Laser cladding method for preparing corrosion-resistant and wear-resistant coatings for piston rods and cylinders

Abstract

This invention belongs to the field of composite coating preparation technology, specifically relating to a laser cladding method for preparing corrosion-resistant and wear-resistant coatings for piston rods and cylinders. 75%–95% nickel-based powder and 5%–25% ceramic powder are mixed to form spherical powder with a particle size ranging from 45 to 105 μm. The spherical powder is dried to obtain cladding powder. The cladding powder is then laser-clad onto a substrate to prepare a coating under ultrasonic vibration assistance. Ultrasonic vibration refers to transmitting ultrasound to a worktable supporting the substrate via an ultrasonic vibration device, which in turn transmits the ultrasound waves to the molten pool, ensuring continuous action of the ultrasound waves on the molten pool. Compared with existing technologies, the beneficial effects of this invention are: the wear-resistant and corrosion-resistant composite coating prepared using ultrasonic vibration-assisted laser cladding technology exhibits high hardness, good wear resistance, and excellent corrosion resistance, making it suitable for high-wear and highly corrosive environments, such as marine equipment.

Description

Technical Field

[0001] This invention belongs to the field of composite coating preparation technology, specifically relating to a laser cladding method for preparing corrosion-resistant and wear-resistant coatings for piston rods and cylinders. Background Technology

[0002] Currently, coatings prepared using traditional techniques exhibit weak adhesion to the substrate, making them prone to detachment under friction and wear. However, laser cladding technology produces coatings that are non-porous, have low dilution rates, and demonstrate excellent metallurgical bonding. Hastelloy C-276, as a nickel-based alloy, exhibits excellent hardness, wear resistance, and corrosion resistance. However, the current hardness, wear resistance, and corrosion resistance of Hastelloy C-276 coatings still do not meet the requirements for marine and aerospace applications. Therefore, a method is needed to improve the performance of Hastelloy C-276 coatings. Summary of the Invention

[0003] This invention provides a laser cladding method for preparing corrosion-resistant and wear-resistant coatings for piston rods and cylinders, aiming to solve the problem that existing coatings cannot simultaneously possess high hardness, good wear resistance, and excellent corrosion resistance.

[0004] The specific technical solution is as follows: A laser cladding method for preparing corrosion-resistant and wear-resistant coatings on piston rods and cylinders includes the following steps: S1. Material preparation: 75%~95% nickel-based powder, 5%~25% ceramic powder, by mass percentage; S2. Powder mixing: Nickel-based powder and ceramic powder are mixed to form spherical powder with a particle size in the range of 45~105μm; S3. Drying: Dry the spherical powder at 100-120℃ for 4-6 hours to obtain the cladding powder; S4. The cladding powder is laser-clad onto the substrate to prepare a coating under the assistance of ultrasonic vibration. The ultrasonic vibration refers to the transmission of ultrasound to the worktable supporting the substrate through an ultrasonic vibration device. The worktable transmits the ultrasonic waves to the molten pool, so that the ultrasonic waves act on the molten pool continuously.

[0005] Preferably, the ultrasonic vibration is set to a frequency range of 30-50Hz and an ultrasonic amplitude range of 35-50μm.

[0006] Preferably, the laser cladding refers to a laser power of 800-1100W, a scanning speed of 16-20mm / s, and a powder feeding rate of 0.5-0.9r / s.

[0007] Preferably, the powder mixing is performed using an omnidirectional planetary ball mill, with the ball mill rotating at 190-210 r / min and revolving at 3-7 r / min, and stirring for 7-9 hours.

[0008] Preferably, in step S2, the spherical powder is a near-spherical powder with a surface roughness of less than 0.5 μm in more than 75% of the single particle surface area, and its sphericity is ≥0.9.

[0009] Preferably, both the nickel-based powder and the ceramic powder are gas-atomized powders, with a purity of 99.9% and a particle size of 45μm to 105μm.

[0010] Preferably, in step S1, the ceramic powder accounts for 5% to 15% of the total mass.

[0011] Preferably, the nickel-based powder is gas-atomized spherical Hastelloy C-276 powder, and the ceramic powder is TiC powder.

[0012] Preferably, in step S1, the mass ratio of nickel-based powder to ceramic powder is 0.95:0.05 or 0.85:0.15.

[0013] The laser cladding method for preparing the corrosion-resistant and wear-resistant coatings for piston rods and cylinders described above is applicable to applications involving severe wear and / or corrosion.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The coating prepared by this invention exhibits high hardness, good wear resistance and excellent corrosion resistance, and different performance requirements can be met by changing the powder ratio.

[0015] 2. The coating prepared by the laser cladding technology of this invention has a good bond with the substrate, high bonding strength, and is not easy to peel off in the environment of friction and wear.

[0016] 3. By introducing ultrasonic vibration technology to assist laser cladding, this invention can refine the microstructure of the coating, thereby strengthening the grains and improving the performance of the composite coating. Furthermore, under the continuous action of ultrasonic vibration, the phenomenon of powder agglomeration can be reduced, resulting in a more uniform powder distribution.

[0017] 4. In laser cladding processes, the present invention addresses the precipitation of TiC. Solid solution strengthening is achieved through the finely dispersed carbides; the introduction of TiC to bear part of the contact stress and the resulting fine grain strengthening improve the hardness and wear resistance of the coating.

[0018] 5. The fine-grain strengthening effect produced by the addition of TiC in this invention reduces the porosity and cracks of the coating, makes the coating structure more compact, makes it less susceptible to the penetration of corrosive media, and improves the corrosion resistance of the coating.

[0019] In summary, the high-hardness, wear-resistant, and corrosion-resistant composite coating prepared by the ultrasonic vibration-assisted laser cladding process of this invention has the characteristics of high hardness, good wear resistance, and excellent corrosion resistance, and is suitable for high-wear and highly corrosive environments, such as marine equipment. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the preparation and testing process of the high-hardness, wear-resistant, and corrosion-resistant composite coating in this invention. Detailed Implementation

[0021] To facilitate understanding of the present invention, it will be described in more detail below with reference to the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0022] The high-hardness, wear-resistant, and corrosion-resistant composite coating is made of 75%~95% nickel-based powder and 5%~25% ceramic powder, by weight percentage.

[0023] The nickel-based powder may be Hastelloy C-276 powder, which is an atomized spherical nickel-based powder with a purity of 99.9% and a particle size of 45μm~105μm.

[0024] The ceramic powder may be TiC powder, which is gas-atomized ceramic powder with a purity of 99.9% and a particle size of 45μm~105μm.

[0025] A laser cladding method for preparing corrosion-resistant and wear-resistant coatings for piston rods and cylinders was employed. Powders were weighed according to a specified ratio, and Hastelloy C-276 powder was mixed with 5%–25% TiC powder. After drying, the mixture was laser-clad onto substrates such as 42CrMo under ultrasonic vibration assistance to prepare a high-hardness, wear-resistant, and corrosion-resistant composite coating. After cutting, grinding, and cleaning, hardness, wear resistance, and corrosion resistance tests were performed to analyze the performance of the composite coating. Figure 1 Understanding. Among them: 1. Preparation method The powder mixing process employs an omnidirectional planetary ball mill, with a rotation speed of 190-210 r / min and a revolution speed of 3-7 r / min, and stirring for 7-9 hours. The resulting powder consists of near-spherical particles with a surface roughness of less than 0.5 μm over 75% of their surface area, and sphericity ≥ 0.9. The particle size of the mixed powder ranges from 45 μm to 105 μm, measured using ImageJ software. When the powder particle size is too fine, the specific surface area increases, making it more susceptible to oxidation; when the particle size is too coarse, it is difficult to completely melt during laser cladding.

[0026] The drying process refers to placing the mixed powder into a drying oven and drying it at 100-120℃ for 4-6 hours. When the temperature is below 100℃, the moisture is not completely removed, which makes the resulting coating prone to defects such as pores, affecting the coating's density, hardness, wear resistance, and corrosion resistance. When the temperature is above 120℃, it will cause the Hastelloy C-276 powder to oxidize, reducing the fluidity of the molten pool and decreasing the adhesion between the coating and the substrate.

[0027] The ultrasonic vibration refers to the transmission of ultrasound waves to a worktable supporting the substrate via an ultrasonic vibration device. The worktable then transmits the ultrasound waves into the molten pool, ensuring that the ultrasound waves continuously act on the molten pool. The frequency range of the ultrasonic vibration is set to 30-50Hz, and the amplitude range is 35-50μm.

[0028] The laser cladding refers to a laser power of 800-1100W, a scanning speed of 16-20mm / s, and a powder feeding rate of 0.5-0.9r / s, with a cladding rate of 50%, a spot diameter of 2.2mm, and argon as the protective gas.

[0029] The substrate refers to a substrate with dimensions of 100mm×100mm×10mm. The surface of the substrate is wiped with anhydrous ethanol to remove the oxide film and grease, and then dried with a paper towel.

[0030] The thickness of the composite coating prepared on the substrate ranges from 0.5 to 2.0 mm.

[0031] Test section The coating was prepared into samples of different sizes by wire cutting for testing of hardness, wear resistance and corrosion resistance.

[0032] Sample Preparation: The wire cutting refers to cutting the coating into samples of 5mm×5mm×10mm, 10mm×10mm×2.5mm, and 10mm×15mm×8mm using a DK77 CNC wire EDM machine. The 5mm×5mm×10mm samples were polished with 400, 800, 1200, 2000, and 3000 grit sandpaper, etched with aqua regia (concentrated nitric acid: concentrated hydrochloric acid = 3:1), rinsed with anhydrous ethanol, and dried with a hairdryer. The 10mm×10mm×2.5mm and 10mm×15mm×8mm samples were polished with 400 and 800 grit sandpaper, rinsed with anhydrous ethanol, and dried with a hairdryer. The 5mm×5mm×10mm samples underwent hardness testing, the 10mm×10mm×2.5mm samples underwent corrosion resistance testing, and the 10mm×15mm×8mm samples underwent abrasion resistance testing.

[0033] Hardness: Tested using an HV-1000 hardness tester. Test conditions: indentation spacing of 0.1 mm, load set to 200 g, and loading time set to 10-12 s.

[0034] Wear resistance: Tested using an M-2000 wear testing machine. Test conditions: GCr15 as the wear material, standard heat treatment, machine speed 190-210 r / min, test time 25-35 min, pressure load 190-210 N.

[0035] Corrosion resistance: Tested using a CHI760E electrochemical workstation. Test conditions: Tested in 3.5wt% NaCl solution. The coated sample was used as the working electrode, AgCl as the reference electrode, and platinum wire as the auxiliary electrode. The frequency range was [missing information]. The scanning range is open circuit voltage -0.5V to open circuit voltage +0.5V, and the scanning speed is 0.01V / s.

[0036] 3. Preparation of different types of high-hardness, wear-resistant, and corrosion-resistant composite coatings Example 1: Using 42CrMo as the matrix, the surface was wiped with anhydrous ethanol and dried with a paper towel. Hastelloy C-276 powder with a particle size of 45μm~105μm was mixed with TiC powder with a particle size of 45μm~105μm at a mass ratio of 0.95:0.05. The mixture was stirred for 7-9 hours using an omnidirectional planetary ball mill at a rotation speed of 190-210 r / min and a revolution speed of 3-7 r / min. The mixed powder was then placed in a drying oven at 100-120℃. The material is dried for 4-6 hours to obtain cladding powder. The cladding powder is then loaded into a powder feeding device and laser cladding is performed under the assistance of ultrasonic vibration. The ultrasonic vibration frequency range is 30-50Hz, and the ultrasonic amplitude range is 35-50μm. The laser cladding refers to a laser power of 800-1100W, a scanning speed of 16-20mm / s, and a powder feeding rate of 0.5-0.9r / s, with a build-up rate of 50%, a spot diameter of 2.2mm, and argon as the protective gas, to obtain a high-hardness, wear-resistant, and corrosion-resistant composite coating.

[0037] Example 2: Unlike Example 1, Hastelloy C-276 powder with a particle size of 45μm to 105μm was mixed with TiC powder with a particle size of 45μm to 105μm at a mass ratio of 0.90:0.10 to obtain cladding powder.

[0038] Example 3: Unlike Example 1, Hastelloy C-276 powder with a particle size of 45μm to 105μm was mixed with TiC powder with a particle size of 45μm to 105μm at a mass ratio of 0.85:0.15 to obtain cladding powder.

[0039] Example 4: Unlike Example 1, Hastelloy C-276 powder with a particle size of 45μm to 105μm was mixed with TiC powder with a particle size of 45μm to 105μm at a mass ratio of 0.80:0.20 to obtain cladding powder.

[0040] Example 5: Unlike Example 1, Hastelloy C-276 powder with a particle size of 45μm to 105μm was mixed with TiC powder with a particle size of 45μm to 105μm at a mass ratio of 0.75:0.25 to obtain cladding powder.

[0041] Comparative Example 1: Referring to Example 1, the difference is that TiC powder was not added, resulting in a Hastelloy C-276 coating.

[0042] 4. Coating performance analysis (1) Hardness: The micro Vickers hardness of the sample coating was measured at 7 points along a cross-section of 5mm×5mm×10mm using a micro Vickers hardness tester, with each point spaced 0.2mm apart. The maximum and minimum micro Vickers hardness values ​​were removed, and the average of the remaining 5 points was calculated to obtain the average micro Vickers hardness value of the sample. The hardness of the sample was determined by analyzing the average micro Vickers hardness value.

[0043] Analysis results: Compared to the single-component Hastelloy C-276 coating, the Hastelloy C-276 / TiC composite coating has higher hardness. Explanation: TiC precipitation... The carbides exert solid solution strengthening effects, improving the yield strength of the composite coating. Simultaneously, the addition of TiC inhibits grain growth, resulting in grain refinement. The synergistic effect of these two factors improves the hardness of the composite coating.

[0044] (2) Wear resistance: Generally speaking, the smaller the coefficient of friction, the less wear, which indicates better wear resistance. A 10mm×15mm×8mm sample was placed in an ultrasonic cleaning device, cleaned for 1 minute, then removed, rinsed with anhydrous ethanol, and dried with a hair dryer. The weight was measured using a balance, and then placed in a wear testing machine. After a 30-minute test, the friction coefficient data was exported from the computer software. Friction and wear are unstable before 1000s; only the stable stage after 1000s is considered. The average friction coefficient after 1000s was obtained. The tested sample was placed back into the ultrasonic cleaning device for 1 minute, removed, and weighed using a balance. The difference between the two weights was the wear amount. A comprehensive analysis of the average friction coefficient and wear amount was performed to determine the wear resistance of the sample.

[0045] Analysis Results: Compared to the single-component Hastelloy C-276 coating, the Hastelloy C-276 / TiC composite coating exhibits better wear resistance, indicating that the introduction of TiC enhances the coating's wear resistance. Explanation: The addition of TiC can absorb some contact stress, reducing the frequency of direct wear on the substrate. Simultaneously, the fine-grained strengthening effect of TiC contributes to a more uniform microstructure. The synergistic effect of these two factors improves the wear resistance of the composite coating.

[0046] (3) Corrosion resistance: Electrochemical tests were conducted on 10mm×10mm×2.5mm samples to obtain corrosion potential, corrosion current density, and polarization resistance. The corrosion resistance of the samples was evaluated by comprehensive analysis of the three parameters.

[0047] Analysis results: Compared with the single-component Hastelloy C-276 coating, the Hastelloy C-276 / TiC composite coating exhibits better corrosion resistance, meaning the introduction of TiC improves the coating's corrosion resistance. This is due to the fine-grain strengthening effect of TiC, which reduces the coating's porosity, decreases the number of cracks, and creates a denser microstructure, making it harder for corrosive media to penetrate and reducing the probability of corrosion.

[0048] The high-hardness, wear-resistant and corrosion-resistant composite coating (Hastelloy C-276 and TiC composite coating) prepared by the present invention through ultrasonic vibration-assisted laser cladding technology has a uniform, dense and seamless surface, and features high hardness, good wear resistance and excellent corrosion resistance. It is suitable for high-wear and highly corrosive environments, such as marine equipment.

[0049] Mechanism explanation: (1) Ball milling and mixing of Hastelloy C-276 powder and TiC powder can effectively reduce powder agglomeration. In subsequent laser cladding, it helps to make the distribution of carbides formed during the cladding process more uniform. (2) Introducing ultrasonic vibration process to assist laser cladding can refine the microstructure of the coating, play a role in fine grain strengthening, and improve the performance of the composite coating; and under the continuous action of ultrasonic vibration, it can reduce powder agglomeration, make the powder distribution more uniform, and form a seamless, dense and uniform coating. (3) Under the action of high energy of laser beam, the dilution rate of coating and substrate is low, and the metallurgical bond formed is good, with high bonding strength, and it is not easy to peel off in the environment of friction and wear. (4) TiC precipitation The solid solution strengthening produced by finely dispersed carbides, the partial contact stress borne by TiC, and the resulting fine grain strengthening improve the hardness and wear resistance of the coating; the fine grain strengthening produced by the addition of TiC reduces the porosity and cracks of the coating, making the coating structure more compact, making it less susceptible to the penetration of corrosive media, and improving the corrosion resistance of the coating.

[0050] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for preparing corrosion-resistant and wear-resistant coatings for piston rods and cylinders using laser cladding, characterized in that, Includes the following steps: S1. Material preparation: 75%~95% nickel-based powder, 5%~25% ceramic powder, by mass percentage; S2. Powder mixing: Nickel-based powder and ceramic powder are mixed to form spherical powder with a particle size in the range of 45~105μm; S3. Drying: Dry the spherical powder at 100-120℃ for 4-6 hours to obtain the cladding powder; S4. The cladding powder is laser-clad onto the substrate to prepare a coating under the assistance of ultrasonic vibration. The ultrasonic vibration refers to the transmission of ultrasound to the worktable supporting the substrate through an ultrasonic vibration device. The worktable transmits the ultrasonic waves to the molten pool, so that the ultrasonic waves act on the molten pool continuously.

2. The preparation method according to claim 1, characterized in that, The ultrasonic vibration frequency range is set to 30-50Hz, and the ultrasonic amplitude range is 35-50μm.

3. The preparation method according to claim 1, characterized in that, The laser cladding refers to a laser power of 800-1100W, a scanning speed of 16-20mm / s, and a powder feeding rate of 0.5-0.9r / s.

4. The preparation method according to claim 1, characterized in that, The powder mixing is carried out using an omnidirectional planetary ball mill, with the ball mill rotating at 190-210 r / min and revolving at 3-7 r / min, and stirring for 7-9 hours.

5. The preparation method according to claim 1, characterized in that, In step S2, the spherical powder is a near-spherical powder with a surface roughness of less than 0.5 μm in more than 75% of the single particle surface area, and its sphericity is ≥0.

9.

6. The preparation method according to claim 1, characterized in that, Both the nickel-based powder and the ceramic powder are gas-atomized powders with a purity of 99.9% and a particle size of 45μm~105μm.

7. The preparation method according to claim 1, characterized in that, In step S1, the ceramic powder accounts for 5% to 15% of the total mass.

8. The preparation method according to claim 1, characterized in that, The nickel-based powder is atomized spherical Hastelloy C-276 powder, and the ceramic powder is TiC powder.

9. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of nickel-based powder to ceramic powder is 0.95:0.05 or 0.85:0.

15.

10. The laser cladding method for preparing the corrosion-resistant and wear-resistant coating of the piston rod and cylinder as described in any one of claims 1-9, characterized in that, Suitable for use in environments with severe wear and / or corrosion.

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