Preparation method of nickel-titanium alloy coating on surface of steel base material

Abstract

The invention discloses a preparation method of a nickel-titanium alloy coating on the surface of a steel base material. The preparation method comprises the following steps: (1) pretreating the surface of steel; (2) nickel-titanium alloy powder is dried and then put into a powder feeder; the nickel-titanium alloy powder is composed of the following elements in percentage by mass: 52%-58% of Ni, 0.01%-0.04% of Fe, 0.009%-0.04% of Co, 0.009%-0.04% of Cu, 0.009%-0.04% of Cr, 0.009%-0.04% of Nb, 0.01%-0.03% of C, 0.02%-0.04% of O, less than or equal to 0.004% of N, less than or equal to 0.02% of H and the balance of Ti, and the particle size of the powder is 45-105 microns; and (3) preparing the nickel-titanium alloy coating on the surface of the steel base material by adopting a laser cladding coaxial powder feeding mode under the protection of argon, and then polishing the surface of the nickel-titanium alloy coating to be flat by adopting a mechanical mode. According to the nickel-titanium alloy coating on the surface of the steel base material, the high-brittleness interface of a pure titanium alloy coating is effectively improved, the bonding strength and the surface titanium content of the coating are improved, and good corrosion-resistant protection is provided for steel.

Description

Technical Field

[0001] This invention belongs to the field of metal laser cladding technology, specifically relating to a method for preparing a nickel-titanium alloy coating on the surface of a steel substrate. Background Technology

[0002] Applying a suitable coating to the surface of a steel substrate is an effective way to mitigate corrosion. Nickel-titanium alloys, as shape memory alloys, perform exceptionally well in a variety of corrosive environments, especially in marine and high-temperature environments. Coating steel substrates with nickel-titanium alloys can significantly improve the substrate's corrosion resistance, wear resistance, and mechanical properties, thereby extending the service life of the equipment.

[0003] However, most titanium alloy products on the market currently employ the traditional production process of smelting, forging, and machining, and the high cost significantly limits their application. Applying a titanium alloy coating to the surface of steel can meet the material's corrosion resistance requirements while reducing the application cost of titanium alloy products, making it one of the effective ways to achieve large-scale application of titanium alloys in the marine engineering field.

[0004] Laser cladding has advantages such as a small heat-affected zone, strong metallurgical bond between the cladding layer and the substrate, coating that is not easy to fall off, dense cladding layer, and high applicability to materials. It is often used for the preparation of surface coatings.

[0005] To improve the corrosion resistance of steel substrates, the nickel-titanium alloy coating of this invention has a salt spray resistance of 1000h and exhibits excellent corrosion resistance. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a nickel-titanium alloy coating on the surface of a steel substrate. The method involves forming a nickel-titanium alloy coating on the surface of a steel substrate by laser cladding of nickel-titanium alloy powder, which has excellent wear resistance and corrosion resistance.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: The present invention discloses a method for preparing a nickel-titanium alloy coating on a steel substrate, comprising the following steps: (1) Pre-treatment of steel surface: Grind the surface of steel substrate with a grinding wheel to remove oxide scale, and then clean it with alcohol; preheat in advance; (2) After drying, the nickel-titanium alloy powder is placed in a powder feeder; the nickel-titanium alloy powder is composed of the following elements in mass fraction: Ni (nickel) 52%~58%, Fe (iron) 0.01%~0.04%, Co (cobalt) 0.009%~0.04%, Cu (copper) 0.009%~0.04%, Cr (chromium) 0.009%~0.04%, Nb (niobium) 0.009%~0.04%, C (carbon) 0.01%~0.03%, O (oxygen) 0.02%~0.04%, N (nitrogen) ≤0.004%, H (hydrogen) ≤0.02%, with the balance being Ti, and the powder particle size is 45~105μm; (3) Under argon protection, a nickel-titanium alloy coating is prepared on the surface of a steel substrate by laser cladding and coaxial powder feeding. Then, the surface of the nickel-titanium alloy coating is polished smooth by mechanical means.

[0008] Preferably, in step (1), the steel substrate is preheated to 195-205°C.

[0009] Preferably, in step (2), the nickel-titanium alloy powder is dried in a sealed blower drying oven at 120°C for more than 2 hours.

[0010] Preferably, in step (3), the powder feeding rate of the powder feeder is 30-35 g / min.

[0011] Preferably, in step (3), the process parameters for laser cladding are as follows: the laser beam is scanned vertically, and argon gas is blown laterally for protection during the scanning process, while argon gas is blown coaxially to protect the lens barrel; the laser power is 1.8 to 2.2 KW, the scanning speed is 2.1 to 3.2 mm / s, the spot diameter is 3.5 to 4.5 mm, the distance from the laser mirror to the sample surface is 95 to 100 mm, the overlap size is 1.5 to 2 mm, and the argon gas protection pressure is 0.3 to 0.7 MPa.

[0012] Preferably, in step (2), the preparation method of the nickel-titanium alloy powder includes the following steps: weighing the solvent and placing it in a dispersion tank for stirring, adding a binder until dissolved; sequentially adding the raw material powder of the nickel-titanium alloy, grinding and dispersing at high speed for 20 to 50 minutes until the powder diameter is 45 to 105 μm, and then drying.

[0013] The high-speed grinding and dispersion is carried out using a planetary ball mill with a rotation speed of 1000-1500 rpm.

[0014] Preferably, the solvent is acetone and / or butyl acetate, and the amount of solvent used is 10% to 15% of the mass of the nickel-titanium alloy powder.

[0015] Preferably, the binder is polyvinyl alcohol with a degree of polymerization of 500 to 2000, and the amount of the binder is 1.0% to 1.5% of the mass of the nickel-titanium alloy powder.

[0016] Preferably, the drying process is carried out in a sealed, blower-driven drying oven at 120°C for more than 2 hours.

[0017] Compared with the prior art, the present invention has the following technical advantages: The nickel-titanium alloy coating on the surface of steel substrate prepared by this invention can eliminate the influence of the difference in flowability between nickel and titanium elemental powders, effectively improve the high brittleness interface of pure titanium alloy coating, improve the bonding strength and surface titanium content of the coating, and ultimately provide good corrosion protection for steel. It has good application prospects in the field of steel material protection for ships and marine engineering. Attached Figure Description

[0018] Figure 1 The image shows the metallographic structure of the nickel-titanium alloy coating of Example 1. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 A method for preparing a nickel-titanium alloy coating on a steel substrate includes the following steps: (1) Pre-treatment of steel surface: Use a grinding wheel to grind the surface of the steel substrate to remove oxide scale, and then clean it with alcohol to remove any oil stains and rust that may remain on the ground surface; preheat to 200℃ in advance; (2) Place the nickel-titanium alloy powder into the powder feeder and set the powder feeding rate to 30 g / min; the nickel-titanium alloy powder is composed of the following elements in mass fraction: Ni 58%, Fe 0.01%, Co 0.01%, Cu 0.01%, Cr 0.01%, Nb 0.01%, C 0.01%, O 0.01%, N 0.004%, H 0.01%, Ti balance; (3) Under argon protection, a nickel-titanium alloy coating is prepared on the surface of a steel substrate by laser cladding and coaxial powder feeding. Then, the surface of the nickel-titanium alloy coating is polished smooth by mechanical means. The laser cladding process parameters are as follows: the laser beam is scanned vertically, and argon gas is blown laterally for protection during the scanning process, while argon gas is blown coaxially to protect the lens barrel; the laser power is 2.0KW, the scanning speed is 2.2mm / s, the spot diameter is 4mm, the distance from the laser mirror to the sample surface is 100mm, the overlap size is 1.6mm, and the argon gas protection pressure is 0.4MPa.

[0021] The preparation method of nickel-titanium alloy powder is as follows: 12.7 ml of solvent acetone is weighed and placed in a dispersion tank and stirred slowly. Then, 1 g of binder polyvinyl alcohol with a polymerization degree of 1000 is added until dissolved. Metal powder is added in proportion. A total of 100 g of powder is ground and dispersed in a planetary ball mill at 1500 rpm for 30 min until the powder diameter is 45-105 μm. The powder is then dried at 120℃ for 2.5 hours.

[0022] Example 2 A method for preparing a nickel-titanium alloy coating on a steel substrate includes the following steps: (1) Pre-treatment of steel surface: Use a grinding wheel to grind the surface of the steel substrate to remove oxide scale, and then clean it with alcohol to remove any oil stains and rust that may remain on the ground surface; preheat to 200℃ in advance; (2) Place the nickel-titanium alloy powder into the powder feeder and set the powder feeding rate to 32 g / min; the nickel-titanium alloy powder is composed of the following elements in mass fraction: Ni 54%, Fe 0.02%, Co 0.02%, Cu 0.02%, Cr 0.02%, Nb 0.02%, C 0.02%, O 0.02%, N 0.002%, H 0.02%, Ti balance; (3) Under argon protection, a nickel-titanium alloy coating is prepared on the surface of a steel substrate by laser cladding and coaxial powder feeding. Then, the surface of the nickel-titanium alloy coating is polished smooth by mechanical means. The laser cladding process parameters are as follows: the laser beam is scanned vertically, and argon gas is blown laterally for protection during the scanning process, while argon gas is blown coaxially to protect the lens barrel; the laser power is 2.0KW, the scanning speed is 2.2mm / s, the spot diameter is 4mm, the distance from the laser mirror to the sample surface is 100mm, the overlap size is 1.6mm, and the argon gas protection pressure is 0.4MPa.

[0023] The preparation method of nickel-titanium alloy powder is the same as in Example 1.

[0024] Example 3 A method for preparing a nickel-titanium alloy coating on a steel substrate includes the following steps: (1) Pre-treatment of steel surface: Use a grinding wheel to grind the surface of the steel substrate to remove oxide scale, and then clean it with alcohol to remove any oil stains and rust that may remain on the ground surface; preheat to 200℃ in advance; (2) Place the nickel-titanium alloy powder into the powder feeder and set the powder feeding rate to 34 g / min; the nickel-titanium alloy powder is composed of the following elements by mass fraction: Ni 53%, Fe 0.03%, Co 0.03%, Cu 0.03%, Cr 0.03%, Nb 0.03%, C 0.03%, O 0.03%, N 0.003%, H 0.015%, Ti balance; (3) Under argon protection, a nickel-titanium alloy coating is prepared on the surface of a steel substrate by laser cladding and coaxial powder feeding. Then, the surface of the nickel-titanium alloy coating is polished smooth by mechanical means. The laser cladding process parameters are as follows: the laser beam is scanned vertically, and argon gas is blown laterally for protection during the scanning process, while argon gas is blown coaxially to protect the lens barrel; the laser power is 2.0KW, the scanning speed is 2.2mm / s, the spot diameter is 4mm, the distance from the laser mirror to the sample surface is 100mm, the overlap size is 1.6mm, and the argon gas protection pressure is 0.4MPa.

[0025] The preparation method of nickel-titanium alloy powder is the same as in Example 1.

[0026] Example 4 A method for preparing a nickel-titanium alloy coating on a steel substrate includes the following steps: (1) Pre-treatment of steel surface: Use a grinding wheel to grind the surface of the steel substrate to remove oxide scale, and then clean it with alcohol to remove any oil stains and rust that may remain on the ground surface; preheat to 200℃ in advance; (2) Place the nickel-titanium alloy powder into the powder feeder and set the powder feeding rate to 35 g / min; the nickel-titanium alloy powder is composed of the following elements in mass fraction: Ni 52%, Fe 0.04%, Co 0.04%, Cu 0.04%, Cr 0.04%, Nb 0.04%, C 0.04%, O 0.04%, N 0.004%, H 0.009% and Ti balance; (3) Under argon protection, a nickel-titanium alloy coating is prepared on the surface of a steel substrate by laser cladding and coaxial powder feeding. Then, the surface of the nickel-titanium alloy coating is polished smooth by mechanical means. The laser cladding process parameters are as follows: the laser beam is scanned vertically, and argon gas is blown laterally for protection during the scanning process, while argon gas is blown coaxially to protect the lens barrel; the laser power is 2.0KW, the scanning speed is 2.2mm / s, the spot diameter is 4mm, the distance from the laser mirror to the sample surface is 100mm, the overlap size is 1.6mm, and the argon gas protection pressure is 0.4MPa.

[0027] The preparation method of nickel-titanium alloy powder is the same as in Example 1.

[0028] Comparative Example 1 A method for preparing a nickel-titanium alloy coating on a steel substrate includes the following steps: (1) Pre-treatment of steel surface: Use a grinding wheel to grind the surface of the steel substrate to remove oxide scale, and then clean it with alcohol to remove any oil stains and rust that may remain on the ground surface; preheat to 200℃ in advance; (2) Place the nickel-titanium alloy powder into the powder feeder and set the powder feeding rate to 35 g / min; the nickel-titanium alloy powder is composed of the following elements in mass fraction: Ni 0%, Fe 0.04%, Co 0.04%, Cu 0.04%, Cr 0.04%, Nb 0.04%, C 0.04%, O 0.04%, N 0.004%, H 0.009% and Ti balance; (3) Under argon protection, a nickel-titanium alloy coating is prepared on the surface of a steel substrate by laser cladding and coaxial powder feeding. Then, the surface of the nickel-titanium alloy coating is polished smooth by mechanical means. The laser cladding process parameters are as follows: the laser beam is scanned vertically, and argon gas is blown laterally for protection during the scanning process, while argon gas is blown coaxially to protect the lens barrel; the laser power is 2.0KW, the scanning speed is 2.2mm / s, the spot diameter is 4mm, the distance from the laser mirror to the sample surface is 100mm, the overlap size is 1.6mm, and the argon gas protection pressure is 0.4MPa.

[0029] The preparation method of nickel-titanium alloy powder is the same as in Example 1.

[0030] Comparative Example 2 A method for preparing a nickel-titanium alloy coating on a steel substrate includes the following steps: (1) Pre-treatment of steel surface: Use a grinding wheel to grind the surface of the steel substrate to remove oxide scale, and then clean it with alcohol to remove any oil stains and rust that may remain on the ground surface; preheat to 200℃ in advance; (2) Place the nickel-titanium alloy powder into the powder feeder, and set the powder feeding rate to 30 g / min; the nickel-titanium alloy powder is composed of the following elements by mass fraction: Ni 99.91%, Fe 0.01%, Co 0.01%, Cu 0.01%, Cr 0.01%, Nb 0.01%, C 0.01%, O 0.01%, N 0.004%, H 0.01% and Ti 0%; (3) Under argon protection, a nickel-titanium alloy coating is prepared on the surface of a steel substrate by laser cladding and coaxial powder feeding. Then, the surface of the nickel-titanium alloy coating is polished smooth by mechanical means. The laser cladding process parameters are as follows: the laser beam is scanned vertically, and argon gas is blown laterally for protection during the scanning process, while argon gas is blown coaxially to protect the lens barrel; the laser power is 2.0KW, the scanning speed is 2.2mm / s, the spot diameter is 4mm, the distance from the laser mirror to the sample surface is 100mm, the overlap size is 1.6mm, and the argon gas protection pressure is 0.4MPa.

[0031] The preparation method of nickel-titanium alloy powder is the same as in Example 1.

[0032] Test Experiment Example 1. The metallographic images of the nickel-titanium alloy coatings prepared in Examples 1-4 were observed using a metallographic microscope to visually analyze the surface microstructure of the prepared nickel-titanium alloy coatings. From Figure 1 It can be observed that the nickel-titanium alloy coating of Example 1 has a dense cladding layer, good interfacial bonding, and no obvious defects.

[0033] 2. The hardness of the nickel-titanium alloy coatings prepared in Examples 1-4 and Comparative Examples 1-2 was tested, and the results are shown in Table 1.

[0034] 3. The nickel-titanium alloy coatings prepared in Examples 1-4 and Comparative Examples 1-2 were immersed in simulated seawater (3.5% NaCl) solution to test their corrosion resistance: the coating sample was used as the working electrode, the saturated calomel electrode (SCE) as the reference electrode, and the platinum sheet electrode as the auxiliary electrode. The working area of ​​the sample was 1 cm². 2 The scanning speed was 2 mV / s. The impedance (EIS) diagram and electrochemical polarization curve were measured on an electrochemical workstation. The self-corrosion potential (Ecoor) and self-corrosion current density (Icoor) of the nickel-titanium alloy coating were calculated. The results are shown in Table 1.

[0035] Table 1. Hardness, self-corrosion potential, and self-corrosion current of Examples 1-3 4. The nickel-titanium alloy coatings prepared in Examples 1 to 4 were subjected to a neutral salt spray test: In accordance with ISO 9227:2017, a 3.5% NaCl aqueous solution was used to conduct a salt spray test for 1000 hours at a temperature of (35±2)℃. The test results were evaluated based on the degree of corrosion, and two parallel tests were performed.

[0036] The test results show that the hardness of Comparative Example 1 is only 122 HV, which is much lower than that of the other examples (the hardness of Examples 1-4 is between 524 and 570 HV). Low hardness makes the coating easily scratched and worn during use, making it difficult to provide good wear resistance protection; its self-corrosion current is 8.1E to 7 A·cm. -2 Although the numerical value is small, the self-corrosion potential is ~475mV. Combined with the self-corrosion current and other comprehensive analyses, the corrosion resistance cannot be effectively guaranteed in actual corrosive environments, and the low hardness significantly reduces its practicality. Comparative Example 2 has a hardness of 368HV, still lower than the example, and a self-corrosion potential of ~710mV, which is more negative than the example (the self-corrosion potential of the example is between 529 and 589mV). The self-corrosion current is 2.84E to 6A·cm. -2 This indicates that it is more prone to corrosion in corrosive environments, resulting in insufficient corrosion resistance. Furthermore, its insufficient hardness also affects its performance in scenarios requiring wear resistance. In contrast, the alloy coatings in the embodiments of this invention exhibit significantly higher hardness than the comparative example, providing better wear resistance. They also possess a relatively superior self-corrosion potential and a reasonable self-corrosion current that effectively delays corrosion. Overall, they demonstrate significant advantages in both hardness and corrosion resistance, better meeting the practical application requirements for wear-resistant and corrosion-resistant coatings.

[0037] Table 2 Salt spray test results of nickel-titanium alloy cladding layers in Examples 1-4 and Comparative Examples 1-2 Examples 1-4 show uniform and crack-free coatings. The alloy coating has a significantly higher hardness than the comparative example, providing better wear resistance. It also exhibits superior self-corrosion related indicators, effectively delaying corrosion. In the salt spray test, the coating maintains a uniform and crack-free state, demonstrating significant advantages in hardness, corrosion resistance, and coating integrity. This meets the practical application requirements for wear-resistant, corrosion-resistant, and structurally intact coatings.

[0038] In contrast, the coating in Comparative Example 2 showed cracks. Cracking compromises the integrity of the coating, making it easier for corrosive media to penetrate, accelerating substrate corrosion, and severely impacting the coating's protective effect and service life.

Claims

1. A method for preparing a nickel-titanium alloy coating on the surface of a steel substrate, characterized in that, Includes the following steps: (1) Pre-treatment of steel surface: Use a grinding wheel to grind the surface of the steel substrate to remove oxide scale, and then clean it with alcohol; Preheat in advance; (2) After drying, the nickel-titanium alloy powder is placed in a powder feeder; the nickel-titanium alloy powder is composed of the following elements by mass fraction: Ni 52%~58%, Fe 0.01%~0.04%, Co 0.009%~0.04%, Cu 0.009%~0.04%, Cr 0.009%~0.04%, Nb 0.009%~0.04%, C 0.01%~0.03%, O 0.02%~0.04%, N≤0.004%, H≤0.02%, with the balance being Ti, and the powder particle size is 45~105μm; (3) Under argon protection, a nickel-titanium alloy coating is prepared on the surface of a steel substrate by laser cladding and coaxial powder feeding. Then, the surface of the nickel-titanium alloy coating is polished smooth by mechanical means.

2. The method for preparing a nickel-titanium alloy coating on a steel substrate according to claim 1, characterized in that, In step (1), the steel substrate is preheated to 195-205°C.

3. The method for preparing a nickel-titanium alloy coating on a steel substrate according to claim 1, characterized in that, In step (2), the nickel-titanium alloy powder is dried in a sealed blower drying oven at 120°C for more than 2 hours.

4. The method for preparing a nickel-titanium alloy coating on a steel substrate according to claim 1, characterized in that, In step (3), the powder feeder feeds 30-35 g / min.

5. The method for preparing a nickel-titanium alloy coating on a steel substrate according to claim 1, characterized in that, In step (3), the process parameters for laser cladding are as follows: the laser beam is scanned vertically, and argon gas is blown laterally for protection during the scanning process, while argon gas is blown coaxially to protect the lens barrel; the laser power is 1.8 to 2.2 KW, the scanning speed is 2.1 to 3.2 mm / s, the spot diameter is 3.5 to 4.5 mm, the distance from the laser mirror to the sample surface is 95 to 100 mm, the overlap size is 1.5 to 2 mm, and the argon gas protection pressure is 0.3 to 0.7 MPa.

6. The method for preparing a nickel-titanium alloy coating on a steel substrate according to claim 1, characterized in that, In step (2), the preparation method of the nickel-titanium alloy powder includes the following steps: weighing the solvent and placing it in a dispersion tank and stirring, adding the binder until dissolved; sequentially adding the raw material powder of the nickel-titanium alloy, grinding and dispersing at high speed for 20 to 50 minutes until the powder diameter is 45 to 105 μm, and then drying.

7. The method for preparing a nickel-titanium alloy coating on a steel substrate according to claim 6, characterized in that, The solvent is acetone and / or butyl acetate, and the amount of solvent used is 10% to 15% of the mass of the nickel-titanium alloy powder.

8. The method for preparing a nickel-titanium alloy coating on a steel substrate according to claim 6, characterized in that, The binder is polyvinyl alcohol with a degree of polymerization of 500 to 2000, and the amount of the binder is 1.0% to 1.5% of the mass of the nickel-titanium alloy powder.

9. The method for preparing a nickel-titanium alloy coating on a steel substrate according to claim 6, characterized in that, The drying process involves drying in a sealed, forced-air drying oven at 120°C for more than 2 hours.

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