A surface-modified centrifugal pump casing and a method of making and using the same

Abstract

The application relates to the technical field of anticorrosive coating, and discloses a surface-modified centrifugal pump shell and a preparation method and application thereof. In the application, the surface of the centrifugal pump shell is modified by plasma spraying of NiCrAlY alloy powder, then cyclohexane siloxane / ethyl titanate impregnation treatment is carried out, a continuous and dense coating is formed on the surface of the shell, finally, electron beam remelting is carried out on the surface coating, the surface of the coating is melted and recrystallized, the coating is changed from a layer of discontinuous mechanical combination into more dense and uniform metallurgical combination, the surface holes and defects are reduced, the internal structure of the coating is improved, the anticorrosion and hydrophobic performance of the coating are improved, and finally the anticorrosion and abrasion resistance of the centrifugal pump are improved. The coating has strong anticorrosion capacity, and can stably and long-term apply the shell material of the centrifugal pump and other equipment to an outdoor environment.

Description

Technical Field

[0001] This application relates to the field of anti-corrosion coating technology, and in particular to a surface-modified centrifugal pump housing, its preparation method, and its application. Background Technology

[0002] Centrifugal pumps, as a type of traditional machinery, are typically used to transport liquids from one place to another, and therefore frequently come into contact with water, chemicals, corrosive substances, etc. Anti-corrosion treatment of centrifugal pumps can effectively extend their lifespan, reduce the frequency of repairs and replacements, and save on maintenance costs.

[0003] Currently, the main methods for designing and developing anti-corrosion materials for centrifugal pumps include chemical precipitation and electrochemical methods. While these methods can achieve certain anti-corrosion effects, they all have different problems in application: chemically precipitated coatings are prone to peeling off; electrochemical methods have high operation and maintenance costs and poor economic efficiency. The extremely high central temperature and high jet velocity of a plasma arc can melt almost any metal into fine particles, allowing the powder to adhere better to the material surface and form a dense protective film. Combining plasma spraying with centrifugal pump protection, as a new technology, has great application potential and a promising future. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a surface-modified centrifugal pump housing and a method for preparing the same, so that the coating on the surface of the centrifugal pump housing has high adhesion, waterproof ability and salt spray corrosion resistance, thereby improving the corrosion resistance of the centrifugal pump housing.

[0005] Another objective of this application is to provide the application of the aforementioned centrifugal pump housing material in the manufacture of centrifugal pumps and to specifically provide a centrifugal pump.

[0006] To solve the aforementioned technical problems / achieve the aforementioned objectives, or at least partially solve the aforementioned technical problems / achieve the aforementioned objectives, as a first aspect of this application, a method for preparing a surface-modified centrifugal pump housing is provided, comprising:

[0007] Step 1: Clean the surface of the centrifugal pump casing;

[0008] Step 2: Plasma spraying is performed on the surface of the centrifugal pump housing using NiCrAlY alloy powder;

[0009] Step 3: After plasma spraying, the centrifugal pump housing is modified by immersion in a cyclohexylsiloxane / ethyl titanate composite solution and then dried;

[0010] Step 4: Perform electron beam remelting modification on the impregnated centrifugal pump housing to obtain a surface-modified centrifugal pump housing.

[0011] Optionally, in the NiCrAlY alloy powder, the mass percentage of each element is 65-70% Ni, 20-25% Cr, 5-15% Al, and Y > 0, totaling 100%. More preferably, in the NiCrAlY alloy powder, the mass percentage of each element is 65-70% Ni, 20-25% Cr, 5-15% Al, and Y ≥ 1%, totaling 100%. Even more preferably, in the NiCrAlY alloy powder, the mass percentage of each element is 65-70% Ni, 20-25% Cr, 5-15% Al, and 1-2% Y, totaling 100%.

[0012] Optionally, the protective gas used in the plasma spraying includes CF4 and He, or includes CF4 and Ar.

[0013] Optionally, the molar ratio of Si ions to Ti ions in the cyclohexylsiloxane / tetratitanate composite solution is 5:1 to 35:1.

[0014] Optionally, the process also includes roughening the surface of the centrifugal pump housing after impregnation modification in step 3.

[0015] As a second aspect of this application, a centrifugal pump housing prepared by the aforementioned preparation method is provided.

[0016] As a third aspect of this application, the use of the aforementioned centrifugal pump housing in the manufacture of centrifugal pumps is provided.

[0017] As a fourth aspect of this application, a centrifugal pump is provided, which includes the centrifugal pump housing described in this application.

[0018] This application modifies the surface of a centrifugal pump housing by plasma spraying with NiCrAlY alloy powder, followed by cyclohexylsiloxane / ethyl titanate impregnation treatment to form a continuous and dense coating on the housing surface. Finally, the surface coating is electron beam remelted, causing melting and recrystallization of the coating surface. This transforms the discontinuous mechanical bonding of the coating into a denser and more uniform metallurgical bonding, reducing surface porosity and defects, improving the internal microstructure of the coating, and enhancing its corrosion resistance and hydrophobic properties. Ultimately, this improves the centrifugal pump's corrosion resistance and abrasion resistance. This coating has strong corrosion resistance, enabling the housing materials of centrifugal pumps and other equipment to be stably used in outdoor environments for extended periods. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application.

[0020] Figure 1The image shown is an EDS surface scan of the Si and Ti element distribution of the modified film impregnated on the surface of the centrifugal pump housing before electron beam remelting.

[0021] Figure 2 The image shows SEM images of the plasma-sprayed film on the surface of the centrifugal pump casing before and after electron beam remelting, magnified by 200K. A: Before remelting; B: After remelting.

[0022] Figure 3 The figures show the macroscopic salt spray corrosion morphology of the centrifugal pump casing after 600 hours with and without coating; A-1: ​​Before the test without coating; A-2: After the test without coating; B-1: Before the test with coating; B-2: After the test with coating.

[0023] Figure 4 The results show the surface contact angle test results of the centrifugal pump casing with and without coating; A: No coating; B: With coating;

[0024] Figure 5 The image shows the Nyquist spectrum of the centrifugal pump casing with and without coating.

[0025] Figure 6 The diagram shows the surface frequency-phase angle of the centrifugal pump casing with and without coating. Detailed Implementation

[0026] This application discloses a surface-modified centrifugal pump housing, its preparation method, and its application. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this application. The centrifugal pump housing, its preparation method, and its application described in this application have been described through preferred embodiments. Those skilled in the art can obviously make modifications or appropriate changes and combinations to the centrifugal pump housing, its preparation method, and its application described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this application. Obviously, the described embodiments are only some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application.

[0027] It should be noted that, in this document, relational terms such as "first" and "second," "step 1" and "step 2," and "(1)" and "(2)" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Moreover, the embodiments and features described in this application can be combined with each other without conflict.

[0028] In the first aspect of this application, a method for preparing a surface-modified centrifugal pump housing is provided, comprising:

[0029] Step 1: Clean the surface of the centrifugal pump casing;

[0030] Step 2: Plasma spraying is performed on the surface of the centrifugal pump housing using NiCrAlY alloy powder;

[0031] Step 3: After plasma spraying, the centrifugal pump housing is modified by immersion in a cyclohexylsiloxane / ethyl titanate composite solution and then dried;

[0032] Step 4: Perform electron beam remelting modification on the impregnated centrifugal pump housing to obtain a surface-modified centrifugal pump housing.

[0033] In some embodiments of this application, step 1 includes: sanding the surface of the centrifugal pump housing with sandpaper, then degreasing and ultrasonically cleaning.

[0034] In some embodiments of this application, plasma spraying employs arc discharge technology to generate high-energy electrons and ions, which then coat the surface with NiCrAlY alloy powder. In the NiCrAlY alloy powder, the mass percentages of each element are: Ni 65-70%, Cr 20-25%, Al 5-15%, Y > 0, totaling 100%. Compared to NiCrAl alloy powder, the appropriate addition of Y can improve the adhesion and durability of the sprayed film, and prolong the time before the first oxidation corrosion occurs. In other embodiments of this application, the mass percentages of each element in the NiCrAlY alloy powder are: Ni 65-70%, Cr 20-25%, Al 5-15%, Y ≥ 1%, totaling 100%. In still other embodiments of this application, the mass percentages of each element in the NiCrAlY alloy powder are: Ni 65-70%, Cr 20-25%, Al 5-15%, Y 1-2%, totaling 100%. In some embodiments of this application, the mass percentage of Ni in the NiCrAlY alloy powder can be 65%, 66%, 67%, 68%, 69%, or 70%, Cr can be 20%, 21%, 22%, 23%, 24%, or 25%, Al can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%, and Y can be 1% or 2%. The NiCrAlY alloy powder is prepared using conventional alloy preparation methods according to the mass percentage of each element, such as mechanical alloying, powder metallurgy, or chemical precipitation.

[0035] In some embodiments of this application, the protective gas for plasma spraying includes CF4 and He, or CF4 and Ar. CF4 and He are preferred as the protective gas. Plasma induces ionization of CF4 / He, and the ionized He undergoes a reduction reaction with iron oxides or hydroxides on the surface of the centrifugal pump housing to remove the rust oxide layer formed in the air on the centrifugal pump surface. Furthermore, hydrophobic groups can be introduced onto the housing surface to improve its anti-wetting properties. Simultaneously, the radial convergence of the plasma jet is enhanced, resulting in a denser distribution of the high-temperature zone of the jet and promoting a uniform and dense distribution of the coating medium on the housing surface. In other embodiments of this application, the CF4 concentration is 10–15 vol%, and the He / Ar concentration is 2–3 vol%.

[0036] In some embodiments of this application, the parameters of the plasma spraying include: a plasma pulse ratio of 8:1 to 13:1, a duty cycle of 5 to 8%, and a current density of 10 A / dm³. 2The processing time is 10–15 min. The plasma power supply is 13.68 MHz radio frequency. The plasma vacuum is controlled at 800–1200 Pa, the plasma power is 50 kW, and the gas flow rate is 80–120 L / min.

[0037] In some embodiments of this application, the solutes in the cyclohexylsiloxane / ethyl titanate composite solution are cyclohexylsiloxane and ethyl titanate, the solvent is ethanol, and the concentration of the solute is 7-10 vol%. Cyclohexylsiloxane has strong heat aging resistance, and ethyl titanate, as a coupling agent, reacts chemically with hydroxyl groups or protons on the material surface through alkoxy groups, promoting the combination of the outer shell cast iron-plasma sprayed film-silane-related groups-organic, thereby improving the interfacial adhesion. In other embodiments of this application, the molar ratio of Si ions to Ti ions in the cyclohexylsiloxane / ethyl titanate composite solution is 5:1 to 35:1. Within this molar ratio range, the adhesion of the coating can be higher than 90 N / cm. 2 Preferably, the molar ratio of Si ions to Ti ions is 15:1 to 25:1. Within this molar ratio range, the adhesion of the coating can exceed 100 N / cm. 2 .

[0038] In some embodiments of this application, the immersion time is 20-30 seconds; the drying temperature is 110-140°C; the coating is driven to cure; and the drying time is 10-20 minutes.

[0039] In some embodiments of this application, the process further includes roughening the surface of the centrifugal pump housing after the impregnation modification in step 3, such as sandblasting. This can generate residual compressive stress on the surface, improve the adhesion between the coating and the housing, and increase its fatigue life.

[0040] In some embodiments of this application, during the electron beam remelting process, the electron beam action time is relatively short, the coating surface is rapidly heated and then rapidly cooled, the metal phase in the coating melts and then solidifies, the alloy phase of the plasma-sprayed film and the Ti ions in the impregnated modified film form a high-entropy alloy, effectively improving the density of the coating, the plasma-sprayed film and the impregnated modified film present an embedded bonding mode, the impregnated modified film can compensate for the defect positions of the plasma-sprayed film, so that the coating changes from the original layered mechanical bonding to metallurgical bonding.

[0041] In some other embodiments of this application, an electron beam with pre-set energy is deflected onto the coating of the centrifugal pump housing for a controlled time of 10–15 seconds. The electron beam frequency is 320 Hz, the field frequency is 32 Hz, the voltage is 30–40 V, the electron beam current is 0.9–1 A, and the power is 27–40 W.

[0042] In a second aspect of this application, a centrifugal pump housing prepared by the method of this application is also provided. This housing mainly comprises a plasma-sprayed film layer on the surface of the centrifugal pump housing, and a cyclohexylsiloxane / ethyl titanate composite solution impregnation-modified film layer on the plasma-sprayed film layer, which is then subjected to electron beam remelting. After a 600-hour salt spray test, no obvious corrosion spots were observed on its surface, achieving a corrosion resistance level of C4; simultaneously, its wettability was improved. Furthermore, Nyquist spectra and frequency-phase angle diagrams also show that the corrosion resistance of the centrifugal pump housing prepared by this application is significantly improved.

[0043] Based on the aforementioned superior technical effects, in a third aspect of this application, the application of the centrifugal pump housing in the manufacture of centrifugal pumps is provided.

[0044] In a fourth aspect of this application, a centrifugal pump is provided according to the field of application, which includes the centrifugal pump housing described in this application.

[0045] In the comparative experiments provided in this application, unless otherwise specified, all experimental conditions and materials remain consistent to ensure comparability. Furthermore, all materials used in this application are commercially available.

[0046] The following provides a further description of a surface-modified centrifugal pump housing, its preparation method, and its application.

[0047] Example 1:

[0048] (1) Plasma spraying (reduction modification) is performed on the surface of the centrifugal pump casing;

[0049] Before plasma spraying, the outer shell surface is sanded, then degreased and ultrasonically cleaned. The plasma source uses arc discharge technology to generate high-energy electrons and ions to coat the surface. A CF4 / He mixture is used as the plasma flame for protection, with a CF4 concentration of 12 vol% and a He concentration of 2.5 vol%. Plasma-induced ionization of CF4 / He occurs, and the ionized He reacts with iron oxides or hydroxides on the centrifugal pump surface to remove the rust oxide layer formed in the air. The plasma pulse ratio is 9:1, the duty cycle is 7%, and the current density is 10 A / dm³. 2 The processing time was 10 minutes. The plasma power supply was 13.68 MHz radio frequency. The plasma vacuum level was controlled at 1000 Pa. The plasma power was 50 kW, and the gas flow rate was set to 80 L / min. The plasma powder used was NiCrAlY alloy powder, with the mass percentages of each element being 65 wt% (Ni), 20 wt% (Cr), 14 wt% (Al), and 1 wt% (Y), and the average particle size of the powder was 75 nm.

[0050] (2) The centrifugal pump casing was modified by impregnation with a cyclohexylsiloxane / ethyl titanate composite solution;

[0051] In the cyclohexylsiloxane / ethyl titanate composite solution, the solute concentration is 10%, and the solvent is ethanol. The molar ratio of Si ions to Ti ions in the solute is 20:1. The centrifugal pump casing is immersed in the solution for 25 seconds.

[0052] The centrifugal pump casing after impregnation modification was dried for 10 minutes at a temperature of 140°C. After cleaning, the casing surface was roughened by sandblasting, which generated residual compressive stress, improved the adhesion between the coating and the casing, and increased its fatigue life.

[0053] (4) Electron beam remelting modification of the coating;

[0054] During the surface remelting process, firstly, the electron beam is applied to the heat-bearing target. After adjusting the required remelting parameters, the electron beam deflection function is activated. During surface remelting, the electron beam with the set energy is deflected onto the outer shell surface for a controlled time of 10 seconds. The electron beam frequency is 320Hz, the field frequency is 32Hz, the voltage is 30V, the electron beam current is 0.9A, and the power is 27W.

[0055] (5) Test results

[0056] Figure 1 This is an EDS surface scan of the Si and Ti element distribution of the modified film impregnated on the surface of the centrifugal pump shell before electron beam remelting. As can be seen from the figure, there are obvious Si and Ti elements on the shell surface, which are relatively uniformly covered on the shell surface.

[0057] Figure 2 As can be seen, the plasma-sprayed film before remelting has a loose structure, with the molten alloy powder mechanically stacked together and containing pores of varying sizes. After high-energy transient electron beam treatment, the surface of the powder-sprayed film melts, and the remelted metal forms columnar crystals of varying sizes along the thickness direction of the film. The surface of the remelted alloy powder-sprayed film changes from loose to extremely smooth and dense, with no defects or pores observed. The entire film changes from its original layered mechanical bonding to a metallurgical bonding. Due to the extremely short duration of the electron beam, the film surface rapidly heats up and then rapidly cools down, causing the metal phase in the film to melt and then solidify, resulting in recrystallization.

[0058] Figure 3The macroscopic salt spray corrosion morphology of the shell surface with and without coating after 600 hours is shown. It can be seen that the surface of the shell without coating shows obvious corrosion after 600 hours of salt spray test, while the surface of the shell with coating does not have obvious corrosion spots after 600 hours of salt spray test, and the corrosion resistance reaches C4 level.

[0059] Figure 4 The contact angle test results with and without coating are given. It can be seen that after the coating is applied, the contact angle of the shell surface becomes larger. The larger the hydrophobic angle, the stronger the coating's ability to isolate corrosive media and the better its corrosion resistance. This indicates that the coating effectively improves the anti-wetting properties of the centrifugal pump shell.

[0060] Figure 5 The Nyquist spectra of the surface with and without coating are given. It can be seen from the figure that after the coating is sprayed on the surface of the centrifugal pump, its capacitive arc radius gradually increases and becomes relatively stable, indicating that the composite coating has good corrosion resistance. Furthermore, the plasma-sprayed film and the impregnated modified film are well bonded, indicating that the coating can effectively improve the corrosion resistance of the centrifugal pump surface.

[0061] Figure 6 The graph shows the frequency-phase angle of the surface with and without coating. It can be seen from the graph that after the coating is applied, the impedance modulus of the shell surface in the low-frequency region increases, indicating that the corrosion resistance of the shell surface after plasma spraying and impregnation modification is significantly improved.

[0062] Example 2:

[0063] (1) Plasma spraying (reduction modification) is performed on the surface of the centrifugal pump casing;

[0064] Before plasma spraying, the outer casing surface is sanded, then degreased and ultrasonically cleaned. The plasma source uses arc discharge technology to generate high-energy electrons and ions, which are then deposited onto the surface. A CF4 / He mixture is used as the plasma flame for protection, with a CF4 concentration of 10 vol% and a He concentration of 3.0 vol%. Plasma-induced ionization of CF4 / He occurs, and the ionized He reacts with iron oxides or hydroxides on the centrifugal pump surface to remove the rust oxide layer formed in the air. The plasma pulse ratio is 13:1, the duty cycle is 5%, and the current density is 10 A / dm³. 2 The processing time was 15 minutes. The plasma power supply was 13.68 MHz radio frequency. The plasma vacuum was controlled at 1000 Pa. The plasma power was 50 kW, and the gas flow rate was set to 120 L / min. The plasma powder used was NiCrAlY alloy powder, with the mass percentages of each element being 70 wt% (Ni), 25 wt% (Cr), 4 wt% (Al), and 1 wt% (Y), and the average particle size of the powder was 75 nm.

[0065] (2) The centrifugal pump casing was modified by impregnation with a cyclohexylsiloxane / ethyl titanate composite solution;

[0066] In a cyclohexylsiloxane / ethyl titanate composite solution, the solute concentration is 10%, and the solvent is ethanol. The molar ratio of Si ions to Ti ions in the solute is 15:1. The silane hydrolysis pH is 4.0. The centrifugal pump casing is immersed in the solution for 30 seconds.

[0067] The centrifugal pump casing after impregnation modification was dried for 10 minutes at a temperature of 140°C. After cleaning, the casing surface was roughened by sandblasting, which generated residual compressive stress, improved the adhesion between the coating and the casing, and increased its fatigue life.

[0068] (4) Electron beam remelting modification of the coating;

[0069] During the surface remelting process, firstly, the electron beam is applied to the heat-bearing target. After adjusting the required remelting parameters, the electron beam deflection function is activated. During surface remelting, the electron beam with the set energy is deflected onto the outer shell surface for a controlled time of 10 seconds. The electron beam frequency is 320Hz, the field frequency is 32Hz, the voltage is 30V, the electron beam current is 0.9A, and the power is 27W.

[0070] (5) Test results

[0071] The results are basically consistent with those of Example 1. The EDS surface scan of the modified film impregnated on the surface of the centrifugal pump shell before electron beam remelting shows that there are obvious Si and Ti elements on the shell surface, which are relatively uniformly covered on the shell surface.

[0072] SEM images of the centrifugal pump casing surface before and after electron beam remelting show that the coating structure before remelting is loose, with molten alloy powder mechanically stacked together and containing pores of varying sizes. After high-energy transient electron beam treatment, the surface of the powder film melted, and the remelted metal formed columnar crystals of varying sizes along the coating thickness direction. The surface of the remelted alloy powder film changed from loose to extremely smooth and dense, with no defects or pores observed. The entire coating changed from the original layered mechanical bonding to a metallurgical bonding.

[0073] The microstructure of the interface between the plasma-sprayed film and the impregnated modified film before electron beam remelting shows that the plasma-sprayed film and the impregnated modified film are embedded in each other. The impregnated modified film almost completely blocks the defect sites of the plasma-sprayed film, and the two are well bonded.

[0074] The results of the 600-hour salt spray corrosion test showed that the surface of the uncoated shell showed obvious corrosion after 600 hours of salt spray test, while the surface of the shell with coating did not show obvious corrosion spots after 600 hours of salt spray test, and the corrosion resistance reached the C4 level.

[0075] The contact angle test results showed that the contact angle of the shell surface increased after the coating was applied; at the same time, the Nyquist spectrum and frequency-phase angle diagram both showed that the coating can effectively improve the corrosion resistance of the centrifugal pump shell surface.

[0076] Example 3:

[0077] (1) Plasma spraying (reduction modification) is performed on the surface of the centrifugal pump casing;

[0078] Before plasma spraying, the outer casing surface is sanded, then degreased and ultrasonically cleaned. The plasma source uses arc discharge technology to generate high-energy electrons and ions to coat the surface. A CF4 / He mixture is used as the plasma flame for protection, with a CF4 concentration of 15 vol% and a He concentration of 2.0 vol%. Plasma-induced ionization of CF4 / He occurs, and the ionized He reacts with iron oxides or hydroxides on the centrifugal pump surface to remove the rust oxide layer formed in the air. The plasma pulse ratio is 8:1, the duty cycle is 8%, and the current density is 10 A / dm³. 2 The processing time was 12 minutes. The plasma power supply was 13.68 MHz radio frequency. The plasma vacuum level was controlled at 1000 Pa. The plasma power was 50 kW, and the gas flow rate was set to 100 L / min. The plasma powder used was NiCrAlY alloy powder, with the mass percentages of each element being 68 wt% (Ni), 22 wt% (Cr), 9 wt% (Al), and 1 wt% (Y), and the average particle size of the powder was 75 nm.

[0079] (2) The centrifugal pump casing was modified by impregnation with a cyclohexylsiloxane / ethyl titanate composite solution;

[0080] In a cyclohexylsiloxane / ethyl titanate composite solution, the solute concentration is 10%, and the solvent is ethanol. The molar ratio of Si ions to Ti ions in the solute is 25:1. The silane hydrolysis pH is 5.0. The centrifugal pump casing is immersed in the solution for 20 seconds.

[0081] The centrifugal pump casing after impregnation modification was dried for 10 minutes at a temperature of 140°C. After cleaning, the casing surface was roughened by sandblasting, which generated residual compressive stress, improved the adhesion between the coating and the casing, and increased its fatigue life.

[0082] (4) Electron beam remelting modification of the coating;

[0083] During the surface remelting process, firstly, the electron beam is applied to the heat-bearing target. After adjusting the required remelting parameters, the electron beam deflection function is activated. During surface remelting, the electron beam with the set energy is deflected onto the outer shell surface for a controlled time of 10 seconds. The electron beam frequency is 320Hz, the field frequency is 32Hz, the voltage is 30V, the electron beam current is 0.9A, and the power is 27W.

[0084] (5) Test results

[0085] The results are basically consistent with those of Example 1. The EDS surface scan of the coating on the surface of the centrifugal pump housing shows that there are obvious Si and Ti elements on the surface of the housing, and they are relatively uniformly covered on the surface of the housing.

[0086] SEM images of the centrifugal pump casing surface before and after electron beam remelting show that the coating structure before remelting is loose, with molten alloy powder mechanically stacked together and containing pores of varying sizes. After high-energy transient electron beam treatment, the surface of the powder coating melts, and the remelted metal forms columnar crystals of varying sizes along the coating thickness direction. The surface of the remelted alloy powder coating changes from loose to extremely smooth and dense, with no defects or pores observed. The coating changes from a layered mechanical bond to a metallurgical bond.

[0087] The final coating interface microstructure shows that the plasma sprayed coating and the impregnated film layer are embedded in each other. The impregnated coating layer almost completely blocks the defect positions of the plasma sprayed film layer, and the two are well bonded.

[0088] The results of the 600-hour salt spray corrosion test showed that the surface of the uncoated shell showed obvious corrosion after 600 hours of salt spray test, while the surface of the shell with coating did not show obvious corrosion spots after 600 hours of salt spray test, and the corrosion resistance reached the C4 level.

[0089] The contact angle test results showed that the contact angle of the shell surface increased after the coating was applied; at the same time, the Nyquist spectrum and frequency-phase angle diagram both showed that the coating can effectively improve the corrosion resistance of the centrifugal pump shell surface.

[0090] Experimental example:

[0091] (1) Performance comparison of plasma-sprayed films prepared by plasma spraying of different alloy powders

[0092] Based on Example 1, plasma-sprayed films were prepared using different alloy powders, and the adhesion and the time to first oxidation and rust (oxidation spot area greater than 4 cm² under 25°C and 40% air humidity) were tested. 2The relevant performance results are shown in Table 1.

[0093] Table 1

[0094]

[0095] Table 1 presents the performance comparison results of films prepared by different plasma spraying techniques. The results show that, compared with FeCrAl, the coatings prepared by plasma spraying of NiCrAl powder have better oxidation resistance and adhesion.

[0096] Based on the experimental results in Table 1, Y element powder was added for plasma spraying, and the effect of different Y element contents on the antioxidant properties of the coating was tested. The results are shown in Table 2 below;

[0097] Table 2

[0098]

[0099] Table 2 presents the experimental results of NiCrAlY alloys with different Y element contents tested under 25℃ and 40% air humidity conditions. The results show that alloy powders prepared by adding Y element to Ni, Cr, and Al elements can improve the adhesion and oxidation resistance of the film after plasma spraying. When the Y element content is increased to 1%–4%, the difference in coating adhesion and oxidation resistance is small. Therefore, considering economic factors, the Y element addition range is 1–2 wt%, more preferably 2%, but this does not limit the Y element content from being increased to more than 4%.

[0100] (2) Comparison of adhesion of modified films (before electron beam remelting) impregnated in cyclohexylsiloxane / ethyl titanate composite solution with different Si / Ti ion molar ratios

[0101] Based on the process in Example 1, different Si / Ti ion molar ratios in the cyclohexylsiloxane / tetratitanate solution were adjusted, and the adhesion of the impregnated modified film layer formed under different Si / Ti ion molar ratios was tested, as shown in Table 3 below;

[0102] Table 3

[0103] Si / Ti molar ratio <![CDATA[Adhesion force N / cm 2 > 5:1 91 10:1 94 15:1 101 20:1 103 25:1 102 30:1 97 35:1 97 ∞ (without ethyl titanate) 80

[0104] As shown in Table 3, when ethyl titanate is added, the adhesion of the impregnated modified film gradually increases as the Si / Ti ion molar ratio increases from 5:1 to 25:1. However, when this molar ratio increases to 30:1, the adhesion of the impregnated modified film decreases. Therefore, a Si / Ti ion molar ratio of 15–25 is optimal. Without ethyl titanate, the adhesion of the impregnated modified film is only 80 N / cm. 2 .

[0105] (3) Comparison of adhesion of impregnation-modified films (before electron beam remelting) under different coupling agents and cyclohexylsiloxane composite conditions

[0106] Based on the process in Example 1, different coupling agents (ethyl titanate, aluminate and aluminum-titanium composite coupling agent) and cyclohexylsiloxane were used, and the corresponding ion molar ratios were set to 15:1, 20:1 and 25:1. The adhesion of the impregnated modified film layer formed under these conditions is shown in Table 4 below.

[0107] Table 4

[0108]

[0109]

[0110] The results in Table 4 show that when ethyl titanate was added to the solution as a coupling agent, the prepared impregnated modified film exhibited the best bonding strength, while the other two coupling agents were less effective.

[0111] (4) The effect of different process combinations on coating performance

[0112] Based on the process in Example 1, different methods were combined from plasma spraying, impregnation modification, and electron beam remelting to prepare coatings. Adhesion, salt spray resistance time, and contact angle between the coating and water were tested, as shown in Table 5 below.

[0113] Table 5

[0114]

[0115] Table 5 shows that electron beam remelting treatment (i.e., Example 1) of the plasma-sprayed and impregnated modified surface can cause surface melting and recrystallization, reducing porosity and defects, and significantly improving the coating's adhesion, salt spray corrosion resistance, and water contact angle. The other three preparation methods using only two processes all performed worse than Example 1, which used all three processes simultaneously, in all three performance indicators.

[0116] (5) The influence of the composition of the protective gas in plasma spraying on the plasma sprayed film.

[0117] Table 6

[0118]

[0119]

[0120] Table 6 presents the experimental results of the influence of plasma gas composition on the plasma-sprayed coating. Since CF4 can generate highly reactive fluorine plasma during ionization, it can better coat the alloy powder onto the centrifugal pump casing surface, improving the coverage of the plasma-sprayed film. Furthermore, it can clean organic contaminants from the surface, improving the material surface quality and adhesion. Compared to CF4, SF6 and CH4 are chemically inert, and sulfur poses a potential environmental threat, while CH4 is highly flammable and poses a safety hazard. He can increase the gas phase conductivity, improving the deposition efficiency of alloy powder on the centrifugal pump casing material surface. Based on the test results of the effect of plasma gas composition on coating performance and deposition efficiency, CF4+He is selected as the optimal plasma protective gas. However, if only adhesion is considered, without considering deposition efficiency, CF4+Ar can also be considered as an alternative.

[0121] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a surface-modified centrifugal pump housing, characterized in that, include: Step 1: Clean the surface of the centrifugal pump casing; Step 2: Plasma spraying is performed on the surface of the centrifugal pump housing using NiCrAlY alloy powder; Step 3: After plasma spraying, the centrifugal pump housing is impregnated and modified in a composite solution of cyclohexylsiloxane and tetraethyl titanate, and then dried; the molar ratio of Si ions to Ti ions in the composite solution of cyclohexylsiloxane and tetraethyl titanate is 5:1 to 35:

1. Step 4: Perform electron beam remelting modification on the impregnated centrifugal pump housing to obtain a surface-modified centrifugal pump housing.

2. The preparation method according to claim 1, characterized in that, In the NiCrAlY alloy powder, the mass percentage of each element is 65-70% for Ni, 20-25% for Cr, 5-15% for Al, and Y > 0, totaling 100%.

3. The preparation method according to claim 2, characterized in that, The NiCrAlY alloy powder contains the following mass percentages: Ni 65-70%, Cr 20-25%, Al 5-15%, Y ≥ 1%, totaling 100%.

4. The preparation method according to claim 3, characterized in that, In the NiCrAlY alloy powder, the mass percentage of each element is 65-70% for Ni, 20-25% for Cr, 5-15% for Al, and 1-2% for Y, totaling 100%.

5. The preparation method according to claim 1, characterized in that, The protective gas used in the plasma spraying includes CF4 and He, or CF4 and Ar.

6. The preparation method according to any one of claims 1-5, characterized in that, It also includes roughening the surface of the centrifugal pump housing after impregnation modification in step 3.

7. The centrifugal pump housing prepared by the preparation method according to any one of claims 1-6.

8. The use of the centrifugal pump housing according to claim 7 in the manufacture of a centrifugal pump.

9. A centrifugal pump, characterized in that, Includes the centrifugal pump housing as described in claim 7.

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