CeO2 / Ni-based wear-resistant laser cladding material and preparation method thereof

Abstract

The invention discloses a CeO2 / Ni-based wear-resistant laser cladding material and a preparation method thereof, and belongs to the technical field of water turbine blade surface processing. The preparation method of the material specifically comprises the following steps: polishing the metal matrix, then cleaning the metal matrix with absolute ethyl alcohol, and then drying the metal matrix for later use; the Ni45 alloy powder and the nanometer CeO2 are weighed according to the mass ratio of the Ni45 alloy powder to the nanometer CeO2 being 100 g: (0.5-2) g and mechanically mixed, and the CeO2 / Ni-based wear-resistant laser cladding material is obtained; drying the CeO2 / Ni-based wear-resistant laser cladding material for later use; and the dried CeO2 / Ni-based wear-resistant laser cladding material is subjected to laser cladding on the surface of a metal matrix, and after natural cooling, a laser cladding layer is obtained on the surface of the metal matrix. The coating prepared through laser cladding is uniform and compact in macroscopic morphology and forms an excellent metallurgical bonding interface with a matrix, and the bonding strength is remarkably improved. In addition, the hardness of the coating is greatly improved compared with that of a base body, the friction performance is obviously improved, and the coating can be effectively suitable for complex working conditions with high wear resistance requirements.

Description

Technical Field

[0001] The invention relates to a CeO2 / Ni-based wear-resistant laser cladding material and a preparation method thereof, and belongs to the technical field of surface processing of turbine blades. Background Art

[0002] Turbine blades are one of the core components of a turbine. During operation, the blade surface is subject to water erosion, sediment wear, and cavitation, resulting in severe wear on the blade surface, which in turn affects the turbine's operating efficiency and service life. Currently, surface coating technologies such as sandblasting, painting, and electroplating are commonly used to improve the wear resistance and cavitation resistance of turbine blades. However, these traditional methods suffer from poor coating adhesion, insufficient wear resistance, complex processes, and environmental pollution.

[0003] Research on hydropower cavitation-resistant alloy coating materials is currently in-depth. While metal cladding materials, such as tungsten carbide (WC) coatings, offer good wear resistance, they suffer from uneven particle distribution and insufficient bonding strength. Traditional cobalt-based alloy cladding layers, due to their high carbon content, are prone to producing hard and brittle phases, resulting in reduced cavitation resistance. Furthermore, their high price and high coating preparation costs limit their wider application in the hydropower sector. Therefore, developing an economical, efficient, environmentally friendly cladding material with excellent wear resistance and its preparation method is of great significance for extending the service life of turbine blades and improving their operating efficiency. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a method for preparing a CeO2 / Ni-based wear-resistant laser cladding material, which specifically comprises the following steps: (1) Grind the metal substrate (preferably ZGOOCr13Ni4Mo martensitic stainless steel as the metal substrate), then clean it with anhydrous ethanol, and then dry it for later use.

[0005] (2) Ni45 alloy powder and nano-CeO2 are weighed in a ratio of 100 g:(0.5~2) g, and mechanically mixed (preferably by vacuum ball milling) to obtain CeO2 / Ni-based wear-resistant laser cladding material.

[0006] (3) The CeO2 / Ni-based wear-resistant laser cladding material is dried (preferably in a drying oven) and then set aside.

[0007] (4) The dried CeO2 / Ni-based wear-resistant laser cladding material is laser clad on the surface of the metal substrate, and after natural cooling, a laser cladding layer is obtained on the surface of the metal substrate.

[0008] Preferably, in step (1), the oxide film on the surface of the metal substrate is polished with 400-grit sandpaper to eliminate the oxide film and macroscopic surface defects. The metal substrate is then rotated 90° and polished again with 800-grit sandpaper to ensure that the wear marks are in the same direction and Ra ≤ 0.8 μm. At the same time, excessive polishing is avoided to prevent excessive surface reflectivity from damaging the instrument. The metal substrate is then cleaned with anhydrous ethanol to remove stains on the surface.

[0009] Preferably, the mechanical mixing conditions in step (2) are: ball milling for 3 hours or more at a speed of 250r-350r / min under a ball-to-material ratio of 2:1; after mixing, a CeO2 / Ni-based wear-resistant laser cladding material with a particle size of 150-300 mesh is obtained.

[0010] Preferably, the CeO2 / Ni-based wear-resistant laser cladding material obtained in step (2) has a hardness of 45HRC and an average particle size of 83.1µm.

[0011] Preferably, the drying conditions in step (3) are: drying in a drying oven at a temperature of 50-90° C. for 5-12 hours.

[0012] Preferably, the CeO2 / Ni-based wear-resistant laser cladding material dried in step (4) is laser clad by a powder feeder.

[0013] Preferably, in step (4), a TLS-KC4000 fiber laser manufactured by IPG Corporation of the United States is used for laser cladding, and a coaxial powder feeding method is adopted. According to a preset scanning path trajectory, under the protection of an argon atmosphere, the cladding powder is laser clad on the surface of the martensitic stainless steel to obtain a cladding coating with parallel distribution of molten pool lines; the laser power is 850~1050W, the scanning speed of the laser cladding is 0.02~0.03m / s, the spot diameter is ≤1.6mm, the protective gas is a mixed gas of Ar, and the gas flow rate is 15~25L / min.

[0014] Another object of the present invention is to provide a CeO2 / Ni-based wear-resistant laser cladding material, which is mechanically mixed with Ni45 alloy powder and nano-CeO2 according to a certain ratio.

[0015] Preferably, the composition of the CeO2 / Ni-based wear-resistant laser cladding material is 0.4% C element, 3% Si element, 2.8% B element, 12% Cr element, ≤15% Fe element, balance Ni element, and nano-CeO2 (0.5~2)% by mass percentage.

[0016] Mechanism of the present invention: The present invention uses mechanical ball milling to uniformly adhere nano-CeO2 particles to the surface of Ni45 spherical particles. During the cladding process, the Ce element is evenly distributed, providing heterogeneous nucleation sites for grain growth and resulting in grain refinement. Furthermore, rare earth elements not only have a strong adsorption effect on impurities, purifying grain boundaries and reducing defects, but also promote melt pool fluidity and the precipitation of strengthening phases, achieving uniform element distribution while significantly improving material hardness.

[0017] Beneficial effects of the present invention: (1) The CeO2 / Ni-based laser cladding coating prepared by the present invention has a good macroscopic morphology, and there are fewer pores and cracks on the coating surface. According to tests, the coating has a good metallurgical bond with the substrate, and the coating has high hardness and good wear resistance.

[0018] (2) The present invention combines the preparation process of CeO2 / Ni-based laser cladding materials, so that the B element and the Cr element can generate Cr5B3 ceramic phase through in-situ reaction, which is distributed in the cladding layer to achieve the effect of dispersion strengthening.

[0019] (3) The present invention combines the preparation process of CeO2 / Ni-based laser cladding materials to effectively combine trace amounts of C elements with Cr elements to form Cr 23 C6 can reduce structural deformation and stress concentration caused by thermal expansion, and is widely used in the fields of wear resistance and corrosion resistance.

[0020] (4) CeO2 as a rare earth oxide can improve the strength and plasticity of the cladding layer, and at the same time, its wear resistance is also improved.

[0021] (5) The present invention obtains a coating with high hardness, high wear resistance and close bonding with the substrate through laser cladding technology, which plays an important guiding role in the preparation of high-quality coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the metallographic structure of the laser cladding coating in Example 1 of the present invention; Figure 2 This is the metallographic structure of the laser cladding coating of Example 2 of the present invention; Figure 3 This is the metallographic structure of the laser cladding coating of Example 3 of the present invention; Figure 4 This is a SEM image of the junction between the laser cladding coating and the substrate in Example 1 of the present invention; Figure 5 This is an SEM image of the junction between the laser cladding coating and the substrate in Example 2 of the present invention; Figure 6 This is an SEM image of the junction between the laser cladding coating and the substrate in Example 3 of the present invention; Figure 7 Microhardness diagram of the laser cladding coatings of Example 1, Example 2 and Example 3. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0024] The average particle size of the Ni45 alloy powder used in the embodiment of the present invention is 81.3 μm; nano-CeO2 was purchased from Beijing Gaodewei Metal Materials Co., Ltd. with a purity of 99.9% and an average particle size of 40 nm.

[0025] The chemical composition of the ZGOOCr13Ni4Mo martensitic stainless steel metal matrix used in the embodiment of the present invention is shown in Table 1: Table 1 Example 1 A method for preparing a CeO2 / Ni-based wear-resistant laser cladding material specifically comprises the following steps: (1) Use 400-grit sandpaper to polish the oxide film on the surface of the ZGOOCr13Ni4Mo martensitic stainless steel metal substrate (chemical composition is shown in Table 1) to eliminate the oxide film and macroscopic surface defects. Then rotate the metal substrate 90° and polish it with 800-grit sandpaper to make the wear marks consistent in direction and Ra ≤ 0.8 μm. At the same time, avoid excessive polishing to cause excessive surface reflectivity and damage the instrument. Then clean it with anhydrous ethanol to remove the oil stains on the surface of the metal substrate and then dry it for use.

[0026] (2) Ni45 alloy powder and nano-CeO2 were weighed in a mass ratio of 100g:0.5g and mixed by vacuum ball milling at a speed of 250r / min for 3h under the condition of a ball-to-material ratio of 2:1 to obtain CeO2 / Ni-based wear-resistant laser cladding material with an average particle size of 150 mesh; the obtained CeO2 / Ni-based wear-resistant laser cladding material was dried in a drying oven at 50℃ for 12h; the dried CeO2 / Ni-based wear-resistant laser cladding material was passed into a powder feeder, and then laser cladding was performed using a TLS-KC4000 fiber laser manufactured by IPG Company of the United States at a laser power of 850W, a scanning speed of 0.02m / s, a spot diameter of 1.6mm, a protective gas of Ar, and a gas flow rate of 15L / min (laser cladding adopts a coaxial powder feeding method and follows a preset scanning path trajectory). After natural cooling, a laser cladding layer is obtained on the surface of the metal substrate.

[0027] The prepared laser cladding layer on the surface of the metal substrate was processed into a square shape by wire cutting, and the cross section was polished according to the metallographic requirements. Deionized water and hydrochloric acid with a mass percentage concentration of 36.46% were mixed in a volume ratio of 1:1. Copper sulfate was then added to the above solution to make the mass concentration of copper sulfate 10g / 100mL to form a mixed solution. The prepared mixed solution was used for corrosion and then observed with a metallographic microscope and a scanning electron microscope. The metallographic pictures are shown as follows. Figure 1 As shown in the figure, it is easy to see that the coating has no obvious pores and cracks, the structure is dense, and there is no inclusion phenomenon; the scanning electron microscope picture is as follows Figure 4 As shown in the figure, it can be seen that the coating and the substrate are well bonded and metallurgically bonded. The microhardness of the cladding layer was tested using a microhardness tester. The longitudinal points were made from the coating to the bonding area, the heat-affected zone and then to the substrate. The results are shown in the figure. Figure 7 As shown in the figure, the average hardness of the laser cladding coating is calculated to be 598HV, which is 2.07 times that of the metal substrate. This effectively demonstrates that the coating has a high hardness, thereby improving the surface friction performance.

[0028] Example 2 A method for preparing a CeO2 / Ni-based wear-resistant laser cladding material specifically comprises the following steps: (1) Use 400-grit sandpaper to polish the oxide film on the surface of the ZGOOCr13Ni4Mo martensitic stainless steel metal substrate (chemical composition shown in Table 1) to remove the oxide film and macroscopic surface defects. Then rotate the metal substrate 90° and polish it again with 800-grit sandpaper to make the wear marks consistent in direction and Ra ≤ 0.8 μm. At the same time, avoid excessive polishing that will cause excessive surface reflectivity and damage the instrument. Afterwards, clean the metal substrate with anhydrous ethanol to remove oil stains on the surface and then dry it for use.

[0029] (2) Ni45 alloy powder and nano-CeO2 were weighed in a mass ratio of 100g:1g and mixed by vacuum ball milling at a speed of 300r / min for 4h under the condition of a ball-to-material ratio of 2:1 to obtain CeO2 / Ni-based wear-resistant laser cladding material with an average particle size of 230 mesh; the obtained CeO2 / Ni-based wear-resistant laser cladding material was dried in a drying oven at 70℃ for 9h; the dried CeO2 / Ni-based wear-resistant laser cladding material was passed into a powder feeder, and then laser cladding was performed using a TLS-KC4000 fiber laser manufactured by IPG Company of the United States at a laser power of 950W, a scanning speed of 0.025m / s, a spot diameter of 1.6mm, a protective gas of Ar, and a gas flow rate of 20L / min (laser cladding adopts a coaxial powder feeding method according to a preset scanning path trajectory). After natural cooling, a laser cladding layer was obtained on the surface of the metal substrate.

[0030] The prepared laser cladding layer on the surface of the metal substrate was processed into a square shape by wire cutting, and the cross section was polished according to the metallographic requirements. Deionized water and hydrochloric acid with a mass percentage concentration of 36.46% were mixed in a volume ratio of 1:1. Copper sulfate was then added to the above solution to make the mass concentration of copper sulfate 10g / 100mL to form a mixed solution. The prepared mixed solution was used for corrosion and then observed with a metallographic microscope and a scanning electron microscope. The metallographic pictures are shown as follows. Figure 2 As shown in the figure, it is easy to see that the coating has no obvious pores and cracks, the structure is dense, and there is no inclusion phenomenon; the scanning electron microscope picture is as follows Figure 5 As shown in the figure, it can be seen that the coating and the substrate are well bonded and metallurgically bonded. The microhardness of the cladding layer was tested using a microhardness tester. The longitudinal points were made from the coating to the bonding area, the heat-affected zone and then to the substrate. The results are shown in the figure. Figure 7 As shown in FIG. , after calculation, the average hardness of the laser cladding coating is 621 HV, which is 2.15 times that of the metal substrate. The coating prepared in this embodiment has high hardness and good surface friction performance.

[0031] Example 3 A method for preparing a CeO2 / Ni-based wear-resistant laser cladding material specifically comprises the following steps: (1) Use 400-grit sandpaper to polish the oxide film on the surface of the ZGOOCr13Ni4Mo martensitic stainless steel metal substrate (chemical composition shown in Table 1) to remove the oxide film and macroscopic surface defects. Then rotate the metal substrate 90° and polish it again with 800-grit sandpaper to make the wear marks consistent in direction and Ra ≤ 0.8 μm. At the same time, avoid excessive polishing that will cause excessive surface reflectivity and damage the instrument. Afterwards, clean the metal substrate with anhydrous ethanol to remove oil stains on the surface and then dry it for use.

[0032] (2) Ni45 alloy powder and nano-CeO2 were weighed in a mass ratio of 100g:2g and mixed by vacuum ball milling at a speed of 350r / min for 5h under the condition of a ball-to-material ratio of 2:1 to obtain CeO2 / Ni-based wear-resistant laser cladding material with an average particle size of 300 mesh; the obtained CeO2 / Ni-based wear-resistant laser cladding material was dried at 90℃ in a drying oven for 5h; the dried CeO2 / Ni-based wear-resistant laser cladding material was passed into a powder feeder, and then laser cladding was performed using a TLS-KC4000 fiber laser manufactured by IPG Company of the United States at a laser power of 1050W, a scanning speed of 0.03m / s, a spot diameter of 1.6mm, a protective gas of Ar, and a gas flow rate of 25L / min (laser cladding adopts a coaxial powder feeding method and follows a preset scanning path trajectory). After natural cooling, a laser cladding layer is obtained on the surface of the metal substrate.

[0033] The prepared laser cladding layer on the surface of the metal substrate was processed into a square shape by wire cutting, and the cross section was polished according to the metallographic requirements. Deionized water and hydrochloric acid with a mass percentage concentration of 36.46% were mixed in a volume ratio of 1:1. Copper sulfate was then added to the above solution to make the mass concentration of copper sulfate 10g / 100mL to form a mixed solution. The prepared mixed solution was used for corrosion and then observed with a metallographic microscope and a scanning electron microscope. The metallographic pictures are shown as follows. Figure 3 As shown in the figure, it is easy to see that the coating has no obvious pores and cracks, the structure is dense, and there is no inclusion phenomenon; the scanning electron microscope picture is as follows Figure 6 As shown in the figure, it can be seen that the coating and the substrate are well bonded and metallurgically bonded. The microhardness of the cladding layer was tested using a microhardness tester. The longitudinal points were made from the coating to the bonding area, the heat-affected zone and then to the substrate. The results are shown in the figure. Figure 7 As shown in the figure, after calculation, the average hardness of the laser cladding coating is 589HV, which is 1.99 times that of the metal substrate. This effectively demonstrates that the coating has a high hardness, thereby improving the surface friction performance.

[0034] While various embodiments of the present invention have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to existing technologies, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a CeO2 / Ni-based wear-resistant laser cladding material, characterized in that: The specific steps include: (1) Grind the metal substrate, then clean it with anhydrous ethanol, and then dry it for later use; (2) Ni45 alloy powder and nano-CeO2 were weighed in a ratio of 100 g:(0.5-2) g, and mechanically mixed to obtain CeO2 / Ni-based wear-resistant laser cladding material; (3) Drying the CeO2 / Ni-based wear-resistant laser cladding material and setting it aside; (4) The dried CeO2 / Ni-based wear-resistant laser cladding material is laser clad on the surface of the metal substrate, and after natural cooling, a laser cladding layer is obtained on the surface of the metal substrate.

2. The method for preparing the CeO2 / Ni-based wear-resistant laser cladding material according to claim 1, characterized in that: The metal matrix in step (1) is ZGOOCr13Ni4Mo martensitic stainless steel.

3. The method for preparing the CeO2 / Ni-based wear-resistant laser cladding material according to claim 1, characterized in that: In the step (1), the oxide film on the surface of the metal substrate is polished with 400-grit sandpaper to eliminate the oxide film and macroscopic surface defects. The metal substrate is then rotated 90° and polished with 800-grit sandpaper to make the wear marks consistent in direction and Ra ≤ 0.8 μm. The metal substrate is then cleaned with anhydrous ethanol to remove stains on the surface of the metal substrate.

4. The method for preparing the CeO2 / Ni-based wear-resistant laser cladding material according to claim 1, characterized in that: The mechanical mixing conditions in step (2) are as follows: vacuum ball milling is used, and the ball-to-material ratio is 2:1, and the rotation speed is 250r / min to 350r / min, and the ball milling is performed for 3 hours or more; after mixing, a CeO2 / Ni-based wear-resistant laser cladding material with a particle size of 150-300 mesh is obtained.

5. The method for preparing the CeO2 / Ni-based wear-resistant laser cladding material according to claim 1, characterized in that: The drying conditions in step (3) are: drying in a drying oven at a temperature of 50-90° C. for 5-12 hours.

6. The method for preparing the CeO2 / Ni-based wear-resistant laser cladding material according to claim 1, characterized in that: The conditions for laser cladding in step (4) are as follows: laser power is 850~1050W, scanning speed of laser cladding is 0.02~0.03m / s, spot diameter is ≤1.6mm, protective gas during laser cladding is Ar gas, and gas flow rate is 15~25L / min.

7. CeO2 / Ni-based wear-resistant laser cladding material prepared by the method according to any one of claims 1 to 6.

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