Water turbine blade surface composite coating and high-speed laser cladding preparation method and application

Abstract

The invention discloses a water turbine blade surface composite coating and a high-speed laser cladding preparation method and application, and belongs to the technical field of hydroelectric equipment surface protective coating preparation. The method comprises the steps that a matrix phase and a reinforcing phase are subjected to ball milling mixing, and metal ceramic composite powder is obtained; depositing metal ceramic composite powder on the surface of the pretreated water turbine blade by using a high-speed laser cladding technology to obtain a water turbine blade surface composite coating; the matrix phase is a nano / submicron authigenic ceramic phase composite nickel-based alloy; and the reinforcing phase is micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles. The multi-stage composite coating is prepared on the surface of the water turbine blade, so that the erosion-wear resistance and the obdurability are improved, the stress cracking in the cladding process is resisted, and the stripping of a hard phase in the erosion-wear process is reduced. And the multi-stage reinforced phase particles play a synergistic shadow protection role in the coating, so that the erosion-wear resistance of gravel is improved, and a new path is provided for long-acting protection and repair of the surface of the water turbine blade.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of surface protective coating preparation of hydroelectric equipment, and particularly relates to a surface composite coating of a water turbine blade and a high-speed laser cladding preparation method and application. BACKGROUND

[0002] The water turbine unit is the core equipment of hydroelectric power generation. The flow parts such as the water turbine blade, the water turbine pump and the pipeline suffer severe erosion-wear damage from silt and other substances during service, resulting in the appearance of holes and pits and other damage on the surface of the key parts such as the water turbine blade, which not only affects the stable operation period and safe service life of the water turbine equipment, but also reduces its operating efficiency, causing huge economic losses. Therefore, it is necessary to prepare a protective coating with excellent erosion-wear resistance on the surface of the key flow parts such as the water turbine blade, so as to significantly improve the erosion-wear resistance of the water turbine blade substrate, thereby improving its service life and working efficiency and reducing the operation and maintenance cost.

[0003] At present, the commonly used surface protection technologies for the flow parts of the water turbine unit equipment mainly include surfacing, thermal spraying and laser cladding. Compared with the surfacing and thermal spraying technologies, laser cladding not only can obtain a metallurgical bonding coating, but also can effectively control the dilution rate of the coating, the heat affected zone of the substrate and the thermal deformation, showing greater application potential in the preparation of surface protective coatings for water turbine blades. For example, the Chinese patent application with publication number CN112663044B discloses a cobalt-based alloy laser cladding powder for water turbine blades and a laser cladding method thereof, which prepares a cladding layer with dense structure and fine grains, effectively improving the wear resistance, corrosion resistance and cavitation resistance of the cladding layer. The Chinese patent application with publication number CN116397225A discloses a laser cladding material resistant to cavitation and its application in the surface repair of flow parts of a hydroelectric power station, which obtains a laser cladding coating with high chemical stability, high hardness, wear resistance and metal toughness, showing good cavitation and erosion resistance. However, the traditional laser cladding technology has low preparation efficiency, which greatly limits its application in the surface protection field of key parts such as water turbine blades. In recent years, high-speed laser cladding technology has emerged, which significantly improves the processing efficiency and reduces the dilution rate of the coating compared with the traditional laser cladding technology, and promotes the grain refinement of the coating, which is beneficial to improve its wear and corrosion resistance.

[0004] Currently used erosion-wear resistant coatings are mainly divided into metal coatings and ceramic coatings. Metal coatings have good corrosion resistance and laser cladding processing performance, but their hardness is relatively low and their erosion-wear resistance is insufficient. Ceramic coatings have the advantages of high hardness and high corrosion resistance, but their poor plasticity and toughness lead to severe cracking during the laser cladding process, making it difficult to obtain a defect-free coating. Therefore, it is necessary to develop new composite coating materials that combine excellent erosion-wear resistance and laser cladding processing performance. The coating must not only exhibit high hardness to significantly improve the erosion-wear resistance of the turbine blade surface, but also have good plasticity and toughness to solve the problem of coating cracking during high-speed laser cladding. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a composite coating on the surface of turbine blades and a high-speed laser cladding preparation method and application to solve the technical problem of severe damage to turbine blades under severe erosion-wear conditions.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a high-speed laser cladding method for preparing a composite coating on the surface of a turbine blade, comprising the following steps: The matrix phase and the reinforcement phase are mechanically ball-milled to obtain a metal-ceramic composite powder; Using high-speed laser cladding technology, metal-ceramic composite powder is deposited on the pre-treated surface of the turbine blade to obtain a composite coating on the turbine blade surface; The composite coating on the surface of turbine blades is a nano / submicron / micron multi-level composite reinforcement structure; The matrix phase of the composite coating on the surface of the turbine blade is a nano / submicron self-generated ceramic phase composite nickel-based alloy, and the reinforcement phase is micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles; The laser power of high-speed laser cladding technology is 1000~3000W; the laser scanning rate is ≥5000mm / min, and the overlap rate is ≥70%.

[0007] Preferably, the content of the reinforcement phase in the metal-ceramic composite powder is 10% to 70%.

[0008] Preferably, in the nano / submicron in-situ ceramic phase composite nickel-based alloy, the mass fraction of Cr is ≥15%; the melting point is ≤1400°C; the hardness is 250-500 HV; and the particle size is 30-105 μm.

[0009] Preferably, in the micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles, the Mo content is 35% to 45%, the B content is 3% to 5%, the Ti content is 1% to 3%, the Cr content is 5.5% to 9.5%, and the rest is Ni; The micron-sized spherical Mo-Ni-B-Ti-Cr cermet composite particles comprise a sub-micron-sized boride ceramic phase and a nickel-based metal binder phase; the sub-micron-sized boride ceramic phase content is greater than or equal to 70%, the hardness is greater than or equal to 1000HV, the fracture toughness is greater than or equal to 15MPa·m 1 / 2 , the melting point is higher than 1400℃, and the particle size is 50-200μm.

[0010] Preferably, the micron-sized spherical Mo-Ni-B-Ti-Cr cermet composite particles are prepared by a vacuum electrode induction melting atomization method, comprising the following steps: The MoB powder, the Ni2B powder, the Ti powder and the Cr powder are ball-mixed, pre-pressed, pre-burned, melted and cooled to obtain a cermet bulk; the cermet bulk is vacuum electrode induction melted and atomized to obtain the micron-sized spherical Mo-Ni-B-Ti-Cr cermet composite particles.

[0011] Preferably, the pre-pressing pressure is greater than or equal to 40MPa; the pre-burning temperature is 800-1000℃; the pre-burning time is 20-60min; The melting conditions comprise: a vacuum degree of less than or equal to 3Pa, a melting temperature of 1500-1800℃, and a holding time of greater than or equal to 20min; The vacuum electrode induction melting atomization conditions comprise: controlling the vacuum degree to be less than or equal to 10 -3 Pa, controlling the rotating speed to be 5-80r / min, controlling the feeding speed to be 3-300mm / min, and controlling the airflow pressure to be 2-6MPa.

[0012] Preferably, the mechanical ball-milling rotating speed is 100-300r / min, and the ball-to-material ratio is (1-5):1.

[0013] Preferably, the high-speed laser cladding technology has a laser power of 1000-3000W; the laser scanning speed is greater than or equal to 5000mm / min, and the overlapping rate is greater than or equal to 70%.

[0014] Preferably, before the high-speed laser cladding, the method further comprises: vacuum drying the cermet composite powder at 120-200℃ for 0.5-3h; Before the high-speed laser cladding, the method further comprises: performing laser scanning preheating treatment on the pretreated surface of the water turbine blade; the laser scanning power is 700-1200W, and the laser scanning speed is 1000-3000mm / min.

[0015] The application further discloses a water turbine blade surface composite coating prepared by the high-speed laser cladding preparation method of the water turbine blade surface composite coating, and the water turbine blade surface composite coating has a thickness of greater than or equal to 300μm and a cladding efficiency of greater than or equal to 0.6m 2 / h; hardness is 800~1100HV; corrosion potential is -0.55~-0.42V; relative erosion wear resistance is 10~25.

[0016] The present invention also discloses the application of the composite coating on the surface of a turbine blade prepared by the high-speed laser cladding preparation method in the surface protection of key components of hydropower generation equipment.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a high-speed laser cladding preparation method for a composite coating on the surface of a turbine blade. By using a high-speed laser cladding technology based on coaxial powder feeding, a multi-level reinforced phase nickel-based composite coating is prepared on the surface of key flow-through components such as turbine blades to greatly improve its erosion-wear resistance. By designing a multi-level composite structure, the strength and toughness of the coating are significantly improved to resist stress cracking during the cladding process, while reducing the peeling of the hard phase during the erosion and wear process. The multi-level reinforced phase particles are used to play a synergistic shadow protection role in the coating, so that its erosion-wear resistance against gravel is significantly better than that of traditional homogeneous coatings. By preferably designing micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles, the bonding phase of which is a Ni solid solution, not only the interface synergy between the large-particle reinforced phase and the nickel-based alloy is guaranteed, but also the potential difference between the reinforced particles and the matrix can be reduced, thereby improving the corrosion resistance of the composite coating. Through this coating system design and cladding strategy selection, the coating cladding efficiency can be greatly improved while ensuring that the coating does not crack significantly, and the erosion-wear resistance of turbine blades can be improved by more than 10 times. This solves the serious cracking problem of high-hardness coatings during high-speed laser cladding, providing a new path for long-term protection of turbine blade surfaces and efficient on-site repair, with important engineering application value. Through the multi-stage composite coating toughness design and cladding strategy optimization, the substrate surface is preheated and pre-phase-transformed using only laser scanning before the cladding process, eliminating the need for long-term preheating and post-heat treatment, significantly simplifying on-site construction procedures and shortening processing cycles.

[0018] Furthermore, by controlling the reinforcing phase content within a specific range of 10% to 70%, a reasonable balance between the coating's toughness and erosion-wear resistance can be achieved. If the reinforcing phase content is too low, the reinforcing phase's full performance-enhancing effect on the coating will be insufficient, effectively failing to improve the coating's erosion-wear resistance. If the content is too high, stress concentration can lead to cracking during the cladding process, compromising coating quality and service life. This content range ensures excellent coating performance while ensuring excellent preparation results, providing reliable, long-term protection for turbine blades and possessing significant engineering value.

[0019] Furthermore, the mass fraction of Cr in the nano / submicron in-situ ceramic phase composite nickel-based alloy is ≥15%. Cr exhibits excellent solid solution strengthening properties in nickel-based alloys, significantly improving the alloy's strength and hardness. Cr also forms a dense oxide film on the alloy surface, effectively enhancing the alloy's corrosion resistance. This is crucial for turbine blades operating under harsh operating conditions, extending their service life and reducing repair and replacement costs due to corrosion and wear. A melting point of ≤1400°C facilitates rapid powder melting and metallurgical bonding with the substrate during high-speed laser cladding, reducing energy consumption and improving cladding efficiency. This reduces the adverse effects of high temperatures on substrate properties, ensuring the overall performance of the substrate is not compromised. A hardness of 250-500 HV allows for optimal coordination with the reinforcement phase, ensuring a certain toughness while imparting sufficient hardness to resist erosion and wear. This allows the coating to operate stably and long-term in complex operating environments, enhancing the reliability and durability of turbine blades. The particle size is 30~105μm, which can ensure the uniform spreading and full melting of the powder during the laser cladding process, which is conducive to the formation of a dense and uniform coating structure, avoiding coating defects such as pores and cracks caused by uneven powder particle size, thereby improving the quality and performance of the coating.

[0020] Furthermore, the micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles contain 35% to 45% Mo, 3% to 5% B, 1% to 3% Ti, 5.5% to 9.5% Cr, and the remainder Ni. Mo, with its high melting point and high hardness, significantly improves the hardness and wear resistance of the composite powder. Ni, as a binder, ensures good bonding between the powder and the matrix, as well as between the various phases. The addition of B contributes to the formation of a boride ceramic phase, further improving the hardness and wear resistance of the coating. Ti refines the grains and improves the toughness of the coating. Cr enhances the coating's corrosion resistance. The precise optimization of the content of each element allows for the full synergistic effect of each element, resulting in the composite powder possessing excellent overall performance. The hardness of the micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles is ≥1000HV, which enables the coating to effectively resist the erosion and wear of hard particles such as gravel, significantly improving the erosion-wear resistance of turbine blades, reducing material loss on the blade surface, and extending the service life of the blades. Fracture toughness ≥15MPa·m 1 / 2, can effectively prevent cracks from occurring and propagating when the coating is subjected to external forces, improve the anti-cracking ability of the coating, ensure the integrity of the coating under complex stress conditions, and thus ensure that the coating can function stably for a long time. The melting point is higher than 1400℃, which enables the composite powder to maintain stable performance during laser cladding and is not prone to phase change or decomposition, which is conducive to forming a coating structure with excellent performance, and can also adapt to the high energy input environment of high-speed laser cladding. The particle size is 50-200μm, which can ensure the flowability and spreadability of the powder during laser cladding, is conducive to forming a uniform and dense coating, improves the bonding strength between the coating and the substrate, reduces defects in the coating, and thus improves the overall performance of the coating. The boride ceramic phase content is ≥70%, which gives the composite powder excellent hardness and wear resistance, and is one of the key factors for the coating to have good anti-erosion-wear performance, which can significantly improve the service life of the water turbine blade in harsh working environment.

[0021] Further, the mechanical ball milling speed is 100-300r / min, which can fully mix the matrix phase and the reinforcing phase, realize uniform powder refinement, and at the same time avoid overheating, oxidation or introduction of too much impurities due to too high speed, which affects the performance of the powder. Suitable speed is conducive to ensuring the uniformity and quality of the cermet composite powder, laying a foundation for preparing high-performance coatings. The ball-to-material ratio is (1-5):1, which can ensure that the powder is subjected to sufficient impact and grinding during ball milling, so that the powder is fully mixed and refined, and at the same time avoid problems such as low ball milling efficiency, powder agglomeration or intensified equipment wear due to too large ball-to-material ratio, improve the stability and efficiency of the ball milling process, and reduce production cost.

[0022] Further, the energy input of high-speed laser cladding technology is low, which can avoid problems such as overheating, deformation and cracking of the coating due to too high energy, and at the same time ensure that the powder can be fully melted and form a good metallurgical bond with the substrate to obtain a high-quality coating. Suitable energy density helps to optimize the organizational structure and performance of the coating, improve the anti-erosion-wear performance and corrosion resistance of the coating. The laser power is 1000-3000W, which can meet the energy requirements for powder melting and bonding with the substrate, and at the same time can be flexibly adjusted according to different powder characteristics and coating requirements. Suitable laser power can ensure the stability and controllability of the cladding process, improve the quality and consistency of the coating. The laser scanning speed is ≥5000mm / min, which can significantly improve the cladding efficiency, shorten the processing time and reduce the production cost. At the same time, fast scanning speed helps to reduce the heat-affected zone, reduce the adverse effects on the performance of the substrate, ensure good bonding between the coating and the substrate, and improve the overall performance and service life of the coating.

[0023] Furthermore, vacuum drying the metal-ceramic composite powder at 120-200°C for 0.5-3 hours effectively removes moisture and impurities from the powder, preventing defects such as pores and cracks caused by water evaporation during the laser cladding process. This improves the density and quality of the coating, ensures good bonding between the coating and the substrate, and thus enhances the coating's performance and reliability. Laser scanning preheating of the pretreated turbine blade surface reduces the temperature gradient between the substrate and the powder, reduces thermal stress during the cladding process, and effectively prevents cracking in the coating. Preheating also improves the wettability of the substrate surface, facilitating powder spreading and bonding, and enhancing the quality and performance of the coating. Laser scanning power of 700-1200W and scanning speed of 1000-3000mm / min ensure that the substrate surface reaches an appropriate temperature, fully maximizing the preheating effect while minimizing the adverse effects of excessive temperatures on substrate performance. Precise control of preheating parameters optimizes the cladding process conditions and improves the efficiency and quality of coating preparation.

[0024] The present invention also discloses a composite coating on the surface of a turbine blade obtained by the above-mentioned preparation method. The composite coating on the surface of the turbine blade has a thickness of ≥300 μm, which can provide sufficient protection for the turbine blade, effectively resist erosion and wear, and extend the service life of the blade. During long-term operation, the thicker coating can better resist erosion from the external harsh environment and reduce material loss on the blade surface. Cladding efficiency ≥0.6m 2 / h, significantly shortening processing time, reducing production costs, and improving production efficiency. This is of great significance for large-scale turbine blade repair and protection projects, meeting the demand for fast and efficient processing in actual production. The hardness ranges from 800 to 1100 HV, giving the coating excellent erosion-wear resistance, effectively resisting the impact and abrasion of hard particles such as gravel, reducing blade surface wear and ensuring the normal operation of the turbine. The appropriate hardness also helps improve the coating's fatigue resistance and extend its service life. The corrosion potential ranges from -0.55 to -0.42 V, indicating that the coating has excellent corrosion resistance and can effectively reduce the corrosion rate of turbine blades in corrosive environments such as those containing water and impurities, reducing blade performance degradation and damage due to corrosion, and improving turbine reliability and safety. The relative erosion wear resistance ranges from 10 to 25, indicating that the coating has higher erosion-wear resistance than traditional coatings, significantly extending the service life of turbine blades in harsh operating environments and reducing maintenance costs. In addition, the content of the large particle reinforcement phase in the multi-stage composite coating prepared by the present invention is ≥10%, and the average hardness of the coating is ≥800 HV, thereby ensuring the excellent erosion-wear resistance of the coating.

[0025] The present invention also discloses the application of the composite coating on the surface of a turbine blade prepared by the high-speed laser cladding preparation method of the composite coating on the surface of a turbine blade in the surface protection of key components of hydropower generation equipment. The application of the composite coating on the surface of a turbine blade in the surface protection of key components of hydropower generation equipment has important engineering application value. By adopting the composite coating obtained by the above preparation method, the erosion-wear resistance and corrosion resistance of key components of hydropower generation equipment, such as turbine blades, can be significantly improved, their service life can be effectively extended, the downtime and maintenance time and cost caused by equipment damage can be reduced, the operating efficiency and reliability of hydropower generation equipment can be improved, the stability of power supply can be guaranteed, and the development of the hydropower generation industry can be actively promoted. At the same time, the preparation method is efficient, simple, and suitable for on-site construction. It provides a new solution for the on-site efficient repair of key components of hydropower generation equipment and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 These are scanning electron microscope images of the surface and cross-section of the micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles prepared in Example 2 of the present invention; wherein (a) is the surface; (b) is the cross-section; Figure 2 This is a scanning electron microscope photograph of a cross section of the composite coating on the surface of a turbine blade prepared in Example 2 of the present invention; Figure 3 The microhardness test results of the composite nickel-based alloy matrix phase composed of micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles, a reinforcement phase, and a nano / submicron in-situ ceramic phase in the composite coating on the surface of the turbine blade prepared in Example 2 of the present invention; Figure 4 This is the X-ray diffraction pattern of the composite coating on the surface of the turbine blade prepared in Example 2 of the present invention; Figure 5 The electrochemical test results of the composite coating on the surface of the turbine blade prepared in Example 2 of the present invention are as follows; Figure 6 This is a scanning electron microscope photograph of a macroscopic cross section of the composite coating on the surface of a turbine blade prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0029] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0030] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.

[0031] In the present invention, unless otherwise specified, the components or preferred components involved can be combined with each other to form a new technical solution.

[0032] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.

[0033] The "range" disclosed in the present invention is in the form of a lower limit and an upper limit, which can be one or more lower limits, and one or more upper limits, respectively.

[0034] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0035] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the sequence. Preferably, the reaction method herein is carried out sequentially.

[0036] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0037] The present invention provides a high-speed laser cladding method for preparing a composite coating on the surface of a turbine blade, comprising the following steps: S1. Select turbine blade steel as the substrate, and grind, clean, sandblast and dry the substrate surface before coating preparation; S2. Select a nano- / submicron in-situ ceramic composite nickel-based alloy as the coating matrix. The Cr mass fraction should be ≥15%, the melting point should be ≤1400°C, and the hardness should be between 250 and 500 HV. The powder particle size should be between 30 and 105 μm. This nano- / submicron in-situ ceramic composite nickel-based alloy has excellent corrosion resistance and ductility to resist cracking during high-speed laser cladding.

[0038] S3. MoB powder, Ni2B powder, Ti powder and Cr powder are used as raw material powders, and a mixed powder with uniform distribution of components is obtained by ball milling. WC-Co grinding balls are selected, and the ball-to-material ratio is controlled to be (1-5):1. Ball milling is carried out under argon protection, the ball milling speed is 100-300 r / min, and the ball milling time is ≥24h; the mixed powder is pre-pressed into a blank and pre-fired, the pre-pressing pressure is ≥40MPa, the pre-fired temperature is 800-1000℃, and the pre-fired time is 20-60min to obtain a prefabricated block; then the prefabricated block is melted and cast in a vacuum induction melting furnace, and the vacuum degree is set to ≤3Pa, the melting temperature is 1500-1800℃, and the holding time is ≥20min to obtain a dense metal ceramic block; then the vacuum electrode induction melting atomization technology is used to control the vacuum degree to ≤10 - 3 Pa, a rotation speed of 5~80r / min, a feed speed of 3~300mm / min, and an air flow pressure of 2~6MPa, and micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles were obtained.

[0039] Micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles are used as the reinforcement phase of the composite coating on the surface of turbine blades. The composition includes: Mo content of 35% to 45%, B content of 3% to 5%, Ti content of 1% to 3%, Cr content of 5.5% to 9.5%, and the remainder is Ni. The micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles include a submicron boride ceramic phase and a nickel-based metal binder phase; the submicron boride ceramic phase content is ≥70%, the particle size is 50 to 200μm, the hardness is ≥1000HV, and the fracture toughness is ≥15MPa·m 1 / 2 , the melting point is higher than 1400℃.

[0040] S4. Mechanically ball-mill the matrix phase and the reinforcement phase, controlling the reinforcement phase content to 10% to 70%. During the mechanical ball-milling process, the rotational speed is 100 to 300 r / min, and the ball-to-material ratio is (1 to 5):1. This ensures that the two powders are evenly mixed after ball milling, resulting in a metal-ceramic composite powder that does not deform the nano- / submicron-scale self-generated ceramic phase composite nickel-based alloy and does not break up the micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles.

[0041] S5. Using high-speed laser cladding technology, a metal-ceramic composite powder is deposited on the pretreated surface of the turbine blade to form a composite coating on the turbine blade surface. The composite coating on the turbine blade surface comprises a nano / submicron in-situ ceramic phase composite nickel-based alloy matrix, submicron ceramic phase reinforced metal-ceramic composite particles, and micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles reinforcing the composite coating.

[0042] Before high-speed laser cladding, the surface of the blade to be repaired is preheated by laser scanning. The laser scanning power is 700~1200W and the laser scanning rate is 1000~3000mm / min to reduce the cracking tendency of the surface coating during the high-speed cladding process.

[0043] During the high-speed laser cladding process, the laser power is 1000~3000W, the laser scanning rate is ≥5000mm / min, and the overlap rate is ≥70%.

[0044] Before high-speed laser cladding, the metal-ceramic composite powder needs to be vacuum dried at 120~200℃ for 0.5~3h to eliminate residual moisture in the powder.

[0045] In the composite coating on the surface of turbine blades, only the surface layer of the micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles is melted and evenly dispersed inside the nano / submicron self-generated ceramic phase composite nickel-based alloy. After the small-particle powder is melted, small-scale reinforcing particles are precipitated to improve the strength and toughness of the coating matrix.

[0046] The erosion-wear resistant composite coating on the surface of the turbine blade prepared by the present invention has a multi-level composite reinforcement structure of large-scale metal ceramic particles and small-scale hard phase particles (such as Figure 1 and Figure 2 As shown), coating thickness ≥300μm, cladding efficiency ≥0.6m 2 / h, and there are no obvious crack defects on the coating surface; the average hardness of the coating is 800~1100HV, the corrosion potential is -0.55~-0.42V; the relative erosion and wear resistance is 10~25, and the erosion and wear resistance is more than 10 times higher than that of the blade substrate.

[0047] The composite coating on the surface of a turbine blade disclosed in the present invention is an erosion-wear protective coating for a sandy liquid environment. It needs to resist the scouring and corrosion of water flow and gravel, and has higher requirements for the impact resistance of the coating. The structure of the composite coating on the surface of the turbine blade is a multi-level reinforced particle composite structure that is erosion-wear resistant, including the reinforcement effect of large-scale Mo-Ni-B-Ti-Cr metal ceramic reinforcement phase on the nickel-based alloy, while the interior of the large-scale reinforcement phase is still a small-scale ceramic particle reinforced composite structure. Through multi-level reinforcement composite, the cladding stress can be effectively reduced, and the high-speed cladding cracking problem can be prevented. At the same time, the coating's resistance to gravel impact can be improved, ensuring higher erosion-wear resistance. Through the coating structure and powder design, auxiliary means such as synchronous pulse laser heating are avoided in the preparation process of the high-speed laser cladding coating, lower requirements are placed on the cladding equipment, and it has better on-site processing applicability.

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0049] Example 1 A high-speed laser cladding method for preparing a composite coating on a surface of a turbine blade comprises the following steps: 1) Using 17-4PH stainless steel plate as the substrate, the substrate surface is polished, cleaned and sandblasted to obtain a clean metal surface, and then dried.

[0050] 2) Spherical Ni45 alloy powder was selected as the matrix phase of the coating, with a Cr content of 15%, a melting point of 1080℃, a hardness of 500 HV, and an average powder particle size of 105μm.

[0051] 3) Micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles were prepared using vacuum electrode induction melting and atomization as a coating composite reinforcement phase. The composition includes: Mo content of 35%, B content of 3%, Ti content of 1%, Cr content of 5.5%, and the remainder is Ni. The micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles contain 70% submicron boride ceramic phase, hardness of 1000 HV, and fracture toughness of 18 MPa·m 1 / 2 , melting point is 1400℃, and average particle size is 200μm.

[0052] The steps of preparing micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles by vacuum electrode induction melting and atomization method include: 31) Pre-sintering of metal ceramic blocks The pre-pressing pressure is controlled to be 50 MPa; the pre-burning temperature is 800°C; and the pre-burning time is 60 minutes. 32) Densification of metal ceramic blocks The vacuum degree was controlled at 3Pa, the melting temperature was 1500℃, and the holding time was 20min; 33) Atomization powder making Control vacuum degree 10 -3Pa, controlled the rotation speed to 5 r / min, the feed speed to 3 mm / min, and the air flow pressure to 6 MPa, and micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles were obtained.

[0053] 4) Weighing Ni45 matrix phase powder and micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles in a mass ratio of 9:1, and mechanically ball milling them at a ball mill speed of 100 r / min and a ball-to-material ratio of 5:1 to obtain a metal ceramic composite powder that is uniformly mixed and has good sphericity.

[0054] 5) Before high-speed laser cladding, the laser scanning power was set to 700 W and the laser scanning rate was set to 1000 mm / min, and laser scanning preheating treatment was performed on the surface of the stainless steel blade; at the same time, the metal-ceramic composite powder was baked at 120°C for 3 hours for drying.

[0055] 6) Using high-speed laser cladding equipment, the laser power was set to 1000 W, the scanning rate was set to 5000 mm / min, the powder feeding rate was set to 0.5 r / min, and the overlap rate between passes was set to 70%. Metal-ceramic composite powder was deposited on the surface of the preheated substrate to obtain a composite coating on the surface of the turbine blade.

[0056] The average thickness of the composite coating on the surface of the turbine blade prepared in Example 1 is about 300 μm, and the cladding efficiency is 0.6 μm. 2 / h, composed of Mo-Ni-B-Ti-Cr metal ceramic particles and nickel matrix, the average hardness of the coating is 800HV, its salt water corrosion resistance is better than that of the substrate, its corrosion potential is -0.55V, and its erosion and wear resistance is 10 times higher than that of the substrate.

[0057] Example 2 A high-speed laser cladding method for preparing a composite coating on a surface of a turbine blade comprises the following steps: 1) Using 17-4PH stainless steel plate as the substrate, the substrate surface is polished, cleaned and sandblasted to obtain a clean metal surface, and then dried.

[0058] 2) Nickel-based 718 alloy powder was selected as the coating matrix phase, with a Cr content of 18%, a melting point of 1300°C, a hardness of 400 HV, and a powder particle size of 30 μm.

[0059] 3) Micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles were prepared using vacuum electrode induction melting and atomization as a coating composite reinforcement phase. The composition includes: Mo content of 40%, B content of 3.6%, Ti content of 2%, Cr content of 9.5%, and the remainder is Ni. The micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles contain 80% submicron boride ceramic phase, hardness of 1048HV, and fracture toughness of 17MPa·m 1 / 2 , melting point is 1480℃, average particle size is 105μm (such as Figure 1 ).

[0060] The steps of preparing micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles by vacuum electrode induction melting and atomization method include: 31) Pre-sintering of metal ceramic blocks The pre-pressing pressure is controlled at 40 MPa; the pre-burning temperature is 1000°C; and the pre-burning time is 20 minutes. 32) Densification of metal ceramic blocks The vacuum degree was controlled at 1Pa, the melting temperature was 1600℃, and the holding time was 25min; 33) Atomization powder making Control vacuum degree 10 -4 Pa, controlled the rotation speed to 40 r / min, the feed speed to 130 mm / min, and the air flow pressure to 2 MPa, and micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles were obtained.

[0061] 4) Weighing nickel-based 718 alloy powder and micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles in a mass ratio of 5:5, and mechanically ball milling them at a speed of 300 r / min and a ball-to-particle ratio of 3:1 to obtain a metal ceramic composite powder that is uniformly mixed and has good sphericity.

[0062] 5) Before high-speed laser cladding, the laser scanning power was set to 900 W and the laser scanning rate was set to 2000 mm / min, and laser scanning preheating treatment was performed on the surface of the stainless steel blade; at the same time, the metal-ceramic composite powder was baked at 200°C for 0.5 h for drying.

[0063] 6) Using high-speed laser cladding equipment, the laser power was set to 2000 W, the scanning rate was set to 8000 mm / min, the powder feeding rate was set to 0.5 r / min, and the overlap rate between passes was set to 80%. Metal-ceramic composite powder was deposited on the surface of the preheated substrate to obtain a composite coating on the surface of the turbine blade.

[0064] The average thickness of the composite coating on the surface of the turbine blade prepared in Example 2 is about 500 μm, and the cladding efficiency is 0.7 μm. 2 / h, the microstructure presents a multi-level composite structure (such as Figure 2 ), the main phase composition is Mo2NiB2 and Ni-based solid solution, the average hardness of the coating is 950HV (such as Figure 4 ), its salt water corrosion resistance is better than that of the base material (such as Figure 5 ), its corrosion potential is -0.53V, and its erosion-wear resistance is 20 times higher than that of the substrate.

[0065] Figure 1 These are scanning electron microscope photographs of the surface and cross-section of the micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles prepared in Example 2 of the present invention; (a) is the surface; (b) is the cross-section; as can be seen from the figure, the micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles are spherical, with a bright white submicron boride ceramic phase inside the powder, and the rest being a nickel-based metal bonding phase.

[0066] Figure 2 This is a cross-sectional scanning electron microscope photograph of the composite coating on the surface of the turbine blade prepared in Example 2 of the present invention; it can be seen from the figure that the composite coating on the surface of the turbine blade is composed of a large-scale micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particle reinforcement phase and a nano / submicron self-generated ceramic phase composite nickel-based alloy matrix phase, the reinforcement phase includes a small-scale submicron-sized Mo2NiB2 ceramic phase and a nickel-based metal bonding phase, and the nano / submicron self-generated ceramic phase composite nickel-based alloy matrix phase of the composite coating on the surface of the turbine blade is composed of a nickel-based alloy and small-scale ceramic particles, presenting a multi-level composite reinforcement structure.

[0067] Figure 3 These are the microhardness test results of the micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particle reinforcement phase and the nano / submicron innate ceramic phase composite nickel-based alloy matrix phase in the composite coating on the surface of the turbine blade prepared in Example 2 of the present invention; as can be seen from the figure, the hardness of the reinforcement phase is higher and the hardness of the matrix phase is lower, and the composite structure of the two can ensure the coating's good erosion and wear resistance and comprehensive mechanical properties.

[0068] Figure 4 This is the X-ray diffraction pattern of the composite coating on the surface of the turbine blade prepared in Example 2 of the present invention; it can be seen from the figure that the prepared composite coating on the surface of the turbine blade is mainly composed of Mo2NiB2 ceramic phase and nickel-based alloy phase.

[0069] Figure 5The electrochemical test results of the composite coating on the surface of the turbine blade prepared in Example 2 of the present invention are shown in the figure. As can be seen from the figure, the corrosion resistance of the composite coating on the surface of the turbine blade prepared is significantly better than that of the 17-4PH stainless steel substrate.

[0070] Figure 6 This is a scanning electron microscope image of a macroscopic cross-section of the composite coating on the surface of a turbine blade prepared in Example 2 of the present invention. The horizontal axis shows E / V vs. SCE. E represents the electrode potential, V represents volts, and vs. SCE represents the potential relative to a saturated calomel electrode (SCE). SCE is used to measure the potential of an electrode in an electrochemical system and reflects the trend of the electrode reaction. The vertical axis shows log I / A cm. -2 ; lg I represents the logarithm of current density; I represents current; A cm -2 The unit of current density is the current passing through an electrode per unit area. Taking its logarithm more clearly demonstrates the differences in current changes at different potentials, facilitating analysis of electrochemical behaviors such as electrode corrosion and passivation. As can be seen from the figure, the composite coating on the turbine blade surface is approximately 500 μm thick, with a uniform structure and no obvious defects such as cracks.

[0071] Example 3 A high-speed laser cladding method for preparing a composite coating on a surface of a turbine blade comprises the following steps: 1) Using 17-4PH stainless steel plate as the substrate, the substrate surface is polished, cleaned and sandblasted to obtain a clean metal surface, and then dried.

[0072] 2) Nickel-based 718 alloy powder was selected as the coating matrix phase, with a Cr content of 18%, a melting point of 1300°C, a hardness of 400 HV, and a powder particle size of 55 μm.

[0073] 3) Micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles were prepared using vacuum electrode induction melting and atomization as a coating composite reinforcement phase. The composition includes: Mo content of 40%, B content of 3.6%, Ti content of 2%, Cr content of 9.5%, and the remainder is Ni. The micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles contain 80% submicron boride ceramic phase, hardness of 1048HV, and fracture toughness of 17MPa·m 1 / 2 , melting point is 1480℃, and average particle size is 50μm.

[0074] The steps of preparing micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles by vacuum electrode induction melting and atomization method include: 31) Pre-sintering of metal ceramic blocks The pre-pressing pressure is controlled at 45 MPa; the pre-burning temperature is 900°C; and the pre-burning time is 40 minutes. 32) Densification of metal ceramic blocks The vacuum degree was controlled at 1Pa, the melting temperature was 1800℃, and the holding time was 20min; 33) Atomization powder making Control vacuum degree 10 -4 Pa, controlled the rotation speed to 80 r / min, the feed speed to 300 mm / min, and the air flow pressure to 5.5 MPa to obtain micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles.

[0075] 4) Weighing nickel-based 718 alloy powder and micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles in a mass ratio of 7:3, and mechanically milling them at a speed of 250 r / min and a ball-to-particle ratio of 4:1 to obtain a metal ceramic composite powder with uniform mixing and good sphericity.

[0076] 5) Before high-speed laser cladding, the laser scanning power was set to 1000 W and the laser scanning rate was set to 2500 mm / min, and laser scanning preheating treatment was performed on the surface of the stainless steel blade; at the same time, the metal-ceramic composite powder was baked at 150°C for 1.5 hours for drying.

[0077] 6) Using high-speed laser cladding equipment, the laser power was set to 2000 W, the scanning rate was set to 10000 mm / min, the powder feeding rate was set to 0.5 r / min, and the overlap rate between passes was set to 85%. Metal-ceramic composite powder was deposited on the surface of the preheated substrate to obtain a composite coating on the surface of the turbine blade.

[0078] The average thickness of the composite coating on the surface of the turbine blade prepared in Example 3 is about 550 μm, and the cladding efficiency is 0.78 m 2 / h, presenting a multi-level composite structure, its main phase composition is Mo2NiB2 and Ni-based solid solution, the average hardness of the coating is 850HV, its salt water corrosion resistance is better than that of the substrate, its corrosion potential is -0.48V, and its erosion-wear resistance is 18 times higher than that of the substrate.

[0079] Example 4 A high-speed laser cladding method for preparing a composite coating on a surface of a turbine blade comprises the following steps: 1) Using 17-4PH stainless steel plate as the substrate, the substrate surface is polished, cleaned and sandblasted to obtain a clean metal surface, and then dried.

[0080] 2) Spherical nickel-based 625 alloy powder was selected as the coating matrix phase, with a Cr content of 22%, a melting point of 1400°C, a hardness of 250HV, and a powder particle size of 80μm.

[0081] 3) Micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles were prepared using vacuum electrode induction melting and atomization as a coating composite reinforcement phase. The composition includes: Mo content of 45%, B content of 5%, Ti content of 3%, Cr content of 6%, and the remainder is Ni. The micron-sized spherical Mo-Ni-B-Ti-Cr metal-ceramic composite particles contain 85% submicron boride ceramic phase, hardness of 1400 HV, and fracture toughness of 15 MPa·m 1 / 2 , melting point is 1500℃, and average particle size is 150μm.

[0082] The steps of preparing micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles by vacuum electrode induction melting and atomization method include: 31) Pre-sintering of metal ceramic blocks The pre-pressing pressure is controlled at 60 MPa; the pre-burning temperature is 850°C; and the pre-burning time is 30 minutes. 32) Densification of metal ceramic blocks The vacuum degree was controlled at 2Pa, the melting temperature was 1700℃, and the holding time was 30min; 33) Atomization powder making Control vacuum degree 10 -4 Pa, controlled the rotation speed to 65 r / min, the feed speed to 200 mm / min, and the air flow pressure to 4.5 MPa to obtain micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles.

[0083] 4) Weighing Ni45 matrix phase powder and micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles in a mass ratio of 7:3, and mechanically ball milling them at a ball mill speed of 200 r / min and a ball-to-material ratio of 1:1 to obtain a metal ceramic composite powder that is uniformly mixed and has good sphericity.

[0084] 5) Before high-speed laser cladding, the laser scanning power was set to 1200 W and the laser scanning rate was set to 3000 mm / min, and laser scanning preheating treatment was performed on the surface of the stainless steel blade; at the same time, the metal-ceramic composite powder was baked at 150°C for 1.5 hours for drying.

[0085] 6) Using high-speed laser cladding equipment, the laser power was set to 3000 W, the scanning rate was set to 11000 mm / min, the powder feeding rate was set to 0.5 r / min, and the overlap rate between passes was set to 85%. Metal-ceramic composite powder was deposited on the surface of the preheated substrate to obtain a composite coating on the surface of the turbine blade.

[0086] The average thickness of the composite coating on the surface of the turbine blade prepared in Example 4 is about 400 μm, and the cladding efficiency is 0.85 μm. 2 / h, composed of Mo-Ni-B-Ti-Cr metal ceramic particles and nickel matrix, the average hardness of the coating is 1100HV, its salt water corrosion resistance is better than that of the substrate, its corrosion potential is -0.42V, and its erosion and wear resistance is 25 times higher than that of the substrate.

[0087] In summary, the present invention combines raw material powder design with high-speed laser cladding technology to produce an erosion- and wear-resistant coating with a multi-level composite structure. This coating exhibits both high hardness and high corrosion resistance, demonstrating excellent resistance to erosion and wear in muddy environments. The relevant key properties of the composite coatings on the surfaces of turbine blades produced in the above examples are shown in the table below.

[0088] Table 1 Comparison of properties of the composite coatings on the surface of turbine blades prepared from the substrate and Examples 1 to 4

[0089] Table 1 is a performance comparison of the composite coatings on the surface of turbine blades prepared by the substrate and Examples 1 to 4. As can be seen from the table, the composite coatings on the surface of turbine blades prepared by the present invention have a hardness of 800 to 1100 HV; a corrosion potential of -0.55 to -0.42 V; and a relative erosion and wear resistance of 10 to 25. Compared with the stainless steel substrate, the composite coatings on the surface of turbine blades exhibit higher hardness and corrosion resistance, and the erosion and wear resistance are improved by more than one order of magnitude, and have good applicability in the field of turbine blade surface protection.

[0090] In summary, the composite coating and high-speed laser cladding preparation method and application disclosed in the present invention are based on the design and preparation of large-scale, micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles with a strong and tough composite structure as the reinforcing phase. A nano / submicron self-generated ceramic phase composite nickel-based alloy with excellent abrasion resistance is selected as the matrix phase. Using low-energy input, high-speed laser cladding rapid deposition technology, a multi-stage composite coating with excellent toughness and corrosion resistance is prepared on the surface of the turbine blade. This coating provides multi-stage shadow protection against liquid-solid erosion and wear, thereby exhibiting excellent erosion and wear resistance. The present invention can effectively reduce erosion and wear damage on the surface of turbine blades, extending their safe service life, and has significant application prospects in the field of surface protection of key components of hydropower generation equipment.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-speed laser cladding method for preparing a composite coating on the surface of a turbine blade, characterized in that: The following steps are involved: The matrix phase and the reinforcement phase are mechanically ball-milled to obtain a metal-ceramic composite powder; Using high-speed laser cladding technology, metal-ceramic composite powder is deposited on the pre-treated surface of the turbine blade to obtain a composite coating on the turbine blade surface; The composite coating on the surface of the turbine blade is a nanometer / submicrometer / micrometer multi-level composite reinforcement structure; The matrix phase in the composite coating on the surface of the turbine blade is a nano / submicron self-generated ceramic phase composite nickel-based alloy, and the reinforcement phase is micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles; The laser power of the high-speed laser cladding technology is 1000~3000W; the laser scanning rate is ≥5000mm / min, and the overlap rate is ≥70%.

2. The high-speed laser cladding method for preparing a composite coating on a turbine blade surface according to claim 1, characterized in that: In the metal-ceramic composite powder, the content of the reinforcement phase is 10% to 70%.

3. The high-speed laser cladding method for preparing a composite coating on a turbine blade surface according to claim 1, characterized in that: In the nano / submicron in-situ ceramic phase composite nickel-based alloy, the mass fraction of Cr is ≥15%; the melting point is ≤1400°C; the hardness is 250-500 HV; and the particle size is 30-105 μm.

4. The high-speed laser cladding method for preparing a composite coating on a turbine blade surface according to claim 1, characterized in that: The micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles have a Mo content of 35% to 45%, a B content of 3% to 5%, a Ti content of 1% to 3%, a Cr content of 5.5% to 9.5%, and the remainder being Ni; The micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles include a submicron-sized boride ceramic phase and a nickel-based metal bonding phase; the submicron-sized boride ceramic phase content is ≥70%, the hardness is ≥1000HV; and the fracture toughness is ≥15MPa·m 1 / 2 ; Melting point is higher than 1400℃; Particle size is 50~200μm.

5. The high-speed laser cladding method for preparing a composite coating on a turbine blade surface according to claim 1, characterized in that: The micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles are produced by vacuum electrode induction melting and atomization method. The following steps are involved: MoB powder, Ni2B powder, Ti powder and Cr powder are ball-milled and mixed, and then pre-pressed, pre-sintered, melted and cooled to obtain a metal ceramic block; the metal ceramic block is subjected to vacuum electrode induction melting and atomization to obtain micron-sized spherical Mo-Ni-B-Ti-Cr metal ceramic composite particles.

6. The high-speed laser cladding method for preparing a composite coating on a turbine blade surface according to claim 5, characterized in that: The pre-pressing pressure is ≥40MPa; the pre-burning temperature is 800-1000°C; and the pre-burning time is 20-60min; The melting conditions include: vacuum degree ≤ 3 Pa, melting temperature 1500-1800° C., and holding time ≥ 20 min; The conditions for vacuum electrode induction melting atomization include: vacuum degree ≤ 10 -3 Pa, the rotation speed is 5~80r / min, the feed speed is 3~300mm / min, and the air flow pressure is 2~6MPa.

7. The high-speed laser cladding method for preparing a composite coating on a turbine blade surface according to claim 1, characterized in that: The rotation speed of the mechanical ball mill is 100-300 r / min, and the ball-to-material ratio is (1-5):

1.

8. The high-speed laser cladding method for preparing a composite coating on a turbine blade surface according to claim 1, characterized in that: Before high-speed laser cladding, the process also includes: vacuum drying the metal-ceramic composite powder at 120-200°C for 0.5-3h; Before high-speed laser cladding, it also includes: laser scanning preheating treatment of the pretreated turbine blade surface; the laser scanning power is 700~1200W, and the laser scanning rate is 1000~3000mm / min.

9. A composite coating on the surface of a turbine blade, characterized in that: The composite coating on the surface of a turbine blade is prepared by the high-speed laser cladding preparation method of any one of claims 1 to 8, wherein the thickness of the composite coating on the surface of the turbine blade is ≥300 μm; Cladding efficiency ≥0.6m 2 / h; hardness is 800~1100HV; corrosion potential is -0.55~-0.42V; The relative erosion wear resistance is 10~25.

10. Use of the composite coating on the surface of a turbine blade produced by the high-speed laser cladding preparation method of the composite coating on the surface of a turbine blade according to any one of claims 1 to 8 in surface protection of key components of hydropower generation equipment.

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