Preparation method of coating suitable for narrow flow channel between runner blades of water pump turbine
阅读说明：本技术 适用于水泵水轮机转轮叶片间狭窄流道的涂层制备方法 (Preparation method of coating suitable for narrow flow channel between runner blades of water pump turbine ) 是由 陈小明 伏利 刘德有 方勇 赵坚 毛鹏展 刘伟 张凯 张磊 霍嘉翔 苏建灏 于 2021-08-10 设计创作，主要内容包括：本发明公开了一种适用于水泵水轮机转轮叶片间狭窄流道的涂层制备方法,是先在需焊接为一体的各部件上先喷涂特制涂层,将各部件进行焊接后再进行常规退火去应力处理；所述的特制涂层包括WC基内层和NiCrAl基面层。该涂层极适用于水泵水轮机转轮叶片间这类狭窄流道先喷涂后焊接的工艺,利用面层可以很好的阻挡800℃～1000℃高温处理对内层的破坏,使内层稳定发挥抗磨抗汽蚀的性能。本发明的方案解决了水泵、水轮机转轮叶片间狭窄流道先喷后焊及高温退火时涂层失效问题。(The invention discloses a preparation method of a coating suitable for a narrow flow passage between runner blades of a water pump turbine, which comprises the steps of firstly spraying a special coating on each part needing to be welded into a whole, welding each part and then carrying out conventional annealing stress removal treatment; the special coating comprises a WC base inner layer and a NiCrAl base surface layer. The coating is extremely suitable for the process of spraying and welding narrow flow passages among runner blades of a water pump turbine, and the damage to the inner layer caused by high-temperature treatment at 800-1000 ℃ can be well prevented by utilizing the surface layer, so that the inner layer can stably exert the performances of wear resistance and cavitation resistance. The scheme of the invention solves the problem that the coating fails when a narrow flow passage between the blades of the water pump and the water turbine is sprayed firstly and then welded and annealed at high temperature.)
1. The preparation method of the coating suitable for the narrow flow passage between the runner blades of the water pump turbine is characterized in that a special coating is firstly sprayed on each part needing to be welded into a whole, and the welding and the conventional annealing stress-relief treatment are carried out on each part; the special coating comprises a WC-based inner layer and a NiCrAl-based surface layer, wherein the WC-based inner layer comprises the following components in percentage by mass: 8-9.5%, Cr: 3-6%, Y or Y2O3: 0.3-1.5% and WC (wolfram carbide), wherein the NiCrAl base surface layer comprises the following components: 25-30% of Al: 8 to 12% of Y2O3: 0.3 to 1.5%, Ta: 2-5% and the balance of Ni.
2. The method for preparing the coating suitable for the narrow flow passage between the blades of the runner of the water pump turbine as claimed in claim 1, wherein the WC-based inner layer and the NiCrAl-based surface layer in the specially-made coating are both prepared by HVAF, HVOF or explosion spraying.
3. The method for preparing the coating suitable for the narrow flow passage between the blades of the runner of the pump turbine as claimed in claim 1, wherein the preparation of the special coating comprises the following steps:
1) weighing WC powder, Co powder, Cr powder, and Y or Y according to a ratio2O3Mixing the powder, adding alcohol and polyethylene glycol, and fully mixing in a ball mill for 20-30 hours; spray drying and granulating the prepared slurry by adopting water atomization or alcohol atomization, sintering the granulated powder in a hydrogen atmosphere at the sintering temperature of 1000-1250 ℃, and crushing and screening after sintering to obtain inner-layer composite powder; spreading and drying;
2) weighing Ni powder, Cr powder, Al powder, Ta powder and Y or Y according to the proportion2O3Ball milling and mixing the powder for 12 to 18 hours, and then adopting water mistCarrying out spray drying granulation on the prepared slurry by chemical or alcohol atomization, sintering the granulated powder in a hydrogen atmosphere at the sintering temperature of 1000-1250 ℃, and then crushing and screening to obtain surface layer composite powder; spreading and drying;
3) cleaning the surface of a sprayed substrate by using acetone or alcohol, drying, removing oil stain and dirt on the surface, and then carrying out rust removal and roughening treatment on the surface of the sprayed substrate by using an aerodynamic sand blasting method;
4) firstly, spraying inner layer composite powder on the surface of a sprayed substrate by adopting HVAF, HVOF or explosion spraying, and then spraying surface layer composite powder by adopting HVAF, HVOF or explosion spraying to obtain a special coating.
4. The preparation method of the coating suitable for the narrow flow passage between the blades of the runner of the pump turbine as claimed in claim 3, wherein the granularity of the WC powder is 5-60 μm, and the granularity of the surface layer composite powder is controlled to be 10-55 μm.
5. The method for preparing a coating suitable for a narrow flow passage between runner blades of a hydroturbine according to claim 3, wherein the particle size of the NiCrAl-based powder is controlled to be 5-65 μm.
6. The method for preparing the coating suitable for the narrow flow passage between the runner blades of the pump turbine as claimed in claim 3, wherein the sand blasting treatment is performed by using 20-30 meshes of white corundum or brown corundum, the pressure of compressed air during sand blasting is 0.4-0.6 MPa, the sand blasting distance is 100-150 mm, and the sand blasting angle is 65-90 °.
Technical Field
The invention belongs to the technical field of hydraulic machinery coatings, and relates to a preparation method of a coating suitable for a narrow flow passage between runner blades of a water pump turbine.
Background
Water pumps and water turbines are key equipment of hydraulic machinery. The hydropower stations in the whole country have 46758 seats and pump stations 424451 seats, wherein the number of the hydropower stations above the scale is 22190 seats and 89063 seats.
Wherein 30-40% of hydraulic equipment such as water turbines, water pumps and the like are damaged by silt abrasion and cavitation in the using process, and the problem is very serious. Under the conditions of high sediment erosion and cavitation damage, the service life of the water pump is often difficult to exceed 1 year, the water pump with high lift is scrapped after running for more than 1000 hours, economic loss of hundreds of billions of yuan RMB is caused every year, even disastrous accidents are caused, environmental pollution and a large amount of resources and energy waste are caused, and urgent solution is needed. At present, the coating is prepared on the surface of the water pump and the water turbine runner blade by a common thermal spraying technology at home and abroad to improve the abrasion resistance and the cavitation resistance of hydraulic equipment.
At present, in practical engineering application, abrasion-resistant and cavitation-resistant coatings are prepared on water pump and turbine rotating wheels by welding and spraying, so that the welded water pump and turbine rotating wheel blades are narrow in space, and the abrasion-resistant and cavitation-resistant coatings cannot be prepared due to insufficient spraying distance. The method for solving the problem can adopt a mode of spraying first and then welding, however, the mode of spraying first and then welding often has the problems: firstly spraying and then welding, wherein the temperature of a welding heat affected zone is usually as high as 800-1000 ℃, and the welded rotating wheel needs to be annealed and destressed at the high temperature of 860 ℃, however, the performance of the conventional WC abrasion-resistant coating fails at the high temperature of more than 480 ℃, and the coating can not play the roles of abrasion resistance and cavitation resistance protection. Therefore, the invention mainly solves the preparation problem of the coating in the narrow flow passage between the water pump and the water turbine runner blades, and through designing the components and the structure of the coating, the coating can be ensured not to lose efficacy in a mode of welding after spraying the coating, and the combination of the environmental protection property, the high efficiency and the practicability of the coating is realized.
Disclosure of Invention
The invention aims to provide a preparation method of a coating suitable for a narrow runner between water pump and turbine runner blades, aiming at solving the problem that the coating is easy to lose efficacy due to high temperature and high temperature annealing generated when the existing narrow runner between the water pump and turbine runner blades is sprayed and welded, and the coating sprayed by the method can resist the high temperature oxidation problem generated by welding and subsequent annealing stress removal, so that the abrasion resistance and cavitation resistance of the coating are ensured.
The technical scheme adopted by the invention is as follows:
the preparation method of the coating suitable for the narrow flow passage between the runner blades of the water pump turbine comprises the steps of firstly spraying a special coating on each part needing to be welded into a whole, welding each part and then carrying out conventional annealing stress removal treatment; the special coating comprises a WC-based inner layer and a NiCrAl-based surface layer, wherein the WC-based inner layer comprises the following components in percentage by mass: 8-9.5%, Cr: 3-6%, Y or Y2O3: 0.3-1.5% of WC (wolfram carbide) balance, and the NiCrAl base surface layerThe method comprises the following steps of: 25-30% of Al: 8 to 12% of Y2O3: 0.3 to 1.5%, Ta: 2-5% and the balance of Ni.
In the technical scheme, the WC-based inner layer and the NiCrAl-based surface layer in the special coating are both prepared by HVAF, HVOF or explosion spraying.
The preparation of the special coating comprises the following steps:
1) weighing WC powder, Co powder, Cr powder, and Y or Y according to a ratio2O3Mixing the powder, adding alcohol and polyethylene glycol, and fully mixing in a ball mill for 20-30 hours; spray drying and granulating the prepared slurry by adopting water atomization or alcohol atomization, sintering the granulated powder in a hydrogen atmosphere at the sintering temperature of 1000-1250 ℃, and crushing and screening after sintering to obtain inner-layer composite powder; spreading and drying;
2) weighing Ni powder, Cr powder, Al powder, Ta powder and Y or Y according to the proportion2O3Ball-milling and mixing the powder for 12-18 hours, then carrying out spray drying granulation on the prepared slurry by adopting water atomization or alcohol atomization, sintering the granulated powder in a hydrogen atmosphere at the sintering temperature of 1000-1250 ℃, and then crushing and screening to obtain surface layer composite powder; spreading and drying;
3) cleaning the surface of a sprayed substrate by using acetone or alcohol, drying, removing oil stain and dirt on the surface, and then carrying out rust removal and roughening treatment on the surface of the sprayed substrate by using an aerodynamic sand blasting method;
4) firstly, spraying inner layer composite powder on the surface of a sprayed substrate by adopting HVAF, HVOF or explosion spraying, and then spraying surface layer composite powder by adopting HVAF, HVOF or explosion spraying to obtain a special coating.
Wherein the granularity of the WC powder is 5-60 mu m, and the granularity of the surface layer composite powder is controlled to be 10-55 mu m.
The particle size of the NiCrAl-based powder needs to be controlled to be 5-65 mu m.
The sand blasting treatment adopts 20-30 meshes of white corundum or brown corundum, the pressure of compressed air during sand blasting is 0.4-0.6 MPa, the sand blasting distance is 100-150 mm, and the sand blasting angle is 65-90 degrees.
The invention is provided by containing Y or Y2O3And a WC-based inner layer of2O3Coating composed of NiCrAl base surface layer of Ta, using Y2O3The coating is extremely suitable for the process of spraying and welding narrow flow passages between water pump turbine runner blades, and the like, wherein the narrow flow passages are formed by spraying the coating firstly, the surface layer in the coating can well prevent the damage of high-temperature treatment at 800-1000 ℃ to the inner layer, and the inner layer can stably exert the performances of abrasion resistance and cavitation resistance. The scheme of the invention solves the problem that the coating fails when a narrow flow passage between the blades of the water pump and the water turbine is sprayed firstly and then welded and annealed at high temperature. The method is low in production cost, reliable in process and stable in performance, and is suitable for large-scale application on water conservancy machinery in a freshwater environment and marine facilities such as steam turbines, ocean current power generation and ships.
Detailed Description
The invention is further illustrated by the following examples.
When preparing the inner layer of the coating, the HVOF adopted in the embodiment of the invention is HV-50 type supersonic flame spraying equipment, the kerosene flow is 21-28L/h, the kerosene pressure is 1.5-1.7 MPa, the oxygen flow is 780-910L/min, the oxygen pressure is 1.7-2.2 MPa, the nitrogen flow is 9-13L/min, the nitrogen pressure is 0.7-1.3 MPa, the powder feeding rate is as follows: 60-80 g/min, and the spraying distance is 350-400 mm.
In another embodiment of the invention, HVAF is adopted as spraying equipment, and the compressed air: 80-84 PSI, propane: 80-82 PSI, nitrogen flow: 20-30 slpm, hydrogen flow: 20-40 slpm, the powder feeding rate of 50-65 g/min and the spraying distance of 180-250 mm.
In another embodiment of the invention, the CCDS2000 explosion spraying equipment is adopted as explosion spraying equipment, and the oxygen-fuel ratio is as follows: 1.0-1.2, the spraying distance is: 220-270 mm, the powder feeding speed is 45-60 g/min, and the moving speed of the spray gun is 48-56 mm/s.
When the surface layer of the coating is prepared, spraying parameters are optimized according to the porosity, the porosity is reduced as much as possible, particularly, the thickness of the surface layer is more than or equal to 150um, the thickness is preferably more than or equal to 180um, the thickness of the single-pass spraying is controlled to be less than or equal to 12um, and through holes are prevented from existing through multiple overlapping;
in one embodiment of the invention, the HVOF is HV-50 type supersonic flame spraying equipment, the kerosene flow is 20-28L/h, the kerosene pressure is 1.5-1.7 MPa, the oxygen flow is 810-910L/min, the oxygen pressure is 1.8-2.2 MPa, the nitrogen flow is 8-12L/min, the nitrogen pressure is 0.8-1.2 MPa, and the spraying distance is 335-400 mm.
In another embodiment of the invention, HVAF is adopted as spraying equipment, and the compressed air: 85-90 PSI, propane: 80-84 PSI, nitrogen flow: 20-30 slpm, the powder feeding rate of 40-60 g/min and the spraying distance of 170-250 mm.
In another embodiment of the invention, the CCDS2000 explosion spraying equipment is adopted as explosion spraying equipment, and the oxygen-fuel ratio is as follows: 1.0-1.1, the spraying distance is: 130-200 mm, powder feeding speed of 40-60 g/min, and spray gun moving speed of 35-50 mm/s.
According to the mass ratio of the inner layer Co: 8-9.5%, Cr: 3-6%, Y or Y2O3: 0.3-1.5% of WC, and weighing WC powder, Co powder, Cr powder, and Y or Y2O3Mixing the powder, wherein the granularity of WC powder is 5-60 mu m, adding alcohol and polyethylene glycol, and fully mixing in a ball mill for 20-30 hours; performing spray drying granulation on the prepared slurry by adopting water atomization or alcohol atomization, sintering the granulated powder in a hydrogen atmosphere at the sintering temperature of 1000-1250 ℃, crushing and screening after sintering, and controlling the particle size to be 10-55 mu m to obtain inner-layer composite powder; and Cr: 25-30% of Al: 8 to 12% of Y2O3: 0.3 to 1.5%, Ta: 2-5% of Ni, and the balance of Ni, weighing Ni powder, Cr powder, Al powder, Ta powder, and Y or Y2O3Ball milling and mixing the powder for 12-18 hours, then adopting water atomization or alcohol atomization to spray dry and granulate the prepared slurry, sintering the granulated powder in hydrogen atmosphere, and keeping the sintering temperatureControlling the particle size to be 5-65 mu m at the temperature of 1000-1250 ℃ to obtain surface layer composite powder; and respectively spreading the inner layer composite powder and the surface layer composite powder, and drying in an insulation box at the insulation temperature of 100-120 ℃ for 3 hours.
In the embodiment of the invention, 2205 stainless steel is cleaned by acetone on the surface of the base material, and is dried in a heat preservation box at 40 ℃ to remove oil stains on the surface. The surface of the spraying base body is subjected to rust removal and texturing treatment by adopting an aerodynamic sand blasting method, white corundum with 20-30 meshes is selected for the sand blasting treatment, the pressure of compressed air during sand blasting is 0.4-0.6 MPa, the sand blasting distance is 100-150 mm, and the sand blasting angle is 65-90 degrees.
The spraying substrate in the embodiment of the invention can adopt 0Cr13Ni5Mo steel, 45 steel, Q345 steel or 2205 stainless steel.
Example 1
The powder is dried according to the implementation method, the matrix 0Cr13Ni5Mo steel is cleaned and subjected to sand blasting texturing treatment, and the coating is reserved.
Firstly, preparing a WC base inner layer by adopting HVOF, wherein the kerosene flow is 23.5L/h, the kerosene pressure is 1.7MPa, the oxygen flow is 845L/min, the oxygen pressure is 2.0MPa, the nitrogen flow is 10L/min, the nitrogen pressure is 1.0MPa, and the spraying distance is 380 mm. The WC-based inner layer had a thickness of 250. mu.m.
Preparing a NiCrAl base surface layer by adopting HVAF, compressing air: 85PSI, propane: 82PSI, nitrogen flow: 26slpm, powder feeding rate of 50g/min, spraying distance of 200 mm. The NiCrAl basal layer thickness was 160 μm.
The porosity of the WC-based inner layer is 0.57%, the microhardness is 1227HV, and the bonding strength is 80 MPa. The porosity of the NiCrAl base surface layer is 0.71%, and the average microhardness is 260 HV; the tensile strength of the coating is 60 MPa. The abrasion resistance of the WC-based inner layer is 20 times that of the matrix; the NiCrAl-based surface layer can resist the high-temperature treatment of more than or equal to 860 ℃.
Example 2
And drying the powder according to the implementation method, cleaning the 45 steel substrate, performing sand blasting texturing treatment, and spraying for later use.
Firstly, preparing a WC-based inner layer by adopting HVAF (high pressure atomic absorption Spectrometry), compressing air: 81PSI, propane: 82PSI, nitrogen flow: 25slpm, hydrogen flow rate: 30slpm, powder feeding rate of 60g/min and spraying distance of 220 mm. The WC-based inner layer had a thickness of 240 μm.
And preparing a NiCrAl base surface layer by adopting HVOF, wherein the kerosene flow is 26L/h, the kerosene pressure is 1.6MPa, the oxygen flow is 855L/min, the oxygen pressure is 2.0MPa, the nitrogen flow is 10L/min, the nitrogen pressure is 1.0MPa, and the spraying distance is 370 mm. The NiCrAl basal layer thickness was 180 μm.
The porosity of the WC-based inner layer is 0.68%, the microhardness is 1227HV, and the bonding strength is 75 MPa. The porosity of the NiCrAl base surface layer is 0.87 percent, and the average microhardness is 310 HV; the tensile strength of the coating is 62 MPa. The abrasion resistance of the WC-based inner layer is 18 times that of the matrix; the NiCrAl base surface layer can resist high temperature treatment of not less than 950 ℃.
Example 3
And drying the powder according to the implementation method, cleaning the substrate Q345 steel, performing sand blasting texturing treatment, and spraying for later use.
Firstly, preparing a WC base inner layer by adopting HVOF, wherein the kerosene flow is 25L/h, the kerosene pressure is 1.7MPa, the oxygen flow is 860L/min, the oxygen pressure is 2.0MPa, the nitrogen flow is 10L/min, the nitrogen pressure is 1.0MPa, and the spraying distance is 390 mm. The WC-based inner layer had a thickness of 230. mu.m.
Then, preparing a NiCrAl base surface layer by adopting CCDS2000 explosion spraying equipment, wherein the oxygen-fuel ratio is as follows: 1.08, the spraying distance is as follows: 150mm, the powder feeding speed is 50g/min, and the moving speed of the spray gun is 40 mm/s. The thickness of the top layer was 200. mu.m.
The porosity of the WC-based inner layer is 0.66%, the microhardness is 1206HV, and the bonding strength is 82 MPa. The porosity of the NiCrAl base surface layer is 0.92 percent, and the average microhardness is 350 HV; the tensile strength of the coating is 63 MPa. The abrasion resistance of the WC-based inner layer is 17 times that of the matrix; the NiCrAl base surface layer can resist high temperature treatment of more than or equal to 900 ℃.
Example 4
The powder is dried according to the implementation method, the substrate 2205 stainless steel is cleaned and subjected to sand blasting texturing treatment, and the powder is sprayed for standby.
Firstly, preparing a WC base inner layer by adopting CCDS2000 explosion spraying equipment as explosion spraying equipment, wherein the oxygen-fuel ratio is as follows: 1.10, the spraying distance is as follows: 250mm, powder feeding speed of 60g/min and spray gun moving speed of 52 mm/s. The WC-based inner layer had a thickness of 220 μm.
And preparing a NiCrAl base surface layer by adopting HVOF, wherein the kerosene flow is 24.5L/h, the kerosene pressure is 1.7MPa, the oxygen flow is 850L/min, the oxygen pressure is 2.0MPa, the nitrogen flow is 10L/min, the nitrogen pressure is 1.0MPa, and the spraying distance is 385 mm. The NiCrAl basal layer thickness was 200. mu.m.
The porosity of the WC-based inner layer is 0.75%, the microhardness is 1277HV, and the bonding strength is 90 MPa. The porosity of the NiCrAl base surface layer is 0.94 percent, and the average microhardness is 335 HV; the tensile strength of the coating is 61 MPa. The abrasion resistance of the WC-based inner layer is 18 times that of the matrix; the NiCrAl base surface layer can resist high temperature treatment at 1000 ℃.
Example 5
The powder is dried according to the implementation method, the matrix 0Cr13Ni5Mo steel is cleaned and subjected to sand blasting texturing treatment, and the coating is reserved.
Firstly, preparing a WC base inner layer by adopting CCDS2000 explosion spraying equipment as explosion spraying equipment, wherein the oxygen-fuel ratio is as follows: 1.10, the spraying distance is as follows: 250mm, powder feeding speed of 60g/min and spray gun moving speed of 52 mm/s. The WC-based inner layer had a thickness of 200. mu.m.
Firstly preparing a NiCrAl base surface layer by adopting HVAF, compressing air: 90PSI, propane: 84PSI, nitrogen flow: 30slpm, hydrogen flow rate: 40slpm, powder feeding rate of 65g/min and spraying distance of 190 mm. The NiCrAl basal layer thickness was 180 μm.
The porosity of the WC-based inner layer is 0.81%, the microhardness is 1230HV, and the bonding strength is 85 MPa. The porosity of the NiCrAl base surface layer is 0.98 percent, and the average microhardness is 320 HV; the tensile strength of the coating is 65 MPa. The abrasion resistance of the WC-based inner layer is 19 times that of the matrix; the NiCrAl-based surface layer can resist the high-temperature treatment of more than or equal to 860 ℃.
Example 6
The powder is dried according to the implementation method, the matrix 0Cr13Ni5Mo steel is cleaned and subjected to sand blasting texturing treatment, and the coating is reserved.
Firstly, preparing a WC base inner layer by adopting HVOF, wherein the kerosene flow is 23.5L/h, the kerosene pressure is 1.7MPa, the oxygen flow is 845L/min, the oxygen pressure is 2.0MPa, the nitrogen flow is 10L/min, the nitrogen pressure is 1.0MPa, and the spraying distance is 380 mm. The WC-based inner layer had a thickness of 250. mu.m.
The surface layer is not prepared, the high-temperature treatment at 800 ℃ is directly carried out, and the coating completely falls off from the matrix and is oxidized to change color.