Abrasion and cavitation resistant laser cladding multi-scale heterogeneous carbide reinforced composite coating and preparation method thereof

Abstract

The invention discloses an abrasion and cavitation resistant laser cladding multi-scale heterogeneous carbide reinforced composite coating and a preparation method thereof, and the composite coating comprises the following components in percentage by mass: the balance of WC powder, 20.9%-26.9% of Ni, 18.00%-23.1% of Co, 10.6%-13.6% of Cr, 7.1%-9.1% of Fe, 7.3%-9.4% of Mo, 4.9%-6.3% of Ti and 1.2%-1.6% of C. The invention further discloses a preparation method of the abrasion and cavitation resistant laser cladding multi-scale heterogeneous carbide reinforced composite coating. The preparation method comprises the steps that high-entropy alloy powder is prepared through a vacuum gas atomization method, the high-entropy alloy powder and WC powder are mixed through a planetary ball mill, and then the composite coating is prepared through a coaxial powder feeding laser cladding process. According to the method, the uniformity of the coating is improved, the strength-toughness synergistic characteristic and optimized laser cladding process parameter matching are considered, high-density uniform arrangement of different carbide reinforcement phases in multiple scales is achieved, and high hardness and crack propagation resistance are synchronously achieved in the coating. The composite coating has excellent cavitation and abrasion resistance, and an efficient and reliable surface protection solution is provided for underwater flow passage components.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material coatings, and in particular relates to a laser cladding multi-scale heterogeneous carbide reinforced composite coating that is resistant to abrasion and cavitation and a preparation method thereof. Background Art

[0002] Anti-abrasion and cavitation materials have key applications in the industrial sector. In numerous industries, such as water conservancy, energy, and the chemical industry, underwater flow-through components of equipment such as turbines, ship propellers, and water pumps are exposed to complex conditions of silty water and cavitation for long periods of time. These components are damaged by mechanical erosion and chemical corrosion caused by the impact of solid particles or the collapse of bubbles in the fluid, resulting in reduced equipment efficiency and shortened lifespan. Studies have shown that abrasion and cavitation often work synergistically to accelerate material failure: surface roughening caused by abrasion exacerbates local turbulence and promotes cavitation formation; pits formed by cavitation become aggregation 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 accidents. Traditional materials often suffer from insufficient hardness and abrasion resistance, or insufficient bonding strength with the substrate under extreme working conditions, making it difficult to meet the high corrosion and wear resistance requirements of modern industry, and a breakthrough is urgently needed.

[0003] Currently, functional surface coating technology is the main protection strategy to deal with abrasion-cavitation coupling damage. Traditional ceramic-based coatings, such as 、 While high-entropy systems possess high hardness and excellent wear resistance, their intrinsic brittleness and insufficient coating-substrate interface bonding strength can easily lead to interfacial debonding failure under cyclic impact loading. Metal alloy coatings can alleviate stress concentration through plastic deformation, but their wear resistance is significantly limited by their microhardness and wear resistance thresholds. High-entropy alloy coatings, thanks to their unique high-entropy effect, exhibit excellent high-temperature strength, corrosion resistance, and oxidation resistance. This is due to the complex and stable interactions between atoms in their multicomponent alloy system. However, they also have inherent drawbacks: First, face-centered cubic (FCC) high-entropy alloys exhibit excellent toughness but insufficient hardness. For example, CoCrFeMnNi has a hardness of less than 200 HV, making it less resistant to wear in high-stress abrasive environments. Second, body-centered cubic (BCC) high-entropy systems or those containing hard phases (such as carbides) exhibit high hardness but reduced toughness, making them susceptible to crack initiation under cavitation impact. The metal-ceramic composite coating system developed in recent years has achieved a balanced optimization of hardness and toughness through multi-phase synergy, but its engineering application is limited by the adaptability of the binding phase selection and the control of the laser cladding process, which has become the core research direction for improving protective effectiveness. Summary of the Invention

[0004] To address these technical challenges, the present invention provides a laser-clad, multi-scale, heterogeneous carbide-reinforced composite coating that is resistant to abrasion and cavitation, and a method for its preparation. This coating improves coating uniformity, balances strength-toughness synergy with optimized laser cladding process parameters, and achieves a high-density, uniform arrangement of multi-scale heterogeneous carbide reinforcements, simultaneously achieving high hardness and crack growth resistance within the coating. This composite coating exhibits excellent resistance to cavitation and abrasion, providing a highly efficient and reliable surface protection solution for underwater flow-through components.

[0005] In order to achieve the above objectives, the present invention provides a laser cladding multi-scale heterogeneous carbide reinforced composite coating resistant to abrasion and cavitation and a preparation method thereof, which is composed of the following components, calculated by mass percentage: WC powder balance, 20.9-26.9% Ni, 18.00-23.1% Co, 10.6-13.6% Cr, 7.1-9.1% Fe, 7.3-9.4% Mo, 4.9-6.3% Ti, and 1.2-1.6% C.

[0006] Preferably, the thickness of the composite coating is 0.5-3 mm.

[0007] The present invention also provides a method for preparing a laser cladding multi-scale heterogeneous carbide reinforced composite coating that is resistant to abrasion and cavitation, comprising the following steps: (1) High entropy alloy powder was prepared by vacuum gas atomization method, and the weight percentage was as follows: 29.86% Ni, 25.70% Co, 15.12% Cr, 10.15% Fe, 10.46% Mo, 6.96% Ti, and 1.75% C; (2) Using a planetary ball mill, the prepared high entropy alloy powder is mixed with WC powder. The mixing ratio is expressed in mass percentage as follows: balance of high entropy alloy powder + 10%-30% WC powder. (3) Drying alloy powder; (4) Clean the substrate and dry it to remove oil stains; (5) The dried alloy powder is placed on the substrate and the coating is prepared by laser cladding.

[0008] Preferably, the heating power of the melting crucible in the vacuum gas atomization method in step (1) is 30-35 kW, and the temperature is maintained at about 1500°C for 10-20 minutes. After the temperature is maintained, the crucible is directly poured into the transfer ladle and atomized in the atomization chamber through the guide tube. The atomization pressure is 4-6 MPa.

[0009] Preferably, the particle size of the alloy powder in step (1) is 100-300 mesh.

[0010] Preferably, the drying condition in step (2) is drying at 100-120° C. for 2-4 hours.

[0011] Preferably, the substrate in step (3) is ZG05Cr13Ni5Mo.

[0012] Preferably, the cleaning agent used in step (3) is acetone or anhydrous alcohol; and the drying condition is 50-60° C. for 2-4 hours.

[0013] Preferably, the thickness of the alloy powder on the substrate in step (4) is 0.5-3 mm.

[0014] 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%.

[0015] The beneficial effects of the present invention are: 1. The strength of a single-phase FCC alloy matrix is insufficient to resist high-content sediment erosion and abrasion. By introducing Ti and C elements with large negative mixing enthalpy, micron and submicron-sized TiC precipitation phases are generated in situ in the FCC alloy matrix. A small amount of excess C element enters the FCC metal matrix in the form of interstitial solid solution, while improving the strength and toughness of the matrix. The precipitation of small-sized strengthening phases maintains the excellent toughness and plasticity of the FCC alloy matrix while significantly improving the strength, thereby simultaneously improving the cavitation and abrasion resistance of the composite coating.

[0016] 2. Coarse WC powder particles are crucial to improving the wear resistance and impact resistance of the coating. The present invention optimizes the WC strengthening phase content by targeting the dual-scale TiC reinforced alloy matrix, thereby significantly improving the abrasion resistance of the composite coating in a high sediment content water flow impact environment.

[0017] 3. By optimizing the laser energy density and the thermodynamic response characteristics of the molten pool, the generation of defects such as pores and unfused metals during the cladding process is effectively suppressed. At the same time, the WC ceramic phase and the in-situ generated TiC ceramic phase are uniformly dispersed in the matrix, and high interface bonding strength and crack propagation resistance are simultaneously achieved in the coating. It can withstand the continuous impact of high-velocity sand-laden water flow and the harsh service environment requirements of cavitation collapse. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a scanning electron microscope photograph of the coating structure of the composite coating prepared in Example 1.

[0019] Figure 2 The following are scanning electron microscope photos of the coating structure and element distribution diagram of the composite coating prepared in Example 2.

[0020] Figure 3 This is a comparison diagram of the abrasion between the composite coating prepared in Example 3 and the substrate. DETAILED DESCRIPTION

[0021] 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.

[0022] Example 1 (1) High entropy alloy powder was prepared by vacuum gas atomization method, and the weight percentage was as follows: 29.86% Ni, 25.70% Co, 15.12% Cr, 10.15% Fe, 10.46% Mo, 6.96% Ti, and 1.75% C; (2) The prepared high entropy alloy powder and WC powder were mixed using a planetary ball mill. The mixture consisted of the remainder of high entropy alloy powder and 30%-WC powder in terms of mass percentage. The ball milling speed was 30 r / min, the ball-to-material ratio was 12:1, and the ball milling time was 6 h. (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 used to prepare a high entropy composite coating on the substrate obtained in step (4) by laser cladding. The laser cladding process parameters were: spot diameter of 4 mm, laser power of 2.3 kW, overlap rate of 50%, scanning speed of 5 mm / s, and powder feeding rate of 50 g / min. The thickness of the prepared composite coating was 0.5 mm.

[0023] Example 2 (1) Preparation of high entropy alloy powder was the same as in Example 1; (2) Using a planetary ball mill, eutectic high entropy alloy powder and WC powder were mixed to form a mixture consisting of high entropy alloy powder balance and 20%-WC powder, according to mass percentage, wherein the ball milling speed was 30 r / min, the ball-to-material ratio was 12:1, and the ball milling time was 6 h; (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) was used to prepare a Ni-based high-entropy alloy coating on the substrate obtained in step (4) by laser cladding. The laser cladding process parameters were: spot diameter of 5 mm, laser power of 2.3 kW, overlap rate of 50%, scanning speed of 5 mm / s, and powder feeding rate of 50 g / min. The thickness of the prepared composite coating was 0.8 mm.

[0024] Example 3 (1) The steps for preparing high entropy alloy powder are the same as those in Example 1; (2) mixing high entropy alloy powder and WC powder using a planetary ball mill to form a mixture consisting of eutectic high entropy alloy powder balance and 10%-WC powder in terms of mass percentage; (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 used to prepare a Ni-based high-entropy alloy coating on the substrate obtained in step (4) by laser cladding. The laser cladding process parameters were: spot diameter 6 mm, laser power 2.0 kW, overlap rate 50%, scanning speed 5 mm / s, and powder feeding rate 50 g / min. The prepared composite coating had a thickness of 0.8 mm.

[0025] Comparative Example 1 (1) Preparation of high entropy alloy powder is the same as in Example 1; (2) Spread the alloy 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 used to prepare a eutectic high entropy alloy coating on the substrate obtained in step (4) by laser cladding process ( Figure 1 The laser cladding process parameters were: 5 mm spot diameter, 2.5 kW laser power, 50% overlap, 5 mm / s scanning speed, and 50 g / min powder feed rate. The resulting eutectic high-entropy alloy coating was 1.1 mm thick.

[0026] Results: The coating samples prepared in the above examples and comparative examples were taken and their microhardness was tested 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.

[0027] Table 1 Performance parameters of high entropy alloy-tungsten carbide composite coating

[0028] 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.

[0029] From Table 1 and Figure 1-3 It can be seen that the high entropy composite coatings prepared in Examples 1-3 significantly improve the microhardness, abrasion resistance and cavitation resistance of the substrate surface.

Claims

1. A laser-clad multi-scale heterogeneous carbide-reinforced composite coating resistant to abrasion and cavitation, characterized by: In terms of mass percentage, it is composed of the following components: WC powder balance, 20.9~26.9% Ni, 18.00~23.1% Co, 10.6~13.6% Cr, 7.1~9.1% Fe, 7.3~9.4% Mo, 4.9~6.3% Ti, and 1.2~1.6% C.

2. The laser cladding multi-scale heterogeneous carbide reinforced composite coating resistant to abrasion and cavitation according to claim 1, characterized in that: The thickness of the laser cladding high entropy composite coating is 0.5-3 mm.

3. A method for preparing a laser cladding multi-scale heterogeneous carbide reinforced composite coating that is resistant to abrasion and cavitation, characterized by: The steps include: (1) High entropy alloy powders were prepared from Ni, Co, Cr, Fe, Mo, Ti, and C single-element blocks using vacuum gas atomization. (2) Using a planetary ball mill, the prepared high entropy alloy powder is mixed with WC powder. The mixing ratio is expressed in mass percentage as follows: balance of high entropy alloy powder + 10%-30% WC powder. (3) Drying the mixed alloy powder; (4) Clean the substrate and dry it to remove oil stains; (5) The dried alloy powder is placed in an automatic powder feeder and the coating is prepared using laser cladding equipment.

4. The preparation method according to claim 3, wherein: The heating power of the melting crucible of the vacuum gas atomization method in step (1) is 30-35KW, and the temperature is kept at about 1500°C for 10-20 minutes. After the temperature is kept, the crucible is directly poured into the transfer bag and enters the atomization chamber through the guide pipe for atomization. The atomization pressure is 4-6MPa.

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 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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