Method for improving wear resistance and corrosion resistance of 45CrNi steel surface

Abstract

The application belongs to the technical field of friction and wear and corrosion, and discloses a method for improving the wear resistance and corrosion resistance of a 45CrNi steel surface. The method prepares a MoSi2 coating on the surface of the 45CrNi steel workpiece, and cooperates with subsequent oxidation treatment to enhance the wear resistance and corrosion resistance of the coating. The process is simple, efficient and low in cost, can significantly improve the wear resistance and corrosion resistance of the workpiece, and effectively prolong the service life of the workpiece in a seawater environment. The core principle is that the MoSi2 coating prepared by the supersonic plasma spraying equipment has high hardness and can form a passivation film on the surface, and has excellent basic wear resistance and corrosion resistance; the subsequent oxidation treatment can also generate oxides on the surface and inside the coating, which have the functions of isolating corrosive media and lubrication, and further strengthens the protection effect.

Description

Technical Field

[0001] This invention belongs to the field of friction, wear and corrosion technology, and particularly relates to a method for improving the wear resistance and corrosion resistance of 45CrNi steel surface. Background Technology

[0002] Marine equipment operating in seawater environments suffers from both corrosion and wear on its moving parts, such as shafts, pumps, and propellers. Due to the unique characteristics of the seawater environment, oils and greases cannot be used for lubrication, often leading to premature equipment failure due to corrosion and wear. Improving the wear and corrosion resistance of materials through surface coatings is an economical and effective solution.

[0003] Plasma spraying is a common method for preparing surface coatings, offering advantages such as fast preparation speed, low cost, minimal restrictions on workpiece size and shape, and uniform and controllable coating thickness. Supersonic plasma spraying technology utilizes the "expanding arc" formed by mixing a "non-transfer" plasma arc with a high-speed gas flow to obtain a stable and concentrated supersonic plasma stream. Compared to ordinary air plasma spraying, it also features a wider range of sprayable materials, lower coating oxidation levels, fewer defects, and higher bonding strength, making it more suitable for preparing high-performance protective coatings.

[0004] MoSi2 is a cermet material possessing both metallic and covalent bonds, exhibiting numerous superior properties that make it an ideal material for preparing protective coatings. Firstly, MoSi2 ceramic coatings have high hardness and generate lubricating SiO2 during friction, resulting in excellent wear resistance and effective protection of the substrate. Secondly, MoSi2 can form a dense passivation film in NaCl solution, demonstrating good corrosion resistance. Thirdly, MoSi2 can be alloyed with silicides to further enhance its performance. Furthermore, MoSi2 is low-cost, non-toxic, and environmentally friendly, possessing extremely high research and application value. Summary of the Invention

[0005] The purpose of this invention is to provide a method for improving the wear resistance and corrosion resistance of 45CrNi steel surface, thereby addressing the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for improving the wear resistance and corrosion resistance of 45CrNi steel surface includes the following steps: Step S1: Sandblasting the 45CrNi steel plate with SiC improves the surface roughness of the substrate and enhances the bonding strength between the coating and the substrate. Step S2: Clean the sandblasted sample with acetone to remove surface impurities; Step S3: Prepare a MoSi2 coating on the sample surface using a supersonic plasma spraying device; Step S4: Use sandpaper to gradually polish the surface of the MoSi2 coating to control the surface roughness of the coating to within 1. Below m; Step S5: Place the polished coating sample into anhydrous ethanol and perform ultrasonic cleaning; Step S6: Place the ultrasonically cleaned sample in a heating furnace and continuously introduce air during the heating process to cause the coating to undergo an oxidation reaction.

[0007] Furthermore, in step S3, the MoSi2 powder used needs to undergo agglomeration and granulation treatment, and the powder particle size is controlled at 45 mm. m~60 m.

[0008] Furthermore, in step S3, the process parameters of the supersonic plasma spraying equipment are: voltage 52.7V, current 600A, flow rates of plasma gas Ar and H2 are 35L / min and 12L / min respectively, flow rate of powder carrier gas Ar is 2.6L / min, and spraying distance is set to 110mm.

[0009] Furthermore, in step S3, the spraying distance of the supersonic plasma spraying equipment is 110mm.

[0010] Furthermore, in step S4, the polishing process requires sequential use of 800-grit, 1500-grit, 2000-grit, and 3000-grit sandpaper for progressive processing.

[0011] Furthermore, in step S5, the time for ultrasonic cleaning with anhydrous ethanol is 60 seconds.

[0012] Furthermore, in step S6, after the heating furnace is heated to 800°C, the coating sample is placed in the furnace and kept at that temperature for 1 hour. Then, the sample is allowed to cool naturally with the furnace to complete the oxidation process.

[0013] Compared with the prior art, the beneficial effects of the present invention are: This method for improving the wear resistance and corrosion resistance of 45CrNi steel surfaces involves preparing a MoSi2 coating on the workpiece surface and further enhancing its wear resistance and corrosion resistance through oxidation treatment. The process is simple, efficient, and low-cost, significantly improving the wear resistance and corrosion resistance of the workpiece. The MoSi2 surface coating, prepared using supersonic plasma spraying, has high hardness and produces a surface passivation film, exhibiting excellent wear resistance and corrosion resistance. Subsequent oxidation treatment generates oxides on the coating surface and within the coating, providing both isolation from corrosive media and lubrication. Therefore, this method effectively improves the wear resistance and corrosion resistance of the workpiece, extending its service life in seawater environments. Attached Figure Description

[0014] Figure 1 These are cross-sectional views of the sprayed coating (MoSi2) and the post-treatment sprayed coating (P-MoSi2) in this invention.

[0015] Figure 2 This is a component analysis diagram of the spray coating (MoSi2) and the post-treatment spray coating (P-MoSi2) in this invention.

[0016] Figure 3 This is a cross-sectional oxygen distribution diagram of the sprayed coating (MoSi2) and the post-treatment sprayed coating (P-MoSi2) in this invention.

[0017] Figure 4 This is a schematic diagram illustrating the protective principle of the spray coating (MoSi2) and post-treatment spray coating (P-MoSi2) on the workpiece in this invention.

[0018] Figure 5 This is a schematic diagram showing the wear rate of the sprayed coating (MoSi2) and the post-treatment sprayed coating (P-MoSi2) in seawater in this invention.

[0019] Figure 6 This is a graph showing the friction coefficients of the sprayed coating (MoSi2) and the post-treatment sprayed coating (P-MoSi2) in seawater in this invention.

[0020] Figure 7 The polarization curves of the sprayed coating (MoSi2) and the post-treatment sprayed coating (P-MoSi2) in this invention are shown under static corrosion and corrosion wear conditions. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0023] like Figure 1-7 As shown, a method for improving the wear resistance and corrosion resistance of 45CrNi steel surface is provided in one embodiment of the present invention, comprising the following steps: Step S1: Sandblasting the 45CrNi steel plate with SiC improves the surface roughness of the substrate and enhances the bonding strength between the coating and the substrate. Step S2: Clean the sandblasted sample with acetone to remove surface impurities; Step S3: Prepare a MoSi2 coating on the sample surface using a supersonic plasma spraying device; Step S4: Use sandpaper to gradually polish the surface of the MoSi2 coating to control the surface roughness of the coating to within 1. Below m; Step S5: Place the polished coating sample into anhydrous ethanol and perform ultrasonic cleaning; Step S6: Place the ultrasonically cleaned sample in a heating furnace and continuously introduce air during the heating process to cause the coating to undergo an oxidation reaction.

[0024] The MoSi2 coating prepared by the method of this invention has an average cross-sectional hardness of 708 HV0.05. The coating exhibits a typical layered structure, with h-MoSi2 as the main phase, and also containing Mo5Si3 and t-MoSi2 phases. After oxidation treatment at 800℃ for 1 hour, oxides are generated on both the surface and inside of the coating. Although the coating hardness decreases slightly and the main phase remains h-MoSi2, MoO3, SiO2, and Mo9O are newly formed. 26 Three phases.

[0025] This oxidation modification treatment only requires a conventional heating furnace and does not require the introduction of additional special gases, making it low-cost and easy to operate. Furthermore, the oxidized P-MoSi2 coating exhibits significantly improved wear resistance and corrosion resistance, with a reduced coefficient of friction during friction and wear processes, further enhancing its protective effect. Electrochemical test data shows that the electrochemical performance of the oxidized coating is significantly optimized under both static corrosion and corrosive wear conditions. The electrochemical parameters of the sprayed coating (MoSi2) and the post-treatment sprayed coating (P-MoSi2) are shown in the table below.

[0026] Table 1 Electrochemical parameters of sprayed coating (MoSi2) and post-treatment sprayed coating (P-MoSi2)

[0027] In a preferred embodiment of the present invention, in step S3, the MoSi2 powder undergoes agglomeration and granulation treatment, and the powder diameter is 45 mm. m to 60 m.

[0028] In a preferred embodiment of the present invention, the parameters of the supersonic plasma spraying equipment in step S3 are as follows: voltage of 52.7V, current of 600A, flow rates of plasma gas Ar and H2 of 35L / min and 12L / min respectively, and flow rate of powder carrier gas Ar of 2.6L / min.

[0029] In a preferred embodiment of the present invention, in step S3, the spraying distance of the supersonic plasma spraying equipment is 110mm.

[0030] In a preferred embodiment of the present invention, in step S4, the surface of the MoSi2 coating is polished using sandpaper of 800 grit, 1500 grit, 2000 grit and 3000 grit.

[0031] In a preferred embodiment of the present invention, the cleaning time in step S5 is 60 seconds.

[0032] In a preferred embodiment of the present invention, in step S6, the coating sample is placed in the heating furnace after being heated to 800°C, and is kept at that temperature for 1 hour before being cooled with the furnace.

[0033] The working principle of this invention is: This method for improving the wear and corrosion resistance of 45CrNi steel combines physical densification through supersonic spraying with chemical densification through oxidation at 800℃. By preparing a MoSi2 coating on the workpiece surface and further enhancing its wear and corrosion resistance through oxidation, it effectively resists corrosion and wear in the seawater environment, reducing material loss. The overall process is simple and efficient, requiring only conventional supersonic plasma spraying equipment and a heating furnace, without the need for special customized devices. This results in low process costs and easy industrial application. The MoSi2 surface coating prepared by supersonic plasma spraying has high hardness and produces a surface passivation film, exhibiting excellent wear and corrosion resistance. Subsequent oxidation treatment creates oxides on the coating surface and within the coating that isolate corrosive media and provide lubrication. Therefore, this method effectively improves the wear and corrosion resistance of workpieces, extends their service life in seawater environments, and solves the problem of premature failure of moving parts in marine equipment due to corrosion and wear, providing an economical and effective technical solution for the protection of marine engineering equipment.

[0034] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the specific embodiments described above. For those skilled in the art, any modifications and improvements made without departing from the concept of the present invention should be included within the scope of protection of the present invention and will not affect the implementation effect and practical application value of the present invention.

Claims

1. The method for improving the wear resistance and corrosion resistance of 45CrNi steel surface according to the present invention specifically includes the following steps: Step S1: Sandblasting the 45CrNi steel plate with SiC improves the surface roughness of the substrate and enhances the bonding strength between the coating and the substrate. Step S2: Clean the sandblasted sample with acetone to remove surface impurities; Step S3: Prepare a MoSi2 coating on the sample surface using a supersonic plasma spraying device; Step S4: Use sandpaper to gradually polish the surface of the MoSi2 coating to control the surface roughness of the coating to within 1. Below m; Step S5: Place the polished coating sample into anhydrous ethanol and perform ultrasonic cleaning; Step S6: Place the ultrasonically cleaned sample in a heating furnace and continuously introduce air during the heating process to cause the coating to undergo an oxidation reaction.

2. The method for improving the wear resistance and corrosion resistance of 45CrNi steel surface according to claim 1, characterized in that, In step S3, the MoSi2 powder used needs to undergo agglomeration and granulation treatment, and the powder particle size needs to be controlled at 45. m~60 m.

3. The method for improving the wear resistance and corrosion resistance of 45CrNi steel surface according to claim 2, characterized in that, In step S3, the process parameters of the supersonic plasma spraying equipment are: voltage 52.7V, current 600A, flow rates of plasma gas Ar and H2 are 35L / min and 12L / min respectively, flow rate of powder carrier gas Ar is 2.6L / min, and spraying distance is set to 110mm.

4. The method for improving the wear resistance and corrosion resistance of 45CrNi steel surface according to claim 1, characterized in that, In step S4, the sanding process requires sequentially using sandpaper of 800 grit, 1500 grit, 2000 grit, and 3000 grit.

5. The method for improving the wear resistance and corrosion resistance of 45CrNi steel surface according to claim 1, characterized in that, In step S5, the ultrasonic cleaning time with anhydrous ethanol is 60 seconds.

6. The method for improving the wear resistance and corrosion resistance of 45CrNi steel surface according to claim 1, characterized in that, In step S6, after the heating furnace is heated to 800°C, the coating sample is placed in the furnace and kept at that temperature for 1 hour. Then, the sample is allowed to cool naturally with the furnace to complete the oxidation process.

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