was 420 mm / s. A 0.8 mm thick anti-erosion coating was sprayed on the blade surface that had been pre-treated by decontamination, degreasing and sandblasting.

[0069] The blade containing the anti-erosion coating was placed in an HVOF device loaded with stainless steel / ceramic powder, and the kerosene flow rate was adjusted to 42.5L / min, the oxygen flow rate was 252L / min, the nitrogen flow rate was 370L / min, the powder feeding rate was 42.0g / min, the spraying distance was 260mm, and the spray gun scanning speed was 260mm / s. The anti-cavitation coating with a thickness of 0.5mm was composited by supersonic flame spraying to obtain an inorganic double-layer anti-erosion coating.

[0070] According to the above spraying operation, the anti-erosion coating and the anti-cavitation coating with different thicknesses are sprayed alternately on the double-layer anti-corrosion coating layer by layer for 9 times to obtain a long-lasting anti-corrosion multi-layer coating.

[0071] Erosion and cavitation test: The coating samples were tested for erosion and cavitation resistance in a high-speed sand jet abrasion instrument and an ultrasonic material cavitation tester, and the abrasion depth of the sample surface was measured using a surface topography instrument. The erosion test conditions were: sand content 200kg / m 3 , flow rate 30m / s, impact angle 90°, impact time 36h; cavitation test conditions are: power 1200W, ultrasonic frequency 20KHz, ultrasonic time 72h.

[0072] Table 1 compares the performance of a ZG04Cr16Ni5Mo stainless steel coating, a SAM2X5 amorphous coating, and the long-lasting corrosion-resistant multilayer coatings prepared in Examples 1 and 2 of the present invention. As can be seen from the table, the ZG04Cr16Ni5Mo stainless steel coating has a relatively low hardness of only 356 HV, a cavitation depth of 0.39 mm, and a total abrasion depth of 1.04 mm in the alternating cavitation and erosion experiments, demonstrating poor corrosion resistance. The SAM2X5 amorphous coating has high hardness, high brittleness, and relatively poor toughness, and its cavitation resistance needs to be improved. Compared with the above coatings, the coatings prepared in Examples 1 and 2 have higher hardness and excellent fracture toughness. Their cavitation depths are 41-46% and 32-36% of those of the ZG04Cr16Ni5Mo stainless steel coating and the SAM2X5 amorphous coating, respectively. They also have excellent protective effects under the alternating damage of cavitation and erosion, and the total abrasion depths are only 38-46% and 62-74% of those of the ZG04Cr16Ni5Mo stainless steel coating and the SAM2X5 amorphous coating, respectively.

[0073] Table 1

[0074]

[0075] The above-described embodiments merely represent specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for preparing a long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade, characterized in that: Please follow the steps below to implement: Step 1: Prepare powder particles for spraying: The SAM2X5 amorphous alloy powder was dried in an oven to obtain alloy powder for spraying; ZG04Cr16Ni5Mo stainless steel powder and WC ceramic powder were ball-milled and mixed in proportion, and then dried to obtain stainless steel / ceramic powder; Step 2: HVOF preparation of erosion-resistant coating: The alloy powder obtained in step 1 is loaded into the HVOF equipment, and the supersonic flame spraying parameters are adjusted to spray the anti-erosion coating on the pretreated blade surface; Step 3, HVOF composite anti-cavitation coating: The blade containing the anti-erosion coating obtained in step 2 is placed in an HVOF device loaded with stainless steel / ceramic powder, and a composite anti-cavitation coating is sprayed by supersonic flame to obtain an inorganic double-layer anti-erosion coating; Step 4: Alternate spraying to prepare a corrosion-resistant multilayer coating: According to the operations of step 2 and step 3, the anti-erosion coating and the anti-cavitation coating are sprayed alternately layer by layer on the inorganic double-layer anti-corrosion coating to obtain a long-lasting anti-corrosion multi-layer coating.

2. The method for preparing a long-lasting corrosion-resistant multi-layer coating on the surface of a turbine blade according to claim 1, characterized in that: The SAM2X5 amorphous alloy powder in step 1 is Fe2O3 without organic binder and with a particle size of 25 to 35 μm. 49.7 Cr 17.7 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 Iron-based amorphous alloy powder; the mass percentages of ZG04Cr16Ni5Mo stainless steel powder and WC ceramic powder are 75% to 76% and 24% to 25% respectively, and the sum of the two is 100%. The ZG04Cr16Ni5Mo stainless steel powder is composed of the following powders by mass fraction: C powder: 0.053~0.065%, Cr powder: 15.17~15.93%, Ni powder: 4.82~5.91%, Mo powder: 0.87~1.03%, Mn powder: 0.45~0.88%, Si powder: 0.35~0.529%, Cu powder: 0.03~0.04%, P powder: 0.005~0.016%, S powder: 0.002~0.005%, Fe powder: 75.595~78.25%, the sum of the above components is 100%, ZG04C The particle size of r16Ni5Mo stainless steel powder is 5-50μm; the particle size of WC ceramic powder is 5-25μm, the ball mill speed is 200-300r / min, the ball milling time is 1-2h, the ball-to-material mass ratio is 2:1, the SAM2X5 amorphous alloy powder is dried in an oven at a temperature of 100-120℃, and the drying time is 2-4h. The drying temperature of ZG04Cr16Ni5Mo stainless steel powder and WC ceramic powder after ball milling is 100-120℃, and the drying time is 2-4h.

3. The method for preparing a long-lasting corrosion-resistant multi-layer coating on the surface of a turbine blade according to claim 1, characterized in that: In step 2, the HVOF equipment uses kerosene as fuel, with a kerosene flow rate of 20.8 to 29.7 L / h; oxygen as the combustion-supporting gas, with an oxygen flow rate of 830 to 940 L / min; nitrogen as the powder feeding gas, with a nitrogen flow rate of 11.5 to 14.0 L / min; the powder feeding rate is 48 to 60 g / min, the spraying distance is 350 to 380 mm, and the spray gun scanning speed is 375 to 500 mm / s.

4. The method for preparing a long-lasting corrosion-resistant multi-layer coating on the surface of a turbine blade according to claim 1, characterized in that: The pretreatment of the blades in step 2 includes surface cleaning and degreasing and sandblasting roughening.

5. The method for preparing a long-lasting corrosion-resistant multi-layer coating on the surface of a turbine blade according to claim 1, characterized in that: In step 3, the HVOF equipment uses kerosene as fuel with a kerosene flow rate of 40.0 to 42.5 L / min, oxygen as the combustion-supporting gas with an oxygen flow rate of 237 to 252 L / min, and nitrogen as the powder feeding gas with a nitrogen flow rate of 348 to 370 L / min; the powder feeding rate is 39.5 to 42.0 g / min, the spraying distance is 250 to 260 mm, and the spray gun scanning speed is 250 to 260 mm / s.

6. The method for preparing a long-lasting corrosion-resistant multi-layer coating on the surface of a turbine blade according to claim 1, characterized in that: In step 4, the anti-erosion coating and the anti-cavitation coating are alternately sprayed 6 to 9 times.

7. The method for preparing a long-lasting corrosion-resistant multi-layer coating on the surface of a turbine blade according to claim 1, characterized in that: The thickness of each layer of the anti-erosion coating is 0.5 to 1 mm, and the thickness of each layer of the anti-cavitation coating is 0.3 to 0.6 mm.

8. The long-lasting corrosion-resistant multilayer coating prepared by the method for preparing a long-lasting corrosion-resistant multilayer coating on the surface of a turbine blade according to any one of claims 1 to 7 is characterized in that: From the inside to the outside, it is composed of an anti-erosion coating and an anti-cavitation coating alternately sprayed on the blade substrate, wherein the anti-erosion coating and the anti-cavitation coating each have 7 to 10 layers.

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