Multi-scale ceramic reinforced Ni-based high-entropy alloy coating resistant to water and sand abrasion and cavitation erosion and preparation method of multi-scale ceramic reinforced Ni-based high-entropy alloy coating

Abstract

The invention discloses a multi-scale ceramic reinforced Ni-based high-entropy alloy coating resistant to water and sand abrasion and cavitation erosion and a preparation method of the multi-scale ceramic reinforced Ni-based high-entropy alloy coating. The Ni-based high-entropy alloy coating is prepared from, by mole, 10%-25% of Co, 10%-15% of Cr, 10%-20% of Fe, 3%-5% of Mo, 4%-6% of Ti and 4%-7% of C; according to the preparation method, alloy powder is prepared by adopting a vacuum gas atomization method, and then the coating is prepared by adopting a laser cladding process. According to the invention, the uniformity of the coating is improved, the impact toughness and wear resistance / cavitation erosion resistance requirements are considered, the limitation of'strong-toughness contradiction 'of the traditional high-entropy coating is overcome, and an efficient and reliable surface protection solution is provided for the underwater flow passage component.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy coatings, and in particular relates to a multi-scale ceramic-reinforced Ni-based high-entropy alloy coating resistant to water and sand abrasion and cavitation, and a preparation method thereof. Background Art

[0002] Underwater flow-through components such as turbines, ship propellers, and pumps are constantly exposed to complex conditions of sediment-laden water and cavitation, facing the dual destructive effects of water-sand erosion and cavitation (cavitation). Water-sand erosion primarily involves hard particles (such as quartz sand) carried by high-speed water flow, which micro-cut, impact, and plow the material surface, leading to gradual material loss. Cavitation, on the other hand, is caused by local pressure changes in the fluid, triggering the formation and collapse of cavitation bubbles. The resulting shock waves (pressures exceeding 1 GPa) and microjets (velocities exceeding 100 m / s) repeatedly impact the material surface, causing fatigue spalling and pitting. Research has shown that abrasion and cavitation often act synergistically to accelerate material failure: the surface roughening caused by abrasion exacerbates local turbulence and promotes cavitation formation; the pits formed by cavitation serve as agglomeration areas for abrasive particles, further exacerbating material loss. This type of damage directly leads to geometric deformation of flow-through components, reduced efficiency, and even fracture. According to statistics, 30%-40% of the units in hydropower stations are forced to shorten their maintenance cycles due to abrasion-cavitation problems, and annual maintenance costs increase by 15%-20%.

[0003] Currently, surface coatings are the primary protection technology against abrasion and cavitation erosion. Ceramic coatings (such as Al₂O₃ and WC-Co) offer high hardness (≥1000 HV), but they are brittle, have low interfacial bonding strength, and are prone to spalling under impact loads. Recently developed surface enhancement technologies, including high velocity oxygen fuel (HVOF) spraying and plasma cladding, still suffer from high porosity (HVOF coatings have a porosity >3%) and large heat-affected zones, making them difficult to meet the long-term service requirements of underwater components.

[0004] High-entropy alloys (HEAs) offer new avenues for anti-wear and cavitation coatings due to their multi-principal component synergistic effects and unique phase structure design. For example, FeCoCrNiAl-based HEAs can achieve a hardness of 400-500 HV through solid solution strengthening and nano-precipitation, resulting in cavitation resistance 5-10 times that of conventional stainless steel. However, existing HEA coatings still face two major bottlenecks: First, face-centered cubic (FCC) HEAs, while offering excellent toughness, lack sufficient hardness (e.g., CoCrFeMnNi has a hardness of only ~200 HV), making them incapable of resisting hard particle grinding. Second, body-centered cubic (BCC) HEAs or those containing hard phases (such as carbides), while offering high hardness, suffer from reduced toughness, making them susceptible to crack initiation under cavitation impact. For example, when the proportion of the VC hard phase in FeCrMoVC coatings is too high (>15%), the loss of toughness leads to a 20%-30% increase in the cavitation rate. Therefore, how to achieve a balance between high-entropy matrix toughness, hard phase strengthening and interface bonding through composition design and microstructure control has become the key to breaking through existing technologies. Summary of the Invention

[0005] In response to the above technical problems, the present invention provides a multi-scale ceramic-reinforced Ni-based high-entropy alloy coating resistant to water and sand erosion and cavitation, and a preparation method thereof, which improves the uniformity of the coating, takes into account the requirements of impact toughness and wear resistance / cavitation resistance, overcomes the limitations of the "strength-toughness contradiction" of traditional high-entropy coatings, and provides an efficient and reliable surface protection solution for underwater flow-through components.

[0006] In order to achieve the above-mentioned objectives, the present invention provides a multi-scale ceramic-reinforced Ni-based high-entropy alloy coating resistant to water and sand erosion and cavitation, which is composed of the following components, calculated by molar percentage: Co: 10-25%; Cr: 10-15%; Fe: 10-20%; Mo: 3-5%; Ti: 4-6%; C: 4-7%; and Ni as the balance.

[0007] Preferably, the coating thickness of the Ni-based high entropy alloy coating is 0.5-3 mm.

[0008] The present invention also provides a method for preparing a multi-scale ceramic reinforced Ni-based high entropy alloy coating resistant to water and sand erosion and cavitation, comprising the following steps: (1) Using vacuum gas atomization method to make alloy powder from Ni, Co, Cr, Fe, Mo, Ti, and C single-substance blocks; (2) Drying alloy powder; (3) Clean the substrate and dry it to remove oil stains; (4) The dried alloy powder is placed on the substrate and the coating is prepared by laser cladding.

[0009] Preferably, the vacuum gas atomization method in step (1) is as follows: placing the single mass block in a melting crucible with a heating power of 30-35 km, heating it to 1400-1600 ° C and then keeping it warm for 10-20 minutes; after the insulation is completed, directly pouring it into a transfer bag, entering the atomization chamber through a guide tube, and atomizing it at 4-6 MPa to form an alloy powder.

[0010] Preferably, the particle size of the alloy powder in step (1) is 100-300 mesh.

[0011] Preferably, the drying condition in step (2) is drying at 100-120° C. for 2-4 hours.

[0012] Preferably, the substrate in step (3) is ZG05Cr13Ni5Mo.

[0013] Preferably, the cleaning agent used in step (3) is anhydrous acetone or anhydrous alcohol; and the drying condition is drying at 50-60°C for 2-4 hours.

[0014] Preferably, the thickness of the alloy powder on the substrate in step (4) is 0.5-3 mm.

[0015] Preferably, the process parameters of the laser cladding in step (4) are: spot diameter 4-6 mm, laser power 1.3-4.5 kW, scanning speed 5-20 mm / s, powder feeding rate 15-100 g / min, and overlap rate 40-60%.

[0016] The beneficial effects of the present invention are: 1. A high-entropy system based on Ni-Co-Cr-Fe-Mo forms a stable face-centered cubic (FCC) structure. The Cr and Mo content is carefully controlled to ensure a single FCC phase in the alloy matrix and avoid the formation of brittle Cr-Mo intermetallic compounds. While maintaining a single-phase FCC matrix, the Mo content is maximized, as Mo provides solid solution strengthening and reduces the stacking fault energy. Solid solution strengthening (including alloy powders produced by gas atomization and coatings produced by laser cladding) improves the strength of the FCC matrix, while reducing the stacking fault energy promotes multi-level deformation twinning and FCC-HCP martensitic transformation during deformation, thereby enhancing the alloy's plastic deformation capacity and, in other words, the toughness of the alloy matrix.

[0017] 2. The strength of the single-phase FCC matrix is insufficient to withstand high-content sediment erosion, so Ti and C are introduced. Because C and Ti have the most negative mixing enthalpy of all alloying elements, the added Ti preferentially combines with C to form an in-situ TiC ceramic phase with an FCC structure. A small amount of excess C enters the FCC metal matrix as an interstitial solid solution, simultaneously improving the matrix's strength and toughness.

[0018] 3. The master alloy smelting and rapid solidification process during the gas atomization powder preparation process ensures the uniform precipitation of fine TiC ceramic phases. Compared with the process of ball milling element powders, it has significant advantages in structural uniformity and ceramic phase refinement, thereby reducing the adverse effects of coarse ceramic phases on cavitation performance.

[0019] 4. The present invention prepares composite powder with uniform composition and fine ceramic phase in one step, and a single-layer coating can achieve high strength and high toughness at the same time, meeting the harsh service environment requirements of high sediment erosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scanning electron microscope photograph of the coating structure of the multi-scale ceramic-reinforced Ni-based high-entropy alloy coating prepared in Example 1.

[0021] Figure 2 This is a comparison diagram of the abrasion between the multi-scale ceramic-reinforced Ni-based high-entropy alloy coating and the substrate prepared in Example 2.

[0022] Figure 3 This is a comparison diagram of the abrasion between the multi-scale ceramic-reinforced Ni-based high-entropy alloy coating and the substrate prepared in Example 3. DETAILED DESCRIPTION

[0023] The technical solutions of the present invention are further explained below with reference to the accompanying drawings and specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be determined by the claims. Any modifications or substitutions made to the technical solutions of the present invention by those skilled in the art without creative effort shall fall within the scope of protection of the present invention.

[0024] Example 1 (1) Weigh the following components in molar percentage: Ni: 41%, Co: 10%, Cr: 15%, Fe: 20%, Mo: 4%, Ti: 4%, C: 4%; (2) The various single blocks in step (1) were pulverized by vacuum gas atomization (1500°C, 4.5 MPa), and sieved to a particle size of 100 mesh to obtain alloy powder; (3) Spread the alloy powder in an insulated box with a thickness of 5 mm and dry it at 100 °C for 4 h; (4) Take ZG05Cr13Ni5Mo as the substrate, spray the acetone solution on the surface of the substrate for cleaning, then place it in an insulated box and dry it at 50°C for 2.5 hours to remove the oil stains on the surface; (5) The alloy powder dried in step (3) was placed in an automatic powder feeder, and a multi-scale ceramic reinforced Ni-based high entropy alloy coating was prepared on the substrate obtained in step (4) by a laser cladding process, wherein the process parameters of the laser cladding were: spot diameter of 4 mm, laser power of 3.0 kW, overlap rate of 50%, scanning speed of 10 mm / s, and powder feeding rate of 30 g / min.

[0025] The thickness of the prepared Ni-based high entropy alloy coating is 0.5 mm Example 2 (1) Weigh the following components in molar percentage: Ni: 37%, Co: 25%, Cr: 10%, Fe: 15%, Mo: 3%, Ti: 5%, C: 5%; (2) Powdering the various single-substance blocks in step (1) by vacuum gas atomization (1500°C, 5 MPa), and sieving the particles to a size of 200 mesh to obtain alloy powder; (3) Spread the alloy powder in an insulated box with a thickness of 4 mm and dry it at 110 °C for 3 h; (4) Take ZG05Cr13Ni5Mo as the substrate, spray the surface of the substrate with anhydrous ethanol solution for cleaning, then place it in an insulated box and dry it at 60°C for 3 hours to remove the oil stains on the surface; (5) The alloy powder dried in step (3) is placed in an automatic powder feeder, and a multi-scale ceramic reinforced Ni-based high entropy alloy coating is prepared on the substrate obtained in step (4) by a laser cladding process, wherein the process parameters of the laser cladding are: spot diameter of 5 mm, laser power of 3.5 kW, overlap rate: 50%, scanning speed of 8 mm / s, and powder feeding rate of 40 g / min.

[0026] Example 3 (1) Weigh the following components in molar percentage: Ni: 40%, Co: 20%, Cr: 12%, Fe: 10%, Mo: 5%, Ti: 6%, C: 7%; (2) The various single blocks in step (1) were pulverized by vacuum gas atomization (1500°C, 5.5 MPa), and sieved to a particle size of 300 mesh to obtain alloy powder; (3) Spread the alloy powder in an insulated box with a thickness of 4 mm and dry it at 120 ° C for 2 h; (4) Take ZG05Cr13Ni5Mo as the substrate, spray the surface of the substrate with anhydrous ethanol solution for cleaning, then place it in an insulated box and dry it at 55°C for 4 hours to remove the oil stains on the surface; (5) The alloy powder dried in step (3) was placed in an automatic powder feeder, and a multi-scale ceramic reinforced Ni-based high entropy alloy coating was prepared on the substrate obtained in step (4) by a laser cladding process, wherein the process parameters of the laser cladding were: spot diameter of 6 mm, laser power of 4.0 kW, overlap rate of 50%, scanning speed of 15 mm / s, and powder feeding rate of 60 g / min.

[0027] Example 4 (1) Weigh the following components in molar percentage: Ni: 35%, Co: 18%, Cr: 13%, Fe: 18%, Mo: 5%, Ti: 4%, C: 7%; (2) Powdering the various single blocks in step (1) by vacuum gas atomization (1550°C, 6 MPa), and sieving the particles to a size of 200 mesh to obtain alloy powder; (3) Spread the alloy powder in an insulated box with a thickness of 5 mm and dry it at 110 °C for 3 h; (4) Take ZG05Cr13Ni5Mo as the substrate, spray the surface of the substrate with anhydrous ethanol solution for cleaning, then place it in an insulated box and dry it at 60°C for 3.5 hours to remove the oil stains on the surface; (5) The alloy powder dried in step (3) is placed in an automatic powder feeder, and a multi-scale ceramic reinforced Ni-based high entropy alloy coating is prepared on the substrate obtained in step (4) by a laser cladding process, wherein the process parameters of the laser cladding are: spot diameter of 5 mm, laser power of 3.5 kW, overlap rate: 50%, scanning speed of 8 mm / s, and powder feeding rate of 40 g / min.

[0028] Comparative Example 1 (1) The following groups of elemental powders were weighed in order according to molar percentage: Ni: 22.7%, Co: 22.7%, Cr: 22.7%, Fe: 22.7%, Mo: 2.2%, Ti: 3.5%, and C: 3.5%. The mixed powders were then ball-milled under vacuum conditions at a speed of 30 r / min, a ball-to-powder ratio of 12:1, and a ball-to-powder ratio of 6 h to obtain a mixed powder. (2) Spread the mixed powder in an insulated box with a thickness of 4 mm and dry it at 110 °C for 3 h; (3) Take ZG05Cr13Ni5Mo as the substrate, spray the surface of the substrate with anhydrous ethanol solution for cleaning, then place it in an insulated box and dry it at 60°C for 3 hours to remove oil stains on the surface; (4) The dried mixed powder is placed in an automatic powder feeder, and a Ni-based high entropy alloy coating is prepared on the substrate obtained in step (4) using a laser cladding process ( Figure 1), where the process parameters of laser cladding are: spot diameter of 5 mm, laser power of 3.5 kW, overlap rate: 50%, scanning speed of 8 mm / s, and powder feeding rate of 40 g / min.

[0029] Comparative Example 2 The method and steps are the same as those in Example 2, except that the molar percentage of Mo in step (1) is changed to 6.5%, the molar percentage of Cr is changed to 9%, and the molar percentage of Ni is changed to 34.5%, thereby preparing a Ni-based high-entropy alloy coating.

[0030] Comparative Example 3 The method and steps are the same as those in Example 2, except that the molar percentage of Mo in step (1) is changed to 2%, the molar percentage of Cr is changed to 16%, and the molar percentage of Ni is changed to 32%, thereby preparing a Ni-based high-entropy alloy coating.

[0031] Comparative Example 4 The method and steps are the same as those in Example 2, except that the molar percentage of Ti in step (1) is changed to 3%, the molar percentage of C is changed to 3%, and the molar percentage of Ni is changed to 41%, to prepare a Ni-based high-entropy alloy coating.

[0032] Comparative Example 5 The method and steps are the same as those in Example 2, except that the molar percentage of Ti in step (1) is changed to 7%, the molar percentage of C is changed to 7%, and the molar percentage of Ni is changed to 33%, thereby preparing a Ni-based high-entropy alloy coating.

[0033] Comparative Example 6 The method and steps are the same as those in Example 2, except that the single substance block in step (1) is replaced with a single substance powder, which is then ball-milled to obtain a mixed powder, which is then dried to prepare a Ni-based high-entropy alloy coating; wherein the ball milling speed is 30 r / min, the ball-to-material ratio is 12:1, and the ball milling time is 6 h.

[0034] Results: The Ni-based high entropy alloy coatings prepared in the above examples and comparative examples were tested for microhardness using a microhardness tester. The results are shown in Table 1. Abrasion performance test: The test was conducted in the SQC-200 three-phase flow abrasion test system. The alloy sample, which had been mechanically polished to 2000 grit sandpaper, was placed on the sample table. 13 kg of quartz sand with a diameter of 1-2 mm and 20 kg of deionized water were added to the test machine. During the test, the stirring blade was stirred at a speed of 1200 r / min to ensure that the sand and gravel were evenly distributed and would not sink to the bottom. The results are shown in Table 1. Figure 2-3 ; Cavitation performance test: The test was conducted using an ultrasonic cavitation tester (Nanjing Xianou XOQS-1200) at 25 ± 2°C. The sample size was Φ22 mm and was fixed under the ultrasound with a spacing of 6 mm. The ultrasonic power was 20 kHz, the wavelength was 50 μm, and the medium was deionized water. The results are shown in Table 1.

[0035] Table 1 Performance parameters of Ni-based high entropy alloy coating

[0036] Note: The anti-abrasion performance and anti-cavitation performance are based on the performance of the substrate being 1 times, and are expressed as multiples.

[0037] From Table 1 and Figure 1-3 It can be seen that the Ni-based high entropy alloy coatings prepared in Examples 1-4 significantly improved the microhardness, abrasion resistance and cavitation resistance of the substrate surface.

Claims

1. A multi-scale ceramic-reinforced Ni-based high-entropy alloy coating resistant to water and sand erosion and cavitation, characterized by: In terms of molar percentage, it is composed of the following components: Co: 10-25%; Cr: 10-15%; Fe: 10-20%; Mo: 3-5%; Ti: 4-6%; C: 4-7%; and Ni as the balance.

2. The multi-scale ceramic-reinforced Ni-based high-entropy alloy coating resistant to water and sand abrasion and cavitation according to claim 1, characterized in that: The coating thickness of the Ni-based high entropy alloy coating is 0.5-3 mm.

3. A method for preparing a multi-scale ceramic-reinforced Ni-based high-entropy alloy coating resistant to water and sand erosion and cavitation, characterized by: The steps include: (1) Using vacuum gas atomization method to make alloy powder from Ni, Co, Cr, Fe, Mo, Ti, and C single blocks; (2) Drying alloy powder; (3) Clean the substrate and dry it to remove oil stains; (4) The dried alloy powder is automatically fed and the coating is prepared by laser cladding.

4. The preparation method according to claim 3, wherein: The vacuum air atomization method in step (1) is to heat the mixture to 1400-1600° C. at a heating power of 30-35 kW and keep the temperature for 10-20 minutes, and then atomize the mixture at a pressure of 4-6 MPa.

5. The preparation method according to claim 3, wherein: The particle size of the alloy powder in step (1) is 100-300 mesh.

6. The preparation method according to claim 3, wherein: The drying condition in step (2) is drying at 100-120°C for 2-4 hours.

7. The preparation method according to claim 3, wherein: The substrate described in step (3) is ZG05Cr13Ni5Mo.

8. The preparation method according to claim 3, wherein: The cleaning agent used in step (3) is anhydrous acetone or anhydrous alcohol; the drying condition is 50-60°C for 2-4 hours.

9. The preparation method according to claim 3, wherein: The thickness of the alloy powder on the substrate in step (4) is 0.5-3 mm.

10. The preparation method according to claim 3, characterized in that: The process parameters of the laser cladding in step (4) are: spot diameter 4-6 mm, laser power 1.3-4.5 kW, scanning speed 5-20 mm / s, powder feeding rate 15-100 g / min, and overlap rate 40-60%.

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