Composite coating for dry vacuum pump and preparation method thereof

Abstract

The invention provides a composite coating for a dry vacuum pump and a preparation method of the composite coating, and belongs to the technical field of vacuum pumps. The composite coating comprises a phosphating layer, a chemical nickel-plating layer and a spraying layer which are sequentially arranged on the surface of the stator and / or the rotor of the dry vacuum pump in a stacked mode. Wherein the phosphating treatment layer comprises 15%-25% of zinc dihydrogen phosphate, 5%-10% of zinc nitrate, 2%-5% of zinc oxide, 0.5%-2% of an accelerant and the balance of deionized water. According to the composite coating disclosed by the invention, the corrosion resistance, the adhesion resistance of a process object and the bonding strength of the coating can be synergistically improved, so that the dry vacuum pump can adapt to complex dry etching working condition requirements, the service life of the dry vacuum pump is prolonged, and the maintenance cost of equipment is reduced.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of vacuum pumps, and particularly relates to a composite coating for a dry vacuum pump and a preparation method thereof. BACKGROUND

[0002] Dry vacuum pumps are widely used in industrial production, especially in the fields of semiconductors, panels, photovoltaics, etc. They often need to handle corrosive gases and at the same time handle a large amount of process materials generated in the process chamber and inside the vacuum pump due to chemical reactions or temperature phase changes. Under these working conditions, the stator and rotor of the vacuum pump are not only easily corroded, but also the stator and rotor gap is easily filled with process materials, causing pump jamming, resulting in reduced service life and performance of the equipment, and increasing the risk of equipment maintenance costs and production interruptions.

[0003] Currently, to solve the problems of corrosion of the stator and rotor and pump jamming by process materials, the commonly used methods include using corrosion-resistant materials to manufacture the stator and rotor, such as high-nickel materials, etc., but these materials are high in cost and difficult to process; or coating a corrosion-resistant coating on the surface of the stator and rotor. However, the above existing coating technologies all have many deficiencies, for example, a single coating cannot simultaneously meet the working condition requirements of corrosion resistance and process material adhesion resistance; some coatings have limited corrosion resistance and cannot meet the requirements of complex working conditions; some coatings have strong corrosion resistance, but have weak adhesion to the substrate and are prone to falling off and failure; and the performance of some coatings rapidly decreases under high temperature and high-speed friction conditions. Therefore, in view of the above problems, it is necessary to develop a coating structure that has excellent corrosion resistance, dust adhesion resistance, high adhesion strength and can adapt to complex working conditions, which is of great significance to improve the service life and performance of the stator and rotor of the dry vacuum pump. SUMMARY

[0004] The present disclosure aims to at least solve one of the technical problems existing in the prior art, and provides a composite coating for a dry vacuum pump and a preparation method thereof.

[0005] In one aspect of the present disclosure, a composite coating for a dry vacuum pump is provided, which comprises a phosphating treatment layer, a chemical nickel plating layer and a spray coating layer arranged in sequence on the surface of the stator and / or rotor of the dry vacuum pump; wherein, The phosphating treatment layer comprises 15-25% zinc dihydrogen phosphate, 5-10% zinc nitrate, 2-5% zinc oxide, 0.5-2% accelerant, and the balance deionized water.

[0006] Optionally, the chemical nickel plating layer comprises 25-30% nickel sulfate, 25-30% sodium hypophosphite, 13-28% sodium citrate, 10-20% sodium acetate, 0.01-0.04% potassium iodate, and the balance deionized water. The spraying layer is a PFA coating or a PTFE coating.

[0007] Optionally, the thickness of the phosphating layer is 6-8 μm. The thickness of the electroless nickel plating layer is 18-22 μm. The thickness of the spraying layer is 18-22 μm.

[0008] Optionally, the composite coating further comprises a sealing layer between the electroless nickel plating layer and the spraying layer.

[0009] Optionally, the thickness of the sealing layer is 3-5 μm. The sealing layer comprises 5%-15% of nano ceramic particles, 20%-30% of epoxy resin, 5%-10% of curing agent, 10%-20% of diluent, and the balance of deionized water.

[0010] In another aspect of the present disclosure, a preparation method of a composite coating for a dry vacuum pump is provided, and the preparation method comprises: The stator and / or rotor of the dry vacuum pump is subjected to shot blasting, degreasing, first water washing, acid pickling, and second water washing pretreatment; The pretreated stator and / or rotor is immersed in a phosphating treatment solution for phosphating treatment to form a phosphating layer; The phosphating treated stator and / or rotor is cleaned and then immersed in an electroless nickel plating solution for nickel plating treatment to form an electroless nickel plating layer; Fluoropolymer coating is uniformly sprayed onto the surface of the electroless nickel plating layer for sintering and drying treatment to form a spraying layer.

[0011] Optionally, the phosphating treatment solution comprises 15%-25% of zinc dihydrogen phosphate, 5%-10% of zinc nitrate, 2%-5% of zinc oxide, 0.5%-2% of accelerant, and the balance of deionized water. The phosphating treatment is performed at a temperature of 40-60°C for 10-20 min, and the phosphating layer formed has a thickness of 6-8 μm.

[0012] Optionally, the electroless nickel plating solution comprises 25%-30% of nickel sulfate, 25%-30% of sodium hypophosphite, 13%-28% of sodium citrate, 10%-20% of sodium acetate, 0.01%-0.04% of potassium iodate, and the balance of deionized water. The nickel plating treatment is performed at a temperature of 85-90°C, a pH value of 4.5-5.2, and for 60-80 min, and the electroless nickel plating layer formed has a thickness of 18-22 μm.

[0013] Optionally, the fluoropolymer coating is a PFA coating or a PTFE coating. The sintering and drying treatment comprises: Preheat at 100~120℃ for 10~20min, then sinter at 380~390℃ for 20~30min to form a coating thickness of 18~22μm.

[0014] Optionally, after forming the electroless nickel plating layer, the preparation method further includes: immersing the nickel-plated stator and / or rotor in a sealing agent after drying, allowing it to stand at room temperature, and then curing it to form a sealing layer; wherein, The sealing agent comprises: 5%~15% nano-ceramic particles, 20%~30% epoxy resin, 5%~10% curing agent, 10%~20% diluent, and the balance being deionized water; The dip coating process takes 2-5 minutes, the room temperature standing time is 10-15 minutes, the curing temperature is 100-120℃, the time is 25-35 minutes, and the thickness of the resulting sealing layer is 3-5 μm.

[0015] This disclosure discloses a composite coating for dry vacuum pumps and its preparation method. The composite coating comprises a phosphating layer, a chemically plated nickel layer, and a sprayed layer sequentially stacked on the surface of the stator and / or rotor of the dry vacuum pump. The composite coating of this disclosure can achieve a synergistic improvement in corrosion resistance, process material adhesion resistance, and coating bonding strength, enabling the dry vacuum pump to adapt to complex dry etching conditions, extending its service life, and reducing equipment maintenance costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the composite coating according to a specific embodiment of the present disclosure; Figure 2 This is a flowchart illustrating the composite coating preparation method according to a specific embodiment of this disclosure. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this disclosure and represent a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0018] like Figure 1 As shown, the composite coating of this embodiment includes a phosphating layer 210, a chemical nickel plating layer 220, and a spray coating layer 240 sequentially stacked on the surface of the dry vacuum pump stator and / or rotor 200.

[0019] In the embodiment, the stator and the rotor are the substrates to be treated. By forming the composite coating on the surfaces of the stator and the rotor, the composite coating between the coatings cooperates to not only optimize the substrates but also play a certain anticorrosion effect to resist the corrosion of corrosive gas. Meanwhile, the stator and the rotor have excellent non-stick property to prevent the process objects from adhering, thereby achieving multiple protection effects of the stator and the rotor of the dry vacuum pump.

[0020] It should be noted that the sprayed coating of the embodiment can be directly formed on the electroless nickel plating layer. In addition, a sealing layer can be arranged on the electroless nickel plating layer, and the sprayed coating is formed on the sealing layer. That is, the sealing layer can be arranged between the electroless nickel plating layer and the sprayed coating. In this way, the micropores and defects on the surface of the electroless nickel plating layer can be effectively plugged, the penetration of corrosive medium is prevented, and the bonding force between the electroless nickel plating layer and the sprayed coating is improved.

[0021] It should be further noted that the composite coating of the embodiment can be coated on the surface of the rotor or the surface of the stator. Of course, the composite coating can be coated on the surfaces of the stator and the rotor, and the composite coating can be arranged according to actual needs.

[0022] It should be understood that the stator is a fixed substrate of the dry vacuum pump, and the inner surface of the stator has a sealing chamber matched with the outer surface of the rotor. The rotor is a high-speed rotating part, and the outer surface of the rotor directly contacts with gas and process objects. Therefore, when the composite coating is coated on the rotor, the composite coating should be coated on the outer surface of the rotor. When the composite coating is coated on the stator, the composite coating should be coated on the inner surface of the stator. Therefore, the inner surface of the stator is referred to as the surface of the stator, and the outer surface of the rotor is referred to as the surface of the rotor. For example, as shown in Figure 1 the phosphating treatment layer 210, the electroless nickel plating layer 220, the sealing layer 230, and the sprayed coating 240 are sequentially arranged on the inner surface of the stator 200 to form the composite coating on the surface of the stator.

[0023] For example, as shown in Figure 1 the phosphating treatment layer 210, the electroless nickel plating layer 220, the sealing layer 230, and the sprayed coating 240 are sequentially arranged on the outer surface of the rotor 200 to form the composite coating on the surface of the rotor.

[0024] It should be noted that the phosphating treatment layer of the embodiment can be a zinc-based phosphating layer or a manganese-based phosphating layer, and the thickness is 6-8 μm. The phosphating treatment layer fills the possible micropores on the surfaces of the stator and the rotor of the dry vacuum pump, reduces the porosity of the subsequent electroless nickel plating layer, optimizes the substrate, provides a good adhesion basis for the subsequent coating, improves the overall corrosion resistance of the composite coating, and improves the bonding strength.

[0025] In some preferred embodiments, the phosphating treatment layer comprises 15-25% of zinc dihydrogen phosphate, 5-10% of zinc nitrate, 2-5% of zinc oxide, 0.5-2% of accelerant, and the balance of deionized water. That is, the phosphating treatment layer is formed by phosphating treatment of the above components, and the specific process of the phosphating treatment is described below.

[0026] Further, the electroless nickel plating layer of the embodiment can be a medium-phosphorus electroless nickel plating layer or a high-phosphorus electroless nickel plating layer, and has a thickness of 18-22 μm, preferably 20 μm. The main function of the electroless nickel plating layer is to act as a corrosion barrier, and to resist corrosion of most corrosive gases due to its excellent corrosion resistance and wear resistance, while having a certain hardness to reduce mechanical wear and provide a solid foundation for the subsequent sprayed coating.

[0027] In some preferred embodiments, the electroless nickel plating layer comprises 25-30% of nickel sulfate, 25-30% of sodium hypophosphite, 13-28% of sodium citrate, 10-20% of sodium acetate, 0.01-0.04% of potassium iodate, and the balance of deionized water. That is, the electroless nickel plating layer is formed by nickel plating treatment of the above components, and the specific process of the nickel plating treatment is described below.

[0028] Further, the sealing layer of the embodiment can be a nano-ceramic sealing layer, and has a thickness of 3-5 μm. The function of the sealing layer is to seal the micropores and defects on the surface of the electroless nickel plating layer, prevent the penetration of corrosive media, and improve the adhesion to the sprayed coating.

[0029] In some preferred embodiments, the sealing layer comprises 5-15% of nano-ceramic particles, 20-30% of epoxy resin, 5-10% of curing agent, 10-20% of diluent, and the balance of deionized water. That is, the sealing layer is formed by dip coating treatment of the above components on the substrate, and the specific process of the dip coating treatment is described below.

[0030] Further, the sprayed coating of the embodiment can be a PFA coating or a PTFE coating, and has a thickness of 18-22 μm, preferably 20 μm. The PFA coating or the PTFE coating has a very low friction coefficient, can prevent the adhesion of process materials, reduce the adhesion of process materials on the rotor and stator, and reduce the risk of wear and scratches. In addition, the coating has good thermal stability and chemical corrosion resistance, can further improve the corrosion resistance of the surface of the rotor and stator, and improve the stability and service life of the equipment.

[0031] In some preferred embodiments, the PFA coating is obtained by spraying PFA paint, and in other preferred embodiments, the PTFE coating is obtained by spraying PTFE paint, and the specific process is described below.

[0032] The composite coating of the present disclosure realizes the synergistic improvement of corrosion resistance, anti-adhesion, bonding strength and dynamic stability on the inner surface of the stator and the outer surface of the rotor through the multi-layer step structure of the substrate optimization, corrosion prevention, defect plugging and functional outer layer, solves the problems of easy corrosion, easy pump jamming and coating failure of the traditional dry vacuum pump stator and rotor, and significantly prolongs the service life of the equipment.

[0033] As shown in Figure 2 Another aspect of the present disclosure provides a composite coating preparation method S100 for a dry vacuum pump, specifically comprising the following steps: S110, shot blasting, degreasing, first water washing, pickling and second water washing pretreatment are performed on the stator and / or rotor of the dry vacuum pump.

[0034] In step S110, the stator or rotor of the dry vacuum pump should be finished to the designed size first, and then pretreated. In the pretreatment process, 70-100 mesh glass beads can be preferably used for shot blasting treatment of the stator or rotor of the dry vacuum pump for 10-15 min; then, an alkaline degreasing agent is used to degrease the above-mentioned substrate at 50-70°C for 15-25 min to remove the oil stains on the surface; then, deionized water is used to wash the above-mentioned substrate for the first time for 3-5 min; then, a hydrochloric acid solution with a mass fraction of 10%-15% is used to pickle the substrate at room temperature for 5-10 min to remove the surface scale and rust, and then deionized water is further used to wash the above-mentioned substrate for the second time for 3-5 min.

[0035] It should be noted that the material of the stator and rotor of the dry vacuum pump in the present embodiment is nodular cast iron, and the above-mentioned stator and rotor represent the substrate object to be treated. The composite coating can be coated on the stator substrate alone, on the rotor substrate alone, or on both the stator and rotor substrates.

[0036] S120, the pretreated stator and / or rotor are immersed in a phosphating treatment solution for phosphating treatment to form a phosphating treatment layer.

[0037] In step S120, the phosphating treatment solution comprises: 15%-25% of zinc dihydrogen phosphate; 5%-10% of zinc nitrate; 2%-5% of zinc oxide; 0.5%-2% of a promoter, which can be preferably sodium nitrite; and the balance of deionized water.

[0038] In some preferred embodiments, the content of zinc dihydrogen phosphate can be preferably 15%, 20%, 25%, etc., the content of zinc nitrate can be preferably 5%, 10%, 15%, etc., the content of zinc oxide can be preferably 2%, 3%, 4%, 5%, etc., and the content of the promoter can be preferably 0.5%, 1%, 1.5%, 2%, etc.

[0039] In step S120, the temperature of the phosphating treatment is 40-60°C, the treatment time is 10-20 min, and the thickness of the phosphating treatment layer formed is 6-8 μm.

[0040] In some preferred embodiments, the temperature of the phosphating treatment can preferably be 40°C, 50°C, 60°C, etc., the treatment time can preferably be 10 min, 15 min, 20 min, etc., and the thickness of the phosphating treatment layer formed can preferably be 6 μm, 7 μm, 8 μm, etc.

[0041] The phosphating treatment solution of the present embodiment generates compact phosphate crystals through a chemical reaction, forms a phosphating treatment layer, can fill the micropores on the surface of the stator and / or rotor, provides a substrate with moderate roughness for subsequent coating, and reduces the porosity of the nickel plating layer. At the same time, the phosphate reacts with the iron element of the substrate to generate a Fe-Zn / Mn phosphate transition layer, forms a chemical bond, and effectively increases the bonding force.

[0042] In step S130, the phosphated stator and / or rotor are cleaned and then immersed in a chemical nickel plating solution for nickel plating treatment to form a chemical nickel plating layer.

[0043] It should be noted that the phosphated stator and rotor should be ultrasonically cleaned with deionized water for 10-15 min before nickel plating to remove residual phosphating solution, and then subjected to nickel plating treatment.

[0044] In step S130, the chemical nickel plating solution comprises: 25%-30% nickel sulfate, 25%-30% sodium hypophosphite, 13%-28% sodium citrate, 10%-20% sodium acetate, 0.01%-0.04% potassium iodate, and the balance deionized water.

[0045] In some preferred embodiments, the content of nickel sulfate can preferably be 25%, 26%, 27%, 28%, 29%, 30%, etc., the content of sodium hypophosphite can preferably be 25%, 26%, 27%, 28%, 29%, 30%, etc., the content of sodium citrate can preferably be 13%, 16%, 20%, 24%, 28%, etc., the content of sodium acetate can preferably be 10%, 12%, 14%, 16%, 18%, 20%, etc., and the content of potassium iodate can preferably be 0.01%, 0.02%, 0.03%, 0.04%, etc.

[0046] In some other preferred embodiments, the concentration of nickel sulfate is preferably 420-480 g / L, the concentration of sodium hypophosphite is preferably 480-525 g / L, the concentration of sodium citrate is preferably 210-250 g / L, the concentration of sodium acetate is preferably 105-150 g / L, and the concentration of potassium iodate is preferably 0.21-0.25 g / L.

[0047] In step S130, the temperature of the nickel plating treatment is 85-90℃, the pH value is 4.5-5.2, the time is 60-80min, and the thickness of the electroless nickel layer formed is 18-22μm.

[0048] In some preferred embodiments, the temperature of the nickel plating treatment can be preferably 85℃, 87℃, 90℃, etc., the time can be preferably 60min, 70min, 80min, etc., and the thickness of the electroless nickel layer formed can be preferably 18μm, 20μm, 22μm, etc.

[0049] The electroless nickel layer of the present embodiment mainly plays a role of corrosion protection, and after being combined with the phosphating treatment layer, a dense protective layer is formed.

[0050] It should be noted that in the composite coating preparation method of the present embodiment, the spray layer can be directly formed on the electroless nickel layer, or the spray layer can be further formed on the sealing layer formed on the electroless nickel layer. Hereinafter, the sealing layer is formed first, and then the spray layer is formed on the sealing layer.

[0051] In step S140, after the nickel plating treatment, the stator and / or rotor is dried and then immersed in a nano-ceramic sealing agent for dip coating treatment, and after standing at room temperature, a curing treatment is performed to form a sealing layer.

[0052] It should be noted that after the nickel plating, the stator or rotor substrate is dried in an oven at 80-100℃ for 15-20min, effectively removing the residual moisture on the surface of the electroless nickel layer, avoiding the formation of bubbles or defects in the subsequent coating (such as the sealing layer) preparation, ensuring the tight bonding between the coatings, and then the dip coating treatment is performed.

[0053] In step S140, the nano-ceramic sealing agent comprises: 5%-15% of nano-ceramic particles; 20%-30% of epoxy resin; 5%-10% of curing agent; 10%-20% of diluent; and the balance of deionized water.

[0054] In some preferred embodiments, the content of nano-ceramic particles can be preferably 5%, 10%, 15%, etc., the content of epoxy resin can be preferably 20%, 25%, 30%, etc., the content of curing agent can be preferably 5%, 7%, 10%, etc., and the content of diluent can be preferably 10%, 15%, 20%, etc.

[0055] In step S140, the time of the dip coating treatment is 2-5min, the time of standing at room temperature is 10-15min, the temperature of the curing treatment is 100-120℃, the time is 25-35min, and the thickness of the sealing layer formed is 3-5μm.

[0056] In some preferred embodiments, the time for the dip coating process can be preferably 2 min, 3 min, 5 min, etc., the time for the room temperature standing can be preferably 10 min, 12 min, 15 min, etc., and the thickness of the formed sealing layer can be preferably 3 μm, 4 μm, 5 μm, etc.

[0057] The present embodiment can block the micro-defects of the nickel plating layer, enhance the adhesion with the subsequent sprayed layer, and block the penetration of corrosive medium by further forming a sealing layer on the electroless nickel plating layer.

[0058] In S150, the fluoropolymer coating is uniformly sprayed onto the surface of the sealing layer, and a sintering and drying treatment is performed to form a sprayed layer.

[0059] In S150, the fluoropolymer coating is PFA coating or PTFE coating, and the formed sprayed layer is PFA coating or PTFE coating.

[0060] In S150, the sintering and drying treatment includes preheating at 100-120℃ for 10-20 min, and then sintering at 380-390℃ for 20-30 min, and the thickness of the formed sprayed layer is 18-22 μm.

[0061] In some preferred embodiments, the preheating temperature can be preferably 100℃, 110℃, 120℃, etc., the preheating time can be preferably 10 min, 15 min, 20 min, etc., the temperature after the temperature rising can be preferably 380℃, 385℃, 390℃, etc., and the thickness of the formed sprayed layer can be preferably 18 μm, 20 μm, 22 μm, etc.

[0062] The sprayed layer of the present embodiment serves as the final protective layer, reduces the risk of pump jamming caused by dust accumulation, and prolongs the service life of the overall coating layer in cooperation with the sealing layer.

[0063] It should be understood that in other embodiments in which the sprayed layer is directly formed on the electroless nickel plating layer, the fluoropolymer coating should be uniformly sprayed onto the surface of the electroless nickel plating layer, and then a sintering and drying treatment is performed to form the sprayed layer, and the sintering and drying treatment process is the same as described above.

[0064] The present disclosure coats a plurality of composite coating layers on the surface of the stator and rotor base, and the synergistic effect of the plurality of coating layers achieves multiple protection effects, the thickness of each coating layer is reasonable, the performance is complementary, and the service life of the dry vacuum pump is significantly improved. Meanwhile, the preparation process parameters provided by the present disclosure are clear, easy to operate, high in stability, and easy to be industrialized, promoted and applied.

[0065] The composite coating layer for the dry vacuum pump and the preparation method thereof will be further described below with reference to specific embodiments: Embodiment 1 In combination with Figure 1 and Figure 2As shown, the preparation method of the composite coating in this example includes the following steps: S1, pretreatment of the stator and rotor base: the stator and rotor base 200 are finished to the designed size, and then strictly surface pretreated, including: Shot peening: the base is shot peened with 80 mesh glass beads for 12 min; Degreasing treatment: the base is degreased at a temperature of 60°C for 20 min with an alkaline degreasing agent to remove surface oil; First water washing treatment: the base is washed with deionized water for 4 min; Pickling treatment: the base is pickled with a 13% hydrochloric acid solution at room temperature for 7 min to remove surface oxide scale and rust; Second water washing treatment: the base is washed with deionized water for 4 min.

[0066] S2, preparation of the phosphating treatment layer: the pretreated stator and rotor are immersed in a phosphating treatment liquid, treated at 50°C for 15 min to form a 7 μm thick phosphating treatment layer 210.

[0067] The phosphating treatment liquid includes: 20% zinc dihydrogen phosphate, 7% zinc nitrate, 3% zinc oxide, 1% accelerator, and the rest is deionized water.

[0068] S3, preparation of the chemical nickel plating layer: the phosphated stator and rotor base are ultrasonically cleaned with deionized water for 12 min to remove residual phosphating liquid, and then the stator and rotor are immersed in a chemical nickel plating liquid, treated at 87°C and pH=5 for 70 min to form a 20 μm thick chemical nickel plating layer 220.

[0069] The chemical nickel plating liquid includes: 27% nickel sulfate, 27% sodium hypophosphite, 20% sodium citrate, 15% sodium acetate, 0.02% potassium iodate, and the rest is deionized water.

[0070] S4, preparation of the sealing layer: the nickel plated stator and rotor are dried in an oven at 90°C for 17 min, and a nano ceramic type sealing agent is coated by dipping, wherein the dipping time is 4 min, and after the dipping is completed, the base is placed at room temperature for 12 min, and then the base is cured at 110°C for 30 min to form a 4 μm thick sealing layer 230.

[0071] The sealing agent includes: 10% nano ceramic particles, 25% epoxy resin, 7% curing agent, 15% diluent, and the rest is deionized water.

[0072] S5, spray coating preparation: PFA coating is uniformly sprayed on the surface of the sealing layer 230 by using a spray gun, and then the substrate is preheated at 110°C for 15 min, and then heated to 385°C for sintering for 25 min, to form a 20 μm thick spray coating 240.

[0073] As shown in FIG. 1, the composite coating formed on the surface of the stator-rotor substrate 200 in the present embodiment includes a phosphating treatment layer 210, a chemical nickel plating layer 220, a sealing layer 230, and a spray coating 240 arranged in sequence. Figure 2

[0074] In the composite coating, the thickness of the phosphating treatment layer is 7 μm, the thickness of the chemical nickel plating layer is 20 μm, the thickness of the sealing layer is 4 μm, and the thickness of the spray coating is 20 μm.

[0075] The composite-coated dry vacuum pump prepared in the above embodiment 1 is subjected to performance testing, and the results show that the corrosion resistance (neutral salt spray test) can reach more than 1000 h, the anti-process material adhesion rate is less than 5%, the coating bonding strength (crosshatch method) can reach 5B level, and completely meets the use requirements of complex dry etching working conditions.

[0076] The present disclosure provides a composite coating for a dry vacuum pump and a preparation method thereof, which has the following beneficial effects compared with the prior art: the composite-coated dry vacuum pump of the present disclosure achieves multiple protection effects through the synergistic effect of multiple coatings. The phosphating treatment layer is used to optimize the substrate and provide a good adhesion base for subsequent coatings. The chemical nickel plating layer serves as the main corrosion-resistant layer to resist the corrosion of corrosive gases. The nano-ceramic sealing layer is used to seal defects, prevent medium penetration, and enhance interlayer bonding. The spray coating can provide excellent non-stickiness to prevent process material adhesion, and also has excellent corrosion resistance. The thickness of each coating is reasonable, the performance is complementary, and the service life of the dry vacuum pump is significantly improved. At the same time, the preparation method provided by the present disclosure has clear process parameters, simple operation, high stability, and is easy to industrialize and popularize.

[0077] It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. Various modifications and improvements can be made by those of ordinary skill in the art without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also considered within the protection scope of the present disclosure.​

Claims

1. A composite coating for a dry vacuum pump, characterized in that, The composite coating comprises a phosphating layer, a chemical nickel plating layer, and a spray coating layer sequentially stacked on the surface of the stator and / or rotor of the dry vacuum pump; wherein... The phosphating layer comprises: 15%~25% zinc dihydrogen phosphate, 5%~10% zinc nitrate, 2%~5% zinc oxide, 0.5%~2% accelerator, and the remainder deionized water.

2. The composite coating according to claim 1, characterized in that, The electroless nickel plating layer comprises: 25%-30% nickel sulfate, 25%-30% sodium hypophosphite, 13%-28% sodium citrate, 10%-20% sodium acetate, 0.01%-0.04% potassium iodate, and the balance being deionized water; The coating material is a PFA coating or a PTFE coating.

3. The composite coating according to claim 1, characterized in that, The thickness of the phosphating layer is 6~8μm; The thickness of the electroless nickel plating layer is 18~22μm; The thickness of the sprayed coating is 18~22μm.

4. The composite coating according to claim 1, characterized in that, The composite coating also includes a sealing layer located between the electroless nickel plating layer and the sprayed coating layer.

5. The composite coating according to claim 4, characterized in that, The thickness of the sealing layer is 3~5μm; The sealing layer comprises: 5%~15% nano-ceramic particles, 20%~30% epoxy resin, 5%~10% curing agent, 10%~20% diluent, and the remainder deionized water.

6. A method for preparing a composite coating for a dry vacuum pump, characterized in that, The preparation method includes: The stator and / or rotor of the dry vacuum pump are pretreated by shot peening, degreasing, first water washing, acid washing and second water washing. The pretreated stator and / or rotor are immersed in a phosphating solution for phosphating treatment to form a phosphating layer. After cleaning the phosphated stator and / or rotor, they are immersed in an electroless nickel plating solution to form an electroless nickel plating layer. Fluoropolymer coating is uniformly sprayed onto the surface of the electroless nickel plating layer and then sintered and dried to form a sprayed layer.

7. The preparation method according to claim 6, characterized in that, The phosphating solution comprises: 15%~25% zinc dihydrogen phosphate, 5%~10% zinc nitrate, 2%~5% zinc oxide, 0.5%~2% accelerator, and the remainder deionized water; The phosphating treatment is performed at a temperature of 40-60°C for 10-20 minutes, and the resulting phosphating layer has a thickness of 6-8 μm.

8. The preparation method according to claim 6, characterized in that, The electroless nickel plating solution comprises: 25%-30% nickel sulfate, 25%-30% sodium hypophosphite, 13%-28% sodium citrate, 10%-20% sodium acetate, 0.01%-0.04% potassium iodate, and the balance being deionized water; The nickel plating process is performed at a temperature of 85-90°C, a pH value of 4.5-5.2, and a time of 60-80 minutes, resulting in a chemically plated nickel layer with a thickness of 18-22 μm.

9. The preparation method according to claim 6, characterized in that, The fluoropolymer coating is a PFA coating or a PTFE coating; The sintering and drying process includes: preheating at 100~120℃ for 10~20 min, then sintering at 380~390℃ for 20~30 min, resulting in a sprayed coating thickness of 18~22 μm.

10. The preparation method according to claim 6, characterized in that, After forming the electroless nickel plating layer, the preparation method further includes: immersing the nickel-plated stator and / or rotor in a sealing agent after drying, allowing it to stand at room temperature, and then curing it to form a sealing layer; wherein, The sealing agent comprises: 5%~15% nano-ceramic particles, 20%~30% epoxy resin, 5%~10% curing agent, 10%~20% diluent, and the remainder deionized water; The dip coating process takes 2-5 minutes, the room temperature standing time is 10-15 minutes, the curing temperature is 100-120℃, the time is 25-35 minutes, and the thickness of the resulting sealing layer is 3-5 μm.

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